Effect of orchiectomy and testosterone on the early stages of azaserine-induced pancreatic carcinogenesis in the rat

The incidence of carcinoma of the pancreas is higher among men than women. It is also higher among male than female carcinogen-treated rats. The role of testosterone in this preferential induction of pancreatic cancer was evaluated in a rat model of pancreatic carcinogenesis. Two-week-old Lewis rats were treated with a single injection of azaserine. At weaning (3 weeks), rats were divided into five groups as follows: females; intact males; sham-operated males; orchiectomized males; and orchiectomized males plus testosterone. Four months after administration of azaserine, quantitative histologic analysis of atypical acinar cell foci and nodules of the pancreas showed that in female and orchiectomized male rats, foci and nodules were smaller and less numerous than in intact males. Testosterone treatment partly reversed the effect of orchiectomy. This suggests that the susceptibility of male rats to induction of pancreatic carcinomas by azaserine is at least partially mediated by testosterone. Estrogen and testosterone receptors were assayed, but high-affinity receptors characteristic of gonadal tissues were not detected in normal pancreas or in a transplantable azaserine-induced acinar cell carcinoma. Thus, the effect of testosterone in the pancreas may depend on steroid-binding proteins of another type, or may be indirectly mediated.     

Precancerous conditions of pancreatic carcinoma

The precancerous conditions associated with pancreatic ductal carcinoma include preneoplastic duct changes and benign-looking tumors that give rise to ductal carcinomas. Among the duct changes that are discussed as precancerous lesions are hyperplastic and metaplastic lesions, which were recently classified as pancreatic intraepithelial neoplasia types 1A, 1B, 2, and 3. This new system is compared with the older terminology. Recent molecular findings concerning the most frequent genetic alterations in manifest carcinomas support the new classification system. The relative frequency of duct lesions in the nonneoplastic pancreas and their association with chronic pancreatitis and ductal carcinoma are discussed. Finally, the pancreatic exocrine tumors that may give rise to ductal carcinomas are presented.     

Cystic and solid lesions of the pancreas

More than 95% of malignant tumours of the pancreas are exocrine carcinomas. The exocrine carcinomas have to be distinguished from benign serous cystadenomas and tumours, the latter including mucinous cystic neoplasms, serous cysts, and solid pseudopapillary neoplasms. Cystic lesions have to be separated from pseudocysts, which are the most common cysts. Pseudocysts are due to extensive confluent autodigestive tissue necrosis caused by alcoholic, biliary, or traumatic acute pancreatitis. This review focuses on the classification of the different types of solid and cystic lesions based on histological criteria. The various imaging procedures are also discussed, along with their strengths and limitations.     

Reduced reactivity of pancreatic exocrine secretion in response to gastrointestinal hormone in WBN/Kob rats

We compared pancreatic exocrine secretion in 5-month-old WBN/Kob rats, a model of chronic pancreatitis, with that in Wistar rats of the same age in a conscious state. Basal pancreatic secretion and pancreatic wet weight in WBN/Kob rats were lower than the values for Wistar rats. There was no difference in plasma cholecystokinin (CCK) concentration between the two types of rats. When CCK-8 was intravenously administered, the stimulation of pancreatic protein secretion in WBN/Kob rats was weaker than that in Wistar rats. When bile and pancreatic juice were diverted from the duodenum, the resulting increase in the plasma CCK concentration was similar in both types of rats, but stimulation of the volume and protein output of pancreatic juice in WBN/Kob rats was weaker than that in Wistar rats. In addition, WBN/Kob rats exhibited little increase in pancreatic wet weight because of this diversion. When secretin was intravenously administered, the stimulation of fluid secretion in WBN/Kob rats was also weaker than that in Wistar rats. The binding of CCK-8 to pancreatic membrane fractions in WBN/Kob rats was much weaker than that in Wistar rats. Histological findings in WBN/Kob rat pancreas showed proliferation of fibrous tissue and atrophy of acinar cells. In conclusion, pancreatic exocrine secretion in response to the gastrointestinal hormones, CCK and secretin, was lower in WBN/Kob rats than in Wistar rats. These findings suggest that the hyposecretion of pancreas in WBN/Kob rats is hyporeaction of pan-creatic membrane to gastrointestinal hormones. (Received Feb. 5, 1997; accepted July 25, 1997)     

