Colon Cancer Inhibition by a Class of PPARgamma Agonists

描述（由申请人提供）：结直肠癌是发达国家男性和女性癌症死亡的主要原因，每年有超过100万新发病例和50万例死亡。遗传易感性仅占所有病例的15-25%，而75-85%的结肠癌是散发性的，与环境/饮食因素有关。本实验室的研究已经鉴定了一系列1，1-双（3 '-吲哚基）-1-（p-取代苯基）甲烷[C-取代二吲哚基甲烷（DIM）]，其表现出低的体内毒性，但通过激活过氧化物酶体增殖物激活受体γ（PPARy）抑制结肠肿瘤和结肠癌细胞生长。我们假设PPARy活性的C-取代的DIM代表了一类新的用于治疗结肠癌的基于机制的药物。目的1将进一步研究过氧化物酶体增殖物激活受体激活？- 依赖性的反式激活和辅激活剂招募使用一系列类似物含有对苯基和吲哚环取代基。这些和其他研究将在具有确定的分子特征的六种结肠癌细胞系中进行，包括表达野生型PPARy（HT-29）和K422 Q突变型PPARy（HCT-15）的至少两种细胞系，其对其他PPARy激动剂如罗格列酮无应答。罗格列酮和PPAR γ活性的C-取代的DIM在结肠癌细胞系中的比较生长抑制活性将被广泛研究。目标2将集中于PPARy活性C取代DIM的生长抑制机制，并基于初步研究，其似乎与细胞周期基因/蛋白（p21和细胞周期蛋白D1）和分化标志物（如小窝蛋白1和2）相关。最初的研究将集中在小窝蛋白诱导的PPARy活性的C-取代的DIM的作用，作为一个关键的途径，抑制癌细胞的生长，使用野生型和PPAR？- 通过RNA干扰灭活细胞。目的3将研究对结肠癌易感的转基因Min小鼠和携带结肠癌细胞作为异种移植物并用PPARy活性C取代的DIM治疗的无胸腺裸鼠模型中结肠肿瘤生长的抑制。拟议的研究将提供关于PPARy依赖性抑制结肠癌的机制见解，并为未来的临床研究鉴定化合物。

DESCRIPTION (provided by applicant): Colorectal cancer is a major cause of cancer deaths in men and women in developed countries, and over a million new cases and 500,000 deaths occur each year. Inherited susceptibility to colorectal cancer only accounts for 15-25% of all cases, whereas, 75-85% of colon cancer is sporadic and associated with environmental/dietary factors. Studies in this laboratory have identified a series of 1,1-bis (3'-indolyl)-l- (p-substituted phenyl) methanes [C-substituted diindolylmethanes (DIMs)], which exhibit low in vivo toxicity but inhibit colon tumor and colon cancer cell growth through activation of peroxisome proliferator-activated receptor y (PPARy). We hypothesize that PPARy-active C-substituted DIMs represent a new class of mechanism-based drugs for treatment of colon cancer. Aim 1 will further investigate activation of PPAR ? -dependent transactivation and coactivator recruitment using a series of analogs containing both p-phenyl and indole ring substituents. These and other studies will be carried out in six colon cancer cell lines with defined molecular features including at least two cell lines which express wild-type PPARy (HT-29) and K422Q mutant PPARy, (HCT-15), which are non-responsive to other PPARy agonists such as rosiglitazone. The comparative growth inhibitory activities of rosiglitazone and PPARy-active C-substituted DIMs in colon cancer cell lines will be extensively investigated. Aim 2 will focus on the mechanisms of growth inhibition by PPARy-active C-substituted DIMs and based on preliminary studies, which appear to be associated with cell cycle genes/proteins (p21 and cyclin D1) and markers of differentiation such as caveolin 1 and 2. Initial studies will focus on the role of caveolin induction by PPARy-active C-substituted DIMs as a critical pathway for inhibition of cancer cell growth using wild-type and PPAR? -inactivated cells through RNA interference. Aim 3 will investigate inhibition of colon tumor growth in transgenic Min mice that are susceptible to colon cancer and athymic nude mouse models bearing colon cancer cells as xenografts and treated with PPARy-active C-substituted DIMs. The proposed studies will provide mechanistic insights on PPARy-dependent inhibition of colon cancer and identify compounds for future clinical studies.