The inhibitor of the redox activity of APE1/REF-1, APX2009, reduces the malignant phenotype of breast cancer cells

Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/REF-1) is a multifunctional protein acting on cellular signaling pathways, including DNA repair and redox activities. APE1/REF-1 has emerged as a target for cancer therapy, and its role in breast cancer models would reveal new strategies for cancer therapy. APX2009 is a specific APE1/REF-1 redox inhibitor whose anticancer properties have not been described in breast cancer cells. Here, we investigated the effect of the APX2009 treatment in the breast cancer cell lines MDA-MB-231 and MCF-7. Breast cancer cell lines were cultured, and WST1 and colony formation assays were performed to evaluate cell proliferation. Annexin V-FITC/7-AAD and LDH-Glo™ assays were performed to evaluate cell death. The wound healing assay and Matrigel transwell assay were performed after APX2009 treatment to evaluate the cellular migration and invasion processes, respectively. Our findings demonstrated that APX2009 treatment decreased breast cancer cell proliferative, migratory, and invasive properties. Furthermore, it induced apoptosis in both cell lines. Our study is the first to show the effects of APX2009 treatment on apoptosis in a breast cancer cell. Therefore, this study suggested that APX2009 treatment is a promising anticancer molecule for breast cancer.

Análise da imunoexpressão de proteínas de reparo do DNA envolvidas nas vias BER e NER em lesões odontogênicas epiteliais benignas / Immunoexpression analysis of DNA repair proteins involved in BER and NER pathways in benign epithelial odontogenic lesions

As lesões odontogênicas epiteliais benignas apresentam comportamento biológico heterogêneo e patogênese ainda não totalmente esclarecida. As vias de reparo do ácido desoxirribonucleico (DNA) atuam em tipos específicos de danos ao material genético, realizando o reparo e regulando diversos processos celulares. Dentre as principais vias de reparo do DNA, destacamse o reparo por excisão de bases (BER) e o reparo por excisão de nucleotídeos (NER). Investigações têm demonstrado que as proteínas envolvidas nessas vias se encontram desreguladas e, por vezes, altamente expressas em algumas neoplasias malignas, contribuindo para a progressão tumoral. Levando em consideração a heterogeneidade do comportamento biológico das lesões odontogênicas epiteliais benignas e a escassez de estudos que tenham avaliado a expressão de proteínas de reparo do DNA nestas lesões, este trabalho avaliou a imunoexpressão de proteínas da via BER (APE-1 e XRCC-1) e NER (XPF) em ameloblastomas (AMEs) sólidos (n = 30), ceratocistos odontogênicos não sindrômicos (CONS) (n = 30), ceratocistos odontogênicos sindrômicos (COS) (associados à Síndrome de Gorlin) (n = 29), cistos dentígeros (CDs) (n = 30) e folículos dentários (FDs) (n = 20). A análise da expressão imunoistoquímica de APE-1, XRCC-1 e XPF foi realizada de forma quantitativa por um avaliador previamente calibrado e sem acesso aos dados clínicos dos casos. Em cinco campos de maior imunorreatividade, foram quantificadas as células positivas e negativas para as proteínas no componente epitelial de todos os casos, sendo estabelecido o percentual de células positivas em relação ao número total de células contadas para cada anticorpo. As marcações nucleares e citoplasmáticas foram analisadas separadamente para APE-1 e XPF, enquanto apenas a imunoexpressão nuclear foi considerada para XRCC-1. As comparações das medianas dos percentuais de imunorreatividade em relação aos grupos estudados foram realizadas por meio dos testes não paramétricos de Kruskal-Wallis e Mann-Whitney. Possíveis correlações entre a expressão de APE-1, XRCC-1 e XPF foram avaliadas por meio do teste de correlação de Spearman. O nível de significância foi estabelecido em 5% (p < 0,05). Foi verificada uma maior imunoexpressão nuclear de APE-1 nos CONSs, COSs e AMEs sólidos, em comparação com os CDs (p < 0,001). Dentre todos os grupos avaliados, a expressão citoplasmática de APE1 só foi encontrada em 4 CONSs e 6 COSs. A expressão nuclear de XRCC-1 foi estatisticamente maior nos CONSs e COSs em relação aos CDs (p < 0,05). Em nível nuclear, a expressão de XPF foi significativamente maior nos CONSs e COSs em relação aos CDs e AMEs (p < 0,05) e, embora sem significância estatística, foi observada uma maior expressão nuclear dessa proteína nos AMEs quando comparado aos CDs. Em relação à expressão citoplasmática de XPF, foi observada uma maior expressão nos COSs em relação aos CDs (p = 0,04). Nenhuma diferença estatisticamente significativa foi encontrada entre as expressões nucleares de APE-1, XRCC-1 e XPF entre CONSs e COSs (p > 0,05). Além disso, todas as lesões odontogênicas estudadas revelaram uma maior expressão estatisticamente significativa de APE-1 (nuclear), XRCC-1 (nuclear) e XPF (nuclear e citoplasmática) quando comparados aos FDs (p < 0,05). Para todas as lesões, o teste de correlação de Spearman mostrou uma correlação positiva entre a expressão nuclear de APE-1 e XRCC-1 ou XPF, em nível nuclear (p < 0,05). Os resultados deste estudo sugerem um potencial envolvimento das proteínas APE-1, XRCC-1 e XPF na patogênese das lesões odontogênicas epiteliais benignas, com destaque para aquelas com comportamento biológico mais agressivo (AU).

