Department of Molecular and Cell Biology, Verna and Marrs McLean Department of Biochemistry and Alkek Center for Molecular Discovery, Baylor College of Medicine, Houston, TX 77030, USA.
Cancer Res. 2011 Dec 15;71(24):7376-86. doi: 10.1158/0008-5472.CAN-11-1154. Epub 2011 Oct 11.
Although alterations in xenobiotic metabolism are considered causal in the development of bladder cancer, the precise mechanisms involved are poorly understood. In this study, we used high-throughput mass spectrometry to measure over 2,000 compounds in 58 clinical specimens, identifying 35 metabolites which exhibited significant changes in bladder cancer. This metabolic signature distinguished both normal and benign bladder from bladder cancer. Exploratory analyses of this metabolomic signature in urine showed promise in distinguishing bladder cancer from controls and also nonmuscle from muscle-invasive bladder cancer. Subsequent enrichment-based bioprocess mapping revealed alterations in phase I/II metabolism and suggested a possible role for DNA methylation in perturbing xenobiotic metabolism in bladder cancer. In particular, we validated tumor-associated hypermethylation in the cytochrome P450 1A1 (CYP1A1) and cytochrome P450 1B1 (CYP1B1) promoters of bladder cancer tissues by bisulfite sequence analysis and methylation-specific PCR and also by in vitro treatment of T-24 bladder cancer cell line with the DNA demethylating agent 5-aza-2'-deoxycytidine. Furthermore, we showed that expression of CYP1A1 and CYP1B1 was reduced significantly in an independent cohort of bladder cancer specimens compared with matched benign adjacent tissues. In summary, our findings identified candidate diagnostic and prognostic markers and highlighted mechanisms associated with the silencing of xenobiotic metabolism. The metabolomic signature we describe offers potential as a urinary biomarker for early detection and staging of bladder cancer, highlighting the utility of evaluating metabolomic profiles of cancer to gain insights into bioprocesses perturbed during tumor development and progression.
虽然外源性代谢物的改变被认为是膀胱癌发展的原因，但涉及的确切机制仍知之甚少。在这项研究中，我们使用高通量质谱法测量了 58 个临床标本中的 2000 多种化合物，确定了 35 种代谢物在膀胱癌中发生了显著变化。这种代谢特征区分了正常和良性膀胱与膀胱癌。对尿液中这种代谢组学特征的探索性分析显示，在区分膀胱癌和对照组以及非肌肉浸润性膀胱癌和肌肉浸润性膀胱癌方面有希望。随后的基于富集的生物过程映射显示，I/II 期代谢物发生了改变，并提示 DNA 甲基化在外源性代谢物干扰膀胱癌中可能起作用。特别是，我们通过亚硫酸氢盐测序分析、甲基特异性 PCR 以及用 DNA 去甲基化剂 5-氮杂-2'-脱氧胞苷体外处理 T-24 膀胱癌细胞系，验证了膀胱癌组织中细胞色素 P450 1A1（CYP1A1）和细胞色素 P450 1B1（CYP1B1）启动子的肿瘤相关高甲基化，并通过独立的膀胱癌标本队列与匹配的良性相邻组织相比，CYP1A1 和 CYP1B1 的表达显著降低。总之，我们的研究结果确定了候选的诊断和预后标志物，并强调了与外源性代谢物沉默相关的机制。我们描述的代谢组学特征为早期检测和分期膀胱癌提供了潜在的尿生物标志物，突出了评估癌症代谢组学特征以深入了解肿瘤发生和进展过程中受干扰的生物过程的效用。
