The Effects of Pulsating Electromagnetic Fields on Differentiation and Growth in Cloudman S91 Murine Melanoma Cells in vitro

Abstract

Specific low-energy pulsed electromagnetic fields (PEMF) induced, in certain circumstances, changes in the activity of tyrosine hydroxylase (a marker for differentiation), the level of melanin (correlating with the tyrosine hydroxylase activity), the level of cAMP, and mitosis, in Cloudman S91 clone M3 murine melanoma cells. The observed changes were similar to those induced by alpha melanocyte stimulating hormone (MSH). A specific PEMF caused an additive increase in tyrosine hydroxylase, and an additive decrease in mitosis with MSH and activators of adenylate cyclase. Continuously applied PEMF throughout the culture period inhibited tyrosine hydroxylase but not cell division. In cultures passaged for more than about 39 times, a loss of tyrosine hydroxylase response but not mitotic response to MSH occurred. This loss of tyrosinase response to MSH correlated with a loss of response to PEMF but both MSH and PEMF inhibited mitosis to the same extent as in earlier passage cells. The inhibition of mitosis by PEMF and MSH still occurred. Different batches of serum could also affect the tyrosine hydroxylase and mitotic response of the cells and the response of the cells to MSH and PEMF. It is concluded that a number of parameters can influence the effect of PEMF on biological systems, but that a large and significant PEMF effect can be reliably and reproducibly measured under the conditions described here.