Rossi Tania, Gallerani Giulia, Angeli Davide, Cocchi Claudia, Bandini Erika, Fici Pietro, Gaudio Michele, Martinelli Giovanni, Rocca Andrea, Maltoni Roberta, Fabbri Francesco
Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, 47014 Meldola, Italy.
Unit of Biostatistics and Clinical Trials, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, 47014 Meldola, Italy.
Cancers (Basel). 2020 Sep 2;12(9):2490. doi: 10.3390/cancers12092490.
Circulating tumor cells (CTCs) are a rare population of cells representing a key player in the metastatic cascade. They are recognized as a validated tool for the identification of patients with a higher risk of relapse, including those diagnosed with breast cancer (BC). However, CTCs are characterized by high levels of heterogeneity that also involve copy number alterations (CNAs), structural variations associated with gene dosage changes. In this study, single CTCs were isolated from the peripheral blood of 11 early-stage BC patients at different time points. A label-free enrichment of CTCs was performed using OncoQuick, and single CTCs were isolated using DEPArray. Libraries were prepared from single CTCs and DNA extracted from matched tumor tissues for a whole-genome low-coverage next-generation sequencing (NGS) analysis using the Ion Torrent S5 System. The analysis of the CNA burden highlighted that CTCs had different degrees of aberration based on the time point and subtype. CTCs were found even six months after surgery and shared CNAs with matched tumor tissue. Tumor-associated CNAs that were recurrent in CTCs were patient-specific, and some alterations involved regions associated with BC and survival (i.e., gains at 1q21-23 and 5p15.33). The enrichment analysis emphasized the involvement of aberrations of terms, associated in particular with interferon (IFN) signaling. Collectively, our findings reveal that these aberrations may contribute to understanding the molecular mechanisms involving CTC-related processes and their survival ability in occult niches, supporting the goal of exploiting their application in patients' surveillance and follow-up.
循环肿瘤细胞（CTCs）是一类罕见的细胞群体，是转移级联反应中的关键参与者。它们被认为是一种经过验证的工具，可用于识别复发风险较高的患者，包括那些被诊断为乳腺癌（BC）的患者。然而，CTCs具有高度的异质性，这也涉及拷贝数改变（CNAs），即与基因剂量变化相关的结构变异。在本研究中，在不同时间点从11例早期BC患者的外周血中分离出单个CTCs。使用OncoQuick对CTCs进行无标记富集，并使用DEPArray分离单个CTCs。从单个CTCs制备文库，并从匹配肿瘤组织中提取DNA，使用Ion Torrent S5系统进行全基因组低覆盖度下一代测序（NGS）分析。对CNA负担的分析突出表明，CTCs根据时间点和亚型具有不同程度的畸变。术后六个月仍能发现CTCs，并且它们与匹配的肿瘤组织共享CNAs。CTCs中反复出现的肿瘤相关CNAs是患者特异性的，一些改变涉及与BC和生存相关的区域（即1q21-23和5p15.33处的增益）。富集分析强调了特别是与干扰素（IFN）信号传导相关的术语畸变的参与。总体而言，我们的研究结果表明，这些畸变可能有助于理解涉及CTCs相关过程的分子机制及其在隐匿微环境中的生存能力，支持在患者监测和随访中利用其应用的目标。
