Gene Summary

Gene:SOD1; superoxide dismutase 1, soluble
Aliases: ALS, SOD, ALS1, IPOA, hSod1, HEL-S-44, homodimer
Summary:The protein encoded by this gene binds copper and zinc ions and is one of two isozymes responsible for destroying free superoxide radicals in the body. The encoded isozyme is a soluble cytoplasmic protein, acting as a homodimer to convert naturally-occuring but harmful superoxide radicals to molecular oxygen and hydrogen peroxide. The other isozyme is a mitochondrial protein. Mutations in this gene have been implicated as causes of familial amyotrophic lateral sclerosis. Rare transcript variants have been reported for this gene. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:superoxide dismutase [Cu-Zn]
Source:NCBIAccessed: 20 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 20 August 2015 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.

Tag cloud generated 20 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: SOD1 (cancer-related)

Kravtsova-Ivantsiv Y, Shomer I, Cohen-Kaplan V, et al.
KPC1-mediated ubiquitination and proteasomal processing of NF-κB1 p105 to p50 restricts tumor growth.
Cell. 2015; 161(2):333-47 [PubMed] Related Publications
NF-κB is a key transcriptional regulator involved in inflammation and cell proliferation, survival, and transformation. Several key steps in its activation are mediated by the ubiquitin (Ub) system. One uncharacterized step is limited proteasomal processing of the NF-κB1 precursor p105 to the p50 active subunit. Here, we identify KPC1 as the Ub ligase (E3) that binds to the ankyrin repeats domain of p105, ubiquitinates it, and mediates its processing both under basal conditions and following signaling. Overexpression of KPC1 inhibits tumor growth likely mediated via excessive generation of p50. Also, overabundance of p50 downregulates p65, suggesting that a p50-p50 homodimer may modulate transcription in place of the tumorigenic p50-p65. Transcript analysis reveals increased expression of genes associated with tumor-suppressive signals. Overall, KPC1 regulation of NF-κB1 processing appears to constitute an important balancing step among the stimulatory and inhibitory activities of the transcription factor in cell growth control.

Melaiu O, Melissari E, Mutti L, et al.
Expression status of candidate genes in mesothelioma tissues and cell lines.
Mutat Res. 2015; 771:6-12 [PubMed] Related Publications
In order to broaden knowledge on the pathogenesis of malignant pleural mesothelioma (MPM), we reviewed studies on the MPM-transcriptome and identified 119 deregulated genes. However, there was poor consistency among the studies. Thus, the expression of these genes was further investigated in the present work using reverse transcriptase-quantitative PCR (RT-qPCR) in 15 MPM and 20 non-MPM tissue samples. Fifty-nine genes showed a statistically significant deregulation and were further evaluated in two epithelioid MPM cell lines (compared to MET-5A, a non-MPM cell line). Nine genes (ACSL1, CCNO, CFB, PDGFRB, SULF1, TACC1, THBS2, TIMP3, XPOT) were deregulated with statistical significance in both cell lines, 12 (ASS1, CCNB1, CDH11, COL1A1, CXADR, EIF4G1, GALNT7, ITGA4, KRT5, PTGIS, RAN, SOD1) in at least one cell line, whereas 7 (DSP, HEG1, MCM4, MSLN, NME2, NMU, TNPO2) were close but did not reach the statistical significance in any of the cell line. Patients whose MPM tissues expressed elevated mRNA levels of BIRC5, DSP, NME2, and THBS2 showed a statistically significant shorter overall survival. Although MPM is a poorly studied cancer, some features are starting to emerge. Novel cancer genes are suggested here, in particular those involved in cell-cell and cell-matrix interactions.

Nalkiran I, Turan S, Arikan S, et al.
Determination of gene expression and serum levels of MnSOD and GPX1 in colorectal cancer.
Anticancer Res. 2015; 35(1):255-9 [PubMed] Related Publications
BACKGROUND/AIM: Oxidative stress plays a role on the development of colorectal cancer. Manganese superoxide dismutase (MnSOD) and glutathione peroxidase 1 (GPX1) are crucial in regulating oxidative balance and its stabilization. Possible mechanisms of action of these enzymes in various types of cancers require further investigation. We aimed to determine expression levels of these genes and their effects on protein levels in serum of patients with colorectal cancer.
MATERIALS AND METHODS: Expression levels of genes were determined using Real Time-Polymerase chain reaction in 35 patients with colorectal cancer. We used enzyme-linked immunosorbent assay to determine MnSOD and GPX1 levels.
RESULTS: We found significant differences in GPX1 expression between tumor and normal tissues, with a 2-fold decrease in tumor tissues (p<0.05). However, although no significant difference was found between the expression of MnSOD gene in tumor and that in normal tissues, there was a 1.13-fold change in expression. We observed no relationship between expressions of either gene and their levels in serum.
CONCLUSION: The GPX1 gene may play a critical role in the development of colorectal cancer.

Kharlyngdoh JB, Pradhan A, Asnake S, et al.
Identification of a group of brominated flame retardants as novel androgen receptor antagonists and potential neuronal and endocrine disrupters.
Environ Int. 2015; 74:60-70 [PubMed] Related Publications
Brominated flame-retardants (BFRs) are used in industrial products to reduce the risk of fire. However, their continuous release into the environment is a concern as they are often persistent, bioaccumulating and toxic. Information on the impact these compounds have on human health and wildlife is limited and only a few of them have been identified to disrupt hormone receptor functions. In the present study we used in silico modeling to determine the interactions of selected BFRs with the human androgen receptor (AR). Three compounds were found to dock into the ligand-binding domain of the human AR and these were further tested using in vitro analysis. Allyl 2,4,6-tribromophenyl ether (ATE), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) were observed to act as AR antagonists. These BFRs have recently been detected in the environment, in house dust and in aquatic animals. The compounds have been detected at high concentrations in both blubber and brain of seals and we therefore also assessed their impact on the expression of L-type amino acid transporter system (LAT) genes, that are needed for amino acid uptake across the blood-brain barrier, as disruption of LAT gene function has been implicated in several brain disorders. The three BFRs down-regulated the expression of AR target genes that encode for prostate specific antigen (PSA), 5α-reductases and β-microseminoprotein. The potency of PSA inhibition was of the same magnitude as the common prostate cancer drugs, demonstrating that these compounds are strong AR antagonists. Western blot analysis of AR protein showed that ATE, BATE and DPTE decreased the 5α-dihydrotestosterone-induced AR protein levels, further confirming that these BFRs act as AR antagonists. The transcription of the LAT genes was altered by the three BFRs, indicating an effect on amino-acid uptake across cellular membranes and blood-brain barrier. This study demonstrated that ATE, BATE and DPTE are potent AR antagonists and the alterations in LAT gene transcription suggest that these compounds can affect neuronal functions and should be considered as potential neurotoxic and endocrine disrupting compounds.

