The function and mechanism of COX-2 in angiogenesis of gastric cancer cells

Microbiota and angiogenesis in the intestinal vasculature

The gut microbiota is responsible for several metabolic functions, producing various metabolites with numerous roles for the host. The gut microbiota plays a key role in constructing the microvascular network in the intestinal villus, depending on the Paneth cells, strategically positioned to coordinate the development of both the microbiota and the microvasculature. The gut microbiota secretes several molecules and chemokines involved in the induction of the secretion of pro-angiogenic factors.

A Network Pharmacology Approach for Uncovering the Antitumor Effects and Potential Mechanisms of the Sijunzi Decoction for the Treatment of Gastric Cancer

Background

Sijunzi decoction (SJZD), a classic Chinese formula, has been clinically used for the treatment of gastrointestinal disorders. However, few studies have uncovered its antitumor effects and its potential mechanisms against gastric cancer (GC). Therefore, this work aimed to identify the active compounds and putative targets of the SJZD and to further explore the potential mechanisms involved in the treatment of GC.

Materials and Methods

The active compounds and potential targets of the SJZD and related genes for GC treatment were collected from a public database. Traditional Chinese medicine (TCM)-compound-target-disease networks, Venn diagrams, protein–protein interactions (PPIs), gene ontology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to obtain the bioactive compounds, key targets, and potential pathways. Next, the human gastric adenocarcinoma cell line NUGC-4 was inoculated subcutaneously into the right flank of NCG mice to build a tumor-bearing mouse model to further verify the findings.

Results

There were 117 compounds in the SJZD in total. The SJZD and GC had 161 and 3288 potential targets, respectively, among which 123 targets overlapped. The network analysis showed that quercetin, kaempferol formononetin, ginsenoside, atractylenolide III, etc., were bioactive molecules. The tumor necrosis factor (TNF), interleukin-6 (IL-6), cellular tumor antigen p53 (TP53), transcription factor AP-1 (JUN), and vascular endothelial growth factor A (VEGFA) were potential targets. A KEGG pathway enrichment analysis revealed 110 pathways involved in the pathways for cancer, including the PI3K-AKT signaling pathway. Validation experiments showed that the SJZD inhibited tumor growth and induced apoptosis in tumor cells. In addition, the SJZD downregulated expressions of VEGFA, iNOS, COX-2, and Bax/Bcl2 and inhibited the expressions of p-PI3K and p-AKT.

Conclusion

The SJZD treats GC by inhibiting blood vessel hyperplasia and inducing cell apoptosis by regulating the PI3K/AKT pathway.

Cyclooxygenase-2 expression is associated with infiltration of inflammatory cells in oral and skin canine melanomas

Melanoma is a fast-growing tumour in dogs and represents 7% of the total malignant neoplasms from the skin and is the most common tumour found in the oral cavity. In these tumours, high expression of cyclooxygenase-2 (COX-2) is associated with a poor prognosis. The aim of this study was to verify if the overexpression of COX-2 is related to the modulation of lymphocytes and if it is associated with the angiogenic and proliferative capacity of the melanoma. Canine melanoma samples (n = 85) were analysed by immunohistochemistry to detect the expression of S-100, Melan-A, PNL-2, COX-2, Factor VIII, Ki-67 and immune cells markers (CD3, CD4, FOXP3 and MAC387); and expression levels of MAC387, NOS and CD206 were determined by immunofluorescence. Our study showed a concurrent difference between the expression of COX-2 and inflammatory cell infiltration: Oral melanomas showed positivity for COX-2 in 34% of the cases and this expression was associated with CD3 positivity in the inflammatory infiltrate and angiogenesis; whereas cutaneous melanomas presented positivity for COX-2 in 42% of the cases and this expression was associated with positive staining for CD3, CD4, FOXP3 and MAC387. These markers are associated with inflammatory cells, angiogenesis and proliferation. Interestingly, melanomas were highly infiltrated by FOXP3+ cells, this is related to angiogenesis, whereas CD3, CD4 and MAC387 expression was only associated with cutaneous melanomas. The macrophage profile analysis showed that both oral and cutaneous melanomas with low COX-2 expression have an M1 phenoptype, whereas the cases with high COX-2 expression demonstrate a hybrid M1/M2 profile pattern. We concluded that the COX-2 is overexpressed in 42% of cutaneous melanomas and in 34% of oral melanomas, with a direct association with angiogenesis, proliferation, and intratumoral lymphocyte infiltration. We propose that COX-2 is a key regulator of immune cell infiltration and may drive tumour associated macrophage activation.

