Coxibs: pharmacology, toxicity and efficacy in cancer clinical trials

Tocotrienol suppresses colitis-associated cancer progression through TLR4 signaling in a mouse model of colorectal cancer

This study aimed to evaluate the preventive efficacy of tocotrienol in inhibiting the nuclear factor-kappa B (NF-κB) mediated inflammation pathways in colorectal cancer. We utilized the azoxymethane (AOM) and dextran sulfate sodium salt (DSS) to induce colitis-associated colorectal cancer (CAC) mice model. In generating a CAC model, mice were intraperitoneally injected with AOM at a concentration of 10 mg/kg body weight. Seven days after the AOM injection, mice drinking water containing 3 % DSS for 1 week, followed by a 2-week period of regular water. This cycle of DSS treatment (1-week 3 % DSS+2-week water) was repeated for two additional cycles. Mice were randomly divided into five groups (n = 20/group), including Blank group, Model group, three different dosages tocotrienol groups (Low dose group [50 mg/kg], Medium dose group [75 mg/kg], and High dose group [100 mg/kg]). The protective effects of tocotrienol were assessed using histological, flow cytometry, western blot and mouse Luminex assay. Compared with the blank group, expressions of toll-like receptor 4 (TLR4), myeloid differentiation protein 88 (MyD88), tumor necrosis factor receptor-associated factor 6 (TRAF-6), NF-κB, Interleukin (IL)-6 and tumor necrosis factor (TNF) -α were increased in model group, while IL-4 and IL-10 were decreased in model group (P<0.05). Tocotrienol prevented carcinogenesis and decreased the IL-6, TNF-α, MyD88, TLR4, TRAF-6 and NF-κB expression levels, compared with the model group (P<0.05). Compared with the model group, the expression of IL-10 was increased in medium dose group and high dose group (P<0.05). The protective effects of tocotrienol may be related to the inhibition of TLR4 /MyD88 /NF-κB mediated inflammatory signaling pathways. Therefore, the use of tocotrienol can improve the abnormal expression of cytokines in a mouse model of colorectal cancer and inhibit the occurrence and development of colorectal cancer.

Ruthenium-dihydroartemisinin complex: a promising new compound for colon cancer prevention via G1 cell cycle arrest, apoptotic induction, and adaptive immune regulation

BACKGROUND

Artemisinin (ART) and its derivatives are important antimalaria agents and have received increased attention due to their broad biomedical effects, such as anticancer and anti-inflammation activities. Recently, ruthenium-derived complexes have attracted considerable attention as their anticancer potentials were observed in preclinical and clinical studies.

METHODS

To explore an innovative approach in colorectal cancer (CRC) management, we synthesized ruthenium-dihydroartemisinin complex (D-Ru), a novel metal-based artemisinin derivative molecule, and investigated its anticancer, anti-inflammation, and adaptive immune regulatory properties.

RESULTS

Compared with its parent compound, ART, D-Ru showed stronger antiproliferative effects on the human CRC cell lines HCT-116 and HT-29. The cancer cell inhibition of D-Ru comprised G1 cell cycle arrest via the downregulation of cyclin A and the induction of apoptosis. ART and D-Ru downregulated the expressions of pro-inflammatory cytokines IL-1β, IL-6, and IL-8. Although ART and D-Ru did not suppress Treg cell differentiation, they significantly inhibited Th1 and Th17 cell differentiation.

CONCLUSIONS

Our results demonstrated that D-Ru, a novel ruthenium complexation of ART, remarkably enhanced its parent compound's anticancer action, while the anti-inflammatory potential was not compromised. The molecular mechanisms of action of D-Ru include inhibition of cancer cell growth via cell cycle arrest, induction of apoptosis, and anti-inflammation via regulation of adaptive immunity.

Crosstalk between P2Y receptors and cyclooxygenase activity in inflammation and tissue repair

The role of extracellular nucleotides as modulators of inflammation and cell stress is well established. One of the main actions of these molecules is mediated by the activation of purinergic receptors (P2) of the plasma membrane. P2 receptors can be classified according to two different structural families: P2X ionotropic ion channel receptors, and P2Y metabotropic G protein-coupled receptors. During inflammation, damaged cells release nucleotides and purinergic signaling occurs along the temporal pattern of the synthesis of pro-inflammatory and pro-resolving mediators by myeloid and lymphoid cells. In macrophages under pro-inflammatory conditions, the expression and activity of cyclooxygenase 2 significantly increases and enhances the circulating levels of prostaglandin E2 (PGE2), which exerts its effects both through specific plasma membrane receptors (EP1-EP4) and by activation of intracellular targets. Here we review the mechanisms involved in the crosstalk between PGE2 and P2Y receptors on macrophages, which is dependent on several isoforms of protein kinase C and protein kinase D1. Due to this crosstalk, a P2Y-dependent increase in calcium is blunted by PGE2 whereas, under these conditions, macrophages exhibit reduced migratory capacity along with enhanced phagocytosis, which contributes to the modulation of the inflammatory response and tissue repair.

Parecoxib decreases cellular growth and Bcl-2 protein levels in primary cultures of keloid fibroblasts

Keloids seem to overexpress cyclo-oxygenase-2 (COX-2), suggesting a role in its deregulated pathway in inducing an altered epithelial-mesenchymal interaction, which may be responsible for the overgrowth of dermal components resulting in scars or keloid lesions. This study aimed to evaluate the effect of Parecoxib, a COX-2 inhibitor, on cell growth in fibroblast primary cultures obtained from human keloid tissues. Tissue explants were obtained from patients who underwent intralesional excision of untreated keloids; central fractions were isolated from keloid tissues and used for establishing distinct primary cultures. Appropriate aliquots of Parecoxib, a COX-2 inhibitor were diluted to obtain the concentration used in the experimental protocols in vitro (1, 10 or 100 μM). Treatment with Parecoxib (at all concentrations) caused a significant decrease in cellular growth from 24 hours onwards, and with a maximum at 72 hours (P < .02). Moreover, at 72 hours Parecoxib significantly reduced cellular vitality. Parecoxib treatment also induced an increase in fragmented nuclei with a maximum effect at 100 μM and a significant decrease in Bcl-2 and an increase in activated caspase-3 protein levels at 72 hours compared with control untreated cultures. Our findings suggest a potential use of the COX-2 inhibitor, Parecoxib, as the therapy for keloids.

