2-(Naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone induces apoptosis via ROS-mediated MAPK, AKT, and STAT3 signaling pathways in HepG2 human hepatocellular carcinoma cells.

1,4-naphthoquinone and its derivatives have attracted widespread attention due to their multiple biological activities, such as induction of cancer cell apoptosis; however, most of these compounds have high cytotoxicity. In this study, in order to reduce their toxicity and increase their potential anti-tumor effects, we synthesized a novel 1,4-naphthoquinone derivative named 2-(naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone (NTDMNQ), and investigated its apoptotic effects and underlying mechanism. Our results showed that NTDMNQ inhibited the viability of HepG2, Hep3B, and Huh7 human hepatocellular carcinoma (HCC) cells. It also increased the accumulation of cells in the G0/G1 phase of the cell cycle by increasing the expression levels of p-p53, p21 and p27, while decreasing the levels of Cyclin D1, Cyclin E, Cyclin-dependent kinase 2 (CDK2), CDK4, and CDK6. Inhibition of reactive oxygen species (ROS) by the ROS scavenger N-acetyl-L-cysteine (NAC) decreased apoptosis in NTDMNQ-treated cells. Western blot analysis showed that NTDMNQ increased the phosphorylation of p38 and c-Jun N-terminal kinase (JNK), and decreased the phosphorylation of extracellular signal-regulated kinase (ERK), AKT, and signal transducer and activator of transcription-3 (STAT3); these effects were blocked by NAC. Both the JNK inhibitor (SP600125) and p38 inhibitor (SB203580) reversed the phosphorylation of STAT3, and the ERK inhibitor (FR180204) and AKT inhibitor (LY294002) reduced the expression of STAT3. Taken together, these findings suggest that NTDMNQ induces apoptosis via ROS-mediated MAPK, AKT and STAT3 signaling pathways in HepG2 cells, and may be a potent anticancer agent.

The compound 2-benzylthio-5,8-dimethoxynaphthalene-1,4-dione leads to apoptotic cell death by increasing the cellular reactive oxygen species levels in Ras-mutated liver cancer cells.

The aim of the present study was to verify the pro-apoptotic anticancer potential of several 5,8-dimethoxy-1,4-phthoquinone (DMNQ) derivatives in Ras-mediated tumorigenesis. MTT assays were used to detect cellular viability and flow cytometry was performed to assess intracellular reactive oxygen species (ROS) levels and apoptosis. The expression levels of proteins were detected via western blotting. Among the 12 newly synthesized DMNQ derivatives, 2-benzylthio-5,8-dimethoxynaphthalene-1,4-dione (BZNQ; component #1) significantly reduced cell viability both in mouse NIH3T3 embryonic fibroblasts cells (NC) and H-RasG12V transfected mouse NIH3T3 embryonic fibroblasts cells (NR). Moreover, BZNQ resulted in increased cytotoxic sensitivity in Ras-mutant transfected cells. Furthermore, the reactive oxygen species (ROS) levels in H-RasG12V transfected HepG2 liver cancer cells (HR) were significantly higher compared with the levels in HepG2 liver cancer cells (HC) following BZNQ treatment, which further resulted in increased cellular apoptosis. Eliminating cellular ROS using an ROS scavenger N-acetyl-L-cysteine markedly reversed BZNQ-induced cellular ROS accumulation and cell apoptosis in HC and HR cells. Western blotting results revealed that BZNQ significantly downregulated H-Ras protein expression and inhibited the Ras-mediated downstream signaling pathways such as protein kinase B, extracellular signal-related kinase and glycogen synthase kinase phosphorylation and ß-catenin protein expression. These results indicated that the novel DMNQ derivative BZNQ may be a therapeutic drug for Ras-mediated liver tumorigenesis. The results of the current study suggest that BZNQ exerts its effect by downregulating H-Ras protein expression and Ras-mediated signaling pathways.

2-(6-Hydroxyhexylthio)-5,8-dimethoxy-1,4-naphthoquinone Induces Apoptosis through ROS-Mediated MAPK, STAT3, and NF-κB Signalling Pathways in Lung Cancer A549 Cells.

