Blockade of cholecystokinin-2 receptor and cyclooxygenase-2 synergistically induces cell apoptosis, and inhibits the proliferation of human gastric cancer cells in vitro

Chiral aldehyde catalysis enables direct asymmetric α-substitution reaction of N-unprotected amino acids with halohydrocarbons

The direct catalytic α-hydrocarbylation of readily available amino acids with halohydrocarbons is one of the most straightforward methods leading to α,α-disubstituted non-proteinogenic α-amino acid compounds. However, all the reported methodologies depend on N-protected amino acids as starting materials. Herein, we report on three highly efficient aldehyde-catalyzed direct α-hydrocarbylations of N-unprotected amino acid esters with aryl-, allyl-, and benzyl halides. By promoting a simple chiral BINOL-aldehyde catalyst or combining catalysts of a chiral aldehyde and Lewis acid ZnCl₂, the asymmetric α-arylation, α-allylation, and α-benzylation of amino acid esters with the corresponding halohydrocarbons proceed smoothly, producing α,α-disubstituted α-amino acids in moderate-to-high yields and good-to-excellent enantioselectivities. The asymmetric α-arylation reaction can be applied in the formal synthesis of the clinical candidate compound (+)-AG-041R. Based on the results given by control experiments, three reaction models are proposed to illustrate the stereoselective-control outcomes.

Myrrh induces the apoptosis and inhibits the proliferation and migration of gastric cancer cells through down-regulating cyclooxygenase-2 expression

Objective: The present study is designed to evaluate the anti-tumor effects of myrrh on human gastric cancer both in vitro and in vivo. Methods: The gastric cancer cell proliferation was determined by MTT assay. Apoptosis was measured by flow cytometry and Hoechst 33342 staining. Wound healing was performed to evaluate the effects of myrrh on the migration. COX-2, PCNA, Bcl-2, and Bax expressions were detected by Western blot analysis. A xenograft nude mice model of human gastric cancer was established to evaluate the anti-cancer effect of myrrh in vivo. Results: Myrrh significantly inhibited cellular proliferation, migration, and induced apoptosis in vitro as well as inhibited tumor growth in vivo. In addition, myrrh inhibited the expression of PCNA, COX-2, and Bcl-2 as well as increased Bax expression in gastric cancer cells. Conclusion: Myrrh may inhibit the proliferation and migration of gastric cancer cells, as well as induced their apoptosis by down-regulating the expression of COX-2.

Anti-prostate cancer activity of a nanoformulation of the spleen tyrosine kinase (SYK) inhibitor C61

Patients with advanced or metastatic castration-resistant prostate cancer have a dismal prognosis and are therefore in urgent need for therapeutic innovations. Spleen tyrosine kinase has emerged as a new molecular target for castration-resistant prostate cancer. This study was done to test the cytotoxicity of the lead nanoformulation of a potent spleen tyrosine kinase inhibitor, C61-LNP, against the human prostatic carcinoma cell line, PC-3. PC-3 cells were treated with various concentrations of C61-LNP either alone or in combination with cisplatin (CDDP) for 24, 48 and 72 hours. The cell viability was evaluated by MTS assay. Cellular expression levels of various regulatory proteins in treated PC-3 cells were evaluated by Western blot analyses. C61-LNP exhibited dose-dependent cytotoxicity against PC-3 cells. C61-LNP, as well as C61-LNP + CDDP treatments, caused pro-apoptotic proteomic changes including an increase in cleaved fragments of caspases-3 and -9 consistent with caspase activation as well as an improvement in the anti-apoptotic Bcl2 and Bax levels. The combination of C61-LNP and CDDP changed in alterations of the cell cycle regulatory proteins p53, p21, p27, cyclin D1 and cyclin E levels. C61-LNP exhibited cytotoxicity against the castration-resistant prostate cancer cell line PC3. It also caused alterations in expression levels of regulatory proteins involved in apoptosis and cell cycle regulation and these effects were not abrogated by the standard chemotherapy drug CDDP. We are planning to further develop C61-LNP as a selective spleen tyrosine kinase inhibitor as part of a multi-modality treatment strategy for advanced/metastatic castration-resistant prostate cancer.

Palladium-catalyzed asymmetric allylic alkylation of 3-aminooxindoles to access chiral homoallylic aminooxindoles

An organometal catalytic conversion of 3-aminooxindoles for the diastereo- and enantioselective synthesis of homoallylic aminooxindoles has been described. The asymmetric allylic alkylation of 3-aminooxindoles with allyl carboxylates proceeded smoothly to afford a series of chiral 3-allyl-3-aminooxindoles. This work offers an alternative route to build these scaffolds. The application of this protocol is also highlighted by a significant conversion of products to the potential applicable spiro[indoline-3,2'-pyrrolidin]-2-one derivatives.

Acetyl-11-keto-β-boswellic acid inhibits proliferation and induces apoptosis of gastric cancer cells through the phosphatase and tensin homolog /Akt/ cyclooxygenase-2 signaling pathway

BACKGROUND

Gastric cancer is one of the most common malignant tumors of the digestive system worldwide, posing a serious danger to human health. Cyclooxygenase (COX)-2 plays an important role in the carcinogenesis and progression of gastric cancer. Acetyl-11-keto-β-boswellic acid (AKBA) is a promising drug for cancer therapy, but its effects and mechanism of action on human gastric cancer remain unclear.

