GENETIC INSTABILITY LEADS TO LOSS OF BOTH P53 ALLELES IN A HUMAN GLIOBLASTOMA

Little is known about the relationship between genetic recombination m echanisms and loss of tumour suppressor genes in solid tumours. Here, we demonstrate deletion and truncation of both p53 alleles in a primar y human glioblastoma and a derived cell line as the combined result of a t(17;20) reciprocal translocation and a 1.1 Mbp genomic deletion on chromosome 17p, starting in intron 4 of the p53 gene and ending at th e telomeric CA-repeat marker D17S960. These results (i) suggest that g enetic instability can lead to loss of tumour suppressor function in s olid cancers, (ii) provide mapping of one such recombination event at the nucleotide level, and (iii) establish the orientation of the p53 g ene on chromosome 17 as: centromere 5'-3'-telomere.