Two novel compounds, 2-(2-hydroxyethylthio)-5,8-dimethoxy-1,4-naphthoquinone (HEDMNQ) and 2-(6-hydroxyhexylthio)-5,8-dimethoxy-1,4-naphthoquinone (HHDMNQ), were synthesized to investigate the kill effects and mechanism of 1,4-naphthoquinone derivatives in lung cancer cells. The results of the CCK-8 assay showed that HEDMNQ and HHDMNQ had significant cytotoxic effects on A549, NCI-H23, and NCI-H460 NSCLC cells. Flow cytometry and western blot results indicated that HHDMNQ induced A549 cell cycle arrest at the G2/M phase by decreasing the expression levels of cyclin-dependent kinase 1/2 and cyclin B1. Fluorescence microscopy and flow cytometry results indicated that HHDMNQ could induce A549 cell apoptosis, and western blot analysis showed that HHDMNQ induced apoptosis through regulating the mitochondria pathway, as well as the MAPK, STAT3, and NF-κB signalling pathways. Flow cytometry results showed that intracellular reactive oxygen species (ROS) levels were increased after HHDMNQ treatment, and western blot showed that ROS could modulate the intrinsic pathway and MAPK, STAT3, and NF-κB signalling pathways. These effects were blocked by the ROS inhibitor N-acetyl-L-cysteine in A549 cells. Our findings suggest that compared with HEDMNQ, HHDMNQ had the stronger ability to inhibit the cell viability of lung cancer cells and induce apoptosis by regulating the ROS-mediated intrinsic pathway and MAPK/STAT3/NF-κB signalling pathways. Thus, HHDMNQ might be a potential antitumour compound for treating lung cancer.

Peroxiredoxin I deficiency increases pancreatic ß­cell apoptosis after streptozotocin stimulation via the AKT/GSK3ß signaling pathway.

Apoptosis of pancreatic ß­cells is involved in the pathogenesis of type I and II diabetes. Peroxiredoxin I (Prx I) serves an important role in regulating cellular apoptosis; however, the role of Prx I in pancreatic ß­cell apoptosis is not completely understood. In the present study, the role of peroxiredoxin 1 (Prx I) during streptozotocin (STZ)­induced apoptosis of pancreatic ß­cells was investigated. The expression level of Prx I was decreased by STZ treatment in a time­dependent manner, and apoptosis of Prx I knockdown MIN6 cells was increased by STZ stimulation, compared with untransduced MIN6 cells. Furthermore, an intraperitoneal injection of STZ increased pancreatic islet damage in Prx I knockout mice, compared with wild­type and Prx II knockout mice. AKT and glycogen synthase kinase (GSK)­3ß phosphorylation significantly decreased following Prx I knockdown in MIN6 cells. However, phosphorylated ß­catenin and p65 levels significantly increased after STZ stimulation, compared with untransduced cells. The results of the present study indicate that deletion of Prx I mediated STZ­induced pancreatic ß­cell death in vivo and in vitro by regulating the AKT/GSK­3ß/ß­catenin signaling pathway, as well as NF­κB signaling. These findings provide a theoretical basis for treatment of pancreatic damage.

Picrasma quassioides Extract Elevates the Cervical Cancer Cell Apoptosis Through ROS-Mitochondrial Axis Activated p38 MAPK Signaling Pathway.

BACKGROUND/AIM: Picrasma quassioides (P. quassioides) is used in traditional Asian medicine widely for the treatment of anemopyretic cold, eczema, nausea, loss of appetite, diabetes mellitus, hypertension etc. In this study we aimed to understand the effect of P. quassioides ethanol extract on SiHa cervical cancer cell apoptosis. MATERIALS AND METHODS: The P. quassioides extract-induced apoptosis was analyzed using the MTT assay, fluorescence microscopy, flow cytometry and western blotting. RESULTS: P. quassioides extract induced cellular apoptosis by increasing the accumulation of cellular and mitochondrial reactive oxygen species (ROS) levels and inhibiting ATP synthesis. Pretreatment with N-Acetylcysteine (NAC), a classic antioxidant, decreased the intracellular ROS production and inhibited apoptosis. In addition, the P38 MAPK signaling pathway is a key in the apoptosis of SiHa cells induced by the P. quassioides extract. CONCLUSION: The P. quassioides extract exerts its anti-cancer properties on SiHa cells through ROS-mitochondria axis and P38 MAPK signaling. Our data provide a new insight for P. quassioides as a therapeutic strategy for cervical cancer treatment.

