Oral bacteria accelerate pancreatic cancer development in mice

OBJECTIVE

Epidemiological studies highlight an association between pancreatic ductal adenocarcinoma (PDAC) and oral carriage of the anaerobic bacterium Porphyromonas gingivalis, a species highly linked to periodontal disease. We analysed the potential for P. gingivalis to promote pancreatic cancer development in an animal model and probed underlying mechanisms.

DESIGN

We tracked P. gingivalis bacterial translocation from the oral cavity to the pancreas following administration to mice. To dissect the role of P. gingivalis in PDAC development, we administered bacteria to a genetically engineered mouse PDAC model consisting of inducible acinar cell expression of mutant Kras (Kras +/LSL-G12D; Ptf1a-CreER, iKC mice). These mice were used to study the cooperative effects of Kras mutation and P. gingivalis on the progression of pancreatic intraepithelial neoplasia (PanIN) to PDAC. The direct effects of P. gingivalis on acinar cells and PDAC cell lines were studied in vitro.

RESULTS

P. gingivalis migrated from the oral cavity to the pancreas in mice and can be detected in human PanIN lesions. Repetitive P. gingivalis administration to wild-type mice induced pancreatic acinar-to-ductal metaplasia (ADM), and altered the composition of the intrapancreatic microbiome. In iKC mice, P. gingivalis accelerated PanIN to PDAC progression. In vitro, P. gingivalis infection induced acinar cell ADM markers SOX9 and CK19, and intracellular bacteria protected PDAC cells from reactive oxygen species-mediated cell death resulting from nutrient stress.

CONCLUSION

Taken together, our findings demonstrate a causal role for P. gingivalis in pancreatic cancer development in mice.

Protein biomarkers and alternatively methylated cell-free DNA detect early stage pancreatic cancer

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is commonly diagnosed at an advanced stage. Liquid biopsy approaches may facilitate detection of early stage PDAC when curative treatments can be employed.

DESIGN

To assess circulating marker discrimination in training, testing and validation patient cohorts (total n=426 patients), plasma markers were measured among PDAC cases and patients with chronic pancreatitis, colorectal cancer (CRC), and healthy controls. Using CA19-9 as an anchor marker, measurements were made of two protein markers (TIMP1, LRG1) and cell-free DNA (cfDNA) pancreas-specific methylation at 9 loci encompassing 61 CpG sites.

RESULTS

Comparative methylome analysis identified nine loci that were differentially methylated in exocrine pancreas DNA. In the training set (n=124 patients), cfDNA methylation markers distinguished PDAC from healthy and CRC controls. In the testing set of 86 early stage PDAC and 86 matched healthy controls, CA19-9 had an area under the receiver operating characteristic curve (AUC) of 0.88 (95% CI 0.83 to 0.94), which was increased by adding TIMP1 (AUC 0.92; 95% CI 0.88 to 0.96; p=0.06), LRG1 (AUC 0.92; 95% CI 0.88 to 0.96; p=0.02) or exocrine pancreas-specific cfDNA methylation markers at nine loci (AUC 0.92; 95% CI 0.88 to 0.96; p=0.02). In the validation set of 40 early stage PDAC and 40 matched healthy controls, a combined panel including CA19-9, TIMP1 and a 9-loci cfDNA methylation panel had greater discrimination (AUC 0.86, 95% CI 0.77 to 0.95) than CA19-9 alone (AUC 0.82; 95% CI 0.72 to 0.92).

CONCLUSION

A combined panel of circulating markers including proteins and methylated cfDNA increased discrimination compared with CA19-9 alone for early stage PDAC.

Revisiting the performance of cyst fluid carcinoembryonic antigen as a diagnostic marker for pancreatic mucinous cysts: a comprehensive 20-year institutional review

OBJECTIVE

Elevated pancreatic cyst fluid carcinoembryonic antigen (CEA) has been routinely used to classify mucinous cysts. This study incorporates original data that established the CEA ≥192 ng/mL threshold with over 20 years of additional data and reassesses the diagnostic performance of CEA for differentiating mucinous from non-mucinous cysts.

DESIGN

1169 pancreatic cysts (1999-2021) with CEA results were identified. 394 cases had histological confirmation as the diagnostic standard. Additionally, 237 cysts without histological confirmation demonstrated KRAS, GNAS, or RNF43 mutations by molecular testing and were combined with the histologically confirmed cysts for separate analysis on a total cohort of 631 cysts.

RESULTS

Median CEA was significantly higher in mucinous cysts (323.9 ng/mL, n=314) versus non-mucinous cysts (204.6 ng/mL, n=80) (p<0.001). Receiver operating characteristic curve analysis demonstrated an optimal CEA cut-off of 20 ng/mL (area under the curve: 80%), though the specificity was lower than desired (sensitivity 89%, specificity 64%). At the previously established threshold of 192 ng/mL, sensitivity and specificity were 56% and 78%, respectively. To achieve a specificity of 85% as originally reported, a CEA threshold of 250 ng/mL was needed; the 13 false positive cases at this threshold included 4 benign simple cysts, 2 squamoid cysts, 1 serous cystadenoma, 1 lymphoepithelial cyst and 5 more uncommon entities. All results remained similar within the total cohort after including additional cases with KRAS/GNAS/RNF43 mutations only.

CONCLUSION

Cyst fluid CEA continues to be a useful test in the diagnosis of mucinous pancreatic cysts but does not appear as specific as previously reported. Raising the CEA threshold to 250 ng/mL to maintain specificity for differentiating mucinous from non-mucinous cysts may be considered.

A mucus production programme promotes classical pancreatic ductal adenocarcinoma

OBJECTIVE

The optimal therapeutic response in cancer patients is highly dependent upon the differentiation state of their tumours. Pancreatic ductal adenocarcinoma (PDA) is a lethal cancer that harbours distinct phenotypic subtypes with preferential sensitivities to standard therapies. This study aimed to investigate intratumour heterogeneity and plasticity of cancer cell states in PDA in order to reveal cell state-specific regulators.

DESIGN

We analysed single-cell expression profiling of mouse PDAs, revealing intratumour heterogeneity and cell plasticity and identified pathways activated in the different cell states. We performed comparative analysis of murine and human expression states and confirmed their phenotypic diversity in specimens by immunolabeling. We assessed the function of phenotypic regulators using mouse models of PDA, organoids, cell lines and orthotopically grafted tumour models.

RESULTS

Our expression analysis and immunolabeling analysis show that a mucus production programme regulated by the transcription factor SPDEF is highly active in precancerous lesions and the classical subtype of PDA - the most common differentiation state. SPDEF maintains the classical differentiation and supports PDA transformation in vivo. The SPDEF tumour-promoting function is mediated by its target genes AGR2 and ERN2/IRE1β that regulate mucus production, and inactivation of the SPDEF programme impairs tumour growth and facilitates subtype interconversion from classical towards basal-like differentiation.

CONCLUSIONS

Our findings expand our understanding of the transcriptional programmes active in precancerous lesions and PDAs of classical differentiation, determine the regulators of mucus production as specific vulnerabilities in these cell states and reveal phenotype switching as a response mechanism to inactivation of differentiation states determinants.

Enhanced antitumour immunity following neoadjuvant chemoradiotherapy mediates a favourable prognosis in women with resected pancreatic cancer

BACKGROUND

This study investigates sex disparities in clinical outcomes and tumour immune profiles in patients with pancreatic ductal adenocarcinoma (PDAC) who underwent upfront resection or resection preceded by gemcitabine-based neoadjuvant chemoradiotherapy (nCRT).

METHODS

Patients originated from the PREOPANC randomised controlled trial. Upfront surgery was performed in 82 patients, and 66 received nCRT before resection. The impact of sex on overall survival (OS) was investigated using Cox proportional hazards models. The immunological landscape within the tumour microenvironment (TME) was mapped using transcriptomic and spatial proteomic profiling.

RESULTS

The 5-year OS rate differed between the sexes following resection preceded by nCRT, with 43% for women compared with 22% for men. In multivariate analysis, the female sex was a favourable independent prognostic factor for OS only in the nCRT group (HR 0.19; 95% CI 0.07 to 0.52). Multivariate heterogeneous treatment effects analysis revealed a significant interaction between sex and treatment, implying increased nCRT efficacy among women with resected PDAC. The TME of women contained fewer protumoural CD163+MRC1+M2 macrophages than that of men after nCRT, as indicated by transcriptomic and validated using spatial proteomic profiling.

CONCLUSION

PDAC tumours of women are more sensitive to gemcitabine-based nCRT, resulting in longer OS after resection compared with men. This may be due to enhanced immunity impeding the infiltration of protumoral M2 macrophages into the TME. Our findings highlight the importance of considering sex disparities and mitigating immunosuppressive macrophage polarisation for personalised PDAC treatment.

