Wnt/β-catenin signaling enhances cyclooxygenase-2 (COX2) transcriptional activity in gastric cancer cells

Biological Activities of Molecules Derived from Olea europaea L. Tested In Vitro

BACKGROUND

Extra virgin olive oil is a typical food of the Mediterranean area, obtained by pressing Olea europaea L. fruits. Its polyphenols have been studied for their antioxidant function and protective action against cancer and chronic kidney disease. In this in vitro study, we tested titrated extracts from Olea europaea L. on a human embryonic kidney 293 (HEK-293E) cell line, regarding their pro-apoptotic and antiproliferative capacities, using " IncuCyte® S3 Live-Cell Analysis System".

MATERIALS AND METHODS

We selected Olea europaea L. active compounds like hydroxytyrosol (HT) and oleuropein (OLE). These extracts were tested at different concentrations and characterized by HPLC-DAD-MS for the content in secondary active metabolites. The real-time observation of cell behavior was performed by IncuCyte, which can quantitatively analyze the cell proliferation and death.

RESULTS

This study showed that all the tested extracts can significantly inhibit cellular growth at 50 µM but the reduced proliferation is not related to an increase in cellular apoptosis. Instead, the same analysis performed by using extracts at 100 µM reveals that they can inhibit cellular growth, further inducing cellular apoptosis.

CONCLUSIONS

The results on the HEK-293E cells confirmed the antiproliferative and proapoptotic actions of active compounds from an Olea europaea L. matrix in this cell line.

Role of CELF2 in ferroptosis: Potential targets for cancer therapy (Review)

Ferroptosis is a novel form of regulated cellular necrosis that plays a critical role in promoting cancer progression and developing drug resistance. The main characteristic of ferroptosis is iron‑dependent lipid peroxidation caused by excess intracellular levels of reactive oxygen species. CUGBP ELAV‑like family number 2 (CELF2) is an RNA‑binding protein that is downregulated in various types of cancer and is associated with poor patient prognoses. CELF2 can directly bind mRNA to a variety of ferroptosis control factors; however, direct evidence of the regulatory role of CELF2 in ferroptosis is currently limited. The aim of the present review was to summarise the findings of previous studies on CELF2 and its role in regulating cellular redox homeostasis. The present review may provide insight into the possible mechanisms through which CELF2 affects ferroptosis and to provide recommendations for future studies.

Global role of IGF2BP1 in controlling the expression of Wnt/β-catenin-regulated genes in colorectal cancer cells

Introduction: Wnt/β-catenin signaling controls cell division and lineage specification during embryonic development, and is crucial for stem cells maintenance and gut tissue regeneration in adults. Aberrant activation of Wnt/β-catenin signaling is also essential for the pathogenesis of a variety of malignancies. The RNA-binding protein IGF2BP1 is a transcriptional target of Wnt/β-catenin signaling, normally expressed during development and often reactivated in cancer cells, where it regulates the stability of oncogenic mRNA. Methods: In this study, we employed iCLIP and RNA sequencing techniques to investigate the role of IGF2BP1 in the post-transcriptional regulation of Wnt/β-catenin-induced genes at a global level within colorectal cancer (CRC) cells characterized by constitutively active Wnt/β-catenin signaling. Results and Discussion: In our study, we show that, in contrast to normal cells, CRC cells exhibit a much stronger dependency on IGF2BP1 expression for Wnt/β-catenin-regulated genes. We show that both untransformed and CRC cells have their unique subsets of Wnt/β-catenin-regulated genes that IGF2BP1 directly controls through binding to their mRNA. Our iCLIP analysis revealed a significant change in the IGF2BP1-binding sites throughout the target transcriptomes and a significant change in the enrichment of 6-mer motifs associated with IGF2BP1 binding in response to Wnt/β-catenin signaling. Our study also revealed a signature of IGF2BP1-regulated genes that are significantly associated with colon cancer-free survival in humans, as well as potential targets for CRC treatment. Overall, this study highlights the complex and context-dependent regulation of Wnt/β-catenin signaling target genes by IGF2BP1 in non-transformed and CRC cells and identifies potential targets for colon cancer treatment.

Functional high-throughput screen identifies microRNAs that promote butyrate-induced death in colorectal cancer cells

The gut fermentation product butyrate displays anti-cancer properties in the human proximal colon, including the ability to inhibit proliferation and induce apoptosis in colorectal cancer (CRC) cells. A natural histone deacetylase inhibitor (HDACi), butyrate can alter histone acetylation patterns in CRC cells, and thereby regulate global gene expression, including the non-coding transcriptome and microRNAs (miRNAs). Dysregulated miRNA expression affects CRC development and progression; however, the interplay between miRNA activity and butyrate response remains to be elucidated. A high-throughput functional screen was employed to identify miRNAs that can act as enhancers of the anti-cancer properties of butyrate. Validation studies confirmed that several miRNAs, including miR-125b, miR-181a, miR-593, and miR-1227, enhanced apoptosis, decreased proliferation, and promoted cell-cycle arrest in the presence of butyrate. Pathway analyses of predicted miRNA target genes highlighted their likely involvement in critical cancer-related growth pathways, including WNT and PI3K signaling. Several cancer-associated miRNA targets, including TRIM29, COX2, PIK3R3, CCND1, MET, EEF2K, DVL3, and NUP62 were synergistically regulated by the combination of cognate miRNAs and butyrate. Overall, this study has exposed the potential of miRNAs to act as enhancers of the anti-cancer effects of HDAC inhibition and identifies specific miRNAs that might be exploited for therapeutic benefit.

A refractory liver metastatic solid pseudopapillary neoplasm pancreas harbored CTNNB1 mutation showed good response to celecoxib: A case report

Solid pseudopapillary neoplasm (SPN) of the pancreas is rare relatively low-grade malignant neoplasm and metastasis rarely. Surgical resection is the primary treatment option for primary and metastatic lesions of SPN, and chemotherapy is often ineffective in non-operable SPNs. SPNs are characterized by the presence of somatic CTNNB1 exon 3 mutations, leading to the activation of Wnt/β-catenin/Cox-2 signal pathway. Here, we firstly report that a refractory liver metastatic pancreatic SPN patient after the failure of multi-line chemotherapies benefited from the Cox-2 selective inhibitor (Celecoxib) based on CTNNB1 D32V mutation detected by next-generation sequencing (NGS), achieving a more than 22-month progression-free survival without any adverse events. Our case provides a potential treatment option for liver metastatic SPN patients with CTNNB1 mutations and highlights the application of NGS for the better treatment decision making.

Targeting Wnt/β-catenin signaling pathway in triple-negative breast cancer by benzylic organotrisulfides: Contribution of the released hydrogen sulfide towards potent anti-cancer activity

The potent anti-cancer activity of naturally occurring organopolysulfides has attracted wide research attention over the last two decades. Sustained donation of hydrogen sulfide (H₂S) from organopolysulfides is found to be beneficial for the treatment of several organ-specific cancers. In the present study, for the first time, the mechanism of action for the potent anti-cancer activity of bis(3,5-dimethoxybenzyl) trisulfide 4 against highly aggressive triple-negative breast cancer cells (MDA-MB-231) is described. Preliminary in vitro studies revealed potent anti-proliferative activity of the trisulfide 4 against triple-negative breast cancer cells with an IC₅₀ value of 1.0 μM. Mechanistic studies reveal that the compound exhibited anti-cancer activity, primarily by targeting and suppressing the Wnt/β-catenin signaling pathway. The inactivation of the β-catenin level was associated with the cell cycle arrest in the G2/M phase and the significant down-regulation of downstream signaling genes such as Cyclin D1 and c-Myc expression. Several control experiments with analogous organosulfur compounds and the key enzyme inhibitors reveal that the presence of a trisulfide unit in the compound is crucial for the desired inactivation of β-catenin expression, which is promoted by GSK-3β-induced phosphorylation of β-catenin and its proteasomal degradation. Moreover, the trisulfide unit or the released H₂S induced down-regulation of the p53 expression with the possible S-sulfhydration process led to p53-independent up-regulation of p21 expression. Therefore, the key results of this study highlighting the potency of synthetic benzylic organotrisulfide and the released H₂S towards the growth inhibition of triple-negative breast cancer via Wnt/β-catenin signaling pathway would certainly be helpful for further studies and developing small-molecule anti-cancer therapeutics in future.