AIM

To evaluate whether the phosphatase and tensin homolog (PTEN)/Akt/COX-2 signaling pathway is involved in the anti-tumor effect of AKBA in gastric cancer.

METHODS

Human poorly differentiated BGC823 and moderately differentiated SGC7901 gastric cancer cells were routinely cultured in Roswell Park Memorial Institute 1640 medium supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin. Gastric cancer cell proliferation was determined by methyl thiazolyl tetrazolium colorimetric assay. Apoptosis was measured by flow cytometry. Cell migration was assessed using the wound-healing assay. Expression of Bcl-2, Bax, proliferating cell nuclear antigen, PTEN, p-Akt, and COX-2 were detected by Western blot analysis. A xenograft nude mouse model of human gastric cancer was established to evaluate the anti-cancer effect of AKBA in vivo.

RESULTS

AKBA significantly inhibited the proliferation of gastric cancer cells in a dose- and time-dependent manner, inhibited migration in a time-dependent manner, and induced apoptosis in a dose-dependent manner in vitro; it also inhibited tumor growth in vivo. AKBA up-regulated the expression of PTEN and Bax, and down-regulated the expression of proliferating cell nuclear antigen, Bcl-2, p-Akt, and COX-2 in a dose-dependent manner. The PTEN inhibitor bpv (Hopic) reversed the high expression of PTEN and low expression of p-Akt and COX-2 that were induced by AKBA. The Akt inhibitor MK2206 combined with AKBA down- regulated the expression of p-Akt and COX-2, and the combined effect was better than that of AKBA alone.

CONCLUSION

AKBA inhibits the proliferation and migration and promotes the apoptosis of gastric cancer cells through the PTEN/Akt/COX-2 signaling pathway.

Gastrin, Cholecystokinin, Signaling, and Biological Activities in Cellular Processes

The structurally-related peptides, gastrin and cholecystokinin (CCK), were originally discovered as humoral stimulants of gastric acid secretion and pancreatic enzyme release, respectively. With the aid of methodological advances in biochemistry, immunochemistry, and molecular biology in the past several decades, our concept of gastrin and CCK as simple gastrointestinal hormones has changed considerably. Extensive in vitro and in vivo studies have shown that gastrin and CCK play important roles in several cellular processes including maintenance of gastric mucosa and pancreatic islet integrity, neurogenesis, and neoplastic transformation. Indeed, gastrin and CCK, as well as their receptors, are expressed in a variety of tumor cell lines, animal models, and human samples, and might contribute to certain carcinogenesis. In this review, we will briefly introduce the gastrin and CCK system and highlight the effects of gastrin and CCK in the regulation of cell proliferation and apoptosis in both normal and abnormal conditions. The potential imaging and therapeutic use of these peptides and their derivatives are also summarized.

Organocatalytic Enantioselective Mukaiyama-Mannich Reaction of Isatin-Derived Ketimines for the Synthesis of Oxindolyl-β3, 3 -Amino Acid Esters

Mukaiyama-Mannich reactions of ester enolate equivalents with aldimines have been elegantly used for the asymmetric synthesis of β-amino acids; nevertheless, the corresponding asymmetric reaction employing ketimines are unexplored. Herein, the first organocatalytic enantioselective Mukaiyama-Mannich reaction employing isatin-derived ketimines with unsubstituted silyl ketene acetals is disclosed towards the scalable synthesis of 2-oxoindolinyl-β^3, 3 -amino acid esters at room temperature with excellent enantioselectivities (ee >99.5 %). Ultra-low catalyst loadings (as low as 250 ppm) could be used for the quantitative product formation with high enantiopurity. The synthetic utility of this protocol has been showcased in the short formal synthesis of pharmaceutically demanded (+)-AG-041R, a potent gastrin/CCK-B receptor antagonist.

Lycopene Inhibits Activation of Epidermal Growth Factor Receptor and Expression of Cyclooxygenase-2 in Gastric Cancer Cells

Reactive oxygen species (ROS) contribute to the oncogenic phenotype of cancer cells by acting as signaling molecules for inducing proliferation. ROS are known to activate the epidermal growth factor receptor (EGFR), which causes the activation of the Ras/mitogen-activated protein kinases (MAPKs) pathway. The Ras-dependent pathway promotes the activation of nuclear factor-kappa-light-chain-enhancer of activated B cells (NF-κB), a transcriptional modulator of cyclooxygenase-2 (COX-2) that induces cell proliferation. Lycopene is a potent antioxidant carotenoid and is responsible for the red color of fruits and vegetables. This study aims to investigate whether lycopene inhibits proliferation and induces apoptosis in gastric cancer AGS cells by suppressing the EGFR/Ras/MAPK and NF-κB-COX-2 signaling axis. Lycopene decreased cell viability and increased apoptotic indices (DNA fragmentation, apoptosis inducing factor, cleavage of caspase-3 and caspase-9, Bax/Bcl-2 ratio). Lycopene reduced the level of intracellular and mitochondrial ROS and decreased the activation of the ROS-mediated EGFR/Ras/extracellular signal-regulated kinase (ERK) and p38 MAPK pathways, thus leading to attenuation of the DNA-binding activity of NF-κB p50/p50 and the level of COX-2 gene expression. These results show that lycopene-induced apoptosis and inhibition of proliferation occur via inhibition of ROS-activated EGFR/Ras/ERK and p38 MAPK pathways and NF-κB-mediated COX-2 gene expression in AGS cells. In conclusion, consumption of lycopene-enriched foods could decrease the incidence of gastric cancer.

