Prevention of Metastasis by Green Tea Polyphenols

描述（由申请人提供）：绿茶多酚（GTP）及其主要成分表没食子儿茶素-3-没食子酸酯（EGCG）与降低前列腺癌进展风险相关，并作为一种有前景的转移抑制剂出现。我们发表的研究（Gupta等人）。Proc。国家的。学会科学。美国（USA） 98:10350- 5,2001)表明，转基因小鼠（TRAMP小鼠模型（小鼠前列腺的转基因腺癌））口服绿茶多酚在遗传上易于发展为前列腺癌，在人类容易达到的剂量下，可显著抑制原发肿瘤并完全防止转移到远处器官。然而，绿茶多酚在阻断癌细胞转移过程中的作用机制仍不清楚。根据我们的初步研究结果，我们假设GTP/EGCG介导的组织金属蛋白酶抑制剂(TIMP)-3的重新表达是GTP/EGCG抑制前列腺癌细胞侵袭从而防止肿瘤转移的关键机制。TIMP-3以1:1的化学计量直接结合基质金属蛋白酶（MMP-2和-9）的催化结构域，它们是参与基底膜溶解的关键酶。低水平的TIMP-3蛋白表达与侵袭性肿瘤表型和较差的无病生存有关。在提出的具体目标1下，我们将研究GTP/EGCG激活TIMP-3并抑制前列腺癌细胞侵袭的表观遗传机制。特异性目的2将确定GTP/EGCG在体内重新激活TIMP-3和防止转移的作用。我们的假设是，在临床前模型中，体内补充GTP/EGCG可以通过组蛋白的全局修饰和TIMP-3启动子的特异性改变，有效地增加TIMP-3的表达，显著减少转移级联。我们计划在阉割的nu/nu小鼠中使用C4-2B肿瘤细胞原位植入，该肿瘤在器官中形成原发肿瘤并转移到骨骼并侵入局部组织，包括淋巴结和肝脏。这些研究将为了解GTP/EGCG在预防前列腺癌转移中的作用提供机制基础。

DESCRIPTION (provided by applicant): Green tea polyphenols (GTP) and its major constituent, epigallocatechin-3-gallate (EGCG) has been associated with reduced risk of prostate cancer progression and emerged as a promising suppressor of metastasis. Our published study (Gupta et al. Proc. Natl. Acad. Sci. USA 98:10350-5, 2001) has shown that oral consumption of green tea polyphenols by transgenic mice [the TRAMP mouse model (transgenic adenocarcinoma of the mouse prostate)] genetically predisposed to developing prostate cancer, at doses readily achievable in humans, results in significant inhibition of primary tumor and completely prevented metastases to distant-site organs. Nonetheless, the mechanism of action of green tea polyphenols in blocking the metastatic process in cancer cells remains largely unknown. Based on the results of our preliminary studies we hypothesize that GTP/EGCG-mediated re-expression of Tissue Inhibitor of Metalloproteinases (TIMP)-3 is a critical mechanism wherein GTP/EGCG inhibits invasion of prostate cancer cells thereby preventing tumor metastasis. TIMP-3 directly binds to the catalytic domain of matrix metalloproteinase (MMP-2 and -9) in 1:1 stoichiometry, which are key enzymes involved in the dissolution of basement membrane. Low level of TIMP-3 protein expression has been associated with an aggressive tumor phenotype and poor disease-free survival. Under the proposed specific aim 1 we will investigate the epigenetic mechanism(s) by which GTP/EGCG reactivates TIMP-3 and suppress invasiveness in prostate cancer cells. Specific aim 2 will determine the in vivo effects of GTP/EGCG in reactivating TIMP-3 and preventing metastasis. The hypothesis is that in vivo supplementation of GTP/EGCG could effectively increase TIMP-3 expression through global modification in histone proteins and specific alterations at the TIMP-3 promoter significantly reducing metastatic cascade in pre-clinical model. We plan to use an orthotopic implantation of C4-2B tumor cells in castrated nu/nu mice which forms primary tumor in the organ and metastasizes to the bone and invades local tissue including lymph nodes and liver. These studies will provide mechanistic basis of understanding the effect of GTP/EGCG in the prevention of prostate cancer metastasis.