Expression of COX-2 is associated with accumulation of p53 in pancreatic cancer: analysis of COX-2 and p53 expression in premalignant and malignant ductal pancreatic lesions

Coxsackievirus and adenovirus receptor expression facilitates enteroviral infections to drive the development of pancreatic cancer

The development of pancreatic cancer requires both, acquisition of an oncogenic mutation in KRAS as well as an inflammatory insult. However, the physiological causes for pancreatic inflammation are less defined. We show here that oncogenic KRas-expressing pre-neoplastic lesion cells upregulate coxsackievirus (CVB) and adenovirus receptor (CAR). This facilitates infections from enteroviruses such as CVB3, which can be detected in approximately 50% of pancreatic cancer patients. Moreover, using an animal model we show that a one-time pancreatic infection with CVB3 in control mice is transient, but in the presence of oncogenic KRas drives chronic inflammation and rapid development of pancreatic cancer. We further demonstrate that a knockout of CAR in pancreatic lesion cells blocks these CVB3-induced effects. Our data demonstrate that KRas-caused lesions promote the development of pancreatic cancer by enabling certain viral infections.

Membrane Lipid Derivatives: Roles of Arachidonic Acid and Its Metabolites in Pancreatic Physiology and Pathophysiology

One of the most important constituents of the cell membrane is arachidonic acid. Lipids forming part of the cellular membrane can be metabolized in a variety of cellular types of the body by a family of enzymes termed phospholipases: phospholipase A2, phospholipase C and phospholipase D. Phospholipase A2 is considered the most important enzyme type for the release of arachidonic acid. The latter is subsequently subjected to metabolization via different enzymes. Three enzymatic pathways, involving the enzymes cyclooxygenase, lipoxygenase and cytochrome P450, transform the lipid derivative into several bioactive compounds. Arachidonic acid itself plays a role as an intracellular signaling molecule. Additionally, its derivatives play critical roles in cell physiology and, moreover, are involved in the development of disease. Its metabolites comprise, predominantly, prostaglandins, thromboxanes, leukotrienes and hydroxyeicosatetraenoic acids. Their involvement in cellular responses leading to inflammation and/or cancer development is subject to intense study. This manuscript reviews the findings on the involvement of the membrane lipid derivative arachidonic acid and its metabolites in the development of pancreatitis, diabetes and/or pancreatic cancer.

Review on the recent progress in the development of fluorescent probes targeting enzymes

Enzymes are very important for biological processes in a living being, performing similar or multiple tasks in and out of cells, tissues and other organisms at a particular location. The abnormal activity of particular enzyme usually caused serious diseases such as Alzheimer's disease, Parkinson's disease, cancers, diabetes, cardiovascular diseases, arthritis etc. Hence, nondestructive and real-time visualization for certain enzyme is very important for understanding the biological issues, as well as the drug administration and drug metabolism. Fluorescent cellular probe-based enzyme detectionin vitroandin vivohas become broad interest for human disease diagnostics and therapeutics. This review highlights the recent findings and designs of highly sensitive and selective fluorescent cellular probes targeting enzymes for quantitative analysis and bioimaging.

Ex vivo culture of intact human patient derived pancreatic tumour tissue

The poor prognosis of pancreatic ductal adenocarcinoma (PDAC) is attributed to the highly fibrotic stroma and complex multi-cellular microenvironment that is difficult to fully recapitulate in pre-clinical models. To fast-track translation of therapies and to inform personalised medicine, we aimed to develop a whole-tissue ex vivo explant model that maintains viability, 3D multicellular architecture, and microenvironmental cues of human pancreatic tumours. Patient-derived surgically-resected PDAC tissue was cut into 1-2 mm explants and cultured on gelatin sponges for 12 days. Immunohistochemistry revealed that human PDAC explants were viable for 12 days and maintained their original tumour, stromal and extracellular matrix architecture. As proof-of-principle, human PDAC explants were treated with Abraxane and we observed different levels of response between patients. PDAC explants were also transfected with polymeric nanoparticles + Cy5-siRNA and we observed abundant cytoplasmic distribution of Cy5-siRNA throughout the PDAC explants. Overall, our novel model retains the 3D architecture of human PDAC and has advantages over standard organoids: presence of functional multi-cellular stroma and fibrosis, and no tissue manipulation, digestion, or artificial propagation of organoids. This provides unprecedented opportunity to study PDAC biology including tumour-stromal interactions and rapidly assess therapeutic response to drive personalised treatment.

