Influence of static magnetic field on the antiproliferative effects of vitamin D on human breast cancer cells

We describe the effect of a 0.2 tesla (T) static magnetic field generated b y a magnetic resonance tomograph and of vitamin D treatment on a human brea st cancer cell line (MCF-7). Cell damage and proliferation were monitored b y measuring the incorporation of [H-3]thymidine in duplicating DNA and by t he clonogenic assay. [H-3]Thymidine incorporation in MCF-7 was stimulated b y vitamin D at low doses (10(-12)-10(-10) M), whereas it was inhibited at h igher concentrations (10(-9)-10(-6) M). Magnetic field treatment (0.2 T) de creased [H-3]thymidine incorporation in human breast cancer cells, eliminat ing the proproliferative effect of low doses of vitamin D, and enhanced the vitamin D antiproliferative effect, further reducing [H-3]thymidine incorp oration, from -12.5% (P < 0.05) to -66.7% (P < 0.001), over the range of 10 (-9) to 10(-6) M. In the clonogenic assay, ability of MCF-7 to form colonie s was inhibited by vitamin D 10(-9) M and above, whereas 3-h exposure to 0. 2 T magnetic field had no effect on the number of cell colonies formed. In conclusion, vitamin D treatment yields a permanent antiproliferative effect , while magnetic field exposure only temporarily slows down cellular growth . These findings suggest that therapy with vitamin D may prove beneficial f or chemoprevention or treatment of breast cancer. Static magnetic field, al one or in combination, does not appear to represent an effective candidate for breast cancer therapy, at least at the intensity used in the present st udy.