Characterization of chromosome 1 abnormalities in malignant melanomas

Chromosome 1 abnormalities are the most commonly detected aberrations in many cancers including malignant melanomas. Specific breakpoints are reported for malignant melanomas throughout the chromosome but especially at 1p36 and at several sites throughout 1p22-q21. In addition, partial deletions and loss of heterozygosity have been found on 1p indicating the possible location of tumor suppressor genes. Here we have characterized the involvement of chromosome 1 in a series of seven malignant melanoma cell lines. Initial chromosome painting studies revealed that six of the cell lines had chromosome 1 rearrangements. Deletions involving 1p10-32, 1q11-44, and 1q25-44 were observed. The other rearrangement breakpoints included three in the 1q10-p11 region with the rest at 1p36, 1p34, 1p32, 1p31, 1p12-13, 1q21, and 1q23. The breaks at 1q10-p11 were investigated further using an alpha-satellite 1 centromere probe and yeast artificial chromosomes (YACs) from the region. Two of the 1q10-p11 breaks mapped in the centromeric region, while the others mapped to variable sites. This suggests that the role of these rearrangements in the pathogenesis of melanomas does not involve the alteration of specific oncogenes in the breakpoint region. During the YAC mapping a previously undetected, small (<1 Mbp) del(1)(p10p11) was identified. This deletion lies within minimal overlapping deleted regions reported in head and neck as well as breast carcinomas and it could therefore facilitate the isolation of a carcinoma-associated tumor suppressor gene.