Takaaki Mizushima

Epidermal Growth Factor Receptor Mediates Increased Cell Proliferation, Migration, and Aggregation in Esophageal Keratinocytes in Vitro and in Vivo

Epidermal growth factor receptor (EGFR) overexpression is observed in a number of malignancies, especially those of esophageal squamous cell origin. However, little is known about the biological functions of EGFR in primary esophageal squamous epithelial cells. Using newly established primary human esophageal squamous epithelial cells as a platform, we overexpressed EGFR through retroviral transduction and established novel three-dimensional organotypic cultures. Additionally, EGFR was targeted in a cell type- and tissue-specific fashion to the esophageal epithelium in transgenic mice. EGFR overexpression in primary esophageal keratinocytes resulted in the biochemical activation of Akt and STAT pathways and induced enhanced cell migration and cell aggregation. When established in organotypic culture, EGFR-overexpressing cells had evidence of epithelial cell hyperproliferation and hyperplasia. These effects were also observed in EGFR-overexpressing transgenic mice and the esophageal cell lines established thereof. In particular, EGFR-induced effects upon aggregation appear to be mediated through the relocalization of p120 from the cytoplasm to the membrane and increased interaction with E-cadherin. EGFR modulates cell migration through the up-regulation of matrix metalloproteinase 1. Taken together, the functional effects of EGFR overexpression help to explain its role in the initiating steps of esophageal squamous carcinogenesis.

Study on free radicals and pancreatic fibrosis-pancreatic fibrosis induced by repeated injections of superoxide dismutase inhibitor

The exact mechanisms of the development of pancreatic fibrosis are still unknown. To clarify the relationship between pancreatic fibrosis and free radicals, the effect of the administration of a superoxide dismutase (SOD) inhibitor, diethyldithiocarbamate (DDC), on pancreatic fibrosis in rats was studied. A single intraperitoneal injection of 500 mg/kg of DDC significantly reduced SOD activity and significantly increased lipid peroxidation products in the pancreas, showing no histologic changes of inflammation or necrosis. Repeated administration of 500 mg/kg DDC, twice a week, caused inter-and intralobular fibrosis with atrophy of acinar cells in the pancreas for at least 2 weeks without fibrosis of the liver and kidney. Administration of allopurinol showed preventive effects against DDC-induced pancreatic fibrosis. In conclusion, repeated administration of DDC, which caused pancreatic fibrosis, is a new experimental model of pancreatic fibrosis from the viewpoint of oxidative stress.

Matrix metalloproteinase-2 in pancreatic juice for diagnosis of pancreatic cancer

Introduction Matrix metalloproteinase-2 (MMP-2) has an activity to degrade type IV collagen and is associated with invasion angiogenesis of malignant tumor. Aim A diagnostic value of MMP-2 in pancreatic juice was studied in the diagnosis of pancreatic cancer. Methodology Using gelatin zymography, active MMP-2 and proMMP-2 were determined in pancreatic juice obtained endoscopically from 12 patients with pancreatic cancer, 11 with chronic pancreatitis, and 7 control subjects. Results ProMMP-2 was detected in 12 of 12 patients (100%) with pancreatic cancer, 6 of 11 (54.5%) with chronic pancreatitis, and 3 of 7 (42.9%) controls. Active MMP-2 was detected in 11 patients (91.6%) with pancreatic cancer, 2 (18.2%) with chronic pancreatitis, and none of the control subjects. An activation ratio of MMP-2 (active MMP-2/total MMP-2) in pancreatic juice is significantly higher in pancreatic cancer (23.4 ± 4.4%, mean ± SE) than in chronic pancreatitis (2.1 ± 1.7%) and controls (0%) (p < 0.01). Active MMP-2 was also detected in pancreatic juice from three cases of small pancreatic cancer (tumor <2 cm in diameter). Conclusion Our observation suggests that detection of active MMP-2 in pancreatic juice using gelatin zymography may be useful for the diagnosis of pancreatic cancer.

Intraductal secretin test is as useful as duodenal secretin test in assessing exocrine pancreatic function

We assessed the clinical usefulness of theintraductal secretin test in order to ascertain whetherit can substitute for the conventional duodenal secretintest. Duodenal juice was obtained with a triple-lumen tube and pure pancreatic juice was obtained byretrograde cannulation of the main pancreatic duct usinga duodenofiberscope. Pancreatic secretion was stimulatedby a bolus intravenous injection of secretin (100 units). The two tests showed comparableinterindividual coefficients of variation, significantlygood correlations, and comparable diagnosticefficiencies. The intraductal secretin test showed noless reproducibility than that of the duodenalsecretin test as reported in the literature. In theintraductal secretin test, secretory volume, peak flowrate, bicarbonate output, and lipase output yielded the best diagnostic efficiency, followed by amylaseoutput and maximal bicarbonate concentration. In theintraductal secretin test, a 10-min collection providedas much information as a 20-min collection. We conclude, therefore, that the 10-minintraductal secretin test is as useful as theconventional duodenal secretin test in assessingexocrine pancreatic function and that the mostdiscriminatory parameters are secretory volume, bicarbonate output, andamylase (or lipase) output.

