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John P Neoptolemos

Publications and source records attributed to John P Neoptolemos.

At least 19 recordsLinked to original sources
PubMed2006

The inherited genetics of pancreatic cancer and prospects for secondary screening.

It is estimated that pancreatic cancer has a familial component in approximately 5-10% of cases. Some of these cases are part of a defined cancer syndrome with a known gene mutation but in the remaining the causative gene remains unknown. In recent years, a better understanding of the molecular events that occur in the progression model of pancreatic cancer has lead to the development of secondary screening programmes with the aim of identifying early precursor lesions or pre-invasive cancer at a stage amenable to curative resection. High-risk groups who have an inherited predisposition for pancreatic cancer form the ideal group to study in developing a robust screening programme. Multimodality screening using computed tomography and endoluminal ultrasound in combination with molecular analysis of pancreatic juice are proving promising as diagnostics tools or at least serving as predictors of risk over a defined period.

Biomarkers, Tumor↗
PubMed2006

Trypsinogen mutations in pancreatic disorders.

There are multiple PRSS1 mutations described in hereditary pancreatitis but only a minority of these are clinically relevant. The two most frequent point mutations are in exon 2 (N29I) and exon3 (R122H), found in diverse racial populations. Both mutations result in early onset pancreatitis but the mechanism underlying this phenotype is unclear. The frequency of these mutations in such diverse populations suggests they have spontaneously occurred many times. The origin of the major mutations may be explained by gene conversions, accounting for multiple founders. The implications are discussed in terms of mechanism of action of the mutations and clinical presentation.

Gene Conversion↗
PubMed2006

Fatty acid ethyl esters cause pancreatic calcium toxicity via inositol trisphosphate receptors and loss of ATP synthesis.

BACKGROUND & AIMS: Fatty acid ethyl esters are ethanol metabolites inducing sustained, toxic elevations of the acinar cytosolic free calcium ion concentration ([Ca(2+)](C)) implicated in pancreatitis. We sought to define the mechanisms of this elevation. METHODS: Isolated mouse pancreatic acinar cells were loaded with fluorescent dyes for confocal microscopy to measure [Ca(2+)](C) (Fluo 4, Fura Red), endoplasmic reticulum calcium ion concentration ([Ca(2+)](ER), Mg Fluo 4), mitochondrial membrane potential (TMRM), ADP:ATP ratio (Mg Green), and NADH autofluorescence in response to palmitoleic acid ethyl ester and palmitoleic acid (10-100 micromol/L). Whole-cell patch clamp was used to measure the calcium-activated chloride current and apply ethanol metabolites and/or ATP intracellularly. RESULTS: Intracellular delivery of ester induced oscillatory increases of [Ca(2+)](C) and calcium-activated currents, inhibited acutely by caffeine (20 mmol/L), but not atropine, indicating involvement of inositol trisphosphate receptor channels. The stronger effect of extracellular ester or acid caused depletion of [Ca(2+)](ER), not prevented by caffeine, but associated with depleted ATP, depleted NADH autofluorescence, and depolarized mitochondria, suggesting calcium-ATPase pump failure because of lack of ATP. Intracellular ATP abolished the sustained rise in [Ca(2+)](C), although oscillatory signals persisted that were prevented by caffeine. Inhibition of ester hydrolysis markedly reduced its calcium-releasing effect and consequent toxicity. CONCLUSIONS: Fatty acid ethyl ester increases [Ca(2+)](C) through inositol trisphosphate receptors and, following hydrolysis, through calcium-ATPase pump failure from impaired mitochondrial ATP production. Lowering cellular fatty acid substrate concentrations may reduce cell injury in pancreatitis.

Adenosine Triphosphate↗
PubMed2006

Evaluation of the 4q32-34 locus in European familial pancreatic cancer.

BACKGROUND: Familial pancreatic cancer (FPC) describes a group of families where the inheritance of pancreatic cancer is consistent with an autosomal-dominant mode of inheritance. The 4q32-34 region has been previously identified as a potential locus for FPC in a large American family. METHODS: The region was allelotyped in 231 individuals from 77 European families using nine microsatellite markers, and haplotyping was possible in 191 individuals from 41 families. Families were selected based on at least two affected first-degree relatives with no other cancer syndromes. RESULTS: Linkage to most of the locus was excluded based on LOD scores less than -2.0. Eight families were excluded from linkage to 4q32-34 based on haplotypes not segregating with the disease compared with a predicted six to seven families. Two groups of families were identified, which seem to share common alleles within the minimal disease-associated region of 4q32-34, one group with an apparently earlier age of cancer death than the other pancreatic cancer families. Four genes were identified with potential tumor suppressor roles within the locus in regions that could not be excluded based on the LOD score. These were HMGB2, PPID, MORF4, and SPOCK3. DNA sequence analysis of exons of these genes in affected individuals and in pancreatic cancer cell lines did not reveal any mutations. CONCLUSION: This locus is unlikely to harbor a FPC gene in the majority of our European families.

Adenocarcinoma↗
PubMed2006

Capecitabine in carcinoma of the pancreas.

