Combined Natural Inhibitors in Skin Cancer Prevention

描述(申请人提供)：本提案的总体目标是确定天然来源化合物协同作用的机制(S)，已知的抑制皮肤癌变的一个或多个阶段，即启动和促进/进展。我们的假设是，在皮肤癌发生的不同阶段，同时使用选定的天然来源抑制剂进行局部和全身(即饮食)治疗会产生协同效应，从而更有效地预防皮肤癌。被测试的抑制剂包括鞣花酸、原花青素B-2-没食子酸酯、N-乙酰半胱氨酸、D-葡萄糖酸钙、番茄红素、迷迭香提取物中的熊果酸和白藜芦醇。我们建议最初利用一些非常具有预测性的短期体外和体内试验，以确定其作用机制(S)，并在标准条件下区分不同浓度的选定抑制剂的效力。然后，将利用7，12-二甲基苯并[a]菲(DMBA)启动的、12-O-十四酰佛波醇-13-乙酸酯(TPA)促进的Sencar小鼠的多阶段癌变模型和紫外线(UV)启动的TPA促进的SKH-1小鼠的多阶段癌变模型，在长期肿瘤实验中研究最有效的化合物。最后，最好的抗启动剂和抗肿瘤促进剂的组合将在DMBA引发的TPA促进的Sencar小鼠皮肤癌模型以及紫外线引发的TPA促进的SKH-1小鼠皮肤癌模型中进行测试。将研究以下特定目标：(I)使用各种非常具有预测性的短期体外和体内试验，包括DMBA诱导的Sencar小鼠炎症-增殖试验和SKH-1小鼠的紫外线诱导的红斑-增殖试验，鉴定最有希望的抗启动和抗肿瘤促进机制以及最有效的天然来源抑制剂及其递送手段，即局部与全身(饮食)；(Ii)利用DMBA引发、TPA促进的Sencar小鼠多阶段皮肤癌变模型，分析选定的、有希望的天然来源抑制剂的长期抗引发和抗肿瘤促进作用，以更好地了解它们的作用机制(S)，并预测其在以下联合研究中的表现；(Iii)研究AIMS 1和2中确定的最佳抗引发剂和抗肿瘤促进剂对紫外线引发、TPA促进的SKH-1小鼠多阶段皮肤癌变的长期抑制作用，以建立化学诱导和紫外线诱导小鼠皮肤癌变数据库之间的桥梁；(Iv)研究机制上不同的抗启动剂和抗癌促进剂的各种组合，以及它们的不同给药方式，即局部和全身(饮食)如何抑制DMBA引发的、TPA促进的Sencar小鼠皮肤癌以及紫外线引发的TPA促进的SKH-1小鼠的皮肤癌，以期发现选定的天然来源抑制剂的最显著协同作用。

DESCRIPTION (provided by applicant): The overall goal of this proposal is to determine the mechanism(s) of synergistic action of the natural source compounds, known to inhibit one or more stages of skin carcinogenesis, i.e., initiation and promotion/progression. Our hypothesis is that concurrent topical and systemic (i.e., dietary) treatment with selected natural source inhibitors of different stages of skin carcinogenesis result in synergistic effects leading to more efficient prevention of skin cancer. The inhibitors to be tested include ellagic acid, proanthocyanidin B-2-gallate, N-acetylcysteine, calcium D-glucarate, lycopene, ursolic acid from rosemary extract, and resveratrol. We propose to initially utilize a number of very predictive short-term in vitro and in vivo tests in order to identify the mechanism(s) and to differentiate the potencies of selected inhibitors at various concentrations under standard conditions. The most effective compounds will then be studied in long-term tumor experiments utilizing a 7,12-dimethylbenz[a]anthracene (DMBA)-initiated, 12-O-tetradecanoylphorbol-13-acetate (TPA)- promoted multistage carcinogenesis model in SENCAR mice and an ultraviolet light (UV)-initiated, TPA-promoted multistage carcinogenesis model in SKH-1 mice. Finally, combinations of the best anti-initiating and anti-tumor promoting agents will be tested in the DMBA-initiated, TPA-promoted skin carcinogenesis model in SENCAR mice as well as in the UV-initiated, TPA-promoted skin carcinogenesis model in SKH-1 mice. The following Specific Aims will be studied: (i) identification, using various very predictive short-term in vitro and in vivo tests, including the DMBA-induced inflammatory-hyperplasia assay in SENCAR mice and the UV-induced erythema-hyperplasia assay in SKH-1 mice, the most promising mechanisms of anti-initiation and anti-tumor promotion as well as the most effective natural source inhibitors and their delivery means, i.e., topical vs. systemic (dietary); (ii) analysis of the long-term anti-initiation and antitumor promoting effects of the selected, promising natural source inhibitors using the DMBA-initiated, TPA-promoted multistage skin carcinogenesis model in SENCAR mice to better understand their mechanism(s) of action and predict their performance in the following combination studies; (iii) studying the long-term inhibitory effects of the best anti-initiators and anti-tumor promoters identified in Aims 1 and 2, on UV-initiated, TPA-promoted multistage skin carcinogenesis in SKH-1 mice, in order to establish a bridge between the chemically induced and UV-induced mouse skin carcinogenesis data bases; (iv) examining how various combinations of mechanistically different anti-initiators and antitumor promoting agents and also how various combinations of their delivery means, i.e., topical vs. systemic (dietary), inhibit DMBA-initiated, TPA-promoted skin carcinogenesis in SENCAR mice as well as UV-initiated, TPA-promoted skin carcinogenesis in SKH-1 mice, with the view of discovering the most pronounced synergistic effects of the selected natural source inhibitors.