tretinoin and Metaplasia

The retinoids, natural and synthetic derivatives of vitamin A, are active in cancer therapy and prevention. Their biological effects are mediated through ligand-dependent interactions with retinoid receptors that associate with specific co-regulators. A better understanding of retinoid chemopreventive mechanisms is needed. Our prior work revealed that all-trans-retinoic acid (RA) prevented tobacco-specific carcinogenic transformation of cultured human bronchial epithelial cells. RA signaled G1 arrest that permitted repair of genomic DNA damage caused by these carcinogens. RA triggered G1 arrest at least partly through proteasome-dependent degradation of cyclin D1. Proteasomal inhibitors blocked RA-mediated cyclin D1 degradation. To confirm that a specific proteolysis pathway was induced by RA-treatment, a degradation assay was established using in vitro translated cyclin D1 and cellular extracts from RA-treated or untreated human bronchial epithelial cells. Incubation of RA-treated but not the control cellular extracts with in vitro translated cyclin D1 led to cyclin degradation. This degradation depended on the PEST domain of cyclin D1, implicating ubiquitination in this retinoid degradation. Retinoid receptor selective agonists demonstrated that retinoic acid receptor (RAR)beta and retinoid X receptor (RXR) but not RARalpha- or RARgamma-dependent pathways signaled this cyclin degradation. Findings were extended to the NT2/D1 human embryonal carcinoma differentiation model where a similar pathway was activated by RA-treatment. To determine whether G1 cyclins were involved directly in bronchial preneoplasia, immunohistochemical expression profiles for cyclins D1 and E were examined. Aberrant expression of these cyclins was frequent in bronchial preneoplasia. Taken together, these findings indicate that ubiquitin-dependent proteolysis of G1 cyclins is a retinoid chemoprevention mechanism. Whether the retinoids represent the optimal agents to activate this pathway is the subject of ongoing work. These findings provide a rationale for combining the retinoids in chemoprevention trials with other agents that do not activate this proteolysis pathway. What is now known about the retinoids as cancer prevention agents will be reviewed. Emphasis is placed on retinoid effects on cell cycle progression at G1.

Topics: Animals; Anticarcinogenic Agents; Bronchi; Bronchial Diseases; Carcinoma, Embryonal; Cell Differentiation; Cell Transformation, Neoplastic; Cyclins; Cysteine Endopeptidases; Endopeptidases; Epithelial Cells; G1 Phase; Gene Expression Profiling; Gene Expression Regulation; Humans; Metaplasia; Mice; Models, Biological; Multienzyme Complexes; Neoplasms; Precancerous Conditions; Proteasome Endopeptidase Complex; Protein Processing, Post-Translational; Protein Structure, Tertiary; Receptors, Retinoic Acid; Retinoids; Tretinoin; Tumor Cells, Cultured; Ubiquitin; Vitamin A Deficiency

To investigate the efficacy of all-trans retinoic acid (ATRA) in human gastric dysplasia.. In this double-blind study, patients with precancerous gastric dysplasia with or without intestinal metaplasia (IM) received either conventional treatment consisting of omeprazole and sucralfate (control group) or conventional treatment plus ATRA. Gastric mucosal biopsies were performed before and after drug treatment and were analysed histologically; expression of retinoblastoma (Rb) protein and HER2 protein in gastric mucosa were measured using immunohistochemistry.. A total of 122 patients were included in the study, 63 in the ATRA group and 59 in the control group. In the ATRA group, dysplasia was attenuated in 43 out of 63 patients (68%) compared with 22 out of 59 patients (37%) in the control group; however, IM was not affected by treatment in either group. ATRA treatment was associated with significantly increased Rb expression and decreased HER2 expression in gastric mucosa.. The use of conventional therapy plus ATRA for gastric dysplasia was associated with improved efficacy compared with conventional therapy alone. It was also accompanied by increased Rb expression and decreased HER2 expression in gastric mucosa. The addition of ATRA to conventional therapy for gastritis may improve the prognosis of gastric dysplasia.

Topics: Adult; Aged; Double-Blind Method; Drug Therapy, Combination; Female; Gastric Mucosa; Humans; Intestines; Male; Metaplasia; Middle Aged; Omeprazole; Precancerous Conditions; Prognosis; Retinoblastoma Protein; Stomach; Stomach Neoplasms; Sucralfate; Treatment Outcome; Tretinoin

Loss of retinoic acid receptor beta (RAR-beta) expression in the bronchial epithelium is considered a biomarker of preneoplasia. Retinoids can restore expression of this receptor and, presumably, halt the progression of carcinogenesis. This study was designed to investigate whether either of two retinoid-based regimens, 9-cis-retinoic acid (RA) or 13-cis-RA plus alpha-tocopherol (AT), could reverse RAR-beta expression loss in former smokers after 3 months of treatment.. Individuals (n = 226) who had smoked at least 20 pack-years and had ceased smoking for at least 12 months were randomly assigned to receive 3 months of daily oral 9-cis-RA (100 mg), 13-cis-RA (1 mg/kg) + AT (1200 IU), or placebo. Bronchoscopy and biopsy at six predetermined sites of the bronchial tree were performed before treatment and at 3 and 6 months thereafter. Specimens were evaluated for squamous metaplasia, dysplasia, and RAR-beta expression. McNemar's test was used to test changes in RAR-beta expression and squamous metaplasia within each treatment group, and a generalized estimating equations model was applied to model the treatment effect, adjusting for covariates. All statistical tests were two-sided.. A total of 177 assessable subjects completed at least 3 months of therapy and underwent at least the baseline and 3-month bronchoscopic evaluations with biopsies. RAR-beta was detected in 69.7% of all baseline biopsy samples, and metaplasia was evident in 6.9% of all baseline samples from 240 subjects. Restoration of RAR-beta expression (P =.03) and reduction of metaplasia (P =.01) were found in the 9-cis-RA group. After adjustment for years of smoking, packs/day smoked, and metaplasia, treatment with 9-cis-RA, but not with 13-cis-RA + AT, led to a statistically significant increase in RAR-beta expression compared with placebo (P =.03).. 9-cis-RA treatment can restore RAR-beta expression in the bronchial epithelium of former smokers, raising the possibility that this retinoid has potential chemopreventive properties in former smokers.

Topics: Adult; Aged; Alitretinoin; Antineoplastic Agents; Biopsy; Bronchi; Bronchoscopy; Double-Blind Method; Female; Gene Expression Regulation, Neoplastic; Humans; In Situ Hybridization; Male; Metaplasia; Middle Aged; Precancerous Conditions; Receptors, Retinoic Acid; Respiratory Mucosa; RNA, Messenger; Smoking; Tretinoin

Epidemiological studies suggested that vitamin A may be protective against lung cancer, however, recent chemoprevention trials with beta-carotene, a precursor of vitamin A, demonstrated enhancement of lung carcinogenesis among smokers. Whether vitamin A is beneficial or harmful in chemoprevention of lung cancer in smokers has not been resolved. This study was designed to determine the effect of retinol alone in current and former smokers using bronchial dysplasia, nuclear morphometry and retinoic acid receptor-beta (RAR-beta) mRNA expression as surrogate end-point biomarkers (SEBs). Eighty-one current or former smokers with a smoking history of >/=30 pack-years were randomized to receive either placebo or retinol (50,000 IU per day) for six months. Fluorescence bronchoscopy was performed prior to treatment to localize areas suggestive of dysplasia. At least 4 bronchial biopsies were taken per subject including at least two biopsies from apparently normal areas. The same areas were precisely re-biopsied after 6 months. Any new areas suggestive of dysplasia were also biopsied. Changes in the SEBs were assessed before and after treatment. At baseline, the frequency of biopsies negative for RAR-beta expression was: normal (23%), hyperplasia (28%), metaplasia (41%), mild dysplasia (41%), and moderate/severe dysplasia (44%). There was no significant difference in the regression rate between the retinol and placebo groups using histopathology and nuclear morphometry as SEBs. The likelihood of regression was found to be lower in those who continued to smoke during the study (OR=1.86 for those smoking >10 cigarettes per day, p=0.084 to OR=0.95, p=0.26 for those smoking 20+ per day compared to ex-smokers). Retinol was not effective in the up-regulation of RAR-beta in lesions with bronchial dysplasia. We postulate that the lack of effect of retinol on RAR-beta expression among individuals who continued to smoke while taking retinol may be due to suppressive effect of tobacco smoke constituents on RAR-beta expression and/or altered cellular metabolism of retinol to retinoic acid and its isomers.

