AIFM1

Gene Summary

Gene:AIFM1; apoptosis inducing factor mitochondria associated 1
Aliases: AIF, CMT2D, CMTX4, COWCK, DFNX5, NADMR, NAMSD, PDCD8, COXPD6
Location:Xq26.1
Summary:This gene encodes a flavoprotein essential for nuclear disassembly in apoptotic cells, and it is found in the mitochondrial intermembrane space in healthy cells. Induction of apoptosis results in the translocation of this protein to the nucleus where it affects chromosome condensation and fragmentation. In addition, this gene product induces mitochondria to release the apoptogenic proteins cytochrome c and caspase-9. Mutations in this gene cause combined oxidative phosphorylation deficiency 6 (COXPD6), a severe mitochondrial encephalomyopathy, as well as Cowchock syndrome, also known as X-linked recessive Charcot-Marie-Tooth disease-4 (CMTX-4), a disorder resulting in neuropathy, and axonal and motor-sensory defects with deafness and mental retardation. Alternative splicing results in multiple transcript variants. A related pseudogene has been identified on chromosome 10. [provided by RefSeq, Aug 2015]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:apoptosis-inducing factor 1, mitochondrial
Source:NCBIAccessed: 13 March, 2017

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 13 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Mitochondria
  • Messenger RNA
  • X Chromosome
  • Sesquiterpenes
  • Cytochromes c
  • Cell Survival
  • Reactive Oxygen Species
  • Protein-Serine-Threonine Kinases
  • Prostate Cancer
  • Membrane Potential, Mitochondrial
  • DNA Fragmentation
  • Drug Synergism
  • RNA Interference
  • Active Transport, Cell Nucleus
  • Caspase 3
  • Transfection
  • Cancer Gene Expression Regulation
  • Cell Nucleus
  • Liver Cancer
  • siRNA
  • Cancer DNA
  • Single Nucleotide Polymorphism
  • Down-Regulation
  • RTPCR
  • BCL2 protein
  • p53 Protein
  • Cell Death
  • Protein Transport
  • Membrane Proteins
  • Apoptosis Inducing Factor
  • Bladder Cancer
  • Flavoproteins
  • Antineoplastic Agents
  • Western Blotting
  • Poly (ADP-Ribose) Polymerase-1
  • Disease Progression
  • Apoptosis
  • bcl-2-Associated X Protein
  • Caspases
  • Dose-Response Relationship, Drug
  • Enzyme Activation
Tag cloud generated 13 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: AIFM1 (cancer-related)

Liu KC, Shih TY, Kuo CL, et al.
Sulforaphane Induces Cell Death Through G2/M Phase Arrest and Triggers Apoptosis in HCT 116 Human Colon Cancer Cells.
Am J Chin Med. 2016; 44(6):1289-1310 [PubMed] Related Publications
Sulforaphane (SFN), an isothiocyanate, exists exclusively in cruciferous vegetables, and has been shown to possess potent antitumor and chemopreventive activity. However, there is no available information that shows SFN affecting human colon cancer HCT 116 cells. In the present study, we found that SFN induced cell morphological changes, which were photographed by contrast-phase microscopy, and decreased viability. SFN also induced G2/M phase arrest and cell apoptosis in HCT 116 cells, which were measured with flow cytometric assays. Western blotting indicated that SFN increased Cyclin A, cdk 2, Cyclin B and WEE1, but decreased Cdc 25C, cdk1 protein expressions that led to G2/M phase arrest. Apoptotic cell death was also confirmed by Annexin V/PI and DAPI staining and DNA gel electrophoresis in HCT 116 cells after exposure to SFN. The flow cytometric assay also showed that SFN induced the generation of reactive oxygen species (ROS) and Ca[Formula: see text] and decreased mitochondria membrane potential and increased caspase-8, -9 and -3 activities in HCT 116 cell. Western blotting also showed that SFN induced the release of cytochrome c, and AIF, which was confirmed by confocal microscopy examination. SFN induced ER stress-associated protein expression. Based on those observations, we suggest that SFN may be used as a novel anticancer agent for the treatment of human colon cancer in the future.

Jagadish N, Gupta N, Agarwal S, et al.
Sperm-associated antigen 9 (SPAG9) promotes the survival and tumor growth of triple-negative breast cancer cells.
Tumour Biol. 2016; 37(10):13101-13110 [PubMed] Related Publications
Recently, we demonstrated the association of sperm-associated antigen 9 (SPAG9) expression with breast cancer. Among breast cancer, 15 % of the cancers are diagnosed as triple-negative breast cancers (TNBC) based on hormone receptor status and represent an important clinical challenge because of lack of effective available targeted therapy. Therefore, in the present investigation, plasmid-based small hairpin (small hairpin RNA (shRNA)) approach was used to ablate SPAG9 in aggressive breast cancer cell line model (MDA-MB-231) in order to understand the role of SPAG9 at molecular level in apoptosis, cell cycle, and epithelial-to-mesenchymal transition (EMT) signaling. Our data in MDA-MB-231 cells showed that ablation of SPAG9 resulted in membrane blebbing, increased mitochondrial membrane potential, DNA fragmentation, phosphatidyl serine surface expression, and caspase activation. SPAG9 depletion also resulted in cell cycle arrest in G0-G1 phase and induced cellular senescence. In addition, in in vitro and in vivo xenograft studies, ablation of SPAG9 resulted in upregulation of p21 along with pro-apoptotic molecules such as BAK, BAX, BIM, BID, NOXA, AIF, Cyto-C, PARP1, APAF1, Caspase 3, and Caspase 9 and epithelial marker, E-cadherin. Also, SPAG9-depleted cells showed downregulation of cyclin B1, cyclin D1, cyclin E, CDK1, CDK4, CDK6, BCL2, Bcl-xL, XIAP, cIAP2, MCL1, GRP78, SLUG, SNAIL, TWIST, vimentin, N-cadherin, MMP2, MMP3, MMP9, SMA, and β-catenin. Collectively, our data suggests that SPAG9 promotes tumor growth by inhibiting apoptosis, altering cell cycle, and enhancing EMT signaling in in vitro cells and in vivo mouse model. Hence, SPAG9 may be a potential novel target for therapeutic use in TNBC treatment.

Scott AJ, Wilkinson AS, Wilkinson JC
Basal metabolic state governs AIF-dependent growth support in pancreatic cancer cells.
BMC Cancer. 2016; 16:286 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Apoptosis-inducing factor (AIF), named for its involvement in cell death pathways, is a mitochondrial protein that regulates metabolic homeostasis. In addition to supporting the survival of healthy cells, AIF also plays a contributory role to the development of cancer through its enzymatic activity, and we have previously shown that AIF preferentially supports advanced-stage prostate cancer cells. Here we further evaluated the role of AIF in tumorigenesis by exploring its function in pancreatic cancer, a disease setting that most often presents at an advanced stage by the time of diagnosis.
METHODS: A bioinformatics approach was first employed to investigate AIF mRNA transcript levels in pancreatic tumor specimens vs. normal tissues. AIF-deficient pancreatic cancer cell lines were then established via lentiviral infection. Immunoblot analysis was used to determine relative protein quantities within cells. Cell viability was measured by flow cytometry; in vitro and Matrigel™ growth/survival using Coulter™ counting and phase contrast microscopy; and glucose consumption in the absence and presence of Matrigel™ using spectrophotometric methods.
RESULTS: Archival gene expression data revealed a modest elevation of AIF transcript levels in subsets of pancreatic tumor specimens, suggesting a possible role in disease progression. AIF expression was then suppressed in a panel of five pancreatic cancer cell lines that display diverse metabolic phenotypes. AIF ablation selectively crippled the growth of cells in vitro in a manner that directly correlated with the loss of mitochondrial respiratory chain subunits and altered glucose metabolism, and these effects were exacerbated in the presence of Matrigel™ substrate. This suggests a critical metabolic role for AIF to pancreatic tumorigenesis, while the spectrum of sensitivities to AIF ablation depends on basal cellular metabolic phenotypes.
CONCLUSIONS: Altogether these data indicate that AIF supports the growth and survival of metabolically defined pancreatic cancer cells and that this metabolic function may derive from a novel mechanism so far undocumented in other cancer types.

