FAK Kinase Activity Is Required for the Progression of c-MET/β-Catenin-Driven Hepataocellular Carcinoma

Abstract

Background & Aims There is an urgent need to develop new and more effective therapeutic strategies and agents to treat hepatocellular carcinoma (HCC). We have recently found that deletion of Fak in hepatocytes before tumors form inhibits tumor development and prolongs survival of animals in a c-Met (MET)/β-catenin (CAT)-driven HCC mouse model. However, it has yet to be determined whether FAK expression in hepatocytes promotes MET/CAT-induced HCC progression after tumor initiation. In addition, it remains unclear whether FAK promotes HCC development through its kinase activity. Methods We generated hepatocyte-specific inducible Fak-deficient mice (Alb-creERT2; Fakflox/flox) to examine the role of FAK in HCC progression. We re-expressed wild-type and mutant FAK in Fak-deficient mice to determine FAK’s kinase activity in HCC development. We also examined the efficacy of a FAK kinase inhibitor PF-562271 on HCC inhibition. Results We found that deletion of Fak after tumors form significantly repressed MET/CAT-induced tumor progression. Ectopic FAK expression restored HCC formation in hepatocyte-specific Fak-deficient mice. However, overexpression of a FAK kinase-dead mutant led to reduced tumor load compared to mice which express wild-type FAK. Furthermore, PF-562271 significantly suppressed progression of MET/CAT-induced HCC. Conclusion Fak kinase activity is important for MET/CAT-induced HCC progression. Inhibiting FAK kinase activity provides a potential therapeutic strategy to treat HCC.

Focal Adhesion Kinase and β‐Catenin Cooperate to Induce Hepatocellular Carcinoma

“…It remains unknown whether overexpression of FAK alone is sufficient to induce HCC. To address this question, we hydrodynamically injected a previously generated FAK transposon vector, pT3‐EF1α‐FAK‐IRES‐GFP (pT3‐FAK), or a control plasmid, pT3‐EF1α‐IRES‐GFP (pT3‐GFP) with the transposase vector (HSB2) into C57BJ/6 mice. We first confirmed overexpression of FAK in approximately 15% of hepatocytes in the livers injected with pT3‐FAK compared to those injected with control (Fig.…”

“…The plasmids pT3‐internal ribosome entry site (IRES)‐green fluorescent protein (GFP), pT3‐FAK‐IRES‐GFP, pT3‐FAK (K454R)‐IRES‐GFP, pT3‐ CAT, and pT3‐MET were generated by Gateway cloning as described . The plasmids were purified using the GeneJET Plasmid Maxiprep Kit (Thermo Fisher Scientific) for hydrodynamic tail vein injection.…”

“…Immunohistochemical (IHC) staining was performed as described . Cells with positive staining were scored in at least five fields at ×400 or ×200 magnification and reported as mean ± standard deviation (SD).…”

“…FAK is often overexpressed in HCC specimens, offering a potential target for the treatment of HCC. We have recently reported that deletion of Fak in hepatocytes or the administration of a FAK inhibitor blocks tumor proliferation and development and prolongs the survival of experimental animals in a mesenchymal–epithelial transition factor (c‐Met)/β‐catenin‐driven HCC mouse model, suggesting that FAK is required for c‐Met/β‐catenin‐driven hepatocarcinogenesis. However, it is not yet known whether the overexpression of FAK by itself is sufficient for hepatocarcinogenesis or whether there is a need for cooperation with other oncogene products to induce HCC.…”

Inhibition of insulin‐like growth factor 1 receptor enhances the efficacy of sorafenib in inhibiting hepatocellular carcinoma cell growth and survival

“…Terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick‐end labeling (TUNEL) staining was performed as described26 using a kit purchased from Millipore (Cat#S7101). The TUNEL‐positive cell numbers were scored in at least five fields (magnification ×400) per mouse and are reported as means ± SD.…”