Inhibition of activator protein 1 activity and neoplastic transformation by aspirin

Genomic and epigenomic responses to aspirin in human colonic organoids

Aspirin (ASA) is a proven chemoprotective agent for colorectal cancer, though mechanisms underlying these effects are incompletely understood. Human organoids are an ideal system to study genomic and epigenomic host-environment interactions. We use human colonic organoids to profile ASA responses on genome-wide gene expression and chromatin accessibility. Human colonic organoids from one individual were cultured and treated in triplicate with 3 mM ASA or vehicle control (DMSO) for 24 h. Gene expression and chromatin accessibility were measured using RNA- and ATAC-sequencing, respectively. Differentially expressed genes were analyzed using DESeq2. Top genes were validated by qPCR. Gene set enrichment was performed by SetRank. Differentially accessible peaks were analyzed using DiffBind and edgeR. Peak annotation and differential transcription factor motifs were determined by HOMER and diffTF. The results showed robust transcriptional responses to ASA with significant enrichment for fatty acid oxidation and peroxisome proliferator-activated receptor (PPAR) signaling that were validated in independent organoid lines. A large number of differentially accessible chromatin regions were found in response to ASA with significant enrichment for Fos, Jun, and Hnf transcription factor motifs. Integrated analysis of epigenomic and genomic treatment responses highlighted gene regions that could mediate ASA's specific effects in the colon including those involved in chemoprotection and/or toxicity. Assessment of chromatin accessibility and transcriptional responses to ASA yielded new observations about genome-wide effects in the colon facilitated by application of human colonic organoids. This framework can be applied to study colonic ASA responses between individuals and populations in future studies.

Targeting cancer-related inflammation with non-steroidal anti-inflammatory drugs: Perspectives in pharmacogenomics

Inflammatory processes are essential for innate immunity and contribute to carcinogenesis in various malignancies, such as colorectal cancer, esophageal cancer and lung cancer. Pharmacotherapies targeting inflammation have the potential to reduce the risk of carcinogenesis and improve therapeutic efficacy of existing anti-cancer treatment. Non-steroidal anti-inflammatory drugs (NSAIDs), comprising a variety of structurally different chemicals that can inhibit cyclooxygenase (COX) enzymes and other COX-independent pathways, are originally used to treat inflammatory diseases, but their preventive and therapeutic potential for cancers have also attracted researchers' attention. Pharmacogenomic variability, including distinct genetic characteristics among different patients, can significantly affect pharmacokinetics and effectiveness of NSAIDs, which might determine the preventive or therapeutic success for cancer patients. Hence, a more comprehensive understanding in pharmacogenomic characteristics of NSAIDs and cancer-related inflammation would provide new insights into this appealing strategy. In this review, the up-to-date advances in clinical and experimental researches targeting cancer-related inflammation with NSAIDs are presented, and the potential of pharmacogenomics are discussed as well.

p66Shc Deficiency in Chronic Lymphocytic Leukemia Promotes Chemokine Receptor Expression Through the ROS-Dependent Inhibition of NF-κB

The microenvironment of lymphoid organs is central to the pathogenesis of chronic lymphocytic leukemia (CLL). Within it, tumor cells find a favourable niche to escape immunosurveillance and acquire pro-survival signals. We have previously reported that a CLL-associated defect in the expression of the pro-apoptotic and pro-oxidant adaptor p66Shc leads to enhanced homing to and accumulation of leukemic cells in the lymphoid microenvironment. The p66Shc deficiency-related impairment in intracellular reactive oxygen species (ROS) production in CLL cells is causally associated to the enhanced expression of the chemokine receptors CCR2, CXCR3 and CCR7, that promote leukemic cell homing to both lymphoid and non-lymphoid organs, suggesting the implication of a ROS-modulated transcription factor(s). Here we show that the activity of the ROS-responsive p65 subunit of the transcription factor NF-κB was hampered in the CLL-derived cell line MEC-1 expressing a NF-κB-luciferase reporter following treatment with H2O2. Similar results were obtained when intracellular ROS were generated by expression of p66Shc, but not of a ROS-defective mutant, in MEC-1 cells. NF-κB activation was associated with increased expression of the chemokine receptors CCR2, CXCR3 and CCR7. Reconstitution of p66Shc in CLL cells normalized intracellular ROS and hampered NF-κB activation, which led to a decrease in the expression of these homing receptors. Our data provide direct evidence that the p66Shc-deficiency-related ROS depletion in CLL cells concurs to NF-κB hyperactivation and homing receptor overexpression, providing a mechanistic basis for the enhanced ability of these cells to accumulate in the pro-survival lymphoid niche.

Limitations of drug concentrations used in cell culture studies for understanding clinical responses of NSAIDs

In this review, the in vitro cellular effects of six nonsteroidal anti-inflammatory drugs (NSAIDs), salicylate, ibuprofen, naproxen, indomethacin, celecoxib and diclofenac, are examined. Inhibition of prostanoid synthesis in vitro generally occurs within the therapeutic range of plasma concentrations that are observed in vivo, consistent with the major action of NSAIDs being inhibition of prostanoid production. An additional probable cellular action of NSAIDs has been discovered recently, viz. decreased oxidation of the endocannabinoids, 2-arachidonoyl glycerol and arachidonyl ethanolamide. Many effects of NSAIDs, other than decreased oxidation of arachidonic acid and endocannabinoids, have been put forward but almost all of these additional processes are observed at supratherapeutic concentrations when the concentration of albumin, the major protein that binds NSAIDs, is taken into account. However, one exception is salicylate, a very potent inhibitor of the neutrophilic enzyme, myeloperoxidase, the inhibition of which leads to reduced production of the inflammatory mediator, hypochlorous acid, and inhibition of the inflammation associated with rheumatoid arthritis.

Mechanisms of Colorectal Cancer Prevention by Aspirin-A Literature Review and Perspective on the Role of COX-Dependent and -Independent Pathways

Aspirin, synthesized and marketed in 1897 by Bayer, is one of the most widely used drugs in the world. It has a well-recognized role in decreasing inflammation, pain and fever, and in the prevention of thrombotic cardiovascular diseases. Its anti-inflammatory and cardio-protective actions have been well studied and occur through inhibition of cyclooxygenases (COX). Interestingly, a vast amount of epidemiological, preclinical and clinical studies have revealed aspirin as a promising chemopreventive agent, particularly against colorectal cancers (CRC); however, the primary mechanism by which it decreases the occurrences of CRC has still not been established. Numerous mechanisms have been proposed for aspirin’s chemopreventive properties among which the inhibition of COX enzymes has been widely discussed. Despite the wide attention COX-inhibition has received as the most probable mechanism of cancer prevention by aspirin, it is clear that aspirin targets many other proteins and pathways, suggesting that these extra-COX targets may also be equally important in preventing CRC. In this review, we discuss the COX-dependent and -independent pathways described in literature for aspirin’s anti-cancer effects and highlight the strengths and limitations of the proposed mechanisms. Additionally, we emphasize the potential role of the metabolites of aspirin and salicylic acid (generated in the gut through microbial biotransformation) in contributing to aspirin’s chemopreventive actions. We suggest that the preferential chemopreventive effect of aspirin against CRC may be related to direct exposure of aspirin/salicylic acid or its metabolites to the colorectal tissues. Future investigations should shed light on the role of aspirin, its metabolites and the role of the gut microbiota in cancer prevention against CRC.

