title: Selective cyclooxygenase inhibitors increase paclitaxel sensitivity in taxane-resistant ovarian cancer by suppressing P-glycoprotein expression.
abstract: OBJECTIVE
  The purpose of this study was to investigate whether selective cyclooxygenase (COX) inhibitors promote paclitaxel-induced apoptosis in taxane-resistant ovarian cancer cells by suppressing MDR1/P-glycoprotein (P-gp) expression.
  
  
  METHODS
  Taxane-resistant ovarian cancer cells were cultured with paclitaxel alone or combined with a selective COX inhibitors. The expression patterns of MDR1/P-gp and the ability of COX inhibitors to inhibit growth of taxane-resistant ovarian cancer cells were measured. The efficacy of prostaglandin E2 (PGE2) supplementation was measured to evaluate the mechanisms involved in suppressing MDR1 gene expression.
  
  
  RESULTS
  P-gp was upregulated in taxane-resistant ovarian cancer cells compared to paired paclitaxel-sensitive ovarian cancer cells. An 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that selective COX inhibitors significantly enhanced the cytotoxic effects of paclitaxel in taxane-resistant ovarian cancer cells via a prostaglandin-independent mechanism. These increased apoptotic effects were further verified by measuring an increased percentage of cells in sub-G1 stage using flow cytometry. Selective COX inhibitors suppressed MDR1 and P-gp expression. Moreover, combined treatment with paclitaxel and selective COX inhibitors increased poly (ADP-ribose) polymerase (PARP) cleavage in taxane-resistant ovarian cancer cells.
  
  
  CONCLUSIONS
  Selective COX inhibitors significantly promote paclitaxel-induced cell death in taxane-resistant ovarian cancer cells in a prostaglandin-independent manner. COX inhibitors could be potent therapeutic tools to promote paclitaxel sensitization of taxane-resistant ovarian cancers by suppressing MDR1/P-gp, which is responsible for the efflux of chemotherapeutic agents.
authors.affiliation: Department of Obstetrics and Gynecology, Ellemedi Women's Hospital, Seoul, Korea.
authors.forename: Jung-Pil
authors.initials: JP
authors.lastname: Lee
authors.forename: Ho-Suap
authors.initials: HS
authors.lastname: Hahn
authors.forename: Soo-Jin
authors.initials: SJ
authors.lastname: Hwang
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Jong-Sup
authors.initials: JS
authors.lastname: Park
authors.forename: In-Ho
authors.initials: IH
authors.lastname: Lee
authors.forename: Tae-Jin
authors.initials: TJ
authors.lastname: Kim
keywords: Chemosensitizer; Cyclooxygenase inhibitor; Ovarian cancer; P-glycoprotein; Paclitaxel