Selective inhibition of cyclooxygenase-2 suppresses the growth of pancreatic cancer cells in vitro and in vivo

The role of aspirin in the prevention of pancreatic cancer: A nested case-control study in the UK Biobank

BACKGROUND

Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) usage has been associated with pancreatic ductal adenocarcinoma (PDAC) prevention, though epidemiological data have not reliably demonstrated this. The aim of this study is to identify if aspirin and other NSAIDs are effective in the primary prevention of PDAC in a large UK prospective cohort.

METHODS

A nested case-control study was conducted using the UK Biobank cohort. Incident PDAC cases (n = 1129 of whom 239 (21.2 %) were using aspirin) were age and sex-matched with cancer-free controls (n = 8822 of whom 1752 (19.9 %) were using aspirin). Conditional logistic regression models were used to generate odds ratios (ORs) and 95 % confidence intervals (CI) for risk of PDAC with and without regular use of aspirin, non-aspirin NSAIDs and all NSAIDs respectively. Exploratory analyses were carried out assessing interactions with diabetes mellitus (DM) as a condition with increased pancreatic cancer risk.

RESULTS

Regular aspirin use at initial recruitment was independently associated with a decreased risk of PDAC (OR [95 % CI] = 0.80 [0.68-0.95] P = 0.01). Regular non-aspirin NSAID use was not associated with a risk reduction of PDAC (OR [95 % CI] = 1.01 [0.84-1.23] P = 0.88). Exploratory analyses showed that in those with DM; regular aspirin use reduced risk of PDAC (OR [95 % CI] = 0.60 [0.42-0.85] P = 0.004) compared to non-use.

DISCUSSION

Regular aspirin use is associated with a reduction in risk of PDAC. The reduced risk is more apparent in participants with DM.

Aspirin Use and Risk of Pancreatic Ductal Adenocarcinoma: A Large Case-Control Study

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers, with a five-year survival rate of approximately 5%. The incidence and mortality rates of PDAC are increasing, and the results of medical treatments remain unsatisfactory. Some conflicting evidence suggests that aspirin intake may reduce the risk of PDAC. This study aimed to evaluate the association between regular low-dose aspirin use (80-mg aspirin tablets, 5-7 tablets/week) and the risk of PDAC.

METHODS

This prospective, hospital-based, case-control study was performed on 470 PDAC patients (case group) and 526 sex and age-matched controls, in Tehran, Iran from 2011 to 2018. The participants were interviewed regarding the patterns of aspirin use. Data are expressed as mean±SD or frequency and percentage as appropriate. Differences in frequency between the case and control groups were evaluated based on the analysis of the contingency table (χ2 test and Fisher's exact test). Propensity score models were designed to calculate odds ratios (OR) and 95% confidence intervals (95% CIs) for PDAC with respect to aspirin use, adjusted for age, sex, smoking status, opium use, diabetes mellitus, place of residence, and family history of cancer in first-degree relatives.

RESULTS

About 60% of PDAC patients were male in this study. Also, 25.2% of PDAC patients had a family history of cancer in one of their first-degree relatives, 21.99% were smokers, 13.9% were opium users, and 11.7% had a history of diabetes. Aspirin was used by 22.77% of PDAC patients and 18.25% of the controls. Ever aspirin use (OR: 1.01, 95% CI: 0.89 - 1.14) was not associated with PDAC.

CONCLUSION

Overall, aspirin use was not associated with a reduced risk of PDAC.

Bioinformatic mining and validation of the effects of ferroptosis regulators on the prognosis and progression of pancreatic adenocarcinoma

Ferroptosis, a new form of programmed cell death, provides a new option for anti-tumor treatment. However, the roles of ferroptosis-related (FR) genes in pancreatic adenocarcinoma (PAAD) were not fully elaborated. In the present study, 185 TCGA samples and 81 ICGC samples were used as training and validation cohorts, respectively. A novel FR risk signature (ALOX5, ALOX12, PTGS2, SAT1, STEAP3 and SQLE) was constructed via the Lasso regression analysis. In TCGA cohort, the risk signature was identified as an independent prognostic factor. Decision curve analysis (DCA) indicated that FR risk score could increase the net benefit when making clinical-decision. In addition, we constructed a nomogram to predict the overall survival rate (OSR) of individual at 1,2,3 year. Meanwhile, the prognostic value was partly validated in ICGC cohort. Through immune analyses, we found that high FR risk could affect the immune abundances of five lymphocytes but not effectively affect the activities of immune-related pathways. The expressions of most FR risk genes did not correlate with that of PD-L1(CD274) and CTLA4. Further, through RT-qPCR tests, the expressions of PTGS2 and SQLE were proven to be significantly upregulated in normal pancreatic duct epithelia cell (HPDE6-C7) compared to pancreatic cancer cells (SW1990 and BxPC-3). MTT, wound-healing and transwell assays revealed that silencing PTGS2 and SQLE could inhibit the proliferation, migration and invasion of pancreatic cancer cells. Besides, western-blot assays showed that blocking PTGS2 and SQLE expressions could suppress the protein expressions of cyclin D1 and N-cadherin, but facilitate that of E-cadherin, which suggested that they were involved in the epithelial to mesenchymal transition (EMT). Collectively, FR risk signature provides an important complement for PAAD prognostic analysis. High FR risk level can adversely affect anti-tumor immune process, but may not serve as a predictive marker of ICIs efficacy. PTGS2 and SQLE are proven to possess cancer-promoting abilities in PAAD.

