Src介导TJP1相分离异常调控肾透明细胞癌转移的机制研究

肾透明细胞癌易转移预后差，其转移机制仍需深入研究。细胞紧密连接结构的破坏是肿瘤转移的关键步骤，紧密连接蛋白TJP1通过相分离驱动紧密连接结构的组装，但该过程是否参与肿瘤转移尚不清楚。预实验显示：TJP1在癌组织中表达低于正常组织，其低表达与不良预后相关。敲低TJP1导致IGFBP5水平降低，激活p38-MAPK，促进肿瘤细胞转移。TJP1膜质定位受到其相分离调控，且与肿瘤侵袭程度相关。Src激酶通过磷酸化抑制TJP1相分离，导致TJP1细胞膜锚定减少，促进YBX3入核抑制IGFBP5转录。据此推测：Src磷酸化抑制TJP1相分离、膜定位及YBX3的相互作用，通过YBX3/IGFBP5/p38-MAPK轴调控肾透明细胞癌转移。本项目拟从细胞、动物以及临床样本层面，阐明TJP1相分离调控肾透明细胞癌转移的分子机制，揭示其生物学功能以及临床意义。本项目的完成将揭示紧密连接调控肿瘤转移的新机制。

Clear cell renal cell carcinoma (ccRCC) tends to metastasize with poor prognosis. It is important to understand the mechanism of metastasis. Loss of cell-to-cell tight junctions is the key step in the process of cancer metastasis, phase separation of tight junction protein TJP1 drives formation of tight junction. However, it’s unclear whether this process is involved in cancer metastasis. Our preliminary results showed that TJP1 was markedly down-regulated in human ccRCC tissues compared to normal tissues. Lower TJP1 expression was correlated to poor prognosis. Knockdown of TJP1 promoted ccRCC cells metastasis through IGFBP5-mediated p38-MAPK signaling pathway. The membrane/cytoplasm translocation of TJP1, which correlated to invasion and stage of ccRCC, was regulated by itself phase separation. Src kinase inhibit phase separation of TJP1 through binding to and promoting phosphorylation of TJP1. Therefore, we speculated that TJP1 phase separation was inhibited by Src-mediated phosphorylation, and regulate ccRCC cells metastasis through YBX3/IGFBP5/p38-MAPK axis. This proposal plans to elucidate mechanism by which TJP1 phase separation regulate ccRCC cells metastasis, to explore the biological function and clinical significance of TJP1 phase separation in ccRCC. We believe that this proposal will provide a new mechanism for tight junction in cancer metastasis.