12-o-tetradeca-2-4-6-8-tetranoylphorbol-13-acetate and Skin-Neoplasms

Our research objective is to develop nontoxic cancer chemopreventive agents and to apply these agents in treating humans. We are identifying agents that inhibit the process of tumor promotion in two-stage carcinogenesis experiments on mouse skin.. We review (a) the inhibitory effect of penta-O-galloyl-beta-D-glucose (5GG) on tumor promotion by teleocidin, one of the 12-O-tetradecanoylphorbol-13-acetate (TPA)-type tumor promoters (5GG is structurally similar to (-)-epigallocatechin gallate (EGCG) and is isolated from hydrolyzed tannic acid); (b) the inhibitory effects of EGCG, the main constituent of Japanese green tea, on tumor promotion with two tumor promoters, teleocidin and okadaic acid, a non-TPA-type tumor promoter; (c) the mechanisms of action of EGCG, a single application of which reduced the specific binding of [3H]TPA and [3H]okadaic acid to a particulate fraction of mouse skin; and (d) the anticarcinogenic effects of EGCG on duodenal carcinogenesis induced by N-ethyl-N'-nitro-N-nitrosoguanidine in male C57BL/6 mice. EGCG is a nontoxic compound.. We believe that the main constituent of Japanese green tea, EGCG, is a practical cancer chemopreventive agent available in everyday life.

Topics: Animals; Anticarcinogenic Agents; Catechin; Hydrolyzable Tannins; Male; Mice; Mice, Inbred C57BL; Skin; Skin Neoplasms; Tannins; Tea; Tetradecanoylphorbol Acetate

Despite the fact that morphological and physiological observations suggest that the tight junction (TJ)-based permeability barrier is modified/disrupted in tumorigenesis, the role of members of the Claudin (Cldn) family of TJ proteins is not well-understood. Using a well-established two-stage chemical carcinogenesis model, we investigated the temporal and spatial changes in expression of those Cldns that we have previously demonstrated to be important in epidermal differentiation and the formation of the epidermal permeability barrier, i.e., Cldn1, Cldn6, Cldn11, Cldn12 and Cldn18.. The lower dorsal backskin of mice was treated topically with 7,12-dimethylbenz(a)anthracene (DMBA; 0.25 mg/ml in acetone) and following a 10-day incubation period, 12-O-tetradecanoyl-phorbol-13-acetate (TPA; 25 microg/ml in acetone) was applied three times a week to the same area. Backskin samples were dissected 2, 4, 6, 8 and 12 weeks after the initiation of the experimental protocol and immunohistochemistry was performed on sections using antibodies against the following: Cldn1, Cldn6, Cldn11, Cldn12, Cldn18, Ki67 and CD3.. Our data indicate that along with the changes in epidermal cell morphology and differentiation that occur during tumor formation, there is a dramatic change in Cldn distribution consistent with cell polarity and barrier selectivity changes. Specifically, in the early stages of DMBA/TPA treatment, the suprabasal-specific Cldns occupy an expanded zone of expression corresponding to an increased number of suprabasal epidermal cell layers. As tumorigenesis progressed, the number of suprabasal epidermal layers positive for Cldn6, Cldn11, Cldn12 and Cldn18 was reduced, especially in the lower strata of the expanded suprabasal zone. In addition, a variably reduced cell membrane association of those differentiation-specific Cldns was observed, especially within the infiltrating epidermal structures. In contrast, Cldn1 (which is normally expressed in all the living layers of the epidermis) remained restricted to the cell membrane throughout the tumorigenesis protocol. However commencing 2 weeks after treatment there was a marked decrease in the number of Cldn1-positive basal cells, and the zone of Cldn1-null epidermal cells was expanded up into the lower stratified epidermis throughout the progression of DMBA/TPA treatment. In addition, there was no Cldn1 localization in the infiltrating epidermal structures of the tumorigenic epidermis.. This is the first demonstration of the changes in Cldn expression in the progression of DMBA/TPA-induced skin tumors; however further investigation into the molecular mechanisms regulating the observed changes in barrier selectivity during tumorigenesis is required.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Carcinogens; Claudin-1; Disease Progression; Epidermis; Gene Expression; Membrane Proteins; Mice; Models, Animal; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tight Junctions; Time Factors

