Detection of tumor messenger RNA in the serum of patients with malignant melanoma

Serum RNases are known to be elevated in patients with cancer, Consequently , it is not clear whether human mRNA with sufficient integrity as to permit reverse transcription-PCR (RT-PCR) amplification is detectable in serum. W e examined serum from six patients with malignant melanoma for human tyrosi nase mRNA using RT-PCR. Serum from 20 normal volunteers served as controls. Tyrosinase mRNA could be demonstrated in serum from four of the six melano ma patients with detection by gel electrophoresis and confirmation by blott ing amplified product to a tyrosinase-specific probe. The serum remained ty rosinase mRNA positive, even if passed through a 0.45 mu m filter prior to RNA extraction, indicating that the mRNA was extracellular at the time of e xtraction. Tyrosinase mRNA could not be detected in any control serum (0 of 20 individuals). The presence and integrity of amplifiable RNA was confirm ed in all serum specimens (patients and controls) by RT-PCR amplification o f c-abl mRNA, Amplifiable RNA could be demonstrated regardless of whether s erum was freshly drawn or stored frozen for several years. We conclude that human mRNA can be extracted and amplified from serum, The ability to ampli fy tumor mRNA from serum may have important utility in cancer diagnostics a nd monitoring.