Isoorientin induces the apoptosis and cell cycle arrest of A549 human lung cancer cells via the ROS­regulated MAPK, STAT3 and NF­κB signaling pathways.

Isoorientin (ISO) is a naturally occurring C­glycosyl flavone that has various pharmacological properties, such as anti­bacterial and anti­inflammatory effects. However, its underlying molecular mechanisms in human lung cancer cells remain unknown. In the present study, the effects of ISO on the induction of apoptosis and relative molecular mechanisms in A549 human lung cancer cells were investigated. The results of Cell Counting Kit­8 assay (CCK­8) indicated that ISO exerted significant cytotoxic effects on 3 lung cancer cell lines, but had no obvious side­effects on normal cells. Moreover, flow cytometry and western blot analysis revealed that ISO induced mitochondrial­dependent apoptosis by reducing mitochondrial membrane potential. ISO also increased the expression levels of Bax, cleaved­caspase­3 (cle­cas­3) and poly(ADP­ribose) polymerase (PARP; cle­PARP), and decreased the expression levels of Bcl­2 in A549 cells. Furthermore, ISO induced G2/M cell cycle arrest by decreasing the expression levels of cyclin B1 and CDK1/2, and increasing the expression levels of p21 and p27 in A549 cells. As the duration of ISO treatment increased, intracellular reactive oxygen species (ROS) levels in A549 cells also increased. However, pre­treatment of the cells with the ROS scavenger, N­acetylcysteine (NAC), inhibited ISO­induced apoptosis. In addition, ISO increased the expression levels of p­p38, p­JNK and IκB­α; and decreased the expression levels of p­extracellular signal­regulated kinase (ERK), p­signal transducer and activator of transcription (STAT)3, p­nuclear factor (NF)­κB, NF­κB and p­IκB; these effects were induced by mitogen­activated protein kinase (MAPK) inhibitors and blocked by NAC. Taken together, the results of the present study indicate that ISO induces the apoptosis of A549 lung cancer cells via the ROS­mediated MAPK/STAT3/NF­κB signaling pathway, and thus may be a potential drug for use in the treatment of lung cancer.

Peroxiredoxin II Maintains the Mitochondrial Membrane Potential against Alcohol-Induced Apoptosis in HT22 Cells.

Excessive alcohol intake can significantly reduce cognitive function and cause irreversible learning and memory disorders. The brain is particularly vulnerable to alcohol-induced ROS damage; the hippocampus is one of the most sensitive areas of the brain for alcohol neurotoxicity. In the present study, we observed significant increasing of intracellular ROS accumulations in Peroxiredoxin II (Prx II) knockdown HT22 cells, which were induced by alcohol treatments. We also found that the level of ROS in mitochondrial was also increased, resulting in a decrease in the mitochondrial membrane potential. The phosphorylation of GSK3ß (Ser9) and anti-apoptotic protein Bcl2 expression levels were significantly downregulated in Prx II knockdown HT22 cells, which suggests that Prx II knockdown HT22 cells were more susceptible to alcohol-induced apoptosis. Scavenging the alcohol-induced ROS with NAC significantly decreased the intracellular ROS levels, as well as the phosphorylation level of GSK3ß in Prx II knockdown HT22 cells. Moreover, NAC treatment also dramatically restored the mitochondrial membrane potential and the cellular apoptosis in Prx II knockdown HT22 cells. Our findings suggest that Prx II plays a crucial role in alcohol-induced neuronal cell apoptosis by regulating the cellular ROS levels, especially through regulating the ROS-dependent mitochondrial membrane potential. Consequently, Prx II may be a therapeutic target molecule for alcohol-induced neuronal cell death, which is closely related to ROS-dependent mitochondria dysfunction.

Two novel 1,4­naphthoquinone derivatives induce human gastric cancer cell apoptosis and cell cycle arrest by regulating reactive oxygen species­mediated MAPK/Akt/STAT3 signaling pathways.

