HOXA5通过CHOP介导的凋亡途径抑制胆管癌的增殖作用研究

Effective therapy to cholangiocarcinoma (CCA) is still lacking. Therefore, there is an urgent need to define the molecular mechanisms underlying CCA tumorigenesis with a view to develop novel therapeutic strategies. Recently, our laboratory has found that HOXA5 expression is lost in CCA. Nevertheless, the molecular pathways that underlie HOXA5 in CCA are not fully elucidated. CHOP is an important regulatory factor in apoptosis induced by endoplasmic reticulum stress, and it plays an important role in regulation of programmed cell death. Our research found that overexpression of HOXA5 in CCA cells induced apoptosis, and up-regulated CHOP. Bioinformatics analysis also revealed the presence of multiple HOXA5 core-binding motifs in the promoter sequences of the CHOP gene. Accordingly, we speculate that HOXA5 contributes to CCA cell proliferation via CHOP-mediated apoptotic signaling pathway. In this study, dual luciferase reporter gene and co-immunoprecipitation assay were performed to confirm whether HOXA5 binds directly to the CHOP promoter in CCA cells. Furthermore, CCA cells overexpressing HOXA5 by Lentiviral vector and transplantation tumors in nude mice will be performed. The effects of HOXA5 to apoptosis of CCA cells and CHOP-mediated apoptosis pathway were tested in vitro and in vivo. our study will elucidate the molecular mechanism underlying HOXA5-mediated inhibition of CCA, which suggests new therapeutic targets for CCA treatment.

胆管癌目前治疗效果尚不理想，探索新的分子靶点意义重大。本课题组前期工作发现HOXA5在人胆管癌中低表达，且与患者预后相关。然而，HOXA5在胆管癌中作用机制尚不明确。CHOP是内质网应激诱导凋亡过程中重要调节因子，在调节程序性细胞死亡过程中发挥重要作用。本课题组发现在胆管癌细胞中过表达HOXA5后，CHOP表达增加，细胞发生凋亡。生物信息学分析也发现CHOP基因启动子区含有HOXA5理论结合位点。据此我们推测，在胆管癌中HOXA5可能通过CHOP介导的凋亡途径实现抑癌作用。本研究拟采用双荧光素酶报告基因、免疫共沉淀等技术研究HOXA5与CHOP的关系，应用慢病毒载体技术构建HOXA5过表达的胆管癌细胞株及其皮下种植瘤裸鼠模型，从体外、体内水平探究HOXA5在胆管癌中促凋亡及对CHOP介导的凋亡通路的作用，有望阐明HOXA5抑制胆管癌增殖的分子机制，为胆管癌的治疗提供新的分子靶点。

胆管癌目前治疗效果尚不理想，探索新的分子靶点意义重大。通过研究我们发现，胆管癌中 HOXA5具有抑癌基因的作用，其主要作用机制是通过 CHOP 介导.的凋亡途径影响胆管癌增殖。在临床样本检测中，通过免疫组化芯片检测临床胆管癌样本中 HOXA5 的表达情况，并分析得出其表达水平越高，患者生存期越长，预后越好。并初步明确HOXA5在胆管癌中低表达的主要原因之一是基因甲基化。在功能检测中，体内外实验均证实过表达HOXA5后，胆管癌增殖受到抑制，凋亡明显。.最后，在机制研究中，发现HOXA5通过上调CHOP，进而上调BCL2、GADD34、ERO1L、TRIB3等下游通路，促凋亡，从而抑制增殖。至此，本项目初步阐明 HOXA5 通过 CHOP 介导的凋亡途径影响胆管癌增殖，为寻找胆管癌有效的治疗靶点奠定坚实基础。