Critical elements of the immunoglobulin heavy chain gene enhancers for deregulated expression of bcl-2.

Translocation of the bcl-2 gene to the immunoglobulin heavy chain gene is the most common alteration in follicular lymphoma. The result is the deregulated expression of bcl-2 and increased resistance to cell death. Regulation of the immunoglobulin heavy chain gene is controlled in part by four DNase I-hypersensitive regions located 3' of the gene.

NF-kappaB activates Bcl-2 expression in t(14;18) lymphoma cells.

The t(14;18) translocation, which is characteristic of follicular lymphoma, results in the overexpression of the bcl-2 gene dependent upon regulatory elements within the bcl-2 5' flanking region and the immunoglobulin heavy chain gene enhancers. Conflicting evidence exists on the effects of NF-kappaB expression on Bcl-2 levels in different cell types. Lymphoma cells with the t(14;18) translocation show high levels of nuclear NF-kappaB proteins.