1,4­Naphthoquinone derivatives have superior anticancer effects, but their use has been severely limited in clinical practice due to adverse side effects. To reduce the side effects and extend the anticancer effects of 1,4­naphthoquinone derivatives, 2­(butane­1­sulfinyl)­1,4­naphthoquinone (BQ) and 2­(octane­1­sulfinyl)­1,4­naphthoquinone (OQ) were synthesized, and their anticancer activities were investigated. The anti­proliferation effects, determined by MTT assays, showed that BQ and OQ significantly inhibited the viability of gastric cancer cells and had no significant cytotoxic effect on normal cell lines. The apoptotic effect was determined by flow cytometry, and the results showed that BQ and OQ induced cell apoptosis by regulating the mitochondrial pathway and cell cycle arrest at the G2/M phase via inhibition of the Akt signaling pathway in AGS cells. Furthermore, BQ and OQ significantly increased the levels of reactive oxygen species (ROS) and this effect was blocked by the ROS scavenger NAC in AGS cells. BQ and OQ induced apoptosis by upregulating the protein expression of p38 and JNK and downregulating the levels of ERK and STAT3. Furthermore, expression levels of these proteins were also blocked after NAC treatment. These results demonstrated that BQ and OQ induced apoptosis and cell cycle arrest at the G2/M phase in AGS cells by stimulating ROS generation, which caused subsequent activation of MAPK, Akt and STAT3 signaling pathways. Thus, BQ and OQ may serve as potential therapeutic agents for the treatment of human gastric cancer.

Peroxiredoxin V Inhibits Emodin-induced Gastric Cancer Cell Apoptosis via the ROS/Bcl2 Pathway.

BACKGROUND/AIM: Peroxiredoxin (Prx) protein family is aberrantly expressed in various cancers including gastric cancer. Among the six family members, Prx V has been known as an antioxidant enzyme which scavenges intracellular reactive oxygen species (ROS) and modulates cellular apoptosis. This study aimed at investigating the role of Prx V in apoptosis of gastric cancer cells. MATERIALS AND METHODS: Stably constructed Prx V knockdown, over-expression and mock AGS cells (a human gastric adenocarcinoma cell line) were used to study the effect of Prx V on emodin-induced apoptosis by western blotting, cell viability, apoptosis and ROS detection assays. RESULTS: Overexpression of Prx V significantly decreased emodin-induced cellular apoptosis and ROS levels compared to Mock and Prx V knockdown AGS cells. Also, overexpression of Prx V down-regulated the expression of pro-apoptotic proteins, Bad and cleaved PARP, and increased the expression of anti-apoptotic protein, Bcl2. CONCLUSION: Prx V suppresses AGS cell apoptosis via scavenging intracellular ROS and modulating apoptosis-related markers.

Peroxiredoxin V Reduces ß-Lapachone-induced Apoptosis of Colon Cancer Cells.

BACKGROUND/AIM: Peroxiredoxin (Prx) V has been known as an antioxidant enzyme which scavenges intracellular reactive oxygen species (ROS). Also, Prx V has been shown to mediate cell apoptosis in various cancers. However, the mechanism of Prx V-induced apoptosis in colon cancer cells remains unknown. Thus, in this study we analyzed the effects of Prx V in ß-lapachone-induced apoptosis in SW480 human colon cancer cells. MATERIALS AND METHODS: ß-lapachone-induced apoptosis was analyzed by the MTT assay, western blotting, fluorescence microscopy, Annexin V staining and flow cytometry. RESULTS: Overexpression of Prx V, significantly decreased ß-lapachone-induced cellular apoptosis and Prx V silencing increased ß-lapachone-induced cellular apoptosis via modulating ROS scavenging activity compared to mock SW480 cells. In addition, to further explore the mechanism of Prx V regulated ß-lapachone-induced SW480 cells apoptosis, the Wnt/ß-catenin signaling was studied. The Wnt/ ß-catenin signaling pathway was found to be induced by ß-lapachone. CONCLUSION: Prx V regulates SW480 cell apoptosis via scavenging ROS cellular levels and mediating the Wnt/ß-catenin signaling pathway, which was induced by ß-lapachone.

2-(4-methoxyphenylthio)-5,8-dimethoxy-1,4-naphthoquinone induces apoptosis via ROS-mediated MAPK and STAT3 signaling pathway in human gastric cancer cells.