The COX-2 inhibitor NS398 selectively sensitizes hypoxic HeLa cells to ionising radiation by mechanisms both dependent and independent of COX-2

It is widely accepted that the hypoxic nature of solid tumors contribute to their resistance to radiation therapy. There is increasing evidence that cyclooxygenase-2 (COX-2) contributes to increased resistance of tumors to radiation therapy. Several studies demonstrate that combination of COX-2 selective inhibitors with radiation therapy selectively enhances radio responsiveness of tumor cells. However, the majority of these studies utilised suprapharmacological concentrations under normoxic conditions only. Furthermore, the mechanism by which these agents act remain largely unclear. Therefore, the aim of this study was to determine the impact of COX-2 selective inhibitors on both normoxic and hypoxic radiosensitivity in vitro and the mechanisms underlying this. Because of the close, reciprocal relationship between COX-2 and p53 we investigated their contribution to radioresistance. To achieve this we exposed HeLa, MCF-7 and MeWo cells to the COX-2 selective inhibitor, NS398 (10μM). NS398 (10μM) selectively sensitized hypoxic HeLa and MCF-7 but not MeWo cells to ionising radiation (5 Gy). Furthermore, while knockdown of COX-2 with siRNA did not affect either normoxic radiosensitivity in HeLa cells, the radiosensitisation observed with NS398 was lost suggesting both COX-2 dependent and independent mechanisms. We also show that ionising radiation at 5 Gy results in phosphorylation of p53 at serine 15, a key phosphorylation site for p53-mediated apoptosis, and that hypoxia attenuates this phosphorylation. Attenuated phosphorylation of p53 under hypoxic conditions may therefore contribute to hypoxic radioresistance. We also show that NS398 selectively phosphorylates p53 under hypoxic conditions following irradiation at 5 Gy. p53 phosphorylation could be an underlying mechanism by which this agent and other COX-2 inhibitors sensitize tumors to radiation therapy.

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.

Epoxy-Oxylipins and Soluble Epoxide Hydrolase Metabolic Pathway as Targets for NSAID-Induced Gastroenteropathy and Inflammation-Associated Carcinogenesis

Polyunsaturated fatty acids (PUFAs) including epoxide-modified ω-3 and ω-6 fatty acids are made via oxidation to create highly polarized carbon-oxygen bonds crucial to their function as signaling molecules. A critical PUFA, arachidonic acid (ARA), is metabolized to a diverse set of lipids signaling molecules through cyclooxygenase (COX), lipoxygenase (LOX), cytochrome P450 epoxygenase, or cytochrome P450 hydroxylase; however, the majority of ARA is metabolized into anti-inflammatory epoxides via cytochrome P450 enzymes. These short-lived epoxide lipids are rapidly metabolized or inactivated by the soluble epoxide hydrolase (sEH) into diol-containing products. sEH inhibition or knockout has been a practical approach to study the biology of the epoxide lipids, and has been shown to effectively treat inflammatory conditions in the preclinical models including gastrointestinal ulcers and colitis by shifting oxylipins to epoxide profiles, inhibiting inflammatory cell infiltration and activation, and enhancing epithelial cell defense via increased mucin production, thus providing further evidence for the role of sEH as a pro-inflammatory protein. Non-steroidal anti-inflammatory drugs (NSAIDs) with COX-inhibitor activity are among the most commonly used analgesics and have demonstrated applications in the management of cardiovascular disease and intriguingly cancer. Major side effects of NSAIDs however are gastrointestinal ulcers which frequently precludes their long-term application. In this review, we hope to bridge the gap between NSAID toxicity and sEH-mediated metabolic pathways to focus on the role of epoxy fatty acid metabolic pathway of PUFAs in NSAIDS-ulcer formation and healing as well as inflammation-related carcinogenesis. Specifically we address the potential application of sEH inhibition to enhance ulcer healing at the site of inflammation via their activity on altered lipid signaling, mitochondrial function, and diminished reactive oxygen species, and further discuss the significance of dual COX and sEH inhibitor in anti-inflammation and carcinogenesis.

Inflammation-Related Pancreatic Carcinogenesis: Mechanisms and Clinical Potentials in Advances

Chronic inflammation has long been considered critical in pancreatic carcinogenesis, and recently studies showed that some anti-inflammatory agents such as aspirin could potentially be used to attenuate pancreatic carcinogenesis. Several inflammation-related critical transcription factors and pathways such as NF-κB (nuclear factor κ-light-chain enhancer of activated B cells) and reactive oxygen species have been confirmed to be involved in carcinogenesis. However, its underlying mechanisms are far from clear, which largely limits further development of potential anticarcinogenesis drugs. As a result, it is of great importance for us to better understand and gain a better perspective in inflammation-related pancreatic carcinogenesis. In this review, we systematically analyzed recent advances concerning inflammation-related pancreatic carcinogenesis and brought out the possible underlying mechanisms. Potential preventive and therapeutic strategies based on anti-inflammatory agents have also been further discussed.

