Dihydromyricetin Alleviates H9C2 Cell Apoptosis and Autophagy by Regulating CircHIPK3 Expression and PI3K/AKT/mTOR Pathway

Objective: To investigate the effect and potential mechanism of dihydromyricetin (Dmy) on H9C2 cell proliferation, apoptosis, and autophagy. Methods: H9C2 cells were randomly divided into 7 groups, namely control, model, EV (empty pCDH-CMV-MCS-EF1-CopGFP-T2A-Puro vector), IV (circHIPK3 interference), Dmy (50 mu mol/L), Dmy+IV, and Dmy+EV groups. Cell proliferation and apoptosis were detected by cell counting kit-8 assay and flow cytometry, respectivley. Western blot was used to evaluate the levels of light chain 3 II/I (LC3II/I), phospho-phosphoinositide 3-kinase (p-PI3K), protein kinase B (p-AKT), and phospho-mammalian target of rapamycin (p-mTOR). The level of circHIPK3 was determined using reverse transcriptase polymerase chain reaction. Electron microscopy was used to observe autophagosomes in H9C2 cells. Results: Compared to H9C2 cells, the expression of circHIPK in H9C2 hypoxia model cells increased significantly (P < 0.05). Compared to the control group, the cell apoptosis and autophagosomes increased, cell proliferation rate decreased significantly, and the expression of LC3 II/I significantly increased (all P < 0.05). Compared to the model group, the rate of apoptosis and autophagosomes in IV, Dmy, and Dmy+IV group decreased, the cell proliferation rate increased, and the expression of LC3 II/I decreased significantly (all P < 0.05). Compared to the control group, the expressions of p-PI3K, p-AKT, and p-mTOR in the model group significantly reduced (P < 0.05), whereas after treatment with Dmy and sh-circHIPK3, the above situation was reversed (P < 0.05). Conclusion: Dmy plays a protective role in H9C2 cells by inhibiting circHIPK expression and cell apoptosis and autophagy, and the mechanism may be related to PI3K/AKT/mTOR pathway.