Irreversible Electroporation Mediates Glioma Apoptosis via Upregulation of <i>AP-1</i> and <i>Bim</i>: Transcriptome Evidence

Abstract

The heat-sink effect and thermal damage of conventional thermal ablative technologies can be minimized by irreversible electroporation (IRE), which results in clear ablative boundaries and conservation of blood vessels, facilitating maximal safe surgical resection for glioblastoma. Although much comparative data about the death forms in IRE have been published, the comprehensive genetic regulatory mechanism for apoptosis, among other forms of regulatory cell death (RCD), remains elusive. We investigated the electric field intensity threshold for apoptosis/necrosis (YO-PRO-1/PI co-staining) of the U251 human malignant glioma cell line with stepwise increased uniform field intensity. Time course samples (0–6 h) of apoptosis induction and sham treatment were collected for transcriptome sequencing. Sequencing showed that transcription factor AP-1 and its target gene Bim (Bcl2l11), related to the signaling pathway, played a major role in the apoptosis of glioma after IRE. The sequencing results were confirmed by qPCR and Western blot. We also found that the transcription changes also implicated three other forms of RCD: autophagy, necroptosis, and immunogenic cell death (ICD), in addition to apoptosis. These together imply that IRE possibly mediates apoptosis by the AP-1-Bim pathway, causes mixed RCD simultaneously, and has the potential to aid in the generation of a systemic antitumor immune response.

Keywords

• irreversible electroporation
• glioma
• apoptosis
• regulatory cell death
• <i>AP-1</i>
• <i>FOS</i>