Combination of celecoxib and calyculin-A inhibits epithelial-mesenchymal transition in human oral cancer cells

Expression of cyclo-oxygenase-2 (COX-2) and protein phosphatase 2A (PP2A) deactivation occurs frequently in oral squamous cell carcinoma (OSCC). We initially assessed COX-2 and PP2A protein expression in OSCC specimens using immunohistochemical (IHC) staining and western blot analysis. We found strong COX-2 and phosphorylated PP2A (p-PP2A) expression in OSCC samples. No significant difference in total PP2A expression was observed between cancer and nontumor tissues. The effect of combining COX-2 inhibitor and celecoxib (CXB) with the PP2A inhibitor, calyculin-A (CLA) on the OSCC cell line, HSC3, was evaluated in vitro. We found that a combination of 1 nM CLA and 50 µM CXB significantly inhibited cell viability, and migration and invasion of HSC3 cells. Western blots for AKT, p-AKT, ERK, p-ERK, E-cadherin, vimentin and β-catenin were conducted after treatment with CXB and/or CLA. Increased E-cadherin and decreased β-catenin expression were found in CXB or CLA treated hsc-3 cells, whereas the combined CXB and CLA treatment showed no difference in E-cadherin or β-catenin expression. Our findings suggest that CLA alone was more effective than CXB alone, but not in the combined drug treatment.

Celecoxib suppresses lipopolysaccharide-stimulated oral squamous cell carcinoma proliferation in vitro and in vivo

Periodontitis is one of the most common chronic oral inflammatory conditions worldwide and is associated with a risk of developing oral squamous cell carcinoma (OSCC). Porphyromonas gingivalis is a major pathogen in periodontitis, and its lipopolysaccharide (LPS) promotes the expression of cyclooxygenase-2 (COX-2) in OSCC both in vivo and in vitro. Celecoxib is a selective COX-2 inhibitor; however, its antitumor effects on P. gingivalis LPS-stimulated OSCC and the underlying molecular mechanism remain unclear. To elucidate the association between periodontitis and OSCC, the effect of P. gingivalis-derived LPS on OSCC cell proliferation was examined both in vitro and in vivo in the present study. The expression levels of COX-2 and p53 in OSCC cells with/without celecoxib treatment were determined via western blotting. The therapeutic potential of celecoxib in LPS-stimulated OSCC was evaluated by staining for Ki-67 and p21, as well as with terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling staining. LPS treatment significantly increased OSCC cell proliferation in vitro, and celecoxib significantly inhibited cell proliferation with/without LPS treatment. Celecoxib treatment of OSCC cells downregulated the protein expression levels of COX-2 compared with untreated cells, but there was little change in p53 expression. In the mouse xenograft model, oral administration of celecoxib significantly suppressed tumor growth, reduced the expression of Ki-67, increased the apoptosis index and induced p21 expression with/without LPS treatment. The results from the present study demonstrate that P. gingivalis' LPS can stimulate tumor growth by interacting with OSCC cells. In conclusion, these results suggest that celecoxib could be used for the effective prevention and treatment of LPS-stimulated OSCC.

Aspirin use and pancreatic cancer risk: A systematic review of observational studies

OBJECTIVES

Although there is evidence that aspirin might be able to prevent pancreatic cancer, the findings have been inconsistent. In this paper, we conducted a meta-analysis of observational studies to examine the relationship between aspirin use and the risk of pancreatic cancer.

METHODS

We identified potential studies by searching the MEDLINE, EMBASE, and Wangfang (Chinese database) database (from 1967 to March 2017) and by reviewing the bibliography of relevant publications. Random effects model was used to calculate odds ratio (OR) and 95% confidence interval. The Cochran Q statistic (significance level at P < .1) was used to assess heterogeneity in this study. The author adopted weighted regression method of Egger to assessed publication bias.

RESULTS

A total of 12 studies involving 4748 pancreatic cancer cases, were included in the meta-analysis. The study reflected that there was no signification association between aspirin use and mortality risk of pancreatic cancer. Aspirin use might reduce the incidence of pancreatic cancer. Specifically, there was a high signification association between frequent aspirin use and reduced pancreatic cancer incidence, without heterogeneity. In addition, there was a high signification association between duration of aspirin use more than 5 years and reduced pancreatic cancer incidence, without obvious heterogeneity among the original studies.

CONCLUSIONS

In summary, this meta-analysis suggested that the aspirin use might be negatively related to the incidence risk of pancreatic cancer. Specifically, the frequency and duration of aspirin use might play an important role in decreasing the incidence of pancreatic cancer.