The patient with slightly elevated pancreatic enzymes and abdominal complaints

Abdominal complaints in combination with slightly elevated serum pancreatic enzymes represent a classical clinical challenge. These symptoms may be due to coincidental unrelated harmless disorders, benign pancreatic alterations which are fairly easily treatable such as mild acute pancreatitis or uncomplicated chronic pancreatitis. However, serious, often insidious diseases such as pancreatic tumours may also present with this constellation as their first signs. Diagnostic procedures need to be stratified according to acuteness and severity of symptoms. While patients with acute onset of symptoms and severe complaints need immediate and combined laboratory and imaging investigations to allow adequate therapy, chronic and mild complaints usually justify a stepwise diagnostic approach consecutively using abdominal ultrasound, CT/MRI and endoscopic ultrasound as imaging procedures and reserving ERCP for cases which remain unclear or in which interventional therapy is needed. Diagnosis and follow-up are often particularly demanding in patients with cystic tumours of the pancreas. In chronic pancreatitis patients pain therapy and adequate control of pancreatic exocrine insufficiency may pose major problems. Patients with refractory pain may ultimately require surgical intervention. Another important indication for surgery in chronic pancreatitis is suspicion of cancer that cannot be ruled out by dedicated diagnostic procedures. This also applies to cystic tumours of the pancreas, which have a high risk of malignant transformation or may even already represent pancreatic cancer at the time of diagnosis.     

Potentiation of pancreatic carcinogenesis in the rat by DL-ethionine-induced pancreatitis

We have assessed the influence of an attack of acute pancreatitis on the incidence of experimentally induced pancreatic cancer in rats. A low-protein diet plus repeated injections of DL-ethionine produced acute pancreatitis in rats. The animals were then fed either a diet of raw soya flour or a non-soya-containing diet and given repeated injections of azaserine, a weak pancreatic carcinogen. The rats that had recovered from acute pancreatitis developed pancreatic cancer, whereas those without previous pancreatitis did not. We conclude that the interaction of recovery from acute pancreatitis with a pancreatic carcinogen predisposes to pancreatic cancer in rats.     

Pancreatic exocrine function during acute exacerbation in WBN/Kob rats with spontaneous chronic pancreatitis

Summary Conclusion Pancreatic exocrine hypofunction is markedly deteriorated during acute exacerbation in a rat model with chronic pancreatitis. Background Little is known about pancreatic exocrine function during acute exacerbation in patients with chronic pancreatitis. We investigated changes in pancreatic exocrine function after inducing acute pancreatitis in an animal model of spontaneous chronic pancreatitis. Methods WBN/Kob rats with chronic pancreatitis sequentially underwent pancreatic exocrine function test 1–6 d after surgical preparation with external pancreatic fistula. We induced acute pancreatitis in another WBN/Kob rats by iv administration of cerulein at a rate of 10 μg/kg/h for 4 h 4 after surgical preparation. Pancreatic exocrine function test was undertaken in a conscious state 1 d before and after cerulein administration. Results In WBN/Kob rats not given cerulein, pancreatic exocrine function remained almost constant, at 3–6 d after surgery. Marked hyperamylasemia developed immediately after cerulein administration. After its administration, the pancreas microscopcially showed prominent intersitial edema and intracellular vacuolization of acinar cells in addition to the finding of pre-existing chronic pancreatitis. Basal and chole-cystokinin-stimulated flow rate, bicarbonate output, and protein output, which were substantially impaired 1 d before cerulein administration, were further reduced 1 d after its administration.     

Relation between chronic pancreatitis and pancreatic cancer in the light of surgical management

BACKGROUND/AIMS: Relation between cancer of the exocrine part of the pancreas and chronic pancreatitis has not been clearly defined and the problem of carcinogens based on long-lasting chronic pancreatitis is still a matter of discussion. METHODOLOGY: The aim of the study was analysis of postoperative material of patients who in the years 1999-2003 underwent either drainage procedures (n=49) in the course of chronic pancreatitis or resectional procedures (n=36) for chronic pancreatitis or pancreatic cancer. RESULTS: In the group of patients with drainage procedures pancreatic cancer was histologically detected in postoperative material (specimens collected from the wall of pancreatic pseudocyst or dilated main pancreatic duct) in 3 patients (6.1%). In the group of patients with long-lasting chronic pancreatitis who underwent a resectional procedure pancreatic cancer was postoperatively detected in 4 cases (30.7%). CONCLUSIONS: Analysis of presented material confirms that long-lasting chronic pancreatitis predisposes to cancer of the exocrine part of the pancreas. This indicates that risk of pancreatic cancer should be taken into consideration in each patient with long lasting chronic pancreatitis.     

