Van der Auwera I, Elst H J, Van Laere S J, Maes H, Huget P, van Dam P, Van Marck E A, Vermeulen P B, Dirix L Y
Translational Cancer Research Group, Laboratory of Pathology, University of Antwerp/University Hospital Antwerp, Oncology Centre, General Hospital St-Augustinus, Wilrijk, Belgium.
Br J Cancer. 2009 Apr 21;100(8):1277-86. doi: 10.1038/sj.bjc.6605013.
Circulating tumour cells (CTC) and tumour-related methylated DNA in blood have been separately assessed for their utility as a marker for subclinical metastasis in breast cancer. However, no studies have looked into the relation between the both molecular markers in this type of cancer. In this study, we investigated the correlations between total/methylated DNA and CTC in the blood from metastatic breast cancer patients. We simultaneously obtained whole blood, plasma and serum samples from 80 patients and 20 controls. The CellSearch System was used to enumerate CTC in blood samples. Plasma total DNA levels were determined by a QPCR method. Sera were analysed by methylation-specific QPCR for three markers: adenomatous polyposis coli (APC), ras association domain family protein 1A (RASSF1A) and oestrogen receptor 1 (ESR1). Total DNA levels in patients were significantly increased when compared with controls (P<0.001) and correlated with the number of CTC (r=0.418, P<0.001). Hypermethylation of one or more genes was detected in 42 (53%) serum samples from breast cancer patients and in three (16%) serum samples from controls (P=0.003). APC was hypermethylated in 29%, RASSF1A in 35% and ESR1 in 20% of breast cancer cases. Detection of a methylated gene in serum was associated with the detection of CTC in blood (P=0.03). The detection of large amounts of circulating total/methylated DNA correlated with the presence of CTC in the blood from patients with breast cancer. This can be interpreted in two ways: (a) CTC are a potential source of circulating tumour-specific DNA; (b) high numbers of CTC and circulating methylated DNA are both a phenotypic feature of more aggressive tumour biology.
循环肿瘤细胞（CTC）和血液中与肿瘤相关的甲基化DNA已分别被评估作为乳腺癌亚临床转移标志物的效用。然而，尚无研究探讨这两种分子标志物在这类癌症中的关系。在本研究中，我们调查了转移性乳腺癌患者血液中总DNA/甲基化DNA与CTC之间的相关性。我们同时从80例患者和20例对照中获取全血、血浆和血清样本。使用CellSearch系统对血液样本中的CTC进行计数。通过定量聚合酶链反应（QPCR）方法测定血浆总DNA水平。对血清进行甲基化特异性QPCR分析，检测三个标志物：腺瘤性息肉病 coli（APC）、Ras相关结构域家族蛋白1A（RASSF1A）和雌激素受体1（ESR1）。与对照组相比，患者的总DNA水平显著升高（P<0.001），且与CTC数量相关（r = 0.418，P<0.001）。在42例（53%）乳腺癌患者的血清样本和3例（16%）对照血清样本中检测到一个或多个基因的高甲基化（P = 0.003）。在29%的乳腺癌病例中检测到APC高甲基化，35%检测到RASSF1A高甲基化，20%检测到ESR1高甲基化。血清中甲基化基因的检测与血液中CTC的检测相关（P = 0.03）。检测到大量循环总DNA/甲基化DNA与乳腺癌患者血液中CTC的存在相关。这可以从两种方式来解释：（a）CTC是循环肿瘤特异性DNA的潜在来源；（b）大量的CTC和循环甲基化DNA都是更具侵袭性肿瘤生物学的表型特征。