Cannabidiolic acid dampens the expression of cyclooxygenase-2 in MDA-MB-231 breast cancer cells: Possible implication of the peroxisome proliferator-activated receptor β/δ abrogation

A growing body of experimental evidence strongly suggests that cannabidiolic acid (CBDA), a major component of the fiber-type cannabis plant, exerts a variety of biological activities. We have reported that CBDA can abrogate cyclooxygenase-2 (COX-2) expression and its enzymatic activity. It is established that aberrant expression of COX-2 correlates with the degree of malignancy in breast cancer. Although the reduction of COX-2 expression by CBDA offers an attractive medicinal application, the molecular mechanisms underlying these effects have not fully been established. It has been reported that COX-2 expression is positively controlled by peroxisome proliferator-activated receptor β/δ (PPARβ/δ) in some cancerous cells, although there is "no" modulatory element for PPARβ/δ on the COX-2 promoter. No previous studies have examined whether an interaction between PPARβ/δ-mediated signaling and COX-2 expression exists in MDA-MB-231 cells. We confirmed, for the first time, that COX-2 expression is positively modulated by PPARβ/δ-mediated signaling in MDA-MB-231 cells. CBDA inhibits PPARβ/δ-mediated transcriptional activation stimulated by the PPARβ/δ-specific agonist, GW501516. Furthermore, the disappearance of cellular actin stress fibers, a hallmark of PPARβ/δ and COX-2 pathway activation, as evoked by the GW501516, was effectively reversed by CBDA. Activator protein-1 (AP-1)-driven transcriptional activity directly involved in the regulation of COX-2 was abrogated by the PPARβ/δ-specific inverse agonists (GSK0660/ST-247). Thus, it is implicated that there is positive interaction between PPARβ/δ and AP-1 in regulation of COX-2. These data support the concept that CBDA is a functional down-regulator of COX-2 through the abrogation of PPARβ/δ-related signaling, at least in part, in MDA-MB-231 cells.

Low-dose aspirin reduces hypoxia-induced sFlt1 release via the JNK/AP-1 pathway in human trophoblast and endothelial cells

Pre-eclampsia (PE) is a serious hypertensive disorder of pregnancy that remains a leading cause of perinatal and maternal morbidity and mortality worldwide. Placental ischemia/hypoxia and the secretion of soluble fms-like tyrosine kinase 1 (sFlt1) into maternal circulation are involved in the pathogenesis of PE. Although low-dose aspirin (LDA) has beneficial effects on the prevention of PE, the exact mechanisms of action of LDA, particularly on placental dysfunction, and sFlt1 release, have not been well investigated. This study aimed to determine whether LDA exists the protective effects on placental trophoblast and endothelial functions and prevents PE-associated sFlt1 release. First, we observed that LDA mitigated hypoxia-induced trophoblast apoptosis, showed positive effects on trophoblast cells migration and invasion activity, and increased the tube-forming activity of human umbilical vein endothelial cells (HUVECs). In addition, LDA decreased hypoxia-induced sFlt1 production, and the c-Jun NH₂ -terminal kinase/activator protein-1 (JNK/AP-1) pathway was shown to mediate the induction of sFlt1. Moreover, the transcription factor AP-1 was confirmed to regulate the Flt1 gene expression by directly binding to the Flt1 promoter in luciferase assays. The result of chromatin immunoprecipitation assays further demonstrated that LDA could directly decrease the expression of the transcription factor AP-1, and thus decrease sFlt1 production. Finally, the effects of LDA on sFlt1 production were proved in human placental explants. Taken together, our data show the protective effects of LDA against trophoblast and endothelial cell dysfunction and reveal that the LDA-mediated inhibition of sFlt1 via the JNK/AP-1 pathway may be a potential cellular/molecular mechanism for the prevention of PE.

Involvement of the antioxidative property of morusin in blocking phorbol ester-induced malignant transformation of JB6 P+ mouse epidermal cells

Chemoprevention has been acknowledged as an important and practical strategy for managing cancer. We have previously synthesized morusin, a prenylated flavonoid that exhibits anti-cancer progression activity. In the present study, we evaluated the anti-cancer promotion potential of morusin by using the mouse epidermal JB6 P⁺ cell model. Extensive evidence shows that tumor promotion by phorbol esters is due to the stimulation of reactive oxygen species (ROS). Therefore, the effect of morusin on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ROS production was assessed. Noncytotoxic concentrations of morusin were found to dose-dependently reduce TPA-induced ROS production. Moreover, morusin inhibited TPA-induced activator protein-1 (AP-1) and nuclear factor-kappa B (NF-κB) activation, which can mediate cell proliferation and malignant transformation. Furthermore, morusin inhibited the TPA upregulation of cyclooxygenase 2 (COX-2), which may be regulated by AP-1 and NF-κB. In addition, noncytotoxic concentrations of morusin reduced the TPA-promoted cell growth of JB6 P⁺ cells and inhibited TPA-induced malignant properties, such as cytoskeletal rearrangement and cell migration of JB6 P⁺ cells. Similar to the effects of glutathione (GSH) pretreatment, morusin inhibited TPA-induced expression of N-cadeherin and vimentin, which are malignant cell surface proteins. Finally, morusin treatment dose-dependently suppressed the TPA-induced anchorage-independent cell transformation of JB6 P⁺ cells. In conclusion, our results evidence that morusin possesses anti-cancer promotion potential because of its antioxidant property, which mediates multiple transformation-associated gene expression.

Inhibition of Radiation-Induced Oxidative Damage in the Lung Tissue: May Acetylsalicylic Acid Have a Positive Role?

The lung is relatively sensitive to irradiation. It is shown that acetylsalicylic acid (ASA) might reduce oxidative injury and that it has a place in protection from cancer. The aim of this study is to evaluate the potential radioprotective effects of ASA. Whole-body irradiation (6 Gy, single dose) was applied to the rats. Glutathione (GSH), malondialdehyde (MDA), myeloperoxidase (MPO), and nitric oxide (NO) levels in the lung tissue were measured. Control (C), Radiation (R), Radiation + ASA (R + ASA; received irradiation and 25 mg/kg of ASA intraperitoneally (i.p.)), and Radiation + Amifostine (R + WR-2721; received irradiation and 200 mg/kg of WR-2721 i.p.) groups were used. The MPO levels decreased statistically significantly in the group administered ASA. Histopathologically, a radioprotective effect of ASA was more evident in the R + ASA group. ASA is an agent which has not been used as a radioprotector in the clinic yet, and it is worth supporting with more advanced studies.

Safety Assessment of Salicylic Acid, Butyloctyl Salicylate, Calcium Salicylate, C12–15 Alkyl Salicylate, Capryloyl Salicylic Acid, Hexyldodecyl Salicylate, Isocetyl Salicylate, Isodecyl Salicylate, Magnesium Salicylate, MEA-Salicylate, Ethylhexyl Salicylate, Potassium Salicylate, Methyl Salicylate, Myristyl Salicylate, Sodium Salicylate, TEA-Salicylate, and Tridecyl Salicylate