Jansma AL, Martinez-Yamout MA, Liao R, et al.
The high-risk HPV16 E7 oncoprotein mediates interaction between the transcriptional coactivator CBP and the retinoblastoma protein pRb.
J Mol Biol. 2014; 426(24):4030-48 [PubMed] Article available free on PMC after 12/12/2015 Related Publications
The oncoprotein E7 from human papillomavirus (HPV) strains that confer high cancer risk mediates cell transformation by deregulating host cellular processes and activating viral gene expression through recruitment of cellular proteins such as the retinoblastoma protein (pRb) and the cyclic-AMP response element binding binding protein (CBP) and its paralog p300. Here we show that the intrinsically disordered N-terminal region of E7 from high-risk HPV16 binds the TAZ2 domain of CBP with greater affinity than E7 from low-risk HPV6b. HPV E7 and the tumor suppressor p53 compete for binding to TAZ2. The TAZ2 binding site in E7 overlaps the LxCxE motif that is crucial for interaction with pRb. While TAZ2 and pRb compete for binding to a monomeric E7 polypeptide, the full-length E7 dimer mediates an interaction between TAZ2 and pRb by promoting formation of a ternary complex. Cell-based assays show that expression of full-length HPV16 E7 promotes increased pRb acetylation and that this response depends both on the presence of CBP/p300 and on the ability of E7 to form a dimer. These observations suggest a model for the oncogenic effect of high-risk HPV16 E7. The disordered region of one E7 molecule in the homodimer interacts with the pocket domain of pRb, while the same region of the other E7 molecule binds the TAZ2 domain of CBP/p300. Through its ability to dimerize, E7 recruits CBP/p300 and pRb into a ternary complex, bringing the histone acetyltransferase domain of CBP/p300 into proximity to pRb and promoting acetylation, leading to disruption of cell cycle control.

Bănescu C, Trifa AP, Voidăzan S, et al.
CAT, GPX1, MnSOD, GSTM1, GSTT1, and GSTP1 genetic polymorphisms in chronic myeloid leukemia: a case-control study.
Oxid Med Cell Longev. 2014; 2014:875861 [PubMed] Article available free on PMC after 12/12/2015 Related Publications
Oxidative damage at the DNA level may be promoted by high levels of reactive oxygen species (ROS), leading to genomic instability and increased neoplastic risk. Superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) enzymes are implicated in the prevention of DNA damage by ROS. The aim of the study was to investigate the relationships between CAT C262T, GPX1 Pro198Leu, MnSOD Ala16Val, GSTM1, GSTT1, and GSTP1 Ile105Val polymorphisms and the risk of CML. No association was observed between CML and variant genotypes of GPX1, MnSOD, GSTM1, and GSTT1 polymorphisms in any of the investigated cases. Our study suggests that the homozygous variant genotype of the GSTP1 Ile105Val gene polymorphisms may be associated with the risk of developing CML (OR = 2.5; 95% CI = 1.08-5.7; P value = 0.02), while the heterozygous genotype of the CAT C262T polymorphism seems to have a protective effect against CML (OR = 0.59, 95% CI = 0.39-0.89, P value = 0.01). In most cases, no association was found between laboratory parameters and prognostic factors and the variant genotype of investigated gene polymorphisms. We concluded that CAT, GPX, MnSOD, GSTM1, and GSTT1 gene polymorphisms are not associated with the risk of CML. Variant genotype of the GSTP1 Ile105Val gene polymorphisms may contribute to the risk of developing CML.

Cao D, Jin L, Zhou H, et al.
Inhibition of PGC-1α after chemotherapy-mediated insult confines multiple myeloma cell survival by affecting ROS accumulation.
Oncol Rep. 2015; 33(2):899-904 [PubMed] Related Publications
Peroxisome proliferator‑activated receptor-γ coactivator-1α (PGC-1α) is a key regulator of reactive oxygen species (ROS). However, whether it has the same role in multiple myeloma (MM), especially after treatement with chemotherapy, remains unclear. After treating cells with bortezomib or dexamethasone, the expression of PGC-1α, superoxide dismutase 2 (SOD-2) and catalase (CAT) was examined by RT-PCR. PGC-1α expression was also analyzed by western blotting. Small‑interference RNA (siRNA) was applied to inhibit the expression of PGC-1α after chemotherapy. Changes of cellular ROS and apoptosis were detected by flow cytometric analysis. Cell proliferation was assessed by MTT assay. The expression of PGC-1α and SOD-2 following chemotherapy were upregulated, but accompanied by increased ROS. Following suppression of PGC-1α, ROS levels, as well as the pro-apoptotic effect of bortezomib were further increased. These findings suggested that PGC-1α regulates ROS in MM, and that inhibition of elevated PGC-1α following stimulation by chemotherapy leads to a higher level of ROS by downregulating antioxidant factors, eventually enhancing the antitumor effect of bortezomib.

Huang F, Ma B, Wang Y, et al.
Targeting gene-virus-mediated manganese superoxide dismutase effectively suppresses tumor growth in hepatocellular carcinoma in vitro and in vivo.
Cancer Biother Radiopharm. 2014; 29(10):403-11 [PubMed] Related Publications
Although the treatment methods for hepatocellular carcinoma (HCC) have made a great progress on patient survival rate and life quality, the HCC recurrence still is very high. To explore the novel effective anticancer strategies for HCC, the Cancer Targeting Gene-Viro-Therapy (CTGVT) strategy was applied through oncolytic virus-delivery antitumor gene. In this article, the dual-regulated oncolytic adenovirus Ad-AFP-E1A-E1B(Δ55kDa)-Mn-SOD (briefly named AD55-Mn-SOD) was constructed using a liver cancer-specific α-fetoprotein (AFP) promoter to control replication-essential E1A gene and deliver the novel tumor suppression gene Manganese superoxide dismutase (Mn-SOD). The results indicated that the constructed AD55-Mn-SOD exerted tumor-specific features, and induced dramatic cytotoxicity in HCC cells in vitro and suppress the HCC xenografted growth in nude mice. Moreover, the anticancer mechanism of AD55-Mn-SOD is due to the activation of caspase apoptotic pathway. These data suggested that AD55-Mn-SOD could become a potential anticancer agent for liver cancer.

Ray S, Murmu N, Adhikari J, et al.
Inhibition of Hep G2 hepatic cancer cell growth and CCl₄ induced liver cytotoxicity in Swiss albino mice by Mahua extract.
J Environ Pathol Toxicol Oncol. 2014; 33(4):295-314 [PubMed] Related Publications
Mahua flower extract may provide protective effects against hepatotoxicity. The effect of Mahua flower extract (ME) was investigated on Hep G2 cell line and carbon tetrachloride (CCl4)-induced liver damages in Swiss albino mice. To investigate its cytotoxic effect in liver cancer, Hep G2 cells were treated with different doses of ME, and cell proliferation as well as colony formation assays demonstrated dose-dependent cytotoxicity of ME towards Hep G2 cells in tissue culture. Further gene expression studies showed significant down-regulation of AKT1/2/3, p-AKT, and COX-2 proteins including up-regulation of active caspase-3 in ME treated Hep G2 cells. In in vivo experiments, the mice were pretreated with ME for 15 days. On the 16th day CCl4 was injected intraperitoneally and after 24 h all mice were sacrificed. The antioxidant enzyme activities were measured in liver homogenates. CCl4-induced hepatotoxicity was evidenced by significant increase in lipid peroxidation and decrease in activities of antioxidant enzymes such as GST, GSH, SOD, CAT, and GPx. Histological studies showed CCl4-induced centrilobular necrosis and formation of fatty vacuoles in cirrhotic mice liver. Treatment with ME at a dose of 2 mg and 4 mg/kg exhibited the potential to prevent significant liver toxicity. The expression of active caspase-3 protein was down-regulated in ME treated groups compared to CCl4 exposed animals. This study demonstrated ME mediated antioxidant activity and hepatoprotective effects; therefore it could be used in the future for treating hepatic disorders including liver cancer, especially in combination with chemotherapeutics.