Trop2 promotes proliferation, invasion and EMT of nasopharyngeal carcinoma cells through the NF-κB pathway

Human trophoblast cell surface antigen 2 (Trop2), a cell surface transmembrane glycoprotein receptor, has been demonstrated to be closely associated with increasing tumor aggressiveness, metastasis and unfavorable prognosis.

Endoscopic ultrasound-guided fine-needle aspiration cytology in pancreaticobiliary carcinomas: diagnostic efficacy of cell-block immunocytochemistry

BACKGROUND

Endoscopic ultrasound-guided fine-needle aspiration cytology was demonstrated to be a useful tool for the diagnosis and staging of pancreaticobiliary neoplastic lesions. Nonetheless, the diagnostic value of this procedure may be limited by low cellularity of the specimen, contamination of intestinal cells and unfeasibility of ancillary immunocytochemical procedures. The present study was to evaluate its usefulness in the diagnosis of neoplastic lesions.

METHODS

A series of 46 pancreaticobiliary carcinomas with available cell block preparations was submitted to immunocytochemistry against cytokeratins, carcinoembryonic antigen, E-cadherin, CD10 and p53. The sensitivity, specificity, positive and negative predictive values of the cytological smear in the discrimination of malignant lesions were calculated and compared with those of cell block preparation with the immunocytochemical stains against p53 and CD10.

RESULTS

According to our findings, the use of cell block preparations together with immunostains against p53 and CD10 allowed to discriminate malignant versus benign specimens with higher sensitivity than the only cytological examination. In detail, CD10 immunostaining was of significant help for the discrimination between cytological contaminants, such as benign gastrointestinal cells, and the neoplastic elements of pancreaticobiliary well differentiated adenocarcinomas. Also, intense nuclear immunoreactivity for p53 was encountered in about 2/3 of the cases and identified pancreatic malignancy with high sensitivity.

CONCLUSIONS

We suggest that immunocytochemistry against both CD10 and p53 could be applied case by case, mainly to differentiate gastrointestinal and pancreatic benign cellular contaminants showing hyperplasia or reactive changes from differentiated pancreaticobiliary adenocarcinomas.

COX-2 overexpression in resected pancreatic head adenocarcinomas correlates with favourable prognosis

Background

Overexpression of cyclooxygenase-2 (COX-2) has been implicated in oncogenesis and progression of adenocarcinomas of the pancreatic head. The data on the prognostic importance of COX expression in these tumours is inconsistent and conflicting. We evaluated how COX-2 overexpression affected overall postoperative survival in pancreatic head adenocarcinomas.

Methods

The study included 230 consecutive pancreatoduodenectomies for pancreatic cancer (PC, n = 92), ampullary cancer (AC, n = 62) and distal bile duct cancer (DBC, n = 76). COX-2 expression was assessed by immunohistochemistry. Associations between COX-2 expression and histopathologic variables including degree of differentiation, histopathologic type of differentiation (pancreatobiliary vs. intestinal) and lymph node ratio (LNR) were evaluated. Unadjusted and adjusted survival analysis was performed.

Results

COX-2 staining was positive in 71% of PC, 77% in AC and 72% in DBC. Irrespective of tumour origin, overall patient survival was more favourable in patients with COX-2 positive tumours than COX-2 negative (p = 0.043 in PC, p = 0.011 in AC, p = 0.06 in DBC). In tumours of pancreatobiliary type of histopathological differentiation, COX-2 expression did not significantly affect overall patient survival. In AC with intestinal differentiation COX-2 expression significantly predicted favourable survival (p = 0.003). In PC, COX-2 expression was significantly associated with high degree of differentiation (p = 0.002). COX-2 and LNR independently predicted good prognosis in a multivariate model.

Conclusions

COX-2 is overexpressed in pancreatic cancer, ampullary cancer and distal bile duct cancer and confers a survival benefit in all three cancer types. In pancreatic cancer, COX-2 overexpression is significantly associated with the degree of differentiation and independently predicts a favourable prognosis.

PRIMA-1, a mutant p53 reactivator, induces apoptosis and enhances chemotherapeutic cytotoxicity in pancreatic cancer cell lines

