Mutational profile of KRAS-positive colorectal cancer

Aim: to study the features of the molecular genetic profile of KRAS-positive colorectal cancer (CRC). Material and Methods. The study included 42 patients diagnosed with colorectal cancer. The KRAS gene mutation was detected in tumor tissue of these patients by real-time PCR. Using the next generation sequencing technology (NGS) on the Illumina platform, the genes involved in the molecular pathogenesis of colorectal cancer, namely KRAS, BRAF, NRAS, APC, TP53, SMAD2, SMAD4, FBXW7, PIK3CA, CTNNB1, TCF7L2, MLH1, MSH2, MSH3, MSH6, ATM, TGF-BR2, AKT1, CDC27, CASP8, MAP2K4, DCC, DMD, MAP7, ERBB2, P3H3, MIER3, CADM1, FLT4, PTPN12, PIK3R1, and EP300 were analyzed. Sample preparation of libraries from isolated DNA was carried out using commercial kits GeneRead DNASeq Targeted Panel v2 Human Colorectal Cancer (Qiagen, USA); NEBNext Ultra DNA library Prep kit for Illumina and NEBNext Multiplex Oligos for Illumina (New England BioLabs). Results. In 36 patients with KRAS-positive tumors, changes were observed in 13 genes involved in the molecular pathogenesis of colorectal cancer. A total of 82 somatic variants were identified. Moreover, 9 patients additionally had one mutation each, 17 patients had 2 mutations each, 7 patients had 3 mutations each, and 3 patients had 4 mutations each. Combination of three mutations in key genes involved in the pathogenesis of colorectal cancer (KRAS, APC и TP53) was detected in 15 (36 %) patients. Combination of two mutations in the KRAS and APC genes was detected in 10 (23.8 %) patients, and in the KRAS and TP53 genes - in 8 (19.1 %) patients. The largest number of somatic mutations was found in the APC (59.5 %) and TP53 (54.7 %) genes. It was hown that a combination of three mutations in key genes was the most unfavorable prognosis factor and indicated a higher aggressiveness of the tumor process. Conclusion. The information obtained using the NGS method on the mutational status of a KRAS-positive tumor in patients with colorectal cancer allows for personalized treatment as well as predicting the outcome.