Kim HC, Song JS, Lee JC, et al.
Clinical significance of NQO1 polymorphism and expression of p53, SOD2, PARP1 in limited-stage small cell lung cancer.
Int J Clin Exp Pathol. 2014; 7(10):6743-51 [PubMed] Article available free on PMC after 12/12/2015 Related Publications
BACKGROUND: Small cell lung cancer (SCLC) is one of highly aggressive cancers with poor prognosis. Unfortunately, there are as yet no molecular targets that can be exploited to prolong survival in patients with SCLC. This study aimed to investigate possible molecular markers associated with prognosis in limited-stage small cell lung cancer (LS-SCLC).
METHODS: The demographic and clinical data for LS-SCLC patients treated in a tertiary care hospital between January 2008 and December 2012 were retrospectively reviewed. NQO1 polymorphism and the expression of p53, SOD2, PARP1 were examined in biopsy specimens, and the factors affecting prognosis were identified.
RESULTS: 79 patients with LS-SCLC having available pathologic tissues were analyzed. 84.8% of them received both chemotherapy and radiotherapy. NQO1 polymorphism was detected in 60.0% (45/79; heterozygous in 26 patients, homozygous in 19 patients). Over-expression of p53, SOD2, PARP1 was seen in 45.6% (36/79), 38.0% (30/79) and 41.8% (33/79) of the patients, respectively. The univariate Cox proportional hazards model revealed that serum lactate dehydrogenase (LDH) levels and PARP1 expression were associated with disease progression. In the multivariate analysis, only PARP1 expression was a significant independent prognostic factor for progression-free survival (hazard ratio: 0.494; 95% CI, 0.267-0.913, P = 0.025).
CONCLUSIONS: PARP1 expression is correlated with longer progression-free survival in LS-SCLC requiring further studies to clarify the precise role of PARP1 and the relevance of PARP1-targeted therapy.

Chen SJ, Hoffman NE, Shanmughapriya S, et al.
A splice variant of the human ion channel TRPM2 modulates neuroblastoma tumor growth through hypoxia-inducible factor (HIF)-1/2α.
J Biol Chem. 2014; 289(52):36284-302 [PubMed] Article available free on PMC after 26/12/2015 Related Publications
The calcium-permeable ion channel TRPM2 is highly expressed in a number of cancers. In neuroblastoma, full-length TRPM2 (TRPM2-L) protected cells from moderate oxidative stress through increased levels of forkhead box transcription factor 3a (FOXO3a) and superoxide dismutase 2. Cells expressing the dominant negative short isoform (TRPM2-S) had reduced FOXO3a and superoxide dismutase 2 levels, reduced calcium influx in response to oxidative stress, and enhanced reactive oxygen species, leading to decreased cell viability. Here, in xenografts generated with SH-SY5Y neuroblastoma cells stably expressing TRPM2 isoforms, growth of tumors expressing TRPM2-S was significantly reduced compared with tumors expressing TRPM2-L. Expression of hypoxia-inducible factor (HIF)-1/2α was significantly reduced in TRPM2-S-expressing tumor cells as was expression of target proteins regulated by HIF-1/2α including those involved in glycolysis (lactate dehydrogenase A and enolase 2), oxidant stress (FOXO3a), angiogenesis (VEGF), mitophagy and mitochondrial function (BNIP3 and NDUFA4L2), and mitochondrial electron transport chain activity (cytochrome oxidase 4.1/4.2 in complex IV). The reduction in HIF-1/2α was mediated through both significantly reduced HIF-1/2α mRNA levels and increased levels of von Hippel-Lindau E3 ligase in TRPM2-S-expressing cells. Inhibition of TRPM2-L by pretreatment with clotrimazole or expression of TRPM2-S significantly increased sensitivity of cells to doxorubicin. Reduced survival of TRPM2-S-expressing cells after doxorubicin treatment was rescued by gain of HIF-1 or -2α function. These data suggest that TRPM2 activity is important for tumor growth and for cell viability and survival following doxorubicin treatment and that interference with TRPM2-L function may be a novel approach to reduce tumor growth through modulation of HIF-1/2α, mitochondrial function, and mitophagy.

Autelitano F, Loyaux D, Roudières S, et al.
Identification of novel tumor-associated cell surface sialoglycoproteins in human glioblastoma tumors using quantitative proteomics.
PLoS One. 2014; 9(10):e110316 [PubMed] Article available free on PMC after 26/12/2015 Related Publications
Glioblastoma multiform (GBM) remains clinical indication with significant "unmet medical need". Innovative new therapy to eliminate residual tumor cells and prevent tumor recurrences is critically needed for this deadly disease. A major challenge of GBM research has been the identification of novel molecular therapeutic targets and accurate diagnostic/prognostic biomarkers. Many of the current clinical therapeutic targets of immunotoxins and ligand-directed toxins for high-grade glioma (HGG) cells are surface sialylated glycoproteins. Therefore, methods that systematically and quantitatively analyze cell surface sialoglycoproteins in human clinical tumor samples would be useful for the identification of potential diagnostic markers and therapeutic targets for malignant gliomas. In this study, we used the bioorthogonal chemical reporter strategy (BOCR) in combination with label-free quantitative mass spectrometry (LFQ-MS) to characterize and accurately quantify the individual cell surface sialoproteome in human GBM tissues, in fetal, adult human astrocytes, and in human neural progenitor cells (NPCs). We identified and quantified a total of 843 proteins, including 801 glycoproteins. Among the 843 proteins, 606 (72%) are known cell surface or secreted glycoproteins, including 156 CD-antigens, all major classes of cell surface receptor proteins, transporters, and adhesion proteins. Our findings identified several known as well as new cell surface antigens whose expression is predominantly restricted to human GBM tumors as confirmed by microarray transcription profiling, quantitative RT-PCR and immunohistochemical staining. This report presents the comprehensive identification of new biomarkers and therapeutic targets for the treatment of malignant gliomas using quantitative sialoglycoproteomics with clinically relevant, patient derived primary glioma cells.

