Gj. Walker et al., REFINED LOCALIZATION OF THE MELANOMA (MLM) GENE ON CHROMOSOME 9P BY ANALYSIS OF ALLELIC DELETIONS, Oncogene, 9(3), 1994, pp. 819-824
Various lines of evidence including linkage analysis, frequent homozyg
ous and heterozygous deletions in melanoma DNAs, and the finding of a
patient with multiple primary melanomas who harbours a 5p/9p transloca
tion involving loss of several 9p markers, have indicated that the 9p2
2-p13 region harbours a gene important for the development of melanoma
(MLM). We have used eight short tandem repeat polymorphism (STRP) mar
kers mapping to this region to look for allelic losses in DNA from mel
anoma biopsies and cell lines. Heterozygous losses were found in 8/14
(57%) fresh melanoma biopsy DNAs with the smallest region of overlap (
SRO) being between IFNA and D9S169. In addition, when DNA from 30 mela
noma cell lines was studied, four cell lines (13%) were found to be ho
mozygously deleted for various 9p markers. Two of these cell lines def
ine the borders of overlapping homozygous deletions within a 4cM regio
n of 9p21 between IFNA and D9S171. Moreover, a further 14 melanoma cel
l lines were hemizygous for the IFNA/ D9S171/D9S126 region. These data
support the hypothesis that the MLM gene acts as a tumour suppressor,
and provide a refinement of its localization on 9P.