Effects of ciglitazone and troglitazone on the proliferation of human stomach cancer cells

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 cell cycle,nuclear metabolism,and phosphorylation.CONCLUSION:Troglitazone and ciglitazone suppress the proliferation of stomach cancer cells via a PPAR-γ-independent pathway.

Enhanced light emission from AlGaN/GaN multiple quantum wells using the localized surface plasmon effect by aluminum nanoring patterns

We investigate the localized surface plasmon(LSP) effect by Al nanorings on the AlGaN/GaN multiple quantum well(MQW) structure emitting at 365 nm. For this experiment, first, the size of Al nanorings is optimized to maximize the energy transfer(or coupling) between the LSP and MQW using the silica nanospheres. Then, the Al nanorings with an outer diameter of 385 nm, which exhibit a strong absorption peak in the near-ultraviolet region, are applied to the top surface of the AlGaN/GaN MQW. The photoluminescence(PL) intensity of the MQW structure with Al nanorings increased by 227% at 365 nm compared to that without Al nanorings.This improvement is mainly attributed to an enhanced radiative recombination rate in the MQWs through the energy-matched LSPs by the temperature-dependent PL and time-resolved PL analyses. The radiative lifetime was about two times shorter than that of the structure without Al nanorings at room temperature. In addition, the measured PL efficiency at room temperature of the structure with Al nanorings was 33%, while that of the structure without Al nanorings was 19%, implying that LSP-QW coupling together with the nanoring array pattern itself played important roles in the enhancement.