Troglitazone, a Selective Ligand for PPARγ, Induces Cell-cycle Arrest in Human Oral SCC Cells

AIM: We attempted to clarify the role of Peroxisome proliferator-activated receptor gamma (PPARgamma) and its ligand, troglitazone (TRO) on oral squamous cell carcinoma (SCC). MATERIALS AND METHODS: The expression of PPARgamma gene was examined in 47 human oral SCC tissues and two human oral SCC cell lines, CA9-22 and HSC-4. The effects of TRO on the growth and cell-cycle progression of human oral SCC cells were examined. RESULTS: PPARgamma mRNA was detected in 20 of 47 oral SCC tissues and two human oral SCC cells. TRO significantly suppressed the growth of the cells, but did not induce apoptosis. CA9-22 cells treated with TRO showed an increased fraction in the G1 phase and decreased fractions in the S and G2-M phases. CONCLUSION: TRO did not induce apoptosis in oral SCC cells, but did inhibit the growth of the cells by arresting the cell cycle at G1 phase.