BIOLOGICAL AND TECHNICAL VARIABLES IN MYC EXPRESSION IN HL60 CELLS EXPOSED TO 60 HZ ELECTROMAGNETIC-FIELDS

The purpose of the present report is two-fold: first, to find an expla nation for the inability of two groups of investigators, Lacy-Hulbert et al. and Saffer and Thurston [A. Lacy-Hulbert, R. Wilkins, T.R. Hesk eth, J.C, Metcalfe, No effect of 60Hz electromagnetic fields on MYC or beta-actin expression in human leukemic cells, Radiation Res. 144 (19 95) 9-17; J.D, Saffer, S.J. Thurston, Short exposures to 60 Hz magneti c fields do not alter MYC expression in HL60 cells or Daudi cells, Rad iation Res. 144 (1995) [18-25], to replicate our results, and second, to examine the broader issues involved in in vitro studies and replica tion in bioelectromagnetics. Replication experiments mandate that the precise cell type population be used and that the experimental protoco l (i.e., exposure system, conditions of exposure, techniques for extra ction and measurement) be followed exactly. By this criterion, the rep orted experiments of Lacy-Hulbert et al. and Saffer and Thurston were not replications. In this paper, we present replication experiments th at again show a significant increase in c-myc transcript levels, altho ugh at a lower level. We also introduce variations from our protocol t hat were used in the reported 'replication' experiments. A major depar ture from the original experiments was the use of different population s of HL60 cells; American Type Culture Collection (ATCC) as opposed to the original Columbia University Cancer Center (CUCC), The growth cha racteristics and responses to 12-O-tetra-decanoylphorbol-13-acetate (T PA) of the two cell populations showed significantly different reactiv ities, In line with these characteristics, c-myc increased in CUCC cel ls and did not increase in ATCC cells when stimulated by EM fields. We also compared other differences in protocol: SDS/phenol and guanidine /phenol RNA extraction procedures, the stability/variability of two ho usekeeping genes, beta-2 mu globulin and GaPDH, as internal standards, sham-exposed controls versus inactive coil and double-wound coils ver sus single-wound coils. In all experiments, cells were shielded within mu metal containers during exposures. The shielding in one of the 're plication' studies, Lacy-Hulbert et al.'s, suggests that both experime ntal and control cells, which were side by side in the apparatus, were exposed to EM fields. (C) 1997 Elsevier Science S.A.