Postoperative peritoneal adhesion: an update on physiopathology and novel traditional herbal and modern medical therapeutics

Postoperative peritoneal adhesion (PPA) is a serious clinical condition that affects the high percentage of patients after abdominal surgery. In this review, we have tried to focus on pathophysiology and different underlying signal pathways of adhesion formation based on recent progress in the molecular and cellular mechanisms. Also, the strategies, developed based on traditional herbal and modern medicines, to prevent and treat the PPA via regulation of the molecular mechanisms were investigated. The search engines such as Google Scholar, PubMed, Scopus, and Science Direct have been used to evaluate the current literature related to the pathogenesis of adhesion formation and novel products. Recently, different mechanisms have been defined for adhesion formation, mainly categorized in fibrin formation and adhesion fibroblast function, inflammation, and angiogenesis. Therefore, the suppression of these mechanisms via traditional and modern medicine has been suggested in several studies. While different strategies with encouraging findings have been developed, most of the studies showed contradictory results and were performed on animals. The herbal products have been introduced as safe and effective agent which can be considered in future preclinical and clinical studies. Although a wide range of therapeutics based on traditional and modern medicines have been suggested, there is no agreement in the efficacy of these methods to prevent or treat adhesion formation after surgeries. Further basic and clinical researches are still needed to propose the efficiency of recommended strategies for prevention and treatment of PPA.

Ferulic Acid Prevents Angiogenesis Through Cyclooxygenase-2 and Vascular Endothelial Growth Factor in the Chick Embryo Chorioallantoic Membrane Model

Objectives

This study was designed to verify the antiangiogenic activity of ferulic acid (FA) and its potency to inhibit cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) expression in the chorioallantoic membrane (CAM) model. Moreover, we verified its mechanism of action by docking the molecule on COX-2, tyrosine kinase, and VEGF-2 proteins in silico.

Materials and Methods

An antiangiogenesis assay of FA at doses of 30, 60, and 90 μg was performed using the CAM of chicken eggs that were 9 days old and stimulated by 60 ng of basic fibroblast growth factor. Celecoxib (60 μg) was used as the reference drug. The inhibitory activity on VEGF and COX-2 expression was determined by immunohistochemistry assay. Molecular docking of FA was accomplished by Molegro Virtual Docker program ver. 5.5 on COX-2 enzyme (PDB ID 1CX2), tyrosine kinase receptor (PDB ID 1XKK), and VEGF-2 receptor (PDB ID 4ASD).

Results

FA at doses of 30, 60, and 90 μg significantly prevented angiogenesis in the CAM model, which was represented as inhibitory activity against endothelial cells of blood vessels (42.6-70.7%) and neovascularization (43.0-86.6%). The inhibitory activity of FA against VEGF expression was stronger than its action on COX-2 expression. Molecular docking on VEGF-2 receptor resulted in an RS value of FA of -73.844 kcal/mol and for celecoxib it was -94.557 kcal/mol. The RS value on tyrosine kinase of FA was -84.954 kcal/mol, while on celecoxib it was -93.163 kcal/mol. Docking on COX-2 receptor gave an RS value of FA of -73.416 kcal/mol, while for celecoxib it was -118.107 kcal/mol.

Conclusion

Reductions in VEGF-2 and COX-2 expression due to treatment with FA at the dose range 30-90 μg appeared to be related to angiogenesis inhibition, which was shown by two parameters, namely inhibition of neovascularization and endothelial cell growth in blood vessels. It was concluded that FA is a promising antiangiogenic therapeutic agent especially at the early stage, and this activity can arise from inhibitory action on COX-2 and VEGF-2 proteins.

Endotoxin-induced changes in expression of cyclooxygenase isoforms in the lamellar tissue of extracorporeally haemoperfused equine limbs