Salicylic Acid is an aromatic acid used in cosmetic formulations as a denaturant, hair-conditioning agent, and skin-conditioning agent—miscellaneous in a wide range of cosmetic products at concentrations ranging from 0.0008% to 3%. The Calcium, Magnesium, and MEA salts are preservatives, and Potassium Salicylate is a cosmetic biocide and preservative, not currently in use. Sodium Salicylate is used as a denaturant and preservative (0.09% to 2%). The TEA salt of Salicylic Acid is used as an ultraviolet (UV) light absorber (0.0001% to 0.75%). Several Salicylic Acid esters are used as skin conditioning agents—miscellaneous (Capryloyl, 0.1% to 1%; C12–15 Alkyl, no current use; Isocetyl, 3% to 5%; Isodecyl, no current use; and Tridecyl, no current use). Butyloctyl Salicylate (0.5% to 5%) and Hexyldodecyl Salicylate (no current use) are hair-conditioning agents and skin-conditioning agents—miscellaneous. Ethylhexyl Salicylate (formerly known as Octyl Salicylate) is used as a fragrance ingredient, sunscreen agent, and UV light absorber (0.001% to 8%), and Methyl Salicylate is used as a denaturant and flavoring agent (0.0001% to 0.6%). Myristyl Salicylate has no reported function. Isodecyl Salicylate is used in three formulations, but no concentration of use information was reported. Salicylates are absorbed percutaneously. Around 10% of applied salicylates can remain in the skin. Salicylic Acid is reported to enhance percutaneous penetration of some agents (e.g., vitamin A), but not others (e.g., hydrocortisone). Little acute toxicity (LD50 in rats; >2 g/kg) via a dermal exposure route is seen for Salicylic Acid, Methyl Salicylate, Tridecyl Salicylate, and Butyloctyl Salicylate. Short-term oral, inhalation, and parenteral exposures to salicylates sufficient to produce high blood concentrations are associated primarily with liver and kidney damage. Subchronic dermal exposures to undiluted Methyl Salicylate were associated with kidney damage. Chronic oral exposure to Methyl Salicylate produced bone lesions as a function of the level of exposure in 2-year rat studies; liver damage was seen in dogs exposed to 0.15 g/kg/day in one study; kidney and liver weight increases in another study at the same exposure; but no liver or kidney abnormalities in a study at 0.167 g/kg/day. Applications of Isodecyl, Tridecyl, and Butyloctyl Salicylate were not irritating to rabbit skin, whereas undiluted Ethylhexyl Salicylate produced minimal to mild irritation. Methyl Salicylate at a 1% concentration with a 70% ethanol vehicle were irritating, whereas a 6% concentration in polyethylene glycol produced little or no irritation. Isodecyl Salicylate, Methyl Salicylate, Ethylhexyl (Octyl) Salicylate, Tridecyl Salicylate, and Butyloctyl Salicylate were not ocular irritants. Although Salicylic Acid at a concentration of 20% in acetone was positive in the local lymph node assay, a concentration of 20% in acetone/olive oil was not. Methyl Salicylate was negative at concentrations up to 25% in this assay, independent of vehicle. Maximization tests of Methyl Salicylate, Ethylhexyl Salicylate, and Butyloctyl Salicylate produced no sensitization in guinea pigs. Neither Salicylic Acid nor Tridecyl Salicylate were photosensitizers. Salicylic Acid, produced when aspirin is rapidly hydrolyzed after absorption from the gut, was reported to be the causative agent in aspirin teratogenesis in animals. Dermal exposures to Methyl Salicylate, oral exposures to Salicylic Acid, Sodium Salicylate, and Methyl Salicylate, and parenteral exposures to Salicylic Acid, Sodium Salicylate, and Methyl Salicylate are all associated with reproductive and developmental toxicity as a function of blood levels reached as a result of exposure. An exposure assessment of a representative cosmetic product used on a daily basis estimated that the exposure from the cosmetic product would be only 20% of the level seen with ingestion of a “baby” aspirin (81 mg) on a daily basis. Studies of the genotoxic potential of Salicylic Acid, Sodium Salicylate, Isodecyl Salicylate, Methyl Salicylate, Ethylhexyl (Octyl) Salicylate, Tridecyl Salicylate, and Butyloctyl Salicylate were generally negative. Methyl Salicylate, in a mouse skin-painting study, did not induce neoplasms. Likewise, Methyl Salicylate was negative in a mouse pulmonary tumor system. In clinical tests, Salicylic Acid (2%) produced minimal cumulative irritation and slight or no irritation(1.5%); TEA-Salicylate (8%) produced no irritation; Methyl Salicylate (>12%) produced pain and erythema, a 1% aerosol produced erythema, but an 8% solution was not irritating; Ethylhexyl Salicylate (4%) and undiluted Tridecyl Salicylate produced no irritation. In atopic patients, Methyl Salicylate caused irritation as a function of concentration (no irritation at concentrations of 15% or less). In normal skin, Salicylic Acid, Methyl Salicylate, and Ethylhexyl (Octyl) Salicylate are not sensitizers. Salicylic Acid is not a photosensitizer, nor is it phototoxic. Salicylic Acid and Ethylhexyl Salicylate are low-level photoprotective agents. Salicylic Acid is well-documented to have keratolytic action on normal human skin. Because of the possible use of these ingredients as exfoliating agents, a concern exists that repeated use may effectively increase exposure of the dermis and epidermis to UV radiation. It was concluded that the prudent course of action would be to advise the cosmetics industry that there is a risk of increased UV radiation damage with the use of any exfoliant, including Salicylic Acid and the listed salicylates, and that steps need to be taken to formulate cosmetic products with these ingredients as exfoliating agents so as not to increase sun sensitivity, or when increased sun sensitivity would be expected, to include directions for the daily use of sun protection. The available data were not sufficient to establish a limit on concentration of these ingredients, or to identify the minimum pH of formulations containing these ingredients, such that no skin irritation would occur, but it was recognized that it is possible to formulate cosmetic products in a way such that significant irritation would not be likely, and it was concluded that the cosmetics industry should formulate products containing these ingredients so as to be nonirritating. Although simultaneous use of several products containing Salicylic Acid could produce exposures greater than would be seen with use of baby aspirin (an exposure generally considered to not present a reproductive or developmental toxicity risk), it was not considered likely that consumers would simultaneously use multiple cosmetic products containing Salicylic Acid. Based on the available information, the Cosmetic Ingredient Review Expert Panel reached the conclusion that these ingredients are safe as used when formulated to avoid skin irritation and when formulated to avoid increasing the skin's sun sensitivity, or, when increased sun sensitivity would be expected, directions for use include the daily use of sun protection.

Aspirin induces IL-4 production: augmented IL-4 production in aspirin-exacerbated respiratory disease

Aspirin hypersensitivity is a hallmark of aspirin-exacerbated respiratory disease (AERD), a clinical syndrome characterized by the severe inflammation of the respiratory tract after ingestion of cyclooxygenase-1 inhibitors. We investigated the capacity of aspirin to induce interleukin-4 (IL-4) production in inflammatory cells relevant to AERD pathogenesis and examined the associated biochemical and molecular pathways. We also compared IL-4 production in peripheral blood mononuclear cells (PBMCs) from patients with AERD vs aspirin-tolerant asthma (ATA) upon exposure to aspirin. Aspirin induced IL-4 expression and activated the IL-4 promoter in a report assay. The capacity of aspirin to induce IL-4 expression correlated with its activity to activate mitogen-activated protein kinases, to form DNA-protein complexes on P elements in the IL-4 promoter and to synthesize nuclear factor of activated T cells, critical transcription factors for IL-4 transcription. Of clinical importance, aspirin upregulated IL-4 production twice as much in PBMCs from patients with AERD compared with PBMCs from patients with ATA. Our results suggest that IL-4 is an inflammatory component mediating intolerance reactions to aspirin, and thus is crucial for AERD pathogenesis.

Src Tyrosine Kinase Activation by 4-Hydroxynonenal Upregulates p38, ERK/AP-1 Signaling and COX-2 Expression in YPEN-1 Cells

4-Hydroxynonenal (4-HNE), a major end product of lipid peroxidation, is highly reactive and involved in various cellular processes, such as inflammatory signaling. However, to date, the mechanistic roles of 4-HNE in inflammatory signaling related to protein tyrosine kinases have not been elucidated. In the present study, we investigated the interaction between 4-HNE and Src (a non-receptor tyrosine kinase) for its involvement in the molecular modulation of the inflammatory signaling pathway utilizing the YPEN-1 cell system. Immunoprecipitation experiments showed that 4-HNE phosphorylates (activates) Src at Tyr416 via adduct formation. In addition, LC-MS/MS and a docking simulation model revealed an addiction site at the Cys248 residue of Src, resulting in the stimulation of downstream p38, ERK/AP-1 and cyclooxygenase-2 (COX-2) signaling in YPEN-1 cells. The role of 4-HNE-activated Src in downstream inflammatory signaling was further investigated using dasatinib (a Src inhibitor) and by siRNA knockdown of Src. p38 and ERK were directly regulated by Src, as revealed by immunoblotting of the phosphorylated forms of mitogen-activated protein kinases (MAPKs), which are key elements in the signaling transduction pathway initiated by Src. The study also shows that Src modulates the HNE-enhanced activation of AP-1 and the expression of COX-2 (a target gene of AP-1). Together, the results of this study show that 4-HNE stimulates Src tyrosine kinase in activation of the inflammation process.

Aspirin Prevents Colorectal Cancer by Normalizing EGFR Expression

BACKGROUND

Aspirin intake reduces the risk of colorectal cancer (CRC), but the molecular underpinnings remain elusive. Epidermal growth factor receptor (EGFR), which is overexpressed in about 80% of CRC cases, is implicated in the etiology of CRC. Here, we investigated whether aspirin can prevent CRC by normalizing EGFR expression.

