Expression of Melan-A/MART-1 in primary melanoma cell cultures has prognostic implication in metastatic melanoma patients

Abstract

The lack of melanoma-associated antigen (MAA) expression has been associated with the reduced overall survival in melanoma patients. In order to investigate whether the MAA expression detected on cell cultures established from melanoma patients might relate to the overall survival in these patients, we screened primary cell cultures derived from 37 melanoma metastases for the expression of five known MAA: Melan-A, tyrosinase, gp-100, MAGE-1 and MAGE-3 by polymerase chain reaction (PCR) and fluorescence-activated cell sorting (FACS). MAA expression detected by PCR was found at a high percentage in evaluated melanoma cell lines: 25 of 28 (89%) were positive for Melan-A, 22 of 28 (79%) were positive for tyrosinase, 26 of 28 (93%) were positive for gp-100, and 18 of 28 (64%) were positive for MAGE-3 expression. Using the FACS method the percentage of MAA-positive cell lines was much lower: 14 of 31 (45%) cell lines were positive for Melan-A, eight of 31 (26%) were positive for tyrosinase, 13 of 31 (42%) were positive for gp-100, six of 31 (19%) were positive for MAGE-1, and 14 of 31 (45%) were positive for MAGE-3 expression. Kaplan-Meier survival analysis demonstrated that the patients whose cell lines were positive for Melan-A expression by PCR had significantly longer overall survival time as Melan-A PCR-negative cases (P=0.0038). This could not be shown for any of the markers tested by FACS. Our results suggest that the expression of Melan-A/MART-1 in patient-derived cell cultures may help to identify a group of melanoma patients with prolonged survival.