Wang CA, Harrell JC, Iwanaga R, et al.
Vascular endothelial growth factor C promotes breast cancer progression via a novel antioxidant mechanism that involves regulation of superoxide dismutase 3.
Breast Cancer Res. 2014; 16(5):462 [PubMed] Article available free on PMC after 26/12/2015 Related Publications
INTRODUCTION: Triple-negative breast cancers, particularly the claudin-low subtype, are highly aggressive and exhibit increased tumor-initiating cell (TIC) characteristics. In this study, we demonstrate that vascular endothelial growth factor C (VEGF-C) is highly expressed in the claudin-low breast cancer subtype and also that it mediates tumor progression, not only through its role in lymphangiogenesis but also through regulating TIC characteristics and the response to reactive oxygen species (ROS).
METHODS: VEGF C expression was examined in breast cancer subtypes, and a VEGF C expression signature was derived. VEGF C expression and/or its associated signature was correlated with TIC and chemoresistance signatures. In vitro and in vivo assays were performed to determine whether VEGF-C expression alters TIC characteristics and the response of breast cancer cells to chemotherapy and oxidative stress. Array analysis was used to identify a downstream effector of VEGF-C, superoxide dismutase 3 (Sod3), which was tested for its involvement in VEGF-C-mediated resistance to oxidative stress and enhancement of in vivo metastasis. The VEGF-C-associated receptor neuropilin 2 (Nrp2) was knocked down to determine whether it is required for the observed effects of VEGF-C. Expression of VEGF C and Sod3 was assessed in human breast cancers.
RESULTS: VEGF C is highly expressed in claudin-low breast cancers, and VEGF C and the VEGF C signature are associated with TIC-related gene signatures. VEGF-C-knockdown in mammary carcinoma cells decreases TIC properties in vitro and in vivo, sensitizing cells to oxidative stress and chemotherapy. We identified Sod3 as a target of VEGF-C in breast cancer cells by demonstrating that it is required for VEGF-C-mediated cell survival in response to oxidative stress and for VEGF-C-mediated metastasis. We demonstrate that Nrp2 is the VEGF-C-associated receptor that mediates alterations in Sod3 expression and the response of tumor cells to oxidative stress. We show that VEGF C and Sod3 are positively associated in human breast cancer.
CONCLUSIONS: We describe a novel mechanism by which VEGF-C contributes to metastasis via its ability to enhance TIC-associated characteristics, particularly the response to ROS. We identified Sod3 as a critical mediator of VEGF-C-induced metastasis, and we provide evidence that the VEGF-C-Sod3 axis plays a role in human breast cancers.

Kim BG, Kwon HY, Sohn EJ, et al.
Activation of caspases and inhibition of ribosome biogenesis mediate antitumor activity of Chijongdan in A549 non-small lung cancer cells.
BMC Complement Altern Med. 2014; 14:420 [PubMed] Article available free on PMC after 26/12/2015 Related Publications
BACKGROUND: Though herbal medicines have been used for cancer prevention and treatment, their scientific evidences still remain unclear so far. Thus, complementary and alternative medicine (CAM) project has been actively executed to reveal the scientific evidences in the USA and other countries. In the present study, we elucidated antitumor mechanism of Chijongdan, an oriental prescription of Rhus verniciflua, processed Panax ginseng, Persicaria tinctoria and Realgar, that has been traditionally applied for cancer treatment in Korea.
METHODS: Chijongdan was prepared with extracts of Rhus verniciflua, processed Panax ginseng, Persicaria tinctoria and processed Realgar. The cytotoxicity of Chijongdan was measured by MTT colorimetric assay. Cell cycle analysis was performed by FACS. Western blot was performed to see the apoptosis related proteins.
RESULTS: Chijongdan significantly exerted cytotoxicity in A549, H460 and H1299 non-small cell lung carcinoma (NSCLC) cells by MTT assay and also increased the number of ethidium homodimer positively stained cells in A549 NSCLC cells. Also, cell cycle analysis showed that Chijongdan increased sub-G1 population in a concentration dependent manner in A549 cells. In addition, Western blotting revealed that Chijongdan activated cleaved PARP, and caspase 9/3, while attenuated the expression of survival genes such as Bcl-2, Bcl-XL and survivin in A549 cells. Furthermore, Chijongdan suppressed the expression of ribosomal biogenesis related proteins such as upstream binding factor (UBF), Fibrillarin, NPM (B23) and Importin-7 (IPO7) and conversely pan-caspase inhibitor Z--VAD-FMK reversed the apoptotic ability of Chijongdan to cleave PARP and caspase 3 and attenuate the expression of UBF and Fibrillarin in A549 cells.
CONCLUSIONS: These findings suggest that Chijongdan induces apoptosis and inhibits ribosomal biogenesis proteins via caspase activation.

Zhao Z, Wu F, Ding S, et al.
Label-free quantitative proteomic analysis reveals potential biomarkers and pathways in renal cell carcinoma.
Tumour Biol. 2015; 36(2):939-51 [PubMed] Related Publications
Renal cell carcinoma (RCC) is one of the most common malignancies in adults, and there is still no acknowledged biomarker for its diagnosis, prognosis, recurrence monitoring, and treatment stratification. Besides, little is known about the post-translational modification (PTM) of proteins in RCC. Here, we performed quantitative proteomic analysis on 12 matched pairs of clear cell RCC (ccRCC) and adjacent kidney tissues using liquid chromatography-tandem mass spectrometry (nanoLCMS/MS) and Progenesis LC-MS software (label-free) to identify and quantify the dysregulated proteins. A total of 1872 and 1927 proteins were identified in ccRCC and adjacent kidney tissues, respectively. Among these proteins, 1037 proteins were quantified by Progenesis LC-MS, and 213 proteins were identified as dysregulated proteins between ccRCC and adjacent tissues. Pathway analysis using IPA, STRING, and David tools was performed, which demonstrated the enrichment of cancer-related signaling pathways and biological processes such as mitochondrial dysfunction, metabolic pathway, cell death, and acetylation. Dysregulation of two mitochondrial proteins, acetyl-CoA acetyltransferase 1 (ACAT1) and manganese superoxide dismutase (MnSOD) were selected and confirmed by Western blotting and immunohistochemistry assays using another 6 pairs of ccRCC and adjacent tissues. Further mass spectrometry analysis indicated that both ACAT1 and MnSOD had characterized acetylation at lysine residues, which is the first time to identify acetylation of ACAT1 and MnSOD in ccRCC. Collectively, these data revealed a number of dysregulated proteins and signaling pathways by label-free quantitative proteomic approach in RCC, which shed light on potential diagnostic or prognostic biomarkers and therapeutic molecular targets for clinical intervention of RCC.

