PGC-1α介导SNAIL2维持三阴乳腺癌干性表型的分子机制研究

The maintenance of breast cancer cell stemness is the root cause of cancer progression. In our previous study, we found that PGC-1αis highly expressed in triple-negative breast cancer(TNBC), and it mediates the maintenance of cancer cell stemness. In addition, we also uncovered that the expression of PGC-1αis regulated by the transcriptional factor SNAIL2. However, the underlying mechanisms by which SNAIL2/PGC-1αaxis regulates TNBC stemness are still unclear. In Sum, in the current project we propose the hypothesis that: SNAIL2 promotes the expression of PGC-1α, and the upregulation further activates Hippo signaling pathway which maintains the cancer stem cell phenotypes. In this study, we will utilize ChIP、EMSA、DNaseI blotting and Luciferase reporter assay to explorethe molecular mechanisms of how SNAIL2 promotes PGC-1αexpression. Additionally, we will overexpress or knockdown/knockout SNAIL2 or PGC-1α to test the effects on Hippo pathway activation and stemness maintenance. We will also explore the correlation of SNAIL2 and PGC-1α expressions with patient survival and prognosis based on our clinical follow-up data. Our study aims at to demonstrate the mechanisms of TNBC malignancy based on the TNBC stem cell model and has the potential to identify new therapeutic targets.

乳腺癌细胞能够维持干性的能力是乳腺癌恶性生长的根本原因。通过研究我们发现PGC-1α在三阴乳腺癌细胞中高表达，PGC-1α参与维持三阴乳腺癌细胞的干性表型，且转录因子SNAIL2是影响PGC-1α表达的关键转录因子，但SNAIL2/PGC-1α发挥作用的具体分子机制不详。综上，本项目提出假设：SNAIL2可能通过转录激活PGC-1Α表达，影响Hippo通路进而参与维持三阴乳腺癌干细胞的干性表型。项目拟采用ChIP、EMSA、DNaseI足迹分析、萤光素酶报告基因实验，探讨SNAIL2调控PGC-1α表达的分子机制；并在三阴乳腺癌细胞模型中改变SNAIL2和PGC-1α表达，检测其对Hippo通路及三阴乳腺癌细胞干性表型的影响；统计分析临床随访资料，探讨SNAIL2和 PGC-1α的表达对三阴乳腺癌患者预后评估的价值，并且有望对三阴乳腺癌恶性生长的治疗提供潜在的干预靶点和实验依据。

乳腺癌细胞能够维持干性的能力是乳腺癌恶性生长的根本原因。通过前期研究我们发现PGC-1α在三阴乳腺癌细胞中高表达，PGC-1α参与维持三阴乳腺癌细胞的干性表型，且转录因子SNAIL2是影响PGC-1α表达的关键转录因子，但SNAIL2/PGC-1α发挥作用的具体分子机制不详。综上，本项目提出假设：SNAIL2可能通过转录激活PGC-1Α表达，影响Hippo通路进而参与维持三阴乳腺癌干细胞的干性表型。项目拟采用ChIP、EMSA、DNaseI足迹分析、萤光素酶报告基因实验，探讨SNAIL2调控PGC-1α表达的分子机制；并在三阴乳腺癌细胞模型中改变SNAIL2和PGC-1α表达，检测其对Hippo通路及三阴乳腺癌细胞干性表型的影响；统计分析临床随访资料，探讨SNAIL2和 PGC-1α的表达对三阴乳腺癌患者预后评估的价值，并且有望对三阴乳腺癌恶性生长的治疗提供潜在的干预靶点和实验依据。本项目通过一系列实验进一步发现，SNAIL2能够与PGC-1α启动子区域进行相互结合，激活PGC-1α表达。鉴定了PGC-1α与Hippo通路关键蛋白YAP1的结合位点。该位点的失活突变减少了PGC-1α与YAP1的结合，并降低YAP的磷酸化水平。YAP磷酸化水平的降低导致三阴乳腺癌肿瘤干细胞形成比例减少。对临床样本进行分析结果显示组织中高表达的SNAIL2及PGC-1α与三阴乳腺癌患者不良预后相关。上述研究结果证实SNAIL2/PGC-1α/Hippo通路是三阴乳腺癌干细胞形成的关键通路，具有临床转化潜力。本课题组同样完成多项横向课题，对乳腺癌侵袭、转移、耐药及化疗副反应等领域进行深入研究，为三阴乳腺癌的治疗提供新的见解。