A chromosomal translocation (Tx) that interrupts the transcription of either c-Myc or Pvt 1 is the principal lesion in many B cell malignancies including Burkitt's Lymphoma (BL), AIDs-NHL, mouse plasmacytoma (Pct) and possibly multiple myeloma (MM).
Using 2 specific antibodies, here we show that the AID protein can be detected in GC centroblasts and their transformed counterpart (Burkitt lymphoma) but not in pre-GC B cells and post-GC neoplasms, including B-cell chronic lymphocytic leukemia and multiple myeloma.
This observation verifies that overexpression of AID in non hypermutating BL cell lines as well as the expression of endogenous AID in the hypermutating BL cell line Raji can overcome the target restriction of AID.
These results suggest that Burkitt lymphoma cell lines may be deficient in an unidentified factor that recruits the machinery necessary for A:T mutation or that AID-mediated cytosine deamination in these cells may be processed by conventional base excision repair truncating somatic hypermutation at the G:C phase.
Expression of these genes enhances viral replication and induces germinal center (GC) B cell expansion, activation-induced cytidine deaminase (AID) expression, and c-myc translocation, which in turn predisposes to BL.
In vivo, this could be sufficient to account for the elevated risk of BL-specific chromosomal translocations which would occur following DNA double strand breaks triggered by AID in secondary lymph nodes at the final stage of immunoglobulin gene maturation.