Monga J, Aggarwal V, Suthar SK, et al.
Topical (+)-catechin emulsified gel prevents DMBA/TPA-induced squamous cell carcinoma of the skin by modulating antioxidants and inflammatory biomarkers in BALB/c mice.
Food Funct. 2014; 5(12):3197-207 [PubMed] Related Publications
An emulsified gel of (+)-catechin was developed and evaluated topically against 7,12-dimethylbenz(a)anthracene-induced and 12-O-tetradecanoylphorbol-13-acetate-promoted (DMBA-induced and TPA-promoted) squamous cell carcinoma of the skin in BALB/c mice. The biological evaluation outcome indicated that the (+)-catechin emulsified gel increased the activity of oxidative stress biomarkers glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR), and glutathione peroxidase (GPx), whereas it decreased the level of malondialdehyde (MDA). The mechanistic study showed that genes implicated in the inflammation and cancer, such as cyclooxygenase-2 (COX-2), nuclear factor-kappa B (NF-κB), and inducible nitric-oxide synthase (iNOS), were down-regulated by (+)-catechin emulsified gel while inhibiting an inflammatory mediator prostaglandin E2 (PGE2). The (+)-catechin emulsified gel further suppressed the activity of pro-inflammatory cytokines, viz. tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6). The in vitro permeation study revealed that release of (+)-catechin from an emulsified gel base reached a steady state after 6 h, while pH of the entire emulsified gel was found to be between 6.2 and 6.5 that falls well within the normal pH range of the skin.

Su B, Shi B, Tang Y, et al.
HMGN5 knockdown sensitizes prostate cancer cells to ionizing radiation.
Prostate. 2015; 75(1):33-44 [PubMed] Related Publications
BACKGROUND: High Mobility Group N (HMGN) proteins are a family of chromatin structural proteins that specifically bind to nucleosome core particles. HMGN5 is a novel and characteristic member of the HMGN protein family. We have previously found that HMGN5 is upregulated in prostate cancer and its downregulation had been demonstrated to induce apoptosis and G2-M cell cycle arrest.
METHODS: The radiosensitization effect of HMGN5 knockdown on PC3 and DU145 cells was assessed using clonogenic assay, flow cytometry, and comet assay. The DNA double-strand break (DSB) repair kinetics of HMGN5 knockdown and control cells after radiation exposure was evaluated using immunocytofluorescence. The mitochondrial reactive oxygen species (ROS) levels were estimated using Dihydrorhodamine 123 (DHR 123) probes. Expression of mitochondrial antioxidant MnSOD was measured by real-time PCR and Western blot. The expression of antiapoptotic proteins Bcl-2 and Bcl-xL as well as cleavage of caspase-3, caspase-9, and PARP were also measured using Western blot.
RESULTS: HMGN5 knockdown cells exhibit decreased clonogenic survival and increased apoptosis rate in response to 2-8 Gy ionizing radiation (IR). Loss of HMGN5 does not affect the DSB repair kinetics after radiation exposure. HMGN5 knockdown cells demonstrated increased mitochondrial ROS level and suppressed induction of MnSOD upon radiation compared with control cells upon radiation. Further, MnSOD knockdown resulted in inhibited cell viability as well as increased mitochondrial ROS level and apoptosis upon radiation in PC3 and DU145 cells. Finally, HMGN5 knockdown cells showed significantly decreased levels of antiapoptotic proteins Bcl-2 and Bcl-xL as well as increased cleavage of caspase-3, caspase-9, and PARP compared with control cells after radiation.
CONCLUSIONS: HMGN5 knockdown sensitizes prostate cancer cells to ionizing radiation, and the radiosensitization effect may be partially mediated through suppressed induction of MnSOD and enhanced activation of apoptosis pathway in response to IR.

Chekhun SV, Lukyanova NY, Shvets YV, et al.
Significance of ferritin expression in formation of malignant phenotype of human breast cancer cells.
Exp Oncol. 2014; 36(3):179-83 [PubMed] Related Publications
AIM: The aim of our study is to investigate the disorders of ferritin functioning in breast cancer (BC) cells of different molecular subtype.
MATERIALS AND METHODS: The cell lines used in the analysis include T47D, MCF-7, MDA-MB-231, MDA-MB-468, MCF-10A, and 184A1. Ferritin heavy chains (FTH) expression was studied by immunohistochemical method. "Free iron" content and superoxide dismutase (SOD) activity were determined by means of EPR spectroscopy. Reactive oxygen species (ROS) level and peculiarities of microRNA expression in studied cell lines were evaluated using flow cytometry and PCR analysis, respectively.
RESULTS: It has been demonstrated that FTH expression directly correlates with proliferative activity of cells of both luminal (r = 0.51) and basal subtypes (r = 0.25), inversely correlates with expression of steroid hormones in cells of basal subtype (ER: r = -0.46; PR: r = -0.44) and does not depend on tumorigenic activity of both subtypes of studied cells (r = 0.12 and r = 0.9). Obtained data are the evidence that cells of luminal subtype B (MCF-7 cell line) and basal subtype (MDA-MB-231 and MDA-MB-468 cell lines) with high proliferative activity contain the highest level of free iron (2.9 ± 0.19·10(16)and 3.0 ± 0.22·10(16)) that can be consequence of intensive use of this element by cells, which actively divide and grow. Along with it, in cell of lines of basal subtype MDA-MB-231 and MDA-MB-468, high level of FTH (254 ± 2.3 and 270 ± 1.9) is being detected in consequence of increase of level of free iron, ROS (11.3 ± 1.05 and 7.27 ± 0.26) and SOD (9.4 ± 0.24 and 8.5 ± 0.18) as well as decrease of expression of microRNA 200b. In contrast, cells of luminal subtype B of MCF-7 line were distinguished by high expression of microRNA 200b and low ferritin level (125 ± 2.7).
CONCLUSION: Obtained data demonstrate that tumor cells, which are referred to different molecular subtypes, are characterized by changes in system of support of balance of intercellular iron and certain associations of studied factors.

Zhang CX, Qin YM, Guo LK
Correlations between polymorphisms of extracellular superoxide dismutase, aldehyde dehydrogenase-2 genes, as well as drinking behavior and pancreatic cancer.
Chin Med Sci J. 2014; 29(3):162-6 [PubMed] Related Publications
OBJECTIVE: To investigate the correlation between drinking behavior combined with polymorphisms of extracellular superoxide dismutase (EC-SOD) and aldehyde dehydrogenase-2 (ALDH2) genes and pancreatic cancer.
METHODS: The genetic polymorphisms of EC-SOD and ALDH2 were analyzed by polymerase chain reaction restriction fragment length polymorphism in the peripheral blood leukocytes obtained from 680 pancreatic cancer cases and 680 non-cancer controls. Subsequently the frequency of genotype was compared between the pancreatic cancer patients and the healthy controls.The relationship of drinking with pancreatic cancer was analyzed.
RESULTS: The frequencies of EC-SOD (C/G) and ALDH2 variant genotypes were 37.35% and 68.82% respectively in the pancreatic cancer cases, and were significantly higher than those in the healthy controls (21.03% and 44.56%, all P<0.01). People who carried EC-SOD (C/G) (OR=2.24, 95% CI= 1.81-4.03, P<0.01) or ALDH2 variant genotypes (OR=2.75, 95% CI=1.92-4.47, P<0.01) had a high risk to develop pancreatic cancer. Those who carried EC-SOD (C/G) genotype combined with ALDH2 variant genotype had a high risk for pancreatic cancer (29.56% vs. 6.76%, OR=7.69, 95% CI=3.58-10.51, P<0.01). The drinking rate of the pancreatic cancer group (64.12%) was significantly higher than that of the control group (40.15%; OR=2.66, 95% CI=1.30-4.42, P<0.01). An interaction between drinking and EC-SOD (C/G)/ALDH2 variant genotypes increased the risk of occurrence of pancreatic cancer (OR=25.00, 95% CI= 11.87-35.64, P<0.01).
CONCLUSION: EC-SOD (C/G), ALDH2 variant genotypes and drinking might be the risk factors of pancreatic cancer.

