Eliane Angst

Baicalein, a component of Scutellaria baicalensis, induces apoptosis by Mcl-1 down-regulation in human pancreatic cancer cells ☆

Scutellaria baicalensis (SB) and SB-derived polyphenols possess anti-proliferative activities in several cancers, including pancreatic cancer (PaCa). However, the precise molecular mechanisms have not been fully defined. SB extract and SB-derived polyphenols (wogonin, baicalin, and baicalein) were used to determine their anti-proliferative mechanisms. Baicalein significantly inhibited the proliferation of PaCa cell lines in a dose-dependent manner, whereas wogonin and baicalin exhibited a much less robust effect. Treatment with baicalein induced apoptosis with release of cytochrome c from mitochondria, and activation of caspase-3 and -7 and PARP. The general caspase inhibitor zVAD-fmk reversed baicalein-induced apoptosis, indicating a caspase-dependent mechanism. Baicalein decreased expression of Mcl-1, an anti-apoptotic member of the Bcl-2 protein family, presumably through a transcriptional mechanism. Genetic knockdown of Mcl-1 resulted in marked induction of apoptosis. The effect of baicalein on apoptosis was significantly attenuated by Mcl-1 over-expression, suggesting a critical role of Mcl-1 in this process. Our results provide evidence that baicalein induces apoptosis in pancreatic cancer cells through down-regulation of the anti-apoptotic Mcl-1 protein.

Complicated intra-abdominal infections in Europe: a comprehensive review of the CIAO study

The CIAO Study (“C omplicated Intra-A bdominal infection O bservational” Study) is a multicenter investigation performed in 68 medical institutions throughout Europe over the course of a 6-month observational period (January-June 2012).Patients with either community-acquired or healthcare-associated complicated intra-abdominal infections (IAIs) were included in the study.2,152 patients with a mean age of 53.8 years (range: 4–98 years) were enrolled in the study. 46.3% of the patients were women and 53.7% were men. Intraperitoneal specimens were collected from 62.2% of the enrolled patients, and from these samples, a variety of microorganisms were collectively identified.The overall mortality rate was 7.5% (163/2.152).According to multivariate analysis of the compiled data, several criteria were found to be independent variables predictive of patient mortality, including patient age, the presence of an intestinal non-appendicular source of infection (colonic non-diverticular perforation, complicated diverticulitis, small bowel perforation), a delayed initial intervention (a delay exceeding 24 hours), sepsis and septic shock in the immediate post-operative period, and ICU admission.Given the sweeping geographical distribution of the participating medical centers, the CIAO Study gives an accurate description of the epidemiological, clinical, microbiological, and treatment profiles of complicated intra-abdominal infections (IAIs) throughout Europe.

Chronic stress accelerates pancreatic cancer growth and invasion: A critical role for beta-adrenergic signaling in the pancreatic microenvironment☆

Pancreatic cancer cells intimately interact with a complex microenvironment that influences pancreatic cancer progression. The pancreas is innervated by fibers of the sympathetic nervous system (SNS) and pancreatic cancer cells have receptors for SNS neurotransmitters which suggests that pancreatic cancer may be sensitive to neural signaling. In vitro and non-orthotopic in vivo studies showed that neural signaling modulates tumour cell behavior. However the effect of SNS signaling on tumor progression within the pancreatic microenvironment has not previously been investigated. To address this, we used in vivo optical imaging to non-invasively track growth and dissemination of primary pancreatic cancer using an orthotopic mouse model that replicates the complex interaction between pancreatic tumor cells and their microenvironment. Stress-induced neural activation increased primary tumor growth and tumor cell dissemination to normal adjacent pancreas. These effects were associated with increased expression of invasion genes by tumor cells and pancreatic stromal cells. Pharmacological activation of β-adrenergic signaling induced similar effects to chronic stress, and pharmacological β-blockade reversed the effects of chronic stress on pancreatic cancer progression. These findings indicate that neural β-adrenergic signaling regulates pancreatic cancer progression and suggest β-blockade as a novel strategy to complement existing therapies for pancreatic cancer.