A Comprehensive Review on the Anti-Cancer Effects of Oleuropein

In Mediterranean cuisine and culture, olive oil and olive fruits play a significant role. Many people believe that those who consume olive oil and its fruit live longer and have a decreased risk of illness. Olive leaves were used to treat a range of diseases in ancient times, including malaria fever and lower earaches. Although it was not understood at the time what key components were responsible for these effects because they had not yet been discovered, Oleuropein is now recognized as one of the primary elements in immature olive fruits and leaves. Later research was carried out to determine the effects of this molecule, and it was determined that it functions as an antioxidant. Oleuropein consumption has aided in cancer treatment over the years, and this was assumed to be owing to its antioxidant properties. Oleuropein’s effects on cancer, however, go beyond that; it is now known that Oleuropein functions as both an anti-proliferative and an apoptotic promoter in many cancer cells. The kinetics and dosages of Oleuropein and the mechanisms behind its involvement and effects in cancer are explored in this review. Finally, the effects of Oleuropein in combination with anticancer medicines are investigated.

Withania somnifera - a magic plant targeting multiple pathways in cancer related inflammation

BACKGROUND

Deregulated inflammatory responses are known to play a pivotal role in cancer initiation and progression. Tumor microenvironment is associated with the presence of a diverse array of inflammatory reactions, which further help tumor growth, metastasis and drug resistance. Withania somnifera is known to curb proliferation of cancer cells and lower inflammatory responses.

PURPOSE

In order to minimize the inflammation, cancer treatments often include immunomodulatory drugs. However, given the side effects of both of the cytotoxic cancer drugs and synthetic immunomodulatory agents, there is a need to develop novel anti-inflammatory agents for improved cancer therapy. A number of reports indicate that bioactive phytochemicals derived from W. somnifera exhibit anti-inflammatory capabilities in cancer. A deeper look into the underlying molecular mechanisms implicated in W. somnifera mediated anti inflammation is lacking, which is essential to fully understand the potential of this magical plant in cancer. Therefore, in the present review we are summarizing various reports, which describe mechanistic understanding of W. somnifera in cancer related inflammation.

STUDY DESIGN AND METHODOLOGY

In order to gather information on the molecular pathways affected by W. somnifera in cancer related inflammation, 'PubMed' and 'Science Direct' databases were searched using keywords Withania, cancer inflammation, and Withaferin A. Selected literature was analyzed to cover the role of inflammation in cancer, usage and side effects of anti-inflammatory drugs, W. somnifera as an immunomodulatory agent in cancer, molecular pathways modulated by W. somnifera in various preclinical models, and clinical trials using W. somnifera as an anti-inflammatory agent.

RESULTS

Upon literature survey we found that both W. somnifera extracts and Withaferin-A, exhibit anti inflammatory activities in various preclinical cancer models. W. somnifera modulates a number of signaling pathways such as NF-kB, JAK-STAT and AP1 to reduce cancer related inflammation. Anti inflammatory properties of W. somnifera might be effective in the treatment of drug resistance in cancers. Based on its promising effects against cancer associated inflammation in preclinical studies, W. somnifera derived products are being tested in clinical trials.

CONCLUSION

Several preclinical studies demonstrated anti-inflammatory potential of W. somnifera in a variety of cancers. While a few clinical trials are investigating the role of W. somnifera in various diseases, focused studies on its role in cancer related inflammation are lacking. Additionally, its anti-inflammatory effects offer targeting of senescence associated secretory phenotype (SASP), which is speculated to play a critical role in chemoresistance. Apart from targeting cancer cell proliferation, anti-inflammatory effects of Withania provide double advantage in cancer management. Therefore, clinical trials to target cancer related inflammation using W. somnifera as a drug, should be performed to validate its advantages in cancer therapy.

Pharmacogenetic Review: Germline Genetic Variants Possessing Increased Cancer Risk With Clinically Actionable Therapeutic Relationships

As our understanding of genomics and genetic testing continues to advance, the personalization of medical decision making is progressing simultaneously. By carefully crafting medical care to fit the specific needs of the individual, patients can experience better long-term outcomes, reduced toxicities, and improved healthcare experiences. Genetic tests are frequently ordered to help diagnose a clinical presentation and even to guide surveillance. Through persistent investigation, studies have begun to delineate further therapeutic implications based upon unique relationships with genetic variants. In this review, a pre-emptive approach is taken to understand the existing evidence of relationships between specific genetic variants and available therapies. The review revealed an array of diverse relationships, ranging from well-documented clinical approaches to investigative findings with potential for future application. Therapeutic agents identified in the study ranged from highly specific targeted therapies to agents possessing similar risk factors as a genetic variant. Working in conjunction with national standardized treatment approaches, it is critical that physicians appropriately consider these relationships when developing personalized treatment plans for their patients.

MT1G inhibits the growth and epithelial-mesenchymal transition of gastric cancer cells by regulating the PI3K/AKT signaling pathway

Gastric carcinoma (GC) is a malignant tumor that has high mortality and morbidity worldwide. Although many efforts have been focused on the development and progression of GC, the underlying functional regulatory mechanism of GC needs more clarification. Metallothionein 1G (MT1G) is a member of the metallothionein family (MTs), and hypermethylation of MT1G occurred in a variety of cancers, including gastric cancer. However, the functional mechanism of MT1G in GC remains unclear. Here, we demonstrated that MT1G was down-regulated in GC tissues and cells. Overexpression of MT1G inhibited cell proliferation, foci formation and cell invasion, while knockdown of MT1G increased cell proliferation, foci formation and cell invasion. In addition, MT1G overexpression inhibited cell cycle progression and MT1G deficiency exerted opposite phenotype. p-AKT was negatively regulated by MT1G. In summary, our study reveals that MT1G exerts crucial role in regulating of cell proliferation and migration of gastric cancer, providing new insights for MT1G-related pathogenesis and a basis for developing new strategies for treatment of GC.

LINC02273 Promotes Hepatocellular Carcinoma Progression via Retaining β-Catenin in the Nucleus to Augment Wnt Signaling

Hepatocellular carcinoma (HCC) is a lethal malignancy whereas the molecular mechanisms remain poorly understood. Recently, long noncoding RNAs (lncRNA) have been shown to regulate HCC progression. However, the involved lncRNAs remain to be fully explored. Here, we showed the expression pattern and biological function of a recently identified lncRNA, LINC02273, in HCC. LINC02273 played a critical role in HCC progression via stabilizing β-catenin. Knockdown of LINC02237 remarkably inhibited the proliferation, stemness, migration, and invasion abilities, whereas it increased the apoptosis of HCC cells. Overall, we characterized the functions of LINC02273 in HCC and its potential as a novel HCC targeting candidate.

Cytoguardin: A Tryptophan Metabolite against Cancer Growth and Metastasis

Cytoguardin was identified in the conditioned medium of fibroblasts as a tryptophan metabolite, 5-methoxytryptophan (5-MTP). It is synthesized via two enzymatic steps: tryptophan hydroxylase (TPH) and hydroxyindole O-methyltransferase (HIOMT). A truncated HIOMT isoform, HIOMT298, catalyzes 5-MTP synthesis. Cancer cells produce scarce 5-MTP due to defective HIOMT298 expression. 5-MTP inhibits cancer cell COX-2 expression and thereby reduces COX-2-mediated cell proliferation and migration. 5-MTP also inhibits MMP-9 expression and thereby reduces cancer cell invasion. 5-MTP exerts its anti-cancer effect by blocking p38 MAPK and p38-mediated NF-κB and p300 HAT activation. The stable transfection of A549 cells with HIOMT298 restores 5-MTP production which renders cancer cells less aggressive. The implantation of HIOMT-transfected A549 into subcutaneous tissues of a murine xenograft tumor model shows that HIOMT-transduced A549 cells form smaller tumors and generate fewer metastatic lung nodules than control A549 cells. HIOMT298 transfection suppresses aromatic amino acid decarboxylase (AADC) expression and serotonin production. Serotonin is a cancer-promoting factor. By restoring 5-MTP and suppressing serotonin production, HIOMT298 overexpression converts cancer cells into less malignant phenotypes. The analysis of HIOMT expression in a human cancer tissue array showed reduced HIOMT levels in a majority of colorectal, pancreatic, and breast cancer. HIOMT298 may be a biomarker of human cancer progression. Furthermore, 5-MTP has the potential to be a lead compound in the development of new therapy for the chemoprevention of certain cancers such as hepatocellular cancer.