Eckers JC, Kalen AL, Sarsour EH, et al.
Forkhead box M1 regulates quiescence-associated radioresistance of human head and neck squamous carcinoma cells.
Radiat Res. 2014; 182(4):420-9 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
Cellular quiescence is a reversible growth arrest in which cells retain their ability to enter into and exit from the proliferative cycle. This study investigates the hypothesis that cell growth-state specific oxidative stress response regulates radiosensitivity of cancer cells. Results showed that quiescent (low proliferative index; >75% G1 phase and lower RNA content) Cal27 and FaDu human head and neck squamous cell carcinoma (HNSCC) are radioresistant compared to proliferating cells. Quiescent cells exhibited a three to tenfold increase in mRNA levels of Mn-superoxide dismutase (MnSOD), dual oxidase 2 (DUOX2) and dual-specificity phosphatase 1 (DUSP1), while mRNA levels of catalase (CAT), peroxiredoxin 3 (PRDX3) and C-C motif ligand 5 (CCL5) were approximately two to threefold lower compared to proliferating cells. mRNA levels of forkhead box M1 (FOXM1) showed the largest decrease in quiescent cells at approximately 18-fold. Surprisingly, radiation treatment resulted in a distinct gene expression pattern that is specific to proliferating and quiescent cells. Specifically, FOXM1 expression increased two to threefold in irradiated quiescent cells, while the same treatment had no net effect on FOXM1 mRNA expression in proliferating cells. RNA interference and pharmacological-based downregulation of FOXM1 abrogated radioresistance of quiescent cells. Furthermore, radioresistance of quiescent cells was associated with an increase in glucose consumption and expression of glucose-6-phosphate dehydrogenase (G6PD). Knockdown of FOXM1 resulted in a significant decrease in G6PD expression, and pharmacological-inhibition of G6PD sensitized quiescent cells to radiation. Taken together, these results suggest that targeting FOXM1 may overcome radioresistance of quiescent HNSCC.

Becuwe P, Ennen M, Klotz R, et al.
Manganese superoxide dismutase in breast cancer: from molecular mechanisms of gene regulation to biological and clinical significance.
Free Radic Biol Med. 2014; 77:139-51 [PubMed] Related Publications
Breast cancer is one of the most common malignancies of all cancers in women worldwide. Many difficulties reside in the prediction of tumor metastatic progression because of the lack of sufficiently reliable predictive biological markers, and this is a permanent preoccupation for clinicians. Manganese superoxide dismutase (MnSOD) may represent a rational candidate as a predictive biomarker of breast tumor metastatic progression, because its gene expression is profoundly altered between early and advanced breast cancer, in contrast to expression in the normal mammary gland. In this review, we report the characterization of some gene polymorphisms and molecular mechanisms of SOD2 gene regulation, which allows a better understanding of how MnSOD is decreased in early breast cancer and increased in advanced breast cancer. Several studies display the biological significance of MnSOD level in proliferation as well as in invasive and angiogenic abilities of breast tumor cells by controlling superoxide anion radical (O2(•-)) and hydrogen peroxide (H2O2). Particularly, they report how these reactive oxygen species may activate some signaling pathways involved in breast tumor growth. Emerging understanding of these findings provides an interesting framework for guiding translational research and suggests a way to define precisely the clinical interest of MnSOD as a prognostic and/or predicting marker in breast cancer, by associating with some regulators involved in SOD2 gene regulation and other well-known biomarkers, in addition to the typical clinical parameters.

White PA, Oliveira RC, Oliveira AP, et al.
Antioxidant activity and mechanisms of action of natural compounds isolated from lichens: a systematic review.
Molecules. 2014; 19(9):14496-527 [PubMed] Related Publications
Chronic diseases such as cancer, diabetes, neurodegenerative and cardiovascular diseases are characterized by an enhanced state of oxidative stress, which may result from the overproduction of reactive species and/or a decrease in antioxidant defenses. The search for new chemical entities with antioxidant profile is still thus an emerging field on ongoing interest. Due to the lack of reviews concerning the antioxidant activity of lichen-derived natural compounds, we performed a review of the antioxidant potential and mechanisms of action of natural compounds isolated from lichens. The search terms "lichens", "antioxidants" and "antioxidant response elements" were used to retrieve articles in LILACS, PubMed and Web of Science published until February 2014. From a total of 319 articles surveyed, 32 met the established inclusion and exclusion criteria. It was observed that the most common isolated compound studied was usnic acid, cited in 14 out of the 32 articles. The most often described antioxidant assays for the study of in vitro antioxidant activity were mainly DPPH, LPO and SOD. The most suggested mechanisms of action were scavenging of reactive species, enzymatic activation and inhibition of iNOS. Thus, compounds isolated from lichens are possible candidates for the management of oxidative stress, and may be useful in the treatment of chronic diseases.

Laafi J, Homedan C, Jacques C, et al.
Pro-oxidant effect of ALA is implicated in mitochondrial dysfunction of HepG2 cells.
Biochimie. 2014; 106:157-66 [PubMed] Related Publications
Heme biosynthesis begins in the mitochondrion with the formation of delta-aminolevulinic acid (ALA). In acute intermittent porphyria, hereditary tyrosinemia type I and lead poisoning patients, ALA is accumulated in plasma and in organs, especially the liver. These diseases are also associated with neuromuscular dysfunction and increased incidence of hepatocellular carcinoma. Many studies suggest that this damage may originate from ALA-induced oxidative stress following its accumulation. Using the MnSOD as an oxidative stress marker, we showed here that ALA treatment of cultured cells induced ROS production, increasing with ALA concentration. The mitochondrial energetic function of ALA-treated HepG2 cells was further explored. Mitochondrial respiration and ATP content were reduced compared to control cells. For the 300 μM treatment, ALA induced a mitochondrial mass decrease and a mitochondrial network imbalance although neither necrosis nor apoptosis were observed. The up regulation of PGC-1, Tfam and ND5 genes was also found; these genes encode mitochondrial proteins involved in mitochondrial biogenesis activation and OXPHOS function. We propose that ALA may constitute an internal bioenergetic signal, which initiates a coordinated upregulation of respiratory genes, which ultimately drives mitochondrial metabolic adaptation within cells. The addition of an antioxidant, Manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), resulted in improvement of maximal respiratory chain capacity with 300 μM ALA. Our results suggest that mitochondria, an ALA-production site, are more sensitive to pro-oxidant effect of ALA, and may be directly involved in pathophysiology of patients with inherited or acquired porphyria.

