Določanje mutacije V600E v genu BRAF Detection of V600E mutation in BRAF gene

Abstract

Mutacija V600E predstavlja več kot 90 % vseh opisanih mutacij v genu BRAF pri različnih vrstah tumorjev. Protein, ki nastane kot produkt onkogena BRAF z mutacijo V600E (BrafV600E), sproža nenehno signaliziranje prek signalne poti RAS-RAF-MAPK, kar povzroči številnejše delitve celice in njeno maligno transformacijo. Zato ima onkogen BrafV600E pomembno vlogo pri indukciji in napredovanju tumorja ter verjetno predstavlja zgodnji dogodek v procesu maligne transformacije. Po podatkih iz literature je čezmerno izražen v različnih vrstah solidnih tumorjev, kot so melanom, metastatski rak debelega črevesa in danke, papilarni rak ščitnice, rak ledvic (RCC), hepatocelularni karcinom (HCC), velikocelični rak pljuč (NSCLC) in serozni rak jajčnikov. Na Oddelku za molekularno diagnostiko smo uvedli metodo za določanje mutacije V600E v genu BRAF. Metoda temelji na PCR-pomnoževanju in uporabi specifičnih sond. Izkazala se je kot primerna za rutinsko diagnostiko. V primerjavi z neposrednim sekveniranjem, ki velja za zlati standard, sta bili njeni občutljivost in specifičnost 100-odstotni. Zaradi velike specifičnosti je zanesljiva za ločevanje med normalnim in mutiranim genotipom BRAF in je primerna za hitro rutinsko diagnostiko.

Abstract (Eng)

The most common BRAF mutation, which accounts for more than 90% of all BRAF mutations described in different malignancies, is a glutamic acid for valin substitution at position 600 (V600E). BRAF gene carrying V600E mutation is termed BrafV600E oncogene. The product of BrafV600E is a protein which induces constitutive signaling in cells through hyperactivation of the RAS-RAF-MAPK pathway leading finally to increased cellular proliferation and malignant transformation. BrafV600E oncogene thus plays an important role in cancer induction and progression and is probably mutated early in the process of malignant transformation. According to the literature, BrafV600E oncogene is over-expressed in diverse human solid tumors: melanoma, colorectal carcinoma, papillary thyroid carcinoma, renal cell carcinoma (RCC), hepatocellular carcinoma (HCC), non-small cell lung cancer (NSCLC) and serous ovarian cancer. At the Department of Molecular Diagnostics, we introduced a method for the detection of V600E mutation in BRAF gene based on real-time PCR and on application of specific probes. The method is robust and convenient for routine diagnostics. Its sensitivity and specificity when determined in comparison to the results of direct sequencing are as high as 100%. Due to the high specificity, the method allows the discrimination between normal and mutated BRAF genotypes and is therefore suitable for fast and accurate routine diagnostics.