Contributions of cardiotrophin-1 to cardiac fibroblast proliferation

AIM: To investigated the role of CT-1 in the hypertensive ventricular remodeling. METHODS: The cardiac fibroblasts in 3-4 passages were cultured in vitro, and divided into eight groups according to the different intervention factors: group C (control); group DM: dimethyl sulphoxide (DMSO); group P: cultured under high hydrostatic pressure (160 mmHg); group ASODN: interfered with CT-1 antisense oligodeoxynucleotides (10 μmol/L); group SODN: incubated with CT-1 sense oligodeoxynucleotides (10 μmol/L); group AG: interfered with AG490 (25 μmol/L); group PD: interfered with PD98059 (20 μmol/L); group LY: interfered with LY 294002 (10 μmol/L). Western blotting was employed to assess the expression of STAT3, ERK1/2 and PI3-K respectively at protein level. Cell proliferation was quantified by MTT. RESULTS: High hydrostatic pressure stimulated the proliferation of cardiac fibroblasts, upregulated the expression of CT-1. CT-1ASODN inhibited the proliferation of cardiac fibroblasts (0.132±0.013 vs 0.154±0.011, P<0.05). ASODN extensively inhibited the expression of STAT3, ERK1/2 and PI3-k respectively at protein level (2.09±0.25 vs 2.47±0.28, P<0.05), (1.13±0.19 vs 1.61±0.22, P<0.05), (1.25±0.23 vs1.71±0.25, P<0.05). AG490, a JAK-STAT3 inhibitor, reversed the increase in the proliferation of cardiac fibroblasts stimulated by high hydrostatic pressure and the expression of ERK1 phosphorylation (0.118±0.018 vs 0.155±0.010, P<0.05). PD98059, a MAPK-ERK1/2 inhibitor, increased the proliferation of cardiac fibroblasts stimulated by high hydrostatic pressure (0.185±0.011 vs 0.155±0.010, P<0.05) and the expression of STAT3 phosphorylation (1.83±0.23 vs 1.58±0.22, P<0.05). LY294002, a PI3-K inhibitor, had no effect on the proliferation of cardiac fibroblasts stimulated by high hydrostatic pressure (0.157±0.015 vs 0.155±0.010, P>0.05). No difference of the expression of the above factors was observed in SOND (0.151±0.010 vs 0.154±0.011, P>0.05) and DMSO (0.141±0.017 vs 0.155±0.010, P>0.05) groups as compared with the control group. CONCLUSION: Under high hydrostatic pressure, the proliferation of cardiac fibroblasts is essentially mediated by STAT3, independent of PI3-K and the action is negatively regulated by ERK1/2 via inhibiting STAT3.The interaction between STAT3 and ERK1/2 may assist CT-1 in developing adequate cardiac fibroblast proliferation.