HRad17, a human homologue of the Schizosaccharomyces pombe checkpoint generad17, is overexpressed in colon carcinoma

Using the palindromic PCR-cDNA display method, we have cloned a novel gene overexpressed by human colon carcinoma relative to normal colon. Among norm al tissues examined, only testis expresses it at a high level. Sequence ana lysis revealed its extensive homology with checkpoint genes rad17 of Schizo saccharomyces pombe and RAD24 of Saccharomyces cerevisiae. This novel gene designated as hRad17 is localized to chromosome 5q12,13.1, a region known t o be deleted in a variety of human cancers. Promoter region and one pseudog ene of hRad17 have been identified. Whereas the increased expression of hRa d17 by human colon carcinomas may be related to the known resistance of the se cells to DNA-damaging agents during therapy, the deletion of hRad17 in a variety of cancers may predispose them to increased rate of mutation and h eightened sensitivity to DNA-damaging agents, including radiation and anti- cancer drugs.