肝癌相关成纤维细胞通过HGF/MiR-125a/ATG4D途径诱导肝癌耐药的机制研究

The emergence of chemoresistance continues to be an obstacle for the successful treatment of hepatocellular carcinoma. Tumor microenvironment facilitates the acquisition of acquired drug resistance. In our previous study, we proved that as the major component of tumor microenvironment -carcinoma associated fibroblast (CAF) could promoted HCC cell proliferation and suppressed the activation of NK cells to create a favorable immunosuppressive shield for HCC cells. Furthermore, we found that CAF could induce chemoresistance of HCC cells by secreted hepatocyte growth factor (HGF) which regulating MiR-125a down-expression, and the expression of MiR-125a is relatively associated with an increased autophagy levels and decreased apoptosis induced by chemotherapy drugs. Based on our previous findings, research will be focus on MiR-125a and its target protein ATG4D, to further study their effect on the interrelationship between apoptosis and autophagy. We hope to identify the central players and confirm the pathway that involves HGF/MiR-125a/ATG4D in mediating drug resistance in hepatocellular carcinoma. These results will help to elucidate the mechanism between tumor microenvironment, epigenetics and HCC chemoresistance and to facilitate targeted therapy design based on HGF/MiR-125a/ATG4D pathway.

肝癌耐药一直是临床上亟须解决的难题之一，肿瘤微环境被认为是肿瘤耐药产生的重要原因。我们前期研究证实肝癌微环境中的肝癌相关成纤维细胞（CAF）可以促进肝癌生长（Plos One，2013）和免疫逃逸（Cancer Letters, 2012），同时也是肝癌获得性耐药的主要“推动者”。CAF通过旁分泌肝细胞生长因子（HGF）作用于肝癌细胞，引起MiR-125a表达下调导致凋亡减少和自噬增加进而诱导肝癌耐药（见工作基础），但具体的分子调控机制尚不清楚。故本课题拟从MiR-125a及其靶蛋白ATG4D入手，结合凋亡、自噬相关通路，明确HGF/MiR-125a/ATG4D途径在CAF诱导肝癌耐药过程中的信号调控网络，找到其中的关键调控节点，并在临床水平上验证。该机制的阐明，不仅有助于从表观遗传学角度更清楚地探究肝癌微环境对肝癌耐药的调控机制，也为基于上述信号途径为靶点的抗肿瘤新药的研发提供理论依据。

肝癌耐药一直是临床上亟须解决的难题之一，肿瘤微环境被认为是肿瘤耐药产生的重要原因。前期已证实肝癌微环境中的肝癌相关成纤维细胞（CAF）可以促进肝癌生长和免疫逃逸，并且还促进了肝癌耐药的发生，但是其中机制尚不清楚。故本课题从MiR-125a及其靶蛋白ATG4D入手，结合凋亡、自噬相关通路阐明其中机制。首先我们在体内外实验中证实CAF可以显著增加肝癌对顺铂、多柔比星、索拉菲尼等证明对肝癌有效药物的抵抗性，进一步通过研究CAF诱导的肝癌细胞miRNA谱变化，发现miR125a-5p与其直接调控的靶点ATG4D参与的自噬过程是肝癌耐药的关键，接着我们发现CAF分泌的细胞因子IL6、HGF通过改变肝癌细胞内蛋白15-PGDH的活性影响了自噬通路的激活，通过过表达或干扰的手段改变15-PGDH 的表达水平可以显著改变细胞自噬与细胞凋亡的发生，因此我们认为CAF是通过miR125a-5p/ATG4D以及IL6/HGF/15-PGDH共同调控肝癌细胞自噬而参与到肝癌耐药过程的。该机制的阐明，不仅有助于从表观遗传学角度更清楚地探究肝癌微环境对肝癌耐药的调控机制，同时也为基于本课题发现的在肝癌耐药中发挥关键作用的miRNA、蛋白为靶点的抗肿瘤新药的研发提供理论依据。