Effects of Genetic and Pharmacologic Inhibition of COX-2 on Colitis-associated Carcinogenesis in Mice

Targeting cyclooxygenase-2 for chemoprevention of inflammation-associated intestinal carcinogenesis: An update

Mounting evidence from preclinical and clinical studies suggests that persistent inflammation functions as a driving force in the journey to cancer. Cyclooxygenase-2 (COX-2) is a key enzyme involved in inflammatory signaling. While being transiently upregulated upon inflammatory stimuli, COX-2 has been found to be consistently overexpressed in human colorectal cancer and several other malignancies. The association between chronic inflammation and cancer has been revisited: cancer can arise when inflammation fails to resolve. Besides its proinflammatory functions, COX-2 also catalyzes the production of pro-resolving as well as anti-inflammatory metabolites from polyunsaturated fatty acids. This may account for the side effects caused by long term use of some COX-2 inhibitory drugs during the cancer chemopreventive trials. This review summarizes the latest findings highlighting the dual functions of COX-2 in the context of its implications in the development, maintenance, and progression of cancer.

Gliclazide Reduces Colitis-Associated Colorectal Cancer Formation by Deceasing Colonic Inflammation and Regulating AMPK-NF-κB Signaling Pathway

BACKGROUND

Gliclazide is a potential anti-cancer drug candidate for preventing carcinogenesis. However, the effect of gliclazide on colitis-associated colorectal cancer remains unknown.

AIMS

We aimed to evaluate whether gliclazide plays a protective role in colitis-associated colorectal cancer and the underlying molecular mechanism.

METHODS

The administration of azoxymethane (AOM) followed by dextran sulfate sodium (DSS) aimed to induce colitis-associated colorectal cancer in mice. C57BL mice were gavaged with gliclazide (6 mg/kg by gavage 5 days a week) for 12 weeks immediately following AOM administration. After sacrificing the mice, colon tissues were measured for tumor number and tumor burden. The proliferation- and inflammation-related molecular mechanisms were explored.

RESULTS

The administration of gliclazide significantly reduced the tumor number and tumor burden in mice. Cell proliferation decreased in the gliclazide group compared with the control group, as indicated by reduced Ki-67 expression. Furthermore, gliclazide alleviated colonic inflammation, significantly decreased pro-inflammatory factor TNF-α levels and increased anti-inflammatory factor IL-10 levels in vivo. In vivo and vitro, it was shown that gliclazide increased the level of phospho-AMPK (p-AMPK) and inhibited NF-κB activity. Further studies demonstrated that the inhibition of NF-κB activity induced by gliclazide was mediated by p-AMPK in vitro.

CONCLUSIONS

Gliclazide effectively alleviated colonic inflammation and prevented colonic carcinogenesis in an AOM-DSS mouse model by modulating the AMPK-NF-κB signaling pathway. Thus, gliclazide holds potential as a chemopreventive agent for colitis-associated colorectal cancer.

Network pharmacology and molecular docking reveal potential mechanism of esculetin in the treatment of ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of the colonic mucosa. Esculetin is a type of natural coumarin that has many pharmacological activities such as antioxidant, anticancer, anti-inflammatory, etc. A previous study showed that esculetin improved intestinal inflammation and reduced serum proinflammatory cytokines in UC. The present study aimed to utilize network pharmacology and molecular docking to explore the potential mechanism of esculetin against UC. The potential gene targets of esculetin were predicted through SwissTargetPrediction and Super-PRED web servers. UC-related genes were obtained from DisGeNet, OMIM, and GeneCards databases. The overlap between gene targets of esculetin and UC-related genes were identified as the potential targets of esculetin against UC. The interaction between these overlapping genes was analyzed by the STRING database and the core genes were identified by Cytoscape platform. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of the core genes were then performed. And the results of these analyses were further confirmed through molecular docking. A total of 50 overlapping genes were identified as the potential action targets of esculetin against UC. Among them, 10 genes (AKT1, STAT1, CCND1, SRC, PTGS2, EGFR, NFKB1, ESR1, MMP9, SERPINE1) were finally identified as the core genes. The Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis results showed that the top signaling pathway associated with the core genes of esculetin against UC was the prolactin (PRL) signaling pathway. Molecular docking results showed that esculetin has a strong binding affinity to the core genes, as well as PRL and prolactin receptor. This study suggests that esculetin may have a crucial impact on UC through the PRL signaling pathway and provides insights into the potential mechanism of esculetin in the treatment of UC, which may shed light on the mechanism and treatment of UC.

