Familial and sporadic pancreatic cancer share the same molecular pathogenesis

Skeletal Muscle-Derived Irisin Enhances Gemcitabine Sensitivity and Suppresses Migration Ability in Pancreatic Ductal Adenocarcinoma

BACKGROUND

High skeletal muscle mass might be a prognostic factor for patients with pancreatic ductal adenocarcinoma (PDAC); however, the underlying reason is unclear. We hypothesized that myokines, which are cytokines secreted by the skeletal muscle, function as suppressors of PDAC. We specifically examined irisin, a myokine, which plays a critical role in the modulation of metabolism, to clarify the anticancer mechanisms.

METHODS

First, the effect of the conditioned medium (CM) from skeletal muscle cells and from irisin-knockdown skeletal muscle cells on PDAC cell lines was evaluated. We then investigated the effects and anticancer mechanism of irisin in PDAC cells, and evaluated the anticancer effect of recombinant irisin in a PDAC xenograft mouse model. Finally, patients undergoing pancreatic resection for PDAC were divided into two groups based on their serum irisin level, and the long-term outcomes were evaluated.

RESULTS

The CM enhanced gemcitabine sensitivity by inducing apoptosis and decreasing cell migration by inhibiting epithelial-mesenchymal transition (EMT) in PDAC cell lines. The CM derived from irisin-knockdown skeletal muscle cells did not affect the PDAC cell lines. The addition of recombinant irisin to PDAC cell lines facilitated sensitivity to gemcitabine by inhibiting the mitogen-activated protein kinase (MAPK) pathway, and decreased migration by inhibiting EMT via the transforming growth factor-β/SMAD pathway. Xenografts injected with gemcitabine and recombinant irisin grew slower than the xenografts injected with gemcitabine alone. The overall survival was prolonged in the high-irisin group compared with that in the low-irisin group.

CONCLUSIONS

Skeletal muscle-derived irisin may affect PDAC by enhancing its sensitivity to gemcitabine and suppressing EMT.

Familial and hereditary pancreatic cancer in Japan

As in Western countries, familial pancreatic cancer accounts for 5-7% of pancreatic cancer (PC) in Japan. Opportunities for diagnosing hereditary pancreatic cancer (HPC) are increasing owing to the coverage of companion diagnostics and cancer genomic profiling by national health insurance in patients with unresectable or recurrent PC refractory to standard chemotherapies. HPC is recognized in 7% of PCs and 15% of familial pancreatic cancer, including germline variants of BRCA1/2, ATM, PALB2, APC, and mismatch repair genes. Individuals with 5-fold or greater inherited risks of PC are recommended to undergo pancreatic surveillance according to Japanese guidelines. The imaging modalities for this surveillance include endoscopic ultrasound, magnetic resonance cholangiopancreatography, abdominal ultrasound, and enhanced computed tomography. Currently, a nationwide prospective surveillance study is ongoing in Japan. Platinum-based chemotherapy is an effective pancreatic cancer treatment in patients with variants of homologous recombination repair genes (BRCA1/2 and PALB2); however, the use of platinum regimens solely based on familial/personal cancer history remains controversial. The efficacy of olaparib maintenance therapy, as confirmed by the POLO study, has significantly impacted the clinical treatment of advanced PC patients in Japan. Since the initiation of precision cancer medicine in 2019, genetic medicine for PC patients has expanded in Japan.

Laterality influence on gene expression of DNA damage repair in colorectal cancer

Colorectal carcinoma (CRC) is the third most common malignancy worldwide, and second in number of deaths in the world. The molecular pathogenesis of CRC is heterogeneous and can affect several genes. Moreover, genomic instability is recognized as an important part of CRC carcinogenesis and is tightly connected to DNA damage response. DNA damage repair (DDR) pathways are intrinsically associated with cancer development and establishment. Traditionally, CRC is considered as one coherent disease, however, new evidence shows that left and right-sided CRC present differences observed in clinical settings, as well as in pre-clinical studies. Therefore, this study aimed to investigate the impact of DDR transcriptional profiles on survival in different sublocations of the colon and rectum using Cox regression, survival analysis and differential gene expression. Right side colon (RSC) has DDR genes' expression associated only with higher risk of death, while left side colon (LSC) and Rectum have most genes' expression associated with lower risk. The pattern is the same with survival analysis. All significant DDR genes had lower expression associated with better survival in RSC, as opposed to LSC and Rectum. Our results demonstrate that RSC is distinctively different from LSC and Rectum. LSC and Rectum have similar DDR expression profiles.

Advances in the Early Diagnosis of Pancreatic Ductal Adenocarcinoma and Premalignant Pancreatic Lesions

Pancreatic cancer is one of the most lethal human malignancies, in part because it is often diagnosed at late stages when surgery and systemic therapies are either unfeasible or ineffective. Therefore, diagnosing pancreatic cancer in earlier stages is important for effective treatment. However, because the signs and symptoms may be nonspecific and not apparent until the disease is at a late stage, the timely diagnoses of pancreatic cancer can be difficult to achieve. Recent studies have shown that selective screening and increased usage of biomarkers could improve the early diagnosis of pancreatic cancer. In this review, we discuss recent advancements in the early detection of pancreatic ductal carcinoma and precancerous lesions. These include innovations in imaging modalities, the diagnostic utility of various biomarkers, biopsy techniques, and population-based surveillance approaches. Additionally, we discuss how machine learning methods are being applied to develop integrated methods of identifying individuals at high risk of developing pancreatic disease. In the future, the overall survival of pancreatic cancer patients could be improved by the development and adoption of these new methods and techniques.

Hyperglycaemia induces metabolic reprogramming into a glycolytic phenotype and promotes epithelial-mesenchymal transitions via YAP/TAZ-Hedgehog signalling axis in pancreatic cancer

BACKGROUND

Hyperglycaemia is a well-known initial symptom in patients with pancreatic ductal adenocarcinoma (PDAC). Metabolic reprogramming in cancer, described as the Warburg effect, can induce epithelial-mesenchymal transition (EMT).

