7,12-Dimethylbenzo[a]anthracene has been studied extensively as a model for carcinogenic and immuno-suppressive polycyclic aromatic hydrocarbons. Most of the biological effects of DMBA require activation by some member of the cytochrome P450 family. One of the most striking effects of DMBA on the immune system is bone marrow toxicity, resulting in severe depletion of progenitor B- lymphocytes. The long-term goal of this project is to identify the mechanisms involved in the bone marrow toxicity of DMBA. In preliminary studies, the investigators found that bone marrow stromal cells have high constitutive levels of cytochrome P450lBl (CYPlBl) that metabolizes DMBA to carcinogenic metabolites in vitro. The investigators also observed that progenitor B- lymphocytes undergo apoptosis when co-cultured with DMBA and bone marrow stromal cells in vitro, but not when incubated with DMBA alone. The central hypothesis is that DMBA metabolism by CYP1B1 in bone marrow stromal cells results in release of metabolites that, directly or indirectly, cause apoptosis in progenitor B- lymphocytes. The rationale for this study is based on: i) the critical importance of stromal cell-B cell interactions in normal B cell development; ii) the high constitutive levels of CYPlBl in stromal cells and its absence in pre B cells; and iii) the ability of DMBA to cause apoptosis in pre-B cells only when co-cultured with bone marrow stromal cells. Death of progenitor B cells might result from: DMBA-DNA adduct formation in pre B cells; loss of an obligatory growth signal from DMBA-treated bone marrow stromal cells; or the release of a toxic moiety for pre B cells by DMBA- treated bone marrow stromal cells. To resolve these possibilities, the investigators will pursue to following three specific aims: 1) Use gene knockout mice in a series of in vivo and in vitro experiments to delineate the roles of CYP1B1, and the AhR, in DMBA-induced pre B cell apoptosis. 2) Distinguish possible mechanisms (i.e., DNA-adduct formation, loss of growth signals, release of Fas ligand or other mediators) that could be responsible for the ability of DMBA-treated bone marrow stromal cells to cause apoptosis in pre-B cells; 3) Identify growth factors and associated regulatory mechanisms that affect CYP1B1 expression in bone marrow stromal cells. At the completion of this project, the investigators expect to have evaluated the role of bone marrow stromal cell CYP1B1, and resulting effector mechanisms, in DMBA-mediated apoptosis in progenitor B cells. These findings could lead to new insights into the mechanisms by which the toxicants cause bone marrow toxicity.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
3R01CA081493-01S1
Application #
6132235
Study Section
Special Emphasis Panel (ZRG1 (01))
Program Officer
Rosenfeld, Bobby
Project Start
1999-05-01
Project End
2003-02-28
Budget Start
1999-09-24
Budget End
2000-02-29
Support Year
1
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Wisconsin Madison
Department
Pathology
Type
Schools of Veterinary Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
N'jai, A U; Larsen, M; Shi, L et al. (2010) Bone marrow lymphoid and myeloid progenitor cells are suppressed in 7,12-dimethylbenz(a)anthracene (DMBA) treated mice. Toxicology 271:27-35
Tang, Yixin; Scheef, Elizabeth A; Gurel, Zafer et al. (2010) CYP1B1 and endothelial nitric oxide synthase combine to sustain proangiogenic functions of endothelial cells under hyperoxic stress. Am J Physiol Cell Physiol 298:C665-78
Tang, Yixin; Scheef, Elizabeth A; Wang, Shoujian et al. (2009) CYP1B1 expression promotes the proangiogenic phenotype of endothelium through decreased intracellular oxidative stress and thrombospondin-2 expression. Blood 113:744-54
Galvan, Noe; Page, Todd J; Czuprynski, Charles J et al. (2006) Benzo(a)pyrene and 7,12-dimethylbenz(a)anthrecene differentially affect bone marrow cells of the lymphoid and myeloid lineages. Toxicol Appl Pharmacol 213:105-16
Galvan, Noe; Teske, Doug E; Zhou, Guodong et al. (2005) Induction of CYP1A1 and CYP1B1 in liver and lung by benzo(a)pyrene and 7,12-d imethylbenz(a)anthracene do not affect distribution of polycyclic hydrocarbons to target tissue: role of AhR and CYP1B1 in bone marrow cytotoxicity. Toxicol Appl Pharmacol 202:244-57
Yuroff, Alice S; Jefcoate, Colin R; Czuprynski, Charles J (2005) Close proximity, but not VLA-4-dependent adherence between pre-B cells and bone marrow stromal cells, is required for DMBA-induced apoptosis of pre-B cells in vitro. Toxicol Lett 156:253-60
Page, Todd J; MacWilliams, Peter S; Suresh, M et al. (2004) 7-12 Dimethylbenz[a]anthracene-induced bone marrow hypocellularity is dependent on signaling through both the TNFR and PKR. Toxicol Appl Pharmacol 198:21-8
Galvan, Noe; Jaskula-Sztul, Renata; MacWilliams, Peter S et al. (2003) Bone marrow cytotoxicity of benzo[a]pyrene is dependent on CYP1B1 but is diminished by Ah receptor-mediated induction of CYP1A1 in liver. Toxicol Appl Pharmacol 193:84-96
Page, Todd J; O'Brien, Scott; Holston, Karrie et al. (2003) 7,12-Dimethylbenz[a]anthracene-induced bone marrow toxicity is p53-dependent. Toxicol Sci 74:85-92
Czuprynski, C J; Faith, N G (2002) Sodium bicarbonate enhances the severity of infection in neutropenic mice orally inoculated with Listeria monocytogenes EGD. Clin Diagn Lab Immunol 9:477-81

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