Novel involvement of miR-522-3p in high-mobility group box 1-induced prostaglandin reductase 1 expression and reduction of phagocytosis
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH
Authors: Kang, Gyeoung-Jin; Lee, Hye-Ja; Byun, Hyun Jung; Kim, Eun Ji; Kim, Hyun Ji; Park, Mi Kyung; Lee, Chang-Hoon
Abstract
Resolution of inflammation is important for physiological homeostasis. Chronic inflammatory diseases may be caused by abnormal resolution of inflammation. However, what causes a failure of inflammatory resolution is unclear. Here we investigated the involvement of high mobility group box 1 (HMGB1) protein in the control of inflammatory resolution as an 'anti -resolution factor'. We first confirmed the increased expression of HMGB1 and prostaglandin reductase 1 (PTGR1) in inflammatory conditions and HMGB1-mediated regulation of the expression of PTGR1. The inhibition of phagocytosis by HMGB1 was abrogated by PTGR1 silencing. PTGR1 was a direct target of miR522-3p and its expression was regulated by miRNA-522-3p inhibitor or mimic. Finally, miR-522-3p had an important role in the regulation of PTGR1 expression by HMGB1. The data indicates that HMGB1-miR522-3p-PTGR1 axis may be involved in the abnormal resolution of inflammation and suggests that this mechanism might be a target for modulation of chronic inflammatory disorder. (C) 2017 Elsevier B.V. All rights reserved.
Chemical and Enzymatic Reductive Activation of Acylfulvene to Isomeric Cytotoxic Reactive Intermediates
CHEMICAL RESEARCH IN TOXICOLOGY
Authors: Pietsch, Kathryn E.; Neels, James F.; Yu, Xiang; Gong, Jiachang; Sturla, Shana J.
Abstract
Acylfulvenes (AFs), a class of semisynthetic analogues of the sesquiterpene natural product illudin S, are cytotoxic toward cancer cells. The minor structural changes between illudin S and AFs translate to an improved therapeutic window in preclinical cell-based assays and xenograft models. AFs are, therefore, unique tools for addressing the chemical and biochemical basis of cytotoxic selectivity. AFs elicit cytotoxic responses by alkylation of biological targets, including DNA. While AFs are capable of direct alkylation, cytosolic reductive bioactivation to an electrophilic intermediate is correlated with enhanced cytotoxicity. Data obtained in this study illustrate chemical aspects of the process of AF activation. By tracking reaction mechanisms with stable isotope-labeled reagents, enzymatic versus chemical activation pathways for AF were compared for reactions involving the NADPH-dependent enzyme prostaglandin reductase 1 (PTGR1) or sodium borohydride, respectively. These two processes resulted in isomeric products that appear to give rise to similar patterns of DNA modification. The chemically activated isomer has been newly isolated and chemically characterized in this study, including an assessment of its relative stereochemistry and stability at varying pH and under bioassay conditions. In mammalian cancer cells, this chemically activated analogue was shown to not rely on further cellular activation to significantly enhance cytotoxic potency, in contrast to the requirements of AF. On the basis of this study, we anticipate that the chemically activated form of AF will serve as a useful chemical probe for evaluating biomolecular interactions independent of enzyme-mediated activation.