CRIP1 fosters MDSC trafficking and resets tumour microenvironment via facilitating NF-κB/p65 nuclear translocation in pancreatic ductal adenocarcinoma

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is among the most immunosuppressive tumour types. The tumour immune microenvironment (TIME) is largely driven by interactions between immune cells and heterogeneous tumour cells. Here, we aimed to investigate the mechanism of tumour cells in TIME formation and provide potential combination treatment strategies for PDAC patients based on genotypic heterogeneity.

DESIGN

Highly multiplexed imaging mass cytometry, RNA sequencing, mass cytometry by time of flight and multiplex immunofluorescence staining were performed to identify the pro-oncogenic proteins associated with low immune activation in PDAC. An in vitro coculture system, an orthotopic PDAC allograft tumour model, flow cytometry and immunohistochemistry were used to explore the biological functions of cysteine-rich intestinal protein 1 (CRIP1) in tumour progression and TIME formation. RNA sequencing, mass spectrometry and chromatin immunoprecipitation were subsequently conducted to investigate the underlying mechanisms of CRIP1.

RESULTS

Our results showed that CRIP1 was frequently upregulated in PDAC tissues with low immune activation. Elevated CRIP1 expression induced high levels of myeloid-derived suppressor cell (MDSC) infiltration and fostered an immunosuppressive tumour microenvironment. Mechanistically, we primarily showed that CRIP1 bound to nuclear factor kappa-B (NF-κB)/p65 and facilitated its nuclear translocation in an importin-dependent manner, leading to the transcriptional activation of CXCL1/5. PDAC-derived CXCL1/5 facilitated the chemotactic migration of MDSCs to drive immunosuppression. SX-682, an inhibitor of CXCR1/2, blocked tumour MDSC recruitment and enhanced T-cell activation. The combination of anti-PD-L1 therapy with SX-682 elicited increased CD8+T cell infiltration and potent antitumor activity in tumour-bearing mice with high CRIP1 expression.

CONCLUSIONS

The CRIP1/NF-κB/CXCL axis is critical for triggering immune evasion and TIME formation in PDAC. Blockade of this signalling pathway prevents MDSC trafficking and thereby sensitises PDAC to immunotherapy.

Mature tertiary lymphoid structures are key niches of tumour-specific immune responses in pancreatic ductal adenocarcinomas

OBJECTIVE

To better understand the immune microenvironment of pancreatic ductal adenocarcinomas (PDACs), here we explored the relevance of T and B cell compartmentalisation into tertiary lymphoid structures (TLSs) for the generation of local antitumour immunity.

DESIGN

We characterised the functional states and spatial organisation of PDAC-infiltrating T and B cells using single-cell RNA sequencing (scRNA-seq), flow cytometry, multicolour immunofluorescence, gene expression profiling of microdissected TLSs, as well as in vitro assays. In addition, we performed a pan-cancer analysis of tumour-infiltrating T cells using scRNA-seq and sc T cell receptor sequencing datasets from eight cancer types. To evaluate the clinical relevance of our findings, we used PDAC bulk RNA-seq data from The Cancer Genome Atlas and the PRINCE chemoimmunotherapy trial.

RESULTS

We found that a subset of PDACs harbours fully developed TLSs where B cells proliferate and differentiate into plasma cells. These mature TLSs also support T cell activity and are enriched with tumour-reactive T cells. Importantly, we showed that chronically activated, tumour-reactive T cells exposed to fibroblast-derived TGF-β may act as TLS organisers by producing the B cell chemoattractant CXCL13. Identification of highly similar subsets of clonally expanded CXCL13 + tumour-infiltrating T cells across multiple cancer types further indicated a conserved link between tumour-antigen recognition and the allocation of B cells within sheltered hubs in the tumour microenvironment. Finally, we showed that the expression of a gene signature reflecting mature TLSs was enriched in pretreatment biopsies from PDAC patients with longer survival after receiving different chemoimmunotherapy regimens.

CONCLUSION

We provided a framework for understanding the biological role of PDAC-associated TLSs and revealed their potential to guide the selection of patients for future immunotherapy trials.

SK2 channels set a signalling hub bolstering CAF-triggered tumourigenic processes in pancreatic cancer

OBJECTIVE

Intercellular communication within pancreatic ductal adenocarcinoma (PDAC) dramatically contributes to metastatic processes. The underlying mechanisms are poorly understood, resulting in a lack of targeted therapy to counteract stromal-induced cancer cell aggressiveness. Here, we investigated whether ion channels, which remain understudied in cancer biology, contribute to intercellular communication in PDAC.

DESIGN

We evaluated the effects of conditioned media from patient-derived cancer-associated fibroblasts (CAFs) on electrical features of pancreatic cancer cells (PCC). The molecular mechanisms were deciphered using a combination of electrophysiology, bioinformatics, molecular and biochemistry techniques in cell lines and human samples. An orthotropic mouse model where CAF and PCC were co-injected was used to evaluate tumour growth and metastasis dissemination. Pharmacological studies were carried out in the Pdx1-Cre, Ink4a^fl/fl LSL-Kras^G12D (KIC^pdx1) mouse model.

RESULTS

We report that the K⁺ channel SK2 expressed in PCC is stimulated by CAF-secreted cues (8.84 vs 2.49 pA/pF) promoting the phosphorylation of the channel through an integrin-epidermal growth factor receptor (EGFR)-AKT (Protein kinase B) axis. SK2 stimulation sets a positive feedback on the signalling pathway, increasing invasiveness in vitro (threefold) and metastasis formation in vivo. The CAF-dependent formation of the signalling hub associating SK2 and AKT requires the sigma-1 receptor chaperone. The pharmacological targeting of Sig-1R abolished CAF-induced activation of SK2, reduced tumour progression and extended the overall survival in mice (11.7 weeks vs 9.5 weeks).

CONCLUSION

We establish a new paradigm in which an ion channel shifts the activation level of a signalling pathway in response to stromal cues, opening a new therapeutic window targeting the formation of ion channel-dependent signalling hubs.

Macrophages direct cancer cells through a LOXL2-mediated metastatic cascade in pancreatic ductal adenocarcinoma

OBJECTIVE

The lysyl oxidase-like protein 2 (LOXL2) contributes to tumour progression and metastasis in different tumour entities, but its role in pancreatic ductal adenocarcinoma (PDAC) has not been evaluated in immunocompetent in vivo PDAC models.

DESIGN

Towards this end, we used PDAC patient data sets, patient-derived xenograft in vivo and in vitro models, and four conditional genetically-engineered mouse models (GEMMS) to dissect the role of LOXL2 in PDAC. For GEMM-based studies, K-Ras +/LSL-G12D;Trp53 LSL-R172H;Pdx1-Cre mice (KPC) and the K-Ras +/LSL-G12D;Pdx1-Cre mice (KC) were crossed with Loxl2 allele floxed mice (Loxl2Exon2 fl/fl) or conditional Loxl2 overexpressing mice (R26Loxl2 KI/KI) to generate KPCL2KO or KCL2KO and KPCL2KI or KCL2KI mice, which were used to study overall survival; tumour incidence, burden and differentiation; metastases; epithelial to mesenchymal transition (EMT); stemness and extracellular collagen matrix (ECM) organisation.

RESULTS

Using these PDAC mouse models, we show that while Loxl2 ablation had little effect on primary tumour development and growth, its loss significantly decreased metastasis and increased overall survival. We attribute this effect to non-cell autonomous factors, primarily ECM remodelling. Loxl2 overexpression, on the other hand, promoted primary and metastatic tumour growth and decreased overall survival, which could be linked to increased EMT and stemness. We also identified tumour-associated macrophage-secreted oncostatin M (OSM) as an inducer of LOXL2 expression, and show that targeting macrophages in vivo affects Osm and Loxl2 expression and collagen fibre alignment.

CONCLUSION

Taken together, our findings establish novel pathophysiological roles and functions for LOXL2 in PDAC, which could be potentially exploited to treat metastatic disease.

Lysosomal lipid switch sensitises to nutrient deprivation and mTOR targeting in pancreatic cancer

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with limited therapeutic options. However, metabolic adaptation to the harsh PDAC environment can expose liabilities useful for therapy. Targeting the key metabolic regulator mechanistic target of rapamycin complex 1 (mTORC1) and its downstream pathway shows efficacy only in subsets of patients but gene modifiers maximising response remain to be identified.

DESIGN

Three independent cohorts of PDAC patients were studied to correlate PI3K-C2γ protein abundance with disease outcome. Mechanisms were then studied in mouse (KPC mice) and cellular models of PDAC, in presence or absence of PI3K-C2γ (WT or KO). PI3K-C2γ-dependent metabolic rewiring and its impact on mTORC1 regulation were assessed in conditions of limiting glutamine availability. Finally, effects of a combination therapy targeting mTORC1 and glutamine metabolism were studied in WT and KO PDAC cells and preclinical models.