TRAIL-Receptor 4 Modulates γδ T Cell-Cytotoxicity Toward Cancer Cells

Acquired immune evasion is one of the mechanisms that contributes to the dismal prognosis of cancer. Recently, we observed that different γδ T cell subsets as well as CD8⁺ αβ T cells infiltrate the pancreatic tissue. Interestingly, the abundance of γδ T cells was reported to have a positive prognostic impact on survival of cancer patients. Since γδ T cells utilize TNF-related apoptosis inducing ligand (TRAIL) for killing of tumor cells in addition to granzyme B and perforin, we investigated the role of the TRAIL-/TRAIL-R system in γδ T cell-cytotoxicity toward pancreatic ductal adenocarcinoma (PDAC) and other cancer cells. Coculture of the different cancer cells with γδ T cells resulted in a moderate lysis of tumor cells. The lysis of PDAC Colo357 cells was independent of TRAIL as it was not inhibited by the addition of neutralizing anti-TRAIL antibodies or TRAIL-R2-Fc fusion protein. In accordance, knockdown (KD) of death receptors TRAIL-R1 or TRAIL-R2 in Colo357 cells had no effect on γδ T cell-mediated cytotoxicity. However, KD of decoy receptor TRAIL-R4, which robustly enhanced TRAIL-induced apoptosis, interestingly, almost completely abolished the γδ T cell-mediated lysis of these tumor cells. This effect was associated with a reduced secretion of granzyme B by γδ T cells and enhanced PGE2 production as a result of increased expression level of synthetase cyclooxygenase (COX)-2 by TRAIL-R4-KD cells. In contrast, knockin of TRAIL-R4 decreased COX-2 expression. Importantly, reduced release of granzyme B by γδ T cells cocultured with TRAIL-R4-KD cells was partially reverted by bispecific antibody [HER2xCD3] and led in consequence to enhanced lysis of tumor cells. Likewise, inhibition of COX-1 and/or COX-2 partially enhanced γδ T cell-mediated lysis of TRAIL-R4-KD cells. The combination of bispecific antibody and COX-inhibitor completely restored the lysis of TRAIL-R4-KD cells by γδ T cells. In conclusion, we uncovered an unexpected novel role of TRAIL-R4 in tumor cells. In contrast to its known pro-tumoral, anti-apoptotic function, TRAIL-R4 augments the anti-tumoral cytotoxic activity of γδ T cells.

The association of changes in RAD51 and survivin expression levels with the proton beam sensitivity of Capan‑1 and Panc‑1 human pancreatic cancer cells

Fewer than 20% of patients diagnosed with pancreatic cancer can be treated with surgical resection. The effects of proton beam irradiation were evaluated on the cell viabilities in Panc‑1 and Capan‑1 pancreatic cancer cells. The cells were irradiated with proton beams at the center of Bragg peaks with a 6‑cm width using a proton accelerator. Cell proliferation was assessed with the MTT assay, gene expression was analyzed with semi‑quantitative or quantitative reverse transcription‑polymerase chain reaction analyses and protein expression was evaluated by western blotting. The results demonstrated that Capan‑1 cells had lower cell viability than Panc‑1 cells at 72 h after proton beam irradiation. Furthermore, the cleaved poly (ADP‑ribose) polymerase protein level was increased by irradiation in Capan‑1 cells, but not in Panc‑1 cells. Additionally, it was determined that histone H2AX phosphorylation in the two cell lines was increased by irradiation. Although a 16 Gy proton beam was only slightly up‑regulated cyclin‑dependent kinase inhibitor 1 (p21) protein expression in Capan‑1 cells, p21 expression levels in Capan‑1 and Panc‑1 cells were significantly increased at 72 h after irradiation. Furthermore, it was observed that the expression of DNA repair protein RAD51 homolog 1 (RAD51), a homogenous repair enzyme, was decreased in what appeared to be a dose‑dependent manner by irradiation in Capan‑1 cells. Contrastingly, the transcription of survivin in Panc‑1 was significantly enhanced. The results suggest that RAD51 and survivin are potent markers that determine the therapeutic efficacy of proton beam therapy in patients with pancreatic cancer.

Cyclooxygenase-2 induces angiogenesis in pancreatic cancer mediated by prostaglandin E2

The purpose of the present study was to elucidate the effects of cyclooxygenase 2 (COX-2) on the expression of vascular endothelial growth factor (VEGF) and prostaglandin E2 (PGE2) in pancreatic cancer in vitro and in vivo, and to clarify the potential mechanism of COX-2-induced angiogenesis of pancreatic cancer. The study analysis was conducted in the pancreatic cancer PC-3 cell line. The expression of COX-2 and VEGF in human pancreatic cancer tissue was analyzed by immunohistochemistry. Angiogenesis was detected using immunohistochemistry with anti-collagen IV antibodies, and was calculated according to the microvascular density (MVD). In vitro analysis was performed using ELISA or radioimmunoassay (RIA). The effect of exogenous PGE2 on the downregulation of VEGF by Celebrex was also assessed. In vivo analysis was performed using western blotting or RIA. Concurrently, MVD was also investigated in nude mice using immunohistochemistry with anti-collagen IV antibodies. COX-2 was overexpressed in pancreatic cancer tissues, with an overall positive rate of 87.5%. There was a positive association between the expression of COX-2 and MVD. The in vitro study indicated that Celebrex suppressed the expression of VEGF and PGE2 in PC-3 cells in a dose- and time-dependent manner, while exogenous PGE2 rescued the expression of VEGF, which was suppressed by Celebrex, in a dose-dependent manner. The in vivo study revealed that the administration of Celebrex to xenograft nude mice significantly inhibited the expression of VEGF and PGE2. These data provide evidence that PGE2 may be an important mediator between COX-2 and VEGF expression in the process of angiogenesis in pancreatic cancer.

