Suppression of chondrosarcoma cells by 15-deoxy-Δ 12,14-prostaglandin J2 is associated with altered expression of Bax/Bcl-xL and p21

We previously reported that 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), the most potent agonist for peroxisome proliferator-activated receptor gamma (PPARgamma), induces apoptosis of human chondrosarcoma cell line OUMS-27. The current study aimed to explore the mechanism of 15d-PGJ(2)-induced apoptosis and inhibition of cell proliferation in OUMS-27 cells. The preliminary results of cDNA microarray analysis showed the down-regulation of anti-apoptotic Bcl-xL and up-regulation of pro-apoptotic Bax in the process of 15d-PGJ2-induced apoptosis. These changes were further confirmed at mRNA and protein levels by RT-PCR and Western blot analysis, respectively. Among cyclin-dependent kinase inhibitors, p21 was induced and up-regulated by 15d-PGJ2, but p 16 and p27 were not changed, suggesting that the involvement of p21 in inhibition of cell proliferation. Activation of caspase-3 by 15d-PGJ2 was partly, but not completely, blocked by PPARgamma antagonist (GW9662) suggesting the 15d-PGJ2 exerted its effect by PPARgamma-dependent and -independent pathways. Interestingly, immunohistochemical study on human chondrosarcoma samples revealed that Bcl-xL is frequently expressed by tumor cells. The results of the current study suggest that the potential ability of 15d-PGJ2 in regulation of cell cycle and inhibition of Bcl-xL expression might be beneficial in the development of novel pharmacological agents for chondrosarcoma. (C) 2005 Elsevier Inc. All rights reserved.