TP53 mutation is a common event in many cancers, including pancreatic adenocarcinoma, where it occurs in 50-70 % of cases. In an effort to reactivate mutant p53 protein, several new drugs are being developed, including PRIMA-1 and PRIMA-1(Met)/APR-246 (p53 reactivation and induction of massive apoptosis). PRIMA-1 has been shown to induce apoptosis in tumor cells by reactivating p53 mutants, but its effect in pancreatic cancer remains unclear. Here we investigated the effects of PRIMA-1 on cell viability, cell cycle and expression of p53-regulated proteins in PANC-1 and BxPC-3 (mutant TP53), and CAPAN-2 (wild-type TP53) pancreatic cell lines. Treatment with PRIMA-1 selectively induced apoptosis and cell cycle arrest in p53 mutant cells compared to CAPAN-2 cells. The growth suppressive effect of PRIMA-1 was markedly reduced in p53 mutant cell lines transfected with p53 siRNA, supporting the role of mutant p53 in PRIMA-1 induced cell death. Moreover, treatment with the thiol group donor N-acetylcysteine completely blocked PRIMA-1-induced apoptosis and reinforced the hypothesis that thiol modifications are important for PRIMA-1 biological activity. In combination treatments, PRIMA-1 enhanced the anti-tumor activity of several chemotherapic drugs against pancreatic cancer cells and also exhibited a pronounced synergistic effect in association with the Mdm2 inhibitor Nutlin-3. Taken together, our data indicate that PRIMA-1 induces apoptosis in p53 mutant pancreatic cancer cells by promoting the re-activation of p53 and inducing proapoptotic signaling pathways, providing in vitro evidence for a potential therapeutic approach in pancreatic cancer.

The role of inflammation in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with an extremely poor prognosis. Inflammatory processes have emerged as key mediators of pancreatic cancer development and progression. In genetically engineered mouse models, induction of pancreatitis accelerates PDAC development, and patients with chronic pancreatitis are known to have a higher risk of developing pancreatic cancer. In recent years, much effort has been given to identify the underlying mechanisms that contribute to inflammation-induced tumorigenesis. Many inflammatory pathways have been identified and inhibitors have been developed in order to prevent cancer development and progression. In this chapter, we discuss the role of inflammatory pathways in the initiation and progression of pancreatic cancer as well as the role of inhibitors used in treatment and prevention of pancreatic cancer.

Role of cyclooxygenase-2 in gastric cancer development and progression

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

Selective COX-2 inhibitors for treatment of pancreatic cancer: Research progress

Cyclooxygenase-2 (COX-2) is highly expressed in pancreatic cancer and closely related to the occurrence, development, differentiation, metastasis and prognosis of this malignancy. Selective COX-2 inhibitors have anti-tumor effects both in vivo and in vitro. In this paper we review the recent progress in research on the molecular characteristics of COX-2, the relationship between COX-2 and pancreatic cancer, and the use of selective COX-2 inhibitors for the treatment of pancreatic cancer.

Tumor-stromal interactions in pancreatic cancer

Pancreatic adenocarcinoma has one of the worse prognoses of any cancer with a 5-year survival of only 3%. Pancreatic cancer displays one of the most prominent stromal reactions of all tumors and it is evident that this is a key contributing factor to disease outcome. The tumor microenvironment of pancreatic cancer harbors a wide spectrum of cell types and a complex network of mechanisms which all serve to promote tumor progression. It is clear that the symbiotic relationship between pancreatic cancer cells and stellate cells is the chief factor creating this unique tumor milieu. Pancreatic stellate cells play critical roles in evasion of cancer cell apoptosis, invasion and metastases, angiogenesis, and promotion of an immunosuppressive environment, all key hallmarks of malignancy. Existing treatments for pancreatic cancer focus on targeting the cancer cells rather than the whole tumor, of which cancer cells represent a small proportion. It is now increasingly evident that research targeted towards the interactions between these cell types, ideally at an early stage of tumor development, is imperative in order to propel the way forward to more effective treatments.

Arousal of cancer-associated stromal fibroblasts: palladin-activated fibroblasts promote tumor invasion

Cancer-associated fibroblasts (CAF), comprised of activated fibroblasts or myofibroblasts, are found in stroma surrounding solid tumors; these myofibroblasts promote invasion and metastasis of cancer cells. Activation of stromal fibroblasts into myofibroblasts is induced by expression of cystoskeleton protein, palladin, at early stages in tumorigenesis and increases with neoplastic progression. Expression of palladin in fibroblasts is triggered by paracrine signaling from adjacent k-ras-expressing epithelial cells. Three-dimensional co-cultures of palladin-expressing fibroblasts and pancreatic cancer cells reveals that the activated fibroblasts lead the invasion by creating tunnels through the extracellular matrix through which the cancer cells follow. Invasive tunneling occurs as a result of the development of invadopodia-like cellular protrusions in the palladin-activated fibroblasts and the addition of a wounding/inflammatory trigger. Abrogation of palladin reduces the invasive capacity of these cells. CAF also play a role in cancer resistance and immuno-privilege, making the targeting of activators of these cells of interest for oncologists.