Nonsteroidal anti-inflammatory drugs, statins, and pancreatic cancer risk: a population-based case-control study

PURPOSE

Studies suggest that aspirin, other nonsteroidal anti-inflammatory drugs (NSAIDs), and statins may reduce risk of some cancers. However, findings have been conflicting as to whether these agents reduce the risk of pancreatic cancer.

METHODS

We used data from the Queensland Pancreatic Cancer Study, a population-based case-control study. In total, 704 cases and 711 age- and sex-matched controls were recruited. Participants completed an interview in which they were asked about history of NSAID and statin use. We included 522 cases and 653 controls who had completed the medication section of the interview in this analysis. Unconditional multivariable logistic regression was used to estimate associations between medication use and pancreatic cancer.

RESULTS

We found no consistent evidence of an association between use of NSAIDs or statins and risk of pancreatic cancer. There was some suggestion of a protective effect in infrequent users of selective COX-2 inhibitors, but no association in more frequent users. We did not find evidence of protective effects in analyses stratified by sex, smoking status, time between diagnosis and interview, or presence/absence of metastases.

CONCLUSIONS

Overall, our results do support the hypothesis that use of NSAIDs or statins may reduce the odds of developing pancreatic cancer.

The Role of Cyclooxygenase-2 in Colorectal Carcinogenesis

Colorectal cancer is a major worldwide health care problem that accounts for 1 million new cases each year. The risk factors for this disease include hereditary factors, environmental agents, and inflammatory stimuli that affect the gastrointestinal tract. Among these risk factors, cyclooxygenase-2 (COX-2) is one of the major players in the progression of colorectal cancer; however, the detailed mechanism of its role in causing colorectal cancer is still not well understood. In addition, the role of COX-2 signaling through the interaction in the epithelial and stromal compartments on colorectal carcinogenesis has not been fully illustrated. In the present review, we provide published evidence to demonstrate that (1) COX-2 signaling plays a major role in the progression of colorectal cancer, (2) activation of COX-2 in the stromal compartment also contributes to colorectal carcinogenesis, and (3) inhibition of COX-2 signaling by COX-2 inhibitors might be an effective method to control colorectal cancer. We have also summarized recent advances and insights from mechanistic studies of colorectal cancer to help prevent and control this deadly disease and provide our opinion regarding the importance of risk reduction and disease prevention for colorectal cancer.

Nimesulide inhibits the growth of human esophageal carcinoma cells by inactivating the JAK2/STAT3 pathway

Although selective COX-2 inhibitors have cancer-preventive effects and induce apoptosis, the mechanisms underlying these effects are not fully understood. This study investigated the effects of nimesulide, a selective COX-2 inhibitor, on apoptosis and on the JAK/STAT signaling pathway in Eca-109 human esophageal squamous carcinoma cells. The effects and mechanisms of nimesulide on Eca-109 cell growth were studied in culture and in nude mice with Eca-109 xenografts. Cells were cultured with or without nimesulide and/or the JAK2 inhibitor AG490. Cell proliferation was evaluated using the MTT assay, and apoptosis was investigated. COX-2 mRNA expression was measured using reverse transcription polymerase chain reaction, and protein expression was detected by Western blot analysis, immunohistochemistry, and flow cytometry. Nimesulide significantly inhibited Eca-109 cell viability in vitro in a dose- and time-dependent manner (P<0.05). Nimesulide also induced apoptosis, which was accompanied by a significant decrease in the expression of COX-2 and survivin and an increase in caspase-3 expression. Nimesulide downregulated the phosphorylation levels of JAK2 and STAT3, and JAK2 inhibition by AG490 significantly augmented both nimesulide-induced apoptosis and the downregulation of COX-2 and survivin (P<0.05). In vivo, nimesulide inhibited the growth of Eca-109 tumors and the expression of p-JAK2 and p-STAT3. Thus, nimesulide downregulates COX-2 and survivin expression and upregulates caspase-3 expression in Eca-109 cells, by inactivating the JAK2/STAT3 pathway. These effects may mediate nimesulide-induced apoptosis and growth inhibition in Eca-109 cells in vitro and in vivo.