METHODS

The biological impact of hyperglycaemia on malignant behaviour in PDAC was examined by in vitro and in vivo experiments.

RESULTS

Hyperglycaemia promoted EMT by inducing metabolic reprogramming into a glycolytic phenotype via yes-associated protein (YAP)/PDZ-binding motif (TAZ) overexpression, accompanied by GLUT1 overexpression and enhanced phosphorylation Akt in PDAC. In addition, hyperglycaemia enhanced chemoresistance by upregulating ABCB1 expression and triggered PDAC switch into pure basal-like subtype with activated Hedgehog pathway (GLI1 high, GATA6 low expression) through YAP/TAZ overexpression. PDAC is characterised by abundant stroma that harbours tumour-promoting properties and chemoresistance. Hyperglycaemia promotes the production of collagen fibre-related proteins (fibronectin, fibroblast activation protein, COL1A1 and COL11A1) by stimulating YAP/TAZ expression in cancer-associated fibroblasts (CAFs). Knockdown of YAP and/or TAZ or treatment with YAP/TAZ inhibitor (K975) abolished EMT, chemoresistance and a favourable tumour microenvironment even under hyperglycemic conditions in vitro and in vivo.

CONCLUSION

Hyperglycaemia induces metabolic reprogramming into glycolytic phenotype and promotes EMT via YAP/TAZ-Hedgehog signalling axis, and YAP/TAZ could be a novel therapeutic target in PDAC.

Whole-exome Sequencing Reveals New Potential Susceptibility Genes for Japanese Familial Pancreatic Cancer

OBJECTIVE

The primary objective of this study was to identify novel genes that predispose people in the Japanese population to FPC.

SUMMARY OF BACKGROUND DATA

Familial history of pancreatic cancer is an important risk factor but, to date, few genes predisposing individuals to increased risk of developing FPC have been identified.

METHODS

We performed whole-exome sequencing of germline DNA from 81 Japanese FPC patients. We also investigated somatic gene alterations in 21 matched tumor tissues through whole-exome sequencing and copy number analysis.

RESULTS

Our germline variants identified previously known FPC susceptibility genes such as ATM and BRCA2, and several novel tumor suppressor genes with potentially deleterious variants for FPC. Interestingly, somatic whole-exome analysis demonstrated that most tumor samples with suspicious loss of heterozygosity of candidate genes were KRAS wild-types, implying that these cases may not have required KRAS activation as a driver event for carcinogenesis.

CONCLUSIONS

Our findings indicate that FPC patients harbor potentially deleterious causative germline variants in tumor suppressor genes, which are known to acquire somatic mutations in pancreatic cancer, and that somatic loss of heterozygosity of some FPC susceptibility genes may contribute to the development of FPC in the absence of somatic KRAS-activating mutation. Genetic testing for a wider variety of FPC-predisposition genes could provide better screening approach for high-risk groups of pancreatic cancer.

Timeline of Development of Pancreatic Cancer and Implications for Successful Early Detection in High-Risk Individuals

BACKGROUND & AIMS

To successfully implement imaging-based pancreatic cancer (PC) surveillance, understanding the timeline and morphologic features of neoplastic progression is key. We aimed to investigate the progression to neoplasia from serial prediagnostic pancreatic imaging tests in high-risk individuals and identify factors associated with successful early detection.

METHODS

We retrospectively examined the development of pancreatic abnormalities in high-risk individuals who were diagnosed with PC or underwent pancreatic surgery, or both, in 16 international surveillance programs.

RESULTS

Of 2552 high-risk individuals under surveillance, 28 (1%) developed neoplastic progression to PC or high-grade dysplasia during a median follow-up of 29 months after baseline (interquartile range [IQR], 40 months). Of these, 13 of 28 (46%) presented with a new lesion (median size, 15 mm; range 7-57 mm), a median of 11 months (IQR, 8; range 3-17 months) after a prior examination, by which time 10 of 13 (77%) had progressed beyond the pancreas. The remaining 15 of 28 (54%) had neoplastic progression in a previously detected lesion (12 originally cystic, 2 indeterminate, 1 solid), and 11 (73%) had PC progressed beyond the pancreas. The 12 patients with cysts had been monitored for 21 months (IQR, 15 months) and had a median growth of 5 mm/y (IQR, 8 mm/y). Successful early detection (as high-grade dysplasia or PC confined to the pancreas) was associated with resection of cystic lesions (vs solid or indeterminate lesions (odds ratio, 5.388; 95% confidence interval, 1.525-19.029) and small lesions (odds ratio, 0.890/mm; 95% confidence interval 0.812-0.976/mm).

CONCLUSIONS

In nearly half of high-risk individuals developing high-grade dysplasia or PC, no prior lesions are detected by imaging, yet they present at an advanced stage. Progression can occur before the next scheduled annual examination. More sensitive diagnostic tools or a different management strategy for rapidly growing cysts are needed.

Molecular Features and Clinical Management of Hereditary Pancreatic Cancer Syndromes and Familial Pancreatic Cancer

Hereditary pancreatic cancers are caused by several inherited genes. Familial pancreatic cancer is defined as pancreatic cancer arising in a patient with at least two first-degree relatives with pancreatic cancer in the absence of an identified genetic cause. Hereditary pancreatic cancer syndromes and familial pancreatic cancers account for about 10% of pancreatic cancer cases. Germline mutations in BRCA1, BRCA2, ATM, PALB2, CDKN2A, STK11, and TP53 and mismatch repair genes (MLH1, MSH2, MSH6, PMS2, and EPCAM) are among the well-known inherited susceptibility genes. Currently available targeted medications include poly (ADP-ribose) polymerase inhibitors (PARP) for cases with mutant BRCA and immune checkpoint inhibitors for cases with mismatch repair deficiency. Loss of heterozygosity of hereditary pancreatic cancer susceptibility genes such as BRCA1/2 plays a key role in carcinogenesis and sensitivity to PARP inhibitors. Signature 3 identified by whole genome sequencing is also associated with homologous recombination deficiency and sensitivity to targeted therapies. In this review, we summarize molecular features and treatments of hereditary pancreatic cancer syndromes and surveillance procedures for unaffected high-risk cases. We also review transgenic murine models to gain a better understanding of carcinogenesis in hereditary pancreatic cancer.

