TIP30调控肝癌细胞自噬的作用及机制研究

Poor prognosis of patients with hepatocellular carcinoma (HCC) is largely due to the high frequency of distant metastasis and chemoresistance. Autophagy is a rapid adaptive response of cells to exogenous stress and recent studies have suggested that autophagy plays an important role in the progression and chemoresistance of cancer. However, the key regulator is still largely unknown. Recently, TIP30 was reported to have a critical role in the regulation of tumor metabolism. However, the underlying mechanisms of TIP30 involved in autophagy are hardly known in HCC progression. Based on our previous studies and relevant reports, we speculated that decreased TIP30 induced autophagy to promoted survival and chemoresistance of HCC under metabolic stress condition. In this study,we will extensively investigate the role of TIP30 involved in regulating autophagy, which impacts ATP storage and chemoresistance in cell lines and animal models. Meanwhile, we will explore the mechanisms by ChIP analysis and small RNA interfering. Finally, we intend to verify the results in clinical samples and clarify the significant correlation between TIP30 and autophagy-related protein expression with clinicopathological features. The results will provide new evidences for understanding mechnisiams of HCC progression and provide new targets for the development of effective therapeutic strategies.

肿瘤细胞通过自噬适应各种代谢压力是肿瘤进展和化疗抵抗的重要原因之一，新型抑癌基因TIP30调节肿瘤代谢的作用机制已被初步揭示，但其对肝癌细胞自噬的调节作用却知之甚少。我们通过前期工作和文献回顾，推测TIP30表达下调可促进肝癌细胞发生自噬，从而促进肝癌细胞存活、增强化疗抵抗。本项目拟开展以下研究：①通过慢病毒载体改变TIP30的表达，证明TIP30对自噬及肝癌细胞能量代谢的调节作用；②通过体内外实验，探讨TIP30调节的自噬对肝癌化疗敏感性的影响；③通过芯片分析等，明确TIP30调控自噬的分子机制；④通过临床标本分析，明确TIP30与自噬相关蛋白表达水平的相关性、二者与患者临床特征的相关性，及其作为预后的新型分子标志的可行性。本研究将从全新角度延伸TIP30在肿瘤代谢方面的作用，深化对肝癌发生发展的认识，对提高肝癌化疗敏感性有一定的指导意义，也为抗肿瘤药物研发提供新靶点和新思路。

肿瘤细胞面临各种代谢压力，自噬在肿瘤发展中的作用是研究热点。我们构建了自噬及脂代谢研究的平台，发现低氧环境下TIP30下降可促进肝癌细胞自噬，促进肿瘤存活。在乏营养环境下，TIP30对肝癌细胞自噬调节作用在不同时间点具有相反的作用，提示TIP30对自噬的调控具有双重性及复杂性。下调TIP30可促进肝癌细胞化疗抵抗，自噬抑制剂无法逆转该现象。自噬与肿瘤细胞能量代谢密切相关。芯片分析发现TIP30参与了肝癌脂代谢。体内外研究发现，下调TIP30可通过促进AKT和 mTOR的磷酸化来促进SREBP1的表达和核聚集，促进HCC细胞脂代谢及生长。通过数据库挖掘及临床标本分析，我们发现 SREBP1和TIP30表达负相关，联合检测SREBP1和TIP30可较好地预测HCC预后。本项目从现象、功能和机制学等方面进探讨了TIP30对肝癌细胞自噬及代谢的调节作用，延伸了TIP30 在肿瘤代谢领域的抑癌作用，为药物研发提供新靶点。