Resistance of cyclooxygenase-2 expressing pancreatic ductal adenocarcinoma cells against γδ T cell cytotoxicity

The prostaglandin (PG) synthetase cyclooxygenase 2 (Cox-2) promotes tumorigenesis, tumor progression, and metastasis in a variety of human cancer entities including pancreatic ductal adenocarcinoma (PDAC). In this study, we demonstrate that in PDAC cells such as Colo357 cells, enhanced Cox-2 expression and increased release of the Cox-2 metabolite prostaglandin E2 (PGE2) promotes resistance against γδ T cell-mediated lysis. Co-culture with activated γδ T cells induced an upregulation of Cox-2 expression in Colo357 cells, and thereby an enhanced PGE2 release, in response to tumor necrosis factor α (TNFα) secretion from γδ T cells. The PGE2-mediated inhibition of γδ T cell cytotoxicity against Cox-2-expressing PDAC cells can be partially overcome by Cox-2 inhibitors. Our results show that differences between PDAC cells in regards to sensitivity to γδ T-cell cytotoxicity can be due to distinct levels of Cox-2 expression associated with varying amounts of PGE2 release. While γδ T cell cytotoxicity against PDAC cells expressing low levels of Cox-2 can be effectively enhanced by tribody [(Her2)₂×Vγ9] with specificity for Vγ9 T cell receptor and HER-2/neu on PDAC cells, a combination of tribody [(Her2)₂×Vγ9] and Cox-2 inhibitor is necessary to induce complete lysis of Cox-2 high expressing Colo357. In conclusion, our results suggest that the application of tribody [(Her2)₂×Vγ9] that enhances γδ T-cell cytotoxicity and Cox-2 inhibitors that overcome PGE2-mediated resistance of PDAC cells to the cytotoxic activity of γδ T cells might offer a promising combined immunotherapy for pancreatic cancer.

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.

The discovery and development of cyclooxygenase-2 inhibitors as potential anticancer therapies

INTRODUCTION

In the past, clinical studies had demonstrated that aspirin and NSAIDs reduce the risk of colorectal cancer. After the discovery of selective prostaglandin-endoperoxide synthase 2 (PTGS2) inhibitors, the further beneficial effects of celecoxib and some other related structures (coxibs) have been demonstrated in both in vivo and in vitro studies.

AREAS COVERED

The authors illustrate the role of prostaglandins following the overexpression of PTGS2 (COX-2) in signaling pathways. The authors elucidate the role of coxibs in cell proliferation, apoptosis, angiogenesis and multi-drug resistance and discuss the molecular mechanisms involved. The authors also present the strong evidence related to the usefulness of coxibs in several cancer cell lines.

EXPERT OPINION

There have been a number of PTGS2 (COX-2) selective inhibitors suggested as potential anticancer therapies. In recent years, the development of nanotechnology has also had an impact on chemotherapy. Indeed, nanoparticles of cytotoxic drug carriers have demonstrated potential through their accumulation in cancer cells, and targeting these nanoparticles has been under evaluation. This area could be opened up for coxib development as they are potentially important targets in cancer cells. Further research using celecoxib as a co-drug with PTGS2-overexpressed and PTGS2-independent cancer is still needed.

High-dose aspirin consumption contributes to decreased risk for pancreatic cancer in a systematic review and meta-analysis

OBJECTIVES

The aim of this study was to analyze the association between aspirin intake and its effect for chemoprevention of pancreatic cancer incidence by using a meta-analysis method.

METHODS

The databases of MEDLINE, EMBASE, and Wangfang (Chinese database) were retrieved to identify eligible studies. Odds ratio (OR) and 95% confidence interval (CI) were calculated using a random-effects model.

RESULTS

A total of 10 studies (4 case-control studies, 5 prospective cohort studies, and 1 randomized controlled trial) with 7,252 cases of pancreatic cancer and more than 120,0000 healthy control subjects were enrolled in the studies. Pooled analyses showed that high-dose aspirin intake was marginally associated with decreased risk for pancreatic cancer for overall analysis (OR, 0.88; 95% CI, 0.76-1.01) as well as for both cohort and case-control studies (OR, 0.70; 95% CI, 0.54-1.16, for the cohort studies; OR, 0.82; 95% CI, 0.62-1.02, for the case-control studies), without between-study heterogeneity. Stratified analysis for Americans showed a similar result (OR, 0.82; 95% CI, 0.65-1.02). In contrast, our study inferred that low-dose aspirin intake was not associated with risk for pancreatic cancer for the total and subgroup analyses.

CONCLUSIONS

In summary, our study indicated that high-dose aspirin, rather than low-dose aspirin, might be associated with decreased risk for pancreatic cancer, especially for Americans.

Involvement of inflammatory factors in pancreatic carcinogenesis and preventive effects of anti-inflammatory agents

Chronic inflammation is known to be a risk for many cancers, including pancreatic cancer. Heavy alcohol drinking and cigarette smoking are major causes of pancreatitis, and epidemiological studies have shown that smoking and chronic pancreatitis are risk factors for pancreatic cancer. Meanwhile, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) are elevated in pancreatitis and pancreatic cancer tissues in humans and in animal models. Selective inhibitors of iNOS and COX-2 suppress pancreatic cancer development in a chemical carcinogenesis model of hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). In addition, hyperlipidemia, obesity, and type II diabetes are also suggested to be associated with chronic inflammation in the pancreas and involved in pancreatic cancer development. We have shown that a high-fat diet increased pancreatic cancer development in BOP-treated hamsters, along with aggravation of hyperlipidemia, severe fatty infiltration, and increased expression of adipokines and inflammatory factors in the pancreas. Of note, fatty pancreas has been observed in obese and/or diabetic cases in humans. Preventive effects of anti-hyperlipidemic/anti-diabetic agents on pancreatic cancer have also been shown in humans and animals. Taking this evidence into consideration, modulation of inflammatory factors by anti-inflammatory agents will provide useful data for prevention of pancreatic cancer.

