Melanoma-associated markers expression in blood: MUC-18 is associated with advanced stages in melanoma patients

Multimarker reverse transcriptase-polymerase chain reaction (RT-PCR) was originally reported to reveal melanoma-associated mRNAs (MAMs) in melanoma cells but not in the peripheral blood of healthy individuals.

To evaluate the expression of MAMs in the peripheral blood of melanoma patients at different American Joint Committee on Cancer (AJCC) stages, and to correlate their presence with early and/or advanced stages of the disease.

One hundred blood samples of melanoma patients (AJCC I-IV) were analysed using multimarker RT-PCR to assess the co-expression of Tyr-OH, MART-1, MAGE-3, MUC-18/MCAM and p97. Patients were stratified into two disease categories: early and advanced stages. The former includes in situ and melanoma stages AJCC I-II, the latter AJCC III-IV. chi(2) and Fisher's exact tests were used to statistically evaluate the association between each MAM and disease categories. The recognized significant associations were subsequently resubmitted to univariate logistic regression. Furthermore, sensitivity and specificity were established.

At least one MAM could be detected in 24% of our series. Tyr-OH was the most common marker (14%), followed by MUC-18 (12%), MART-1 (5%), MAGE-3 (4%) and p97 (3%). No significant association among Tyr-OH, MART-1, MAGE-3, p97 and disease stages were evidenced. Only MUC-18 was statistically associated (P < 0.009) with advanced stages alone or co-expressed with other MAMs. According to logistic regression univariate analysis, MUC-18 increases the probability (odds ratio: 33) being in advanced stages and the incidence of recurrences (95% CI 2.9-374).

MUC-18 RT-PCR assay could be proposed as an adjunctive molecular method in the management of melanoma patients and is useful in the monitoring of study protocols.