METHODS

Immunohistochemistry staining was performed on paraffin-embedded tissue sections from normal colon mucosa, adenomatous polyps from FAP patients who were classified as regular aspirin users or nonusers. The interplay between cyclooxygenase-2 (COX-2) and EGFR was studied in primary intestinal epithelial cells isolated from Apc^Min mice, immortalized normal human colon epithelial cells (HCEC) as well as murine embryonic fibroblasts (MEFs).

RESULTS

Immunohistochemistry staining results established that EGFR overexpression is an early event in colorectal tumorigenesis, which can be greatly attenuated by regular use of aspirin. Importantly, EGFR and COX-2 were co-overexpressed and co-localized with each other in FAP patients. Further mechanistic studies revealed that COX-2 overexpression triggers the activation of the c-Jun-dependent transcription factor, activator protein-1 (AP-1), which binds to the Egfr promoter. Binding facilitates the cellular accumulation of EGFR and lowers the threshold required for pre-neoplastic cells to undergo transformation.

CONCLUSION

Aspirin might exert its chemopreventive activity against CRC, at least partially, by normalizing EGFR expression in gastrointestinal precancerous lesions.

Down-regulation of cyclooxygenase-2 (COX-2) by cannabidiolic acid in human breast cancer cells

Metastases are known to be responsible for approximately 90% of breast cancer-related deaths. Cyclooxygenase-2 (COX-2) is involved not only in inflammatory processes, but also in the metastasis of cancer cells; it is expressed in 40% of human invasive breast cancers. To comprehensively analyze the effects of cannabidiolic acid (CBDA), a selective COX-2 inhibitor found in the fiber-type cannabis plant (Takeda et al., 2008), on COX-2 expression and the genes involved in metastasis, we performed a DNA microarray analysis of human breast cancer MDA-MB-231 cells, which are invasive breast cancer cells that express high levels of COX-2, treated with CBDA for 48 hr at 25 µM. The results obtained revealed that COX-2 and Id-1, a positive regulator of breast cancer metastasis, were down-regulated (0.19-fold and 0.52-fold, respectively), while SHARP1 (or BHLHE41), a suppressor of breast cancer metastasis, was up-regulated (1.72-fold) and CHIP (or STUB1) was unaffected (1.03-fold). These changes were confirmed by real-time RT-PCR analyses. Taken together, the results obtained here demonstrated that i) CBDA had dual inhibitory effects on COX-2 through down-regulation and enzyme inhibition, and ii) CBDA may possess the ability to suppress genes that are positively involved in the metastasis of cancer cells in vitro.

Impact of acetylsalicylic Acid on the clinicopathological characteristics and prognosis of patients with invasive breast cancer

BACKGROUND

The impact of acetylsalicylic acid (ASA) on the clinicopathological characteristics of breast cancer has not yet been elucidated in detail; we therefore aimed to investigate the effects of ASA on the clinicopathological characteristics of patients with breast cancer.

PATIENTS AND METHODS

Patients diagnosed with breast cancer were retrospectively analyzed. Breast cancer patients who were taking ASA at the time of breast cancer diagnosis were enrolled as ASA users (n = 84); matching patients with the same age who were not taking ASA were included as control group (n = 890).

RESULTS

The median age was 56 (range 34-82) years in both groups. ASA users had a significantly lower incidence of grade II-III tumors compared to non-users (P = 0.02). The other clinicopathological characteristics and treatment histories were similar in both groups. In patients using ASA, the disease-free survival (DFS) rate was 97.3%, 89.4%, and 79.9% and in non-users it was 94.1%, 81.8%, and 70.9% in the 1rst, 3rd, and 5th year, respectively (P = 0.01). In aspirin users, the overall survival rate was 95.0%, 90.6%, and 87.6% and in non-users it was 98.1%, 91.2%, and 85.5% in the 1rst, 3rd, and 5th year, respectively (P = 0.50).

CONCLUSION

Using ASA at the time of breast cancer diagnosis was associated with significantly improved DFS in breast cancer patients.

Δ(9)-THC modulation of fatty acid 2-hydroxylase (FA2H) gene expression: possible involvement of induced levels of PPARα in MDA-MB-231 breast cancer cells

We recently reported that Δ(9)-tetrahydrocannabinol (Δ(9)-THC), a major cannabinoid component in Cannabis Sativa (marijuana), significantly stimulated the expression of fatty acid 2-hydroxylase (FA2H) in human breast cancer MDA-MB-231 cells. Peroxisome proliferator-activated receptor α (PPARα) was previously implicated in this induction. However, the mechanisms mediating this induction have not been elucidated in detail. We performed a DNA microarray analysis of Δ(9)-THC-treated samples and showed the selective up-regulation of the PPARα isoform coupled with the induction of FA2H over the other isoforms (β and γ). Δ(9)-THC itself had no binding/activation potential to/on PPARα, and palmitic acid (PA), a PPARα ligand, exhibited no stimulatory effects on FA2H in MDA-MB-231 cells; thus, we hypothesized that the levels of PPARα induced were involved in the Δ(9)-THC-mediated increase in FA2H. In support of this hypothesis, we herein demonstrated that; (i) Δ(9)-THC activated the basal transcriptional activity of PPARα in a concentration-dependent manner, (ii) the concomitant up-regulation of PPARα/FA2H was caused by Δ(9)-THC, (iii) PA could activate PPARα after the PPARα expression plasmid was introduced, and (iv) the Δ(9)-THC-induced up-regulation of FA2H was further stimulated by the co-treatment with L-663,536 (a known PPARα inducer). Taken together, these results support the concept that the induced levels of PPARα may be involved in the Δ(9)-THC up-regulation of FA2H in MDA-MB-231 cells.

Salicylideneamino-2-thiophenol modulates nuclear factor-κB through redox regulation during the aging process

AIM

Many intracellular components have been implicated in the regulation of redox homeostasis, but homeostasis can be unbalanced by reactive species (RS), which also probably contribute to underlying inflammatory processes. Nuclear factor-κB (NF-κB) is a well-known redox-sensitive transcription factor that controls the genes responsible for regulating inflammation.

METHODS

In the present study, the authors investigated the effect of short-term salicylideneamino-2-thiophenol (SAL-2) administration on the modulation of pro-inflammatory NF-κB through redox regulation in aged rats. In addition, we compared the effects of SAL-2 and caloric restriction (CR) on inflammation and redox balance. The subjects were 24-month-old (old) Fischer 344 rats administered SAL-2 (10 mg/kg/day) by dietary supplementation or placed on a 30% restricted diet for 10 days, and 6-month-old (young) rats fed ad libitum for 10 days.

RESULTS

We found that NF-κB activation and the expressions of its related genes (vascular cell adhesion molecule-1, intercellular adhesion molecule-1, cyclooxygenase-2 and inducible nitric oxide synthase) were suppressed by SAL-2 supplementation in old CR rats to the levels observed in young rats. In addition, our molecular studies showed that the inhibitory effect of SAL-2 on the activation of NF-κB was mediated by the ability of SAL-2 to block the nuclear translocations of cytosolic thioredoxin and redox factor-1.

CONCLUSION

These findings strongly indicate that SAL-2 stabilizes age-related redox imbalance and modulates the signal transduction pathway involved in the age-associated molecular inflammatory process.

Piroxicam inhibits Masitinib-induced cyclooxygenase 2 expression in oral squamous cell carcinoma cells in vitro

Development and characterization of animal models for human cancers is important for the improvement of diagnosis and therapy. The oral squamous cell carcinoma (OSCC) of domestic animals resembles human OSCC in many aspects; thus, cell lines derived from OSCC of cats and dogs are a valuable model for human OSCC. We characterized 1 feline OSCC (FeOSCC-Sidney) and 1 canine OSCC (K9OSCC-Abby) cell line and compared their characteristics with human OSCC cell line hSCC-25. We calculated the doubling time of the new OSCC cell lines and evaluated the expression profiles of cancer-related markers and cell-cycle proteins such as c-kit, platelet-derived growth factor receptor, vascular endothelial growth factor receptor, epidermal growth factor receptor, cyclooxygenase (COX)-1, COX-2, and p27 by immunocytochemistry and Western blot analysis. We evaluated the effects of novel receptor tyrosine kinase inhibitor (Masitinib, AB1010) and the nonsteroidal anti-inflammatory drug piroxicam on the previously mentioned OSCC cells. Interestingly, AB1010 increased expression levels of COX-2 in all tested OSCCs. Cotreatment of piroxicam with Masitinib significantly inhibited cell proliferation of OSCC as compared to either drug alone through the c-kit and AKT signaling pathways. Piroxicam inhibited Masitinib-induced COX-2 expression in all tested OSCCs. Therefore, targeting these two signaling pathways simultaneously was more efficient for inhibition of OSCCs across these species.