The HMGA1-COX-2 axis: a key molecular pathway and potential target in pancreatic adenocarcinoma

CONTEXT

Although pancreatic cancer is a common, highly lethal malignancy, the molecular events that enable precursor lesions to become invasive carcinoma remain unclear. We previously reported that the high-mobility group A1 (HMGA1) protein is overexpressed in >90% of primary pancreatic cancers, with absent or low levels in early precursor lesions.

METHODS

Here, we investigate the role of HMGA1 in reprogramming pancreatic epithelium into invasive cancer cells. We assessed oncogenic properties induced by HMGA1 in non-transformed pancreatic epithelial cells expressing activated K-RAS. We also explored the HMGA1-cyclooxygenase (COX-2) pathway in human pancreatic cancer cells and the therapeutic effects of COX-2 inhibitors in xenograft tumorigenesis.

RESULTS

HMGA1 cooperates with activated K-RAS to induce migration, invasion, and anchorage-independent cell growth in a cell line derived from normal human pancreatic epithelium. Moreover, HMGA1 and COX-2 expression are positively correlated in pancreatic cancer cell lines (r(2) = 0.93; p < 0.001). HMGA1 binds directly to the COX-2 promoter at an AT-rich region in vivo in three pancreatic cancer cell lines. In addition, HMGA1 induces COX-2 expression in pancreatic epithelial cells, while knock-down of HMGA1 results in repression of COX-2 in pancreatic cancer cells. Strikingly, we also discovered that Sulindac (a COX-1/COX-2 inhibitor) or Celecoxib (a more specific COX-2 inhibitor) block xenograft tumorigenesis from pancreatic cancer cells expressing high levels of HMGA1.

CONCLUSIONS

Our studies identify for the first time an important role for the HMGA1-COX-2 pathway in pancreatic cancer and suggest that targeting this pathway could be effective to treat, or even prevent, pancreatic cancer.

(-)-Epigallocatechin-3-gallate, a green tea-derived catechin, synergizes with celecoxib to inhibit IL-1-induced tumorigenic mediators by human pancreatic adenocarcinoma cells Colo357

Despite their toxic side effects prostaglandin H(2) synthase-2 (PGHS-2) inhibitors hold promise for cancer chemoprevention. In order to overcome adverse effects lower doses of PGHS-2 inhibitors could be applied in combination with other agents exhibiting complementary effects. Herein, the effects of the PGHS-2-specific inhibitor celecoxib either alone or in combination with the green tea-derived catechin (-)-epigallocatechin-3-gallate (EGCG) were studied on the expression of interleukin (IL)-1-induced tumorigenic factors in Colo357 human pancreatic adenocarcinoma cells. This approach mimics tumor-associated pancreatic inflammation which is considered as a key player in pancreatic malignancy. We found that co-incubation of Colo357 with celecoxib and EGCG synergistically diminished metabolic activity via apoptosis induction and down-regulated release of pro-angiogenic vascular endothelial growth factor (VEGF) and invasiveness-promoting matrix metalloproteinase (MMP)-2 to a maximum of 30%. Celecoxib and EGCG synergistically reduced IL-1-induced production of pro-inflammatory IL-6 and pro-angiogenic IL-8 to 23-50%. Celecoxib dose-dependently increased PGHS-2 levels. Whereas EGCG was able to compensate for celecoxib-mediated increase of PGHS-2, it failed to potentiate celecoxib-mediated suppression of prostaglandin E(2) (PGE(2)) release. Thus, in Colo357, EGCG synergistically boosts celecoxib-mediated effects and reduces the levels of celecoxib required to elicit beneficial effects on tumorigenic mediators by a factor of ten.

Chronic inflammation in cancer development

Chronic inflammatory mediators exert pleiotropic effects in the development of cancer. On the one hand, inflammation favors carcinogenesis, malignant transformation, tumor growth, invasion, and metastatic spread; on the other hand inflammation can stimulate immune effector mechanisms that might limit tumor growth. The link between cancer and inflammation depends on intrinsic and extrinsic pathways. Both pathways result in the activation of transcription factors such as NF-κB, STAT-3, and HIF-1 and in accumulation of tumorigenic factors in tumor and microenvironment. STAT-3 and NF-κB interact at multiple levels and thereby boost tumor-associated inflammation which can suppress anti-tumor immune responses. These factors also promote tumor growth, progression, and metastatic spread. IL-1, IL-6, TNF, and PGHS-2 are key mediators of an inflammatory milieu by modulating the expression of tumor-promoting factors. In this review we concentrate on the crucial role of pro-inflammatory mediators in inflammation-driven carcinogenesis and outline molecular mechanisms of IL-1 signaling in tumors. In addition, we elucidate the dual roles of stress proteins as danger signals in the development of anti-cancer immunity and anti-apoptotic functions.

