Whole-genome sequencing of MNNG-treated normal and MLH1-deficient colorectal patient-derived organoids to assess mutation accumulation

This experiment was designed to evaluate the impact of mismatch repair deficiency on mutation accumulation following alkylating DNA damage. Normal and MLH1-deficient colorectal patient-derived organoids were exposed to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for 24 hours and subsequently cultured without treatment for 48 hours to allow recovery and fixation of DNA damage–induced mutations. Whole-genome sequencing was performed on both treated and untreated organoids to quantify mutation burden and characterize mutational signatures associated with mismatch repair deficiency. The resulting BAM files were used to compare base substitution patterns and indel profiles between normal and MLH1-deficient organoids.