tretinoin and Papilloma

A review of recent investigations in the retinoid field is presented. Retinoic acid exerts a prophylactic and a therapeutic effect on chemically induced benign and malignant epithelial tumors in mice. In clinical studies positive therapeutic results have been obtained in patients with preneoplastic and neoplastic epithelial lesions. However, treatment with retinoic acid is limited by serious side effects (hypervitaminosis A syndrome). Therefore, the synthesis of analogs of retinoic acid (retinoids) possessing a more favorable therapeutic ratio has been initiated. Among a large series of synthesized compounds, certain aromatic analogs proved to have a particularly favorable therapeutic ratio. The structure-activity relationship of the most active retinoids is discussed including some biological data concerning prophylaxis and therapy of epithelial tumors. The total synthesis of retinoids according to various building schemes is discussed in detail. Methods for the synthesis of the cyclic end group, of the polyene chain component, and of the full retinoid skeleton are described. Metabolic studies of retinoic acid and of the most active retinoid, as well as the synthesis of some isolated metabolites are outlined. Suggestions concerning the mechanism of action of retinoids are made. Some clinical results on the treatment of acne, psoriasis and precancerous conditions are reported.

Topics: Animals; Carcinoma; Humans; Neoplasms, Experimental; Papilloma; Retinaldehyde; Skin Diseases; Skin Neoplasms; Structure-Activity Relationship; Tretinoin; Vitamin A

Retinoic acid (RA) and its analogues (retinoids) are promising agents in skin cancer prevention following either topical application or oral administration. However, long-term in vivo effects of RA on chemically induced hyperplastic epidermal foci in adult mouse skin have also been described, casting some doubt with regard to its chemopreventive activity.. To characterize chemically induced skin tumours and to investigate the in vivo long-term action and preventive effect of RA on adult mouse skin carcinogenesis.. Fifty-six adult Naval Medical Research Institute mice, exposed (n = 28) or not exposed (n = 28) to RA in utero.. Mice were treated with a standard two-stage skin carcinogenesis protocol, which included an initiating application of 7,12-dimethylbenz(a)anthracene followed by promotion with 12-O-tetradecanoylphorbol 13-acetate.. Retinoic acid administered to pregnant mice showed a long-term inhibitory action on cell differentiation and development of chemically induced tumours on the adult skin of their offspring, as well as a stimulatory effect on cell proliferation and expression of an early marker of malignant progression (keratin 13).. The results suggest that RA exposure in utero confers long-lasting effects on adult mouse skin carcinogenesis. These include chemopreventive activity (reduced number of tumours), as well as enhancement of squamous papilloma progression, which appears to be due to enhanced keratinocyte proliferation and suppression of epidermal maturation. The clinical significance of these findings is not known for other routes of RA administration at this time.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Antineoplastic Agents; Carcinogens; Carcinoma, Squamous Cell; Drug Administration Schedule; Female; Keratoacanthoma; Male; Mice; Papilloma; Pregnancy; Skin Neoplasms; Tetradecanoylphorbol Acetate; Treatment Outcome; Tretinoin

Confluent and reticulate papillomatosis (CRP) is a rare disorder that has mostly been described in case reports and limited case series. Studies on this condition from our region are lacking.. To describe the clinical and histopathological findings, as well as response to treatment of all patients diagnosed with CRP at the American University of Beirut Medical Center (AUB-MC) between 1999 and 2009, and to compare our findings with those published in the literature.. Confluent and reticulate papillomatosis was diagnosed in 10 patients (five men, five women). Mean age at diagnosis was 19 years. Duration of lesions ranged from few months to several years. Skin lesions mainly consisted of reticulated, pigmented macules, patches and plaques. The most common area of involvement was the chest in five cases. The rash was asymptomatic in eight patients. Skin biopsy specimens from all patients revealed hyperkeratosis, papillomatosis and variable acanthosis. Whereas follicular plugging was observed in nine cases, anastomosis of the rete ridges was noted in three. Periodic acid Schiff stains highlighted yeast forms in six cases.. The clinical and histopathological features of the CRP patients in our study are generally comparable to those published in the literature, with minor differences. Clinically, one case had an atypical clinical presentation, and microscopically follicular plugging was seen in the majority of cases. Yeast-like spores were seen in six cases further supporting a role of Malassezia furfur in the pathogenesis of CRP.

Topics: Administration, Oral; Administration, Topical; Adolescent; Adult; Biopsy, Needle; Cohort Studies; Drug Therapy, Combination; Female; Follow-Up Studies; Humans; Immunohistochemistry; Lebanon; Male; Minocycline; Papilloma; Rare Diseases; Retrospective Studies; Skin Neoplasms; Steroids; Treatment Outcome; Tretinoin

Retinoic acid (RA) signalling is essential for epidermal differentiation; however, the mechanisms by which it acts are largely unexplored. Partitioning of RA between different nuclear receptors is regulated by RA-binding proteins. We show that cellular RA-binding proteins CRABP1 and CRABP2 and the fatty acid-binding protein FABP5 are dynamically expressed during skin development and in adult tissue. CRABP1 is expressed in embryonic dermis and in the stroma of skin tumours, but confined to the hair follicle dermal papilla in normal postnatal skin. CRABP2 and FABP5 are expressed in the differentiating cells of sebaceous gland, interfollicular epidermis and hair follicles, with FABP5 being a prominent marker of sebaceous glands and anagen follicle bulbs. All three proteins are upregulated in response to RA treatment or Notch activation and are negatively regulated by Wnt/beta-catenin signalling. Ectopic follicles induced by beta-catenin arise from areas of the sebaceous gland that have lost CRABP2 and FABP5; conversely, inhibition of hair follicle formation by N-terminally truncated Lef1 results in upregulation of CRABP2 and FABP5. Our findings demonstrate that there is dynamic regulation of RA signalling in different regions of the skin and provide evidence for interactions between the RA, beta-catenin and Notch pathways.

Topics: Animals; beta Catenin; Carcinoma, Squamous Cell; Cell Differentiation; Epidermis; Fatty Acid-Binding Proteins; Hair Follicle; Lymphoid Enhancer-Binding Factor 1; Mice; Mice, Transgenic; Neoplasm Proteins; Papilloma; Receptor, Notch1; Receptors, Retinoic Acid; Signal Transduction; Skin; Skin Neoplasms; Stromal Cells; Tretinoin; Up-Regulation

Adult Naval Medical Research Institute (NMRI) mice, after prenatal exposure to retinoic acid (RA), were treated with a standard two-stage skin carcinogenesis regime to characterize hyperplastic epidermal foci that precede the appearance of cutaneous papillomas, and to investigate the in vivo long-term action of RA on adult mouse skin treated with DMBA (7,12 dimethyl benz[a]anthracene) and TPA (12-O-tetradecanoylphorbol 13-acetate). The results demonstrate that RA administered to pregnant mice had a long-term inhibitory action on the cell differentiation and development of hyperplastic lesions occurring prior to cancer on the adult skin of their offspring as well as a stimulatory effect on cell proliferation of these hyperplastic lesions.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Administration, Oral; Animals; Carcinogens; Cell Differentiation; Disease Models, Animal; Female; Keratolytic Agents; Mice; Papilloma; Pregnancy; Prenatal Exposure Delayed Effects; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

Squamous cell carcinoma (SCC) is the most prevalent form of epithelial cancer. SCC results when normal epithelial cells undergo multiple neoplastic changes that culminate in the evolution of an invasive cancer. Retinoids are commonly used as chemopreventive and treatment agents in skin cancer; however, SCC progression is accompanied by a gradual loss of retinoid responsiveness. The synthetic retinoid N-(4-hydroxyphenyl)retinamide (HPR) has shown promising anti-neoplastic activity in a variety of tumor cells, including those that are resistant to all-trans retinoic acid (t-RA). We investigated the effect of HPR on growth and apoptosis of squamous cells at different stages of carcinogenesis. We then determined if retinoic acid receptor (RAR) overexpression affected the outcome of HPR treatment. To model SCC malignant progression, we used a panel of murine keratinocytes representing different stages of squamous cell carcinogenesis. This panel consisted of primary keratinocytes, SP1 and 308 papilloma cell lines, the PAM-212 squamous carcinoma cell line, and the spindle I7 cell line. With the exception of the primary keratinocytes, all cells were unresponsive to t-RA treatment. Pharmacological concentrations of HPR were non-cytotoxic to all keratinocytes tested and HPR sensitivity was stage-dependent, with the papilloma cell lines being the most sensitive, and the spindle cells being the most resistant. Overexpression of RARgamma in SP1 papilloma cells enhanced growth suppression and apoptosis induction by HPR. HPR-induced growth suppression was accompanied by a simultaneous block in the G(1) phase of the cell cycle in RAR-transduced and control SP1 cells and differential regulation of cell cycle and apoptotic mediators.

Topics: Animals; Antineoplastic Agents; Apoptosis; Benzimidazoles; Carcinoma, Squamous Cell; Cell Division; Cell Transformation, Neoplastic; Cells, Cultured; Fenretinide; G1 Phase; Keratinocytes; Mice; Mice, Inbred BALB C; Neoplasm Staging; Nevus, Spindle Cell; Papilloma; Propidium; Receptors, Retinoic Acid; Ribonucleases; Tretinoin

The design of analogues of 7,8-dihydroretinoic acid (7,8-dihydro-RA) was based on reported biological activities of this retinoid and its dihydro-TMMP(1) analogue and on structural hypotheses. 7-Oxa-7,8-dihydroretinoids (5, 6) were prepared by O-alkylation of phenoxides by methyl 8-bromo-3,7-dimethyl-2,4,6-octatrienoate. In some cases, C-alkylation also occurred. 7-Aza-8-oxo-7,8-dihydroretinoids (12, 13) were synthesized from benzeneamines and the acyl cyano or bromo derivative of the monomethyl ester of 3,7-dimethyl-2,4,6-octatriene-1,8-dioic acid. These monomethyl ester precursors were synthesized from the known analogous aldehyde via an O-trimethylsilyl cyanohydrin. 7-(2,3,5-Trimethylphenoxy)-3,5-dimethyl-2,4,6-octatrienoic acid (6b) was the most active of the 7-oxa-7,8-dihydro-RAs in inhibiting DMBA-initiated and TPA-promoted mouse-skin papillomas. The ED(50) was about 4-fold that of etretinate. Two additional 7-oxa-7,8-dihydro-RAs exhibited modest activity in the papilloma assay. Some of the 7-oxa-7,8-dihydro-RAs bind to CRABP and RARalpha.

Topics: Animals; Anticarcinogenic Agents; Fatty Acids, Unsaturated; Mice; Papilloma; Protein Binding; Receptors, Retinoic Acid; Retinoic Acid Receptor alpha; Skin Neoplasms

The construction of transgenic FVB/N mice targeting the PMLRARA fusion gene under the control of a human MRP8 promoter recapitulated the phenotype of acute promyelocytic leukemia but had the unexpected result of multiple squamous papillomas of the skin (Brown et al., PROC: Natl. Acad. Sci. USA, 94:2551-2556, 1997). In addition, transgenic MRP8-PMLRARA mice exhibited a skin phenotype characteristic of vitamin A deficiency. The severity of the skin phenotype and spontaneous papilloma development correlated with the level of transgene expression. Papilloma formation was preceded by follicular hyperplasia and the expression of epidermal differentiation markers in the follicular epithelium. Mutations in the Ha or Ki alleles of ras were not detected in papillomas that developed on transgenic skin, and papilloma formation was accentuated on the C57/Bl6 background, unlike the usual resistance of this strain to skin tumor induction. Analysis of liver extracts from transgenic mice indicated a deficiency in the production of retinoic acid. Furthermore, affected transgenic epidermis had reduced levels of retinoic acid receptoralpha (RARalpha) and retinoic X receptor (RXRalpha), and supplementation with exogenous retinoic acid prevented the skin phenotype. When transgenic keratinocytes were grafted to nude mice, the resulting integument was normal, and conversely, when transgenic bone marrow was grafted to normal mice, a skin phenotype did not develop. Together these results suggest that local interruption of PML and RARalpha signaling in the skin, together with a systemic retinoid deficiency, initiates a tumor induction pathway that is independent of ras activation.

