Temozolomide chemoresistance heterogeneity in melanoma with different treatment regimens: DNA damage accumulation contribution
Temozolomide chemoresistance heterogeneity in melanoma with different treatment regimens: DNA damage accumulation contribution
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DOI：
10.1097/cmr.0b013e328345af95
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发表时间：
2011-06-01
影响因子：
2.2
通讯作者：
Emmert, Steffen
中科院分区：
文献类型：
--
作者：
Boeckmann, Lars;Nickel, Ann-Christin;Emmert, Steffen
替莫唑胺治疗黑色素瘤的疗效较低(有效率为20%)，可能取决于O-6-甲基鸟嘌呤DNA甲基转移酶(MGMT)的活性和错配修复。我们确定了黑色素瘤细胞株对替莫唑胺治疗的单一临床剂量方案和长期临床剂量方案具有不同的敏感性，并使用该模型评估了各种潜在的耐药机制。我们检测了MGMT和基本错配修复基因(MLH1、MSH2)的mRNA表达和启动子甲基化。观察细胞周期分布、细胞凋亡/坏死诱导、O-6-甲基鸟嘌呤加合物形成和ABCB1基因表达。我们发现三种细胞系，Mela，Melb和Melc，对单次给药方案比对长时间给药方案更敏感，后者预计会表现出更高的细胞毒性。KAII和LIBR细胞对延长治疗方案的敏感性更高，正如预期的那样。只有Melc表达MGMT。基因表达与启动子甲基化密切相关。替莫唑胺暴露并未改变mRNA的表达。对替莫唑胺的不同敏感性既不是由于早期细胞周期停滞导致的延迟诱导细胞凋亡，也不是由于O-6-甲基鸟嘌呤加合物的形成或外排转运体的表达。MALC细胞对O-6-甲基鸟嘌呤加合物的清除速度最快，抗性最强。这与它的MGMT表达很好地一致。与其他三种细胞系相比，敏感细胞系KAII和LIBR在替莫唑胺处理第二个周期后积累了O-6-甲基鸟嘌呤加合物。结论：MGMT表达和DNA加合物蓄积是替莫唑胺化疗敏感性的相关因素。无论是通过DNA加合物的定量还是通过药敏试验来考虑个性化的替莫唑胺治疗方案似乎都值得临床应用。黑色素瘤Res 21：206-216(C)2011 Wolters Kluwer Health垂直条Lippincott Williams&Wilkins。
The efficacy of temozolomide in melanoma treatment is low (response rate < 20%) and may depend on the activity of O-6-methylguanine DNA methyltransferase (MGMT) and mismatch repair. We identified melanoma cell lines with different sensitivities to single versus prolonged clinical dosing regimens of temozolomide treatment and assessed a variety of potential resistance mechanisms using this model. We measured mRNA expression and promoter methylation of MGMT and essential mismatch repair genes (MLH1, MSH2). Cell cycle distribution, apoptosis/necrosis induction, O-6-methylguanine-adduct formation, and ABCB1 gene expression were assessed. We found that three cell lines, MelA, MelB, and MelC, were more sensitive to a single dose regimen than to a prolonged regimen, which would be expected to exhibit higher cytotoxicity. KAII and LIBR cell sensitivity was higher with regard to the prolonged treatment regimen, as expected. Only MelC expressed MGMT. Gene expression correlated well with promoter methylation. Temozolomide exposure did not alter mRNA expression. Different sensitivities to temozolomide were caused neither by delayed apoptosis induction due to early cell cycle arrest nor by O-6-methylguanine-adduct formation or efflux transporter expression. MelC was the most resistant cell line with rapid elimination of O-6-methylguanine adducts. This was in good agreement with its MGMT expression. The sensitive cell lines KAII and LIBR accumulated O-6-methylguanine adducts after a second treatment cycle with temozolomide in contrast with the other three cell lines. We conclude that MGMT expression and DNA adduct accumulation are relevant factors in temozolomide chemosensitivity. Considering individualized temozolomide treatment regimens either by quantification of DNA adducts or by chemosensitivity testing seems worthwhile clinically. Melanoma Res 21:206-216 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.