Wnt signaling enhances macrophage responses to IL-4 and promotes resolution of atherosclerosis

Atherosclerosis is a disease of chronic inflammation. We investigated the roles of the cytokines IL-4 and IL-13, the classical activators of STAT6, in the resolution of atherosclerosis inflammation. Using Il4-/-Il13-/- mice, resolution was impaired, and in control mice, in both progressing and resolving plaques, levels of IL-4 were stably low and IL-13 was undetectable. This suggested that IL-4 is required for atherosclerosis resolution, but collaborates with other factors. We had observed increased Wnt signaling in macrophages in resolving plaques, and human genetic data from others showed that a loss-of-function Wnt mutation was associated with premature atherosclerosis. We now find an inverse association between activation of Wnt signaling and disease severity in mice and humans. Wnt enhanced the expression of inflammation resolving factors after treatment with plaque-relevant low concentrations of IL-4. Mechanistically, activation of the Wnt pathway following lipid lowering potentiates IL-4 responsiveness in macrophages via a PGE2/STAT3 axis.

Wnt/β-catenin Pathway-Mediated PPARδ Expression during Embryonic Development Differentiation and Disease

The Wnt/β-catenin signaling pathway plays a crucial role in early embryonic development. Wnt/β-catenin signaling is a major regulator of cell proliferation and keeps embryonic stem cells (ESCs) in the pluripotent state. Dysregulation of Wnt signaling in the early developmental stages causes several hereditary diseases that lead to embryonic abnormalities. Several other signaling molecules are directly or indirectly activated in response to Wnt/β-catenin stimulation. The crosstalk of these signaling factors either synergizes or opposes the transcriptional activation of β-catenin/Tcf4-mediated target gene expression. Recently, the crosstalk between the peroxisome proliferator-activated receptor delta (PPARδ), which belongs to the steroid superfamily, and Wnt/β-catenin signaling has been reported to take place during several aspects of embryonic development. However, numerous questions need to be answered regarding the function and regulation of PPARδ in coordination with the Wnt/β-catenin pathway. Here, we have summarized the functional activation of the PPARδ in co-ordination with the Wnt/β-catenin pathway during the regulation of several aspects of embryonic development, stem cell regulation and maintenance, as well as during the progression of several metabolic disorders.

E7386, a Selective Inhibitor of the Interaction between β-Catenin and CBP, Exerts Antitumor Activity in Tumor Models with Activated Canonical Wnt Signaling

The Wnt/β-catenin signaling pathway plays crucial roles in embryonic development and the development of multiple types of cancer, and its aberrant activation provides cancer cells with escape mechanisms from immune checkpoint inhibitors. E7386, an orally active selective inhibitor of the interaction between β-catenin and CREB binding protein, which is part of the Wnt/β-catenin signaling pathway, disrupts the Wnt/β-catenin signaling pathway in HEK293 and adenomatous polyposis coli (APC)-mutated human gastric cancer ECC10 cells. It also inhibited tumor growth in an ECC10 xenograft model and suppressed polyp formation in the intestinal tract of Apc^{Min /+} mice, in which mutation of Apc activates the Wnt/β-catenin signaling pathway. E7386 demonstrated antitumor activity against mouse mammary tumors developed in mouse mammary tumor virus (MMTV)-Wnt1 transgenic mice. Gene expression profiling using RNA sequencing data of MMTV-Wnt1 tumor tissue from mice treated with E7386 showed that E7386 downregulated genes in the hypoxia signaling pathway and immune responses related to the CCL2, and IHC analysis showed that E7386 induced infiltration of CD8⁺ cells into tumor tissues. Furthermore, E7386 showed synergistic antitumor activity against MMTV-Wnt1 tumor in combination with anti-PD-1 antibody. In conclusion, E7386 demonstrates clear antitumor activity via modulation of the Wnt/β-catenin signaling pathway and alteration of the tumor and immune microenvironments, and its antitumor activity can be enhanced in combination with anti-PD-1 antibody. SIGNIFICANCE: These findings demonstrate that the novel anticancer agent, E7386, modulates Wnt/β-catenin signaling, altering the tumor immune microenvironment and exhibiting synergistic antitumor activity in combination with anti-PD-1 antibody.

Chemoprevention in familial adenomatous polyposis: past, present and future

Familial adenomatous polyposis (FAP) is a hereditary colorectal cancer syndrome characterized by colorectal adenomas and a near 100% lifetime risk of colorectal cancer (CRC). Prophylactic colectomy, usually by age 40, is the gold-standard therapy to mitigate this risk. However, colectomy is associated with morbidity and fails to prevent extra-colonic disease manifestations, including gastric polyposis, duodenal polyposis and cancer, thyroid cancer, and desmoid disease. Substantial research has investigated chemoprevention medications in an aim to prevent disease progression, postponing the need for colectomy and temporizing the development of extracolonic disease. An ideal chemoprevention agent should have a biologically plausible mechanism of action, be safe and easily tolerated over a prolonged treatment period, and produce a durable and clinically meaningful effect. To date, no chemoprevention agent tested has fulfilled these criteria. New agents targeting novel pathways in FAP are needed. Substantial preclinical literature exists linking the molecular target of rapamycin (mTOR) pathway to FAP. A single case report of rapamycin, an mTOR inhibitor, used as chemoprevention in FAP patients exists, but no formal clinical studies have been conducted. Here, we review the prior literature on chemoprevention in FAP, discuss the rationale for rapamycin in FAP, and outline a proposed clinical trial testing rapamycin as a chemoprevention agent in patients with FAP.

Advancements of compounds targeting Wnt and Notch signalling pathways in the treatment of inflammatory bowel disease and colon cancer

The Wnt and Notch signalling pathways are important for maintenance of intestinal epithelial barrier integrity by intestinal stem cells (ISCs). Dysfunction of these pathways is implicated in inflammatory bowel disease (IBD) and colon cancer. The objective of this review is to summarise advancements of drugs that regulate Wnt and Notch in the treatment of IBD and colon cancer. The compositions and biological effects of Wnt and Notch modulators in both ISCs and non-ISCs are discussed. The drugs, including phytochemicals, plant extracts, probiotics and synthetic compounds, have been found to regulate Wnt and Notch signalling pathways by targeting regulatory factors (including secreted frizzled-related proteins or pathway proteins such as β-catenin and γ-secretase) to alleviate IBD and colon cancer. This review highlights the potential for targeting Wnt and Notch pathways to treat IBD and colon cancer.

KSHV G-protein coupled receptor vGPCR oncogenic signaling upregulation of Cyclooxygenase-2 expression mediates angiogenesis and tumorigenesis in Kaposi's sarcoma

Kaposi's sarcoma-associated herpesvirus (KSHV) vGPCR is a constitutively active G protein-coupled receptor that subverts proliferative and inflammatory signaling pathways to induce cell transformation in Kaposi's sarcoma. Cyclooxygenase-2 (COX-2) is an inflammatory mediator that plays a key regulatory role in the activation of tumor angiogenesis. Using two different transformed mouse models and tumorigenic full KSHV genome-bearing cells, including KSHV-Bac16 based mutant system with a vGPCR deletion, we demostrate that vGPCR upregulates COX-2 expression and activity, signaling through selective MAPK cascades. We show that vGPCR expression triggers signaling pathways that upregulate COX-2 levels due to a dual effect upon both its gene promoter region and, in mature mRNA, the 3'UTR region that control mRNA stability. Both events are mediated by signaling through ERK1/2 MAPK pathway. Inhibition of COX-2 in vGPCR-transformed cells impairs vGPCR-driven angiogenesis and treatment with the COX-2-selective inhibitory drug Celecoxib produces a significant decrease in tumor growth, pointing to COX-2 activity as critical for vGPCR oncogenicity in vivo and indicating that COX-2-mediated angiogenesis could play a role in KS tumorigenesis. These results, along with the overexpression of COX-2 in KS lesions, define COX-2 as a potential target for the prevention and treatment of KSHV-oncogenesis.

