Effects of 5-bromo-2-deoxy-uridine and 2-deoxy-D-glucose on the radiosensitivity of proliferating transformed mammalian cells

Effects of 5-bromo-2-deoxy-uridine (BrdU) and 2-deoxy-D-glucose (2-DG) were studied in exponentially growing transformed mammalian (BHK-21) cells, grown as monolayer. Micronuclei formation as an index of radiation damage was studied by i)cytokinesis block technique from cytochalasin-B induced binucleated cells, and ii)conventional technique. Presence of BrdU (0.8 μM) for nearly 2 cell cycles before γ-irradiation (2.5 Gy) significantly increased frequencies of cells with micronuclei. Post-irradiation incubation of cultures in liquid holding medium (HBSS) however, reduced micronuclei formation, especially in the BrdU treated cells. Presence of 2-DG (4 hr, equimolar with glucose) in growth as well as liquid holding medium further increased micronuclei frequencies. These observations suggest that radiation induced DNA lesions in BrdU substituted cells, leading to chromosome fragmentation are partly repairable. 2-DG increased cytogenetic damage, possibly by inhibiting the repair of such repairable lesions. Present studies suggest that combination of 2-DG could optimize BrdU-radiation therapy of brain tumors by reducing the BrdU doses required for tumor radiosensitization. (author). 34 refs., 2 figs., 2 tabs