Savva CG, Totokotsopoulos S, Nicolaou KC, et al.
Selective activation of TNFR1 and NF-κB inhibition by a novel biyouyanagin analogue promotes apoptosis in acute leukemia cells.
BMC Cancer. 2016; 16:279 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Acquired resistance towards apoptosis is a hallmark of cancer. Elimination of cells bearing activated oncogenes or stimulation of tumor suppressor mediators may provide a selection pressure to overcome resistance. KC-53 is a novel biyouyanagin analogue known to elicit strong anti-inflammatory and anti-viral activity. The current study was designed to evaluate the anticancer efficacy and molecular mechanisms of KC-53 against human cancer cells.
METHODS: Using the MTT assay we examined initially how KC-53 affects the proliferation rates of thirteen representative human cancer cell lines in comparison to normal peripheral blood mononuclear cells (PBMCs) and immortalized cell lines. To decipher the key molecular events underlying its mode of action we selected the human promyelocytic leukemia HL-60 and the acute lymphocytic leukemia CCRF/CEM cell lines that were found to be the most sensitive to the antiproliferative effects of KC-53.
RESULTS: KC-53 promoted rapidly and irreversibly apoptosis in both leukemia cell lines at relatively low concentrations. Apoptosis was characterized by an increase in membrane-associated TNFR1, activation of Caspase-8 and proteolytic inactivation of the death domain kinase RIP1 indicating that KC-53 induced mainly the extrinsic/death receptor apoptotic pathway. Regardless, induction of the intrinsic/mitochondrial pathway was also achieved by Caspase-8 processing of Bid, activation of Caspase-9 and increased translocation of AIF to the nucleus. FADD protein knockdown restored HL-60 and CCRF/CEM cell viability and completely blocked KC-53-induced apoptosis. Furthermore, KC-53 administration dramatically inhibited TNFα-induced serine phosphorylation on TRAF2 and on IκBα hindering therefore p65/NF-κΒ translocation to nucleus. Reduced transcriptional expression of pro-inflammatory and pro-survival p65 target genes, confirmed that the agent functionally inhibited the transcriptional activity of p65.
CONCLUSIONS: Our findings demonstrate, for the first time, the selective anticancer properties of KC-53 towards leukemic cell lines and provide a detailed understanding of the molecular events underlying its dual anti-proliferative and pro-apoptotic properties. These results provide new insights into the development of innovative and targeted therapies for the treatment of some forms of leukemia.

Arif T, Krelin Y, Shoshan-Barmatz V
Reducing VDAC1 expression induces a non-apoptotic role for pro-apoptotic proteins in cancer cell differentiation.
Biochim Biophys Acta. 2016; 1857(8):1228-42 [PubMed] Related Publications
Proteins initially identified as essential for apoptosis also mediate a wide range of non-apoptotic functions that include cell cycle progression, differentiation and metabolism. As this phenomenon was mostly reported with non-cancer cells, we considered non-conventional roles for the apoptotic machinery in the cancer setting. We found that treating glioblastoma (GBM) tumors with siRNA against VDAC1, a mitochondrial protein found at the crossroads of metabolic and survival pathways and involved in apoptosis, inhibited tumor growth while leading to differentiation of tumor cells into neuronal-like cells, as reflected in the expression of specific markers. Although VDAC1 depletion did not induce apoptosis, the expression levels of several pro-apoptotic regulatory proteins were changed. Specifically, VDAC1 deletion led to up-regulation of caspases, p53, cytochrome c, and down-regulation of SMAC/Diablo, AIF and TSPO. The down-regulated group was highly expressed in U-87MG xenografts, as well as in GBMs from human patients. We also showed that the rewired cancer-cell metabolism resulting from VDAC1 depletion reinforced cell growth arrest and differentiation via alterations in the transcription factors p53, c-Myc, HIF-1α and NF-κB. The decrease in c-Myc, HIF-1α and NF-κB levels was in accord with reduced cell proliferation, whereas increased p53 expression promoted differentiation. Thus, upon metabolic re-programing induced by VDAC1 depletion, the levels of pro-apoptotic proteins associated with cell growth decreased, while those connected to cell differentiation increased, converting GBM cells into astrocyte- and neuron-like cells. The results reveal that in tumors, pro-apoptotic proteins can perform non-apoptotic functions, acting as regulators of cell growth and differentiation, making these molecules potential new targets for cancer therapy. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.

Santos S, Silva AM, Matos M, et al.
Copper induced apoptosis in Caco-2 and Hep-G2 cells: Expression of caspases 3, 8 and 9, AIF and p53.
Comp Biochem Physiol C Toxicol Pharmacol. 2016 Jul-Aug; 185-186:138-46 [PubMed] Related Publications
Copper (Cu) is an essential trace metal needed to ensure cell function. However, when present at high concentrations it becomes toxic to organisms. Cell death, induced by toxic levels of copper, was previously observed in in vitro studies. However, there is no consensus about the cell death pathway induced by Cu and it is still not known whether this occurs as a result of the direct action of the metal or by indirect effects. In the present work, we intend to identify the influence of different Cu concentrations in the induction of apoptosis and to explore the potential signaling pathways, using two different in vitro cell culture models (Caco-2 and Hep-G2). Cells were exposed, during 6, 12, 24 and 48h, to Cu concentrations corresponding to IC50 and 1/8 of IC50, according to the viability assays. Then, considering the different apoptosis pathways, the expression of caspases 3, 8 and 9, apoptosis inducing factor (AIF) and p53 genes was analyzed by quantitative real time PCR. The results suggested that different Cu concentrations could trigger different apoptotic pathways, at different times of exposure. In both cell lines, apoptosis seems to be initiated by caspase independent pathway and intrinsic pathway, followed by extrinsic pathway. In conclusion, this study demonstrates that Cu induces the activation of apoptosis through caspase dependent and independent pathways, also suggesting that apoptosis activation mechanism is dependent on the concentration, time of exposure to Cu and cell type.

