Tyrosinase mRNA levels in the blood of uveal melanoma patients: correlation with the number of circulating tumor cells and tumor progression.
We measured tyrosinase mRNA levels by real-time quantitative reverse transcription-PCR (qRT-PCR), in the blood of patients with uveal melanoma. Results were correlated with clinical data and, in a subgroup of patients, with the number of circulating tumor cells (CTC) assessed using isolation by size of epithelial tumor cells (ISET). Forty-one patients with uveal melanoma were longitudinally investigated over a period of 5 years. The standard curve of the qRT-PCR method used melanoma cell line SK-MEL-28, added to the blood of normal donors and it was calibrated on a synthetic RNA standard (1 SK-MEL-28 cell corresponding to 18 tyrosinase mRNA copies) to improve the procedural standardization to facilitate the comparison of data collected at different laboratories. Increased tyrosinase mRNA levels were found in at least one of the blood samples in 20 of 41 (49%) uveal melanoma patients (median 0.8 SK-MEL-28 cell equivalents/ml blood; range 0.1-14.4). A significant correlation was found between mRNA tyrosinase levels and tumor dimension (P<0.01), disease-free and overall survival (P<0.05). CTC were isolated by ISET in five of 16 patients (5.8, 2.33, 2.00, 1.25, and 0.75 CTC/ml of blood) and the corresponding tyrosinase mRNA levels were 2.13, 1.37, 0.83, 0.58, and 0.35 SK-MEL-28 cell equivalents/ml of blood. Tyrosinase was undetectable in 11 ISET-negative patients. Tyrosinase assay by qRT-PCR is a noninvasive method for the detection of tumor progression in uveal melanoma patients. The mRNA tyrosinase levels can be taken as an indirect parameter correlated to the number of CTC isolated from blood by ISET.
Pinzani
Pamela
P
Department of Clinical Physiopathology, Centre of Experimental and Clinical Oncology, University of Florence, Florence, Italy. p.pinzani@dfc.unifi.it
Mazzini
Cinzia
C
Salvianti
Francesca
F
Massi
Daniela
D
Grifoni
Raffaella
R
Paoletti
Costanza
C
Ucci
Francesca
F
Molinara
Elena
E
Orlando
Claudio
C
Pazzagli
Mario
M
Neri
Bruno
B
D000368:Aged; D000369:Aged, 80 and over; D045744:Cell Line, Tumor; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D015870:Gene Expression; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008545:Melanoma / Q000097:blood / Q000235:genetics* / Q000473:pathology; D008875:Middle Aged; D014442:Monophenol Monooxygenase / Q000097:blood / Q000235:genetics*; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D012333:RNA, Messenger / Q000097:blood* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014604:Uveal Neoplasms / Q000097:blood / Q000235:genetics* / Q000473:pathology
D012333:RNA, Messenger; D014442:Monophenol Monooxygenase