N-Cadherin/β-catenin复合体介导FRK对脑胶质瘤细胞侵袭、增殖作用的研究

Most members of oncogene Src family promote tumor growth, but the special member FRK inhibits tumor growth and the mechanism is still unknown. We have found that FRK not only inhibited glioma cell invasion and proliferation, but also promoted the expression of N-cadherin, as well as increasing the membrane location of N-cadherin and β-catenin and the formation of N-cadherin/β-catenin complex. In this study, by starting from the cadherin/β-catenin complex, the key molecule complex in regulating cell adhesion, and using cultured glioma cells and in situ nude mice glioma model, we will study the role and the mechanism of FRK in glioma cell invasion, migration and proliferation. The expected results will reveal that FRK promotes glioma cell adhesion and inhibits invasion/migration by increasing the level of N-cadherin, recruiting β-catenin to cell membrane, and promoting N-cadherin/β-catenin complex formation, as well as inhibiting cell proliferation by reducing β-catenin nuclear translocation. Our results will imply that FRK, might be a potential molecular therapeutic target of gliomas.

原癌基因Src家族多数成员促进肿瘤生长，其特殊成员FRK却抑制肿瘤生长，但机制不明。我们发现FRK抑制胶质瘤细胞侵袭和增殖，且上调N-cadherin水平，增加其和β-catenin在膜上的聚集，促进N-cadherin/β-catenin复合体的形成。因此，本项目拟以调节细胞粘附的关键分子cadherin/β-catenin复合体为切入点，应用培养的胶质瘤细胞和裸鼠原位胶质瘤模型为研究对象，从分子、细胞及整体水平阐明FRK通过调节N-cadherin/β-catenin复合体抑制胶质瘤细胞侵袭和增殖的机制。预期结果将揭示FRK通过增加N-cadherin的水平，募集β-catenin到膜上，促进N-cadherin/β-catenin复合体的形成，增强细胞间粘附作用，抑制侵袭与迁移；同时减少β-catenin的核转位，抑制胶质瘤细胞增殖的新机制，提示FRK可能是胶质瘤的一个潜在分子靶点。

原癌基因Src家族成员大多具有促进细胞迁移及增殖的功能，然而其特殊成员FRK却可抑制肿瘤的增殖，我们发现与非肿瘤脑组织相比，脑胶质瘤中FRK的mRNA 和蛋白水平降低，提示FRK在脑胶质瘤的发病中起着一定的作用。而且，过表达FRK 可以抑制胶质瘤U251和U87细胞的侵袭、迁移及增殖、促进凋亡。过表达FRK增加了N-cadherin蛋白水平，以及N-cadherin和β-catenin的结合能力，但对E-cadherin及β-catenin蛋白水平无明显影响；免疫荧光、免疫共沉淀和免疫印迹结果发现：过表达FRK增加了N-cadherin和β-catenin在细胞膜上的聚集，同时减少了β-catenin的核转位。此外，我们还发现下调N-cadherin可以促进胶质瘤细胞的迁移与侵袭，促进增殖、抑制凋亡；N-cadherin siRNA可以逆转过表达FRK对胶质瘤细胞迁移、侵袭、增殖和凋亡的作用。并且用siRNA下调N-cadherin的表达能够抑制过表达FRK对β-catenin定位的影响。通过裸鼠实验，我们发现过表达FRK可以减小颅内原位肿瘤的体积、抑制原位肿瘤细胞的增殖、促进原位胶质瘤细胞的凋亡，并延长裸鼠生存时间，表明在体水平，FRK可以抑制胶质瘤生长。以上结果提示我们FRK可以通过调节N-cadherin/β-catenin复合体抑制胶质瘤细胞侵袭和增殖。