LOSS OF HETEROZYGOSITY AFFECTING THE APC AND MCC GENETIC-LOCI IN PATIENTS WITH PRIMARY BREAST CARCINOMAS

Tumor suppressor genes APC and MCC were identified recently, and their chromosomal location was ascribed to chromosome 5q21. Mutations in th e APC gene give rise to familial adenomatous polyposis and occur in ma ny, perhaps even the majority, of sporadic colon cancers. Loss of hete rozygosity has been described in other human tumors such as lung and e sophageal cancers. Here we show loss of heterozygosity (LOH) in 87 pat ients with breast cancer for the APC and/or MCC loci using a polymeras e chain reaction-LOH assay. LOH affected loci in APC exons 11 and 15 i n 9 of 35 (25%) and 4 of 34 (11%) heterozygous patients, respectively. LOH at the MCC exon 10 locus occurred in 7 of 40 (17%) informative sa mples. These data suggest that allelic deletion of APC and/or MCC is p robably involved in the pathogenesis and/or progression of a subset of breast cancers.