Common single-base insertions in the VNTR of the carboxyl ester lipase (CEL) gene are benign and also likely to arise somatically in the exocrine pancreas

The CEL gene encodes carboxyl ester lipase, a pancreatic digestive enzyme. CEL is extremely polymorphic due to a variable number tandem repeat (VNTR) located in the last exon. Single-base deletions within this VNTR cause the inherited disorder MODY8, whereas little is known about VNTR single-base insertions in pancreatic disease. We therefore mapped CEL insertion variants (CEL-INS) in 200 Norwegian patients with pancreatic neoplastic disorders. Twenty-eight samples (14.0%) carried CEL-INS alleles. Most common were insertions in repeat 9 (9.5%), which always associated with a VNTR length of 13 repeats. The combined INS allele frequency (0.078) was similar to that observed in a control material of 416 subjects (0.075). We performed functional testing in HEK293T cells of a set of CEL-INS variants, in which the insertion site varied from the first to the 12th VNTR repeat. Lipase activity showed little difference among the variants. However, CEL-INS variants with insertions occurring in the most proximal repeats led to protein aggregation and endoplasmic reticulum stress, which upregulated the unfolded protein response. Moreover, by using a CEL-INS-specific antibody, we observed patchy signals in pancreatic tissue from humans without any CEL-INS variant in the germline. Similar pancreatic staining was seen in knock-in mice expressing the most common human CEL VNTR with 16 repeats. CEL-INS proteins may therefore be constantly produced from somatic events in the normal pancreatic parenchyma. This observation along with the high population frequency of CEL-INS alleles strongly suggests that these variants are benign, with a possible exception for insertions in VNTR repeats 1-4.

Congenital hyperinsulinism

This clinical review will give doctors who work with children and neonates an introduction to the diagnosis and treatment of congenital hyperinsulinism, the most common cause of persistent neonatal hypoglycaemia. The condition is a rare monogenic disorder characterised by elevated insulin secretion and is a result of mutations in genes that regulate insulin secretion from pancreatic beta cells. The anabolic effect of insulin induces systemic glucose uptake and inhibits gluconeogenesis, glycogenolysis, ketogenesis and lipolysis. Low levels of glucose and ketone bodies in the blood are harmful to the central nervous system and can lead to brain damage or death. Early diagnosis and treatment of congenital hyperinsulinism are therefore crucial for a good prognosis.

Characterisation of HNF1A variants in paediatric diabetes in Norway using functional and clinical investigations to unmask phenotype and monogenic diabetes

AIMS/HYPOTHESIS

Correctly diagnosing MODY is important, as individuals with this diagnosis can discontinue insulin injections; however, many people are misdiagnosed. We aimed to develop a robust approach for determining the pathogenicity of variants of uncertain significance in hepatocyte nuclear factor-1 alpha (HNF1A)-MODY and to obtain an accurate estimate of the prevalence of HNF1A-MODY in paediatric cases of diabetes.

METHODS

We extended our previous screening of the Norwegian Childhood Diabetes Registry by 830 additional samples and comprehensively genotyped HNF1A variants in autoantibody-negative participants using next-generation sequencing. Carriers of pathogenic variants were treated by local healthcare providers, and participants with novel likely pathogenic variants and variants of uncertain significance were enrolled in an investigator-initiated, non-randomised, open-label pilot study (ClinicalTrials.gov registration no. NCT04239586). To identify variants associated with HNF1A-MODY, we functionally characterised their pathogenicity and assessed the carriers' phenotype and treatment response to sulfonylurea.

RESULTS

In total, 615 autoantibody-negative participants among 4712 cases of paediatric diabetes underwent genetic sequencing, revealing 19 with HNF1A variants. We identified nine carriers with novel variants classified as variants of uncertain significance or likely to be pathogenic, while the remaining ten participants carried five pathogenic variants previously reported. Of the nine carriers with novel variants, six responded favourably to sulfonylurea. Functional investigations revealed their variants to be dysfunctional and demonstrated a correlation with the resulting phenotype, providing evidence for reclassifying these variants as pathogenic.

CONCLUSIONS/INTERPRETATION

Based on this robust classification, we estimate that the prevalence of HNF1A-MODY is 0.3% in paediatric diabetes. Clinical phenotyping is challenging and functional investigations provide a strong complementary line of evidence. We demonstrate here that combining clinical phenotyping with functional protein studies provides a powerful tool to obtain a precise diagnosis of HNF1A-MODY.

Deficiency of the metabolic enzyme SCHAD in pancreatic β-cells promotes amino acid-sensitive hypoglycemia

Congenital hyperinsulinism of infancy (CHI) can be caused by a deficiency of the ubiquitously expressed enzyme short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD). To test the hypothesis that SCHAD-CHI arises from a specific defect in pancreatic β-cells, we created genetically engineered β-cell-specific (β-SKO) or hepatocyte-specific (L-SKO) SCHAD knockout mice. While L-SKO mice were normoglycemic, plasma glucose in β-SKO animals was significantly reduced in the random-fed state, after overnight fasting, and following refeeding. The hypoglycemic phenotype was exacerbated when the mice were fed a diet enriched in leucine, glutamine, and alanine. Intraperitoneal injection of these three amino acids led to a rapid elevation in insulin levels in β-SKO mice compared to controls. Consistently, treating isolated β-SKO islets with the amino acid mixture potently enhanced insulin secretion compared to controls in a low-glucose environment. RNA sequencing of β-SKO islets revealed reduced transcription of β-cell identity genes and upregulation of genes involved in oxidative phosphorylation, protein metabolism, and Ca2+ handling. The β-SKO mouse offers a useful model to interrogate the intra-islet heterogeneity of amino acid sensing given the very variable expression levels of SCHAD within different hormonal cells, with high levels in β- and δ-cells and virtually absent α-cell expression. We conclude that the lack of SCHAD protein in β-cells results in a hypoglycemic phenotype characterized by increased sensitivity to amino acid-stimulated insulin secretion and loss of β-cell identity.

The genetic risk factor CEL-HYB1 causes proteotoxicity and chronic pancreatitis in mice

BACKGROUND & AIMS

The CEL gene encodes the digestive enzyme carboxyl ester lipase. CEL-HYB1, a hybrid allele of CEL and its adjacent pseudogene CELP, is a genetic variant suggested to increase the risk of chronic pancreatitis (CP). Our aim was to develop a mouse model for CEL-HYB1 that enables studies of pancreatic disease mechanisms.

METHODS

We established a knock-in mouse strain where the variable number of tandem repeat (VNTR) region of the endogenous mouse Cel gene was substituted with the mutated VNTR of the human CEL-HYB1 allele. Heterozygous and homozygous Cel-HYB1 mice and littermate wildtype controls were characterized with respect to pancreatic pathology and function.

RESULTS

We successfully constructed a mouse model with pancreatic expression of a humanized CEL-HYB1 protein. The Cel-HYB1 mice spontaneously developed features of CP including inflammation, acinar atrophy and fatty replacement, and the phenotype became more pronounced as the animals aged. Moreover, Cel-HYB1 mice were normoglycemic at age 6 months, whereas at 12 months they exhibited impaired glucose tolerance. Immunostaining of pancreatic tissue indicated the formation of CEL protein aggregates, and electron microscopy showed dilated endoplasmic reticulum. Upregulation of the stress marker BiP/GRP78 was seen in pancreatic parenchyma obtained both from Cel-HYB1 animals and from a human CEL-HYB1 carrier.

CONCLUSIONS

We have developed a new mouse model for CP that confirms the pathogenicity of the human CEL-HYB1 variant. Our findings place CEL-HYB1 in the group of genes that increase CP risk through protein misfolding-dependent pathways.

