Role of DNA methylation in the adaptive responses induced in a human B lymphoblast cell line by long-term low-dose exposures to gamma-rays and cadmium

摘要

The possible involvement of epigenetic factors in health risks due to exposures to environmental toxicants and ionizing radiation is poorly understood. We have tested the hypothesis that DNA methylation contributes to the adaptive response (AR) to ionizing radiation or Cd. Human B lymphoblast cells HMy2.CIR were irradiated (0.032 Gy gamma-rays) three times per week for 4 weeks or exposed to CdCb (0.005, 0.01, or 0.1 |jlM) for 3 months, and then challenged with a high dose ofCd (50 or 100 muM) or-gamma-rays (2Gy). Long-term low-dose radiation (LDR) or long-term low-dose Cd exposure induced AR against challenging doses of Cd and irradiation, respectively. When the primed cells were treated with 5-aza-2'-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, the ARs were eliminated. These results indicate that DNA methylation is involved in the induction of AR in HMy2.CIR cells.