Triple-negative breast cancer (TNBC) liver metastasis is associated with poor prognosis and low patient survival. It occurs when tumor cells disseminate from primary tumors, circulate in blood/lymph [circulating tumor cells (CTCs)], and acquire distinct characteristics during disease progression toward the metastatic phenotype. The purpose of this study was to decipher the genomic/transcriptomic properties of TNBC liver metastasis and its recurrence for potential therapeutic targeting. We employed a negative depletion strategy to isolate and interrogate CTCs from the blood of patients with TNBC, and to establish sequential generations of CTC-derived xenografts (CDXs) through injection of patient CTCs in immunodeficient mice. The isolation and validation of CDX-derived cell populations [analyses of CTCs were paired with bone marrow-resident cells (BMRTCs) and liver tissue cells obtained from the same animal] were performed by multiparametric flow cytometry, immune phenotyping, and genomic sequencing of putative CTCs. Comprehensive characterization of gene expression arrays from sequentially generated CDX-derived cell populations, online gene expression arrays, and TCGA databases were employed to discover a CTC-driven, liver metastasis-associated TNBC signature. We discovered a distinct transcriptomic signature of TNBC patient-isolated CTCs from primary TNBCs, which was consistent throughout sequential CDX modeling. We established a novel TNBC liver metastasis-specific CDX model that selectively recapitulates CTC biology for four sequential generations of mice. The evaluation of online databases and CDX-derived populations revealed 597 genes specific to the TNBC liver metastasis signatures. Further investigation of the TNBC liver metastasis signature predicted 16 hub genes, 6 biomarkers with clinically available drugs, and 22 survival genes. The sequential interrogation of CDX-CTCs is an innovative liquid biopsy-based approach for the discovery of organ metastasis-specific signatures of CTCs. This represents the first step for mechanistic and analytical validation in their application as prognostic indicators and therapeutic targets. Targeting CTC drug candidate biomarkers along with combination therapy can improve the clinical outcome of TNBC patients in general and recurrence of liver metastasis in particular.

中文翻译：

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通过顺序CTC-异种移植模型鉴定TNBC肝转移基因签名。

三阴性乳腺癌（TNBC）肝转移与预后不良和患者生存率低有关。当肿瘤细胞从原发性肿瘤中扩散出来，在血液/淋巴中循环[循环肿瘤细胞（CTC）]，并在疾病向转移表型发展的过程中获得独特的特征时，就会发生这种情况。这项研究的目的是破译TNBC肝转移的基因组/转录组特性及其对于潜在治疗靶点的复发。我们采用了一种阴性耗竭策略从TNBC患者的血液中分离和讯问CTC，并通过在免疫缺陷小鼠中注射患者CTC来建立CTC衍生异种移植物（CDXs）的连续世代。通过多参数流式细胞术，免疫表型分析和推定基因组测序对CDX来源的细胞群进行分离和验证[将CTC的分析与从同一动物获得的骨髓驻留细胞（BMRTC）和肝组织细胞配对]四氯化碳。从顺序生成的CDX衍生的细胞群体，在线基因表达阵列和TCGA数据库对基因表达阵列进行全面表征，以发现CTC驱动的肝转移相关的TNBC签名。我们从原发性TNBC中发现了TNBC患者隔离的CTC的独特转录组签名，在整个顺序CDX建模中都是一致的。我们建立了一个新颖的TNBC肝转移特异性CDX模型，该模型选择性地概括了四代连续小鼠的CTC生物学。在线数据库和CDX来源人群的评估揭示了597个特定于TNBC肝转移特征的基因。TNBC肝转移标记的进一步研究预测了16个中枢基因，6个具有临床可用药物的生物标记以及22个存活基因。CDX-CTC的顺序询问是一种创新的基于液体活检的方法，用于发现CTC的器官转移特异性特征。这代表了机械和分析验证在其作为预后指标和治疗靶标应用中的第一步。靶向CTC候选药物生物标志物以及联合治疗可以总体上改善TNBC患者的临床结局，尤其是改善肝转移的复发。