Inhibition of pancreatic intraepithelial neoplasia progression to carcinoma by nitric oxide-releasing aspirin in p48(Cre/+)-LSL-Kras(G12D/+) mice

Nitric oxide-releasing aspirin (NO-aspirin) represents a novel class of promising chemopreventive agents. Unlike conventional nonsteroidal anti-inflammatory drugs, NO-aspirin seems to be free of adverse effects while retaining the beneficial activities of its parent compound. The effect of NO-aspirin on pancreatic carcinogenesis was investigated by assessing the development of precursor pancreatic lesions and adenocarcinomas in Kras(G12D/+) transgenic mice that recapitulate human pancreatic cancer progression. Six-week-old male p48(Cre/+)-LSL-Kras(G12D/+) transgenic mice (20 per group) were fed diets containing 0, 1000, or 2000 ppm NO-aspirin. The development of pancreatic tumors was monitored by positron emission tomography imaging. All mice were killed at the age of 41 weeks and assessed for pancreatic intraepithelial neoplasia (PanIN) and pancreatic ductal adenocarcinoma (PDAC) and for molecular changes in the tumors. Our results reveal that NO-aspirin at 1000 and 2000 ppm significantly suppressed pancreatic tumor weights, PDAC incidence, and carcinoma in situ (PanIN-3 lesions). The degree of inhibition of PanIN-3 and carcinoma was more pronounced with NO-aspirin at 1000 ppm (58.8% and 48%, respectively) than with 2000 ppm (47% and 20%, respectively). NO-aspirin at 1000 ppm significantly inhibited the spread of carcinoma in the pancreas (∼97%; P < .0001). Decreased expression of cyclooxygenase (COX; with ∼42% inhibition of total COX activity), inducible nitric oxide synthase, proliferating cell nuclear antigen, Bcl-2, cyclin D1, and β-catenin was observed, with induction of p21, p38, and p53 in the pancreas of NO-aspirin-treated mice. These results suggest that low-dose NO-aspirin possesses inhibitory activity against pancreatic carcinogenesis by modulating multiple molecular targets.

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.

Dangerous liaisons: pancreatic stellate cells and pancreatic cancer cells

One of the characteristic features of the majority of pancreatic ductal adenocarcinomas is an abundant desmoplastic/stromal reaction. Until recently, this stroma had received little attention from researchers studying the pathogenesis of pancreatic cancer, with most of the research focus resting on the biology of tumor cells themselves. However, evidence is now accumulating that the stroma plays a critical role in pancreatic cancer progression. The cells responsible for producing the stromal reaction in pancreatic cancer are activated pancreatic stellate cells (PSCs, the key effector cells in pancreatic fibrogenesis). In vitro and in vivo studies have convincingly demonstrated a close bi-directional interaction between PSCs and pancreatic cancer cells, which facilitates local tumor growth as well as distant metastasis. PSCs also interact closely with endothelial cells to stimulate angiogenesis and are possibly involved in the known resistance of pancreatic cancer to chemotherapy and radiation. Most interestingly, it has recently been shown that PSCs from the primary tumor can travel to distant metastatic sites where they likely facilitate the seeding, survival, and proliferation of cancer cells. Thus, it is now recognized that the stroma is an important alternative therapeutic target in this disease and concerted pre-clinical research is underway to develop strategies to modulate/deplete the stromal reaction to inhibit cancer progression. The challenge is to translate these developments into clinically applicable treatments for patients.

Inhibition of chronic pancreatitis and pancreatic intraepithelial neoplasia (PanIN) by capsaicin in LSL-KrasG12D/Pdx1-Cre mice

Capsaicin is a major biologically active ingredient of chili peppers. Extensive studies indicate that capsaicin is a cancer-suppressing agent via blocking the activities of several signal transduction pathways including nuclear factor-kappaB, activator protein-1 and signal transducer and activator of transcription 3. However, there is little study on the effect of capsaicin on pancreatic carcinogenesis. In the present study, the effect of capsaicin on pancreatitis and pancreatic intraepithelial neoplasia (PanIN) was determined in a mutant Kras-driven and caerulein-induced pancreatitis-associated carcinogenesis in LSL-Kras(G12D)/Pdx1-Cre mice. Forty-five LSL-Kras(G12D)/Pdx1-Cre mice and 10 wild-type mice were subjected to one dose of caerulein (250 μg/kg body wt, intraperitoneally) at age 4 weeks to induce and synchronize the development of chronic pancreatitis and PanIN lesions. One week after caerulein induction, animals were randomly distributed into three groups and fed with either AIN-76A diet, AIN-76A diet containing 10 p.p.m. capsaicin or 20 p.p.m. capsaicin for a total of 8 weeks. The results showed that capsaicin significantly reduced the severity of chronic pancreatitis, as determined by evaluating the loss of acini, inflammatory cell infiltration and stromal fibrosis. PanIN formation was frequently observed in the LSL-Kras(G12D)/Pdx1-Cre mice. The progression of PanIN-1 to high-grade PanIN-2 and -3 were significantly inhibited by capsaicin. Further immunochemical studies revealed that treatment with 10 and 20 p.p.m. capsaicin significantly reduced proliferating cell nuclear antigen-labeled cell proliferation and suppressed phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun as well blocked Hedgehog/GLI pathway activation. These results indicate that capsaicin could be a promising agent for the chemoprevention of pancreatic carcinogenesis, possibly via inhibiting pancreatitis and mutant Kras-led ERK activation.