Death in the substantia nigra: a motor tragedy

It is well known that the death of dopaminergic neurons of the substantia nigra pars compacta (SNc) is the pathological hallmark of Parkinson's disease (PD), the second most common and disabling condition in the expanding elderly population. Nevertheless, the intracellular cascade of events leading to dopamine cell death is still unknown and, consequently, treatment is largely symptomatic rather than preventive. Moreover, the mechanisms whereby nigral dopaminergic neurons may degenerate still remain controversial. Hitherto, several data have shown that the earlier cellular disturbances occurring in dopaminergic neurons include oxidative stress, excitotoxicity, inflammation, mitochondrial dysfunction and altered proteolysis. These alterations, rather than killing neurons, trigger subsequent death-related molecular pathways, including elements of apoptosis. In rare incidences, PD may be inherited; this evidence has opened a new and exciting area of research, attempting to shed light on the nature of the more common idiopathic PD form. In this review, the characteristics of the SNc dopaminergic neurons and their lifecycle from birth to death are reviewed. In addition, of the mechanisms by which the aforementioned alterations cause neuronal dopaminergic death, particular emphasis will be given to the role played by inflammation, and the relevance of the possible use of anti-inflammatory drugs in the treatment of PD. Finally, new evidence of a possible de novo neurogenesis in the SNc of adult animals and in PD patients will also be examined.

6-C-(E-phenylethenyl)-naringenin suppresses colorectal cancer growth by inhibiting cyclooxygenase-1

Recent clinical trials raised concerns regarding the cardiovascular toxicity of selective cyclooxygenase-2 (COX-2) inhibitors and cyclooxygenase-1 (COX-1) is now being reconsidered as a target for chemoprevention. Our aims were to determine whether selective COX-1 inhibition could delay or prevent cancer development and also clarify the underlying mechanisms. Data clearly showed that COX-1 was required for maintenance of malignant characteristics of colon cancer cells or tumor promoter-induced transformation of preneoplastic cells. We also successfully applied a ligand-docking computational method to identify a novel selective COX-1 inhibitor, 6-C-(E-phenylethenyl)-naringenin (designated herein as 6CEPN). 6CEPN could bind to COX-1 and specifically inhibited its activity both in vitro and ex vivo. In colorectal cancer cells, it potently suppressed anchorage-independent growth by inhibiting COX-1 activity. 6CEPN also effectively suppressed tumor growth in a 28-day colon cancer xenograft model without any obvious systemic toxicity. Taken together, COX-1 plays a critical role in human colorectal carcinogenesis, and this specific COX-1 inhibitor merits further investigation as a potential preventive agent against colorectal cancer.

Aspirin attenuates vinorelbine-induced endothelial inflammation via modulating SIRT1/AMPK axis

Vinorelbine (VNR), a semisynthetic vinca alkaloid acquired from vinblastine, is frequently used as the candidate for intervention of solid tumors. Nevertheless, VNR-caused endothelial injuries may lead a mitigative effect of clinical treatment efficiency. A growing body of evidence reveals that aspirin is a potent antioxidant and anti-inflammation drug. We investigated whether aspirin attenuate VNR-induced endothelial dysfunction. Human endothelial cells (EA.hy 926) were treated with VNR to cause endothelial inflammation. Western blotting, ROS assay, ELISA were used to confirm the anti-inflammatory effect of aspirin. We confirmed that VNR suppresses SIRT1 expression, reduced LKB1 and AMPK phosphorylation as well as enriched PKC activation in treated endothelial cells. Furthermore, the membrane translocation assay displayed that the levels of NADPH oxidase subunits p47phox and Rac-1 in membrane fractions of endothelial cells were higher in cells that had been treated with VNR for than in untreated cells. We corroborated that treatment of Aspirin significantly diminishes VNR-repressed SIRT1, LKB1 and AMPK phosphorylation and VNR-promoted NADPH oxidase activation, however, those findings were vanished by SIRT1 and AMPK siRNAs. Our data also shown that Aspirin represses VNR-activated TGF-beta-activated kinase-1 (TAK1) activation, inhibited the interaction of TAK1/TAK-binding protein1 (TAB1), suppressed NF-kappa B activation and pro-inflammatory cytokine secretion. We demonstrated a novel connection between VNR-caused oxidative damages and endothelial dysfunction, and provide further insight into the protective effects of aspirin in VNR-caused endothelial dysfunction.

Mechanisms of aspirin desensitization

Aspirin-exacerbated respiratory disease is a clinical syndrome characterized by severe, persistent asthma, hyperplastic eosinophilic sinusitis with nasal polyps, and reactions to aspirin and other nonsteroidal antiinflammatory drugs that preferentially inhibit cyclooxygenase 1. The mechanisms behind the therapeutic effects of aspirin desensitization remain poorly understood. Recent studies suggest that the clinical benefits may occur through direct inhibition of tyrosine kinases and the signal transducer and activator of transcription 6 signaling pathway, which results in inhibition of interleukin 4 production. In this article, the current understanding of the mechanisms of aspirin desensitization is reviewed and future areas of investigation are discussed.

The proapoptotic effect of traditional and novel nonsteroidal anti-inflammatory drugs in mammalian and yeast cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) have long been used to treat pain, fever, and inflammation. However, mounting evidence shows that NSAIDs, such as aspirin, have very promising antineoplastic properties. The chemopreventive, antiproliferative behaviour of NSAIDs has been associated with both their inactivation of cyclooxygenases (COX) and their ability to induce apoptosis via pathways that are largely COX-independent. In this review, the various proapoptotic pathways induced by traditional and novel NSAIDs such as phospho-NSAIDs, hydrogen sulfide-releasing NSAIDs and nitric oxide-releasing NSAIDs in mammalian cell lines are discussed, as well as the proapoptotic effects of NSAIDs on budding yeast which retains the hallmarks of mammalian apoptosis. The significance of these mechanisms in terms of the role of NSAIDs in effective cancer prevention is considered.

Synergistic effects of exemestane and aspirin on MCF-7 human breast cancer cells

OBJECTIVE

The purpose of this study is to investigate the combined effects of exemestane and aspirin on MCF-7 human breast cancer cells.

METHODS

Antiproliferative effects of exemestane and aspirin, alone and in combination, on growth of MCF-7 human breast cancer cells were assessed using the MTT assay. Synergistic interaction between the two drugs was evaluated in vitro using the combination index (CI) method. The cell cycle distribution was analyzed by flow cytometry and Western blotting was used to investigate the expression of cyclooxygenase-1, cyclooxygenase-2 and Bcl-2.

RESULTS

MTT assays indicated that combination treatment obviously decreased the viability of MCF-7 human breast cancer cells compared to individual drug treatment (CI<1). In addition, the combination of exemestane and aspirin exhibited a synergistic inhibition of cell proliferation, significantly arrested the cell cycle in the G0/G1 phase and produced a stronger inhibitory effect on COX-1 and Bcl-2 expression than control or individual drug treatment.

CONCLUSION

These results indicate that the combination of exemestane and aspirin might become a useful method to the treatment of hormone- dependent breast cancer. The combination of the two inhibitors significantly increased the response as compared to single agent treatment, suggesting that combination treatment could become a highly effective approach for breast cancer.

Aspirin protects human coronary artery endothelial cells against atherogenic electronegative LDL via an epigenetic mechanism: a novel cytoprotective role of aspirin in acute myocardial infarction

AIMS

L5 is the most negatively charged subfraction of human low-density lipoprotein (LDL) and is the only subfraction of LDL capable of inducing apoptosis in cultured vascular endothelial cells (ECs) by inhibiting fibroblast growth factor-2 (FGF2) transcription. We examined whether plasma L5 levels are elevated in patients with ST-segment elevation myocardial infarction (STEMI) and whether aspirin provides epigenetic protection of human coronary artery ECs (HCAECs) exposed to L5.

