Puerarin attenuates the daunorubicin-induced apoptosis of H9c2 cells by activating the PI3K/Akt signaling pathway via the inhibition of Ca2+ influx.

Puerarin extracted from Radix Puerariae is well known for its pharmacological effects, including antioxidant, anti‑inflammatory, neuroprotective and cardioprotective properties. In this study, we aimed to investigate the effects of puerarin on the daunorubicin (DNR)-induced apoptosis of H9c2 cells and to elucidate the potential mechanisms involved. MTT assay and flow cytometry were performed to evaluate cell cytotoxicity and apoptosis, respectively. Western blot analysis was used to assess changes in the expression levels of proteins, including caspase-3, Akt and phosphorylated Akt (p-Akt). Ratiometric imaging of intracellular calcium (Ca2+) using cells loaded with Fura-2 was also carried out. Our results revealed that puerarin pre-treatment protected the H9c2 cells against DNR-induced cytotoxicity by inhibiting cell apoptosis, which was also confirmed by the decrease in the expression of cleaved caspase-3. Additionally, p-Akt activation was associated with the suppressive effects of puerarin. Following pre-treatment with puerarin, the extracellular Ca2+ influx was restrained and this resulted in a reduction in the intracellular Ca2+ levels; these effects were abrogated by LY294002 [an inhibitor of phosphatidylinositol 3-kinase (PI3K)]. The inhibition of Ca2+ influx suggested that the PI3K/Akt signaling pathway participated in the suppressive effects of puerarin against H9c2 cell apoptosis. Taken togher, our findings demonstrate that puerarin attenuates the DNR-induced apoptosis of H9c2 cells by activating the PI3K/Akt signaling pathway via the inhibition of Ca2+ influx, suggesting that puerarin may be a potential cardioprotective agent for use in the clinical treatment of cardiomyopathy triggered by DNR.