Intermittent F-actin Perturbations by Magnetic Fields Inhibit Breast Cancer Metastasis

F-actin (filamentous actin) has been shown to be sensitive to mechanical stimuli and play critical roles in cell attachment, migration and cancer metastasis, but there are very limited ways to perturb F-actin dynamics with low cell toxicity. Magnetic field is a non-invasive and reversible physical tool that can easily penetrate cells and human bodies. Here we show that 0.1/0.4 T 4.2 Hz moderate intensity low frequency rotating magnetic field (LF-RMF)-induced electric current could directly decrease F-actin formation in vitro and in vivo, which results in decreased breast cancer cell migration, invasion and attachment. Moreover, LF-RMFs generated significantly different effects on F-actin in breast cancer vs. noncancerous cells, including F-actin number and their recovery after magnetic field retrieval. Using an intermittent treatment modality, LF-RMFs could significantly reduce mice breast cancer metastasis, prolong mice survival by 31.5-46.0% (P < 0.0001) and improve their overall physical condition. Therefore, our work demonstrates that LF-RMFs not only can be used as a research tool to perturb F-actin, but also can inhibit breast cancer metastasis through F-actin modulation while having minimum effects on normal cells, which reveals their potential to be developed as temporal-controlled, non-invasive and high-penetration physical treatments for metastatic cancer.