Nanosecond Pulsed Electric Fields Induce The Apoptosis Of Breast Cancer Cell MDA-MB-231

BACKGROUND AND OBJECTIVE:Researches on skin tumors show that nanosecond pulsed electric fields (nsPEFs) induce apoptosis in vitro and eliminate cancer in vivo. The current research investigated nsPEFs-induced apoptosis on the highly-metastatic human breast cancer cell lines: MDA-MB-231in vitro and in vivo. The possible molecular mechanism is also studied.METHODS:After treatment of nsPEFs in different parameters, the apoptosis, proliferation and invasion of MDA-MB-231cells were examined by Long-Term cell viability assay, CCK-8, DNA ladder, TUNEL and Transwell. Cell cycle and apoptosis were examined by Flow Cytometer, while the morphological changes were observed by transmission electron microscopy (TEM). JC-1analysis was used to test the mitochondrial transmembrane potential, and Fluorometric immunosorbent enzyme activity assay to see the changes of caspase family. The tumor bearing animal model was also set up to study the anti-tumor effect in vivo by30ns,40KV/cm, and100pulses.RESULTS:In vitro, nsPEFs inhibit the cell viability, as well as the ability of cell invasion obviously and induce cell apoptosis, expressed by the results of CCK-8assay that cell inhibition rate in treated groups after24h,48h,72h is20KV/cm,71.78%,78.60%,82.13%;40KV/cm,80.92%,89.16%,92.13%;60KV/cm,82.94%90.70%,92.95%, with a significant statistically compared with control group inhibition rate(P<0.01); It also expressed by forming DNA fragmentation, increasing TUNEL positive cells, presenting mitochondria degeneration. Flow cytometer showed that nsPEFs could inhibit cancer cell proliferation and stop cell cycle at G2phase, with the support of morphological changes. In vivo, tumor growth in treatment group is statistically inhibited(30ns40kV/cm l00pulses3days, volume320g, compared with the control group680g, and the sham operated group620g, P0.01), but not achieved the complete elimination.CONCLUTIONS:These results suggest that nsPEFs has a positive effect on human breast cancer cell line MDA-MB-231by the way of activating caspase signaling pathway.