Topics: Animals; Calgranulin A; Cell Differentiation; Diterpenes; Genes, ras; Genetic Predisposition to Disease; Hair Follicle; Humans; Liver; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mutation; Neoplasm Proteins; Oncogene Proteins, Fusion; Papilloma; Promoter Regions, Genetic; Receptors, Retinoic Acid; Retinoic Acid Receptor alpha; Retinoid X Receptors; Retinoids; Retinyl Esters; Skin Neoplasms; Transcription Factors; Transgenes; Tretinoin; Vitamin A

Confluent and reticulate papillomatosis (CRP) of Gougerot and Carteaud is a rare cutaneous disorder characterized by persistent, usually asymptomatic, dark papules and plaques centrally located on the back, intermammary, and epigastric areas. The eruption spreads out peripherally into a fading reticulated pattern. The pathogenesis is poorly understood, but there are several theories. Many different treatments, with varying success rates, have been attempted. We present 3 patients with CRP who had excellent results in the areas treated with topical tretinoin. The only difficulty with therapy is applying the tretinoin to the back, which sometimes necessitates a second person. However, if this situation can be overcome, topical tretinoin provides an effective, safe alternative to systemic therapies. Response to tretinoin provides support that CRP is a disorder of keratinization. Finally, the fact that 2 of the patients were brothers may support the idea that CRP has a hereditary influence.

Topics: Administration, Topical; Adolescent; Adult; Antineoplastic Agents; Humans; Male; Papilloma; Skin Neoplasms; Tretinoin

We recently synthesized several conformationally constrained retinoic acid (RA) analogues [8-(2'-cyclohexen-1'-ylidene)-3, 7-dimethyl-2,4,6-octatrienoic acids with different alkyl substituents at 2' (R1) and 3' (R2) positions on the cyclohexene ring] (Muccio et al. J. Med. Chem. 1996, 39, 3625) as cancer chemopreventive agents. UAB8 (R1 = Et; R2 = iPr), which contains sufficient steric bulk at the terminal end of the polyene chain to mimic the trimethylcyclohexenyl ring of RA, displayed biological properties similar to those of RA. To explore the efficacy of this retinoid in acute promyelocytic leukemia (APL) and juvenile myelomonocytic leukemia (JMML), we evaluated UAB8 isomers in in vitro assays which measure the capacity of retinoids to inhibit aberrant myeloid colony growth from blood or bone marrow cells obtained from human JMML patients and in assays measuring the potential of retinoids to differentiate NB4 cells (an APL cell line). Both (all-E)- and (13Z)-UAB8 were 2-fold more active than RA in the NB4 cell differentiation assay; however, only (all-E)-UAB8 had comparable activity to the natural retinoids in the JMML cell assays. These results were compared to the biological effectiveness of a new retinoid, UAB30 [8-(3', 4'-dihydro-1'(2'H)-naphthalen-1'-ylidene)-3,7-dimethyl-2,4, 6-octatrienoic acid], which had different nuclear receptor binding and transactivational properties than UAB8. Relative to (all-E)-RA and (all-E)-UAB8, (all-E)-UAB30 bound well to RARalpha but did not activate transcription-mediated RARalpha homodimers, even though it was effective in RARbeta- and RARgamma-mediated transactivational assays. In APL assays, this retinoid had much reduced activity and was only moderately effective in JMML assays and in cancer chemoprevention assays.

Topics: Animals; Antineoplastic Agents; Cell Line; Chickens; Child; Fatty Acids, Unsaturated; HL-60 Cells; Humans; In Vitro Techniques; Leukemia, Myelomonocytic, Chronic; Leukemia, Promyelocytic, Acute; Mice; Molecular Conformation; Naphthalenes; Papilloma; Radioligand Assay; Receptors, Retinoic Acid; Skin; Skin Neoplasms; Stereoisomerism; Transcription, Genetic; Tretinoin; Tumor Stem Cell Assay

Retinoic acid (RA) was topically applied to the skin of Sencar mice during the promotion phase of specific tumor induction protocols that produce papillomas at low (12-O-tetradecanoylphorbol-13-acetate promoted, TPA) or high (mezerein-promoted) risk for premalignant progression and malignant conversion. RA consistently reduced the yield of papillomas and carcinomas in both protocols, but the frequency of malignant conversion in papillomas that emerged during RA treatment was not reduced. When TPA was reapplied after cessation of RA treatment, the number of papillomas increased 2-fold, suggesting that RA had not eliminated initiated cells. In vitro, RA prevented the emergence of transformed keratinocytes in an assay that mimics malignant conversion, suggesting that RA can suppress conversion if applied during the stage of premalignant progression. Examination of tumor markers at weeks 14 and 22 of the tumor-induction experiments in vivo indicated that papillomas evolving during RA treatment exhibited a phenotype of high progression risk, even in the TPA-promoted groups. In the majority of these tumors, the alpha6beta4 integrin and retinoid X receptor alpha transcripts were detected suprabasally, indicating an advanced state of premalignant progression. RA-treated tumors also expressed higher levels of transcripts for transforming growth factor (TGF)-beta1 and localized TGF-beta1 peptide in the basal portions of the tumor fronds. Because up-regulated expression of TGF-beta1 suppresses papilloma formation, these studies suggest a mechanism whereby RA can prevent papilloma eruption via a TGF-beta intermediate, but papillomas resistant to RA may have altered TGF-beta signaling and progress to carcinomas at an increased frequency.

Topics: Administration, Topical; Animals; Anticarcinogenic Agents; Antineoplastic Agents; Biomarkers, Tumor; Carcinogens; Carcinoma, Basal Cell; Cell Transformation, Neoplastic; Disease Progression; Diterpenes; Female; Immunohistochemistry; Mice; Mice, Inbred BALB C; Mice, Inbred SENCAR; Papilloma; Phenotype; Precancerous Conditions; Receptors, Retinoic Acid; Retinoid X Receptors; Risk Factors; Skin Neoplasms; Terpenes; Tetradecanoylphorbol Acetate; Transcription Factors; Transforming Growth Factor beta; Tretinoin

Retinoic acid is one of the most promising drugs for chemotherapy and chemoprevention of cancer. Either blocking activator protein-1 (AP-1) activity or activating retinoic acid response element (RARE) have been proposed to be responsible for its antitumor activity. However, evidence for this hypothesis is lacking in vivo studies. To address this issue, we used an AP-1-luciferase transgenic mouse as a carcinogenesis model and new synthetic retinoids that are either selective inhibitors of AP-1 activation or selective activators of the RARE. The results showed that the SR11302, an AP-1 inhibition-specific retinoid, and other AP-1 inhibitors such as trans-retinoic acid and fluocinolone acetonide, markedly inhibit both 12-O-tetradecanoylphorbol-13-acetate-induced papilloma formation and AP-1 activation in 7,12-dimethyl benz(a)anthracene-initiated mouse skin (P < 0.05). In contrast, repeated applications of SR11235, a retinoid with RARE transactivating activity, but devoid of AP-1 inhibiting effect, did not cause significant inhibition of papilloma formation and AP-1 activation (P > 0.05). These results provide the first in vivo evidence that the antitumor effect of retinoids is mediated by blocking AP-1 activity, but not by activation of RARE.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Anticarcinogenic Agents; Carcinogens; Female; Fluocinolone Acetonide; Luciferases; Male; Mice; Mice, Transgenic; Papilloma; Recombinant Fusion Proteins; Regulatory Sequences, Nucleic Acid; Retinoids; Skin Neoplasms; Tetradecanoylphorbol Acetate; Transcription Factor AP-1; Transcriptional Activation; Tretinoin

The retinoic acid (RA) signaling pathway was investigated by transient transfection of a chloramphenicol acetyltransferase (CAT) reporter gene construct containing the RA response element (RARE) of the murine (m) RARbeta2 gene into murine primary epidermal keratinocytes (PEK), papilloma-derived SP1 cells, and carcinoma-derived 3P2 cells. Murine PEK transfected in a low-Ca2+ medium (0.05 mM Ca2+) exhibited a strong transactivation of the CATgene after exposure of the cells to 0.1 microM RA. Transactivation of the CATgene could, however, also be achieved by shifting RAREbeta2-transfected low-Ca2+ PEK to high-Ca2+ conditions (0.15-1.2 mM Ca2+). Concomitantly, the Ca2+ raise also led to the induction of both cellular retinol (ROL)-binding protein I (CRBPI) and cellular RA-binding protein II (CRABPII), whereas expression of cellular RA-binding protein I (CRABPI) was not observed. Moreover, induction of in vitro differentiation also activated the ROL-->RA converting enzyme system in PEK. These findings suggest the following sequence of events involved in the high Ca2+-mediated activation of RAREbeta2. First, high Ca2+ induces the synthesis of mCRBPI, which binds ROL released from retinyl ester stores and makes it accessible to the ROL-RA converting enzyme system. Enzymatically generated RA is taken over by mCRABPII and transported to the nucleus, where it acts as ligand for nuclear receptors, which complex with RAREbeta2 to activate the reporter gene. This hypothetical cascade of RA signaling was supported by our findings that inhibition of the ROL-->RA converting enzyme system by citral abolished the Ca2+-mediated transactivation of the CAT gene in a nontoxic manner. Studies in transformed murine cell lines revealed that Ca2+-induced activation of RAREbeta2 was essentially maintained in papilloma-derived SP1 cells, although all parameters of the Ca2+-dependent RAREbeta2 activation cascade were induced to a much lower extent. In contrast, strong RAREbeta2 activity was already observed in low-Ca2+ carcinoma-derived 3P2 cells. Low-Ca2+ 3P2 cells also expressed high levels of both mCRBPI and mCRABPII and possessed a highly active ROL-->RA converting enzyme system. Again, inhibition of the enzyme by citral abolished RAREbeta2 activity in low-Ca2+ 3P2 cells. Our data show that Ca2+-induced differentiation in cultured murine PEK entails a series of events that ultimately lead to the activation of RARE-containing genes. These properties are maintained in transformed e

Topics: Animals; Calcium; Carcinoma; Cell Differentiation; Chloramphenicol O-Acetyltransferase; Genes, Reporter; Keratinocytes; Mice; Mice, Inbred Strains; Papilloma; Receptors, Retinoic Acid; Signal Transduction; Skin; Skin Neoplasms; Skin Physiological Phenomena; Transcriptional Activation; Transfection; Tretinoin; Vitamin A

