Akihiko Satoh

Expression of survivin is correlated with cancer cell apoptosis and is involved in the development of human pancreatic duct cell tumors

Survivin is a new member of the inhibitor of apoptosis family of antiapoptotic proteins. This protein was expressed selectively in all the most common human carcinomas but not in normal adult tissues. To our knowledge, the relation between survivin expression and apoptosis or tumorigenesis has not yet been studied in pancreatic neoplasms.

Inhibition of nuclear factor-κB activation improves the survival of rats with taurocholate pancreatitis

Background Death in the early stages of severe acute pancreatitis is frequently the result of multiple organ dysfunction, but its mechanism is not clear. Aims To investigate the state of nuclear factor-κB (NF-κB) in macrophages of rats with lethal pancreatitis, and to assess the effectiveness of pyrrolidine dithiocarbamate, an inhibitor of NF-κB, on the pathology and mortality. Methods Taurocholate pancreatitis was produced in rats, and the severity of the disease, the mortality, and activation of NF-κB in peritoneal and alveolar macrophages were compared in rats receiving pyrrolidine dithiocarbamate (PDTC) treatment and those that were not. Results Taurocholate pancreatitis produced massive necrosis, haemorrhage, and severe leucocyte infiltration in the pancreas as well as alveolar septal thickening in the lung. NF-κB was activated in peritoneal and alveolar macrophages six hours after pancreatitis induction. Pretreatment with PDTC dose-dependently attenuated the NF-κB activation and improved the survival of the rats, although it did not affect the early increase in serum amylase and histological findings. Conclusions Early blockage of NF-κB activation may be effective in reducing fatal outcome in severe acute pancreatitis.

Periostin, secreted from stromal cells, has biphasic effect on cell migration and correlates with the epithelial to mesenchymal transition of human pancreatic cancer cells

Periostin is a secretory protein that has been suggested to function as a cell adhesion molecule and promote the invasiveness or growth rate of tumors. However, little is known about the association of its expression and epithelial to mesenchymal transition (EMT), which is considered to play a crucial role in cancer cell metastasis. Thus, the authors investigated whether periostin could be involved in the process of EMT and the role of this gene in pancreatic cancer development. The expression of periostin was observed mainly in stromal cells but very little in cancer cells by immunohistochemistry and real‐time RT‐PCR. In vitro, pancreatic stellate cells (PSCs) exhibited a much higher basal expression of periostin compared with cancer cells. Periostin secreted in the supernatant from 293T cells that expressed periostin (approximately 150 ng/ml) inhibited the migration of pancreatic cancer cells. Coculture assay revealed that periostin expression in PSC was induced by pancreatic cancer cells. To assess the direct role of periostin in pancreatic cancer cells, the authors generated pancreatic cancer cell lines that stably express periostin. The induced expression of periostin (to 150 ng/ml) altered the morphology of cancer cells, changing them from mesenchymal to epithelial phenotypes with the induction of epithelial markers and a reduction of mesenchymal markers, and showed reduced cell migration in vitro and formed smaller tumors as well as suppressed metastasis in vivo. On the other hand, high concentration of recombinant periostin (1 μg/ml) promoted cell migration with AKT activation. The findings suggest that periostin has biphasic effect on the development of pancreatic cancer.

Myosin light chain kinase inhibitors can block invasion and adhesion of human pancreatic cancer cell lines.

Introduction Invasion and metastasis of pancreatic cancer (PC) require cell motility and adhesion, which depend on the activity of cytoskeleton. A cytoskeletal component indispensable for these processes is myosin II, the cytoplasmic analogue of smooth and skeletal muscle myosin. Aims and methodology Because the activity of myosin II is accelerated by phosphorylation of myosin II on its regulatory light chain (RLC) by myosin light chain kinase (MLCK), we used two specific MLCK inhibitors, ML-7 and ML-9, for suppression of motility and adhesion of PC cell lines. Results Both drugs were potent inhibitors, as measured by in vitro motility assay and adhesion assay. When treated with the same concentration of ML-7, the PC cells were rounded up, and the number of stress fibers was reduced markedly. The in vitro migration and adhesion of PC cells were inhibited by ML-7 and ML-9 in a dose-dependent manner, supporting a specific and competitive inhibition of MLCK by these drugs. The inhibition occurred at nontoxic concentrations. Conclusions These results highlight the importance of myosin II in the invasion and metastasis of PC cells and suggest the possibility that blocking of myosin II activity by a specific MLCK inhibitor may be a therapeutic strategy for preventing the invasion and metastasis of PC.