EBV down-regulates COX-2 expression via TRAF2 and ERK signal pathway in EBV-associated gastric cancer

Epstein-Barr virus-associated gastric cancer (EBVaGC) accounts for nearly 10% of gastric cancer. Cyclooxygenase-2 (COX-2) plays a crucial role in cancer progression. However, there is no experimental study on the regulation mechanism of EBV on COX-2 in EBVaGC. To understand more about the tumorigenic mechanism of EBVaGC, the study investigated the role of EBV encode latent membrane protein LMP1 and LMP2A in the regulation of COX-2. The expression of COX-2 was examined in EBVaGC and EBV negative gastric cancer (EBVnGC) cell lines. The plasmids were transfected in SGC7901 to overexpress LMP1/2A. Small interfering RNA (si-RNA) targeting LMP1/2A in GT38 and targeting TRAF2 in SGC7901 were used to detect the expression of COX-2. Furthermore, si-ERK1/2 and the MEK inhibitor PD0325901 were used to investigate whether p-ERK participate in the regulation of COX-2 in SGC7901. The overexpression of LMP1 or LMP2A in SGC7901 down-regulates both COX-2 and TRAF2 expression, and knockdown of LMP1 or LMP2A in GT38 resulted in a certain recovery of COX-2 and TRAF2 expression. Moreover, si-TRAF2 indicated that a sharp down-regulation of COX-2. And the decrease of p-ERK also mediates the inhibitory effect of LMP1 on COX-2. In summary, overexpression of LMP1 and LMP2A inhibits COX-2, which is mediated by a decrease of TRAF2, and p-ERK is involved in the inhibition of COX-2 by LMP1 in gastric cancer.

An asymmetric acetate-Mannich reaction of chiral isatin derived ketimines and its applications

A highly efficient TMSOTf-mediated asymmetric acetate-Mannich reaction of isatin derived tert-butylsulfinyl ketimines and S-phenyl thioacetate was developed to afford the direct synthesis of indole-based β^3,3-amino acid thioester with excellent selectivity (dr > 98 : 2). Syntheses of (+)-AG-041R and 3-aminopyrroloindoline have been accomplished utilizing the developed method.

Cyclooxygenase-2 mediated synergistic effect of ursolic acid in combination with paclitaxel against human gastric carcinoma

Ursolic acid (UA) induces apoptosis in gastric cancer cells by inhibiting cyclooxygenase-2 (COX-2). Paclitaxel (PTX) is an important chemotherapy agent used to treat solid tumors. We evaluated the in vitro antitumor activity of UA in combination with PTX against gastric cancer cells and investigated the mechanisms underlying the combined effects. A cytotoxicity test and flow cytometry were utilized to study the effects of UA and PTX on proliferation and apoptosis, respectively. To further elucidate the mechanism, Western blot analysis was used to assess changes in the expression of a series of related proteins, including COX-2, proliferating cell nuclear antigen (PCNA), Bcl-2, and Bax. UA and PTX dose- and time-dependently inhibited BGC-823 and SGC-7901 gastric cancer cell proliferation. Combined delivery of UA and PTX synergistically reduced cell proliferation and induced apoptosis in these cells by lowering COX-2, PCNA, and Bcl-2 expression and by increasing Bax expression. These results indicate that the synergistic inhibition of proliferation and induction of apoptosis by UA and PTX may be induced by reducing COX-2 expression in gastric cancer cells.

Prostate cancer downregulated SIRP-α modulates apoptosis and proliferation through p38-MAPK/NF-κB/COX-2 signaling

The present study investigated the regulatory mechanism of signal-regulatory protein (SIRP)-α in the apoptosis and proliferation of prostate cancer (CaP) cells. The expression profile of SIRP-α in prostate cancer cells was analyzed using reverse transcription-quantitative polymerase chain reaction and western blotting. Then SIRP-α function in CaP cells was further analyzed with the overexpression and RNA interference of SIRP-α. The results revealed that SIRP-α expression levels were decreased in CaP tissues and cell lines, with androgen-independent CaP exhibiting a lower SIRP-α expression compared with androgen-dependent CaP. Overexpression of SIRP-α resulted in a significantly reduced number of live CaP cells by enhancing apoptosis, whereas SIRP-α silencing increased CaP cell proliferation. Mechanistically, SIRP-α decreases cyclooxygenase-2 (COX-2) expression and cytokine production by negatively regulating p38 mitogen-activated protein kinase and nuclear factor-κB pathway. Therefore, SIRP-α knockdown decreases cell apoptosis by enhancing COX-2 expression. The present results indicate that SIRP-α may function as a novel negative regulator to modulate cellular proliferation, survival and migration in CaP cells. The heightened sensitivity of cells restoring SIRP-α function could be exploited in the development of therapeutics that may potentiate the antineoplastic effects of conventional cytokines or chemotherapeutic agents.