Ginseng berry concentrate prevents colon cancer via cell cycle, apoptosis regulation, and inflammation-linked Th17 cell differentiation

The Asian ginseng root (Panax ginseng C.A. Meyer) is a very commonly used herbal medicine worldwide. Ginseng fruit, including the berry (or pulp) and seed, is also valuable for several health conditions including immunostimulation and cancer chemoprevention. In this study, the anticancer and anti-proliferative effects of the extracts of ginseng berry and seed were evaluated. The ginsenosides in the ginseng berry concentrate (GBC) and ginseng seed extract (GSE) were analyzed. We then evaluated their anti-colorectal cancer potentials, including antiproliferation, cell cycle arrest, and apoptotic induction. Further investigation consisted of the berry's adaptive immune responses, such as the actions on the differentiation of T helper cells Treg, Th1, and Th17. The major constituents in GBC were ginsenosides Re and Rd, which can be compared to those in the root. The GBC significantly inhibited colon cancer cell growth, and its anti-proliferative effect involved mechanisms including G2/M cell cycle arrest via upregulation of cyclin A and induction of apoptosis via regulation of apoptotic related gene expressions. GBC also downregulated the expressions of pro-inflammatory cytokine genes. For the adaptive immune responses, GBC did not influence Th1 and Treg cell differentiation but significantly inhibited Th17 cell differentiation and thus regulated the balance of Th17/Treg for adaptive immunity. Although no ginsenoside was detected in the GSE, interestingly, it obviously enhanced colon cancer cell proliferation with the underlined details to be determined. Our results suggested that GBC is a promising dietary supplement for cancer chemoprevention and immunomodulation.

Ginseng berry polysaccharides on inflammation-associated colon cancer: inhibiting T-cell differentiation, promoting apoptosis, and enhancing the effects of 5-fluorouracil

Background

Ginseng is a commonly used herbal medicine in treating various medical conditions. Chronic gut inflammation is a recognized factor for the development of colorectal cancer (CRC). In this project, Asian ginseng berry polysaccharide preparations were used to assess their effects on CRC and related immune regulation mechanisms.

Methods

Ginseng berry polysaccharide extract (GBPE) and purified ginseng berry polysaccharide portion (GBPP) were used to evaluate their activities on human HCT-116 and HT-29 CRC cell proliferation. Interleukin-8 secretion analysis was performed on HT-29 cells. Naive CD4 cell isolation and T-helper cell differentiation were performed and determined using flow cytometry for Th1 and Treg in addition to cell cycle and apoptotic investigation.

Results

GBPE and GBPP significantly inhibited interleukin-8 secretion and cancer cell proliferation, inhibited CD4⁺IFN-γ⁺ cell (Th1) differentiation, and decreased CD4⁺FoxP3⁺ cell (Treg) differentiation. Compared to the GBPE, GBPP showed more potent antiinflammatory activities on the malignant cells. This is consistent with the observation that GBPP can also inhibit Th1-cell differentiation better, suggesting that it has an important role in antiinflammation, whereas Treg cells hinder the body's immune response against malignancies. Supported by cell cycle and apoptosis data, GBPE and GBPP, at various degrees, remarkably enhanced the anticancer activities of 5-fluorouracil.

Conclusion

Data from this project suggested that Asian ginseng berry potentially has clinical utility in managing enteric inflammation and suppressing CRC through immunomodulation mechanisms.

Post-translational modifications of prostaglandin-endoperoxide synthase 2 in colorectal cancer: An update

The biosynthesis of prostanoids is involved in both physiological and pathological processes. The expression of prostaglandin-endoperoxide synthase 2 (PTGS2; also known as COX-2) has been traditionally associated to the onset of several pathologies, from inflammation to cardiovascular, gastrointestinal and oncologic events. For this reason, the search of selective PTGS2 inhibitors has been a focus for therapeutic interventions. In addition to the classic non-steroidal anti-inflammatory drugs, selective and specific PTGS2 inhibitors, termed coxibs, have been generated and widely used. PTGS2 activity is less restrictive in terms of substrate specificity than the homeostatic counterpart PTGS1, and it accounts for the elevated prostanoid synthesis that accompanies several pathologies. The main regulation of PTGS2 occurs at the transcription level. In addition to this, the stability of the mRNA is finely regulated through the interaction with several cytoplasmic elements, ranging from specific microRNAs to proteins that control mRNA degradation. Moreover, the protein has been recognized to be the substrate for several post-translational modifications that affect both the enzyme activity and the targeting for degradation via proteasomal and non-proteasomal mechanisms. Among these modifications, phosphorylation, glycosylation and covalent modifications by reactive lipidic intermediates and by free radicals associated to the pro-inflammatory condition appear to be the main changes. Identification of these post-translational modifications is relevant to better understand the role of PTGS2 in several pathologies and to establish a correct analysis of the potential function of this protein in diseases progress. Finally, these modifications can be used as biomarkers to establish correlations with other parameters, including the immunomodulation dependent on molecular pathological epidemiology determinants, which may provide a better frame for potential therapeutic interventions.

