Free Radical-Initiated and Gap Junction-Mediated Bystander Effect due to Nonuniform Distribution of Incorporated Radioactivity in a Three-Dimensional Tissue Culture Model

• Published in: Radiation research Vol. 155; no. 2; pp. 335 - 344
• Main Authors: Bishayee, Anupam, Hill, Helene Z., Stein, Dana, Rao, Dandamudi V., Howell, Roger W.
• Format: Journal Article
• Language: English
• Published: Oak Brook, Il Radiation Research Society 01-02-2001
• Subjects: Animals; Beta Particles; Biological and medical sciences; Biological effects of radiation; Biological Transport; Cell Communication; Cell nucleus; Cells; CHO cells; Cricetinae; Cricetulus; Culture Techniques - methods; Dimethyl Sulfoxide - pharmacology; Diploidy; Dyes; Epithelial cells; Fibroblasts - metabolism; Fibroblasts - radiation effects; Fibroblasts - ultrastructure; Free Radicals; Fundamental and applied biological sciences. Psychology; Gap junctions; Gap Junctions - physiology; Ionizing radiations; Irradiation; Lindane - pharmacology; Medical sciences; Miscellaneous; Radiation-Protective Agents - pharmacology; Radioactive decay; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); REGULAR ARTICLES; Space life sciences; Thymidine - metabolism; Tissues, organs and organisms biophysics; Tritium - metabolism; Animal model; Pathophysiology; Treatment efficiency; Lindane; Rodentia; Tissue culture; Experimental study; Radiotherapy; Gap junction; Free radical; Heterogeneity; Vertebrata; Radiation dose; Mammalia; Organochlorine compounds; Animal; Dimethyl sulfoxide; Radiation injury; Hamster
• ISSN: 0033-7587; 1938-5404
• DOI: 10.1667/0033-7587(2001)155[0335:FRIAGJ]2.0.CO;2

Bishayee, A., Hill, H. Z., Stein, D., Rao, D. V. and Howell, R. W. Free Radical-Initiated and Gap Junction-Mediated Bystander Effect due to Nonuniform Distribution of Incorporated Radioactivity in a Three-Dimensional Tissue Culture Model. To investigate the biological effects of nonuniform distribution of radioactivity in mammalian cells, we have developed a novel three-dimensional tissue culture model. Chinese hamster V79 cells were labeled with tritiated thymidine and mixed with unlabeled cells, and multicellular clusters (∼1.6 mm in diameter) were formed by gentle centrifugation. The short-range β particles emitted by 3H impart only self-irradiation of labeled cells without significant cross-irradiation of unlabeled bystander cells. The clusters were assembled in the absence or presence of 10% dimethyl sulfoxide (DMSO) and/or 100 μM lindane. DMSO is a hydroxyl radical scavenger, whereas lindane is an inhibitor of gap junctional intercellular communication. The clusters were maintained at 10.5°C for 72 h to allow 3H decays to accumulate and then dismantled, and the cells were plated for colony formation. When 100% of the cells were labeled, the surviving fraction was exponentially dependent on the mean level of radioactivity per labeled cell. A two-component exponential response was observed when either 50 or 10% of the cells were labeled. Though both DMSO and lindane significantly protected the unlabeled or bystander cells when 50 or 10% of the cells were labeled, the effect of lindane was greater than that of DMSO. In both cases, the combined treatment (DMSO + lindane) elicited maximum protection of the bystander cells. These results suggest that the bystander effects caused by nonuniform distributions of radioactivity are affected by the fraction of cells that are labeled. Furthermore, at least a part of these bystander effects are initiated by free radicals and are likely to be mediated by gap junctional intercellular communication.