We recently demonstrated that conformationally defined 6-s-trans-retinoic acid (RA) analogs were effective in the prevention of skin papillomas (Vaezi et al. J. Med. Chem. 1994, 37, 4499-4507) and selective agonists for nuclear receptor binding and activation (Alam et al. J. Med. Chem. 1995, 38, 2302-2310). In order to probe important structure-activity relationships, we evaluated a homologous series of four 6-s-trans-retinoids that are 8-(2'-cyclohexen-1'-ylidene)-3,7-dimethyl-2,4,6-octatrienoic acids with different substituents at 2' (R2) and 3' (R1) positions on the cyclohexene ring. UAB1 (R1 = R2 = H), UAB4 (R1 = R2 = Me), UAB7 (R1 = Me, R2 = iPr), and UAB8 (R1 = Et, R2 = iPr) contain alkyl R groups that mimic, to different extents, portions of the trimethylcyclohexenyl ring of RA. Both 9Z- and all-E-isomers of these retinoids were evaluated in binding assays for cellular retinoic acid-binding proteins (CRABP-I and CRABP-II), a nuclear retinoic acid receptor (RAR alpha), and a nuclear retinoid X receptor (RXR alpha). The all-E-isomers of UAB retinoids bound tightly to CRABPs and RAR alpha, the binding affinity of the all-E-isomer increased systematically from UAB1 to UAB8, and binding for the latter was comparable to that of all-E-RA. In contrast to RA, the (9Z)-UAB retinoids were at least 200-fold less active than the all-E-isomers in binding to RAR alpha. The (9Z)-UAB isomers exhibited increasingly stronger binding to RXR alpha, and (9Z)-UAB8 was nearly as effective as (9Z)-RA in binding affinity. The retinoids were also evaluated in gene expression assays mediated by RAR alpha and RXR alpha homodimers or RAR alpha/RXR alpha heterodimers. Consistent with the binding affinities, the (all-E)-UAB retinoids activated gene transciption mediated by RAR alpha homodimers or RAR alpha/RXR alpha heterodimers, while the (9Z)-UAB isomers activated only the RXR alpha homodimer-mediated transcription. The all-E- and 9Z-isomers of the UAB retinoids were further evaluated for their capacity to prevent the induction of mouse skin papillomas. When compared to RA, only the (all-E)-UAB retinoids containing bulky R1 and R2 groups were effective in this chemoprevention assay. (9Z)-RA displayed equal capacity as RA to prevent papillomas, while the 9Z-isomers of the UAB retinoids were much less effective. Taken together, these studies demonstrate that the cyclohexenyl ring substituents of 6-s-trans-UAB retinoids are important for their biological activities and that the ch

Topics: Animals; Anticarcinogenic Agents; Cell Nucleus; Mice; Models, Molecular; Molecular Conformation; Molecular Structure; Papilloma; Receptors, Retinoic Acid; Retinoid X Receptors; Retinoids; Skin Neoplasms; Stereoisomerism; Structure-Activity Relationship; Thermodynamics; Transcription Factors; Transcription, Genetic

Topics: Adolescent; Adult; Female; Humans; Hypersensitivity, Immediate; Male; Papilloma; Skin Neoplasms; Tretinoin; Urea

In the two-stage protocol of skin carcinogenesis, the carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) is applied to the skin of mice at around seven weeks of age. We previously performed DMBA initiation at three weeks of age to study the effect of pharmacological (30 micrograms/g diet) dietary retinoic acid (RA) on skin carcinogenesis. In this study we asked whether dietary pharmacological RA is equally effective against skin carcinogenesis when mice are initiated with (DMBA) at 7 weeks of age and then subjected to weekly applications of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) or mezerein (MEZ) for 20 weeks. Similar to the three-week initiation protocol, high dietary RA inhibited papilloma incidence and yield in MEZ- but not in TPA-promoted female SENCAR mice. In addition, carcinoma incidence and yield were decreased by high dietary RA in TPA- as well as MEZ-treated mice. These data demonstrate that the high dietary RA diet is as effective in inhibiting papilloma and carcinoma formation when the DMBA is applied at seven weeks of age as at three weeks.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Aging; Animals; Antineoplastic Agents; Carcinogens; Diet; Diterpenes; Female; Mice; Papilloma; Skin Neoplasms; Terpenes; Tetradecanoylphorbol Acetate; Tretinoin

(2E, 4E, 6E)-8-[3'-Ethyl-2'-(1-methylethyl)-2'-cyclohexen-1'-ylidene] -3, 7-dimethyl-2,4,6-octatrienoic acid (UAB-8) has potent activity in preventing papillomas on the skin of mice similar to that determined in a previous study for the homolog containing one less carbon atom. To evaluate the toxicological profile for UAB-8, relative to all-trans-retinoic acid (RA), female mice were dosed by oral gavage for 29 days with amounts of 0.05, 0.1, or 0.2 mmol/kg/day. For the two compounds, the effects on body weights were similar. Mice dosed with UAB-8, however, had a lower incidence of clinical signs of toxicity (alopecia, scaly skin, and limping). At necropsy, bone fractures, skin abnormalities, and splenomegaly were observed in some mice dosed with RA but not in any dosed with UAB-8. Lymph node hyperplasia was noted in some mice dosed with either dose of RA but only in those dosed with the highest dose of UAB-8. All dose levels of RA produced microscopic lesions in the bones of mice; only the highest dose of UAB-8 had this effect. RA and UAB-8 had similar effects on chondrogenesis in cultures of cells from mouse limb buds, an indication of comparable teratogenic effects. For mice dosed i.v. (10 mg/kg), there was a saturated phase of elimination of RA from plasma (Km = 0.61 microgram/ml and Vmax = 2572 micrograms/hr); no such phase was noted when UAB-8 was administered. UAB-8 had values for t1/2 alpha and t1/2 beta of 0.47 and 17.1 hr, respectively. Relative to RA, UAB-8 has a favorable toxicological profile and different pharmacokinetics.

Topics: Animals; Body Weight; Calcification, Physiologic; Erythrocyte Count; Female; Hematocrit; Hemoglobins; Keratolytic Agents; Limb Buds; Lymph Nodes; Mice; Papilloma; Skin; Skin Neoplasms; Tretinoin

Using mouse skin papilloma as a model system, we examined whether the antitumorigenic activity of carotenoids was related to their provitamin A activity. Oral administration of canthaxanthin (CX) or beta-carotene at 200 mg/kg/day for 14 days significantly reduced the cumulative size of papillomas induced on the skin by 9,10-dimethyl-1,2-benzanthracene (p < 0.05), after the accumulation of these carotenoids in the tumors. The levels of a protooncogene, c-myc, were simultaneously suppressed in papillomas in carotenoid-treated mice. Because CX cannot be converted metabolically to retinoids, these results suggested that CX directly inhibited the growth of papillomas. Neither the accumulation of retinoids nor the expression of a retinoic acid-inducible gene, retinoic acid receptor-beta, was found in papillomas of CX- and beta-carotene-treated mice, suggesting that, like CX, beta-carotene might exert the tumor-suppressing effect without being converted to retinoids. Thus a certain antitumorigenic activity of carotenoids appears not necessarily to require their provitamin A activity.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; beta Carotene; Canthaxanthin; Female; Gene Expression; Mice; Papilloma; Proto-Oncogene Proteins c-myc; Receptors, Retinoic Acid; RNA, Messenger; Skin Neoplasms; Tretinoin

Many studies have shown that all trans retinoic acid (RA) exhibits significant protective effects against mouse skin tumor promotion and spontaneous as well as enhanced malignant conversion. In a recently completed study, we showed that under treatments in which papillomas on SENCAR mouse skin are induced at low and high probabilities to convert to malignant carcinomas, RA affords significant protection against both tumor promotion and subsequent malignant conversion. More than 95% of these mouse skin papillomas and carcinomas have been shown to contain point mutation at the 61 codon of Ha-ras oncogene. The ras oncogene encodes a p21 protein that, in its mutated form, transforms mammalian cells only when p21 is at the inner surface of the plasma membrane, by a series of enzymatic reactions in which the initial step is catalyzed by farnesyltransferase (FTase). In this study, we assessed whether the protective effect of RA against malignant conversion involves the inhibition of ras p21 processing in those tumors that contain the activated ras oncogene. The FTase activity and the levels of cytosolic and membrane-bound Ha-ras p21 were determined in all papillomas and carcinomas obtained from acetone- or RA-treated animals. No matter how the data were analyzed and what comparisons were considered, in all the protocols used, compared with controls, papillomas and carcinomas obtained from RA-treated groups showed significantly decreased (P < 0.01-0.001) FTase activity. Furthermore, the tissue samples from RA-treated groups in different protocols also showed significantly diminished membrane localization of Ha-ras p21, with a concomitant increase in cytosolic Ha-ras p21 levels. The analysis of these data also showed that in all the protocols used, the increased FTase activity and membrane localization of Ha-ras p21 were associated with the induction of papillomas and their subsequent malignant conversion to squamous cell carcinomas. Taken together, these results indicate a strong correlation between the inhibition of ras p21 farnesylation because of a decrease in FTase activity by RA and its protective effect against malignant conversion of papillomas to carcinomas. Based on the results of this study, it is tempting to suggest that clinical trials evaluating the preventive or therapeutic potential of retinoids may be directed more toward those clinical malignancies that are known to contain the activated ras oncogene.

Topics: Alkyl and Aryl Transferases; Animals; Carcinoma; Cell Compartmentation; Cell Membrane; Cell Transformation, Neoplastic; Cytosol; Diterpenes; Enzyme Inhibitors; Mice; Papilloma; Proto-Oncogene Proteins p21(ras); Skin; Skin Neoplasms; Terpenes; Tetradecanoylphorbol Acetate; Transferases; Tretinoin

Mirex, a halogenated hydrocarbon, is a potent skin tumor promoter in 7,12-dimethylbenz[a]anthracene (DMBA)-initiated mouse skin. In the present study retinoic acid (RA) and fluocinolone acetonide (FA), classical inhibitors of phorbol ester- and non-phorbol ester-type skin tumor promoters, were examined for their ability to inhibit mirex tumor promotion. Female CD-1 mice were initiated with 200 nmol DMBA and promoted with equipotent promoting doses of either 5 nmol 12-O-tetradecanoylphorbol-13-acetate (TPA) or 200 nmol mirex twice weekly for 25 weeks and RA (2(1 or 5 nmol), FA (0.5 or 2 nmol) or acetone were applied 30 min prior to each TPA or mirex dose. TPA-promoted papilloma formation was strongly inhibited by > 70% with both doses of RA and by > 90% with both doses of FA. In contrast, mirex-promoted papilloma formation was not inhibited by either dose of RA or 0.5 nmol FA and 2 nmol FA weakly inhibited mirex-promoted papillomas by only 32%. TPA- and mirex-promoted papillomas that were refractory to RA and FA demonstrated the same incidence of Ha-ras mutation as TPA- or mirex-promoted papillomas without RA and FA treatment, further indicating that the inhibitory activity of RA and FA is promoter-dependent and not solely dependent on mutant Ha-ras. FA (2 nmol) treatment completely abolished TPA-induced epidermal hyperplasia and proliferating cell nuclear antigen (PCNA) S phase-positive cells, however, FA had no inhibitory effect on the weak proliferative response induced by mirex. Collectively, these results indicate that the promotional activity of mirex, as well as its weak proliferative response, result from a distinct promoter mechanism and/or that mirex promotes a unique population of epidermal cells that are insensitive to FA and RA and cannot be distinguished by their mutant Ha-ras genotype.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Anticarcinogenic Agents; Base Sequence; Carcinogens; Cell Division; Drug Interactions; Ear, External; Edema; Female; Fluocinolone Acetonide; Genes, ras; Genotype; Mice; Mice, Inbred Strains; Mirex; Molecular Sequence Data; Papilloma; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

We studied the effect of dietary retinoic acid (RA) in a two-stage protocol of skin carcinogenesis in female SENCAR mice. At 3 weeks of age mice were initiated with 7,12-dimethylbenz[a]anthracene (DMBA, 20 micrograms) and promoted with either 12-O-tetradecanoylphorbol-13-acetate (TPA, 2 micrograms) once per week or mezerein (MEZ, 4 micrograms) twice per week for 20 weeks. At the week of DMBA initiation mice were also put on a purified diet containing either 3 (physiological dose) or 30 micrograms (pharmacological dose) of RA/g of diet. High dietary RA significantly inhibited papilloma yield but not incidence in the MEZ-promoted group. Papilloma incidence and yield were also lower in the MEZ- than in the TPA-treated groups. Cumulative carcinoma incidence and yield, and conversion efficiency (= (carcinomas/maximal papillomas) x 100%), were all decreased by high dietary RA in both MEZ- and TPA-treated groups. These results demonstrate that high dietary RA inhibited skin carcinogenesis in MEZ-promoted mice at the stages of tumor promotion and malignant conversion, while this inhibition occurred only at the malignant conversion stage in TPA-promoted mice.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinogens; Carcinoma; Diet; Diterpenes; Female; Mice; Mice, Inbred SENCAR; Papilloma; Skin Neoplasms; Terpenes; Tretinoin

The introduction of substituents at position 3 of methyl 4-oxoretinoate can be effected in good yields by alkylating the lithium dienolate. A second substituent can be introduced also, but the resulting 3,3-disubstituted-4-oxoretinoates were isolated in lower yields. Evidence was obtained for a slower rate of alkylation at the alpha-position (carbon 14) of the ester group. Some of these 4-oxoretinoic acid analogues showed high activity in assays in vivo for the inhibition of ornithine decarboxylase activity and carcinogen-induced papillomas in mouse skin.