Insights into gastric neuroendocrine tumors burden

Type 1 gastric neuroendocrine tumors (gNETs) are usually small lesions, restricted to mucosal and sub-mucosal layers of corpus and fundus, with low aggressive behavior, for the majority of cases. Nevertheless, some cases present aggressive behavior. The increasing incidence of gNETs brings together a new relevant problem: how to identify potentially aggressive type 1 gNETs. The challenging problem seems to be finding out signs or features able to predict potentially aggressive cases, allowing a tailored approach, since the involved societies dedicated to provide guidelines for management of these neoplasms apparently failed in producing staging systems able to accurately predict prognosis of these tumors. Additionally, it is also important to try to find out explanations for increasing incidence, as well as to identify potential targets aiming to reach better control of this neoplasia. Here, we discuss potential pathways implicated in aggressive behavior, as well as new strategies to improve clinical management of these tumors.

Downregulated microRNA-26a modulates prostate cancer cell proliferation and apoptosis by targeting COX-2

MicroRNA-26a (miR-26a) is expressed at lower levels in prostate cancer cells compared with normal prostate cells. However, the regulatory mechanism of miR-26a in tumorigenesis and metastasis is not clear. In the present study, the expression profile of cellular miR-26a was analyzed by reverse transcription-quantitative polymerase chain reaction. The potential target of miR-26a was identified by luciferase assay and western blotting. Examination of miR-26a function was performed by transfection with miR-26a mimics and inhibitor. It was found that miR-26a expression was decreased in prostate cancer tissues and cell lines, with androgen-independent prostate cancer (AIPC) showing lower miR-26a expression compared with androgen-dependent prostate cancer (ADPC). Overexpression of miR-26a by transfecting miR-26a mimics could significantly enhance apoptosis, and this upregulation of apoptosis was triggered by cytochrome c oxidase subunit II inhibition. Furthermore, it was found that lower miR-26a density resulted in an evidently poor prognosis. Understanding the important roles of miR-26a in regulating cell apoptosis in human prostate cancer cells may aid the exploration of AIPC transformation mechanisms and contribute to the development of miRNA-based therapy in the future.

Anti-cancer Effects of a Novel Quinoline Derivative 83b1 on Human Esophageal Squamous Cell Carcinoma through Down-Regulation of COX-2 mRNA and PGE2

PURPOSE

83b1 is a novel quinoline derivative that has been shown to inhibit cancer growth in human esophageal squamous cell carcinoma (ESCC). This study was conducted to comprehensively evaluate the cytotoxic effects of 83b1 on a series of ESCC cell lines and investigate the mechanisms by which 83b1 suppresses cancer growth based on molecular docking analysis.

MATERIALS AND METHODS

A series of ESCC and nontumor immortalized cell lines were exposed to 83b1 and cisplatin (CDDP) in a dose-dependent manner, and the cytotoxicity was examined by a MTS assay kit. Prediction of the molecular targets of 83b1 was conducted by molecular docking analysis. Expression of cyclooxygenase 2 (COX-2) mRNA and COX-2-derived prostaglandin E₂ (PGE₂) were measured by quantitative real-time polymerase chain reaction and enzymelinked immuno-sorbent assay, respectively. In vivo anti-tumor effect was determined using a nude mice xenografted model transplanted with an ESCC cell line, KYSE-450.

RESULTS

83b1 showed the significant anti-cancer effects on all ESCC cell lines compared to CDDP; however, 83b1 revealed much lower toxic effects on non-tumor cell lines than CDDP. The predicted molecular target of 83b1 is peroxisome proliferator-activated receptor delta (PPARδ), which is a widely known oncoprotein. Additionally the expression of COX-2 mRNA and COX-2-derived PGE₂ were down-regulated by 83b1 in a dose-dependent manner in ESCC cell lines. Furthermore, 83b1 was shown to significantly reduce the tumor size in nude mice xenograft.

CONCLUSION

The results of this study suggest that the potential anti-cancer effects of 83b1 on human esophageal cancers occur through the possible oncotarget, PPARδ, and down-regulation of the cancer related genes and molecules.

Harmine combined with paclitaxel inhibits tumor proliferation and induces apoptosis through down-regulation of cyclooxygenase-2 expression in gastric cancer

Cyclooxygenase-2 (COX-2) serves an important role in the carcinogenesis and progression of gastric cancer. Harmine (HM) and paclitaxel (PTX) are reported as promising drug candidates for cancer therapy, but whether a synergistic anti-tumor effect of HM combined with PTX exists in human gastric cancer remains unknown. The present study evaluated the effects of HM and/or PTX on cell proliferation and apoptosis in a gastric cancer cell line, SGC-7901. HM and PTX inhibited cell proliferation in a dose-dependent manner. Both HM and PTX alone induced apoptosis in gastric cancer cells. The combination of HM and PTX exerted synergistic effects on proliferation inhibition and apoptosis induction in SGC-7901 cells, with down-regulation of COX-2, PCNA and Bcl-2 and up-regulation of Bax expression. The results indicated that combination chemotherapy using HM with PTX exerts an anti-tumor effect for treating gastric cancer. The combination of the two drugs inhibits gastric cancer development more effectively than each drug alone through down-regulation of COX-2 expression.

