The enforced expression of c-Myc in pig fibroblasts triggers mesenchymal-epithelial transition (MET) via F-actin reorganization and RhoA/Rock pathway inactivation

• Published in: Cell cycle (Georgetown, Tex.) Tex.), 2013-04, Vol.12 (7), p.1119-1127
• Main Authors: Shi, Jun-Wen, Liu, Wei, Zhang, Ting-Ting, Wang, Sheng-Chun, Lin, Xiao-Lin, Li, Jing, Jia, Jun-Shuang, Sheng, Hong-Fen, Yao, Zhi-Fang, Zhao, Wen-Tao, Zhao, Zun-Lan, Xie, Rao-Ying, Yang, Sheng, Gao, Fei, Fan, Quan-Rong, Zhang, Meng-Ya, Yue, Min, Yuan, Jin, Gu, Wei-Wang, Yao, Kai-Tai, xiao, dong
• Format: Article
• Language: English
• Subjects: Actins - metabolism; Animals; c-Myc; Cell Adhesion; Cell Movement; Cells, Cultured; cytoskeleton reorganization; dermal fibroblasts; Dermis - cytology; embryonic fibroblasts; Epithelial-Mesenchymal Transition; Fibroblasts - cytology; Fibroblasts - metabolism; HEK293 Cells; Humans; mesenchymal stem cells; Mesenchymal Stromal Cells - cytology; Mesenchymal Stromal Cells - metabolism; mesenchymal-epithelial transition (MET); Proto-Oncogene Proteins c-myc - genetics; Proto-Oncogene Proteins c-myc - metabolism; rho-Associated Kinases - metabolism; rhoA GTP-Binding Protein - metabolism; RhoA/Rock pathway; RNA, Messenger - metabolism; Swine; Tibetan miniature pigs; Transfection
• ISSN: 1538-4101; 1551-4005
• DOI: 10.4161/cc.24164

In previous studies from other labs it has been well demonstrated that the ectopic expression of c-Myc in mammary epithelial cells can induce epithelial-mesenchymal transition (EMT), whereas in our pilot experiment, epithelial-like morphological changes were unexpectedly observed in c-Myc-expressing pig fibroblasts [i.e., porcine embryonic fibroblasts (PEFs) and porcine dermal fibroblasts (PDFs)] and pig mesenchymal stem cells, suggesting that the same c-Myc gene is entitled to trigger EMT in epithelial cells and mesenchymal-epithelial transition (MET) in fibroblasts. This prompted us to characterize the existence of a MET in c-Myc-expressing PEFs and PDFs at the molecular level. qRT-PCR, immunofluorescence and western blot analysis illustrated that epithelial-like morphological changes were accompanied by the increased expression of epithelial markers [such as cell adhesion proteins (E-cadherin, α-catenin and Bves), tight junction protein occludin and cytokeratins (Krt8 and Krt18)], the reduced expression of mesenchymal markers [vimentin, fibronectin 1 (FN1), snail1, collagen family of proteins (COL1A1, COL5A2) and matrix metalloproteinase (MMP) family (MMP12 and MMP14)] and the decreased cell motility and increased cell adhesion in c-Myc-expressing PEFs and PDFs. Furthermore, the ectopic expression of c-Myc in pig fibroblasts disrupted the stress fiber network, suppressed the formation of filopodia and lamellipodia, and resulted in RhoA/Rock pathway inactivation, which finally participates in epithelial-like morphological conversion. Taken together, these findings demonstrate, for the first time, that the enforced expression of c-Myc in fibroblasts can trigger MET, to which cytoskeleton depolymerization and RhoA/Rock pathway inactivation contribute.