The aim of the current study is to elucidate the mechanism of
proline-rich tyrosine kinase 2 (Pyk2)-mediated cell proliferation and invasiveness in
hepatocellular carcinoma (HCC) cells. Human HCC cell lines PLC and MHCC97L were stably transfected with either full-length Pyk2 or C-terminal non-
kinase region of Pyk2 (PRNK). Functional studies on cell proliferation and invasion were conducted in vitro by colony formation assay, adhesion assay, migration assay and wound-healing assay. For the in vivo study, an orthotopic nude mice liver
tumor model was applied to investigate the effects of Pyk2 overexpression on
tumor growth and
metastasis. Overexpression of Pyk2 in PLC cells resulted in an upregulation of colony formation (P = 0.021) and adhesion toward
laminin (P = 0.018). Pyk2 promoted
wound recovery by stimulation of actin stress fiber polymerization. In the in vivo study, transfection of PRNK in MHCC97L cells significantly decreased
tumor volume (P = 0.001) and the incidence of lung
metastasis (P = 0.014). Overexpression of Pyk2 promoted the activation of c-Src, formation of Pyk2/c-Src complex and activated the
extracellular signal-regulated kinase (ERK)/
mitogen-activated protein kinase (MAPK)-signaling pathway. Pyk2 upregulated the activation of ERK1/2 that is insensitive to
MAPK/ERK kinase (
MEK)1/2 inhibition. On the contrary, PRNK overexpression downregulated the activation of c-Src and ERK/MAPK-signaling pathways. Immunofluorescence staining showed that the focal adhesion localization of Pyk2 is a major determinant for c-Src and ERK/MAPK activation. In conclusion, our results showed that Pyk2 promoted cell proliferation and invasiveness by upregulation of the c-Src and ERK/MAPK-signaling pathways.