LncRNA HCG18 is critical for vascular smooth muscle cell proliferation and phenotypic switching.

Previous studies have shown that some specific long non-coding RNAs are dysregulated in vascular walls and abnormally expressed in vascular disease. LncRNA HLA complex group 18 (HCG18) is a member of the HLA complex group, which has been rarely investigated in human diseases. In this study, we aimed to investigate the role of HCG in vascular smooth muscle cells. HCG18 was over-expressed by adenovirus transfection and knocked down in vascular smooth muscle cells by shRNA. Cell proliferation was detected by CCK-8 assays. Flow cytometry was employed to test the impacts of HCG18 on vascular smooth muscle apoptotic cells. The expression of associated genes in protein and mRNA levels was detected by western blotting, immunofluorescence and qRT-PCR. The interactions between HCG18 and fused in sarcoma (FUS) were confirmed by RNA EMSA and RIP assays. The expression of serum HCG18 was decreased in hypertensive patients and PDGF-BB-treated vascular smooth muscle cells. HCG18 inhibited proliferation and induced apoptotic cells in vascular smooth muscle cells. In addition, we also found that HCG18 can inhibit vascular smooth muscle cell phenotypic switching from a contractile to a secretory phenotype. Finally, our results showed that HCG18 enhanced apoptotic cells by directly binding with FUS. Our findings reveal that HCG18 is involved in the regulation of proliferation, apoptosis and the expression levels of markers of the contractile and synthetic phenotype.