Angiogenesis and sepsis‐related equine laminitis have several features in common. Both events can be induced by endotoxin (lipopolysaccharide— LPS) and both are associated with increased expression of the enzyme cyclooxygenase (COX), of which two isoforms (COX‐1 and COX‐2) exist. To examine the causal relationship between LPS exposure and COX expression and to investigate the tissue distribution of COX in the LPS‐exposed tissue, the technique of extracorporeal haemoperfusion of isolated equine forelimbs was utilized. Perfusion was performed for 10 hr under physiological conditions (control‐perfused limbs, n = 5) and with addition of 80 ng/L of endotoxin (LPS‐perfused limbs; n = 5). After perfusion, samples of lamellar tissue were collected from the dorsal aspect of the hoof wall. Additional control samples were collected from three non‐perfused limbs. Immunohistochemical analysis was performed using antibodies against COX‐1 and COX‐2, and intensity of immunohistochemical staining was scored for each isoform. In the lamellar tissue of control‐ and LPS‐perfused limbs, there was no significant difference in COX‐1 staining intensity and distribution, whereas COX‐2 expression was significantly increased in LPS‐perfused limbs (especially in endothelial cells, fibroblasts and intravasal leucocytes as well as in epidermal basal cells at the base of the primary epidermal lamellae). These results suggest that COX‐2 and its metabolites are involved in the initiation of pathological changes seen in sepsis‐associated events such as sepsis‐related laminitis. In such cases, COX‐2 could therefore be an important therapeutic target; however, early therapy may be required as increase in COX‐2 expression occurs within 10 hr after LPS exposure.

4,5-Diaryl 3(2H)Furanones: Anti-Inflammatory Activity and Influence on Cancer Growth

Apart from their anti-inflammatory action, COX inhibitors have gathered the interest of many scientists due to their potential use for the treatment and prevention of cancer. It has been shown that cyclooxygenase inhibitors restrict cancer cell growth and are able to interact with known antitumor drugs, enhancing their in vitro and in vivo cytotoxicity. The permutation of hydrophilic and hydrophobic aryl groups in COX inhibitors leads to cardinal changes in the biological activity of the compounds. In the present study, thirteen heterocyclic coxib-like 4,5-diarylfuran-3(2H)-ones and their annelated derivatives—phenanthro[9,10-b]furan-3-ones—were synthesized and studied for anti-inflammatory and COX-1/2 inhibitory action and for their cytotoxic activity on the breast cancer (MCF-7) and squamous cell carcinoma (HSC-3) cell lines. The F-derivative of the –SOMe substituted furan-3(2H)-ones exhibited the best activity (COX-1 IC₅₀ = 2.8 μM, anti-inflammatory activity (by carrageenan paw edema model) of 54% (dose 0.01 mmol/kg), and MCF-7 and HSC-3 cytotoxicity with IC₅₀ values of 10 μM and 7.5 μM, respectively). A cytotoxic effect related to the COX-1 inhibitory action was observed and a synergistic effect with the anti-neoplastic drugs gefitinib and 5-fluorouracil was found. A phenanthrene derivative exhibited the best synergistic effect with gefitinib.

Mechanisms of angiogenesis in microbe-regulated inflammatory and neoplastic conditions

Commensal microbiota inhabit all the mucosal surfaces of the human body. It plays significant roles during homeostatic conditions, and perturbations in numbers and/or products are associated with several pathological disorders. Angiogenesis, the process of new vessel formation, promotes embryonic development and critically modulates several biological processes during adulthood. Indeed, deregulated angiogenesis can induce or augment several pathological conditions. Accumulating evidence has implicated the angiogenic process in various microbiota-associated human diseases. Herein, we critically review diseases that are regulated by microbiota and are affected by angiogenesis, aiming to provide a broad understanding of how angiogenesis is involved and how microbiota regulate angiogenesis in microbiota-associated human conditions.

COX-2 regulates Snail expression in gastric cancer via the Notch1 signaling pathway

The conversion of arachidonic acid into prostaglandins by cyclooxygenase (COX)-2 contributes to the biological properties of malignant tumours. During the initiation and development of various tumours, the Notch family plays a key role. However, the association between COX‑2 and the Notch family in gastric cancer (GC) remains unclear. The present study aimed to clarify the mechanisms through which COX‑2 participates in the pathogenesis of GC. Quantitative PCR and western blot analysis were used to detect the expression of Notch family members and COX‑2 in human GC and paracancerous tissues, GES‑1 cells and GC cell lines (AGS, SGC‑7901, BGC‑823, and MGC‑803) treated with or without celecoxib, prostaglandin E2 and small interfering RNA (siRNA). A CCK‑8 assay was performed to detect the proliferation of GC cells transfected with siRNA against COX‑2 (si‑COX‑2). A high mRNA expression of Notch1 and a decreased expression of Notch-1 intracellular active domain (N1IC) in GC were found to be related to the depth of invasion and TNM staging. The mRNA levels of Notch2, Notch3, Jagged1 and N2IC were found to be high in GC. A High expression of COX‑2 was associated with poorly differentiated and deeply invasive GC. COX‑2 and Notch1 exhibited an inverse expression pattern in the GES‑1 cells and different GC cell lines; the inhibition of COX‑2 increased Notch1 expression and activated the GC cells, whereas Notch1 downregulation had the opposite effect. Notch1 exhibited varying effects on Snail in the GC cell lines. The downregulation of COX‑2 expression significantly inhibited the proliferation of GC cells. On the whole, the expression of Notch signalling molecules differed in GC. COX‑2 inversely regulated Notch1 in GC and partially depended on the Notch1 signalling pathway in altering the expression of Snail.

