Abstract: Objective　To explore the expressions and roles of interleukin (IL)-6 and transcription factor GATA6 in the proliferation of rat pulmonary artery smooth muscle cells (PASMCs) induced by platelet-derived growth factor-BB (PDGF-BB). Methods　Pulmonary arteries were isolated from 8-week-old SD rats, and PASMCs were cultured by type Ⅰ collagenase digestion method. The cells were observed by inverted microscope and identified by immunofluorescence staining. The effects of different concentrations of PDGF-BB (0, 15, 30, 45, 60 and 75 μg/L) on the proliferation of PASMCs at 12 h, 24 h and 48 h were detected by CCK-8. Flow cytometry was used to detect the cell cycle of 30 μg/L PDGF-BB induced cell proliferation for 48 h. The qPCR and Western blot assay were used to detect the expression levels of IL-6 mRNA and GATA6 mRNA and protein after 30 μg/L PDGF-BB induced cell proliferation for 12 h, 24 h and 48 h. Results　The proliferation model of PASMCs could be effectively established by PDGF-BB. The proliferation of PASMCs was significantly increased by PDGF-BB at 15-60 μg/L for 24 h and 48 h, and the best effect was induced by 30 μg/L for 48 h (P＜0.05). Flow cytometry results showed that the percentage of G1 phase was significantly lower in PDGF-BB group than that of control group, while the percentages of S phase and G2 phase were significantly increased (P＜0.01). PDGF-BB can induce cells to increase IL-6 mRNA and protein secretion and reduce GATA6 mRNA and protein expression levels. Correlation analysis showed that the proliferation of PASMCs was positively correlated with the expressions of IL-6 mRNA and negatively correlated with the expression of GATA6 mRNA (r=0.538, -0.647 respectively, P＜0.05). The expression of IL-6 mRNA was negatively correlated with the expression of GATA6 mRNA (r=-0.705, P＜0.01). Conclusion　PDGF-BB induces proliferation of PASMCs cultured in vitro. IL-6 and GATA6 are involved in the occurrence and development of PDGF-induced PASMCs proliferation. PASMC proliferation is associated with up-regulation of IL-6 mRNA and down-regulation of GATA6 mRNA.

Key words: platelet-derived growth factor, interleukin-6, GATA6 transcription factor, myocytes, smooth muscle, cell proliferation