BACKGROUND & AIMS Excessive consumption of ethanol is one of the most common causes of acute and chronic pancreatitis. Alterations to the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) also cause pancreatitis. However, little is known about the role of CFTR in the pathogenesis of alcohol-induced pancreatitis. METHODS We measured CFTR activity based on chloride concentrations in sweat from patients with cystic fibrosis, patients admitted to the emergency department because of excessive alcohol consumption, and healthy volunteers. We measured CFTR levels and localization in pancreatic tissues and in patients with acute or chronic pancreatitis induced by alcohol. We studied the effects of ethanol, fatty acids, and fatty acid ethyl esters on secretion of pancreatic fluid and HCO3− , levels and function of CFTR, and exchange of Cl− for HCO3− in pancreatic cell lines as well as in tissues from guinea pigs and CFTR knockout mice after administration of alcohol. RESULTS Chloride concentrations increased in sweat samples from patients who acutely abused alcohol but not in samples from healthy volunteers, indicating that alcohol affects CFTR function. Pancreatic tissues from patients with acute or chronic pancreatitis had lower levels of CFTR than tissues from healthy volunteers. Alcohol and fatty acids inhibited secretion of fluid and HCO3− , as well as CFTR activity, in pancreatic ductal epithelial cells. These effects were mediated by sustained increases in concentrations of intracellular calcium and adenosine 3’,5’-cyclic monophosphate, depletion of adenosine triphosphate, and depolarization of mitochondrial membranes. In pancreatic cell lines and pancreatic tissues of mice and guinea pigs, administration of ethanol reduced expression of CFTR messenger RNA, reduced the stability of CFTR at the cell surface, and disrupted folding of CFTR at the endoplasmic reticulum. CFTR knockout mice given ethanol or fatty acids developed more severe pancreatitis than mice not given ethanol or fatty acids. CONCLUSIONS Based on studies of human, mouse, and guinea pig pancreata, alcohol disrupts expression and localization of the CFTR. This appears to contribute to development of pancreatitis. Strategies to increase CFTR levels or function might be used to treat alcohol-associated pancreatitis.

(1,25-D 3 ), is inhibition of cell growth and induction of cell differentiation and/or apoptosis. Synthesis and degradation of the secosteroid occurs not only in the kidney but also in normal tissue or malignant extrarenal tissues such as the colon. Because 25-hydroxyvitamin D 3 24-hydroxylase (CYP24A1) is considered to be the main enzyme determining the biological half-life of 1,25-D 3 , we have examined expression of the CYP24A1 mRNA (by real-time RT-PCR) and protein (by immunohistochemistry) in normal human colon mucosa, colorectal adenomas, and adenocarcinomas in 111 patients. Although 76% of the normal and benign colonic tissue was either completely devoid of or expressed very low levels of CYP24A1, in the majority of the adenocarcinomas (69%), the enzyme was present at high concentrations. A parallel increased expression of the proliferation marker Ki-67 in the same samples suggests that overexpression of CYP24A1 reduced local 1,25-D 3 availability, decreasing its antiproliferative effect. (J Histochem Cytochem 58:277-285, 2010) COLORECTAL CANCER (CRC) is the second leading cause of malignant mortality in Western industrialized countries (Boyle and Ferlay 2005). Geographical distribution of cancer mortality in the US correlates with exposure to solar (ultraviolet B) radiation; the highest mortality rates for CRC were observed in regions with less solar radiation (Freedman et al. 2002). Furthermore, epidemiological data have shown an inverse association of serum 25-hydroxyvitamin D 3 (25-D 3 ) levels with risk for prostate, breast, and colorectal malignancies (Garland et al. 1989;Ahonen et al. 2000;Bertone-Johnson et al. 2005). Estimating premature cancer mortality in the US, Grant and Garland (2006) implied that actually 20-30% of CRC cases could be avoided by sufficient exposure to sunlight.A recent meta-analysis of 18 cohort and case-control studies showed that an elevation of serum 25-D 3 concentration to levels $33 ng/ml led to a 50% lower incidence of CRC (Gorham et al. 2005). Cumulative epidemiological evidence suggests that there is a direct correlation between reduced CRC incidence and sunlight exposure, nutritional vitamin D intake, and high serum levels of 25-D 3 (Giovannucci et al. 2006).Vitamin D metabolism is a strictly regulated, multistep process, beginning with the formation of previtamin D 3 in the skin, mediated by ultraviolet radiation, or with absorption of vitamin D from dietary sources (Henry 1997;Sawada et al. 2000;Cheng et al. 2003). Vitamin D is hydroxylated by CYP27A1 to 25-hydroxyvitamin D 3 in the liver. The last step of the activation is accomplished by the 25-hydroxyvitamin D 3 1a hydroxylase (CYP27B1) in the kidney. The most active metabolite of vitamin D 3, 1a,25-dyhydroxyvitamin D 3 (1,25-D 3 , also known as calcitriol), has a crucial Correspondence to: Enikö Kállay,