Gender differences in hypoxic acclimatization in cyclooxygenase-2-deficient mice

The aim of this study was to determine the effect of cyclooxygenase‐2 (COX‐2) gene deletion on the adaptive responses during prolonged moderate hypobaric hypoxia. Wild‐type (WT) and COX‐2 knockout (KO) mice of both genders (3 months old) were exposed to hypobaric hypoxia (~0.4 ATM) or normoxia for 21 days and brain capillary densities were determined. Hematocrit was measured at different time intervals; brain hypoxia‐inducible factor ‐1α (HIF‐1α), angiopoietin 2 (Ang‐2), brain erythropoietin (EPO), and kidney EPO were measured under normoxic and hypoxic conditions. There were no gender differences in hypoxic acclimatization in the WT mice and similar adaptive responses were observed in the female KO mice. However, the male KO mice exhibited progressive vulnerability to prolonged hypoxia. Compared to the WT and female KO mice, the male COX‐2 KO mice had significantly lower survival rate and decreased erythropoietic and polycythemic responses, diminished cerebral angiogenesis, decreased brain accumulation of HIF‐1α, and attenuated upregulation of VEGF, EPO, and Ang‐2 during hypoxia. Our data suggest that there are physiologically important gender differences in hypoxic acclimatization in COX‐2‐deficient mice. The COX‐2 signaling pathway appears to be required for acclimatization in oxygen‐limiting environments only in males, whereas female COX‐2‐deficient mice may be able to access COX‐2‐independent mechanisms to achieve hypoxic acclimatization.

Environmental immune disruptors, inflammation and cancer risk

An emerging area in environmental toxicology is the role that chemicals and chemical mixtures have on the cells of the human immune system. This is an important area of research that has been most widely pursued in relation to autoimmune diseases and allergy/asthma as opposed to cancer causation. This is despite the well-recognized role that innate and adaptive immunity play as essential factors in tumorigenesis. Here, we review the role that the innate immune cells of inflammatory responses play in tumorigenesis. Focus is placed on the molecules and pathways that have been mechanistically linked with tumor-associated inflammation. Within the context of chemically induced disturbances in immune function as co-factors in carcinogenesis, the evidence linking environmental toxicant exposures with perturbation in the balance between pro- and anti-inflammatory responses is reviewed. Reported effects of bisphenol A, atrazine, phthalates and other common toxicants on molecular and cellular targets involved in tumor-associated inflammation (e.g. cyclooxygenase/prostaglandin E2, nuclear factor kappa B, nitric oxide synthesis, cytokines and chemokines) are presented as example chemically mediated target molecule perturbations relevant to cancer. Commentary on areas of additional research including the need for innovation and integration of systems biology approaches to the study of environmental exposures and cancer causation are presented.

Inflammation and Oral Cancer: An Update Review on Targeted Therapies

In the recent past, numerous inflammation-mediated molecular pathways have been explored and studied as important events in carcinogenesis with respect to oral squamous cell carcinoma (OSCC). These pathways are engaged in numerous stages during tumorigenesis; which includes processes, like initiation, promotion, malignant conversion, invasion and metastasis. The inflammation-mediated/related carcinogenesis pathways reported in OSCC involves COX-2, epidermal growth factor receptor (EGFR), p38a MAP kinase, NF-kB, STAT, RhoC, PPARy, etc. Many researchers are trying to target these pathways to explore more effective therapeutic interventions in OSCC. The aim of the present paper is to briefly discuss these pathways, with special emphasis on the therapeutic utilities. The therapeutic targets for the aforementioned pathways were searched in databases pubmed and scopus with no restriction to date of publication. Articles published in English medical literature on OSCC were selected for discussion. The recent combinations, modifications in dosage and frequency, or the use of new anti-inflammatory compounds, may exemplify the next generation care for OSCC.

