PPARgamma ligands suppress the feedback loop between E2F2 and cyclin-E1.

PPARgamma is a nuclear hormone receptor that plays a key role in the induction of peroxisome proliferation. A number of studies showed that PPARgamma ligands suppress cell cycle progression; however, the mechanism remains to be determined. Here, we showed that PPARgamma ligand troglitazone inhibited G1/S transition in colon cancer cells, LS174T.

Heat shock protein 90 inhibitor 17-allylamino-17-demethoxygeldanamycin potentiates the radiation response of tumor cells grown as monolayer cultures and spheroids by inducing apoptosis.

Activation of the PI3K-Akt pathway is known to induce tumor radioresistance. In the current study, we examined the ability of 17AAG, which decreases the levels of Hsp90 client proteins including components of the PI3K-Akt pathway, to sensitize radioresistant human squamous cell carcinoma cells to X-irradiation. Human squamous cell carcinoma cell lines (SQ20B, SCC61 and SCC13) were incubated for 16 h at 37 degrees C in medium containing 17AAG.

Preferential sensitization of tumor cells to radiation by heat shock protein 90 inhibitor geldanamycin.

The purpose of this study was to investigate the radiosensitizing effect of geldanamycin (GA), an inhibitor of heat shock protein 90, on tumour cells and normal cells. We tested the effect of a combination of GA and radiation on cell survival, PI3K/Akt-related proteins and apoptosis induction. GA sensitized tumour cells to radiation in preference to normal cells.