Downregulation of long noncoding RNA Sox2ot protects PC-12 cells from hydrogen peroxide-induced injury in spinal cord injury via regulating the miR-211-myeloid cell leukemia-1 isoform2 axis.

This study aimed to investigate the effects and possible mechanisms of long noncoding RNA (lncRNA) Sox2 overlapping transcript (Sox2ot) on hydrogen peroxide (H2 O2 )-induced injury in pheochromocytoma (PC-12) cells. PC-12 cells were treated with H2 O2 to cell injury. The cells were transfected with short-hairpin RNA directed against Sox2ot (sh-Sox2ot), small interfering RNA directed against myeloid cell leukemia-1 (MCL-1) isoform2 (si-MCL-1), a miR-211 mimic, a miR-211 inhibitor, and their negative controls. Under different transfected treatments, cell viability, migration, invasion, and apoptosis as well as the expressions of apoptosis- and autophagy-related proteins were investigated. Besides, the regulatory relationships between Sox2ot and miR-211, miR-211 and MCL-1, as well as between MCL-1 and the protein kinase B (Akt)/mammalian target of the rapamycin (mTOR)/p70 ribosomal S6 protein kinase (p70S6K) signaling pathway were explored. Suppression of Sox2ot inhibited H2 O2 -induced PC-12 cell injury by increasing cell viability, migration, invasion, and decreasing apoptosis and autophagy. Moreover, suppression of Sox2ot increased miR-211 expression and alleviated H2 O2 -induced injury in PC-12 cells possibly via upregulation of miR-211. Furthermore, MCL-1 isoform2 was identified as a direct target of miR-211 and could be negatively regulated by miR-211. Suppression of miR-211 aggravated H2 O2 -induced cell injury by regulation of MCL-1 isoform2. Besides, inhibition of miR-211 suppressed the activation of the Akt/mTOR/p70S6K signaling pathway in H2 O2 -treated PC-12 cells, which was reversed after knockdown of MCL-1 isoform2 at the same time. Our findings indicate that downregulation of Sox2ot may protect PC-12 cells from H2 O2 -induced injury in SCI via targeting the miR-211/MCL-1 isoform2 axis. MCL-1 isoform2 may further regulate the activation of the Akt/mTOR/p70S6K pathway to mediate H2 O2 -induced injury. The Sox2ot-miR-211-MCL-1 isoform2 axis may be a promising therapeutic strategy for SCI.