Topics: Aged; Anticarcinogenic Agents; Biomarkers; Biomarkers, Tumor; Biopsy; Bronchoscopy; Cell Nucleus; Chemoprevention; Female; Humans; Lung Diseases; Lung Neoplasms; Male; Metaplasia; Middle Aged; Odds Ratio; Placebos; Receptors, Retinoic Acid; RNA, Messenger; Smoking; Time Factors; Tretinoin; Vitamin A

Epidermal growth factor receptor (EGFr) is expressed in human bronchial epithelial cells, and non-small cell lung cancers express increased EGFr. Squamous metaplasia of the bronchial epithelium occurs in chronic smokers and is considered an early premalignant change. In this study, EGFr expression was examined in biopsies of histologically normal and metaplastic bronchial tissues obtained from 69 smokers who were enrolled in a randomized placebo-controlled chemoprevention trial. This trial tested the effects of 6 months of treatment with 13-cis retinoic acid (13cRA) on bronchial metaplasia. EGFr expression was examined as a marker of bronchial metaplasia and response to 13cRA treatment. In bronchial biopsies obtained from patients in this study, EGFr expression was higher in metaplastic biopsies than in normal biopsies (P = 0.02). Smoking cessation during treatment correlated with reduced metaplasia (P < 0.001) and EGFr expression (P = 0.02), but multivariate analysis suggested that this effect of smoking cessation on EGFr expression was dependent upon reversal of bronchial metaplasia. 13cRA treatment did not alter EGFr expression (P = 0.23). Baseline EGFr expression levels in metaplastic biopsies did not predict metaplasia reversal. This study demonstrated that increased EGFr expression is a biomarker of bronchial metaplasia, but it did not support the hypothesis that EGFr is a biomarker of retinoid response in lung cancer chemoprevention trials.

Topics: Analysis of Variance; Antineoplastic Agents; Biopsy; Bronchi; Epithelium; ErbB Receptors; Female; Humans; Logistic Models; Male; Metaplasia; Predictive Value of Tests; Smoking Cessation; Tretinoin

In a prospective, double-masked clinical study, the authors evaluated the efficacy and safety of topically applied tretinoin ophthalmic ointment (0.01%) versus placebo in the treatment of squamous metaplasia associated with various ocular surface disorders involving dry eyes. Study parameters consisted of graded symptoms and signs, and serial impression cytologies. A total of 161 patients were enrolled in the study. Of these patients, 116 who had a minimum of 4 to 8 months of follow-up qualified for final statistical analysis. These patients were classified into two major groups: (1) keratoconjunctivitis sicca (KCS) and (2) conjunctival cicatricial diseases (Stevens-Johnson syndrome, inactive pemphigoid, radiation-induced dry eye, drug-induced pseudopemphigoid, and toxic epidermal necrolysis). An analysis of adjusted mean changes for KCS patients showed no statistically significant differences between active drug and placebo. A similar analysis of patients with conjunctival cicatricial diseases indicated a statistically significant (P less than 0.05) reversal of conjunctival keratinization in the temporal bulbar site after treatment with active drug, however, clinical symptoms and signs showed no significant improvement with active drug relative to placebo. Side effects were limited to blepharoconjunctivitis and were reversible upon tapering or stopping the drug.

Topics: Administration, Topical; Adolescent; Adult; Aged; Aged, 80 and over; Conjunctiva; Conjunctival Diseases; Double-Blind Method; Epithelium; Female; Follow-Up Studies; Humans; Keratoconjunctivitis; Keratoconjunctivitis Sicca; Male; Metaplasia; Middle Aged; Multicenter Studies as Topic; Prospective Studies; Random Allocation; Tretinoin

Topics: Adult; Aged; Biopsy; Bronchi; Bronchoscopes; Clinical Trials as Topic; Etretinate; Female; Fiber Optic Technology; Humans; Male; Metaplasia; Middle Aged; Smoking; Tretinoin; Vitamin A

Smoking is an established risk factor for pancreatic cancer (PC), but late diagnosis limits the evaluation of its mechanistic role in the progression of PC. We used a well-established genetically engineered mouse model (LSL-K-ras(G12D)) of PC to elucidate the role of smoking during initiation and development of pancreatic intraepithelial neoplasia (PanIN). The 10-week-old floxed mice (K-ras(G12D); Pdx-1cre) and their control unfloxed (LSL-K-ras(G12D)) littermates were exposed to cigarette smoke (total suspended particles: 150 mg/m(3)) for 20 weeks. Smoke exposure significantly accelerated the development of PanIN lesions in the floxed mice, which correlated with tenfold increase in the expression of cytokeratin19. The systemic accumulation of myeloid-derived suppressor cells (MDSCs) decreased significantly in floxed mice compared with unfloxed controls (P<0.01) after the smoke exposure with the concurrent increase in the macrophage (P<0.05) and dendritic cell (DCs) (P<0.01) population. Further, smoking-induced inflammation (IFN-γ, CXCL2; P<0.05) was accompanied by enhanced activation of pancreatic stellate cells and elevated levels of serum retinoic acid-binding protein 4, indicating increased bioavailability of retinoic acid which contributes to differentiation of MDSCs to tumor-associated macrophages (TAMs) and DCs. TAMs predominantly contribute to the increased expression of heparin-binding epidermal growth factor-like growth factor (EGFR ligand) in pre-neoplastic lesions in smoke-exposed floxed mice that facilitate acinar-to-ductal metaplasia (ADM). Further, smoke exposure also resulted in partial suppression of the immune system early during PC progression. Overall, the present study provides a novel mechanism of smoking-induced increase in ADM in the presence of constitutively active K-ras mutation.

