Detection of circulating melanoma cells by RT-PCR amplification of three different melanocyte-specific mRNAs in a mouse model

Three different melanocyte-specific mRNAs are studied as potential markers for circulating melanoma cells in the serum of mice inoculated subcutaneous ly with B16F10 melanoma tells. These three mRNAs encode tyrosinase, tyrosin ase related protein-2 (TRP-2) and Pmel17, proteins that are essential for t he synthesis of melanin and are expressed specifically in melanocytes. We u sed reverse-transcription polymerase chain reaction (RT-PCR) to detect thes e three different melanocyte-specific mRNAs in the sera of B16F10 bearing m ice, Since melanocytes would not normally be present in the blood, the dete ction of those transcripts should indicate the presence of circulating mela noma cells, RT-PCR detection of all three mRNAs was highly sensitive and sp ecific. Our in vitro studies show that as few as 10 melanoma cells can be d etected in 125 mu l blood and that in vivo, melanoma cells fan be detected in blood samples from B16F10 melanoma bearing mice. Of these three mRNAs, P mel17 mRNA is the most sensitive marker for detecting circulating melanoma cells compared with tyrosinase mRNA and TRP-2 mRNA, Moreover, this mouse mo del might be useful for basic research of malignant melanoma patients with haematogenous metastasis.