Focus formation of C3H/10T1/2 cells and exposure to a 836.55 MHz modulated radiofrequency field

✍ Scribed by Christopher D. Cain; Deborah L. Thomas; W. Ross Adey

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 89 KB
• Volume: 18
• Category: Article
• ISSN: 0197-8462
• DOI: 10.1002/(sici)1521-186x(1997)18:3<237::aid-bem6>3.0.co;2-3

✦ Synopsis

Disruption of communication between transformed cells and normal cells is involved in tumor promotion. We 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 mW/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 ЊC and 95% humidity/5% CO 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 mW/g, TPA-induced focus formation (at 10, 30, and 50 ng/ ml) 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 mW/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.