Alterations in the cell cycle and in the protein level of cyclin D1, p21CIP1, and p16INK4a after exposure to 50 Hz MF in human cells.

The effect of exposure to 50 Hz, 1 mT magnetic fields (MF) on the cell cycle in general, on the DNA synthesis in S-phase, and on the G1-phase regulating proteins Cdk4, cyclin D1, p16INK4a, and p21CIP1 was investigated in human amniotic fluid cells. The BrdU-incorporation assay revealed a significant diminution of S-phase cells in MF-exposed cultures. The protein level of Cdk4 did not change, but MF induced a decreased expression of cyclin D1 after 24 h and 30 h exposures. The level of p16INK4a increased at 1 h and 12 h after exposure, whereas the expression of p21CIP1 was enhanced at 6 h and 12 h after exposure. Reduced levels of both Cdk inhibitors were observed at longer exposure times (24 h, 30 h). Our results suggest an inhibitory effect of MF on the G1-phase induced by altered expression of p16INK4a and p21CIP1.