Interleukin 1α sustains the expression of inflammatory factors in human pancreatic cancer microenvironment by targeting cancer-associated fibroblasts

The tumor microenvironment in pancreatic ductal adenocarcinoma (PDAC) is dynamic, with an extensive interaction between the stroma and tumor cells. The aim of this study was to delineate the cross talk between PDAC and cancer-associated fibroblasts (CAFs), with a focus on the mechanism creating the chronic inflammatory tumor milieu. We assessed the effects of the cross talk between PDAC and CAF cell lines on the creation and sustenance of the inflammatory tumor microenvironment in pancreatic cancer. The coculture of PDAC and CAF cell lines enhanced the levels of inflammatory factors including IL-1α, IL-6, CXCL8, VEGF-A, CCL20, and COX-2. CAFs were superior to tumor cells regarding the production of most inflammatory factors, and tumor cell-associated IL-1α was established as the initiator of the enhanced production of inflammatory factors through the binding of IL-1α to IL-1 receptor 1 (IL-1R1) expressed predominantly by CAFs. Furthermore, we found a correlation between IL-1α and CXCL8 expression levels in PDAC tissues and correlation between IL-1α expression and the clinical outcome of the patients. This confirmed an important role for the IL-1 signaling cascade in the creation and sustenance of a tumor favorable microenvironment. Neutralization of the IL-1α signaling efficiently diminished the cross talk-induced production of inflammatory factors. These data suggest that the cross talk between PDAC cells and the main stroma cell type, i.e. CAFs, is one essential factor in the formation of the inflammatory tumor environment, and we propose that neutralization of the IL-1α signaling might be a potential therapy for this cancer.

Combined inhibitory effects of celecoxib and fluvastatin on the growth of human hepatocellular carcinoma xenografts in nude mice

This study was designed to investigate the in vivo growth inhibitory effects of celecoxib, a cyclo-oxygenase-2 inhibitor, and fluvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on the hepatocellular carcinoma (HCC) cell line, BEL-7402. Athymic nude mice implanted with BEL-7402 cells were given celecoxib and fluvastatin, either alone or in combination, and the effect of treatment on tumour growth was evaluated after 6 weeks. The combination of celecoxib and fluvastatin enhanced inhibition of tumour growth, induction of apoptosis, inhibition of tumour cell proliferation, and inhibition of tumour angiogenesis compared with either treatment alone. The combination of celecoxib and fluvastatin also increased levels of the cyclin-dependent kinase inhibitor p21(Waf1/Cip1), decreased levels of p-Akt, myeloid cell leukaemia-1 (Mcl-1) and survivin protein, but had no effect on Akt protein levels in tumours. These results suggest that celecoxib combined with fluvastatin would be more efficacious for the treatment of HCC than either treatment alone and this combination of therapy warrants further research.

Transcript profiling identifies novel key players mediating the growth inhibitory effect of NS-398 on human pancreatic cancer cells

Pancreatic cancer is one of the most aggressive human malignancies with an increasing incidence worldwide. Despite an increase in the number of systemic treatments available for pancreatic cancer, the impact of therapy on the clinical course of the disease has been modest, underscoring an urgent need for new therapeutic options. Although selective cyclooxygenase-2 inhibitors have been demonstrated to have cancer-preventive effects, the mechanism of their effects is not clearly known. Moreover, there have been no unbiased studies to identify novel molecular targets of NS-398 regarding pancreatic cancer. Here we undertook a gene expression profiling study to identify novel molecular targets modulating the growth inhibitory effects of NS-398 on pancreatic cancer cell lines. Our mRNA-based gene expression results showed that the growth inhibitory effect of NS-398 was accompanied with an activation of G1/S and G2/M cell cycle regulation, P53 signalling, apoptotic, aryl hydrocarbon receptor and death receptor signalling pathways. Moreover, we reported, for the first time, that the growth inhibitory effect of NS-398 is mediated by down-regulation of RRM2, CTGF, MCM2 and PCNA and up-regulation of NAG-1 in all cell lines.

Nimesulide, a selective cyclooxygenase-2 inhibitor, inhibits the growth of esophageal carcinoma in vivo by modulating PPARγ signal transduction pathway

AIM: To detect the expression of cyclooxygenase-2 (COX-2) and peroxisome proliferator-activated receptor γ (PPARγ) in human esophageal carcinoma, to investigate the inhibitory effects of nimesulide on tumor growth in esophageal carcinoma xenografts in nude mice, and to explore potential mechanisms involved.

METHODS: The expression of PPARγ and COX-2 in 18 normal esophageal epithelial specimens and 59 esophageal squamous cell carcinoma (ESCC) specimens were examined by immunohistochemistry. A nude mouse model bearing Eca-109 cell xenografts was established. The mice were divided randomly into control group and nimesulide group [treated with nimesulide at a dose of 20 mg/(kg•d) for 4 wk]. The tumor volume and reduced rate of tumor growth were calculated according to the length and width of xenograft tumors. Cell apoptosis was detected by flow cytometry. The expression of COX-2 and PPARγ mRNAs and proteins was detected by RT-PCR and immunohistochemistry, respectively.

