Xq27-28 deletions in prostate carcinoma

Linkage studies have implicated a prostate cancer susceptibility locus at Xq27-28 (termed HPCX), estimated to be responsible for approximately 16% of hereditary prostate cancer cases. To date, this region has not been investigated in sporadic disease. In this study, we examined tumor DNA samples prepared from patients with sporadic prostate cancer, prostate cancer cell lines, and prostate cancer xenografts for evidence of genomic alterations within the Xq27-28 region. To facilitate the detection of nullizygosity, we examined a unique series of highly tumor-enriched DNA samples prepared from men with multi-sampled metastatic prostate cancer, as well as a series of prostate cancer xenografts and cell lines. PCR amplification of carcinoma and normal DNA templates was performed for II loci spanning an Xq27-28 interval of ∼16 cM. Among 19 patients studied, somatic deletions in this region were found in two cases. Within these two cases, each independent metastatic tumor sample available from an individual (n = 4 sites and 8 sites, respectively) showed the same reduction to nullizygosity, suggesting a pre-metastatic origin for the deletion events in both. Mapping of the deletion boundaries with eight additional sets of markers indicated that both deletions had breakpoints within an ∼500- to 800-kb interval containing FMRI; however, the deletions were non-overlapping. The lack of a common region of deletion suggests one of three possibilities: (1) that these two deletions are unrelated, (2) that the deletions affect the opposite ends of an as yet unknown gene, or (3) that each deletion has inactivated a single copy of an unknown gene arranged in cis in the region of interest. These data clearly indicate that deletions do occur within the HPCX locus in a subset of sporadic prostate cancers and therefore raises the possibility that the gene at this locus may prove to play a role in sporadic disease.