The 1,4-naphthoquinones and their derivatives have garnered great interest due to their antitumor pharmacological properties in various cancers; however, their clinical application is limited by side effects. In this study, to reduce side effects and improve therapeutic efficacy, a novel 1,4-naphthoquinone derivative-2-(4-methoxyphenylthio)-5,8-dimethoxy-1,4-naphthoquinone (MPTDMNQ) was synthesized. We investigated the effects and underlying mechanisms of MPTDMNQ on cell viability, apoptosis, and reactive oxygen species (ROS) generation in human gastric cancer cells. Our results showed that MPTDMNQ decreased cell viability in nine human gastric cancer cell lines. MPTDMNQ significantly induced apoptosis accompanied by the accumulation of ROS in GC cells. However, pre-treatment with the ROS scavenger N-acetyl-L-cysteine (NAC) attenuated the MPTDMNQ-induced apoptosis. Moreover, MPTDMNQ decreased the phosphorylation levels of extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3); and increased the phosphorylation levels of c-Jun N-terminal kinase (JNK) and p38 kinase. However, phosphorylation was inhibited by NAC and a mitogen-activated protein kinase (MAPK) inhibitor. These findings showed that MPTDMNQ induced AGS cell apoptosis via ROS-mediated MAPK and STAT3 signaling pathways. Thus, MPTDMNQ may be a promising candidate for treating gastric cancer.

New naphthalene derivatives induce human lung cancer A549 cell apoptosis via ROS-mediated MAPKs, Akt, and STAT3 signaling pathways.

1,4-Naphthoquinone compounds are a class of organic compounds derived from naphthalene. They exert a wide variety of biological effects, but when used as anticancer drugs, have varying levels of side effects. In the present study, in order to reduce toxicity and improve the antitumor activity, we synthesized two novel 1,4-naphthoquinone derivatives, 2-(butane-1-sulfinyl)-1,4-naphthoquinone (BSQ) and 2-(octane-1-sulfinyl)-1,4-naphthoquinone (OSQ). We investigated the antitumor effects of BSQ and OSQ in human lung cancer cells and the underlying molecular mechanisms of these effects, focusing on the relationship between these compounds and reactive oxygen species (ROS) production. MTT assay and trypan blue exclusion assay results showed that BSQ and OSQ had significant cytotoxic effects in human lung cancer cells. Flow cytometry results indicated that the number of apoptotic cells and the intracellular ROS levels significantly increased after treatment with BSQ and OSQ. However, cell apoptosis was inhibited by pretreatment with the ROS scavenger N-acetyl-l-cysteine (NAC). Western blotting results showed that BSQ and OSQ increased the expression levels of p-p38 kinase and p-c-Jun N-terminal kinase (p-JNK), and decreased the expression levels of p-extracellular signal-regulated kinase (p-ERK), p-protein kinase B (p-Akt), and p-signal transducer and activator of transcription-3 (p-STAT3). These phenomena were blocked by mitogen-activated protein kinase (MAPK) inhibitors, Akt inhibitors and NAC. In conclusion, BSQ and OSQ induce human lung cancer A549 cell apoptosis by ROS-mediated MAPKs, Akt, and STAT3 signaling pathways. Therefore, BSQ and OSQ may be therapeutic potential agents for the treatment of human lung cancer.

The design of 1,4-naphthoquinone derivatives and mechanisms underlying apoptosis induction through ROS-dependent MAPK/Akt/STAT3 pathways in human lung cancer cells.

The natural compound 1,4-naphthoquinone has potent anti-tumor activity. However, the clinical application of 1,4-naphthoquinone and its derivatives has been limited by their side effects. In this study, we attempted to reduce the toxicity of 1,4-naphthoquinone by synthesizing two derivatives: 2,3-dihydro-2,3-epoxy-2-propylsulfonyl-5,8-dimethoxy-1,4-naphthoquinone (EPDMNQ) and 2,3-dihydro-2,3-epoxy-2-nonylsulfonyl-5,8-dimethoxy-1,4-naphthoquinone (ENDMNQ). Then we evaluated the cytotoxicity and molecular mechanisms of these compounds in lung cancer cells. EPDMNQ and ENDMNQ significantly inhibited the viabilities of three lung cancer cell lines and induced A549 cell cycle arrest at the G1 phase. In addition, they induced the apoptosis of A549 lung cancer cells by increasing the phosphorylation of p38 and c-Jun N-terminal kinase (p-JNK), and decreasing the phosphorylation of extracellular signal-related kinase (p-ERK), protein kinase B (Akt), and signal transducer and activator of transcription 3 (STAT3). Furthermore, they increased reactive oxygen species (ROS) levels in A549 cells; however, pretreatment with the ROS inhibitor N-acetyl-l-cysteine significantly inhibited EPDMNQ- and ENDMNQ-mediated apoptosis and reversed apoptotic proteins expression. In conclusion, EPDMNQ and ENDMNQ induced G1 phase cell cycle arrest and apoptosis in A549 cells via the ROS-mediated activation of mitogen activated protein kinase (MAPK), Akt and STAT3 signaling pathways.

