Search

Allelic variations of the melanocortin-1 receptor (MC1R) gene have been linked to red hair and sun-sensitive skin types and may play a role in the susceptibility to develop cutaneous malignant melanoma (CMM). To define the role of MC1R gene in uveal melanoma, a case control study was performed, in which the presence of MC1R gene variations in uveal melanoma patients was compared with that of healthy controls.MC1R gene variants were analyzed in 162 uveal melanoma patients and 255 healthy controls. After genomic DNA was isolated from venous blood, the MC1R gene was amplified by polymerase chain reaction (PCR) and examined for the presence of variants by single-strand conformation polymorphism (SSCP) analysis. Participants were asked to complete a questionnaire regarding skin type, eye color, and hair color.No disparity was found between the distribution of the MC1R gene variants in both groups. Furthermore, no associations between MC1R genotype and pigment phenotype were found. In contrast to CMM, uveal melanoma patients did not show specific MC1R gene variants. Compared with controls, most uveal melanoma patients had blue eyes (65%, P = 0.060) and skin type III (56%); however, in the uveal melanoma group the presence of dark blond hair was significantly elevated (46%, P = 0.030). These findings are in contrast with studies on CMM, where most patients have skin type II and red/fair hair.These data suggest that MC1R variants do not play a role in the susceptibility to develop uveal melanoma. Furthermore, most uveal melanoma patients share phenotypic characteristics that differ from findings in CMM patients.

Tumors often display unrestricted cell cycling attributable to a dysfunctional G(1)-S checkpoint. One of the mechanisms leading to such a defect is the inactivation of the cyclin-dependent kinase inhibitor p16(INK4a). Although inactivation of p16(INK4a) is observed in a wide range of tumors, including cutaneous melanoma, genetic alteration of p16(INK4a) is reportedly uncommon in uveal melanoma. Here we show that the p16(INK4a) promoter is hypermethylated in 6 of 12 uveal melanoma cell lines and in 7 of 22 primary uveal melanomas analyzed. Five of seven patients with a methylated primary tumor died of metastatic disease compared with 2 of 15 patients with a nonmethylated primary tumor. We also show that all uveal melanoma cell lines with a hypermethylated p16(INK4a) promoter have lost p16(INK4a) expression but have maintained the expression of p14(ARF). Treatment of uveal melanoma cell lines with 5-aza-2'-deoxycytidine results in demethylation of p16(INK4a) and in reexpression of p16(INK4a) mRNA, which is maintained upon withdrawal of the 5-aza-2'-deoxycytidine. In conclusion, p16(INK4a) promoter methylation appears to be a common event in uveal melanoma and is accompanied by the loss of p16(INK4a) expression.

Familial atypical multiple mole-melanoma (FAMMM) syndrome is characterized by the familial occurrence of malignant melanoma of the skin in combination with multiple atypical precursor naevi. In the present study we performed linkage analysis in seven Dutch FAMMM families to define the relationship between the ultimate phenotype melanoma and the postulated precursors, atypical (dysplastic) naevi. Various models were defined, varying from melanoma only to various combinations of melanoma and atypical naevi, reflecting the FAMMM phenotype. Using 124 microsatellite markers spread across all autosomes, hints for linkage were obtained between several chromosome 9p markers and a melanoma locus (D9S171; odds for linkage, 275:1). In a model including melanoma and a florid manifestation of atypical naevi a considerably higher lod score was obtained with D9S171 (odds for linkage, 4365:1); models including milder manifestations yielded less support. We conclude that, also in the Dutch FAMMM families, a melanoma gene is located on the short arm of chromosome 9 and that multiple atypical naevi, at least in certain cases, seems to be a component of the FAMMM phenotype.