Human CD34 Hematopoietic Progenitor Cells Are Sensitive Targets for Toxicity Induced by 1,4-Benzoquinone

Chronic human exposure to benzene has been linked to several hematopoietic disorders, including leukemia and lymphomas. Cer-tain benzene metabolites, including benzoquinone (BQ), are genotoxic and mutagenic. Bone marrow stem cells are targets for benzene-induced cytotoxicity and DNA damage that could result in changes to the genome of these progenitor cells, thereby leading to hemato-poietic disorders and cancers. Human bone marrow CD34 hemato-poietic progenitor cells (HPC) were exposed in vitro to 1,4-BQ to assess cytotoxicity, genotoxicity, and DNA damage responses and the molecular mechanisms associated with these events. CD34 HPC from 10 men and 10 women were exposed to 0, 1, 5, 10, 15, or 20 M of 1,4-BQ and analyzed 72 h later. Apoptosis and cytotoxicity were dose-dependent, with exposure to 10 M 1,4-BQ resulting in approximately 60 % cytotoxicity relative to untreated controls. A significant increase in the percentage of micronucle