Flavonoids as a scaffold for development of novel anti-angiogenic agents: An experimental and computational enquiry

Relationship between structural diversity and biological activities of flavonoids has remained an important discourse in the mainstream of flavonoid research. In the current study anti-angiogenic, cytotoxic, antioxidant and cyclooxygenase (COX) inhibitory activities of diverse class of flavonoids including hydroxyl and methoxy substituted flavones, flavonones and flavonols have been evaluated in the light of developing flavonoids as a potential scaffold for designing novel anti-antiangiogenic agents. We demonstrate anti-angiogenic potential of flavonoids using in vivo chorioallantoic membrane model (CAM) and further elaborate the possible structural reasoning behind observed anti-angiogenic effect using in silico methods. Additionally, we report antioxidant potential and kinetics of free radical scavenging activity using DPPH and SOR scavenging assays. Current study indicates that selected flavonoids possess considerable COX inhibition potential. Furthermore, we describe cytotoxicity of flavonoids against selected cancer cell lines using MTT cell viability assay. Structural analysis of in silico docking poses and predicted binding free energy values are not only in accordance with the experimental anti-angiogenic CAM values from this study but also are in agreement with the previously reported literature on crystallographic data concerning EGFR and VEGFR inhibition.

Anti-angiogenic effects of resveratrol in combination with 5-fluorouracil on B16 murine melanoma cells

5-Fluorouracil (5-FU) has been used as a chemotherapeutic drug for various types of cancer, although the development of resistance remains a major limitation for its use in clinical settings. In the present study, the anti-angiogenic effects of resveratrol and 5-FU either alone or in combination were examined in a B16 murine melanoma model. Co-treatment using resveratrol and 5-FU inhibited cell proliferation more efficiently compared with use of either drug alone and the antiproliferative effect coincided with changes in the expression levels of AMP-activated protein kinase (AMPK), cyclooxygenase-2, vasodilator-stimulated phosphoprotein (VASP) and vascular endothelial growth factor (VEGF). Furthermore, co-treatment with resveratrol and 5-FU reduced tumor growth compared with that in the control group and this growth-inhibitory effect was associated with changes in the expression levels of AMPK, VASP and VEGF. Immunohistochemical staining for angiogenesis demonstrated that co-treatment with resveratrol and 5-FU reduced the number of microvascular vessels compared with that in the control group. These results suggested that co-treatment with resveratrol and 5-FU suppressed cell growth and angiogenesis in B16 murine melanoma tumors.

Interactions between osteopontin and vascular endothelial growth factor: Implications for cancer

For this comprehensive review, 257 publications with the keywords "osteopontin" or "OPN" and "vascular endothelial growth factor" or "VEGF" in PubMed were screened (time frame from year 1996 to year 2014). 37 articles were excluded because they were not focused on the interactions between these molecules, and papers relevant for transformation-related phenomena were selected. Osteopontin (OPN) and vascular endothelial growth factor (VEGF) are characterized by a convergence in function for regulating cell motility and angiogenesis, the response to hypoxia, and apoptosis. Often, they are co-expressed or one molecule induces the other, however, in some settings OPN-associated pathways and VEGF-associated pathways are distinct. Their relationships affect the pathogenesis in cancer, where they contribute to progression and angiogenesis and serve as markers for poor prognosis. The inhibition of OPN may reduce VEGF levels and suppress tumor progression. In vascular pathologies, these two cytokines mediate remodeling, but may also perpetuate inflammation and narrowing of the arteries. OPN and VEGF are elevated and contribute to vascularization in inflammatory diseases.

Impact of combined proglumide and celecoxib on cell proliferation and PGE2 secretion in human gastric cancer cell line BGC-823

AIM: To investigate the effect of proglumide (a gastrin receptor antagonist) and celecoxib [a selective cyclooxygenase-2 (COX-2) inhibitor] on cell proliferation and COX-2, 15-hydroxyprostaglandin dehydrogenase (15-PGDH) and prostaglandin E2 (PGE2) expression in human gastric cancer cell line BGC-823.

METHODS: BGC-823 cells were treated with proglumide and celecoxib, alone or in combination. MTT assay was used to detect the proliferation of BGC-823 cells. Real-time PCR was used to detect COX-2 and 15-PGDH mRNA expression. Western blot was used to detect COX-2 and 15-PGDH protein expression, and ELISA was used to determine the content of PGE2 in culture medium.

