TASP1调控EMT促进胆囊癌细胞侵袭转移的分子机制研究

Gallbladder carcinoma (GBC) is one of the most aggressive malignancy found in the biliary tract. Early metastasis is the main cause of death from GBC. TASP1 regulates some nuclear transcription factors, and its relationship with invasion and metastasis remains unknown to date. The previous research found that TASP1 expression is significantly upregulated in the high metastatic potential GBC-SD/M3. Overexpression/RNA interference-mediated silencing of TASP1 gene can change the expression level of EMT-related marker proteins, which indicated that TASP1 played an important role in regulating EMT of GBC. We further screened that MLL interacts with TASP1 by the yeast two-hybrid system, and the molecular mechanism should be explored further. Based on these results, we suggested that TASP1 actives histone methyltransferase MLL to induce EMT in GBC. From the aspects of molecule, cell, animal model and clinical tissue levels, we will investigate the regulatory function of TASP1 in EMT, and explore that how TASP1 actives MLL to promote invasion and metastasis in GBC. This project might contribute to clarify the mechanisms of cellular invasion and metastasis, and provide the new theoretical basis for developing the medical treatment strategies in GBC.

胆囊癌是胆道系统最常见的恶性肿瘤，早期转移是其最重要的死亡原因。TASP1具有调控核转录因子的功能，迄今对其与肿瘤侵袭转移的关系仍知之甚少。本课题组前期发现TASP1在胆囊癌高转移细胞亚群GBC-SD/M3中的表达量显著升高；采用过表达/RNAi沉默TASP1后，发现EMT相关分子标记物表达水平发生改变，提示TASP1在调控胆囊癌EMT中起重要作用；进一步通过酵母双杂交实验筛选出TASP1的相互作用蛋白MLL，其作用机制还有待进一步探讨。为此我们提出假说：TASP1可能通过激活组蛋白甲基转移酶MLL来进一步诱导胆囊癌发生EMT。为验证这一假说，我们从分子、细胞、动物及临床组织水平探讨TASP1在调控胆囊癌EMT中的重要作用，明确TASP1如何通过激活MLL来促进侵袭转移的分子机制。本研究将从TASP1这个新视点为揭示肿瘤细胞侵袭转移机制奠定基础，为胆囊癌医学治疗策略的开发提供新的理论依据。

胆囊癌是胆道系统最常见的恶性肿瘤，其恶性程度高，预后极差，早期转移是其最重要的死亡原因。胆囊癌的侵袭转移是一个十分复杂的级联过程，针对胆囊癌的转移机制研究，将有助于寻找新的胆囊癌肿瘤标记物和医学治疗靶点。特异性位点蛋白酶解不仅对整个生理过程至关重要，而且这些关键酶类在多种癌症内也发挥着十分重要的调控功能。在本研究中，我们通过免疫组化及临床病理资料分析，发现高度保守的蛋白酶TASP1在胆囊癌组织中高表达，且其表达量与患者的组织学分化程度及转移等相关。TASP1高表达提示患者预后不良，是影响患者预后的独立危险因素。敲减TASP1基因后，胆囊癌GBC-SD和EH-GB-1细胞增殖、侵袭及转移能力显著受到抑制，且在动物水平上验证了其对胆囊癌细胞增殖能力的影响。通过生物信息学对基因表达谱芯片分析，我们筛选出TASP1调控FAM49B表达，并首次证明FAM49B在胆囊癌细胞中具有生物学功能，且进一步验证了TASP1能有效通过激活PI3K/AKT信号通路而影响FAM49B表达的分子调控机制。进一步加入PI3K/AKT信号通路抑制剂LY294002后， PI3K/AKT及FAM49B表达量下调，可以部分回复过表达TASP1后所引起的胆囊癌细胞增殖及转移能力增强。综上所述，TASP1可能成为判断胆囊癌预后以及指导临床治疗的新靶点。