KLF5-mediated COX2 upregulation contributes to tumorigenesis driven by PTEN deficiency

Tumor suppressor gene PTEN is frequently mutated in a wide variety of cancers. However, the downstream targets or signal transduction pathways of PTEN remain not fully understood. By analyzing Pten-null mouse embryonic fibroblasts (MEFs) cell lines and their isogenic counterparts, we showed that loss of PTEN led to increased cyclooxygenase2 (COX2) expression in an AKT-independent manner. Moreover, we demonstrated that PTEN deficiency promotes the transcription of COX2 via upregulation of the transcription factor Krüppel-like factor 5 (KLF5). Knocked down the expression of COX2 suppressed proliferation, migration and tumoral growth of Pten-null cells. Further experiments revealed that COX2 enhanced Pten-null MEFs growth and migration through upregulation of NADPH oxidase 4 (NOX4). In addition, MK-2206, a specific inhibitor of AKT, in combination with celecoxib, a COX2 inhibitor, strongly inhibited Pten-deficient cell growth. We concluded that KLF5/COX2/NOX4 signaling pathway is critical for cell growth and migration caused by the loss of PTEN, and the combination of MK-2206 and celecoxib may be an effective new approach to treating PTEN deficiency related tumors.

Hepatoprotective effect of Matricaria chamomilla aqueous extract against 1,2-Dimethylhydrazine-induced carcinogenic hepatic damage in mice

Dimethylhydrazine (DMH) is a potent colonic and hepatic carcinogen that is metabolized into oxyradicals causing liver injury and DNA mutations. Matricaria chamomilla is a well-documented medicinal herb that possesses anti-inflammatory, antioxidant and antitumor activities and is commonly used to treat diverse ailments. The present study aimed to reveal the hepatoprotective effects of Matricaria chamomilla aqueous extract during an intermediate stage of colorectal cancer (CRC) in mice. Male Balb/c mice were divided into six groups: group A served as control, group B received chamomile extract (150 mg/Kg b.w.) orally for 12 weeks, and groups C-F received weekly intraperitoneal injections of DMH (20 mg/Kg b.w.) once a week for 12 weeks. In addition to DMH, groups D and F received chamomile during the initiation and post-initiation stages, respectively. Blood and liver samples were collected for biochemical and molecular analyses. The results showed that DMH induced hepatic injury in mice as shown by significant increase in serum aspartate aminotransferase and alanine aminotransferase. The changes in biochemical parameters were accompanied by activation of the Wnt signaling pathway leading to increased hepatocytes proliferation as well as inflammation evidenced by high levels of pro-inflammatory enzymes cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS). The results also showed potential hepatoprotective effects of chamomile extract against DMH-induced liver injury, proliferation and inflammation. Chamomile restored the biochemical and molecular parameters and this improvement was more pronounced in mice pretreated with the extract. In conclusion, chamomile extract may exert its hepatoprotective activities against DMH probably due to the antioxidant, antiproliferative and anti-inflammatory properties of its flavonoids.

COX-2 mediated crosstalk between Wnt/β-catenin and the NF-κB signaling pathway during inflammatory responses induced by Haemophilus parasuis in PK-15 and NPTr cells

Haemophilus parasuis infection causes typical acute systemic inflammation in pigs, is characterized by fibrinous polyserositis inflammation, and results in great economic losses to the swine industry worldwide. However, the molecular details of how the host modulates the acute inflammatory response induced by H. parasuis are largely unknown. In previous studies, we found that H. parasuis high-virulence strain SH0165 infection induced the activation of both Wnt/β-catenin and NF-κB signaling in PK-15 and NPTr cells. In this study, we found that the activation of NF-κB, a central hub in inflammatory signaling, was impeded by the Wnt/β-catenin pathway during H. parasuis infection. In contrast, blocking NF-κB activity had no effect on the Wnt/β-catenin pathway during H. parasuis infection. Furthermore, we found that the inhibitory effect of β-catenin on NF-κB activity was mediated by its target gene, pig cyclooxygenase-2 (COX-2). Therefore, we demonstrated that H. parasuis infection activates the canonical Wnt/β-catenin signaling pathway, which leads to decreased NF-κB activity, reducing the acute inflammatory response in pigs. Additionally, the data provide a possible perspective for understanding the anti-inflammatory role of Wnt/β-catenin in pigs during bacterial infection.

Prospects of NSAIDs administration as double-edged agents against endometrial cancer and pathological species of the uterine microbiome

Many types of cancers, including endometrial cancer, were found to have cyclooxygenase-2 (COX-2) overexpression. Because this enzyme belongs to the group of pro-inflammatory enzymes, so-called NSAIDs (non-steroidal anti–inflammatory drugs) directly inhibit its activity. An increasing number of reports on COX-2 involvement in cancer, as well as on the role of microbiota in abnormal metabolism and signaling of cells, forces the development of new NSAID types. Besides, NSAIDs can affect some bacteria, which are vaginal/endometrial microbiome members. The overgrowth of those species was found to be a major cause of some uterus diseases. Those infections can lead to chronic inflammatory response and suppress anti-tumorigenic cell pathways. The purpose of this review is to highlight the COX-2 enzyme role in endometrial cancer, the potential effect of the endometrial microbiome on COX-2 enzyme overexpression, and the prospects of NSAIDs use in terms of this type of cancer.

Gastric Damage and Cancer-Associated Biomarkers in Helicobacter pylori-Infected Children

Helicobacter pylori (H. pylori) is well-known to be involved in gastric carcinogenesis, associated with deregulation of cell proliferation and epigenetic changes in cancer-related genes. H. pylori infection is largely acquired during childhood, persisting long-term in about half of infected individuals, a subset of whom will go on to develop peptic ulcer disease and eventually gastric cancer, however, the sequence of events leading to disease is not completely understood. Knowledge on carcinogenesis and gastric damage-related biomarkers is abundant in adult populations, but scarce in children. We performed an extensive literature review focusing on gastric cancer related biomarkers identified in adult populations, which have been detected in children infected with H. pylori. Biomarkers were related to expression levels (RNA or protein) and/or methylation levels (DNA) in gastric tissue or blood of infected children as compared to non-infected controls. In this review, we identified 37 biomarkers of which 24 are over expressed, three are under expressed, and ten genes are significantly hypermethylated in H. pylori-infected children compared to healthy controls in at least 1 study. Only four of these biomarkers (pepsinogen I, pepsinogen II, gastrin, and SLC5A8) have been studied in asymptomatically infected children. Importantly, 13 of these biomarkers (β-catenin, C-MYC, GATA-4, DAPK1, CXCL13, DC-SIGN, TIMP3, EGFR, GRIN2B, PIM2, SLC5A8, CDH1, and VCAM-1.) are consistently deregulated in infected children and in adults with gastric cancer. Future studies should be designed to determine the clinical significance of these changes in infection-associated biomarkers in children and their persistence over time. The effect of eradication therapy over these biomarkers in children if proven significant, could lead to modifications in treatment guidelines for younger populations, and eventually promote the development of preventive strategies, such as vaccination, in the near future.