Multiple Effects of Ginseng Berry Polysaccharides: Plasma Cholesterol Level Reduction and Enteric Neoplasm Prevention

The root of Asian ginseng (Panax ginseng C.A. Meyer) has been used for centuries in Oriental medicine to improve general well-being and to relieve various medical conditions. It is commonly understood that ginsenosides are responsible for the pharmacological activities of ginseng. Compared to the root of ginseng, studies on the berry are considerably limited. In this study, we evaluated the effects of polysaccharides from Asian ginseng berries on plasma lipid levels, chemically-induced enteric inflammation and neoplasm, and cancer chemoprevention in different experimental models. We tested two polysaccharide preparations: regular ginseng berry polysaccharide extract (GBPE) and ginseng berry polysaccharide portion (GBPP, removed MV [Formula: see text]). We first observed that both oral GBPE and oral GBPP significantly reduced plasma cholesterol and triglycerides levels in a dose-related manner in ob/ob mice, without obvious body weight changes. Then, in AOM/DSS-induced acute colitis mice, GBPE and GBPP significantly ameliorated the increased gut disease activity index and inhibited the reduction of the colon length. Further, the berry polysaccharides significantly suppressed chemically-induced pro-inflammatory cytokine levels. This is consistent with the observation that GBPE and GBPP attenuated tumorigenesis in mice by significantly and dose-dependently reducing tumor load. Finally, in vitro HCT-116 and HT-29 human colon cancer cells were used. While these berry preparations had better antiproliferation effects on the HCT-116 than the HT-29 cells, the GBPE had significantly stronger inhibitory effects than GBPP. The observed in vitro GBPE's effect could contribute to the actions of its small-molecule non-polysaccharide compounds due to their direct antiproliferative activities. Results obtained from the present study suggest that ginseng berry polysaccharides may have a therapeutic role in the management of high lipid levels, enteric inflammation, and colon malignancies.

Interleukin-10 and prostaglandin E2 have complementary but distinct suppressive effects on Toll-like receptor-mediated dendritic cell activation in ovarian carcinoma

Dendritic cells (DC) have the potential to instigate a tumour-specific immune response, but their ability to prime naïve lymphocytes depends on their activation status. Thus, for tumour immunotherapy to be effective, the provision of appropriate DC activation stimuli such as Toll-like receptor (TLR) agonists is crucial in order to overcome immunosuppression associated with the tumour microenvironment. To address this, we investigated how ovarian carcinoma (OC)-associated ascites impedes activation of DC by TLR agonists. Our results show that ascites reduces the TLR-mediated up-regulation of CD86 and partially inhibits the production of the pro-inflammatory cytokines interleukin 6 (IL-6), IL-12 and tumour necrosis factor α (TNFα) in monocyte-derived DC from healthy controls. We further observe an impaired T cell stimulatory capacity of DC upon activation with TLR agonists in the presence of ascites, indicating that their functionality is affected by the immunosuppressive factors. We identify IL-10 and prostaglandin E2 (PGE₂) as the pivotal immunosuppressive components in OC-associated ascites compromising TLR-mediated DC activation. Interestingly, IL-10 is present in both ascites from patients with malignant OC and in peritoneal fluid from patients with benign ovarian conditions and both fluids have similar ability to reduce TLR-mediated DC activation. However, depletion of IL-10 from ascites revealed that the presence of paracrine IL-10 is not crucial for ascites-mediated suppression of DC activation in response to TLR activation. Unlike IL-10, PGE₂ is absent from peritoneal fluid of patients with benign conditions and selectively reduces TNFα induction in response to TLR-mediated activation in the presence of OC-associated ascites. Our study highlights PGE₂ as an immunosuppressive component of the malignant OC microenvironment rendering PGE₂ a potentially important target for immunotherapy in OC.

Ibuprofen arginate retains eNOS substrate activity and reverses endothelial dysfunction: implications for the COX-2/ADMA axis

Nonsteroidal antiinflammatory drugs, including ibuprofen, are among the most commonly used medications and produce their antiinflammatory effects by blocking cyclooxygenase (COX)-2. Their use is associated with increased risk of heart attacks caused by blocking COX-2 in the vasculature and/or kidney, with our recent work implicating the endogenous NOS inhibitor asymmetric dimethylarginine (ADMA), a cardiotoxic hormone whose effects can be prevented by l-arginine. The ibuprofen salt ibuprofen arginate (Spididol) was created to increase solubility but we suggest that it could also augment the NO pathway through codelivery of arginine. Here we investigated the idea that ibuprofen arginate can act to simultaneously inhibit COX-2 and preserve the NO pathway. Ibuprofen arginate functioned similarly to ibuprofen sodium for inhibition of mouse/human COX-2, but only ibuprofen arginate served as a substrate for NOS. Ibuprofen arginate but not ibuprofen sodium also reversed the inhibitory effects of ADMA and N^G-nitro-l-arginine methyl ester on inducible NOS (macrophages) and endothelial NOS in vitro (aorta) and in vivo (blood pressure). These observations show that ibuprofen arginate provides, in one preparation, a COX-2 inhibitor and NOS substrate that could act to negate the harmful cardiovascular consequences mediated by blocking renal COX-2 and increased ADMA. While remarkably simple, our findings are potentially game-changing in the nonsteroidal antiinflammatory drug arena.-Kirkby, N. S., Tesfai, A., Ahmetaj-Shala, B., Gashaw, H. H., Sampaio, W., Etelvino, G., Leão, N. M., Santos, R. A., Mitchell, J. A. Ibuprofen arginate retains eNOS substrate activity and reverses endothelial dysfunction: implications for the COX-2/ADMA axis.

