Abnormal expression of TFIIIB subunits and RNA PolⅢgenes is associated with hepatocellular carcinoma

The levels of the products of RNA polymeraseⅢ-dependent genes(PolⅢgenes),including tRNAs and 5S rRNA,are elevated in transformed and tumor cells,which potentiate tumorigenesis.TFIIB-related factor 1(Brf1)is a key transcription factor and specifically regulates the transcription of PolⅢgenes.In vivo and in vitro studies have demonstrated that a decrease in Brf1 reduces PolⅢgene transcription and is sufficient for inhibiting cell transformation and tumor formation.Emerging evidence indicates that dysregulation of Brf1 and PolⅢgenes is linked to the development of hepatocellular carcinoma(HCC)in humans and animals.We have reported that Brf1 is overexpressed in human liver cancer patients and that those with high Brf1 levels have shorter survivals.This review summarizes the effects of dysregulation of these genes on HCC and their regulation by signaling pathways and epigenetics.These novel data should help us determine the molecular mechanisms of HCC from a different perspective and guide the development of therapeutic approaches for HCC patients.