正常胰腺及胰腺占位病变超声内镜弹性成像特点初步研究

目的 初步探讨正常胰腺及胰腺与位病变的超声内镜弹性成像特征及其在良恶性鉴别中的价值.方法 自2009年1月至6月,对9例胰腺占位病变行EUS的患者同时进行超声内镜实时弹性成像,同时选取6例因其他病变而行EUS者的正常胰腺行超声内镜实时弹性成像作对照,按照弹性成像5分法对组织弹性成像进行评分.结果 9例胰腺占位病变患者最终诊断为胰腺癌4例,囊腺癌1例,囊腺瘤2例,局限性胰腺炎2例,其弹性成像评分：胰腺癌1例3分、3例4分,囊腺癌5分,2例囊腺瘤均为2分,局限性胰腺炎2分和3分各1例;6例正常胰腺者其弹性成像评分1分5例,2分1例.当以1、2分为良性,3～5分为恶性病变的标准进行判断时,超声内镜弹性成像对9例胰腺占位性病变良恶性鉴别有8例准确.结论 胰腺良恶性组织弹性成像呈不同的图像特征,超声内镜实时弹性成像有助于胰腺良恶性病变的鉴别.     

Effect of long term alcohol feeding on the pancreas in rat

To elucidate the pathophysiological process of alcoholic pancreatitis, chronic alcohol intoxication was made in Wistar rats on balanced diet giving 20% ethanol freely for 60 weeks. The control rats received water. Histological picture of the pancreas, hormonal activity in the mucosa of upper digestive tract and the nature of pancreatic juice were examined in every 15th week. The results were as follows. 1) No histological changes were noted in the pancreas of control group. In the ethanol group, morphological abnormalities of the pancreas appeared after 30 weeks. Of the histological findings, the changes on the ductal system such as dilatation of pancreatic duct, plug formation in the ductal lumen and periductal fibrosis were significant. 2) The long term ethanol administration tended to decrease the amounts of gastrin, secretin and cholecystokinin contained in the gastrointestinal mucosa. 3) Regardless of the histological changes of the pancreas, almost no changes were noted in the bicarbonate and protein concentration during the experimental period of 60 weeks. From the above results, a mechanism obstructing pancreatic ductal system is considered to be important in the pancreatic lesions by alcohol rather than a mechanism of stimulating pancreatic exocrine secretion.     

Expression of Tn, sialosyl Tn, and T antigens in human pancreas.

Carbohydrate antigens representing some of the initial steps in mucin O-linked glycosylation were examined in specimens of normal pancreas, chronic pancreatitis, and pancreatic adenocarcinoma. Tn antigen, recognized by Vicia villosa lectin, was expressed by all specimens of normal pancreas (acinar cells) and pancreatic cancers and all but one case of chronic pancreatitis. Sialosyl Tn antigen, recognized by monoclonal antibody TKH2, was expressed in a cancer-associated fashion, being completely absent in normal pancreas but expressed by 56% of chronic pancreatitis and 97% of pancreatic cancers. T antigen, recognized by monoclonal antibody AH9-16, was expressed in 68% of normal pancreas (acinar cells), 67% of chronic pancreatitis, and 48% of pancreatic cancer tissues. These results indicate that normal acinar cells of the pancreas are capable of expressing selected carbohydrate structures associated with the initial steps of mucin glycosylation. The marked expression of sialosyl Tn compared with T antigen in pancreatic cancers suggests that with malignant transformation there is selective usage of glycosyltransferase enzymes involved in mucin oligosaccharide synthesis.     

