Lycium Barbarum Polysaccharides Alleviates Oxidative Damage Induced by H2O2 Through Down-Regulating MicroRNA-194 in PC-12 and SH-SY5Y Cells.

BACKGROUND/AIMS: Currently, scientists attempt to improve outcome of spinal cord injury (SCI) via reducing secondary injury during SCI. Oxidative stress is critical for pathophysiology of secondary damage, thus we mainly focused on the anti-oxidant effects of Lycium barbarum polysaccharides (LBPs) on PC-12 and SH-SY5Y cells as well as the underlying mechanisms. METHODS: Oxidative stress was induced by H2O2 stimulation. Effects of LBPs on cell viability, apoptosis, and expression of proteins associated with apoptosis and autophagy in H2O2-induced cells were assessed by CCK-8 assay, flow cytometry assay and Western blot analysis, respectively. Then, expression of miR-194 was determined by qRT-PCR. Expression of miR-194 was dysregulated, and whether LBPs affected H2O2-treated cells through modulating miR-194 was verified. The expression of key kinases in the PI3K/AKT pathway and the intracellular levels of ROS and NO were testified by Western blot analysis and flow cytometry with fluorescent probes. RESULTS: H2O2-induced decrease of cell viability and increases of apoptosis and autophagy in PC-12 cells were mitigated by LBPs treatment. Next, we found that miR-194 expression was both down-regulated by LBPs treatment in PC-12 and SH-SY5Y cells. More experiments consolidated that influence of LBPs on H2O2-treated cells was reversed by miR-194 overexpression while was augmented by miR-194 inhibition. LBPs elevated the phosphorylated levels of PI3K and AKT and reduced levels of ROS and NO through miR-194. CONCLUSION: LBPs alleviated H2O2-induced decrease of cell viability, and increase of apoptosis and autophagy through down-regulating miR-194. Moreover, LBPs activated the PI3K/AKT pathway and reduced oxidative stress through miR-194.

Silencing SUMO2 promotes protection against degradation and apoptosis of nucleus pulposus cells through p53 signaling pathway in intervertebral disc degeneration.

OBJECTIVE: Intervertebral disc degeneration (IDD), as a common cause of back pain, is related to the promotion of cellular senescence and reduction in proliferation. Based on recent studies, small ubiquitin-related modifier (SUMO) proteins have been implicated in various biological functions. Therefore, in the present study, we investigated the effects of SUMO2 on proliferation and senescence of nucleus pulposus cells (NPCs) via mediation of p53 signaling pathway in rat models of IDD. METHODS: After the establishment of rat models of IDD for the measurement of positive expression of SUMO2/3 protein, the mRNA and protein levels of SUMO2, molecular phenotype [matrix metalloproteinase-2 (MMP-2) and hypoxia-inducible factor-1α (HIF-1α)] and p53 signaling pathway-related genes [p21, murine double minute-2 (MDM2), growth arrest and DNA-damage-inducible protein 45 α (GADD45α), cyclin-dependent kinase 2/4 (CDK2/4), and CyclinB1] were determined, followed by the detection of cell proliferation, cell cycle, apoptosis, and cell senescence. RESULTS: The rat models of IDD were successfully constructed. The results obtained showed that there was a higher positive expression of SUMO2/3 protein in IDD rats. Moreover, the silencing of the SUMO2 gene decreases the levels of SUMO2, p53, p21, MDM2, GADD45α, MMP-2, and HIF-1α expressions and p53 phosphorylation level while it increases the levels of CDK2/4 and CyclinB1 expressions. In addition, SUMO2 gene silencing enhances proliferation and suppresses apoptosis and cell senescence of NPCs. CONCLUSION: In conclusion, SUMO2 gene silencing promotes proliferation, and inhibits the apoptosis and senescence of NPCs in rats with IDD through the down-regulation of the p53 signaling pathway. Thus, SUMO2 is a potential target in the treatment of IDD.