Non-invasive quantification of cell-free DNA mutations in plasma during lung tumor progression in mice

Testing carcinogenicity caused by chemicals requires a noninvasive tool that can be used before autopsy because autopsy takes a long time. We investigated whether non-small cell lung cancer related gene mutations could be detected in cell-free DNA in plasma by Insight OncoTM next-generation sequencing, which is a fast and sensitive method. Adenoma formation was confirmed in urethane-injected 17-week-old mice. Seven single nucleotide polymorphisms, such as Cdkn2a and Vegfa, were selected. Mutant-enriched Insight OncoTM NGS and normal NGS were performed on genomic DNA. The results demonstrate that Insight OncoTM NGS detected Cdkn2a and Vegfa SNPs at 0.05%. The sensitivity of Insight OncoTM NGS was twice higher than that of normal NGS. In this analysis, the Cdkn2a gene mutation was detected not only in two genomic DNA samples of lung tissue from the 11th week of urethane injection but also in two cell-free DNA samples. In addition, the Vegfa gene mutation was detected not only in three genomic DNA samples of lung tissue of injection but also in one cell-free DNA sample, showing 33% concordance. Our results confirm that Insight OncoTM NGS is a rapid and sensitive detection method that enables lung cancer-associated gene mutations to be detected in cell-free DNA before the end of the carcinogenicity test.