Suppression of CK-19 expression by shRNA can inhibit the malignancy of hepatocellular carcinoma cells

Objective: Cytokeratin-19 (CK-19) is highly expressed in a novel subtype of hepatocellular carcinomas (HCC) displaying both hepatocellular and cholangiocellular differentiation which we firstly defined as dual-phenotype HCC (DPHCC). Compared with patients with classical HCC, the patients with DPHCC showed worse clinical prognosis. However, the role of CK-19 in development of DPHCC remains unknown. The main purpose of the present study was to investigate the possible effect of CK-19 on the malignant phenotype of DPHCC and its possible value as a potential therapeutic target. Methods: In this study, we prospectively examined the CK-19 expression in 404 clinical HCC tissues and evaluated its clinical significance. We also evaluated the biological function of CK-19 both in vitro and in vivo using knockdown HCC cells. Results: Our results showed that CK-19 expression was significantly associated with TNM stage (p = 0.011) and vascular invasion (p = 0.035). Patients with positive CK-19 expression had poorer overall-survival and disease-free survival, whereas those with negative CK-19 expression survived longer. Knockdown of CK-19 can reduce the MHCC-97H cell proliferation (p = 0.006) and the number of colonies formed in soft agar (p = 0.0043). The number of MHCC-97H cells invading the matrigel coated membrane was decreased in CK-19 knockdown cells (p = 0.038). In addition, the in vivo experiments in mice showed the tumor weight was significantly reduced in CK-19 knockdown group (0.257 +/- 0.081 g) compared with negative control (0.443 +/- 0.114 g) (P < 0.01). Our findings demonstrated the biological function in HCC cell lines of CK-19 expression, since suppression of CK-19 inhibits the growth of tumor cells both in vitro and vivo. Conclusion: Taken together, our results implied that CK-19 not only could be a candidate pathobiological biomarker for evaluating the malignant extent of DPHCC, also could consider being a potential candidate therapy target in DPHCC.