Focus formation of C3H/10T1/2 cells and exposure to a 836.55 MHz modulated radiofrequency field
- Jerry L. Pettis Memorial Veterans Administration Medical Center, Loma Linda, CA (United States)
Disruption of communication between transformed cells and normal cells is involved in tumor promotion. The authors have tested the hypothesis that exposures to radiofrequency (RF) fields using a form of digital modulation (TDMA) and a chemical tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), are copromoters that enhance focus formation of transformed cells in coculture with parental C3H/10T1/2 murine fibroblasts. RF field exposures did not influence TPA`s dose-dependent promotion of focus formation in coculture. Cell cultures were exposed to an 836.55 MHz TDMA-modulated field in TEM transmission line chambers, with incident energies that simulated field intensities at a user`s head. Specific absorption rates (SARs) of 0.15, 1.5, and 15 {micro}W/g were used during each digital packet, and the packet frequency was 50/s. The TEM chambers were placed in a commercial incubator at 37 C and 95% humidity/5% CO{sub 2}. The RF field exposures were in a repeating cycle, 20 min on, 20 min off, 24 h/day for 28 days. At 1.5 {micro}W/g, TPA-induced focus formation was not significantly different in RF-exposed cultures compared to parallel sham-exposed cultures in ten independent experiments in terms of the number, density, and area of foci. Similarly, at 0.15 and 15.0 {micro}W/g, in two and four experiments, respectively, RF exposure did not alter TPA-induced focus formation. The findings support a conclusion that repeated exposures to this RF field do not influence tumor promotion in vitro, based on the RF field`s inability to enhance TPA-induced focus formation.
- DOE Contract Number:
- AI01-90CE35035
- OSTI ID:
- 462569
- Journal Information:
- Bioelectromagnetics, Vol. 18, Issue 3; Other Information: PBD: 1997
- Country of Publication:
- United States
- Language:
- English
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