The flavonoid quercetin inhibits pancreatic cancer growth in vitro and in vivo

Objectives The flavonoid quercetin holds promise as an antitumor agent in several preclinical animal models. However, the efficacy of oral administration of quercetin in a pancreatic cancer mouse model is unknown. Methods The antiproliferative effects of quercetin alone or in combination with gemcitabine were tested in 2 human pancreatic cancer cell lines using cell count and MTT assays. Apoptosis was evaluated by flow cytometry. Tumor growth in vivo was investigated in an orthotopic pancreatic cancer animal model using bioluminescence. Quercetin was administered orally in the diet. Results Quercetin inhibited the growth of pancreatic cancer cell lines, which was caused by an induction of apoptosis. In addition, dietary supplementation of quercetin attenuated the growth of orthotopically transplanted pancreatic xenografts. The combination of gemcitabine and quercetin had no additional effect compared with quercetin alone. In vivo quercetin caused significant apoptosis and reduced tumor cell proliferation. Conclusions Our data provide evidence that oral administration of quercetin was capable of inhibiting growth of orthotopic pancreatic tumors in a nude mouse model. These data suggest a possible benefit of quercetin in patients with pancreatic cancer.

Mononuclear cell-derived interleukin-1 beta confers chemoresistance in pancreatic cancer cells by upregulation of cyclooxygenase-2

BACKGROUND Pancreatic cancer is a very aggressive malignancy and efficient therapeutic options are still largely lacking. The importance of interactions between tumor cells and surrounding stromal elements, eg, mononuclear cells, for chemoresistance have been increasingly recognized. In addition, cyclooxygenase-2 is thought to be an important mediator of chemoresistance in several malignancies. The aim of this study was to explore the role of mononuclear cells in pancreatic cancer chemoresistance. METHODS Human histiocytic lymphoma U937 cells were differentiated into macrophage-like cells. The effect of U937-conditioned medium on drug-induced pancreatic cancer cell apoptosis was measured by enzyme-linked immunosorbent assay. The contributions of interleukin-1beta and cyclooxygenase-2 were evaluated by specific receptor antagonists and inhibitors. The importance of the extracellular signal-regulated kinase (ERK1/2) pathway also was determined. RESULTS U937-conditioned culture medium protected pancreatic cancer cells from drug-induced apoptosis. This protective effect was abolished by an interleukin-1 receptor antagonist and cyclooxygenase-2 inhibitor. U937-conditioned medium and interleukin-1beta stimulated expression of cyclooxygenase-2 and prostaglandin E(2) production in pancreatic cancer cells, which was mediated by activation of the ERK1/2 pathway. Transfection of pancreatic cancer cells with cyclooxygenase-2 increased resistance to drug-induced cell death. CONCLUSIONS Mononuclear cells protect pancreatic cancer cells from drug-induced apoptosis in vitro by interleukin-1beta-mediated expression of cyclooxygenase-2 and production of prostaglandins. This study highlights the importance of tumor-host interactions in pancreatic cancers and may provide the basis for novel therapeutic approaches to sensitize pancreatic cancers to chemotherapeutic agents.

Coordinate regulation of PSP/reg and PAP isoforms as a family of secretory stress proteins in an animal model of chronic pancreatitis.

BACKGROUND PSP/reg and PAP are secretory stress proteins (SSP) and may be part of a protective mechanism. They share structural homologies and form insoluble fibrils after tryptic activation. To further explore the regulation of these proteins, we investigated the male WBN/Kob rat, a model of pancreatic inflammatory and fibrotic disease similar to chronic pancreatitis. MATERIALS AND METHODS Expression of PSP/reg and PAP I, II and III in the WBN/Kob rat pancreas was evaluated on the mRNA and protein level, by immunohistochemistry and by highly sensitive isoform specific ELISAs. RESULTS The SSPs are constitutively secreted, PAP in nanomolar, PSP/reg in micromolar concentrations. Before conventional morphological changes are detectable in the WBN/Kob rat, focally increased expression of secretory stress protein is visible. SSP levels in pancreatic juice of WBN/Kob rats reach peak values 10- to 50-fold higher than in Wistar control rats. The highest expression was localized to acini with inflammatory infiltration. CONCLUSIONS There is a tight spatial and temporal association between pre-inflammatory changes or inflammation and SSP-expression. These results support our concept that PSP/reg and PAP are coordinately regulated SSP.

Expression analysis of the prostaglandin E2 production pathway in human pancreatic cancers.

