低剂量LPS激活NF-κB促进胰岛β细胞株NIT-1增殖

Low dose LPS enhances proliferation of a mouse insulinoma cell line NIT-1

目的探讨脂多糖(lipopolysaccharide,LPS)对小鼠胰岛β细胞增殖的影响及NF-κB信号途径的调节作用。方法不同剂量LPS按不同时间刺激小鼠胰岛β细胞株NIT-1细胞,并使用NF-κB特异性抑制剂Bay11-7082(5μmol·L-1)进行干预。使用cell counting kit-8(CCK-8)试剂检测细胞增殖,Western blot检测NIT-1细胞磷酸化I-κBα(pI-κBα)和总I-κBα蛋白水平。结果LPS在0.1、0.5、1.0、5.0mg·L-1刺激72h对NIT-1细胞增殖有促进作用,在5.0mg·L-1浓度时促进作用减弱,在10.0mg·L-1浓度时对NIT-1细胞增殖无明显影响;NF-κB特异性抑制剂Bay11-7082可阻断LPS对NIT-1细胞增殖的促进作用;LPS刺激后60～120min,NIT-1细胞磷酸化I-κBα相对于总I-κBα蛋白水平增高;Bay11-7082阻断LPS诱导的NIT-1细胞I-κBα蛋白磷酸化。结论低剂量LPS促进NIT-1细胞增殖,NF-κB激活可能参与其过程。

Aim To investigate the effect of LPS on proliferation of pancreatic islet cells in a mouse insulinoma cell line NIT-1 and the role of nuclear factor-B （NF-κB） in the process.Methods NIT-1 cells were cultured and challenged with LPS at different concentrations and for different time courses. A specific NF-κB inhibitor,Bay11-7082,was used either alone or as a pretreatment followed by LPS being added to the medium to test the involvement of NF-κB in LPS-induced cell growth.Cell proliferation was evaluated through cell counting kit-8 reagents.The protein levels of I-κB and phosphorylated I-κB （pI-κB） were detected by Western blot by specific antibodies.Results LPS dose-dependently enhanced NIT-1 cell proliferation at the concentrations from 0.1 to 1.0 mg·L-1 after treatment for 72 hours.The effect was also observed at the does of 5.0 mg·L-1 but became less remarkable. No significant difference was observed when LPS was applied at the does of 10.0 mg·L-1.LPS-induced increase in NIT-1 cell growth was blocked by pretreatment with Bay11-7082.Correspondingly,the protein level of pI-κB relative to total I-κB was significantly increased in NIT-1 cells challenged with LPS for 60 and 120 minutes.LPS-induced phosphorylation of I-κB was remarkably blunted by Bay11-7082.Conclusions Low does LPS can enhance proliferation of NIT-1 cells,in which NF-κB may be involved.