Bcl6

BCL6 is a nuclear protein (BCL is the acronym for"B-cell lymphoma") that physiologically functions as a "repressor of transcription". Target genes include the p53 gene, which causes cell cycle arrest or cell death when DNA is damaged.

Inhibitors of histone deacetylases allow the attachment of acetyl groups; as a result, the protein BCL6 loses its repressor function; p53 can be activated. Tumor cells can go into apoptosis (see also BCL2).

Mantle cell lymphoma shows the translocation t(11;14)(q13;q32) with an IGH-cyclin D1 (CCND1) rearrangement. However, variant CCND1 translocations can also be observed. Usually other aberrations are found. Complex karyotypes are common.

In MALT lymphomas (extranodal marginal zone lymphomas of mucosa-associated tissues), a translocation t(11;18)(q21;q21) is often seen. However, genetic alterations vary widely, and other IGH rearrangements or 6q deletions are possible.

In follicular lymphoma, a t(14;18)(q32;q21) translocation with a BCL-2 rearrangement is found in the majority of cases; in addition, other cytogenetic aberrations are usually found.

Diffuse large B-cell lymphomas (DLBCL) often show rearrangements of BCL6, MYC or BCL2. However, these do not show specificity for a particular entity, but can also occur in other lymphoid entities.

No specific chromosomal aberrations are found in lymphoplasmocytic lymphoma. They are also less frequent than in other lymphoma entities.

1. Hallermann C et al (2004) Molecular cytogenetic analysis of chromosomal breakpoints in the IGH, MYC, BCL6 and MALT1-gene loci in primary cutaneous B-cell-lymphomas.J Invest Dermatol 123: 213-219