Samatiwat P, Prawan A, Senggunprai L, et al.
Nrf2 inhibition sensitizes cholangiocarcinoma cells to cytotoxic and antiproliferative activities of chemotherapeutic agents.
Tumour Biol. 2016; 37(8):11495-507 [PubMed] Related Publications
Nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription factor regulating antioxidant, cytoprotective, and metabolic enzymes, plays important roles in drug resistance and proliferation in cancer cells. The present study was aimed to examine the expression of Nrf2 in connection with chemotherapeutic drug sensitivity on cholangiocarcinoma (CCA) cells. The basal levels of Nrf2 protein in cytosol and nuclear fractions of CCA cells were determined using Western blot analysis. Nrf2 mRNA expression of KKU-M156 and KKU-100 cells, representatives of low and high-Nrf2-expressing CCA cells, were silenced using siRNA. After knockdown of Nrf2, the sensitivity of those cells to the cytotoxicity of cisplatin (Cis) was enhanced in association with the increased release of AIF and downregulation of Bcl-xl in both cells. Also, knockdown of Nrf2 suppressed the replicative capability of those cells in colony-forming assay and enhanced their sensitivity to antiproliferative activity of Cis and 5-fluorouracil. The chemosensitizing effect was associated with the suppressed expression of Nrf2-regulated and Cis-induced antioxidant and metabolic genes including NQO1, HO-1, GCLC, TXN, MRP2, TKT, and G6PD. In cell cycle analysis, Nrf2 knockdown cells were arrested at G0/G1 phase and combination with Cis increased the accumulation of cells at S phase. The suppression of KKU-M156 cell proliferation was associated with the downregulation of cyclin D1 and increased level of p21. Inhibition of Nrf2 could be a novel strategy in enhancing antitumor activity of chemotherapeutic agent in control of resistant cancer.

Shimizu T, Kawai J, Ouchi K, et al.
Agarol, an ergosterol derivative from Agaricus blazei, induces caspase-independent apoptosis in human cancer cells.
Int J Oncol. 2016; 48(4):1670-8 [PubMed] Related Publications
Agaricus blazei (A. blazei) is a mushroom with many biological effects and active ingredients. We purified a tumoricidal substance from A. blazei, an ergosterol derivative, and named it 'Agarol'. Cytotoxic effects of Agarol were determined by the MTT assay using A549, MKN45, HSC-3, and HSC-4 human carcinoma cell lines treated with Agarol. Apoptosis was detected by flow cytometry analysis. Reactive oxygen species (ROS) levels and mitochondria membrane potential (∆ψm) were also determined by flow cytometry. Western blot analysis was used to quantify the expression of apoptosis-related proteins. Agarol predominantly induced apoptosis in two p53-wild cell lines (A549 and MKN45) compared to the other p53-mutant cell lines (HSC-3 and HSC-4). Further mechanistic studies revealed that induction of apoptosis is associated with increased generation of ROS, reduced ∆ψm, release of apoptosis-inducing factor (AIF) from the mitochondria to the cytosol, upregulation of Bax, and downregulation of Bcl-2. Caspase-3 activities did not increase, and z-VAD-fmk, a caspase inhibitor, did not inhibit the Agarol-induced apoptosis. These findings indicate that Agarol induces caspase-independent apoptosis in human carcinoma cells through a mitochondrial pathway. The in vivo anticancer activity of Agarol was confirmed in a xenograft murine model. This study suggests a molecular mechanism by which Agarol induces apoptosis in human carcinoma cells and indicates the potential use of Agarol as an anticancer agent.

Feng J, Yan PF, Zhao HY, et al.
SIRT6 suppresses glioma cell growth via induction of apoptosis, inhibition of oxidative stress and suppression of JAK2/STAT3 signaling pathway activation.
Oncol Rep. 2016; 35(3):1395-402 [PubMed] Related Publications
Sirtuin 6 (SIRT6) is a member of the mammalian NAD+‑dependent deacetylase sirtuin family that acts to maintain genomic stability and to repress genes. SIRT6 has recently been reported to be a tumor suppressor that controls cancer metabolism, although this effect of SIRT6 is still in dispute. Moreover, the role of SIRT6 in glioma is largely unknown. In the present study, we found that overexpression of SIRT6 using an adenovirus inhibited glioma cell growth and induced marked cell injury in two glioma cell lines (U87‑MG and T98G). Fluorescent terminal deoxyribonucleotidyl transferase (TdT)‑mediated biotin‑16‑dUTP nick‑end labelling (TUNEL) assay showed that SIRT6 overexpression induced obvious apoptosis in the T98G glioma cells. Immunoblotting and immunofluorescent staining demonstrated that SIRT6 overexpression promoted the mitochondrial-to‑nuclear translocation of apoptosis‑inducing factor (AIF), a potent apoptosis inducer. Moreover, we found that SIRT6 overexpression largely reduced oxidative stress and suppressed the activation of the JAK2/STAT3 signaling pathway in glioma cells. Finally, we showed that SIRT6 mRNA and protein levels in human glioblastoma multiforme tissues were significantly lower than the levels in peritumor tissues. In summary, our data suggest that SIRT6 suppresses glioma cell growth via induction of apoptosis, inhibition of oxidative stress and inhibition of the activation of the JAK2/STAT3 signaling pathway. These results indicate that SIRT6 may be a promising therapeutic target for glioma treatment.

Jang JH, Kim JY, Sung EG, et al.
Gambogic acid induces apoptosis and sensitizes TRAIL-mediated apoptosis through downregulation of cFLIPL in renal carcinoma Caki cells.
Int J Oncol. 2016; 48(1):376-84 [PubMed] Related Publications
Gambogic acid (GA) is a natural compound derived from brownish gamboge resin that shows a range of bioactivity, such as antitumor and antimicrobial properties. Although, GA is already known to induce cell death in a variety of cancer cells, the molecular basis for GA-induced cell death in renal cancer cells is unclear. In this study, a treatment with GA induced cell death in human renal carcinoma Caki cells in a dose-dependent manner. Treatment of Caki cells with GA decreased the levels of antiapoptotic proteins, such as Bcl-2 and XIAP in a dose-dependent manner. In addition, GA decreased the expression of the cFLIPL protein, which was downregulated at the transcriptional level without any change in the levels of cFLIPs expression. z-VAD (pan-caspase inhibitor) partially blocked GA-mediated cell death. GA-induced apoptotic cell death in Caki cells is mediated partly by the AIF translocation from the mitochondria into the nucleus via a caspase-independent pathway. In contrast, N-acetylcysteine (NAC), a ROS scavenger, had no effect on GA-induced cell death. The restoration of cFLIPL attenuated GA-induced cell death in Caki cells. Furthermore, a sub-toxic dose of GA sensitized TRAIL-mediated apoptosis in Caki cells. Pretreatment with z-VAD completely blocked GA plus TRAIL-mediated apoptosis. On the contrary, pretreatment with NAC partially inhibited GA plus TRAIL-induced apoptosis. Our findings suggested that GA induces apoptosis via the downregulation of cFLIPL and sensitized TRAIL-mediated apoptosis in Caki cells.