Cryptotanshinone induces reactive oxygen species­mediated apoptosis in human rheumatoid arthritis fibroblast­like synoviocytes.

The present study investigated the mechanisms of apoptosis induced by cryptotanshinone (CT) in human rheumatoid arthritis fibroblast­like synoviocytes (RA­FLSs). Cell Counting kit­8 assay was performed to determine the cytotoxic effects of CT in human RA­FLSs, including primary RA­FLS, HFLS­RA and MH7A cells, and in HFLS cells derived from normal synovial tissue. Annexin V­FITC/PI staining was used to detect the apoptotic effects of CT in HFLS­RA and MH7A cells. Flow cytometry was performed to detect the apoptotic and reactive oxygen species (ROS) levels induced by CT in HFLS­RA cells. Western blotting was used to assess the expression levels of proteins associated with apoptosis and with the mitogen­activated protein kinase (MAPK), protein kinase B (Akt), and signal transducer and activator of transcription­3 (STAT3) signaling pathways. The results demonstrated that CT treatment significantly suppressed HFLS­RA and MH7A cell growth, whereas no clear inhibitory effect was observed in normal HFLS cells. CT exposure downregulated the expression levels of B­cell lymphoma 2 (Bcl­2), p­Akt, p­extracellular signal­related kinase and p­STAT3, while it upregulated the expression levels of Bcl­2­associated death promoter (Bad), caspase­3, poly (ADP­ribose) polymerase (PARP), p­p38 and p­c­Jun N­terminal kinase. Following ROS scavenging, the CT­induced apoptosis and altered expression levels of Bcl­2, Bad, cleaved caspase­3 and cleaved PARP were restored. Furthermore, the Akt, MAPK and STAT3 signaling pathways were regulated by intracellular ROS. These results suggest that ROS­mediated Akt, MAPK and STAT3 signaling pathways serve important roles in the CT­induced apoptosis of RA­FLSs.

Novel 1,4­naphthoquinone derivatives induce reactive oxygen species­mediated apoptosis in liver cancer cells.

Derivatives of 1,4­naphthoquinone have excellent anti­cancer effects, but their use has been greatly limited due to their serious side effects. To develop compounds with decreased side effects and improved anti­cancer activity, two novel types of 1,4­naphthoquinone derivatives, 2,3­dihydro­2,3­epoxy­2­propylsulfonyl­5,8­dimethoxy­1,4­naphthoquinone (EPDMNQ) and 2,3­dihydro­2,3­epoxy­2­nonylsulfonyl­5,8­dimethoxy­1,4­naphthoquinone (ENDMNQ) were synthesized and their anti­tumor activities were investigated. The effects of EPDMNQ and ENDMNQ on cell viability, apoptosis and accumulation of reactive oxygen species (ROS) in liver cancer cells were determined by MTT cell viability assay and flow cytometry. The expression levels of mitochondrial, mitogen activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3) signaling pathway­associated proteins in Hep3B liver cancer cells were analyzed by western blot analysis. The results demonstrated that EPDMNQ and ENDMNQ inhibited the proliferation of liver cancer Hep3B, HepG2, and Huh7 cell lines but not that of normal liver L­02, normal lung IMR­90 and stomach GES­1 cell lines. The number of apoptotic cells and ROS levels were significantly increased following treatment with EPDMNQ and ENDMNQ, and these effects were blocked by the ROS inhibitor N­acetyl­L­cysteine (NAC) in Hep3B cells. EPDMNQ and ENDMNQ induced apoptosis by upregulating the protein expression of p38 MAPK and c­Jun N­terminal kinase and downregulating extracellular signal­regulated kinase and STAT3; these effects were inhibited by NAC. The results of the present study demonstrated that EPDMNQ and ENDMNQ induced apoptosis through ROS­modulated MAPK and STAT3 signaling pathways in Hep3B cells. Therefore, these novel 1,4­naphthoquinone derivatives may be useful as anticancer agents for the treatment of liver cancer.

