代谢应激通过TRB3调节肿瘤相关巨噬细胞和肝癌干细胞样特性的作用和机制

Chronic inflammation and obesity are associated with increased risk of hepatocellular carcinoma. Metabolic stresses and immune factors participate parallelly and reciprocally in the regulation of tumorigenesis and tumor progression of hepatocellular carcinoma. Recently, we reported that TRB3, a stress-induced protein, links insulin/IGF to tumor promotion by interacting with p62 and impeding autophagic/proteasomal degradations. We then identified that depletion of TRB3 inhibits the M2 polarization of tumor-associated macrophage (TAM) and decreases the expression of cancer stem cell markers. We also found that TRB3 is a binding partner of macrophage migration inhibitory factor (MIF) and increases the stability of MIF. We therefore hypothesize that metabolic stress-increased TRB3 connects metabolic factors to hepatocellular carcinogenesis and progression through inducing TAM recruitment and M2 polarization as well as enhancement of cancer stem cell-like properties. To prove this hypothesis, we’ll pursuit the potential roles and mechanisms of TRB3 in the regulation of macrophage polarization and cancer stem cell-like properties by using molecular & cellular technologies and animal models, in combination with clinical samples analysis. We'll also explore the therapeutic strategy of repolarizing macrophage for liver cancer treatment. Our proposed studies may not only provide deep insights into the pathogenesis of metabolic/immune stresses in the promotion of hepatocellular carcinogenesis and progression but also provide clues and opportunities for the development of anti-cancer drugs.

慢性炎症和肥胖是导致肝癌的重要风险因素，代谢应激与炎症平行或交互调节肝癌发生、发展。本研究小组近期工作报道，应激蛋白TRB3与自噬受体蛋白P62相互作用，介导自噬和蛋白酶体系统交互抑制，促进糖尿病相关肿瘤进程。我们还发现，敲低肝癌细胞TRB3，降低肿瘤干细胞标志蛋白表达，抑制巨噬细胞M2型极化。此外，TRB3与巨噬细胞迁移抑制因子（MIF）相互作用，增强MIF稳定性。我们因此提出假说：代谢应激诱导TRB3表达增高，增加的TRB3与MIF相互作用增强MIF稳定性，进而促进肿瘤相关巨噬细胞M2极化，诱导和维持肿瘤干细胞样特性，促进肝癌发生、发展。为此，我们将从整体动物－细胞－分子三个层次，结合肝癌临床样本，阐明TRB3通过调节肿瘤免疫微环境和肿瘤干性，在肥胖相关肝癌发生、发展中的作用和机制，并探索肝癌免疫治疗新策略。本研究揭示的代谢应激促肝癌的分子机制将为肝癌的防治和药物研发提供新的思路。

基础和流行病学证据显示糖尿病人群罹患肿瘤的风险显著高于普通人群。我们早期的工作证明，代谢应激诱导假性激酶TRIB3表达增高，该蛋白通过抑制自噬流促进肿瘤恶性进展。在本项目中我们进一步证实TRIB3还可诱导和维持肿瘤特异性癌基因信号活化并导致抗肿瘤免疫逃逸。在结肠癌中，TRIB3募集并促进beta-catenin—TCF4功能性转录复合物形成，增强beta-catenin转录活性、维持结肠癌干细胞特性、促进结肠癌对化疗药物产生耐受；TRIB3还抑制CD8+ T细胞浸润，导致结肠癌免疫逃逸。在肺癌中，TRIB3促进EGFR回膜循环，维持EGFR蛋白稳定性和信号持续活化。在机制上，我们阐明高糖等代谢通过P300介导TRIB-K240乙酰化修饰，该修饰抑制TRIB3泛素化降解，造成TRIB3稳定性异常增高。此外，我们发现EGFR可诱导SQSTM1-Y433磷酸化，导致SQSTM1-UBA结构域二聚化和自噬抑制，促进肿瘤进展。该工作拓展了我们对癌基因信号调控自噬的认识。我们利用自主设计的多肽类先导化合物证实，靶向EGFR—TRIB3相互作用促进EGFR降解；靶向beta-Catenin—TRIB3相互作用抑制beta-catenin—TCF4功能性转录复合物形成是治疗上述肿瘤的潜在靶点和全新策略。上述工作为开发原创抗肿瘤药奠定了理论基础和物质准备。项目执行期间共发表SCI论文5篇（其中影响因子10以上论文2篇），中文论文2篇；新申请专利3项；另有3项专利在执行期间经补充完善获得授权；参加学术会议并做会议报告3次。