Epidemiology and Inherited Predisposition for Sporadic Pancreatic Adenocarcinoma

Association between prediagnostic serum metabolites and pancreatic ductal adenocarcinoma risk in two prospective cohorts

Pancreatic ductal adenocarcinoma (PDAC) is highly fatal, with incidence rising worldwide. Metabolomics may provide insight into etiology and mechanisms contributing to pancreatic carcinogenesis. We examined associations between 1483 prediagnostic (up to 24 years) serum metabolites and PDAC in nested case-control studies within a cohort of male Finnish smokers and another of American men and women (n = 732 matched pairs). We used conditional logistic regression to calculate odds ratios (OR) and 95% confidence intervals per standard deviation increase in log-metabolite level within each cohort and combined using fixed-effect meta-analyses. We performed elastic net regression (EN) to select metabolites and calculated area under the curve (AUC) for established PDAC risk factors (smoking, diabetes, and overweight/obesity), selected metabolites, and their combination. Sixty-six metabolites were associated with PDAC at false discovery rate <0.05, with 26 below Bonferroni threshold (p < 3.4 × 10-5) and 38 not reported previously. Notable findings include fibrinopeptide B (1-9); 13 modified, di- or poly-peptides; 11 tobacco-chemical related xenobiotics; glycolysis-gluconeogenesis-tricarboxylic acid (TCA) cycle metabolites (aspartate, glutamate, lactate, α-ketoglutarate, and pyruvate); and four secondary and two primary bile acids that were positively (OR = 1.18-1.58) and five fibrinogen cleavage peptides that were inversely (OR = 0.70-0.84) associated with PDAC. AUCs for combined metabolites-risk factors outperformed known risk factors (p ≤ .01) but not metabolites (p ≥ .31) alone. Systemic metabolism is prospectively associated with PDAC. New metabolite associations include those related to immune response, tobacco, microbiome, glycolysis-gluconeogenesis and TCA cycle, and adiposity or diabetes. The EN selected metabolites were more sensitive indicators of prediagnostic metabolic processes and exposures associated with PDAC than established risk factors.

Global Burden of Pancreatic Cancer Attributable to High Body-Mass Index in 204 Countries and Territories, 1990-2019

(1) Background: This study aimed to assess the global burden of pancreatic cancer attributable to a high BMI in 1990-2019. (2) Methods: An ecological study was carried out. Data about deaths and Disability-Adjusted Life Years (DALYs) for pancreatic cancer were extracted from the Global Burden of Disease (GBD) study. The age-standardized rates (ASRs, per 100,000) were presented. In order to determine trends of pancreatic cancer burden, joinpoint regression analysis was used to calculate the average annual percent change (AAPC). (3) Results: The highest ASRs of DALYs of pancreatic cancer were found in the United Arab Emirates (47.5 per 100,000), followed by countries with about 25.0 per 100,000 (such as Hungary, Czechia, and Montenegro). From 1990 to 2019, the ASRs of deaths and DALYs of pancreatic cancer attributable to a high BMI significantly increased (p < 0.001) for both sexes in all ages, and across all SDI quintiles and all GBD regions. The highest fraction of DALYs attributable to a high BMI was found in the United States of America and China (equally about 15.0%), followed by the Russian Federation, India, Germany, and Brazil (about 5.0%, equally). (4) Conclusions: Further analytical epidemiological studies are necessary to elucidate the relationship between pancreatic cancer and a high BMI.

Robust Descriptor of Pancreatic Tissue for Automatic Detection of Pancreatic Cancer in Endoscopic Ultrasonography

Pancreatic cancer (PC) has a reported mortality of 98% and a 5-y survival rate of 6.7%. Experienced gastroenterologists detect 80% of those with early-stage PC by endoscopic ultrasonography (EUS). Here we propose an automatic second reader strategy to detect PC in an entire EUS procedure, rather than focusing on pre-selected frames, as the state-of-the-art methods do. The method unmasks echo tumoral patterns in frames with a high probability of tumor. First, speeded up robust features define a set of interest points with correlated heterogeneities among different filtering scales. Afterward, intensity gradients of each interest point are summarized by 64 features at certain locations and scales. A frame feature vector is built by concatenating statistics of each feature of the 15 groups of scales. Then, binary classification is performed by Support Vector Machine and Adaboost models. Evaluation was performed using a data set comprising 55 participants, 18 of PC class (16,585 frames) and 37 subjects of non-PC class (49,664 frames), randomly splitting 10 times. The proposed method reached an accuracy of 92.1%, sensitivity of 96.3% and specificity of 87.8.3%. The observed results are also stable in noisy experiments while deep learning approaches fail to maintain similar performance.

Risk of malignancy associated with the diagnostic categories proposed by the Papanicolaou Society of Cytopathology for pancreaticobiliary specimens: An institutional experience

BACKGROUND

The guidelines published by the Papanicolaou Society of Cytopathology (PSC) intend to unify the reporting language in pancreaticobiliary specimens and improve communication between cytopathologists and clinicians. The six categories in the system will determine the best management for patients. However, there is limited evidence regarding the risk of malignancy (ROM) associated with each category.

METHODS

A retrospective search was performed for pancreaticobiliary fine-needle aspiration (FNA) reports with corresponding surgical follow-up. Cases were reclassified according to the PSC. The ROM, sensitivity, specificity, positive predictive value, and negative predictive value were calculated for each category.

RESULTS

A total of 297 cases were identified and reclassified as: 30 nondiagnostic (category I), 45 negative for malignancy (II), 20 atypical (III), 42 neoplastic: other (IVB), 19 suspicious for malignancy (V), and 141 malignant (VI). The absolute ROM was 10% for category I, 8.9% for category II, 60% for category III, 4.8% for category IV when the neoplasms were not characterized as malignant, and 100% when categorized as malignant; 100% for category V, and 95.7% for category VI. Sensitivity, specificity, positive predictive value, and negative predictive value for neoplasia and malignancy, including categories IV to VI, were 96.6%, 88.4%, 97.5%, and 84.4%, respectively.

CONCLUSIONS

The categories developed by the PSC stratify the ROM. Aspirates designated as categories V and VI had the highest ROM. Our rate of atypical category complies with the recommended rate of <10%. This scheme provides valuable information to clinicians treating patients with pancreatic lesions.

A 584 bp deletion in CTRB2 inhibits chymotrypsin B2 activity and secretion and confers risk of pancreatic cancer

Genome-wide association studies (GWASs) have discovered 20 risk loci in the human genome where germline variants associate with risk of pancreatic ductal adenocarcinoma (PDAC) in populations of European ancestry. Here, we fine-mapped one such locus on chr16q23.1 (rs72802365, p = 2.51 × 10-17, OR = 1.36, 95% CI = 1.31-1.40) and identified colocalization (PP = 0.87) with aberrant exon 5-7 CTRB2 splicing in pancreatic tissues (pGTEx = 1.40 × 10-69, βGTEx = 1.99; pLTG = 1.02 × 10-30, βLTG = 1.99). Imputation of a 584 bp structural variant overlapping exon 6 of CTRB2 into the GWAS datasets resulted in a highly significant association with pancreatic cancer risk (p = 2.83 × 10-16, OR = 1.36, 95% CI = 1.31-1.42), indicating that it may underlie this signal. Exon skipping attributable to the deletion (risk) allele introduces a premature stop codon in exon 7 of CTRB2, yielding a truncated chymotrypsinogen B2 protein that lacks chymotrypsin activity, is poorly secreted, and accumulates intracellularly in the endoplasmic reticulum (ER). We propose that intracellular accumulation of a nonfunctional chymotrypsinogen B2 protein leads to ER stress and pancreatic inflammation, which may explain the increased pancreatic cancer risk in carriers of CTRB2 exon 6 deletion alleles.

The Landscape of Genetic Alterations Stratified Prognosis in Oriental Pancreatic Cancer Patients

Background

Pancreatic cancer is a life-threatening malignant disease with significant diversity among geographic regions and races leading to distinct carcinogenesis and prognosis. Previous studies mainly focused on Western patients, while the genomic landscape of Oriental patients, especially Chinese, remained less investigated.

Methods

A total of 408 pancreatic cancer patients were enrolled. A panel containing 436 cancer-related genes was used to detect genetic alterations in tumor samples.

Results

We profiled the genomic alteration landscape of pancreatic duct adenocarcinoma (PDAC), intraductal papillary mucinous neoplasm (IPMN), periampullary carcinoma (PVC), and solid-pseudopapillary tumor (SPT). Comparison with a public database revealed specific gene mutations in Oriental PDAC patients including higher mutation rates of DNA damage repair-related genes. Analysis of mutational signatures showed potential heterogenous carcinogenic factors caused by diabetes mellitus. KRAS mutation, especially KRAS G12D mutation, was associated with poor survival, while patients not harboring the 17 significant copy number variations (CNVs) had a better prognosis. We further identified multiple correlations between clinicopathologic variables and genetic mutations, as well as CNVs. Finally, by network-based stratification, three classes of PDAC patients were robustly clustered. Among these, class 1 (characterized by the Fanconi anemia pathway) achieved the best outcome, while class 2 (involved in the platinum drug resistance pathway) suffered from the worst prognosis.

Conclusions

In this study, we reported for the first time the genetic alteration landscape of Oriental PDAC patients identifying many Oriental-specific alterations. The relationship between genetic alterations and clinicopathological factors as well as prognosis demonstrated important genomic impact on tumor biology. This study will help to optimize clinical treatment of Oriental PDAC patients and improve their survival.

Associations between metabolites and pancreatic cancer risk in a large prospective epidemiological study

OBJECTIVE

To assess whether prediagnostic metabolites were associated with incident pancreatic ductal adenocarcinoma (PDAC) in a prospective cohort study.

DESIGN

We conducted an untargeted analysis of 554 known metabolites measured in prediagnostic serum (up to 24 years) to determine their association with incident PDAC in a nested case-control study of male smokers (372 matched case-control sets) and an independent nested case-control study that included women and non-smokers (107 matched sets). Metabolites were measured using Orbitrap Elite or Q-Exactive high-resolution/accurate mass spectrometers. Controls were matched to cases by age, sex, race, date of blood draw, and follow-up time. We used conditional logistic regression adjusted for age to calculate ORs and 95% CIs for a 1 SD increase in log-metabolite level separately in each cohort and combined the two ORs using a fixed-effects meta-analysis.

RESULTS

Thirty-one metabolites were significantly associated with PDAC at a false discovery rate <0.05 with 12 metabolites below the Bonferroni-corrected threshold (p<9.04×10^-5). Similar associations were observed in both cohorts. The dipeptides glycylvaline, aspartylphenylalanine, pyroglutamylglycine, phenylalanylphenylalanine, phenylalanylleucine and tryptophylglutamate and amino acids aspartate and glutamate were positively while the dipeptides tyrosylglutamine and α-glutamyltyrosine, fibrinogen cleavage peptide DSGEGDFXAEGGGVR and glutathione-related amino acid cysteine-glutathione disulfide were inversely associated with PDAC after Bonferroni correction. Five top metabolites demonstrated significant time-varying associations (p<0.023) with the strongest associations observed 10-15 years after participants' blood collection and attenuated thereafter.

CONCLUSION

Our results suggest that prediagnostic metabolites related to subclinical disease, γ-glutamyl cycle metabolism and adiposity/insulin resistance are associated with PDAC.

A Transcriptome-Wide Association Study Identifies Novel Candidate Susceptibility Genes for Pancreatic Cancer

BACKGROUND

Although 20 pancreatic cancer susceptibility loci have been identified through genome-wide association studies in individuals of European ancestry, much of its heritability remains unexplained and the genes responsible largely unknown.

METHODS

To discover novel pancreatic cancer risk loci and possible causal genes, we performed a pancreatic cancer transcriptome-wide association study in Europeans using three approaches: FUSION, MetaXcan, and Summary-MulTiXcan. We integrated genome-wide association studies summary statistics from 9040 pancreatic cancer cases and 12 496 controls, with gene expression prediction models built using transcriptome data from histologically normal pancreatic tissue samples (NCI Laboratory of Translational Genomics [n = 95] and Genotype-Tissue Expression v7 [n = 174] datasets) and data from 48 different tissues (Genotype-Tissue Expression v7, n = 74-421 samples).

RESULTS

We identified 25 genes whose genetically predicted expression was statistically significantly associated with pancreatic cancer risk (false discovery rate < .05), including 14 candidate genes at 11 novel loci (1p36.12: CELA3B; 9q31.1: SMC2, SMC2-AS1; 10q23.31: RP11-80H5.9; 12q13.13: SMUG1; 14q32.33: BTBD6; 15q23: HEXA; 15q26.1: RCCD1; 17q12: PNMT, CDK12, PGAP3; 17q22: SUPT4H1; 18q11.22: RP11-888D10.3; and 19p13.11: PGPEP1) and 11 at six known risk loci (5p15.33: TERT, CLPTM1L, ZDHHC11B; 7p14.1: INHBA; 9q34.2: ABO; 13q12.2: PDX1; 13q22.1: KLF5; and 16q23.1: WDR59, CFDP1, BCAR1, TMEM170A). The association for 12 of these genes (CELA3B, SMC2, and PNMT at novel risk loci and TERT, CLPTM1L, INHBA, ABO, PDX1, KLF5, WDR59, CFDP1, and BCAR1 at known loci) remained statistically significant after Bonferroni correction.

CONCLUSIONS

By integrating gene expression and genotype data, we identified novel pancreatic cancer risk loci and candidate functional genes that warrant further investigation.

Genetic Alterations Featuring Biological Models to Tailor Clinical Management of Pancreatic Cancer Patients

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death worldwide. This high mortality rate is due to the disease's lack of symptoms, resulting in a late diagnosis. Biomarkers and treatment options for pancreatic cancer are also limited. In order to overcome this, new research models and novel approaches to discovering PDAC biomarkers are required. In this review, we outline the hereditary and somatic causes of PDAC and provide an overview of the recent genome wide association studies (GWAS) and pathway analysis studies. We also provide a summary of some of the systems used to study PDAC, including established and primary cell lines, patient-derived xenografts (PDX), and newer models such as organoids and organ-on-chip. These ex vitro laboratory systems allow for critical research into the development and progression of PDAC.

FAM84B, amplified in pancreatic ductal adenocarcinoma, promotes tumorigenesis through the Wnt/β-catenin pathway

Altered expression of family with sequence similarity 84, member B (FAM84B) has been found in various human cancers. However, the expression and function of FAM84B in pancreatic ductal adenocarcinoma (PDAC) has not been studied. Here, by analyzing The Cancer Genome Atlas cohort, we found that FAM84B amplification was observed in 11% of 141 PDAC patients, and FAM84B amplification was correlated with higher mRNA expression of FAM84B. FAM84B amplification and overexpression was significantly correlated with poor overall survival. Moreover, knockdown of FAM84B in PDAC cell lines suppressed cell proliferation and induced apoptosis. FAM84B knockdown also suppressed mitochondrial function and glycolysis of PDAC cells. Interestingly, knockdown of FAM84B decreased the nuclear accumulation of β-catenin, and the expression of c-Myc and lactate dehydrogenase A, but enhanced the expression of Survivin. On the contrary, FAM84B overexpression displayed reversed effects in cell proliferation, apoptosis, mitochondrial function, and glycolysis, which was blocked by the Wnt/β-catenin pathway inhibitor (XAV939). In addition, PDAC cells with lower expression of FAM84B were more sensitive to gemcitabine-induced cell proliferation inhibition both in vitro and in vivo. In conclusion, FAM84B plays an important role in aerobic glycolysis and tumorigenesis in PDAC and Wnt/β-catenin may be involved in this process.

Modelling of pancreatic cancer biology: transcriptomic signature for 3D PDX-derived organoids and primary cell line organoid development

With a five-year survival rate of 9%, pancreatic ductal adenocarcinoma (PDAC) is the deadliest of all cancers. The rapid mortality makes PDAC difficult to research, and inspires a resolve to create reliable, tractable cellular models for preclinical cancer research. Organoids are increasingly used to model PDAC as they maintain the differentiation status, molecular and genomic signatures of the original tumour. In this paper, we present novel methodologies and experimental approaches to develop PDAC organoids from PDX tumours, and the simultaneous development of matched primary cell lines. Moreover, we also present a method of recapitulating primary cell line cultures to organoids (CLOs). We highlight the usefulness of CLOs as PDAC organoid models, as they maintain similar transcriptomic signatures as their matched patient-derived organoids and patient derived xenografts (PDX)s. These models provide a manageable, expandable in vitro resource for downstream applications such as high throughput screening, functional genomics, and tumour microenvironment studies.

Emerging incidence trends and application of curative treatments of pancreatic cancer in the USA

Annual pancreatic tumor incidence rates have been increasing. We explored pancreatic tumor incidence trends by treatment and clinicopathologic features.Data from the Surveillance, Epidemiology and End Results (SEER) was retrieved to evaluate temporal trends and pancreatic cancer rates from 2000 to 2015. Joinpoint regression analyses were carried out to examine trend differences.Overall, the incidence of pancreatic cancer was on the increase. The initial APC increased at a rate of 2.22% from 2000 to 2012, and increased from 2012 to 2015 at a rate of 9.05%. Joinpoint analyses revealed that trends within different demographics of pancreatic cancer showed different characteristics. The rate of pancreatic cancer also varied with histologic types. In addition, the trends by cancer stage showed significant increase incidences of stage I and II pancreatic cancer from 2000 to 2013 (stage I: APC: 2.71%; stage II: APC: 4.87%). Incidences of patients receiving surgery increased from 2000 to 2008 (APC: 7.55%), 2008 to 2011 (APC: 2.17%) and then there was a significant acceleration from 2011 to 2015 (APC: 10.51%). The incidence of cases in stage II receiving surgery increased significantly from 2004 to 2009 (APC: 9.28%) and 2009 to 2013 (APC: 2.57%). However, for cases in stage I, the incidence of cases with surgery decreased significantly since 2009 (APC: -4.14%). Patients undergoing surgical treatment without chemotherapy and radiotherapy had the higher rates compared with those who received other combined treatments.Pancreatic cancer has been increasing overall, but patterns differ by demographics and clinicopathologic features. Efforts to identify and treat more eligible candidates for curative therapy could be beneficial.

Potential functional variants in SMC2 and TP53 in the AURORA pathway genes and risk of pancreatic cancer

The AURORA pathway participates in mitosis and cell division, and alterations in mitosis and cell division can lead to carcinogenesis. Therefore, genetic variants in the AURORA pathway genes may be associated with susceptibility to pancreatic cancer. To test this hypothesis, we used three large publically available pancreatic cancer genome-wide association study (GWAS) datasets (PanScan I, II/III and PanC4) to assess the associations of 7168 single nucleotide polymorphisms (SNPs) in a set of 62 genes of this pathway with pancreatic cancer risk in 8477 cases and 6946 controls of European ancestry. We identify 15 significant pancreatic cancer risk-associated SNPs in three genes (SMC2, ARHGEF7 and TP53) after correction for multiple comparisons by a false discovery rate < 0.20. Through further linkage disequilibrium analysis, SNP functional prediction and stepwise logistic regression analysis, we focused on three SNPs: rs3818626 in SMC2, rs79447092 in ARHGEF7 and rs9895829 in TP53. We found that these three SNPs were associated with pancreatic cancer risk [odds ratio (OR) = 1.12, 95% confidence interval (CI) = 1.07-1.17 and P = 2.20E-06 for the rs3818626 C allele; OR = 0.76, CI = 0.66-0.88 and P = 1.46E-04 for the rs79447092 A allele and OR = 0.82, CI = 0.74-0.91 and P = 1.51E-04 for the rs9895829 G allele]. Their joint effect as the number of protective genotypes also showed a significant association with pancreatic cancer risk (trend test P ≤ 0.001). Finally, we performed an expression quantitative trait loci analysis and found that rs3818626 and rs9895829 were significantly associated with SMC2 and TP53 messenger RNA expression levels in 373 lymphoblastoid cell lines, respectively. In conclusion, these three representative SNPs may be potentially susceptibility loci for pancreatic cancer and warrant additional validation.

Agnostic Pathway/Gene Set Analysis of Genome-Wide Association Data Identifies Associations for Pancreatic Cancer

BACKGROUND

Genome-wide association studies (GWAS) identify associations of individual single-nucleotide polymorphisms (SNPs) with cancer risk but usually only explain a fraction of the inherited variability. Pathway analysis of genetic variants is a powerful tool to identify networks of susceptibility genes.

METHODS

We conducted a large agnostic pathway-based meta-analysis of GWAS data using the summary-based adaptive rank truncated product method to identify gene sets and pathways associated with pancreatic ductal adenocarcinoma (PDAC) in 9040 cases and 12 496 controls. We performed expression quantitative trait loci (eQTL) analysis and functional annotation of the top SNPs in genes contributing to the top associated pathways and gene sets. All statistical tests were two-sided.

RESULTS

We identified 14 pathways and gene sets associated with PDAC at a false discovery rate of less than 0.05. After Bonferroni correction (P ≤ 1.3 × 10-5), the strongest associations were detected in five pathways and gene sets, including maturity-onset diabetes of the young, regulation of beta-cell development, role of epidermal growth factor (EGF) receptor transactivation by G protein-coupled receptors in cardiac hypertrophy pathways, and the Nikolsky breast cancer chr17q11-q21 amplicon and Pujana ATM Pearson correlation coefficient (PCC) network gene sets. We identified and validated rs876493 and three correlating SNPs (PGAP3) and rs3124737 (CASP7) from the Pujana ATM PCC gene set as eQTLs in two normal derived pancreas tissue datasets.

CONCLUSION

Our agnostic pathway and gene set analysis integrated with functional annotation and eQTL analysis provides insight into genes and pathways that may be biologically relevant for risk of PDAC, including those not previously identified.

Epidemiology and burden of pancreatic cancer

Pancreatic cancer, although infrequent, has a very poor prognosis, making it currently the fourth common causes of cancer mortality in most developed countries including the European Union (EU). Its incidence varies across regions, which suggests that lifestyle factors play an important role in its etiology, although part of the variation could be ascribed to difference in diagnostic and coding practices. Because pancreatic cancer is strongly age-dependent, increasing population longevity and ageing will lead to an increase of the global burden of pancreatic cancer. It was estimated that, by 2040, the total number of cases in the EU will increase by more than 30%. Pancreatic cancer is a multifactorial disease and many risk factors have been identified. Hereditary factors are responsible for less than 10% of the cases while tobacco smoking and excess body weight, the two most important potentially modifiable risk factors, are responsible for 10 to 30% of the cases, affording a unique opportunity for preventing one of our deadliest cancers.

Pancreatic cancer incidence trends: evidence from the Surveillance, Epidemiology and End Results (SEER) population-based data

Background

Annual pancreatic cancer incidence rates have been increasing. We examine pancreatic cancer incidence trends by demographics and histologic type.

Methods

Data from the Surveillance, Epidemiology and End Results (SEER) registries were available to assess temporal trends and pancreatic cancer rates from 1974 to 2013.

Results

Pancreatic cancer incidence rates declined between the 1970s and 1990s but increased from 1994 to 2013 among White males. Among non-Hispanic White and Hispanic males, the annual percent change (APC) in incidence between 1992 and 2013 was 0.84% and 0.73%, respectively. Rates also rose among White non-Hispanic, Hispanic and Asian females (APC = 0.81%, 0.56% and 1.23%, respectively) and even more rapidly among females aged 25-34 years (APC > 2.5%). Rates among Black males and females remained unchanged, but higher compared with the other racial/ethnic groups. By histologic type, the increases were greatest for non-secretory endocrine cancers ( > 6%), followed by ductal adenocarcinomas (∼5%) and adenocarcinoma, NOS (∼1.4%)-the largest histologic subgroup of pancreatic cancer. Rates for mucinous adenocarcinomas and poorly specified pancreatic cancer decreased. Overall, incidence rates during 2000-13 were higher among males than females [MF incidence rate ratio (IRR) = 1.28]. The IRR was >1.00 at all ages ≥ 35, but rates among females were higher at younger ages (IRRs 15-24: 0.66, 25-34: 0.81). The MF IRRs for most of the histologic types were elevated among males apart from solid pseudopapillary adenocarcinoma and cystic carcinomas (IRR = 0.22, confidence interval: 0.14-0.34 and 0.52, 0.41-0.65, respectively).

Conclusion

Pancreatic cancer has been increasing overall, but patterns differ by demographic group and histologic type. Many of the trends parallel changing prevalence of lifestyle risk factors such as smoking, overweight and obesity, and diabetes in the USA, particularly for pancreatic adenocarcinoma, and improved diagnosis methods during the past 40 years.

Genetic variants in the platelet-derived growth factor subunit B gene associated with pancreatic cancer risk

The platelet-derived growth factor (PDGF) signaling pathway plays important roles in development and progression of human cancers. In our study, we aimed to identify genetic variants of the PDGF pathway genes associated with pancreatic cancer (PC) risk in European populations using three published genome-wide association study datasets, which consisted of 9,381 cases and 7,719 controls. The expression quantitative trait loci (eQTL) analysis was also performed using data from the 1000 Genomes, TCGA and GTEx projects. As a result, we identified two potential susceptibility loci (rs5757573 and rs6001516) of PDGFB associated with PC risk [odds ratio (OR) = 1.10, 95% confidence interval (CI) = 1.05-1.16, and p = 4.70 × 10-5 for the rs5757573 C allele and 1.21, 1.11-1.32, and 2.01 × 10-5 for the rs6001516 T allele]. Haplotype analysis revealed that the C-T haplotype carriers had a significantly increased risk of PC than those carrying the T-C haplotype (OR = 1.23, 95% CI = 1.12-1.34, p =5.00 × 10-6 ). The multivariate regression model incorporating the number of unfavorable genotypes (NUGs) with age and sex showed that carriers with 1-2 NUGs, particularly among 60-70 age group or males, had an increased risk of PC, compared to those without NUG. Furthermore, the eQTL analysis revealed that both loci were correlated with a decreased mRNA expression level of PDGFB in lymphoblastoid cell lines and pancreatic tumor tissues (p = 0.015 and 0.071, respectively). Our results suggest that genetic variants in PDGFB may play a role in susceptibility to PC. Further population and functional validations of our findings are warranted.

Characterising cis-regulatory variation in the transcriptome of histologically normal and tumour-derived pancreatic tissues

OBJECTIVE

To elucidate the genetic architecture of gene expression in pancreatic tissues.

DESIGN

We performed expression quantitative trait locus (eQTL) analysis in histologically normal pancreatic tissue samples (n=95) using RNA sequencing and the corresponding 1000 genomes imputed germline genotypes. Data from pancreatic tumour-derived tissue samples (n=115) from The Cancer Genome Atlas were included for comparison.

RESULTS

We identified 38 615 cis-eQTLs (in 484 genes) in histologically normal tissues and 39 713 cis-eQTL (in 237 genes) in tumour-derived tissues (false discovery rate <0.1), with the strongest effects seen near transcriptional start sites. Approximately 23% and 42% of genes with significant cis-eQTLs appeared to be specific for tumour-derived and normal-derived tissues, respectively. Significant enrichment of cis-eQTL variants was noted in non-coding regulatory regions, in particular for pancreatic tissues (1.53-fold to 3.12-fold, p≤0.0001), indicating tissue-specific functional relevance. A common pancreatic cancer risk locus on 9q34.2 (rs687289) was associated with ABO expression in histologically normal (p=5.8×10-8) and tumour-derived (p=8.3×10-5) tissues. The high linkage disequilibrium between this variant and the O blood group generating deletion variant in ABO (exon 6) suggested that nonsense-mediated decay (NMD) of the 'O' mRNA might explain this finding. However, knockdown of crucial NMD regulators did not influence decay of the ABO 'O' mRNA, indicating that a gene regulatory element influenced by pancreatic cancer risk alleles may underlie the eQTL.

CONCLUSIONS

We have identified cis-eQTLs representing potential functional regulatory variants in the pancreas and generated a rich data set for further studies on gene expression and its regulation in pancreatic tissues.

Genome-wide meta-analysis identifies five new susceptibility loci for pancreatic cancer

In 2020, 146,063 deaths due to pancreatic cancer are estimated to occur in Europe and the United States combined. To identify common susceptibility alleles, we performed the largest pancreatic cancer GWAS to date, including 9040 patients and 12,496 controls of European ancestry from the Pancreatic Cancer Cohort Consortium (PanScan) and the Pancreatic Cancer Case-Control Consortium (PanC4). Here, we find significant evidence of a novel association at rs78417682 (7p12/TNS3, P = 4.35 × 10-8). Replication of 10 promising signals in up to 2737 patients and 4752 controls from the PANcreatic Disease ReseArch (PANDoRA) consortium yields new genome-wide significant loci: rs13303010 at 1p36.33 (NOC2L, P = 8.36 × 10-14), rs2941471 at 8q21.11 (HNF4G, P = 6.60 × 10-10), rs4795218 at 17q12 (HNF1B, P = 1.32 × 10-8), and rs1517037 at 18q21.32 (GRP, P = 3.28 × 10-8). rs78417682 is not statistically significantly associated with pancreatic cancer in PANDoRA. Expression quantitative trait locus analysis in three independent pancreatic data sets provides molecular support of NOC2L as a pancreatic cancer susceptibility gene.

Triptonide potently suppresses pancreatic cancer cell-mediated vasculogenic mimicry by inhibiting expression of VE-cadherin and chemokine ligand 2 genes

Various aggressive cancers, including pancreatic cancer, produce functional blood vessels by neovascularization. Tumor vasculogenic mimicry (VM) promotes cancer progression and is closely associated with the poor prognosis of the cancer patients. Therefore, tumor VM is a sensible target for novel anti-cancer drug discovery. However, there is a lack of effective anti-tumor VM drugs in the clinical setting. In this study, we aim to explore novel agents to effectually inhibit pancreatic cancer cell-mediated tumor VM for anti-cancer therapy. Pancreatic cancer cell lines Patu8988 and Panc1 were utilized as a model. A mouse model was used for in vitro capillary-like structure formation and in vivo Matrigel plug assays to evaluate the anti-tumor VM efficacy of a small molecule triptonide from traditional Chinese herbs. Various methods, including RT-PCR, immunohistochemical staining, and the luciferase gene transcription reporter system, were applied to study the mechanisms of triptonide-exerted anti-tumor VM. Triptonide effectively inhibited pancreatic cancer cell-formed capillary-like structures in vitro and blood vessels in vivo through suppressing pancreatic cancer cell migration, invasion, and VM via inhibiting expression of tumor VM master gene VE-cadherin and pro-migratory gene chemokine C-X-C motif ligand 2 (CXCL2), mainly via reduction of gene promoter activity. Triptonide potently suppresses pancreatic cancer cell-mediated VM by reducing tumor cell migration and invasion and inhibiting expression of VE-cadherin and CXCL2 genes. Our results provide a novel and potent anti-tumor VM drug candidate for further development of effective anti-pancreatic cancer therapy.

