Background: Hepatocyte nuclear factor-3β (HNF-3β) plays a critical role in hepatocyte differentiation and controls liver-specific gene expression during the development of hepatocellular carcinoma (HCC), but the molecular basis of this process has not been fully elucidated. microRNAs (miRNAs) are powerful, post-transcriptional regulators of gene expression. Whether miRNAs can impact the effects of HNF-3β in HCC is still unknown.
Methods: HNF-3β and miR-141 expression levels were detected in HepG2 cells, using real-time quantitative RT-PCR (qRT-PCR). Luciferase reporter assays and Western blots were used to validate HNF-3β as a direct target gene of miR-141. Cell proliferation, invasion, and apoptosis were also examined to confirm whether miR-141 could impact on HNF-3β in HCC.
Results: In this study, we found that HNF-3β protein levels were consistently upregulated in HCC clinical tissues compared with matched normal adjacent tissues. However, the mRNA levels of HNF-3β varied in random tissues, suggesting that a post-transcriptional mechanism was involved in its regulation. We used bioinformatic analyses to search for miRNAs that could potentially target HNF-3β, and identified specific targeting sites for miR-141 in the 3'-untranslated region (3'-UTR) of the HNF-3β gene. By overexpressing miR-141 in HepG2 cells, we experimentally validated that miR-141 directly regulated HNF-3β expression. Furthermore, the biological consequences of targeting HNF-3β by miR-141 were examined using cell proliferation, invasion and apoptosis assays in vitro. We demonstrated that the repression of HNF-3β by miR-141 suppressed the proliferation and invasion and promoted the apoptosis of HepG2 cells.
Conclusions: miR-141 functions as a tumor suppressor in HCC cells through the inhibition of HNF-3β translation.