Abstract
Hepatocellular carcinoma (HCC) is the most common type of liver cancer in humans. The focal adhesion tyrosine kinase (FAK) is often over-expressed in human HCC and FAK inhibition may reduce HCC cell invasiveness. However, the anti-oncogenic effect of FAK knockdown in HCC cells remains to be clarified. We found that FAK depletion in HCC cells reduced in vitro and in vivo tumorigenicity, by inducing G2/M arrest and apoptosis, decreasing anchorage-independent growth, and modulating the expression of several cancer-related genes. Among these genes, we showed that FAK silencing decreased transcription and nuclear localization of enhancer of zeste homolog 2 (EZH2) and its tri-methylation activity on lysine 27 of histone H3 (H3K27me3). Accordingly, FAK, EZH2 and H3K27me3 were concomitantly upregulated in human HCCs compared to non-tumor livers. In vitro experiments demonstrated that FAK affected EZH2 expression and function by modulating, at least in part, p53 and E2F2/3 transcriptional activity. Moreover, FAK silencing downregulated both EZH2 binding and histone H3K27me3 levels at the promoter of its target gene NOTCH2. Finally, we found that pharmacological inhibition of FAK activity resembled these effects although milder. In summary, we demonstrate that FAK depletion reduces HCC cell growth by affecting cancer-promoting genes including the pro-oncogene EZH2. Furthermore, we unveil a novel unprecedented FAK/EZH2 crosstalk in HCC cells, thus identifying a targetable network paving the way for new anticancer therapies.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Aminopyridines / pharmacology
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Animals
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Apoptosis / drug effects
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Apoptosis / genetics
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Carcinoma, Hepatocellular / genetics*
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Carcinoma, Hepatocellular / metabolism
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Carcinoma, Hepatocellular / pathology
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Cell Line, Tumor
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Cell Proliferation / drug effects
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E2F2 Transcription Factor / genetics
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E2F2 Transcription Factor / metabolism
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E2F3 Transcription Factor / genetics
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E2F3 Transcription Factor / metabolism
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Enhancer of Zeste Homolog 2 Protein / genetics*
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Enhancer of Zeste Homolog 2 Protein / metabolism
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Focal Adhesion Kinase 1 / antagonists & inhibitors
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Focal Adhesion Kinase 1 / genetics*
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Focal Adhesion Kinase 1 / metabolism
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G2 Phase Cell Cycle Checkpoints
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Gene Expression Regulation, Neoplastic*
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Hep G2 Cells
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Histones / genetics
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Histones / metabolism
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Humans
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Liver Neoplasms / genetics*
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Liver Neoplasms / metabolism
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Liver Neoplasms / pathology
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Male
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Mice
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Mice, Nude
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Neoplasm Transplantation
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Promoter Regions, Genetic
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RNA, Small Interfering / genetics
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RNA, Small Interfering / metabolism
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Receptor, Notch2 / genetics*
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Receptor, Notch2 / metabolism
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Signal Transduction
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Tumor Suppressor Protein p53 / genetics
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Tumor Suppressor Protein p53 / metabolism
Substances
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Aminopyridines
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E2F2 Transcription Factor
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E2F3 Transcription Factor
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E2f2 protein, mouse
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E2f3 protein, mouse
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Histones
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Notch2 protein, mouse
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PND 1186
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RNA, Small Interfering
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Receptor, Notch2
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Tumor Suppressor Protein p53
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Enhancer of Zeste Homolog 2 Protein
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Ezh2 protein, mouse
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Focal Adhesion Kinase 1
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Ptk2 protein, mouse