Apoptotic and necrotic cell death are both induced by electroporation in HL60 human promyeloid leukaemia cells

Cell death was induced by electroporation in HL60 cells, a human promyeloid leukaemia strain, in order to determine by both morphological and biochemical criteria whether necrotic or apoptotic processes occurred. Cells sampled at several times after electroporation were analyzed for the assessment of the following end-points: (i) chromosomal DNA fragmentation; (ii) cell viability; (iii) mono- and oligonucleosomes in the cytoplasmic fraction; (iv) apoptotic index; and (v) morphology of treated cells. The results indicate that about 50% of the cells killed by electroporation die through necrosis, while the remaining 50% of the cells undergo apoptosis. Chromosome damage was also studied by cytogenetic analysis at metaphase. The possibility of killing tumour cells by electroporation, as a variant of electrotherapy, constitutes, in our opinion, a promising procedure in cancer therapy, avoiding the undesirable side effects normally derived from treatment with cytotoxic drugs.