Cigarette smoking, cyclooxygenase-2 pathway and cancer

Cigarette smoking is a major cause of mortality and morbidity worldwide. Cyclooxygenase (COX) and its derived prostanoids, mainly including prostaglandin E2 (PGE2), thromboxane A2 (TxA2) and prostacyclin (PGI2), have well-known roles in cardiovascular disease and cancer, both of which are associated with cigarette smoking. This article is focused on the role of COX-2 pathway in smoke-related pathologies and cancer. Cigarette smoke exposure can induce COX-2 expression and activity, increase PGE2 and TxA2 release, and lead to an imbalance in PGI2 and TxA2 production in favor of the latter. It exerts pro-inflammatory effects in a PGE2-dependent manner, which contributes to carcinogenesis and tumor progression. TxA2 mediates other diverse biologic effects of cigarette smoking, such as platelet activation, cell contraction and angiogenesis, which may facilitate tumor growth and metastasis in smokers. Among cigarette smoke components, nicotine and its derived nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are the most potent carcinogens. COX-2 and PGE2 have been shown to play a pivotal role in many cancers associated with cigarette smoking, including cancers of lung, gastric and bladder, while the information for the role of TxA2 and PGI2 in smoke-associated cancers is limited. Recent findings from our group have revealed how NNK influences the TxA2 to promote the tumor growth. Better understanding in the above areas may help to generate new therapeutic protocols or to optimize the existing treatment strategy.

Staining for p53 and Ki-67 increases the sensitivity of EUS-FNA to detect pancreatic malignancy

AIM: To investigate whether tumor marker staining can improve the sensitivity of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) to diagnose pancreatic malignancy.

METHODS: Patients who underwent EUS-FNA were retrospectively identified. Each EUS-FNA specimen was evaluated by routine cytology and stained for tumor markers p53, Ki-67, carcinoembryonic antigen (CEA) and CA19-9. Sensitivity, specificity, positive and negative predictive values (PPV and NPV), and positive and negative likelihood ratios (PLR and NLR) were calculated in order to evaluate the performance of each test to detect malignancy.

RESULTS: Sixty-one specimens had complete sets of stains, yielding 49 and 12 specimens from pancreatic adenocarcinomas and benign pancreatic lesions due to pancreatitis, respectively. Cytology alone had sensitivity and specificity of 41% and 100% to detect malignancy, respectively. In 46% of the specimens, routine cytology alone was deemed indeterminate. The addition of either p53 or Ki-67 increased the sensitivity to 51% and 53%, respectively, with perfect specificity, PPV and PLR (100%, 100% and infinite). Both stains in combination increased the sensitivity to 57%. While additional staining with CEA and CA19-9 further increased the sensitivity to 86%, the specificity, PPV and PLR were significantly reduced (at minimum 42%, 84% and 1, respectively). Markers in all combinations performed poorly as a negative test (NPV 26% to 47%, and NLR 0.27 and 0.70).

CONCLUSION: Immunohistochemical staining for p53 and Ki-67 can improve the sensitivity of EUS-FNA to diagnose pancreatic adenocarcinoma.

Comparative analysis of clinicopathological correlations of cyclooxygenase-2 expression in resectable pancreatic cancer

AIM: To perform a comparative analysis of clinicopathological correlations of cyclooxygenase-2 (COX-2) expression in pancreatic cancer, examined by monoclonal and polyclonal antibodies.

METHODS: The COX-2 expression in 85 resection specimens of pancreatic ductal adenocarcinoma was immunohistochemically examined using both monoclonal and polyclonal antibodies. The final immunoscores were obtained by multiplying the percentage of positive cells with the numeric score reflecting the staining intensity. COX-2 expression levels were classified into three categories (0, 1+, and 2+) and the clinicopathological correlations were statistically evaluated and analyzed.

