Induction of G 2 Arrest and Apoptosis of Raji Cells by Continuous Low-Dose Beta Irradiation with 188 Re-Perrhenate

Abstract

Continuous irradiation with exponentially reducing β-rays induces cell death, known as apoptosis. The aim of this study was to investigate the G2 arrest and apoptosis caused by the β-ray emitted by the radioisotope¹⁸⁸Re. Doses of 0.4 Gy (3.7 MBq), 4 Gy (37 MBq), and 40 Gy (370 MBq), were added to Blymphoma Raji cells, and cell viability, apoptosis, and DNA cell-cycle changes were assayed. ¹⁸⁸Re showed time- and dose-dependent effects on cell viability and on cell apoptosis and necrosis. At a ¹⁸⁸Re dose of 0.4 Gy, G₂ cell-cycle arrest was observed after 16 hours, and 4,6-diamidino-2-phenylindole (DAPI) staining indicated a slow, time-dependent increase in apoptotic bodies. At a ¹⁸⁸Re dose of 40 Gy, DNA fragmentation was observed at 2 hours, indicative of early damage in the nucleus. In summary, our results showed that continuous irradiation with low-dose β-rays induced G₂ arrest and progressive apoptosis, which may be characteristic mechanisms of radionuclide therapy.