Inhibitory Effect of Zinc on Colorectal Cancer by Granzyme B Transcriptional Regulation in Cytotoxic T Cells

Zinc is one of the essential trace elements and is involved in various functions in the body. Zinc deficiency is known to cause immune abnormalities, but the mechanism is not fully understood. Therefore, we focused our research on tumor immunity to elucidate the effect of zinc on colorectal cancer and its mechanisms. Mice were treated with azoxymethane (AOM) and dextran sodium sulfate (DSS) to develop colorectal cancer, and the relationship between zinc content in the diet and the number and area of tumors in the colon was observed. The number of tumors in the colon was significantly higher in the no-zinc-added group than in the normal zinc intake group, and about half as many in the high-zinc-intake group as in the normal-zinc-intake group. In T-cell-deficient mice, the number of tumors in the high-zinc-intake group was similar to that in the normal-zinc-intake group, suggesting that the inhibitory effect of zinc was dependent on T cells. Furthermore, we found that the amount of granzyme B transcript released by cytotoxic T cells upon antigen stimulation was significantly increased by the addition of zinc. We also showed that granzyme B transcriptional activation by zinc addition was dependent on calcineurin activity. In this study, we have shown that zinc exerts its tumor-suppressive effect by acting on cytotoxic T cells, the center of cellular immunity, and increases the transcription of granzyme B, one of the key molecules in tumor immunity.

Aspirin activates resolution pathways to reprogram T cell and macrophage responses in colitis-associated colorectal cancer

Inflammation is linked with carcinogenesis in many types of cancer including colorectal cancer (CRC). Aspirin is recommended for the prevention of CRC, although the mechanism(s) mediating its immunomodulatory actions remain incompletely understood. Here, we demonstrate that aspirin increased concentrations of the immune-regulatory aspirin-triggered specialized proresolving mediators (AT-SPMs), including AT-lipoxin A4 and AT-resolvin D1, in colonic tissues during inflammation-associated CRC (I-CRC). Aspirin also down-regulated the expression of the checkpoint protein programmed cell death protein-1 in macrophages and CD8+ T cells from the colonic mucosa. Inhibition of AT-SPM biosynthesis or knockout of the AT-SPM receptor Alx/Fpr2 reversed the immunomodulatory actions of aspirin on macrophages and CD8+ T cells and abrogated its protective effects during I-CRC. Furthermore, treatment of mice with AT-SPM recapitulated the immune-directed actions of aspirin during I-CRC. Together, these findings elucidate a central role for AT-SPM in mediating the immune-directed actions of aspirin in regulating I-CRC progression.

Oral administration of E-type prostanoid (EP) 1 receptor antagonist suppresses carcinogenesis and development of prostate cancer via upregulation of apoptosis in an animal model

Prostaglandin E2 plays an important role in carcinogenesis and malignant potential of prostate cancer (PC) cells by binding to its specific receptors, E-type prostanoid (EP) receptors. However, anti-carcinogenic effects of the EP receptor antagonist are unclear. In this study, we used a mouse model of PC. The mice were provided standard feed (control) or feed containing the EP1 receptor antagonist and were sacrificed at 10, 15, 30, and 52 weeks of age. Apoptosis was evaluated by immunohistochemical analysis using a cleaved caspase-3 assay. The incidence of cancer in the experimental group was significantly lower than that in the control group at 15, 30, and 52 weeks of age. The percentage of poorly differentiated PC cells was significantly lower in the experimental group than in the control group at 30 and 52 weeks of age. The percentage of apoptotic cells in the experimental group was significantly higher than that in the control group at 15, 30, and 52 weeks of age. These findings indicate that feeding with the addition of EP1 receptor antagonist delayed PC progression via the upregulation of apoptosis. We suggest that the EP1 receptor antagonist may be a novel chemopreventive agent for PC.

Nutraceuticals and diet in human health and disease. The special issue at a glance

This first Special Issue collects fifteen original research and up-to-date review articles addressing the beneficial properties of herbal products, nutrient supplements, dietary regimens, and functional food for the complementary therapy of human pathologies. In these articles, renowned scholars present and discuss the curative effects and the molecular mechanisms of action of nutraceuticals, medicinal herbs, and dietary regimens that have been proven effective in the treatment of cancers, metabolic syndrome, fatty liver disease, hearth arrythmia and neurodegenerative disorders.