Suppressed apoptosis of pre-B cells in bone marrow of pre-leukemic p190bcr/abl transgenic mice.
Mice transgenic for a p190bcr/abl construct develop pre-B cell leukemia/lymphoma, providing a model of Ph+ ALL. To investigate events in tumorigenesis, immunofluorescence labeling, flow cytometry and a short-term culture assay were used to quantitate precursor B cells and their apoptotic rates in bone marrow of p190bcr/abl transgenic mice over a wide age range. Malignancies appeared rapidly at 8-12 weeks of age, followed by slower tumor onset. At 8-12 weeks in normal mice, the apoptotic rate fell among pro-B cells but increased steeply among pre-B cells, while the total number of B lineage cells declined. In contrast, in p190bcr/abl transgenic mice over the same time period, while pro-B cells remained normal in apoptotic rate and number, apoptosis of pre-B cells was markedly inhibited and the number of B lymphocytes increased. At later ages (14-30 weeks), B cell precursors in control mice remained constant in apoptotic activity and number, while in the few surviving transgenic mice B cell populations were expanded. The results reveal characteristic changes in apoptotic activity among B cell precursors in bone marrow during early life, severely perturbed in preleukemic p190bcr/abl transgenic mice by a preferential suppression of pre-B cell apoptosis. p190bcr/abl may thus promote leukemogenesis by permitting aberrant cells generated during early B cell development to evade a normal quality checkpoint and negative selection.
Yu
Q
Q
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada.
Brain
J
J
Laneuville
P
P
Osmond
D G
DG
D000367:Age Factors; D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000502:physiology*; D001854:Bone Marrow Cells / Q000502:physiology*; D004249:DNA Damage; D016044:Fusion Proteins, bcr-abl / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D011289:Preleukemia / Q000473:pathology*
D016044:Fusion Proteins, bcr-abl