Flavonoids Extracted from Licorice Prevents Colitis-Associated Carcinogenesis in AOM/DSS Mouse Model

Inflammatory bowel disease (IBD) is generally considered as a major risk factor in the progression of colitis-associated carcinogenesis (CAC). Thus, it is well accepted that ameliorating inflammation creates a potential to achieve an inhibitory effect on CAC. Licorice flavonoids (LFs) possess strong anti-inflammatory activity, making it possible to investigate its pharmacologic role in suppressing CAC. The purpose of the present study was to evaluate the anti-tumor potential of LFs, and further explore the underlying mechanisms. Firstly, an azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced mouse model was established and administered with or without LFs for 10 weeks, and then the severity of CAC was examined macroscopically and histologically. Subsequently, the effects of LFs on expression of proteins associated with apoptosis and proliferation, levels of inflammatory cytokine, expression of phosphorylated-Janus kinases 2 (p-Jak2) and phosphorylated-signal transducer and activator of transcription 3 (p-Stat3), and activation of nuclear factor-κB (NFκB) and P53 were assessed. We found that LFs could significantly reduce tumorigenesis induced by AOM/DSS. Further study revealed that LFs treatment substantially reduced activation of NFκB and P53, and subsequently suppressed production of inflammatory cytokines and phosphorylation of Jak2 and Stat3 in AOM/DSS-induced mice. Taken together, LFs treatment alleviated AOM/DSS induced CAC via P53 and NFκB/IL-6/Jak2/Stat3 pathways, highlighting the potential of LFs in preventing CAC.

A small amount of cyclooxygenase 2 (COX2) is constitutively expressed in platelets

Cyclooxygenase (COX) is the rate-limiting enzyme in conversion of arachidonic acid to prostanoids, and has two isoforms, COX1 and COX2, which share ~65% amino acid homology. COX1 is universally expressed in many cell types including platelets; however, expression of COX2 is known to be more limited. We examined expression of COX2 mRNA and protein in platelets and platelet-derived microparticles (MPs); using quantitative RT-PCR, immunostaining, and Western blotting. We have detected a significant amount of COX2 in platelets, both at mRNA and protein levels. We found that COX1/COX2 mRNA and protein ratios in platelets were 370:1 and 17:1, respectively. Expression level of COX2 in platelets was less than COX1, but comparable to the expression of COX2 in malignant epithelial cells. Considering the important role of COX2 in tumorigenesis and thrombosis, and the large number of circulating platelets, we propose that platelet COX2 may play an important role in physiologic and pathologic conditions.

Palmatine from Mahonia bealei attenuates gut tumorigenesis in ApcMin/+ mice via inhibition of inflammatory cytokines

Mahonia bealei is a Chinese folk medicine used to treat various ailments, in particular gastrointestinal inflammation‑related illnesses, and palmatine is one of its active constituents. In this study, ApcMin/+ mice, a genetically engineered model, were used to investigate the effects of palmatine on the initiation and progression of gut inflammation and tumorigenesis enhanced by a high‑fat diet. The in vitro antiproliferation and anti‑inflammation effects of palmatine were evaluated on HT‑29 and SW‑480 human colorectal cancer cell lines. The concentration‑related antiproliferative effects of palmatine on both cell lines (P<0.01) were observed. Palmatine significantly inhibited lipopolysaccharide‑induced increase in cytokine interleukin (IL)‑8 levels in the HT‑29 cells (P<0.01). In the in vivo studies with ApcMin/+ mice, after 10 or 20 mg/kg/day oral palmatine treatment, tumor numbers were significantly reduced in the small intestine and colon in a dose‑dependent manner (P<0.01 compared with the model group). The results were supported by tumor distribution data, body weight changes and organ index. The effect on survival was also dose‑dependent. Both the low‑ and high‑dose palmatine treatments significantly increased the life span of the mice (P<0.01). The gut histology from the model group showed a prominent adenomatous change along with inflammatory lesions. With palmatine treatment, however, the dysplastic changes were greatly reduced in the small intestine and colon tissue. Reverse transcription‑quantitative polymerase chain reaction analysis of interleukin (IL)‑1α, IL1‑β, IL‑8, granulocyte‑colony stimulating factor and granulocyte macrophage colony‑stimulating factor in the gut tissue showed that these inflammatory cytokines were reduced significantly following treatment (all P<0.01); serum cytokine levels were also decreased. Data suggests that palmatine has a clinical value in colorectal cancer therapeutics, and this action is likely linked to the inhibition of inflammatory cytokines.

Up-regulation of HB-EGF by the COX-2/PGE2 signaling associates with the cisplatin resistance and tumor recurrence of advanced HNSCC

OBJECTIVES

When treating advanced HNSCC, a cisplatin-based systemic regimen benefit patient survival. However, chemoresistance will greatly reduce the effectiveness of this approach. The identification of molecules that contribute to cisplatin resistance may potentially improve the survival. Both HB-EGF and COX-2 have been reported to increase cisplatin-resistance. Here, we have focused on the regulation of HB-EGF/COX-2 and their roles in cisplatin resistance.

MATERIALS AND METHODS

IHC staining was used to measure the expression levels of HB-EGF and COX-2 on the tissue microarray from 43 tissue samples of patients with advanced HNSCC. siRNA, western blot and qRT-PCR were used to dissect the regulation between EGF, Akt, COX-2, PGE2, and cisplatin sensitivity. The correlation between HB-EGF, COX2 and HNSCC progression was analyzed by the receiver operating characteristic (ROC) curve and Kaplan-Meier disease free survival.