RESULTS

PI3K-C2γ expression was reduced in about 30% of PDAC cases and was associated with an aggressive phenotype. Similarly, loss of PI3K-C2γ in KPC mice enhanced tumour development and progression. The increased aggressiveness of tumours lacking PI3K-C2γ correlated with hyperactivation of mTORC1 pathway and glutamine metabolism rewiring to support lipid synthesis. PI3K-C2γ-KO tumours failed to adapt to metabolic stress induced by glutamine depletion, resulting in cell death.

CONCLUSION

Loss of PI3K-C2γ prevents mTOR inactivation and triggers tumour vulnerability to RAD001 (mTOR inhibitor) and BPTES/CB-839 (glutaminase inhibitors). Therefore, these results might open the way to personalised treatments in PDAC with PI3K-C2γ loss.

Managing inoperable pancreatic cancer: the role of the pancreaticobiliary physician

Despite our understanding of pancreatic cancer (PC), the majority of patients with this disease are incurable. Both the incidence and mortality rates for PC have increased over the last decade. At diagnosis, the majority of patients have locally advanced PC, less than 20% of patients are eligible for potentially curative resection and approximately one-third have metastatic disease. The combination of frequent advanced presentation, low resection rates and poor responses to chemotherapy make PC one of the most lethal tumours. The treatment goals are to maintain local control, manage tumour-related morbidities and improve quality of life. Patients with inoperable PC are likely to experience significant symptoms associated with their tumour, including pancreatic insufficiency, nutritional deficiencies, pain, biliary obstruction, gastric outlet obstruction and diabetes. As a result, guidance on the management of patients with inoperable PC is critical. PC is commonly referred centrally to specialist centres particularly for surgery; however, the majority do not undergo surgical intervention and thus the importance of pancreaticobiliary physicians and endoscopists. This review will focus on the non-operative management of patients with unresectable pancreatic adenocarcinoma and review some of the issues that centralisation has contributed to.

Radiological evaluation of pancreatic cancer: What is the significance of arterial encasement >180° after neoadjuvant treatment?

PURPOSE

This study aimed to evaluate contrast-enhanced computed tomography (CE-CT) features for prediction of arterial tumor invasion in pancreatic cancer (PDAC) patients in the event of arterial encasement >180° after neoadjuvant (radio-)chemotherapy (NAT).

METHODS

Seventy PDAC patients with seventy-five arteries showing encasement >180° after completion of NAT were analyzed. All patients underwent surgical exploration with either tumor resection including arterial resection, periadventitial dissection (arterial divestment) or confirmation of locally irresectable disease. CE-CT scans were assessed regarding tumor extent and artery-specific imaging features. The results were analyzed on a per-artery basis. Based on the intraoperative and histopathological findings, encased arteries were classified as either invaded or non-invaded.

RESULTS

Eighteen radiologically encased arteries were resected; of these, nine had pathologic evidence for tumor invasion. In 42 encased arteries, the tumor could be removed by arterial divestment. In 13 patients with 15 encased arteries, the tumor was deemed technically irresectable. Median tumor size, length of solid soft tissue contact, and degree of circumferential contiguity by solid soft tissue along the artery in CE-CT were significantly lower in the non-invaded than in the invaded artery group (p ≤ 0.017). Imaging features showed moderate accuracies for prediction of arterial invasion (≤72.0 %). The thresholds ≤26 mm for post-NAT solid soft tissue contact and ≤270° for circumferential contiguity by solid soft tissue had high negative predictive values (≥87.5 %).

CONCLUSION

Although post-NAT prediction of arterial invasion remains difficult, arteries with ≤270° contiguity by soft tissue and arteries with ≤26 mm length of solid soft tissue contact are unlikely to be invaded, with possible implications for surgical planning.

c-Myc downregulation is required for preacinar to acinar maturation and pancreatic homeostasis

BACKGROUND AND AIMS

c-Myc is highly expressed in pancreatic multipotent progenitor cells (MPC) and in pancreatic cancer. The transition from MPC to unipotent acinar progenitors is associated with c-Myc downregulation; a role for c-Myc in this process, and its possible relationship to a role in cancer, has not been established.

DESIGN

Using coimmunoprecipitation assays, we demonstrate that c-Myc and Ptf1a interact. Using reverse transcriptase qPCR, western blot and immunofluorescence, we show the erosion of the acinar programme. To analyse the genomic distribution of c-Myc and Ptf1a and the global transcriptomic profile, we used ChIP-seq and RNA-seq, respectively; validation was performed with ChIP-qPCR and RT-qPCR. Lineage-tracing experiments were used to follow the effect of c-Myc overexpression in preacinar cells on acinar differentiation.

RESULTS

c-Myc binds and represses the transcriptional activity of Ptf1a. c-Myc overexpression in preacinar cells leads to a massive erosion of differentiation. In adult Ela1-Myc mice: (1) c-Myc binds to Ptf1a, and Tcf3 is downregulated; (2) Ptf1a and c-Myc display partially overlapping chromatin occupancy but do not bind the same E-boxes; (3) at the proximal promoter of genes coding for digestive enzymes, we find reduced PTF1 binding and increased levels of repressive chromatin marks and PRC2 complex components. Lineage tracing of committed acinar precursors reveals that c-Myc overexpression does not restore multipotency but allows the persistence of a preacinar-like cell population. In addition, mutant KRas can lead to c-Myc overexpression and acinar dysregulation.

CONCLUSIONS

c-Myc repression during development is crucial for the maturation of preacinar cells, and c-Myc overexpression can contribute to pancreatic carcinogenesis through the induction of a dedifferentiated state.

Fibroblast drug scavenging increases intratumoural gemcitabine accumulation in murine pancreas cancer

OBJECTIVE

Desmoplasia and hypovascularity are thought to impede drug delivery in pancreatic ductal adenocarcinoma (PDAC). However, stromal depletion approaches have failed to show clinical responses in patients. Here, we aimed to revisit the role of the tumour microenvironment as a physical barrier for gemcitabine delivery.

DESIGN

Gemcitabine metabolites were analysed in LSL-KrasG12D/+ ; LSL-Trp53R172H/+ ; Pdx-1-Cre (KPC) murine tumours and matched liver metastases, primary tumour cell lines, cancer-associated fibroblasts (CAFs) and pancreatic stellate cells (PSCs) by liquid chromatography-mass spectrometry/mass spectrometry. Functional and preclinical experiments, as well as expression analysis of stromal markers and gemcitabine metabolism pathways were performed in murine and human specimen to investigate the preclinical implications and the mechanism of gemcitabine accumulation.

RESULTS

Gemcitabine accumulation was significantly enhanced in fibroblast-rich tumours compared with liver metastases and normal liver. In vitro, significantly increased concentrations of activated 2',2'-difluorodeoxycytidine-5'-triphosphate (dFdCTP) and greatly reduced amounts of the inactive gemcitabine metabolite 2',2'-difluorodeoxyuridine were detected in PSCs and CAFs. Mechanistically, key metabolic enzymes involved in gemcitabine inactivation such as hydrolytic cytosolic 5'-nucleotidases (Nt5c1A, Nt5c3) were expressed at low levels in CAFs in vitro and in vivo, and recombinant expression of Nt5c1A resulted in decreased intracellular dFdCTP concentrations in vitro. Moreover, gemcitabine treatment in KPC mice reduced the number of liver metastases by >50%.

CONCLUSIONS

Our findings suggest that fibroblast drug scavenging may contribute to the clinical failure of gemcitabine in desmoplastic PDAC. Metabolic targeting of CAFs may thus be a promising strategy to enhance the antiproliferative effects of gemcitabine.

Pancreatic cancer cell lines as patient-derived avatars: genetic characterisation and functional utility

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is a therapy recalcitrant disease with the worst survival rate of common solid tumours. Preclinical models that accurately reflect the genetic and biological diversity of PDAC will be important for delineating features of tumour biology and therapeutic vulnerabilities.

DESIGN

27 primary PDAC tumours were employed for genetic analysis and development of tumour models. Tumour tissue was used for derivation of xenografts and cell lines. Exome sequencing was performed on the originating tumour and developed models. RNA sequencing, histological and functional analyses were employed to determine the relationship of the patient-derived models to clinical presentation of PDAC.

