Apelin‑13 promotes cell proliferation in the H9c2 cardiomyoblast cell line by triggering extracellular signal‑regulated kinase 1/2 and protein kinase B phosphorylation

Apelin‑13 (APL‑13), a peptide hormone that serves as a ligand for G‑protein coupled receptors, has been demonstrated to be highly expressed in left ventricular hypertrophy rat models. It has been implicated in cardio‑protection under pathological states. The present study aimed to assess the physiological proliferation effect of APL‑13 in cultured H9c2 cardiomyoblast cells, and to elucidate the underlying mechanisms. Cell proliferation was determined by MTT assay. The extracellular signal‑regulated kinase (ERK) 1/2 and protein kinase B (Akt) signaling pathway was identified, and protein expression levels were detected using western blot analysis. The results demonstrated that APL‑13 markedly increased cell proliferation. Western blotting results suggested that APL‑13 significantly enhanced the expression of phosphoinositide ERK1/2 and Akt activation in a dose‑dependent manner. U0126 (10 µM; ERK1/2 inhibitor) and/or 10 µM LY294002 (Akt inhibitor) were used to help to determine the APL‑signaling mechanism. As a result, LY294002 and U0126 partially blocked the APL‑13 induced H9c2 proliferation. In conclusion, these data suggested that APL‑13 has a proliferative effect on myocardium cells via the Akt and ERK1/2 signaling pathways, and provide potential novel pharmaceutical targets for cardiovascular disease.