Mizutani Yoichi, Kamoi Kazumi, Ukimura Osamu, Kawauchi Akihiro, Miki Tsuneharu
Department of Urology, Kyoto Prefectural University of Medicine, Japan.
J Urol. 2002 Dec;168(6):2650-4. doi: 10.1016/S0022-5347(05)64237-1.
Cyclooxygenase-2 (COX-2) is a key inducible enzyme involved in the production of prostaglandins that has been shown to induce apoptosis in various cancer cells. Several anticancer agents also mediate apoptosis and may share the common intracellular pathways leading to apoptosis. Since over expression of COX-2 has been demonstrated in bladder cancer, we reasoned that combination treatment with a COX-2 inhibitor and anticancer agents in bladder cancer cells may result in synergistic apoptosis. We examined whether the selective COX-2 inhibitor JTE-522 induces apoptosis in bladder cancer cells and whether JTE-522 may act synergistically with anticancer agents to achieve cytotoxicity and apoptosis in these cells.
Cytotoxicity was determined by microculture tetrazolium dye assay. Synergy was assessed by isobolographic analysis.
COX-2 mRNA expression was observed in the HT1197 bladder cancer cell line. JTE-522 was cytotoxic in HT1197 cells. Treating HT1197 cells with JTE-522 combined with doxorubicin or mitomycin C did not show synergistic cytotoxicity. However, combination treatment of HT1197 cells with JTE-522 and 5-fluorouracil (5-FU) resulted in a synergistic cytotoxic effect. Synergy was also achieved in the T24 bladder cancer line. Synergistic cytotoxicity was noted irrespective of treatment sequence but the highest percent cytotoxicity was obtained when HT1197 cells were treated with JTE-522 and 5-FU simultaneously. The synergy achieved in cytotoxicity with JTE-522 and 5-FU was shown to be due to apoptosis. The mechanisms responsible for synergistic cytotoxicity and apoptosis was examined. Treating HT1197 cells with 5-FU enhanced expression of the pro-apoptotic molecule Bax, while JTE-522 treatment reduced expression of the anti-apoptotic molecule Bcl-XL, resulting in a significantly higher ratio of Bax-to-Bcl-XL.
This study shows that combination treatment of bladder cancer cells with the selective COX-2 inhibitor JTE-522 and 5-FU results in synergistic cytotoxicity and apoptosis due to the enhanced Bax-to-Bcl-XL expression ratio. These findings support the in vivo potential application of a combination of JTE-522 and 5-FU for bladder cancer.
环氧合酶-2（COX-2）是参与前列腺素生成的一种关键诱导酶，已被证明可诱导多种癌细胞凋亡。几种抗癌药物也介导细胞凋亡，可能共享导致细胞凋亡的常见细胞内途径。由于已证实在膀胱癌中存在COX-2的过表达，我们推测在膀胱癌细胞中用COX-2抑制剂和抗癌药物联合治疗可能会导致协同性细胞凋亡。我们研究了选择性COX-2抑制剂JTE-522是否能诱导膀胱癌细胞凋亡，以及JTE-522是否能与抗癌药物协同作用，在这些细胞中实现细胞毒性和细胞凋亡。
通过微量培养四氮唑染料法测定细胞毒性。通过等效线图分析评估协同作用。
在HT1197膀胱癌细胞系中观察到COX-2 mRNA表达。JTE-522对HT1197细胞具有细胞毒性。用JTE-522联合阿霉素或丝裂霉素C处理HT1197细胞未显示协同细胞毒性。然而，用JTE-522和5-氟尿嘧啶（5-FU）联合处理HT1197细胞产生了协同细胞毒性作用。在T24膀胱癌细胞系中也实现了协同作用。无论处理顺序如何，均观察到协同细胞毒性，但当HT1197细胞同时用JTE-522和5-FU处理时，获得的细胞毒性百分比最高。JTE-522和5-FU在细胞毒性方面的协同作用被证明是由于细胞凋亡。研究了协同细胞毒性和细胞凋亡的机制。用5-FU处理HT1197细胞可增强促凋亡分子Bax的表达，而用JTE-522处理可降低抗凋亡分子Bcl-XL的表达，导致Bax与Bcl-XL的比率显著升高。
本研究表明，用选择性COX-2抑制剂JTE-522和5-FU联合治疗膀胱癌细胞可导致协同细胞毒性和细胞凋亡，这是由于Bax与Bcl-XL表达比率的增加。这些发现支持JTE-522和5-FU联合应用于膀胱癌的体内潜在应用。
