Identification of three subgroups of B cell chronic lymphocytic leukemia based upon mutations of BCL-6 and IgV genes.
Although B cell chronic lymphocytic leukemia (B-CLL) has been traditionally viewed as a tumor of virgin B cells, this notion has been recently questioned by data suggesting that a fraction of B-CLL derives from antigen experienced B cells. In order to further clarify the histogenetic derivation of this lymphoproliferation, we have analyzed the DNA sequences of the 5' non-coding region of BCL-6 proto-oncogene in 28 cases of B-CLL. Mutations of BCL-6 proto-oncogene, a zinc finger transcription factor implicated in lymphoma development, represent a histogenetic marker of B cell transit through the germinal center (GC) and occur frequently in B cell malignancies derived from GC or post-GC B cells. For comparison, the same tumor panel was analyzed for somatic mutations of the rearranged immunoglobulin variable (IgV) genes, which are known to be acquired at the time of B cell transit through the GC. Sequence analyses of BCL-6 and IgV genes allowed the definition of three groups of B-CLL. Group I B-CLL displayed mutations of both BCL-6 and IgV genes (10/28; 36%). Group II B-CLL displayed mutated IgV genes, but a germline BCL-6 gene (5/28; 18%). Finally, group III B-CLL included the remaining cases (13/28; 46%) that were characterized by the absence of somatic mutations of both BCL-6 and IgV genes. Overall, the distribution of BCL-6 and IgV mutations in B-CLL reinforce the notion that this leukemia is histogenetically heterogeneous and that a substantial subgroup of these lymphoproliferations derives from post-germinal center B cells.
Capello
D
D
Department of Medical Sciences, 'Amedeo Avogadro' University of Eastern Piedmont, Novara.
Fais
F
F
Vivenza
D
D
Migliaretti
G
G
Chiorazzi
N
N
Gaidano
G
G
Ferrarini
M
M
D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D015322:Gene Rearrangement, B-Lymphocyte; D005803:Genes, Immunoglobulin; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000145:classification* / Q000235:genetics* / Q000276:immunology; D009154:Mutation; D017354:Point Mutation; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051560:Proto-Oncogene Proteins c-bcl-6; D011519:Proto-Oncogenes; D014157:Transcription Factors / Q000235:genetics*; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D051560:Proto-Oncogene Proteins c-bcl-6; D014157:Transcription Factors