Clinical relevance of endosonography in diagnosis of pancreatobiliary diseases]

Endoscopic ultrasonography allows a high-resolution imaging of the pancreas and the extrahepatic biliary tract due to the high ultrasonic frequencies employed. This is of clinical benefit in the delineation of small pancreatic carcinomas complementary to ERCP and in the preoperative localization of endocrine tumors of potential pancreatic origin. Endosonography is the most accurate method presently available for the local staging of pancreatobiliary malignancy and thus helps avoiding diagnostic laparotomy for staging purposes. The role of endoscopic ultrasonography in the diagnosis of benign diseases such as chronic pancreatitis and choledocholithiasis has not yet fully been established. Endosonography, however, has no role in the differential diagnosis of benign and malignant disorders of the pancreas and biliary tract.     

Differentiation of chronic pancreatitis from pancreatic cancer: recent advances in molecular diagnosis

Chronic pancreatitis is an inflammatory disease of the pancreas, characterized by a progressive destruction of the exocrine and endocrine pancreas, leading both to exocrine and endocrine insufficiency. In recent years, our knowledge of this disease has improved, an epidemiological link between chronic pancreatitis and pancreatic cancer has been established, and the molecular alterations underlying their pathogenesis have been partly revealed. Nevertheless, the differentiation of chronic inflammation of the pancreas from cancer of the pancreas remains a great challenge. This overview will point out the present knowledge of the molecular pathogenesis of chronic pancreatitis and pancreatic cancer and will focus on the role of molecular markers for differentiating chronic pancreatitis from pancreatic cancer.     

Chronic Alcohol-Induced Alterations in the Pancreatic Secretory Control Mechanisms

Chronic alcohol ingestion appears to increase susceptibility of the pancreas to pancreatitis through multiple mechanisms. The aim of the current study was to determine the effect of chronic low- and high-dose alcohol consumption on the neurohormonal control of the exocrine pancreas in rats. Male Wistar rats were fed Lieber DeCarli liquid control-, low-, and high-dose alcohol diets for 3 months. Pancreatic exocrine secretion was measured under basal and 2-deoxy-d-glucose (2-DG)-, CCK-, bethanechol-, or meal-stimulated conditions while on chronic alcohol diets and after 2-DG or CCK stimulation during alcohol withdrawal in awake rats. Chronic alcohol ingestion was associated with a dose-related inhibition of basal pancreatic protein secretion, which was reversed upon alcohol withdrawal. Low-dose alcohol feeding had no effect on bethanechol-stimulated pancreatic secretion but altered 2-DG-stimulated pancreatic secretion. In chronic high-dose alcohol rats, meal- and bethanechol-stimulated protein secretion was significantly potentiated during early and late phases. The response to CCK appeared to be disinhibited, whereas the response to 2-DG was uniformly blunted. Upon withdrawal of low-dose alcohol, the response to 2-DG was potentiated, whereas with the withdrawal of high-dose alcohol, the response to CCK was potentiated. Adaptation to chronic alcohol consumption differs depending on the alcohol dose. The most significant effects were seen after high-dose alcohol withdrawal, with apparent loss of central inhibitory regulation combined with exaggerated response at the acinar cell level. This combination of factors could increase susceptibility to acute alcoholic pancreatitis through a hyperstimulation mechanism.     

Helicobacter species ribosomal DNA in the pancreas, stomach and duodenum of pancreatic cancer patients

AIM: To determine whether gastric and enteric Helicobacter species are associated with pancreatic cancer. METHODS: Patients with exocrine pancreatic cancer (n = 40), neuroendocrine cancer (n=14), multiple endocrine neoplasia type 1 {n = 8), and chronic pancreatitis (n = 5) were studied. Other benign pancreatic diseases (n = 10) and specimens of normal pancreas (n=7) were included as controls. Pancreatic tissue specimens were analyzed by He/icobacter-specific PCR-assay and products were characterized by denaturing gradient electrophoresis and DNA-sequencing. From a subset of the pancreatic cancer patients, gastric and/or duodenal tissue as well as gallbladder and ductus choledochus tissue were analyzed. Gallbladder and choledochus samples were included as controls. Stomach and duodenum samples were investigated to analyze whether a gastric helicobacter might disseminate to the pancreas in pancreatic cancer patients. Pancreatic specimens were analyzed by Bacteroides-specific PCR for detecting the translocation of indigenous gut microbes to the diseased pancreas. RESULTS: Helicobacter DNA was detected in pancreas (tumor and/or surrounding tissue) of 75% of patients with exocrine cancer, 57% of patients with neuroendocrine cancer, 38% of patients with multiple endocrine neoplasia, and 60% of patients with chronic pancreatitis. All samples from other benign pancreatic diseases and normal pancreas were negative. Thirty-three percent of the patients were helicobacter-positive in gastroduodenal specimens. Surprisingly, H. bilis was identified in 60% of the positive gastro-duodenal samples. All gallbladder and ductus cho-ledochus specimens were negative for helicobacter. Bacteroides PCR-assay was negative for all pancreatic samples. CONCLUSION: Helicobacter DNA commonly detected in pancreatic cancer suggests a possible role of the emerging pathogens in the development of chronic pancreatitis and pancreatic cancer.     

