Abstract C96: The effect of non-steroidal anti-inflammatory drugs (NSAIDs) in ovarian cancer cells

Abstract

Abstract Epidemiological and laboratory studies have suggested a protective role for non-steroidal anti-inflammatory drugs (NSAIDs) against various neoplasms, including ovarian cancer. In an attempt to clarify the mechanisms and molecular targets of tumor prevention by NSAIDs, we have studied the effects of multiple NSAIDs in several ovarian cancer cell lines. NSAID treatment decreased the viability of all the ovarian cancer cell lines examined. To determine the effect of NSAIDs on the cell cycle, flow cytometry analysis was performed. Cells treated with indomethacin, ibuprofen or celecoxib were arrested in G1 phase, while cells treated with diclofenac underwent an S/G2 arrest. In addition, induction of apoptosis was cell line specific. The levels of several cell cycle regulatory and apoptosis proteins were examined. The levels of phosphorylated Rb protein decreased and phospho-p53 increased upon treatment with NSAIDs, suggesting an involvement of these proteins in the response of ovarian cancer cells to NSAID treatment. In order to further clarify the mechanisms of action of NSAIDs in ovarian cancer cells, gene expression profiling experiments were performed. Ovarian cancer cell lines Hey, OVCAR5, and UCI101 were treated with diclofenac, indomethacin, celecoxib, and ibuprofen, and microarray analysis was performed. A large number of gene expression changes were observed in the different cell lines treated with various NSAIDs. Among the most consistent and reproducible changes observed, S-phase kinase associated protein 2 (Skp2) was found to be downregulated at the mRNA and protein levels in all cell lines with all NSAIDs tested. In addition, Damage inducible transcript-4 (DDIT4) was found to be upregulated in all cell lines upon treatment with diclofenac, indomethacin and celecoxib. Skp2 forms part of the SCF ubiquitin ligase and is involved in the targeting for degradation of several proteins, including the cyclin dependent kinase inhibitors p21 and p27, therefore facilitating S-phase entry. DDIT-4, is transcriptionally activated upon p53 activation and it is known to inhibit mTOR signaling. In conclusion, we have identified a number of target genes that may be important for the NSAID-induced cell cycle arrest and apoptosis and their exact roles are currently being investigated. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C96.