Topics: Acinar Cells; Animals; Carcinoma in Situ; Carcinoma, Pancreatic Ductal; Cell Differentiation; Chemokine CXCL2; Dendritic Cells; Disease Progression; Genes, ras; Heparin-binding EGF-like Growth Factor; Inflammation; Interferon-gamma; Keratin-19; Macrophages; Metaplasia; Mice; Mice, Transgenic; Myeloid Cells; Pancreatic Ducts; Pancreatic Neoplasms; Pancreatic Stellate Cells; Receptors, Retinoic Acid; Signal Transduction; Smoke; Smoking; Tretinoin

The blood testis-barrier (BTB) is essential for maintaining homeostasis in the seminiferous epithelium. Although many studies have reported that vitamin A (VA) is required for the maintenance of spermatogenesis, the relationships between the BTB, spermatogenesis and VA have not been elucidated. In this study, we analyzed BTB assembly and spermatogenesis in the testes of mice fed the VA-deficient (VAD) diet from the prepubertal period to adulthood. During the prepubertal period, no changes were observed in the initiation and progression of the first spermatogenic wave in mice fed the VAD diet. However, the numbers of preleptotene/leptotene spermatocytes derived from the second spermatogenic wave onwards were decreased, and initial BTB formation was also delayed, as evidenced by the decreased expression of mRNAs encoding BTB components and VA signaling molecules. From 60 days postpartum, mice fed the VAD diet exhibited apoptosis of germ cells, arrest of meiosis, disruption of the BTB, and dramatically decreased testis size. Furthermore, vacuolization and calcification were observed in the seminiferous epithelium of adult mice fed the VAD diet. Re-initiation of spermatogenesis by VA replenishment in adult mice fed the VAD diet rescued BTB assembly after when the second spermatogenic wave initiated from the arrested spermatogonia reached the preleptotene/leptotene spermatocytes. These results suggested that BTB integrity was regulated by VA metabolism with meiotic progression and that the impermeable BTB was required for persistent spermatogenesis rather than meiotic initiation. In conclusion, consumption of the VAD diet led to critical defects in spermatogenesis progression and altered the dynamics of BTB assembly.

Topics: Animals; Apoptosis; Biomarkers; Blood-Testis Barrier; Calcinosis; Diet; Disease Models, Animal; Epididymis; Female; Gene Expression Regulation, Developmental; Infertility, Male; Male; Metaplasia; Mice; Mice, Inbred C57BL; Organ Size; Spermatogenesis; Spermatogonia; Testis; Tretinoin; Vacuoles; Vitamin A Deficiency

Understanding the molecular and cellular processes underlying the development, maintenance, and progression of Barrett's esophagus (BE) presents an empirical challenge because there are no simple animal models and standard 2D cell culture can distort cellular processes. Here we describe a three-dimensional (3D) cell culture system to study BE. BE cell lines (CP-A, CP-B, CP-C, and CP-D) and esophageal squamous keratinocytes (EPC2) were cultured on a matrix consisting of esophageal fibroblasts and collagen. Comparison of growth and cytokeratin expression in the presence of all-trans retinoic acid or hydrochloric acid was made by immunohistochemistry and Alcian Blue staining to determine which treatments produced a BE phenotype of columnar cytokeratin expression in 3D culture. All-trans retinoic acid differentially affected the growth of BE cell lines in 3D culture. Notably, the non-dyplastic metaplasia-derived cell line (CP-A) expressed reduced squamous cytokeratins and enhanced columnar cytokeratins upon ATRA treatment. ATRA altered the EPC2 squamous cytokeratin profile towards a more columnar expression pattern. Cell lines derived from patients with high-grade dysplasia already expressed columnar cytokeratins and therefore did not show a systematic shift toward a more columnar phenotype with ATRA treatment. ATRA treatment, however, did reduce the squamoid-like multilayer stratification observed in all cell lines. As the first study to demonstrate long-term 3D growth of BE cell lines, we have determined that BE cells can be cultured for at least 3 weeks on a fibroblast/collagen matrix and that the use of ATRA causes a general reduction in squamous-like multilayered growth and an increase in columnar phenotype with the specific effects cell-line dependent.

Topics: Barrett Esophagus; Cell Line, Transformed; Coculture Techniques; Collagen; Epithelial Cells; Esophagus; Fibroblasts; Humans; Hydrochloric Acid; Hydrogen-Ion Concentration; Keratinocytes; Keratins; Metaplasia; Phenotype; Telomerase; Time Factors; Transfection; Tretinoin

Retinoids such as all trans-retinoic acid (ATRA) have been used as chemopreventive agents for a number of premalignant conditions. To explore a potential role for retinoids as chemopreventive agents for Barrett's esophagus, we studied ATRA's effects on apoptosis in a nonneoplastic, telomerase-immortalized, metaplastic Barrett's cell line. We treated the Barrett's cells with ATRA in the presence and absence of inhibitors to p53 (pSRZ-siRNA-p53), p38 (SB-203580 and p38 siRNA), and the caspase cascade (z-Val-Ala-Asp-fluoromethyl ketone). We determined the effects of ATRA and the various inhibitors on apoptosis using cell morphology, terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling staining, cleaved caspase-3 immunofluorescence, and Annexin V staining. We also determined how ATRA in the presence and absence of the inhibitors affected apoptosis following low-dose UV-B irradiation. ATRA induced apoptosis and increased the expression of p53 protein in a dose-dependent fashion. The apoptotic effect of ATRA was abolished by treatment with inhibitors of both p38 and caspase, but not by p53 interfering RNA (RNAi). Inhibition of p38 also prevented expression of cleaved caspase-3, suggesting that ATRA activates p38 upstream of the caspase cascade. We found that ATRA sensitized immortalized Barrett's cells to apoptosis induced by low-dose UV-B irradiation via a similar mechanism. ATRA induces apoptosis in Barrett's epithelial cells and sensitizes them to apoptosis induced by UV-B irradiation via activation of p38 and the caspase cascade, but not through p53. This study elucidates molecular pathways whereby retinoid treatment might prevent carcinogenesis in Barrett's metaplasia and suggests a potential role for the use of safer retinoids for chemoprevention in Barrett's esophagus.

Topics: Apoptosis; Barrett Esophagus; Caspases; Cell Culture Techniques; Cell Line; Flow Cytometry; Humans; Metaplasia; p38 Mitogen-Activated Protein Kinases; RNA Interference; Tretinoin; Tumor Suppressor Protein p53; Ultraviolet Rays

Two novel series of all-trans-beta-retinoic acid derivatives were synthesized and found to possess anticancer activity. The first series, cephalosporin 3'-retinoic esters 6 and 7 were, respectively, obtained by the condensation of all-trans-beta-retinoic acid (2) with cephalosporins 4 and 5. The second series, 7-(retinamido)cephalosporins 11 and 12, were synthesized, respectively, by the condensation of 2 with cephalosporins 9 and 10. These four heretofore undescribed compounds 6, 7, 11, and 12 showed inhibitory activity against murine leukemias (L1210 and P388), sarcoma 180, breast carcinoma (MCF7), and human T-lymphocytes (Molt4/C8 and CEM/0). They also inhibited squamous metaplasia and keratinization in tracheal organ cultures derived from vitamin-A-deficient hamsters. Moreover, cephalosporin 3'-retinoic ester 7 exhibited enhanced activity against keratinization with ED(50)=3.91 x 10(-11) M in the presence of a beta-lactamase from Staphylococcus aureus 95. A tumor targeting fusion protein (dsFv3-beta-lactamase) was also used in conjunction with cephem-based retinoid 7 and the potency of 7 toward L1210, P388, and MCF7 was found to approach that of the free retinoic acid (2). In the presence of dsFv3-beta-lactamase, tumor cells were found to be much more susceptible to retinoid 7 than normal human embryonic lung cells. These notions provide a new approach to the use of beta-retinoic acid for antitumor therapy.