The benign epithelial odontogenic lesions present a heterogeneous biological behavior and their pathogenesis are not fully understood. The deoxyribonucleic acid (DNA) repair pathways act on specific types of damage to the genetic material, performing the repair and regulating several cellular processes. Among the main DNA repair pathways, the most notable are the base excision repair (BER) and the nucleotide excision repair (NER). Investigations have shown that the proteins involved in these pathways are deregulated and sometimes highly expressed in some malignancies, contributing to tumor progression. Taking into account the heterogeneity of the biological behavior of benign epithelial odontogenic lesions and the scarcity of studies that have evaluated the expression of DNA repair proteins in these lesions, this study evaluated the immunoexpression of BER (APE-1 and XRCC-1) proteins and NER (XPF) in solid ameloblastomas (AMEs) (n = 30), non-syndromic odontogenic keratocysts (NSOKCs) (n = 30), syndromic odontogenic keratocysts (SKOCs) (associated with Gorlin's Syndrome) (n = 29), dentigerous cysts (DCs) (n = 30) and dental follicles (DFs) (n = 20). The immunohistochemical analysis of APE-1, XRCC-1 and XPF was performed quantitatively by a previously calibrated evaluator and without access to the clinical data of the cases. In five fields of higher immunoreactivity, positive and negative cells were quantified for the proteins in the epithelial component of all cases, and the percentage of positive cells was established in relation to the total number of cells counted for each antibody. Nuclear and cytoplasmic markers were analyzed separately for APE-1 and XPF, while only nuclear immunoexpression was considered for XRCC-1. The comparisons of the median percentages of immunoreactivity in relation to the studied groups were performed using the non-parametric Kruskal-Wallis and MannWhitney tests. Possible correlations between the expression of APE-1, XRCC-1 and XPF were assessed by Spearman's correlation test. The level of significance was set at 5% (p < 0.05). A higher nuclear immunoexpression of APE-1 in the NSOKCs, SOKCs and solid AMEs was verified in comparison with the DCs (p < 0.001). Among all the evaluated groups, the cytoplasmic expression of APE-1 was only found in 4 NSOKCs and 6 SOKCs. Nuclear expression of XRCC-1 was statistically higher in NSOKCs and SOKCs than in DCs (p < 0.05). At the nuclear level, XPF expression was significantly higher in NSOKCs and SOKCs than in DCs and AMEs (p < 0.05) and, although without statistical significance, a higher nuclear expression of this protein was observed in AMEs when compared to CDs. Regarding the cytoplasmic expression of XPF, a greater expression was observed in the SOKCs in relation to the DCs (p = 0.04). No statistically significant difference was found between the nuclear expressions of APE-1, XRCC-1 and XPF between NSOKCs and SOKCs (p > 0.05). In addition, all the odontogenic lesions studied revealed a statistically significant expression of APE-1 (nuclear), XRCC-1 (nuclear) and XPF (nuclear and cytoplasmic) when compared to DFs (p < 0.05). For all lesions, Spearman's correlation test showed a positive correlation between nuclear expression of APE-1 and XRCC-1 or XPF at the nuclear level (p < 0.05). The results of this study suggest a potential involvement of APE-1, XRCC-1 and XPF proteins in the pathogenesis of benign epithelial odontogenic lesions. The role played by these proteins may be more important in odontogenic lesions with more aggressive biological behavior (AU).

