Binding of transcription factor sp1 to exon-1 of C-myc is altered in burkitts-lymphoma.

In Burkitt's lymphoma (BL) a consistent chromosomal translocation involving the c-myc proto-oncogene locus on chromosome 8 and one of the immunoglobulin loci located on chromosomes 14, 22 or 2 results in the aberrant expression of c-myc. In six out of ten published BL sequences the translocated c-myc gene contains mutations and/or deletions in an Spl site in the first exon. We show by competition gel mobility shift assays and association constant comparison that the binding of Spl to this site is altered in four of these clones. The affinity of Spl for this site is increased 5-10 fold in Burkitt's lymphoma BL22 and decreased approximately 5 fold in BL2. Mutations at this site in cell lines Raji and Daudi also show a decrease in Sp1 binding when compared with the wild type sequence.