RESULTS: Proglumide and celecoxib inhibited the growth of BGC-823 cells in a dose- and time-dependent manner. Treatment with combined proglumide (6 mmol/L, less than IC₅₀) and celecoxib (50 μmol/L, less than IC₅₀) for 48 h was associated with a significantly higher inhibition rate than either of the agents alone (65.1% ± 7.7% vs 38.1% ± 7.1%, 32.6% ± 3.3%, P < 0.05). Proglumide and celecoxib down-regulated the expression of COX-2 mRNA and protein, and up-regulated the expression of 15-PGDH mRNA and protein in BGC-823 cells, and the effects of combined treatment were more significant than treatment with either of the agents alone (P < 0.05 vs proglumide; P < 0.01 vs celecoxib). Proglumide and celecoxib reduced the secretion of PGE2, and the effects of combined treatment were more significant than either of the agents alone (P < 0.05 vs proglumide; P < 0.01 vs celecoxib).

CONCLUSION: Proglumide and celecoxib inhibit the growth of cultured BGC-823 cells time- and dose-dependently, possibly by down-regulating the expression of COX-2 mRNA and protein, up-regulating the expression of 15-PGDH mRNA and protein, and reducing PGE2 synthesis or secretion. Combined use of proglumide and celecoxib has a synergistic effect.

Effects of cyclooxygenase-2 gene silencing on the biological behavior of SKOV3 ovarian cancer cells

The aim of the present study was to investigate the effects of plasmid-mediated RNA interference targeting of cyclooxygenase-2 (COX-2) on the biological behaviors of SKOV3 human ovarian cancer cells and to analyze the function of COX-2 in carcinogenesis and development of ovarian cancer. A COX-2 small hairpin (sh)RNA sequence was designed and synthesized and pGPU6-COX-2-shRNA plasmids were constructed. The recombinant vector plasmids were stably transfected into SKOV3 cells. The mRNA and protein expression of COX-2 was subsequently analyzed by quantitative polymerase chain reaction and western blot analysis, respectively. MTT and colony formation assays were used to detect the cellular proliferation ability and flow cytometry was performed to detect phase changes in the cell cycle. Finally, a Transwell assay was used to detect cell invasion. The SKOV3 cells, transfected with recombinant vector plasmids, and control cells, were injected into nude mice and the tumor emergence time, volume and weight were measured. The impact of COX-2 gene silencing on the growth of xenograft tumors in nude mice was analyzed. Following transfection of the pGPU6-COX-2-shRNA plasmid, in vitro analyses indicated that the shRNA efficiently suppressed the mRNA and protein expression of COX-2. COX-2 gene silencing significantly inhibited the proliferation and invasion ability of SKOV3 cells, leading to cell cycle arrest in G1. The tumor formation time in the interference group was significantly prolonged, and the tumor volume and weight were significantly decreased, as compared with the control group. Plasmid-mediated shRNA was shown to effectively silence COX-2 expression in SKOV3 ovarian cancer cells. It was identified that COX-2 functioned in regulating proliferation, cell cycle and invasion of ovarian cancer cells. These findings provided a theoretical basis for determining the function of COX-2 in the development of ovarian cancer and suggested that COX-2 may be an effective target for gene therapy and clinical applications.

Celecoxib decreases growth and angiogenesis and promotes apoptosis in a tumor cell line resistant to chemotherapy

BACKGROUND

During the last few years it has been shown in several laboratories that Celecoxib (Cx), a non-steroidal anti-inflammatory agent (NSAID) normally used for pain and arthritis, mediates antitumor and antiangiogenic effects. However, the effects of this drug on a tumor cell line resistant to chemotherapeutical drugs used in cancer have not been described.

RESULTS

Cx reduces angiogenesis in the chick embryonic chorioallantoic membrane assay (CAM), inhibits the growth and microvascular density of the murine TA3-MTXR tumor, reduces microvascular density of tumor metastases, promotes apoptosis and reduces vascular endothelial growth factor (VEGF) production and cell proliferation in the tumor.

CONCLUSION

The antiangiogenic and antitumor Cx effects correlate with its activity on other tumor cell lines, suggesting that Prostaglandins (PGs) and VEGF production are involved. These results open the possibility of using Celecoxib combined with other experimental therapies, ideally aiming to get synergic effects.

