title: Cyclooxygenase-2 gene induction causes CDDP resistance in colon cancer cell line, HCT-15.
abstract: Drug resistance to cisplatin (CDDP) would represent a major obstacle for cancer therapy. The adenosine triphosphate (ATP) binding cassette (ABC) family of transport proteins, such as the 170 kDa P-glycoprotein (multidrug resistance gene-1; MDR-1) and the 190 kDa multidrug resistance-associated proteins (MRPs), are associated with multidrug resistance, including resistance to CDDP. The purpose of the present study was to investigate the relationship between cyclooxygenase-2 (COX-2) expression and the level of chemosensitivity to CDDP. We established the COX-2-overexpressed colon cancer cell line TR-5 from HCT-15 cells. We quantified the expression of m-RNA for MRP-1 and MDR-1 by a real-time PCR method, determining that the values of each gene/standardized GAPDH in HCT-15 and TR-5 were 23+/-0.4 and 6.1+/-0.5 in MRP-1 (p<0.02) and 9.0+/-4.8 and 3.6+/-0.5 in MDR-1, respectively. With respect to chemosensitivity, survival rates for 3 microg/ml and 10 microg/ml of CDDP were 81.5+/-12.2% and 26.1+/-11.7% (IC50=6.5 microg/ml) for HCT-15 and 96.6+/-1.7% and 77.4+/-4.9% (IC50=18.5 microg/ml) for TR-5, respectively, thus TR-5 showed higher resistance to CDDP than HCT-15 did with statistical differences. We also demonstrated a successful re-sensitization to CDDP toxicity in TR-5 by means of the COX-2 selective inhibitor JTE-522, 4-(4-cyclohexyl-2-methyl-1, 3-oxazol-5-yl)-2-fluorobenzene sulfonamide, which markedly decreased the IC50 of CDDP for TR-5 (from 17.3+/-2.6 microg/ml to 8.6+/-2.5 microg/ml). In conclusion, COX-2 overexpression induced increased MRP-1 expression in a colon cancer cell line, TR-5, resulting in chemoresistance to CDDP that was approximately triple the level of chemoresistance observed in the original HCT-15 cells line, as measured by calculation of the IC50. We also confirmed the efficacy of pretreatment of TR-5 cells with the COX-2 selective inhibitor JTE-522 in restoring chemosensitivity of these cells to CDDP, suggesting a strategy for overcoming drug resistance to CDDP.
authors.affiliation: Department of Surgery, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan. saiky@sc.itc.keio.ac.jp
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Saikawa
authors.forename: Tsudoi
authors.initials: T
authors.lastname: Sugiura
authors.forename: Fumiki
authors.initials: F
authors.lastname: Toriumi
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Kubota
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Suganuma
authors.forename: Soichiro
authors.initials: S
authors.lastname: Isshiki
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Otani
authors.forename: Koichiro
authors.initials: K
authors.lastname: Kumai
authors.forename: Masaki
authors.initials: M
authors.lastname: Kitajima
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology; D001557:Benzenesulfonates / Q000494:pharmacology; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000235:genetics; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D008565:Membrane Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis / Q000235:genetics; D010080:Oxazoles / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015533:Transcriptional Activation; D000096926:Benzenesulfonamides
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D001557:Benzenesulfonates; D002945:Cisplatin; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010080:Oxazoles; D011451:Prostaglandin-Endoperoxide Synthases; D012333:RNA, Messenger; C110453:4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzenesulfonamide; D000096926:Benzenesulfonamides; C496540:PTGS2 protein, human; C421109:multidrug resistance-associated protein 1