Down-regulation of DNA repair in human CD34+ progenitor cells corresponds to increased drug sensitivity and apoptotic response
Down-regulation of DNA repair in human CD34+ progenitor cells corresponds to increased drug sensitivity and apoptotic response
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DOI：
10.1182/blood-2002-01-0022
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发表时间：
2002-08-01
期刊：
影响因子：
20.3
通讯作者：
Thomale, J
中科院分区：
文献类型：
--
作者：
Buschfort-Papewalis, C;Moritz, T;Thomale, J
虽然DNA修复过程已被证明在很大程度上调节烷化剂的细胞毒性作用，这些机制在化疗诱导的骨髓抑制的作用的信息很少。因此，我们详细分析了原代人造血细胞的DNA修复能力从脐带血（CB）或骨髓（BM）的两个功能测定，免疫细胞学试验（伊卡）和单细胞凝胶电泳（彗星试验）。除了显著的个体间差异外，我们始终观察到，与同一供体的CD 34（-）、CD 19（+）或CD 33（+）细胞相比，CD 34（+）细胞的修复能力显著降低。暴露于烷化剂乙基亚硝基脲（EtNU）后，彗星试验显示，与相应的CD 34（-）细胞相比，CD 34（+）细胞中的DNA单链断裂（SSB）平均为两倍，这些损伤的半衰期为三倍。同样，在应用美法仑或顺铂后，检测到CD 34（+）细胞中SSB修复活性降低。当使用特异性抗体来监测这些药物的DNA反应产物时，加合物水平显著更高，并且损伤在CD 34（+）部分中持续更长时间。为了评估单个途径对整体DNA修复的贡献，将阻断修复过程中定义步骤的调节剂与烷基化药物共同应用。在相应的CD 34（+）和CD 34-细胞组分中类似的“调节模式”表明CD 34（+）细胞的DNA修复能力普遍降低，而不是特定途径的缺陷。由于CD 34（+）细胞在美法仑或顺铂的作用下也表现出更高的凋亡频率，这些发现可能有助于解释暴露于烷化剂后的骨髓抑制。(C)2002年，美国血液学会。
Although DNA repair processes have been shown to considerably modulate the cytotoxic effects of alkylating agents, little information is available on the role of these mechanisms in chemotherapy-induced myelosuppression. Therefore, we have analyzed in detail the DNA repair capacity of primary human hematopoietic cells from cord blood (CB) or bone marrow (BM) by 2 functional assays, the immunocytologic assay (ICA) and single-cell gel electrophoresis (comet assay). Besides substantial interindividual differences, we consistently observed significantly lower repair capacity of CD34(+) cells in comparison to CD34(-), CD19(+), or CD33(+) cells of the same donor. After exposure to the alkylating agent ethyinitrosourea (EtNU), the comet assay displayed on average twice as many DNA single-strand breaks (SSBs) in CD34(+) cells and a tripled half-life of these lesions in comparison to corresponding CD34(-) cells. Similarly, reduced SSB repair activity in CD34(+) cells was detected following melphalan or cisplatin application. When specific antibodies were used to monitor DNA reaction products of these drugs, adduct levels were significantly higher and lesions persisted longer in the CD34(+) fraction. To assess the contribution of individual pathways to overall DNA repair, modulators blocking defined steps in repair processes were coapplied with alkylating drugs. Similar "modulation pattern" in corresponding CD34(+) and CD34-cell fractions indicated a generalized reduction in DNA repair capacity of CD34(+) cells, rather than deficiencies in a specific pathway. Because CD34(+) cells also displayed higher frequencies of apoptosis in response to melphalan or cisplatin, these findings may help to explain the myelosuppression after exposure to alkylating agents. (C) 2002 by The American Society of Hematology.