title: Lipopolysaccharide-enhanced early proliferation of insulin secreting NIT-1 cell is associated with nuclear factor-kappaB- mediated inhibition of caspase 3 cleavage.
abstract: BACKGROUND
  Increased levels of plasma lipopolysaccharide (LPS) have been found in obesity and diabetes patients. This study was to investigate the effect of LPS on pancreatic beta-cell viability and the involvement of caspase 3 in NIT-1 cell line.
  
  
  METHODS
  Mouse insulinoma NIT-1 cells were treated with LPS for the indicated time and dose. Cell viability was measured by cell counting kit-8 reagent. Toll-like receptor 4 (TLR4), caspase 3 and cleaved caspase 3 were detected by Western blotting. Insulin was determined by radioimmunoassay (RIA).
  
  
  RESULTS
  LPS promoted NIT-1 cell proliferation at 1 µg/ml, peaked at 72 hours of incubation. A reduction in cleavage of caspase 3 was observed upon LPS treatment. Bay11-7082, a specific inhibitor of nuclear factor (NF)-κB, blunted LPS-induced inhibition of caspase 3 cleavage. Reduction in chronic insulin secretion was observed after treatment with LPS at 1 µg/ml for 48 and 72 hours, not for 24 hours. TLR4 protein was upregulated when NIT-1 cells were treated with LPS at 1 µg/ml for 24 hours.
  
  
  CONCLUSIONS
  LPS promotes early NIT-1 cell proliferation in association with NF-κB-mediated inhibition of caspase 3 cleavage. LPS exerts a time-dependent inhibitory effect on chronic insulin secretion from NIT-1 cells.
authors.affiliation: Research Center of Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510120, China.
authors.forename: Shan-Ying
authors.initials: SY
authors.lastname: Liu
authors.forename: Qi-Jun
authors.initials: QJ
authors.lastname: Liang
authors.forename: Tian-Xin
authors.initials: TX
authors.lastname: Lin
authors.forename: Xin-Lan
authors.initials: XL
authors.lastname: Fan
authors.forename: Ying
authors.initials: Y
authors.lastname: Liang
authors.forename: Uwe
authors.initials: U
authors.lastname: Heemann
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D053148:Caspase 3 / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000378:metabolism
chemical_list: D007328:Insulin; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D053148:Caspase 3