DELETION MAPPING IN BREAST-TUMOR CELL-LINES POINTS TO 2 DISTINCT TUMOR-SUPPRESSOR GENES IN THE 1P32-PTER REGION, ONE OF DELETED REGIONS (1P36.2) BEING LOCATED WITHIN THE CONSENSUS REGION OF LOH IN NEUROBLASTOMA

Cytogenetic and molecular studies have suggested that the 1p32-pter re gion might contain tumor-suppressor genes involved in the pathogenesis of breast cancer and other malignancies. Isolation of these genes cou ld be facilitated by studying tumor cell lines with well-defined delet ed regions. We examined deletions on chromosome Ip in 10 breast tumor cell lines, using a panel of 36 polymorphic markers located mainly in the 1p32-pter region, that comprised microsatellite, restriction fragm ent length polymorphism (RFLP) and variable number of tandem repeat (V NTR) markers. Two regions of interest were clearly identified: one (27 cM apart) is located at 1p32-p34 and reduces the smallest common dele ted region (SCDR) to 8 cM if recorded the previous Ip LOH studies from primary breast tumors and the other (15 cM) is located at 1p36.2, wit hin the 'consensus region of LOH' in neuroblastoma. These results show that the study of cell lines can refine SCDRs identified in primary t umors and can be used to identify putative homozygous deletions and to study the expression and structural alterations of candidate tumor-su ppressor genes in these deleted regions.