Saikawa Yoshiro, Sugiura Tsudoi, Toriumi Fumiki, Kubota Tetsuro, Suganuma Kazuhiro, Isshiki Soichiro, Otani Yoshihide, Kumai Koichiro, Kitajima Masaki
Department of Surgery, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan.
Anticancer Res. 2004 Sep-Oct;24(5A):2723-8.
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.
顺铂（CDDP）耐药是癌症治疗的主要障碍。三磷酸腺苷（ATP）结合盒（ABC）转运蛋白家族，如170 kDa的P-糖蛋白（多药耐药基因-1；MDR-1）和190 kDa的多药耐药相关蛋白（MRP），与多药耐药有关，包括对CDDP的耐药。本研究的目的是探讨环氧合酶-2（COX-2）表达与对CDDP的化疗敏感性水平之间的关系。我们从HCT-15细胞建立了COX-2过表达的结肠癌细胞系TR-5。我们通过实时PCR方法定量MRP-1和MDR-1的m-RNA表达，确定HCT-15和TR-5中每个基因/标准化甘油醛-3-磷酸脱氢酶（GAPDH）的值在MRP-1中分别为23±0.4和6.1±0.5（p<0.02），在MDR-1中分别为9.0±4.8和3.6±0.5。关于化疗敏感性，3μg/ml和10μg/ml CDDP对HCT-15的存活率分别为81.5±12.2%和26.1±11.7%（半数抑制浓度[IC50]=6.5μg/ml），对TR-5的存活率分别为96.6±1.7%和77.4±4.9%（IC50=18.5μg/ml），因此TR-5对CDDP的耐药性高于HCT-15，具有统计学差异。我们还证明，通过COX-2选择性抑制剂JTE-522（4-(4-环己基-2-甲基-1,3-恶唑-5-基)-2-氟苯磺酰胺）可使TR-5对CDDP毒性成功恢复敏感，该抑制剂显著降低了TR-5对CDDP的IC50（从17.3±2.6μg/ml降至8.6±2.5μg/ml）。总之，COX-2过表达诱导结肠癌细胞系TR-5中MRP-1表达增加，导致对CDDP的化疗耐药性增加，通过计算IC50测量，其化疗耐药水平约为原始HCT-15细胞系中观察到的三倍。我们还证实了用COX-2选择性抑制剂JTE-522预处理TR-5细胞可恢复这些细胞对CDDP的化疗敏感性，提示了一种克服对CDDP耐药的策略。