Topics: Alkylation; Animals; Anticarcinogenic Agents; Cricetinae; Drug Stability; Enzyme Induction; Female; Magnetic Resonance Spectroscopy; Mice; Mice, Inbred Strains; Ornithine Decarboxylase; Papilloma; Skin; Skin Neoplasms; Structure-Activity Relationship; Tetradecanoylphorbol Acetate; Tretinoin

Using 7,12-dimethylbenz[a]anthracene as the initiator and 12-O-tetradecanoyl-13-acetate as the tumor promoter on the dorsal skin of Sencar mice, we previously showed that pharmacological dietary all-trans-retinoic acid and beta-carotene inhibit the conversion of papillomas to carcinomas in a two-stage system of chemical carcinogenesis. The purpose of this study was to determine the influence of dietary retinoic acid and beta-carotene on retinoid and beta-carotene concentrations in skin and other tissues. We were unable to measure tissue retinoic acid because of the relatively limited amount of tissue available for analysis and the fast rate of metabolism. Different dietary levels of retinoic acid or beta-carotene did not influence total retinol of skin, papilloma, and carcinoma tissues, which all showed a concentration of approximately 1 +/- 0.5 microgram/g wet wt. Equally refractory to dietary retinoic acid or beta-carotene was serum retinol concentration. In contrast, dietary retinoic acid protected loss of liver retinol and retinyl palmitate, and beta-carotene caused an increase in beta-carotene and retinyl palmitate in liver but did not affect serum and liver retinol. We further investigated metabolic and functional aspects of retinoic acid in cultured mouse epidermal keratinocytes (LC-8 cells) and found that these cells actively metabolized [10,11-14C]retinoic acid to polar compounds. Isomers of retinoic acid were a minor product in the presence of cells and the major product when incubated in serum-containing medium in the absence of cells. From the functional point of view, exposure of LC-8 cells to 3 x 10(-6) M all-trans-retinoic acid (RA) caused a 75-fold induction in tissue transglutaminase and an approximately 9-fold induction in 10(-6) M RA at three days of culture. We conclude that retinoic acid spares endogenous retinol and that beta-carotene greatly enhances liver retinyl palmitate levels. Moreover we show that although mouse epidermal cells metabolize retinoic acid at a very high rate, they respond functionally by induction of tissue transglutaminase activity. Because this enzyme has been suggested to be involved in programmed cell death, we are presently investigating the possibility that it may be involved in the inhibition of carcinogenesis in mice fed pharmacological doses of RA.

Topics: Animals; beta Carotene; Carcinoma; Carotenoids; Cell Division; Chromatography, High Pressure Liquid; Diet; Female; Keratinocytes; Liver; Mice; Mice, Inbred BALB C; Mice, Inbred Strains; Papilloma; Skin; Skin Neoplasms; Transglutaminases; Tretinoin; Tumor Cells, Cultured; Vitamin A

We have previously reported that high dietary retinoic acid (RA; 30 micrograms/g diet) inhibits carcinoma formation in a two-stage skin carcinogenesis protocol, using 7,12-dimethylbenz[a]anthracene (DMBA) as the initiator and 12-O-tetradecanoyl phorbol-13-acetate (TPA) as the tumor-promoter in female SENCAR mice. We next asked whether switching the diets from high to control levels of RA and vice versa would influence carcinoma formation. Mice at 3 weeks of age were initiated with DMBA (20 micrograms) once, followed by 20 weekly applications of TPA (2 micrograms). At 3 weeks of age mice were weaned onto a diet containing either 3 (control) or 30 (high) micrograms RA/g diet. Half of the mice from either dietary group were switched to the other diet at 20 weeks of age, when papilloma formation was at its peak. These four groups are designated RA 3 micrograms, RA 30 micrograms, RA 3/30 micrograms and RA 30/3 micrograms groups. As previously found, papilloma formation (including incidence and yield) was not significantly affected by dietary treatment. However, high dietary RA inhibited carcinoma formation; specifically cumulative carcinoma incidence (18.5-23.1% versus 50%) and yield (0.19-0.23 versus 0.68) were significantly lower (P < 0.05) in the high dietary RA treatment groups than the RA 3 micrograms control group, as was the carcinoma conversion efficiency (2.1-3.8% versus 9.4%). The beneficial effect on carcinoma formation was still evident when excess RA was given late during the carcinogenesis process (i.e. the RA 3/30 micrograms group). Moreover, a residual effect of excess RA was also seen after the dietary RA was switched to the control level at 20 weeks of age, when papilloma yield was highest (i.e. the RA 30/3 micrograms group). It is therefore concluded that the chemopreventive effect of high dietary RA on skin carcinogenesis induced by a two-stage carcinogenesis protocol with DMBA and TPA resides mainly at the step of conversion from benign papillomas to malignant carcinomas.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Anticarcinogenic Agents; Dose-Response Relationship, Drug; Female; Male; Mice; Mice, Inbred SENCAR; Papilloma; Pregnancy; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

Previously, we have shown that dietary retinoic acid (RA) at pharmacological doses (30 micrograms/g of diet) inhibited the malignant conversion of skin papillomas to carcinomas induced by a two-stage carcinogenesis protocol with 7,12-dimethylbenz[a]anthracene as initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as promoter (De Luca et al., Carcinogenesis, 14 (1993) 539-542). The purpose of this study was to determine the effect of dietary RA on skin papilloma and carcinoma formation induced by a complete carcinogenesis protocol with repeated DMBA treatment in female Sencar mice. Mice at 3 weeks of age were weaned onto a diet containing either 3 (control) or 30 (excess) micrograms of RA/g of diet and treated topically with DMBA (25.5 micrograms) once per week for 20 weeks. Mice fed excess dietary RA did not significantly differ from control mice in the following parameters: body weight, survival rate, papilloma incidence, cumulative carcinoma incidence (19.4% versus 23.7%), carcinoma yield (0.19 versus 0.26 per mouse), carcinoma conversion efficiency (5.2% versus 3.9%), and average age of carcinoma development (22.7 +/- 4.7 versus 23.3 +/- 2.8 weeks). However, papilloma yield was decreased by about 50% (i.e. 3.7 versus 7.0 at week 20, P < 0.01) between weeks 17 and 22 of age by excess dietary RA treatment. Contrary to other routes of administration (i.e. topical and systemic) of RA (Verma et al., Cancer Res., 42 (1982) 3519-3525), excess dietary RA did not enhance skin tumor formation. In addition, excess dietary RA failed to inhibit malignant conversion of papillomas to carcinomas in the complete carcinogenesis protocol. Thus, the modulation of RA on skin papilloma and carcinoma formation is dependent on carcinogenesis protocol and route of RA administration.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinoma; Diet; Female; Mice; Papilloma; Skin Neoplasms; Tretinoin

The long-term effects of butylated hydroxyanisole (BHA), in combination with various other chemicals on the development of forestomach lesions in rats were investigated. BHA is a synthetic antioxidant, and the other agents included the glutathione-depleting agent diethylmaleate (DEM), the anti-inflammatory drugs indomethacin (IM), dexamethazone (DEX), 6-aminocaproic acetate (6-ACA) and FOY (gabexate mesilate), and the vitamin all-trans-retinol acetate (RA). Concurrent treatment with BHA (1% in diet) and DEM, IM, DEX or FOY for 52 weeks inhibited development of forestomach epithelial hyperplasia as compared to BHA alone, while simultaneous treatment with RA enhanced hyperplastic development. However, the inhibition by DEX or FOY was only partial and in the DEX case, in particular, might have been due to weight loss. Since the most effective inhibitory influence on BHA-induced forestomach lesions exerted in this 1-year experiment was by DEM, a further 2-year experiment was conducted to confirm whether DEM actually can exert inhibitory effects on BHA (2% in diet)-induced forestomach carcinogenesis. The results demonstrated that induction of forestomach hyperplasias and papillomas by BHA was significantly reduced by combination treatment with DEM. Both multiplicity and incidence of forestomach papillomas were significantly decreased, while squamous cell carcinoma development showed a tendency for decrease only.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Butylated Hydroxyanisole; Dexamethasone; Drug Antagonism; Hyperplasia; Male; Maleates; Papilloma; Rats; Rats, Inbred F344; Stomach; Stomach Neoplasms; Tretinoin

Previously we have shown that dietary retinoids are essential for papilloma formation induced by either an initiation-promotion or a complete skin carcinogenesis protocol. The present study was conducted to further determine the effect of dietary retinoic acid (RA) on papilloma formation and the conversion of papillomas to carcinomas. Skin tumors were induced in 3 week old female SENCAR mice by an initiation-promotion protocol with one application of 20 micrograms of 7,12-dimethylbenz[a]anthracene (DMBA), followed by 20 weekly applications of 2 micrograms of 12-O-tetradecanoylphorbol-13-acetate (TPA). Mice were fed RA at one of the three doses: 0.3 (nutritionally marginal dose), 3 (near physiological) and 30 (pharmacological) micrograms/g of diet. Mice fed 30 micrograms of RA/g of diet had the same survival rate as the other two groups despite a lower body weight and all three groups had similar papilloma incidence, which reached 100% at age 18 weeks. Mice fed 3 micrograms of RA/g of diet had the highest papilloma yield (approximately 14 papillomas/mouse) of all groups and it peaked between weeks 18 and 38 of age. These papillomas later regressed such that mice from all three groups had about the same papilloma yield at week 44 of age. Mice fed 30 micrograms of RA/g of diet failed to develop any visible carcinoma, while mice fed 0.3 or 3 micrograms/g showed 1.9% conversion of papillomas to carcinomas. Therefore, dietary RA at 30 micrograms/g of diet inhibited the conversion of papillomas to carcinomas without affecting papilloma incidence. In addition, dietary RA at 30 and 0.3 micrograms/g of diet lowered papilloma yield.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinoma; Diet; Female; Mice; Papilloma; Skin Neoplasms; Tretinoin

The inhibitory effect of retinoic acid (RA) on 12-O-tetradecanoylphorbol-13-acetate- (TPA) induced mouse skin tumors was studied. Two subpopulations of tumors, small (< 2 mm) and large (> or = 2 mm) appeared after 12 weeks of cutaneous promotion by TPA (10 nmol), following initiation by application of 2 x 100 nmol of 7,12-dimethylbenz[a]anthracene (DMBA) to the skin. RA in the doses of 17 and 34 nmol, prior to each TPA treatment inhibited (P < 0.05) the formation of small tumors at 12 weeks of promotion. However, RA in either dose did not inhibit the formation of large (> or = 2 mm) tumors. Ten weeks following withdrawal of all treatments, the number of large tumors persisted in a significantly (P < 0.05) higher number as compared to small tumors in all groups. Our results provide evidence for the existence of tumor subpopulations with a differential response to RA. In addition, elevated levels of metallothionein (MT) expression were demonstrated in papillomas induced by TPA, 72 h after the last TPA treatment. Comparing papillomas treated with RA prior to each TPA treatment and papillomas treated with TPA only, demonstrated that the elevated MT expression in papillomas was unaffected by RA. This indicated that RA did not affect the expression of a protein that showed elevated level in TPA-induced papillomas.