Correlations between Ape1/Ref-1, ICAM-1 and IL-17A Levels in Serum and Radiation Pneumonitis for Local Advanced Non-small Cell Lung Cancer Patients / 中国肺癌杂志

BACKGROUND@#The main manifestations of radiation pneumonitis are injury of alveolar epithelial and endothelial cells, abnormal expression of cytokines, abnormal proliferation of fibroblasts and synthesis of fibrous matrix. The occurrence of radiation pneumonitis is associated with multiplecytokine level abnormality. These cytokines can also be used as bio-markers to predict the occurrence of radiation pneumonitis. This study was to evaluate the correlation between the change of apurinic/apyrimidinic endonuclease 1/redox factor-1 (Ape1/Ref-1), intercellular adhesion molecules 1 (ICAM-1) and interleukin-17A (IL-17A) before and after radiotherapy and radiation pneumonitis for local advanced non-small cell lung cancer (NSCLC) patients with concurrent chemoradiotherapy.@*METHODS@#NSCLC patients (68 cases) were treated with concurrent radiotherapy and chemotherapy, every patient's normal tissue were controlled with a same radation dose. 68 local advanced NSCLC patients with concurrent chemoradiotherapy were detected the levels of Ape1/Ref-1, ICAM-1 and IL-17A in serum by ELISA before radiotherapy and in the 14th week after radiotherapy. Acute and advanced radiation pulmonary injury was graded according to Radiation Therapy Oncology Group/European Organization For Research and Treatment (RTOG/EORTC) diagnostic and grading criteria. Grade 2 or more radiation pneumonitis was taken as the main end point.@*RESULTS@#Eighteen cases out of 68 developed radiation pneumonitis, 50 of 68 cases have no radiation pneumonia development. There was no significant change of Ape1/Ref-1 levels before and after radiotherapy in radiation pneumonitis group (P>0.05). There was no significant change of Ape1/Ref-1 concentration in serum after radiotherapy between radiation pneumonitis group and non-radiation pneumonitis group (P>0.05). Compared with before radiotherapy, upregulation degree of ICAM-1 levels in radiation pneumonitis group was significantly higher than that in non- radiation pneumonitis group (P<0.05). There was no significant change of IL-17A concentration before and after radiotherapy in radiation pneumonitis group, but after radiotherapy IL-17A concentration in serum were remarkably higher than that in non-radiation pneumonitis group (P<0.05). Correlation analysis found that the change of ICAM-1 before and after radiotherapy has no obvious correlation with the incidence of radiation pneumonitis, and IL-17A change has obvious correlation with the incidence of radiation pneumonitis.@*CONCLUSIONS@#On the basis of strictly controlling radiation dose on normal tissue, IL-17A in serum could be the predictive factors of radiation pneumonitis for local advanced NSCLC patients with concurrent chemoradiotherapy.

Identification of New Potential APE1 Inhibitors by Pharmacophore Modeling and Molecular Docking

Apurinic/apyrimidinic endonuclease 1 (APE1) is an enzyme responsible for the initial step in the base excision repair pathway and is known to be a potential drug target for treating cancers, because its expression is associated with resistance to DNA-damaging anticancer agents. Although several inhibitors already have been identified, the identification of novel kinds of potential inhibitors of APE1 could provide a seed for the development of improved anticancer drugs. For this purpose, we first classified known inhibitors of APE1. According to the classification, we constructed two distinct pharmacophore models. We screened more than 3 million lead-like compounds using the pharmacophores. Hits that fulfilled the features of the pharmacophore models were identified. In addition to the pharmacophore screen, we carried out molecular docking to prioritize hits. Based on these processes, we ultimately identified 1,338 potential inhibitors of APE1 with predicted binding affinities to the enzyme.

Accelerated processing of solitary and clustered abasic site DNA damage lesions by APE1 in the presence of aqueous extract of Ganoderma lucidum.

