COX-2 inhibitor NS-398 suppresses doxorubicin-induced p53 accumulation through inhibition of ROS-mediated Jnk activation

Cyclooxygenase-2 activates the free radical-mediated apoptosis of polymorphonuclear leukocytes in the maneb- and paraquat-intoxicated rats

Overproduction of free radicals and inflammation could lead to maneb (MB)- and paraquat (PQ)-induced toxicity in the polymorphonuclear leukocytes (PMNs). Cyclooxygenase-2 (COX-2), an inducible COX, is imperative in the pesticides-induced pathological alterations. However, its role in MB- and PQ-induced toxicity in the PMNs is not yet clearly deciphered. The current study explored the contribution of COX-2 in MB- and PQ-induced toxicity in the PMNs and the mechanism involved therein. Combined MB and PQ augmented the production of free radicals, lipid peroxides and activity of superoxide dismutase (SOD) in the rat PMNs. While combined MB and PQ elevated the expression of COX-2 protein, activation of nuclear factor-kappa B (NF-κB) and phosphorylation of c-Jun N-terminal kinase (JNK), release of mitochondrial cytochrome c and levels of procaspase-3/9 were attenuated in the PMNs. Celecoxib (CXB), a COX-2 inhibitor, ameliorated the combined MB and PQ-induced modulations in the PMNs. MB and PQ augmented the free radical generation, COX-2 protein expression, NF-κB activation and JNK phosphorylation and reduced the cell viability of cultured rat PMNs and human leukemic HL60. MB and PQ elevated mitochondrial cytochrome c release and poly (ADP-ribose) polymerase cleavage whilst procaspase-3/9 levels were attenuated in the cultured PMNs. MB and PQ also increased the levels of phosphorylated c-jun and caspase-3 activity in the HL60 cells. CXB; SP600125, a JNK-inhibitor and pyrrolidine dithiocarbamate (PDTC), a NF-κB inhibitor, rescued from MB and PQ-induced changes in the PMNs and HL60 cells. However, CXB offered the maximum protection among the three. The results show that COX-2 activates apoptosis in the PMNs following MB and PQ intoxication, which could be linked to NF-κB and JNK signaling.

P53: A Guardian of Immunity Becomes Its Saboteur through Mutation

Awareness of the importance of immunity in controlling cancer development triggered research into the impact of its key oncogenic drivers on the immune response, as well as their value as targets for immunotherapy. At the heart of tumour suppression is p53, which was discovered in the context of viral infection and now emerges as a significant player in normal and cancer immunity. Wild-type p53 (wt p53) plays fundamental roles in cancer immunity and inflammation. Mutations in p53 not only cripple wt p53 immune functions but also sinisterly subvert the immune function through its neomorphic gain-of-functions (GOFs). The prevalence of mutant p53 across different types of human cancers, which are associated with inflammatory and immune dysfunction, further implicates mutant p53 in modulating cancer immunity, thereby promoting tumorigenesis, metastasis and invasion. In this review, we discuss several mutant p53 immune GOFs in the context of the established roles of wt p53 in regulating and responding to tumour-associated inflammation, and regulating innate and adaptive immunity. We discuss the capacity of mutant p53 to alter the tumour milieu to support immune dysfunction, modulate toll-like receptor (TLR) signalling pathways to disrupt innate immunity and subvert cell-mediated immunity in favour of immune privilege and survival. Furthermore, we expose the potential and challenges associated with mutant p53 as a cancer immunotherapy target and underscore existing therapies that may benefit from inquiry into cancer p53 status.

Aspirin ameliorates the long-term adverse effects of doxorubicin through suppression of cellular senescence

A number of childhood cancer survivors develop adverse, late onset side effects of earlier cancer treatments, known as the late effects of cancer therapy. As the number of survivors continues to increase, this growing population is at increased risk for a number of health-related problems. In the present study, we have examined the effect of aspirin on the late effects of chemotherapy by treating juvenile mice with doxorubicin (DOX). This novel mouse model produced various long-term adverse effects, some of which resemble premature aging phenotypes. DOX also resulted in the tissue accumulation of senescent cells and up-regulation of cyclooxygenase-2 (COX2) expression. However, treatment with aspirin following juvenile exposure to DOX improved body weight gain, ameliorated the long-term adverse effects, and reduced the levels of senescence markers. Moreover, aspirin reduced p53 and p21 accumulation in DOX-treated human and mouse fibroblasts. However, the suppressive effect of aspirin on DOX-induced p53 accumulation was significantly decreased in COX2 knockout mouse embryonic fibroblasts. Additionally, treatment of senescent fibroblasts with aspirin or celecoxib, a COX2 specific inhibitor, reduced cell viability and decreased the levels of Bcl-xL protein. Taken together, these studies suggest that aspirin may be able to reduce the late effects of chemotherapy through the suppression of cellular senescence.

