Abstract 124: Hypoxia-inducible miR-210 is involved in hypoxia-induced cell migration and invasion in human hepatocellular carcinoma

Abstract

Abstract MicroRNA dysregulation is implicated in many human malignancies, yet little is known regarding the regulatory mechanisms of these small noncoding RNAs. Hypoxia is a prevalent tumor microenvironment in hepatocellular carcinoma (HCC) and plays a key role in modulating tumor aggressiveness. In the present study, we investigated the effects of hypoxia on microRNA expression in human HCC. First, we examined the miRNA expression profiles with TaqMan human microRNA Low-Density Array on HCC cell lines put under normoxic and hypoxic conditions to identify expression changes of microRNA. From the 664 microRNAs examined, miR-210 was overexpressed in SMMC-7721, Huh-7 and MHCC-97L HCC cell lines under 0.1% O2 hypoxic condition. The hypoxic induction of miR-210 was further validated in another two HCC cell lines (Hep3B and PLC/PRF/5) by individual real-time quantitative PCR (qPCR) and the same expression pattern was observed, suggesting that miR-210 is consistently induced in HCC cells under hypoxic conditions. The abundance of mature human miR-210 was also examined by qPCR in a human HCC cohort consisting of 48 pairs of primary HCC tissues and their corresponding non-tumorous livers. We found that miR-210 expression was significantly higher in the HCC tissues as compared with the corresponding non-tumorous livers (P=0.0003). Furthermore, we used the hypoxia marker carbonic anhydrase IX (CAIX) coupled with microdissection technique to isolate tissue samples in the peri-necrotic areas, which are considered pathologically hypoxic, in clinical formalin-fixed paraffin-embedded (FFPE) HCC samples. We extracted the microRNA from the tissues and compared the miR-210 expression with those from histologically preserved HCC areas away from necrotic areas. In line with the in vitro observations, with qPCR, miR-210 was remarkably overexpressed in hypoxic HCC regions. Furthermore, miR-210 overexpression significantly and inversely correlated with the overall survival and disease-free survival rates (P= 0.029 and 0.043, respectively) of HCC patients, indicating that overexpression of miR-210 in HCC was associated with a poorer prognosis. The biological function of the miR-210 induction in HCC was also investigated. Notably, with transwell and cell invasion assays, we demonstrated that the cell migratory and invasive abilities of SMMC-7721 were dramatically enhanced during hypoxia, and this enhancement was abolished upon miR-210 suppression using locked nucleic acid (LNA) inhibitor. Taken together, our present data indicate that miR-210 is a hypoxia-inducible microRNA in HCC, which may enhance HCC aggressiveness under hypoxic conditions. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 124. doi:1538-7445.AM2012-124