Son YO, Pratheeshkumar P, Roy RV, et al.
Nrf2/p62 signaling in apoptosis resistance and its role in cadmium-induced carcinogenesis.
J Biol Chem. 2014; 289(41):28660-75 [PubMed] Article available free on PMC after 10/10/2015 Related Publications
The cadmium-transformed human lung bronchial epithelial BEAS-2B cells exhibit a property of apoptosis resistance as compared with normal non-transformed BEAS-2B cells. The level of basal reactive oxygen species (ROS) is extremely low in transformed cells in correlation with elevated expressions of both antioxidant enzymes (catalase, SOD1, and SOD2) and antiapoptotic proteins (Bcl-2/Bcl-xL). Moreover, Nrf2 and p62 are highly expressed in these transformed cells. The knockdown of Nrf2 or p62 by siRNA enhances ROS levels and cadmium-induced apoptosis. The binding activities of Nrf2 on the antioxidant response element promoter regions of p62/Bcl-2/Bcl-xL were dramatically increased in the cadmium-exposed transformed cells. Cadmium exposure increased the formation of LC3-II and the frequency of GFP-LC3 punctal cells in non-transformed BEAS-2B cells, whereas these increases are not shown in transformed cells, an indication of autophagy deficiency of transformed cells. Furthermore, the expression levels of Nrf2 and p62 are dramatically increased during chronic long term exposure to cadmium in the BEAS-2B cells as well as antiapoptotic proteins and antioxidant enzymes. These proteins are overexpressed in the tumor tissues derived from xenograft mouse models. Moreover, the colony growth is significantly attenuated in the transformed cells by siRNA transfection specific for Nrf2 or p62. Taken together, this study demonstrates that cadmium-transformed cells have acquired autophagy deficiency, leading to constitutive p62 and Nrf2 overexpression. These overexpressions up-regulate the antioxidant proteins catalase and SOD and the antiapoptotic proteins Bcl-2 and Bcl-xL. The final consequences are decrease in ROS generation, apoptotic resistance, and increased cell survival, proliferation, and tumorigenesis.

Dinić J, Novaković M, Podolski-Renić A, et al.
Antioxidative activity of diarylheptanoids from the bark of black alder (Alnus glutinosa) and their interaction with anticancer drugs.
Planta Med. 2014; 80(13):1088-96 [PubMed] Related Publications
Diarylheptanoids belong to polyphenols, a group of plant secondary metabolites with multiple biological properties. Many of them display antioxidative, cytotoxic, or anticancer actions and are increasingly recognized as potential therapeutic agents. The aim of this study was to evaluate antioxidant and cytoprotective activity of two diarylheptanoids: platyphylloside 5(S)-1,7-di(4-hydroxyphenyl)-3-heptanone-5-O-β-D-glucopyranoside (1) and its newly discovered analog 5(S)-1,7-di(4-hydroxyphenyl)-5-O-β-D-[6-(E-p-coumaroylglucopyranosyl)]heptane-3-one (2), both isolated from the bark of black alder (Alnus glutinosa). To that end, we have employed a cancer cell line (NCI-H460), normal human keratinocytes (HaCaT), and peripheral blood mononuclear cells. The effects on cell growth were assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay. Cell death was examined by annexin V/propidium iodide staining on a flow cytometer. Reactive oxygen species production was examined by dihydroethidium staining. Mitochondrial structure and doxorubicin localization were visualized by fluorescent microscopy. Gene expression of manganese superoxide dismutase and hypoxia-inducible factor-1α was determined by reverse transcription polymerase chain reaction. Diarylheptanoids antagonized the effects of either doxorubicin or cisplatin, significantly increasing their IC50 values in normal cells. Diarylheptanoid 1 induced the retention of doxorubicin in cytoplasm and reduced mitochondrial fragmentation associated with doxorubicin application. Diarylheptanoid 2 reduced the reactive oxygen species production induced by cisplatin. Both compounds increased the messenger ribonucleic acid expression of enzymes involved in reactive oxygen species elimination (manganese superoxide dismutase and hypoxia-inducible factor-1α). These results indicate that neutralization of reactive oxygen species is an important mechanism of diarylheptanoid action, although these compounds exert a considerable anticancer effect. Therefore, these compounds may serve as protectors of normal cells during chemotherapy without significantly diminishing the effect of the applied chemotherapeutic.

Chatterjee A, Ronghe A, Singh B, et al.
Natural antioxidants exhibit chemopreventive characteristics through the regulation of CNC b-Zip transcription factors in estrogen-induced breast carcinogenesis.
J Biochem Mol Toxicol. 2014; 28(12):529-38 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
UNLABELLED: The objective of the present study was to characterize the role of resveratrol (Res) and vitamin C (VC) in prevention of estrogen-induced breast cancer through regulation of cap "n"collar (CNC) b-zip transcription factors. Human breast epithelial cell line MCF-10A was treated with 17β-estradiol (E2) and VC or Res with or without E2. mRNA and protein expression levels of CNC b-zip transcription factors nuclear factor erythroid 2-related factor 1 (Nrf1), nuclear factor erythroid 2 related factor 2 (Nrf2), nuclear factor erythroid 2 related factor 3 (Nrf3), and Nrf2-regulated antioxidant enzymes superoxide dismutase 3 (SOD3) and
NAD(P)H: quinone oxidoreductase 1 (NQO1) were quantified. The treatment with E2 suppressed, whereas VC and Res prevented E2-mediated decrease in the expression levels of SOD3, NQO1, Nrf2 mRNA, and protein in MCF-10A cells. The treatment with E2, Res, or VC significantly increased mRNA and protein expression levels of Nrf1. 17β-Estradiol treatment significantly increased but VC or Res decreased Nrf3 mRNA and protein expression levels. Our studies demonstrate that estrogen-induced breast cancer might be prevented through upregulation of antioxidant enzymes via Nrf-dependent pathways.