Topics: Animals; Female; Metallothionein; Mice; Mice, Inbred Strains; Papilloma; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

We have defined conditions permitting the in vitro growth of human laryngeal papilloma cells at the air-liquid interface. Using this model system, retinoic acid has been found to modulate the differentiation of human laryngeal papilloma cells along two different pathways. At low concentrations of retinoic acid [10(-9) mol/L and 10(-8) mol/L], the cells formed a stratified squamous epithelium with a differentiation-specific protein staining pattern identical to that found in vivo. At higher concentrations of retinoic acid [10(-7) mol/L and 10(-6) mol/L], the cells differentiated into a columnar epithelium with occasional ciliated cells, lacking the markers of squamous differentiation. Analysis of the human papillomavirus DNA content revealed that as the concentration of retinoic acid increased, the viral DNA content decreased. This system is proposed as a model to further investigate the differentiation defects of human laryngeal papilloma cells and the regulatory role of retinoic acid in the clinical expression of human laryngeal papillomatosis.

Topics: DNA, Viral; Dose-Response Relationship, Drug; Epithelial Cells; Humans; In Vitro Techniques; Laryngeal Neoplasms; Papilloma; Papillomaviridae; Tretinoin; Tumor Cells, Cultured

It is becoming increasingly clear that cutaneous carcinogenesis in murine skin is a stepwise process comprising of initiation, promotion and progression. Most of the papillomas induced by an initiation-promotion protocol regress, while a few of them progress to malignant carcinomas. Progression of benign tumors into malignant cancer is critical since the latter lesions are capable of metastatic spread and eventual death. Inhibitors of the conversion process are therefore likely to be useful as cancer chemopreventive agents. All-trans retinoic acid (RA) is a known regulator of cellular proliferation and differentiation, and a known inhibitor of tumor promotion in murine skin. In this study we assessed the effect of topical application of RA on conversion of benign skin papillomas to malignant carcinomas. Papillomas were induced in SENCAR mice by topical application of 7,12-dimethylbenz[a]anthracene (DMBA) as tumor initiator followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) as tumor promoter. In SKH-1 hairless mice papillomas were induced by thrice weekly exposure to ultraviolet B (UVB) radiation. At 18 (DMBA/TPA group) and 25 (UVB group) weeks papilloma yield stabilized and no new tumors developed. Beginning at the 20th week (DMBA/TPA group) and at the 27th week (UVB group), malignant conversion was achieved by twice weekly topical application of TPA or free radical-generating compounds benzoyl peroxide (BPO), 2,2-azobis(2-amidinopropane) (ABP) and tert-butyl peroxybenzoate (BPB). Application of RA (10 micrograms/animal) 1 h prior to skin application of TPA, BPO, ABP or BPB afforded significant protection (up to 70%) only against malignant conversion mediated by free radical-generating compounds in both chemically induced and UVB-induced benign skin papillomas. On the other hand, preapplication of RA was less effective in the suppression of spontaneous malignant conversion in vehicle-treated animals. These results suggest that, in addition to their anti-tumor promoting effects, retinoids may also act as anti-carcinogens by inhibiting the process of malignant conversion induced by free radical-generating compounds.

Topics: Animals; Carcinoma; Female; Mice; Neoplasms, Radiation-Induced; Papilloma; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Time Factors; Tretinoin; Ultraviolet Rays

Tumor-promoting or antipromoting agents potentially may act directly on initiated squamous epithelial cells or indirectly through effects on normal keratinocytes or immune cells. The purpose of this study was to examine direct effects by comparing in vitro and in vivo treatment of initiated cell populations with 12-O-tetradecanoylphorbol-13-acetate (TPA) or retinoic acid. Keratinocytes were initiated by treatment in vitro with 7,12-dimethylbenz[alpha]anthracene. Replicate cultures of a cloned initiated cell line were exposed to TPA or retinoic acid with acetone as control. After an equivalent number of population doublings, cultured cell sheets were transplanted as skin grafts to athymic nude mice. Replicate grafts from each in vitro treatment group were then treated with TPA or retinoic acid for 8 months. Promotion was quantified by tumor incidence (graft sites with tumor per total sites) and by tumor growth rate. The findings were as follows: (a) TPA increased tumor incidence whether it was applied in vitro or in vivo; (b) TPA in vitro favored more progressive tumors than TPA in vivo; (c) stages of malignant progression from cloned keratinocytes treated in vitro were histologically identical to those following treatment of skin in vivo, including papilloma, dysplastic invasive papilloma, squamous cell carcinoma, and metastasis to lymph node and lung; (d) retinoic acid treatment in vivo reduced tumor incidence and tumor growth rate in initiated cells previously exposed to TPA but not in cells previously exposed to retinoic acid. The results indicated the following: (a) direct effects of TPA on initiated keratinocyte populations were a significant component of tumor promotion; (b) factors in vivo modified the TPA response toward less progressive growth; and (c) the effect of retinoic acid was modulated by prior treatment history.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Drug Synergism; Mice; Mice, Inbred BALB C; Papilloma; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

The preventive effect of vitamin A acid (13-cis-retinoic acid) on skin papillomas induced in rabbits (Oryctolagus cuniculus) by the bite of bed bugs (Cimex lectularius) pre-irradiated with gamma rays was investigated. Painting the papillomas with an oily 13-cis-retinoic acid suspension twice a week in a dose of 25 mg/kg body weight leads to significant regression of these structures.

Topics: Animals; Antineoplastic Agents; Bedbugs; Male; Papilloma; Rabbits; Skin Neoplasms; Tretinoin

Repeated promotion of 7,12-dimethylbenz[alpha]anthracene-initiated cells in mouse skin with 12-O-tetradecanoylphorbol-13-acetate (TPA) induces them to grow as premalignant skin papillomas and some of these subsequently progress to carcinomas. In this study, we demonstrate that this TPA-induced progression of initiated cells to papillomas and carcinomas could be prevented by exposing them previously to weak promoting regimens or to agents that mimic TPA activity.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Benzoflavones; Benzyl Alcohols; Cell Transformation, Neoplastic; Cortisone; Dose-Response Relationship, Drug; Indoles; Mice; Mice, Inbred BALB C; Papilloma; Precancerous Conditions; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin; Vitamin E

A single topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) was found to induce mRNA of a metallothionein (MT) gene or genes in the skin of Sencar mice, and papillomas produced by repeated applications of TPA were shown to have elevated levels of MT mRNA. Induction of MT mRNA was maximal 4-8 h after application of TPA and returned to the control level 24 h later. A dose-dependent increase of MT mRNA was observed with doses of TPA of 1-5 micrograms. Of the other promoters tested, phorbol-12, 13-didecanoate, mezerein, and the ionophore A23187 also induced MT mRNA, but 4-O-methyl-TPA and benzoyl peroxide did not. Phorbol and 4 alpha-phorbol-12,13-didecanoate, which are not promoters, also did not induce MT mRNA. Retinoic acid and 1 alpha, 25-dihydroxyvitamin D3, inhibitors of tumor promotion, did not induce MT mRNA themselves or inhibit the induction of MT mRNA by TPA. In C57BL/6 promotion-resistant mice, TPA caused only slight induction of MT mRNA. These data suggest a correlation between induction of MT mRNA and epidermal hyperplasia. The constitutive elevation of MT mRNA levels in papillomas may be due to the loss, during the process of tumor promotion, of some mechanism regulating MT gene expression.

Topics: Administration, Topical; Animals; Carcinogens; Cholecalciferol; Female; Gene Expression Regulation; Metallothionein; Mice; Mice, Inbred C57BL; Papilloma; RNA, Messenger; Skin Neoplasms; Tetradecanoylphorbol Acetate; Transcription, Genetic; Tretinoin

A 16-year-old girl initially had an eruption consisting of dark gray, flat, pin-sized, confluent papules with a slight hyperkeratotic surface. The lesions appeared after her summer holidays and were restricted to the tanned skin of sun-exposed areas, mainly the abdomen and back. Clinical and histologic findings were consistent with confluent and reticulated papillomatosis. If a basic disorder of keratinization is the cause of confluent and reticulated papillomatosis, it seems likely that the development of the disease in our patient may be due to an abnormal epidermal response to ultraviolet light.

Topics: Adolescent; Biopsy; Epidermis; Female; Humans; Papilloma; Pigmentation Disorders; Tretinoin; Ultraviolet Rays

The present study examined the effect of several prototypic inhibitors of phorbol ester skin tumor promotion on skin tumor promotion by chrysarobin, an anthrone tumor promoter. Retinoic acid (RA) inhibited skin tumor promotion by chrysarobin; however, the degree of inhibition was dependent on the treatment protocol. When RA (10 micrograms/mouse) was given 1 h after each twice-weekly application of chrysarobin (220 nmol/mouse), a marked inhibition of papilloma formation was observed (78%). In additional experiments, using a once-weekly application of chrysarobin, RA also inhibited skin tumor promotion but the magnitude of inhibition was less. Interestingly, RA (10 micrograms/mouse), given 1 or 6 h after the promoter, did not inhibit the induction of epidermal ornithine decarboxylase (ODC) activity induced by a single topical application of chrysarobin (220 nmol). Fluocinolone acetonide (1 microgram/mouse), given 5 min before each twice-weekly application of chrysarobin (220 nmol/mouse) effectively inhibited skin tumor promotion (88%). A 0.5 or 0.25% supplement of alpha-difluoromethylornithine (alpha-DFMO) in the drinking water inhibited the induction of epidermal ODC following chrysarobin (220 nmol/mouse) treatment by 85 or 70%, respectively. Supplements of both 0.25 and 0.5% of alpha-DFMO also led to a 50 and 61% inhibition, respectively, in the number of papillomas per mouse after 25 weeks of promotion with chrysarobin. Interestingly, 0.25% alpha-DFMO in the drinking water did not reduce the number of papillomas per mouse after 20 weeks of promotion with 1.7 nmol 12-O-tetradecanoylphorbol-13-acetate (TPA). However, the number of papillomas per mouse that were greater than or equal to 4 mm in diameter was significantly reduced in both chrysarobin- and TPA-treated mice. The data indicate that RA, FA and alpha-DFMO may be general inhibitors of tumor promoter regardless of the chemical class of tumor promoter. The ability of these inhibitors of phorbol ester promotion to inhibit anthrone promotion indicates that some common biochemical pathways may exist for both classes of skin tumor promoters.