MicroRNA-146a enhances Helicobacter pylori induced cell apoptosis in human gastric cancer epithelial cells

Helicobacter pylori (H. pylori) infection induces apoptosis in gastric epithelial cells, and this occurrence may link to gastric carcinogenesis. However, the regulatory mechanism of H. pylori-induced apoptosis is not clear. MicroRNA-146a has been implicated as a key regulator of the immune system. This report describes our discovery of molecular mechanisms of microRNA-146a regulation of apoptosis in human gastric cancer cells. We found that overexpression of microRNA-146a by transfecting microRNA-146a mimics could significantly enhance apoptosis, and this up-regulation was triggered by COX-2 inhibition. Furthermore, we found that microRNA-146a density was positively correlated with apoptosis rates in H. pylori-positive gastric cancer tissues and intratumoral microRNA-146a density was negatively correlated with lymph node metastasis among H. pylori-positive gastric cancer patients. Understanding the important roles of microRNA-146a in regulating cell apoptosis in H. pylori infected human gastric cancer cells will contribute to the development of microRNA targeted therapy in the future.

Paclitaxel combined with harmine inhibits the migration and invasion of gastric cancer cells through downregulation of cyclooxygenase-2 expression

Cyclooxygenase-2 (COX-2) has a critical role in the invasiveness and metastasis of gastric cancer. In addition, paclitaxel (PTX) and harmine (HM) were reported to be potential therapeutic drug candidates for cancer therapy; however, the synergistic antitumor effect of PTX and HM combined treatment on the human gastric cancer cells remains to be elucidated. The aim of the present study was to evaluate the effects of PTX and/or HM on the cell migration and invasion in two human gastric cancer cell lines, SGC-7901 and MKN-45. MTT assay was used to detect the growth inhibition induced by PTX and HM. The Transwell assay was employed to assess the effects of PTX and HM on the cell migration and invasion. The expression levels of COX-2 and matrix metalloproteinase-9 (MMP-9) were analyzed by western blot analysis. The results demonstrated that PTX and HM inhibited cell proliferation in a dose-dependent manner. Individually PTX and HM were able to inhibit the migration and invasion of two human gastric cancer cells; however, the combination of PTX and HM exerted synergistic effects on migration and invasion inhibition, with downregulation of COX-2 and matrix metalloproteinase (MMP)-9. In conclusion, the results of the present study indicated that combination chemotherapy using PTX with HM exerted an antitumor effect, which may be implicated for the treatment of gastric cancer. Of note, the combination of the two drugs inhibited migration and invasion more effectively compared with each drug alone, the mechanism of which proceeded via the downregulation of COX-2 expression.

An organocatalytic Mannich/denitration reaction for the asymmetric synthesis of 3-ethylacetate-substitued 3-amino-2-oxindoles: formal synthesis of AG-041R

The highly enantioselective organocatalytic addition of ethyl nitroacetate to isatin-derived N-Boc ketimines (Boc = tert-butoxycarbonyl), followed by the removal of the nitro group, is described. The scalable reaction sequence leads to the title compounds as important intermediates of pyrroloindoline alkaloids and related drugs in excellent yields and enantioselectivities. The synthesis of the hexahydrofurano[2,3-b]indole skeleton, the spirocarbamate oxindole unit, and the formal synthesis of AG-041R have been carried out to demonstrate the synthetic utility of this protocol.

Bortezomib inhibits gastric carcinoma HGC-27 cells through the phospho-Jun N-terminal kinase (p-JNK) pathway in vitro

The study is designed to explore the anticancer mechanism of Bortezomib. The effects of Bortezomib on the proliferation of human gastric cancer cells HGC-27 and expression levels of the phospho-Jun N-terminal kinase (p-JNK) pathway-related proteins in vitro were investigated. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that the Bortezomib significantly decreased the viability of HGC-27 cells and induced apoptosis. Western blot showed that the Bortezomib strongly increased the levels of p-JNK, caspase-3, PARP, and bax proteins while it increased the level of bcl-2. However, SP600125 can significantly decrease antitumour effects of Bortezomib in HGC-27 cells. It can be concluded that Bortezomib has significant inhibitory effects on the growth of HGC-27 cells. The effect may be achieved partly via upregulating JNK pathway and its down-stream apoptosis-related proteins. Therefore, Bortezomib may be beneficial in gastric carcinoma treatment.

Helicobacter pylori infection, gastrin and cyclooxygenase-2 in gastric carcinogenesis

Gastric cancer is one of the most frequent neoplasms and a main cause of death worldwide, especially in China and Japan. Numerous epidemiological, animal and experimental studies support a positive association between chronic Helicobacter pylori (H. pylori) infection and the development of gastric cancer. However, the exact mechanism whereby H. pylori causes gastric carcinogenesis remains unclear. It has been demonstrated that expression of cyclooxygenase-2 (COX-2) is elevated in gastric carcinomas and in their precursor lesions. In this review, we present the latest clinical and experimental evidence showing the role of gastrin and COX-2 in H. pylori-infected patients and their possible association with gastric cancer risk.

