Research Of 1,25-Dihydroxyvitamin D₃ Effects In Rat Mesangial Cell Proliferation And Apoptosis As Well As Related Mechanisms

Objective:To study the effect of 1,25-dihydroxyvitamin D3 on the growth and cell cycle of rat glomerular mesangial cells.Methods:Rat glomerular mesangial cells were separated into four groups, including control group, EGF treatment group,1,25-(OH)2D3 treatment group and EGF combined 1,25-(OH)2D3 treatment group. Cells were treated with lOng/ml EGF and/or 0～10-6mol/L 1,25-(OH)2D3 for 24～72 hour.1. Cells growth and proliferation were measured by MTT assay.2. The cell apoptosis and cell cycles were detected by flow cytometry.3. Morphology and proliferation of mesangial cell were observed dynamically under inverted phase contrast microscope.4. Proliferating cell nuclear antigen (PCNA) protein expression was detected by Western Blot Analysis.Results:1.Growth and proliferation of the mesangial cells were inhibited significantly (P<0.01) and showed dose-dependent 48h after mesangial cell were incubated with 1,25-(OH)2D3(0～10-6mol/L).10-8mol/L 1,25-(OH)2D3 showed time-dependent for 72h.2. After treatment with 0～10-6mol/L 1,25(OH)2D3, mesangial cells presented apoptosis under inverted phase contrast microscope, and significant difference were found in the cell cycle in response to 1,25(OH)2D3 from G1 to S phases and apoptotic peak compare with the control group, the G2/M phases had no significant change(P>0.05).3. The cell population in EGF group were significantly more than other groups (P<0.05); The G0/G1 phase cells in EGF group were significantly decreased, S phase cells increased significantly, G2/M phase cells increased(P<0.05); The conjoined group cell population of EGF and 1,25(OH)2D3 were decreased significantly; From the FCM gram we found that the proliferative phase cells of EGF group increased compared with other groups, while the conjoined group decrease and it was thus clear that second G1 apoptotic peak.4.The Western Blot result showed that the PCNA protein express in EGF group increased while the express in 1,25(OH)2D3 group and conjoined group decreased compared with control group, especially decreased significantly in 1,25(OH)2D3 group, the conjoined group had no significant difference compares with control group.Conclusion:1.0～10-6mol/L 1,25(OH)2D3 inhibited mesangial cell growth, the inhibitory action showed dose and time dependent.2.1,25-(OH)2D3 could inhibit the mesangial cell proliferation induced by EGF, induce apoptosis and it could also decrease the PCNA express induced by EGF.