The stimulatory effect of the aqueous extract of G. lucidum, a basidiomycetes class fungus in the APE1-enzyme-mediated processing of solitary and bistranded clustered abasic sites DNA damages is presented. Abasic sites are considered the most common type of DNA damage lesions. Our study shows enhanced activity of APE1 in the processing of abasic sites in the presence of the polysaccharides fraction of G. lucidum. Remarkable increase in the amount of single-strand breaks (SSBs) and double-strand breaks (DSBs) from solitary and bistranded clustered abasic sites respectively with APE1 in the presence of the extract was found. This trend is maintained when abasic sites in DNA oligomers are exposed to fibroblast cell extracts in the presence of the extract. While DNA conformational alteration is negligible, APE1 enzyme shows characteristic changes in the alpha helix and beta strand ratio after incubation with G. lucidum extract. The enhanced reactivity of APE1 at the molecular level in the presence of G. lucidium is attributed to this effect. This study potentially amplifies the scope of the use of G. lucidum, which was earlier shown to have only reactive oxygen species (ROS) scavenging properties with regards to DNA damage inhibition.

Altered Secretory Activity of APE1/Ref-1 D148E Variants Identified in Human Patients With Bladder Cancer / 대한배뇨장애요실금학회지

PURPOSE: Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multifunctional protein involved in DNA repair and redox modulation. Recently, serum and urinary APE1/Ref-1 levels were reported to be increased in patients with bladder cancer. Genetic variations of APE/Ref-1 are associated with the risk of cancer. However, the effect of APE1/Ref-1 variants on its secretory activity is yet unknown. METHODS: APE1/Ref-1 variants were evaluated by DNA sequencing analysis of reverse transcription polymerase chain reaction products in coding DNA sequences (CDS) of APE1/Ref-1 in bladder tissue samples from patients with bladder cancer (n=10). Secretory activity of APE1/Ref-1 variants was evaluated with immunoblot and enzyme-linked immunosorbent assay of the culture medium supernatants. RESULTS: Four different substitution mutants (D148E, I64V/D148E, W67R/D148E, and E86G/D148E) of APE1/Ref-1 were identified in bladder cancer specimens. However, deletion mutants of APE1/Ref-1 CDS were not found. The secretory activity of the APE1/Ref-1 variants (D148E, I64V/D148E, and E86G/D148E) was increased compared to that of wild type APE1/Ref-1. Furthermore, the secretory activity in basal or hyperacetylated conditions was much higher than that in APE1/Ref-1 D148E-transfected HEK293 cells. CONCLUSIONS: Taken together, our data suggest that the increased secretory activity of D148E might contribute to increased serum levels of APE1/Ref-1 in patients with bladder cancer.

Gemcitabine-resistant Human Pancreatic Cancer Cell Line Overexpresses APE1/Ref-1 / 胃肠病学

Background:Gemcitabine is the main drug for chemotherapy of advanced pancreatic cancer,however,the prognosis of pancreatic cancer patients has not been changed obviously because of the high innate and acquired resistance of cancer cells to gemcitabine. Aims:To investigate the correlation of DNA repair and expression of human APE1 / Ref-1(apurinic/apyrimidinic endonuclease 1 / redox factor-1),the key enzyme in base excision repair pathway,with the resistance of pancreatic cancer to gemcitabine. Methods:A gemcitabine-resistant human pancreatic cancer cell line SW1990-0. 5 with a resistance index of 9. 32 and its parental cell line SW1990 were treated with gemcitabine. DNA injury was assessed by comet assay. Expressions of APE1 / Ref-1 mRNA and protein were determined by real-time PCR and Western blotting, respectively. Results:In comet assay,after treated with gemcitabine for 24 hours,OTM value of SW1990-0. 5 and SW1990 cells were 0. 32 ± 0. 13 and 26. 96 ± 6. 83,respectively. Expression level of APE1 / Ref-1 mRNA in SW1990-0. 5 cells was 2. 48 ± 0. 49;and expression levels of APE1 / Ref-1 protein in SW1990-0. 5 and SW1990 cells were 1. 57 ± 0. 08 and 0. 84 ± 0. 06,respectively. Statistically significant differences were existed in all these parameters between SW1990-0. 5 and SW1990 cells(P all < 0. 05). Conclusions:DNA repair might be correlated with the resistance of pancreatic cancer to gemcitabine,and up-regulation of APE1 / Ref-1 might contribute to this resistance by its function on DNA repair.