Alcohol-induced protein kinase Calpha phosphorylation of Munc18c in carbachol-stimulated acini causes basolateral exocytosis

BACKGROUND & AIMS: Acute or chronic alcohol treatment does little to the exocrine pancreas but predisposes the pancreas to postprandial cholinergic stimulation that triggers cellular events leading to pancreatitis. This alcohol-induced susceptibility mechanism of pancreatitis is unknown. METHODS: We employed alcohol-treated dispersed rat pancreatic acini and alcohol diet-fed rats to examine the effects of submaximal carbachol-induced changes in exocytosis (FM1-43 epifluorescence imaging and electron microscopy), Munc18c cellular translocation (confocal microscopy and subcellular fractionation), and protein kinase C (PKC) alpha-induced phosphorylation in relation to pancreatitis. RESULTS: Acute low-dose alcohol (20 mmol/L) in vitro exposure or chronic alcohol diet reduces postprandial cholinergic-stimulated amylase secretion from rat pancreatic acinar cells by blocking apical exocytosis and redirecting exocytosis to less efficient basolateral plasma membrane sites. This ectopic exocytosis is mediated by PKCalpha-induced phosphorylation of Munc18c, causing Munc18c displacement from the basolateral plasma membrane into the cytosol in which it undergoes proteolytic degradation; these processes can be blocked by PKCalpha inhibition. CONCLUSIONS: We conclude that sequential low-dose alcohol and postprandial cholinergic stimulation can induce PKCalpha-mediated Munc18c plasma membrane displacement. This relieves cognate SNARE proteins on zymogen granules and basolateral membrane to complex and consummate pathologic ectopic exocytosis at the basolateral surface. This change in vesicle trafficking may be related to the pathogenesis of pancreatitis.     

Pancreatic cholesterol esterase,ES-10, and fatty acid ethyl ester synthase III gene expression are increased in the pancreas and liver but not in the brain or heart with long-term ethanol feeding in rats

INTRODUCTION: Chronic alcohol consumption predisposes susceptible individuals to both acute and chronic pancreatitis. AIMS: Our hypothesis was that alcohol increases the risk of pancreatitis by disrupting defense mechanisms and/or enhancing injury-associated pathways through altered gene expression. Hence, we studied the expression of pancreatic genes in rats chronically exposed to ethanol. METHODOLOGY: Male Wistar rats were pair-fed liquid diets without and with ethanol for 4 weeks. Total RNA was extracted from rat pancreas and other organs. The mRNA expression patterns among pancreatic samples from ethanol-fed rats and controls were compared with use of mRNA differential display. The differentially expressed cDNA tags were isolated, cloned, and sequenced. RESULTS: One cDNA tag that was overexpressed in the pancreas showed 99% sequence homology to a rat pancreatic cholesterol esterase mRNA (CEL; Enzyme Commission number [EC] 3.1.1.13). The differential expression was confirmed by realtime PCR. Gene expression was also increased in the liver but not in the heart or brain of the alcohol-fed rats. Because CEL has fatty acid ethyl ester (FAEE)-generating activity and FAEEs play a major role in acute alcoholic pancreatitis, we determined the expression of other genes encoding for FAEE-generating enzymes and showed similar organ-specific expression patterns. CONCLUSION: Our results demonstrate that chronic ethanol consumption induced expression of FAEE-related genes in the pancreas and liver. This upregulation may be a central mechanism leading to acinar cell injury.     