Identification of Differentially Expressed Genes and Signaling Pathways in Acute Myocardial Infarction Based on Integrated Bioinformatics Analysis

Background

Acute myocardial infarction (AMI) is a common disease with high morbidity and mortality around the world. The aim of this research was to determine the differentially expressed genes (DEGs), which may serve as potential therapeutic targets or new biomarkers in AMI.

Methods

From the Gene Expression Omnibus (GEO) database, three gene expression profiles (GSE775, GSE19322, and GSE97494) were downloaded. To identify the DEGs, integrated bioinformatics analysis and robust rank aggregation (RRA) method were applied. These DEGs were performed through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses by using Clusterprofiler package. In order to explore the correlation between these DEGs, the interaction network of protein-protein internet (PPI) was constructed using the STRING database. Utilizing the MCODE plug-in of Cytoscape, the module analysis was performed. Utilizing the cytoHubba plug-in, the hub genes were screened out.

Results

57 DEGs in total were identified, including 2 down- and 55 upregulated genes. These DEGs were mainly enriched in cytokine-cytokine receptor interaction, chemokine signaling pathway, TNF signaling pathway, and so on. The module analysis filtered out 18 key genes, including Cxcl5, Arg1, Cxcl1, Spp1, Selp, Ptx3, Tnfaip6, Mmp8, Serpine1, Ptgs2, Il6, Il1r2, Il1b, Ccl3, Ccr1, Hmox1, Cxcl2, and Ccl2. Ccr1 was the most fundamental gene in PPI network. 4 hub genes in total were identified, including Cxcl1, Cxcl2, Cxcl5, and Mmp8.

Conclusion

This study may provide credible molecular biomarkers in terms of screening, diagnosis, and prognosis for AMI. Meanwhile, it also serves as a basis for exploring new therapeutic target for AMI.

Ethanol extracts of Allium sp. regulate cyclooxygenase-2 and E-cadherin expression in gastric cancer MKN74 cell line and enhance doxorubicin toxicity

Background

Gastric cancer (GC) remains one of the leading causes of cancer-related death. Its aetiology is multifactorial, but the major risk factor is a high in salt diet. During gastric carcinogenesis, cadherin-1 (CDH1) down-expression and cyclooxygenase 2 (COX2) overexpression may be observed. The intensity of these alterations contributes to the GC invasion, its metastases and poor prognosis. As the diet plays a significant role in the aetiology of GC, it is reasonable to include the nutritional chemoprevention agents. One of the plant genus demonstrating chemoprotective properties is Allium genus, which includes garlic. The relationship between CDH1 and COX2 in GC cells treated with Allium species extract has never been evaluated.

Methods

In this study, the MKN28 and MKN74 GC cell lines were treated with ethanol extracts of Allium angulosum L., Allium lusitanicum Lam., Allium sativum L. (from Malaysia and Poland), Allium tibeticum Rendle and Allium ursinum L. The cytotoxicity of the extracts and their influence on COX2 and CDH1 mRNA and protein expression were evaluated as well as their influence on doxorubicin's (DOX) efficacy - a drug that has been used in GC treatment.

Results

Among the tested species, ethanol extracts of A. sativum L. (Poland and Malaysia), A. tibeticum Rendle and A. ursinum L. influenced the levels of CDH1 and COX2, but only in the MKN74 cell line. Thus, it is possible that tumours with increased COX2 expression will be more susceptible to garlic treatment. Observed phenomenon was independent of Allium extract's toxicity. In comparison to DOX, tested extracts were more toxic. Moreover, A. sativum revealed synergistic effect with the drug.

Conclusion

In conclusion, the results indicate the potential application of Allium genus to GC chemoprevention and treatment support through CDH restoration and COX2 downregulation. This issue needs further investigations as it might be used in clinics.

MicroRNA-26b relieves inflammatory response and myocardial remodeling of mice with myocardial infarction by suppression of MAPK pathway through binding to PTGS2

BACKGROUND

Myocardial infarction (MI) is a common cardiovascular disease caused by myocardial ischemia. Also, microRNA (miRNA) participates in the pathophysiology of many cardiovascular diseases, which can affect stem cell transplantation in the treatment of MI. In this study, our aim is to explore effect of miR-26b on inflammatory response and myocardial remodeling through the MAPK pathway by targeting PTGS2 in mice with MI.

METHODS

Microarray data analysis was conducted to screen MI-related differentially expressed gens (DEGs). Relationship between miR-26b and PTGS2 was testified. Cardiac function, inflammatory reaction, infarct size, and myocardial fibrosis were observed. The miR-26b expression and mRNA and protein levels of, PTGS2, ERK, JNK and p38 and Bcl-2/Bax were examined. The effect of miR-26b on cell apoptosis was also analyzed.

RESULTS

MiR-26b was predicted to target PTGS2 further to mediate the MAPK pathway, thus affecting MI. MiR-26b negatively targeted PTGS2. MI mice showed decreased cardiac function, as well as increased inflammatory reaction, myocardial injury, area of fibrosis and myocardial cell apoptosis. After injection of miR-26b agomir or NS-398 (PTGS2 inhibitor), inflammatory response of MI mice was attenuated and myocardial remodeling induced by MI was alleviated.