Pancreatic cancer epidemiology: understanding the role of lifestyle and inherited risk factors

Pancreatic cancer is a leading cause of cancer death worldwide and its global burden has more than doubled over the past 25 years. The highest incidence regions for pancreatic cancer include North America, Europe and Australia, and although much of this increase is due to ageing worldwide populations, there are key modifiable risk factors for pancreatic cancer such as cigarette smoking, obesity, diabetes and alcohol intake. The prevalence of these risk factors is increasing in many global regions, resulting in increasing age-adjusted incidence rates for pancreatic cancer, but the relative contribution from these risk factors varies globally due to variation in the underlying prevalence and prevention strategies. Inherited genetic factors, although not directly modifiable, are an important component of pancreatic cancer risk, and include pathogenic variants in hereditary cancer genes, genes associated with hereditary pancreatitis, as well as common variants identified in genome-wide association studies. Identification of the genetic changes that underlie pancreatic cancer not only provides insight into the aetiology of this cancer but also provides an opportunity to guide early detection strategies. The goal of this Review is to provide an up-to-date overview of the established modifiable and inherited risk factors for pancreatic cancer.

Somatic Mutation Profiling in the Liquid Biopsy and Clinical Analysis of Hereditary and Familial Pancreatic Cancer Cases Reveals KRAS Negativity and a Longer Overall Survival

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis. KRAS mutations occur in up to 95% of cases and render the tumor resistant to many types of therapy. Therefore, these patients are treated with traditional cytotoxic agents, according to guidelines. The familial or hereditary form of the disease accounts for up to 10–15% of cases. We hypothesized that hereditary and Familial Pancreatic Cancer cases (H/FPC) have a distinct tumor specific mutation profile due to the presence of pathogenic germline mutations and we used circulating free DNA (cfDNA) in plasma to assess this hypothesis. H/FPC cases were mainly KRAS mutation negative and harbored tumor specific mutations that are potential treatment targets in the clinic. Thus, we conclude that cases with a hereditary or familial background can be treated with newer and more effective agents that may ultimately improve their overall survival.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) presents many challenges in the clinic and there are many areas for improvement in diagnostics and patient management. The five-year survival rate is around 7.2% as the majority of patients present with advanced disease at diagnosis that is treatment resistant. Approximately 10–15% of PDAC cases have a hereditary basis or Familial Pancreatic Cancer (FPC). Here we demonstrate the use of circulating free DNA (cfDNA) in plasma as a prognostic biomarker in PDAC. The levels of cfDNA correlated with disease status, disease stage, and overall survival. Furthermore, we show for the first time via BEAMing that the majority of hereditary or familial PDAC cases (around 84%) are negative for a KRAS somatic mutation. In addition, KRAS mutation negative cases harbor somatic mutations in potentially druggable genes such as KIT, PDGFR, MET, BRAF, and PIK3CA that could be exploited in the clinic. Finally, familial or hereditary cases have a longer overall survival compared to sporadic cases (10.2 vs. 21.7 months, respectively). Currently, all patients are treated the same in the clinic with cytotoxic agents, although here we demonstrate that there are different subtypes of tumors at the genetic level that could pave the way to personalized treatment.

The influence of familial pancreatic cancer on postoperative outcome in pancreatic cancer: relevance to adjuvant chemotherapy

BACKGROUND

Familial pancreatic cancer (FPC) is defined as a family in which at least two first-degree relatives have pancreatic cancer (PC). The prognostic significance of PC in an FPC family after surgery is not fully understood.

METHODS

This was a retrospective study of 427 patients who underwent pancreatectomy for pancreatic ductal adenocarcinoma between January 2008 and December 2016. PC patients who also had at least one first-degree relative with PC were defined as FPC patients. The associations between recurrence and clinicopathological characteristics were analyzed for both FPC and non-FPC patients.

RESULTS

FPC patients accounted for 31 of the 427 (7.3%) patients. Recurrence occurred in 72.1% of the total cohort and in 87.1% of the 31 FPC patients. Multivariate analysis showed that being an FPC patient was an independent predictor for relapse-free survival (RFS) (hazard ratio [HR] 1.52, P = 0.038). Although univariate analysis revealed that being an FPC patient was significantly associated with poorer overall survival (OS) (P < 0.001), multivariate analysis showed that being an FPC patient was not an independent predictor for OS (P = 0.164). Dichotomization of the 427 patients into those who received (n = 317: 17 FPC and 300 non-FPC patients) and did not receive (n = 110: 14 FPC and 96 non-FPC patients) adjuvant chemotherapy revealed that being an FPC patient was an independent predictor for RFS (HR 2.50, P < 0.001) and OS (HR 2.30, P = 0.003) only for patients who received adjuvant chemotherapy.

CONCLUSIONS

This study has shown that being an FPC patient is a significant prognostic indicator for PC patients who undergo resection and receive adjuvant chemotherapy.

Advances on diagnostic biomarkers of pancreatic ductal adenocarcinoma: A systems biology perspective

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy that is usually diagnosed at an advanced stage when curative surgery is no longer an option. Robust diagnostic biomarkers with high sensitivity and specificity for early detection are urgently needed. Systems biology provides a powerful tool for understanding diseases and solving challenging biological problems, allowing biomarkers to be identified and quantified with increasing accuracy, sensitivity, and comprehensiveness. Here, we present a comprehensive overview of efforts to identify biomarkers of PDAC using genomics, transcriptomics, proteomics, metabonomics, and bioinformatics. Systems biology perspective provides a crucial “network” to integrate multi-omics approaches to biomarker identification, shedding additional light on early PDAC detection.

