AIM:To determine the cytological and molecular effects of peroxisome proliferation-activated receptor(PPAR)-γ and PPAR-γ agonists on stomach cancer cells.METHODS:To determine the proliferation-suppressive effects of troglitazone and ciglitazone,SNU-216 and SNU-668 stomach cancer cells were plated in media containing 40 μmol/L troglitazone and ciglitazone at a density of 1 × 104 cells/well.After 3,5 and 7 d,the cells were counted with a hemocytometer.To assess the appearance of PPAR-γ,a reverse-transcription polymerase chain reaction analysis was performed.On day 7,Western blotting was used to determine the effects of troglitazone and ciglitazone on the expression of p21 and phosphorylated-ERK(pERK) genes.Flow cytometry analysis was used to determine which portion of the cell cycle was delayed when troglitazone was used to suppress cell proliferation.In order to clarify the mechanism underlying the activity of troglitazone,microarray analysis was conducted.RESULTS:PPAR-γ was manifested in both SNU-216 and SNU-668 cells.Ciglitazone and troglitazone suppressed cell growth,and troglitazone was a stronger suppressor of stomach cancer cells than ciglitazone,an inducer of cell cycle arrest in the G1 phase.SNU-668 cells were also determined to be more sensitive to ciglitazone and troglitazone than SNU-216 cells.When troglitazone and ciglitazone were administered to stomach cancer cells,levels of p21 expression were increased,but ERK phosphorylation levels were reduced.When GW9662,an antagonist of PPAR-γ,was applied in conjunction with ciglitazone and troglitazone,the cell growth suppression effect was unaffected.The gene transcription program revealed a variety of alterations as the consequence of troglitazone treatment,and multiple troglitazone-associated pathways were detected.The genes whose expression was increased by troglitazone treatment were associated with cell development,differentiation,signal transmission between cells,and cell adhesion,and were also associated with reductions in cell proliferation,the
Chan Woo CheonDae Hwan KimDong Heon KimYong Hoon ChoJae Hun Kim
AIM： To investigate the effect of troglitazone on peroxisome proliferator-activated receptor γ （PPARγ） expression and cellular growth in human colon cancer HCT-116 and HCT-15 cells and to explore the related molecular mechanism.METHODS： Human colon cancer HCT-116 and HCT-15 cells cultured in vitro were treated with troglitazone. Reverse transcription-polymerase chain reaction （RT-PCR） and Western blot were employed to detect the effect of troglitazone on PPARy expression. The proliferative activity was determined by MTT assay, cell cycle and apoptosis were detected by flow cytometry. Apoptosisrelated genes, cell cycle regulatory genes and p53 were examined by RT-PCR and Western blot respectively. RESULTS： The expression of PPARy in colon cancer HCT-116 and HCT-15 cells was up-regulated by troglitazone. Troglitazone inhibited proliferation, induced apoptosis and cell cycle G1 arrest in colon cancer cells. Troglitazone induced p53 expression in HCT-116 cells, but not in HCT-15 cells. The down-regulation of survivin and bcl-2 was found in both cell lines and up-regulation of bax was found only in HCT-116 cells, being consistent with growth inhibition in HCT-116 cells but not in HCT-15 cells. Troglitazone increased expression of p21^WAF1/CIP1 （p21）, p27^KIP1 （p27） and reduced cyclin D1 in HCT-116 cells while only a minor decrease of cyclin D1 was found in HCT-15 cells. CONCLUSION： Troglitazone is an inductor of PPARγ in colon cancer cells and inhibits PPARγ-dependently proliferation, which may attribute to cell cycle G1 arrest and apoptosis in colon cancer cells. Troglitazone may induce p53-independent apoptosis and p53- dependent expression of p21 and p27. Depending on cell background, different activation pathways may exist in colon cancer cells.
Mei MingJie-Ping YuXiang-Zhi MengYan-Hong ZhouHong-Gang YuHe-Sheng kuo
