Prognosis In PDAC Research Articles

Identification of an unfolded protein response-related signature for predicting the prognosis of pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive lethal malignancy. An effective prognosis prediction model is urgently needed for treatment optimization. The differentially expressed unfolded protein response (UPR)‒related genes between pancreatic tumor and normal tissue were analyzed using the TCGA-PDAC dataset, and these genes that overlapped with UPR‒related prognostic genes from the E-MTAB-6134 dataset were further analyzed. Univariate, LASSO and multivariate Cox regression analyses were applied to establish a prognostic gene signature, which was evaluated by Kaplan‒Meier curve and receiver operating characteristic (ROC) analyses. E‒MTAB‒6134 was set as the training dataset, while TCGA-PDAC, GSE21501 and ICGC-PACA-AU were used for external validation. Subsequently, a nomogram integrating risk scores and clinical parameters was established, and gene set enrichment analysis (GSEA), tumor immunity analysis and drug sensitivity analysis were conducted. A UPR-related signature comprising twelve genes was constructed and divided PDAC patients into high- and low-risk groups based on the median risk score. The UPR-related signature accurately predicted the prognosis and acted as an independent prognostic factor of PDAC patients, and the AUCs of the UPR-related signature in predicting PDAC prognosis at 1, 2 and 3 years were all more than 0.7 in the training and validation datasets. The UPR-related signature showed excellent performance in outcome prediction even in different clinicopathological subgroups, including the female (p<0.0001), male (p<0.0001), grade 1/2 (p<0.0001), grade 3 (p=0.028), N0 (p=0.043), N1 (p<0.001), and R0 (p<0.0001) groups. Furthermore, multiple immune-related pathways were enriched in the low-risk group, and risk scores in the low-risk group were also associated with significantly higher levels of tumor-infiltrating lymphocytes (TILs). In addition, DepMap drug sensitivity analysis and our validation experiment showed that PDAC cell lines with high UPR-related risk scores or UPR activation are more sensitive to floxuridine, which is used as an antineoplastic agent. Herein, we identified a novel UPR-related prognostic signature that showed high value in predicting survival in patients with PDAC. Targeting these UPR-related genes might be an alternative for PDAC therapy. Further experimental studies are required to reveal how these genes mediate ER stress and PDAC progression.

Pancreatic ductal adenocarcinoma complete regression after preoperative chemotherapy: Surgical results in a small series

BackgroundPancreatic ductal adenocarcinoma (PDAC) becomes a systemic disease from an early stage. Complete surgical resection remains the only validated and potentially curative treatment; disappointingly only 20% of patients present with a resectable tumour. Although a complete pathological regression (pCR) after the preoperative chemotherapy could intuitively lead to better outcomes and prolonged survival some reports highlighted significant rates of recurrence. Cases PresentationWe describe three cases of pCR following preoperative chemotherapy for PDAC. The first two cases received neoadjuvant mFOLFIRINOX and PAX-G scheme for borderline resectable PDAC. Recurrence appeared 9 and 12 months after surgery. Although both patients started adjuvant therapy straight after the diagnosis of recurrence, the disease rapidly progressed and led them to death 12 and 15 months after surgery. The third case was characterized by germline BRCA2 mutation. The patient presented with PDAC of the body, intrapancreatic biliary stenosis and suspected peritoneal metastasis. One year later, after first and second-line chemotherapy, she underwent explorative laparoscopy and total spleno-pancreatectomy without evidence of viable tumour cells in the surgical specimen. At six months she is recurrence-free. ConclusionsVery few reports describe a complete pathological response following preoperative chemotherapy in pancreatic cancer. We observed three cases in the last three years with disappointing oncological results. Further investigations are needed to predict PDAC prognosis in pCR after chemotherapy.