Topics: Animals; Anthracenes; Carcinogens; Cocarcinogenesis; Eflornithine; Female; Fluocinolone Acetonide; Mice; Ornithine Decarboxylase; Papilloma; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

A large number of cross-linked envelopes form spontaneously when cell lines derived from chemically induced mouse skin papillomas are cultured in medium containing 1.2 mM calcium. This phenomenon is associated with high activity of the cross-linking enzyme, epidermal transglutaminase (TGase). The influence of retinoic acid (RA) on envelope formation was studied in detail in a papilloma cell line, PE. Retinoic acid (3 microM) completely blocked cornified envelope (CE) production but reduced TGase activity only 50%. A rabbit antiserum was produced against sonicated CEs isolated from newborn mouse skin. On Western blots of epidermal extracts, diffuse staining was observed for particulate proteins of suprabasal, but not basal, cells and similar immunoreactive material was absent from the cytosolic fraction of both cell layers. The antibody also recognized particulate proteins from PE cells induced to differentiate by calcium, but not from cells grown in the presence of high calcium and RA. The antiserum appears to recognize partially cross-linked CE precursor proteins judging by the diffuse staining, the molecular weight range of the proteins stained, and their origin in the particulate cellular fraction. Cross-linked envelopes could be induced in RA-treated PE cells by permeabilization with 0.75 M NaCl or 50 micrograms/ml A23187. However, this treatment failed to cause the appearance of proteins recognized by the antiserum. Preincubation of the antiserum with purified fragments of CEs from newborn mouse epidermis, but not with cross-linked envelopes from permeabilized, RA-treated PE cells, removed immunoreactivity. These results indicate that the cross-linked envelopes formed in RA-treated cells after permeabilization lack a set of proteins contained in CEs from stratum corneum and may even be composed of different proteins. Retinoic acid appears to prevent CE formation in part by inhibiting activation of epidermal TGase but in addition by influencing the synthesis of precursor proteins.

Topics: Animals; Calcimycin; Cell Membrane; Epidermal Cells; Epidermis; Immunologic Techniques; Papilloma; Sodium Chloride; Time Factors; Transglutaminases; Tretinoin

The present study was designed to determine the effects of dietary 13-cis-retinoic acid and retinyl palmitate on mouse skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA). Female CD-1 mice were initiated with 150 nmol of 7,12-dimethylbenz(a)anthracene and promoted twice weekly with 8 nmol of TPA. Diets supplemented with retinyl palmitate to yield 60,000 or 200,000 IU or 700,000 for 5 wk followed by 350,000 IU per kg of diet (700,000/350,000) fed to mice during tumor promotion resulted in 9%, 37%, and 65% inhibition of the papilloma yield, respectively, at 21 wk of promotion. Although topical applications of 13-cis-retinoic acid have been almost as effective as retinoic acid in preventing the appearance of mouse skin tumors, dietary 13-cis-retinoic acid at 200,000 or 700,000 IU per kg of diet resulted in no reduction in papilloma yield but did result in a dose-dependent decrease in the tumor burden (weight of tumors per mouse). Therefore, dietary retinyl palmitate yielded a dose-dependent inhibition of the number and weight of tumors promoted by TPA, whereas dietary 13-cis-retinoic acid resulted in a decrease in weight but not in number of tumors promoted by TPA.

Topics: Administration, Cutaneous; Animals; Cell Transformation, Neoplastic; Diet; Diterpenes; Dose-Response Relationship, Drug; Female; Isotretinoin; Mice; Papilloma; Retinyl Esters; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Time Factors; Tretinoin; Vitamin A

One of the earliest events after treatment of mouse skin with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) is the induction of ornithine decarboxylase (ODC). Using an immunoperoxidase technique with a rabbit antiserum specific for ODC, the localization of cells containing high levels of ODC following TPA treatment was determined. CD-1 female mice treated with multiple topical applications of TPA and killed 4.5 h after the last TPA treatment exhibited a heterogeneous localization of ODC in this hyperplastic epidermis. The cells which exhibited intense immunostaining were found predominantly in the suprabasal cells lining the hair follicles. This specific ODC staining in cells surrounding hair follicles was inhibited by pretreatment of mice with either retinoic acid or cycloheximide 1 h before TPA treatment. The induction of ODC-specific staining after TPA treatment in hyperplastic mouse skin was transient, since no staining was observed 16 or 24 h after TPA treatment. In contrast, benign papillomas produced by two-stage tumorigenesis contained some cells demonstrating high levels of ODC a week after the last TPA application. These results indicate that both normal mouse epidermal cells as well as tumor tissue display cellular heterogeneity of ODC expression.

Topics: Animals; Enzyme Induction; Epidermal Cells; Epidermis; Female; Keratins; Mice; Mice, Inbred Strains; Ornithine Decarboxylase; Papilloma; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

The effects of dietary supplementation of 13-cis-retinoic acid (13-cis-RA) and alpha-difluoromethylornithine (DFMO) in the drinking water on 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor formation was determined. Administration of 13-cis-RA in the diet and DFMO in the drinking water was started 1 week and 2 days before the first TPA application to the dimethylbenz[a]anthracene-initiated skin of either female CD-1 or SENCAR mice, respectively. Dietary 13-cis-RA failed to inhibit both the tumor yield and the incidence; papillomas per mouse at 0, 5, 50, 100 and 200 mg/kg diet 13-cis-RA doses were 25, 30, 22, 28 and 25 respectively at 18 weeks of promotion treatment and at all doses 100% of the mice bore papillomas. However, dietary 13-cis-RA dramatically reduced the size of skin tumor promoted with TPA. 13-Cis-RA at doses of 5, 50, 100 and 200 mg/kg diet inhibited skin papillomas (greater than 4 mm diameter) per mouse by 28, 55, 76 and 93%, respectively. Retinoid treatment did not affect body weight gains and the survival was more than 80% in all groups. In accord with our previous findings, DFMO when given in drinking water, was a very effective inhibitor of mouse skin tumor promotion by TPA; DFMO at 0.25% concentration inhibited the number of papillomas by 50%. Inhibition of skin tumor promotion by combined treatments with dietary 13-cis-RA (100 mg/kg) and DFMO (0.25%) in the drinking water was possibly additive. The retinoid and DFMO preclude TPA-increased ornithine decarboxylase (ODC) activity and the accumulation of putrescine by differential effects on ODC, an enzyme associated with skin tumor promotion by TPA.

Topics: Animals; Diet; Eflornithine; Female; Isotretinoin; Mice; Mice, Inbred Strains; Ornithine; Ornithine Decarboxylase; Papilloma; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

Laryngeal papillomatosis often involves a relentless growth of papillomas on the vocal cords, requiring repeated excisions to maintain an adequate airway. Because of its antiproliferative effects on epithelial tissues, 13-cis-retinoic acid (0.5-2.0 mg/kd/day p.o.) was used in five patients whose disease was poorly controlled by laser beam surgery. Control of disease for 24+, 5+, and 12 months has been achieved in three of the patients, with two complete and one partial responses. Side effects of treatment were mild and rapidly reversible, following a 25-50% reduction in drug dose.

Topics: Adult; Aged; Antineoplastic Agents; Child; Child, Preschool; Combined Modality Therapy; Drug Evaluation; Female; Humans; Isotretinoin; Laryngeal Neoplasms; Laser Therapy; Male; Middle Aged; Papilloma; Tretinoin

More than one application of the potent tumor-promoting agent, 12-O-tetradecanoylphorbol-13-acetate (TPA), to mouse skin at intervals of more than 48 h led to a larger induction of ornithine decarboxylase (EC 4.1.1.17; ODC) than did a single application. In contrast, at intervals of less than 24 h, the first application of TPA appeared to induce a refractory state; the second application of TPA did not induce ODC. The extent of the inhibitory effect caused by the first application of TPA was dependent on the dose. The abilities of a series of phorbol esters to induce the refractory state correlated with their promoting abilities. However, both mezerein and ethylphenylpropiolate, potent hyperplastic agents with little or no promoting properties, induced the refractory state. On the other hand, pretreatment with TPA caused a refractory effect on ODC induction by mezerein but potentiated ODC induction by ethylphenylpropiolate. The epidermal cells escaped from the refractory state by repeated application of TPA at intervals of 24 h as well as at intervals of twice a week; that is, there was a full induction of ODC activity following a second application within 24 h of a prior application. TPA did not elicit production of detectable ODC-antizyme activity in mouse epidermis. Mixing of a soluble extract from mouse epidermis in the refractory state with that from TPA-stimulated epidermis gave essentially additive ODC activity. Elimination of ODC induction by topical application of retinoic acid or injection of cycloheximide concurrent with the first application of TPA did not restore the ability of a second application of TPA to induce ODC. These results suggest that the refractory effect on ODC induction by TPA does not result from feedback regulation of ODC.

Topics: Acetone; Alkynes; Animals; Carcinogens; Cycloheximide; Diterpenes; Dose-Response Relationship, Drug; Drug Administration Schedule; Enzyme Induction; Epidermis; Female; Mice; Ornithine Decarboxylase; Papilloma; Phorbols; Terpenes; Tetradecanoylphorbol Acetate; Tretinoin

A series of conformationally restricted retinoids has been synthesized and assayed for biological activity. These compounds have aromatic rings in place of selected double bonds of the tetraene side-chain of retinoic acid and could be considered as analogues of retinoic acid in which some of the double bonds possess s-cis topology. Thus far, analogues in which the bonds corresponding to the (5,7E)-, (7,9E)-, (9,11,13E)- and (11,13E)-double bond systems of retinoic acid are restricted to a cisoid conformation have been studied. Analogues were screened for their ability to reverse keratinization in hamster tracheal organ culture and to inhibit the induction of ornithine decarboxylase in mouse epidermis. Selected compounds were also screened in the antipapilloma assay in mice. The toxicity of some analogues on intraperitoneal injection in mice was determined.

Topics: Animals; Biological Assay; Cricetinae; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Enzyme Induction; Epithelium; Keratins; Lethal Dose 50; Mice; Molecular Conformation; Ornithine Decarboxylase Inhibitors; Papilloma; Retinoids; Tretinoin

Topics: Animals; Mice; Papilloma; Retinoids; Skin Neoplasms; Tretinoin

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinogens; Carcinoma, Squamous Cell; Cell Transformation, Neoplastic; Cocarcinogenesis; Croton Oil; Fluocinolone Acetonide; Mice; Mice, Inbred Strains; Papilloma; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tosylphenylalanyl Chloromethyl Ketone; Tretinoin

A series of conformationally restricted retinoids was synthesized and screened in two assays used to measure the ability of retinoids to control cell differentiation, namely, the reversal of keratinization in tracheal organ culture from vitamin A deficient hamsters and the inhibition of the induction of mouse epidermal ornithine decarboxylase by a tumor promoter. These compounds had bonds corresponding to selected bonds of the E-tetraene chain of retinoic acid (1) held in a planar cisoid conformation by inclusion in an aromatic ring. The meta-substituted analogue 3 of 4-[(E)-2-methyl-4-(2,6,6-trimethylcyclohexenyl)-1,3-butadienyl+ ++]benzoic acid (2) was far less active than 2 in both assays. In contrast, the vinyl homologue of 2 (4) and the 7,8-dihydro and 7,8-methano analogues (5 and 6) had activity comparable to that of 2. Analogues of 4-[(E)-2-(1,1,4,4-tetramethyl-1,2,3,4-tetrahydro-6-naphthyl)propenyl] benzoic acid (7) were also screened. Replacement of the tetrahydronaphthalene ring of 7 by a benzonorbornenyl group (9) significantly reduced activity, as did removal of the vinylic methyl group from 9 (10). Replacement of the propenyl group of 9 by a cyclopropane ring (12) also reduced activity. Replacement of the tetrahydronaphthalene ring of 7 by 4,4-dimethyl-3,4-dihydro-2H-1-benzopyran and -benzothiopyran rings (13 and 14) also decreased activity. Inclusion of the 7,9 double bond system of 1 in an aromatic ring (15 and 16) reduced activity, whereas inclusion of the 5,7 double bond system in an aromatic ring enhanced activity (7 and 19). Inclusion of the 11,13 and 9,11,13 double bond systems in aromatic rings (2 and 18) also reduced activity below that of 1. Retinoic acid, 7, 13, 14, and 19 inhibited papilloma tumor formation in mice. Toxicity testing indicated that 7 was more toxic than 1, 13, 14, and 19, 19 was more toxic than 1, and 13 and 14 were less toxic than 1.