APE1/Ref-1 as an emerging therapeutic target for various human diseases: phytochemical modulation of its functions

Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional enzyme involved in the base excision repair (BER) pathway, which repairs oxidative base damage caused by endogenous and exogenous agents. APE1 acts as a reductive activator of many transcription factors (TFs) and has also been named redox effector factor 1, Ref-1. For example, APE1 activates activator protein-1, nuclear factor kappa B, hypoxia-inducible factor 1alpha, paired box gene 8, signal transducer activator of transcription 3 and p53, which are involved in apoptosis, inflammation, angiogenesis and survival pathways. APE1/Ref-1 maintains cellular homeostasis (redox) via the activation of TFs that regulate various physiological processes and that crosstalk with redox balancing agents (for example, thioredoxin, catalase and superoxide dismutase) by controlling levels of reactive oxygen and nitrogen species. The efficiency of APE1/Ref-1's function(s) depends on pairwise interaction with participant protein(s), the functions regulated by APE1/Ref-1 include the BER pathway, TFs, energy metabolism, cytoskeletal elements and stress-dependent responses. Thus, APE1/Ref-1 acts as a 'hub-protein' that controls pathways that are important for cell survival. In this review, we will discuss APE1/Ref-1's versatile nature in various human etiologies, including neurodegeneration, cancer, cardiovascular and other diseases that have been linked with alterations in the expression, subcellular localization and activities of APE/Ref-1. APE1/Ref-1 can be targeted for therapeutic intervention using natural plant products that modulate the expression and functions of APE1/Ref-1. In addition, studies focusing on translational applications based on APE1/Ref-1-mediated therapeutic interventions are discussed.

Expression of DNA Repairing Enzymes in the Cerebral Tissue of the Rat Fetus After Hypoxic Injury / 체질인류학회지

Hypoxia is one of the major causes of neonatal mortality. Hypoxia-induced tissue injuries are resulted from complex mechanisms such as DNA damage and apoptosis. In this study, we aimed to elucidate the changes in the expression of DNA repairing enzymes such as 8-hydroxyguanine glycosylase 1 (OGG1) and apurinic/apyrimidinic endonuclease 1 (APE1) and brain derived neurotrophic factor (BDNF) in the fetal cerebral tissue after intrauterine hypoxic injury. For this study, pregnant Sprague-Dawley rats were exposed to hypoxic gas (10% O2, 5% CO2, 85% N2) for 2 or 4 hours at postconception day 14.5 and 15.5. After 24 hours, the animals were anesthetized with ethyl ether and fetuses were obtained by laparatomy. Hematoxylin-eosin stain, immunohistochemical stain, and western blot were employed for analysis. The caspase-3 immunolabeled cells were significantly increased within the cerebral cortex after hypoxic injury. The expressions of OGG1, APE1, and BDNF were also increased in the cerebral tissue after hypoxic injury at post-conception day 14.5, in a dose-dependent manner. However, the expression of BDNF was significantly decreased in the cortical tissue exposed to hypoxic injury at postconception day 15.5. These results demonstrate that fetal hypoxic injury induces apoptosis of the nerve cells and promotes the expressions of the DNA repairing enzymes and neurotrophic factors. In addition, these results suggest that protection mechanisms against hypoxic injury alter along the progression of the fetal development.

Ape1/Ref-1 Stimulates GDNF/GFR alpha1-mediated Downstream Signaling and Neuroblastoma Proliferation

We previously reported that glial cell line-derived neurotropic factor (GDNF) receptor alpha1 (GFR alpha1) is a direct target of apurinic/apyrimidinic endonuclease 1 (Ape1/Ref-1). In the present study, we further analyzed the physiological roles of Ape1/Ref-1-induced GFRalpha1 expression in Neuro2a mouse neuroblastoma cells. Ape1/Ref-1 expression caused the clustering of GFR alpha1 immunoreactivity in lipid rafts in response to GDNF. We also found that Ret, a downstream target of GFRalpha1, was functionally activated by GDNF in Ape1/Ref-1-expressing cells. Moreover, GDNF promoted the proliferation of Ape1/Ref-1-expressing Neuro2a cells. Furthermore, GFR alpha1-specific RNA experiments demonstrated that the downregulation of GFR alpha1 by siRNA in Ape1/Ref-1-expressing cells impaired the ability of GDNF to phosphorylate Akt and PLC gamma-1 and to stimulate cellular proliferation. These results show an association between Ape1/Ref-1 and GDNF/GFR alpha signaling, and suggest a potential molecular mechanism for the involvement of Ape1/Ref-1 in neuronal proliferation.