Jagadish N, Parashar D, Gupta N, et al.
A-kinase anchor protein 4 (AKAP4) a promising therapeutic target of colorectal cancer.
J Exp Clin Cancer Res. 2015; 34:142 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Colorectal cancer (CRC) ranks third among the estimated cancer cases and cancer related mortalities in the Western world. Early detection and efficient therapy of CRC remains a major health challenge. Therefore, there is a need to identify novel tumor markers for early diagnosis and treatment of CRC.
METHODS: A-kinase anchor protein 4 (AKAP4) gene and protein expression was monitored by quantitative polymerase chain reaction (qPCR), reverse transcription (RT)-PCR and Western blotting in normal colon tissue lysate, normal colon epithelial cells and in colon cancer cell lines viz., Caco-2, COLO205, COLO320DM, HCT-15, HCT116, HT-29, SW480, and SW620. The effect of AKAP4 on cellular growth, migration and invasion abilities was studied using gene silencing approach. The role of AKAP4 in various pathways involved in cell cycle, apoptosis, senescence was investigated in in vitro and in human xenograft mouse model.
RESULTS: Our studies showed that AKAP4 gene and protein expression was expressed in all colon cancer cells while no expression was detectable in normal colon cells. Ablation of AKAP4 led to reduced cellular growth, migration, invasion and increased apoptosis and senescence of CRC cells in in vitro assays and tumor growth in human xenograft mouse. Human colon xenograft studies showed a significant decrease in the levels of cyclins B1, D and E and cyclin dependent kinases such as CDK1, CDK2, CDK4 and CDK6. Interestingly, an up-regulation in the levels of p16 and p21 was also observed. Besides, an increase in the levels of pro-apoptotic molecules AIF, APAF1, BAD, BID, BAK, BAX, PARP1, NOXA, PUMA and cyt-C and Caspase 3, 7, 8 and 9 was also found in cancer cells as well as in xenograft tissue sections. However, anti-apoptotic molecules BCL2, Bcl-xL, cIAP2, XIAP, Axin2 and Survivin were down regulated in these samples. Our data also revealed elevated expression of epithelial marker E-cadherin and down regulation of EMT markers N-cadherin, P-cadherin, SLUG, α-SMA, SNAIL, TWIST and Vimentin. Further ablation of AKAP4 resulted in the down regulation of invasion molecules matrix metalloproteinase MMP2, MMP3 and MMP9.
CONCLUSION: AKAP4 appears to be a novel CRC-associated antigen with a potential for developing as a new clinical therapeutic target.

Wang L, Hu T, Shen J, et al.
Dihydrotanshinone I induced apoptosis and autophagy through caspase dependent pathway in colon cancer.
Phytomedicine. 2015; 22(12):1079-87 [PubMed] Related Publications
BACKGROUND: Dihydrotanshinone I (DHTS) was previously reported to exhibit the most potent anti-cancer activity among several tanshinones in colon cancer cells. Its cytotoxic action was reactive oxygen species (ROS) dependent but p53 independent.
PURPOSE: To further study the anti-cancer activity of DHTS and its molecular mechanisms of action in colon cancer both in vitro and in vivo.
METHODS: Caspase activity was detected by fluorescence assay. Apoptosis was detected by flow cytometry and TUNEL assay. Protein levels were analyzed by western blotting. Knockdown of target gene was achieved by siRNA transfection. Formation of LC3B puncta and activation of caspase-3 were detected by confocal fluorescence microscope. In vivo anti-colon cancer activity of DHTS was observed in xenograft tumors in NOD/SCID mice.
RESULTS: Anti-colon cancer activity of DHTS by inducing apoptosis and autophagy was observed both in vitro and in vivo. Mitochondria mediated caspase dependent pathway was essential in DHTS-induced cytotoxicity. The apoptosis induced by DHTS was suppressed by knockdown of apoptosis inducing factor (AIF), inhibition of caspase-3/9 but was increased after knockdown of caspase-2. Meantime, knockdown of caspase-2, pretreatment with Z-VAD-fmk or NAC (N-Acety-L-Cysteine) efficiently inhibited the autophagy induced by DHTS. A crosstalk between cytochrome c and AIF was also reported.
CONCLUSION: DHTS-induced caspase and ROS dependent apoptosis and autophagy were mediated by mitochondria in colon cancer. DHTS could be a promising leading compound for the development of anti-tumor agent or be developed as an adjuvant drug for colon cancer therapy.

Wang J, Li Y, Liu Y, et al.
Overexpression of truncated AIF regulated by Egr1 promoter radiation-induced apoptosis on MCF-7 cells.
Radiat Environ Biophys. 2015; 54(4):413-21 [PubMed] Related Publications
It has been demonstrated that gene-radiotherapy can improve the radiotherapy by selectively increasing cells' response to ionizing radiation. Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein, and its C-terminal domain is responsible for the proapoptotic activity. In the present study, we overexpressed truncated AIF on MCF-7 cells by transfection of pcDNA3.1-tAIF (pc-tAIF) and pcDNA3.1-Egr1-tAIF (pc-Egr1-tAIF) plasmids. After MCF-7-tAIF cells were exposed to X-rays, the AIF and tAIF expressions, cell proliferation, apoptosis, cell cycle invasion, cytochrome c (Cyt c) release and activation of caspase-9 were measured by using Western blot, MTT assay, flow cytometry and Matrigel transwell assay, respectively. Our results showed that tAIF expression increased on time- and dose-dependent manners. Both tAIF and radiation can synergistically enhance the apoptosis, cell proliferation inhibition, cell cycle arrest and cell-invasive inhibition. In addition, tAIF overexpression and irradiation increased Cyt c release. However, only irradiation increased caspase-9 activation. Our studies indicated that tAIF overexpression might enhance apoptosis induced by radiation in MCF-7 cells.

Shen SM, Guo M, Xiong Z, et al.
AIF inhibits tumor metastasis by protecting PTEN from oxidation.
EMBO Rep. 2015; 16(11):1563-80 [PubMed] Free Access to Full Article Related Publications
Apoptosis-inducing factor (AIF) exerts dual roles on cell death and survival, but its substrates as a putative oxidoreductase and roles in tumorigenesis remain elusive. Here, we report that AIF physically interacts with and inhibits the oxidation of phosphatase and tensin homolog on chromosome ten (PTEN), a tumor suppressor susceptible for oxidation-mediated inactivation. More intriguingly, we also identify PTEN as a mitochondrial protein and the ectopic expression of mitochondrial targeting sequence-carrying PTEN almost completely inhibits Akt phosphorylation in PTEN-deficient cells. AIF knockdown causes oxidation-mediated inactivation of the lipid phosphatase activity of PTEN, with ensuing activation of Akt kinase, phosphorylation of the Akt substrate GSK-3β, and activation of β-catenin signaling in cancer cells. Through its effect on β-catenin signaling, AIF inhibits epithelial-mesenchymal transition (EMT) and metastasis of cancer cells in vitro and in orthotopically implanted xenografts. Accordingly, the expression of AIF is correlated with the survival of human patients with cancers of multiple origins. These results identify PTEN as the substrate of AIF oxidoreductase and reveal a novel function for AIF in controlling tumor metastasis.

Liang J, Piao Y, Henry V, et al.
Interferon-regulatory factor-1 (IRF1) regulates bevacizumab induced autophagy.
Oncotarget. 2015; 6(31):31479-92 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Antiangiogenic therapy is commonly being used for the treatment of glioblastoma. However, the benefits of angiogenesis inhibitors are typically transient and resistance often develops. Determining the mechanism of treatment failure of the VEGF monoclonal antibody bevacizumab for malignant glioma would provide insight into approaches to overcome therapeutic resistance.
EXPERIMENTAL DESIGN: In this study, we evaluated the effects of bevacizumab on the autophagy of glioma cells and determined target genes involving in the regulation of bevacizumab-induced autophagy.
RESULTS: We demonstrated that bevacizumab treatment increased expression of autophagy markers and autophagosome formation in cell culture experiments as well as in in vivo studies. Gene expression profile analysis performed on murine xenograft models of glioblastoma showed increased transcriptional levels of STAT1/IRF1 signaling in bevacizumab resistant tumors compared to control tumors. In vitro experiments showed that bevacizumab treatment increased IRF1 expression in a dose and time dependent manner, which was coincident with bevacizumab-mediated autophagy. Down regulation of IRF1 by shRNA blocked autophagy and increased AIF-dependent apoptosis in bevacizumab-treated glioma cells. Consistently, IRF1 depletion increased the efficacy of anti-VEGF therapy in a glioma xenograft model, which was due to less bevacizumab-promoted autophagy and increased apoptosis in tumors with down-regulated IRF1.
CONCLUSIONS: These data suggest that IRF1 may regulate bevacizumab-induced autophagy, and may be one important mediator of glioblastoma resistant to bevacizumab.

