Dna Damage Induction by ¹²⁵I-Estrogen

Abstract

DNA damage induced by the radioactive decay of ¹²⁵I-estrogen (¹²⁵I-VME2) in an estrogen receptor expressing CHO cell line, CHO-ER, was measured. ¹²⁵I-VME2 targeted ¹²⁵I atoms proximal to DNA estrogen response elements (EREs). ¹²⁵I decays were accumulated at-135^oC, and thereafter assayed by alkaline and neutral filter elution techniques to measure DNA single strand break (ssb) and double strand break (dsb) induction respectively. Increasing DNA damage (both ssbs and dsbs) was detected after exposure of cells to increasing concentrations of ¹²⁵I-VME2. DNA ssb and dsb dose-response curves for ¹²⁵I-VME2 were multiphasic. The rates of DNA damage induction by the decay of ¹²⁵I-VME2 was determined by comparing slopes of all data or by comparing initial slopes. DNA ssb induction per ¹²⁵I-VME2 decay was approximately 2 times greater compared with DNA dsb induction. ¹²⁵I-VME2 decay induced approximately 4-8 times more DNA dsbs than ¹²⁵IUdR decay.