Lycium barbarum polysaccharides protects H9c2 cells from hypoxia-induced injury by down-regulation of miR-122.

BACKGROUND:Lycium barbarum polysaccharides (LBPs) are major ingredients of fructus lycii, which have multiple pharmacological activities, such as antioxidant, neuroprotective, and anti-inflammatory activities. This study attempted to reveal the potential of LBPs in hypoxia-injured H9c2 cells and the possible underlying mechanisms. METHODS:H9c2 cells were treated by 300 μg/mL LBPs for 24 h upon hypoxia. Subsequently, the changes in cell viability, migration and apoptosis were evaluated. pre-miR-122 or miR-122 sponge was transfected into H9c2 cells to investigate whether miR-122 was involved in the mechanisms of LBPs' action. Besides, an animal model of myocardial infarction (MI) was established, and the in vivo effects of LBPs were further investigated. RESULTS:LBPs increased cell viability, down-regulated p53, p21 and p16 protein expressions, improved migration, and repressed apoptosis in hypoxia-injured H9c2 cells. miR-122 was highly expressed in response to hypoxia, while was down-regulated by addition of LBPs. The protective actions of LBPs in hypoxia-injured H9c2 cells were attenuated by miR-122 overexpression, while were accelerated by miR-122 suppression. Also, LBPs-induced the activation of MEK/ERK and AMPK signaling pathways were attenuated by miR-122 overexpression, and were accelerated by miR-122 suppression. in vivo investigation revealed that, MI rats administrated with LBPs decreased infarct size and improved cardiac function via down-regulation of miR-122. CONCLUSION:LBPs exhibited in vitro and in vivo cardioprotective activities via down-regulating miR-122. LBPs may have potential for the treatment of acute myocardial infarction (AMI).