Arsenic trioxide induces autophagic cell death in malignant glioma cells by upregulation of mitochondrial cell death protein BNIP3

Abstract

Arsenic trioxide (As 2 O 3 ) has shown considerable efficacy in treating hematological malignancies with induction of programmed cell death (PCD) type I, apoptosis. However, the mechanisms underlying the antitumor effect of As 2 O 3 on solid tumors are poorly defined. Previously, we reported that As 2 O 3 induced autophagic cell death (PCD type II) but not apoptosis in human malignant glioma cell lines. The purpose of this study was to elucidate the molecular pathway leading to autophagic cell death. In this study, we demonstrated that the cell death was accompanied by involvement of autophagy-specific marker, microtubule-associated protein light chain 3 (LC3), and damage of mitochondrial membrane integrity, but not by caspase activation. Analysis by cDNA microarray, RT-PCR, and Western blot showed that cell death members of Bcl-2 family, Bcl-2/adenovirus E1B 19-kDa-interacting protein 3 (BNIP3) and its homologue BNIP3-like (BNIP3L), were upregulated in As 2 O 3 -induced autophagic cell death. Exogenous expression of BNIP3, but not BNIP3L, induced autophagic cell death in malignant glioma cells without As 2 O 3 treatment. When upregulation of BNIP3 induced by As 2 O 3 was suppressed by a dominant-negative effect of the transmembranedeleted BNIP3 (BNIP3DTM), autophagic cell death was inhibited. In contrast, BNIP3 transfection augmented As 2 O 3 -induced autophagic cell death. These results suggest that BNIP3 plays a central role in As 2 O 3 -induced autophagic cell death in malignant glioma cells. This study adds a new concept to characterize the pathways by which As 2 O 3 acts to induce autophagic cell death in malignant glioma cells. Oncogene (2005) 24, 980-991.

BNIP3 protects HepG2 cells against etoposide-induced cell death under hypoxia by an autophagy-independent pathway

“…We observed that autophagy was enhanced by etoposide. The upregulation of autophagy by chemotherapeutic drugs has already been described [42][43][44][45][46][47]. Chemotherapyinduced autophagy may promote cell resistance against it.…”

“…Many studies have reported that BNIP3 expression induces cell death with features that are both consistent and inconsistent with apoptosis suggesting that BNIP3 induces cell death through multiple pathways including apoptosis, necrosis and autophagy according to cell lines and conditions [13][14][15]44]. Indeed, BNIP3-induced cell death is related to mitochondrial dysfunction, membrane depolarization, permeability transition pore opening and increased generation of ROS according to the experimental conditions.…”

“…Examples of autophagic cell death in response to chemotherapy were also described. Vitamin D analogue, EB1089, kills MCF7 through the induction of massive autophagy [43] while arsenic trioxide induces autophagic cell death in human malignant A c c e p t e d M a n u s c r i p t 17 glioma cell lines [44]. Autophagic cell death is also an alternative cell death pathway to apoptosis when it is no longer functional.…”

Silencing mammalian target of rapamycin signaling by small interfering RNA enhances rapamycin-induced autophagy in malignant glioma cells

“…GFP-LC3-expressing cells have been successfully used to demonstrate induction of autophagy by amino-acid deprivation or anticancer treatments (Kabeya et al, 2000;Mizushima et al, 2001;Kanzawa et al, 2005). GFP-LC3 cells present a diffuse distribution under control conditions, whereas a punctate pattern of GFP-LC3 expression (GFP-LC3 dots) is induced by autophagy.…”

“…GFP-LC3 cells present a diffuse distribution under control conditions, whereas a punctate pattern of GFP-LC3 expression (GFP-LC3 dots) is induced by autophagy. In the current study, we determined the prevalence of autophagic cells (i.e., cells expressing GFP-LC3 dots) by using the GFP-LC3 expression vector kindly provided by Dr Noboru Mizushima (Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan), as described previously (Daido et al, 2005;Kanzawa et al, 2005). Tumor cells were transiently transfected with this vector by using Fugene 6 transfection reagent (Roche).…”