Involvement of TRPC1 and Cyclin D1 in Human Pulmonary Artery Smooth Muscle Cells Proliferation Induced by Cigarette Smoke Extract.

Cigarette smoking contributes to the development of pulmonary artery hypertension (PAH). As the basic pathological change of PAH, pulmonary vascular remodeling is considered to be related to the abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs). However, the molecular mechanism underlying this process remains not exactly clear. The aim of this research was to study the molecular mechanism of PASMCs proliferation induced by smoking. Human PASMCs (HPASMCs) were divided into 6 groups: 0% (control group), cigarette smoking extract (CSE)-treated groups at concentrations of 0.5%, 1%, 2%, 5%, 10% CSE respectively. HPASMCs proliferation was observed after 24 h. HPASMCs were divided into two groups: 0 (control group), 0.5% CSE group. The mRNA and protein expression levels of transient receptor potential channel 1 (TRPC1) and cyclin D1 in HPASMCs after CSE treatment were respectively detected by RT-PCR and Western blotting. The intracellular calcium ion concentration was measured by the calcium probe in each group. In the negative control group and TRPC1-siRNA transfection group, the proliferation of HPASMCs and the expression of cyclin D1 mRNA and protein were detected. Data were compared with one-way ANOVA (for multiple-group comparison) and independent t-test (for two-group comparison) followed by the least significant difference (LSD) test with the computer software SPSS 17.0. It was found that 0.5% and 1% CSE could promote the proliferation of HPASMCs (P<0.05), and the former was more effective than the latter (P<0.05), while 3% and above CSE had inhibitory effect on HPASMCs (P<0.05). The mRNA and protein expression levels of TRPC1 and cyclin D1 in 0.5% and 1% CSE groups were significantly higher than those in the control group (P<0.05), while those in 3% CSE group were significantly decreased (P<0.05). Moreover, the proliferation of HPASMCs and the expression of cyclin D1 mRNA and protein in TRPC1-siRNA transfection group were significantly reduced as compared with those in the negative control group (P<0.05). It was concluded that low concentration of CSE can promote the proliferation of HPASMCs, while high concentrations of CSE inhibit HPASMCs proliferation. These findings suggested that CSE induced proliferation of HPASMCs at least in part via TRPC1-mediated cyclin D1 expression.