DDR2在炎症信号通路IL-6/STAT3/ACK1介导肝癌发生中的作用及机制

Hepatocellular carcinoma (HCC) is one of the most common malignant tumor in China. Our previous study have shown that the expression of DDR2 and ACK1 were obviously higher in HCC tissues than that in non-tumor tissues and DDR2 may be a downstream target of ACK1, but the role and mechanisms are still unknown. Previous studies have shown that inflammation plays a key role in the hepatocarcinogenesis. As an important inflammatory factor, IL-6 can promote the hepatocarcinogenesis by regulating the downstream pathway IL-6/STAT3, but the exact mechanism of IL-6-associated hepatocarcinogenesis still remains unclear. In our present project, we try to determine whether DDR2 acts as a downstream target of IL-6/STAT3/ACK1 inflammatory signaling pathway, and IL-6/ACK1 signaling can activate the downstream ERK and AKT signaling pathways by regulating DDR2, and promote EMT and up regulation of BAD, Caspase9 and FKHRL1 phosphorylation. Furthermore, we attempt to elucidate the molecular mechanism of DDR2 in the hepatocarcinogenesis mediated by inflammation. The aim of this study is to investigate the molecular mechanisms of DDR2, in order to provide the scientific basis to exploit novel targeting agents and predictive biomarkers for HCC patients.

肝细胞癌是我国常见恶性肿瘤之一。我们前期研究证实DDR2和ACK1在肝癌中存在过表达现象，且DDR2可能是ACK1的下游因子，但具体作用机制不明。既往研究表明IL-6作为一个重要炎症因子，可以通过调控下游IL-6/STAT3通路进而促进肝癌的发生。我们的前期工作也发现IL-6/STAT3通路可以上调ACK1的表达，但其在HCC中具体机制以及如何通过下游因子调节 HCC 生长和转移的，目前仍不清楚。本研究是对既往工作的深入，拟通过组织学及体内外实验证实DDR2是炎症信号通路IL-6/STAT3/ACK1的一个下游靶点，IL-6/STAT3/ACK1通路可以通过调控DDR2进而激活下游ERK、AKT信号通路，促进EMT及上调BAD、Caspase 9和FKHRL 1磷酸化水平，从而参与HCC的发生发展。本项目将为HCC的靶向治疗及诊断预后标志物的发现提供实验依据。

肝细胞肝癌（Hepatocellular carcinoma,HCC）是我国常见恶性肿瘤之一，预后差，特别是中晚期肝癌，靶向治疗是延长其生存期有效方法。我们实验中发现DDR2和ACK1在肝癌样品中显著高表达，并已成功构建下调DDR2表达的HepG2shDDR2细胞和下调ACK1表达的HepG2shACK1细胞，WB试验发现DDR2与ACK1具有正相关性。同时我们还发现DDR2在索拉非尼耐药性肝癌组织中高表达。索拉非尼是第一个被FDA批准用于中晚期HCC治疗的靶向治疗药物，然而临床应用过程中常出现索拉菲尼耐药。本研究以DDR2调控NF-κB/c-Rel信号通路参与索拉菲尼耐药的分子机制为主线开展科学研究。采用qPCR和免疫印迹法检测HCC组织和细胞系中DDR2的表达情况；采用MTT、集落形成、TUNEL和流式细胞检测DDR2对索拉非尼耐药性的影响；通过荧光素酶报告基因检测DDR2对NF-κB信号通路的影响；采用基因组DNA定量PCR检测DDR2 DNA扩增情况。结果：①相对于索拉非尼敏感性肝癌组织，DDR2在索拉非尼耐药的肝癌组织中表达显著上调；②DDR2下调增强HCC细胞对索拉非尼的敏感性；③DDR2可以促进NF-κB亚基REL的核转位，从而激活NF-κB信号通路；④DDR2的DNA扩增是导致DDR2在肝癌中过表达的可能机制。本研究为预测肝癌索拉非尼敏感性以及抵抗性提供新的理论依据，寻找新型治疗靶点，最终提高肝癌病人的生存率。