Anti-tumor effect of zartoprofen, a non-steroidal anti-inflammatory drug, targeting PPARγ (peroxisome proliferator-activated receptor gamma) on chondrosarcoma.

Abstract

232 Background: Peroxisome proliferator-activated receptor gamma (PPARγ) plays a central role in the differentiation of adipocytes. Anti-tumor effects by activating PPARγ have been reported on chondrosarcoma. We revealed that zaltoprofen, a non-steroidal anti-inflammatory drug (NSAID), could activate and induce PPARγ in chondrosarcoma cells. We report antitumor effects of zaltoprofen targeting PPARγ on chondrosarcoma. Methods: PPARγ activation by zaltoprofen was assessed with luciferase assay. Human chondrosarcoma cells and PPARγ-silencing cells established with shRNA were subjected to the anti-tumor analyses, western blotting, RT-PCR, and zymography. For in vivo study, chondrosarcoma cells were subcutaneously inoculated into nude mice. Zaltoprofen was administered to mice (30 mg/kg/day). Tumors were pathologically assessed. We obtained tumor tissue specimens from a patient who underwent several surgeries for recurrent spinal chondrosarcoma. The patient was administered zaltoprofen as a therapeutic agent for algia the tumor remained stable for more than 2 years. Pathological analyses were performed on the specimen before and after administration of zaltoprofen). Results: Zaltoprofen significantly increased PPARg activation (EC50 47.3 uM). Treatment with 200–400 uM zaltoprofen significantly inhibited cell viability and induced PPARγ protein and mRNA expression in chondrosarcoma cells. Zaltoprofen (400 uM) significantly decreased the cell proliferation, migration, invasion, and MMP2 expression in control cells, whereas these were significantly increased in PPARγ-silencing cells. Also, zaltoprofen (400 uM) induced p21, p27, and p53 expression in control cells, whereas these effects were canceled in PPARg-silencing cells. Upregulation of KROX20 followed by CEBP-α and –β, all of which were reported to induce PPARγ in normal adipose tissue, were detected after zaltoprofen administration. Tumor growth was significantly inhibited in mice administered zaltoprofen. Apoptotic indices in the TUNEL-labeled area were significantly larger and Ki-67 positive cells were significantly lower in tumor specimens from mice administered zaltoprofen. Patient’s specimens revealed that PPARγ expression was stronger and MMP2 expression was weaker in post-administration specimens. Conclusions: Zaltoprofen suppressed tumor progression by inhibiting cell proliferation, migration, and invasion with induction of PPARγ expression in chondrosarcoma cells. The suppressing effect on tumor progression by zaltoprofen was also observed in vivo. Zaltoprofen induced PPARγ expression and MMP2 downregulation in clinical specimens with expected antitumor effects. This is the first study demonstrating that one of the NSAIDs, zaltoprofen, may act as an antitumor agent by targeting PPARγ for chondrosarcoma.