High‐resolution analyses of copy number changes in disseminated tumor cells of patients with breast cancer

Abstract

The presence of disseminated tumor cells (DTCs) in bone marrow (BM) identifies breast cancer patients with less favorable outcome. Furthermore, molecular characterization is required to investigate the malignant potential of these cells. This study presents a single‐cell array comparative genomic hybridization (SCaCGH) method providing molecular analysis of immunomorphologically detected DTCs. The resolution limit of the method was estimated using the cancer cell line SK‐BR‐3 on 44 and 244k arrays. The technique was further tested on 28 circulating tumor cells and four hematopoietic cells (HCs) from peripheral blood (n = 8 patients). The SCaCGH method was finally applied to 24 DTCs, three immunopositive cells morphologically classified as probable HCs from breast cancer patients and five HC controls from BM (n = 7 patients plus n = 1 healthy donor). The frequency of copy number changes of the DTCs revealed similarities with primary breast tumor samples. Three of the patients had available profiles for DTCs and the corresponding tumor tissue from primary surgery. More than two‐third of the analyzed DTCs disclosed equivalent changes, both to each other and to the corresponding primary disease, whereas the rest of the cells showed balanced profiles. The probable HCs revealed either balanced profiles (n = 2) or changes comparable to the tumor tissue and DTCs (n = 1), indicating morphological overlap between HCs and DTCs. Similar aberration patterns were visible in DTCs collected at diagnosis and at 3 years relapse‐free follow‐up. SCaCGH may be a powerful tool for the molecular characterization of DTCs.

Tracing the origin of disseminated tumor cells in breast cancer using single-cell sequencing

“…In contrast, only one of the 21 single cells classified as uncertain, PHC, or HC turned out to be a true DTC (three out of 26 including doublets). While the adaptation of the staining-as required for downstream genomic analysis [26]-may have affected the precision of the morphologic classification of the immunodetected single cells, these findings still underscore its value (true positive rate 52.6 ± 11.5%, false negative rate 4.8 ± 4.7%). Notably, we found true DTCs for only three patients (MicMa003, 083 and 107), all of which went on to develop distant metastases (Table 1).…”

“…Following isolation of the selected cells from the cytospins, the single cells were lysed and their DNA amplified using the GenomePlex® Single-Cell WholeGenome Amplification Kit (Sigma-Aldrich, St. Louis, MO, USA) but using the Titanium Taq DNA polymerase (BD Biosciences Clontech, Heidelberg, Germany) instead of the kit's standard polymerase, as described by Mathiesen et al [26].…”

“…Additionally, copy number aberrations (CNAs) detected among DTCs from the same nonmetastatic patient were generally non-recurrent [23,25]. In contrast, DTCs isolated from the same patient burdened with metastatic disease frequently shared CNAs, also with the primary tumor and/or the lymph node metastasis, fitting a linear progression model [26,27].…”

Regulation of the MicroRNA 200b (miRNA-200b) by Transcriptional Regulators PEA3 and ELK-1 Protein Affects Expression of Pin1 Protein to Control Anoikis

“…These cells have lost interaction with the matrix and have obtained a balance between proliferation and apoptosis (53,54). MiRNA-200b could regulate proliferation in at least two ways.…”

Chemotherapy of WAP‐T mouse mammary carcinomas aggravates tumor phenotype and enhances tumor cell dissemination

“…1 About 25% of the patients develop distant metastases and ultimately die of breast cancer. 2 The prognosis of cancer patients is largely determined by the occurrence of distant metastases. Disseminated tumor cells (DTCs) in the bone marrow at diagnosis and during follow-up have been demonstrated in several early breast cancer studies to be of clinical relevance 3,4 and are used in patient risk assessment.…”