Capecitabine is an oral prodrug of 5-fluorouracil, which is converted to 5-fluorouracil by three sequential enzymatic reactions. The final requisite enzyme, thymidine phosphorylase, is present at consistently higher levels in tumours compared with normal tissues, thereby suggesting that 5-fluorouracil that is delivered in this way may benefit from an element of tumour targeting and thus enhanced selectivity and better tolerability. Capecitabine has been shown to have single-agent activity in advanced carcinoma of the pancreas and to improve response rates and survival when administered in combination with gemcitabine compared with gemcitabine alone. This paper reviews the pharmacology and clinical data that are relevant to the use of capecitabine in pancreatic cancer.

Adenocarcinoma↗
PubMed2005

RNASEL germline variants are associated with pancreatic cancer.

The RNASEL (encoding ribonuclease L) gene Glu265X mutation has been implicated in familial prostate cancer, and an association between the RNASEL Arg462Gln variant and sporadic and familial prostate cancer, has also been suggested. Because prostate cancer occurs in some familial pancreatic cancer families, we evaluated the role of the RNASEL gene variants Glu265X and Arg462Gln in the etiology of pancreatic cancer. Exon 2 of the RNASEL gene was directly sequenced in the germline of 36 familial and 75 sporadic pancreatic cancer patients and in 108 controls. The Glu265X mutation was identified in one (2.8%) familial and one (1.3%) sporadic pancreatic cancer case, but not in any of the controls. Arg462Gln variants were identified in 61 (56%) controls and in 55 (73%) sporadic pancreatic cancer cases with 8 (7%) and 12 (16%) homozygotes, respectively (p = 0.009). For homozygous carriers the increased risk for pancreatic cancer was 3.5 (odds ratio [OR] = 3.53, 95% confidence interval [CI] = 1.11-11.46, p = 0.03). The population attributable fraction (PAF) was 38.7% (95% CI = 0.08-0.80). In familial pancreatic cancer no association between Arg462Gln genotypes and pancreatic cancer risk was evident. In sporadic pancreatic cancer there were no significant differences between Arg462Gln genotypes regarding clinical characteristics. In familial pancreatic cancer, however, patients with Arg462Gln variants had more aggressive tumors with more high grade cancers (OR = 15.40, p = 0.009) and more distant metastases (OR = 7.00, p = 0.04) than patients with the wild-type genotype. Our results suggest that RNASEL variants Glu265X and Arg462Gln may contribute to the tumorigenesis of sporadic and familial pancreatic cancer, which has to be proven in large scale studies.

Adult↗
PubMed2005

Increased risk of idiopathic chronic pancreatitis in cystic fibrosis carriers.

Cystic fibrosis (CF) is a recessive disease caused by mutations of the CF transmembrane conductance regulator (CFTR) gene. The risk of idiopathic chronic pancreatitis (ICP) is increased in individuals who have CFTR genotypes containing a CF-causing mutation plus a second pathogenic allele. It is unknown whether the risk of ICP is increased in CF carriers who have one CF-causing mutation plus one normal allele. In this study, 52 sporadic cases of ICP were ascertained through the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer. Individuals with pathogenic cationic trypsinogen mutations were excluded. DNA was comprehensively tested for CFTR mutations using a robotically enhanced, multiplexed, and highly redundant form of single-strand conformation polymorphism (SSCP) analysis followed by DNA sequencing. Fifteen subjects had a total of 18 pathogenic CFTR alleles. Eight subjects had common CF-causing mutations. This group included seven CF carriers in whom the second CFTR allele was normal (4.3 times the expected frequency, P=0.0002). Three subjects had compound heterozygotes genotypes containing two pathogenic alleles (31 times the expected frequency, P<0.0001). A variant allele of uncertain significance (p.R75Q) was detected in eight of the 52 ICP subjects and at a similar frequency (13/96) in random donors. ICP differs from other established CFTR-related conditions in that ICP risk is increased in CF carriers who have one documented normal CFTR allele. Having two CFTR mutations imparts a higher relative risk, while having only one mutation imparts a higher attributable risk.

Adult↗
PubMed2005

Cationic trypsinogen mutations and pancreatitis.

The discovery of PRSS 1 mutations in hereditary pancreatitis and analysis of how the genotype affects the presentation and progression of hereditary pancreatitis has led to a better understanding of the pathophysiology of the disease. Patients with hereditary pancreatitis present with symptoms at an early age and have a significant lifetime risk for the development of endocrine and exocrine insufficiency, albeit at a later stage than patients with either idiopathic or alcoholic chronic pancreatitis. There are distinct phenotypic differences between hereditary pancreatitis and with other types of pancreatitis. As many as 80% of patients with symptomatic hereditary pancreatitis have an underlying causative PRSS1 mutation; there are, however, few significant phenotypic differences between these PRSS1 mutations. TheR122H mutation is the most common PRSS1 mutation observed, and patients with the R122H mutation present earlier. This, however, does not necessarily translate into a more aggressive disease with respect to complications of chronic pancreatitis. Indeed, the age of presentation of symptoms may be a poor surrogate for predicting outcome, as inherited disorders of trypsinogen may cause subclinical attacks of pancreatitis, which ultimately lead to pancreatic destruction and dysfunction. All patients, irrespective of whether they carry a PRSS1 mutation, are at significant risk of developing pancreatic ductal adenocarcinoma. The risk appears to be insignificant below the age of 40 years, but it increases incrementally thereafter. Significantly, the risk of pancreatic cancer is not related to PRSS1 mutation type and does not appear to be related to the mode of inheritance. The role of SPINK1 mutations in modifying the expression of PRSS1mutations is unclear but appears to be of clinical importance. It is unlikely that they act as causative mutations per se, at least in the Western form of the disease. Additionally, they do not appear to have an impact on the penetrance of PRSS1 gene mutations in hereditary pancreatitis.