Familial Pancreatic Cancer and Surveillance of High-Risk Individuals

Family history of pancreatic cancer (PC) is a risk factor for PC development, and the risk level correlates with the number of affected families. A case of PC with ≥1 PC cases in the first-degree relative is broadly defined as familial pancreatic cancer (FPC) and accounts for 5% to 10% of total PC cases. FPC possesses several epidemiological, genetic and clinicopathological aspects that are distinct from those of conventional PCs. In Western countries, FPC registries have been established since the 1990s, and high-risk individuals are screened to detect early PCs. For the pharmacotherapy of FPC, especially in cases with germline pathogenic BRCA mutations, regimens using platinum and poly (ADP-ribose) polymerase inhibitor have recently been studied for their effectiveness. To date, the concept of FPC has prevailed in Western countries, and it has begun to infiltrate into Eastern countries. As the genetic background and environmental conditions vary in association with ethnicity and living area, we need to establish our own FPC registries and accumulate data in Asian countries.

Surveillance of Individuals with a Family History of Pancreatic Cancer and Inherited Cancer Syndromes: A Strategy for Detecting Early Pancreatic Cancers

A family history of pancreatic cancer (PC) is a risk factor of PC, and risk levels increase as affected families grow in number and/or develop PC at younger ages. Familial pancreatic cancer (FPC) is defined as a client having at least two PC cases in a first degree relatives. In the narrow sense, FPC does not include some inherited cancer syndromes that are known to increase the risks of PC, such as Peutz-Jeghers syndrome (PJS), hereditary pancreatitis (HP), hereditary breast ovarian cancer syndrome (HBOC), and so on. FPC accounts for 5%-10% of total PC diagnoses and is marked by several features in genetic, epidemiological, and clinicopathological findings that are similar to or distinct from conventional PC. Recent advances in genetic medicine have led to an increased ability to identify germline variants of cancer-associated genes. To date, high-risk individuals (HRIs) in many developed countries, including FPC kindreds and inherited cancer syndromes, are screened clinically to detect and treat early-stage PC. This article highlights the concept of FPC and the most recent data on its detection.

Biphenotypic Differentiation of Pancreatic Cancer in 3-Dimensional Culture

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is the third most common cause of cancer death in the United States. Improved characterized models of PDAC are needed for drug screening.

METHODS

We grew 4 established pancreatic cancer cell lines in hanging drop cultures to produce spheroids. We also grew organoids from explanted xenografted PDAC and surgically resected primary PDAC. We performed transmission and scanning electron microscopy and compared findings with those of the normal pancreatic duct. We also performed single-cell cloning to determine the potential options for differentiation.

RESULTS

Spheroids contained tight junctions and desmosomes but lacked zymogen granules, as expected. The former features were present in normal pancreatic duct but absent from PDAC cell lines grown in standard 2-dimensional culture. Spheroids functionally excluded macromolecules in whole mounts. Cells on the surface of PDAC spheroids were carpeted by microvilli except for rare cells with prominent stereocilia. Carpets of microvilli were also seen in low passage organoids produced from xenografts and surgically resected human PDAC, in addition to normal human pancreatic duct. We performed single-cell cloning and resulting spheroids produced both cell phenotypes at the same approximate ratios as those from bulk cultures.

CONCLUSIONS

Pancreatic cancer spheroids/organoids are capable of biphenotypic differentiation.

Next-Generation Sequencing in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is lethal, and the majority of patients present with locally advanced or metastatic disease that is not amenable to cure. Thus, with surgical resection being the only curative modality, it is critical that disease is identified at an earlier stage to allow the appropriate therapy to be applied. Unfortunately, a specific biomarker for early diagnosis has not yet been identified; hence, no screening process exists. Recently, high-throughput screening and next-generation sequencing (NGS) have led to the identification of novel biomarkers for many disease processes, and work has commenced in PDAC. Genomic data generated by NGS not only have the potential to assist clinicians in early diagnosis and screening, especially in high-risk populations, but also may eventually allow the development of personalized treatment programs with targeted therapies, given the large number of gene mutations seen in PDAC. This review introduces the basic concepts of NGS and provides a comprehensive review of the current understanding of genetics in PDAC as related to discoveries made using NGS.

Circulating Tumor DNA as a Clinical Test in Resected Pancreatic Cancer

PURPOSE

In research settings, circulating tumor DNA (ctDNA) shows promise as a tumor-specific biomarker for pancreatic ductal adenocarcinoma (PDAC). This study aims to perform analytical and clinical validation of a KRAS ctDNA assay in a Clinical Laboratory Improvement Amendments (CLIA) and College of American Pathology-certified clinical laboratory.

EXPERIMENTAL DESIGN

Digital-droplet PCR was used to detect the major PDAC-associated somatic KRAS mutations (G12D, G12V, G12R, and Q61H) in liquid biopsies. For clinical validation, 290 preoperative and longitudinal postoperative plasma samples were collected from 59 patients with PDAC. The utility of ctDNA status to predict PDAC recurrence during follow-up was assessed.

RESULTS

ctDNA was detected preoperatively in 29 (49%) patients and was an independent predictor of decreased recurrence-free survival (RFS) and overall survival (OS). Patients who had neoadjuvant chemotherapy were less likely to have preoperative ctDNA than were chemo-naïve patients (21% vs. 69%; P < 0.001). ctDNA levels dropped significantly after tumor resection. Persistence of ctDNA in the immediate postoperative period was associated with a high rate of recurrence and poor median RFS (5 months). ctDNA detected during follow-up predicted clinical recurrence [sensitivity 90% (95% confidence interval (CI), 74%-98%), specificity 88% (95% CI, 62%-98%)] with a median lead time of 84 days (interquartile range, 25-146). Detection of ctDNA during postpancreatectomy follow-up was associated with a median OS of 17 months, while median OS was not yet reached at 30 months for patients without ctDNA (P = 0.011).

