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Published on: March 21, 2018
KRAS mutation analysis of single circulating tumor cells from patients with metastatic colorectal cancer
Yuurin Kondo1, Kazuhiko Hayashi2, Kazuyuki Kawakami2
1Department of Chemotherapy and Palliative Care, Tokyo Women's Medical University, 8-1 Kawada-chyo, Shinjuku-ku, Tokyo, 162-8666, Japan. kondo.yurin@twmu.ac.jp.
Background:
The molecular profiles of tumors may inform the selection of appropriate targeted therapies. Circulating tumor cells (CTCs) reflect the real-time status of tumor genotypes. CTCs exhibit high genetic heterogeneity within a patient; accordingly, the analysis of individual CTCs, including their heterogeneity, may enable more precise treatments. We analyzed KRAS mutations in single CTCs from patients with metastatic colorectal cancer (mCRC) using a new single-cell picking system.
Methods:
Blood samples were obtained from 61 patients with mCRC. CTCs were enriched and fluorescently labeled using the CellSearch® System. They were recovered using the single-cell picking system based on the fluorescence intensity of marker dyes. Single CTCs and tumor tissue samples were examined for mutations in codons 12 and 13 of the KRAS gene.
Results:
CTCs were detected in 27 of 61 patients with mCRC. We isolated at least two CTCs from 15 of 27 patients. KRAS genotype was evaluated in a total of 284 CTCs from 11 patients, and 15 cells with mutations were identified in four patients. In 10 of 11 patients, the KRAS status was the same in the primary tumor and CTCs. In one patient, the KRAS status was discordant between the primary tumor and CTCs. In two patients, different KRAS mutations were found among individual CTCs.
Conclusions:
We successfully isolated single CTCs and detected KRAS mutations in individual cells from clinical samples using a novel application of single-cell isolation system. Using the system, we detected CTC heterozygosity and heterogeneity in KRAS status among CTCs within a patient and between CTCs and tumor tissues.
Insights
Analyzing KRAS mutations in single circulating tumor cells (CTCs) from metastatic colorectal cancer (mCRC) patients reveals genetic heterogeneity. This single-cell analysis offers potential for more precise, personalized cancer treatments.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Tumor molecular profiles guide targeted therapy selection.
- Circulating tumor cells (CTCs) provide real-time tumor genotype information.
- CTCs display significant intra-patient genetic heterogeneity, necessitating individual cell analysis for precise treatment.
Purpose of the Study:
- To analyze KRAS mutations in single CTCs from patients with metastatic colorectal cancer (mCRC).
- To evaluate the utility of a novel single-cell picking system for analyzing CTCs.
- To investigate KRAS mutation heterogeneity within and between CTCs and tumor tissues.
Main Methods:
- Blood samples from 61 mCRC patients were analyzed.
- CTCs were enriched and labeled using the CellSearch® System.
- A single-cell picking system was employed to isolate CTCs for KRAS mutation analysis (codons 12 and 13).
Main Results:
- CTCs were detected in 27 of 61 patients; single CTCs were isolated from 15.
- KRAS mutations were identified in 15 of 284 analyzed CTCs from 11 patients.
- Discordant KRAS status was observed between primary tumor and CTCs in one patient; intratumoral heterogeneity was found in two patients.
Conclusions:
- Single CTC isolation and KRAS mutation detection were successfully achieved using a novel system.
- The system identified KRAS genotype heterogeneity among CTCs within a patient.
- This approach enables the detection of heterogeneity between CTCs and primary tumor tissues.
