Cross-resistance in the 2′,2′-difluorodeoxycytidine (gemcitabine)-resistant human ovarian cancer cell line AG6000 to standard and investigational drugs
Cross-resistance in the 2′,2′-difluorodeoxycytidine (gemcitabine)-resistant human ovarian cancer cell line AG6000 to standard and investigational drugs
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DOI：
10.1016/s0959-8049(00)00246-x
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发表时间：
2000-10-01
影响因子：
8.4
通讯作者：
Peters, GJ
中科院分区：
文献类型：
--
作者：
Bergman, AM;Giaccone, G;Peters, GJ
吉西他滨（2'-2'-二氟脱氧胞苷；dFdC）是一种脱氧胞苷类似物，可有效治疗实体肿瘤，包括肺癌和卵巢癌。dFdC需要脱氧胞苷激酶（dCK）磷酸化才能激活。在人卵巢癌细胞系A2780及其3万倍dfdc耐药变异AG6000中（P < 0.001），我们研究了几种药物的交叉耐药谱。AG6000完全缺乏dCK，对其他脱氧核苷类似物，如1- β -d -阿拉伯糖醛基胞嘧啶、2-氯脱氧腺苷、aza脱氧胞苷和2',2'-二氟脱氧鸟苷（dFdG）的耐药性约为1000-10 000倍（P < 0.001）。dFdG可被dCK和脱氧鸟苷激酶（dGK）激活；而后一种酶在AG6000细胞中没有改变。因此，对dFdG的抗性仅仅是由于dCK缺乏。AG6000对5-氟尿嘧啶（5-FU）和ZD1694分别有1.6倍和46.7倍的耐药（后者显著，P < 0.01），这可能是由于其胸腺苷酸合成酶（TS）活性高1.7倍，但AG6000细胞对亲脂性TS抑制剂AG337也有2.7倍的耐药（P < 0.05）。AG6000细胞对甲氨蝶呤（MTX）的敏感性是A2780细胞的2.5倍（P < 0.01），对三甲氨蝶呤（TMQ）的耐药性是A2780细胞的1.6倍（P < 0.10）。然而，在叶酸载体活性降低、叶酸聚谷氨酸合成酶（FPGS）活性和MTX多谷氨酸化方面，不同细胞系间没有发现差异。AG6000细胞对阿霉素（DOX）、柔红霉素（DAU）、表柔比星和长春新碱（VCR）的耐药性约为2 ~ 7.5倍（后者显著，P < 0.02），对微管抑制剂紫杉醇和多西紫杉醇的耐药性约为4倍（P < 0.001）。荧光活化细胞分选仪（FACS）分析显示AG6000细胞无p -糖蛋白（Pgp）或多药耐药相关蛋白（MRP）表达，但嵌入的DAU荧光较少。AG6000细胞对拓扑异构酶I和II抑制剂依托泊苷、CPT-I I和SN38有大约2倍的耐药性。AG6000细胞中拓扑异构酶landⅱα RNA表达降低。AG6000对EO9 （P < 0.02）、丝裂霉素- c (MMC) （P < 0.05）、顺铂（CDDP） （P < 0.10）和mapphosphamide （MAPH）的耐药分别高出2.4、2.4、2.3和3.7倍。激活EO9的DT-diaphorase （DTD）在AG6000细胞中降低了2.2倍。抗CDDP可能与AG6000中DNA加合物的保留减少有关。然而，A2780和AG6000细胞中的谷胱甘肽水平相同。在等摩尔和等量浓度下暴露于DOX、VCR和紫杉醇24小时后，A2780细胞的双链断裂比AG6000细胞多（1.5至2倍）。在EO9的1120 nM和17 nM处，MAPH对两种细胞系均未造成DNA损伤。总之，AG6000是一种对多种药物具有高度交叉耐药的细胞系。这种交叉抗性可能与酶活性的改变有关；或增加DNA修复。(C) 2000 Elsevier Science Ltd.版权所有。
Gemcitabine (2'-2'-difluorodeoxycytidine; dFdC) is a deoxycytidine analogue which is effective against solid tumours, iucluding lung cancer and ovarian cancer. dFdC requires phosphorylation by deoxycytidine kinase (dCK) for activation. In the human ovarian cancer cell line A2780 and its 30 000-fold dFdC-resistant variant AG6000 (P < 0.001), we investigated the cross-resistance profile to several drugs. AG6000, which has a complete dCK deficiency, was approximately 1000-10 000-fold resistant to other deoxynucleoside analogues such as 1-beta-D-arabinofuranosyl cytosine, 2-chloro-deoxyadenosine, aza-deoxycytidine and 2',2'-difluorodeoxyguanosine (dFdG) (P < 0.001). dFdG can be activated by dCK and deoxyguanosine kinase (dGK); but the latter enzyme was not altered in AG6000 cells. Thus dFdG resistance was only due to dCK deficiency. AG6000 was 1.6- and 46.7-fold resistant to 5-fluorouracil (5-FU) and ZD1694, respectively (the latter was significant, P < 0.01), which may be due to the 1.7-fold higher thymidylate synthase (TS) activity, but AG6000 cells were also 2.7-fold resistant to the lipophilic TS inhibitor AG337 (P < 0.05). Remarkably, AG6000 cells were 2.5-fold more sensitive to methotrexate (MTX) (P < 0.01) than A2780 cells, but 1.6-fold more resistant to trimetrexate (TMQ) (P < 0.10). However, no differences in reduced folate carrier activity, folylpolyglutamate synthetase (FPGS) activity and polyglutamation of MTX were found between the cell lines. AG6000 cells were approximately 2 to 7.5-fold more resistant to doxorubicin (DOX), daunorubicin (DAU), epirubicin and vincristine (VCR) (the latter was significant; P < 0.02) and approximately 4-fold more resistant to the microtubule inhibitors paclitaxel and docetaxel (P < 0.001). Fluorescent activated cell sorter (FACS) analysis revealed no P-glycoprotein (Pgp) or multidrug resistance-associated protein (MRP) expression, but less fluorescence of intercalated DAU in AG6000 cells. An approximately 2-fold resistance to the topoisomerase I and II inhibitors etoposide, CPT-I i and SN38 uas found in AG6000 cells. Topoisomerase land II alpha RNA expression was decreased in AG6000 cells. AG6000 was 2.4, 2.4, 2.3 and 3.7-fold more resistant to EO9 (P < 0.02), mitomycin-C (MMC) (p < 0.05), cisplatin (CDDP) (P < 0.10) and maphosphamide (MAPH), respectively. DT-diaphorase (DTD), which activates EO9, was 2.2-fold lower in AG6000 cells. CDDP resistance might be related to a reduced retention of DNA adducts in AG6000. However, glutathione levels were equal in A2780 and AG6000 cells. A 24 h exposure to DOX, VCR and paclitaxel at equimolar and equitoxic concentrations, resulted in more double-strand breaks (1.5- to 2-fold) in A2780 than in AG6000 cells. MAPH at 1120 nM and 17 nM of EO9 did not cause DNA damage in either cell line. In conclusion, AG6000 is a cell line highly cross-resistant to a wide variety of drugs. This cross-resistance might be related to altered enzyme activities and;or increased DNA repair. (C) 2000 Elsevier Science Ltd. All rights reserved.