炎症因子通过Rictor调控肾癌转移的机制研究

Chronicle inflammation is closely associated with tumorigenesis and metastasis of renal cell carcinoma (RCC) while metastasis is the major cause of morbidity and mortality in RCC patients. Extensive reports have demonstrated that chemotaxis plays a critical role in metastasis. However, the molecular mechanism of RCC cell chemotaxis and metastasis is largely unknown. Our preliminary study revealed that the expression of Rictor, a key component of mTORC2,was closely associated with lymph node metastasis and distant metastasis. Knockdown Rictor in ACHN, a RCC cell line,impaired chemotaxis, suggesting a critical role of Rictor in RCC migration. Phosphoproteosomic analysis of Rictor knockdown cell line revealed changes of a set of cytoskeleton proteins, further indicating the role of Rictor in chemotaxis. Treatment with TNFα, a proinflammatory cytokine,enhanced the expression of Rictor in ACHN, suggestting a role of inflammation in promoting cell migration. Thus, we hypothesize that TNFα regulates the expression of Rictor, which plays a critical role in RCC chemotaxis and metastasis. To test this hypothesis,we will investigate the molecular mechanism of TNFα promoted Rictor expression and the molecular mechanism of Rictor-mediated RCC metastasis.

慢性炎症与肾癌的恶化转移密切相关，而转移是影响肾癌治疗效果、造成患者死亡的重要原因。大量文献显示趋化运动在肿瘤转移中起着关键作用，而肾癌细胞趋化运动的分子机理依然缺乏研究。我们在前期研究中发现Rictor在肾癌组织中高表达，并与淋巴结及远端转移等密切相关。用促炎因子TNFα刺激后，肾癌细胞中Rictor的蛋白表达水平显著升高。在肾癌细胞系中抑制Rictor表达后能明显抑制细胞的趋化运动。因此我们推测促炎因子TNFα调控Rictor表达，而Rictor是调控肾癌趋化运动和转移的重要信号分子。为证实此假设，本项目拟在前期工作基础上，通过体外细胞学实验、免疫缺陷小鼠癌转移模型、蛋白组学及患者组织样本深入探讨TNFα调控Rictor表达的分子机制，Rictor在肿瘤转移中的功能，揭示Rictor下游信号分子网络，探索其作为治疗肿瘤转移药物靶点的潜在可能性。

转移是影响肾癌治疗效果、造成患者死亡的重要原因。慢性炎症与肾癌的恶化转移密切相关，前期数据显示促炎因子TNFα可能通过促进Rictor的表达，进而影响肾癌细胞的侵袭转移。我们研究发现Rictor在肾癌中表达明显增高，而且与患者出现淋巴结转移和远处转移以及生存时间明显相关；细胞学实验证实Rictor降表达抑制了肾癌细胞ACHN的运动及侵袭能力，小鼠体内实验证实Rictor降表达抑制了小鼠肿瘤生长和转移；促炎因子TNFα诱导后，肾癌细胞系ACHN中Rictor表达水平升高，细胞的运动及侵袭能力增强，而Rictor降表达后抑制了TNFα对转移的促进作用，进一步机制研究显示TNFα能够通过NFκB通路直接调控RICTOR的转录；通过磷酸化定量蛋白组学分析了Rictor下游分子，发现了Rictor能够通过53BP1蛋白参与DNA损伤修复过程，机理研究显示Rictor可能通过调控Akt活性及CDK1间接影响53BP1的磷酸化及其生物学功能。总之，我们的结果提示Rictor有望发展成为肾癌转移及预后的标志物、治疗肾癌转移的药物靶标，以及肾癌个体化治疗的靶点。