定位于伪足的Polycystin-1激活Daam1促进乳腺癌细胞Wnt5a自分泌和定向迁移的机制研究

乳腺癌转移是威胁患者生命的主要原因之一。乳腺癌细胞既能适应肿瘤微环境的变化，又能改变肿瘤微环境。我们以往的工作已阐明肿瘤微环境中的胶原蛋白通过Integrin αvβ3激活Daam1，促进乳腺癌细胞的定向迁移。然而Integrin αvβ3和Daam1不能直接结合，何种蛋白直接感受肿瘤微环境的改变并激活Daam1尚未可知。本项目拟研究：(1)Polycystin-1能否单独或与Integrin αvβ3形成复合体感受乳腺癌细胞外基质(ECM)信号并激活Daam1，进而促进微丝重构和定向迁移？(2)活化的Daam1能否激活Rab35，促进Wnt5a自分泌，从而改造乳腺癌的肿瘤微环境？(3)分泌到细胞外(肿瘤微环境中)的Wnt5a浓度是否与乳腺癌浸润和转移程度呈正相关，能否刺激乳腺癌细胞维持Daam1/Rab35持续激活？本项目从乳腺癌和肿瘤微环境的相互作用这个角度揭示乳腺癌转移的新机理。

The metastasis of breast cancer is a major reason threatening the health and even survival of patients. However, the underlying mechanism of breast cancer metastasis is largely unknown. Breast cancer cells can not only adapt to the changes of tumor microenvironment, but also change and influence tumor microenvironment. We have demonstrated that Daam1 is activated by Integrin αvβ3 in response to collagen, a component of tumor microenvironment, subsequently facilitates the microfilament reassembly and the formation of invadopodia and the migration of breast cancer cells. However, Daam1 does not directly bind to Integrin αvβ3. Which protein directly activates Daam1 and then allows breast cancer cells to sense tumor microenvironment? In this study, we will perform mass spectrometry, unbiased forward genetic screening approach, mice in vivo model, immunohistochemistry assays to investigate: (1) Whether Polycystin-1 or Polycystin-1/Integrin αvβ3 complex senses collagen signaling to activate Daam1 and promotes the microfilament reassembly and migration? (2) Whether active Daam1 activates Rab35 and then accelerates the autocrine of Wnt5a? (3) Whether the concentration of autocrine Wnt5a is positively association with the invasion and metastasis of breast cancer? Whether endogenous Wnt5a continually activates Daam1/Rab35 and facilitates cell migration of breast cancer cells? Our research would provide better understanding of the molecular mechanisms involved in the interaction of breast cancer cells and tumor microenvironment and the potential target gene pathway for breast cancer molecular targeted therapy.