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Background & Aims The effects of trypsin on pancreatic ductal epithelial cells (PDEC) vary among species and depend on localization of proteinase-activated receptor-2 (PAR-2). Bicarbonate secretion is similar in human and guinea pig PDEC; we compared its localization in these cell types and isolated guinea pig ducts to study the effects of trypsin and a PAR-2 agonist on this process. Methods PAR-2 localization was analyzed by immunohistochemistry in guinea pig and human pancreatic tissue samples (from 15 patients with chronic pancreatitis and 15 without pancreatic disease). Functions of guinea pig PDEC were studied by microperfusion of isolated ducts, measurements of intracellular pH (pHi) and Ca2+ concentration [Ca2+]i, and patch clamp analysis. The effect of pH on trypsinogen autoactivation was assessed using recombinant human cationic trypsinogen. Results PAR-2 localized to the apical membrane of human and guinea pig PDEC. Trypsin increased [Ca2+]i and pHi, and inhibited secretion of bicarbonate by the luminal anion exchanger and the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. Autoactivation of human cationic trypsinogen accelerated when the pH was reduced from 8.5 to 6.0. PAR-2 expression was strongly down-regulated, at transcriptional and protein levels, in the ducts of patients with chronic pancreatitis, consistent with increased activity of intraductal trypsin. Importantly, in PAR-2 knockout mice, the effects of trypsin were PAR-2 dependent. Conclusions Trypsin reduces pancreatic ductal bicarbonate secretion via PAR-2–dependent inhibition of the apical anion exchanger and the CFTR Cl- channel. This could contribute to the development of chronic pancreatitis, decreasing luminal pH and promoting premature activation of trypsinogen in the pancreatic ducts.

Altered expression of recently described claudins (CLDNs) as members of tight junction (TJ) transmembrane proteins was noted in several malignancies. We aimed to analyze protein and messenger RNA (mRNA) expressions of different CLDNs in human pancreatic endocrine tumors (PET) and ductal adenocarcinomas. A total of 45 formalin-fixed, paraffin-embedded samples were studied. Immunohistochemistry and real-time reverse transcriptase polymerase chain reaction analysis were carried out for quantification of CLDN 1, -2, -3, -4, and -7 expressions. Normal acini and ducts showed strong CLDNs 1, -3, -4, and -7 and scattered CLDN 2 protein expressions, while Langerhans islands revealed only CLDN 3 and -7 expressions. CLDN 2 expression was found in the half of ductal adenocarcinomas, while the vast majority of endocrine tumors were negative. CLDN 1, -4, and -7 immunohistochemistry was positive in all adenocarcinomas, whereas endocrine tumors were completely negative for CLDNs 1 and -4. CLDN 3 and -7 proteins were detected in all endocrine tumors, while CLDN 3 in ductal adenocarcinomas was negative. The mRNA expression of CLDNs showed differences between endocrine tumors and ductal adenocarcinomas, similar as found for protein expression. Our findings support that PET and ductal carcinomas are specifically characterized by different expression pattern of CLDNs. High expressions of CLDN 3 in endocrine tumors and CLDN 4 in ductal carcinomas might attract them as targets for adjuvant therapy.

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This is the first report to describe the tricellulin expression profile in normal and neoplastic human pancreas. Both normal and neoplastic pancreatic exocrine tissues expressed tricellulin, whereas no expression was seen in normal or neoplastic endocrine cells. Tricellulin expression in pancreatic ductal adenocarcinomas showed a significant negative correlation with the degree of differentiation.

Aquaporins (AQPs) facilitate the transepithelial water flow involved in epithelial fluid secretion in numerous tissues; however, their function in the pancreas is less characterized. Acute pancreatitis (AP) is a serious disorder in which specific treatment is still not possible. Accumulating evidence indicate that decreased pancreatic ductal fluid secretion plays an essential role in AP; therefore, the aim of this study was to investigate the physiological and pathophysiological role of AQPs in the pancreas. Expression and localization of AQPs were investigated by real-time PCR and immunocytochemistry, whereas osmotic transmembrane water permeability was estimated by the dye dilution technique, in Capan-1 cells. The presence of AQP1 and CFTR in the mice and human pancreas were investigated by immunohistochemistry. Pancreatic ductal HCO3- and fluid secretion were studied on pancreatic ducts isolated from wild-type (WT) and AQP1 knock out (KO) mice using microfluorometry and videomicroscopy, respectively. In vivo pancreatic fluid secretion was estimated by magnetic resonance imaging. AP was induced by intraperitoneal injection of cerulein and disease severity was assessed by measuring biochemical and histological parameters. In the mice, the presence of AQP1 was detected throughout the whole plasma membrane of the ductal cells and its expression highly depends on the presence of CFTR Cl- channel. In contrast, the expression of AQP1 is mainly localized to the apical membrane of ductal cells in the human pancreas. Bile acid treatment dose- and time-dependently decreased mRNA and protein expression of AQP1 and reduced expression of this channel was also demonstrated in patients suffering from acute and chronic pancreatitis. HCO3- and fluid secretion significantly decreased in AQP1 KO versus WT mice and the absence of AQP1 also worsened the severity of pancreatitis. Our results suggest that AQP1 plays an essential role in pancreatic ductal fluid and HCO3- secretion and decreased expression of the channel alters fluid secretion which probably contribute to increased susceptibility of the pancreas to inflammation.