Hippo/PKM2通路调控乳腺癌他莫昔芬耐药的分子机制研究

The challenges of tamoxifen (TAM) resistance have drawn wide attention and attached great importance in clinical endocrinotherapy of breast cancer. Supported by NSFC grant (No.81272544), TAM-resistant breast cancer cell line (MCF-7R) was established, and the gene expression profile of MCF-7 and MCF-7R was screened by high-throughput sequencing. Here, we firstly revealed that the Hippo signaling pathway and pyruvate kinase M2 (PKM2) were involved in the regulation of TAM resistance in breast cancer cells; and so we conceive a hypothesis that Hippo/PKM2 signaling pathway is involved in TAM resistance of breast cancer cells. The underlying mechanisms were illuminated in many aspects, including YAP/TAZ regulated the expression of PKM2 in transcriptional levels, the interaction between PKM2 and MST1 promoted cell apoptosis and PKM2 mediated autophagy in drug-resistant cells. It is confirmed that the effects of Hippo/PKM2 signaling pathway on TAM resistance in breast cancer and clarified PKM2 served as the leading actor and main focus in TAM resistance, which inspired us to reverse TAM resistance by silencing PKM2 expression in resistant breast cancer cells. On basis of this study on the novel signaling pathway and molecular mechanisms of TAM resistance, it grounded the theoretical and experimental foundations for seeking critical target aimed at TAM resistance in clinical therapy of breast cancer. On the other hand, it also made beneficial attempts to explore the approach and strategy for reversing endocrinotherapy resistance of breast cancer.

临床乳腺癌TAM治疗的耐药性难题已引起广泛关注。本课题组在NSFC项目No.81272544支持下，前期构建了TAM耐药乳腺癌细胞株MCF-7R，通过高通量测序方法，比较MCF-7和MCF-7R细胞的基因差异表达谱，首次发现Hippo信号通路、PKM2参与乳腺癌TAM耐药，提出“Hippo/PKM2通路调节乳腺癌细胞TAM耐药”的科学假说。通过深入解析YAP/TAZ调控PKM2转录表达、PKM2与MST1相互作用促进细胞凋亡及PKM2介导耐药细胞自噬等分子机制，明确Hippo/PKM2通路在调控乳腺癌TAM耐药中的作用，阐明PKM2在其中发挥的重要功能，并通过对PKM2的干预，实现对乳腺癌细胞TAM耐药的逆转。上述研究探讨了乳腺癌TAM耐药新的信号通路和分子机制，为寻找乳腺癌细胞TAM耐药的关键靶点提供了重要的理论和实验基础，并对成功逆转乳腺癌内分泌治疗抵抗的方法和策略进行了有益尝试。

临床乳腺癌他莫昔芬治疗的耐药性难题已引起广泛关注。通过转录组学分析我们发现EREG是维持乳腺癌细胞对他莫西芬耐药性的一种新的调节因子，EREG通过激活EGFR信号通路及其下游糖酵解基因，在他莫昔芬耐药乳腺癌细胞糖酵解的增强中发挥重要作用，我们的研究结果揭示了miR-186-3p/EREG轴调节ER+乳腺癌细胞有氧糖酵解而影响他莫昔芬耐药的新分子机制。与此同时，我们也发现了葡萄糖代谢过程中的关键酶-丙酮酸脱氢酶激酶1（PDK1）在他莫昔芬耐药性人乳腺癌细胞株中表达量明显升高，干扰耐药细胞中PDK1蛋白表达后细胞耐药性降低，并且在EGF的处理条件下PDK1会发生核转位现象，促进乳腺癌细胞的增殖迁移侵袭，抑制PDK1的核定位可能为乳腺癌的治疗提供新的治疗策略。