β-carotene Inhibits Expression of c-Myc and Cyclin E in Helicobacter pylori-infected Gastric Epithelial Cells

Background

Helicobacter pylori infection is a major risk factor in the development of gastric cancer. H. pylori infection of gastric epithelial cells increases the levels of reactive oxygen species (ROS), activates oncogenes, and leads to β-catenin-mediated hyper-proliferation. β-Carotene reduces ROS levels, inhibits oxidant-mediated activation of inflammatory signaling and exhibits anticancer properties. The present study was carried out to determine if β-carotene inhibits H. pylori-induced cell proliferation and the expression of oncogenes c-myc and cyclin E by reducing the levels of β-catenin and phosphorylated glycogen synthase kinase 3β (p-GSK3β).

Methods

Gastric epithelial AGS cells were pre-treated with β-carotene (5 and 10 μM) for 2 hours prior to H. pylori infection and cultured for 6 hours (for determination of the levels of p-GSK3β, GSK3β, and β-catenin) and 24 hours (for determination of cell viability and protein levels of c-myc and cyclin E). Cell viability was determined by the MTT assay and protein levels were determined via western blot-based analysis.

Results

β-Carotene inhibited H. pylori-induced increases in the percentage of viable cells, phosphorylated GSK3β (p-GSK3β), and the levels of β-catenin, c-myc and cyclin E.

Conclusions

β-Carotene inhibits H. pylori-induced hyper-proliferation of gastric epithelial cells by suppressing β-catenin signaling and oncogene expression.

MiR-503 suppresses cell proliferation and invasion of gastric cancer by targeting HMGA2 and inactivating WNT signaling pathway

Background

Abnormal expression of microRNAs (miRNAs) is related to human carcinogenesis. Although previous studies have shown that miR-503 expression in gastric cancer (GC) is downregulated, however, the underlying molecular mechanism for miR-503 involved in gastric cancer development is still largely unknown.

Methods

The relative expression of miR-503 in GC tissues and adjacent normal tissues was examined using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analyses. In vitro, cell proliferation and invasion were evaluated by using CCK8, cell colony and transwell invasion assays. In vivo, xenograft tumor model was constructed to assess miR-503 expression whether affects tumor growth or not. Luciferase reporter assay, qRT-PCR and western blot assay were used to demonstrate HMGA2 is a target of miR-503.

Results

We demonstrated that miR-503 expression was significantly downregulated in GC tissues and cell lines compared to adjacent normal tissues and normal gastric mucosa cell lines, respectively. Lower miR-503 expression associated with tumor size, lymph node metastasis, and predicted a poor overall survival (OS) time in GC patients. Subsequently, in vitro, gain-function and loss-function assays confirmed that miR-503 overexpression significantly suppressed GC cell proliferation, colony formation and cell invasion, while decreased miR-503 expression had an adverse effect in GC cells. Furthermore, we found that miR-503 specifically targeted the 3′-UTR regions of HMGA2 mRNA and suppressed its protein expression. Overexpression of HMGA2 could reverse the miR-503 mediated inhibition of GC cell proliferation and invasion. In vivo, miR-503 overexpression dramatically reduced tumor growth. Moreover, we demonstrated that miR-503 suppressed WNT/β-catenin signaling by elevating GSK-3β and p-β-catenin expression, but decreased p-GSK-3β and β-catenin expression in GC cells.

Conclusion

These results provide that miR-503 expression acts as a predictor for GC prognosis and may have a potential application in GC therapy.

Beyond a chemopreventive reagent, aspirin is a master regulator of the hallmarks of cancer

PURPOSE

Aspirin, one of the most commonly used nonsteroidal anti-inflammatory drugs (NAIDS), not only shows cancer chemoprevention effects but also improves cancer therapeutic effects when combined with other therapies. Studies that focus on aspirin regulation of the hallmarks of cancer and the associated molecular mechanisms facilitate a more thorough understanding of aspirin in mediating chemoprevention and may supply additional information for the development of novel cancer therapeutic agents.

METHODS

The relevant literatures from PubMed have been reviewed in this article.

RESULTS

Current studies have revealed that aspirin regulates almost all the hallmarks of cancer. Within tumor tissue, aspirin suppresses the bioactivities of cancer cells themselves and deteriorates the tumor microenvironment that supports cancer progression. In addition to tumor tissues, blocking of platelet activation also contributes to the ability of aspirin to inhibit cancer progression. In terms of the molecular mechanism, aspirin targets oncogenes and cancer-related signaling pathways and activates certain tumor suppressors.

CONCLUSION

Beyond a chemopreventive agent, aspirin is a master regulator of the hallmarks of cancer.

Alterations in WNT Signaling in Leukemias

The WNT/β-catenin signaling pathway plays an important role in the differentiation and proliferation of hematopoietic cells. In recent years, special attention has been paid to the role of impairments in the WNT signaling pathway in pathogenesis of malignant neoplasms of the hematopoietic system. Disorders in the WNT/β-catenin signaling in leukemias identified to date include hypersensitivity to the WNT ligands, epigenetic repression of WNT antagonists, overexpression of WNT ligands, impaired β-catenin degradation in the cytoplasm, and changes in the activity of the TCF/Lef transcription factors. At the molecular level, these impairments involve overexpression of the FZD protein, hypermethylation of the SFRP, DKK, WiF, Sox, and CXXC gene promoters, overexpression of Lef1 and plakoglobin, mutations in GSK3β, and β-catenin phosphorylation by the BCR-ABL kinase. This review is devoted to the systematization of these data.

Gfi1b regulates the level of Wnt/β-catenin signaling in hematopoietic stem cells and megakaryocytes

Gfi1b is a transcriptional repressor expressed in hematopoietic stem cells (HSCs) and megakaryocytes (MKs). Gfi1b deficiency leads to expansion of both cell types and abrogates the ability of MKs to respond to integrin. Here we show that Gfi1b forms complexes with β-catenin, its co-factors Pontin52, CHD8, TLE3 and CtBP1 and regulates Wnt/β-catenin-dependent gene expression. In reporter assays, Gfi1b can activate TCF-dependent transcription and Wnt3a treatment enhances this activation. This requires interaction between Gfi1b and LSD1 and suggests that a tripartite β-catenin/Gfi1b/LSD1 complex exists, which regulates Wnt/β-catenin target genes. Consistently, numerous canonical Wnt/β-catenin target genes, co-occupied by Gfi1b, β-catenin and LSD1, have their expression deregulated in Gfi1b-deficient cells. When Gfi1b-deficient cells are treated with Wnt3a, their normal cellularity is restored and Gfi1b-deficient MKs regained their ability to spread on integrin substrates. This indicates that Gfi1b controls both the cellularity and functional integrity of HSCs and MKs by regulating Wnt/β-catenin signaling pathway.

Gfi1b regulates cellularity of haematopoietic stem cells (HSCs) and megakaryocytes (MKs) as well as spreading of MKs on matrix. Here the authors show that Gfi1b regulates this behaviour by recruiting LSD1 and β-catenin to Wnt/β-catenin signalling targets.

Lipopolysaccharide Stimulated the Migration of NIH3T3 Cells Through a Positive Feedback Between β-Catenin and COX-2

How β-catenin/COX-2 contribute to inflammation-induced fibroblasts migration remains poorly understood. Therefore, in this study, lipopolysaccharide (LPS) was used as a stimulus to accelerate the migration of NIH3T3 cells, which mimicked the tissue repair process. LPS treatment increased the cell migration in concentration-and time-dependent manner. And NS398, a COX-2 inhibitor, inhibited LPS-induced NIH3T3 cells migration. DKK-1, an antagonist of the Wnt/β-catenin signaling, also inhibited that migration. However, TWS119, an inducer of β-catenin via GSK-3β, increased the cell migration. LPS or TWS119 treatment increased COX-2, β-catenin, TGF-β1, and HMGB-1 expressions, and that could be attenuated by NS398 or DKK-1 addition. LPS induced the PGE₂ production, and PGE₂ increased the expression and nuclear translocation of β-catenin, while EP2 blocker, AH6809, alleviated those effects. TWS119 increased the luciferase activity in the COX-2 promoter. In conclusion, LPS stimulated the NIH3T3 fibroblasts migration through a positive feedback between β-catenin and COX-2, in which PGE₂, EP2, TGF-β1, and HMGB-1 played as signal molecules.

