P53蛋白调节mTOR信号通路诱导胰腺癌吉西他滨耐药的机制研究

Gemcitabine mono-chemotherapy is the standard first-line regimen for advanced pancreatic cancer, however,the efficiency is poor. Drug resistance is considered ad one of the most important factors responsible for the failure of Gecitabine chemotherapy in pancreatic cancer, but the mechanism of drug resistance is not clear. Apoptosis and autophagy mediated by signal pathway of mTOR involved in process of drug-resistance of tumor, and p53 mediates cross-talk between apoptosis and autophagy. As a famous apoptotic factor, p53 not only mediates cell apoptosis, but also associates with autophagy by regulating mTOR signal pathway. Studies showed that in order to satisfy requirement of tumor growth, p53 can express and mediate autophagy of tumors by regulating signal pathway of AMPK/mTOR. In the preliminary stage of tumors, tumor cells express high-level of p53, thereby, reduce autophagy and promote proliferation by regulating signal pathway of AMPK/mTOR. In the stage of overgrowth and malnutrition, tumor cells express low level of p53 and induce autophagy for requirement of nutrition by inhibition of AMPK/mTOR signal pathway. But when chemotherapy, there are a lot of tumor cells in apoptosis induced by chemical drugs, autophagy is in level of high expression, and the level decides growth of unapoptotic tumor cells and associate with drug-resistance. Unapoptotic tumor cells enhance existent ability by engulfing apoptotic cells and then absorbing the energy and nutritions.This phagocytosis plays an important role in drug-resistance. Therefore,our protocol intends to establish pancreatic cell and animal models resisted to Gemcitabine, validate autophagy is associated with drug-resistance of Gemcitabine for pancreatic cancer. By analyzing expression of p53 protein, mTOR, AMPK, sestrin proteins in drug-resistant cells and animal models, we aid to validate signal pathway of p53/AMPK/mTOR involve drug-resistance of Gemcitabine for pancreatic cancer. The protocol provides a new attempt for the research of drug-resistance of Gemcitabine for pancreatic cancer .

吉西他滨单药治疗胰腺癌有效率低与多药耐药有关。mTOR信号通路介导的凋亡及自噬参与肿瘤的耐药形成。研究表明，p53作为促凋亡因子也可通过调节AMPK/mTOR信号通路表达介导肿瘤的自噬，参与调节肿瘤生长、增殖、以及耐药。在肿瘤初期，肿瘤细胞高表达p53激活AMPK/mTOR信号通路抑制自噬促进增殖；过度生长营养不足时，p53低表达抑制AMPK/mTOR信号通路诱发自噬保持营养需求。但肿瘤化疗时由于药物作用始终有大量凋亡肿瘤细胞产生，自噬处于相对高表达状态，其水平高低决定未凋亡肿瘤细胞的生长，与耐药有关。本项目拟运用新方法构建胰腺癌吉西他滨耐药模型，分析p53蛋白、mTOR、AMPK在不同耐药潜能细胞及模型内的表达差异，验证AMPK/mTOR与胰腺癌吉西他滨耐药的相关性；并通过p53蛋白调节及sestrin干扰试验验证p53/AMPK/mTor通路的调控机制。从而丰富肿瘤耐药机制的研究。

吉西他滨单药治疗胰腺癌有效率低与多药耐药有关。mTOR信号通路介导的凋亡及自噬参与肿瘤的耐药形成。本项目运用体外培养体内诱导循环筛选的新方法构建胰腺癌吉西他滨耐药模型，分析了Aurora-A蛋白（p53蛋白前体）在不同耐药潜能细胞及模型内的表达差异，明确了苦参碱这一中药单体在诱导耐药或逆转耐药方面无明确作用； 筛选出PPP5C这一胰腺癌吉西他滨耐药相关基因，并深入研究了PPP5C在p-p53、p-JNK、caspase和PARP介导凋亡的机制。研究了mTOR、AMPK在胰腺癌吉西他滨耐药模型的表达；验证了p53/AMPK/mTor通路的调控机制。研究表明p53/AMPK/mTor自噬通路和PPP5C基因与胰腺癌吉西他滨耐药有关，但具体机制及相互的调控机理还需深入研究。