An FDA approved drug for the treatment of type II diabetes, Troglitazone (TRO), a peroxisome proliferator–activated receptor gamma agonist, is withdrawn due to severe idiosyncratic hepatotoxicity. In the search for new applications of TRO, we investigated the cellular effects of TRO on YD15 tongue carcinoma cells. TRO suppressed the growth of YD15 cells in the MTT assay. The inhibition of cell growth was accompanied by the induction of cell cycle arrest at G0/G1 and apoptosis, which are confirmed by flow cytometry and western blotting. TRO also suppressed the expression of cell cycle proteins such as cyclin D1, cdk2, cdk4, cyclin B1, cdk1(or cdc2), cyclin E1 and cyclin A. The inhibition of cell cycle proteins was coincident with the up-regulation of p21CIP1/WAF1 and p27KIP1. In addition, TRO induces the activation of caspase-3 and caspase-7, as well as the cleavage of PARP. Further, TRO suppressed the expressions of Bcl-2 without affecting the expressions of Bad and Bax. Overall, our data supports that TRO induces cell cycle arrest and apoptosis on YD15 cells.

Introduction
 Materials and Methods
  Chemicals and antibodies
  Cell culture
  Cell viability assay
  DAPI staining
  Cell cycle analysis by flow cytometry
  Western blot analysis
 Results
  TRO inhibited the cell growth in YD15 cells
  TRO induced G0/G1 phase arrest and apoptosis inYD15 cells
 Discussion
 References

• Ta Thi Loan(Department of Pharmacology and Dental Therapeutics, College of Dentistry, Chosun University, Gwangju 501-759 South Korea)
• Hoon Yoo(Department of Pharmacology and Dental Therapeutics, College of Dentistry, Chosun University, Gwangju 501-759 South Korea) Corresponding Author