RESULTS

Patients of advanced HNSCC patients with increased HB-EGF and COX-2 expression have higher tumor recurrent rates that was related to cisplatin resistance. The resistance was mediated via an increased expression of HB-EGF and COX-2. The activation of Akt by either EGF or areca nut extract were able to upregulate COX-2, which would increase the expression of HB-EGF in a PGE2 dependent manner. Inhibition and knockdown of COX-2 resulted in a decrease in HB-EGF. In the tissue samples from HNSCC patients, there was a significant positive correlation between the expression of COX-2 and HB-EGF.

CONCLUSION

Our results suggested that COX-2 and HB-EGF are important in development of HNSCC cisplatin resistance. These findings may help the development of new strategies for overcoming cisplatin resistance.

Systematic study of constitutive cyclooxygenase-2 expression: Role of NF-κB and NFAT transcriptional pathways

Cyclooxygenase-2 (COX-2) is an inducible enzyme that drives inflammation and is the therapeutic target for widely used nonsteroidal antiinflammatory drugs (NSAIDs). However, COX-2 is also constitutively expressed, in the absence of overt inflammation, with a specific tissue distribution that includes the kidney, gastrointestinal tract, brain, and thymus. Constitutive COX-2 expression is therapeutically important because NSAIDs cause cardiovascular and renal side effects in otherwise healthy individuals. These side effects are now of major concern globally. However, the pathways driving constitutive COX-2 expression remain poorly understood. Here we show that in the kidney and other sites, constitutive COX-2 expression is a sterile response, independent of commensal microorganisms and not associated with activity of the inflammatory transcription factor NF-κB. Instead, COX-2 expression in the kidney but not other regions colocalized with nuclear factor of activated T cells (NFAT) transcription factor activity and was sensitive to inhibition of calcineurin-dependent NFAT activation. However, calcineurin/NFAT regulation did not contribute to constitutive expression elsewhere or to inflammatory COX-2 induction at any site. These data address the mechanisms driving constitutive COX-2 and suggest that by targeting transcription it may be possible to develop antiinflammatory therapies that spare the constitutive expression necessary for normal homeostatic functions, including those important to the cardiovascular-renal system.

Duodenal adenoma surveillance in patients with familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is a hereditary disorder caused by Adenomatous Polyposis Gene mutations that lead to the development of colorectal polyps with great malignant risk throughout life. Moreover, numerous extracolonic manifestations incorporate different clinical features to produce varied individual phenotypes. Among them, the occurrence of duodenal adenomatous polyps is considered an almost inevitable event, and their incidence rates increase as a patient’s age advances. Although the majority of patients exhibit different grades of duodenal adenomatosis as they age, only a small proportion (1%-5%) of patients will ultimately develop duodenal carcinoma. Within this context, the aim of the present study was to review the data regarding the epidemiology, classification, genetic features, endoscopic features, carcinogenesis, surveillance and management of duodenal polyps in patients with FAP.

Novel insights into the regulation of cyclooxygenase-2 expression by platelet-cancer cell cross-talk

Platelets are activated by the interaction with cancer cells and release enhanced levels of lipid mediators [such as thromboxane (TX)A2 and prostaglandin (PG)E2, generated from arachidonic acid (AA) by the activity of cyclooxygenase (COX)-1], granule content, including ADP and growth factors, chemokines, proteases and Wnt proteins. Moreover, activated platelets shed different vesicles, such as microparticles (MPs) and exosomes (rich in genetic material such as mRNAs and miRNAs). These platelet-derived products induce several phenotypic changes in cancer cells which confer high metastatic capacity. A central event involves an aberrant expression of COX-2 which influences cell-cycle progression and contribute to the acquisition of a cell migratory phenotype through the induction of epithelial mesenchymal transition genes and down-regulation of E-cadherin expression. The identification of novel molecular determinants involved in the cross-talk between platelets and cancer cells has led to identify novel targets for anti-cancer drug development.

American ginseng significantly reduced the progression of high-fat-diet-enhanced colon carcinogenesis in Apc (Min/+) mice

BACKGROUND

Colorectal cancer (CRC) is a leading cause of death worldwide. Chronic gut inflammation is recognized as a risk factor for tumor development, including CRC. American ginseng is a very commonly used ginseng species in the West.

METHODS

A genetically engineered Apc (Min/+) mouse model was used in this study. We analyzed the saponin composition of American ginseng used in this project, and evaluated its effects on the progression of high-fat-diet-enhanced CRC carcinogenesis.

RESULTS

After oral ginseng administration (10-20 mg/kg/d for up to 32 wk), experimental data showed that, compared with the untreated mice, ginseng very significantly reduced tumor initiation and progression in both the small intestine (including the proximal end, middle end, and distal end) and the colon (all p < 0.01). This tumor number reduction was more obvious in those mice treated with a low dose of ginseng. The tumor multiplicity data were supported by body weight changes and gut tissue histology examinations. In addition, quantitative real-time polymerase chain reaction analysis showed that compared with the untreated group, ginseng very significantly reduced the gene expression of inflammatory cytokines, including interleukin-1α (IL-1α), IL-1β, IL-6, tumor necrosis factor-α, granulocyte-colony stimulating factor, and granulocyte-macrophage colony-stimulating factor in both the small intestine and the colon (all p < 0.01).

CONCLUSION

Further studies are needed to link our observed effects to the actions of the gut microbiome in converting the parent ginsenosides to bioactive ginseng metabolites. Our data suggest that American ginseng may have potential value in CRC chemoprevention.

