Long-term hypoxia exposure enhanced IGFBP-3 protein synthesis and secretion resulting in cell apoptosis in H9c2 myocardial cells.

Myocardial infarction (MI) usually results in myocardial ischemia, remodeling and hypoxia that lead to cell death. To date, the insulin-like growth factor binding protein-3 (IGFBP3) is known to play an important role in insulin growth factor (IGF) bioavailability. Previous studies have found that hypoxia results in cell apoptosis. However, the detailed mechanism and roles of IGFBP3 in long-term hypoxia (LTH) regulated heart cell apoptosis remains unknown. In this study H9c2 cardiomyoblast cells were treated with investigated long-term hypoxic exposure with the possible mechanisms involved. The results showed that LTH enhanced IGFBP3 protein synthesis and induced its secretion. The accumulated IGFBP3 sequestered Insulin growth factor 1 (IGF-1) away from the type I IGF receptor (IGF-1 R), which blocked the IGF1R/PI3K/Akt survival signaling pathway, resulting in cell apoptosis. According to our findings, IGFBP3 could be a valuable target for developing treatments for cardiac diseases in long-term hypoxia exposure patients.