The anti‐tumour compound, RH1, causes mitochondria‐mediated apoptosis by activating c‐Jun N‐terminal kinase

Abstract

BACKGROUND AND PURPOSE2,5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone (RH1) is a bioreductive agent that is activated by the two-electron reductase NAD(P)H quinone oxidoreductase 1 (NQO1). Although the cytotoxic efficacy of RH1 against tumours has been studied extensively, the molecular mechanisms underlying this anti-cancer activity have not yet been fully elucidated. EXPERIMENTAL APPROACH2,5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone-induced apoptosis and related signalling pathways in NQO1-negative and NQO1-overexpressing cells were evaluated. The role of p53 in RH1-induced cell death was investigated using parental and p53-deficient RKO human colorectal cancer cells by assaying clonogenic cell survival. Specific inhibitors and siRNAs targeting factors involved in RH1-induced apoptosis were used to clarify the roles played by such factors in RH1-activated apoptotic signalling pathways. KEY RESULTS2,5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone induced apoptosis and clonogenic death, dependent on NQO1 and p53. Treatment of NQO1-overexpressing cells with RH1 caused rapid disruption of mitochondrial membrane potential, nuclear translocation of apoptosis-inducing factor (AIF) and endonuclease G (Endo G) from mitochondria, and subsequent caspase-independent apoptotic cell death. siRNA targeting AIF and Endo G effectively attenuated RH1-induced apoptotic cell death. Moreover, RH1 induced cleavage of Bax, which targets mitochondria. RH1 significantly activated the c-Jun N-terminal kinase (JNK) pathway, and inhibition of this pathway suppressed RH1-induced mitochondria-mediated apoptosis. RH1-induced generation and mitochondrial translocation of cleaved Bax were blocked by the JNK inhibitor, SP600125. Inhibition of JNK with SP600125 attenuated the mitochondrial translocation of JNK. CONCLUSIONS AND IMPLICATIONS2,5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone activated JNK, resulting in mitochondria-mediated apoptotic cell death that was NQO1-dependent. AbbreviationsAIF, apoptosis-inducing factor; DiOC6(3), 3

Study of the cytotoxic effects of 2,5-diaziridinyl-3,6-dimethyl-1,4-benzoquinone (MeDZQ) in mouse hepatoma cells

“…There are studies reporting that quinones induce apoptotic cell death (Sun and Ross, 1996[29]; Fourie et al, 2002[11]; Park et al, 2011[21]). Our results confirmed this fact showing that MeDZQ at LC 50 induced apoptosis: AO/EB staining demonstrated 17 % of nonviable apoptotic and 15 % viable apoptotic cells (Figure 3A(Fig.…”

“…Two of them, JNK and p38, are known as SAPKs. There is evidence that following quinone exposure, some SAPKs take part in apoptosis induction (Park et al, 2011[21]). …”

“…1) oxidative stress-type cytotoxicity arising from the ability of quinones to form free radicals, which may further undergo redox cycling in aerobic conditions (Cassagnes et al, 2015[9]) thus forming reactive oxygen species (ROS) which provoke quinone-induced apoptotic (Ollinger and Kagedal, 2002[20]; Park et al, 2011[21]) and necrotic (Nemeikaite-Ceniene et al, 2005[18]) cell death; …”

“…Previous studies have shown that the reduction of aziridinyl-substituted quinones can regulate the activation of mitogen-activated protein kinases (MAPK) (Seanor et al, 2003[24]; Park et al, 2011[21]). In mammals, there are three main subfamilies of MAPKs: extracellular signal-regulated kinases (ERKs), c-Jun N-terminal kinases (JNKs) and p38 isoforms (p38-MAPKs) (Wada and Penninger, 2004[30]; Huang et al, 2010[12]).…”

The Polymerization Agent, 2-Methyl-4′-(methylthio)-2-morpholinopropiophenone Induces Caspases-3/7 in Human Blood Mononuclear Cells <i>in Vitro</i>

“…[30][31][32] In the caspase-independent pathway, nuclear factor-kappa B (NF-κB), p53, p73 and orphan nuclear receptor Nur77 are reportedly involved in apoptosis. [33][34][35][36] One limitation of this study is the fact that it was conducted in vitro. Moreover, in a clinical setting, MTMP that is present in an infusion bag slowly enters the body in small amounts over an extended period of time.…”