FREQUENCY OF NRAS GENE MUTATIONS AMONG THE PATIENTS WITH WILD TYPE KRAS COLORECTAL CANCERS IN SOUTHERN-EASTERN SERBIA

Jugovic D., P. Vasiljevic, Lj. Brankovic, R. Milicevic, V. Madic, M. Vukelic-Nikolic (2021). Frequency of NRAS gene mutations among the patients with wild type Kras colorectal cancers in southern-eastern Serbia. -Genetika, Vol 53, No.3, 985-996. Colorectal cancer (CRC) is the fourth most frequently diagnosed cancer worldwide, with 1.1 million cases in 2018. KRAS and NRAS genes are some of the most important molecular biomarkers of CRC. That is why, before starting treatment with anti-epidermal growth factor therapy, patients with CRC are tested for the mutation in those genes. The aim of this study was to evaluate the frequency of NRAS gene mutations among patients with wild type (wt) KRAS colorectal cancer in Southern-Eastern Serbia. Formalin-fixed paraffin-embedded sample tissues of 55 CRC patients with wt KRAS were investigated during the period from 2017 to 2019. Following DNA extraction, the samples were analysed for common mutations of exons 2 (codons 12 and 13), 3 (codon 61), and 4 (codon 117 and 146) of the NRAS gene using two diagnostic analyses: real-time PCR and NRAS StripAssay. Among these 55 cases of colorectal cancer with wt KRAS, there were 3 (5.4%) cases with mutant NRAS. One of these patients had mutations in codon 13 and the other two in codon 61. No mutation in codon 12 was found. Moreover, two out of three patients were men with CRC in the T3 stage of tumour infiltration and liver metastases. The third one was a woman with CRC in the T3 stage of tumour infiltration and lung metastases. Our results showed that the frequency of NRAS mutation in CRC is low, which is similar to other studies covering different geographic areas of the world.