1
|
Kaur P, Campo D, Porras TB, Ring A, Lu J, Chairez Y, Su Y, Kang I, Lang JE. A Pilot Study for the Feasibility of Exome-Sequencing in Circulating Tumor Cells Versus Single Metastatic Biopsies in Breast Cancer. Int J Mol Sci 2020; 21:ijms21144826. [PMID: 32650480 PMCID: PMC7402350 DOI: 10.3390/ijms21144826] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 11/16/2022] Open
Abstract
The comparison of the landscape of somatic alterations in circulating tumor cells (CTCs) versus metastases is challenging. Here, we comprehensively characterized the somatic landscape in bulk (amplified and non-amplified), spike-in breast cancer cells, CTCs, and metastases from breast cancer patients using whole-exome sequencing (WES). We determined the level of genomic concordance for somatic nucleotide variants (SNVs), copy number alterations (CNAs), and structural variants (SVs). The variant allele fractions (VAFs) of somatic variants were remarkably similar between amplified and non-amplified cell line samples as technical replicates. In clinical samples, a significant fraction of somatic variants had low VAFs in CTCs compared to metastases. The most frequently recurrent gene mutations in clinical samples were associated with an elevated C > T mutational signature. We found complex rearrangement patterns including intra- and inter-chromosomal rearrangements, singleton, and recurrent gene fusions, and tandem duplications. We observed high molecular discordance for somatic alterations between paired samples consistent with marked heterogeneity of the somatic landscape. The most prevalent copy number calls were focal deletion events in CTCs and metastases. Our results demonstrate the feasibility of an integrated workflow for the identification of a complete repertoire of somatic alterations and highlight the intrapatient genomic differences that occur between CTCs and metastases.
Collapse
Affiliation(s)
- Pushpinder Kaur
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; (P.K.); (Y.S.)
- University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA; (J.L.); (I.K.)
| | - Daniel Campo
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA;
| | - Tania B. Porras
- Cancer and Blood Disease Institute, Children Hospital Los Angeles, University of Southern California, Los Angeles, CA 90027, USA;
| | - Alexander Ring
- Department of Oncology and Hematology, UniversitätsSpital Zürich, Rämistrasse 100, 8091 Zürich, Switzerland;
| | - Janice Lu
- University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA; (J.L.); (I.K.)
- Division of Medical Oncology, Department of Medicine and University of Southern California Norris Cancer Center, University of Southern California, Los Angeles, CA 90033, USA
| | - Yvonne Chairez
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA;
| | - Yunyun Su
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; (P.K.); (Y.S.)
- University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA; (J.L.); (I.K.)
| | - Irene Kang
- University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA; (J.L.); (I.K.)
- Division of Medical Oncology, Department of Medicine and University of Southern California Norris Cancer Center, University of Southern California, Los Angeles, CA 90033, USA
| | - Julie E. Lang
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; (P.K.); (Y.S.)
- University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA; (J.L.); (I.K.)
- Correspondence: ; Tel.: +1-(323)-442-8140
| |
Collapse
|
2
|
Porras TB, Kaur P, Ring A, Schechter N, Lang JE. Challenges in using liquid biopsies for gene expression profiling. Oncotarget 2018; 9:7036-7053. [PMID: 29467948 PMCID: PMC5805534 DOI: 10.18632/oncotarget.24140] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 12/26/2017] [Indexed: 02/07/2023] Open
Abstract
Circulating tumor cells (CTCs) have potential utility as a surrogate biomarker of tumor biology via a liquid biopsy. The aim of this study was to evaluate if the nCounter NanoString assay could be used for accurate gene expression profiling of CTCs using the PAM50 research-use-only CodeSet. Analysis was performed on CTCs isolated by the ANGLE Parsortix system from healthy blood spiked with the breast cancer cell lines Hs578T, SkBr3, MDA-MB-231 or MCF7. Using cell lines as gold standard positive controls and Parsortix processed blood without spiking (unspiked) as negative controls, we found an average of 12 significantly differentially expressed genes among spiked samples versus unspiked controls. We validated our findings with the NanoStringDiff differential expression statistical method. The NanoString recommended targeted pre-amplification introduced false positive results due to pre-amplification bias, and the amplification of non-cancer genes from normal leukocytes confounded gene expression profiling of CTCs. Pre-amplification bias is a concern for other similar assays that may be used as discovery tools or target validation of transcripts of interest in gene expression profiling of CTCs. We recommend the use of an unspiked negative control when evaluating CTC technologies regarding gene expression profiling. Given that the molecular profiling of CTCs as a liquid biopsy may have clinical ramifications for potential treatment selection in future clinical trials, our study emphasizes cautious consideration of pre-analytical variables such as amplification bias in the context of liquid biopsy studies.
Collapse
Affiliation(s)
- Tania B Porras
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.,University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA, United States
| | - Pushpinder Kaur
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.,University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA, United States
| | - Alexander Ring
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.,University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA, United States
| | - Naomi Schechter
- Department of Radiation Oncology, Keck Medical Center, University of Southern California, Los Angeles, CA, United States.,University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA, United States
| | - Julie E Lang
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.,University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA, United States
| |
Collapse
|