Identification of a novel microsatellite marker tightly linked to the KAI-1 gene for predicting prostate cancer progression

Background: We have mapped the human prostate-specific membrane antigen (PS M) gene to the chromosome 11p11.2 region at 62.5 cM, a region which also co ntains the prostatic cancer metastasis suppressor gene KAI-1. The genetic m arker D11S1344 has been utilised for loss of heterozygosity (LOH) studies o n the KAI-1 gene in a large series of prostate cancer specimens. The result s were negative and it was concluded that deletions of the KAI-7 gene were not involved in the development of the metastatic phenotype in these tumour s. One possible explanation for this result could be that D11S1344 is not s ufficiently tightly linked to the KAI-7 gene to detect small deletions. Objective: To attempt to identify a genetic marker more tightly linked to t he KAI-1 gene than D11S1344. Methods: Yeast artificial chromosome (YAC) clones containing the KAI-7 gene and the neighbouring marker D11S1344 were analysed by the fluorescent in s itu hybridisation technique. The human genomic inserts in these novel clone s were sized by pulsed field gel electrophoresis. For more accurate mapping of the KAI-1 gene, YACs containing it were screened for polymorphic marker s (including D11S1344) from the 11p11.2 region. Results: The novel VAC clones localised exclusively to the 11p11.2 region, with single hybridisation signals compared to the dual signals consistently obtained with nearby PSM-containing YACs. All the KAI-7 clones found had s mall inserts (<300 kb). The only known microsatellite which gave amplificat ion products with these YACs was D11S986 which has been mapped at 61.3 cM o n human chromosome 11. Conclusions: We have precisely localised KAI-1 at 61.3 cM on human chromoso me 11. This is some 1.2 cM away from the previously utilised LOH microsatel lite marker, D11S1344. We suggest that the very tightly linked microsatelli te D11S986 may be a more accurate marker to assess LOH of the KAI-1 gene an d thus predict progression of prostate cancer. The region of genetic duplic ation around the PSM gene does not extend as far distally on 11p as KAI-1. Copyright (C) 2000 S. Karger AG, Basel.