去甲斑蝥素抑制HIF-1α/2α和IRS-1逆转肾癌雷帕霉素类似物耐药的机制

Rapalogs targeting mTORC1 have greatly improved the survival of patients with metastatic renal cell carcinoma (mRCC) characteristic of insensitivity to conventional radiation and chemotherapy. However, development of resistance to existing rapalogs represents a big obstacle for the treatment of mRCC. Our study show norcantharidin (NCTD) can not only arrest cell cycle in G1 phase, inhibit proliferation, invasion and migration, but also can induce apoptosis in renal cell carcinoma cell lines. Western blot and qPCR results indicate NCTD reduces the protein expression of HIF-1α and HIF2α and down-regulates pro-angiogenic factors, such as VEGF, PDGF and Ang2 in mRNA level. Accordingly we postulate that the anti-tumor mechanism of NCTD is involved in suppressing both mTORC1 and mTORC2 pathway. Furthermore, we found NCTD can decrease mRNA level of IRS1, which is a crucial factor in. Therefore, we speculate NCTD may reverse resistance of mTORC1 inhibition by inhibiting mTORC1/2-HIF1α/2α and restore the IRS1/PI3K/Akt-associated negative feedback loop of mTORC1 inhibition. In this project, we aim to explore the antitumor mechanism of NCTD against RCC and its potential synergistic effect with rapalogs by reversing drug resistance to rapalogs in vitro and in vivo，providing a new way of treating mRCC.

肾癌具有对传统放化疗不敏感的特性，以mTORC1为靶点的雷帕霉素类似物（Rapalogs）显著地提高了转移性肾癌的生存期，但其耐药成为转移性肾癌治疗的巨大障碍。前期研究发现，去甲斑蝥素（NCTD）能够阻滞肾癌细胞于G1期、抑制增殖，减弱迁移、侵袭能力，诱导其凋亡；而且，NCTD可减少肾细胞癌中HIF-1α、HIF2α的蛋白表达，降低VEGF、Ang2、PDGF的mRNA水平，推测其抗肾癌机制可能是同时抑制mTORC1-HIF1α和mTORC2-HIF2α 轴；此外，NCTD还可以降低mTORC1负反馈通路中IRS1的mRNA水平，极有可能NCTD能够通过mTORC1/2-HIF1α/2α通路和IRS1-PI3K/Akt负反馈逆转Rapalogs 耐药。本项目拟通过体内外实验探索NCTD与Rapalogs协同抗肾癌、逆转其耐药的作用及机制，为晚期肾癌的治疗提供新的思路。