Zhang Q, Hou D, Luo Z, et al.
The novel protective role of P27 in MLN4924-treated gastric cancer cells.
Cell Death Dis. 2015; 6:e1867 [PubMed] Free Access to Full Article Related Publications
The tumor-suppressor gene cyclin-dependent kinase inhibitor 1B (P27) is downregulated in gastric cancer cells mainly through proteolytic degradation mediated by the SKP-Cullin1-F-Box (SCF) complex. But the correlation between its downregulation and gastric cancer prognosis still remains indefinite. MLN4924, an anti-tumor agent, which suppresses the SCF complex by inhibiting Cullin1 neddylation, emerges as a promising tool to elucidate its functions in gastric cancer cells. In this study, MLN4924 induced significant growth inhibition of gastric cancer cells in a dose-dependent manner, along with the simultaneous accumulation of P27 and cell cycle abnormalities such as G2/M arrest. Importantly, we found that P27 silencing in MLN4924-treated cells resulted in an enhancement of growth inhibition both in vitro and in vivo. Mechanism analysis revealed the antagonism effects of antioxidants to this excess apoptosis, suggesting reactive oxygen species (ROS) overproduction especially in the mitochondria was the principal cause of the augmentation. Moreover, the robust ROS attacked the mitochondria to initiate collapse of the mitochondrial membrane permeability and the exportation of apoptosis-inducing factor (AIF), IAP-binding mitochondrial protein (SMAC/DIABLO) and cytochrome c. Finally, we also found that P27 knockdown affected the expression profile of several critical BH3 family members to amplify the mitochondrial dysfunction and apoptosis. In summary, our findings unveiled a protective role of P27 by maintaining mitochondrial membrane permeability in MLN4924-treated gastric cancer cells, and therefore highlighted the potential combination of MLN4924 with P27 inhibition to improve its therapeutic efficacy.

Qiu X, Klausen C, Cheng JC, Leung PC
CD40 ligand induces RIP1-dependent, necroptosis-like cell death in low-grade serous but not serous borderline ovarian tumor cells.
Cell Death Dis. 2015; 6:e1864 [PubMed] Free Access to Full Article Related Publications
Ovarian high-grade serous carcinomas (HGSCs) and invasive low-grade serous carcinomas (LGSCs) are considered to be distinct entities. In particular, LGSCs are thought to arise from non-invasive serous borderline ovarian tumors (SBOTs) and show poor responsiveness to conventional chemotherapy. The pro-apoptotic effects of CD40 ligand (CD40L) have been demonstrated in HGSC, though the underlying mechanisms are not fully understood. Conversely, the therapeutic potential of the CD40L-CD40 system has yet to be evaluated in LGSC. We now show that CD40 protein is focally expressed on tumor cells in two of five primary LGSCs compared with no expression in eight primary SBOTs. Treatment with CD40L or agonistic CD40 antibody decreased the viability of LGSC-derived MPSC1 and VOA1312 cells, but not SBOT3.1 cells. Small interfering RNA (siRNA) targeting CD40 was used to show that it is required for these reductions in cell viability. CD40L treatment increased cleaved caspase-3 levels in MPSC1 cells though, surprisingly, neither pan-caspase inhibitor nor caspase-3 siRNA reversed or even attenuated CD40L-induced cell death. In addition, CD40-induced cell death was not affected by knockdown of the mitochondrial proteins apoptosis-inducing factor (AIF) and endonuclease G (EndoG). Interestingly, CD40L-induced cell death was blocked by necrostatin-1, an inhibitor of receptor-interacting protein 1 (RIP1), and attenuated by inhibitors of RIP3 (GSK'872) or MLKL (mixed lineage kinase domain-like; necrosulfonamide). Our results indicate that the upregulation of CD40 may be relatively common in LGSC and that CD40 activation induces RIP1-dependent, necroptosis-like cell death in LGSC cells.

Tiffen JC, Gunatilake D, Gallagher SJ, et al.
Targeting activating mutations of EZH2 leads to potent cell growth inhibition in human melanoma by derepression of tumor suppressor genes.
Oncotarget. 2015; 6(29):27023-36 [PubMed] Free Access to Full Article Related Publications
The epigenetic modifier EZH2 is part of the polycomb repressive complex that suppresses gene expression via histone methylation. Activating mutations in EZH2 are found in a subset of melanoma that contributes to disease progression by inactivating tumor suppressor genes. In this study we have targeted EZH2 with a specific inhibitor (GSK126) or depleted EZH2 protein by stable shRNA knockdown. We show that inhibition of EZH2 has potent effects on the growth of both wild-type and EZH2 mutant human melanoma in vitro particularly in cell lines harboring the EZH2Y646 activating mutation. This was associated with cell cycle arrest, reduced proliferative capacity in both 2D and 3D culture systems, and induction of apoptosis. The latter was caspase independent and mediated by the release of apoptosis inducing factor (AIFM1) from mitochondria. Gene expression arrays showed that several well characterized tumor suppressor genes were reactivated by EZH2 inhibition. This included activating transcription factor 3 (ATF3) that was validated as an EZH2 target gene by ChIP-qPCR. These results emphasize a critical role for EZH2 in the proliferation and viability of melanoma and highlight the potential for targeted therapy against EZH2 in treatment of patients with melanoma.

Park N, Baek HS, Chun YJ
Embelin-Induced Apoptosis of Human Prostate Cancer Cells Is Mediated through Modulation of Akt and β-Catenin Signaling.
PLoS One. 2015; 10(8):e0134760 [PubMed] Free Access to Full Article Related Publications
There is increasing evidence that embelin, an active component of Embelia ribes, induces apoptosis in human cancer cells, but the detailed mechanisms are still unclear. Here, we have investigated the effect of embelin on the growth of human prostate cancer cells. Embelin strongly inhibited cell growth especially in human prostate cancer cell lines, including PC3, DU145, LNCaP-LN3 and normal prostate epithelial cell, RWPE-1 compared to breast cancer (MDA-MB-231, MCF-7, and T47D), hepatoma (HepG2, Hep3B, and HuH-7), or choriocarcinoma (JEG-3). We observed that embelin induced apoptosis of PC3 cells in a time-dependent manner correlated with decreased expression of Bcl-2, Bcl-xL, and Mcl-1, increased translocation of Bax into mitochondria, and a reduction in the mitochondrial membrane potential. Furthermore, embelin induced voltage-dependent anion channel (VDAC) 1 expression and oligomerization, which may promote cytochrome c and AIF release. Because embelin was able to inhibit Akt activation and cyclooxygenase-2 expression, the effects on Wnt/ β-catenin signaling were determined. Embelin activated glycogen synthase kinase (GSK)-3β by preventing phosphorylation and suppressed β-catenin expression. Attenuation of β-catenin-mediated TCF transcriptional activity and gene transcription, such as cyclin D1, c-myc, and matrix metalloproteinase (MMP)-7, were shown in embelin-treated cells. The changes in β-catenin levels in response to embelin were blocked by lithium chloride, a GSK-3 inhibitor, indicating that embelin may decrease β-catenin expression via GSK-3β activation. Furthermore, exposure of PC3 cells to embelin resulted in a significant decrease in cell migration and invasion. In conclusion, these findings suggest that inhibition of Akt signaling and activation of GSK-3β partially contributes to the pro-apoptotic effect of embelin in prostate cancer cells.