Harmine induces apoptosis and inhibits tumor cell proliferation, migration and invasion through down-regulation of cyclooxygenase-2 expression in gastric cancer

Cyclooxygenase-2 (COX-2) plays an important role in the carcinogenesis and progression of gastric cancer. Harmine is reported as a promising drug candidate for cancer therapy; however, effects and action mechanism of harmine on the human gastric cancer cells remain unclear. This study evaluated the anti-tumor effects of harmine on human gastric cancer both in vitro and in vivo. The cell proliferation was determined using MTT colorimetric assay. Apoptosis was measured by DAPI staining and flow cytometry analysis. The wound healing and transwell invasion assays were performed to evaluate the effects of harmine on the migration and invasion of gastric cancer cells. The expression of COX-2, proliferating cell nuclear antigen (PCNA), Bcl-2, Bax and matrix metalloproteinase-2 (MMP-2) was detected by Western blot analysis. Our results showed that harmine significantly inhibited cellular proliferation, migration, invasion and induced apoptosis in vitro, as well as inhibited tumor growth in vivo. In addition, harmine significantly inhibited the expression of COX-2, PCNA, Bcl-2 and MMP-2 as well as increased Bax expression in gastric cancer cells. These results collectively indicate that harmine induces apoptosis and inhibits proliferation, migration and invasion of human gastric cancer cells, which may be mediated by down-regulation of COX-2 expression.

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.

Effect of 15-hydroxyprostaglandin dehydrogenase gene on the proliferation of gastric cancer cell murine forestomach carcinoma

The aim of the present study was to construct the eukaryotic expression vector pcDNA3.1/15-PGDH. The vector was used to transfect mouse murine forestomach carcinoma (MFC) cancer cells and observe the effects of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) on the proliferation of MFC. pcDNA3.1/15-PGDH was constructed using gene recombination technology and the vector was used to transfect MFC cells to build a stable transfected cell strain. The expression levels of 15-PGDH in the transfected cells were detected using reverse transcription polymerase chain reaction. Optical Density (OD) values were determined using an MTT assay and used to draw cell growth curves. The effects of 15-PGDH on the proliferation of MFC were observed using a clone formation experiment. Following successful transfection by 15-PGDH, the relative expression levels of 15-PGDH in the MFC/15-PGDH cells were significantly higher (1.06±0.08) (P<0.01) compared with the empty plasmid-transfected group (0.22±0.01) and the untransfected group (0.21±0.01). Following transfection by 15-PGDH, cell growth was markedly inhibited. The MTT results showed that on days 4, 6 and 8, the 15-PGDH-transfected group had a low OD on average, which was significantly different (P<0.05) from the empty plasmid-transfected group or the untransfected group. The 15-PGDH-transfected group had a plating efficiency of 18%, and compared with the untransfected group (63%) and the empty plasmid-transfected group (59%), clone formation was significantly inhibited (P<0.01). Results of the present study indicate that transfection by 15-PGDH may significantly inhibit the proliferation and clone formation of MFC cells.

MiR-148a regulates the growth and apoptosis in pancreatic cancer by targeting CCKBR and Bcl-2

Our previous studies have revealed that miR-148a is downregulated in pancreatic cancer. Bioinformatics analysis has shown cholecystokinin-B receptor (CCKBR) and B cell lymphoma (Bcl-2) to be potential targets of miR-148a. But the pathophysiologic role of miR-148a and its relevance to the growth and development of pancreatic cancer are yet to be investigated. The purpose of this study is to elucidate the molecular mechanisms where miR-148a acts as a tumor suppressor in pancreatic cancer. Our results showed significant downregulation of miR-148a in 28 pancreatic cancer tissue samples and five pancreatic cancer cell lines, compared with their non-tumor counterparts by qRT-PCR. MiR-148a was found to not only inhibit the proliferation of pancreatic cancer cells (PANC-1 and AsPC-1) in vitro by MTT assay and colony formation assay, but also to promote cells apoptosis in vitro by Annexin V-FITC apoptosis detection and caspase activity assay. Using western blot and luciferase activity assay, CCKBR and Bcl-2 were identified as targets of miR-148a. Moreover, we also found that the expression of Bcl-2 lacking in 3'UTR could abrogate the pro-apoptosis function of miR-148a. These findings suggest the importance of miR-148a's targeting of CCKBR and Bcl-2 in the regulation of pancreatic cancer growth and apoptosis.

Delivery of ursolic acid (UA) in polymeric nanoparticles effectively promotes the apoptosis of gastric cancer cells through enhanced inhibition of cyclooxygenase 2 (COX-2)

It has been demonstrated that ursolic acid (UA) could effectively induces apoptosis of cancer cells by inhibiting the expression of cyclooxygenase 2 (COX-2), which constitutively expresses in gastric cancer. However, the hydrophobicity of UA increases the difficulty in its potential clinical application, which raises the possibility for its application as a novel model drug in nanoparticle-based delivery system. UA-loaded nanoparticles (UA-NPs) were prepared by a nano-precipitation method using amphilic methoxy poly(ethylene glycol)-polycaprolactone (mPEG-PCL) block copolymers as drug carriers. UA was effectively transported into SGC7901 cells by nanoparticles and localized around the nuclei in the cytoplasms. The in vitro cytotoxicity and apoptosis test indicated that UA-NPs significantly elicited more cell death at almost equivalent dose and corresponding incubation time. Moreover, UA-NPs led to more cell apoptosis through stronger inhibition of COX-2 and activation of caspase 3. The most powerful evidence from this report is that the significant differences between the cytotoxicity of free UA and UA-NPs are closely related to the expression levels of COX-2 and caspase-3, which demonstrates the superiority of UA-NPs over free UA through penetrating cell membrane. Therefore, the study offer an effective way to improve the anticancer efficiency of UA through nano-drug delivery system.