RESULTS

The cohort employed captured the genetic diversity of PDAC. From most cases, both cell lines and xenograft models were developed. Exome sequencing confirmed preservation of the primary tumour mutations in developed cell lines, which remained stable with extended passaging. The level of genetic conservation in the cell lines was comparable to that observed with patient-derived xenograft (PDX) models. Unlike historically established PDAC cancer cell lines, patient-derived models recapitulated the histological architecture of the primary tumour and exhibited metastatic spread similar to that observed clinically. Detailed genetic analyses of tumours and derived models revealed features of ex vivo evolution and the clonal architecture of PDAC. Functional analysis was used to elucidate therapeutic vulnerabilities of relevance to treatment of PDAC.

CONCLUSIONS

These data illustrate that with the appropriate methods it is possible to develop cell lines that maintain genetic features of PDAC. Such models serve as important substrates for analysing the significance of genetic variants and create a unique biorepository of annotated cell lines and xenografts that were established simultaneously from same primary tumour. These models can be used to infer genetic and empirically determined therapeutic sensitivities that would be germane to the patient.

IL-6 and PD-L1 antibody blockade combination therapy reduces tumour progression in murine models of pancreatic cancer

OBJECTIVE

Limited efficacy of immune checkpoint inhibitors in pancreatic ductal adenocarcinoma (PDAC) has prompted investigation into combination therapy. We hypothesised that interleukin 6 (IL-6) blockade would modulate immunological features of PDAC and enhance the efficacy of anti-programmed death-1-ligand 1 (PD-L1) checkpoint inhibitor therapy.

DESIGN

Transcription profiles and IL-6 secretion from primary patient-derived pancreatic stellate cells (PSCs) were analyzed via Nanostring and immunohistochemistry, respectively. In vivo efficacy and mechanistic studies were conducted with antibodies (Abs) targeting IL-6, PD-L1, CD4 or CD8 in subcutaneous or orthotopic models using Panc02, MT5 or KPC-luc cell lines; and the aggressive, genetically engineered PDAC model (Kras^LSL-G12D, Trp53^LSL-R270H, Pdx1-cre, Brca2^F/F (KPC-Brca2 mice)). Systemic and local changes in immunophenotype were measured by flow cytometry or immunohistochemical analysis.

RESULTS

PSCs (n=12) demonstrated prominent IL-6 expression, which was localised to stroma of tumours. Combined IL-6 and PD-L1 blockade elicited efficacy in mice bearing subcutaneous MT5 (p<0.02) and Panc02 tumours (p=0.046), which was accompanied by increased intratumoural effector T lymphocytes (CD62L^-CD44^-). CD8-depleting but not CD4-depleting Abs abrogated the efficacy of combined IL-6 and PD-L1 blockade in mice bearing Panc02 tumours (p=0.0016). This treatment combination also elicited significant antitumour activity in mice bearing orthotopic KPC-luc tumours and limited tumour progression in KPC-Brca2 mice (p<0.001). Histological analysis revealed increased T-cell infiltration and reduced α-smooth muscle actin cells in tumours from multiple models. Finally, IL-6 and PD-L1 blockade increased overall survival in KPC-Brca2 mice compared with isotype controls (p=0.0012).

CONCLUSIONS

These preclinical results indicate that targeted inhibition of IL-6 may enhance the efficacy of anti-PD-L1 in PDAC.

Metabolic biomarker signature to differentiate pancreatic ductal adenocarcinoma from chronic pancreatitis

OBJECTIVE

Current non-invasive diagnostic tests can distinguish between pancreatic cancer (pancreatic ductal adenocarcinoma (PDAC)) and chronic pancreatitis (CP) in only about two thirds of patients. We have searched for blood-derived metabolite biomarkers for this diagnostic purpose.

DESIGN

For a case-control study in three tertiary referral centres, 914 subjects were prospectively recruited with PDAC (n=271), CP (n=282), liver cirrhosis (n=100) or healthy as well as non-pancreatic disease controls (n=261) in three consecutive studies. Metabolomic profiles of plasma and serum samples were generated from 477 metabolites identified by gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.

RESULTS

A biomarker signature (nine metabolites and additionally CA19-9) was identified for the differential diagnosis between PDAC and CP. The biomarker signature distinguished PDAC from CP in the training set with an area under the curve (AUC) of 0.96 (95% CI 0.93-0.98). The biomarker signature cut-off of 0.384 at 85% fixed specificity showed a sensitivity of 94.9% (95% CI 87.0%-97.0%). In the test set, an AUC of 0.94 (95% CI 0.91-0.97) and, using the same cut-off, a sensitivity of 89.9% (95% CI 81.0%-95.5%) and a specificity of 91.3% (95% CI 82.8%-96.4%) were achieved, successfully validating the biomarker signature.

CONCLUSIONS

In patients with CP with an increased risk for pancreatic cancer (cumulative incidence 1.95%), the performance of this biomarker signature results in a negative predictive value of 99.9% (95% CI 99.7%-99.9%) (training set) and 99.8% (95% CI 99.6%-99.9%) (test set). In one third of our patients, the clinical use of this biomarker signature would have improved diagnosis and treatment stratification in comparison to CA19-9.

Dynamic landscape of pancreatic carcinogenesis reveals early molecular networks of malignancy

OBJECTIVE

The initial steps of pancreatic regeneration versus carcinogenesis are insufficiently understood. Although a combination of oncogenic Kras and inflammation has been shown to induce malignancy, molecular networks of early carcinogenesis remain poorly defined.

DESIGN

We compared early events during inflammation, regeneration and carcinogenesis on histological and transcriptional levels with a high temporal resolution using a well-established mouse model of pancreatitis and of inflammation-accelerated Kras^G12D-driven pancreatic ductal adenocarcinoma. Quantitative expression data were analysed and extensively modelled in silico.

RESULTS

We defined three distinctive phases-termed inflammation, regeneration and refinement-following induction of moderate acute pancreatitis in wild-type mice. These corresponded to different waves of proliferation of mesenchymal, progenitor-like and acinar cells. Pancreas regeneration required a coordinated transition of proliferation between progenitor-like and acinar cells. In mice harbouring an oncogenic Kras mutation and challenged with pancreatitis, there was an extended inflammatory phase and a parallel, continuous proliferation of mesenchymal, progenitor-like and acinar cells. Analysis of high-resolution transcriptional data from wild-type animals revealed that organ regeneration relied on a complex interaction of a gene network that normally governs acinar cell homeostasis, exocrine specification and intercellular signalling. In mice with oncogenic Kras, a specific carcinogenic signature was found, which was preserved in full-blown mouse pancreas cancer.

CONCLUSIONS

These data define a transcriptional signature of early pancreatic carcinogenesis and a molecular network driving formation of preneoplastic lesions, which allows for more targeted biomarker development in order to detect cancer earlier in patients with pancreatitis.

Guide to managing persistent upper gastrointestinal symptoms during and after treatment for cancer

BACKGROUND

Guidance: the practical management of the gastrointestinal symptoms of pelvic radiation disease was published in 2014 for a multidisciplinary audience. Following this, a companion guide to managing upper gastrointestinal (GI) consequences was developed.

AIMS

The development and peer review of an algorithm which could be accessible to all types of clinicians working with patients experiencing upper GI symptoms following cancer treatment.

METHODS

Experts who manage patients with upper GI symptoms were asked to review the guide, rating each section for agreement with the recommended measures and suggesting amendments if necessary. Specific comments were discussed and incorporated as appropriate, and this process was repeated for a second round of review.

RESULTS

21 gastroenterologists, 11 upper GI surgeons, 9 specialist dietitians, 8 clinical nurse specialists, 5 clinical oncologists, 3 medical oncologists and 4 others participated in the review. Consensus (defined prospectively as 60% or more panellists selecting 'strongly agree' or 'agree') was reached for all of the original 31 sections in the guide, with a median of 90%. 85% of panellists agreed that the guide was acceptable for publication or acceptable with minor revisions. 56 of the original 61 panellists participated in round 2. 93% agreed it was acceptable for publication after the first revision. Further minor amendments were made in response to round 2.

CONCLUSIONS

Feedback from the panel of experts developed the guide with improvement of occasional algorithmic steps, a more user-friendly layout, clearer time frames for referral to other teams and addition of procedures to the appendix.

Fukuoka criteria accurately predict risk for adverse outcomes during follow-up of pancreatic cysts presumed to be intraductal papillary mucinous neoplasms

OBJECTIVE

Fukuoka consensus guidelines classify pancreatic cystic lesions (PCLs) presumed to be intraductal papillary mucinous neoplasms (IPMNs) into Fukuoka positive (FP) (subgroups of high-risk (HR) and worrisome features (WFs)) and Fukuoka negative (FN) (non-HR feature/WF cysts). We retrospectively estimated 5-year risk of pancreatic cancer (PC) in FN, WF and HR cysts of patients with PCL-IPMN.