Kaszuba-Zwoińska J, Ćwiklińska M, Balwierz W, et al.
Changes in cell death of peripheral blood lymphocytes isolated from children with acute lymphoblastic leukemia upon stimulation with 7 Hz, 30 mT pulsed electromagnetic field.
Cell Mol Biol Lett. 2015; 20(1):130-42 [PubMed] Related Publications
Pulsed electromagnetic field (PEMF) influenced the viability of proliferating in vitro peripheral blood mononuclear cells (PBMCs) isolated from Crohn's disease patients as well as acute myeloblastic leukemia (AML) patients by induction of cell death, but did not cause any vital changes in cells from healthy donors. Experiments with lymphoid U937 and monocytic MonoMac6 cell lines have shown a protective effect of PEMF on the death process in cells treated with death inducers. The aim of the current study was to investigate the influence of PEMF on native proliferating leukocytes originating from newly diagnosed acute lymphoblastic leukemia (ALL) patients. The effects of exposure to PEMF were studied in PBMCs from 20 children with ALL. PBMCs were stimulated with three doses of PEMF (7 Hz, 30 mT) for 4 h each with 24 h intervals. After the last stimulation, the cells were double stained with annexin V and propidium iodide dye to estimate viability by flow cytometric analysis. The results indicated an increase of annexin V positive as well as double stained annexin V and propidium iodide positive cells after exposure to threefold PEMF stimulation. A low-frequency pulsed electromagnetic field induces cell death in native proliferating cells isolated from ALL patients. The increased vulnerability of proliferating PBMCs to PEMF-induced interactions may be potentially applied in the therapy of ALL. The analysis of expression of apoptosis-related genes revealed changes in mRNA of some genes engaged in the intrinsic apoptotic pathway belonging to the Bcl-2 family and the pathway with apoptosis-inducing factor (AIF) abundance upon PEMF stimulation of PBMCs.

Zhao N, Mao Y, Han G, et al.
YM155, a survivin suppressant, triggers PARP-dependent cell death (parthanatos) and inhibits esophageal squamous-cell carcinoma xenografts in mice.
Oncotarget. 2015; 6(21):18445-59 [PubMed] Free Access to Full Article Related Publications
Here we demonstrated that sepantronium bromide (YM155), a survivin suppressant, inhibited esophageal squamous-cell carcinoma (ESCC) growth in mice bearing human ESCC xenografts without affecting body weight. In cell culture, YM155 decreased survivin levels and caused PARP-1 activation, poly-ADP polymer formation, and AIF translocation from the cytosol to the nucleus. Genetic knockdown of PARP-1 or AIF abrogated YM155-induced parthanatos cell death. Furthermore, FOS, JUN and c-MYC gene transcription, which is stimulated by activated PARP-1, was increased following YM155 treatment. Our data demonstrate that YM155 did not trigger apoptosis, but induced parthanatos, a cell death dependent on PARP-1 hyper-activation, and support clinical development of YM155 in ESCC.

Tsai CC, Chang YH, Chang CC, et al.
Induction of Apoptosis in Endometrial Cancer (Ishikawa) Cells by Pogostemon cablin Aqueous Extract (PCAE).
Int J Mol Sci. 2015; 16(6):12424-35 [PubMed] Free Access to Full Article Related Publications
Pogostemon cablin (PC) is a traditional herbal medicine used in the treatment of the common cold, nausea, diarrhea, and even for headaches and fever. However, the mechanisms underlying the anti-proliferative activity of PC in endometrial cancer (EC) cells have yet to be fully elucidated. This study investigated the anticancer effects of an aqueous extract of Pogostemon cablin (PCAE), specifically induced apoptosis in EC (Ishikawa) cells. Proliferation of EC cells following exposure to PCAE was assessed by an MTT assay. DNA content and the induction of cell cycle apoptosis were analyzed by flow cytometry (FACS Calibur). Protein caspase-3 and, -9 as well as AIF were investigated using Western blot. Our results demonstrate growth inhibition of Ishikawa cells by PCAE. Furthermore, caspase-3 activity caused PCAE-treated cell lines to accumulate in apoptosis. Gene expression profiling (GEP) results further suggest that, in addition to its known effects with regard to EC prevention, PCAE may also exert antitumor activity on established EC cells. Many previous studies have identified the chemo-preventive effects of natural plant materials and the potential role of these materials in chemotherapy. This current study used human EC Ishikawa cells to investigate the anti-tumor effects of PCAE in EC cells. Our results demonstrate that PCAE inhibits the growth of cancer cells and induces apoptosis, which suggests the potential applicability of PCAE as an antitumor agent.

Prinz C, Vasyutina E, Lohmann G, et al.
Organometallic nucleosides induce non-classical leukemic cell death that is mitochondrial-ROS dependent and facilitated by TCL1-oncogene burden.
Mol Cancer. 2015; 14:114 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Redox stress is a hallmark of the rewired metabolic phenotype of cancer. The underlying dysregulation of reactive oxygen species (ROS) is interconnected with abnormal mitochondrial biogenesis and function. In chronic lymphocytic leukemia (CLL), elevated ROS are implicated in clonal outgrowth and drug resistance. The pro-survival oncogene T-cell leukemia 1 (TCL1) is causally linked to the high threshold towards classical apoptosis in CLL. We investigated how aberrant redox characteristics and bioenergetics of CLL are impacted by TCL1 and if this is therapeutically exploitable.
METHODS: Bio-organometallic chemistry provided compounds containing a cytosine nucleobase, a metal core (ferrocene, ruthenocene, Fe(CO)3), and a 5'-CH2O-TDS substituent. Four of these metal-containing nucleoside analogues (MCNA) were tested for their efficacy and mode of action in CLL patient samples, gene-targeted cell lines, and murine TCL1-transgenic splenocytes.
RESULTS: The MCNA showed a marked and selective cytotoxicity towards CLL cells. MCNA activity was equally observed in high-risk disease groups, including those of del11q/del17p cytogenetics and of clinical fludarabine resistance. They overcame protective stromal cell interactions. MCNA-evoked PARP-mediated cell death was non-autophagic and non-necrotic as well as caspase- and P53-independent. This unconventional apoptosis involved early increases of ROS, which proved indispensible based on mitigation of MCNA-triggered death by various scavengers. MCNA exposure reduced mitochondrial respiration (oxygen consumption rate; OCR) and induced a rapid membrane depolarization (∆ΨM). These characteristics distinguished the MCNA from the alkylator bendamustine and from fludarabine. Higher cellular ROS and increased MCNA sensitivity were linked to TCL1 expression. The presence of TCL1 promoted a mitochondrial release of in part caspase-independent apoptotic factors (AIF, Smac, Cytochrome-c) in response to MCNA. Although basal mitochondrial respiration (OCR) and maximal respiratory capacity were not affected by TCL1 overexpression, it mediated a reduced aerobic glycolysis (lactate production) and a higher fraction of oxygen consumption coupled to ATP-synthesis.
CONCLUSIONS: Redox-active substances such as organometallic nucleosides can confer specific cytotoxicity to ROS-stressed cancer cells. Their P53- and caspase-independent induction of non-classical apoptosis implicates that redox-based strategies can overcome resistance to conventional apoptotic triggers. The high TCL1-oncogenic burden of aggressive CLL cells instructs their particular dependence on mitochondrial energetic flux and renders them more susceptible towards agents interfering in mitochondrial homeostasis.