RESULTS: The immunohistochemical score of PPARγ was significantly lower in ESCC than in normal esophageal epithelium (2.88 ± 2.23 vs 6.29 ± 2.17, P < 0.05), while that of COX-2 was significantly higher in ESCC than in normal esophageal epithelium (2.12 ± 1.77 vs 0.82 ± 0.46, P < 0.05). The immunohistochemical score of PPARγ decreased as tumor pathological grade increased. The immunohistochemical score of PPARγ was closely related to tumor differentiation degree (P < 0.05). The expression level of COX-2 was significantly higher in well and moderately differentiated ESCC than in poorly differentiated ESCC (P < 0.05). Nimesulide significantly inhibited tumor growth in esophageal carcinoma xenografts when compared with the control group (tumor volume: 807.68 mm3 ± 217.76 mm3 vs 2116.77 mm3 ± 362.47 mm3; tumor weight: 0.81 g ± 0.21 g vs 1.45 g ± 0.39 g; both P < 0.05), and the reduced rate of tumor growth was 44.14% ± 6.3%. Nimesulide treatment increased the apoptosis rate from 15.86% ± 2.57% to 32.21% ± 5.98%. COX-2 expression was down-regulated, and PPARγ expression up-regulated in the nimesulide group when compared with the control group. A negative correlation was noted between the expression of COX-2 and PPARγ.

CONCLUSION: Down-regulation of PPARγ expression and up-regulation of COX-2 expression are related to the carcinogenesis of ESCC. Nimesulide inhibits tumor growth and induces apoptosis in esophageal carcinoma xenografts possibly by down-regulating COX-2 expression and up-regulating PPARγ expression.

[The role of chemotherapy in pediatric medulloblastoma]

Medulloblastoma is one of the most frequent brain tumors in childhood. The mortality of medulloblastoma decreased significantly during the last few decades, which was the result of the better surgical and radiotherapeutic methods and of the development of chemotherapy. The aim of this publication is the critical review of the present chemotherapeutic treatment. The new therapeutic trials based on the molecular genetic mechanism of these tumors are also mentioned.

Chemoprevention strategies for pancreatic cancer

Pancreatic cancer has a poor prognosis and is often diagnosed at an advanced stage, which makes it difficult to treat. The low survival rate of patients with pancreatic cancer points towards an increased need for novel therapeutic and chemopreventive strategies and also early detection of this disease. Increased consumption of fruits and vegetables has been associated with a reduced risk of pancreatic cancer. Synthetic and natural, diet-derived bioactive compounds have been evaluated as pancreatic cancer chemopreventive agents and have demonstrated various degrees of efficacy in cellular and in vivo animal models. Some chemopreventive agents (for example, curcumin or resveratrol) have also been reported to sensitize pancreatic cancer cells to standard chemotherapeutic drugs (for example, gemcitabine or erlotinib), which suggests that chemopreventive agents could potentially be used as potentiators of standard chemotherapy. Few clinical trials of pancreatic cancer chemopreventive agents have been completed and some are in early phases. Further development of pancreatic cancer chemopreventive agents may prove to be tremendously valuable for individuals at high risk of developing pancreatic cancer and patients who present with premalignant lesions. This Review discusses the current state of the pancreatic cancer chemoprevention field and highlights the challenges ahead.

The role of cyclooxygenase-2 in cell proliferation and cell death in human malignancies

It is well admitted that the link between chronic inflammation and cancer involves cytokines and mediators of inflammatory pathways, which act during the different steps of tumorigenesis. The cyclooxygenases (COXs) are a family of enzymes, which catalyze the rate-limiting step of prostaglandin biosynthesis. This family contains three members: ubiquitously expressed COX-1, which is involved in homeostasis; the inducible COX-2 isoform, which is upregulated during both inflammation and cancer; and COX-3, expressed in brain and spinal cord, whose functions remain to be elucidated. COX-2 was described to modulate cell proliferation and apoptosis mainly in solid tumors, that is, colorectal, breast, and prostate cancers, and, more recently, in hematological malignancies. These findings prompt us to analyze here the effects of a combination of COX-2 inhibitors together with different clinically used therapeutic strategies in order to further improve the efficiency of future anticancer treatments. COX-2 modulation is a promising field investigated by many research groups.

Countering tumor-induced immunosuppression during immunotherapy for pancreatic cancer

BACKGROUND

Vaccines for pancreatic cancer have been challenged by a number of factors, especially the immunosuppressive microenvironment within the tumor that allows for escape from immune surveillance.

OBJECTIVE/METHODS

We sought to identify results that define mechanisms of pancreatic-cancer-associated immunosuppression and strategies that might be useful to overcome them thereby resulting in effective immune responses to cancer vaccines capable of deleting pancreatic cancer cells.

RESULTS/CONCLUSION

Immunosuppressive tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSC), and regulatory T cells (Treg) reside in tumors, and their products along with tumor derived products (such as VEGF, TGFbeta and IL-10), create a microenvironment that counters immune activation and attack. Immunotherapy with cancer vaccines must include strategies to modulate these immunosuppressive cell types and tumor byproducts. Clinical trials are beginning to test these strategies.