Fetuin, a major serum glycoprotein secreted by the liver, has been shown to play a role in bone development, calcium homeostasis and insulin sensitivity. In an earlier study, we demonstrated that bovine fetuin can bind to the plasma membrane of squamous and spindle-cell carcinoma cells. To test our hypothesis that fetuin plays a causal role in skin tumorigenesis, fetuin-A null and wild-type mice were challenged using a two-stage chemically-induced carcinogenesis protocol with DMBA (7,12-dimethylbenzo(a)anthracene) as the initiator, followed by twice weekly treatments with the tumor promoter TPA (12-O-tetradecanoylphorbol-13-acetate). Tumors that developed on fetuin-A null animals grew at a similar rate as those arising on their wild-type counterparts. Absence of fetuin-A did not alter tumor onset or conversion to squamous cell carcinoma, but reduced the number of tumors per mouse by 30%. This correlated with a decrease in tumor burden in fetuin-A null animals compared to wild-type weeks 18-22 from tumor onset. In addition, tumors arising on fetuin-A null mice had a diminished proliferative index with no change in cell survival or neovascularization in comparison with wild-type tumors. Our results suggest that fetuin-A contributes to early stages of skin tumorigenesis.

Topics: 9,10-Dimethyl-1,2-benzanthracene; alpha-2-HS-Glycoprotein; Animals; Apoptosis; Blood Proteins; Cell Proliferation; Cell Transformation, Neoplastic; Mice; Mice, Inbred C57BL; Mutation; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate

Constitutive activation of signal transducer and activator of transcription 3 (Stat3) has been found in a wide spectrum of human malignancies. Here, we have assessed the effect of Stat3 deficiency on skin tumor development using the 2-stage chemical carcinogenesis model. The epidermis of Stat3-deficient mice showed a significantly reduced proliferative response following treatment with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) because of a defect in G1-to-S-phase cell cycle progression. Treatment with the tumor initiator 7,12-dimethylbenz[a]anthracene (DMBA) resulted in a significant increase in the number of keratinocyte stem cells undergoing apoptosis in the bulge region of hair follicles of Stat3-deficient mice compared with nontransgenic littermates. Notably, Stat3-deficient mice were completely resistant to skin tumor development when DMBA was used as the initiator and TPA as the promoter. Abrogation of Stat3 function using a decoy oligonucleotide inhibited the growth of initiated keratinocytes possessing an activated Ha-ras gene, both in vitro and in vivo. In addition, injection of Stat3 decoy into skin tumors inhibited their growth. To our knowledge, these data provide the first evidence that Stat3 is required for de novo epithelial carcinogenesis, through maintaining the survival of DNA-damaged stem cells and through mediating and maintaining the proliferation necessary for clonal expansion of initiated cells during tumor promotion. Collectively, these data suggest that, in addition to its emerging role as a target for cancer therapy, Stat3 may also be a target for cancer prevention strategies.

Topics: Animals; Carcinogens; Cell Division; DNA-Binding Proteins; Epidermis; Mice; Neoplasms, Glandular and Epithelial; Skin Neoplasms; STAT3 Transcription Factor; Tetradecanoylphorbol Acetate; Trans-Activators

Squalene inhibited the effect of tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), such as increased 32Pi incorporation into phospholipids of HeLa cell membrane, induction of Epstein-Barr-virus early antigen in Raji cell and induction of ornithine decarboxylase in mouse skin. Squalene also markedly suppressed the promoting activity of TPA on skin carcinogenesis in 7,12-dimethylbenz[a]anthracene-initiated mice.