Novel hybridization- and tag-based error-corrected method for sensitive ctDNA mutation detection using ion semiconductor sequencing

Circulating tumor DNA (ctDNA) analysis has emerged as a clinically useful tool for cancer diagnostics and treatment monitoring. However, ctDNA detection is complicated by low DNA concentrations and technical challenges. Here we describe our newly developed sensitive method for ctDNA detection on the Ion Torrent sequencing platform, which we call HYbridization- and Tag-based Error-Corrected sequencing (HYTEC-seq). This method combines hybridization-based capture with molecular tags, and the novel variant caller PlasmaMutationDetector2 to eliminate background errors. We describe the validation of HYTEC-seq using control samples with known mutations, demonstrating an analytical sensitivity down to 0.1% at > 99.99% specificity. Furthermore, to demonstrate the utility of this method in a clinical setting, we analyzed plasma samples from 44 patients with advanced pancreatic cancer, revealing mutations in 57% of the patients at allele frequencies as low as 0.23%.

Two New Mutations in the CEL Gene Causing Diabetes and Hereditary Pancreatitis: How to Correctly Identify MODY8 Cases

CONTEXT

Maturity onset diabetes of the young, type 8 (MODY8) is associated with mutations in the CEL gene, which encodes the digestive enzyme carboxyl ester lipase. Several diabetes cases and families have in recent years been attributed to mutations in CEL without any functional or clinical evidence provided.

OBJECTIVE

To facilitate correct MODY8 diagnostics, we screened 2 cohorts of diabetes patients and delineated the phenotype.

METHODS

Young, lean Swedish and Finnish patients with a diagnosis of type 2 diabetes (352 cases, 406 controls) were screened for mutations in the CEL gene. We also screened 58 Czech MODY cases who had tested negative for common MODY genes. For CEL mutation-positive subjects, family history was recorded, and clinical investigations and pancreatic imaging performed.

RESULTS

Two cases (1 Swedish and 1 Czech) with germline mutation in CEL were identified. Clinical and radiological investigations of these 2 probands and their families revealed dominantly inherited insulin-dependent diabetes, pancreatic exocrine dysfunction, and atrophic pancreas with lipomatosis and cysts. Notably, hereditary pancreatitis was the predominant phenotype in 1 pedigree. Both families carried single-base pair deletions in the proximal part of the CEL variable number of tandem repeat (VNTR) region in exon 11. The mutations are predicted to lead to aberrant protein tails that make the CEL protein susceptible to aggregation.

CONCLUSION

The diagnosis of MODY8 requires a pancreatic exocrine phenotype and a deletion in the CEL VNTR in addition to dominantly inherited diabetes. CEL screening may be warranted also in families with hereditary pancreatitis of unknown genetic etiology.

C/EBPB-dependent adaptation to palmitic acid promotes tumor formation in hormone receptor negative breast cancer

Epidemiological studies have established a positive association between obesity and the incidence of postmenopausal breast cancer. Moreover, it is known that obesity promotes stem cell-like properties of breast cancer cells. However, the cancer cell-autonomous mechanisms underlying this correlation are not well defined. Here we demonstrate that obesity-associated tumor formation is driven by cellular adaptation rather than expansion of pre-existing clones within the cancer cell population. While there is no correlation with specific mutations, cellular adaptation to obesity is governed by palmitic acid (PA) and leads to enhanced tumor formation capacity of breast cancer cells. This process is governed epigenetically through increased chromatin occupancy of the transcription factor CCAAT/enhancer-binding protein beta (C/EBPB). Obesity-induced epigenetic activation of C/EBPB regulates cancer stem-like properties by modulating the expression of key downstream regulators including CLDN1 and LCN2. Collectively, our findings demonstrate that obesity drives cellular adaptation to PA drives tumor initiation in the obese setting through activation of a C/EBPB dependent transcriptional network.

Obesity is linked to cancer risk in post-menopausal breast cancer. At the molecular level this is governed by cellular adaption to palmitic acid through epigenetic activation of a C/EBPB-dependent transcriptional network that drives tumor formation.

Abnormal exocrine-endocrine cell cross-talk promotes β-cell dysfunction and loss in MODY8

MODY8 (maturity-onset diabetes of the young, type 8) is a dominantly inherited monogenic form of diabetes associated with mutations in the carboxyl ester lipase (CEL) gene expressed by pancreatic acinar cells. MODY8 patients develop childhood-onset exocrine pancreas dysfunction followed by diabetes during adulthood. However, it is unclear how CEL mutations cause diabetes. In the present study, we report the transfer of CEL proteins from acinar cells to β-cells as a form of cross-talk between exocrine and endocrine cells. Human β-cells show a relatively higher propensity for internalizing the mutant versus the wild-type CEL protein. After internalization, the mutant protein forms stable intracellular aggregates leading to β-cell secretory dysfunction. Analysis of pancreas sections from a MODY8 patient reveals the presence of CEL protein in the few extant β-cells. The present study provides compelling evidence for the mechanism by which a mutant gene expressed specifically in acinar cells promotes dysfunction and loss of β-cells to cause diabetes.

KRAS mutation analysis by droplet digital PCR of duodenal juice from patients with MODY8 and other pancreatic diseases

BACKGROUND

Maturity-onset diabetes of the young type 8 (MODY8 or CEL-MODY) is an inherited pancreatic disease characterized by chronic inflammation of the pancreas and diabetes. It is not known whether MODY8 patients have increased risk for developing pancreatic cancer. We investigated KRAS mutation load in duodenal juice from MODY8 patients, comparing with other groups of pancreatic disease.

METHODS

Droplet digital PCR (ddPCR) was used to detect KRAS codon 12/13/61 mutations in duodenal juice sampled from 11 MODY8 patients, nine healthy subjects and 100 patients clinically investigated due to suspected pancreatic disease.

RESULTS

KRAS mutations were detected in 4/11 patients with MODY8 (36%), 1/9 healthy subjects (11%), 15/44 patients with chronic pancreatitis (CP, 34%), 3/5 patients with pancreatic ductal adenocarcinoma (PDAC, 60%), 3/20 patients with acute pancreatitis (15%), 0/13 patients with other pancreatic disorders and 2/18 patients with nonpancreatic gastrointestinal disease (11%). Of the 28 positive juice samples, 25 (89%) had low-abundance mutations in codons 12/13, with a variant allele frequency (VAF) less than 1%. KRAS-positive patients with MODY8 or CP had significantly lower VAFs than patients with PDAC (Mann-Whitney U test; p = 0.041). Although the overall mutation detection rate was higher for subjects ≥50 years old (26%) than for younger subjects (15%), the difference was not statistically significant.

CONCLUSIONS

KRAS mutations were detectable in duodenal juice from MODY8 patients, but with low abundance and at the same frequency as in CP patients. The discriminative value of the analysis with regard to other pancreatic disease was limited.

Germline ATM variants predispose to melanoma: a joint analysis across the GenoMEL and MelaNostrum consortia

PURPOSE

Ataxia-Telangiectasia Mutated (ATM) has been implicated in the risk of several cancers, but establishing a causal relationship is often challenging. Although ATM single-nucleotide polymorphisms have been linked to melanoma, few functional alleles have been identified. Therefore, ATM impact on melanoma predisposition is unclear.

METHODS

From 22 American, Australian, and European sites, we collected 2,104 familial, multiple primary (MPM), and sporadic melanoma cases who underwent ATM genotyping via panel, exome, or genome sequencing, and compared the allele frequency (AF) of selected ATM variants classified as loss-of-function (LOF) and variants of uncertain significance (VUS) between this cohort and the gnomAD non-Finnish European (NFE) data set.

RESULTS

LOF variants were more represented in our study cohort than in gnomAD NFE, both in all (AF = 0.005 and 0.002, OR = 2.6, 95% CI = 1.56-4.11, p < 0.01), and familial + MPM cases (AF = 0.0054 and 0.002, OR = 2.97, p < 0.01). Similarly, VUS were enriched in all (AF = 0.046 and 0.033, OR = 1.41, 95% CI = 1.6-5.09, p < 0.01) and familial + MPM cases (AF = 0.053 and 0.033, OR = 1.63, p < 0.01). In a case-control comparison of two centers that provided 1,446 controls, LOF and VUS were enriched in familial + MPM cases (p = 0.027, p = 0.018).