Chronic Disease↗
PubMed2004

Analysis of gene expression in cancer cell lines identifies candidate markers for pancreatic tumorigenesis and metastasis.

Pancreatic cancer is a highly aggressive type of malignancy and the prognosis for disease presenting typically at a late stage is extremely poor. A comprehensive understanding of its molecular genetics is required in order to develop new approaches to clinical management. To date, serial analysis of gene expression and more recently oligo/cDNA microarray technologies have been employed in order to identify genes involved in pancreatic neoplasia that can be developed as diagnostic markers and drug targets for this dismal disease. This study describes the expression profile obtained from 20 pancreatic cell lines using cDNA microarrays containing 9,932 human gene elements. Numerous genes were identified as being differentially expressed, some of which have been previously implicated in pancreatic adenocarcinoma (S100P, S100A4, prostate stem cell antigen, lipocalin 2, claudins 3 and 4, trefoil factors 1 and 2) as well as several novel genes. The differentially expressed genes identified are involved in a variety of cellular functions, including control of transcription, regulation of the cell cycle, proteolysis, cell adhesion and signaling. Validation of our array results was performed by exploring the SAGEmap database and by immunohistochemistry for a selection of 4 genes that have not previously been studied in pancreatic cancer: anterior gradient 2 homologue (Xenopus laevis), insulin-like growth factor binding protein 3 and 4 and Forkhead box J1. Immunostaining was performed using pancreas-specific tissue microarrays containing core biopsies from 305 clinical specimens. In addition, using statistical group comparison and hierarchical clustering, a selection of genes was identified that may be linked to the site of metastasis from which these cell lines were isolated.

Biomarkers, Tumor↗
PubMed2004

No evidence for germline mutations of the LKB1/STK11 gene in familial pancreatic carcinoma.

Familial pancreatic cancer (FPC) (approximately 3% of all cases) has not been linked to defects in any specific gene. Germline inactivation of the gene LKB1/STK11 have been shown to cause Peutz-Jeghers syndrome (PJS) associated with a approximately 100-fold higher risk for the development of pancreatic cancer. We have analysed 39 index patients from European FPC families for mutations of LKB1/STK11 by sequencing of their DNA. No germline mutation was found within the complete coding region. Therefore, our results indicate that LKB1/STK11 is not altered in the germline of patients with hereditary pancreatic cancer.

AMP-Activated Protein Kinase Kinases↗
PubMed2004

Ethanol toxicity in pancreatic acinar cells: mediation by nonoxidative fatty acid metabolites.

Ethanol causes pancreatic damage by an unknown mechanism. Previously, we demonstrated that a sustained rise of the cytosolic Ca(2+) concentration ([Ca(2+)](i)) causes pancreatic acinar cell injury. Here we have investigated the effects of ethanol and its metabolites on Ca(2+) signaling in pancreatic acinar cells. Most cells exposed to ethanol (up to 850 mM) showed little or no increase in [Ca(2+)](i) (and never at concentrations <50 mM). During sustained exposure to 850 mM ethanol, acetylcholine (ACh) evoked a normal [Ca(2+)](i) elevation and following ACh removal there was a normal and rapid recovery to a low resting level. The oxidative metabolite acetaldehyde (up to 5 mM) had no effect, whereas the nonoxidative unsaturated metabolite palmitoleic acid ethyl ester (10-100 microM, added on top of 850 mM ethanol) induced sustained, concentration-dependent increases in [Ca(2+)](i) that were acutely dependent on external Ca(2+) and caused cell death. These actions were shared by the unsaturated metabolite arachidonic acid ethyl ester, the saturated equivalents palmitic and arachidic acid ethyl esters, and the fatty acid palmitoleic acid. In the absence of external Ca(2+), releasing all Ca(2+) from the endoplasmic reticulum by ACh (10 microM) or the specific Ca(2+) pump inhibitor thapsigargin (2 microM) prevented such Ca(2+) signal generation. We conclude that nonoxidative fatty acid metabolites, rather than ethanol itself, are responsible for the marked elevations of [Ca(2+)](i) that mediate toxicity in the pancreatic acinar cell and that these compounds act primarily by releasing Ca(2+) from the endoplasmic reticulum.

Acetylcholine↗