DESIGN

From Mayo Clinic databases, we randomly selected 2000 patients reported to have a PCL; we excluded inflammatory or suspected non-IPMN cysts and those without imaging follow-up. We re-reviewed cross-sectional imaging and abstracted clinical and follow-up data on PCL-IPMNs. The study contained 802 patients with FN cysts and 358 with FP cysts.

RESULTS

Patients with PCL-IPMN had median (IQR) follow-up of 4.2 (1.8-7.1) years. Among FN cysts, 5-year PC risk was low (2-3%) regardless of cyst size (p=0.67). After excluding events in the first 6 months, 5-year PC risk remained low (0-2%) regardless of cyst size (p=0.61). Among FP cysts, HR cysts (n=66) had greater 5-year PC risk than WF cysts (n=292) (49.7% vs 4.1%; p<0.001). In HR cysts, 3-year PC risk was greatest for obstructive jaundice versus enhancing solid component or main pancreatic duct >10 mm (79.8% vs 37.3% vs 39.4%, respectively; p=0.01).

CONCLUSIONS

Fukuoka guidelines accurately stratify PCL-IPMNs for PC risk, with FN cysts having lowest and HR cysts having greatest risk. After 6-month follow-up, WF and FN cysts had a low 5-year PC risk. Surveillance strategies should be tailored appropriately.

Digital next-generation sequencing identifies low-abundance mutations in pancreatic juice samples collected from the duodenum of patients with pancreatic cancer and intraductal papillary mucinous neoplasms

OBJECTIVE

Secretin-stimulated pancreatic juice contains DNA shed from cells lining the pancreatic ducts. Genetic analysis of this fluid may form a test to detect pancreatic ductal neoplasia.

DESIGN

We employed digital next-generation sequencing ('digital NGS') to detect low-abundance mutations in secretin-stimulated juice samples collected from the duodenum of subjects enrolled in Cancer of the Pancreas Screening studies at Johns Hopkins Hospital. For each juice sample, digital NGS necessitated 96 NGS reactions sequencing nine genes. The study population included 115 subjects (53 discovery, 62 validation) (1) with pancreatic ductal adenocarcinoma (PDAC), (2) intraductal papillary mucinous neoplasm (IPMN), (3) controls with non-suspicious pancreata.

RESULTS

Cases with PDAC and IPMN were more likely to have mutant DNA detected in pancreatic juice than controls (both p<0.0001); mutant DNA concentrations were higher in patients with PDAC than IPMN (p=0.003) or controls (p<0.001). TP53 and/or SMAD4 mutations were commonly detected in juice samples from patients with PDAC and were not detected in controls (p<0.0001); mutant TP53/SMAD4 concentrations could distinguish PDAC from IPMN cases with 32.4% sensitivity, 100% specificity (area under the curve, AUC 0.73, p=0.0002) and controls (AUC 0.82, p<0.0001). Two of four patients who developed pancreatic cancer despite close surveillance had SMAD4/TP53 mutations from their cancer detected in juice samples collected over 1 year prior to their pancreatic cancer diagnosis when no suspicious pancreatic lesions were detected by imaging.

CONCLUSIONS

The detection in pancreatic juice of mutations important for the progression of low-grade dysplasia to high-grade dysplasia and invasive pancreatic cancer may improve the management of patients undergoing pancreatic screening and surveillance.

GATA6 regulates EMT and tumour dissemination, and is a marker of response to adjuvant chemotherapy in pancreatic cancer

BACKGROUND AND AIMS

The role of GATA factors in cancer has gained increasing attention recently, but the function of GATA6 in pancreatic ductal adenocarcinoma (PDAC) is controversial. GATA6 is amplified in a subset of tumours and was proposed to be oncogenic, but high GATA6 levels are found in well-differentiated tumours and are associated with better patient outcome. By contrast, a tumour-suppressive function of GATA6 was demonstrated using genetic mouse models. We aimed at clarifying GATA6 function in PDAC.

DESIGN

We combined GATA6 silencing and overexpression in PDAC cell lines with GATA6 ChIP-Seq and RNA-Seq data, in order to understand the mechanism of GATA6 functions. We then confirmed some of our observations in primary patient samples, some of which were included in the ESPAC-3 randomised clinical trial for adjuvant therapy.

RESULTS

GATA6 inhibits the epithelial-mesenchymal transition (EMT) in vitro and cell dissemination in vivo. GATA6 has a unique proepithelial and antimesenchymal function, and its transcriptional regulation is direct and implies, indirectly, the regulation of other transcription factors involved in EMT. GATA6 is lost in tumours, in association with altered differentiation and the acquisition of a basal-like molecular phenotype, consistent with an epithelial-to-epithelial (ET2) transition. Patients with basal-like GATA6low tumours have a shorter survival and have a distinctly poor response to adjuvant 5-fluorouracil (5-FU)/leucovorin. However, modulation of GATA6 expression in cultured cells does not directly regulate response to 5-FU.

CONCLUSIONS

We provide mechanistic insight into GATA6 tumour-suppressive function, its role as a regulator of canonical epithelial differentiation, and propose that loss of GATA6 expression is both prognostic and predictive of response to adjuvant therapy.

Tumor-Targeting Salmonella typhimurium A1-R Promotes Tumoricidal CD8+ T Cell Tumor Infiltration and Arrests Growth and Metastasis in a Syngeneic Pancreatic-Cancer Orthotopic Mouse Model

The present study determined the effect of the tumor-targeting strain Salmonella typhimurium A1-R (S. typhimurium A1-R) on CD8⁺ tumor-infiltrating lymphocytes (TILs) in a syngeneic pancreatic-cancer orthotopic mouse model. The effect of tumor-targeting S. typhimurium A1-R on CD8⁺ TILs was determined on the Pan02 murine pancreatic-adenocarcinoma implanted orthotopically in the pancreatic tail of C57BL/6 immunocompromised mice. Three weeks after orthotopic implantation, mice were randomized as follows G1: untreated control group (n = 8); and G2: S. typhimurium A1-R-treatment group (n = 8, 1 × 10⁷ colony forming units [CFU]/body, iv, weekly, 3 weeks). On the 22nd day from initial treatment, all mice were sacrificed and tumors were harvested. The tumor-volume ratio was defined as ratio of tumor volume on the 22nd day relative to the 1st day. The tumor volume ratio was significantly lower in the S. typhimurium A1-R-treated group (G2) (3.0 ± 2.8) than the untreated control (G1) (39.9 ± 30.7, P < 0.01). Hematoxylin and easin (H&E) staining on tumor sections was performed to evaluate tumor destruction which was classified according to the Evans grading system and found to be much greater in the S. typhimurium A1-R-treated mice (G2). Six mice in G1 had peritoneal dissemination, whereas no mice showed peritoneal dissemination in G2 (P < 0.01). Immunohistochemical staining with anti-mouse CD8⁺ antibody was performed in order to detect TILs determined by calculating the average number of CD8⁺ cells in three high power fields (200×) in the treated and untreated tumors. The TIL score was significantly higher in G2 (133.5 ± 32.2) than G1 (45.1 ± 19.4, P < 0.001). The present study demonstrates that S. typhimurium A1-R promotes CD8⁺ T cell infiltration and inhibition of tumor growth and metastasis. J. Cell. Biochem. 119: 634-639, 2018. © 2017 Wiley Periodicals, Inc.

Pharmacological macrophage inhibition decreases metastasis formation in a genetic model of pancreatic cancer

OBJECTIVES

Tumour-associated macrophages play an important role in mediating tumour progression. In pancreatic cancer, infiltrating macrophages are known to mediate tumour progression and have been identified in invasive tumours and in early preinvasive pancreatic intraepithelial precursor lesions. We aimed to study the impact of pharmacological macrophage depletion by liposomal clodronate in a genetic mouse model of pancreatic cancer.

METHODS

KPC mice (LSL-Kras^G12D/+;LSL-Trp53^R172H/+;Pdx-1-Cre) were treated for 12 weeks with liposomal clodronate or control liposomes. Tumour and metastasis formation as well as alterations in local and circulating immune cells and cytokines were analysed.

RESULTS

Treatment with liposomal clodronate effectively reduced CD11b-positive macrophages both in the pancreas and other organs such as liver, lung and spleen. While tumour incidence and growth were only slightly reduced, metastasis formation in the liver and lungs was significantly diminished after macrophage depletion. This antimetastatic effect was independent of the presence of an endogenous primary tumour, since reduced pulmonary colonisation was also detected in clodronate-pretreated mice after tail vein injection of syngeneic pancreatic cancer cell lines. Macrophage inhibition by liposomal clodronate was associated with significantly impaired angiogenesis, reduced circulating vascular endothelial growth factor levels and decreased circulating CD4+CD25+ T cells. These alterations could be confirmed in an independent macrophage depletion model using CD11b-diphtheria toxin receptor mice.

CONCLUSIONS

Pharmacological depletion of macrophages in a genetic mouse model of pancreatic cancer markedly reduced metastasis formation and is associated with impaired angiogenesis and reduced CD4+CD25+ T cell levels. Pharmacological targeting of infiltrating macrophages represents a promising novel tool for antimetastatic therapeutic approaches.

Clinicopathological significance of Necl-4 expression in pancreatic ductal adenocarcinoma

AIMS

The loss, or decreased expression, of nectin-like molecule 4 (Necl-4; an immunoglobulin-like cell adhesion molecule) is reported to be associated with the development and progression of certain types of cancer. We investigated the clinicopathological significance of Necl-4 expression in patients with pancreatic ductal adenocarcinoma (PDAC).

METHODS

Immunohistochemical analyses of Necl-4 (n=258) and E-cadherin (n=256) expression were performed using tissue microarray blocks of PDAC samples. Necl-4 expression of 38 pancreatic intraepithelial neoplasia (PanIN) lesions included in tissue microarray cores was also evaluated. Necl-4 and E-cadherin expression was considered positive if >30% of cells were stained, and negative if ≤30% of cells were stained.

RESULTS

Necl-4 expression was positive in 45.7% (n=118) and negative in 54.3% (n=140) of PDAC cases. Necl-4 staining was positive in 96.7% (n=29) and negative in 3.3% (n=1) of low-grade PanIN cases, and positive in 62.5% (n=5) and negative in 37.5% (n=3) of high-grade PanIN cases. The number of cases with positive Necl-4 expression decreased in the order low-grade PanIN>high-grade PanIN>PDAC (p<0.001). Negative Necl-4 expression was significantly associated with a larger tumour size of >30 mm, perineural invasion, lymphatic involvement, lymph node metastasis (pN1), an advanced TNM (tumour, node, metastases) stage (stage IIB-IV), an advanced histological grade (G2/3), and shorter overall survival. E-cadherin staining was positive in 46.1% (n=118) and negative in 53.9% (n=138) of PDAC cases. Necl-4 expression correlated positively with E-cadherin expression (r=0.405, p<0.001).

CONCLUSIONS

The results suggest that Necl-4 is associated with carcinogenesis and aggressiveness of PDAC.

Leucocyte telomere length, genetic variants at the TERT gene region and risk of pancreatic cancer

OBJECTIVE

Telomere shortening occurs as an early event in pancreatic tumorigenesis, and genetic variants at the telomerase reverse transcriptase (TERT) gene region have been associated with pancreatic cancer risk. However, it is unknown whether prediagnostic leucocyte telomere length is associated with subsequent risk of pancreatic cancer.

DESIGN

We measured prediagnostic leucocyte telomere length in 386 pancreatic cancer cases and 896 matched controls from five prospective US cohorts. ORs and 95% CIs were calculated using conditional logistic regression. Matching factors included year of birth, cohort (which also matches on sex), smoking status, fasting status and month/year of blood collection. We additionally examined single-nucleotide polymorphisms (SNPs) at the TERT region in relation to pancreatic cancer risk and leucocyte telomere length using logistic and linear regression, respectively.

RESULTS

Shorter prediagnostic leucocyte telomere length was associated with higher risk of pancreatic cancer (comparing extreme quintiles of telomere length, OR 1.72; 95% CI 1.07 to 2.78; p_trend=0.048). Results remained unchanged after adjustment for diabetes, body mass index and physical activity. Three SNPs at TERT (linkage disequilibrium r²<0.25) were associated with pancreatic cancer risk, including rs401681 (per minor allele OR 1.33; 95% CI 1.12 to 1.59; p=0.002), rs2736100 (per minor allele OR 1.36; 95% CI 1.13 to 1.63; p=0.001) and rs2736098 (per minor allele OR 0.75; 95% CI 0.63 to 0.90; p=0.002). The minor allele for rs401681 was associated with shorter telomere length (p=0.023).

CONCLUSIONS

Prediagnostic leucocyte telomere length and genetic variants at the TERT gene region were associated with risk of pancreatic cancer.

Comprehensive Dissection of Transcriptome Data and Regulatory Factors in Pancreatic Cancer Cells

Features of pancreatic cancers include high mortality rates caused by rapid tumor progression and a lack of effective therapy. Underpinning the molecular mechanisms involved in the alteration of the gene expression program in the pancreatic cancer remains to be understood. In the current study, we performed a comprehensive analysis using 282 pancreatic tumor and normal samples from seven independent expression data sets to provide a better view on the interactions between different transcription factors (TFs) and the most affected biological pathways in pancreatic cancer. We highlighted common differentially expressed genes (DEGs) and common affected processes within pancreatic cancer samples. We revealed 16 main DE-TFs that regulated gene expression alterations as well as the most significant processes in pancreatic cancer compared to normal cells. For example, we found the upregulated FOXM1 to be a top regulator of pancreatic cellular transformation based on results from different analyses, including from its regulation of gene regulatory networks, its presence in protein complex, its significant regulation of genes related to cancer pathways, and its regulation of most of the identified DE-TFs. Furthermore, we provided a model and assessed the role of different DE-TFs in the regulation of the most affected pancreatic- and cancer-specific processes. In conclusion, our bioinformatics meta-analysis of high throughput expression data sets, besides clarifying common affected genes and pathways, also showed the mechanisms involved in regulating these common profiles. Our results, especially for DE-TFs, could potentially be useful for screening for pancreatic cancer, and for confirming or determining novel pharmacological targets. J. Cell. Biochem. 118: 3976-3985, 2017. © 2017 Wiley Periodicals, Inc.

Low progression of intraductal papillary mucinous neoplasms with worrisome features and high-risk stigmata undergoing non-operative management: a mid-term follow-up analysis

OBJECTIVE

To evaluate mid-term outcomes and predictors of survival in non-operated patients with pancreatic intraductal papillary mucinous neoplasms (IPMNs) with worrisome features or high-risk stigmata as defined by International Consensus Guidelines for IPMN. Reasons for non-surgical options were physicians' recommendation, patient personal choice or comorbidities precluding surgery.

METHODS

In this retrospective, multicentre analysis, IPMNs were classified as branch duct (BD) and main duct (MD), the latter including mixed IPMNs. Univariate and multivariate analysis for overall survival (OS) and disease-specific survival (DSS) were obtained.

RESULTS

Of 281 patients identified, 159 (57%) had BD-IPMNs and 122 (43%) had MD-IPMNs; 50 (18%) had high-risk stigmata and 231 (82%) had worrisome features. Median follow-up was 51 months. The 5-year OS and DSS for the entire cohort were 81% and 89.9%. An invasive pancreatic malignancy developed in 34 patients (12%); 31 had invasive IPMNs (11%) and 3 had IPMN-distinct pancreatic ductal adenocarcinoma (1%). Independent predictors of poor DSS in the entire cohort were age >70 years, atypical/malignant cyst fluid cytology, jaundice and MD >15 mm. Compared with MD-IPMNs, BD-IPMNs had significantly better 5-year OS (86% vs 74.1%, p=0.002) and DSS (97% vs 81.2%, p<0.0001). Patients with worrisome features had better 5-year DSS compared with those with high-risk stigmata (96.2% vs 60.2%, p<0.0001).

CONCLUSIONS

In elderly patients with IPMNs that have worrisome features, the 5-year DSS is 96%, suggesting that conservative management is appropriate. By contrast, presence of high-risk stigmata is associated with a 40% risk of IPMN-related death, reinforcing that surgical resection should be offered to fit patients.

Myeloid cells are required for PD-1/PD-L1 checkpoint activation and the establishment of an immunosuppressive environment in pancreatic cancer

BACKGROUND

Pancreatic cancer is characterised by the accumulation of a fibro-inflammatory stroma. Within this stromal reaction, myeloid cells are a predominant population. Distinct myeloid subsets have been correlated with tumour promotion and unmasking of anti-tumour immunity.

OBJECTIVE

The goal of this study was to determine the effect of myeloid cell depletion on the onset and progression of pancreatic cancer and to understand the relationship between myeloid cells and T cell-mediated immunity within the pancreatic cancer microenvironment.

METHODS

Primary mouse pancreatic cancer cells were transplanted into CD11b-diphtheria toxin receptor (DTR) mice. Alternatively, the iKras* mouse model of pancreatic cancer was crossed into CD11b-DTR mice. CD11b+ cells (mostly myeloid cell population) were depleted by diphtheria toxin treatment during tumour initiation or in established tumours.

RESULTS

Depletion of myeloid cells prevented KrasG12D-driven pancreatic cancer initiation. In pre-established tumours, myeloid cell depletion arrested tumour growth and in some cases, induced tumour regressions that were dependent on CD8+ T cells. We found that myeloid cells inhibited CD8+ T-cell anti-tumour activity by inducing the expression of programmed cell death-ligand 1 (PD-L1) in tumour cells in an epidermal growth factor receptor (EGFR)/mitogen-activated protein kinases (MAPK)-dependent manner.

