TY - JOUR
T1 - Circulating cell-free DNA from colorectal cancer patients may reveal high KRAS or BRAF mutation load
AU - Mouliere, Florent
AU - Messaoudi, Safia El
AU - Gongora, Celine
AU - Guedj, Anne Sophie
AU - Robert, Bruno
AU - del Rio, Maguy
AU - Molina, Franck
AU - Lamy, Pierre Jean
AU - Lopez-Crapez, Evelyne
AU - Mathonnet, Muriel
AU - Ychou, Marc
AU - Pezet, Denis
AU - Thierry, Alain R.
PY - 2013/1/1
Y1 - 2013/1/1
N2 - We used a novel method based on allele-specific quantitative polymerase chain reaction (Intplex) for the analysis of circulating cell-free DNA (ccfDNA) to compare total ccfDNA and KRAS- or BRAF-mutated ccfDNA concentrations in blood samples from mice xenografted with the human SW620 colorectal cancer (CRC) cell line and from patients with CRC. Intplex enables single-copy detection of variant alleles down to a sensitivity of ≥0.005 mutant to wild-type ratio. The proportion of mutant allele corresponding to the percentage of tumor-derived ccfDNA was elevated in xenografted mice with KRAS homozygous mutation and varied highly from 0.13% to 68.7% in samples from mutationpositive CRC patients (n = 38). Mutant ccfDNA alleles were quantified in the plasma of every patient at stages II/III and IV with a mean of 8.4% (median, 8.4%) and 21.8% (median, 12.4%), respectively. Twelve of 38 (31.6%) and 5 of 38 (13.2%) samples showed a mutation load higher than 25%and 50%, respectively. This suggests that an important part of ccfDNA may originate from tumor cells. In addition, we observed that tumor-derived (mutant) ccfDNA was more fragmented than ccfDNA from normal tissues. This observation suggests that the form of tumor-derived and normal ccfDNA could differ. Our approach revealed that allelic dilution is much less pronounced than previously stated, considerably facilitating the noninvasive molecular analysis of tumors.
AB - We used a novel method based on allele-specific quantitative polymerase chain reaction (Intplex) for the analysis of circulating cell-free DNA (ccfDNA) to compare total ccfDNA and KRAS- or BRAF-mutated ccfDNA concentrations in blood samples from mice xenografted with the human SW620 colorectal cancer (CRC) cell line and from patients with CRC. Intplex enables single-copy detection of variant alleles down to a sensitivity of ≥0.005 mutant to wild-type ratio. The proportion of mutant allele corresponding to the percentage of tumor-derived ccfDNA was elevated in xenografted mice with KRAS homozygous mutation and varied highly from 0.13% to 68.7% in samples from mutationpositive CRC patients (n = 38). Mutant ccfDNA alleles were quantified in the plasma of every patient at stages II/III and IV with a mean of 8.4% (median, 8.4%) and 21.8% (median, 12.4%), respectively. Twelve of 38 (31.6%) and 5 of 38 (13.2%) samples showed a mutation load higher than 25%and 50%, respectively. This suggests that an important part of ccfDNA may originate from tumor cells. In addition, we observed that tumor-derived (mutant) ccfDNA was more fragmented than ccfDNA from normal tissues. This observation suggests that the form of tumor-derived and normal ccfDNA could differ. Our approach revealed that allelic dilution is much less pronounced than previously stated, considerably facilitating the noninvasive molecular analysis of tumors.
UR - http://www.scopus.com/inward/record.url?scp=84878734930&partnerID=8YFLogxK
U2 - https://doi.org/10.1593/tlo.12445
DO - https://doi.org/10.1593/tlo.12445
M3 - Article
SN - 1936-5233
VL - 6
SP - 319
EP - 328
JO - Translational oncology
JF - Translational oncology
IS - 3
ER -