Zhang Yanhong, Young Ashley, Zhang Jin, Chen Xinbin
Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of Californian at Davis, Davis, CA, USA.
Oncotarget. 2015 Jun 10;6(16):13994-4004. doi: 10.18632/oncotarget.4374.
P73, a member of p53 tumor suppressor family, plays a crucial role in tumor suppression and neural development. Due to the usage of two promoters, p73 is expressed as two isoforms, TAp73 and âNp73, with opposing functions. Here, we investigated the potential role of p73 in epithelial polarity and morphogenesis by using Madin-Darby canine kidney (MDCK) cells as a model system. We found that knockdown of TAp73 enhances, whereas knockdown of âNp73 inhibits, MDCK cell proliferation and migration in two-dimensional (2-D) culture. We also found that knockdown of TAp73, but not âNp73, disrupts cyst formation of MDCK cells in three-dimensional (3-D) culture. Interestingly, we found that p21 and PUMA, both of which are induced by TAp73 but repressed by âNp73, are required for suppressing cell proliferation and migration in 2-D culture and for MDCK ce ll morphogenesis in 3-D culture. Finally, we showed knockdown of TAp73, p21 or PUMA induces epithelial to mesenchymal transition (EMT) with a decrease in E-cadherin and an increase in EMT transcription factors. Together, our data suggest that TAp73, p21 and PUMA play a critical role in modulating MDCK cell morphogenesis by maintaining an appropriate level of the EMT.
P73是p53肿瘤抑制家族的成员，在肿瘤抑制和神经发育中起关键作用。由于使用了两个启动子，p73以两种异构体TAp73和ΔNp73的形式表达，它们具有相反的功能。在这里，我们以Madin-Darby犬肾（MDCK）细胞为模型系统，研究了p73在上皮极性和形态发生中的潜在作用。我们发现，敲低TAp73会增强MDCK细胞在二维（2-D）培养中的增殖和迁移，而敲低ΔNp73则会抑制这种增殖和迁移。我们还发现，敲低TAp73而非ΔNp73会破坏MDCK细胞在三维（3-D）培养中的囊肿形成。有趣的是，我们发现p21和PUMA这两种蛋白，它们均由TAp73诱导但被ΔNp73抑制，是二维培养中抑制细胞增殖和迁移以及三维培养中MDCK细胞形态发生所必需的。最后，我们表明敲低TAp73、p21或PUMA会诱导上皮-间质转化（EMT），同时E-钙黏蛋白减少，EMT转录因子增加。总之，我们的数据表明TAp73、p21和PUMA通过维持适当水平的EMT在调节MDCK细胞形态发生中起关键作用。