Topics: Animals; Cell Differentiation; Chemical Phenomena; Chemistry; Female; Keratins; Mice; Organ Culture Techniques; Ornithine Decarboxylase Inhibitors; Papilloma; Retinoids; Skin; Structure-Activity Relationship; Trachea; Vitamin A Deficiency

Topics: Animals; Cell Transformation, Neoplastic; Etretinate; Female; Humans; Keratins; Male; Middle Aged; Neoplasm Recurrence, Local; Papilloma; Skin Neoplasms; Tretinoin; Urinary Bladder Neoplasms

Tumor initiation in CD-1 mice by benzo[a]pyrene (BaP) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was unaffected by topical pretreatment with 13-cis-retinoic acid (13-cis-RA). Likewise, anthralin-induced tumor promotion in SENCAR mice was unaffected by pretreatment with 13-cis-RA. These results suggest that the action of retinoids in preventing either tumor initiation or promotion is very carcinogen or cocarcinogen specific.

Topics: Animals; Anthralin; Benzo(a)pyrene; Benzopyrenes; Female; Isotretinoin; Methylnitronitrosoguanidine; Mice; Papilloma; Skin Neoplasms; Time Factors; Tretinoin

Two retinoids (13-cis-retinoic acid and retinyl palmitate ) have been shown to exert a good preventive effect in chemically induced papillomas and carcinomas of the skin in female Swiss mice; this effect was investigated over a period of 23 weeks. The tumors were induced by repeated topical application of 3-methylcholanthrene (0.3% MCA, dissolved in acetone; 14 applications). Retinyl palmitate (RP; 6 mg in 0.1 ml acetone/mouse; 10 applications) and 13-cis-retinoic acid (RA; 3 mg in 0.1 ml acetone/mouse; 10 applications) were also administered topically for the 3rd to 9th week from the start of the experiment. This investigation gave evidence for the fact that both the retinoids did not only inhibit the development of skin papillomas but had also a marked effect on skin carcinomas.

Topics: Animals; Diterpenes; Isotretinoin; Methylcholanthrene; Mice; Papilloma; Retinyl Esters; Skin Neoplasms; Tretinoin; Vitamin A

Retinoic acid, a potent inhibitor of mouse skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate, fails to inhibit tumor formation by the complete carcinogen, 7, 12-dimethylbenz[a]anthracene (DMBA). To obtain further clues about the nature of the mechanism of the carcinogenic process as well as the mechanism of the effect of retinoic acid on tumor promotion, the effect of retinoic acid and two other modifiers (dexamethasone and 7,8-benzoflavone) of tumor formation on tumor promotion by 7-bromomethylbenz[a]anthracene (BrMBA) was determined. BrMBA, a structural analogue of DMBA, is a weak mouse skin tumor-initiating agent but is a good skin tumor promoter. Application of 10, 100, and 200 nmol of BrMBA twice weekly to DMBA-initiated skin resulted in 0, 1.6, and 2.5 papillomas per mouse, and 0, 44, and 60% of mice had papillomas at the 25th week of promotion treatment, respectively. Application of 17 nmol of retinoic acid or 76 nmol of dexamethasone 30 min prior to each twice weekly application of 100 nmol of BrMBA to DMBA-initiated skin inhibited the formation of skin papillomas by 73 and 100%, respectively. 7,8-Benzoflavone, at a 367-nmol dose, did not inhibit tumor promotion by BrMBA. Application of 200 nmol of BrMBA to mouse skin induced epidermal ornithine decarboxylase activity; a peak activity was observed between 8 and 18 hr following BrMBA treatment. Application of 17 nmol of retinoic acid or 76 nmol of dexamethasone inhibited the induction of ornithine decarboxylase activity by BrMBA. 7,8-Benzoflavone did not inhibit the induction of ornithine decarboxylase activity by BrMBA. Retinoic acid and dexamethasone, which inhibit tumor promotion by 12-O-tetradecanoylphorbol-13-acetate, also inhibited tumor promotion by BrMBA, but the nature of the mechanism of tumor promotion by BrMBA is unclear; BrMBA did not inhibit specific binding of 12-O-[3H]tetradecanoylphorbol-13-acetate to the cellular membrane fraction of mouse epidermis.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Benz(a)Anthracenes; Cocarcinogenesis; Dexamethasone; Drug Interactions; Enzyme Induction; Female; Mice; Neoplasms, Experimental; Ornithine Decarboxylase; Papilloma; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

Topics: Animals; Avitaminosis; Female; Humans; Neoplasms; Neoplasms, Experimental; Nutritional Physiological Phenomena; Papilloma; Safety; Skin Neoplasms; Tretinoin; Vitamin A; Vitamins; World Health Organization; Xerophthalmia

Papillomas and carcinomas were induced on the skin of mice by initiation with dimethylbenzanthracene, followed by promotion with 12-O-tetradecanoylphorbol-13-acetate. Retinoic acid was applied topically, either chronically, throughout the promotion period, or acutely, to the papillomas or carcinomas. All tumor types were verified histologically. Tumor tissue was incubated with labeled glucosamine and labeled glycoproteins released into media were fractionated on DEAE-Sephadex. For papillomas, one peak (eluted with 0.17 M NaCl) appeared and another (0.40 M) all but disappeared as a result of retinoic acid treatment. Carcinomas also showed the 0.40 M peak released by papillomas, which was also suppressed by retinoic acid. Carcinomas released a 0.26 M peak instead of the 0.17 M peak in response to the retinoid. All three peaks yielded single, symmetrical peaks on gel filtration columns. They were all resistant to mild alkaline hydrolysis. Labeling experiments revealed the presence also of mannose, galactose, and traces of fucose in all three glycoproteins. The 0.17 and 0.26 M peaks were bound by concanavalin A-Sepharose columns, the 0.40 M peak was not. Molecular weights, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, were approximately 80,000 and 105,000 (0.17 M peak), 67,000 (0.26 M peak), 70,000 and 80,000 (0.4 M peak).

Topics: Animals; Electrophoresis, Polyacrylamide Gel; Glycoproteins; Male; Mice; Molecular Weight; Neoplasm Proteins; Neoplasms, Experimental; Papilloma; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

Pathological and histochemical studies were made to clarify the response to an aromatic retinoids (Ro 10-1670, Ro 10-9359) of the papilloma and carcinoma in hamster cheek pouch and mouse dorsal skin. The sizes of papilloma and carcinoma were remarkably reduced or completely regressed following systemic and topical administration of the aromatic retinoids. The antitumor effects increased in proportion to the frequency of administration than doses and were showed no side effects. Tumor tissues responded remarkably to the aromatic retinoids indicated an irregular keratinization including loss of hornified cells, nuclear vacuolization and inflammatory infiltrates which located in the border layer between stromas and neoplastic epithelia. Histochemically, tumor tissues which intensely affected by drugs were characterized by the presence of abundant acid phosphatase active cells. Those acid phosphatase active cells may be consisted of tumor cells, histiocytes and fibroblasts. In the electrocytochemical study acid phosphatase (a lysosomal marker enzyme) activity was found in epithelial tumor cells and fibroblasts. These results were indicated that epithelial tumor regression by aromatic retinoids the might be due to the accelerated lysosomal activity in the tumor cells and fibroblasts.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Acitretin; Animals; Antineoplastic Agents; Carcinoma, Squamous Cell; Cricetinae; Etretinate; Mesocricetus; Mice; Neoplasms, Experimental; Papilloma; Skin Neoplasms; Tretinoin

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Benz(a)Anthracenes; Benzo(a)pyrene; Benzoflavones; Benzopyrenes; Dose-Response Relationship, Drug; Enzyme Induction; Female; Flavonoids; Injections, Intraperitoneal; Methylcholanthrene; Mice; Neoplasms, Experimental; Ornithine Decarboxylase; Papilloma; Phorbols; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin

Topics: Adolescent; Female; Humans; Keratolytic Agents; Middle Aged; Papilloma; Skin; Skin Neoplasms; Syndrome; Tretinoin

Several analogues (15a--e) of methyl (E,E,Z,E)-3,7-dimethyl-6-fluoro-9-(4-methoxy-2,3,6-trimethylphenyl)nonatetraenoate (15f), which had been found to cause a marked regression of chemically induced skin papillomas in mice, were prepared. Two synthetically versatile methods leading to these derivatives are described. The key intermediate, ethyl (Z)-2-fluoro-3-methyl-4,4-dimethoxy-2-butenoate (8), was elaborated to the C10 aldehyde ester, methyl (2E,4E,6Z)-3-methyl-6-fluoro-7-formyl-2,4,6-octatrienoate (14a), which upon Wittig condensation with the aryl-phosphonium salts 13a--e gave the (2E,4E,6Z,8E)-3,7-dimethyl-6-fluoro-9-aryl-2,4,6,8-nonatetraenoates 15a--e. Alternatively, Wittig reaction of 8 and [(4-methoxy-2,3,6-trimethylphenyl)methyl]triphenylphosphonium chloride (13f) gave a mixture of (E/Z,E)-2-fluoro-3-methyl-5-(2,3,6-trimethyl-4-methoxyphenyl)-2,4-pentadienoates 17 and 18, which was converted to 15f. The biological activity of these analogues and the 1H and 19F NMR spectral properties of the intermediates and final products are discussed.

Topics: Animals; Antineoplastic Agents; Mice; Papilloma; Skin Neoplasms; Tretinoin

The pathogenesis of papillomas which developed spontaneously in the forestomach of WB X C57BL/6 F1-W/Wv mutant mice was investigated. The thickness of the forestomach epithelium was used as a quantitative index for development of papillomas. From the 15th day after birth, the forestomach epithelium of the W/Wv mice was significantly thicker than that of the congenic +/+ mice. Administration of aromatic retinoic acid analog (ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-3,7-dimethyl-2,4,6,8 -nonatetraenoate) did not suppress development of papillomas. Since papillomas did not appear in the stomach which was removed from the W/Wv embryos and grafted to the s.c. space produced in the back of the adult mice and since a considerable amount of bile reflux preceded development of papillomas, bile reflux may be a cause of papillomas in W/Wv mice.

