Activation of caspases and apoptosis in response to low-voltage electric pulses

Abstract

Abstract. Few studies have examined apoptosis induced by low-voltage electric pulses (LVEPs). LVEP-induce changes in membrane potential that are below the membrane breakdown threshold and increase membrane permeability without electroporation (pore formation) through the transport of extracellular substances via phagocytosis. We demonstrated that propidium iodide uptake and apoptosis increased in accordance with the duration and number of LVEPs in B16 cells, which showed relatively good viability under mild electric field conditions. We showed that LVEP-induced apoptosis was achieved through caspase-8 and -9 activation and subsequent caspase-3 activation. Long-duration LVEPs caused only mild cell damage, such that the apoptosis ratio (apoptosis/total cell death) in electric pulse-treated cells was similar to that in non-treated control cells. To assess the relative degree of caspase dependency in LVEP-induced apoptosis, the apoptosis rate and caspase-3 activity were analyzed using a pan-caspase inhibitor (Z-VAD-FMK). Z-VAD-FMK treatment inhibited, but did not abolish, LVEP-induced apoptosis, indicating that caspases other than caspase-3 participate in this pathway. Moreover, LVEP treatment inhibited cell growth, suggesting that LVEP treatment may be a valuable anticancer therapy. Although the mechanism of LVEP-induced apoptosis remains unclear, it may be related to dysfunctional membrane transport of Ca 2+ and other extracellular substances involved in caspase activation.

Adoptive Antitumor Immunotherapy In Vitro and In Vivo Using Genetically Activated erbB2-specific T Cells

“…36 Given the fact that apoptosis is the main reason of cell death after electroporation, we can add caspase inhibitors in the recovery medium. 37 As PTLs are primary cells with a limited life span, increased concentration of FBS, IL-2, and OKT3 were added during G418 selection. 38 According to the results reported, during the generation of PTLs, it could be better to add irradiated allogeneic PBMC feeder cells or irradiated allogeneic EBV-transformed lymphoblastoid cell line cells.…”

Gene Therapy of Malignant Solid Tumors by Targeting erbB2 Receptors and by Activating T Cells

“…32 Given to the fact that apoptosis is the main death of cells after electroporation, we can add a caspase inhibitor in the recovery medium. 33 For PTLs are primary cells with a short life span, during G418 selection, IL-2 and OKT3 were added every other day, 34 and FBS concentration was increased to 15%-20%. According to the reported, during the generation of PTLs, it could be a better choice to add irradiated allogeneic PBMC feeder cells or irradiated allogeneic EBV-transformed lymphoblastoid cell line cells.…”

Addition of novel degenerate electrical waveform stimulation with photodynamic therapy significantly enhances its cytotoxic effect in keloid fibroblasts: First report of a potential combination therapy

“…Cas pas e-3 death cascade by ES mainly causing a dysfunctional ER membrane followed by caspase activation [29]. Application of DW may have a cumulative effect on the already activated apoptotic/necrotic pathways and hence further lead to enhancement of cell death.…”