The aim of this study was to analyze
microphthalmia-associated transcription factor (MITF) as a marker for the detection of circulating
melanoma cells, determine its prognostic value in
melanoma patients, and compare it with
tyrosinase. Blood samples from 201
melanoma patients in all stages of the disease and 40 healthy volunteers were analyzed.
RNA was isolated from mononuclear cell fraction of the blood and assayed by reverse transcription-PCR for the expression of MITF and
tyrosinase. All samples from healthy volunteers were negative for both MITF and
tyrosinase. Out of 201 blood samples from
melanoma patients 32 were positive for MITF, 20 for
tyrosinase, and four for both MITF and
tyrosinase. Analysis of MITF as an additional marker to
tyrosinase allowed for detection of circulating
melanoma cells in a larger number of
melanoma patients in comparison to
tyrosinase analysis alone (48 vs. 20 positive). A positive value of MITF was associated with shorter progression-free (P=0.005) and overall survival (P=0.042). A positive value of
tyrosinase was associated with shorter overall survival (P=0.012), whereas there was no significant association between the value of
tyrosinase and progression-free survival. The value of MITF was selected with multivariate analysis as the independent prognostic factor for progression-free survival, whereas the only independent prognostic factor for overall survival was the stage of disease. This study has shown that MITF is a specific marker for detection of circulating
melanoma cells that has a prognostic value in
melanoma patients. Determination of MITF in addition to
tyrosinase improved the detection of circulating
melanoma cells in
melanoma patients.