ABC transporters and neuroblastoma

Neuroblastoma is the most common cancer of infancy and accounts for 15% of all pediatric oncology deaths. Survival rates of high-risk neuroblastoma remain less than 50%, with amplification of the MYCN oncogene the most important aberration associated with poor outcome. Direct transcriptional targets of MYCN include a number of ATP-binding cassette (ABC) transporters, of which ABCC1 (MRP1), ABCC3 (MRP3), and ABCC4 (MRP4) are the best characterized. These three transporter genes have been shown to be strongly prognostic of neuroblastoma outcome in primary untreated neuroblastoma. In addition to their ability to efflux a number of chemotherapeutic drugs, evidence suggests that these transporters also contribute to neuroblastoma outcome independent of any role in cytotoxic drug efflux. Endogenous substrates of ABCC1 and ABCC4 that may be potential candidates affecting neuroblastoma biology include molecules such as prostaglandins and leukotrienes. These bioactive lipid mediators have the ability to influence biological processes contributing to cancer initiation and progression, such as angiogenesis, cell signaling, inflammation, proliferation, and migration and invasion. ABCC1 and ABCC4 are thus potential targets for therapeutic suppression in high-risk neuroblastoma, and recently developed small-molecule inhibitors may be an effective strategy in treating aggressive forms of this cancer, as well as other cancers that express high levels of these transporters.

Leukotriene signaling in the extinct human subspecies Homo denisovan and Homo neanderthalensis. Structural and functional comparison with Homo sapiens

Mammalian lipoxygenases (LOXs) have been implicated in cell differentiation and in the biosynthesis of pro- and anti-inflammatory lipid mediators. The initial draft sequence of the Homo neanderthalensis genome (coverage of 1.3-fold) suggested defective leukotriene signaling in this archaic human subspecies since expression of essential proteins appeared to be corrupted. Meanwhile high quality genomic sequence data became available for two extinct human subspecies (H. neanderthalensis, Homo denisovan) and completion of the human 1000 genome project provided a comprehensive database characterizing the genetic variability of the human genome. For this study we extracted the nucleotide sequences of selected eicosanoid relevant genes (ALOX5, ALOX15, ALOX12, ALOX15B, ALOX12B, ALOXE3, COX1, COX2, LTA4H, LTC4S, ALOX5AP, CYSLTR1, CYSLTR2, BLTR1, BLTR2) from the corresponding databases. Comparison of the deduced amino acid sequences in connection with site-directed mutagenesis studies and structural modeling suggested that the major enzymes and receptors of leukotriene signaling as well as the two cyclooxygenase isoforms were fully functional in these two extinct human subspecies.

American ginseng attenuates azoxymethane/dextran sodium sulfate-induced colon carcinogenesis in mice

BACKGROUND

Colorectal cancer is a leading cause of cancer-related death, and inflammatory bowel disease is a risk factor for this malignancy. We previously reported colon cancer chemoprevention potential using American ginseng (AG) in a xenograft mice model. However, the nude mouse model is not a gut-specific colon carcinogenesis animal model.

METHODS

In this study, an experimental colitis and colitis-associated colorectal carcinogenesis mouse model, chemically induced by azoxymethane/dextran sodium sulfate (DSS) was established and the effects of oral AG were evaluated. The contents of representative ginseng saponins in the extract were determined.

RESULTS

AG significantly reduced experimental colitis measured by the disease activity index scores. This suppression of the experimental colitis was not only evident during DSS treatment, but also very obvious after the cessation of DSS, suggesting that the ginseng significantly promoted recovery from the colitis. Consistent with the anti-inflammation data, we showed that ginseng very significantly attenuated azoxymethane/DSS-induced colon carcinogenesis by reducing the colon tumor number and tumor load. The ginseng also effectively suppressed DSS-induced proinflammatory cytokines activation using an enzyme-linked immunosorbent assay array, in which 12 proinflammatory cytokine levels were assessed, and this effect was supported subsequently by real-time polymerase chain reaction data.

CONCLUSION

AG, as a candidate of botanical-based colon cancer chemoprevention, should be further investigated for its potential clinical utility.

Reversible suppression of cyclooxygenase 2 (COX-2) expression in vivo by inducible RNA interference

Prostaglandin-endoperoxide synthase 2 (PTGS2), also known as cyclooxygenase 2 (COX-2), plays a critical role in many normal physiological functions and modulates a variety of pathological conditions. The ability to turn endogenous COX-2 on and off in a reversible fashion, at specific times and in specific cell types, would be a powerful tool in determining its role in many contexts. To achieve this goal, we took advantage of a recently developed RNA interference system in mice. An shRNA targeting the Cox2 mRNA 3′untranslated region was inserted into a microRNA expression cassette, under the control of a tetracycline response element (TRE) promoter. Transgenic mice containing the COX-2-shRNA were crossed with mice encoding a CAG promoter-driven reverse tetracycline transactivator, which activates the TRE promoter in the presence of tetracycline/doxycycline. To facilitate testing the system, we generated a knockin reporter mouse in which the firefly luciferase gene replaces the Cox2 coding region. Cox2 promoter activation in cultured cells from triple transgenic mice containing the luciferase allele, the shRNA and the transactivator transgene resulted in robust luciferase and COX-2 expression that was reversibly down-regulated by doxycycline administration. In vivo, using a skin inflammation-model, both luciferase and COX-2 expression were inhibited over 80% in mice that received doxycycline in their diet, leading to a significant reduction of infiltrating leukocytes. In summary, using inducible RNA interference to target COX-2 expression, we demonstrate potent, reversible Cox2 gene silencing in vivo. This system should provide a valuable tool to analyze cell type-specific roles for COX-2.

Celecoxib increases miR-222 while deterring aromatase-expressing breast tumor growth in mice

Background

Breast cancer is one of the most deadly diseases in women. Inhibiting the synthesis of estrogen is effective in treating patients with estrogen-responsive breast cancer. Previous studies have demonstrated that use of cyclooxygenase (COX) inhibitors is associated with reduced breast cancer risk.

