title: Krüppel-like factor 4, a tumor suppressor in hepatocellular carcinoma cells reverts epithelial mesenchymal transition by suppressing slug expression.
abstract: Krüppel-like factor 4 (KLF4) is a zinc-finger transcription factor that plays an important role in differentiation and pathogenesis. KLF4 has been suggested to act as an oncogene or tumor suppressor in different tumor types. However, the role of KLF4 in hepatocellular carcinoma (HCC) remains unclear. Here, we demonstrate that forced expression of Klf4 in murine HCC cell lines reduced anchorage-independent growth in soft agar as well as cell migration and invasion activities in vitro. Ectopic Klf4 expression impaired subcutaneous tumor growth and lung colonization in vivo. By contrast, Klf4 knockdown enhanced HCC cell migration. Interestingly, ectopic expression of Klf4 changed the morphology of murine HCC cells to a more epithelial phenotype. Associated with this, we found that expression of Slug, a critical epithelial mesenchymal transition (EMT)-related transcription factor, was significantly down-regulated in Klf4-expressing cells. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays showed that Klf4 is able to bind and repress the activity of the Slug promoter. Furthermore, ectopic Slug expression partially reverts the Klf4-mediated phenotypes. Consistent with a role as a tumor suppressor in HCC, analysis of the public microarray databases from Oncomine revealed reduced KLF4 expression in human HCC tissues in comparison with normal liver tissues in 3 out of 4 data sets. By quantitative reverse transcription-polymerase chain reaction (qRT-PCR), we found reduced KLF4 mRNA in 50% of HCC tissues. Importantly, an inverse correlation between the expression of KLF4 and SLUG was found in HCC tissues. Our data suggest that KLF4 acts as a tumor suppressor in HCC cells, in part by suppressing SLUG transcription.
authors.affiliation: National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan.
authors.forename: Ze-Shiang
authors.initials: ZS
authors.lastname: Lin
authors.forename: Hsiao-Chien
authors.initials: HC
authors.lastname: Chu
authors.forename: Yi-Chen
authors.initials: YC
authors.lastname: Yen
authors.forename: Brian C
authors.initials: BC
authors.lastname: Lewis
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Chen
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; C000604407:SNAI1 protein, human; C000604449:Snai2 protein, mouse; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors