Gene Summary

Gene:AIFM1; apoptosis-inducing factor, mitochondrion-associated, 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, which results in a severe mitochondrial encephalomyopathy. Alternative splicing results in multiple transcript variants. A related pseudogene has been identified on chromosome 10. [provided by RefSeq, May 2010]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:apoptosis-inducing factor 1, mitochondrial
Source:NCBIAccessed: 21 August, 2015


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 (1990-2015)
Graph generated 21 August 2015 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 21 August, 2015 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)

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.

Zhang WG, Liu XF, Meng KW, Hu SY
Puerarin inhibits growth and induces apoptosis in SMMC-7721 hepatocellular carcinoma cells.
Mol Med Rep. 2014; 10(5):2752-8 [PubMed] Related Publications
Puerarin, a predominant isoflavonoid compound extracted from the Chinese medicinal herb Radix Puerariae, is considered to exhibit an antitumor effect. In the present study, the effects of puerarin on SMMC-7721 human hepatocellular carcinoma cells were investigated. Cell viability was assessed by MTT assay. Apoptosis was detected by flow cytometry with Annexin V-fluorescein isothiocyante staining and morphological observation of nuclear changes by Hoechst staining. The mitochondrial membrane potential (MMP) was monitored using rhodamine 123. The generation of reactive oxygen species (ROS) was quantified using dichloro‑dihydro‑fluorescein diacetate. Polymerase chain reaction and western blot analysis were used to detect the expression levels of apoptosis‑associated genes. The results revealed that high concentrations of puerarin (500, 1,000 and 1,500 µg/ml) significantly inhibited the proliferation of SMMC-7721 cells in a time- and dose-dependent manner. Simultaneously, apoptotic rates were increased and cell morphology was changed following puerarin treatment. Furthermore, puerarin‑induced apoptosis of SMMC-7721 cells was associated with loss of MMP and generation of ROS. Puerarin treatment increased caspase‑3,8,9 and apoptosis‑inducing factor (AIF) mRNA expression levels in SMMC‑7721 cells, while the phosphorylation levels of P38, extracellular signal‑regulated kinase (ERK1) and c-Jun N‑terminal kinase were also increased. Furthermore, caspase-9 and AIF protein expression was upregulated. In conclusion, puerarin inhibited proliferation and induced apoptosis in SMMC‑7721 cells via the mitochondria‑dependent pathway; however, the specific mechanisms require further investigation.

Song G, Valdez BC, Li Y, et al.
Synergistic cytotoxicity of sorafenib with busulfan and nucleoside analogs in human FMS-like tyrosine kinase 3 internal tandem duplications-positive acute myeloid leukemia cells.
Biol Blood Marrow Transplant. 2014; 20(11):1687-95 [PubMed] Related Publications
Clofarabine (Clo), fludarabine (Flu), and busulfan (Bu) are used in pretransplantation conditioning therapy for patients with myeloid leukemia. To further improve their efficacy in FMS-like tyrosine kinase 3 internal tandem duplications (FLT3-ITD)-positive acute myeloid leukemia (AML), we investigated their synergism with sorafenib (Sor). Exposure of FLT3-ITD-positive MV-4-11 and MOLM 13 cells to Bu+Clo+Flu+Sor resulted in synergistic cytotoxicity; no such synergism was observed in the FLT3-wild type THP-1 and KBM3/Bu250(6) cell lines. The drug synergism in MV-4-11 cells could be attributed to activation of DNA damage response, histone 3 modifications, inhibition of prosurvival kinases, and activation of apoptosis. Further, the phosphorylation of kinases, including FLT3, MAPK kinase (MEK), and AKT, was inhibited. The FLT3-ITD substrate STAT5 and its target gene PIM 2 product decreased when cells were exposed to Sor alone, Bu+Clo+Flu, and Bu+Clo+Flu+Sor. The level of the proapoptotic protein p53 upregulated modulator of apoptosis (PUMA) increased, whereas the level of prosurvival protein MCL-1 decreased when cells were exposed to Bu+Clo+Flu+Sor. The interactions of PUMA with MCL-1 and/or BCL-2 were enhanced when cells were exposed to Bu+Clo+Flu or Bu+Clo+Flu+Sor. The changes in the level of these proteins, which are involved in mitochondrial control of apoptosis, correlate with changes in mitochondrial membrane potential. Bu+Clo+Flu+Sor decreased mitochondrial membrane potential by 60% and caused leakage of cytochrome c, second mitochondria-derived activator of caspases (SMAC)/direct IAP Binding protein with low pI (DIABLO), and AIF from the mitochondria to the cytoplasm, caspase activation, and cell death, suggesting the activation of apoptosis. Analogous, synergistic cytotoxicity in response to Bu, Clo, Flu, and Sor was observed in mononuclear cells isolated from FLT3-ITD-positive AML patients. Although our previous studies were aimed at standardizing the conditioning regimen, the new findings suggest that patients with abnormal expression of FLT3 might further benefit from individualizing treatment through the addition of Sor to Bu+Clo+Flu, thereby providing personalized pretransplantation therapy.

Park SY, Kim do Y, Kang JK, et al.
Involvement of activation of the Nrf2/ARE pathway in protection against 6-OHDA-induced SH-SY5Y cell death by α-iso-cubebenol.
Neurotoxicology. 2014; 44:160-8 [PubMed] Related Publications
Free radical-mediated neurodegeneration is one of the many causes of Parkinson's disease (PD). As part of our ongoing studies on the identification of biologically active Schisandra chinensis components, we have isolated and structurally elucidated α-iso-cubebenol. This study was carried out in an attempt to clarify the neuroprotective effect of α-iso-cubebenol on toxin-insulted dopaminergic neuronal death using 6-hydroxy-dopamine (6-OHDA)-induced dopaminergic SH-SY5Y cells. α-iso-cubebenol significantly attenuated the loss of mitochondrial function (MTT assay) and membrane integrity (lactate dehydrogenase assay) associated with 6-OHDA-induced neurotoxicity. Pretreatment of the cells with α-iso-cubebenol diminished the intracellular accumulation of reactive oxygen species (ROS) and calcium in response to 6-OHDA. Moreover, α-iso-cubebenol protected against 6-OHDA-induced neurotoxicity through inhibition of SH-SY5Y cell apoptosis. In addition, JC-1 staining, which is a well-established measure of mitochondrial damage, was decreased after treatment with α-iso-cubebenol. Notably, α-iso-cubebenol inhibited the release of mitochondrial flavoprotein apoptosis inducing factor (AIF) from the mitochondria to the cytosol and nucleus following 6-OHDA treatment. In addition, α-iso-cubebenol reduced the 6-OHDA-induced phosphorylation of ERK and induced the phosphorylation of PKA, PKB, and CREB in a dose-dependent manner. Moreover, α-iso-cubebenol stimulated the activation of Nrf2, a downstream target of CREB. Furthermore, α-iso-cubebenol stimulated the expression of multiple antioxidant response genes (NQO-1 and HO-1). Finally, CREB and Nrf2 siRNA transfection diminished α-iso-cubebenol-mediated neuroprotection.

Jang JH, Cho YC, Kim KH, et al.
BAI, a novel Cdk inhibitor, enhances farnesyltransferase inhibitor LB42708-mediated apoptosis in renal carcinoma cells through the downregulation of Bcl-2 and c-FLIP (L).
Int J Oncol. 2014; 45(4):1680-90 [PubMed] Related Publications
Previously, we reported the potential of a novel Cdk inhibitor, 2-[1,1'-biphenyl]-4-yl-N-[5-(1,1-dioxo-1λ6-isothiazolidin-2-yl)-1H-indazol-3-yl]acetamide (BAI) as a cancer chemotherapeutic agent. In this study, we investigated mechanisms by which BAI modulates FTI-mediated apoptosis in human renal carcinoma Caki cells. BAI synergizes with FTI to activate DEVDase, cleavage of poly ADP-ribose polymerase (PARP), and degradation of various anti-apoptotic proteins in Caki cells. BAI plus LB42708-induced apoptosis was inhibited by pretreatment with pan-caspase inhibitor, z-VAD-fmk, but not by overexpression of CrmA. The ROS scavenger, N-acetylcysteine (NAC) did not reduce BAI plus LB4270-induced apoptosis. Co-treatment of BAI and LB42708 reduced the mitochondrial membrane potential (MMP, ∆Ψm) in a time-dependent manner, and induced release of AIF and cytochrome c from mitochondria in Caki cells. Furthermore, BAL plus LB42708 induced downregulation of anti-apoptotic proteins [c-FLIP (L), c-FLIP (s), Bcl-2, XIAP, and Mcl-1 (L)]. Especially, we found that BAI plus LB42708-induced apoptosis was significantly attenuated by overexpression of Bcl-2 and partially blocked by overexpression of c-FLIP (L). Taken together, our results show that the activity of BAI plus LB42708 modulate multiple components in apoptotic response of human renal Caki cells, and indicate a potential as combinational therapeutic agents for preventing cancer such as renal carcinoma.

Gao Z, Zhu M, Wu Y, et al.
Interferon-λ1 induces G1 phase cell cycle arrest and apoptosis in gastric carcinoma cells in vitro.
Oncol Rep. 2014; 32(1):199-204 [PubMed] Related Publications
The aim of the present study was to examine the potential antitumor action of IFN-λ1 in human gastric carcinoma cell lines and the possible interaction between IFN-λ1 and human gastric carcinoma cells. Gastric carcinoma HGC-27 and SGC-7901 cells were treated with IFN-λ1 (0, 10, 100, 1000 ng/ml) for 48 h. Cytotoxicity was examined using an MTT method. Cell cycle distribution was examined using propidium iodide staining. Apoptosis was examined using the Annexin V-FITC/PI apoptosis kit. By using flow cytometry and JC-1 probe, the mitochondrial membrane potential of cells following treatment with IFN-λ1 was also examined. Expression levels of representative apoptosis‑related proteins were evaluated by western blot analysis. IFN-λ1 inhibited the proliferation of gastric carcinoma cells in a concentration‑dependent manner. IFN-λ1 increased the accumulation of cells in the sub-G0 phase and arrested the cells in the G1 phase. Exposure to IFN‑λ1 decreased the mitochondrial membrane potential and increased apoptosis. Moreover, IFN‑λ1 exposure upregulated the expression of p21, p27 and Bax, downregulated the expression of Bcl‑2, increased the release of cytochrome c and apoptosis-inducing factor (AIF) and activated caspase-3 and caspase-9. In conclusion, IFN-λ1 inhibits the proliferation of gastric carcinoma cells by arresting the cells in the G1 phase and by inducing mitochondrial‑mediated apoptosis.

Hsia TC, Yu CC, Hsu SC, et al.
Cantharidin induces apoptosis of H460 human lung cancer cells through mitochondria-dependent pathways.
Int J Oncol. 2014; 45(1):245-54 [PubMed] Related Publications
Lung cancer is one of the leading causes of death in cancer-related diseases. Cantharidin (CTD) is one of the components of natural mylabris (Mylabris phalerata Pallas). Numerous studies have shown that CTD induced cytotoxic effects on cancer cells. However, there is no report to demonstrate that CTD induced apoptosis in human lung cancer cells. Herein, we investigated the effect of CTD on the cell death via the induction of apoptosis in H460 human lung cancer cells. Flow cytometry assay was used for examining the percentage of cell viability, sub-G1 phase of the cell cycle, reactive oxygen species (ROS) and Ca²⁺ productions and the levels of mitochondrial membrane potential (∆Ψm). Annexin V/PI staining and DNA gel electrophoresis were also used for examining cell apoptosis. Western blot analysis was used to examine the changes of apoptosis associated protein expression and confocal microscopy for examining the translocation apoptosis associated protein. Results indicated that CTD significantly induced cell morphological changes and decreased the percentage of viable H460 cells. CTD induced apoptosis based on the occurrence of sub-G1 phase and DNA fragmentation. We found that CTD increased gene expression (mRNA) of caspase-3 and -8. Moreover, CTD increased ROS and Ca2+ production and decreased the levels of ∆Ψm. Western blot analysis results showed that CTD increased the expression of cleavage caspase-3 and -8, cytochrome c, Bax and AIF but inhibited the levels of Bcl-xL. CTD promoted ER stress associated protein expression such as GRP78, IRE1α, IRE1β, ATF6α and caspase-4 and it also promoted the expression of calpain 2 and XBP-1, but inhibited calpain 1 that is associated with apoptosis pathways. Based on those observations, we suggest that CTD may be used as a novel anticancer agent for the treatment of lung cancer in the future.

Lee K, Hart MR, Briehl MM, et al.
The copper chelator ATN-224 induces caspase-independent cell death in diffuse large B cell lymphoma.
Int J Oncol. 2014; 45(1):439-47 [PubMed] Free Access to Full Article Related Publications
Bcl-2 and other anti-apoptotic proteins are associated with defective caspase-dependent apoptotic pathways, resulting in chemoresistance. We have previously shown that ATN-224, a copper chelator drug, induces cell death in murine thymic lymphoma cells transfected with Bcl-2. In the current study, we tested whether ATN-224 was effective in diffuse large B cell lymphoma (DLBCL) cells, which have increased anti‑apoptotic proteins through translocation or amplification. We found that nanomolar concentrations of ATN-224 induced cell death in DLBCL cells independent of Bcl-2, Bcl-xL or Mcl-1 status. ATN-224 treatment resulted in mitochondrial dysfunction, release of apoptosis-inducing factor (AIF) and induction of caspase-independent cell death. In addition, ATN-224 degraded Mcl-1 and enhanced the effect of the BH3 mimetic ABT-263. These findings indicate that ATN-224 has potential as a therapeutic for the treatment of DLBCL. Induction of caspase‑independent cell death in apoptosis‑resistant DLBCL would provide a therapeutic alternative for the treatment of refractory disease.

Sun YS, Lv LX, Zhao Z, et al.
Cordycepol C induces caspase-independent apoptosis in human hepatocellular carcinoma HepG2 cells.
Biol Pharm Bull. 2014; 37(4):608-17 [PubMed] Related Publications
Cordycepol C, a novel sesquiterpene isolated from the cultured mycelia of Cordyceps ophioglossoides, contains a hydroperoxy group and is cytotoxic to HepG2 cells. So far, no sesquiterpenes have been found in the genus Cordyceps and it would be interesting to investigate the antitumor efficacy as well as the mechanism of action of this unusual sesquiterpene. In this study, we showed that cordycepol C induced apoptosis of the HepG2 cells without affecting the normal liver cell line L-02. Cordycepol C caused poly(ADP-ribose)polymerase-1 (PARP-1) cleavage and triggered the loss of mitochondrial membrane potential (Δψm) in HepG2 cells in a time- and dose-dependent manner, resulting in the nuclear translocation of apoptosis-inducing factor (AIF) and endonuclease G (Endo G). We also found that cordycepol C induced the expression of Bax protein, followed by its translocation from the cytosol to mitochondria in both wild type and p53 knockdown HepG2 cells. However, cordycepol C could not cause cleavages of procaspase-3, -8, and -9. Caspase activities were not increased and Z-VAD-fmk, a caspase inhibitor, could not prevent the apoptosis induced by cordycepol C. These findings indicate that cordycepol C induces caspase-independent apoptosis in HepG2 cells through a p53-independent and Bax-mediated mitochondrial pathway, leading to the nuclear translocation of AIF and Endo G. Our study provides the molecular mechanism by which cordycepol C induces apoptosis in hepatocellular carcinoma cells and indicates the potential use of cordycepol C as an antitumor agent.

Agarwal E, Chaudhuri A, Leiphrakpam PD, et al.
Akt inhibitor MK-2206 promotes anti-tumor activity and cell death by modulation of AIF and Ezrin in colorectal cancer.
BMC Cancer. 2014; 14:145 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: There is extensive evidence for the role of aberrant cell survival signaling mechanisms in cancer progression and metastasis. Akt is a major component of cell survival-signaling mechanisms in several types of cancer. It has been shown that activated Akt stabilizes XIAP by S87 phosphorylation leading to survivin/XIAP complex formation, caspase inhibition and cytoprotection of cancer cells. We have reported that TGFβ/PKA/PP2A-mediated tumor suppressor signaling regulates Akt phosphorylation in association with the dissociation of survivin/XIAP complexes leading to inhibition of stress-dependent induction of cell survival.
METHODS: IGF1R-dependent colon cancer cells (GEO and CBS) were used for the study. Effects on cell proliferation and cell death were determined in the presence of MK-2206. Xenograft studies were performed to determine the effect of MK-2206 on tumor volume. The effect on various cell death markers such as XIAP, survivin, AIF, Ezrin, pEzrin was determined by western blot analysis. Graph pad 5.0 was used for statistical analysis. P < 0.05 was considered significant.
RESULTS: We characterized the mechanisms by which a novel Akt kinase inhibitor MK-2206 induced cell death in IGF1R-dependent colorectal cancer (CRC) cells with upregulated PI3K/Akt signaling in response to IGF1R activation. MK-2206 treatment generated a significant reduction in tumor growth in vivo and promoted cell death through two mechanisms. This is the first report demonstrating that Akt inactivation by MK-2206 leads to induction of and mitochondria-to-nuclear localization of the Apoptosis Inducing Factor (AIF), which is involved in caspase-independent cell death. We also observed that exposure to MK-2206 dephosphorylated Ezrin at the T567 site leading to the disruption of Akt-pEzrin-XIAP cell survival signaling. Ezrin phosphorylation at this site has been associated with malignant progression in solid tumors.
CONCLUSION: The identification of these 2 novel mechanisms leading to induction of cell death indicates MK-2206 might be a potential clinical candidate for therapeutic targeting of the subset of IGF1R-dependent cancers in CRC.

Meggyeshazi N, Andocs G, Balogh L, et al.
DNA fragmentation and caspase-independent programmed cell death by modulated electrohyperthermia.
Strahlenther Onkol. 2014; 190(9):815-22 [PubMed] Related Publications
BACKGROUND AND PURPOSE: The electric field and the concomitant heat (electrohyperthermia) can synergistically induce cell death in tumor tissue, due to elevated glycolysis, ion concentration, and permittivity in malignant compared with nonmalignant tissues. Here we studied the mechanism and time course of tumor destruction caused by electrohyperthermia.
MATERIAL AND METHODS: Bilateral implants of HT29 colorectal cancer in the femoral regions of Balb/c (nu/nu) mice were treated with a single 30-min shot of modulated, 13.56-MHz, radiofrequency-generated electrohyperthermia (mEHT). Tumors at 0, 1, 4, 8, 14, 24, 48, and 72 h posttreatment were studied for morphology, DNA fragmentation, and cell death response-related protein expression using tissue microarrays, immunohistochemistry, Western immunoblots, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays.
RESULTS: Modulated EHT treatment induced significant tumor destruction in HT29 xenografts with a peak of a sevenfold increase compared with the untreated controls. The significant treatment-related elevation of DNA fragmentation--detected with TUNEL assay--and apoptotic bodies between 24 and 72 h posttreatment was proof of a programmed cell death response. This was associated with significant mitochondrial accumulation of bax and mitochondrial-to-cytoplasmic release of cytochrome c proteins between 8 and 14 h. Cleaved caspase-3 levels were low and mainly localized to inflammatory cells. The substantial cytoplasmic-to-nuclear translocation of apoptosis-inducing factor (AIF) and its 57-kDa activated fragment detected between 14 and 24 h after treatment indicated AIF as an effector for DNA fragmentation.
CONCLUSION: Modulated EHT treatment can induce programmed cell death-related tumor destruction in HT29 colorectal adenocarcinoma xenografts, which dominantly follows a caspase-independent subroutine.

Jin B, Ding K, Pan J
Ponatinib induces apoptosis in imatinib-resistant human mast cells by dephosphorylating mutant D816V KIT and silencing β-catenin signaling.
Mol Cancer Ther. 2014; 13(5):1217-30 [PubMed] Related Publications
Gain-of-function mutations of membrane receptor tyrosine kinase KIT, especially gatekeeper D816V point mutation in KIT, render kinase autoactivation, disease progression, and poor prognosis. D816V KIT is found in approximately 80% of the patients with systemic mastocytosis, and is resistant to the first and second generations of tyrosine kinase inhibitors (TKI). The purpose of this investigation was aimed at exploring whether ponatinib (AP24534), a novel effective TKI against T315I Bcr-Abl, was active against D816V KIT. We discovered that ponatinib abrogated the phosphorylation of KIT harboring either V560G (sensitive to imatinib) or D816V mutation (resistant to imatinib) and the downstream signaling transduction. Ponatinib inhibited the growth of D816V KIT-expressing cells in culture and nude mouse xenografted tumor. Ponatinib triggered apoptosis by inducing the release of cytochrome c and AIF, downregulation of Mcl-1. Furthermore, ponatinib abrogated the phosphorylation of β-catenin at the site Y654, suppressed the translocation of β-catenin, and inhibited the transcription and DNA binding of TCF and the expression of its targets (e.g., AXIN2, c-MYC, and CCND1). Moreover, ponatinib was highly active against xenografted D816V KIT tumors in nude mice and significantly prolonged the survival of mice with aggressive systemic mastocytosis or mast cell leukemia by impeding the expansion and infiltration of mast cells with imatinib-resistant D814Y KIT. Our findings warrant a clinical trial of ponatinib in patients with systemic mastocytosis harboring D816V KIT.

Won YS, Lee JH, Kwon SJ, et al.
α-Mangostin-induced apoptosis is mediated by estrogen receptor α in human breast cancer cells.
Food Chem Toxicol. 2014; 66:158-65 [PubMed] Related Publications
In this study, we evaluated the effects of α-mangostin on cell growth inhibition and induction of apoptosis in MCF-7 ERα-positive human breast cancer cells. Our results showed that α-mangostin inhibited MCF-7 cell proliferation whereas ERα-negative MDA-MB-231 cells were less sensitive to the agent. Additionally, α-mangostin effectively induced apoptosis as evidenced by the appearance of apoptotic nuclei observed with Hoechst 33258 staining and evaluation of sub-G1 DNA contents by flow cytometry. α-Mangostin also activated caspases-8, -9, and -7; increased the protein levels of Bax, p53, and cytosolic cytochrome c; and induced PARP cleavage while reducing Bid and Bcl-2 protein expression. In addition, apoptosis-inducing factor (AIF) was transported from mitochondria to the cytosol after α-mangostin treatment. α-mangostin also induced apoptosis in 17-β-estradiol (E2)-stimulated MCF-7 cells in parallel with the non-stimulated cells. Moreover, treatment with 10μM α-mangostin for 48h specifically decreased the expression of ERα and pS2, an estrogen-responsive gene, in MCF-7 cells. Furthermore, knockdown of ERα expression in MCF-7 cells with siRNA attenuated α-mangostin-induced cell growth inhibition and caspase-7 activation. These results suggest that ERα is required for α-mangostin-induced growth inhibition and apoptosis in human breast cancer cells. Therefore, α-mangostin may be used to prevent and treat of ER-positive breast cancer.

Huang Q, Chen H, Wang F, et al.
Reduced syncytin-1 expression in choriocarcinoma BeWo cells activates the calpain1-AIF-mediated apoptosis, implication for preeclampsia.
Cell Mol Life Sci. 2014; 71(16):3151-64 [PubMed] Related Publications
Placentas associated with preeclampsia are characterized by extensive apoptosis in trophoblast lineages. Syncytin-1 (HERVWE1) mediates the fusion of cytotrophoblasts to form syncytiotrophoblasts, which assume the placental barrier, fetal-maternal exchange and endocrine functions. While decreased syncytin-1 expression has been observed in preeclamptic placentas, it is not clear if this alteration is involved in trophoblast apoptosis. In the current study, we found that siRNA-mediated knockdown of syncytin-1 led to apoptosis in choriocarcinoma BeWo, a cell line of trophoblastic origin. Characterization of the apoptotic pathways indicated that this effect does not rely on the activation of caspases. Rather, decreased syncytin-1 levels activated the apoptosis inducing factor (AIF) apoptotic pathway by inducing the expression, cleavage, and nuclear translocation of AIF. Moreover, calpain1, the cysteine protease capable of cleaving AIF, was upregulated by syncytin-1 knockdown. Furthermore, treatment with calpain1 inhibitor MDL28170 effectively reversed AIF cleavage, AIF nuclear translocation, and cell apoptosis triggered by syncytin-1 downregulation, verifying the specific action of calpain1-AIF pathway in trophoblast apoptosis. We confirmed that preeclamptic placentas express lower levels of syncytin-1 than normal placentas, and observed an inverse correlation between syncytin-1 and AIF/calpain1 mRNA levels, a result consistent with the in vitro findings. Immunohistochemistry analyses indicated decreased syncytin-1 and increased AIF and calpain1 protein levels in apoptotic cells of preeclamptic placentas. These findings have for the first time revealed that decreased levels of syncytin-1 can trigger the AIF-mediated apoptosis pathway in BeWo cells. This novel mechanism may contribute to the structural and functional deficiencies of syncytium frequently observed in preeclamptic placentas.

Song W, Tian L, Li SS, et al.
The aberrant expression and localization of prohibitin during apoptosis of human cholangiocarcinoma Mz-ChA-1 cells.
FEBS Lett. 2014; 588(3):422-8 [PubMed] Related Publications
In this study, we aimed to investigate the aberrant expression and shift in localization of prohibitin (PHB) during apoptosis of human cholangiocarcinoma cells. Our study demonstrated that PHB was expressed primarily in the cytoplasm and only a little in the nucleus. However, PHB expression significantly decreased, and its localization shifted from the cytoplasm to the nucleus during apoptosis. PHB co-localized with AIF, Rb, p53, and c-Fos, but the region of co-localization was altered after treatment. Meanwhile, we detected a direct interaction between PHB and both p53 and Rb in Mz-ChA-1 cells. These results suggest that the altered localization and expression of PHB, as well as its co-localization with related oncogenes and tumor suppressor genes, can affect the apoptosis of Mz-ChA-1 cells.

Chiang YY, Chow KC, Lin TY, et al.
Hepatocyte growth factor and HER2/neu downregulate expression of apoptosis-inducing factor in non-small cell lung cancer.
Oncol Rep. 2014; 31(2):597-604 [PubMed] Related Publications
Our previous study showed that patients with advanced stages of non-small cell lung cancer (NSCLC) were frequently detected with upregulation of hepatocyte growth factor (HGF). In vitro, HGF reduced expression of apoptosis-inducing factor (AIF) and cisplatin sensitivity in NSCLC cells. The effect of HGF was via HGF receptor (c-MET) and the downstream effector, focal adhesion kinase (FAK). In this study, we determined the prognostic value of AIF in NSCLC patients. AIF expression was determined by immunohistochemistry and immunoblotting. Our data show that AIF expression was associated with better prognosis. Expression of AIF inversely correlated with that of positive NSCLC markers, e.g., dihydrodiol dehydrogenase (DDH), c-MET, short oncostatin M receptor (OSMRs), matrix metalloproteinase (MMP)-1, and HER2/neu, which were closely associated with drug resistance, tumor recurrence, metastasis and poor prognosis. Noteworthy, silence of HER2/neu gene expression increases AIF level and drug sensitivity. Addition of HGF inhibits AIF expression in HER2/neu-silenced cells. These results suggested that both HGF and HER2/neu affect drug resistance by regulating AIF expression in NSCLC.

Aporta A, Catalán E, Galán-Malo P, et al.
Granulysin induces apoptotic cell death and cleavage of the autophagy regulator Atg5 in human hematological tumors.
Biochem Pharmacol. 2014; 87(3):410-23 [PubMed] Related Publications
Granulysin is a protein present in the granules of human CTL and NK cells, with cytolytic activity against microbes and tumors. Previous work demonstrated that granulysin caused cell death through mitochondrial damage with release of AIF and cytochrome c. However, the molecular mechanism and, especially, the type of cell death were still not well defined. In the present work we show that granulysin-induced cell death is apoptotic, with phosphatidylserine exposure preceding membrane breakdown and with caspase 3 activation. Granulysin-induced apoptosis is prevented in Jurkat cells over-expressing Bcl-xL or Bcl2, or lacking Bak and Bax or Bim expression, suggesting a central role of the mitochondrial apoptotic pathway. This apoptotic process is initiated by intracellular Ca(2+) increase and mitochondrial ROS generation. We have tested granulysin against other hematological tumor cells such as multiple myeloma cell lines, and cells from B cell chronic lymphocytic leukemia (B-CLL) patients, finding different degrees of sensitivity. We also show that granulysin induces the cleavage of Atg5 in the complex formed with Atg12, without affecting autophagy. In conclusion, granulysin induces apoptosis on hematological tumor cells and on cells from B-CLL patients, opening the door to research on its use as a new anti-tumoral treatment.

Chen XM, Bai Y, Zhong YJ, et al.
Wogonin has multiple anti-cancer effects by regulating c-Myc/SKP2/Fbw7α and HDAC1/HDAC2 pathways and inducing apoptosis in human lung adenocarcinoma cell line A549.
PLoS One. 2013; 8(11):e79201 [PubMed] Free Access to Full Article Related Publications
Wogonin is a plant monoflavonoid which has been reported to inhibit cell growth and/or induce apoptosis in various tumors. The present study examined the apoptosis-inducing activity and underlying mechanism of action of wogonin in A549 cells. The results showed that wogonin was a potent inhibitor of the viability of A549 cells. Apoptotic protein changes detected after exposure to wogonin included decreased XIAP and Mcl-1 expression, increased cleaved-PARP expression and increased release of AIF and cytochrome C. Western blot analysis showed that the activity of c-Myc/Skp2 and HDAC1/HDAC2 pathways, which play important roles in tumor progress, was decreased. Quantitative PCR identified increased levels of c-Myc mRNA and decreased levels of its protein. Protein levels of Fbw7α, GSK3β and Thr58-Myc, which are involved in c-Myc ubiquitin-dependent degradation, were also analyzed. After exposure to wogonin, Fbw7α and GSK3β expression decreased and Thr58-Myc expression increased. However, MG132 was unable to prevent c-Myc degradation. The present results suggest that wogonin has multiple anti-cancer effects associated with degradation of c-Myc, SKP2, HDAC1 and HDAC2. Its ability to induce apoptosis independently of Fbw7α suggests a possible use in drug-resistance cancer related to Fbw7 deficiency. Further studies are needed to determine which pathways are related to c-Myc and Fbw7α reversal and whether Thr58 phosphorylation of c-Myc is dependent on GSK3β.

Mohammadpour R, Safarian S, Ejeian F, et al.
Acetazolamide triggers death inducing autophagy in T-47D breast cancer cells.
Cell Biol Int. 2014; 38(2):228-38 [PubMed] Related Publications
The inhibitory effects of acetazolamide on the growth and proliferation of epithelial breast cancer cells (T-47D) were investigated. Analysis of morphological changes indicated little apoptosis in T-47D cells incubated with acetazolamide, according to data from flow cytometry, DNA laddering, and expression of AIF. However, an increase in caspase-3 activity was detected in cells. This was concomitant with an increase in DFF45/DFF40 ratio leading to inhibition of caspase-3 activity, DNA fragmentation and progression of apoptosis. Flow cytometry also confirmed that acetazolamide had no significant effect on cell cycle progression. These results are consistent with lack of change in the expression of cell cycle regulatory proteins p21, p27, cdc2 and cyclinD1. Increased expression of ATG5, p53 and DRAM, along with an increase in BCLN1/Bcl-2 ratio, indicated that acetazolamide inhibited the proliferation of T-47D cells by inducing autophagy. Increased expression of PTEN, along with decreased expression of Akt1, also showed that acetazolamide treatment resulted in death inducing autophagy. Collectively the results indicate that autophagy is an adequate mechanism mediating the anti-cancer effects of acetazolamide in T-47D cells through engagement of p53/DRAM pathway and attenuation of Akt survival signalling.

Zhou Y, Bi Y, Yang C, et al.
Magnolol induces apoptosis in MCF-7 human breast cancer cells through G2/M phase arrest and caspase-independent pathway.
Pharmazie. 2013; 68(9):755-62 [PubMed] Related Publications
Magnolol, a small-molecule hydroxylated biphenol, isolated from the root and stem bark of Magnolia officinalis, has been shown to possess antiproliferative effect on various cancer cell lines. In the current study, we found that magnolol potently inhibited proliferation and induced apoptosis in MCF-7 human breast cancer cells. Further mechanistic studies revealed that induction of apoptosis is associated with cell cycle arrest at G2/M phase, increased generation of reactive oxygen species (ROS), reduced mitochondrial membrane potential (MMP), release of cytochrome c (Cyto c) and apoptosis inducing factor (AIF) from mitochondria to cytosol, upregulation of Bax, p21 and p53, and down-regulation of Bcl-2, cyclin B1 and cyclin-dependent kinase 1 (CDK1). Our findings indicated that magnolol induced apoptosis in MCF-7 cells via the intrinsic pathway with release of AIF from mitochondrial and G2/M phase arrest pathway. Therefore, magnolol might be a potential lead compound in the therapy of breast cancer.

Vanella L, Di Giacomo C, Acquaviva R, et al.
Apoptotic markers in a prostate cancer cell line: effect of ellagic acid.
Oncol Rep. 2013; 30(6):2804-10 [PubMed] Related Publications
Ellagic acid (EA) inhibits cell growth and induces apoptosis in cultured cells; however, the precise molecular mechanism involved in EA-induced apoptosis in prostate cancer cells is unknown. The aim of the present study was to delineate possible apoptotic pathway(s) involved in the EA-mediated chemotherapeutic effects in the LNCaP human prostatic cancer cell line. EA produced anti-proliferative effects through inhibition of rapamycin (mTOR) activation and a reduction in intracellular levels of β-catenin. Moreover, we demonstrated that EA induced apoptosis via downregulation of the anti-apoptotic proteins, silent information regulator 1 (SIRT1), human antigen R (HuR) and heme oxygenase-1 (HO-1). EA modulated the expression of apoptosis-inducing factor (AIF) resulting in a significant increase in reactive oxygen species (ROS) levels and the activation of caspase-3. Finally, we demonstrated that EA reduced both transforming growth factor-β (TGF-β) and interleukin-6 (IL-6) levels. EA treatment resulted in the increased expression of the tumor suppressor protein p21 and increased the percentage of apoptotic cells. In conclusion, the results suggest that EA treatment represents a new and highly effective strategy in reducing prostate cancer carcinogenesis.

Su CH, Chen LJ, Liao JF, Cheng JT
Dual effects of silymarin on nasopharyngeal carcinoma cells (NPC-TW01).
Forsch Komplementmed. 2013; 20(4):261-6 [PubMed] Related Publications
BACKGROUND: Silymarin is an active component from the seeds of Silybum marianum and is widely used as a hepatic protection agent. Apoptosis induced by silymarin has been mentioned in cervical cancer cells. However, silymarin shows dual effects on tumor cells: cytostatic action at a low dose and cytotoxic action at higher dose. Thus, in the present study, we focused on low-dosing of silymarin in nasopharyngeal carcinoma cells, NPC-TW01 (TW01).
METHODS: Cell viability assay was used to screen the effect of silymarin in TW01 cells. Western blot analysis was used to identify the expressions of antioxidant enzymes and anti-/proapoptotic proteins. Fluorescent dyes are employed to detect the content of reactive oxygen species (ROS) and cell apoptosis.
RESULTS: Treatment of TW01 cells with silymarin at a low dose (80 µmol/l) resulted in a significant increase of antioxidant enzymes. Silymarin increased the expressions of superoxide dismutase 1, catalase, and glutathione peroxidase. Consequently, the cell apoptosis was reduced markedly. An increase of Bcl-2 expression and a decrease of activated caspase-3 or apoptosis-inducing factor (AIF) were observed in TW01 cells at a low dose (80 µmol/l) treatment.
CONCLUSION: Silymarin at a low dose can induce cytostatic effect on TW01 cells mainly through an increase of antioxidant-like action. Thus, silymarin should be applied carefully to patients with nasopharyngeal carcinoma.

Guo WZ, Shiina I, Wang Y, et al.
Ridaifen-SB8, a novel tamoxifen derivative, induces apoptosis via reactive oxygen species-dependent signaling pathway.
Biochem Pharmacol. 2013; 86(9):1272-84 [PubMed] Related Publications
Tamoxifen is an anticancer agent widely used for treatment of estrogen receptor (ERα)-positive breast cancer. We previously developed a novel synthesis of tamoxifen and its derivatives, named Ridaifens (RIDs). Some of them, including RID-SB8, exhibited a stronger anticancer activity than tamoxifen in ERα-positive MCF-7 cells while having lost the affinity for ERα, suggesting an ERα-independent anticancer mode of action. In this study, we investigated the underlying mechanism by which RID-SB8 exerts anticancer activity. As expected, anticancer activity of RID-SB8 was not influenced upon knockdown of ERα expression in MCF-7 cells. RID-SB8 exerted similar anticancer effects on thirteen ERα-negative cancer cell lines including human gliosarcoma SF539 cells. In SF539 cells, RID-SB8 triggered loss of mitochondrial membrane potential (ΔΨ(m)) and progression of apoptosis accompanied by activation of caspases and translocation of apoptosis-inducing factor (AIF) to the nucleus. Furthermore, it induced reactive oxygen species (ROS), and a ROS scavenger, N-acetylcysteine (NAC), canceled loss of ΔΨ(m) and progression of apoptosis triggered by RID-SB8. Using fifteen human cancer cell lines, we demonstrated a significant correlation between RID-SB8 concentration required for ROS production and that required for cytotoxic effect across these cell lines, but such correlation was not observed for tamoxifen. Finally, the selective induction of ROS and cytotoxic effect on cancer cells by RID-SB8 were confirmed. From these results, we concluded that RID-SB8 exerts an anticancer effect via a mode of action distinct from tamoxifen, and that RID-SB8 could become a promising anticancer lead compound which selectively induces ROS formation and apoptosis in cancer cells.

Fan T, Tian F, Yi S, et al.
Implications of Bit1 and AIF overexpressions in esophageal squamous cell carcinoma.
Tumour Biol. 2014; 35(1):519-27 [PubMed] Related Publications
Overwhelming evidence has demonstrated that Bit1 and AIF as mitochondrial proteins are implicated in the development and progression of a variety of tumors. However, their expressions and biological functions in esophageal squamous cell carcinoma (ESCC) remain to be delineated. In the present study, we found that Bit1, AIF, and Bcl-2 levels in ESCC tissues were significantly higher than those in normal esophageal epithelial tissues and dysplasia tissues (P < 0.05). Stepwise investigation demonstrated that Bit1 and Bcl-2 levels were both tightly associated with lymphatic metastasis and TNM staging (P < 0.05), and the levels of Bit1 mRNA as well as AIF and Bcl-2 proteins were both closely related to tumor differentiation (P < 0.05), but not related to the patients' age and gender (P > 0.05). Importantly, Bit1 mRNA and protein levels in ESCC with lymphatic metastasis and TNM staging in III and IV were markedly higher than that without lymphatic metastasis and TMN staging in I and II. Further analysis showed that expression of Bit1 protein was both positively correlated with expressions of AIF and Bcl-2 proteins (r = 0.408 and 0.405, respectively; P < 0.05). Correctively, our data cited earlier suggest that Bit1 plays pivotal roles in the development and progression of ESCC, and its biological functions in ESCC may be closely associated with AIF and Bcl-2 levels.

Chang PY, Peng SF, Lee CY, et al.
Curcumin-loaded nanoparticles induce apoptotic cell death through regulation of the function of MDR1 and reactive oxygen species in cisplatin-resistant CAR human oral cancer cells.
Int J Oncol. 2013; 43(4):1141-50 [PubMed] Related Publications
Curcumin is a polyphenolic compound which possesses anticancer potential. It has been shown to induce cell death in a variety of cancer cells, however, its effect on CAL27‑cisplatin-resistant human oral cancer cells (CAR cells) has not been elucidated to date. The low water solubility of curcumin which leads to poor bioavailability, however, has been highlighted as a major limiting factor. In this study, we utilized water-soluble PLGA curcumin nanoparticles (Cur-NPs), and investigated the effects of Cur-NPs on CAR cells. The results showed Cur-NPs induced apoptosis in CAR cells but exhibited low cytotoxicity to normal human gingival fibroblasts (HGFs) and normal human oral keratinocytes (OKs). Cur-NPs triggered DNA concentration, fragmentation and subsequent apoptosis. Compared to untreated CAR cells, a more detectable amount of Calcein-AM accumulation was found inside the treated CAR cells. Cur-NPs suppressed the protein and mRNA expression levels of MDR1. Both the activity and the expression levels of caspase-3 and caspase-9 were elevated in the treated CAR cells. The Cur-NP-triggered apoptosis was blocked by specific inhibitors of pan-caspase (z-VAD-fmk), caspase-3 (z-DEVD-fmk), caspase-9 (z-LEHD-fmk) and antioxidant agent (N-acetylcysteine; NAC). Cur-NPs increased reactive oxygen species (ROS) production, upregulated the protein expression levels of cleaved caspase-3/caspase-9, cytochrome c, Apaf-1, AIF, Bax and downregulated the protein levels of Bcl-2. Our results suggest that Cur-NPs triggered the intrinsic apoptotic pathway through regulating the function of multiple drug resistance protein 1 (MDR1) and the production of reactive oxygen species (ROS) in CAR cells. Cur-NPs could be potentially efficacious in the treatment of cisplatin-resistant human oral cancer.

Kim MJ, Yun HS, Hong EH, et al.
Depletion of end-binding protein 1 (EB1) promotes apoptosis of human non-small-cell lung cancer cells via reactive oxygen species and Bax-mediated mitochondrial dysfunction.
Cancer Lett. 2013; 339(1):15-24 [PubMed] Related Publications
Although end-binding protein 1 (EB1) is well known to regulate microtubule dynamics, the role of EB1 in apoptosis of non-small cell lung cancer (NSCLC) is poorly understood. Here, we investigated the molecular mechanism by which EB1 regulates apoptosis in H460, A549, and H1299 cells. Depletion of EB1 in A549 and H1299 cells, which express high levels of EB1, induced cell death in a p53-independent manner through over-production of reactive oxygen species (ROS) and Bax induction. This phenomenon was potentiated in radiation-treated EB1-knockdown cells and was largely blocked by N-acetyl-L-cysteine, a scavenger of ROS. ROS accelerated the activation of nuclear factor-kappa B (NF-κB) to promote transcriptional activity of Bax, an action that was accompanied by cytochrome c translocation and apoptosis-inducing factor (AIF) release. The NF-κB inhibitor, BAY 11-7082, potently inhibited the apoptosis induced by EB1 knockdown and radiation treatment, in association with diminished activity of the mitochondrial death pathway. Conversely, ectopic overexpression of EB1 in H460 cells, which express low levels of EB1, remarkably abrogated radiation-induced apoptosis and NF-κB-mediated mitochondrial dysfunction. Our data provide the first demonstration that down-regulation of EB1 promotes NSCLC cell death by inducing ROS-mediated, NF-κB-dependent Bax signaling cascades, a process in which cytochrome c and AIF play important roles, indicating a potential therapeutic benefit of EB1 in lung cancer.

Bey EA, Reinicke KE, Srougi MC, et al.
Catalase abrogates β-lapachone-induced PARP1 hyperactivation-directed programmed necrosis in NQO1-positive breast cancers.
Mol Cancer Ther. 2013; 12(10):2110-20 [PubMed] Free Access to Full Article Related Publications
Improving patient outcome by personalized therapy involves a thorough understanding of an agent's mechanism of action. β-Lapachone (clinical forms, Arq501/Arq761) has been developed to exploit dramatic cancer-specific elevations in the phase II detoxifying enzyme NAD(P)H:quinone oxidoreductase (NQO1). NQO1 is dramatically elevated in solid cancers, including primary and metastatic [e.g., triple-negative (ER-, PR-, Her2/Neu-)] breast cancers. To define cellular factors that influence the efficacy of β-lapachone using knowledge of its mechanism of action, we confirmed that NQO1 was required for lethality and mediated a futile redox cycle where ∼120 moles of superoxide were formed per mole of β-lapachone in 2 minutes. β-Lapachone induced reactive oxygen species (ROS), stimulated DNA single-strand break-dependent poly(ADP-ribose) polymerase-1 (PARP1) hyperactivation, caused dramatic loss of essential nucleotides (NAD(+)/ATP), and elicited programmed necrosis in breast cancer cells. Although PARP1 hyperactivation and NQO1 expression were major determinants of β-lapachone-induced lethality, alterations in catalase expression, including treatment with exogenous enzyme, caused marked cytoprotection. Thus, catalase is an important resistance factor and highlights H2O2 as an obligate ROS for cell death from this agent. Exogenous superoxide dismutase enhanced catalase-induced cytoprotection. β-Lapachone-induced cell death included apoptosis-inducing factor (AIF) translocation from mitochondria to nuclei, TUNEL+ staining, atypical PARP1 cleavage, and glyceraldehyde 3-phosphate dehydrogenase S-nitrosylation, which were abrogated by catalase. We predict that the ratio of NQO1:catalase activities in breast cancer versus associated normal tissue are likely to be the major determinants affecting the therapeutic window of β-lapachone and other NQO1 bioactivatable drugs.

Zhang YQ, Xiao CX, Lin BY, et al.
Silencing of Pokemon enhances caspase-dependent apoptosis via fas- and mitochondria-mediated pathways in hepatocellular carcinoma cells.
PLoS One. 2013; 8(7):e68981 [PubMed] Free Access to Full Article Related Publications
The role of Pokemon (POK erythroid myeloid ontogenic actor), a recently identified POK transcription factor with proto-oncogenic activity, in hepatocellular carcinogenesis has only been assessed by a few studies. Our previous study revealed that Pokemon is overexpressed in hepatocellular carcinomas (HCC) and promotes HCC cell proliferation and migration via an AKT- and ERK- dependent manner. In the present study, we used the TUNEL assay and FACS analysis to demonstrate that oxaliplatin induced apoptosis was significantly increased in cells with silenced Pokemon. Western blots showed that p53 expression and phosphorylation were significantly increased in Pokemon defective cells, thereby initiating the mitochondria-mediated and death receptor-mediated apoptotic pathways. In the mitochondria-mediated pathway, expression of pro-apoptotic Bcl-2 family members (including Bad, Bid, Bim and Puma) as well as AIF was increased and decreasing the mitochondrial membrane potential resulted in cytochrome C released from mitochondrial in HepG2 si-Pokemon cells. In addition, upon oxaliplatin treatment of Pokemon-silenced cells, the FAS receptor, FADD and their downstream targets caspase-10 and caspase-8 were activated, causing increased release of caspase-8 active fragments p18 and p10. Increased activated caspase-8-mediated cleavage and activation of downstream effector caspases such as caspase-9 and caspase-3 was observed in HepG2 si-Pokemon cells as compared to control. Therefore, Pokemon might serve as an important mediator of crosstalk between intrinsic and extrinsic apoptotic pathways in HCC cells. Moreover, our findings suggest that Pokemon could be an attractive therapeutic target gene for human cancer therapy.

Salemi M, Galia A, Fraggetta F, et al.
Poly (ADP-ribose) polymerase 1 protein expression in normal and neoplastic prostatic tissue.
Eur J Histochem. 2013; 57(2):e13 [PubMed] Free Access to Full Article Related Publications
A genetic background has been implicated in the development of prostate cancer. Protein microarrays have enabled the identification of proteins, some of which associated with apoptosis, that may play a role in the development of such a tumor. Inhibition of apoptosis is a co-factor that contributes to the onset and progression of prostate cancer, though the molecular mechanisms are not entirely understood. Poly (ADP-ribose) polymerase 1 (PARP-1) gene is required for translocation of the apoptosis-inducing factor (AIF) from the mitochondria to the nucleus. Hence, it is involved in programmed cell death. Different PARP-1 gene expression has been observed in various tumors such as glioblastoma, lung, ovarian, endometrial, and skin cancers. We evaluated the expression of PARP-1 protein in prostatic cancer and normal prostate tissues by immunohistochemistry in 40 men with prostate cancer and in 37 normal men. Positive nuclear PARP-1 staining was found in all samples (normal prostate and prostate cancer tissues). No cytoplasmic staining was observed in any sample. PARP-1-positive cells resulted significantly higher in patients with prostate carcinoma compared with controls (P<0.001). PARP-1 over-expression in prostate cancer tissue compared with normal prostate suggests a greater activity of PARP-1 in these tumors. These findings suggest that PARP-1 expression in prostate cancer is an attempt to trigger apoptosis in this type of tumor similarly to what reported in other cancers.

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