Methods

In the present study, we employed an established mouse model for postmenopausal breast cancer to evaluate the potential mechanisms of the COX-2 inhibitor celecoxib. Aromatase-expressing MCF-7 cells were transplanted into ovariectomized athymic mice. The animals were given celecoxib at 1500 ppm or aspirin at 200 ppm by oral administration with androstenedione injection.

Results

Our results showed that both COX inhibitors could suppress the cancer xenograft growth without changing the plasma estrogen level. Protein expression of ERα, COX-2, Cyclin A, and Bcl-xL were reduced in celecoxib-treated tumor samples, whereas only Bcl-xL expression was suppressed in those treated with aspirin. Among the breast cancer-related miRNAs, miR-222 expression was elevated in samples treated with celecoxib. Further studies in culture cells verified that the increase in miR-222 expression might contribute to ERα downregulation but not the growth deterrence of cells.

Conclusion

Overall, this study suggested that both celecoxib and aspirin could prevent breast cancer growth by regulating proteins in the cell cycle and apoptosis without blocking estrogen synthesis. Besides, celecoxib might affect miR expression in an undesirable fashion.

Pathway analysis for drug repositioning based on public database mining

Sixteen FDA-approved drugs were investigated to elucidate their mechanisms of action (MOAs) and clinical functions by pathway analysis based on retrieved drug targets interacting with or affected by the investigated drugs. Protein and gene targets and associated pathways were obtained by data-mining of public databases including the MMDB, PubChem BioAssay, GEO DataSets, and the BioSystems databases. Entrez E-Utilities were applied, and in-house Ruby scripts were developed for data retrieval and pathway analysis to identify and evaluate relevant pathways common to the retrieved drug targets. Pathways pertinent to clinical uses or MOAs were obtained for most drugs. Interestingly, some drugs identified pathways responsible for other diseases than their current therapeutic uses, and these pathways were verified retrospectively by in vitro tests, in vivo tests, or clinical trials. The pathway enrichment analysis based on drug target information from public databases could provide a novel approach for elucidating drug MOAs and repositioning, therefore benefiting the discovery of new therapeutic treatments for diseases.

Management of cancer pain: 1. Wider implications of orthodox analgesics

In this review, the first of two parts, we first provide an overview of the orthodox analgesics used commonly against cancer pain. Then, we examine in more detail the emerging evidence for the potential impact of analgesic use on cancer risk and disease progression. Increasing findings suggest that long-term use of nonsteroidal anti-inflammatory drugs, particularly aspirin, may reduce cancer occurrence. However, acetaminophen may raise the risk of some hematological malignancies. Drugs acting upon receptors of gamma-aminobutyric acid (GABA) and GABA “mimetics” (eg, gabapentin) appear generally safe for cancer patients, but there is some evidence of potential carcinogenicity. Some barbiturates appear to slightly raise cancer risks and can affect cancer cell behavior in vitro. For cannabis, studies suggest an increased risk of squamous cell carcinoma of the tongue, larynx, and possibly lung. Morphine may stimulate human microvascular endothelial cell proliferation and angiogenesis; it is not clear whether this might cause harm or produce benefit. The opioid, fentanyl, may promote growth in some tumor cell lines. Opium itself is an emerging risk factor for gastric adenocarcinoma and possibly cancers of the esophagus, bladder, larynx, and lung. It is concluded that analgesics currently prescribed for cancer pain can significantly affect the cancer process itself. More futuristically, several ion channels are being targeted with novel analgesics, but many of these are also involved in primary and/or secondary tumorigenesis. Further studies are needed to elucidate possible cellular and molecular effects of orthodox analgesics and their possible long-term impact, both positive and negative, and thus enable the best possible clinical gain for cancer patients.

Interactions between diet, lifestyle and IL10, IL1B, and PTGS2/COX-2 gene polymorphisms in relation to risk of colorectal cancer in a prospective Danish case-cohort study

Background & Aims

Diet contributes to colorectal cancer development and may be potentially modified. We wanted to identify the biological mechanisms underlying colorectal carcinogenesis by assessment of diet-gene interactions.

Methods

The polymorphisms IL10 C-592A (rs1800872), C-rs3024505-T, IL1b C-3737T (rs4848306), G-1464C (rs1143623), T-31C (rs1143627) and PTGS2 (encoding COX-2) A-1195G (rs689466), G-765C (rs20417), and T8473C (rs5275) were assessed in relation to risk of colorectal cancer (CRC) and interaction with diet (red meat, fish, fibre, cereals, fruit and vegetables) and lifestyle (non-steroid-anti-inflammatory drug use and smoking status) was assessed in a nested case-cohort study of nine hundred and seventy CRC cases and 1789 randomly selected participants from a prospective study of 57,053 persons.

Results

IL1b C-3737T, G-1464C and PTGS2 T8473C variant genotypes were associated with risk of CRC compared to the homozygous wildtype genotype (IRR=0.81, 95%CI: 0.68-0.97, p=0.02, and IRR=1.22, 95%CI: 1.04-1.44, p=0.02, IRR=0.75, 95%CI: 0.57-0.99, p=0.04, respectively). Interactions were found between diet and IL10 rs3024505 (P-value for interaction (P_int); meat=0.04, fish=0.007, fibre=0.0008, vegetables=0.0005), C-592A (P_int; fibre=0.025), IL1b C-3737T (P_int; vegetables=0.030, NSAID use=0.040) and PTGS2 genotypes G-765C (P_int; meat=0.006, fibre=0.0003, fruit 0.004), and T8473C (P_int; meat 0.049, fruit=0.03) and A-1195G (P_int; meat 0.038, fibre 0.040, fruit=0.059, vegetables=0.025, and current smoking=0.046).

