KLF8 promotes tumorigenesis, invasion and metastasis of colorectal cancer cells by transcriptional activation of FHL2
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Qingqing Yan1, Wenjing Zhang1, Yao Wu1, Meiyan Wu1, Mengnan Zhang1, Xinpeng Shi1, Jinjun Zhao2, Qingzhen Nan1, Ye Chen1, Long Wang3, Tianming Cheng1, Jiachu Li4, Yang Bai1, Side Liu1, Jide Wang1
1Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
2Department of Rheumatism, Nanfang Hospital, Southern Medical University, Guangzhou, China
3Division of Vascular Interventional Radiology, Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
4Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, China
Jide Wang, e-mail: [email protected]
Side Liu, e-mail: [email protected]
Keywords: KLF8, EMT, FHL2, metastasis, colorectal cancer
Abbreviations: EMT, epithelial-to-mesenchymal transition; FHL2, four-and-a-half LIM-only protein 2; RLU, relative luciferase unit; ATCC, american type culture collection; ChIP, chromatin immunoprecipitation
Received: December 10, 2014 Accepted: July 03, 2015 Published: July 15, 2015
The transcription factor Krüppel-like factor (KLF)8 plays an important role in the formation of several human tumors, including colorectal cancer. We recently identified four-and-a-half LIM protein 2 (FHL2) as a critical inducer of the epithelial-to-mesenchymal transition (EMT) and invasion. However, the molecular mechanism by which KLF8 affects FHL2-mediated tumor proliferation, EMT and metastasis remains unknown. Here, we showed that KLF8 overexpression promoted EMT and metastatic phenotypes. KLF8 expression was stimulated by transforming growth factor (TGF)-β1. Moreover, KLF8 acted as a potential EMT inducer by stimulating vimentin expression and inducing a loss of E-cadherin in stable KLF8-transfected cells. KLF8 overexpression induced a strong increase in FHL2 expression, and a positive correlation between the expression patterns of KLF8 and FHL2 was observed in CRC cells. Promoter reporter and chromatin immunoprecipitation (ChIP) assays demonstrated that KLF8 directly bound to and activated the human FHL2 gene promoter. However, siRNA-mediated repression of FHL2 in KLF8-overexpressing cells reversed the EMT and the proliferative and metastatic phenotypes. In vivo, KLF8 promoted FHL2-mediated proliferation and metastasis via orthotopic implantation. Taken together, this work identified KLF8-induced FHL2 activation as a novel and critical signaling mechanism underlying human breast/colorectal cancer invasion and metastasis.
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