CONCLUSIONS

Measurement of KRAS ctDNA in a CLIA laboratory setting can be used to predict recurrence and survival in patients with PDAC.

Effects of the MDM-2 inhibitor Nutlin-3a on PDAC cells containing and lacking WT-TP53 on sensitivity to chemotherapy, signal transduction inhibitors and nutraceuticals

Mutations at the TP53 gene are readily detected (approximately 50-75%) in pancreatic ductal adenocarcinoma (PDAC) patients. TP53 was previously thought to be a difficult target as it is often mutated, deleted or inactivated on both chromosomes in certain cancers. In the following study, the effects of restoration of wild-type (WT) TP53 activity on the sensitivities of MIA-PaCa-2 pancreatic cancer cells to the MDM2 inhibitor nutlin-3a in combination with chemotherapy, targeted therapy, as well as, nutraceuticals were examined. Upon introduction of the WT-TP53 gene into MIA-PaCa-2 cells, which contain a TP53 gain of function (GOF) mutation, the sensitivity to the MDM2 inhibitor increased. However, effects of nutlin-3a were also observed in MIA-PaCa-2 cells lacking WT-TP53, as upon co-treatment with nutlin-3a, the sensitivity to certain inhibitors, chemotherapeutic drugs and nutraceuticals increased. Interestingly, co-treatment with nutlin-3a and certain chemotherapeutic drug such as irinotecan and oxaliplatin resulted in antagonistic effects in cells both lacking and containing WT-TP53 activity. These studies indicate the sensitizing abilities that WT-TP53 activity can have in PDAC cells which normally lack WT-TP53, as well as, the effects that the MDM2 inhibitor nutlin-3a can have in both cells containing and lacking WT-TP53 to various therapeutic agents.

Host IDO2 Gene Status Influences Tumor Progression and Radiotherapy Response in KRAS-Driven Sporadic Pancreatic Cancers

PURPOSE

Heritable genetic variations can affect the inflammatory tumor microenvironment, which can ultimately affect cancer susceptibility and clinical outcomes. Recent evidence indicates that IDO2, a positive modifier in inflammatory disease models, is frequently upregulated in pancreatic ductal adenocarcinoma (PDAC). A unique feature of IDO2 in humans is the high prevalence of two inactivating single-nucleotide polymorphisms (SNP), which affords the opportunity to carry out loss-of-function studies directly in humans. In this study, we sought to address whether genetic loss of IDO2 may influence PDAC development and responsiveness to treatment.Experimental Design: Transgenic Ido2 ^+/+ and Ido2 ^-/- mice in which oncogenic KRAS is activated in pancreatic epithelial cells were evaluated for PDAC. Two patient data sets (N = 200) were evaluated for the two IDO2-inactivating SNPs together with histologic, RNA expression, and clinical survival data.

RESULTS

PDAC development was notably decreased in the Ido2 ^-/- mice (30% vs. 10%, P < 0.05), with a female predominance similar to the association observed for one of the human SNPs. In patients, the biallelic occurrence of either of the two IDO2-inactivating SNPs was significantly associated with markedly improved disease-free survival in response to adjuvant radiotherapy (P < 0.01), a treatment modality that has been highly debated due to its variable efficacy.

CONCLUSIONS

The results of this study provide genetic support for IDO2 as a contributing factor in PDAC development and argue that IDO2 genotype analysis has the immediate potential to influence the PDAC care decision-making process through stratification of those patients who stand to benefit from adjuvant radiotherapy.

Introduction of WT-TP53 into pancreatic cancer cells alters sensitivity to chemotherapeutic drugs, targeted therapeutics and nutraceuticals

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive, highly metastatic malignancy and accounts for 85% of pancreatic cancers. PDAC patients have poor prognosis with a five-year survival of only 5-10%. Mutations at the TP53 gene are readily detected in pancreatic tumors isolated from PDAC patients. We have investigated the effects of restoration of wild-type (WT) TP53 activity on the sensitivity of pancreatic cancer cells to: chemotherapy, targeted therapy, as well as, nutraceuticals. Upon introduction of the WT-TP53 gene into the MIA-PaCa-2 pancreatic cancer cell line, the sensitivity to drugs used to treat pancreatic cancer cells such as: gemcitabine, fluorouracil (5FU), cisplatin, irinotecan, oxaliplatin, and paclitaxel increased significantly. Likewise, the sensitivity to drugs used to treat other cancers such as: doxorubicin, mitoxantrone, and 4 hydroxy tamoxifen (4HT) also increased upon introduction of WT-TP53 into MIA-PaCa-2 cells. Furthermore, the sensitivity to certain inhibitors which target: PI3K/mTORC1, PDK1, SRC, GSK-3, and biochemical processes such as proteasomal degradation and the nutraceutical berberine as increased upon introduction of WT-TP53. Furthermore, in some cases, cells with WT-TP53 were more sensitive to the combination of drugs and suboptimal doses of the MDM2 inhibitor nutlin-3a. However, TP53-independent effects of nutlin-3a were observed upon treatment with either a proteasomal or a PI3K/mTOR inhibitor. These studies indicate the sensitizing effects that WT-TP53 can have in PDAC cells which normally lack WT-TP53 to various therapeutic agents and suggest approaches to improve PDAC therapy.

Protein Biomarkers for Early Detection of Pancreatic Ductal Adenocarcinoma: Progress and Challenges

Approximately 75% of patients with pancreatic ductal adenocarcinoma are diagnosed with advanced cancer, which cannot be safely resected. The most commonly used biomarker CA19-9 has inadequate sensitivity and specificity for early detection, which we define as Stage I/II cancers. Therefore, progress in next-generation biomarkers is greatly needed. Recent reports have validated a number of biomarkers, including combination assays of proteins and DNA mutations; however, the history of translating promising biomarkers to clinical utility suggests that several major hurdles require careful consideration by the medical community. The first set of challenges involves nominating and verifying biomarkers. Candidate biomarkers need to discriminate disease from benign controls with high sensitivity and specificity for an intended use, which we describe as a two-tiered strategy of identifying and screening high-risk patients. Community-wide efforts to share samples, data, and analysis methods have been beneficial and progress meeting this challenge has been achieved. The second set of challenges is assay optimization and validating biomarkers. After initial candidate validation, assays need to be refined into accurate, cost-effective, highly reproducible, and multiplexed targeted panels and then validated in large cohorts. To move the most promising candidates forward, ideally, biomarker panels, head-to-head comparisons, meta-analysis, and assessment in independent data sets might mitigate risk of failure. Much more investment is needed to overcome these challenges. The third challenge is achieving clinical translation. To moonshot an early detection test to the clinic requires a large clinical trial and organizational, regulatory, and entrepreneurial know-how. Additional factors, such as imaging technologies, will likely need to improve concomitant with molecular biomarker development. The magnitude of the clinical translational challenge is uncertain, but interdisciplinary cooperation within the PDAC community is poised to confront it.

A Sub-Type of Familial Pancreatic Cancer: Evidence and Implications of Loss-of-Function Polymorphisms in Indoleamine-2,3-Dioxygenase-2

BACKGROUND

Variation in an individual’s genetic status can impact the development of pancreatic ductal adenocarcinoma; however, the m ajority of familial pancreatic cancers (FPC) cannot yet be attributed to a specific inherited mutation. We present data suggesting a correlation between loss-of-function single nucleotide polymorphisms (SNPs) in an immune regulator gene, indoleamine-2,3-dioxygenase-2 (IDO2), and an increased risk of FPC.

STUDY DESIGN

Germline DNA from patients who underwent resection for pancreatic ductal adenocarcinoma (n = 79) was sequenced for the IDO2 SNPs R248W and Y359Stop. Genotypes resulting in inactivation of IDO2 (Y325X homozygous, R248W homozygous) were labeled as homozygous, and the other genotypes were grouped as wild-type or heterozygous. Genotype distributions of each SNP were analyzed for Hardy-Weinberg deviation. A genotype frequency set from the 1000 Genomes Project (n = 99) was used as a genetic control for genotype distribution comparisons.

RESULTS

A significant 2-fold increase in the overall prevalence of the Y359Stop homozygous genotype compared with the expected Hardy-Weinberg equilibrium was noted (p < 0.05). Familial pancreatic cancer was noted in 15 cases (19%) and comparison of the FPC cohort set to the genetic control set showed a 3-fold increase in Y359Stop homozygous rates (p = 0.054). Overall in our cohort, the homozygous genotype group was associated with increased risk of FPC (odds ratio 5.4; 95% CI 1.6 to 17.6; p < 0.01). Sex, age at diagnosis, and history of tobacco use were not found to be significantly associated with FPC.

CONCLUSIONS

Our preliminary data suggest a strong association between the IDO2 inactivating Y359Stop SNP and an increased risk of FPC when compared with the control group. Future studies will evaluate the value of IDO2 genotyping as a prognostic, early detection marker for pancreatic ductal adenocarcinoma and a predictive marker for novel immune checkpoint therapies.

BRCA1/BRCA2 Germline Mutation Carriers and Sporadic Pancreatic Ductal Adenocarcinoma

BACKGROUND

The outcomes of sporadic pancreatic ductal adenocarcinoma (PDAC) patients with germline mutations of BRCA1/BRCA2 remains unclear. The prognostic significance of BRCA1/BRCA2 mutations on survival is not well established.

STUDY DESIGN

We performed targeted next-generation sequencing (NGS) to identify BRCA1/BRCA2 germline mutations in resected sporadic PDAC cases from 2000 to 2015. Germline BRCA mutation carriers were matched by age and tumor location to those with BRCA1/BRCA2 wild-type genes from our institutional database. Demographics, clinicopathologic features, overall survival (OS), and disease-free survival (DFS) were abstracted from medical records and compared between the 2 cohorts.

RESULTS

Twenty-two patients with sporadic cancer and BRCA1 (n = 4) or BRCA2 (n = 18) germline mutations and 105 wild-type patients were identified for this case-control study. The BRCA1/BRCA2 mutations were associated with inferior median OS (20.2 vs 27.8 months, p = 0.034) and DFS (8.4 vs 16.7 months, p < 0.001) when compared with the matched wild-type controls. On multivariable analyses, a BRCA1/BRCA2 mutation (hazard ratio [HR] 2.10, p < 0.001), positive margin status (HR 1.72, p = 0.021), and lack of adjuvant therapy (HR 2.38, p < 0.001), were all independently associated with worse survival. Within the BRCA1/BRCA2 mutated group, having had platinum-based adjuvant chemotherapy (n = 10) was associated with better survival than alternative chemotherapy (n = 8) or no adjuvant therapy (n = 4) (31.0 vs 17.8 vs 9.3 months, respectively, p < 0.001).

CONCLUSIONS

Carriers of BRCA1/BRCA2 mutation with sporadic PDAC had a worse survival after pancreatectomy than their BRCA wild-type counterparts. However, platinum-based chemotherapy regimens were associated with markedly improved survival in patients with BRCA1/BRCA2 mutations, with survival differences no longer appreciated with wild-type patients.

Pancreatic Cancer: Molecular Characterization, Clonal Evolution and Cancer Stem Cells

Pancreatic Ductal Adenocarcinoma (PDAC) is the fourth most common cause of cancer-related death and is the most lethal of common malignancies with a five-year survival rate of <10%. PDAC arises from different types of non-invasive precursor lesions: intraductal papillary mucinous neoplasms, mucinous cystic neoplasms and pancreatic intraepithelial neoplasia. The genetic landscape of PDAC is characterized by the presence of four frequently-mutated genes: KRAS, CDKN2A, TP53 and SMAD4. The development of mouse models of PDAC has greatly contributed to the understanding of the molecular and cellular mechanisms through which driver genes contribute to pancreatic cancer development. Particularly, oncogenic KRAS-driven genetically-engineered mouse models that phenotypically and genetically recapitulate human pancreatic cancer have clarified the mechanisms through which various mutated genes act in neoplasia induction and progression and have led to identifying the possible cellular origin of these neoplasias. Patient-derived xenografts are increasingly used for preclinical studies and for the development of personalized medicine strategies. The studies of the purification and characterization of pancreatic cancer stem cells have suggested that a minority cell population is responsible for initiation and maintenance of pancreatic adenocarcinomas. The study of these cells could contribute to the identification and clinical development of more efficacious drug treatments.