Topics: Animals; Antibodies, Monoclonal; Antineoplastic Agents; beta-Lactamases; Cell Survival; Cephalosporins; Drug Design; Drug Stability; Esters; Humans; Hydrolysis; Keratins; Kinetics; Magnetic Resonance Spectroscopy; Metaplasia; Mice; Prodrugs; Rats; Solubility; Tretinoin; Tritium; Tumor Cells, Cultured; Water

Topics: Animals; Anticarcinogenic Agents; Antioxidants; Asbestosis; beta Carotene; Cocarcinogenesis; Cohort Studies; Down-Regulation; Ferrets; Gene Expression Regulation; Genes, fos; Genes, jun; Humans; Incidence; Lung; Lung Neoplasms; Metaplasia; Nicotiana; Plants, Toxic; Proliferating Cell Nuclear Antigen; Receptors, Retinoic Acid; Smoke; Smoking; Transcription Factor AP-1; Tretinoin

Epidemiologic studies have demonstrated that individuals who eat more fruits and vegetables and/or have high levels of serum beta-carotene have a lower risk of cancer, especially lung cancer. However, recent human intervention studies using beta-carotene supplements have shown an increase in the risk of lung cancer among smokers and asbestos workers. In this study, we used an animal model system to evaluate the hazard associated with a combination of high-dose beta-carotene supplementation and tobacco smoking.. Ferrets were given a beta-carotene supplement, exposed to cigarette smoke, or both for 6 months. Cell proliferation and squamous metaplasia in lung tissue were assessed by examination of proliferating-cell nuclear antigen expression and histopathologic examination, respectively. beta-Carotene and retinoid concentrations in lung tissue and plasma samples were analyzed by high-performance liquid chromatography. Expression of genes for retinoic acid receptors (RARs) and activator protein-1 (encoded by the c-Jun and c-Fos genes) in lung tissue specimens was examined by western blotting.. A strong proliferative response in lung tissue and squamous metaplasia was observed in all beta-carotene-supplemented animals, and this response was enhanced by exposure to tobacco smoke. When compared with control groups, all three treatment groups had statistically significantly lower concentrations of retinoic acid in lung tissue, and they exhibited 18%-73% reductions in RARbeta gene expression; however, RARalpha and RARgamma gene expression was not reduced. Ferrets given a beta-carotene supplement and exposed to tobacco smoke had threefold to fourfold elevated expression of the c-Jun and c-Fos genes.. Diminished retinoid signaling, resulting from the suppression of RARbeta gene expression and overexpression of activator protein-1, could be a mechanism to enhance lung tumorigenesis after high-dose beta-carotene supplementation and exposure to tobacco smoke.

Topics: Animals; beta Carotene; Cell Division; Cocarcinogenesis; Diterpenes; Down-Regulation; Environmental Exposure; Ferrets; Gene Expression Regulation; Genes, fos; Genes, jun; Humans; Lung; Lung Neoplasms; Male; Metaplasia; Nicotiana; Plants, Toxic; Precancerous Conditions; Proliferating Cell Nuclear Antigen; Receptors, Retinoic Acid; Retinyl Esters; Signal Transduction; Smoke; Transcription Factor AP-1; Tretinoin; Vitamin A

We previously reported (Gray, T. E., K. Guzman, C. W. Davis, L. H. Abdullah, and P. Nettesheim. 1996. Mucociliary differentiation of serially passaged normal human tracheobronchial epithelial cells. Am. J. Respir. Cell Mol. Biol. 14:104-112) that retinoic acid (RA)-deprived cultures of normal human tracheobronchial epithelial (NHTBE) cells became squamous, failed to produce mucin, and instead secreted or released large amounts of lysozyme (LZ). The purpose of the studies reported here was to elucidate the relationship between RA deficiency-induced squamous differentiation and increased LZ, and to determine what mechanisms were involved. We found that intracellular LZ began to accumulate in RA-deficient NHTBE cultures early during squamous differentiation. Between Days 10 and 18 of culture, cellular LZ levels were more than 10 times higher in RA-deficient than in RA-sufficient cultures. On Day 12, large numbers of cells began to exfoliate in RA-deficient cultures and extracellular LZ appeared at the apical surface, presumably released from the exfoliated cells. Metabolic labeling studies showed that the rate of LZ synthesis was not increased in RA-deficient cultures over that in RA-sufficient cultures; however, intracellular LZ half-life was much longer in RA-deficient cultures. We concluded that the increased accumulation of both intra- and extracellular LZ in RA-deficient cultures was due to increased LZ stability and was not the result of increased LZ synthesis. When RA-deficient cultures were treated on Day 7 with 10(-6) M RA, intracellular LZ levels did not substantially decrease until 3 d later, coinciding with a marked increase in mucin secretion. LZ messenger RNA levels were unchanged at 24 h, but were modestly increased (rather than decreased) at all subsequent time points. We concluded that RA does not directly regulate LZ, and that the excessive accumulation of LZ in RA-deprived NHTBE cells is a consequence of vitamin A deficiency-induced abnormal differentiation.

Topics: Bronchi; Cell Differentiation; Cell Line; Cornified Envelope Proline-Rich Proteins; Epithelial Cells; Humans; Keratinocytes; Membrane Proteins; Metaplasia; Mucins; Muramidase; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors; Trachea; Transcription, Genetic; Tretinoin

The 9-cis-retinoic acid (9cRA) is an endogenous ligand of retinoid X nuclear receptors (RXRs). Although the epidermis contains five times more RXRs than RARs, little is known on the activity of topical 9cRA. In order to circumvent surface isomerization of topically applied 9cRA into all-trans-retinoic acid (atRA), we used topical 9-cis-retinaldehyde (9cRAL) as a precursor of 9cRA, hypothesizing that keratinocytes would metabolize 9cRAL into 9-cis-retinoic acid (9cRA). Retinoid content was determined by HPLC analysis of mouse tail skin that had been washed after the application of 9cRAL (0.05% for 14 days) to evaluate the metabolites produced within the epidermis. Biologic activities of 9cRAL and atRAL were analysed by assessing hyperplastic and metaplastic responses, by determining epidermal thickness and the levels of mRNAs encoding for specific keratins. atRAL and derived retinoids were found in skin treated with either atRAL or 9cRAL. The metabolite pattern obtained with 9cRAL was similar to that obtained with atRAL except the presence in 9cRAL samples of an unidentified nonpolar metabolite. However, treatment with 9cRAL yielded higher atRAL and lower retinyl ester concentrations. The biologic activities (hyperplastic and metaplastic responses) resulting from topical application of 9cRAL were lower than those induced by atRAL or atRA at similar concentrations. Taken together, these data show that topical 9cRAL does not deliver significant amounts of 9cRA and exerts less biologic activity than atRAL. Contrary to atRAL, 9cRAL does not appear therefore as a pertinent candidate for topical use in humans.

Topics: Administration, Topical; Alitretinoin; Animals; Gene Expression; Hyperplasia; Keratins; Metaplasia; Mice; Mice, Inbred C57BL; Retinaldehyde; Retinoids; RNA, Messenger; Skin; Stereoisomerism; Tail; Tretinoin

Rabbit tracheal explants, exposed to burning pine wood smoke, were cultured in a chemically defined medium with and without retinoic acid (+/- RA). Exposures of 15-20 minute led to RA-independent degeneration of the mucociliary epithelial sheath. In 10 minute exposures tissue integrity was retained, but epithelial morphology changed from normal pseudostratified columnar to the flattened appearance typical of the squamous phenotype. Despite the dramatic shift in morphology, explants exhibited normal RA-dependent mucin gene expression characteristic of the mucociliary phenotype. Furthermore, electron micrographs showed continued presence of both secretory granules and cilia. RA(+) cultures also showed a normal pattern of adherent epithelial cells. In RA(-) cultures, however, there were prominent intercellular spaces indicating an RA dependence for maintaining adhesive contacts following smoke exposure. An 18-mer mucin antisense oligomer that suppressed mucin gene expression also unexpectedly blocked the smoke induced metaplasia in RA(+) cultures, but the sense oligomer had no effect.