Conclusions

Genetically determined low COX-2 and high IL-1β activity were associated with increased risk of CRC in this northern Caucasian cohort. Furthermore, interactions were found between IL10, IL1b, and PTGS2 and diet and lifestyle factors in relation to CRC. The present study demonstrates that gene-environment interactions may identify genes and environmental factors involved in colorectal carcinogenesis.

Panax notoginseng attenuates experimental colitis in the azoxymethane/dextran sulfate sodium mouse model

Patients suffering from inflammatory bowel disease are at a high risk of developing colorectal cancer. To assess the anticancer potential of botanicals, in this study, we evaluated the effects of Panax notoginseng on azoxymethane/dextran sulfate sodium (DSS)-induced colitis. One week after A/J mice received azoxymethane, the animals received DSS for 8 days or were supplemented with P. notoginseng extract, at 30 or 90 mg/kg. DSS-induced colitis was scored with the disease activity index. The severity of the inflammatory lesions was evaluated by a colon tissue histological assessment. The expression of inducible nitric oxide synthase and cyclooxygenase-2 (COX-2) were also explored. We observed that the effects of P. notoginseng on the reduction of colon inflammation, expressed in disease activity index score, were in a dose-related manner (p < 0.01). P. notoginseng inhibited the reduction of the colon length and the loss of bodyweight in dose-related manner (all p < 0.05). The histological assessment of the colitis and inflammatory-related immunohistochemical data also supported the pharmacological observations. Our data suggest that P. notoginseng is a promising candidate in preventing and treating colitis and inflammation-associated colon carcinogenesis.

Biomarkers in precision therapy in colorectal cancer

Colorectal cancer (CRC) is the most commonly diagnosed cancer in Europe. Because CRC is also a major cause of cancer-related deaths worldwide, a lot of research has been focused on the discovery and development of biomarkers to improve the diagnostic process and to predict treatment outcomes. Up till now only a few biomarkers are recommended by expert panels. Current TNM criteria, however, cause substantial under- and overtreatment of CRC patients. Consequently, there is a growing need for new and efficient biomarkers to ensure optimal treatment allocation. An ideal biomarker should be easily translated into clinical practice, to identify patients who can be spared from treatment or benefit from therapy, ultimately resulting in precision medicine in the future. In this review we aim to provide an overview of a number of frequently studied biomarkers in CRC and, at the same time, we will emphasize the challenges and controversies that withhold the clinical introduction of these biomarkers. We will discuss both prognostic and predictive markers of chemotherapy, aspirin therapy as well as overall therapy toxicity. Currently, only mutant KRAS, mutant BRAF, MSI and the Oncotype DX® Colon Cancer Assay are used in clinical practice. Other biomarker studies showed insufficient evidence to be introduced into clinical practice. Divergent patient selection criteria, absence of validation studies and a large number of single biomarker studies are possibly responsible. We therefore recommend that future studies focus on combining key markers, rather than analysing single markers, standardizing study protocols, and validate the results in independent study cohorts, followed by prospective clinical trials.

Suppression of inflammatory cascade is implicated in methyl amooranin-mediated inhibition of experimental mammary carcinogenesis

Breast cancer represents the second leading cause of cancer-related deaths among women worldwide and preventive therapy could reverse or delay the devastating impact of this disease. Methyl-amooranin (methyl-25-hydroxy-3-oxoolean-12-en-28-oate, AMR-Me), a novel synthetic oleanane triterpenoid, reduced the incidence and burden of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in rats through antiproliferative and proapoptotic effects. Since chronic inflammation plays an important role in the pathogenesis of breast cancer and several synthetic oleanane compounds are known potent anti-inflammatory agents, we aim to investigate anti-inflammatory mechanisms of AMR-Me by monitoring various proinflammatory and stress markers, such as cyclooxygenase-2 (COX-2) and heat shock protein 90 (HSP90), and nuclear factor-κB (NF-κB) signaling during DMBA mammary tumorigenesis in rats. Mammary tumors were harvested from a chemopreventive study in which AMR-Me (0.8-1.6 mg/kg) was found to inhibit mammary carcinogenesis in a dose-response manner. The expressions of COX-2, HSP90, NF-κB, and inhibitory κB-α (IκB-α) were determined by immunohistochemistry and reverse transcription-polymerase chain reaction. AMR-Me downregulated the expression of intratumor COX-2 and HSP90, suppressed the degradation of IκB-α, and reduced the translocation of NF-κB from cytosol to nucleus. Our present study provides the first in vivo evidence that NF-κB-evoked inflammatory cascade is a major target of AMR-Me in breast cancer. Our current results together with our previous findings suggest that disruption of NF-κB signaling contributes to anti-inflammatory, antiproliferative, and apoptosis-inducing mechanisms involved in AMR-Me-mediated chemoprevention of rat mammary carcinogenesis. These encouraging mechanistic results coupled with a safety profile should facilitate the clinical development of AMR-Me as breast cancer chemopreventive drug.

Targeting 20-HETE producing enzymes in cancer - rationale, pharmacology, and clinical potential

Studies demonstrate that lipid mediator 20-Hydroxyeicosatetraenoic acid (20-HETE) synthesis and signaling are associated with the growth of cancer cells in vitro and in vivo. Stable 20-HETE agonists promote the proliferation of cancer cells, whereas selective inhibitors of the 20-HETE-producing enzymes of the Cytochrome (CYP450)4A and CYP4F families can block the proliferation of glioblastoma, prostate, renal cell carcinoma, and breast cancer cell lines. A recent observation that the expression of CYP4A/4F genes was markedly elevated in thyroid, breast, colon, and ovarian cancer further highlights the significance of 20-HETE-producing enzymes in the progression of different types of human cancer. These findings provide the rationale for targeting 20-HETE-producing enzymes in human cancers and set the basis for the development of novel therapeutic strategies for anticancer treatment.