Bone marrow stromal cell cytochrome P4501B1 is required for pre-B cell apoptosis induced by 7,12-dimethylbenz[a]anthracene.
We previously demonstrated that murine bone marrow stromal cells express high levels of cytochrome P4501B1 (CYP1B1) that metabolizes 7,12-dimethylbenza[a]anthracene (DMBA), and that DMBA activates the Ah receptor (AhR) in these cells in vitro. More recently, we reported that CYP1B1 is required for DMBA-induced lymphoblastoma formation in vivo. In this study, we addressed the hypothesis that bone marrow stromal cell CYP1B1, and not AhR activation, is required for DMBA-induced pre-B-cell apoptosis. Although DMBA did not directly cause apoptosis in pre-B cells, dose-dependent apoptosis of pre-B cells was observed when they were cocultured with a bone marrow stromal cell line. The DMBA 3,4-dihydrodiol metabolite was more potent in effecting pre-B-cell apoptosis than DMBA, whereas the potent AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin was inactive. Both pre-B cells and bone marrow stromal cells contained DMBA-diol-epoxide DNA adducts, indicating that reactive metabolites were transferred from stromal cells to pre-B cells. DMBA caused apoptosis when cocultured with primary bone marrow stromal cells isolated from AhR-null mice but not CYP1B1-null mice. When cocultured with AhR-null primary bone marrow stromal cells, DMBA induced approximately 50% of the pre-B-cell apoptosis seen with stromal cells from AhR-heterozygous mice. This reduced level of apoptosis parallels the decreased CYP1B1 expression in AhR-null mouse bone marrow stromal cells. These findings provide convincing evidence that bone marrow stromal cell CYP1B1 metabolism of DMBA, but not AhR activation, is required for DMBA-induced pre-B-cell apoptosis.
Heidel
S M
SM
Department of Pathobiological Sciences, University of Wisconsin, Madison, Wisconsin, USA.
Holston
K
K
Buters
J T
JT
Gonzalez
F J
FJ
Jefcoate
C R
CR
Czupyrynski
C J
CJ
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis; D001189:Aryl Hydrocarbon Hydroxylases; D001402:B-Lymphocytes / Q000187:drug effects* / Q000473:pathology; D001854:Bone Marrow Cells / Q000166:cytology / Q000201:enzymology*; D002273:Carcinogens / Q000378:metabolism / Q000494:pharmacology*; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000502:physiology*; D018736:DNA Adducts / Q000378:metabolism; D051379:Mice; D011950:Receptors, Cholinergic / Q000378:metabolism; D017154:Stromal Cells / Q000201:enzymology; D014407:Tumor Cells, Cultured
D002273:Carcinogens; D018736:DNA Adducts; D011950:Receptors, Cholinergic; D015127:9,10-Dimethyl-1,2-benzanthracene; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585498:Cyp1b1 protein, mouse; D065633:Cytochrome P-450 CYP1B1