[STAT signaling pathway mediates high glucose induced cardiac fibroblasts proliferation and collagen deposition in vitro].

Objective: To observe the signal transducers and activator of transcriptions (STATs) protein expression changes and investigate the functional role of STATs pathway in case of high glucose-induced cardiac fibroblasts (CFs) proliferation and collagen deposition in vitro.

Methods: Rat cardiac fibroblasts were isolated from 1- to 3-day-old SD rats, cells from the second to fourth passages were used for the experiment. CFs were cultured in Dulbecco's modified Eagle's medium, supplemented with 5.5 mmol/L glucose (NG), 5.5 mmol/L glucose plus 19.4 mmol/L mannose (OC) or 25 mmol/L glucose (HG) in the presence of absence of STAT1 inhibitor (fludarabine, FLU) and STAT3 inhibitor (S3I-201). After 24 h and 48 h culture in vitro, the proliferation of CFs was measured by 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. After 12 h and 24 h culture in vitro, the production of type I and III collagen was evaluated using real-time quantitative PCR and ELISA. After 0, 30, 60 and 120 min culture in vitro, the phosphorylated expression of STAT1 and STAT3 was analyzed by Western blot.

Results: CFs proliferation was significantly enhanced post 24 h and 48 h HG stimulation, and procollagen I and III mRNA expression was significantly upregulated post 12 h and 24 h HG stimulation. Deposition of collagen I and III was also significantly increased post 24 h and 72 h HG stimulation. STAT1 phosphorylation in CFs was increased after 120 min HG stimulation and STAT3 phosphorylation in CFs was increased post 60 min and 120 min HG stimulation. FLU and S3I-201 could inhibit HG-induced CFs proliferation and suppress of which was stimulated by FLU and S3I-201 could both suppress upregulated procollagen I and III mRNA expression and the deposition of collagen types I and III post HG stimulation. STAT1 phosphorylation inhibition resulted in less mRNA downregulation of procollagen type III than that of procollagen type I post 12 h HG stimulation. The STAT3 phosphorylation inhibition resulted in more significantly upregulated procollagen type III mRNA expression than procollagen type I mRNA expression at 12 h post HG stimulation.

Conclusion: HG could enhance the protein expression of phosphorylated STAT1 and STAT3 in CFs, which are responsible for HG-induced increased CFs proliferation and collagen deposition in vitro.