Jia S, Du Z, Jiang H, et al.
Daintain/AIF-1 accelerates the activation of insulin-like growth factor-1 receptor signaling pathway in HepG2 cells.
Oncol Rep. 2015; 34(1):511-7 [PubMed] Related Publications
Daintain/allograft inflammatory factor-1 (AIF-1), as a novel inflammatory factor, has been reported to accelerate the proliferation and migration of breast cancer cells. However, the effect of daintain/AIF-1 on hepatocarcinogenesis remains unclear. In order to explore the effect of daintain/AIF-1 on the progression of hepatocellular carcinoma (HCC), enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR) were performed to examine the secretion and gene expression of (IGF)-1, IGF-2 and IGFBP-3. The expression of IGF-1R and its downstream targets was evaluated by western blotting. In addition, the proliferation and cell-cycle progression of HepG2 cells was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylterazolium bromide (MTT) and flow cytometric analysis. The results showed that HepG2 cells subjected to daintain/AIF-1 treatment revealed an obvious increase in the secretion of IGF-1 and IGF-2, and a reduction in the secretion of IGFBP-3. Moreover, daintain/AIF-1 accelerated the activation of IGF-1-induced IGF-1R and its downstream AKT signaling pathway, and subsequently promoted the activation of cyclin D1 pathway, thus accelerating the progression of the cell cycle and eventually promoting the proliferation of HepG2 cells. In conclusion, daintain/AIF-1 promoted the proliferation of HepG2 cells by accelerating the activation of IGF-1R and its downstream signaling pathway, which confirms that daintain/AIF-1 plays a crucial role in the development of HCC.

Shen K, Xie J, Wang H, et al.
Cambogin Induces Caspase-Independent Apoptosis through the ROS/JNK Pathway and Epigenetic Regulation in Breast Cancer Cells.
Mol Cancer Ther. 2015; 14(7):1738-49 [PubMed] Related Publications
Cambogin is a polycyclic polyprenylated acylphoroglucinol (PPAP) from the Garcinia genus, which has been used traditionally for cancer treatment across Southeastern Asia. In this study, we found that cambogin inhibited breast cancer cell proliferation and induced cell apoptosis in vitro. Cambogin induced the activation of the caspase-independent mitochondrial apoptotic pathway, as indicated by an increase in the ratio of Bax/Bcl-2 and the nuclear translocation of apoptosis inducing factor (AIF). Two-dimensional gel electrophoresis and mass spectrometry revealed that the expression of proteins involving in the radical oxygen species (ROS) pathway was among the most affected upon cambogin treatment. Cambogin enhanced cellular ROS production, and induced the activation of the ASK1-MKK4/MKK7-JNK/SAPK signaling pathway. Pretreatment with ROS scavenger N-acetylcysteine (NAC), an antioxidant, or the JNK inhibitor SP600125 was able to restore cell viability in the presence of cambogin. Importantly, cambogin treatment led to the activation of activating transcription factor-2 (ATF-2) and the trimethylation of histone H3K9 in the activator protein 1 (AP-1) binding region of the Bcl-2 gene promoter. Finally, cambogin exhibited a potential antitumor effect in MCF-7 breast cancer xenografts without apparent toxicity. Taken in conjunction, the present study indicates that cambogin can induce breast adenocarcinoma cell apoptosis and therefore represents therapeutic potential for cancer treatment.

Gou WF, Yang XF, Shen DF, et al.
The roles of BTG3 expression in gastric cancer: a potential marker for carcinogenesis and a target molecule for gene therapy.
Oncotarget. 2015; 6(23):19841-67 [PubMed] Free Access to Full Article Related Publications
BTG (B-cell translocation gene) can inhibit cell proliferation, metastasis and angiogenesis, cell cycle progression, and induce differentiation in various cells. Here, we found that BTG3 overexpression inhibited proliferation, induced S/G2 arrest, differentiation, autophagy, apoptosis, suppressed migration and invasion in MKN28 and MGC803 cells (p < 0.05). BTG3 transfectants showed a higher mRNA expression of p27, Bax, 14-3-3, Caspase-3, Caspase-9, Beclin 1, NF-κB, IL-1, -2, -4, -10 and -17, but a lower mRNA expression of p21, MMP-9 and VEGF than the control and mock (p < 0.05). At protein level, BTG3 overexpression increased the expression of CDK4, AIF, LC-3B, Beclin 1 and p38 (p < 0.05), but decreased the expression of p21 and β-catenin in both transfectants (p < 0.05). After treated with cisplatin, MG132, paclitaxel and SAHA, both BTG3 transfectants showed lower viability and higher apoptosis than the control in both time- and dose-dependent manners (p < 0.05). BTG3 expression was restored after 5-aza-2'-deoxycytidine or MG132 treatment in gastric cancer cells. BTG3 expression was decreased in gastric cancer in comparison to the adjacent mucosa (p < 0.05), and positively correlated with venous invasion and dedifferentiation of cancer (p < 0.05). It was suggested that BTG3 expression might contribute to gastric carcinogenesis. BTG3 overexpression might reverse the aggressive phenotypes and be employed as a potential target for gene therapy of gastric cancer.

Mi YJ, Geng GJ, Zou ZZ, et al.
Dihydroartemisinin inhibits glucose uptake and cooperates with glycolysis inhibitor to induce apoptosis in non-small cell lung carcinoma cells.
PLoS One. 2015; 10(3):e0120426 [PubMed] Free Access to Full Article Related Publications
Despite recent advances in the therapy of non-small cell lung cancer (NSCLC), the chemotherapy efficacy against NSCLC is still unsatisfactory. Previous studies show the herbal antimalarial drug dihydroartemisinin (DHA) displays cytotoxic to multiple human tumors. Here, we showed that DHA decreased cell viability and colony formation, induced apoptosis in A549 and PC-9 cells. Additionally, we first revealed DHA inhibited glucose uptake in NSCLC cells. Moreover, glycolytic metabolism was attenuated by DHA, including inhibition of ATP and lactate production. Consequently, we demonstrated that the phosphorylated forms of both S6 ribosomal protein and mechanistic target of rapamycin (mTOR), and GLUT1 levels were abrogated by DHA treatment in NSCLC cells. Furthermore, the upregulation of mTOR activation by high expressed Rheb increased the level of glycolytic metabolism and cell viability inhibited by DHA. These results suggested that DHA-suppressed glycolytic metabolism might be associated with mTOR activation and GLUT1 expression. Besides, we showed GLUT1 overexpression significantly attenuated DHA-triggered NSCLC cells apoptosis. Notably, DHA synergized with 2-Deoxy-D-glucose (2DG, a glycolysis inhibitor) to reduce cell viability and increase cell apoptosis in A549 and PC-9 cells. However, the combination of the two compounds displayed minimal toxicity to WI-38 cells, a normal lung fibroblast cell line. More importantly, 2DG synergistically potentiated DHA-induced activation of caspase-9, -8 and -3, as well as the levels of both cytochrome c and AIF of cytoplasm. However, 2DG failed to increase the reactive oxygen species (ROS) levels elicited by DHA. Overall, the data shown above indicated DHA plus 2DG induced apoptosis was involved in both extrinsic and intrinsic apoptosis pathways in NSCLC cells.