METHODS AND RESULTS

Plasma L5 levels were compared between patients with STEMI (n = 10) and control subjects with chest pain syndrome but a normal coronary arteriogram (n = 5). L5 was isolated from the plasma of STEMI patients and control subjects, and apoptosis, FGF2 expression, and FGF2 promoter methylation were examined in HCAECs treated with L5 and aspirin. Plasma L5 levels were significantly higher in STEMI patients than in control subjects (P < 0.001). Treatment of HCAECs with L5 resulted in reduced survival and FGF2 expression and increased CpG methylation of the FGF2 promoter. Co-treatment of HCAECs with L5 and a physiologically relevant, low concentration of aspirin (0.2 mM) attenuated the adverse effects of L5 on HCAEC survival, FGF2 expression, and FGF2 promoter methylation. In contrast, high concentrations of aspirin (≥1.0 mM) accentuated the effects of L5.

CONCLUSIONS

Our results show that L5 levels are significantly increased in STEMI patients. Furthermore, L5 impairs HCAEC function through CpG methylation of the FGF2 promoter, which is suppressed in the presence of low-concentration aspirin. Our results provide evidence of a novel mechanism of aspirin in the prevention of MI.

Expression of NSAID-activated gene-1 by EGCG in head and neck cancer: involvement of ATM-dependent p53 expression

Epigallocatechin-3-gallate (EGCG), a major polyphenolic constituent of green tea, possesses remarkable chemopreventive and therapeutic potential against various types of cancer, including head and neck squamous cell carcinoma (HNSCC). However, the molecular mechanism involved is not completely understood. Nonsteroidal anti-inflammatory drug-activated gene-1 (NAG-1), a transforming growth factor β superfamily protein, is shown to be induced by several antitumorigenic compounds and to exhibit proapoptotic and antitumorigenic activities. In this report, we demonstrate that EGCG transcriptionally induced the expression of NAG-1 during EGCG-induced apoptosis of HNSCC cells. Reporter assays, using the luciferase constructs containing the NAG-1 promoter, demonstrate that p53 is required for EGCG-mediated activation of NAG-1. Overexpression of NAG-1 enhanced the apoptotic effect of EGCG, whereas suppression of NAG-1 expression by small interfering RNA attenuated EGCG-induced apoptosis in HNSCC cells. Subsequently, we found that ataxia-telangiectasia mutated (ATM) plays an important role in activating these proapoptotic proteins (NAG-1 and p53) and cell cycle inhibitor (p21). Furthermore, EGCG significantly inhibited tumor formation as assessed by xenograft models, and this result is accompanied with induction of apoptotic cells and NAG-1 expression in tumor tissue samples. Taken together, these results demonstrate for the first time that EGCG induces apoptosis via ATM/p53-dependent NAG-1 expression in HNSCC, providing an additional mechanistic explanation for the apoptotic activity of EGCG.

Quercetin potentiates UVB-Induced c-Fos expression: implications for its use as a chemopreventive agent

Quercetin (Qu) is currently being investigated as a chemopreventive agent for several cancers, including nonmelanoma skin cancer induced by UV light. We previously reported that Qu degradation has important consequences on signaling and cell biology. In the current study, we report that Qu induces c-Fos mRNA and protein expression through activation of p38 and cAMP-responsive element binding protein (CREB), and Qu potentiates UVB-induced c-Fos expression. Inclusion of ascorbic acid (AA) in cell culture medium stabilizes Qu and completely prevents both Qu- and UVB-induced p38 and CREB activation, leading to a blockade of c-fos gene expression through reduced CREB/cAMP-responsive element binding. AA stabilizes c-Fos mRNA, increasing steady-state levels even when c-fos gene expression is suppressed, but this has no effect on c-Fos protein levels in either mock- or UVB-irradiated cells. We report that Qu blocks mammalian target of rapamycin signaling and inhibits c-Fos protein expression directly through this mechanism because cotreatment with Qu and AA resulted in the complete suppression of UVB-induced c-Fos protein expression even in the presence of significantly increased mRNA levels. We further confirmed that this was not due to increased protein turnover because inhibition of proteasome activity with MG-132 did not raise c-Fos protein levels in Qu+AA-treated cells. Together, these data indicate that although Qu has been reported to have some beneficial properties as a chemopreventive agent, it is also capable of inducing c-fos expression, a cellular event important for the promotion phase of tumor development, if it is not stabilized.

Size-dependent effects of tungsten carbide-cobalt particles on oxygen radical production and activation of cell signaling pathways in murine epidermal cells

Hard metal or cemented carbide consists of a mixture of tungsten carbide (WC) (85%) and metallic cobalt (Co) (5-15%). WC-Co is considered to be potentially carcinogenic to humans. However, no comparison of the adverse effects of nano-sized WC-Co particles is available to date. In the present study, we compared the ability of nano- and fine-sized WC-Co particles to form free radicals and propensity to activate the transcription factors, AP-1 and NF-kappaB, along with stimulation of mitogen-activated protein kinase (MAPK) signaling pathways in a mouse epidermal cell line (JB6 P(+)). Our results demonstrated that nano-WC-Co generated a higher level of hydroxyl radicals, induced greater oxidative stress, as evidenced by a decrease of GSH levels, and caused faster JB6 P(+) cell growth/proliferation than observed after exposure of cells to fine WC-Co. In addition, nano-WC-Co activated AP-1 and NF-kappaB more efficiently in JB6(+/+) cells as compared to fine WC-Co. Experiments using AP-1-luciferase reporter transgenic mice confirmed the activation of AP-1 by nano-WC-Co. Nano- and fine-sized WC-Co particles also stimulated MAPKs, including ERKs, p38, and JNKs with significantly higher potency of nano-WC-Co. Finally, co-incubation of the JB6(+/+) cells with N-acetyl-cysteine decreased AP-1 activation and phosphorylation of ERKs, p38 kinase, and JNKs, thus suggesting that oxidative stress is involved in WC-Co-induced toxicity and AP-1 activation.

Innate and adaptive immunity for the pathobiology of Parkinson's disease

Innate and adaptive immunity affect the pathogenesis of Parkinson's disease (PD). In particular, activation of microglia influences degeneration of dopaminergic neurons. Cell-to-cell interactions and immune regulation critical for neuronal homeostasis also influence immune responses. The links between T cell immunity and nigrostriatal degeneration are supported by laboratory, animal model, and human pathologic investigations. Immune-associated biomarkers in spinal fluids and brain tissue of patients with idiopathic or familial forms of PD provide means to improve diagnosis and therapeutic monitoring. Relationships between oxidative stress, inflammation, and immune-mediated cell death pathways are examined in this review as they are linked to PD pathogenesis. Harnessing the immune system by drugs or by vaccination remain promising future therapeutic options.

Effects of combination of calcium and aspirin on azoxymethane-induced aberrant crypt foci formation in the colons of mice and rats

Human intervention studies have suggested an exciting synergistic action between calcium supplementation and aspirin intake in reducing the risk of colorectal cancer. The aim of this study was to determine whether such a synergy can be demonstrated on azoxymethane (AOM)-induced colon aberrant crypt foci (ACF) formation in mice and rats. Female CF-1 mice and male F344 rats were injected subcutaneously with AOM and then received diet treatments for 8 wk. The basal control diet contained high fat (20% mixed lipids by weight) and low calcium (1.4 mg/g diet) to mimic the average Western diet. The treatment diets contained enriched calcium (5.2 mg calcium/g diet), aspirin (0.2 mg aspirin/g diet), or calcium plus aspirin (5.2 mg calcium plus 0.2 mg aspirin/g diet). Treatment with calcium, aspirin, or their combination significantly decreased the number of total ACF and aberrant crypt per mouse (by 43-59%) or rat (by 23-38%), but statistically significant differences among the 3 groups were not observed. A hint of additivity between calcium and aspirin was observed in mice but not in rats. These results indicate that the combination of calcium and aspirin did not produce a synergistic effect on the ACF formation in AOM-treated mice and rats.