CONCLUSION

Our results show that myeloid cells support immune evasion in pancreatic cancer through EGFR/MAPK-dependent regulation of PD-L1 expression on tumour cells. Derailing this crosstalk between myeloid cells and tumour cells is sufficient to restore anti-tumour immunity mediated by CD8+ T cells, a finding with implications for the design of immune therapies for pancreatic cancer.

Epigenetic treatment of pancreatic cancer: is there a therapeutic perspective on the horizon?

Pancreatic ductal adenocarcinoma (PDAC) constitutes one of the most aggressive malignancies with a 5-year survival rate of <7%. Due to growing incidence, late diagnosis and insufficient treatment options, PDAC is predicted to soon become one of the leading causes of cancer-related death. Although intensified cytostatic combinations, particularly gemcitabine plus nab-paclitaxel and the folinic acid, fluorouracil, irinotecan, oxaliplatin (FOLFIRINOX) protocol, provide some improvement in efficacy and survival compared with gemcitabine alone, a breakthrough in the treatment of metastatic pancreatic cancer remains out of sight. Nevertheless, recent translational research activities propose that either modulation of the immune response or pharmacological targeting of epigenetic modifications alone, or in combination with chemotherapy, might open highly powerful therapeutic avenues in GI cancer entities, including pancreatic cancer. Deregulation of key epigenetic factors and chromatin-modifying proteins, particularly those responsible for the addition, removal or recognition of post-translational histone modifications, are frequently found in human pancreatic cancer and hence constitute particularly exciting treatment opportunities. This review summarises both current clinical trial activities and discovery programmes initiated throughout the biopharma landscape, and critically discusses the chances, hurdles and limitations of epigenetic-based therapy in future PDAC treatment.

Tumour-specific delivery of siRNA-coupled superparamagnetic iron oxide nanoparticles, targeted against PLK1, stops progression of pancreatic cancer

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies and is projected to be the second leading cause of cancer-related death by 2030. Despite extensive knowledge and insights into biological properties and genetic aberrations of PDAC, therapeutic options remain temporary and ineffective. One plausible explanation for the futile response to therapy is an insufficient and non-specific delivery of anticancer drugs to the tumour site.

DESIGN

Superparamagnetic iron oxide nanoparticles (SPIONs) coupled with siRNA directed against the cell cycle-specific serine-threonine-kinase, Polo-like kinase-1 (siPLK1-StAv-SPIONs), could serve a dual purpose for delivery of siPLK1 to the tumour and for non-invasive assessment of efficiency of delivery in vivo by imaging the tumour response. siPLK1-StAv-SPIONs were designed and synthesised as theranostics to function via a membrane translocation peptide with added advantage of driving endosomal escape for mediating transportation to the cytoplasm (myristoylated polyarginine peptides) as well as a tumour-selective peptide (EPPT1) to increase intracellular delivery and tumour specificity, respectively.

RESULTS

A syngeneic orthotopic as well as an endogenous cancer model was treated biweekly with siPLK1-StAv-SPIONs and tumour growth was monitored by small animal MRI. In vitro and in vivo experiments using a syngeneic orthotopic PDAC model as well as the endogenous LSL-KrasG12D, LSL-Trp53R172H, Pdx-1-Cre model revealed significant accumulation of siPLK1-StAv-SPIONs in PDAC, resulting in efficient PLK1 silencing. Tumour-specific silencing of PLK1 halted tumour growth, marked by a decrease in tumour cell proliferation and an increase in apoptosis.

CONCLUSIONS

Our data suggest siPLK1-StAv-SPIONs with dual specificity residues for tumour targeting and membrane translocation to represent an exciting opportunity for targeted therapy in patients with PDAC.

Control of Apoptosis in Treatment and Biology of Pancreatic Cancer

Pancreatic cancer is estimated to be the 12th most common cancer in the United States in 2014 and yet this malignancy is the fourth leading cause of cancer-related death in the United States. Late detection and resistance to therapy are the major causes for its dismal prognosis. Apoptosis is an actively orchestrated cell death mechanism that serves to maintain tissue homoeostasis. Cancer develops from normal cells by accruing significant changes through one or more mechanisms, leading to DNA damage and mutations, which in a normal cell would induce this programmed cell death pathway. As a result, evasion of apoptosis is one of the hallmarks of cancer cells. PDAC is notoriously resistant to apoptosis, thereby explaining its aggressive nature and resistance to conventional treatment modalities. The current review is focus on understanding different intrinsic and extrinsic pathways in pancreatic cancer that may affect apoptosis in this disease.

Dual prognostic significance of tumour-associated macrophages in human pancreatic adenocarcinoma treated or untreated with chemotherapy

OBJECTIVE

Tumour-associated macrophages (TAMs) play key roles in tumour progression. Recent evidence suggests that TAMs critically modulate the efficacy of anticancer therapies, raising the prospect of their targeting in human cancer.

DESIGN

In a large retrospective cohort study involving 110 patients with pancreatic ductal adenocarcinoma (PDAC), we assessed the density of CD68-TAM immune reactive area (%IRA) at the tumour-stroma interface and addressed their prognostic relevance in relation to postsurgical adjuvant chemotherapy (CTX). In vitro, we dissected the synergism of CTX and TAMs.

RESULTS

In human PDAC, TAMs predominantly exhibited an immunoregulatory profile, characterised by expression of scavenger receptors (CD206, CD163) and production of interleukin 10 (IL-10). Surprisingly, while the density of TAMs associated to worse prognosis and distant metastasis, CTX restrained their protumour prognostic significance. High density of TAMs at the tumour-stroma interface positively dictated prognostic responsiveness to CTX independently of T-cell density. Accordingly, in vitro, gemcitabine-treated macrophages became tumoricidal, activating a cytotoxic gene expression programme, inhibiting their protumoural effect and switching to an antitumour phenotype. In patients with human PDAC, neoadjuvant CTX was associated to a decreased density of CD206(+) and IL-10(+) TAMs at the tumour-stroma interface.

CONCLUSIONS

Overall, our data highlight TAMs as critical determinants of prognostic responsiveness to CTX and provide clinical and in vitro evidence that CTX overall directly re-educates TAMs to restrain tumour progression. These results suggest that the quantification of TAMs could be exploited to select patients more likely to respond to CTX and provide the basis for novel strategies aimed at re-educating macrophages in the context of CTX.

Regression grading in neoadjuvant treated pancreatic cancer: an interobserver study

AIM

Several regression grading systems have been proposed for neoadjuvant chemoradiation-treated pancreatic ductal adenocarcinoma (PDAC). This study aimed to examine the utility, reproducibility and level of concordance of three most frequently used grading systems.

METHODS

Four gastrointestinal pathologists used the College of American Pathologists (CAP), Evans, MD Anderson Cancer Centre (MDA) regression grading systems to grade 14 selected cases (7-20 slides from each case) of neoadjuvant chemoradiation-treated PDAC. A postscoring discussion with each pathologist was conducted. The results were entered into a standardised data collection form and statistical analyses were performed.

RESULTS

There was little concordance across the three systems. The Kendall coefficient of concordance agreement scores were: CAP: 2-poor, 2-fair; Evans: 1-fair, 1-moderate, 2-good; MDA: 1-poor, 2-moderate, 1-good. Interpretation in all three grades in the CAP grading system was a source of discrepancy. Furthermore, using fibrosis as a criterion to assess regression was contentious. In the Evans system, quantifying tumour destruction using arbitrary percentage cut-offs (ie, 9% vs 10%; 50% vs 51%, etc) was imprecise and subjective. Although the MDA system generated greatest concordance, this was due to 'oversimplification' surrounding wide, arbitrarily assigned thresholds of </> 5% of tumour.

CONCLUSIONS

All systems lacked precision and clarity for accurate regression grading. Presently the clinical utility and impact of histological regression grading in patient management is questionable. There is a need to re-evaluate regression grading in the pancreas and establish a reproducible, clinically relevant grading system.

