The role of serum response factor in hepatocellular carcinoma: implications for disease progression.

Serum response factor (SRF) regulates transcription of the immediate early genes and triggers proliferation, migration and differentiation in several types of cells. We examined the role of SRF in HCC by transfecting the SRF cDNA in HLE cells and the SRF anti-sense cDNA in sarcomatoid HCC cells. The overexpression of SRF in the HLE cells significantly increased the cell growth and proliferation. Overexpression of SRF increased actin polymerization of the HCC cells and induced morphologic changes. The mesenchymal markers vimentin, N-cadherin and RhoA were highly expressed in the SRF-transfected HLE cells. Furthermore, the overexpression of SRF in the HLE cells increased the expression levels of the active form of the beta-catenin and Wnt/beta-catenin target genes, such as c-myc and cyclin D1. The overexpression of SRF significantly enhanced the cell migration and invasiveness of HCC cells. Conversely, inhibition of the SRF expression in the sarcomatoid SH-J1 cells by the SRF anti-sense cDNA significantly decreased migration and invasion through the attenuated expression of mesenchymal markers and the proteins involved in the Wnt/beta-catenin pathway. These results indicate that the overexpression of SRF in HCC cells modulates the Wnt/beta-catenin pathway, and this plays an important role in HCC progression.