CONCLUSION

This study, describing the largest multicenter melanoma cohort investigated for ATM germline variants, supports the role of ATM as a melanoma predisposition gene, with LOF variants suggesting a moderate-risk.

The position of single-base deletions in the VNTR sequence of the carboxyl ester lipase (CEL) gene determines proteotoxicity

Variable number of tandem repeat (VNTR) sequences in the genome can have functional consequences that contribute to human disease. This is the case for the CEL gene, which is specifically expressed in pancreatic acinar cells and encodes the digestive enzyme carboxyl ester lipase. Rare single-base deletions (DELs) within the first (DEL1) or fourth (DEL4) VNTR segment of CEL cause maturity-onset diabetes of the young, type 8 (MODY8), an inherited disorder characterized by exocrine pancreatic dysfunction and diabetes. Studies on the DEL1 variant have suggested that MODY8 is initiated by CEL protein misfolding and aggregation. However, it is unclear how the position of single-base deletions within the CEL VNTR affects pathogenic properties of the protein. Here, we investigated four naturally occurring CEL variants, arising from single-base deletions in different VNTR segments (DEL1, DEL4, DEL9, and DEL13). When the four variants were expressed in human embryonic kidney 293 cells, only DEL1 and DEL4 led to significantly reduced secretion, increased intracellular aggregation, and increased endoplasmic reticulum stress compared with normal CEL protein. The level of O-glycosylation was affected in all DEL variants. Moreover, all variants had enzymatic activity comparable with that of normal CEL. We conclude that the longest aberrant protein tails, resulting from single-base deletions in the proximal VNTR segments, have highest pathogenic potential, explaining why DEL1 and DEL4 but not DEL9 and DEL13 have been observed in patients with MODY8. These findings further support the view that CEL mutations cause pancreatic disease through protein misfolding and proteotoxicity, leading to endoplasmic reticulum stress and activation of the unfolded protein response.

Functional evaluation of 16 SCHAD missense variants: Only amino acid substitutions causing congenital hyperinsulinism of infancy lead to loss-of-function phenotypes in vitro

Short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD), encoded by the HADH gene, is a ubiquitously expressed mitochondrial enzyme involved in fatty acid oxidation. This protein also plays a role in insulin secretion as recessive HADH mutations cause congenital hyperinsulinism of infancy (CHI) via loss of an inhibitory interaction with glutamate dehydrogenase (GDH). Here, we present a functional evaluation of 16 SCHAD missense variants identified either in CHI patients or by high-throughput sequencing projects in various populations. To avoid interactions with endogenously produced SCHAD protein, we assessed protein stability, subcellular localization, and GDH interaction in a SCHAD knockout HEK293 cell line constructed by CRISPR-Cas9 methodology. We also established methods for efficient SCHAD expression and purification in E. coli, and tested enzymatic activity of the variants. Our analyses showed that rare variants of unknown significance identified in populations generally had similar properties as normal SCHAD. However, the CHI-associated variants p.Gly34Arg, p.Ile184Phe, p.Pro258Leu, and p.Gly303Ser were unstable with low protein levels detectable when expressed in HEK293 cells. Moreover, CHI variants p.Lys136Glu, p.His170Arg, and p.Met188Val presented normal protein levels but displayed clearly impaired enzymatic activity in vitro, and their interaction with GDH appeared reduced. Our results suggest that pathogenic missense variants of SCHAD either make the protein target of a post-translational quality control system or can impair the function of SCHAD without influencing its steady-state protein level. We did not find any evidence that rare SCHAD missense variants observed only in the general population and not in CHI patients are functionally affected.

Association of HERV-K and LINE-1 hypomethylation with reduced disease-free survival in melanoma patients

Aim: To evaluate CpG methylation of long interspersed nuclear elements 1 (LINE-1) and human endogenous retrovirus K (HERV-K) retroelements as potential prognostic biomarkers in cutaneous melanoma. Materials & methods: Methylation of HERV-K and LINE-1 retroelements was assessed in resected melanoma tissues from 82 patients ranging in age from 14 to 88 years. In addition, nevi from eight patients were included for comparison with nonmalignant melanocytic lesions. Results: Methylation levels were lower in melanomas than in nevi. HERV-K and LINE-1 methylation were decreased in melanoma patients with clinical parameters associated with adverse prognosis, while they were independent of age and gender. Hypomethylation of HERV-K (but not LINE-1) was an independent predictor of reduced disease-free survival. Conclusion: HERV-K hypomethylation can be a potential independent biomarker of melanoma recurrence.

Unsupervised Clustering of Missense Variants in HNF1A Using Multidimensional Functional Data Aids Clinical Interpretation

Exome sequencing in diabetes presents a diagnostic challenge because depending on frequency, functional impact, and genomic and environmental contexts, HNF1A variants can cause maturity-onset diabetes of the young (MODY), increase type 2 diabetes risk, or be benign. A correct diagnosis matters as it informs on treatment, progression, and family risk. We describe a multi-dimensional functional dataset of 73 HNF1A missense variants identified in exomes of 12,940 individuals. Our aim was to develop an analytical framework for stratifying variants along the HNF1A phenotypic continuum to facilitate diagnostic interpretation. HNF1A variant function was determined by four different molecular assays. Structure of the multi-dimensional dataset was explored using principal component analysis, k-means, and hierarchical clustering. Weights for tissue-specific isoform expression and functional domain were integrated. Functionally annotated variant subgroups were used to re-evaluate genetic diagnoses in national MODY diagnostic registries. HNF1A variants demonstrated a range of behaviors across the assays. The structure of the multi-parametric data was shaped primarily by transactivation. Using unsupervised learning methods, we obtained high-resolution functional clusters of the variants that separated known causal MODY variants from benign and type 2 diabetes risk variants and led to reclassification of 4% and 9% of HNF1A variants identified in the UK and Norway MODY diagnostic registries, respectively. Our proof-of-principle analyses facilitated informative stratification of HNF1A variants along the continuum, allowing improved evaluation of clinical significance, management, and precision medicine in diabetes clinics. Transcriptional activity appears a superior readout supporting pursuit of transactivation-centric experimental designs for high-throughput functional screens.

Single nucleotide polymorphisms in CEL-HYB1 increase risk for chronic pancreatitis through proteotoxic misfolding

Genetic variants contribute to the risk of chronic pancreatitis (CP) in adults and children. The risk variant CEL-HYB1, a recombinant hybrid allele of CEL and its neighboring pseudogene (CELP), encodes a pathogenic variant of the pancreatic digestive enzyme carboxyl ester lipase (CEL). We previously identified combinations of two non-synonymous SNPs, c.1463T>C (p. Ile488Thr) and c.1643C>T (p. Thr548Ile), in the break point region of CEL-HYB1. Herein, we tested whether these missense variants alter CP risk and their impact on functional properties of the CEL-HYB1 protein. Examination of CEL-HYB1 haplotypes in European patients and controls revealed that the combinationThr488-Ile548 was present only in cases (p ≤ .001). The lipase activity of purified recombinant CEL-HYB1 variants showed normal or near normal activity. CEL-HYB variants expressed in HEK293T cells all had decreased secretion compared with CEL, formed intracellular protein aggregates, and triggered endoplasmic reticulum stress. Thus, we propose that the presence of missense variants in CEL-HYB increases the pathogenicity of CEL-HYB1 through misfolding and gain-of-function proteotoxicity. Interestingly, Thr488-Ile548 and Thr488-Thr548 were equally pathogenic in the functional assays even though only the Thr488-Ile548 haplotype was significantly enriched in cases. The explanation for the mismatch between genetic and functional data requires further investigation.

Genome-wide association meta-analyses combining multiple risk phenotypes provide insights into the genetic architecture of cutaneous melanoma susceptibility

Most genetic susceptibility to cutaneous melanoma remains to be discovered. Meta-analysis genome-wide association study (GWAS) of 36,760 cases of melanoma (67% newly genotyped) and 375,188 controls identified 54 significant (P < 5 × 10-8) loci with 68 independent single nucleotide polymorphisms. Analysis of risk estimates across geographical regions and host factors suggests the acral melanoma subtype is uniquely unrelated to pigmentation. Combining this meta-analysis with GWAS of nevus count and hair color, and transcriptome association approaches, uncovered 31 potential secondary loci for a total of 85 cutaneous melanoma susceptibility loci. These findings provide insights into cutaneous melanoma genetic architecture, reinforcing the importance of nevogenesis, pigmentation and telomere maintenance, together with identifying potential new pathways for cutaneous melanoma pathogenesis.

Golgi-Localized PAQR4 Mediates Antiapoptotic Ceramidase Activity in Breast Cancer

The metabolic network of sphingolipids plays important roles in cancer biology. Prominent sphingolipids include ceramides and sphingosine-1-phosphate that regulate multiple aspects of growth, apoptosis, and cellular signaling. Although a significant number of enzymatic regulators of the sphingolipid pathway have been described in detail, many remained poorly characterized. Here we applied a patient-derived systemic approach to identify and molecularly define progestin and adipoQ receptor family member IV (PAQR4) as a Golgi-localized ceramidase. PAQR4 was approximately 5-fold upregulated in breast cancer compared with matched control tissue and its overexpression correlated with disease-specific survival rates in breast cancer. Induction of PAQR4 in breast tumors was found to be subtype-independent and correlated with increased ceramidase activity. These findings establish PAQR4 as Golgi-localized ceramidase required for cellular growth in breast cancer. SIGNIFICANCE: Induction of and cellular dependency on de novo sphingolipid synthesis via PAQR4 highlights a central vulnerability in breast cancer that may serve as a viable therapeutic target.

Characterization of CEL-DUP2: Complete duplication of the carboxyl ester lipase gene is unlikely to influence risk of chronic pancreatitis

BACKGROUND/OBJECTIVES

Carboxyl ester lipase is a pancreatic enzyme encoded by CEL, an extremely polymorphic human gene. Pathogenic variants of CEL either increases the risk for chronic pancreatitis (CP) or cause MODY8, a syndrome of pancreatic exocrine and endocrine dysfunction. Here, we aimed to characterize a novel duplication allele of CEL (CEL-DUP2) and to investigate whether it associates with CP or pancreatic cancer.

METHODS

The structure of CEL-DUP2 was determined by a combination of Sanger sequencing, DNA fragment analysis, multiplex ligation-dependent probe amplification and whole-genome sequencing. We developed assays for screening of CEL-DUP2 and analyzed cohorts of idiopathic CP, alcoholic CP and pancreatic cancer. CEL protein expression was analyzed by immunohistochemistry.

RESULTS

CEL-DUP2 consists of an extra copy of the complete CEL gene. The allele has probably arisen from non-allelic, homologous recombination involving the adjacent pseudogene of CEL. We found no association between CEL-DUP2 carrier frequency and CP in cohorts from France (cases/controls: 2.5%/2.4%; P = 1.0), China (10.3%/8.1%; P = 0.08) or Germany (1.6%/2.3%; P = 0.62). Similarly, no association with disease was observed in alcohol-induced pancreatitis (Germany: 3.2%/2.3%; P = 0.51) or pancreatic cancer (Norway; 2.5%/3.2%; P = 0.77). Notably, the carrier frequency of CEL-DUP2 was more than three-fold higher in Chinese compared with Europeans. CEL protein expression was similar in tissues from CEL-DUP2 carriers and controls.

CONCLUSIONS

Our results support the contention that the number of CEL alleles does not influence the risk of pancreatic exocrine disease. Rather, the pathogenic CEL variants identified so far involve exon 11 sequence changes that substantially alter the protein's tail region.

Pathogenic Carboxyl Ester Lipase (CEL) Variants Interact with the Normal CEL Protein in Pancreatic Cells

Mutations in the gene encoding the digestive enzyme carboxyl ester lipase (CEL) are linked to pancreatic disease. The CEL variant denoted CEL-HYB predisposes to chronic pancreatitis, whereas the CEL-MODY variant causes MODY8, an inherited disorder of endocrine and exocrine pancreatic dysfunction. Both pathogenic variants exhibit altered biochemical and cellular properties compared with the normal CEL protein (CEL-WT, wild type). We here aimed to investigate effects of CEL variants on pancreatic acinar and ductal cell lines. Following extracellular exposure, CEL-HYB, CEL-MODY, and CEL-WT were endocytosed. The two pathogenic CEL proteins significantly reduced cell viability compared with CEL-WT. We also found evidence of CEL uptake in primary human pancreatic acinar cells and in native ductal tissue. Moreover, coexpression of CEL-HYB or CEL-MODY with CEL-WT affected secretion of the latter, as CEL-WT was observed to accumulate intracellularly to a higher degree in the presence of either pathogenic variant. Notably, in coendocytosis experiments, both pathogenic variants displayed a modest effect on cell viability when CEL-WT was present, indicating that the normal protein might diminish toxic effects conferred by CEL-HYB and CEL-MODY. Taken together, our findings provide valuable insight into how the pathogenic CEL variants predispose to pancreatic disease and why these disorders develop slowly over time.

Integrin α11β1 is expressed in breast cancer stroma and associates with aggressive tumor phenotypes

Cancer‐associated fibroblasts are essential modifiers of the tumor microenvironment. The collagen‐binding integrin α11β1 has been proposed to be upregulated in a pro‐tumorigenic subtype of cancer‐associated fibroblasts. Here, we analyzed the expression and clinical relevance of integrin α11β1 in a large breast cancer series using a novel antibody against the human integrin α11 chain. Several novel monoclonal antibodies against the integrin α11 subunit were tested for use on formalin‐fixed paraffin‐embedded tissues, and Ab 210F4B6A4 was eventually selected to investigate the immunohistochemical expression in 392 breast cancers using whole sections. mRNA data from METABRIC and co‐expression patterns of integrin α11 in relation to αSMA and cytokeratin‐14 were also investigated. Integrin α11 was expressed to varying degrees in spindle‐shaped cells in the stroma of 99% of invasive breast carcinomas. Integrin α11 co‐localized with αSMA in stromal cells, and with αSMA and cytokeratin‐14 in breast myoepithelium. High stromal integrin α11 expression (66% of cases) was associated with aggressive breast cancer features such as high histologic grade, increased tumor cell proliferation, ER negativity, HER2 positivity, and triple‐negative phenotype, but was not associated with breast cancer specific survival at protein or mRNA levels. In conclusion, high stromal integrin α11 expression was associated with aggressive breast cancer phenotypes.

The hybrid allele 1 of carboxyl-ester lipase (CEL-HYB1) in Polish pediatric patients with chronic pancreatitis

OBJECTIVES

It has previously been reported in a European case-control study with patients from Germany and France that CEL-HYB1, a hybrid allele of the carboxyl ester lipase (CEL) gene and its pseudogene CELP, increases susceptibility to chronic pancreatitis (CP). Here, we aimed to replicate this finding in Polish pediatric patients with CP.

METHOD

The distribution of the CEL-HYB1 allele in a CP pediatric cohort (n = 147, median age at CP onset 7.6 years) with no history of alcohol/smoking abuse was compared with ethnically matched healthy controls (n = 500, median age 46 years). Screening was performed using long-range PCR followed by agarose gel-electrophoresis.

RESULTS

We observed no significant difference in the carrier frequency of the CEL-HYB1 allele between CP patients (7/147, 4.8%) and controls (12/500, 2.4%; P = 0.16).

CONCLUSIONS

This study found no statistically significant association between CEL-HYB1 and chronic pancreatitis in a cohort of Polish pediatric CP patients.

α11β1 Integrin is Induced in a Subset of Cancer-Associated Fibroblasts in Desmoplastic Tumor Stroma and Mediates In Vitro Cell Migration

Integrin α11β1 is a collagen receptor that has been reported to be overexpressed in the stroma of non-small cell lung cancer (NSCLC) and of head and neck squamous cell carcinoma (HNSCC). In the current study, we further analyzed integrin α11 expression in 14 tumor types by screening a tumor tissue array while using mAb 203E3, a newly developed monoclonal antibody to human α11. Different degrees of expression of integrin α11 were observed in the stroma of breast, ovary, skin, lung, uterus, stomach, and pancreatic ductal adenocarcinoma (PDAC) tumors. Co-expression queries with the myofibroblastic cancer-associated fibroblast (myCAF) marker, alpha smooth muscle actin (αSMA), demonstrated a moderate level of α11+ in myCAFs associated with PDAC and HNSCC tumors, and a lack of α11 expression in additional stromal cells (i.e., cells positive for fibroblast-specific protein 1 (FSP1) and NG2). The new function-blocking α11 antibody, mAb 203E1, inhibited cell adhesion to collagen I, partially hindered fibroblast-mediated collagen remodeling and obstructed the three-dimensional (3D) migration rates of PDAC myCAFs. Our data demonstrate that integrin α11 is expressed in a subset of non-pericyte-derived CAFs in a range of cancers and suggest that α11β1 constitutes an important receptor for collagen remodeling and CAF migration in the tumor microenvironment (TME).

Mutation analysis by deep sequencing of pancreatic juice from patients with pancreatic ductal adenocarcinoma

Background

Reliable methods are needed to identify patients with early-stage cancer or high-grade precancerous lesions in the pancreas. Analysis of pancreatic juice to detect somatic mutations could represent one such approach. Here we investigated the concordance between mutations found in the primary tumor and pancreatic juice from the same patient.

Methods

Amplicon-based targeted deep sequencing was performed on samples from 21 patients with pancreatic ductal adenocarcinoma (PDAC) who had undergone Whipple’s operation. Mutation profiles were determined in formalin-fixed sections of the primary tumor and in pancreatic juice sampled from the main pancreatic duct during surgery.

Results

Using a cut-off of 3% for variant allele frequency, KRAS mutations were detected in 20/21 primary tumors (95%) and in 15/21 (71%) juice samples. When also considering low-frequency variants, KRAS mutations were found in 20/21 juice samples. Most juice samples exhibited multiple KRAS variants not seen in the primary tumor, and only in 11 cases (52%) did the most abundant variant of the juice correspond to the KRAS mutation detected in the tumor. TP53 mutations were found in 16 tumors (76%) and six juice samples (29%). Among the positive juice samples, only one exhibited more than a single TP53 mutation. Detection of both KRAS and TP53 mutations was fully concordant in the primary tumor and juice sample in 7/21 cases (33%).

Conclusions

Pancreatic juice from PDAC patients is rich in KRAS mutations often not seen in the primary tumor and possibly reflecting precancerous lesions in other regions of the pancreas. The inclusion of TP53 mutation detection and additional markers must therefore be considered for fully exploiting the clinical potential of pancreatic juice samples in early cancer detection.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5195-7) contains supplementary material, which is available to authorized users.

Author Correction: Telomere length and survival in primary cutaneous melanoma patients

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

The mucinous domain of pancreatic carboxyl-ester lipase (CEL) contains core 1/core 2 O-glycans that can be modified by ABO blood group determinants

Carboxyl-ester lipase (CEL) is a pancreatic fat-digesting enzyme associated with human disease. Rare mutations in the CEL gene cause a syndrome of pancreatic exocrine and endocrine dysfunction denoted MODY8, whereas a recombined CEL allele increases the risk for chronic pancreatitis. Moreover, CEL has been linked to pancreatic ductal adenocarcinoma (PDAC) through a postulated oncofetal CEL variant termed feto-acinar pancreatic protein (FAPP). The monoclonal antibody mAb16D10 was previously reported to detect a glycotope in the highly O-glycosylated, mucin-like C terminus of CEL/FAPP. We here assessed the expression of human CEL in malignant pancreatic lesions and cell lines. CEL was not detectably expressed in neoplastic cells, implying that FAPP is unlikely to be a glycoisoform of CEL in pancreatic cancer. Testing of the mAb16D10 antibody in glycan microarrays then demonstrated that it recognized structures containing terminal GalNAc-α1,3(Fuc-α1,2)Gal (blood group A antigen) and also repeated protein sequences containing GalNAc residues linked to Ser/Thr (Tn antigen), findings that were supported by immunostainings of human pancreatic tissue. To examine whether the CEL glycoprotein might be modified by blood group antigens, we used high-sensitivity MALDI-TOF MS to characterize the released O-glycan pool of CEL immunoprecipitated from human pancreatic juice. We found that the O-glycome of CEL consisted mainly of core 1/core 2 structures with a composition depending on the subject's FUT2 and ABO gene polymorphisms. Thus, among digestive enzymes secreted by the pancreas, CEL is a glycoprotein with some unique characteristics, supporting the view that it could serve additional biological functions to its cholesteryl esterase activity in the duodenum.

Telomere length and survival in primary cutaneous melanoma patients

Telomere repeats at chromosomal ends, critical to genomic integrity, undergo age-dependent attrition. Telomere length, a polygenic trait, has been associated with risk of several disorders including cancers. In contrast to association of long telomeres with increased risk of several cancers, including melanoma, emerging reports suggest that short telomeres predict poor survival in patients with different cancers. In this study based on 1019 stage I and II cutaneous melanoma patients, we show an association between the patients with short telomeres and poor melanoma-specific survival (HR 2.05, 95% CI 1.33-3.16) compared to patients with long telomeres. Due to inverse correlation between age and telomere length (r -0.19, P < 0.0001), we stratified the patients into quantiles based on age at diagnosis and also carried out age-matched analysis. The effect of short telomeres on survival was determined by using multivariate Cox regression that included composite genetic risk score computed from genotyping of the patients for telomere-length associated polymorphisms. The effect of decreased telomere length on poor melanoma-specific survival was particularly strong in patients within the age quantile below 30 years (HR 3.82, 95% CI 1.10-13.30) and between 30-40 years (HR 2.69, 95% CI 1.03-7.03). Our study shows that in contrast to increased melanoma risk associated with increased telomere length, decreased telomere length predicts poor survival in melanoma subgroups.

Mice Carrying a Dominant-Negative Human PI3K Mutation Are Protected From Obesity and Hepatic Steatosis but Not Diabetes

Phosphatidylinositol 3-kinase (PI3K) plays a central role in insulin signaling, glucose metabolism, cell growth, cell development, and apoptosis. A heterozygous missense mutation (R649W) in the p85α regulatory subunit gene of PI3K (PIK3R1) has been identified in patients with SHORT (Short stature, Hyperextensibility/Hernia, Ocular depression, Rieger anomaly, and Teething delay) syndrome, a disorder characterized by postnatal growth retardation, insulin resistance, and partial lipodystrophy. Knock-in mice with the same heterozygous mutation mirror the human phenotype. In this study, we show that Pik3r1 R649W knock-in mice fed a high-fat diet (HFD) have reduced weight gain and adipose accumulation. This is accompanied by reduced expression of several genes involved in lipid metabolism. Interestingly, despite the lower level of adiposity, the HFD knock-in mice are more hyperglycemic and more insulin-resistant than HFD-fed control mice. Likewise, when crossed with genetically obese ob/ob mice, the ob/ob mice carrying the heterozygous R649W mutation were protected from obesity and hepatic steatosis but developed a severe diabetic state. Together, our data demonstrate a central role of PI3K in development of obesity and fatty liver disease, separating these effects from the role of PI3K in insulin resistance and the resultant hyperglycemia.

The role of the carboxyl ester lipase (CEL) gene in pancreatic disease

The enzyme carboxyl ester lipase (CEL), also known as bile salt-dependent or -stimulated lipase (BSDL, BSSL), hydrolyzes dietary fat, cholesteryl esters and fat-soluble vitamins in the duodenum. CEL is mainly expressed in pancreatic acinar cells and lactating mammary glands. The human CEL gene resides on chromosome 9q34.3 and contains a variable number of tandem repeats (VNTR) region that encodes a mucin-like protein tail. Although the number of normal repeats does not appear to significantly influence the risk for pancreatic disease, single-base pair deletions in the first VNTR repeat cause a syndrome of endocrine and exocrine dysfunction denoted MODY8. Hallmarks are low fecal elastase levels and pancreatic lipomatosis manifesting before the age of twenty, followed by development of diabetes and pancreatic cysts later in life. The mutant protein forms intracellular and extracellular aggregates, suggesting that MODY8 is a protein misfolding disease. Recently, a recombined allele between CEL and its pseudogene CELP was discovered. This allele (CEL-HYB) encodes a chimeric protein with impaired secretion increasing five-fold the risk for chronic pancreatitis. The CEL gene has proven to be exceptionally polymorphic due to copy number variants of the CEL-CELP locus and alterations involving the VNTR. Genome-wide association studies or deep sequencing cannot easily pick up this wealth of genetic variation. CEL is therefore an attractive candidate gene for further exploration of links to pancreatic disease.

The HNF1A mutant Ala180Val: Clinical challenges in determining causality of a rare HNF1A variant in familial diabetes

AIMS

Heterozygous mutations in hepatocyte nuclear factor-1A (HNF1A) cause maturity-onset diabetes of the young type 3 (MODY3). Our aim was to compare two families with suspected dominantly inherited diabetes and a new HNF1A variant of unknown clinical significance.

METHODS

The HNF1A gene was sequenced in two independently recruited families from the Norwegian MODY Registry. Both familes were phenotyped clinically and biochemically. Microsatellite markers around and within the HNF1A locus were used for haplotyping. Chromosomal linkage analysis was performed in one family, and whole-exome sequencing was undertaken in two affected family members from each family. Transactivation activity, DNA binding and nuclear localization of wild type and mutant HNF-1A were assessed.

RESULTS

The novel HNF1A variant c.539C>T (p.Ala180Val) was found in both families. The variant fully co-segregated with diabetes in one family. In the other family, two subjects with diabetes mellitus and one with normal glucose levels were homozygous variant carriers. Chromosomal linkage of diabetes to the HNF1A locus or to other genomic regions could not be established. The protein functional studies did not reveal significant differences between wild type and variant HNF-1A. In each family, whole-exome sequencing failed to identify any other variant that could explain the disease.

CONCLUSIONS

The HNF1A variant p.Ala180Val does not seem to cause MODY3, although it may confer risk for type 2 diabetes mellitus. Our data demonstrate challenges in causality evaluation of rare variants detected in known diabetes genes.

Heterogeneity of proliferative markers in pancreatic β-cells of patients with severe hypoglycemia following Roux-en-Y gastric bypass

AIMS

Severe postprandial hypoglycemia with neuroglycopenia is an increasingly recognized, debilitating complication of Roux-en-Y gastric bypass (RYGB) surgery. Increased secretion of insulin and incretin hormones is implicated in its pathogenesis. Histopathologic examination of pancreas has demonstrated increased islet size and/or nuclear diameter in post-RYGB patients who underwent pancreatectomy for severe refractory hypoglycemia with neuroglycopenia (RYGB + NG). We aimed to determine whether β-cell proliferation or apoptosis is altered in RYGB + NG.

METHODS

We performed an observational study to analyze markers of proliferation, apoptosis, cell cycle, and transcription factor expression in pancreatic tissue from affected RYGB + NG patients (n = 12), normoglycemic patients undergoing pancreatic surgery for benign lesions (controls, n = 6), and individuals with hypoglycemia due to insulinoma (n = 52).

RESULTS

Proliferative cell nuclear antigen (PCNA) expression was increased in insulin-positive cells in RYGB + NG patients (4.5-fold increase, p < 0.001 vs. controls) and correlated with β-cell mass. Ki-67 immunoreactivity was low in both RYGB + NG and controls, but did not differ between groups. Phospho-histone H3 levels did not differ between RYGB + NG and controls. PCNA and Ki-67 were both significantly lower in both controls and RYGB + NG than insulinomas. Markers of apoptosis and cell cycle (M30, p27, and p21) did not differ between groups. PDX1 and menin exhibited similar expression patterns, while FOXO1 appeared to be more cytosolic in RYGB + NG.

CONCLUSIONS

Markers of proliferation are heterogeneous in patients with severe post-RYGB hypoglycemia. Increased β-cell proliferation in some individuals may contribute to increased β-cell mass observed in severely affected patients.

Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase

Purpose

To determine the ocular consequences of a dominant-negative mutation in the p85α subunit of phosphatidylinositol 3-kinase (PIK3R1) using a knock-in mouse model of SHORT syndrome, a syndrome associated with short stature, lipodystrophy, diabetes, and Rieger anomaly in humans.

Methods

We investigated knock-in mice heterozygous for the SHORT syndrome mutation changing arginine 649 to tryptophan in p85α (PIK3R1) using physical examination, optical coherence tomography (OCT), tonometry, and histopathologic sections from paraffin-embedded eyes, and compared the findings to similar investigations in two human subjects with SHORT syndrome heterozygous for the same mutation.

Results

While overall eye development was normal with clear cornea and lens, normal anterior chamber volume, normal intraocular pressure, and no changes in the retinal structure, OCT images of the knock-in mouse eyes revealed a significant decrease in thickness and width of the iris resulting in increased pupil area and irregularity of shape. Both human subjects had Rieger anomaly with similar defects including thin irides and irregular pupils, as well as a prominent ring of Schwalbe, goniosynechiae, early cataract formation, and glaucoma. Although the two subjects had had diabetes for more than 30 years, there were no signs of diabetic retinopathy.

Conclusions

A dominant-negative mutation in the p85α regulatory subunit of PI3K affects development of the iris, and contributes to changes consistent with anterior segment dysgenesis in both humans and mice.

Associations between ABO blood groups and pancreatic ductal adenocarcinoma: influence on resection status and survival

Both serology-based and genetic studies have reported an association between pancreatic cancer risk and ABO blood groups. We have investigated this relationship in a cohort of pancreatic cancer patients from Western Norway (n = 237) and two control materials (healthy blood donors, n = 379; unselected hospitalized patients, n = 6149). When comparing patient and blood donor ABO allele frequencies, we found only the A1 allele to be associated with significantly higher risk for pancreatic ductal adenocarcinoma (PDAC) (23.8% vs. 17.9%; OR = 1.43, P = 0.018). Analyzing phenotypes, blood group A was more frequent among PDAC cases than blood donors (50.8% vs. 40.6%; OR = 1.51, P = 0.021), an enrichment fully explained by the A1 subgroup. Blood group O frequency was lower in cases than in blood donors (33.8% vs. 42.7%; OR = 0.69, P = 0.039). This lower frequency was confirmed when cases were compared to hospitalized patients (33.8% vs. 42.9%; OR = 0.68, P = 0.012). Results for blood group B varied according to which control cohort was used for comparison. When patients were classified according to surgical treatment, the enrichment of blood group A was most prominent among unresected cases (54.0%), who also had the lowest prevalence of O (28.7%). There was a statistically significant better survival (P = 0.04) for blood group O cases than non-O cases among unresected but not among resected patients. Secretor status did not show an association with PDAC or survival. Our study demonstrates that pancreatic cancer risk is influenced by ABO status, in particular blood groups O and A1 , and that this association may reflect also in tumor resectability and survival.