CONCLUSION

These findings indicate that miR-26b inhibits PTGS2 to activate the MAPK pathway, so as to reduce inflammatory response and improve myocardial remodeling in mice with MI.

Activating Transcription Factor 3 as a Novel Regulator of Chemotherapy Response in Breast Cancer

Anthracyclines, such as doxorubicin, are used as first-line chemotherapeutics, usually in combination therapies, for the treatment of advanced breast cancer. While these drugs have been successful therapeutic options, their use is limited due to serious drug related toxicities and acquired tumor resistance. Uncovering the molecular mechanisms that mediate doxorubicin's cytotoxic effect will lead to the identification of novel more efficacious combination therapies and allow for reduced doses of doxorubicin to be administered while maintaining efficacy. In our study, we demonstrate that activating transcription factor (ATF) 3 expression was upregulated by doxorubicin treatment in a representative panel of human breast cancer cell lines MCF7 and MDA-MB-231. We have also shown that doxorubicin treatment can induce ATF3 expression in ex vivo human breast and ovarian tumor samples. The upregulation of ATF3 in the cell lines was regulated by multiple cellular mechanisms including the activation of JNK and ATM signaling pathways. Importantly, loss of ATF3 expression resulted in reduced sensitivity to doxorubicin treatment in mouse embryonic fibroblasts. Through a 1200 FDA-approved compound library screen, we identified a number of agents whose cytotoxicity is dependent on ATF3 expression that also enhanced doxorubicin induced cytotoxicity. For example, the combination of the HDAC inhibitor vorinostat or the nucleoside analogue trifluridine could synergistically enhance doxorubicin cytotoxicity in the MCF7 cell line. Synergy in cell lines with the combination of ATF3 inducers and patients with elevated basal levels of ATF3 shows enhanced response to chemotherapy. Taken together, our results demonstrate a role for ATF3 in mediating doxorubicin cytotoxicity and provide rationale for the combination of ATF3-inducing agents with doxorubicin as a novel therapeutic approach.

Transgenic expression of cyclooxygenase-2 (COX2) causes premature aging phenotypes in mice

Cyclooxygenase (COX) is a key enzyme in the biosynthesis of prostanoids, lipid signaling molecules that regulate various physiological processes. COX2, one of the isoforms of COX, is highly inducible in response to a wide variety of cellular and environmental stresses. Increased COX2 expression is thought to play a role in the pathogenesis of many age-related diseases. COX2 expression is also reported to be increased in the tissues of aged humans and mice, which suggests the involvement of COX2 in the aging process. However, it is not clear whether the increased COX2 expression is causal to or a result of aging. We have now addressed this question by creating an inducible COX2 transgenic mouse model. Here we show that post-natal expression of COX2 led to a panel of aging-related phenotypes. The expression of p16, p53, and phospho-H2AX was increased in the tissues of COX2 transgenic mice. Additionally, adult mouse lung fibroblasts from COX2 transgenic mice exhibited increased expression of the senescence-associated β-galactosidase. Our study reveals that the increased COX2 expression has an impact on the aging process and suggests that modulation of COX2 and its downstream signaling may be an approach for intervention of age-related disorders.

Growth and adherence of Staphylococcus aureus were enhanced through the PGE2 produced by the activated COX-2/PGE2 pathway of infected oral epithelial cells

Staphylococcus aureus is a major pathogen of varieties of oral mucous infection. Prostaglandin E2 (PGE₂) is a pro-inflammatory factor and Cyclooxygenase 2 (COX-2) is a critical enzyme of PGE₂ biosynthesis. The purpose of this study is to investigate whether Staphylococcus aureus can increase PGE₂ production of oral epithelial cells and how PGE₂ functions in the growth and adherence of Staphylococcus aureus. mRNA levels of COX-2, fnbpA and fnbpB were estimated by quantitative PCR. PGE₂ production was measured by Enzyme Linked Immunosorbent Assay (ELISA). The binding biomass of Staphylococcus aureus to human fibronectin was investigated by crystal violet staining and confocal laser scanning microscopy and the adherent force was measured by atomic force microscope (AFM). The COX-2 mRNA level and PGE₂ production were increased by Staphylococcus aureus. PGE₂ promoted the growth and biofilm formation of Staphylococcus aureus, enhanced the attachment of Staphylococcus aureus to the human fibronectin as well as to the HOK cells. The transcription of fnbpB was up-regulated by PGE₂ in both early and middle exponential phase but not fnbpA. These results suggest that the activation of COX-2/PGE₂ pathway in oral epithelial cell by Staphylococcus aureus can in turn facilitate the growth and the ability to adhere of the pathogen. These findings uncover a new function of PGE₂ and may lead to the potential of COX-2/PGE₂ targeting in the therapy of inflammation and cancer in both which the COX-2/PGE₂ pathway were observed activated.