Wnt/β-catenin signaling enhances transcription of the CX43 gene in murine Sertoli cells

Sertoli cells provide the nutritional and metabolic support for germ cells. Wnt/β-catenin signaling is important for the development of the seminiferous epithelium during embryonic age, although after birth this pathway is downregulated. Cx43 gene codes for a protein that is critical during testicular development. The Cx43 promoter contains TCF/β-catenin binding elements (TBEs) that contribute CX43 expression in different cell types and which may also be regulating the expression of this gene in Sertoli cells. In this study, we demonstrate that 42GPA9 Sertoli cells respond to treatments that result in accumulation of β-catenin within the nucleus and in upregulation of CX43 gene transcription. β-Catenin binds to TBEs located both upstream and downstream of the transcriptional start site (TSS). Luciferase reporter experiments revealed that TBEs located upstream of the TSS are necessary for β-catenin-mediated upregulation. Our results also indicate that the Wnt/β-catenin-dependent upregulation of the Cx43 gene in Sertoli cells is accompanied by changes in epigenetic parameters that may be directly contributing to generating a chromatin environment that facilitates the establishment of the transcriptional machinery at this promoter.

Protective mechanisms of 6-gingerol in dextran sulfate sodium-induced chronic ulcerative colitis in mice

Ulcerative colitis (UC) is a relapsing and remitting inflammatory disease of the colon, with an increasing incidence worldwide. 6-Gingerol (6G) is a bioactive constituent of Zingiber officinale, which has been reported to possess various biological activities. This study was designed to evaluate the role of 6G in chronic UC. Chronic UC was induced in mice by three cycles of 2.5% dextran sulfate sodium (DSS) in drinking water. Each cycle consisted of 7 days of 2.5% DSS followed by 14 days of normal drinking water. 6G (100 mg/kg) and a reference anti-colitis drug sulfasalazine (SZ) (100 mg/kg) were orally administered daily to the mice throughout exposure to three cycles of 2.5% DSS. Administration of 6G and SZ significantly prevented disease activity index and aberrant crypt foci formation in DSS-treated mice. Furthermore, 6G and SZ suppresses immunoexpression of tumor necrosis factor alpha, interleukin-1β, inducible nitric oxide synthase, Regulated on activation, normal T cell expressed and secreted (RANTES), and Monocyte chemoattractant protein-1 (MCP-1) in the DSS-treated mice. 6G effectively protected against colonic oxidative damage by augmenting the antioxidant status with marked decrease in lipid peroxidation levels in DSS-treated mice. Moreover, 6G significantly inhibited nuclear factor kappa B (P65), p38, cyclooxygenase-2, and β-catenin whereas it enhanced IL-10 and adenomatous polyposis coli expression in DSS-treated mice. In conclusion, 6G prevented DSS-induced chronic UC via anti-inflammatory and antioxidative mechanisms and preservation of the Wnt/β-catenin signaling pathway.

MicroRNA-140-5p suppresses cell proliferation and invasion in gastric cancer by targeting WNT1 in the WNT/β-catenin signaling pathway

MicroRNAs have been suggested as potential regulators in gastric cancer (GC) development through affecting the expression of their target genes. Previous studies have demonstrated that miR-140-5p is downregulated in GC. However, the underlying functional role of miR-140-5p in GC remains largely unknown. The present study revealed that miR-140-5p expression was significantly decreased in 60 GC tissues, compared with corresponding adjacent non-tumor tissues. A lower miR-140-5p expression was significantly associated with lymph node metastasis and an advanced Tumor-Node-Metastasis stage in patients with GC. Furthermore, patients with a lower miR-140-5p expression exhibited shorter disease-free survival and overall survival times. Gain- and loss-of-function assays revealed that increased miR-140-5p expression significantly inhibited GC cell proliferation and invasion ability, as well as the Wnt/β-catenin signaling pathway by decreasing WNT1 and β-catenin expression. However, decreasing miR-140-5p expression had the opposite effects. Bioinformatics methods and dual-luciferase reporter assays revealed that WNT1 was a direct target of miR-140-5p. miR-140-5p suppressed cell proliferation and invasion by regulating WNT1 expression. Therefore, the results of the present study demonstrated that miR-140-5p may serve as a potential prognostic marker and therapeutic target in patients with GC.

Extract of the Blood Circulation-Promoting Recipe-84 Can Protect Rat Retinas by Inhibiting the β-Catenin Signaling Pathway

Extract of the Blood Circulation-Promoting Recipe (EBR-84) from the Chinese Herbal medicine “Blood Circulation Promoting Recipe” could retard retinopathy development. This study investigated whether EBR-84 protects retinas by inhibiting the β-catenin pathway using a rat model of retinopathy and a retinal ganglion cell 5 (RGC-5) cell death model. RGC death was induced by either N-methyl-d-aspartic acid (NMDA) or TWS119 (an activator of the β-catenin pathway). After the corresponding treatment with EBR-84, RGC death and the protein expression levels of β-catenin, cyclooxygenase-2 (COX-2), and vascular endothelial growth factor (VEGF) in rat retinas were examined. β-Catenin accumulated in the retinal ganglion cell layer (GCL) of NMDA-treated rats. EBR-84 (3.9, 7.8, and 15.6 g/kg) significantly attenuated the NMDA-induced RGC loss accompanying the reduction of β-catenin expression. Moreover, the expression levels of COX-2 and VEGF were decreased by EBR-84 in a dose-dependent manner. For the TWS119-treated rats, EBR-84 also ameliorated RGC loss and lowered the expression levels of β-catenin, COX-2, and VEGF. In vitro, EBR-84 increased the viability of NMDA-treated RGC-5 while decreased β-catenin expression. In conclusion, EBR-84 retarded ratretinopathy, and the β-catenin signaling pathway played an important role during this protective process.

Knockdown of lncRNA TP73-AS1 inhibits gastric cancer cell proliferation and invasion via the WNT/β-catenin signaling pathway

Long non-coding RNAs (lncRNAs) function as tumor suppressors or oncogenes in tumor development and progression. The purpose of the present study was to investigate the clinical significance and functional role of lncRNA TP73-AS1 in gastric cancer (GC). Reverse transcription-quantitative polymerase chain reaction analysis demonstrated that TP73-AS1 was significantly upregulated in GC tissues compared with adjacent normal tissues. The higher expression of TP73-AS1 was closely associated with lymph node metastasis and tumor-node-metastasis stage in patients with GC. Those patients with GC showing a higher expression of TP73-AS1 were predicted to have shorter disease-free survival and overall survival rates. The knockdown of TP73-AS1 was shown to markedly inhibit cell proliferation, cell colony formation and cell invasion. In addition, the downregulation of TP73-AS1 suppressed the expression of transcription factor 4 and β-catenin, which suggested that a decrease in TP73-AS1 suppressed the WNT/β-catenin signaling pathway in GC. Therefore, these results indicated that TP73-AS1 may be a target for GC treatment.

Wnt/β-catenin signaling stimulates the expression and synaptic clustering of the autism-associated Neuroligin 3 gene

Synaptic abnormalities have been described in individuals with autism spectrum disorders (ASD). The cell-adhesion molecule Neuroligin-3 (Nlgn3) has an essential role in the function and maturation of synapses and NLGN3 ASD-associated mutations disrupt hippocampal and cortical function. Here we show that Wnt/β-catenin signaling increases Nlgn3 mRNA and protein levels in HT22 mouse hippocampal cells and primary cultures of rat hippocampal neurons. We characterized the activity of mouse and rat Nlgn3 promoter constructs containing conserved putative T-cell factor/lymphoid enhancing factor (TCF/LEF)-binding elements (TBE) and found that their activity is significantly augmented in Wnt/β-catenin cell reporter assays. Chromatin immunoprecipitation (ChIP) assays and site-directed mutagenesis experiments revealed that endogenous β-catenin binds to novel TBE consensus sequences in the Nlgn3 promoter. Moreover, activation of the signaling cascade increased Nlgn3 clustering and co- localization with the scaffold PSD-95 protein in dendritic processes of primary neurons. Our results directly link Wnt/β-catenin signaling to the transcription of the Nlgn3 gene and support a functional role for the signaling pathway in the dysregulation of excitatory/inhibitory neuronal activity, as is observed in animal models of ASD.

