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ERK1/2 phosphorylation, induced by electromagnetic fields, diminishes during neoplastic transformation
Author(s) -
Jin Ming,
Blank Martin,
Goodman Reba
Publication year - 2000
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/1097-4644(20000901)78:3<371::aid-jcb3>3.0.co;2-m
Subject(s) - neoplastic transformation , phosphorylation , transformation (genetics) , malignant transformation , mapk/erk pathway , p38 mitogen activated protein kinases , extracellular , microbiology and biotechnology , biology , chemistry , cancer research , carcinogenesis , biochemistry , gene
It has been suggested that electromagnetic (EM) fields can act as co‐promoters during neoplastic transformation. To examine this possibility, we studied the effects of 0.8‐, 8‐, 80‐, and 300‐μT 60‐Hz electromagnetic (EM) fields in INITC3H/10T1/2 mouse fibroblast cells. These cells are transformed carcinogenically by methylcholanthrene, but the neoplastic phenotype can be suppressed indefinitely by the presence of retinyl acetate (RAC) in the culture medium. The effects of EM field exposures were examined at three stages: (1) before initiation of transformation (i.e., RAC in the culture media); (2) early in the transformation process (4 days after withdrawal of RAC); and (3) at full of neoplastic transformation (10 days after withdrawal of RAC). EM field exposures induced significant increases in protein levels for hsp70 and c‐Fos and in AP‐1 binding activity. EM fields induced phosphorylation of MAPK/ERK1/2 before the onset of transformation, but these increases diminished during the transformation process. No phosphorylation in the other major extracellular stress pathway, SAPK/JNK, was detected in cells exposed to EM fields at any time before, during, or after neoplastic transformation. Human cells HL60, MCF7, and HTB124, exposed to EM fields, also showed MAPK/ERK1/2 phosphorylation. Cells treated with the phorbol ester, TPA, served as positive controls for AP‐1 activation, c‐Fos protein synthesis, and ERK1/2 phosphorylation. There was no indication that EM fields affected the rate of cell transformation or acted as a co‐promoter, under the conditions of this study. J. Cell. Biochem. 78:371–379, 2000. © 2000 Wiley‐Liss, Inc.