Topics: Alleles; Animals; Bile Reflux; Biliary Tract Diseases; Etretinate; Female; Genotype; Male; Mice; Mutation; Papilloma; Stomach; Stomach Neoplasms; Tretinoin

Topics: Animals; Humans; Neoplasms; Neoplasms, Experimental; Organ Culture Techniques; Papilloma; Rats; Skin Neoplasms; Stomach Neoplasms; Structure-Activity Relationship; Tretinoin; Vitamin A; Vitamin A Deficiency

A study was conducted to investigate the in vitro binding affinity of new synthetic polyprenoids to cellular retinoid-binding proteins. Among 10 synthetic polyprenoic acid derivatives, 3,7,11,15-tetramethyl-2,4,6,10,14 hexadecapentaenoic acid (compound 1) was found to have the strongest binding affinity to cellular retinoic acid-binding protein (CRABP) from rat testis. As regards the chemical structure of the polyprenoic acids, it was found that suitable carbon chain length and double bond arrangement are both essential for binding affinity to CRABP. Moreover, compound I displayed a binding affinity to cellular retinoid receptors obtained from precancerous tissues such as mouse skin papillomas and rat liver hyperplastic nodules experimentally induced.

Topics: Animals; Binding, Competitive; Cell Fractionation; Chemical Phenomena; Chemistry; Diterpenes; Female; Hyperplasia; Liver; Male; Mice; Papilloma; Precancerous Conditions; Rats; Rats, Inbred Strains; Retinol-Binding Proteins; Terpenes; Testis; Tretinoin

Ethyl (E,Z,E,E)-3,7-dimethyl-4-fluoro-9-(4-methoxy-2,3,6-trimethylphenyl)nonatetraenoate (10a) has been found to cause a marked regression of chemically induced skin papillomas in mice. A new synthesis of this compound was achieved by condensation of 4-fluoro aldehyde 7 or 8 with the aromatic phosphonium salt 9a. Several analogues (101-e) having different substituted aromatic moieties were also prepared and tested for their antipapilloma effect. The monochloro analogue 10b was shown to have comparable activity to the parent compound 10a.

Topics: Animals; Antineoplastic Agents; Chemical Phenomena; Chemistry; Hypervitaminosis A; Mice; Neoplasms, Experimental; Papilloma; Tretinoin

A new rapid assay has been developed for measurement of the binding of [3H]retinoic acid to cellular retinoic acid-binding protein. The assay, which uses activated charcoal for the separation of bound from unbound retinoic acid, was used to determine the concentration required to inhibit the binding of [3H]retinoic acid to cellular retinoic acid-binding protein by 50% for 18 retinoids with free carboxylic acid groups. Partially purified cellular retinoic acid-binding proteins isolated from rat testes and carcinogen-induced rat mammary tumors were used for these determinations. The following parameters were also determined for some or all of the retinoids: hypervitaminosis A doses; activity against carcinogen-induced mouse skin papillomas; inhibition of growth of a rat chondrosarcoma; inhibition of growth of 3T6 cells; and differentiation of the embryonal carcinoma cell line PCC4.azaIR. While all retinoids that are potent in these biological test systems bind tightly to cellular retinoic acid-binding protein, the converse is not true. The lack of a consistent quantitative correlation between 50% inhibitory concentration and biological activity is probably due to insufficient concentrations of the retinoid in the target tissue or celll, which is a consequence of factors such as absorbability, metabolism, tissue distribution, and pharmacokinetics.

Topics: Animals; Binding, Competitive; Chondrosarcoma; Female; In Vitro Techniques; Male; Mammary Neoplasms, Experimental; Mice; Neoplasms, Experimental; Papilloma; Rats; Retinol-Binding Proteins; Skin Neoplasms; Testis; Tretinoin; Vitamin A

The ability of 5,6-epoxyretinoic acid, a biologically active metabolites of retinoic acid, to inhibit both the induction of ornithine decarboxylase (ODC) activity and skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA) was evaluated. Application of 5,6-epoxyretinoic acid either concurrently with or 1 hr after each application of TPA to the initiated mouse skin inhibited the formation of skin tumors as effectively as did retinoic acid. 5,6-Dihydroretinoic acid, which is a poor substrate for epoxidation, also inhibited skin tumor promotion. 5,6-Epoxyretinoic acid, 5,6-dihydroretinoic acid, and retinoic acid were equally effective in inhibiting the induction of ODC activity by TPA. Insect juvenile hormones inhibited neither the induction of ODC activity nor skin tumor promotion by TPA. These results indicate that (a) epoxidation of retinoic acid at the 5,6-position is not a rate-limiting modification for the anti-promoting activity of retinoic acid and that (b) inhibition of the induction by TPA of mouse epidermal ODC activity may be a simple test for screening the potential prophylactic activities of new retinoids.

Topics: Animals; Female; Juvenile Hormones; Mice; Ornithine Decarboxylase Inhibitors; Papilloma; Phorbol Esters; Phorbols; Skin Neoplasms; Time Factors; Tretinoin

The inhibitory effect of an aromatic retinoic acid analog, ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate, on bladder carcinogenesis in rats treated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) was evaluated. Administration of 50 ppm of aromatic retinoid in the diet before BBN in the drinking water reduced the incidence of papillary or nodular hyperplasia as a preneoplastic lesion of the bladder epithelium (P < 0.05). When given before, during or after BBN, it also greatly reduced the incidence of papilloma (P < 0.001 before BBN, P < 0.01 during or after BBN treatment), and slightly inhibited the development of cancer. Administration of 100 ppm of aromatic retinoid before or during BBN administration also reduced the incidences of papillary or nodular hyperplasia (P < 0.01 before BBN, P < 0.05 during BBN treatment), and its administration before, during or after BBN treatment greatly reduced the incidences of papilloma (P < 0.001), and cancer (P < 0.01 before or after BBN, P < 0.001 during BBN treatment). Similar results were obtained by assessing the effect of the retinoid on the average numbers of various epithelial lesions per 10 cm length of basement membrane of the bladder in tissue slices. These results show that the aromatic retinoid inhibits both the initiation and promotion of bladder carcinogenesis induced in rats by BBN, and that its effect is dose-dependent.

Topics: Animals; Butylhydroxybutylnitrosamine; Cricetinae; Etretinate; Hyperplasia; Male; Mice; Nitrosamines; Papilloma; Precancerous Conditions; Rats; Tretinoin; Urinary Bladder; Urinary Bladder Neoplasms

Topics: Adolescent; Aged; Anti-Bacterial Agents; Child; Cryosurgery; Darier Disease; Elastic Tissue; Epidermolysis Bullosa; Female; Humans; Impetigo; Larva Migrans; Lichen Planus; Male; Middle Aged; Papilloma; Pemphigus; Skin Diseases; Tongue Neoplasms; Tretinoin

(4-Methoyx-2,3,6-trimethylphenyl)nonatetraenoic acids, esters, and amides (analogues of retinoic acid) bearing a fluorine atom(s) or a trifluoromethyl group on the polyene side chain were synthesized. The biological activities of these compounds and of 10-, 12-, and 14-fluororetinoic acid esters were evaluated in vivo in a chemically induced mouse papilloma test; the toxicities were assessed in an in vivo mouse hypervitaminosis A test. Antipapilloma activity greater than the parent nonfluorinated ester was found for 1c (ethyl 12-fluororetinoate) and 23 and 39 (aromatic 4- and 6-fluororetinoid esters, respectively). A similar increase in antipapilloma activity was observed for 71 and 72, the aromatic 4- and 6-fluororetinoic acids, respectively, relative to 2 and for 73 (aromatic 4-fluororetinoid amide) relative to 4.

Topics: Animals; Mice; Neoplasms, Experimental; Papilloma; Skin Neoplasms; Structure-Activity Relationship; Tretinoin

Topics: Animals; Carboxy-Lyases; Enzyme Induction; Female; Mice; Neoplasms, Experimental; Ornithine Decarboxylase; Papilloma; Phorbols; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Time Factors; Tretinoin; Vitamin A

The syntheses of the ring and four side-chain dihydroretinoic acids and/or their esters, 3-7, are described. The syntheses of several other retinoids containing a substituted aromatic ring are also included. The biological activity of the compounds was evaluated in vivo in a chemically induced mouse skin papilloma test and in vitro in two vitamin A deficient assays. The activity observed for 1a, 1c, and 2a in the former test was partially retained in the dihydro derivatives 4b, 4c, and 6b. Similar results were found in the in vitro assays.

Topics: Animals; Cells, Cultured; Cricetinae; Female; Mice; Neoplasms, Experimental; Organ Culture Techniques; Papilloma; RNA; Skin; Skin Neoplasms; Tretinoin; Vitamin A; Vitamin A Deficiency

The mode of action of an aromatic analogue of retinoic acid, ethyl all-trans-9-(4-methoxy-2,3,6-trimethyl-phenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate (Ro 10-9359), a compound known to possess a considerable prophylactic and therapeutic effect on skin papillomas and carcinomas, was investigated with autoradiographic and histopathologic methods. The ip application of a single dose of 1,000 mg Ro 10-9359/kg to female Swiss mice with chemically induced skin papillomas caused a 29% regression of the mean tumor diameter after 3 days and a 51% regression after 7 days. In the tumors, the number of DNA-synthesizing cells [measured by the labeling index (LI)] and the length of the cell cycle were not affected by the retinoid; thus a mode of action at the level of cell proliferation can be excluded. In the normal skin, an increase in the LI of about 30% was observed. A small effect on the cell loss was observed; however, it was not sufficient to explain quantitatively the regression of the tumors. When measured histometrically, it appeared that the loss of the horn and the formation of necroses, 3-10 times larger than in the placebo groups, were mainly responsible for the tumor regressions caused by the retinoid. After 7 days, the proportion of stroma in the tumors was increased, and dilation of the vessels and edema in the stroma proximal to the necroses were frequent.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Cell Division; Croton Oil; DNA, Neoplasm; Female; Mice; Necrosis; Neoplasms, Experimental; Papilloma; Skin Neoplasms; Tretinoin; Vitamin A

Topics: Animals; Carcinoma, Basal Cell; Humans; Neoplasms, Experimental; Papilloma; Precancerous Conditions; Skin Diseases; Skin Neoplasms; Tretinoin; Vitamin A; Vitamin A Deficiency

Topics: Adenosylmethionine Decarboxylase; Animals; Carboxy-Lyases; Drug Administration Schedule; Enzyme Induction; Female; In Vitro Techniques; Mice; Neoplasms, Experimental; Ornithine Decarboxylase; Ornithine Decarboxylase Inhibitors; Papilloma; Phorbols; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin; Vitamin A

Topics: Animals; Cell Membrane; Female; Mice; Microscopy, Electron; Papilloma; Skin Neoplasms; Time Factors; Tretinoin; Vitamin A

Topics: Breast Neoplasms; Papilloma; Retinol-Binding Proteins; Skin; Structure-Activity Relationship; Trachea; Tretinoin; Vitamin A

The properties of a new aromatic retinoic acid analog are described. The compound: all-trans-N-ethyl-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenamide = Ro 11-1430, exerts a therapeutic influence on chemically induced papillomas and carcinomas of the skin of mice. It leads to a marked regression of chemically induced epithelial tumors but does not inhibit the growth of transplantable tumors. The therapeutic use of retinoic acid and its analogs is limited by the appearance of the toxic side effects of the so-called hypervitaminosis A syndrome. The relationship between the anti-tumor activity and these toxic effects is considered a good inidicator for establishing the quality of a compound. The new retinoic acid analog posses a ten times more favorable therapeutic ratio than retinoic acid. The mechanism of action is discussed.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinoma; Mice; Neoplasms, Experimental; Papilloma; Skin Neoplasms; Tretinoin; Vitamin A

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinoma; Croton Oil; Female; Mice; Neoplasms, Experimental; Papilloma; Skin Neoplasms; Tretinoin; Vitamin A

Topics: Administration, Oral; Animals; Female; Injections, Intraperitoneal; Mice; Neoplasms, Experimental; Papilloma; Skin Neoplasms; Tretinoin; Vitamin A