Moghadamtousi SZ, Kadir HA, Paydar M, et al.
Annona muricata leaves induced apoptosis in A549 cells through mitochondrial-mediated pathway and involvement of NF-κB.
BMC Complement Altern Med. 2014; 14:299 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
BACKGROUND: Annona muricata leaves have been reported to have antiproliferative effects against various cancer cell lines. However, the detailed mechanism has yet to be defined. The current study was designed to evaluate the molecular mechanisms of A. muricata leaves ethyl acetate extract (AMEAE) against lung cancer A549 cells.
METHODS: The effect of AMEAE on cell proliferation of different cell lines was analyzed by MTT assay. High content screening (HCS) was applied to investigate the suppression of NF-κB translocation, cell membrane permeability, mitochondrial membrane potential (MMP) and cytochrome c translocation from mitochondria to cytosol. Reactive oxygen species (ROS) formation, lactate dehydrogenase (LDH) release and activation of caspase-3/7, -8 and -9 were measured while treatment. The western blot analysis also carried out to determine the protein expression of cleaved caspase-3 and -9. Flow cytometry analysis was used to determine the cell cycle distribution and phosphatidylserine externalization. Quantitative PCR analysis was performed to measure the gene expression of Bax and Bcl-2 proteins.
RESULTS: Cell viability analysis revealed the selective cytotoxic effect of AMEAE towards lung cancer cells, A549, with an IC50 value of 5.09 ± 0.41 μg/mL after 72 h of treatment. Significant LDH leakage and phosphatidylserine externalization were observed in AMEAE treated cells by fluorescence analysis. Treatment of A549 cells with AMEAE significantly elevated ROS formation, followed by attenuation of MMP via upregulation of Bax and downregulation of Bcl-2, accompanied by cytochrome c release to the cytosol. The incubation of A549 cells with superoxide dismutase and catalase significantly attenuated the cytotoxicity caused by AMEAE, indicating that intracellular ROS plays a pivotal role in cell death. The released cytochrome c triggered the activation of caspase-9 followed by caspase-3. In addition, AMEAE-induced apoptosis was accompanied by cell cycle arrest at G0/G1 phase. Moreover, AMEAE suppressed the induced translocation of NF-κB from cytoplasm to nucleus.
CONCLUSIONS: Our data showed for the first time that the ethyl acetate extract of Annona muricata inhibited the proliferation of A549 cells, leading to cell cycle arrest and programmed cell death through activation of the mitochondrial-mediated signaling pathway with the involvement of the NF-kB signalling pathway.

Briehl MM, Tome ME, Wilkinson ST, et al.
Mitochondria and redox homoeostasis as chemotherapeutic targets.
Biochem Soc Trans. 2014; 42(4):939-44 [PubMed] Related Publications
Characteristics of cancer cells include a more oxidized redox environment, metabolic reprogramming and apoptosis resistance. Our studies with a lymphoma model have explored connections between the cellular redox environment and cancer cell phenotypes. Alterations seen in lymphoma cells made resistant to oxidative stress include: a more oxidized redox environment despite increased expression of antioxidant enzymes, enhanced net tumour growth, metabolic changes involving the mitochondria and resistance to the mitochondrial pathway to apoptosis. Of particular importance, the cells show cross-resistance to multiple chemotherapeutic agents used to treat aggressive lymphomas. Analyses of clinical and tumour data reveal the worst prognosis when patients' lymphomas have gene expression patterns consistent with the most oxidized redox environment. Lymphomas from patients with the worst survival outcomes express increased levels of proteins involved in oxidative phosphorylation, including cytochrome c. This is consistent with these cells functioning as metabolic opportunists. Using lymphoma cell models and primary lymphoma cultures, we observed enhanced killing using genetic and drug approaches which further oxidize the cellular redox environment. These approaches include increased expression of SOD2 (superoxide dismutase 2), treatment with a manganoporphyrin that oxidizes the glutathione redox couple, or treatment with a copper chelator that inhibits SOD1 and leads to peroxynitrite-dependent cell death. The latter approach effectively kills lymphoma cells that overexpress the anti-apoptotic protein Bcl-2. Given the central role of mitochondria in redox homoeostasis, metabolism and the intrinsic pathway to apoptosis, our studies support the development of new anti-cancer drugs to target this organelle.

Low IC, Loh T, Huang Y, et al.
Ser70 phosphorylation of Bcl-2 by selective tyrosine nitration of PP2A-B56δ stabilizes its antiapoptotic activity.
Blood. 2014; 124(14):2223-34 [PubMed] Related Publications
Bcl-2 is frequently overexpressed in hematopoietic malignancies, and selective phosphorylation at ser70 enhances its antiapoptotic activity. Phospho-ser70 is dephosphorylated by specific heterotrimers of protein phosphatase 2A (PP2A). We report here that a mild pro-oxidant intracellular milieu induced by either pharmacological inhibition or genetic knockdown of superoxide dismutase 1 (SOD1) inhibits the functional holoenzyme assembly of PP2A and prevents Bcl-2 ser70 dephosphorylation. This redox-dependent regulation of Bcl-2 phosphorylation is due to nitrosative modification of B56δ, which we identify as the regulatory subunit mediating PP2A-dependent Bcl-2 dephosphorylation. Redox inhibition of PP2A results from peroxynitrite-mediated nitration of a conserved tyrosine residue within B56δ (B56δ(Y289)). Although nitrated B56δ(Y289) binds efficiently to ser70-phosphorylated Bcl-2, this specific modification inhibits the recruitment of the PP2A catalytic core (A and C subunits). Furthermore, inhibition of B56δ(Y289) nitration restores PP2A holoenzyme assembly, thereby permitting S70 dephosphorylation of Bcl-2 and inhibiting its antiapoptotic activity. More important, in primary cells derived from clinical lymphomas, Bcl-2 phosphorylation at S70 directly correlates with B56δ nitration and repression of SOD1, but inversely correlates with B56δ interaction with the PP2A-C catalytic subunit. These data underscore the role of a pro-oxidant milieu in chemoresistance of hematopoietic and other cancers via selective targeting of tumor suppressors such as PP2A.

Chen L, Xu WM, Zhang D
Association of abdominal obesity, insulin resistance, and oxidative stress in adipose tissue in women with polycystic ovary syndrome.
Fertil Steril. 2014; 102(4):1167-1174.e4 [PubMed] Related Publications
OBJECTIVE: To study the expression of insulin signaling-related genes and oxidative stress markers in the visceral adipose tissue obtained from polycystic ovary syndrome (PCOS) patients and healthy control subjects and to investigate the relationships among abdominal obesity, insulin resistance, and oxidative stress at the tissue level.
DESIGN: Case-control study.
SETTING: University teaching hospital.
PATIENT(S): In total, 30 PCOS patients and 30 healthy control subjects, who underwent laparoscopic surgery, were included in the study.
INTERVENTION(S): Abdominal obesity was defined based on waist circumference (WC). The homeostasis model index was used to assess insulin resistance (HOMA-IR).
MAIN OUTCOME MEASURE(S): Gene expression of glucose transporter 4 (GLUT4) and insulin receptor substrate 1 (IRS1) in visceral adipose tissue (VAT) and the parameters of oxidative stress, such as superoxide dismutase, enzyme glutathione reductase, and dimethylarginine, were measured, and the expression of protein oxidative damage product 3-nitro-tyrosine residues (nitrotyrosine) in VAT was identified with the use of immunohistochemistry.
RESULT(S): PCOS was associated with lower expression of GLUT4 and IRS1 and a higher level of oxidative stress in VAT, which was strongly correlated with WC and HOMA-IR. Presence of abdominal obesity further intensified the correlations observed in our measurements. The nitrotyrosine expression in VAT was stronger in PCOS patients.
CONCLUSION(S): The strong correlation of insulin resistance with oxidative stress at the VAT level suggests that local oxidative stress and abnormalities of insulin signaling in adipose tissue play critical roles in the pathogenesis of PCOS.

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