Cancer cachexia associates with a systemic autophagy-inducing activity mimicked by cancer cell-derived IL-6 trans-signaling

The majority of cancer patients with advanced disease experience weight loss, including loss of lean body mass. Severe weight loss is characteristic for cancer cachexia, a condition that significantly impairs functional status and survival. The underlying causes of cachexia are incompletely understood, and currently no therapeutic approach can completely reverse the condition. Autophagy coordinates lysosomal destruction of cytosolic constituents and is systemically induced by starvation. We hypothesized that starvation-mimicking signaling compounds secreted from tumor cells may cause a systemic acceleration of autophagy during cachexia. We found that IL-6 secreted by tumor cells accelerates autophagy in myotubes when complexed with soluble IL-6 receptor (trans-signaling). In lung cancer patients, were cachexia is prevalent, there was a significant correlation between elevated IL-6 expression in the tumor and poor prognosis of the patients. We found evidence for an autophagy-inducing bioactivity in serum from cancer patients and that this is clearly associated with weight loss. Importantly, the autophagy-inducing bioactivity was reduced by interference with IL-6 trans-signaling. Together, our findings suggest that IL-6 trans-signaling may be targeted in cancer cachexia.

Hypoglycemia and decreased insulin requirement caused by malignant insulinoma in a type 1 diabetic patient: when the hoof beats are from a zebra, not a horse

Insulinomas are uncommon tumors, and in patients with diabetes mellitus they are extremely rare. We describe a patient with type 1 diabetes who developed malignant insulinoma. When hypoglycemic episodes persist in a patient with diabetes and treatment‐induced and other causes of hypoglycemia have been ruled out, an insulin‐producing tumor should be considered.

Targeted next-generation sequencing reveals MODY in up to 6.5% of antibody-negative diabetes cases listed in the Norwegian Childhood Diabetes Registry

AIMS/HYPOTHESIS

MODY can be wrongly diagnosed as type 1 diabetes in children. We aimed to find the prevalence of MODY in a nationwide population-based registry of childhood diabetes.

METHODS

Using next-generation sequencing, we screened the HNF1A, HNF4A, HNF1B, GCK and INS genes in all 469 children (12.1%) negative for both GAD and IA-2 autoantibodies and 469 antibody-positive matched controls selected from the Norwegian Childhood Diabetes Registry (3882 children). Variants were classified using clinical diagnostic criteria for pathogenicity ranging from class 1 (neutral) to class 5 (pathogenic).

RESULTS

We identified 58 rare exonic and splice variants in cases and controls. Among antibody-negative patients, 6.5% had genetic variants of classes 3-5 (vs 2.4% in controls; p = 0.002). For the stricter classification (classes 4 and 5), the corresponding number was 4.1% (vs 0.2% in controls; p = 1.6 × 10^-5). HNF1A showed the strongest enrichment of class 3-5 variants, with 3.9% among antibody-negative patients (vs 0.4% in controls; p = 0.0002). Antibody-negative carriers of variants in class 3 had a similar phenotype to those carrying variants in classes 4 and 5.

CONCLUSIONS/INTERPRETATION

This is the first study screening for MODY in all antibody-negative children in a nationwide population-based registry. Our results suggest that the prevalence of MODY in antibody-negative childhood diabetes may reach 6.5%. One-third of these MODY cases had not been recognised by clinicians. Since a precise diagnosis is important for treatment and genetic counselling, molecular screening of all antibody-negative children should be considered in routine diagnostics.

Tissue MicroRNA profiles as diagnostic and prognostic biomarkers in patients with resectable pancreatic ductal adenocarcinoma and periampullary cancers

Background

The aim of this study was to validate previously described diagnostic and prognostic microRNA expression profiles in tissue samples from patients with pancreatic cancer and other periampullary cancers.

Methods

Expression of 46 selected microRNAs was studied in formalin-fixed paraffin-embedded tissue from patients with resected pancreatic ductal adenocarcinoma (n = 165), ampullary cancer (n=59), duodenal cancer (n = 6), distal common bile duct cancer (n = 21), and gastric cancer (n = 20); chronic pancreatitis (n = 39); and normal pancreas (n = 35). The microRNAs were analyzed by PCR using the Fluidigm platform.

Results

Twenty-two microRNAs were significantly differently expressed in patients with pancreatic cancer when compared to healthy controls and chronic pancreatitis patients; 17 miRNAs were upregulated (miR-21-5p, −23a-3p, −31-5p, −34c-5p, −93-3p, −135b-3p, −155-5p, −186-5p, −196b-5p, −203, −205-5p, −210, −222-3p, −451, −492, −614, and miR-622) and 5 were downregulated (miR-122-5p, −130b-3p, −216b, −217, and miR-375). MicroRNAs were grouped into diagnostic indices of varying complexity. Ten microRNAs associated with prognosis were identified (let-7 g, miR-29a-5p, −34a-5p, −125a-3p, −146a-5p, −187, −205-5p, −212-3p, −222-5p, and miR-450b-5p). Prognostic indices based on differences in expression of 2 different microRNAs were constructed for pancreatic and ampullary cancer combined and separately (30, 5, and 21 indices).

Conclusion

The study confirms that pancreatic cancer tissue has a microRNA expression profile that is different from that of other periampullary cancers, chronic pancreatitis, and normal pancreas. We identified prognostic microRNAs and microRNA indices that were associated with shorter overall survival in patients with radically resected pancreatic cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s40364-017-0087-6) contains supplementary material, which is available to authorized users.

Functional Investigations of HNF1A Identify Rare Variants as Risk Factors for Type 2 Diabetes in the General Population

Variants in HNF1A encoding hepatocyte nuclear factor 1α (HNF-1A) are associated with maturity-onset diabetes of the young form 3 (MODY 3) and type 2 diabetes. We investigated whether functional classification of HNF1A rare coding variants can inform models of diabetes risk prediction in the general population by analyzing the effect of 27 HNF1A variants identified in well-phenotyped populations (n = 4,115). Bioinformatics tools classified 11 variants as likely pathogenic and showed no association with diabetes risk (combined minor allele frequency [MAF] 0.22%; odds ratio [OR] 2.02; 95% CI 0.73-5.60; P = 0.18). However, a different set of 11 variants that reduced HNF-1A transcriptional activity to <60% of normal (wild-type) activity was strongly associated with diabetes in the general population (combined MAF 0.22%; OR 5.04; 95% CI 1.99-12.80; P = 0.0007). Our functional investigations indicate that 0.44% of the population carry HNF1A variants that result in a substantially increased risk for developing diabetes. These results suggest that functional characterization of variants within MODY genes may overcome the limitations of bioinformatics tools for the purposes of presymptomatic diabetes risk prediction in the general population.

Length of Variable Numbers of Tandem Repeats in the Carboxyl Ester Lipase (CEL) Gene May Confer Susceptibility to Alcoholic Liver Cirrhosis but Not Alcoholic Chronic Pancreatitis

BACKGROUND

Carboxyl-ester lipase (CEL) contributes to fatty acid ethyl ester metabolism, which is implicated in alcoholic pancreatitis. The CEL gene harbours a variable number of tandem repeats (VNTR) region in exon 11. Variation in this VNTR has been linked to monogenic pancreatic disease, while conflicting results were reported for chronic pancreatitis (CP). Here, we aimed to investigate a potential association of CEL VNTR lengths with alcoholic CP.

METHODS

Overall, 395 alcoholic CP patients, 218 patients with alcoholic liver cirrhosis (ALC) serving as controls with a comparable amount of alcohol consumed, and 327 healthy controls from Germany and the United Kingdom (UK) were analysed by determination of fragment lengths by capillary electrophoresis. Allele frequencies and genotypes of different VNTR categories were compared between the groups.

RESULTS

Twelve repeats were overrepresented in UK ACP patients (P = 0.04) compared to controls, whereas twelve repeats were enriched in German ALC compared to alcoholic CP patients (P = 0.03). Frequencies of CEL VNTR lengths of 14 and 15 repeats differed between German ALC patients and healthy controls (P = 0.03 and 0.008, respectively). However, in the genotype and pooled analysis of VNTR lengths no statistical significant association was depicted. Additionally, the 16-16 genotype as well as 16 repeats were more frequent in UK ALC than in alcoholic CP patients (P = 0.034 and 0.02, respectively). In all other calculations, including pooled German and UK data, allele frequencies and genotype distributions did not differ significantly between patients and controls or between alcoholic CP and ALC.

