Microphthalmia-associated transcription factor and tyrosinase as markers of melanoma cells in blood of patients with melanoma

Abstract

Aim: To investigate whether analysis of microphthalmia-associated transcription factor (MITF) as an additional marker to tyrosinase in melanoma patients can improve the detection of circulating melanoma cells by reverse-transcription-polymerase chain reaction (RT-PCR).

Methods: Blood samples were taken from 33 patients with metastatic melanoma. RNA was isolated from mononuclear cell fraction of the blood and reversely transcribed into the complementary DNA (cDNA). The cDNA was assayed by PCR for the expression of tyrosinase and MITF. Peripheral blood samples from 15 healthy subjects were used as controls.

Results: The threshold for detection of both tyrosinase and MITF was set low enough to detect 50 melanoma cells in 10 mL of healthy volunteer blood in the relative ratio of one melanoma cell in 0.82 x 106 peripheral blood leukocytes. Out of 33 blood samples from metastatic melanoma patients, 5 were positive for both tyrosinase and MITF, 7 for tyrosinase only, and 5 for MITF only. All samples from healthy volunteers were negative for both tyrosinase and MITF.

Conclusion: Determination of MITF marker in addition to tyrosinase improved the detection of circulating melanoma cells in patients with metastatic melanoma.