NMR exposure sensitizes tumor cells to apoptosis

NMR technology has dramatically contributed to the revolution of image diagnostic. NMR apparatuses use combinations of microwaves over a homogeneous strong (1 Tesla) static magnetic field. We had previously shown that low intensity (0.3–66 mT) static magnetic fields deeply affect apoptosis in a Ca²⁺ dependent fashion (Fanelli et al., 1999 FASEBJ., 13;95–102). The rationale of the present study is to examine whether exposure to the static magnetic fields of NMR can affect apoptosis induced on reporter tumor cells of haematopoietic origin. The impressive result was the strong increase (1.8–2.5 fold) of damage-induced apoptosis by NMR. This potentiation is due to cytosolic Ca²⁺ overload consequent to NMR-promoted Ca²⁺ influx, since it is prevented by intracellular (BAPTA-AM) and extracellular (EGTA) Ca²⁺ chelation or by inhibition of plasma membrane L-type Ca²⁺ channels. Three-days follow up of treated cultures shows that NMR decrease long term cell survival, thus increasing the efficiency of cytocidal treatments. Importantly, mononuclear white blood cells are not sensitised to apoptosis by NMR, showing that NMR may increase the differential cytotoxicity of antitumor drugs on tumor vs normal cells. This strong, differential potentiating effect of NMR on tumor cell apoptosis may have important implications, being in fact a possible adjuvant for antitumor therapies.