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.

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.

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.

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.

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.