Topics: Animals; Cell Differentiation; Culture Techniques; Epithelium; Gene Expression; Metaplasia; Microscopy, Electron; Mucins; Mucous Membrane; Oligonucleotides, Antisense; Phenotype; Rabbits; Smoke Inhalation Injury; Trachea; Tretinoin

Embryonic mouse upper-lip skin explants treated with 16.7 microM all-trans retinoic acid (tRA) give rise to a glandular metaplasia of hair vibrissa follicles; however, at this concentration, tRA can activate not only the three retinoic acid receptors (RARalpha, beta, and gamma), but also the retinoid X receptors (RXRalpha, beta, and gamma) as a consequence of its isomerization to 9-cis retinoic acid. We therefore studied the respective roles of the RXR and RAR by treating RARalpha(-/-), beta(-/-), and gamma(-/-) skin explants with tRA and wild-type explants with synthetic retinoids specific for RXR or for each of the RAR. The null mutation of the RARalpha, RARbeta, and RARgamma genes did not prevent tRA-induced hair glandular metaplasia, but RARgamma inactivation dramatically reduced its ratio. As demonstrated by treating explants with a RAR- or a RXR-specific panagonist (CD367 and Ro25-7386, respectively), RAR are primarily responsible for this metaplasia. The use of two retinoids (Ro40-6055, 8 x 10(-3) microM, or CD437, 7.7 x 10(-2) microM) that are believed to act, respectively, as a RARalpha- or a RARgamma-specific agonist showed that both these receptors can initiate a metaplasia. In contrast, BMS453, a RARbeta-specific agonist, was unable to give rise to any metaplasia. Nevertheless, the highest degrees and ratios of metaplasia were only obtained after treatment with the CD367 RAR panagonist, or with either Ro40-6055 or CD437 at a concentration sufficient to allow the activation of the three RAR, suggesting that RARbeta activation is required for a metaplasia of all vibrissae.

Topics: Animals; Female; Lip; Metaplasia; Mice; Mice, Knockout; Receptors, Retinoic Acid; Retinoic Acid Receptor alpha; Retinoic Acid Receptor gamma; Skin; Tretinoin

Changes in ultrastructural characteristics and mucin gene expression were examined in rat tracheal explants cultured in a synthetic medium +/- retinoic acid (RA), benzo[a]pyrene (B[a]P) and N-methyl-N-nitrosourea (NMNU). In the RA(+) cultures, no changes in either ultrastructural features or mucin gene expression were detected after 48 h incubation. After 96 h incubation, however, the ultrastructural features associated with the squamous phenotype were characteristics of cultures containing the two carcinogens and the mucin gene expression was slightly reduced. Thus, in the presence of retinoic acid, the carcinogen induced changes in cytology to the squamous phenotypes were not matched by a marked loss of mucin gene expression. Explants cultured for 48 h without RA and +/- carcinogens showed none of the cytological changes associated with onset of the squamous phenotype. While mucin mRNA was still detected, it was clearly reduced compared to 48 h cultures in RA(+) medium. However, 48 h later, all explants exhibited pronounced squamous metaplasia and the mucin message decreased to trace levels. Thus, the results of these experiments with B[a]P and NMNU in RA(+) and RA(-) media indicates that at least the early carcinogen induced changes may be distinct from those associated with the retinoid pathway controlling expression of the mucin component of the mucociliary epithelium.

Topics: Animals; Benzo(a)pyrene; Carcinogens; Carcinoma, Squamous Cell; Cell Differentiation; Culture Media; Culture Techniques; Epithelium; Gene Expression; Lung Neoplasms; Metaplasia; Methylnitrosourea; Mucins; Phenotype; Rats; RNA, Messenger; Trachea; Tretinoin; Vitamin A Deficiency

The alterations in the mucociliary unit in the course of chronic inflammation of the upper respiratory tract correspond to morphologic anomalies of the respiratory epithelium and induce cuboidal and squamous metaplasia. While the squamous pattern is most probably irreversible, it is still not clear whether it is possible to restore ciliogenesis in cuboidal metaplasia. In the present study, the action of different inductors of differentiation was evaluated in vitro in isolated cells and explants from human nasal metaplastic epithelium. Polar/apolar compounds induced secretory activity, whereas retinoic acid was able to induce ciliogenesis in some cases. Therefore, the cuboidal metaplastic condition appears to be reversible, and two distinct pathways of differentiation, secretory and ciliogenetic, are identifiable.

Topics: Acetamides; Cell Differentiation; Cells, Cultured; Chronic Disease; Cilia; Cryoprotective Agents; Dimethyl Sulfoxide; Epithelium; Hematinics; Humans; Keratolytic Agents; Metaplasia; Microscopy, Electron; Microscopy, Electron, Scanning; Nasal Cavity; Nasopharyngitis; Tretinoin

A striking effect of retinoids is their ability to alter cell fate during development. The mucous metaplasia produced by treating chick embryo skin in organ culture with retinoic acid is a classical example of this property. It has been impossible so far to demonstrate that retinoids are able to provoke metaplasia of adult keratinocytes grown in vitro, although these agents have been shown to block terminal epidermal differentiation, to induce increased synthesis of mucopolysaccharides, and to induce the ectopic expression of K19 and K13 keratins. Our previous work showed that adult human epidermal keratinocytes grown on dermal equivalents at the surface of a culture medium containing physiological amounts of retinoids form a normal keratinized epidermis, while when excess retinoic acid is added to the culture medium, keratinization is prevented but stratification is not. Here we show that the distribution of tissue- and differentiation-stage-specific markers in retinoic acid-treated epithelium is similar to that of the oral mucosa. Moreover, when the excess retinoic acid is removed, a new epithelium is formed beneath the "old" one and this epithelium displays an epidermal orthokeratinized phenotype, whereas the "old" epithelium remains unchanged. This phenomenon of "partial reversibility", as well as the mutually exclusive distribution of the markers of the two alternative routes of differentiation, demonstrate that retinoic acid is indeed able to provoke metaplasia of adult epidermal keratinocytes.

Topics: Adult; Culture Techniques; Epithelium; Humans; Keratinocytes; Metaplasia; Phenotype; Skin; Tretinoin

