Morphological transformation of C3H 10T1/2 cells by Tc-99m-Cardiolite

The induction of in vitro morphological transformation in C3H 10T1/2 cells by Tc-99m-Cardiolite (contents of Cardiolite kit [hexakis(2-methoxyisobutyl isonitrile) and other components] plus Tc-99m generator eluate) was examine d. Methods: Cells were grown for 48 h in the presence of Tc-99m-Cardiolite or decayed Tc-99m-Cardiolite (Tc-99m-Cardiolite after 1 wk of storage), and cell survival and transformation were assessed by the colony-forming and f ocus assays, respectively. X-ray was used as a reference for radiation effe cts, and 20-methylcholanthrene was used as a positive control for focus for mation. Results: Exposure of cells to Tc-99m-Cardiolite results in a transf ormation frequency that is not significantly different from that induced by the volume equivalent of decayed Tc-99m-Cardiolite. The number of foci per viable cell increases linearly from similar to 0.17 x 10(-4) in the untrea ted control to 1.7 x 10(-4) at 37 kBq/mL and 30 x 10(-4) at 1100 kBq/mL Tc- 99m-Cardiolite or its decayed Tc-99m-Cardiolite volume equivalent. Furtherm ore, exposure of cells to low extracellular concentrations of Tc-99m-Cardio lite or decayed Tc-99m-Cardiolite (cell survival, greater than or equal to 88%) induces an similar to 20-fold greater number of transformants per viab le cell than that observed after 0.5 Gy x-irradiation, a dose that causes t he same level of toxicity. Conclusion: Radioactive and decayed Tc-99m-Cardi olite induce morphological transformation of C3H 10T1/2 cells in vitro. The underlying mechanism does not seem to be related to the radiation effects of decaying Tc-99m but to chemical(s) present in the Tc-99m-Cardiolite kit.