Objectives: There is strong evidence for an important role of cyclooxygenase (COX) 2 and COX-2-generated PGE2 during pancreatic tumorigenesis. Cyclooxygenase 2 has therefore become a potential chemotherapeutic target for pancreatic cancer. However, recent studies raised concerns regarding the safety of selective COX-2 inhibitors. Although the benefits of COX-2 inhibition may eventually outweigh the associated cardiovascular risks, there are a number of alternative targets for inhibiting the formation of PGE2 in human tumors that may prove less harmful to the patient. This study aimed at analyzing the expression of various proteins involved in the generation of PGE2 in human pancreatic cancers. Methods and Results: Real-time polymerase chain reaction and Western blot analyses demonstrated overexpression of cytoplasmic phospholipase A2, COX-2, cytoplasmic prostaglandin E synthase, and microsomal prostaglandin E synthases 1 and 2 in most human pancreatic cancers when compared with matched normal pancreas. Immunohistochemistry revealed expression of these proteins predominantly by pancreatic cancer cells. Variable expression of these proteins was also confirmed in several human pancreatic cancer cell lines. Conclusions: Our studies demonstrated for the first time that various proteins involved in the generation of PGE2 are overexpressed in human pancreatic cancers. These proteins may represent potentially novel targets for the therapy of pancreatic cancers.

Hypoxia increases cytoplasmic expression of NDRG1, but is insufficient for its membrane localization in human hepatocellular carcinoma

NDRG1 is a hypoxia‐inducible protein, whose modulated expression is associated with the progression of human cancers. Here, we reveal that NDRG1 is markedly upregulated in the cytoplasm and on the membrane in human hepatocellular carcinoma (HCC). We demonstrate further that hypoxic stress increases the cytoplasmic expression of NDRG1 in vitro, but does not result in its localization on the plasma membrane. However, grown within an HCC‐xenograft in vivo, cells express NDRG1 in the cytoplasm and on the plasma membrane. In conclusion, hypoxia is a potent inducer of NDRG1 in HCCs, albeit requiring additional stimuli within the tumour microenvironment for its recruitment to the membrane.

Lymphotoxin β Receptor Signaling Promotes Development of Autoimmune Pancreatitis

BACKGROUND & AIMS Little is known about the pathogenic mechanisms of autoimmune pancreatitis (AIP), an increasingly recognized, immune-mediated form of chronic pancreatitis. Current treatment options are limited and disease relapse is frequent. We investigated factors that contribute to the development of AIP and new therapeutic strategies. METHODS We used quantitative polymerase chain reaction, immunohistochemical, and enzyme-linked immunosorbent analyses to measure the expression of cytokines and chemokines in tissue and serum samples from patients with and without AIP. We created a mouse model of human AIP by overexpressing lymphotoxin (LT)α and β specifically in acinar cells (Ela1-LTab mice). RESULTS Messenger RNA levels of LTα and β were increased in pancreatic tissues from patients with AIP, compared with controls, and expression of chemokines (CXCL13, CCL19, CCL21, CCL1, and B-cell-activating factor) was increased in pancreatic and serum samples from patients. Up-regulation of these factors was not affected by corticosteroid treatment. Acinar-specific overexpression of LTαβ (Ela1-LTαβ) in mice led to an autoimmune disorder with various features of AIP. Chronic inflammation developed only in the pancreas but was sufficient to cause systemic autoimmunity. Acinar-specific overexpression of LTαβ did not cause autoimmunity in mice without lymphocytes (Ela1-LTab/Rag1(-/-)); moreover, lack of proinflammatory monocytes (Ela1-LTab/Ccr2(-/-)) failed to prevent AIP but prevented early pancreatic tissue damage. Administration of corticosteroids reduced pancreatitis but did not affect production of autoantibodies, such as antipancreatic secretory trypsin inhibitor in Ela1-LTab mice. In contrast, inhibition of LTβR signaling reduced chemokine expression, renal immune-complex deposition, and features of AIP in Ela1-LTab mice. CONCLUSIONS Overexpression of LTαβ specifically in acinar cells of mice causes features of AIP. Reagents that neutralize LTβR ligands might be used to treat patients with AIP.

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.Abbreviations: COX-2 - cyclooxygenase 2, MEK - mitogen-activated protein kinase kinase, MAPK - mitogen-activated protein kinase, ERK - extracellular signal-related kinase, EGF - epidermal growth factor, PKC - protein kinase C, PG - prostaglandin, PGDH - 15-hydroxyprostaglandin dehydrogenase, mPGES - microsomal prostaglandin E synthase