Inhibition of myeloid cell leukemia-1 by tolfenamic acid induces apoptosis in mucoepidermoid carcinoma

Abstract

Objectives: The aim of this study was to evaluate the role of tolfenamic acid (Tol) and ampiroxicam (Amp) in the apoptotic regulation of YD-15 salivary mucoepidermoid carcinoma (MEC). Materials and methods: The effect of Tol on apoptosis and its mechanism were examined using a 3-(4,5-dimethylthiazol-2-yl)-5-(2,4-disulfophenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, Sub-G(1) population, Western blot analysis, 4'-6-Diamidino-2-phenylindole staining, reverse transcriptase polymerase chain reaction, immunostaining and small interfering RNA transfection. Results: Tol inhibited cell growth of YD-15 cells but Amp did not. Tol induces apoptosis in YD-15 cells as evidenced by nuclear fragmentation, accumulation of the sub-G1 phase and the activation of caspase 3. Tol inhibited myeloid cell leukemia-1 (MCL-1) at the protein and mRNA levels. The treatment of MCL-1 siRNA to YD-15 cells resulted in the activation of caspase 3 and the inhibition of cell growth. Moreover, MCL-1 was regulated by specificity protein 1, but not by mitogen-activated protein kinases. Conclusion: These results suggest that Tol could be a potent anti-cancer drug for YD-15 MEC cells that acts by regulating the MCL-1 protein.