Cytogenetic and molecular analysis of 6q deletions in Burkitt's lymphoma cell lines

Although abnormalities of chromosome 6 have frequently been observed in Burkitt's lymphoma (BL), they have so far not been defined by modern cytogenetic and molecular methods. By a combination of high-resolution chromosome banding, fluorescence in situ hybridization (FISH), and loss of heterozygosity (LOH) analysis, we have examined the nature of aberrations affecting chromosome 6 in 7 previously established BL cell lines. All cell lines exhibited the characteristic translocations associated with BL; 5 had t(8;14)(q24;q32) and 2 had t(8;22)(q24;q11). Three cell lines had deletions of 6q; 3 others had rearrangements affecting 6q, whereas one cell line had apparently normal chromosomes 6. FISH analysis of the three deletions established that they were interstitial. LOH analysis with probes mapped to the 6q26-27 region confirmed the sub-telomeric interstitial deletion in cell line BL-108, which had a del(6)(q23q27). All informative loci mapped to 6q26-27 (5/7) were deleted in BL-74, which had no apparent cytogenetic abnormality in chromosome 6, thus documenting a sub-microscopic deletion. These data define the cytogenetic and molecular limits of 6q deletions in BL and are consistent with our previous demonstration of LOH analysis of the site of a candidate tumor suppressor gene in the 6q25-27 region.