Figure 3.

Dose- and exposure duration-dependence of arsenic-induced global DNA hypomethylation and altered gene expression in arsenic-transformed cells. (A) DNA methylation status in cells treated with arsenic for 19 weeks and cultured in arsenic-free medium for 6 more weeks. (B) DNA methylation status in cells exposed to 0.5 μM arsenic at times indicated. All data are normalized to the control. (C) Correlation based on the various dosage groups of arsenic between genomic DNA methylation status and tumor incidence after inoculation. (D) MT expression in arsenic-transformed cells (cross-hatched column) and nontransformed cells (solid column) determined after cells were exposed to cadmium at the indicated concentration for 24 hr. Data are normalized to nontransformed cells without exposure to cadmium and represent mean ± SEM of triplicate experiments.