Jp. Alao et al., Detection of tyrosinase mRNA by RT-PCR in the peripheral blood of patientswith advanced metastatic melanoma, MELANOMA RE, 9(4), 1999, pp. 395-399
Detection of melanoma cells in the peripheral blood has been facilitated by
the reverse transcriptase-polymerase chain reaction (RT-PCR), but their pr
esence is of uncertain importance in the evolution of the disease. We studi
ed the detection of melanoma cells using RT-PCR in the peripheral blood of
21 patients, four with regional lymph node metastases (American Joint Commi
ttee on Cancer [AJCC] stage III) and 17 with disseminated disease (AJCC sta
ge IV), RNA was extracted from 10 ml of heparinized blood following density
gradient centrifugation and converted into cDNA for PCR analysis. Assay se
nsitivity of 10 cells in 10(7) mononuclear cells and granulocytes obtained
from 10 ml of peripheral blood was achieved using the G361 and C32 melanoma
cell lines. Tyrosinase mRNA was not detected in control samples from healt
hy volunteers or patients with non-malignant disease. Six patients (one sta
ge III, five stage IV) tested positive for tyrosinase mRNA (28.6%); with on
e exception, all patients were receiving chemotherapy at the time of sampli
ng. Of the six positive results, three were from patients who initially tes
ted negative but were subsequently positive after a 3-4 week interval. The
low detection rates of melanoma cells in the peripheral blood of patients w
ith widely disseminated disease is consistent with recent reports and corre
lates poorly with the clinical stage of melanoma. This may be partly explai
ned by the clinically observed intermittent and random evolution of melanom
a metastases. (C) 1999 Lippincott Williams & Wilkins.