We describe an animal model to induce the histogenesis of squamous metaplasia of the cervical columnar epithelium, a condition usually preceding cervical neoplasia. This model is based on dietary retinoid depletion in female mice. Control sibling mice fed the same diet but with all-trans-retinoic acid (at 3 micrograms/g diet) showed the normal endocervical epithelial and glandular columnar morphology, typical of a simple epithelium without subcolumnar reserve cells. The stratified squamous ectocervical epithelium of these mice fed all-trans retinoic acid showed intense immunohistochemical staining in basal and suprabasal cells with mono-specific antibodies against keratins K5, K14, K6, K13, and, suprabasally, with antibodies specific for K1 and K10. At the squamocolumnar junction, the adjacent columnar epithelium (termed "suprajunctional") did not show staining for K5, K14, K6, K13, K1, and K10 but specifically stained for keratin K8, typical of simple epithelia and absent from the adjacent ectocervical squamous stratified lining (termed "subjunctional"), in striking contrast. Sections of the squamocolumnar junction from mice kept on the vitamin A-deficient diet for 10 weeks showed suprajunctional isolated patches of reserve cells, proximal and distal to the junction. These cells were detected prior to any symptoms of vitamin A deficiency, such as loss of body weight or respiratory discomfort. The subcolumnar reserve cells induced by vitamin A deficiency displayed positive staining for K5 and K14. As deficiency became severe, the reserve cells occupied the entirety of the suprajunctional basement membrane. This epithelium eventually became stratified and squamous metaplastic, the squamocolumnar junction was no longer discernible, and the entire endocervical epithelium and the endometrial glands lost K8 positivity, while acquiring K5, K14, K6, K13, K1, and K10 keratins typical of the ectocervix under normal conditions of vitamin A nutriture. Vitamin A deficiency also altered keratin expression and localization in squamous subjunctional epithelium. In situ hybridization studies for K1 and K5 mRNA showed their major site of expression at the basal (K5) and immediately suprabasal (K1) cell layers. The localization of both K5 and K1 proteins in these same cell layers, and above, is consistent with transcriptional regulation of these keratins. Early vitamin A deficiency caused the appearance of single subcolumnar reserve cells expressing K5 mRNA. After these ce

Topics: Animals; Carcinoma, Squamous Cell; Cervix Uteri; Diet; Disease Models, Animal; Epithelium; Female; Immunohistochemistry; In Situ Hybridization; Keratins; Metaplasia; Mice; Mice, Inbred BALB C; Mice, Nude; Phenotype; Precancerous Conditions; Retinoids; RNA, Messenger; Tretinoin; Uterine Cervical Neoplasms; Vitamin A Deficiency

We induced vitamin A depletion to define early and late changes during the histogenesis of squamous metaplasia of hamster tracheal epithelium. An early change is the "minimal morphological change" (MMC), in which the mucociliary epithelium is separated from the basement membrane by a continuous layer of basal cells. Immunohistochemistry showed an exclusive localization of the keratins K5 and K14 in basal cells of normal and MMC epithelia. At the MMC stage no staining was observed above the basal layer with antibodies to K5, but upon progression of the lesion to a squamous focus all cells from basal to terminally differentiated were positive for K5 and K14. In contrast, when we used antibodies to the keratins K6 or K13 all cells were negative in the normal epithelium and in the MMC epithelium. Successive layers of suprabasal squamous cells found in squamous metaplasia failed to express normal epidermal differentiation marker keratins K1 and K10 but expressed the proliferation marker keratin K6 and the internal stratified epithelium keratin K13, not normally found in the epidermis or in the trachea. Hamster tracheal epithelial cells could be maintained in culture in serum-free medium for at least 4 weeks in the presence of retinoic acid (RA). In non-RA-containing medium, cells from vitamin A-deficient hamsters showed markedly reduced growth and an increase in the expression of keratins K5, K6, K13, and K14. Since our previous work had implicated retinoids in the control of cell adhesiveness, we were interested to find out whether changes in cell adhesion occur in vitamin A-deficient hamster tracheal epithelial cells, compared to normal cells. Functional assays demonstrated that hamster tracheal epithelial cells, obtained from non-RA-treated tracheas or maintained in culture, displayed reduced attachment to laminin, compared to RA-treated cells. Immunofluorescence studies did not show a decrease either in the alpha 6 integrin subunit, which was localized in the basal aspect of basal cells, or in basement membrane laminin. However, the expression of laminin-binding protein 37 decreased as the epithelium changed from pseudostratified to stratified. Therefore, a coordinated pattern of changes in keratin gene expression, as well as in the expression of laminin-binding protein 37, the precursor to the cell surface laminin receptor 67LR, and in adhesive properties takes place in tracheal epithelium when its phenotype changes from mucociliary to the preneoplastic s

Topics: Amino Acid Sequence; Animals; Antibodies; Blotting, Western; Cell Adhesion; Cell Adhesion Molecules; Cells, Cultured; Cricetinae; Epithelium; Fibroblasts; Immunohistochemistry; Keratins; Laminin; Male; Mesocricetus; Metaplasia; Molecular Sequence Data; Protein Binding; Trachea; Tretinoin; Vitamin A Deficiency

The distribution of transcripts of nuclear (RAR alpha, RAR beta, and RAR gamma) and cytosolic (CRABP) retinoic acid receptors was analyzed in 13.5-day mouse embryo upper-lip skin, cultured in vitro for 48 hr with or without added retinoic acid. The results show a significant up-regulation of the transcription of the RAR beta gene concomitant with the initiation of an alteration of hair vibrissae follicle development, leading, after transfer for 8 days to the chick embryo chorioallantoic membrane, to an exocrine-type gland morphogenesis.

Topics: Animals; Carrier Proteins; Gene Expression; Hair; Metaplasia; Mice; Nucleic Acid Hybridization; Organ Culture Techniques; Receptors, Retinoic Acid; RNA, Messenger; Skin; Skin Physiological Phenomena; Tretinoin

We have demonstrated that squamous metaplasia induced by benzo(a)pyrene (BP) in the hamster tracheal explants accompany distinct alterations in carbohydrate moieties in the epithelial mucosa. Most prominent alterations were the preferential binding of peanut agglutinin (PNA) and wheat germ agglutinin (WGA) in the basal cell layer in metaplastic lesions. In this study we examined if reversal of BP-induced lesions by all-trans retinoic acid (RA) results in the acquisition of normal carbohydrate composition by the tissue. Four lectins, PNA, WGA, Dolichos biflorus agglutinin, and Concanavalin A, in their horseradish peroxidase conjugates were used. In control explants the intercellular plasma membrane of basal and mucous cells exhibited no significant reaction with any of the lectins tested. In the metaplastic lesions induced by BP, PNA and WGA intensely stained the plasma membrane and intercellular spaces of basal and intermediate cell layers; the granular layer cells did not bind PNA whereas they were stained moderately with WGA. RA, which reversed the metaplasia, also conferred the tissue with lectin binding patterns similar to that of control explants. These results thus show that the reversal of metaplasia is accompanied by acquisition of the tissue's original carbohydrate composition.

Topics: Benzo(a)pyrene; Epithelium; Histocytochemistry; Lectins; Metaplasia; Organ Culture Techniques; Trachea; Tretinoin

To test the efficacy of topically applied tretinoin eyedrops (0.01%, twice daily, in a solution of peanut oil) in the treatment of squamous metaplasia of the conjunctival epithelium associated with dry-eye, the authors evaluated the impression cytology (IPC) of a total of 31 patients. The cytological findings were classified into four different stages with an overall range from 0 to 9 points. The average period of treatment was 12 weeks. The patients were classified into three groups: (1) Those with mucin deficiency (Mucin less than - greater than; n = 19), (2) those with Keratoconjunctivitis sicca (KSC; n = 6), and (3) a control group in whom pure peanut oil was used (n = 6). The IPC showed a considerable improvement of squamous metaplasia in the mucin less than - greater than group, by an average of 4.3 points (from 6.2 points before treatment to 1.9 points). No changes were seen in the IPC of the KCS patients or the control group. The results of this study show a good effect of tretinoin eyedrops in patients with a significant decrease in or loss of goblet cells seen in the IPC, a decreased break-up time and with no severe aqueous deficiency of tear film. These patients seem to have a "primary" mucin deficiency induced by the decrease in or loss of goblet cells. There is no indication for tretinoin treatment in patients with aqueous deficiency involving major or accessory lacrimal glands. The results of other previous and recent studies on tretinoin treatment are discussed.