RESULTS: The positive tumor expression rates of COX-2 were 80.5% using monoclonal antibody and 69.4% using polyclonal antibody. In the Kaplan-Meier analysis, no significant correlations were found between levels of COX-2 expression and overall survival (OS), but trends to longer OS were found in COX-2 negative cases using monoclonal antibody. Significantly longer disease free survival was revealed in COX-2 negative cases using monoclonal antibody (P = 0.019). No correlations between COX-2 expression levels and grade (G), tumor (T) status and nodal (N) status were demonstrated. Low histological grade showed a strong association with a longer OS (P < 0.001). Correlation of survival and T status revealed a shorter OS in T3 tumors, but the results reached only marginal statistical significance (P = 0.070). In the multivariate Cox proportional hazards regression model, histological grade, T and N status remained valuable predictors of a worse survival with borderline significance for T [hazards ratio (HR) = 4.18 for G (if G = 3, P < 0.001); HR = 1.64 for T (if T = 3, P = 0.065); HR = 2.53 for N (if N = 1, P = 0.006)]. Higher grade, T or N status was associated with a worse OS.

CONCLUSION: The immunohistochemically assessed level of COX-2 expression does not seem to represent a valuable independent prognostic factor and is not superior to the conventional prognostic factors.

Loss of 15-hydroxyprostaglandin dehydrogenase increases prostaglandin E2 in pancreatic tumors

OBJECTIVES

Prostaglandin E2 (PGE2) is a product of cyclooxygenase (COX) and PGE synthase (PGES) and deactivated by 15-hydroxyprostaglandin dehydrogenase (PGDH). Down-regulation of PGDH contributes to PGE2 accumulation in lung and colon cancers but has not been identified in pancreatic cancer.

METHODS

Normal human pancreatic and tumor-matched tissues, as well as MiaPaCa-2 and BxPC-3 cell lines, were assessed for COX-2, microsomal PGES-1, PGDH, and snail homolog 1 (SNAI1) and SNAI2 expressions by real-time polymerase chain reaction and Western blotting and PGE2 by enzyme-linked immunosorbent assay.

RESULTS

Normal tissues exhibited low COX-2 messenger RNA (mRNA) and protein expressions and high PGDH mRNA and protein expressions and PGE2 levels at 13 pg/mg of protein. In contrast, tumor tissues exhibited high COX-2 mRNA and protein expressions and low PGDH mRNA and protein expressions and PGE2 levels at 32 pg/mg of protein. Tumor tissues exhibited significantly elevated expressions of SNAI2 mRNA and protein but not SNAI1 because SNAI1 and SNAI2 reportedly down-regulate PGDH expression. The COX-2-positive BxPC-3 but not the COX-2-negative MiaPaCa-2 treated with 100-nmol/L PGE2 induced phosphorylated extracellular signal-related kinase that was blocked by the mitogen-activated protein kinase kinase inhibitor U0126, demonstrating the ability of PGE2 to activate ERK.

CONCLUSIONS

These results suggest that enhanced PGE2 production proceeds through the expressions of COX-2 and microsomal PGES-1 and down-regulation of PGDH by SNAI2 in pancreatic tumors.

Embryonic expression of cyclooxygenase-2 causes malformations in axial skeleton

Cyclooxygenases (COXs) have important functions in various physiological and pathological processes. COX-2 expression is highly induced by a variety of stimuli and is observed during certain periods of embryonic development. In this report, the direct effect of COX-2 expression on embryonic development is examined in a novel COX-2 transgenic mouse model that ubiquitously expresses human COX-2 from the early stages of embryonic development. COX-2 transgenic fetuses exhibit severe skeletal malformations and die shortly after birth. Skeletal malformations are localized along the entire vertebral column and rib cage and are linked to defective formation of cartilage anlagen. The cartilage anlagen of axial skeleton fail to properly develop in transgenic embryos because of impaired precartilaginous sclerotomal condensation, which results from the reduction of cell number in the sclerotome. Despite the ubiquitous expression of COX-2, the number of apoptotic cells is highly increased in the sclerotome of transgenic embryos but not in other tissues, suggesting that it is a tissue-specific response. Therefore, the loss of sclerotomal cells due to an increased apoptosis is probably responsible for axial skeletal malformations in transgenic fetuses. In addition, the sclerotomal accumulation of p53 protein is observed in transgenic embryos, suggesting that COX-2 may induce apoptosis via the up-regulation of p53. Our results demonstrate that the aberrant COX-2 signaling during embryonic development is teratogenic and suggest a possible association of COX-2 with fetal malformations of unknown etiology.

Germ-line mutations, pancreatic inflammation, and pancreatic cancer

The fundamental problem underlying pancreatic cancer is altered genetics. Rare germ-line mutations lead to familial cancer syndromes that may include pancreatic cancer. But why do some people develop pancreatic cancer while others develop cancer in other organs, or not at all? We discuss the possibility that other common germ-line mutations diminish the ability of pancreatic cells to protect themselves from environmental or metabolic stressors, resulting in reactive molecules that lead to cell injury and DNA damage-with a series of lucky hits knocking out key tumor-suppressor genes and activating oncogenes in at least one cell with clonal growth potential. Inflammation likely accelerates this process, whether or not it is clinically evident. We also note the significant effects of smoking, alcohol, antioxidants, and diet on risk, and that together they confer a major portion of attributable risk that may be linked to the injury-inflammation-cancer pathway. Because we cannot change our genes, lifestyle choices are currently the best way to reduce pancreatic cancer risk until more effective preventative strategies are developed.

