Construction of a high-resolution physical map of the approximate 1-Mb region of human chromosome 7q31.1-q31.2 harboring a putative tumor suppressor gene.

Reports of frequent loss of heterozygosity (LOH) of markers on human chromosome 7q in malignant myeloid disorders as well as breast, prostate, ovarian, colon, head and neck, gastric, pancreatic, and renal cell carcinomas suggest the presence of a tumor suppressor gene (TSG). Functional assays have demonstrated that the introduction of an intact copy of human chromosome 7 (hchr7) can restore senescence to immortalized human fibroblast cell lines having LOH of markers within 7q31-q32 and can inhibit the tumorigenic phenotype of a murine squamous cell carcinoma cell line. To facilitate the cloning of the putative TSG, we have constructed a high-resolution physical map of this region of hchr7, specifically that encompassing the markers D7S522 and D7S677 within 7q31.1-q31.2. By using a lower resolution yeast artificial chromosome-based map as a starting framework, we established complete clone coverage of the implicated critical region in bacterial-artificial chromosomes (BACs) and P1-derived artificial chromosomes (PACs). The resulting BAC/PAC-based contig map has provided suitable clones for the systematic sequencing of the entire interval. In addition, we have already identified 29 clusters of overlapping expressed-sequence tags (ESTs) and 4 known genes contained within these clones. Together, the physical map reported here coupled with the evolving sequence and gene maps should hasten the identification of the putative TSG residing within this region of hchr7.