Topics: Animals; Anticarcinogenic Agents; Antigens, Viral; Cell Line; Enzyme Induction; HeLa Cells; Herpesvirus 4, Human; Humans; Membrane Lipids; Mice; Ornithine Decarboxylase; Phospholipids; Skin Neoplasms; Squalene; Tetradecanoylphorbol Acetate; Virus Activation

Keratinocyte intercellular adhesion molecule (ICAM)-I expression is induced by interferon (IFN)-gamma. It has been previously reported that IFN-beta suppresses IFN-gamma-induced ICAM-I expression in A431 cells, a human squamous cell carcinoma cell line. In this study, the suppression mechanisms were investigated at the post second messenger level. Both 12-O-tetradecanoylphorbol-13-acetate (TPA) and calcium ionophore (A23187) induce ICAM-I expression in A431 cells. ICAM-I expression induced by either was not suppressed with cotreatment with IFN-beta. Furthermore, IFN-beta did not inhibit the translocation of protein kinase C (PKC) by TPA. It appears that the pathways involved in ICAM-I expression induced by activation of PKC or increased in intracellular Ca++ are not affected by IFN-beta.

Topics: Calcimycin; Carcinoma, Squamous Cell; Cell Adhesion Molecules; Cell Line; Enzyme Activation; Humans; In Vitro Techniques; Intercellular Adhesion Molecule-1; Interferon-beta; Keratinocytes; Protein Kinase C; Second Messenger Systems; Skin Neoplasms; Tetradecanoylphorbol Acetate

Gomisin A, isolated from the fruits of Schisandra chinensis, is one of the dibenzocyclooctadiene lignans. Application of 12-O-tetradecanoylphorbol-13-acetate (TPA, 1 microgram/ear), a tumor-promoting agent, to the ears of mice induces inflammation. Among seven dibenzocyclooctadiene lignans assayed, gomisin A, gomisin J, and wuweizisu C inhibited the inflammatory activity induced by TPA in mice. The ED50 of these compounds for TPA-induced inflammation was 1.4-4.4 mumol. Gomisin A, with an ED50 of 1.4 mumol, showed the strongest inhibitory effect. Furthermore, at 5 mumol/mouse, it markedly suppressed the promotion effect of TPA (2.5 micrograms/mouse) on skin tumor formation in mice following initiation with 7,12-dimethylbenz[a]anthracene (50 micrograms/mouse). It is assumed that the inhibition of tumor promotion by gomisin A is due to its anti-inflammatory activity.

Topics: Animals; Anticarcinogenic Agents; Cyclooctanes; Dioxoles; Drugs, Chinese Herbal; Female; Inflammation; Lignans; Mice; Mice, Inbred ICR; Polycyclic Compounds; Skin Neoplasms; Tetradecanoylphorbol Acetate

There is currently a great interest in the protective potential of beta-carotene and other micronutrients against carcinogenesis. We investigated the role of beta-carotene in modifying 7,12-dimethylbenz[a]anthracene (DMBA)-initiated, 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted, two-stage skin carcinogenesis. We were interested in comparing the protective effects of two types of dietary beta-carotene, a beadlet formulation and crystalline beta-carotene, in two strains of mice (Skh:HR-1 and CR:ORL Sencar). Mice were maintained throughout the study on one of these 3% beta-carotene-fortified diets or on control diets. In Week 11 after the start of the diets, the DMBA/TPA treatment regimen was begun. The resulting skin tumors were counted weekly. In addition, serum and skin levels were monitored for beta-carotene at the time of chemical initiation and at the termination of the study. A decrease in the number of cumulative tumors in the beta-carotene-fed animals compared with the appropriate control groups was observed in both strains of mice. However, statistical evaluation of the data revealed that the decrease was significant only in Skh mice. This phenomenon might be explained by the inherent sensitivity of Sencar mice to the two-stage carcinogenesis treatment regimen. The mechanism of the protective effect found in this study is still not clear. Recent data suggest that a vitamin A pathway is not probable but that a direct 1O2 and/or radical-quenching property of the parent beta-carotene molecule may be involved. This study also demonstrates that two-stage-induced skin tumorigenesis can be modified by both types of beta-carotene-fortified diets.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; beta Carotene; Body Weight; Carotenoids; Diet; Female; Food, Fortified; Mice; Mice, Inbred Strains; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate