title: Cell cycle kinetic measurements in an irradiated rat rhabdomyosarcoma using a monoclonal antibody to bromodeoxyuridine.
abstract: Cell cycle kinetics after X-irradiation were studied in a solid rat rhabdomyosarcoma using a monoclonal antibody to bromodeoxyuridine (BrdUrd) in cells in which the DNA was labeled by BrdUrd. It could be shown that this tumor was composed of about 80% diploid host cells, and only 20% of the cells in the dissociated tumor were actually tetraploid tumor cells. When rats were injected intraperitoneally with BrdUrd to label S-phase cells in the tumor, only a fraction of both types of cells became labeled with BrdUrd during S-phase, even 24 h after injection. The diploid BrdUrd-labeled cells progressed rapidly into cycle; 4 h after injection of BrdUrd, labeled diploid G1-phase cells could be observed. Only 25% of the tetraploid S-phase cells could be labeled by a single injection of BrdUrd (160 mg/kg body weight). These labeled tetraploid cells progressed through the cell cycle with similar velocities as did labeled diploid cells. Using a "Mini Osmotic Pump" containing bromodeoxycytidine (BrdCyd) at high concentration (0.3 mol/L) that released BrdCyd continuously into the organism where it was converted to BrdUrd, it could be shown that after 2 days about 60% of cells in S-phase and 70% of cells in G2-phase were labeled. The fraction of labeled G2-phase cells in irradiated tumors (D = 10 and 20 Gy) was enhanced between 10 and 50 h after irradiation due to a radiation-induced G2 block in cycling tetraploid tumor cells.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001972:Bromodeoxycytidine / Q000008:administration & dosage; D001973:Bromodeoxyuridine / Q000276:immunology; D002453:Cell Cycle / Q000528:radiation effects; D004171:Diploidy; D011003:Ploidies; D011419:Propidium; D051381:Rats; D012208:Rhabdomyosarcoma / Q000473:pathology* / Q000532:radiotherapy; D014965:X-Rays
chemical_list: D000911:Antibodies, Monoclonal; D001972:Bromodeoxycytidine; D011419:Propidium; D001973:Bromodeoxyuridine