Camostat, an oral trypsin inhibitor, reduces pancreatic fibrosis induced by repeated administration of a superoxide dismutase inhibitor in rats

Background and Aim:  An oral trypsin inhibitor, camostat (CM), has a beneficial effect on chronic pancreatitis, but its mechanism is not yet fully understood. Recently, pancreatic stellate cells (PSC) have been reported to play an essential role in pancreatic fibrosis. An experimental model of pancreatic fibrosis induced by a superoxide dismutase (SOD) inhibitor (diethyldithiocarbamate [DDC]) was developed in rats. Thus, the effect of an oral trypsin inhibitor on pancreatic fibrosis and PSC was investigated.

Prevention of hyperlipidemic acute pancreatitis during pregnancy with medium-chain triglyceride nutritional support

SummaryConclusionA combination of diet therapy, nutritional support with medium-chain triglycerides (MCT), and well-planned preterm Cesarean delivery on demand is an effective measure to prevent gestational hyperlipidemic pancreatitis and leads to successful childbirth.BackgroundPrevention and therapy of gestational hyperlipidemic pancreatitis are important, although difficult, because the condition carries a high maternal and fetal morbidity and mortality.ResultsWe describe a 32-yr-old female with lipoprotein lipase-deficient familial hypertriglyceridemia who had recurrent episodes of acute pancreatitis. The third episode occurred with worsened hyperlipidemia 7 yr earlier at 32 wk of her first pregnancy and resulted in fetal death. The fourth and fifth episodes were also accompanied by marked hyperlipidemia probably caused by drug discontinuance and dietary noncompliance. She became pregnant. Serum triglyceride levels were controlled below 2000 mg/dL by strict monitoring with low-fat, low-calorie diet and MCT nutritional support. A premature but healthy infant was born by Cesarean delivery at 36 wk of gestation when the mother presented with mild abdominal pain and was found to have uterine contractions. The ensuing clinical course has been uneventful.

Chronic Pancreatitis: Functional Testing

This article reviews the evolution of functional testing of the pancreas in Japan for the diagnosis and treatment of chronic pancreatitis (CP), contrasting the pre- with the postsecretin test (S test) era. In the pre-S test era, the diagnosis was based on symptoms, clinical findings, fasting serum diastase levels, and the vagostigmin- and ether-stimulation test unless morphologic evidence was available. The S test and CCK-pancreozymin (PZ) test (PS test) were introduced into Japan around 1963 and have been used as the gold standard of the exocrine pancreatic-function test. Through a series of attempts at standardization in 1971, 1985, and 1987, the method was standardized to collect duodenal juice for 60 min through a double- or triple-lumen tube after a bolus or during a continuous i.v. injection of secretin (100 U). The S test, however, is an invasive and cumbersome procedure. As a result, N-benzoyl-L-tyrosal-p-aminobenzoic acid (BT-PABA) testing and fecal chymotrypsin testing were introduced into Japan in the middle and late 1970s, respectively. Although simple and noninvasive, these two methods were found have lower sensitivity and specificity than the conventional S test. These two methods, therefore, are presently used more often for monitoring the course of disease and therapeutic effects. Additionally, the glucose tolerance test can be performed to detect endocrine pancreatic insufficiency.

A case of small pancreatic cancer diagnosed by serial follow-up studies promptly by a positive K-ras point mutation in pure pancreatic juice

We report a 74-yr-old woman who was referred to our hospital because of abdominal fullness. ERP showed a questionable irregularity of the main pancreatic duct at the body. Examination of pure pancreatic juice was positive for K-ras point mutation at codon 12 and negative for cytology. Because neither US nor CT showed apparent lesions in the pancreas, we decided to follow up the patient with serial ERP and pure pancreatic juice studies at 3-month intervals. No changes had been seen up to 18 months later, when cytology was conclusive for malignancy with an apparent stenosis of the main pancreatic duct at the body. Distal pancreatectomy with splenectomy was performed. A round mass, 12 mm in diameter, was found in the body, which proved to be an adenocarcinoma at histological examination. No extrapancreatic extension and metastases were noted. Although positive K-ras point mutation has been reported in some cases of adenoma or mucinous cell hyperplasia of the pancreas and chronic pancreatitis, our case, along with previous reports, indicated the importance of testing K-ras point mutation in pure pancreatic juices for the diagnosis of pancreatic cancer at an early stage.

Pancreatic enzyme supplement improves dysmotility in chronic pancreatitis patients

Background and Aims:  Impaired gallbladder contraction and rapid gastric emptying in patients with chronic pancreatitis may be the result of depleted pancreatic exocrine function. The authors tested whether oral pancreatic enzymes can improve the dysmotility or not.

Xanthine oxidase-derived free radicals directly activate rat pancreatic stellate cells.

Background and Aim:  Free radicals are reported to be associated with fibrosis in the pancreas. It is generally accepted that pancreatic stellate cells (PSC) play an important role in pancreatic fibrosis. However, the exact role of free radicals in activation of PSC has not been fully elucidated. In the present study, using a superoxide dismutase (SOD) inhibitor, diethyldithiocarbamate (DDC) with cultured PSC, we investigated how free radicals act on the activation of PSC.