Gastrodin protects rat cardiomyocytes H9c2 from hypoxia-induced injury by up-regulation of microRNA-21.

The in vivo protective role of gastrodin (GSTD) in myocardial infarction (MI) has been reported. However, the underlying mechanism remains unclear. Herein, we aimed to explore the effects of GSTD on hypoxia-injured H9c2 cells as well as the downstream microRNAs (miRNAs) and signaling cascades. Hypoxic injury model was constructed to mimic MI. Effects of GSTD pretreatment on cell proliferation and apoptosis were measured by CCK-8 assay, Western blot analysis, and flow cytometry/Western blot analysis, respectively. Expression of miR-21 in cells treated with hypoxia or hypoxia plus GSTD was determined by stem-loop RT-PCR. Whether GSTD affected hypoxia-injured cells via miR-21 was subsequently verified. The direct target of miR-21 was studied by bio-informatics ways and luciferase reporter assay. Besides, expression levels of key kinases in the PTEN/PI3K/AKT and NF-κB pathways were testified by Western blot analysis. Hypoxia-induced decrease of cell viability, up-regulation of p53 and p16, increase of apoptotic cells and up-regulation of Bax, cleaved casapse-3 and cleaved caspase-9 were all mitigated by GSTD pretreatment. Expression of miR-21 was up-regulated by hypoxia and was further up-regulated by GSTD treatment. In transfected H9c2 cells, effects of GSTD on hypoxia-treated cells were augmented by miR-21 overexpression while were reversed by miR-21 inhibition. PDCD4 was confirmed as a direct target of miR-21, and reversed the effect of miR-21 on hypoxia-injured cells. Finally, GSTD down-regulated PTEN expression and enhanced phosphorylation levels of PI3K, AKT, p65 and IκBα via up-regulating miR-21. GSTD attenuated hypoxic injury of H9c2 cells through activating PTEN/PI3K/AKT and NF-κB pathways via up-regulating miR-21.