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,P0.05).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,P0.05),(1.13±0.19 vs 1.61±0.22,P0.05),(1.25±0.23 vs1.71±0.25,P0.05).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,P0.05).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,P0.05)and the expression of STAT3 phosphorylation(1.83±0.23 vs 1.58±0.22,P0.05).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,P0.05).No difference of the expression of the above factors was observed in SOND(0.151±0.010 vs 0.154±0.011,P0.05)and DMSO(0.141±0.017 vs 0.155±0.010,P0.05)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.