Gastrin acting on the cholecystokinin2 receptor induces cyclooxygenase-2 expression through JAK2/STAT3/PI3K/Akt pathway in human gastric cancer cells

Gastrin, cholecystokinin2 receptor (CCK2R), and cyclooxygenase-2 (COX-2) have been implicated in the carcinogenesis and progression of gastric cancer. Our study demonstrated that antagonist or siRNA against CCK2R blocked amidated gastrin (G17)-induced activation of STAT3 and Akt in gastric cancer cell lines. G17-increased COX-2 expression and cell proliferation were effectively blocked by CCK2R antagonist and inhibitors of JAK2 and PI3K. In addition, knockdown of STAT3 expression significantly attenuated G17-induced PI3K/Akt activation, COX-2 expression, and cell proliferation. These results suggest that CCK2R-mediated COX-2 up-regulation via JAK2/STAT3/PI3K/Akt pathway is involved in the proliferative effect of G17 on human gastric cancer cells.

Downregulation of miR-101 in gastric cancer correlates with cyclooxygenase-2 overexpression and tumor growth

Cyclooxygenase-2 (COX-2) plays an important role in the carcinogenesis and progression of gastric cancer. It has been demonstrated that COX-2 overexpression depends on different cellular pathways, involving both transcriptional and post-transcriptional regulation. MicroRNAs (miRNAs) are small, noncoding RNAs that function as post-transcriptional regulators. Here, we characterize miR-101 expression and its role in the regulation of COX-2 expression, which in turn, will provide us with additional insights into the potential therapeutic benefits of exogenous miR-101 for treatment of gastric cancer. Our results showed that miR-101 levels in gastric cancer tissues were significantly lower than those in the matched normal tissue (P < 0.01). Furthermore, lower levels of miR-101 were associated with increased tumor invasion and lymph node metastasis (P < 0.05). We also found an inverse correlation between miR-101 and COX-2 expression in both gastric cancer specimens and cell lines. Significant decreases in COX-2 mRNA and COX-2 levels were observed in the pre-miR-101-infected gastric cancer cells. One possible mechanism of interaction is that miR-101 inhibited COX-2 expression by directly binding to the 3'-UTR of COX-2 mRNA. Overexpression of miR-101 in gastric cancer cell lines also inhibited cell proliferation and induced apoptosis in vitro, as well as inhibiting tumor growth in vivo. These results collectively indicate that miR-101 may function as a tumor suppressor in gastric cancer, with COX-2 as a direct target.

Cholecystokinin and gastrin receptors targeting in gastrointestinal cancer

Cholecystokinin and Gastrin are amongst the first gastrointestinal hormone discovered. In addition to classical actions (contraction of gallbladder, growth and secretion in the stomach and pancreas), these also act as growth stimulants for gastrointestinal malignancies and cell lines. Growth of these tumours is inhibited by antagonists of the cholecystokinin and gastrin receptors. These receptors provides most promising approach in clinical oncology and several specific radiolabelled ligands have been synthesized for specific tumour targeting and therapy of tumours overexpressing these receptors. Therefore, definition of the molecular structure of the receptor involved in the autocrine/paracrine loop may contribute to novel therapies for gastrointestinal cancer. Hence, this review tries to focus on the role and distribution of these hormones and their receptors in gastrointestinal cancer with a brief talk about the clinical trial using available agonist and antagonist in gastrointestinal cancers.

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.

Prognostic relevance of cyclooxygenase-2 (COX-2) expression in Chinese patients with prostate cancer

Cyclooxygenase-2 (COX-2), an inducible isoform of cyclooxygenase, has been reported to be correlated with tumorigenesis, tumor progression and metastasis. The present study was designed to investigate the clinicopathological and prognostic significance of COX-2 in Chinese patients with prostate cancer. Firstly, RT-PCR and Western blot assays were performed to detect the expression of COX-2 mRNA and protein in prostate cancer cell lines and 20 tissue samples (tumor or corresponding non-tumor). Next, immunohistochemistry was performed to detect the expression of COX-2 protein in 88 prostate cancer tissue samples. Finally, the correlation between COX-2 expression and clinicopathological factors and patient survival was evaluated. We found that the expression levels of COX-2 mRNA and protein showed significant difference among four prostate cancer cell lines. Moreover, the levels of COX-2 mRNA and protein were significantly higher in prostate cancer tissues than in corresponding non-tumor tissues. COX-2 staining was positive in the cytoplasm of prostate cancer cells. High-COX-2 expression was correlated with the Gleason score (P=0.009), tumor stage (P=0.012), and lymph-node status (P=0.036). Furthermore, patients with high-COX-2 expression showed lower disease-free (P=0.014) and overall survival (P=0.047) rates than those with low-COX-2 expression. Univariate and multivariate analyses suggested that the status of COX-2 protein expression was an independent prognostic indicator for patients' survival. Taken together, higher COX-2 protein expression might provide an independent prognostic marker for Chinese patients with prostate cancer who have undergone surgery.

Gastrin, inflammation, and carcinogenesis

PURPOSE OF REVIEW

Chronic infection of the gastric mucosa with Helicobacter pylori has long been recognized as a significant risk factor for gastric cancer, and indeed, this model represents the prototypical inflammation-associated cancer. In this review, we present the latest clinical and experimental evidence showing that gastrin peptides and their receptors [the cholecystokinin (CCK2) receptors] potentiate the progression of gastric cancer and other gastrointestinal malignancies in the presence of inflammation.

