Effects of ciglitazone and troglitazone on the proliferation of human stomach cancer cells.
OBJECTIVE
To determine the cytological and molecular effects of peroxisome proliferation-activated receptor (PPAR)-gamma and PPAR-gamma 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 micromol/L troglitazone and ciglitazone at a density of 1 multiply 10(4) cells/well. After 3, 5 and 7 d, the cells were counted with a hemocytometer. To assess the appearance of PPAR-gamma, 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-gamma 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-gamma, 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 cell cycle, nuclear metabolism, and phosphorylation.


CONCLUSIONS
Troglitazone and ciglitazone suppress the proliferation of stomach cancer cells via a PPAR-gamma-independent pathway.
Cheon
Chan Woo
CW
Department of Surgery, Medical Research Institute, Pusan National University, Busan, South Korea.
Kim
Dae Hwan
DH
Kim
Dong Heon
DH
Cho
Yong Hoon
YH
Kim
Jae Hun
JH
D002453:Cell Cycle / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D048430:Cell Shape; D002839:Chromans / Q000494:pharmacology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases; D020869:Gene Expression Profiling; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis; D047495:PPAR gamma / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology*; D045162:Thiazolidinediones / Q000494:pharmacology*; D000077288:Troglitazone
D002839:Chromans; D050759:Cyclin-Dependent Kinase Inhibitor p21; D007004:Hypoglycemic Agents; D047495:PPAR gamma; D045162:Thiazolidinediones; D048049:Extracellular Signal-Regulated MAP Kinases; D000077288:Troglitazone; C039671:ciglitazone