Adenomatous polyposis coli-mediated hypersensitivity of mouse embryonic fibroblast cell lines to methylmethane sulfonate treatment: implication of base excision repair pathways
Adenomatous polyposis coli-mediated hypersensitivity of mouse embryonic fibroblast cell lines to methylmethane sulfonate treatment: implication of base excision repair pathways
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DOI：
10.1093/carcin/bgm125
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发表时间：
2007-10-01
期刊：
影响因子：
4.7
通讯作者：
Narayan, Satya
中科院分区：
文献类型：
--
作者：
Kundu, Chanakya N.;Balusu, Ramesh;Narayan, Satya
结肠腺瘤性息肉病(APC)与多种细胞功能有关，包括细胞迁移、细胞间黏附、细胞周期调控、染色体分离和细胞凋亡。最近，我们发现了APC在DNA碱基切除修复(BER)中的一个新的作用，并发现APC与DNA聚合酶β(Pol-beta)和翻盖核酸内切酶1相互作用，并通过阻断链置换合成来干扰长斑块碱基切除修复(LP-BER)。许多情况下，化疗药物会导致DNA烷基化损伤，这种损伤主要通过BER途径修复。因此，APC可以提高这类药物的疗效，从而阻断LP-BER。在本研究中，我们使用同基因野生型和Pol-β基因敲除的小鼠胚胎成纤维细胞(MEF)细胞株来验证这一假设，在MEF细胞系中，APC基因被小干扰RNA技术敲除并用甲基甲烷磺酸(MMS)处理。与MEF-APC(WT)/Pol beta(-/-)细胞相比，MEF-APC(WT)/Pol beta(-/-)细胞对MMS超敏。然而，一旦APC基因被敲除，这些细胞对MMS处理的抵抗力变得更强，这表明MMS诱导的超敏反应与APC有关。然后，我们确定MEF-APC(WT)/Pol beta(-/-)和MEF-APC(WT)/Pol beta(-/-)细胞系的超敏反应是否分别是由于Pol-β非依赖和Pol-β依赖的LP-BER通路减少所致。体内和体外LP-BER测试结果支持我们的发现。此外，与MEF-APC(KD)/Polβ(-/-)和MEF-APC(KD)/Polβ(+/+)细胞相比，APC介导的MMS治疗超敏反应与MEF-APC(WT)/Polβ(-/-)和MEF-APC(WT)/Polβ(+/+)细胞的凋亡率增加相关。这些结果表明，增加APC水平可以增加DNA烷基化药物的疗效作为一种根治疗法。
The role of adenomatous polyposis coli (APC) has been implicated in various cellular functions including cell migration, cell - cell adhesion, cell cycle control, chromosomal segregation and apoptosis. Recently, we discovered a novel role of APC in DNA base excision repair (BER) and showed that APC interacts with DNA polymerase beta (Pol-beta) and flap endonuclease 1 and interferes long-patch base excision repair (LP-BER) by blocking strand displacement synthesis. Many times, the chemotherapeutic drugs induce DNA alkylation damage, which is primarily repaired by the BER pathway. Thus, the efficacy of such drugs can be increased by APC resulting in the blockage of LP-BER. In the present study, we tested this hypothesis by using isogenic wild-type and Pol-beta-knockout mouse embryonic fibroblast (MEF) cell lines in which the Apc gene was knocked down by the small interfering RNA technique and treated with methylmethane sulfonate (MMS). The MEF-Apc(WT)/Pol beta(-/-) cells were hypersensitive to MMS treatment compared with the MEF-Apc(WT)/Pol beta(-/-) cells. However, once the Apc gene was knocked down, these cells became more resistant to MMS treatment, suggesting that the MMS-induced hypersensitivity was associated with Apc. We then determined whether the hypersensitivity of MEF-Apc(WT)/Pol beta(-/-) and MEF-Apc(WT)/Pol beta(-/-) cell lines were due to decreased Pol-beta-independent and Pol-beta-dependent LP-BER pathways, respectively. The results of in vivo and in vitro LP-BER assays supported our findings. Furthermore, Apc-mediated hypersensitivity to MMS treatment was correlated with increased apoptosis of MEF-Apc(WT)/Pol beta(-/-) and MEF-Apc(WT)/Pol beta(+/+) as compared with MEF-Apc(KD)/Pol beta(-/-) and MEF-Apc(KD)/Pol beta(+/+) cells. These results suggest that an increased level of Apc can increase the efficacy of DNA-alkylating drugs used as a curative therapy.