Simultaneous analysis of tyrosinase mRNA and markers of tyrosinase activity in the blood of patients with metastatic melanoma

Abstract

Determination of blood tyrosinase mRNA by RT-PCR and markers of tyrosinase activity ( l-DOPA/ l-tyrosine ratio) by HPLC have been proposed as biological tools for the detection of metastases in melanoma patients. We prospectively evaluated their significance and clinical value in a group of 30 stage III ( n=10) and IV ( n=20) melanoma patients and one with melanosis of Dubreuilh. l-DOPA/ l-tyrosine ratio was elevated in 30% of stage III, 41% of stage IV patients (range: 7.5–261.0×10 5) and in melanosis of Dubreuilh (184.8) (reference values: 6–16×10 5). One stage III and four stage IV melanoma patients were positive for tyrosinase mRNA. In stage IV patients, tyrosinase mRNA positivity was associated with disease progression ( P<0.01). The presence of tyrosinase mRNA in blood is more related to clinical status than level of melanin precursors, which probably reflects tumor burden.