Effect of celecoxib plus standard chemotherapy on serum levels of vascular endothelial growth factor and cyclooxygenase-2 in patients with gastric cancer

Elevated serum levels of vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) are associated with poor prognosis in patients with gastric cancer. Little is known regarding the clinical benefits of combining celecoxib, a selective inhibitor of COX-2, with standard chemotherapy regimens for the treatment of gastric cancer patients. In this study, we investigated the effect of the combinatorial use of celecoxib with standard chemotherapy on the serum levels of VEGF and COX-2 in patients with gastric cancer. In our study, 80 patients with gastric cancer who underwent laparoscopic radical surgery were randomized into two groups, the combination [celecoxib plus standard oxaliplatin, leucovorin and 5-fluorouracil (FOLFOX4) chemotherapy, n=40] and the FOLFOX4 alone (n=40) groups. In the combination group, celecoxib was orally administered to the patients (400 mg, twice daily). The serum levels of VEGF and COX-2 were measured by ELISA prior to and following surgery. We detected no significant difference in the serum levels of VEGF and COX-2 between the combination and FOLFOX4 alone groups prior to chemotherapy (P>0.05). However, after 6 cycles of chemotherapy, there was a greater decrease in the serum levels of VEGF and COX-2 in the combination group compared to those in the FOLFOX4 group (P<0.01). In addition, the serum levels of VEGF and COX-2 were closely correlated in patients with gastric adenocarcinoma prior to treatment. Our data indicated that, when combined with standard chemotherapy, celecoxib may reduce the serum levels of VEGF and COX-2, suggesting that COX-2 inhibitors may be of therapeutic value through the inhibition of tumor angiogenesis and the prevention of recurrence or metastasis. Thus, celecoxib may be a useful adjuvant agent to standard chemotherapy in patients with advanced gastric cancer.

Role of cyclooxygenase-2 in gastric cancer development and progression

Although the incidence of gastric cancer has been declining in recent decades, it remains a major public health issue as the second leading cause of cancer death worldwide. In China, gastric cancer is still the main cause of death in patients with malignant tumors. Most patients are diagnosed at an advanced stage and mortality is high. Cyclooxygenase-2 (COX-2) is a rate-limiting enzyme in prostanoid synthesis and plays an important role in the development and progression of gastric cancer. The expression of COX-2 in gastric cancer is upregulated and its molecular mechanisms have been investigated. Helicobacter pylori infection, tumor suppressor gene mutation and the activation of nuclear factor-kappa B may be responsible for the elevated expression of COX-2 in gastric cancer. The mechanisms of COX-2 in the development and progression of gastric cancer are probably through promoting the proliferation of gastric cancer cells, while inhibiting apoptosis, assisting angiogenesis and lymphatic metastasis, and participating in cancer invasion and immunosuppression. This review is intended to discuss, comment and summarize recent research progress on the role of COX-2 in gastric cancer development and progression, and elucidate the molecular mechanisms which might be involved in the carcinogenesis.

Oral lichen planus: focus on etiopathogenesis

Lichen planus is a chronic mucocutaneous inflammatory disease, which frequently affects the oral mucosa of white females over 40 years old. Its aetiology remains uncertain and the pathogenesis is still the object of much speculation. The present paper presents the most well known antigens, and describes the action of different cells and proteins associated with the development of that disease, as well as the possible agents involved with its malignant transformation. Different external agents, especially virus, and internal agents, like stress, and the heat shock protein antigen expression, associated or not, can alter the basal keratinocytes of the oral mucosa making them susceptible to apoptosis by CD8(+) cytotoxic T cell as well as activate matrix metalloproteinase and mast cell degranulation, which produce a great range of inflammatory mediators and cytokines determining the clinical onset of the disease. Regarding carcinogenesis, since it is a complex process and presents multifactorial origin, it is believed that there may be a synergism between intrinsic, such as inflammation mediators, and extrinsic agents (tobacco, alcohol, viral infections) for the OLP malignant transformation to occur. However, further studies are needed to better understand the origin, pathogenesis and process of malignant transformation of OLP.

Sinomenine hydrochloride enhancement of the inhibitory effects of anti-transferrin receptor antibody-dependent on the COX-2 pathway in human hepatoma cells

