靶向PI3K/AKT 与TGF-β 信号对肿瘤细胞代谢的双调控在肺癌治疗中的实验研究

Previous clinical studies indicated that targeting PI3K/AKT pathway alone was not sufficient to suppress tumor growth due to complicated signaling interaction and feedback with other pathways, therefore, to identify the detailed interactions between PI3K/AKT and other signaling pathways will facilitate the design of effective combination strategies for cancer therapy. Using synthetic lethal strategies combined with genome-wide RNAi library screening we identified a panel of genes that are synthetic lethal with AKT inhibition. Using Ingenuity Pathway Analysis, we determined that TGF-β signaling pathway is synthetic lethal with PI3K/AKT. We confirmed that there are signaling interactions between PI3K/AKT and TGF-β, and that both pathways regulate cancer cell lipogenesis pathways. We found that concurrent inhibition of PI3K/AKT and TGF-β pathways induced synergistic anticancer effects. Based on the preliminary results, we hypothesize that PI3K/AKT and TGF-β pathways can compensate each other in the inhibition of cancer cell survival and metabolic signaling. The work proposed in this application will further explore the mechanism underlying synthetic lethal interaction between TGF-β and AKT pathways in lung cancer cells and to evaluate the anti-tumor activity of combination of TGF-β and AKT inhibitors for lung cancer therapy in vitro and in vivo.

前期的临床研究表明由于PI3K/AKT信号通路与其他信号通路之间存在复杂的交互和反馈作用，单向抑制PI3K/AKT信号通路并不能对肿瘤细胞产生有效的杀伤，因此进一步阐明PI3K/AKT通路与其他信号通路的作用将有助于设计有效的肿瘤治疗新方案。我们利用全基因组siRNA文库筛选出多个与AKT抑制剂存在合成致死效应的基因靶点，并通过信号网络分析发现TGF-β是其中一个重要的与AKT具有合成致死关系的信号通路。我们证实TGF-β和AKT信号通路之间存在信号反馈且共同调节肿瘤细胞的脂质合成途径，并初步发现同时抑制TGF-β和AKT信号通路可产生协同肿瘤杀伤效应。我们推测两条通路在肿瘤生长信号和肿瘤代谢的调控两个层面上存在相互代偿的关系。本研究拟进一步深入探讨两条信号通路在细胞的生长信号和肿瘤关键代谢途径上相互作用和代偿，并探索联合TGF-β和AKT抑制剂对肺癌治疗的体内效果。

本课题开展了联合AKT抑制剂（MK2206） 与多种脂质合成代谢抑制剂联合在肺癌治疗的实验性研究，同时探索了FASN抑制剂（Orlistat）对多种肺癌细胞的体内外杀伤效应以及背后作用机理。本课题研究发现联合MK2006和Orlistat 或TOFA 具有协同杀伤肿瘤效应，促进细胞的凋亡。同时本课题还通过RNA-seq首次发现FASN 抑制剂Orlistat 抑制FASN 相关蛋白FAF2基因的表达、诱导肿瘤细胞的铁死亡效应、抑制肿瘤生长以及促进免疫细胞的肿瘤浸润。在此基础上，本研究也探索了Orlistat和PD1 抗体的联合对小鼠肿瘤抑制的研究，虽然并没有发现两者联合的协同效应。另外，本课题通过组织芯片结合TCGA 数据库发现FAF2 基因在肺癌组织显著高表达且与肺癌病人的生存成负相关，同时验证了FAF2具有促进非小细胞肺癌细胞的生长和侵袭功能。有关FAF2 如何通过影响脂质油滴在细胞内的形成和转运参与肺癌的进展和免疫逃逸的机理正在进一步深入研究之中。