Single Cell Profiling of Circulating Tumor Cells: Transcriptional Heterogeneity and Diversity from Breast Cancer Cell Lines

• Published in: PloS one Vol. 7; no. 5; p. e33788
• Main Authors: Powell, Ashley A., Talasaz, AmirAli H., Zhang, Haiyu, Coram, Marc A., Reddy, Anupama, Deng, Glenn, Telli, Melinda L., Advani, Ranjana H., Carlson, Robert W., Mollick, Joseph A., Sheth, Shruti, Kurian, Allison W., Ford, James M., Stockdale, Frank E., Quake, Stephen R., Pease, R. Fabian, Mindrinos, Michael N., Bhanot, Gyan, Dairkee, Shanaz H., Davis, Ronald W., Jeffrey, Stefanie S.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.05.2012; Public Library of Science (PLoS)
• Subjects: Analysis; Antigens; Biochemistry; Bioengineering; Biology; Biopsy; Biotechnology; Blood; Blood circulation; Breast cancer; Breast Neoplasms - blood; Breast Neoplasms - genetics; Breast Neoplasms - metabolism; Cancer; Cancer metastasis; Cancer treatment; Cell Line, Tumor; Contamination; CXCR4 protein; Drug discovery; Electrical engineering; Engineering; Epidermal growth factor; Feasibility studies; Female; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Genes; Genetic aspects; Genomes; Health aspects; Heterogeneity; Humans; Kinases; Leukocytes; Lymphoma - blood; Medical research; Medicine; Mesenchyme; Metastases; Metastasis; Microarray Analysis - methods; Microfluidic Analytical Techniques; Microfluidics; Molecular biology; Motility; Neoplasm Metastasis; Neoplastic Cells, Circulating - metabolism; Pancreatic cancer; Patients; Prostate; Rodents; S100A4 protein; Single-Cell Analysis - instrumentation; Single-Cell Analysis - methods; Solid tumors; Stem cells; Subgroups; Surgery; Therapy; Transcription; Transcription (Genetics); Transforming growth factors; Tumor cell lines; Tumor cells; Tumors; Palo Alto California; California; United States > US; New Brunswick New Jersey
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0033788

To improve cancer therapy, it is critical to target metastasizing cells. Circulating tumor cells (CTCs) are rare cells found in the blood of patients with solid tumors and may play a key role in cancer dissemination. Uncovering CTC phenotypes offers a potential avenue to inform treatment. However, CTC transcriptional profiling is limited by leukocyte contamination; an approach to surmount this problem is single cell analysis. Here we demonstrate feasibility of performing high dimensional single CTC profiling, providing early insight into CTC heterogeneity and allowing comparisons to breast cancer cell lines widely used for drug discovery. We purified CTCs using the MagSweeper, an immunomagnetic enrichment device that isolates live tumor cells from unfractionated blood. CTCs that met stringent criteria for further analysis were obtained from 70% (14/20) of primary and 70% (21/30) of metastatic breast cancer patients; none were captured from patients with non-epithelial cancer (n = 20) or healthy subjects (n = 25). Microfluidic-based single cell transcriptional profiling of 87 cancer-associated and reference genes showed heterogeneity among individual CTCs, separating them into two major subgroups, based on 31 highly expressed genes. In contrast, single cells from seven breast cancer cell lines were tightly clustered together by sample ID and ER status. CTC profiles were distinct from those of cancer cell lines, questioning the suitability of such lines for drug discovery efforts for late stage cancer therapy. For the first time, we directly measured high dimensional gene expression in individual CTCs without the common practice of pooling such cells. Elevated transcript levels of genes associated with metastasis NPTN, S100A4, S100A9, and with epithelial mesenchymal transition: VIM, TGFß1, ZEB2, FOXC1, CXCR4, were striking compared to cell lines. Our findings demonstrate that profiling CTCs on a cell-by-cell basis is possible and may facilitate the application of 'liquid biopsies' to better model drug discovery.