Departments of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
Theranostics. 2018 Aug 10;8(16):4520-4534. doi: 10.7150/thno.25130. eCollection 2018.
Alterations in DNA methylation are important epigenetic markers in bladder cancer (BC). These epigenome modifications may drive the mechanisms of aggressive chemo-resistant BC. Clinicopathological biomarkers that indicate chemotherapeutic resistance are critical for better assessing treatment strategies for individual patients. Thus, in this study, we aimed to determine whether DNA methylation of certain metabolic enzymes is significantly altered in cisplatin-resistant BC cells. To characterize CpG methylation and nucleosome accessibility in cisplatin-resistant BC cells, the Illumina Infinium HM450 DNA methylation assay was performed. Perturbed gene expression was found to be associated with cisplatin resistance, and the biological roles of spermidine/spermine N-acetyltransferase (SAT1) and argininosuccinate synthase 1 (ASS1) were further studied using qRT-PCR analysis and various cell biology assays, including western blot. and , genes for amino acid and polyamine metabolism catalysts, respectively, were found to be vastly hypermethylated, resulting in greatly downregulated expression. ASS1 expression is of particular interest because prior studies have demonstrated its potential association with BC stage and recurrence. In regard to chemoresistance, we found that aberrant expression or induced stimulation of SAT1 restored cisplatin sensitivity in the cell culture system. We also found that the addition of exogenous arginine deiminase through administration of ADI-PEG 20 (pegylated arginine deiminase) increased ASS1 expression and enhanced cisplatin's apoptotic effects. Our study demonstrates a novel mechanistic link between the epigenetic perturbation of SAT1 and ASS1 and cancer metabolism in cisplatin-resistant bladder cancer cells. These findings suggest potential utility of and as predictive biomarkers in re-sensitizing bladder cancer to chemotherapy and personalizing therapy.
DNA 甲基化的改变是膀胱癌（BC）中重要的表观遗传标记。这些表观基因组修饰可能驱动了侵袭性化疗耐药 BC 的机制。预示化疗耐药的临床病理生物标志物对于更好地评估个体患者的治疗策略至关重要。因此，在这项研究中，我们旨在确定顺铂耐药 BC 细胞中某些代谢酶的 DNA 甲基化是否发生显著改变。 为了描述顺铂耐药 BC 细胞中的 CpG 甲基化和核小体可及性，进行了 Illumina Infinium HM450 DNA 甲基化分析。发现失调的基因表达与顺铂耐药相关，并且使用 qRT-PCR 分析和各种细胞生物学测定（包括 Western blot）进一步研究了 spermidine/spermine N-acetyltransferase (SAT1) 和 argininosuccinate synthase 1 (ASS1) 的生物学作用。 分别是氨基酸和多胺代谢催化剂的基因，发现它们被广泛过度甲基化，导致表达大大下调。ASS1 表达特别有趣，因为先前的研究表明它可能与 BC 分期和复发有关。关于化疗耐药性，我们发现 SAT1 的异常表达或诱导刺激在细胞培养系统中恢复了顺铂敏感性。我们还发现，通过给予 ADI-PEG 20（聚乙二醇化精氨酸脱氨酶）添加外源性精氨酸脱氨酶可增加 ASS1 的表达并增强顺铂的凋亡作用。 我们的研究证明了 SAT1 和 ASS1 的表观遗传扰动与顺铂耐药膀胱癌细胞中的癌症代谢之间存在新的机制联系。这些发现表明 和 作为重新使膀胱癌对化疗敏感和个性化治疗的预测生物标志物具有潜在的用途。
