Specific Inhibition of the Redox Activity of Ape1/Ref-1 by E3330 Blocks Tnf-Α-Induced Activation of Il-8 Production in Liver Cancer Cell Lines

Abstract

APE1/Ref-1 is a main regulator of cellular response to oxidative stress via DNA-repair function and co-activating activity on the NF-κB transcription factor. APE1 is central in controlling the oxidative stress-based inflammatory processes through modulation of cytokines expression and its overexpression is responsible for the onset of chemoresistance in different tumors including hepatic cancer. We examined the functional role of APE1 overexpression during hepatic cell damage related to fatty acid accumulation and the role of the redox function of APE1 in the inflammatory process. HepG2 cells were stably transfected with functional and non-functional APE1 encoding plasmids and the protective effect of APE1 overexpression toward genotoxic compounds or FAs accumulation, was tested. JHH6 cells were stimulated with TNF-α in the presence or absence of E3330, an APE1 redox inhibitor. IL-8 promoter activity was assessed by a luciferase reporter assay, gene expression by Real-Time PCR and cytokines (IL-6, IL-8, IL-12) levels measured by ELISA. APE1 over-expression did not prevent cytotoxicity induced by lipid accumulation. E3330 treatment prevented the functional activation of NF-κB via the alteration of APE1 subcellular trafficking and reduced IL-6 and IL-8 expression induced by TNF-α and FAs accumulation through blockage of the redox-mediated activation of NF-κB. APE1 overexpression observed in hepatic cancer cells may reflect an adaptive response to cell damage and may be responsible for further cell resistance to chemotherapy and for the onset of inflammatory response. The efficacy of the inhibition of APE1 redox activity in blocking TNF-α and FAs induced inflammatory response opens new perspectives for treatment of inflammatory-based liver diseases.

The APE1 redox inhibitor E3330 reduces collective cell migration of human breast cancer cells and decreases chemoinvasion and colony formation when combined with docetaxel

“…The chemotactic migration involves the horizontal and vertical migration and provides information about the single‐cell motility . Moreover, despite the fact that the conditions of the chemotaxis assay better mimic the in vivo tumour microenvironment, we cannot discard a possible binding of E3330 to the serum proteins contributing to a decrease in the amount of E3330 available to enter in the cells and interact with APE1, consequently decreasing the efficacy of protein redox function inhibition when compared to the wound‐healing assay. In view of this, some of the effects of E3330 herein observed could be even more evident if a lower concentration of serum was used.…”

“…E3330 was found to suppress the inflammatory response of activated macrophages and to prevent the induction of inflammatory cytokines (IL‐8 and IL‐6) expression in hepatic cancer cell lines suggesting that this inhibitor can be used in inflammatory processes associated with tumours and liver pathologies. E3330 also inhibited the differentiation of adult human bone marrow‐derived mesenchymal stem cells (BM‐MSCs) and the growth of endothelial cell precursors and pancreatic cancer‐associated endothelial cells .…”

Placental aging and oxidation damage in a tissue micro-array model: an immunohistochemistry study

“…In this paper, we also focus our attention on the immunohistochemical expression of APE1/ Ref-1 (APE1). This is involved both in the base excision repair (BER) pathway of DNA lesions, acting as the major apurinic/apyrimidinic (AP) endonuclease, and in transcriptional regulation of gene expression, where it functions as a redox co-activator of different transcription factors that could lead to increased interleukin (IL)-6 and IL-8 expression (Cesaratto et al 2013;Thakur et al 2015;Tell et al 2005). IL-6 and IL-8 are two important immune-modulatory cytokines that are part of the senescence-associated secretory phenotype (SASP) (Coppé et al 2008).…”

The Redox Function of APE1 Is Involved in the Differentiation Process of Stem Cells toward a Neuronal Cell Fate

“…E3330 was also found to selectively inhibit growth/migration of human pancreatic cancer cells [8], suggesting that the APE1 redox function could represent a good candidate for inhibition of tumor invasion and metastasis. We recently demonstrated that E3330-treatment inhibits the TNFα-induced IL8 production driven by NF-κB, in hepatic cancer cell lines [9]. However, knowledge on the detailed molecular mechanisms responsible for the C65-mediated APE1 redox function and for the effects of E3330 inhibition on APE1 in vivo are only at its beginning.…”