Comprehensive assessment and meta-analysis of the association between CTNNB1 polymorphisms and cancer risk

CTNNB1, encoding β-catenin, is a well-known tumor-related gene in the wnt signaling pathway. It has been reported that CTNNB1 polymorphisms are associated with cancer risk. However, the data were inconsistent. In this article, we conducted a systematic review for the researches related to the association of single nucleotide polymorphisms (SNPs) in CTNNB1 with overall cancer risk. Meanwhile, a series of inclusion and exclusion criteria were set to select articles for quantitative analysis. Consequently, eight case-control studies containing 4388 cases and 4477 controls were included in a meta-analysis of four highly studied CTNNB1 SNPs (rs1798802 A/G, rs4135385 A/G, rs11564475 A/G, and rs2293303 C/T). The association between each SNP and cancer risk was estimated by calculating odds ratios (ORs) and their 95% confidence intervals (95%CIs). The results showed rs1798802 (AA compared with GG: P=0.044, OR=0.72) and rs2293303 (TT compared with CC: P=0.002, OR=2.86; recessive model: P=0.006, OR=2.91; T compared with C: P=0.004, OR=1.19) polymorphisms were associated with overall cancer risk. In stratified analysis, rs4135385 polymorphism was found to elevate the risk in Caucasian or in gastrointestinal cancer subgroup. Additionally, rs2293303 conferred to an increased cancer risk when the source of control groups was hospital-based (HB). In conclusion, the three CTNNB1 SNPs were suggested to have the potential to be novel biomarkers for risk prediction of cancer in overall population or some specific subgroups. Our study could provide research clues for further related investigations.

The crossroads of breast cancer progression: insights into the modulation of major signaling pathways

Cancer is the disease with highest public health impact in developed countries. Particularly, breast cancer has the highest incidence in women worldwide and the fifth highest mortality in the globe, imposing a significant social and economic burden to society. The disease has a complex heterogeneous etiology, being associated with several risk factors that range from lifestyle to age and family history. Breast cancer is usually classified according to the site of tumor occurrence and gene expression profiling. Although mutations in a few key genes, such as BRCA1 and BRCA2, are associated with high breast cancer risk, the large majority of breast cancer cases are related to mutated genes of low penetrance, which are frequently altered in the whole population. Therefore, understanding the molecular basis of breast cancer, including the several deregulated genes and related pathways linked to this pathology, is essential to ensure advances in early tumor detection and prevention. In this review, we outline key cellular pathways whose deregulation has been associated with breast cancer, leading to alterations in cell proliferation, apoptosis, and the delicate hormonal balance of breast tissue cells. Therefore, here we describe some potential breast cancer-related nodes and signaling concepts linked to the disease, which can be positively translated into novel therapeutic approaches and predictive biomarkers.

Inhibition of Wnt/β-Catenin pathway and Histone acetyltransferase activity by Rimonabant: a therapeutic target for colon cancer

In a high percentage (≥85%) of both sporadic and familial adenomatous polyposis forms of colorectal cancer (CRC), the inactivation of the APC tumor suppressor gene initiates tumor formation and modulates the Wnt/β-Catenin transduction pathways involved in the control of cell proliferation, adhesion and metastasis. Increasing evidence showed that the endocannabinoids control tumor growth and progression, both in vitro and in vivo. We evaluated the effect of Rimonabant, a Cannabinoid Receptor 1 (CB1) inverse agonist, on the Wnt/β-Catenin pathway in HCT116 and SW48 cell lines carrying the genetic profile of metastatic CRC poorly responsive to chemotherapies. In these models, Rimonabant inhibited the Wnt/β-Catenin canonical pathway and increased β-Catenin phosphorylation; in HCT116 cells, but not in SW48, the compound also triggered the Wnt/β-Catenin non canonical pathway activation through induction of Wnt5A and activation of CaMKII. The Rimonabant-induced downregulation of Wnt/β-Catenin target genes was partially ascribable to a direct inhibition of p300/KAT3B histone acetyltransferase, a coactivator of β-Catenin dependent gene regulation. Finally, in HCT116 xenografts, Rimonabant significantly reduced tumor growth and destabilized the nuclear localization of β-Catenin. Obtained data heavily supported the rationale for the use of cannabinoids in combined therapies for metastatic CRC harbouring activating mutations of β-Catenin.

Lithium Chloride Increases COX-2 Expression and PGE2 Production in a Human Granulosa-Lutein SVOG Cell Line Via a GSK-3β/β-Catenin Signaling Pathway

Lithium chloride (LiCl) is widely prescribed for the treatment of bipolar disorders and is associated with a higher incidence of reproductive adverse effects. Cyclooxygenase (COX)-2 and its derivative, prostaglandin E2 (PGE2), play regulatory roles in the human ovulatory process. Whether LiCl affects ovulation by regulating COX2 expression and PGE2 production in the human ovary is still largely unknown. The aim of this study was to investigate the effect of LiCl on the expression of COX-2 and production of PGE2 in human granulosa-lutein (hGL) cells, as well as the mechanisms underlying this effect. Both immortalized and primary hGL cells were used as research models. Using dual inhibition approaches, our results show that LiCl initiates the hGL cellular action by inhibiting the activity of glycogen synthase kinase-3β [GSK-3β (phosphorylation of GSK-3β)] and activation of extracellular signal-regulated kinase 1/2 (ERK1/2), but not by affecting protein kinase B or cAMP response element binding protein signaling. Additionally, the phosphorylation of GSK-3β, but not ERK1/2, resulted in the stabilization and nuclear localization of β-catenin. Furthermore, knockdown of either β-catenin or GSK-3β reversed the LiCl-induced upregulation of COX-2 expression. These results indicate that LiCl upregulates the expression of COX-2 and the subsequent production of PGE2 through the canonical GSK-3β/β-catenin signaling pathway in hGL cells.

SerpinB3 upregulates the Cyclooxygenase-2 / β-Catenin positive loop in colorectal cancer

Colorectal cancer is characterized by aberrant Cyclooxigenase-2 (COX-2) and β-Catenin pathways. Recently, the protease inhibitor SerpinB3 has been described overexpressed in more advanced stages of this tumor. Aim of the study was to explore the possible relationship between these molecules in this setting. We evaluated colorectal cancer specimens from 105 patients and a positive correlation between SerpinB3, COX-2 and β-Catenin expression was observed, with higher levels in tumor than in adjacent tissue. The highest levels were associated with pathologic parameters of poor prognosis, including vascular invasion, lymph node metastasis and perineural invasion. The molecular and protein profiles of COX-2 and β-Catenin were analyzed in cell lines with different expression of SerpinB3. In those with high expression of SerpinB3, COX-2 and β-Catenin were higher than in controls. Cells with high levels of SerpinB3 showed higher proliferation and invasion compared to controls. In conclusion, in colorectal cancer SerpinB3, COX-2 and β-Catenin are positively correlated and associated with more advanced tumor stage. The in vitro experimental results support a driving role of SerpinB3 in the upregulation of COX-2/ β-Catenin positive loop, associated with a more aggressive cellular phenotype.

Roles of Wnt Target Genes in the Journey of Cancer Stem Cells

The importance of Wnt/β-catenin signaling in cancer stem cells (CSCs) has been acknowledged; however, the mechanism through which it regulates the biological function of CSCs and promotes cancer progression remains elusive. Hence, to understand the intricate mechanism by which Wnt controls stemness, the specific downstream target genes of Wnt were established by analyzing the genetic signatures of multiple types of metastatic cancers based on gene set enrichment. By focusing on the molecular function of Wnt target genes, the biological roles of Wnt were interpreted in terms of CSC dynamics from initiation to metastasis. Wnt signaling participates in cancer initiation by generating CSCs from normal stem cells or non-CSCs and augmenting persistent growth at the primary region, which is resistant to anti-cancer therapy. Moreover, it assists CSCs in invading nearby tissues and in entering the blood stream, during which the negative feedback of the Wnt signaling pathway maintains CSCs in a dormant state that is suitable for survival. When CSCs arrive at distant organs, another burst of Wnt signaling induces CSCs to succeed in re-initiation and colonization. This comprehensive understanding of Wnt target genes provides a plausible explanation for how Wnt allows CSCs variation during cancer progression.

