ABSTRACT
Objective To investigate the effects of liver X receptor (LXR) agonist on the proliferation of mouse pancreatic β cell line MIN6 cells.Methods The viability,changes of cell cycle,mRNA levels of S phase kinase associated protein 2 (Skp2) and p27,and protein levels of Skp2 and p27 in MIN6 cells treated with LXR agonist T0901317 were determined by the CCK-8 method,flow cytometry,real-time RT-PCR and western blot,respectively.Results The viability of MIN6 cells treated with 1 μmol/L,5 μmol/L and 10 μnol/L of T0901317 were (98.54 ±0.94)％,(87.03 ±0.93)％ and (75.57 ± 1.85)％ of the controls,respectively,and there was significant difference among them (F =301.90,P ＜ 0.01).The percentages of G1 phase cells in the MIN6 cells treated with 0 μmol/L,1 μmol/L,5 μmol/L and 10 μmol/L of T0901317 were (35.93 ±2.25)％,(38.45 ±0.91)％,(45.46±1.34)％ and (53.28 ± 1.14) ％,respectively,and there was significant difference among them (F =80.83,P ＜ 0.01).Similarly,the percentages of S phase cells in the MIN6 cells treated with 0 μmol/L,1 μmol/L,5 μmol/L and 10 μmoi/L of T0901317 were (52.87 ± 1.19) ％,(48.65 ± 0.85) ％,(36.31 ± 1.37) ％ and (31.45 ± 1.22) ％,respectively,and there was also significant difference among them (F =221.30,P ＜ 0.01).The protein levels of p27 in the MIN6 cells treated with 10 μmol/L of T0901317 (2.84 ± 0.14) were significantly higher than that in the controls (2.28 ± 0.10) (t =4.54,P ＜ 0.05),while there was no significant difference in the mRNA levels of p27 between them (t =0.28,P ＞ 0.05).However,10 μmol/L of T0901317 significantly decreased mRNA (0.52 ± 0.02,t =29.22,P ＜ 0.01) and protein levels (0.98 ± 0.12 vs 1.89 ± 0.01,t =10.98,P ＜ 0.01) of Skp2 in MIN6 cells.Based on the control siRNA transfection group as a reference (100％),the cell survival rates of the p27 siRNA transfection group,10 μmol/L of T0901317 treatment group and the intervention group (p27 siRNA transfection + T0901317 treatment) were (100.97 ± 1.08) ％,(75.03 ± 1.83) ％ and (86.67 ± 2.45) ％,respectively.There was no significant difference between the control siRNA and p27 siR-NA transfection groups (t =1.542,P ＞ 0.05).Compared with the control siRNA transfection group,the cell survival rates of the T0901317 treatment group decreased (t =23.58,P ＜ 0.01).There was also significant difference in the cell survival rates between the T0901317 treatment group and the intervention group (t =7.77,P ＜ 0.01).Conclusion The activation of LXR may induce pancreatic β cell cycle arrest by up-regulating the expression of p27 and down-regulating the expression of Skp2.