NDRG2 suppresses cell proliferation through down-regulation of AP-1 activity in human colon carcinoma cells

Recently, the anti-tumor activity of N-myc downstream-regulated gene 2 (NDRG2) was elucidated, but the molecular mechanism of how NDRG2 works as a tumor suppressor is not well known. To determine the function of NDRG2 as a tumor suppressor, we established stable cell lines expressing NDRG2 protein or its mutant forms, and studied their effects on tumor cell growth. Interestingly, constitutive expression of wild-type NDRG2 induced the growth retardation of SW620 colon carcinoma cells. Introduction of NDRG2 into SW620 cells induced the decrease of c-Jun phosphorylation at Ser63, followed by the attenuation of activator protein-1 (AP-1) function as a transcriptional activator. Subsequently, the down-regulation of cyclin D1, which is known as a major target for AP-1 transcription activator, resulted in cell cycle arrest at G1/S phase. Additionally, treatment of NDRG2-siRNA on NDRG2-expressing cells has induced the recovery of c-Jun phosphorylation and cyclin D1 expression. Cell proliferation of those cells was also increased compared with untreated cells. NDRG2 mutants of which the phosphorylation sites at C-terminal region were removed by deletion or site-directed mutagenesis have shown no effect on cyclin D1 expression and could not induce cell growth retardation. In conclusion, NDRG2 modulates intracellular signals to control cell cycle through the regulation of cyclin D1 expression via phosphorylation pathway.

c-Jun/AP-1 pathway-mediated cyclin D1 expression participates in low dose arsenite-induced transformation in mouse epidermal JB6 Cl41 cells

Arsenic is a well-documented human carcinogen associated with skin carcinogenesis. Our previous work reveals that arsenite exposure is able to induce cell transformation in mouse epidermal cell JB6 Cl41 through the activation of ERK, rather than JNK pathway. Our current studies further evaluate downstream pathway in low dose arsenite-induced cell transformation in JB6 Cl41 cells. Our results showed that treatment of cells with low dose arsenite induced activation of c-Jun/AP-1 pathway, and ectopic expression of dominant negative mutant of c-Jun (TAM67) blocked arsenite-induced transformation. Furthermore, our data indicated that cyclin D1 was an important downstream molecule involved in c-Jun/AP-1-mediated cell transformation upon low dose arsenite exposure, because inhibition of cyclin D1 expression by its specific siRNA in the JB6 Cl41 cells resulted in impairment of anchorage-independent growth of cells induced by low dose arsenite. Collectively, our results demonstrate that c-Jun/AP-1-mediated cyclin D1 expression is at least one of the key events implicated in cell transformation upon low dose arsenite exposure.

Aspirin induces gastric epithelial barrier dysfunction by activating p38 MAPK via claudin-7

Tight junctions create a paracellular permeability barrier that is breached when nonsteroidal anti-inflammatory drugs cause gastrointestinal injury, including increased gastrointestinal permeability. However, the mechanism by which aspirin affects the function of gastric epithelial tight junctions is unknown. Thus, we examined the effect of aspirin on gastric mucosal barrier properties and tight junction organization using MKN28, a human gastric epithelial cell line that expresses claudin-3, claudin-4, claudin-7, zonula occludens (ZO)-1, and occludin, but not claudin-2 or claudin-5, as determined by immunoblot analysis and immunofluorescent staining. Aspirin (5 mM) treatment of MKN28 gastric epithelial monolayers significantly decreased transepithelial electrical resistance and increased dextran permeability. Both aspirin-mediated permeability and phosphorylation of p38 MAPK were significantly attenuated by SB-203580 (a p38 MAPK inhibitor) but not by U-0126 (a MEK1 inhibitor) or SP-600125 (a JNK inhibitor). Aspirin significantly decreased the quantity of claudin-7 protein produced by MKN28 cells but not the quantity of claudin-3, claudin-4, ZO-1, or occludin. The aspirin-induced decrease in claudin-7 protein was completely abolished by SB-203580 pretreatment. These results demonstrate, for the first time, that claudin-7 protein is important in aspirin-induced gastric barrier loss and that p38 MAPK activity mediates this epithelial barrier dysfunction.

Salicylideneamino-2-thiophenol inhibits inflammatory mediator genes (RANTES, MCP-1, IL-8 and HIF-1alpha) expression induced by tert-butyl hydroperoxide via MAPK pathways in rat peritoneal macrophages

Salicylideneamino-2-thiophenol (Sal) regulated the redox status and the expression of chemokines induced by tert-butyl hydroperoxide (t-BHP). Sal (100 microM) increased reduced/oxidized glutathione (GSH/GSSG) ratios and thiol (SH) levels by 210 and 157%, respectively, and decreased reactive oxygen species (ROS) levels by 60% in t-BHP-treated macrophages. The inductions of regulated upon activation, normal T-cell expressed and secreted (RANTES), monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8) and hypoxia inducible factor-1alpha (HIF-1alpha) by t-BHP (10 microM) were decreased to 250, 80, 80 and 500% by Sal (100 microM), respectively. In the Sal signaling pathway, c-Jun N-terminal kinases (JNK), extracellular signal-regulated kinases (ERK) and p38 signaling protein modulation were decreased by 67, 69 and 119%, respectively, by Sal at 100 microM. Sal (100 microM) also altered cytosol and nuclear NF-kappaB protein expression by 169 and 5%, respectively. Sal also attenuated NF-kappaB nuclear binding activity. Sal thus has a protective effect against t-BHP-induced inflammation and that this, in part, is due to the inhibition of the production of RANTES, MCP-1, IL-8 and HIF-1alpha via the modulation of the NF-kappaB and mitogen-activated protein kinase (MAPK) pathways.

Differential effects of triptolide and tetrandrine on activation of COX-2, NF-kappaB, and AP-1 and virus production in dengue virus-infected human lung cells

Most virus infections induce cycloxygenase-2 (COX-2) expression and subsequent prostaglandin E₂ (PGE₂) production in cells, an inflammatory response that might be detrimental to virus replication and pathogenesis. This response in dengue virus infection remains to be elucidated. Triptolide and tetrandrine, compounds derived from two commonly used Chinese herbs, both demonstrate anti-inflammatory and immunosuppressive effects partly through modulation of COX-2 expression and, hence, may have antiviral effects. In this study, we examined, firstly, the immune response to dengue virus infection with respect to COX-2 expression and PGE₂ production in human lung cells (A549), liver cells (HepG2) and dendritic cells. Secondly, we assessed the potential antiviral effects of triptolide and tetrandrine on dengue virus infection vis-à-vis expression of COX-2, PGE₂, transcription factors, as well as virus production. We found that dengue virus infection enhanced COX-2 expression and PGE₂ production in A549 cells, similarly to the response in dendritic cells, but not in HepG2 cells. In dengue virus-infected A549 cells, nuclear factor κB (NF-κB) and activator protein 1 (AP-1) were also activated, and both were dose-dependently inhibited by triptolide (0.5–4 ng/ml). Tetrandrine (1–10 μM) had no similar immunosuppressive effects and, moreover, at higher concentrations, enhanced NF-κB and AP-1 activity, COX-2 expression and PGE₂ production. However, unexpectedly, tetrandrine, but not triptolide, dose-dependently suppressed dengue virus production in A549 cells, independent of PGE₂ level. Our findings imply that triptolide and tetrandrine may attenuate dengue virus infection in human lung cells, but through distinct pathways.