Pancreatic stellate cells express Toll-like receptors.

BackgroundToll-like receptors (TLRs) are proteins involved in recognition of foreign pathogen-associated molecular patterns (PAMPs) and activation of innate immunity. This study aimed to clarify whether pancreatic stellate cells (PSCs), a major profibrogenic cell type in the pancreas, expressed TLRs and responded to PAMPs.MethodsPSCs were isolated from rat pancreas tissue, and expression of TLRs was examined. PSCs were treated with lipoteichoic acid (a ligand for TLR2), polyinosinic-polycytidylic acid (a ligand for TLR3), lipopolysaccharide (a ligand for TLR4), or flagellin (a ligand for TLR5). The effects of the TLR ligands on key cell functions and activation of signaling pathways were examined. The ability of PSCs to perform endocytosis and phagocytosis was also examined.ResultsPSCs expressed TLR2, 3, 4, and 5, as well as the associated molecules CD14 and MD2. All of the TLR ligands activated nuclear factor-κB, and three classes of mitogen-activated protein kinases (extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase). TLR ligands induced expression of monocyte chemoattractant protein 1, cytokine-induced neutrophil chemoattractant 1 (a rat homolog of interleukin-8), and inducible nitric oxide synthase, but not proliferation or type I collagen production. PSCs could perform fluid-phase and receptor-mediated endocytosis, as well as phagocytosis of Escherichia coli.ConclusionsPSCs expressed a variety of TLRs and responded to TLR ligands, leading to the activation of signaling pathways and proinflammatory responses. PSCs could process exogenous antigens by endocytosis and phagocytosis. PSCs might play a role in the immune functions of the pancreas through the recognition of PAMPs.

Human Leukocyte Antigen-DR Expression on Peripheral Monocytes as a Predictive Marker of Sepsis During Acute Pancreatitis

Introduction The mortality associated with severe acute pancreatitis is still high, and death in the later stage of the disease is chiefly due to bacterial infection and sepsis. However, objective parameters for the risk of sepsis in acute pancreatitis have not been established. Aim To investigate the value of human leukocyte antigen-DR (HLA-DR) on peripheral monocytes for predicting the development of sepsis during acute pancreatitis. Methodology The expression of HLA-DR on peripheral monocytes was measured in 64 patients by flow cytometry at admission and 7 and 14 days after the onset of acute pancreatitis. Twenty-eight patients with severe acute pancreatitis and 36 with mild acute pancreatitis, as determined by the Atlanta classification, were enrolled. Results Six patients had sepsis, and two of them died during the hospital stay. At admission, the percentage of HLA-DR-expressing cells in the monocyte population was significantly lower in the patients who had sepsis in the later course than in the patients who did not have sepsis. A percentage lower than 80% at admission was observed in 17 patients, and the patients who had persistently low percentages of HLA-DR-expressing monocytes throughout the observation period had sepsis in the later clinical course, whereas the patients in whom expression recovered to the normal range were spared the development of sepsis. Conclusion In acute pancreatitis, the low percentage of HLA-DR-expressing cells in the monocyte population is a reliable predictor of the development of sepsis. Monitoring of monocyte HLA-DR expression may be a useful marker for identifying the patients who are at high risk of sepsis in acute pancreatitis.

Activated rat pancreatic stellate cells express intercellular adhesion molecule-1 (ICAM-1) in vitro.

IntroductionActivated pancreatic stellate cells (PSCs) have recently been implicated in the pathogenesis of pancreatic fibrosis.AimsTo examine the role of PSCs in pancreatic inflammation by determining whether activated PSCs express intercellular adhesion molecule-1 (ICAM-1).MethodologyCulture-activ