Topics: Adult; Conjunctiva; Female; Humans; Keratoconjunctivitis; Keratoconjunctivitis Sicca; Male; Metaplasia; Ophthalmic Solutions; Tretinoin

N-(all-trans-Retinoyl)amino acids were synthesized via all-trans-retinoyl chloride and an ester of the amino acid. The retinoyl derivatives of leucine, phenylalanine, alanine, tyrosine, and glutamic acid were prepared. The 13-cis-retinoyl derivatives of leucine, phenylalanine, alanine, and glycine were prepared similarly from 13-cis-retinoic acid. In assays of the retinoylamino acids for reversal of squamous metaplasia in hamster trachea organ cultures, these compounds were less active than retinoic acid, but the leucine, alanine, and phenylalanine derivatives were similar in activity to several retinamides that suppress bladder carcinogenesis in vivo. Two of the retinoylamino acids, as well as two simple retinamides, were shown to be moderately cytotoxic to murine leukemia and human epidermoid carcinoma cells in culture.

Topics: Amino Acids; Animals; Cricetinae; Indicators and Reagents; Metaplasia; Organ Culture Techniques; Retinoids; Structure-Activity Relationship; Trachea

We report four cases of corneoconjunctival keratinization that were successfully treated with topical retinoic acid ointment. In two cases keratinization was due to squamous metaplasia and in two others it was secondary to intraepithelial corneoconjunctival neoplasia. Treatment reversed severe keratinization in a case of drug-induced pseudopemphigoid and stabilized the disease in one of the two affected eyes without additional treatment. In a case of ocular cicatricial pemphigoid, retinoic acid was useful as an adjuvant therapy to immunosuppression, by reversing keratinization of the conjunctiva. In two cases of corneoconjunctival neoplasia, lesions regressed markedly. Long-term treatment was well tolerated in three patients. Our findings suggest that retinoic acid ointment is effective in treating severe squamous metaplasia in cicatrizing diseases of the conjunctiva. Our findings indicate further that retinoic acid seems to inhibit growth of corneoconjunctival neoplasias and thus might be useful complementary therapy in this situation.

Topics: Administration, Topical; Aged; Aged, 80 and over; Conjunctiva; Conjunctival Diseases; Conjunctival Neoplasms; Conjunctivitis; Cornea; Corneal Diseases; Epithelium; Female; Humans; Keratins; Male; Metaplasia; Tretinoin

Topics: Administration, Topical; Aged; Biopsy; Conjunctiva; Humans; Male; Metaplasia; Remission Induction; Tretinoin

These studies were performed to follow a spectrum of relevant parameters in male Syrian golden hamsters fed either a vitamin A-deficient diet or the same diet supplemented with retinoic acid at 3 micrograms/g diet. Body weight and life span were not affected by the vitamin A-deficient diet until after 6-7 wk. Squamous metaplastic lesions of the Formalin-fixed tracheas were not generally observed in the hamsters fed the deficient diet until 6-7 wk, at which time blood retinol and liver retinyl palmitate levels had also decreased. Blood glucose levels remained normal (90 mg/dl) until about 7 wk but declined to about 40% of normal at 9 and 10 wk. Dietary retinoic acid supplementation of the vitamin-deficient diet (3 micrograms/g diet) inhibited the loss of retinol from blood and of retinyl palmitate from the liver so that these compounds were still present at 10 wk, but were not detectable in hamsters fed the vitamin A-deficient diet without retinoic acid.

Topics: Animals; Blood Glucose; Cricetinae; Diet; Diterpenes; Epithelium; Growth; Life Expectancy; Liver; Male; Mesocricetus; Metaplasia; Retinyl Esters; Trachea; Tretinoin; Vitamin A; Vitamin A Deficiency

Experiments were designed to define the ability of retinoic acid to block the estrogen-induced metaplasia in the mouse anterior prostate gland (coagulating gland), and to elucidate some of the biochemical correlates of the actions and interactions of these two compounds. In castrated mice, the estrogen-induced metaplasia of epithelial cells consisted of multi-layered, nonpolarized cells, which accumulated to fill the lumen of the acini. Retinoic acid had no discernable effect on epithelial morphology of castrates, but significantly reduced the estrogen-induced metaplasia. Likewise, the estrogen-induced increases in the prostatic wet weight, ratio of ribonucleic to deoxy ribonucleic acids (RNA/DNA) and glycosyltransferases, as well as the decreases in 21,000 and 28,000 Mr soluble proteins were prevented by retinoic acid; the retinoid had no effect on these various parameters when administered alone to castrates. In contrast, the cyclic 3',5'-adenosine monophosphate (cAMP)-dependent phosphorylations at 16,000, 18,000, and 25,000 Mr and the activities of the type II cAMP-dependent kinase were uniformly reduced by both estradiol and retinoic acid. Tests of the action of the anti-estrogen LY-156758 on estrogen and retinoid effects showed that for those parameters on which retinoic acid was anti-estrogenic, LY-156758 was also anti-estrogenic. However, the qualitatively similar effects of retinoic acid and estradiol, which were confined to selected aspects of protein phosphorylation, were not antagonized by LY-156758. It is concluded that in the mouse anterior prostate, retinoic acid has both anti-estrogenic and estrogenic actions, and the latter may occur independently of the estrogen receptor.

Topics: Animals; Castration; Drug Interactions; Enzyme Activation; Estradiol; Glucosyltransferases; Male; Metaplasia; Mice; Nucleic Acids; Organ Size; Phosphoproteins; Phosphorylation; Piperidines; Prostate; Protein Kinases; Raloxifene Hydrochloride; Tretinoin

Topics: Administration, Topical; Aged; Conjunctiva; Female; Humans; Metaplasia; Sjogren's Syndrome; Tretinoin

We have demonstrated the clinical efficacy of topical all-trans retinoic acid ointment in the treatment of four severe cases of the following dry eye disorders: Keratoconjunctivitis sicca, Stevens-Johnson syndrome, drug-induced pseudopemphigoid, surgery-induced dry eye. In all four cases, impression cytology confirmed that improvements in symptoms, visual acuity, keratopathy, and Schirmer test resulted from reversal of the process of squamous metaplasia. This treatment represents the first nonsurgical approach with action directed specifically at the diseased ocular surface epithelia.

Topics: Administration, Topical; Adult; Aged; Conjunctiva; Cornea; Female; Humans; Keratoconjunctivitis; Male; Metaplasia; Pemphigoid, Bullous; Stevens-Johnson Syndrome; Tretinoin; Xerophthalmia

Topical all trans retinoic acid (tretinoin) 0.1 per cent has been used to treat eight patients with squamous metaplasia and keratinisation of the conjunctiva. In four patients the changes followed Stevens-Johnson syndrome, one patient had chronic atopic kerato conjunctivitis, one had persistent epithelial erosions following sarcoid related kerato conjunctivitis sicca complicated by preservative induced epithelial toxicity, one had a recurrent Bowen like epithelial dysplasia and one had an unclassifiable primary ocular surface disorder. Improvement in symptoms and signs were noted in all patients but local irritation developed in some and the optimum dosage remains to be determined. Problems of formulation and stability of the preparation need to be solved before topical retinoid therapy can be more widely used.