Equol, a metabolite of the soybean isoflavone daidzein, inhibits neoplastic cell transformation by targeting the MEK/ERK/p90RSK/activator protein-1 pathway

Daidzein and genistein are isoflavones found in soybean. Genistein is known to exhibit anticarcinogenic activities and inhibit tyrosine kinase activity. However, the underlying molecular mechanisms of the chemopreventive activities of daidzein and its metabolite, equol, are not understood. Here we report that equol inhibits 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced neoplastic transformation of JB6 P+ mouse epidermal cells by targeting the MEK/ERK/p90RSK/activator protein-1 signaling pathway. TPA-induced neoplastic cell transformation was inhibited by equol, but not daidzein, at noncytotoxic concentrations in a dose-dependent manner. Equol dose-dependently attenuated TPA-induced activation of activator protein-1 and c-fos, whereas daidzein did not exert any effect when tested at the same concentrations. The TPA-induced phosphorylation of ERK1/2, p90RSK, and Elk, but not MEK or c-Jun N-terminal kinase, was inhibited by equol but not by daidzein. In vitro kinase assays revealed that equol greatly inhibited MEK1, but not Raf1, kinase activity, and an ex vivo kinase assay also demonstrated that equol suppressed TPA-induced MEK1 kinase activity in JB6 P+ cell lysates. Equol dose-dependently inhibited neoplastic transformation of JB6 P+ cells induced by epidermal growth factor or H-Ras. Both in vitro and ex vivo pull-down assays revealed that equol directly bound with glutathione S-transferase-MEK1 to inhibit MEK1 activity without competing with ATP. These results suggested that the antitumor-promoting effect of equol is due to the inhibition of cell transformation mainly by targeting a MEK signaling pathway. These findings are the first to reveal a molecular basis for the anticancer action of equol and may partially account for the reported chemopreventive effects of soybean.

Non-steroidal anti-inflammatory drugs in Parkinson's disease

Parkinson's disease (PD) is known to be a chronic and progressive neurodegenerative disease caused by a selective degeneration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNc). A large body of experimental evidence indicates that the factors involved in the pathogenesis of this disease are several, occurring inside and outside the DAergic neuron. Recently, the role of the neuron-glia interaction and the inflammatory process, in particular, has been the object of intense study by the research community. It seems to represent a new therapeutic approach opportunity for this neurological disorder. Indeed, it has been demonstrated that the cyclooxygenase type 2 (COX-2) is up-regulated in SNc DAergic neurons in both PD patients and animal models of PD and, furthermore, non-steroidal anti-inflammatory drugs (NSAIDs) pre-treatment protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 6 hydroxydopamine (6-OHDA)-induced nigro-striatal dopamine degeneration. Moreover, recent epidemiological studies have revealed that the risk of developing PD is reduced in humans who make therapeutical use of NSAIDs. Consequently, it is hypothesized that they might delay or prevent the onset of PD. However, whether or not these common drugs may also be of benefit to those individuals who already have Parkinson's disease has not as yet been shown. In this paper, evidence relating to the protective effects of aspirin or other NSAIDs on DAergic neurons in animal models of Parkinson's disease will be discussed. In addition, the pharmacological mechanisms by which these molecules can exert their neuroprotective effects will be reviewed. Finally, epidemiological data exploring the effectiveness of NSAIDs in the prevention of PD and their possible use as adjuvants in the therapy of this neurodegenerative disease will also be examined.

Protective effects of a red orange extract on UVB-induced damage in human keratinocytes

UV light is considered one of the major etiological factor in skin aging, cancer and also to systemic impairment such as immunosuppression. Increased production of reactive oxygen species (ROS) and oxidative stress condition are known to play a central role in initiating and driving the signalling events that lead to cellular response following UV irradiation. In the present study we have investigated the photoprotective activity of a standardized extract from red orange (ROE), obtained from three red orange varieties and containing as main active principles phenolic compounds (anthocyanins, flavanones and hydroxycinnamic acids) and ascorbic acid. The aim of this study was to evaluate the efficacy of ROE in modulating cellular responses to UVB in human keratinocytes (HaCaT). Our data indicate that ROE is potentially able to efficiently counteract UVB-induced response, and in particular some events associated to inflammation and apoptosis, such as NF-kB and AP-1 translocation and procaspase-3 cleavage. This activity is probably due to a block of cellular oxidative stress-related events. Thus we can propose ROE as a useful natural standardised extract in skin photoprotection with promising applications in the field of dermatology.

Aspirin reduces the outcome of anticancer therapy in Meth A-bearing mice through activation of AKT-glycogen synthase kinase signaling

Aspirin displays, at millimolar concentrations, several mechanisms independent from its ability to inhibit cyclooxygenases. Occasionally, the mechanisms displayed in vitro have been clearly related to an effect of clinical relevance in vivo. An expanding literature has been focusing on the cytoprotective effect of aspirin in neurodegenerative disorders and the activation of AKT pathway in neuroprotection and induction of resistance to anticancer drugs. In this work, we tested the ability of aspirin to activate the AKT survival pathway in methylcholanthrene-induced fibrosarcoma cells (Meth A) transplanted into BALB/c nude mice and the clinical effect of aspirin cotreatment during etoposide (VP-16)-based anticancer therapy. We found that cotreatment with aspirin reduced VP-16-induced apoptosis and activated AKT in vitro and in vivo. In Meth A-bearing mice, aspirin administration also activated glycogen synthase kinase-3 and reduced the activity and the efficacy of anticancer therapy in VP-16 cotreated animals. Our data suggest that the antiapoptotic effect of aspirin operates in vivo through the activation of AKT-glycogen synthase kinase pathway causing a decrease in the outcome of VP-16-based therapy. These findings could have clinical relevance in treatment of human malignancies.

Nuclear factor-kappa B-independent anti-inflammatory action of salicylate in human endothelial cells: induction of heme oxygenase-1 by the c-jun N-terminal kinase/activator protein-1 pathway

In contrast to aspirin, salicylate, its active metabolite, possesses profound anti-inflammatory properties without blocking cyclooxygenase. Inhibition of the transcription factor nuclear factor-kappaB (NF-kappaB) has been discussed to play a role in the anti-inflammatory profile of salicylate. However, NF-kappaB-independent effects of salicylate have been assumed but have up to now been poorly investigated. Therefore, the aim of the present study was to investigate NF-kappaB-independent anti-inflammatory mechanisms of salicylate in human umbilical vein endothelial cells using interleukin-4 (IL-4) as NF-kappaB-independent proinflammatory stimulus and P-selectin as inflammatory read-out parameter. Using quantitative real-time reverse transcription-polymerase chain reaction, we found that salicylate decreases IL-4-induced P-selectin expression. As judged by Western blot analysis, salicylate increased endothelial heme oxygenase-1 (HO-1) protein levels. Using both the HO-1 inhibitor tin(II) protoporphyrin IX and HO-1 antisense oligonucleotides, we causally linked the induction of HO-1 to the decrease of P-selectin. Moreover, we were interested in the signaling mechanisms leading to the up-regulation of HO-1 by salicylate. c-Jun NH2-terminal kinase (JNK) was found to be activated by salicylate, and we could causally link this activation to the induction of HO-1 by using the JNK inhibitor 1,9-pyrazoloanthrone. By applying activator protein-1 (AP-1) decoys, it was shown that the transcription factor AP-1 is crucially involved in the up-regulation of HO-1 downstream of JNK. In summary, our study introduces HO-1 as novel NF-kappaB-independent anti-inflammatory target of salicylate in human endothelial cells. Moreover, we elucidated the JNK/AP-1 pathway as crucial for the induction of HO-1 by salicylate.

Galectin-3 in macrophage-like cells exposed to immunomodulatory drugs

During the last few decades, the effects of immunomodulatory drugs on numerous molecules and biological processes have been widely studied. Nevertheless, the relationship between immunomodulatory drugs and lectin expression/function is still to be elucidated. In this study, we used THP-1-derived macrophages to investigate the effects of non-steroidal anti-inflammatory drugs (aspirin and indomethacin) and glucocorticoids (hydrocortisone and dexamethasone) on galectin-3, a multifunctional beta-galactoside binding lectin, which in general acts as a strong pro-inflammatory signal. The results showed that all immunomodulatory drugs applied in clinically relevant doses affect both the gene (LGALS3) and protein expression level of galectin-3. The provoked changes on protein level are qualitatively and quantitatively different comparing to the effects on galectin-3 mRNA level, and depend on the differentiation state of the cell, drug type and applied concentration as well as on time of the exposure. Our data revealed galectin-3 as a new target molecule of immunomodulatory drugs, thus suggesting an additional pathway of their action on immune response.