Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized by enhanced proliferation of pulmonary artery smooth muscle cells (PASMCs) and suppressed apoptosis. Platelet-derived growth factor (PDGF) is a potent mitogen involved in cell proliferation and migration. PDGF-BB induces the proliferation and migration of PASMCs and has been proposed to be a key mediator in the progression of PAH. Previous studies have shown that PDGF and its receptor are substantially elevated in lung tissues and PASMCs isolated from patients and animals with PAH, but the underlying mechanisms are still poorly manifested. MAP kinases, including extracellular signal-regulated kinase1/2 (ERK1/2), c-Jun NH2-terminal kinase1/2 (JNK1/2), and p38 are the key intracellular signals for stimuli-induced cell proliferation, survival, and apoptosis. Therefore, the purpose of this study is to determine whether PDGF-BB on cell proliferation process is mediated through the MAP kinases pathway in human PASMCs (HPASMCs). Our results showed PDGF-BB-induced proliferating cell nuclear antigen (PCNA), Cyclin A and Cyclin E expression in a concentration-dependent manner. The expression levels of phosphorylated JNK (p-JNK) was upregulated with 20 ng/ml PDGF-BB treatment, while PDGF-BB could not increase phosphorylated ERK1/2 (p-ERK1/2) and p-38 (p-p38) expression. The effects of PDGF-BB on cell proliferation and survival were weakened after the administration of antagonist of the JNK pathway or si-JNK. In addition, PDGF-BB protected against the loss of mitochondrial membrane potentials evoked by serum deprivation (SD) in a JNK-dependent manner. These results suggest that PDGF-BB promotes HPASMCs proliferation and survival, which is likely to be mediated via the JNK pathway.
Keywords: JNK; PDGF-BB; proliferation; pulmonary arterial hypertension.