Topics: Administration, Topical; Adolescent; Adult; Aged; Antineoplastic Agents; Conjunctiva; Conjunctival Diseases; Female; Humans; Keratoconjunctivitis; Male; Metaplasia; Middle Aged; Tretinoin

We evaluated the clinical efficacy of treating various dry-eye disorders using 0.01% and 0.1% (weight/weight) topical all-trans retinoic acid ointment. Twenty-two patients were selected and classified into four major groups: keratoconjunctivitis sicca (6 patients; 11 eyes), Stevens-Johnson syndrome (9 patients; 17 eyes), ocular pemphigoid or drug-induced pseudopemphigoid (3 patients; 6 eyes), and surgery or radiation-induced dry eye (4 patients; 4 eyes), based on the criterion that they remained symptomatic even under maximum tolerable conventional medical and/or surgical therapies. The results indicated that squamous metaplasia with mucin deficiency secondary to goblet cell loss and keratinization may be the basis for the development of clinical symptoms and morbidities, as these epithelial abnormalities were invariably present before treatment. After treatment, all patients demonstrated clinical improvements in symptoms, visual acuity, rose Bengal staining, or Schirmer test. Most importantly, this topical vitamin A treatment caused the reversal of squamous metaplasia as evidenced by impression cytology. Therefore, this treatment may represent the first nonsurgical attempt to treat these disorders by reversing diseased ocular surface epithelium.

Topics: Administration, Topical; Adolescent; Adult; Aged; Child; Child, Preschool; Eye; Female; Humans; Keratoconjunctivitis; Lacrimal Apparatus Diseases; Male; Metaplasia; Middle Aged; Ointments; Pemphigoid, Benign Mucous Membrane; Postoperative Complications; Radiotherapy; Stevens-Johnson Syndrome; Tretinoin; Visual Acuity; Xerophthalmia

Cytokinetic and ultrastructural studies were carried out to elucidate mechanisms involved in the reversal of squamous metaplasia (SM) by beta-retinoic acid in organ cultures of tracheas derived from vitamin A-deficient hamsters. Tracheal cultures exhibiting focal areas of SM were treated with the retinoid for up to 7 days. The retinoid significantly inhibited [3H]-thymidine labeling indices in the basal cells and stimulated the labeling indices in mucous cells. At the ultrastructural level the retinoid induced marked remodeling alterations in the metaplastic epithelium that included: (a) disruption of desmosomes and widening of intercellular spaces; (b) extensive vacuolation and degeneration of the metaplastic cells; (c) extrusion of the degenerated cells; (d) aggregation of keratin filaments; and (e) differentiation of certain basal cells into secretory cells. Consequently most degenerated metaplastic cells were extruded and the epithelium repopulated as a result of differentiation of basal cells into mucous cells and hyperplasia of the pre-existing mucous cells. The degenerative effects of the retinoid were limited to the metaplastic foci since the uninvolved epithelium adjoining metaplastic foci were not significantly altered. The results suggest that the restoration of normal tracheal epithelium following the retinoid treatment of explants exhibiting focal areas of squamous metaplasia is associated with the enhanced proliferation of the mucous cells. The inhibition of proliferation of basal cells further prevented hyperplasia and restored cell replication within the normal range.

Topics: Animals; Cell Differentiation; Cell Division; Cricetinae; Epithelium; Keratins; Metaplasia; Microscopy, Electron; Organ Culture Techniques; Trachea; Tretinoin; Vitamin A Deficiency

The influence of an aromatic analog of vitamin A, etretinate, on the effects of 3,4-benzpyrene and cigarette smoke condensate has been investigated in fetal mouse lung and neonatal rat tracheas grown in organ culture. In both tissues, 3,4-benzpyrene as well as cigarette smoke condensate induces a striking increase of epithelial mitosis within 12--14 days of treatment. The increase is associated with a loss of secretory activity and of ciliary function. These changes persist in the absence of benzpyrene or smoke condensate in explants transferred to control medium. Treatment with etretinate alone does not affect the normal epithelial growth rate or normal differentiation. If combined with either benzpyrene or smoke condensate, the aromatic compound inhibits the increase in cell division and prevents the loss of secretory activity or ciliary function. In explants pretreated with 3,4-benzpyrene or cigarette smoke condensate, etretinate reduces the carcinogen- or smoke condensate-induced increase in mitotic activity to normal levels and restores secretory differentiation and ciliary function. The mechanism of action involved in the anticarcinogenic activity of the retinoid is discussed.

Topics: Animals; Benzo(a)pyrene; Benzopyrenes; Etretinate; Lung; Metaplasia; Mice; Mitosis; Mutagens; Nicotiana; Organ Culture Techniques; Plants, Toxic; Rats; Smoke; Trachea; Tretinoin

Topics: Animals; Cells, Cultured; Disease Models, Animal; Haplorhini; Male; Metaplasia; Microscopy, Electron; Neoplasms, Experimental; Prostate; Testosterone; Transplantation, Homologous; Tretinoin

Twelve retinoids were evaluated in organ culture for activity in modulating epithelial differentiation of metatarsal skin explants from 13-day chick embryos. The epithelium differentiated into a squamous, keratinizing epidermis; but, in the presence of active retinoids, keratinization was inhibited, and a mucous metaplasia developed. The methyl-keto and 1-methoxyethyl cyclopentenyl analogs of retinoic acid were about tenfold more effective than retinoic acid in altering epithelial differentiation. The dichlorophenyl analog exhibited about the same activity as retinoic acid. The following analogs were one-half to one-third as effective as retinoic acid in inhibiting keratinization: the chlorotrimethylphenyl analog of retinoic acid and the 13-cis, 10-fluoro analog of trimethylmethoxyphenyl methyl retinoate. The other 7 retinoids were essentially not active at the concentration tested (1.4--2.0 x 10(-5) M). The activity of synthetic retinoids in altering epithelial differentiation may be related to their ability to affect or treat epithelial lesions provided that modification of the retinoid molecule can enhance its activity and decrease toxicity.

Topics: Animals; Cell Differentiation; Chick Embryo; Epidermal Cells; Epidermis; Epithelial Cells; Epithelium; Keratins; Metaplasia; Organ Culture Techniques; Skin; Tretinoin; Vitamin A

The influence of vitamin A-related compounds on hyperplasia and metaplasia induced by methylcholanthrene was studied in mouse prostate glands in organ culture. Methylcholanthrene was found to cause extensive hyperplasia and squamous metaplasia of the prostatic epithelium which persisted after withdrawal of the carcinogen. The retinoids included retinoic acid and 6 of its structural analogues synthesized in an attempt to enhance the anticarcinogenic action and reduce the toxicity of the parent compound. These where the cyclopentenyl analogus 7699, A2-retinoic acid, 13-cis-alpha-retinoic acid and 3 aromatic analogues. Administration of the compounds following the carcinogen reduced the extent and incidence of hyperplasia significantly and with the exception of one compound reversed the squamous metaplasia. Two of the aromatic analogues, one with a terminal ethylamide group (1430), and the other with a terminal ethylester group (9369), proved to be the most potent inhibitors, followed by compound 7699 and (9369), proved to be the most potent inhibitors, followed by compound 7699 and retinoic acid. A2-retinoic acid and 13-cis-alpha-retinoic acid showed the lowest activity. The inhibition of hyperplasia appeared to be mediated via a reduction of DNA synthesis. It seemed unrelated to either the biological growth-promoting activity of the compounds or their surface-active properties. It is tentatively suggested that vitamin A and its analogues may act as hormones.

Topics: Animals; DNA; Hyperplasia; In Vitro Techniques; Male; Metaplasia; Methylcholanthrene; Mice; Mice, Inbred C3H; Mice, Inbred Strains; Prostate; Prostatic Neoplasms; Thymidine; Tretinoin; Vitamin A