HNRNPA2B1 regulates hypoxia-related tumor angiogenesis in hilar cholangiocarcinoma through exosomal miR-155-5p

Abstract

Abstract Cancer-cell-secreted miRNAs (miRs) can be packaged into exosomes and are implicated in different aspects of tumor angiogenesis. HNRNPA2B1, as a RNA binding protein, participates in exosomal genesis and cargo sorting. However, little is known about whether HNRNPA2B1 is involved in the exosomal miR sorting process and tumor angiogenesis in hilar cholangiocarcinoma (HCCA) cells under hypoxia. Bioinformatics analysis of miRs in the exosomes secreted by hypoxic HCCA cells demonstrated that miR-155-5p was the miR associated with angiogenesis and bound most effectively to HNRNPA2B1. RNA immunoprecipitation (RIP) revealed that the amount of miR-155-5p bound to HNRNPA2B1 in HCCA cells under hypoxia was 1.43 times higher than that under normoxia. qRT-PCR showed that exosomal miR-155-5p expression was reduced by 66.4% in the HNRNPA2B1 knockdown group (KD) compared with the negative control (NC) group; however, cellular miR-155-5p expression did not differ significantly between the groups. Tube formation assays were used for studying the effect of HNRNPA2B1 and exosomal miR-155-5p on angiogenesis in the hypoxic HCCA cells. Western blotting showed that expression of VEGF-A in HUVECs was consistent with fluctuation in the tube formation assays. In conclusion, HNRNPA2B1 is involved in exosomal miR-155-5p sorting in HCCA cells under hypoxia and can promote tumor angiogenesis via the exosomal miR-155-5p.