lncRNA BSG-AS1 is hypoxia-responsive and promotes hepatocellular carcinoma by enhancing BSG mRNA stability.

Emerging evidence indicates that aberrant changes of lncRNAs expression induced by hypoxia participate in the development of HCC. The present study aimed to identify novel hypoxia-responsive lncRNAs and reveal its role and mechanism in HCC. Hypoxia exposure in HCC tissues was comprehensively estimated based on public data using multiple hypoxia gene signatures. Huh7 cells were treated with hypoxia and RNA-seq was performed. Then we analyzed the changes of lncRNAs in HCC tissues and cells exposed to hypoxia. We found that lncRNA BSG-AS1 was highly expressed in tissues with high hypoxia score. Then we verified the response of lncRNA BSG-AS1 to hypoxia in the cell hypoxia model in vitro. Through functional phenotypic analysis, we found that lncRNA BSG-AS1 can mediate the promoting effect of hypoxia on the proliferation and migration in HCC cells. RNA-seq was used to find the downstream target genes of lncRNA BSG-AS1. Sequencing data and wet experiments showed that mRNA of BSG decreased after knockout of lncRNA BSG-AS1, and mediated the promotive effect of lncRNA BSG-AS1 on proliferation and migration in HCC cells. The mechanism is that lncRNA BSG-AS1 can enhance the stability of BSG mRNA as antisense lncRNA. Finally, the data based on the public cohort and the cohort we collected suggested that the overexpression of lncRNA BSG-AS1 and BSG are related to the poor prognosis. In conclusion, lncRNA BSG-AS1 is a novel hypoxia-responsive lncRNA. LncRNA BSG-AS1 can positively regulate BSG, by maintaining the mRNA stability of BSG, thus promoting the proliferation and migration of HCC. High expression of lncRNA BSG-AS1 and BSG are risk factors for prognosis.