Oncogene expression and immunoglobulin synthesis in a North American Burkitt (NAB-2) lymphoma cell line with a 8;22 chromosome translocation.

A Burkitt's lymphoma (BL) cell line, (NAB-2) deriving from a North American patient, exhibited a 8;22 (q22;q11-12) translocation involving the c-myc gene and lambda immunoglobulin genes. In addition, NAB-2 cells have two other consistent translocations: a 1;5 (p22;q23) and a 3;7 (p25;q22), with breakpoints close to the location of N-ras, fms, and raf-1 protooncogenes, respectively. In situ hybridization with myc, N-ras, and raf-1 radiolabeled DNA probes to NAB-2 chromosomes showed that none of these genes was relocated as a result of translocation. However, by Northern blot analysis, the myc mRNA was represented by two transcripts, one approximately 2.4 kb and the other considerably larger (74 kb). The raf-1 gene transcript was also detected in NAB-2 cells; however, its size and level were similar to those seen in two other BL lines. On the other hand, the N-ras, fms, and fgr genes, which are frequently activated in BL, were not actively transcribed. NAB-2 cells also have a chromatid defect visible as an achromatic region on the short arm of chromosome 2 near the locus of the kappa immunoglobulin gene. This alteration, which is a viral modification site caused by the Epstein-Barr virus or viral products, had no influence on immunoglobulin synthesis, as NAB-2 cells concordant to the 8;22 translocation were positive for cytoplasmic and surface lambda light chains. Although NAB-2 cells exhibit several chromosomal abnormalities, only translocation, 8;22 was associated with gene alterations relevant to the neoplastic development of this malignancy.