Fluorocurcumins as cyclooxygenase-2 inhibitor: molecular docking, pharmacokinetics and tissue distribution in mice

PURPOSE

The purpose of the current study was to assess the effect of newly synthesized Curcumin analogs on COX-2 protein by molecular docking studies and by assessments of the effect of one such analog (CDF) on nuclear factor NF-kappaB and PGE(2). In addition, we have determined the pharmacokinetics and tissue distribution of CDF in mice compared to Curcumin.

METHODS

Molecular docking on COX-2 protein was assessed by standard computer modeling studies. PGE(2) assay in conditioned media was done utilizing high sensitivity immunoassay kit following manufacturer's instructions, while NF-kappaB was done by routine EMSA. Serum pharmacokinetics and tissue distribution studies were carried out using the validated high-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) methods.

RESULTS

The molecular docking showed that fluorocurcumin analogs do not introduce any major steric changes compared to the parent Curcumin molecule, which was consistent with down-regulation of NF-kappaB and reduced PGE(2) levels in cells treated with CDF. Pharmacokinetic parameters revealed that CDF had better retention and bioavailability and that the concentration of CDF in the pancreas tissue was 10-fold higher compared to Curcumin.

CONCLUSION

Our observations clearly suggest that the bioavailability of CDF is much superior compared to Curcumin, suggesting that CDF would be clinically useful.

Inflammation and pancreatic cancer: an evidence-based review

There is a growing awareness that inflammation plays a contributory role in numerous pathologies, including pancreatic carcinogenesis. Inflammatory states are characterized by the creation of reactive oxygen species and the induction of cell cycling for tissue growth and repair. The initiation, promotion and expansion of tumors may be influenced by numerous components that function in the inflammatory response. Recognized risk factors for pancreatic cancer include cigarette smoking, chronic/hereditary pancreatitis, obesity and type II diabetes. Each risk factor is linked by the fact that the inflammatory state significantly drives its pathology. This article will outline how inflammatory mechanisms are etiologically linked to pancreatic adenocarcinoma.

Clinicopathological correlations of cyclooxygenase-2, MDM2, and p53 expressions in surgically resectable pancreatic invasive ductal adenocarcinoma

OBJECTIVES

Cyclooxygenase-2 (COX-2) and p53 represent molecules linked to oncogenesis of pancreatic cancer, and there is also a known regulatory loop between mouse double minute 2 (MDM2) and p53. The complex cross talks between p53 and COX-2 and scenarios explaining patterns of p53 and COX-2 expressions in precursor and cancer lesions have been recently reported.

METHODS

The expressions of COX-2, p53, and MDM2 were examined using immunohistochemistry in 85 resection specimens of pancreatic ductal adenocarcinoma.

RESULTS

The positive tumor expression rates of COX-2, p53, and MDM2 were 69.4%, 60.0%, and 41.2%, respectively. Significant correlations between COX-2 and p53 expressions and between p53 and MDM2 expressions were revealed. In the Kaplan-Meier analysis, no statistically significant correlations were found among the levels of COX-2, p53, and MDM2 expressions and survival rates. In the multivariate Cox proportional hazards regression model, grade and nodal status showed to be a valuable predictor of a worse overall survival.

CONCLUSIONS

The reported findings confirmed the relationship of p53, MDM2, and COX-2 with the biological process of pancreatic cancer. The expression of none of the examined proteins showed to be a valuable independent prognostic factor. On the contrary, grade and nodal status showed to be a valuable predictor of a worse survival.

Pancreatic cancer: a plea for good and comprehensive morphological studies

Despite considerable progress, PDA carries a dismal prognosis. Recent advances in clinical and basic science have revealed new insights into pancreatic carcinogenesis. Compelling histopathological and molecular evidence support the evolution of PDA through a series of noninvasive duct lesions named PanINs. Progression of PanIN lesions is associated with genetic and biochemical aberrations correlating with advancing cellular atypia from early stages to invasive cancer. Several studies with pancreatic resection specimens revealed a sequence of genetic changes including activating K-ras mutations, overexpression of the growth factor receptor HER-2/neu, and the inactivation of the tumor suppressor genes INK4A/ARF, TP53, Smad4/DPC4, and BRCA2. The availability of mouse models mimicking human pancreatic cancer allows functional studies which will evaluate relevance for the human disease. Moreover, the precise knowledge of critical events in pancreatic carcinogenesis opens new horizons in designing new diagnostic and therapeutic strategies against this fatal disease.