DETECTION OF K-RAS MUTATION IN CELL FREE DNA FROM PLASMA OF CRC PATIENTS

Colorectal cancer is the third most common cancer diagnosed worldwide and the fourth most common cause of cancer death. With the development of new sensitive molecular techniques, circulating cell free tumor DNA containing mutations can be identified in the plasma of cancer patients. Cell-free circulating DNA in plasma may serve as a biomarker for malignant tumor detection and follow up in patients with a variety of solid tumors including colorectal cancer. In healthy patients, DNA is normally released from an apoptotic source which generates small fragments of cell free DNA, whereas cancer patients have cell free circulating DNA that originated from necrosis, autophagy, or mitotic catastrophe. The aim of this study was to detect K-ras mutations in cell free DNA extracted from the plasma of patients with CRC. K-ras is part of the RAS family of proto-oncogenes and encodes a G-protein with a critical role in cell signaling pathways. Activating mutations lead to increased signaling through multiple downstream growth promoting pathways. The K-ras oncogene is mutated in approximately 35%-45% of colorectal cancers. To achieve this objective, Tumor and plasma DNA were extracted from 20 patients with colorectal cancer. K-ras alterations were detected using a PCR point mutation and sequencing eventually use HRM technique to validate the results. Half of patients had a codon 12 K-ras mutation. Mutant DNA was not detected in the plasma specimens of 10 patients whose tumors tested negative for K-ras mutations or in healthy control subjects. K-ras mutations can be detected in cf DNA extracted from the specimens of patients with CRC. If these results are confirmed in larger studies, genetic analysis of cell free DNA may have clinical applications in the future.