Downregulation of Notch1 inhibits the invasion of human hepatocellular carcinoma HepG2 and MHCC97H cells through the regulation of PTEN and FAK

Abstract

Tumor invasion and metastasis are the main causes of mortality in patients with hepatocellular carcinoma (HCC). Thus, the effective inhibition of these tumorigenic processes is critical in order for HCC therapy to be effective. Previous studies have demonstrated that Notch1 is associated with metastasis in several human malignancies. However, the exact molecular mechanisms underlying the Notch1-mediated induction of the invasion of HCC cells remain poorly understood. In the present study, we demonstrate that, compared to the normal liver cell line, L02, Notch1 is highly expressed in the human HCC cell lines, HepG2 and MHCC97H. Using small interfering RNA (siRNA), we knocked down the expression of Notch1 in the cell lines. Notch1 expression in the HCC cell lines was also measured following transfection with siRNA using RT-PCR and western blot analysis. In addition, a migration and invasion assay was performed to determine the effects of Notch1 knockdown on cell migration and invasion. Our results demonstrated that the downregulation of Notch1 by small interfering RNA (siRNA) significantly inhibited the migration and invasion of both HCC cell lines. Additionally, we demonstrated that the knockdown of Notch1 in both HCC cell lines increased both the total expression of phosphatase and tensin homolog (PTEN) and its phosphorylated form. By contrast, focal adhesion kinase (FAK) and phospho-FAK expression was decreased following Notch1 depletion. Taken together, our data suggest that targeting Notch1 may be a useful therapeutic approach to inhibiting the metastasis of HCC cells.