The potential role of sildenafil in serotonin-induced pulmonary arterial SMCs proliferation is mediated via upregualtion of ERK1/ERK2 phosphorylation / 复旦学报（医学版）

ABSTRACT

Objective To explore the underlying mechanism of potential effect of sildenafil on porcine pulmonary artery smooth muscle cells (SMCs) proliferation induced by serotonin. Methods Porcine pulmonary artery SMCs at 3-5 passages were randomly divided into 4 groups: control group (CON), 5-HT group (HT), sildenafil group (SIL) and sildenfil-5HT combined group (S-HT). Pulmonary artery SMCs at exponential growth phase were serum starved with 0.2% FBS for 72 h, followed by sterile PBS, serotonin (10 μmol/L) and sildenafil (1 μmol/L) incubation in CON group, HT group and SIL group, respectively. In combined group (S-HT): pulmonary artery SMCs were serum starved and then exposed to sildenafil for 20 min, followed by serotonin incubation for indicated time. The phosphorylation of extracellular signal regulated kinase (ERK1/ERK2) was measured by Western blot at indicated time points. Flow active cell sorting (FACS) was used to evaluate the ratio of S phase cells in the cell cycle after 24 h of treatment. MTT color metric method was used to analyze SMCs proliferative index after 72 h of treatment. Results Compared with CON group, the phosphorylation of ERK1/ERK2, the percentage of cells in S phase, and the cell proliferation index increased remarkably after incubation with 5-HT (P<0.05). Preincubation with sildenafil followed by serotonin enhanced the phosphorylation of ERK1/ERK2 (p-ERK1/ERK2) and further elevated the percentage of cells in S phase and the cell proliferation index compared with that of HT group. While the total ERK1/ERK2 (t-ERK1/ERK2) was not statistically different among these groups. Conclusions Sildenafil potentiates the proliferative effect of serotonin on pulmonary arterial SMCs via upregulating phosphorylation of ERK1/ERK2.