Interaction of protein kinase C-extracellular signal-regulated kinase 1/2 signal pathway in the process of plasminogen activator inhibitor-1 expression induced by nicotine in human umbilical vein endothelial cells

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To explore the role of protein kinase C (PKC)- extracellular signal-regulated kinase (ERK)1/2 signal pathway in the process of plasminogen activator inhibitor-1 (PAI-1) protein and mRNA expression in cultured human umbilical vein endothelial cells (HUVECs) induced by nicotine. HUVECs were cultured to examine the effect of nicotine on the expression of secreting PAI-1 in HUVECs on different experimental conditions. The expression of PAI-1 protein was measured by ELISA. PKC inhibitor staurosporine (STS) and ERK1/2 inhibitor PD98059 were used to detect PKC or ERK1/2 function on the expression of PAI-1 in HUVECs induced by nicotine. The PAI-1 mRNA expression was determined by RT-PCR. The expression level of PAI-1 protein in 100 µmol/L nicotine treated group [(22.6 ± 1.1) µg/L] increased significantly compared to the control group [(14.2 ± 2.8) µg/L; q = 5.64, P < 0.05]. After stimulation with 100 µmol/L nicotine for 0, 4, 6, 8, 12 and 24 h, the levels of PAI-1 protein increased over time and reached the peak at 12 h (F = 32.063, P < 0.05). The PAI-1 mRNA and protein expression in nicotine treated group [(1.32 ± 0.20), (21.08 ± 0.83) µg/L] increased significantly compared to the control group [(0.73 ± 0.10), (13.39 ± 0.93) µg/L; q = 8.43, 11.97, all P < 0.05].Compared with nicotine treated group, the PAI-1 mRNA and protein expression in nicotine and STS treated group [(1.07 ± 0.10), (16.19 ± 2.15) µg/L] decreased significantly(q = 5.61, 7.61, all P < 0.05), but still higher than the control group (q = 7.84, 4.36, all P < 0.05). In nicotine and PD98059 treated group, the PAI-1 mRNA and protein expression [(1.12 ± 0.11), (17.52 ± 1.72) µg/L] decreased significantly compared to the nicotine treated group(q = 4.68, 5.54, all P < 0.05), still higher than the control group (q = 8.77, 6.43, all P < 0.05). PKC-ERK1/2 signal pathway may play a partial role in the up-regulation of PAI-1 induced by nicotine in HUVECs.