Abstract
Abstract: :
Purpose:Loss of heterozygosity (LOH) of the chromosomal arm 3p is the most common genetic alteration detected in uveal melanomas. Using microsatellite analysis, we recently performed a fine mapping of the chromosomal arm 3p. Three shared regions of allelic loss were identified on chromosomal region 3p24-25, 3p21 and 3p14. In the present study we have further mapped the 10 Mb region located on chromosome 3p24-25, between microsatellite markers D3S1597 and D3S1286. Methods:The 21 uveal melanomas previously analysed for LOH on chromosomal arm 3p were tested for allelic loss in the 3p24-25 region using 10 additional markers. DNA was isolated from microdissected paraffin sections and amplified by PCR using microsatellite markers chosen to span the region between markers D3S1597 and D3S1286 at approximately 1 cM intervals. The minimal region of LOH identified was investigated further with analysis of single nucleotide polymorphisms (SNP) as markers. PCR amplification of extracted DNA was followed by primer extension using fluorescent primers specific for each SNP analysed. The analysis was then performed using the MegaBACE 1000 and SNP Profiler software (Molecular Dynamics). Results:LOH for at least one of the microsatellite markers was found in 6 of 21 uveal melanomas (29%). Five of those 6 tumors showed a 4 Mb minimal region of deletion between microsatellite markers D3S656 and D3S1286. Interestingly, the remaining tumor showed a putative area of homozygous deletion in the same region. A high resolution mapping of this 4 Mb area is currently underway using the SNP analysis. Conclusion:We have identified a minimal area of allelic loss in uveal melanoma on chromosomal arm 3p24 that includes several genes, including putative tumor suppressor genes. Inactivation of one or more of these genes may be important in the development of uveal melanoma.
Keywords: 464 melanoma • 476 molecular biology