Clonogenicity and gene expression modulation in the bone marrow of mice chronically exposed to arsenic and atrazine.

The clonogenicity of myeloid progenitors (CFU-GM) and the modulation of gene expression of 1185 cancer-related genes by DNA-macroarrays in bone marrow were used to investigate in male and female mice the combined effects of continuous exposure to arsenate and atrazine in drinking water. In male mice, the exposure to arsenate or to atrazine alone and the combined exposure did not change the clonogenicity of the progenitors. In females the percentage of CFU-GM decreased significantly after atrazine exposure, did not change with arsenic treatment, but dramatically increased after the combined exposure to the two chemicals. Results from microarrays indicate that atrazine alone didn’t stimulate the expression of any of the cancer genes analyzed in both male and female. Arsenic induced gene expression modulation only in female and had no effects on male. Major significant changes on the gene expression in bone marrow cells resulted following the co-exposure to arsenic and atrazine in both male and female. These results indicate that co-exposure of mice to atrazine and arsenate induces significant effects at the level of transcriptional activation of genes in bone marrow cells, as well as stimulating the myeloid progenitors to proliferate, particularly when co-administered in drinking water to female mice.