The compound 2-(naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone induces apoptosis via reactive oxygen species-regulated mitogen-activated protein kinase, protein kinase B, and signal transducer and activator of transcription 3 signaling in human gastric cancer cells.

Hit, Lead & Candidate Discovery It is reported that 1,4-naphthoquinones and their derivatives have potent antitumor activity in various cancers, although their clinical application is limited by observed side effects. To improve the therapeutic efficacy of naphthoquinones in the treatment of cancer and to reduce side effects, we synthesized a novel naphthoquinone derivative, 2-(naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone (NTDMNQ). In this study, we explored the effects of NTDMNQ on apoptosis in gastric cancer cells with a focus on reactive oxygen species (ROS) production. Our results demonstrated that NTDMNQ exhibited the cytotoxic effects on gastric cancer cells in a dose-dependent manner. NTDMNQ significantly induced mitochondrial-related apoptosis in AGS cells and increased the accumulation of ROS. However, pre-treatment with N-acetyl-L-cysteine (NAC), an ROS scavenger, inhibited the NTDMNQ-induced apoptosis. In addition, NTDMNQ increased the phosphorylation of p38 kinase and c-Jun N-terminal kinase (JNK) and decreased the phosphorylation of extracellular signal-regulated kinase (ERK), protein kinase B (Akt), and Signal Transducer and Activator of Transcription 3 (STAT3); these effects were blocked by mitogen-activated protein kinase (MAPK) inhibitor and NAC. Taken together, the present findings indicate that NTDMNQ-induced gastric cancer cell apoptosis via ROS-mediated regulation of the MAPK, Akt, and STAT3 signaling pathways. Therefore, NTDMNQ may be a potential treatment for gastric cancer as well as other tumor types.

Peroxiredoxin I deficiency increases LPS­induced lethal shock in mice.

Peroxiredoxin I (Prx I) plays a role in regulating macrophage proinflammatory cytokine production and gene expression and participates in immune regulation. However, the possible protective role of Prx I in endotoxin­induced lethal shock is poorly understood. In the present study, western blot analysis, ELISA and haematoxylin and eosin staining were performed to examine the protein expression of cytoines and analyses the levels of cytokines in the serum and tissue to evaluate the tissue damage. The present study revealed that lipopolysaccharide (LPS)­induced lethality in Prx I­/­ mice was is accelerated via the observed decreased serum IL­10 levels. Results also demonstrated rapid immune cell infiltration and oxidative stress in the Prx I­/­mice liver after LPS injections. These phenomena increased liver apoptosis through increasing cleaved caspase­3 protein expression in Prx I­/­ mice after LPS injections, resulting in high lethality after LPS challenges. These findings provide a new insight for understanding the function of Prx I against endotoxin­induced injury.

Quinalizarin Induces Apoptosis through Reactive Oxygen Species (ROS)-Mediated Mitogen-Activated Protein Kinase (MAPK) and Signal Transducer and Activator of Transcription 3 (STAT3) Signaling Pathways in Colorectal Cancer Cells.

