Pro-Angiogenic Role of LncRNA HULC in Microvascular Endothelial Cells via Sequestrating miR-124

Background/Aims: HULC is a multifunctional lncRNA that has pro-angiogenic function in various cancers. The present study was designed to see the role of lncRNA HULC in normal endothelial cells angiogenesis. Methods: Cell viability, apoptosis, migration, tube formation and expression levels of angiogenesis-related proteins were respectively assessed in human microvascular endothelial HMEC-1 cells after lncRNA HULC was silenced by shRNA transfection. Cross-regulation between lncRNA HULC and miR-124, and between miR-124 and MCL-1 were detected by qRT-PCR, sequence analysis, and luciferase reporter assay. Results: Silence of lncRNA HULC significantly reduced viability, migration, tube formation and protein levels of VEGF, VEGFR2, CD144 and eNOS in HMEC-1 cells. Meanwhile, silence of lncRNA HULC induced apoptosis in HMEC-1 cells, as Bcl-2 was down-regulated, Bax was up-regulated, and caspase-3 and -9 were cleaved. miR-124 expression was negatively regulated by lncRNA HULC, and HULC worked as a molecular sponge for miR-124, in having miR-124 exhausted. Besides, MCL-1 was a target gene of miR-124. Rescue assay results showed that the effects of lncRNA HULC silence on HMEC-1 cells growth, migration and angiogenesis were abolished by miR-124 suppression. Similarly, the effects of miR-124 on HMEC-1 cells were abolished by MCL-1 overexpression. Furthermore, MCL-1 activated PI3K/AKT and JAK/STAT signaling pathways. Conclusion: These findings suggest a pro-angiogenic role of lncRNA HULC in endothelial cells. The pro-angiogenic actions of lncRNA HULC may be through sponging miR-124, preventing MCL-1 from degradation by miR-124.