Identification of Green Tea Polyphenol-Targeted Genes

描述（由申请人提供）：绿茶多酚似乎对某些癌症具有化学预防作用，包括口腔癌；但是癌细胞是如何在暴露于多酚的情况下死亡而正常细胞却存活下来的还不清楚。这些信息的缺乏阻碍了多酚在口腔癌化学预防或治疗中的临床应用。本研究的长期目标是阐明绿茶多酚不同作用于正常细胞和恶性细胞的信号通路和机制，以直接保护或凋亡细胞。我们实验室的初步数据表明，正常上皮细胞表达p57 (KIP2)，以剂量和时间依赖的方式响应绿茶多酚。我们提出了一个新的概念，绿茶多酚能够激活两条途径：1)p57介导的生存途径，和/或2)caspase 3依赖的凋亡途径。我们的假设是绿茶多酚在正常上皮细胞中诱导p57可能具有抗凋亡功能，在恶性细胞中缺乏p57反应可能导致诱导caspase 3依赖性凋亡。本研究的直接目标是确定受绿茶多酚调节的存活或凋亡基因。在这个拟议的项目中，将确定绿茶多酚暴露后正常人表皮角质形成细胞和人口腔鳞状细胞癌细胞的存活/凋亡基因表达谱。具体来说，将确定最有效的绿茶多酚(-)-表没食子儿茶素-3-没食子酸酯（EGCG）在正常人类上皮细胞中诱导的p57表达水平。通过RT-PCR、mRNA稳定性分析、Northern和Western blot分析，建立p57诱导的转录/翻译水平与EGCG时间/剂量之间的关系。特定时间点的RNA样本将进行基因阵列分析和谱分析。不仅可以确定正常细胞或肿瘤细胞中被EGCG激活或抑制的基因的表达谱，还可以确定未来化疗干预的有希望的细胞靶点。这项提议产生的数据可能揭示头颈癌治疗的新药物靶点。

DESCRIPTION (provided by applicant): Green tea polyphenols appear to be chemopreventive against certain cancers, including oral cancer; but how cancer cells succumb while normal cells survive this polyphenol exposure is not known. Lack of this information prevented clinical uses of polyphenols for oral cancer chemoprevention or treatment. The long-term goal of this investigation is to elucidate the signal pathways and mechanisms by which green tea polyphenols differentially target normal and malignant cells to direct protective or apoptotic effects. Preliminary data from our laboratories have demonstrated that normal epithelial cells express p57 (KIP2) in response to green tea polyphenols in a dose- and time-dependent manner. We propose a novel concept, that green tea polyphenols are able to activate two pathways: 1) a p57-mediated survival pathway, and/or 2) a caspase 3-dependent apoptosis pathway. The hypotheses to be tested is that p57 induction by green tea polyphenols in normal epithelial cells may serve an anti-apoptotic function, absence of the p57 response in malignant cells may result in induction of caspase 3-dependent apoptosis. The immediate goal of this proposal is to identify the survival or apoptotic genes that are regulated by green tea polyphenols. In this proposed project, the survival/apoptosis gene expression profile will be determined following green tea polyphenol exposure, in normal human epidermal keratinocytes and in human oral squamous cell carcinoma cells. Specifically, the levels of p57 expression induced by the most potent green tea polyphenol, (-)- epigallocatechin-3-gallate (EGCG), in normal human epithelial cells will be determined. Using RT-PCR, mRNA stability assay, Northern and Western blot analyses, the relationship between transcription/translation levels of p57 induction and the time/dose of EGCG will be established. The RNA samples at specific time points will be subjeted to gene array analysis and profiling. Not only will the expression profile of those genes that are either activated or suppressed by EGCG in normal or tumor cells, but promising cellular targets for future chemotherapeutic intervention may be identified. Data generated from this proposal may reveal novel drug targets for treatment of head and neck cancer.