癌蛋白TBC1D3与β-肌动蛋白“对话”促进乳腺癌细胞迁移的分子机制

Actin shuttles in the cytoplasm and nucleus, nucleus actin participates in a variety of functions, such as transcription. TBC1D3 oncoprotein promoted the migration of breast cancer cells, which was found in Graduate Research and Innovation Projects in Jiangsu Province hosted by the applicant during the study of doctoral students (Relevant research was published in Cancer letters, IF:6.375). Recently we found that TBC1D3 might interact with β-actin and promote the migration of breast cancer cells, however, little is known about the concrete mechanism. Therefore, we propose that TBC1D3 may transport into the nucleus by interacting with β-actin and promote the migration of human breast cancer cells through regulating the expression of target genes related with migration. This project aims to screen the target genes regulated by TBC1D3 interacting with β-actin and further explore the molecular mechanism of "a dialog" between TBC1D3 and β-actin, which promotes the migration of breast cancer cells. The completion of this project not only provides a new perspective for transcription of nuclear actin and actin new binding protein(TBC1D3), but also provides a theoretical basis and potential target for the prevention and treatment of breast cancer.

肌动蛋白在胞浆胞核中穿梭，在胞核中发挥转录调控等多种功能。申请人攻读博士期间主持的江苏省研究生创新计划中发现癌蛋白TBC1D3介导乳腺癌细胞的迁移（相关研究发表在Cancer letters，IF:6.375），近期发现TBC1D3与β-肌动蛋白在乳腺癌细胞胞浆和核内存在相互作用，促进乳腺癌细胞迁移，但迁移的具体机制未知。基于此，我们提出TBC1D3作为新的肌动蛋白结合蛋白，可能通过与β-肌动蛋白相互作用进入细胞核，调控迁移相关靶基因表达进而促进乳腺癌细胞迁移进程。本项目拟通过免疫共沉淀和高通量测序等方法筛选TBC1D3与β-肌动蛋白相互作用调控迁移的相关靶基因，进一步探讨TBC1D3与β-肌动蛋白“对话”促进乳腺癌细胞迁移的分子机制。本项目的完成既为研究细胞核肌动蛋白与肌动蛋白新的结合蛋白TBC1D3参与基因转录提供了新的视点，也为预防和治疗乳腺癌提供理论基础和潜在靶点。

乳腺癌在女性癌症患者位居第一，死亡率居第二。死亡的主要原因是晚期转移。TBC1D3可以诱导乳腺癌细胞侵袭转移，但具体机制还未明确。在本研究中，我们通过免疫共沉淀联合质谱分析发现TBC1D3与β肌动蛋白在乳腺癌细胞胞浆胞核存在相互作用，免疫共沉淀正向和方向验证TBC1D3为β肌动蛋白新的结合蛋白；TBC1D3与β肌动蛋白结合区域位于251-353片段；同时我们还发现 TBC1D3与F-actin也存在共定位，用鬼笔环肽破坏微丝，发现TBC1D3入核增加；TBC1D3入核后，我们通过染色质免疫共沉淀测序与转录组测序联合分析发现TBC1D3在核内结合在SLC12A6启动子区域，激活SLC12A6的表达；除此之外，高通量测序发现TBC1D3激活MAPK信号通路和阻滞细胞周期在G1期。总的来说，TBC1D3通过上调SL12A6表达激活MAPK信号通路促进乳腺癌细胞迁移。这些研究结果阐明TBC1D3诱导乳腺癌迁移的新机制，为乳腺癌治疗提供新的潜在靶点。