Differential modification of radiation damage in 5-bromo-2-deoxy-uridine sensitized human glioma cells and PHA-stimulated peripheral leukocytes by 2-deoxy-D-glucose.

Effects of 5-bromo-2-deoxy-uridine (BrdU) and 2-deoxy-D-glucose (2-DG) on 60-Co-gamma-ray induced damage were studied in monolayer cultures of glioma (BMG-1) cells, and PHA-stimulated peripheral leukocytes from normal donors. Micronuclei formation was used as an index of cytogenetic damage. BrdU and 2-DG treatments did not induce micronuclei formation in unirradiated cultures. Presence of BrdU (0.8 microM) for more than one cell cycle (24 hr) significantly increased gamma-ray (1-4 Gy) induced micronuclei formation in exponentially growing BMG-1 cells. Incubation of irradiated cells under sub-optimal growth conditions (DMEM with 1% serum) for 3 hr, instead of growth medium, significantly decreased micronuclei formation. Post-irradiation presence of 2-DG (5 mM; 3 hr, in DMEM + 1% serum) significantly increased radiation damage. In BrdU sensitized cells also, 2-DG significantly increased radiation damage further. In PHA-stimulated leukocytes from normal donors, 2-DG (5mM, equimolar with glucose; for 2 hr) did not increase gamma-ray (2-Gy, 42 hr after PHA-stimulation) induced micronuclei formation. Pre-irradiation presence of BrdU (1.6 microM) significantly increased micronuclei. On the contrary, 2-DG treatment reduced radiation induced micronuclei formation in BrdU sensitized leukocyte cultures. These results suggest that (i) radiation induced lesions leading to micronuclei formation in proliferating tumour cells, are, at least, partly repairable; (ii) combination of 2-DG could reduce BrdU doses required for radiosensitization of proliferating tumour cells; and (iii) 2-DG could differentially increase radiation damage in BrdU sensitized proliferating tumour cells, while reducing manifestation of damage in normal proliferating cells.