PDX1: A Unique Pancreatic Master Regulator Constantly Changes Its Functions during Embryonic Development and Progression of Pancreatic Cancer

Multifunctional activity of the PDX1 gene product is reviewed. The PDX1 protein is unique in that being expressed exclusively in the pancreas it exhibits various functional activities in this organ both during embryonic development and during induction and progression of pancreatic cancer. Hence, PDX1 belongs to the family of master regulators with multiple and often antagonistic functions.

Alterations of type II classical cadherin, cadherin-10 (CDH10), is associated with pancreatic ductal adenocarcinomas

Pancreatic ductal adenocarcinoma (PDAC), either sporadic or familial, has a dismal prognosis and finding candidate genes involved in development of the cancer is crucial for the patient care. First, we identified two patients with germline alterations in or adjacent to CDH10 by chromosome studies and sequencing analyses in 41 familial pancreatic cancer (FPC) cases. One patient had a balanced translocation between chromosome 5 and 20. The breakpoint on chromosome band 5p14.2 was ∼810 Kb upstream of CDH10, while that on chromosome arm 20p was in the pericentromeric region which might result in inactivation of one copy of the gene leading to reduced expression of CDH10. This interpretation was supported by loss of heterozygosity (LOH) seen in this region as determined by short tandem repeat analyses. Another patient had a single nucleotide variant in exon 12 (p.Arg688Gln) of CDH10. This amino acid was conserved among vertebrates and the mutation was predicted to have a pathogenic effect on the protein by several prediction algorithms. Next, we analyzed LOH status in the CDH10 region in sporadic PDAC and at least 24% of tumors had evidence of LOH. Immunohistochemical stains with CDH10 antibody showed a different staining pattern between normal pancreatic ducts and PDAC. Taken together, our data supports the notion that CDH10 is involved in sporadic pancreatic carcinogenesis, and might have a role in rare cases of FPC. Further functional studies are needed to elucidate the tumor suppressive role of CDH10 in pancreatic carcinogenesis.

Familial pancreatic cancer: Concept, management and issues

Familial pancreatic cancer (FPC) is broadly defined as two first-degree-relatives with pancreatic cancer (PC) and accounts for 4%-10% of PC. Several genetic syndromes, including Peutz-Jeghers syndrome, hereditary pancreatitis, hereditary breast-ovarian cancer syndrome (HBOC), Lynch syndrome, and familial adenomatous polyposis (FAP), also have increased risks of PC, but the narrowest definition of FPC excludes these known syndromes. When compared with other familial tumors, proven genetic alterations are limited to a small proportion (< 20%) and the familial aggregation is usually modest. However, an ethnic deviation (Ashkenazi Jewish > Caucasian) and a younger onset are common also in FPC. In European countries, “anticipation” is reported in FPC families, as with other hereditary syndromes; a trend toward younger age and worse prognosis is recognized in the late years. The resected pancreases of FPC kindred often show multiple pancreatic intraepithelial neoplasia (PanIN) foci, with various K-ras mutations, similar to colorectal polyposis seen in the FAP patients. As with HBOC patients, a patient who is a BRCA mutation carrier with unresectable pancreatic cancer (accounting for 0%-19% of FPC patients) demonstrated better outcome following platinum and Poly (ADP-ribose) polymerase inhibitor treatment. Western countries have established FPC registries since the 1990s and several surveillance projects for high-risk individuals are now ongoing to detect early PCs. Improvement in lifestyle habits, including non-smoking, is recommended for individuals at risk. In Japan, the FPC study group was initiated in 2013 and the Japanese FPC registry was established in 2014 by the Japan Pancreas Society.

Post-transcriptional Regulation of BRCA2 through Interactions with miR-19a and miR-19b

Breast cancer type 2, early onset susceptibility gene (BRCA2) is a major component of the homologous recombination DNA repair pathway. It acts as a tumor suppressor whose function is often lost in cancers. Patients with specific mutations in the BRCA2 gene often display discrete clinical, histopathological, and molecular features. However, a subset of sporadic cancers has wild type BRCA2 and display defects in the homology-directed repair pathway, which is the hallmark of ‘BRCAness.’ The mechanisms by which BRCAness arises are not well understood but post-transcriptional regulation of BRCA2 gene expression by microRNAs (miRNAs) may contribute to this phenotype. Here, we examine the post-transcriptional effects that some members of the six-miRNA cluster known as the miR-17/92 cluster have on the abundance of BRCA2’s messenger RNA (mRNA) and protein. We discuss two interactions involving the miR-19a and miR-19b members of the cluster and the 3′UTR of BRCA2’s mRNA. We investigated these miRNA:mRNA interactions in 15 cell lines derived from pancreatic, breast, colon, and kidney tissue. We show that over-expression of these two miRNAs results in a concomitant decrease of BRCA2’s mRNA and protein expression in a subset of the tested cell lines. Additionally, using luciferase reporter assays we identified direct interactions between miR-19a/miR-19b and a miRNA response element (MRE) in BRCA2’s 3′UTR. Our results suggest that BRCA2 is subject to a complex post-transcriptional regulatory program that has specific dependencies on the genetic and phenotypic background of cell types.