RECENT FINDINGS

We highlight the feed-forward mechanisms by which gastrin and CCK2 receptor expression are upregulated during inflammation and in gastrointestinal cancers, summarize gastrin's proinflammatory role by inducing the production of cyclooxgenase-2 (COX-2) and interleukin-8 (IL-8), and relate evidence suggesting that gastrin and their receptors modulate the function of immune cells and fibroblasts following cellular stress, injury, repair, as well as during cancer progression.

SUMMARY

We discuss trends for future studies directed toward the elucidation of gastrin peptides' role in regulating intercellular molecular signaling mechanisms between local and circulating immune cells, fibroblasts, epithelial cells, and other cell types in the microenvironments of inflammation-related cancers. Elucidation of the molecular and cellular pathways that relate inflammation with cancer may provide additional opportunities to develop complementary therapies that target the inflammatory microenvironment of the cancer.

Cyclooxygenase-2 inhibition inhibits PI3K/AKT kinase activity in epithelial ovarian cancer

Cyclooxygenase-2 (COX-2) expression contributes to tumor growth and invasion in epithelial ovarian cancer (EOC). COX-2 inhibitors exhibit important anticarcinogenic potential against EOC, but the molecular mechanisms underlying this effect and relation with PI3-kinase/AKT signaling remain the subject of intense investigations. Therefore, the role of COX-2 in EOC and its cross talk with PI3-kinase/AKT pathway were investigated using a large series of EOC tissues in a tissue micro array (TMA) format followed by in vitro and in vivo studies using EOC cell lines and NUDE mice. Clinically, COX-2 was overexpressed in 60.3% of EOC and was significantly associated with activated AKT (p < 0.0001). Cox-1 expression was seen in 59.9% but did not associate with AKT. Our in vitro data using EOC cell line showed that inhibition of COX-2 by aspirin, selective inhibitor NS398 and gene silencing by COX-2 specific siRNA impaired phosphorylation of AKT resulting decreased downstream signaling leading to cell growth inhibition and induction of apoptosis. Finally, treatment of MDAH2774 cell line xenografts with aspirin resulted in growth inhibition of tumors in NUDE mice via down-regulation of COX-2 and AKT activity. These data identify COX-2 as a potential biomarker and therapeutic target in distinct molecular subtypes of ovarian cancer.

Importance of gastrin in the pathogenesis and treatment of gastric tumors

In addition to regulating acid secretion, the gastric antral hormone gastrin regulates several important cellular processes in the gastric epithelium including proliferation, apoptosis, migration, invasion, tissue remodelling and angiogenesis. Elevated serum concentrations of this hormone are caused by many conditions, particularly hypochlorhydria (as a result of autoimmune or Helicobacter pylori (H pylori)-induced chronic atrophic gastritis or acid suppressing drugs) and gastrin producing tumors (gastrinomas). There is now accumulating evidence that altered local and plasma concentrations of gastrin may play a role during the development of various gastric tumors. In the absence of H pylori infection, marked hypergastrinemia frequently results in the development of gastric enterochromaffin cell-like neuroendocrine tumors and surgery to remove the cause of hypergastrinemia may lead to tumor resolution in this condition. In animal models such as transgenic INS-GAS mice, hypergastrinemia has also been shown to act as a cofactor with Helicobacter infection during gastric adenocarcinoma development. However, it is currently unclear as to what extent gastrin also modulates human gastric adenocarcinoma development. Therapeutic approaches targeting hypergastrinemia, such as immunization with G17DT, have been evaluated for the treatment of gastric adenocarcinoma, with some promising results. Although the mild hypergastrinemia associated with proton pump inhibitor drug use has been shown to cause ECL-cell hyperplasia and to increase H pylori-induced gastric atrophy, there is currently no convincing evidence that this class of agents contributes towards the development of gastric neuroendocrine tumors or gastric adenocarcinomas in human subjects.

Inhibition of COX-2 and activation of peroxisome proliferator-activated receptor gamma synergistically inhibits proliferation and induces apoptosis of human pancreatic carcinoma cells

Although inhibition of cyclooxygenase-2 (COX-2) or activation of peroxisome proliferators-activated receptor gamma (PPAR-gamma) leads to growth inhibition in malignancies, the synergistic anti-tumor effects of combination of COX-2 inhibitor (NS-398) and PPAR-gamma agonist (rosiglitazone) on the human pancreatic cancer cells remains unknown. Here, we evaluated the effects of NS-398 and/or rosiglitazone on the cell proliferation and apoptosis in a pancreatic cancer cell line, SW1990. NS-398 and rosiglitazone decreased cell proliferation in a dose- and time-dependent manner. Proliferating cell nuclear antigen (PCNA) labeling index significantly decreased in the cells treated with either NS-398 or rosiglitazone. Both NS-398 and rosiglitazone alone induced apoptotic cell death of SW1990. The combination of NS-398 and rosiglitazone exerted synergistic effects on proliferation inhibition, and apoptosis induction in SW1990 cells, with down-regulation of Bcl-2 and up-regulation of Bax expression. Our results indicate that simultaneous targeting of COX-2 and PPAR-gamma inhibits pancreatic cancer development more effectively than targeting each molecule alone.