Voltage dependent anion channel-1 regulates death receptor mediated apoptosis by enabling cleavage of caspase-8

Queen's University Belfast, Centre for Cancer Research and Cell Biology, Belfast, UK.
BMC Cancer (Impact Factor: 3.36). 07/2010; 10(1, article 380):380. DOI: 10.1186/1471-2407-10-380
Source: PubMed


Activation of the extrinsic apoptosis pathway by tumour necrosis factor related apoptosis inducing ligand (TRAIL) is a novel therapeutic strategy for treating cancer that is currently under clinical evaluation. Identification of molecular biomarkers of resistance is likely to play an important role in predicting clinical anti tumour activity. The involvement of the mitochondrial type 1 voltage dependent anion channel (VDAC1) in regulating apoptosis has been highly debated. To date, a functional role in regulating the extrinsic apoptosis pathway has not been formally excluded.
We carried out stable and transient RNAi knockdowns of VDAC1 in non-small cell lung cancer cells, and stimulated the extrinsic apoptotic pathway principally by incubating cells with the death ligand TRAIL. We used in-vitro apoptotic and cell viability assays, as well as western blot for markers of apoptosis, to demonstrate that TRAIL-induced toxicity is VDAC1 dependant. Confocal microscopy and mitochondrial fractionation were used to determine the importance of mitochondria for caspase-8 activation.
Here we show that either stable or transient knockdown of VDAC1 is sufficient to antagonize TRAIL mediated apoptosis in non-small cell lung cancer (NSCLC) cells. Specifically, VDAC1 is required for processing of procaspase-8 to its fully active p18 form at the mitochondria. Loss of VDAC1 does not alter mitochondrial sensitivity to exogenous caspase-8-cleaved BID induced mitochondrial depolarization, even though VDAC1 expression is essential for TRAIL dependent activation of the intrinsic apoptosis pathway. Furthermore, expression of exogenous VDAC1 restores the apoptotic response to TRAIL in cells in which endogenous VDAC1 has been selectively silenced.
Expression of VDAC1 is required for full processing and activation of caspase-8 and supports a role for mitochondria in regulating apoptosis signaling via the death receptor pathway.

Download full-text


Available from: Ian Paul
  • Source
    • "VDAC plays a major role in mitochondria mediated apoptosis [3] [6] [16] [17]. Several anti-apoptotic and pro-apoptotic proteins as well as chemicals are known to target VDAC [18] [19] [20]. Intra-mitochondrial calcium overload mediated by VDAC, triggers the formation of permeability transition pore (PTP). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Voltage dependent anion channel (VDAC) of mitochondria plays a crucial role in apoptosis. Human VDAC-1, reconstituted in planar lipid bilayer showed reduced conductance when treated with curcumin. Curcumin interacts with residues in the α helical N-terminus of VDAC and in the channel wall, as revealed by molecular docking, followed by mutational analysis. N-terminus mimicking peptide showed conformational changes in circular dichroism, upon curcumin treatment. We propose that the interaction of curcumin with amino acids in N-terminus and in channel wall fixes the α helix in closed conformation. This restricts its movement which is required for the opening of the channel.
    Full-text · Article · Jan 2015 · Biochimica et Biophysica Acta (BBA) - Biomembranes
  • Source
    • "Voltage-dependent anion-selective channel protein 1 (VDAC) is a mitochondrial outer membrane protein that regulates ATP/ADP exchange and respiratory control [47]. VDAC has been shown to be proapoptotic by regulation of Bak and Bax [48] as well as activation of caspase-8 to induce extrinsic apoptosis pathway [49]. Thus, we believe that up-regulation of VDAC by Phyllanthus extracts was able to initiate apoptotic cell death in PC-3 cells (Table 2, Group IV). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Phyllanthus is a traditional medicinal plant that has been found to have antihepatitis, antibacterial, and anticancer properties. The present studies were to investigate the in vitro molecular mechanisms of anticancer effects of Phyllanthus (P. amarus, P. niruri, P. urinaria, and P. watsonii) plant extracts in human prostate adenocarcinoma. The cancer ten-pathway reporter array was performed and revealed that the expression of six pathway reporters were significantly decreased (Wnt, NFκB, Myc/Max, hypoxia, MAPK/ERK, and MAPK/JNK) in PC-3 cells after treatment with Phyllanthus extracts. Western blot was conducted and identified several signalling molecules that were affected in the signalling pathways including pan-Ras, c-Raf, RSK, Elk1, c-Jun, JNK1/2, p38 MAPK, c-myc, DSH, β-catenin, Akt, HIF-1α, GSK3β, NFκB p50 and p52, Bcl-2, Bax, and VEGF, in treated PC-3 cells. A proteomics-based approach, 2D gel electrophoresis, was performed, and mass spectrometry (MS/MS) results revealed that there were 72 differentially expressed proteins identified in treated PC-3 cells and were involved in tumour cell adhesion, apoptosis, glycogenesis and glycolysis, metastasis, angiogenesis, and protein synthesis and energy metabolism. Overall, these findings suggest that Phyllanthus can interfere with multiple signalling cascades involved in tumorigenesis and be used as a potential therapeutic candidate for treatment of cancer.
    Full-text · Article · Apr 2013 · Evidence-based Complementary and Alternative Medicine
  • Source
    • "et al. 2008). In intracellular organelles, they modulate the concentration of ions and play important roles in physiological events such as the voltage-dependent anion channel (VDAC) in apoptosis (Chacko et al. 2010 "
    [Show abstract] [Hide abstract]
    ABSTRACT: The large conductance calcium- and voltage-activated potassium channel (BKCa) is widely expressed at the plasma membrane. This channel is involved in a variety of fundamental cellular functions including excitability, smooth muscle contractility, and Ca2+ homeostasis, as well as in pathological situations like proinflammatory responses in rheumatoid arthritis, and cancer cell proliferation. Immunological, biochemical and pharmacological studies from over a decade have intermittently shown the presence of BKCa in intracellular organelles. To date, intracellular BKCa (iBKCa) has been localized in the mitochondria, endoplasmic reticulum, nucleus and Golgi apparatus but its functional role remains largely unknown except for the mitochondrial BKCa whose opening is thought to play a role in protecting the heart from ischemic injury. In the nucleus, pharmacology suggests a role in regulating nuclear Ca2+, membrane potential and eNOS expression. Establishing the molecular correlates of iBKCa, the mechanisms defining iBKCa organelle-specific targeting, and their modulation are challenging questions. This review summarizes iBKCa channels, their possible functions, and efforts to identify their molecular correlates.
    Full-text · Article · Aug 2012 · The Journal of Physiology
Show more