CONCLUSIONS

We did not obtain evidence that CEL VNTR lengths are associated with alcoholic CP. However, our results suggest that CEL VNTR lengths might associate with ALC, a finding that needs to be clarified in larger cohorts.

A human clinical trial using ultrasound and microbubbles to enhance gemcitabine treatment of inoperable pancreatic cancer

BACKGROUND

The primary aim of our study was to evaluate the safety and potential toxicity of gemcitabine combined with microbubbles under sonication in inoperable pancreatic cancer patients. The secondary aim was to evaluate a novel image-guided microbubble-based therapy, based on commercially available technology, towards improving chemotherapeutic efficacy, preserving patient performance status, and prolonging survival.

METHODS

Ten patients were enrolled and treated in this Phase I clinical trial. Gemcitabine was infused intravenously over 30min. Subsequently, patients were treated using a commercial clinical ultrasound scanner for 31.5min. SonoVue® was injected intravenously (0.5ml followed by 5ml saline every 3.5min) during the ultrasound treatment with the aim of inducing sonoporation, thus enhancing therapeutic efficacy.

RESULTS

The combined therapeutic regimen did not induce any additional toxicity or increased frequency of side effects when compared to gemcitabine chemotherapy alone (historical controls). Combination treated patients (n=10) tolerated an increased number of gemcitabine cycles compared with historical controls (n=63 patients; average of 8.3±6.0cycles, versus 13.8±5.6cycles, p=0.008, unpaired t-test). In five patients, the maximum tumour diameter was decreased from the first to last treatment. The median survival in our patients (n=10) was also increased from 8.9months to 17.6months (p=0.011).

CONCLUSIONS

It is possible to combine ultrasound, microbubbles, and chemotherapy in a clinical setting using commercially available equipment with no additional toxicities. This combined treatment may improve the clinical efficacy of gemcitabine, prolong the quality of life, and extend survival in patients with pancreatic ductal adenocarcinoma.

Copy number variants and VNTR length polymorphisms of the carboxyl-ester lipase (CEL) gene as risk factors in pancreatic cancer

BACKGROUND/OBJECTIVES

We have recently described copy number variants (CNVs) of the human carboxyl-ester lipase (CEL) gene, including a recombined deletion allele (CEL-HYB) that is a genetic risk factor for chronic pancreatitis. Associations with pancreatic disease have also been reported for the variable number of tandem repeat (VNTR) region located in CEL exon 11. Here, we examined if CEL CNVs and VNTR length polymorphisms affect the risk for developing pancreatic cancer.

METHODS

CEL CNVs and VNTR were genotyped in a German family with non-alcoholic chronic pancreatitis and pancreatic cancer, in 265 German and 197 Norwegian patients diagnosed with pancreatic adenocarcinoma, and in 882 controls. CNV screening was performed using PCR assays followed by agarose gel electrophoresis whereas VNTR lengths were determined by DNA fragment analysis.

RESULTS

The investigated family was CEL-HYB-positive. However, an association of CEL-HYB or a duplication CEL allele with pancreatic cancer was not seen in our two patient cohorts. The frequency of the 23-repeat VNTR allele was borderline significant in Norwegian cases compared to controls (1.2% vs. 0.3%; P = 0.05). For all other VNTR lengths, no statistically significant difference in frequency was observed. Moreover, no association with pancreatic cancer was detected when CEL VNTR lengths were pooled into groups of short, normal or long alleles.

CONCLUSIONS

We could not demonstrate an association between CEL CNVs and pancreatic cancer. An association is also unlikely for CEL VNTR lengths, although analyses in larger materials are necessary to completely exclude an effect of rare VNTR alleles.

Branched Fatty Acid Esters of Hydroxy Fatty Acids Are Preferred Substrates of the MODY8 Protein Carboxyl Ester Lipase

A recently discovered class of endogenous mammalian lipids, branched fatty acid esters of hydroxy fatty acids (FAHFAs), possesses anti-diabetic and anti-inflammatory activities. Here, we identified and validated carboxyl ester lipase (CEL), a pancreatic enzyme hydrolyzing cholesteryl esters and other dietary lipids, as a FAHFA hydrolase. Variants of CEL have been linked to maturity-onset diabetes of the young, type 8 (MODY8), and to chronic pancreatitis. We tested the FAHFA hydrolysis activity of the CEL MODY8 variant and found a modest increase in activity as compared with that of the normal enzyme. Together, the data suggest that CEL might break down dietary FAHFAs.

The Hypoglycemic Phenotype Is Islet Cell-Autonomous in Short-Chain Hydroxyacyl-CoA Dehydrogenase-Deficient Mice

Congenital hyperinsulinism of infancy (CHI) can be caused by inactivating mutations in the gene encoding short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD), a ubiquitously expressed enzyme involved in fatty acid oxidation. The hypersecretion of insulin may be explained by a loss of interaction between SCHAD and glutamate dehydrogenase in the pancreatic β-cells. However, there is also a general accumulation of metabolites specific for the enzymatic defect in affected individuals. It remains to be explored whether hypoglycemia in SCHAD CHI can be uncoupled from the systemic effect on fatty acid oxidation. We therefore transplanted islets from global SCHAD knockout (SCHADKO) mice into mice with streptozotocin-induced diabetes. After transplantation, SCHADKO islet recipients exhibited significantly lower random and fasting blood glucose compared with mice transplanted with normal islets or nondiabetic, nontransplanted controls. Furthermore, intraperitoneal glucose tolerance was improved in animals receiving SCHADKO islets compared with those receiving normal islets. Graft β-cell proliferation and apoptosis rates were similar in the two transplantation groups. We conclude that hypoglycemia in SCHAD-CHI is islet cell-autonomous.

PI3-kinase mutation linked to insulin and growth factor resistance in vivo

The phosphatidylinositol 3-kinase (PI3K) signaling pathway is central to the action of insulin and many growth factors. Heterozygous mutations in the gene encoding the p85α regulatory subunit of PI3K (PIK3R1) have been identified in patients with SHORT syndrome - a disorder characterized by short stature, partial lipodystrophy, and insulin resistance. Here, we evaluated whether SHORT syndrome-associated PIK3R1 mutations account for the pathophysiology that underlies the abnormalities by generating knockin mice that are heterozygous for the Pik3r1Arg649Trp mutation, which is homologous to the mutation found in the majority of affected individuals. Similar to the patients, mutant mice exhibited a reduction in body weight and length, partial lipodystrophy, and systemic insulin resistance. These derangements were associated with a reduced capacity of insulin and other growth factors to activate PI3K in liver, muscle, and fat; marked insulin resistance in liver and fat of mutation-harboring animals; and insulin resistance in vitro in cells derived from these mice. In addition, mutant mice displayed defective insulin secretion and GLP-1 action on islets in vivo and in vitro. These data demonstrate the ability of this heterozygous mutation to alter PI3K activity in vivo and the central role of PI3K in insulin/growth factor action, adipocyte function, and glucose metabolism.

Genome-wide meta-analysis identifies five new susceptibility loci for cutaneous malignant melanoma

Thirteen common susceptibility loci have been reproducibly associated with cutaneous malignant melanoma (CMM). We report the results of an international 2-stage meta-analysis of CMM genome-wide association studies (GWAS). This meta-analysis combines 11 GWAS (5 previously unpublished) and a further three stage 2 data sets, totaling 15,990 CMM cases and 26,409 controls. Five loci not previously associated with CMM risk reached genome-wide significance (P < 5 × 10(-8)), as did 2 previously reported but unreplicated loci and all 13 established loci. Newly associated SNPs fall within putative melanocyte regulatory elements, and bioinformatic and expression quantitative trait locus (eQTL) data highlight candidate genes in the associated regions, including one involved in telomere biology.