Enhanced Killing of HeLa Cells Pre-Labeled with 5-Bromodeoxyuridine by Monochromatic Synchrotron Radiation at 0.9 Å : An Evidence for Auger Enhancement in Mammalian Cells

Abstract

The HeLa cells labeled with 5-bromodeoxyuridine were irradiated with monochromatic synchrotron radiation at 0.90 Å or 1.00 Å, below or above the wavelength of the K absorption edge (0.92 Å) of bromine. Although non-specific sensitization of labeled cells to the radiation was observed irrespective of the wavelengths, the labeled cells were killed at a higher rate by the irradiation at 0.90 Å than at 1.00 Å. The nonlabeled cells showed no difference in the sensitivity to the radiation at the two wavelengths. The enhanced lethality of labeled cells at 0.90 Å may be inferred to be due to the induction of Auger effect in bromine atom of the DNA selectively absorbed the photon at 0.90 Å. Implications of this finding for the photon activation therapy was discussed.