Transferrin receptor (TfR) has been used as a target for the antibody-based therapy of cancer due to its higher expression in tumors relative to normal tissues. Great potential has been shown by anti-TfR antibodies combined with chemotherapeutic drugs as a possible cancer therapeutic strategy. In our study, we investigated the anti-tumor effects of anti-TfR monoclonal antibody (mAb) alone or in combination with sinomenine hydrochloride in vitro. Results suggested that anti-TfR mAb or sinomenine hydrochloride could induce apoptosis, inhibit proliferation, and affect the cell cycle. A synergistic effect was found in relation to tumor growth inhibition and the induction of apoptosis when anti-TfR mAb and sinomenine hydrochloride were used simultaneously. The expression of COX-2 and VEGF protein in HepG2 cells treated with anti-TfR mAb alone was increased in line with increasing dosage of the agent. In contrast, COX-2 expression was dramatically decreased in HepG2 cells treated with sinomenine hydrochloride alone. Furthermore, we demonstrated that the inhibitory effects of sinomenine hydrochloride and anti-TfR mAb administered in combination were more prominent than when the agents were administered singly. To sum up, these results showed that the combined use of sinomenine hydrochloride and anti-TfR mAb may exert synergistic inhibitory effects on human hepatoma HepG2 cells in a COX-2-dependent manner. This finding provides new insight into how tumor cells overcome the interference of iron intake to survive and forms the basis of a new therapeutic strategy involving the development of anti-TfR mAb combined with sinomenine hydrochloride for liver cancer.

Lentivirus-mediated siRNA targeting VEGF inhibits gastric cancer growth in vivo

Vascular endothelial growth factor (VEGF), a crucial promoter of blood vessel growth, not only stimulates endothelial cell proliferation, migration and survival, but also increases vascular permeability. The promotion of angiogenesis is a well-known prerequisite for tumor growth, invasion and metastasis. Evidence has shown that VEGF is overexpressed in many types of tumor tissues. Small interfering RNA (siRNA) targeting VEGF may effectively suppress cell proliferation and induce apoptosis in tumor cells. In this study, we aimed to evaluate whether lentivirus-mediated siRNA targeting VEGF inhibits gastric cancer growth in vivo. The transfection of VEGF siRNA into SGC7901 human gastric cancer cells downregulated the expression of VEGF and Bcl-2, but upregulated the expression of p21. In a nude mouse model of subcutaneous xenografts, 24 days after VEGF siRNA treatment, the tumor volume and weight were significantly smaller in the VEGF siRNA group compared to the control scrambled siRNA group. Furthermore, the expression of VEGF, sirtuin 1 (SIRT1), survivin and Bcl-2 was downregulated, whereas the expression of p53 and p21 was upregulated in the tumor cells, indicating that VEGF siRNA induced apoptosis in gastric cancer cells by inhibiting SIRT1 expression, leading to p53 transcriptional upregulation and the activation of downstream p21, while suppressing Bcl-2 and survivin expression. Our results demonstrate that lentivirus-mediated siRNA targeting VEGF offers a potential strategy to prevent the growth of gastric cancer.

Cyclooxygenase-2 and gastric cancer

Gastric cancer remains a leading cause of cancer-related deaths worldwide, although its incidence has been steadily declining during recent decades. Expression of cyclooxygenase-2 (COX-2) is elevated in gastric carcinomas and in their precursor lesions. COX-2 expression associates with reduced survival in gastric cancer patients, and it has also been shown to be an independent factor of poor prognosis. Several molecular mechanisms are involved in the regulation of COX-2 expression in gastric cancer cell lines, including signal transduction pathways activated by Helicobacter pylori. In gastric tumor models in vivo the role of COX-2 seems to be predominantly to facilitate tumor promotion and growth.

Gastric cancer: basic aspects

Gastric cancer (GC) is a world health burden, ranging as the second cause of cancer death worldwide. Etiologically, GC arises not only from the combined effects of environmental factors and susceptible genetic variants but also from the accumulation of genetic and epigenetic alterations. In the last years, molecular oncobiology studies brought to light a number of genes that are implicated in gastric carcinogenesis. This review is intended to focus on the recently described basic aspects that play key roles in the process of gastric carcinogenesis. Genetic variants of the genes IL-10, IL-17, MUC1, MUC6, DNMT3B, SMAD4, and SERPINE1 have been reported to modify the risk of developing GC. Several genes have been newly associated with gastric carcinogenesis, both through oncogenic activation (GSK3β, CD133, DSC2, P-Cadherin, CDH17, CD168, CD44, metalloproteinases MMP7 and MMP11, and a subset of miRNAs) and through tumor suppressor gene inactivation mechanisms (TFF1, PDX1, BCL2L10, XRCC, psiTPTE-HERV, HAI-2, GRIK2, and RUNX3). It also addressed the role of the inflammatory mediator cyclooxygenase-2 (COX-2) in the process of gastric carcinogenesis and its importance as a potential molecular target for therapy.