Overexpression of pancreatitis-associated protein (PAP) in human pancreatic ductal adenocarcinoma

Pancreatitis-associated protein (PAP) is almost absent in normal pancreas, but is strongly induced in acute pancreatitis. PAP mRNA is also expressed in cancer cells, including pancreatic ductal adenocarcinoma. However, the clinicopathological significance of PAP in human pancreatic cancer is not clear. We examined PAP expression in pancreatic tissues from individuals with pancreatic ductal adenocarcinoma using immunohistochemistry. PAP was overexpressed in 79% (30 of 38) of pancreatic ductal adenocarcinoma, 19% (7 of 36) of chronic pancreatitis, and 29% (2 of 7) of mucinous cystadenoma. PAP was found in malignant ductular structures in pancreatic carcinomas as well as in benign proliferating ductules and acinar cells in chronic pancreatitis. It was not expressed in normal pancreas. The incidence of PAP overexpression was significantly higher in pancreatic cancer than in the other pancreatic diseases (P < 0.01). PAP overexpression was significantly correlated with nodal involvement, distant metastasis (P < 0.05), and short survival (P < 0.01) in pancreatic cancer. These results suggest that overexpression of PAP in human pancreatic ductal adenocarcinoma indicates tumor aggressiveness.     

Diabetes

Pancreatologists have often divided research of the pancreas based upon the origin of the function or disease, namely the endocrine or exocrine pancreas. In fact, as a result, many of our meetings and conferences have followed separate paths. Interestingly, among patients with chronic pancreatitis and pancreatic cancer, both disorders of the exocrine pancreas, diabetes is common. However, the clinical features of the diabetes associated with these two differ. Peripheral insulin resistance and hyperinsulinemia are the predominant diabetic traits in pancreatic cancer, while reduced islet cell mass and impaired insulin secretion are observed more often in chronic pancreatitis. The causal relationship between diabetes and pancreatic cancer remains an intriguing but unanswered question. Since diabetes often precedes pancreatic cancer, it is regarded as a potential risk factor for malignancy. On the other hand, there remains the possibility that pancreatic cancer secretes diabetogenic factors. Regardless of how the science ultimately illuminates this issue, there is increasing interest in utilizing screening for diabetes to aid early detection of pancreatic tumor lesions. Therefore, in this issue of Pancreatology and the Web, we explore the topic of diabetes to keep us alert to this very important association, even if we study diseases of the exocrine pancreas.     

Expression of major histocompatibility antigens in human chronic pancreatitis.

T-lymphocytic infiltration of the exocrine pancreas and liver in patients with chronic pancreatitis has suggested that cell mediated immune mechanisms may play a part in the pathogenesis of this disease. As expression of major histocompatibility (MHC) antigens is a prerequisite for organ specific autoimmunity, the expression of HLA class I (beta 2-microglobulin) and class II (HLA-DR) determinants have been analysed, together with the presence of T-lymphocytes, in 93 patients (64 men and 29 women, mean age 40.6 years) having an operation for chronic pancreatitis. Ethanol (63 patients), recurrent acute pancreatitis (12), congenital lesions (2), and unknown (16) were suggested to be the causes of the disease. Immunohistochemical staining of formalin fixed and paraffin wax embedded tissue sections used conventional immunohistochemical techniques with specific anti-serum samples. No MHC expression was identified in 10 histologically normal pancreatic control specimens or in four cases of chronic pancreatitis secondary to obstruction by neuroendocrine tumours within the head of the pancreas. beta 2-microglobulin expression by pancreatic exocrine epithelial cells was seen in 76 chronic pancreatitis specimens (82%) while HLA-DR was present in 61 (66%). Simultaneous expression of both class I and II determinants was seen in 53 (57%) of cases. MHC determinant expression was not found in 10 cases (11%) of chronic pancreatitis. In the positive specimens, expression was confined to ductal and ductular (interlobular and intralobular) epithelium with no staining of acinar cells. Staining was not related to the suspected cause of the disease or age. T-lymphocytes were more prominent in chronic pancreatitis mean (SEM) (131 (15) cells per high powered field) than controls (5 (1), p < 0.01). Aberrant MHC expression by exocrine pancreatic epithelial cells occurring in the presence of an appreciable T-cell infiltration confirmed that the appropriate cellular conditions were present for cell mediated cytotoxicity to contribute to the pathogenesis of chronic pancreatitis.