Aberrantly activated Cox-2 and Wnt signaling interact to maintain cancer stem cells in glioblastoma

Glioblastoma recurrence after aggressive therapy typically occurs within six months, and patients inevitably succumb to their disease. Tumor recurrence is driven by a subpopulation of cancer stem cells in glioblastoma (glioblastoma stem-like cells, GSCs), which exhibit resistance to cytotoxic therapies, compared to their non-stem-cell counterparts. Here, we show that the Cox-2 and Wnt signaling pathways are aberrantly activated in GSCs and interact to maintain the cancer stem cell identity. Cox-2 stimulates GSC self-renewal and proliferation through prostaglandin E2 (PGE2), which in turn activates the Wnt signaling pathway. Wnt signaling underlies PGE2-induced GSC self-renewal and independently directs GSC self-renewal and proliferation. Inhibition of PGE2 enhances the effect of temozolomide on GSCs, but affords only a modest survival advantage in a xenograft model in the setting of COX-independent Wnt activation. Our findings uncover an aberrant positive feedback interaction between the Cox-2/PGE2 and Wnt pathways that mediates the stem-like state in glioblastoma.

Microglia-glioblastoma interactions: New role for Wnt signaling

Glioblastoma, the most aggressive and fatal type of brain tumor, is capable of interacting with brain immune cells such as microglia, which contributes to the growth of these tumors. Various molecules, including growth factors and cytokines, have been identified as regulators of microglia-glioblastoma interaction. Recent studies suggest that the Wnt family of lipoglycoproteins plays an important role, not only in biological events during development, but also in cancer progression, and can be part of microglia recruitment to glioblastoma as well as of tumor growth and invasion. Here, we discuss recent interesting findings that support a role for Wnt signaling pathways in the microglia-glioblastoma crosstalk.

Prostaglandin E2-Induced COX-2 Expressions via EP2 and EP4 Signaling Pathways in Human LoVo Colon Cancer Cells

Metastasis is the most dangerous risk faced by patients with hereditary non-polyposis colon cancer (HNPCC). The expression of matrix metalloproteinases (MMPs) has been observed in several types of human cancers and regulates the efficacy of many therapies. Here, we show that treatment with various concentrations of prostaglandin E2 (PGE2; 0, 1, 5 or 10 μM) promotes the migration ability of the human LoVo colon cancer cell line. As demonstrated by mRNA and protein expression analyses, EP2 and EP4 are the major PGE2 receptors expressed on the LoVo cell membrane. The Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/Akt cell survival pathway was upregulated by EP2 and EP4 activation. Following the activation of the PI3K/Akt pathway, β-catenin translocated into the nucleus and triggered COX2 transcription via LEF-1 and TCF-4 and its subsequent translation. COX2 expression correlated with the elevation in the migration ability of LoVo cells. The experimental evidence shows a possible mechanism by which PGE2 induces cancer cell migration and further suggests PGE2 to be a potential therapeutic target in colon cancer metastasis. On inhibition of PGE2, in order to determine the downstream pathway, the levels of PI3K/Akt pathway were suppressed and the β-catenin expression was also modulated. Inhibition of EP2 and EP4 shows that PGE2 induces protein expression of COX-2 through EP2 and EP4 receptors in LoVo colon cancer cells.

Osteopontin Deficiency Suppresses Intestinal Tumor Development in Apc-Deficient Min Mice

Osteopontin (OPN) is a secreted phosphoglycoprotein, and is a transcriptional target of aberrant Wnt signaling. OPN is upregulated in human colon cancers, and is suggested to enhance cancer progression. In this study, the effect of deficiency of OPN on intestinal tumor development in Apc-deficient Min mice was investigated. At 16 weeks of age, the number of small intestinal polyps in Min/OPN(+/−) and Min/OPN(−/−) mice was lower than that of Min/OPN(+/+) mice. Colorectal tumor incidences and multiplicities in Min/OPN(+/−) and Min/OPN(−/−) mice were significantly lower than those in Min/OPN(+/+) mice, being 48% and 0.6 ± 0.8, 50% and 0.8 ± 0.9 vs. 80% and 1.6 ± 1.7, respectively. OPN expression in colorectal tumors was strongly upregulated in Min/OPN(+/+) compared to adjacent non-tumor parts, but was decreased in Min/OPN(+/−) and not detected in Min/OPN(−/−). Targets of OPN, matrix metalloproteinases (MMPs)-3, -9, and -13 were lowered by OPN deficiency. Macrophage marker F4/80 in colorectal tumors was also lowered by OPN deficiency. MMP-9 expression was observed in tumor cells and tumor-infiltrating neutrophils. These results indicate that induction of OPN by aberrant Wnt signaling could enhance colorectal tumor development in part by upregulation of MMP-3, -9, and -13 and infiltration of macrophage and neutrophils. Suppression of OPN expression could contribute to tumor prevention, but complete deficiency of OPN may cause some adverse effects.

Role of Wnt signalling in early pregnancy

The integration of a complex network of signalling molecules promotes implantation of the blastocyst and development of the placenta. These processes are crucial for a successful pregnancy and fetal growth and development. The signalling network involves both cell-cell and cell-extracellular matrix communication. The family of secreted glycoprotein ligands, the Wnts, plays a major role in regulating a wide range of biological processes, including embryonic development, cell fate, proliferation, migration, stem cell maintenance, tumour suppression, oncogenesis and tissue homeostasis. Recent studies have provided evidence that Wnt signalling pathways play an important role in reproductive tissues and in early pregnancy events. The focus of this review is to summarise our present knowledge of expression, regulation and function of the Wnt signalling pathways in early pregnancy events of human and other model systems, and its association with pathological conditions. Despite our recent progress, much remains to be learned about Wnt signalling in human reproduction. The advancement of knowledge in this area has applications in the reduction of infertility and the incidence and morbidity of gestational diseases.

Thymoquinone suppresses migration of LoVo human colon cancer cells by reducing prostaglandin E2 induced COX-2 activation

AIM

To identify potential anti-cancer constituents in natural extracts that inhibit cancer cell growth and migration.

METHODS

Our experiments used high dose thymoquinone (TQ) as an inhibitor to arrest LoVo (a human colon adenocarcinoma cell line) cancer cell growth, which was detected by cell proliferation assay and immunoblotting assay. Low dose TQ did not significantly reduce LoVo cancer cell growth. Cyclooxygenase 2 (COX-2) is an enzyme that is involved in the conversion of arachidonic acid into prostaglandin E2 (PGE2) in humans. PGE2 can promote COX-2 protein expression and tumor cell proliferation and was used as a control.

RESULTS

Our results showed that 20 μmol/L TQ significantly reduced human LoVo colon cancer cell proliferation. TQ treatment reduced the levels of p-PI3K, p-Akt, p-GSK3β, and β-catenin and thereby inhibited the downstream COX-2 expression. Results also showed that the reduction in COX-2 expression resulted in a reduction in PGE2 levels and the suppression of EP2 and EP4 activation. Further analysis showed that TG treatment inhibited the nuclear translocation of β-catenin in LoVo cancer cells. The levels of the cofactors LEF-1 and TCF-4 were also decreased in the nucleus following TQ treatment in a dose-dependent manner. Treatment with low dose TQ inhibited the COX-2 expression at the transcriptional level and the regulation of COX-2 expression efficiently reduced LoVo cell migration. The results were further verified in vivo by confirming the effects of TQ and/or PGE2 using tumor xenografts in nude mice.

CONCLUSION

TQ inhibits LoVo cancer cell growth and migration, and this result highlights the therapeutic advantage of using TQ in combination therapy against colorectal cancer.