Childhood body mass index and risk of adult pancreatic cancer

BACKGROUND

Excess weight in adulthood is one of the few modifiable risk factors for pancreatic cancer, and height has associations as well. This leads to question whether body weight and height in childhood are associated with adult pancreatic cancer.

OBJECTIVE

To examine if childhood body mass index (BMI; kg/m2) and height are associated with pancreatic cancer in adult life.

METHODS

We linked 293,208 children born from 1930-1982 in the Copenhagen School Health Records Register who had measured values of weights and heights at ages 7-13 years with the Danish Cancer Registry to identify incident pancreatic cancer cases from 1968-2012. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazard regressions.

RESULTS

During 8,207,015 person-years of follow-up, 1,268 pancreatic cancer cases were diagnosed. Childhood BMI z-scores at ages 7-13 years were positively and significantly associated with pancreatic cancer in men and women up to age 70 years; beyond age 70 the associations diminished. The HRs of pancreatic cancer were 1.13 (95% CI: 1.05-1.21) and 1.18 (95% CI: 1.09-1.27) per BMI z-score at ages 7 and 13 years, respectively. A BMI ≥1.5 z-score at ages 7, 10 and 13 years was positively and significantly associated with pancreatic cancer; however, the effect did not differ from having a BMI z-score ≥1.5 at only one of these ages. Positive, albeit non-statistically significant, associations were identified with height.

CONCLUSIONS

BMI at all ages from 7-13 years is positively and linearly associated with adult pancreatic cancer; the higher the BMI, the higher the risk. Excess childhood BMI may be indicative of processes initiated early in life that lead to this cancer. Prevention of childhood adiposity may decrease the burden of pancreatic cancer in adults.

Three new pancreatic cancer susceptibility signals identified on chromosomes 1q32.1, 5p15.33 and 8q24.21

Genome-wide association studies (GWAS) have identified common pancreatic cancer susceptibility variants at 13 chromosomal loci in individuals of European descent. To identify new susceptibility variants, we performed imputation based on 1000 Genomes (1000G) Project data and association analysis using 5,107 case and 8,845 control subjects from 27 cohort and case-control studies that participated in the PanScan I-III GWAS. This analysis, in combination with a two-staged replication in an additional 6,076 case and 7,555 control subjects from the PANcreatic Disease ReseArch (PANDoRA) and Pancreatic Cancer Case-Control (PanC4) Consortia uncovered 3 new pancreatic cancer risk signals marked by single nucleotide polymorphisms (SNPs) rs2816938 at chromosome 1q32.1 (per allele odds ratio (OR) = 1.20, P = 4.88x10 -15), rs10094872 at 8q24.21 (OR = 1.15, P = 3.22x10 -9) and rs35226131 at 5p15.33 (OR = 0.71, P = 1.70x10 -8). These SNPs represent independent risk variants at previously identified pancreatic cancer risk loci on chr1q32.1 ( NR5A2), chr8q24.21 ( MYC) and chr5p15.33 ( CLPTM1L- TERT) as per analyses conditioned on previously reported susceptibility variants. We assessed expression of candidate genes at the three risk loci in histologically normal ( n = 10) and tumor ( n = 8) derived pancreatic tissue samples and observed a marked reduction of NR5A2 expression (chr1q32.1) in the tumors (fold change -7.6, P = 5.7x10 -8). This finding was validated in a second set of paired ( n = 20) histologically normal and tumor derived pancreatic tissue samples (average fold change for three NR5A2 isoforms -31.3 to -95.7, P = 7.5x10 -4-2.0x10 -3). Our study has identified new susceptibility variants independently conferring pancreatic cancer risk that merit functional follow-up to identify target genes and explain the underlying biology.

Pancreatic cancer biology and genetics from an evolutionary perspective

Cancer is an evolutionary disease, containing the hallmarks of an asexually reproducing unicellular organism subject to evolutionary paradigms. Pancreatic ductal adenocarcinoma (hereafter referred to as pancreatic cancer) is a particularly robust example of this phenomenon. Genomic features indicate that pancreatic cancer cells are selected for fitness advantages when encountering the geographic and resource-depleted constraints of the microenvironment. Phenotypic adaptations to these pressures help disseminated cells to survive in secondary sites, a major clinical problem for patients with this disease. In this Review we gather the wide-ranging aspects of pancreatic cancer research into a single concept rooted in Darwinian evolution, with the goal of identifying novel insights and opportunities for study.