Combined Natural Inhibitors in Skin Cancer Prevention

描述（由申请人提供）：本提案的总体目标是确定已知抑制皮肤致癌的一个或多个阶段的天然来源化合物的协同作用机制，即，启动和晋升/进展。我们的假设是，同时局部和全身（即，饮食）与皮肤癌发生的不同阶段的所选天然来源抑制剂的治疗产生协同效应，导致更有效地预防皮肤癌。待测试的抑制剂包括鞣花酸、原花色素B-2-没食子酸酯、N-乙酰半胱氨酸、D-葡糖二酸钙、番茄红素、来自迷迭香提取物的熊果酸和白藜芦醇。我们建议首先利用一些非常具有预测性的短期体外和体内试验，以确定机制，并在标准条件下区分不同浓度下选定抑制剂的效力。最有效的化合物将在长期肿瘤实验中进行研究，在SENCAR小鼠中使用7，12-二甲基苯并[a]蒽（DMBA）引发的12-O-十四酰基佛波醇-13-乙酸酯（TPA）促进的多阶段致癌模型，在SKH-1小鼠中使用紫外线（UV）引发的TPA促进的多阶段致癌模型。最后，将在SENCAR小鼠的DMBA引发、TPA促进的皮肤致癌模型以及SKH-1小鼠的UV引发、TPA促进的皮肤致癌模型中测试最佳抗引发剂和抗肿瘤促进剂的组合。（i）使用各种非常具有预测性的短期体外和体内试验，包括SENCAR小鼠中DMBA诱导的炎症-增生测定和SKH-1小鼠中UV诱导的乳腺增生测定，鉴定最有希望的抗起始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方式，即，局部vs.全身（饮食）;（ii）在SENCAR小鼠中使用DMBA引发、TPA促进的多阶段皮肤癌发生模型分析所选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，以更好地理解它们的作用机制并预测它们在以下组合研究中的表现;（iii）研究在目的1和2中鉴定的最佳抗引发剂和抗肿瘤促进剂对SKH-1小鼠中UV引发、TPA促进的多阶段皮肤癌发生的长期抑制作用，以便在化学诱导的和UV诱导的小鼠皮肤致癌作用数据库之间建立桥梁;（iv）检查机械上不同的抗引发剂和抗肿瘤促进剂的各种组合以及它们的递送手段的各种组合，即，局部相对于全身（饮食），抑制SENCAR小鼠中DMBA引发的TPA促进的皮肤致癌作用以及SKH-1小鼠中UV引发的TPA促进的皮肤致癌作用，目的是发现所选天然来源抑制剂的最显著的协同作用。

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.