High fragmentation characterizes tumour-derived circulating DNA

• Published in: PloS one Vol. 6; no. 9; p. e23418
• Main Authors: Mouliere, Florent, Robert, Bruno, Arnau Peyrotte, Erika, Del Rio, Maguy, Ychou, Marc, Molina, Franck, Gongora, Celine, Thierry, Alain R
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 06-09-2011; Public Library of Science (PLoS)
• Subjects: Analysis; Animals; Apoptosis; Biology; Biomarkers; Breast cancer; Cancer; Cancer metastasis; Cell Line, Tumor; Chemotherapy; Colon; Colon cancer; Colorectal cancer; Colorectal carcinoma; Colorectal Neoplasms - blood; Colorectal Neoplasms - genetics; Colorectal Neoplasms - pathology; Data processing; Deoxyribonucleic acid; Diagnostic software; Diagnostic systems; DNA; DNA Fragmentation; DNA, Neoplasm - blood; Epidermal growth factor; Female; Fragmentation; Fragments; Gangrene; Genetic aspects; Health; Human health and pathology; Humans; Life Sciences; Lung cancer; Lung diseases; Medical research; Medicine; Metastases; Metastasis; Mice; Mice, Nude; Mutation; Oncology; Patients; Plasma; Polymerase Chain Reaction; Size distribution; Spectrum analysis; Tumor Burden; Tumors; Xenograft Model Antitumor Assays; Xenografts; France
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0023418

Circulating DNA (ctDNA) is acknowledged as a potential diagnostic tool for various cancers including colorectal cancer, especially when considering the detection of mutations. Certainly due to lack of normalization of the experimental conditions, previous reports present many discrepancies and contradictory data on the analysis of the concentration of total ctDNA and on the proportion of tumour-derived ctDNA fragments.
In order to rigorously analyse ctDNA, we thoroughly investigated ctDNA size distribution. We used a highly specific Q-PCR assay and athymic nude mice xenografted with SW620 or HT29 human colon cancer cells, and we correlated our results by examining plasma from metastatic CRC patients.
Fragmentation and concentration of tumour-derived ctDNA is positively correlated with tumour weight. CtDNA quantification by Q-PCR depends on the amplified target length and is optimal for 60-100 bp fragments. Q-PCR analysis of plasma samples from xenografted mice and cancer patients showed that tumour-derived ctDNA exhibits a specific amount profile based on ctDNA size and significant higher ctDNA fragmentation. Metastatic colorectal patients (n = 12) showed nearly 5-fold higher mean ctDNA fragmentation than healthy individuals (n = 16).