ATP-binding cassette (ABC) transporters play a crucial role in multidrug resistance (MDR) of cancers. They function as efflux pumps, resulting in limited effectiveness or even failure of therapy. Increasing evidence suggests that ABC transporters are also involved in tumor initiation, progression, and metastasis. Tumors frequently show multiple genetic and epigenetic abnormalities, including changes in histone modification and DNA methylation. Alterations in the DNA methylation status of ABC transporters have been reported for a variety of cancer types. In this review, we outline the current knowledge of DNA methylation of ABC transporters in cancer. We give a brief introduction to structure, function, and gene regulation of ABC transporters that have already been investigated for their DNA methylation status in cancer. After giving an overview of the applied methodologies and the CpGs analyzed, we summarize and discuss the findings on aberrant DNA methylation of ABC transporters by cancer types. We conclude our review with the discussion of the potential to target aberrant DNA methylation of ABC transporters for cancer therapy.

中文翻译：

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癌症中ABC转运蛋白的异常DNA甲基化

ATP结合盒（ABC）转运蛋白在癌症的多药耐药性（MDR）中起着至关重要的作用。它们充当外排泵，导致疗效有限甚至失败。越来越多的证据表明，ABC转运蛋白也参与了肿瘤的发生，发展和转移。肿瘤经常表现出多种遗传和表观遗传异常，包括组蛋白修饰和DNA甲基化的变化。对于多种癌症类型，已经报道了ABC转运蛋白的DNA甲基化状态的改变。在这篇综述中，我们概述了癌症中ABC转运蛋白的DNA甲基化的最新知识。我们简要介绍了ABC转运蛋白的结构，功能和基因调控，这些转运蛋白已经针对其在癌症中的DNA甲基化状态进行了研究。在概述了所应用的方法并分析了CpG之后，我们总结并讨论了按癌症类型分类的ABC转运蛋白异常DNA甲基化的发现。我们以讨论针对ABC转运蛋白的异常DNA甲基化潜力进行癌症治疗的讨论作为总结。