The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, UK.
Breast Cancer Res Treat. 2013 Jun;139(2):341-50. doi: 10.1007/s10549-013-2544-8. Epub 2013 May 15.
DNA methylation of tumor-suppressor genes occurs early in the molecular transformation of precursor events to breast cancer and is therefore of interest to screening in high-risk women. The aim of this study was to use tumor-suppressor genes that have previously been shown to be cancer predictive in tissue to evaluate the potential of DNA methylation assays in cells from duct lavage (DL) fluid. The frequency of target gene DNA methylation in tissue and DL of cancer and healthy control patients was assessed, and an association of DNA methylation between different duct systems in the same breast was explored. The cancer and control groups were identified in the outpatient clinic when surgical treatment was finalized. Tumor, adjacent tissue and bilateral DL samples for comparative DNA methylation studies were obtained during surgery from women with cancer. In the healthy control group, samples of tissue and DL were collected. Reverse transcriptase methylation-specific PCR was conducted on modified DNA purified from 42 cancer biopsies, 41 benign excision cavity biopsies (internal control), 29 benign biopsies (external control), and 119 DL specimens. A validated panel of cancer predictive genes was analyzed in the study bank of tissue and DL samples from cancer and healthy patients. The sensitivity of DNA methylation in DL samples compared with matched cancer tissue was highest for SCGB3A1 (90 %), CDH13 (91 %), and RARB (83 %). The genetic algorithm selected RASSF1A, RARB, and IGFBP7 as the optimum predictor set for detecting DNA methylation in cancer tissue. The optimum area under the ROC curve for DNA methylation in cancer compared with internal control healthy tissue from excision margins was 0.84. The area under the ROC curve for DNA methylation in cancer DL compared with contralateral benign DL was 0.76. DL cytology was not a helpful predictor of breast cancer. This study shows that relative patterns of tumor-suppressor gene hypermethylation in breast cancer tissue are significantly reflected in the DL from the cancer affected breast. Using DL, nonconcordant patterns of DNA methylation between different duct systems confer independent oncologic potential for distinct breast lobes. The approach of DNA methylation in DL may be substantiated by a larger trial of breast cancer biomarkers.
肿瘤抑制基因的 DNA 甲基化发生在乳腺癌前体事件的分子转化早期，因此对高危女性的筛查具有重要意义。本研究旨在使用先前在组织中显示具有预测癌症作用的肿瘤抑制基因，评估 DNA 甲基化检测在乳腺导管灌洗（DL）液细胞中的潜力。评估了癌症和健康对照组患者组织和 DL 中靶基因 DNA 甲基化的频率，并探讨了同一乳房不同导管系统之间 DNA 甲基化的相关性。当手术治疗最终确定时，在门诊诊所确定癌症和对照组。在手术过程中，从患有癌症的女性中获得了肿瘤、相邻组织和双侧 DL 样本，用于比较 DNA 甲基化研究。在健康对照组中，收集了组织和 DL 的样本。对 42 例癌症活检、41 例良性切除腔活检（内部对照）、29 例良性活检（外部对照）和 119 例 DL 标本的修饰 DNA 进行逆转录酶甲基化特异性 PCR。在癌症和健康患者的组织和 DL 样本研究库中分析了经过验证的癌症预测基因面板。与匹配的癌症组织相比，DL 样本中 DNA 甲基化的敏感性以 SCGB3A1（90%）、CDH13（91%）和 RARB（83%）最高。遗传算法选择 RASSF1A、RARB 和 IGFBP7 作为检测癌症组织中 DNA 甲基化的最佳预测因子集。与来自切除边缘的内部对照健康组织相比，癌症中 DNA 甲基化的 ROC 曲线下面积为 0.84。与对侧良性 DL 相比，癌症 DL 中 DNA 甲基化的 ROC 曲线下面积为 0.76。DL 细胞学不是乳腺癌的有用预测因子。本研究表明，乳腺癌组织中肿瘤抑制基因高甲基化的相对模式在受癌症影响的乳房的 DL 中得到了显著反映。使用 DL，不同导管系统之间 DNA 甲基化的不一致模式为不同的乳腺叶赋予了独立的肿瘤潜力。更大规模的乳腺癌生物标志物试验可能会证实 DL 中的 DNA 甲基化方法。