In vitro study of the treatment of human osteosarcoma by pSilence APE1 combined with neutron-ray / 解放军医学杂志

Objective Apuinic/apyrimidic endonuclease/redox effector factor-1(APE1/Ref-1,abbreviated as APE1) is a major member of the base excision repair(BER) pathway involved in oxidative DNA damage repair.To knock down APE1 gene expression in HOS cells with pSilence APE1,and explore its effect in combination with 252Cf neutron ray radiotherapy.Methods The constructed APE1 siRNA expression vector pSilence APE1 was transfected into HOS cells by SuperFect Transfection liposome,and it was used to knock down the expression of APE1.The HOS cells and transfected HOS cells were respectively irradiated by 252Cf neutron ray,then the cell survival(D0),DNA single strand breaks(SSB) and cell apoptosis were determined by clone formation assay,alkaline comet assay and flow cytometer.Results The cell-survival curve was plotted by clone formation assay,the D0 value was 2.80 vs.1.89 and Dq value was 2.66 vs.2.00 for the control and transfected HOS cells,respectively,after being irradiated by 252Cf neutron ray.The tail moments at 2,5 and 10 Gy were 6.664?0.648 vs.7.997?0.542,20.322?1.433 vs.25.238?1.185 and 33.909?1.245 vs.39.191?1.052,respectively,for the control and transfected HOS cells,and the cell apoptosis rate at 2,5 and 10 Gy was 4.00 vs.5.68,5.91 vs.7.55 and 9.63 vs.13.51,respectively,for the control and transfected HOS cells.All these findings showed significant difference between the two groups(P

pSilence APE1 inhibits migration of endothelial cell induced by osteosarcoma cell / 第三军医大学学报

Objective To determine the inhibitory effect of APE1 siRNA expression vector pSilence APE1, and the possible synergetic role of pSilence APE1 and endostatin on endothelial cell migration induced by osteosarcoma cell 9901 and HOS . Methods The osteosarcoma cells and endothelial cells were co-cultured with transwell model, and the cell number through the inner membrane was counted to evaluate the inhibitory effect of endothelial cell migration by pSilence APE1 and its combination with endostatin. Results Both low dose (350 ng/ml) and high dose (700 ng/ml) of endostatin showed significant inhibition to endothelial cell migration induced by osteosarcoma cell, while the high dose showed much stronger inhibition than the low dose (P

The altered gene profile of human osteosarcoma cell after knock-down of double functional gene apurinic/apyrimidinic endonuclease / 第三军医大学学报

Objective To explore the molecular mechanism of inhibited malignant phenotype by knock-down of apurinic/apyrimidinic endonuclease(APE1) in human osteosarcoma cell HOS,as well as the possible interacting molecules among APE1.Methods Knock-down of APE1 by synthesized APE1 siRNA in HOS cell was identified first by Western blotting and AP endonuclease assay,then the gene profile was determined with GEArray~(TM) series Human CancerPathwayFinder gene array.Results The specific knock-down of APE1 was found in HOS cell transfected with APE1 siRNA,and its inhibited rate was 91.5%.Six biological pathways of the gene array were involved in HOS cell after knock-down of APE1,but the cell cycle pathway was less influenced.Forty-two out of 96 genes were altered(43.8%),in which only CDK4,FGFR2,KAI1 and NCAM were increased,38 others were decreased.Conclusion The knock-down of APE1 was detected to be involved in all the pathways including cell cycle and DNA repair,apoptosis,signal transduction,adhesion,angiogenesis,invasion and metastasis.These findings are significant to further elucidate APE1 role in tumor genesis and to provide experimental evidence for gene therapy targeting APE1 gene in the future.