The sixth nationwide epidemiological survey of chronic pancreatitis in Japan

OBJECTIVES A nationwide survey was conducted to clarify the epidemiological features of patients with chronic pancreatitis (CP) in Japan. METHODS Two sequential surveys were conducted. In the first survey, both the prevalence and incidence of CP in Japan in 2007 were estimated by a questionnaire, which was mailed to 3027 randomly chosen Japanese facilities. In the second survey, the second questionnaire was then mailed to 1110 facilities selected by the first survey to clarify the clinicoepidemiological features of the patients. RESULTS The estimated annual prevalence of CP was 36.9 per 100,000; 53.2 in males and 21.2 in females. The estimated annual incidence was 11.9 per 100,000. The prevalence and the incidence of CP gradually increased in Japan as compared to former surveys. The sex ratio (male/female) of definitive and probable CP patients was 4.5, with a mean age of 59.4 years; 59.2 years in males and 60.2 years in females. Alcoholic (69.7%) was most the common and idiopathic (21.0%) was the second most common cause of CP. The proportion of alcoholic CP increased as compared to the 55.5% found in 1994. The clinical features of overall Japanese patients with CP were: abdominal pain (60.6%), malabsorbtion (12.2%), diabetes mellitus (39.7%) and pancreatolithiasis (75.7%). Alcoholic patients were characterized by high morbidity as compared to nonalcoholic patients: abdominal pain (alcoholic 65.0% vs nonalcoholic 53.0%, p < 0.0001), diabetes mellitus (44.8% vs 31.4%, p < 0.0001) and pancreatolithiasis (84.0% vs 60.8%, p < 0.0001). CONCLUSION The prevalence and the incidence of CP, especially alcoholic CP, have been increasing in Japan.

Ligands of peroxisome proliferator-activated receptor-γ induce apoptosis in AR42J cells

Introduction Peroxisome proliferator-activated receptor-&ggr; (PPAR-&ggr;) is a ligand-activated transcription factor that controls growth, differentiation, and inflammation in different tissues. Roles of PPAR-&ggr; activation in pancreatic acinar cells are poorly characterized. Aims To examine the effects of PPAR-&ggr; activation on the induction of apoptosis in rat pancreatic AR42J cells. Methodology AR42J cells were treated with ligands of PPAR-&ggr;, and induction of apoptosis was evaluated by cell viability, DNA-fragmentation, and flow cytometry. Results Treatment of the cells with ligands of PPAR-&ggr; (15-deoxy-▵12,14-prostaglandin J2 or troglitazone) induced apoptosis in a dose-dependent manner. Troglitazone-induced apoptosis was not blocked by inhibitors of caspases (acetyl-DEVD-aldehyde and benzoyloxycarbonyl-VAD-fluoromethylketone). Troglitazone induced the expression of pancreatitis-associated protein-1 and clusterin mRNAs. Troglitazone activated c-Jun NH2-terminal kinase/stress-activated protein kinase, but inhibited the activation of extracellular signal-regulated kinases 1/2. Troglitazone did not activate NF-&kgr;B, suggesting a role of NF-&kgr;B-independent pathways. In AR42J cells and isolated pancreatic acini, PPAR-&ggr; gene and protein were detected. In addition, troglitazone increased the PPAR-dependent transcriptional activity, suggesting that PPAR-&ggr; is functional in AR42J cells. Conclusion These results indicate that activation of PPAR-&ggr; induces apoptosis in AR42J cells and imply that PPAR-&ggr; may be a potential therapeutic target of pancreatic inflammation, because of its anti-inflammatory effects in addition to its proapoptotic effects.

Lysophosphatidylcholine induces apoptosis in AR42J cells

Phospholipase A2 (PLA2) has been suggested to play an important role in the pathogenesis of acute pancreatitis, in part through the PLA2-generated phospholipid by-products, most notably lysophosphatidylcholine (lyso-PC). The effects of lyso-PC on pancreatic acinar cells, other than the induction of necrosis, are poorly characterized. Here we examined the effects of lyso-PC on the induction of apoptosis in rat pancreatic AR42J cells. Lyso-PC induced apoptosis in a dose-dependent manner at 10 and 25 &mgr;M, but induced cell lysis at ≥50 &mgr;M. Lyso-PC–induced (at 25 &mgr;M) apoptosis was not blocked by a protein kinase C inhibitor (staurosporine) or by inhibitors of caspases (acetyl-DEVD-aldehyde and benzoyloxycarbonyl-VAD-fluoromethylketone). Lyso-PC at 10 and 25 &mgr;M induced the expression of clusterin mRNA and wild-type p53. Apoptosis induction by lyso-PC (at 25 &mgr;M) was not inhibited by a specific antagonist of platelet-activating factor (PAF) receptor, suggesting that the action was independent of the PAF receptor. These molecular events suggest a novel role of lyso-PC in the modulation of acinar cell function.