p66Shc与雌激素依赖性结肠癌细胞增殖调控相关性的研究

Estrogen is considered to play important roles in the tumorigenesis and progression of colon cancer. However, the mechanism of estrogen in colon cancer is still unclear. Our previous studies showed that similar to that in hormone-dependent prostate cancer，the expression of hormone receptor, p66Shc protein were overexpressed in colon cancer. Adaptor protein p66Shc and ROS were upregulated by steroid hormones in hormone-dependent cancer, which was correlated with the steroid hormone-stimulated cell proliferation. And expression of p66Shc protein was significantly correlated with histological grading of colon cancer. Therefore, we hypothesized that estrogen plays an important role in the steroid hormone sensitive colon cancer. Estrogen upregulated the expression of p66Shc through estrogen receptor activation. Increased p66Shc generates ROS production. Increased ROS production promotes cell cycle progression, through Cyclin D1 and, which in turn, increases cell proliferation. First, this research will detect the molecular mechanism of p66Shc-ROS pathway induced by estrogens (E2) in colon cancer cell proliferation by gene transfection and RNA interference. Second, the results will be further confirmed by clinical investigations. Detected by immunohistochemistry, this research will investigate the p66Shc expression as well as 8-OHdG expression of tissue and the corresponding adjacent non-cancerous tissue in colon cancer, and their relationship with AJCC stage and clinicopathlolgical characteristics of colon cancer. Our study is of great significance on illustration the mechanism of estrogen on p66Shc expression and molecular mechanism of p66Shc in colon cancer induction. The study findings will help to provide a theoretical basis for endocrine therapy to colon cancer and find p66Shc protein- a new tumor marker in colon cancer.

雌激素在结肠癌的发生发展中起重要作用，但具体作用机制不清。我们前期工作发现，与激素依赖性肿瘤-前列腺癌相似，结肠癌中也有激素受体(ER)和p66Shc高表达，雌激素可上调p66Shc和产生ROS并促进细胞增殖,且p66Shc的表达与肿瘤病理分级正相关。据此提出假说：雌激素通过作用ER上调p66Shc 的表达水平，p66Shc通过调节胞内ROS生成使CyclinD1过表达，从而促进结肠癌细胞的增殖。通过基因转染、RNA干扰方法探讨p66Shc-ROS信号通路在雌激素促结肠癌细胞增殖中的作用机制，并对上述结果进行临床论证，探讨p66Shc和8－OHdG的表达与AJCC分期、癌分化程度及临床进展的相关性，为结肠癌的内分泌治疗提供理论基础，使p66Shc有望成为新的结肠癌肿瘤标志物。

结肠癌是人类高发恶性肿瘤，雌激素与结肠癌的发生发展密切相关，但其具体作用机制不清。雌激素能否促进或抑制结肠癌的增殖目前仍有争议。本项目研究发现与激素依赖性肿瘤-前列腺癌相似，结肠癌中也有激素受体（ERα和ERβ）和p66Shc高表达以及活性氧（ROS）的产生，p66Shc-ROS信号通路在雌激素促进结肠癌细胞增殖中发挥作用。对于 结肠癌细胞株HCT8，雌激素可以通过作用ERβ上调p66Shc的表达水平，使胞浆中的p66Shc聚集到线粒体产生ROS, 通过调节胞内ROS生成使CyclinD1过表达，从而促进结肠癌细胞的增殖。结肠癌细胞株HT29对于雌激素的促细胞增殖作用不明显，结肠癌细胞株Colo320对激素的促细胞增殖作用不应答。可能因为对有些结肠癌细胞株，雌激素通过ERβ通道诱导细胞增殖；有些结肠癌细胞株，雌激素可能是通过ERα途径来诱导增殖的, 因为这些细胞株不表达ERα而无法诱导。免疫组化的方法亦检测出人结肠癌组织中ER和p66Shc的表达明显高于癌旁组织，p66Shc的表达与肿瘤病理分级呈正相关，而与患者的年龄、性别、原发肿瘤部位、大小、病理大体类型、组织类型、肠壁浸润、淋巴结转移无明显相关性。该研究为临床内分泌治疗结肠癌提供理论依据，使p66Shc有望成为一种新的早期诊断、预后判断的结肠癌肿瘤标记物。