Université de Liège
Biologie des tissus conjonctifs
Sart Tilman, CHU B-23 | 4000 Liège
EMF interference on cell membrane (1995-2005)
B.Nusgens & P.Mineur
In order to determine if there might be biological and health consequences after exposure to EMF, the understanding of the potential mechanism(s) of interactions of EMF with biological structures is required. A plausible mechanism is an interference of EMF with the events occurring at the cell membrane allowing communication with their external environment (hormones, growth factors) through receptors (antenna). The transmission of such messages is performed by second messengers (calcium ions, cyclic AMP) to ultimately regulate cellular functions (proliferation, manufacture of products for exportation, migration, programmed cell death). Perturbation of this cascade of events may have health consequences.
In vitro experiments, using a variety of cell types under controlled conditions, have been performed world wide to investigate the effect of EMF on this communication network with negative and positive results, which were, in some cases, not reproducible by other research teams. Our team observed a modulation by EMF of the calcium signals induced by growth factors in normal human cells. This effect was only observed in a window of concentration of growth factors in serum that sub-optimally activate the cells. A further potential mechanism considers that EMF, not mutagenic on their own, might act as co-carcinogen. Our approach was to combine EMF to a constant, environmentally deleterious factor: the UV irradiation known to be responsible for the increasing incidence of aggressive skin cancers such as melanoma. Up to now, no alteration of the cell response to UV and EMF has been observed.
The only effect of EMF that we reproducibly observed was the preservation of the [Ca 2+ ] i oscillations in cells activated by sub-optimal concentrations of seric growth factors. The involvement of the signaling molecules of the MAPKinases family, ERK 1/2, has yet to be confirmed. Other members of this family, p-38 and JUN-kinase, have to be investigated. Experiments using siRNA against MAPKinases will confirm their role in Ca 2+ signalling and in the effect of EMF. The significance of this observation in cell proliferation (survival) and programmed cell death (apoptosis) will be evaluated on other types of cells, normal and transformed.
Up to now, no significant influence of EMF on the expression of UVB-induced genes, potentially involved in angiogenesis, has been observed either in fibroblasts from human dermis or in keratinocytes from human epidermis. Repetition of these experiments on keratinocytes transfected with the oncogene ras will be considered.
B.Nusgens & P.Mineur
In most cell types, a transient rise in the concentration of intracellular ionised calcium [Ca2+]i participates in the transfer of information from the outside to the various components of the cell machinery controlling vital functions (attachment, migration, manufacture of products, multiplication and death). This signal is generated by the opening of membrane-bound channels and/or the reversible release of the ion from intracellular stores. Most types of membrane-bound receptors, including the membrane receptors recognising the mechanical signals, use this sensitive signaling pathway. In cultured human fibroblasts, EMF at moderate intensity extend the [Ca2+]i oscillations induced by growth factor activity contained in suboptimal concentrations of serum.
Bomans, J., Lambert, CH.A., Scarpa, B., Nusgens, B., Legros, W., and Lapière, CH.M. (1996). Low intensity electromagnetic fields produce a wave of calcium in the fibroblasts (Les champs électromagnétiques de faible intensité produisent une vague calcique dans les fibroblastes): Bulletin et mémoires de l’académie royale de médecine de Belgique, 151, p. 243-249.
Mineur, P. (2010). Etudes des effets biologiques de facteurs environnementaux.PhD thesis, University of Liège, Belgium (see the document online).