Differentiation Therapy of Hepatocellular Carcinoma in Mice with Recombinant Adenovirus Carrying Hepatocyte Nuclear Factor-4α Gene

Previous studies have shown that hepatocyte nuclear factor-4 alpha (HNF4 alpha) is a central regulator of differentiated hepatocyte phenotype and forced expression of HNF4 alpha could promote reversion of tumors toward a less invasive phenotype. However, the effect of HNF4 alpha on cancer stem cells (CSCs) and the treatment of hepatocetlular carcinoma (HCC) with HNF4 alpha have not been reported. In this study, an adenovirus-mediated gene delivery system, which could efficiently transfer and express HNF4 alpha, was generated to determine its effect on hepatoma cells (Hep3B and HepG2) in vitro and investigate the anti-tumor effect of HN174 alpha in mice. Our results demonstrated that forced re-expression of HNF4 alpha induced the differentiation of hepatoma cells into hepatocytes, dramatically decreased stemness gene expression and the percentage of CD133(+) and CD90(+) cells, which are considered as cancer stem cells in HCC. Meanwhile, HNF4 alpha reduced cell viability through inducing apparent apoptosis in Hep3B, while it induced cell cycle arrest and cellular senescence in HepG2. Moreover, infection of hepatoma cells by HNF4 alpha abolished their tumorigenesis in mice. Most interestingly, systemic administration of adenovirus carrying the HNF4 alpha gene protected mice from liver metastatic tumor formation, and intratumoral injection of HNF4 alpha also displayed significant antitumor effects on transplanted tumor models. Conclusion. The striking suppression effect of HNF4 alpha on tumorigenesis and tumor development is attained by inducing the differentiation of hepatoma cells-especially CSCs-into mature hepatocytes, suggesting that differentiation therapy with HNF4 alpha may be an effective treatment for HCC patients. Our study also implies that differentiation therapy may present as one of the best strategies for cancer treatment through the induction of cell differentiation by key transcription factors. (HEPATOLOGY 2008,48:1528-1539.)