Nanopore sequencing detects structural variants in cancer

Despite advances in sequencing, structural variants (SVs) remain difficult to reliably detect due to the short read length (<300 bp) of 2nd generation sequencing. Not only do the reads (or paired-end reads) need to straddle a breakpoint, but repetitive elements often lead to ambiguities in the alignment of short reads. We propose to use the long-reads (up to 20 kb) possible with 3rd generation sequencing, specifically nanopore sequencing on the MinION. Nanopore sequencing relies on a similar concept to a Coulter counter, reading the DNA sequence from the change in electrical current resulting from a DNA strand being forced through a nanometer-sized pore embedded in a membrane. Though nanopore sequencing currently has a relatively high mismatch rate that precludes base substitution and small frameshift mutation detection, its accuracy is sufficient for SV detection because of its long reads. In fact, long reads in some cases may improve SV detection efficiency. We have tested nanopore sequencing to detect a series of well-characterized SVs, including large deletions, inversions, and translocations that inactivate the CDKN2A/p16 and SMAD4/DPC4 tumor suppressor genes in pancreatic cancer. Using PCR amplicon mixes, we have demonstrated that nanopore sequencing can detect large deletions, translocations and inversions at dilutions as low as 1:100, with as few as 500 reads per sample. Given the speed, small footprint, and low capital cost, nanopore sequencing could become the ideal tool for the low-level detection of cancer-associated SVs needed for molecular relapse, early detection, or therapeutic monitoring.

Whole Genome Sequencing Defines the Genetic Heterogeneity of Familial Pancreatic Cancer

Pancreatic cancer is projected to become the second leading cause of cancer-related death in the United States by 2020. A familial aggregation of pancreatic cancer has been established, but the cause of this aggregation in most families is unknown. To determine the genetic basis of susceptibility in these families, we sequenced the germline genomes of 638 patients with familial pancreatic cancer and the tumor exomes of 39 familial pancreatic adenocarcinomas. Our analyses support the role of previously identified familial pancreatic cancer susceptibility genes such as BRCA2, CDKN2A, and ATM, and identify novel candidate genes harboring rare, deleterious germline variants for further characterization. We also show how somatic point mutations that occur during hematopoiesis can affect the interpretation of genome-wide studies of hereditary traits. Our observations have important implications for the etiology of pancreatic cancer and for the identification of susceptibility genes in other common cancer types.

SIGNIFICANCE

The genetic basis of disease susceptibility in the majority of patients with familial pancreatic cancer is unknown. We whole genome sequenced 638 patients with familial pancreatic cancer and demonstrate that the genetic underpinning of inherited pancreatic cancer is highly heterogeneous. This has significant implications for the management of patients with familial pancreatic cancer.

Time to progression of pancreatic ductal adenocarcinoma from low-to-high tumour stages

OBJECTIVE

Although pancreatic ductal adenocarcinoma is considered a rapidly progressive disease, mathematical models estimate that it takes many years for an initiating pancreatic cancer cell to grow into an advanced stage cancer. In order to estimate the time it takes for a pancreatic cancer to progress through different tumor, node, metastasis (TNM) stages, we compared the mean age of patients with pancreatic cancers of different sizes and stages.

DESIGN

Patient age, tumour size, stage and demographic information were analysed for 13,131 patients with pancreatic ductal adenocarcinoma entered into the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database. Multiple linear regression models for age were generated, adjusting for patient ethnicity, gender, tumour location and neoplastic grades.

RESULTS

African-American ethnicity and male gender were associated with an earlier age at diagnosis. Patients with stage I cancers (mean age 64.8 years) were on average 1.3 adjusted years younger at diagnosis than those with stage IV cancers (p=0.001). Among patients without distant metastases, those with T1 stage cancers were on average 1.06 and 1.19 adjusted years younger, respectively, than patients with T3 or T4 cancers (p=0.03 for both). Among patients with stage IIB cancers, those with T1/T2 cancers were 0.79 adjusted years younger than those with T3 cancers (p=0.06). There was no significant difference in the mean adjusted age of patients with stage IA versus stage IB cancers.

CONCLUSIONS

These results are consistent with the hypothesis that once pancreatic ductal adenocarcinomas become detectable clinically progression from low-stage to advanced-stage disease is rapid.

Transflip mutations produce deletions in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is driven by the inactivation of the tumor suppressor genes (TSGs), CDKN2A (P16) and SMAD4 (DPC4), commonly by homozygous deletions (HDs). Using a combination of high density single-nucleotide polymorphism (SNP) microarray and whole genome sequencing (WGS), we fine-mapped novel breakpoints surrounding deletions of CDKN2A and SMAD4 and characterized them by their underlying structural variants (SVs). Only one third of CDKN2A and SMAD4 deletions (6 of 18) were simple interstitial deletions, rather, the majority of deletions were caused by complex rearrangements, specifically, a translocation on one side of the TSG in combination with an inversion on the other side. We designate these as "TransFlip" mutations. Characteristics of TransFlip mutations are: (1) a propensity to target the TSGs CDKN2A and SMAD4 (P < 0.005), (2) not present in the germline of the examined samples, (3) non-recurrent breakpoints, (4) relatively small (47 bp to 3.4 kb) inversions, (5) inversions can be either telomeric or centromeric to the TSG, and (6) non-reciprocal, and non-recurrent translocations. TransFlip mutations are novel complex genomic rearrangements with unique breakpoint signatures in pancreatic cancer. We hypothesize that they are a common but poorly understood mechanism of TSG inactivation in human cancer. © 2015 Wiley Periodicals, Inc.

The genetic classification of pancreatic neoplasia

Cancer is caused by the accumulation of inherited and/or acquired alterations in specific genes. The recent decline in the cost of DNA sequencing has allowed tumor sequencing to be conducted on a large scale, which, in turn, has led to an unprecedented understanding of the genetic events that drive neoplasia. This understanding, when integrated with meticulous histologic analyses and with clinical findings, has direct clinical implications. The recent sequencing of all of the major types of cystic and noncystic neoplasms of the pancreas has revealed opportunities for molecular diagnoses and for personalized treatment. This review summarizes the results from these recent studies focusing on the clinical relevance of genomic data.