Shoshan-Barmatz V, Ben-Hail D, Admoni L, et al.
The mitochondrial voltage-dependent anion channel 1 in tumor cells.
Biochim Biophys Acta. 2015; 1848(10 Pt B):2547-75 [PubMed] Related Publications
VDAC1 is found at the crossroads of metabolic and survival pathways. VDAC1 controls metabolic cross-talk between mitochondria and the rest of the cell by allowing the influx and efflux of metabolites, ions, nucleotides, Ca2+ and more. The location of VDAC1 at the outer mitochondrial membrane also enables its interaction with proteins that mediate and regulate the integration of mitochondrial functions with cellular activities. As a transporter of metabolites, VDAC1 contributes to the metabolic phenotype of cancer cells. Indeed, this protein is over-expressed in many cancer types, and silencing of VDAC1 expression induces an inhibition of tumor development. At the same time, along with regulating cellular energy production and metabolism, VDAC1 is involved in the process of mitochondria-mediated apoptosis by mediating the release of apoptotic proteins and interacting with anti-apoptotic proteins. The engagement of VDAC1 in the release of apoptotic proteins located in the inter-membranal space involves VDAC1 oligomerization that mediates the release of cytochrome c and AIF to the cytosol, subsequently leading to apoptotic cell death. Apoptosis can also be regulated by VDAC1, serving as an anchor point for mitochondria-interacting proteins, such as hexokinase (HK), Bcl2 and Bcl-xL, some of which are also highly expressed in many cancers. By binding to VDAC1, HK provides both a metabolic benefit and apoptosis-suppressive capacity that offer the cell a proliferative advantage and increase its resistance to chemotherapy. Thus, these and other functions point to VDAC1 as an excellent target for impairing the re-programed metabolism of cancer cells and their ability to evade apoptosis. Here, we review current evidence pointing to the function of VDAC1 in cell life and death, and highlight these functions in relation to both cancer development and therapy. In addressing the recently solved 3D structures of VDAC1, this review will point to structure-function relationships of VDAC as critical for deciphering how this channel can perform such a variety of roles, all of which are important for cell life and death. Finally, this review will also provide insight into VDAC function in Ca2+ homeostasis, protection against oxidative stress, regulation of apoptosis and involvement in several diseases, as well as its role in the action of different drugs. We will discuss the use of VDAC1-based strategies to attack the altered metabolism and apoptosis of cancer cells. These strategies include specific siRNA able to impair energy and metabolic homeostasis, leading to arrested cancer cell growth and tumor development, as well VDAC1-based peptides that interact with anti-apoptotic proteins to induce apoptosis, thereby overcoming the resistance of cancer cell to chemotherapy. Finally, small molecules targeting VDAC1 can induce apoptosis. VDAC1 can thus be considered as standing at the crossroads between mitochondrial metabolite transport and apoptosis and hence represents an emerging cancer drug target. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Hsiao YP, Tsai CH, Wu PP, et al.
Cantharidin induces G2/M phase arrest by inhibition of Cdc25c and Cyclin A and triggers apoptosis through reactive oxygen species and the mitochondria‑dependent pathways of A375.S2 human melanoma cells.
Int J Oncol. 2014; 45(6):2393-402 [PubMed] Related Publications
Cantharidin (CTD), a component of natural mylabris (Mylabris phalerata Pallas) was reported to have high cytotoxicity in many human cancer cell lines. However, it was not reported to affect human melanoma A375.S2 cells. In the present study, we found that CTD induced cell morphological changes and decreased the percentage of viable cells and induced G2/M phase arrest and induction of apoptosis in A375.S2 cells. Results also showed that CTD induced the generation of reactive oxygen species (ROS) and Ca2+ and decreased mitochondria membrane potential and lead to the release of cytochrome c, AIF and Endo G. Further investigation revealed that CTD induced A375.S2 cells with an increase of caspase activation and caspase-dependent apoptotic proteins to trigger correlated pathway mechanisms according to western blotting results. Western blotting was used for examining the changes of G2/M phase arrest and apoptosis-associated protein expression and confocal laser microscopy was used to examine the translocation apoptosis-associated protein. Results showed that CTD increased the protein expression of caspase-3, -8 and -9, cytochrome c, Bax, Bid, Endo G and AIF but inhibited the levels of Bcl-2 and Bcl-x. CTD induced ER stress-associated protein expression such as GRP78, IRE1β, ATF6α and caspase-12. Based on those observations, we suggest that CTD may have potential as a novel anti-cancer agent for the treatment of skin cancer.

Chaves Neto AH, Pelizzaro-Rocha KJ, Fernandes MN, Ferreira-Halder CV
Antitumor activity of irradiated riboflavin on human renal carcinoma cell line 786-O.
Tumour Biol. 2015; 36(2):595-604 [PubMed] Related Publications
Riboflavin (vitamin B2) is a precursor for coenzymes involved in energy production, biosynthesis, detoxification, and electron scavenging. Previously, we demonstrated that irradiated riboflavin (IR) has potential antitumoral effects against human leukemia cells (HL60), human prostate cancer cells (PC3), and mouse melanoma cells (B16F10) through a common mechanism that leads to apoptosis. Hence, we here investigated the effect of IR on 786-O cells, a known model cell line for clear cell renal cell carcinoma (CCRCC), which is characterized by high-risk metastasis and chemotherapy resistance. IR also induced cell death in 786-O cells by apoptosis, which was not prevented by antioxidant agents. IR treatment was characterized by downregulation of Fas ligand (TNF superfamily, member 6)/Fas (TNF receptor superfamily member 6) (FasL/Fas) and tumor necrosis factor receptor superfamily, member 1a (TNFR1)/TNFRSF1A-associated via death domain (TRADD)/TNF receptor-associated factor 2 (TRAF) signaling pathways (the extrinsic apoptosis pathway), while the intrinsic apoptotic pathway was upregulated, as observed by an elevated Bcl-2 associated x protein/B-cell CLL/lymphoma 2 (Bax/Bcl-2) ratio, reduced cellular inhibitor of apoptosis 1 (c-IAP1) expression, and increased expression of apoptosis-inducing factor (AIF). The observed cell death was caspase-dependent as proven by caspase 3 activation and poly(ADP-ribose) polymerase-1 (PARP) cleavage. IR-induced cell death was also associated with downregulation of v-src sarcoma (Schmidt-Ruppin A-2) viral oncogene homologue (avian)/protein serine/threonine kinase B/extracellular signal-regulated protein kinase 1/2 (Src/AKT/ERK1/2) pathway and activation of p38 MAP kinase (p38) and Jun-amino-terminal kinase (JNK). Interestingly, IR treatment leads to inhibition of matrix metalloproteinase-2 (MMP-2) activity and reduced expression of renal cancer aggressiveness markers caveolin-1, low molecular weight phosphotyrosine protein phosphatase (LMWPTP), and kinase insert domain receptor (a type III receptor tyrosine kinase) (VEGFR-2). Together, these results show the potential of IR for treating cancer.

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