BACKGROUND Quinalizarin (1,2,5,8-tetrahydroxyanthraquinone) exhibits potentially useful anticancer effects by inducing apoptosis in several types of cancer, but its underlying mechanism of action remains unknown. The present study examined the effects of quinalizarin on the induction of cell cycle arrest, apoptosis, the generation of reactive oxygen species (ROS), other underlying mechanisms, and its role in modifying colorectal cancer cell lines. MATERIAL AND METHODS The MTT assay was used to evaluate the viability of SW480 and HCT-116 cells that had been treated with quinalizarin and 5-fluorouracil (5-FU). Cell cycle arrest and apoptosis were analyzed by flow cytometry. Western blotting was used to investigate the mitochondrial pathway; Akt, MAPK, and STAT3 signaling pathways were also investigated. The relationship between ROS generation and apoptosis was analyzed by flow cytometry and western blotting. RESULTS The results indicated that quinalizarin significantly inhibits the viability of SW480 and HCT-116 cells in a dose-dependent manner. Quinalizarin induced SW480 cell cycle arrest at G2/M by regulating cyclin B1 and CDK1/2. The apoptosis-related protein expression levels of p-p53, Bad, cleaved caspase-3, cleaved PARP and p-JNK were increased in quinalizarin-treated cells, while protein expression levels Bcl-2, p-Akt, p-ERK, and p-STAT3 were decreased. Quinalizarin induced apoptosis in colorectal cancer cells by regulating MAPK and STAT3 signaling pathways via ROS generation. CONCLUSIONS Quinalizarin induces apoptosis via ROS-mediated MAPK/STAT3 signaling pathways.

Knockdown of peroxiredoxin V increases glutamate­induced apoptosis in HT22 hippocampal neuron cells.

High concentrations of glutamate may mediate neuronal cell apoptosis by increasing intracellular reactive oxygen species (ROS) levels. Peroxiredoxin V (Prx V), a member of the Prx family, serves crucial roles in protecting cells from oxidative stress. The present study investigated the regulatory effect of Prx V on glutamate­induced effects on viability and apoptosis in HT22 cells. Western blotting was used for protein expression analysis and Annexin V/PI staining and flow cytometry for determination of apoptosis. The results demonstrated that glutamate may ROS­dependently increase HT22 cell apoptosis and upregulate Prx V protein levels. Furthermore, knockdown of Prx V protein expression with a lentivirus significantly enhanced HT22 cell apoptosis mediated by glutamate, which was reversed by inhibition of ROS with N­acetyl­L­cysteine. Inhibiting the extracellular signal­regulated kinase (ERK) signaling pathway with PD98059, a specific inhibitor for ERK phosphorylation, markedly decreased glutamate­induced HT22 cell apoptosis in Prx V knockdown cells, indicating the potential involvement of ERK signaling in glutamate­induced HT22 cell apoptosis. In addition, an increase in nuclear apoptosis­inducing factor was observed in Prx V knockdown HT22 cells following glutamate treatment, compared with mock cells, whereas no differences in B­cell lymphoma­2 and cleaved­caspase­3 protein expression levels were observed between mock and Prx V knockdown cells. The results of the present study indicated that Prx V may have potential as a therapeutic molecular target for glutamate­induced neuronal cell death and provide novel insight into the role of Prx V in oxidative­stress induced neuronal cell death.

Novel 1,4-naphthoquinone derivatives induce apoptosis via ROS-mediated p38/MAPK, Akt and STAT3 signaling in human hepatoma Hep3B cells.

1,4-Naphthoquinone and its derivatives have shown some efficacy as therapeutic compounds for cancer and inflammation, though their clinical application is limited by their side-effects. To reduce the toxicity of these compounds and optimize their effects, we synthesized two 1,4-naphthoquinone derivatives-2-butylsulfinyl- 1,4-naphthoquinone (BSNQ) and 2-octylsulfinyl-1,4-naphthoquinone (OSNQ)-and investigated their effects and underlying mechanisms in hepatocellular carcinoma cells. BSNQ and OSNQ decreased cell viability and significantly induced apoptosis, accompanied by the accumulation of reactive oxygen species (ROS). However, pretreatment with N-acetyl-l-cysteine, a specific ROS scavenger, blocked apoptosis. Western blot results indicated that BSNQ and OSNQ up-regulated the phosphorylation of p38 and JNK, and down-regulated the phosphorylation of ERK, Akt and STAT3, and that these effects were blocked by N-acetyl-l-cysteine. Furthermore, BSNQ and OSNQ suppressed tumor growth and modulated MAPK and STAT3 signaling in mouse xenografts without detectable effects on body weight or hematological parameters. These results indicate that BSNQ and OSNQ induce apoptosis in human hepatoma Hep3B cells via ROS-mediated p38/MAPK, Akt and STAT3 signaling pathways, suggesting that these 1,4-naphthoquinone derivatives may provide promising new anticancer agents to treat HCC.