Cellular radiosensitivity and endocytosis: The role of PINCH1 and caveolin-1.

在正常细胞和癌细胞中，内吞作用在细胞的生存、增殖、代谢、迁移和信号转导等多种功能中发挥着重要作用。组织特异性地，整体膜蛋白小窝蛋白-1、-2和-3负责小窝介导的内吞作用。Caveolin-1与整合素粘附和生长因子受体相连，并以整合素连接激酶（integrin -linked kinase， ILK）的方式控制小泡的形成。PINCH1与ILK和Parvin （IPP蛋白复合物）一起控制局灶黏附组装，其在依赖于小窝蛋白-1的内吞作用中的作用仍然难以捉摸。自己的初步数据表明，caveolin-1和PINCH1相互作用，两种蛋白在恶性肿瘤中都过表达。PINCH1和caveolin-1都与蛋白激酶Akt1相互作用，调节放射性和化学耐药机制。通过靶向抑制PINCH1和caveolin-1，我们能够显著降低来自不同癌症类型的细胞的放射和化疗耐药。然而，电离辐射和化疗对小窝蛋白-1依赖性内吞作用的影响以及PINCH1作为IPP复合物的一部分在这一过程中所起的作用仍然是难以捉摸的。该项目旨在研究用不同PINCH1变体重组的小鼠胚胎PINCH1-/-成纤维细胞和胰腺导管腺癌细胞培养物中小窝蛋白-1依赖性内吞噬的分子机制，以及PINCH1对放射治疗的贡献。通过鉴定PINCH1对放疗依赖性的内吞调节，有望对恶性肿瘤的耐药机制和相关信号通路有新的认识，并有望发现新的潜在的联合放疗治疗策略。

In normal and cancer cells, endocytosis plays a fundamental role in various cell functions such as survival, proliferation, metabolism, migration and signal transduction. Tissue-specifically, the integral membrane proteins caveolin-1, -2 and -3 are responsible for caveolae-mediated endocytosis. Caveolin-1 is linked to integrin adhesion and growth factor receptors and controls the caveolae formation in an Integrin-linked kinase (ILK) manner. For PINCH1, which controls focal adhesion assembly together with ILK and Parvin (IPP protein complex), a role in caveolin-1-dependent endocytosis remains elusive. Own preliminary data show that caveolin-1 and PINCH1 interact and that both proteins are over-expressed in malignant tumors. Both, PINCH1 and caveolin-1 interact with the protein kinase Akt1 for the regulation of radio- and chemoresistance mechanisms. By means of targeted inhibition of PINCH1 and caveolin-1, we were able to significantly reduce radio- and chemoresistance in cells originating from different cancer types. However, it remains elusive what influence ionizing radiation and chemotherapeutics have on caveolin-1-dependent endocytosis and which function PINCH1, as part of the IPP complex, has in this process. The proposed project addresses the molecular mechanisms of caveolin-1-dependent endocytosis and the contribution of PINCH1 upon radiotherapy in mouse embryonic PINCH1-/- fibroblasts reconstituted with different PINCH1 variants and in cell cultures from ductal adenocarcinomas of the pancreas. Through the identification of the endocytosis regulation in dependence on PINCH1 upon radiotherapy, new insights into the resistance mechanisms and associated signaling pathways in malignant tumors as well as the identification of novel potential therapeutic strategies in combination with radiotherapy are anticipated.