Inhibition of Pancreatic Cancer Cell-Induced Paracrine Hedgehog Signaling by Liver X Receptor Agonists and Oxy16, a Naturally Occurring Oxysterol

The widespread involvement of the Hedgehog (Hh) signaling pathway in human malignancies has driven efforts to develop Hh pathway inhibitors as anti-cancer agents. The majority of these agents antagonize Smoothened (Smo), a plasma membrane-associated signal transducer molecule. However, several such Smo antagonists have failed in clinical trials to benefit patients with cancers that arise from aberrant Hh signaling (which often bypasses Smo). In this study, we report that a naturally occurring oxysterol, 20α, 22(R)-dihydroxycholesterol (Oxy16), a known metabolite in the biosynthesis of steroid hormones, strongly inhibits Hh signaling induced in C3H10T1/2 embryonic fibroblasts and NIH3T3-E1 fibroblasts through a mechanism that is independent of liver X receptor (LXR) activation. We demonstrate that Oxy16 inhibits Hh signaling in Suppressor of Fused (Sufu) null mouse embryonic fibroblast (MEF) cells, indicating that its inhibitory effect on Hh signaling is epistatic to Sufu. We further demonstrate that Oxy16 inhibits Gli1 transcriptional activity in NIH3T3-E1 cells overexpressing Gli1 and a Gli-dependent reporter construct. Altogether, data presented here suggest that Oxy16 may be a suitable starting point for the development of new drugs that inhibit Hh signaling downstream of Smo. By targeting aberrant Hh signaling, such novel Hh pathway inhibitors could significantly broaden the range of clinical applications compared to existing Smo antagonists. Furthermore, the present study adds a new facet to the spectrum of Hh pathway modulation that naturally occurring oxysterol derivatives are capable of, ranging from allosteric activation of the pathway via Smo binding to inhibition of the pathway downstream of Smo. J. Cell. Biochem. 118: 499-509, 2017. © 2016 Wiley Periodicals, Inc.

A multicentre comparative prospective blinded analysis of EUS and MRI for screening of pancreatic cancer in high-risk individuals

OBJECTIVE

Endoscopic ultrasonography (EUS) and MRI are promising tests to detect precursors and early-stage pancreatic ductal adenocarcinoma (PDAC) in high-risk individuals (HRIs). It is unclear which screening technique is to be preferred. We aimed to compare the efficacy of EUS and MRI in their ability to detect clinically relevant lesions in HRI.

DESIGN

Multicentre prospective study. The results of 139 asymptomatic HRI (>10-fold increased risk) undergoing first-time screening by EUS and MRI are described. Clinically relevant lesions were defined as solid lesions, main duct intraductal papillary mucinous neoplasms and cysts ≥10 mm. Results were compared in a blinded, independent fashion.

RESULTS

Two solid lesions (mean size 9 mm) and nine cysts ≥10 mm (mean size 17 mm) were detected in nine HRI (6%). Both solid lesions were detected by EUS only and proved to be a stage I PDAC and a multifocal pancreatic intraepithelial neoplasia 2. Of the nine cysts ≥10 mm, six were detected by both imaging techniques and three were detected by MRI only. The agreement between EUS and MRI for the detection of clinically relevant lesions was 55%. Of these clinically relevant lesions detected by both techniques, there was a good agreement for location and size.

CONCLUSIONS

EUS and/or MRI detected clinically relevant pancreatic lesions in 6% of HRI. Both imaging techniques were complementary rather than interchangeable: contrary to EUS, MRI was found to be very sensitive for the detection of cystic lesions of any size; MRI, however, might have some important limitations with regard to the timely detection of solid lesions.

Refinement of screening for familial pancreatic cancer

OBJECTIVE

Surveillance programmes are recommended for individuals at risk (IAR) of familial pancreatic cancer (FPC) to detect early pancreatic cancer (pancreatic ductal adenocarcinoma, PDAC). However, the age to begin screening and the optimal screening protocol remain to be determined.

METHODS

IAR from non-CDKN2A FPC families underwent annual screening by MRI with endoscopic ultrasonography (EUS) in board-approved prospective screening programmes at three tertiary referral centres. The diagnostic yield according to age and different screening protocols was analysed.

RESULTS

253 IAR with a median age of 48 (25-81) years underwent screening with a median of 3 (1-11) screening visits during a median follow-up of 28 (1-152) months. 134 (53%) IAR revealed pancreatic lesions on imaging, mostly cystic (94%), on baseline or follow-up screening. Lesions were significantly more often identified in IAR above the age of 45 years (p<0.0001). In 21 IAR who underwent surgery, no significant lesions (PDAC, pancreatic intraepithelial neoplasia (PanIN) 3 lesions, high-grade intraductal papillary mucinous neoplasia (IPMN)) were detected before the age of 50 years. Potentially relevant lesions (multifocal PanIN2 lesions, low/moderate-grade branch-duct IPMNs) occurred also significantly more often after the age of 50 years (13 vs 2, p<0.0004). The diagnostic yield of potentially relevant lesions was not different between screening protocols using annual MRI with EUS (n=98) or annual MRI with EUS every 3rd year (n=198) and between IAR screened at intervals of 12 months (n=180) or IAR that decided to be screened at ≥24 months intervals (n=30).

CONCLUSIONS

It appears safe to start screening for PDAC in IAR of non-CDKN2a FPC families at the age of 50 years. MRI-based screening supplemented by EUS at baseline and every 3rd year or when changes in MRI occur appears to be efficient.

Pathogenesis of pancreatic cancer exosome-induced lipolysis in adipose tissue

BACKGROUND AND OBJECTIVES

New-onset diabetes and concomitant weight loss occurring several months before the clinical presentation of pancreatic cancer (PC) appear to be paraneoplastic phenomena caused by tumour-secreted products. Our recent findings have shown exosomal adrenomedullin (AM) is important in development of diabetes in PC. Adipose tissue lipolysis might explain early onset weight loss in PC. We hypothesise that lipolysis-inducing cargo is carried in exosomes shed by PC and is responsible for the paraneoplastic effects. Therefore, in this study we investigate if exosomes secreted by PC induce lipolysis in adipocytes and explore the role of AM in PC-exosomes as the mediator of this lipolysis.

DESIGN

Exosomes from patient-derived cell lines and from plasma of patients with PC and non-PC controls were isolated and characterised. Differentiated murine (3T3-L1) and human adipocytes were exposed to these exosomes to study lipolysis. Glycerol assay and western blotting were used to study lipolysis. Duolink Assay was used to study AM and adrenomedullin receptor (ADMR) interaction in adipocytes treated with exosomes.

RESULTS

In murine and human adipocytes, we found that both AM and PC-exosomes promoted lipolysis, which was abrogated by ADMR blockade. AM interacted with its receptor on the adipocytes, activated p38 and extracellular signal-regulated (ERK1/2) mitogen-activated protein kinases and promoted lipolysis by phosphorylating hormone-sensitive lipase. PKH67-labelled PC-exosomes were readily internalised into adipocytes and involved both caveolin and macropinocytosis as possible mechanisms for endocytosis.

CONCLUSIONS

PC-secreted exosomes induce lipolysis in subcutaneous adipose tissue; exosomal AM is a candidate mediator of this effect.

Activated Schwann cells in pancreatic cancer are linked to analgesia via suppression of spinal astroglia and microglia

OBJECTIVE

The impact of glia cells during GI carcinogenesis and in cancer pain is unknown. Here, we demonstrate a novel mechanism how Schwann cells (SCs) become activated in the pancreatic cancer (PCa) microenvironment and influence spinal activity and pain sensation.

DESIGN

Human SCs were exposed to hypoxia, to pancreatic cancer cells (PCCs) and/or to T-lymphocytes. Both SC and intrapancreatic nerves of patients with PCa with known pain severity were assessed for glial intermediate filament and hypoxia marker expression, proliferation and for transcriptional alterations of pain-related targets. In conditional PCa mouse models with selective in vivo blockade of interleukin (IL)-6 signalling (Ptf1a-Cre;LSL-Kras(G12D)/KC interbred with IL6(-/-) or sgp130(tg) mice), SC reactivity, abdominal mechanosensitivity and spinal glial/neuronal activity were quantified.

RESULTS

Tumour hypoxia, PCC and/or T-lymphocytes activated SC via IL-6-signalling in vitro. Blockade of the IL-6-signalling suppressed SC activation around PCa precursor lesions (pancreatic intraepithelial neoplasia (PanIN)) in KC;IL6(-/-) (32.06%±5.25% of PanINs) and KC;sgp130(tg) (55.84%±5.51%) mouse models compared with KC mice (78.27%±3.91%). Activated SCs were associated with less pain in human PCa and with decreased abdominal mechanosensitivity in KC mice (von Frey score of KC: 3.9±0.5 vs KC;IL6(-/-) mice: 5.9±0.9; and KC;sgp130(tg): 10.21±1.4) parallel to attenuation of spinal astroglial and/or microglial activity. Activated SC exhibited a transcriptomic profile with anti-inflammatory and anti-nociceptive features.

CONCLUSIONS

Activated SC in PCa recapitulate the hallmarks of 'reactive gliosis' and contribute to analgesia due to suppression of spinal glia. Our findings propose a mechanism for how cancer might remain pain-free via the SC-central glia interplay during cancer progression.