Abstract C034: Bioinformatical identification of cancer-associated-fibroblasts with tumor cells pro-migratory crosstalks depending on activin

Abstract Pancreatic ductal adenocarcinoma (PDAC) aggressiveness results from its high metastatic and chemoresistance potential. Pancreatic cancer cells are immersed in an exuberant tumor microenvironment (or stroma), which represents up to 80% of PDAC tumor volume, and is hijacked by cancer cells for their own survival and metastasis. Additionally, PDAC tumors are heterogeneous, e.g. transcriptomic (RNAseq) analyses of human PDAC tumors have allowed patients to be stratified into two tumor subgroups (basal and classical) with different prognoses. Therefore, we aimed to understand which tumor-stroma crosstalks are critical for PDAC aggressiveness in the context of its heterogeneity, and how they can be pharmacologically targeted, to then propose more effective personalized therapeutic strategies. By performing bioinformatical analysis on RNAseq data from PDX (Patient Derived Xenograft), a hybrid tumor model from which human-derived tumor cell sequences are distinguishable from murine-derived stromal cell sequences, we searched for different stromal behaviors linked to the tumor aggressiveness, to be then validated in published PDAC patient databases. According to NMF (Non-negative matrix factorization) and GSEA (Gene Set Enrichment Analyses), we identified two components, which classify the samples according to a stromal gradient. Interestingly, these components are characterized by distinct functional signatures of aggressiveness and they are highly prognostic (correlated with survival). In addition, these components stratify patients independently on the described molecular tumor (basal or classical) classification. Importantly, we validated those results on other PDAC published databases. Moreover, ligand-receptor bioinformatics analyses identified novel players of the TGFβ superfamily in the most aggressive stromal component. Indeed, we have highlighted the involvement of the ligand activin a member of this large superfamily. Using in situ hybridization coupled with immunofluorescence, we were able to demonstrate that activin is only expressed by stromal cells, and more specifically by cancer associated fibroblasts (CAF), with however a strong heterogeneity (inter and intra-tumor). In vitro, activin strongly increases the migratory capacity of fibroblasts but also of specific cancer cells, this effect being effectively blocked pharmacologically with an activin receptor-targeting drug that is now tested in a pre-clinical PDAC murine model. Therapeutic targeting of the stroma must take into account its functional heterogeneity. We have identified in specific aggressive PDAC tumors novel stromal players involved in the tumor-stroma symbiosis, and which presumably play a critical role in CAFs and cancer cells migration and invasion. Our work should enable to delineate which stroma-targeting drug to co-deliver, in addition to chemotherapies, in stratified patients, to improve PDAC prognosis. Citation Format: Alexia Brunel, Jérôme Raffenne, Remy Nicolle, Ilse Rooman, Elisa Espinet, Marjorie Fanjul, Aurélie Perraud, Muriel Mathonnet, Sophie Vasseur, Nelson Dusetti, Yvan Martineau, Christine Jean, Corinne Bousquet. Bioinformatical identification of cancer-associated-fibroblasts with tumor cells pro-migratory crosstalks depending on activin [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C034.

The immune escape signature predicts the prognosis and immunotherapy sensitivity for pancreatic ductal adenocarcinoma.

BackgroundPancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies worldwide. Immune escape is considered to be a reason for immunotherapy failure in PDAC. In this study, we explored the correlation between immune escape-related genes and the prognosis of PDAC patients.Methods1163 PDAC patients from four public databases, including The Cancer Genome Atlas (TCGA), International Cancer Genome Consortium (ICGC), Array-express, and Gene Expression Omnibus (GEO), were included in our study. Cox regression analysis was used to identify the 182 immune genes which were significantly associated with overall survival (OS). And then we established an immune escape-related gene prognosis index (IEGPI) score using several datasets as the training cohort and validated it using the validation cohort. Kaplan-Meier (KM) and Cox regression analysis were used to detect the relationship of IEGPI score with OS. We further explored the relationship between the IEGPI and immune indexes. And the prediction value of response for immunotherapy in Tumor Immune Dysfunction and Exclusion (TIDE) dataset.ResultsWe establish an IEGPI score based on 27 immune escape genes which were significantly related to the prognosis of OS in PDAC patients. Patients in the high-IEGPI group had a significantly worse overall survival rate compared with that in the low-IEGPI groups by KM curves and cox-regression. 5 of the 32 cancer types in TCGA could be significantly distinguished in survival rates through the low- and high-IEGPI groups. Moreover, the correlation between the IEGPI score was negatively correlated with an immune score in several datasets. And higher IEGPI better recurrence-free survival (RFS) and OS in the patients after patients were treated with both PD-1 and CTLA4 in the public datasets (P<0.05). Intriguingly, by using RT-PCR, we verified that the gene of PTPN2, CEP55, and JAK2 were all higher in the BxPC-3 and PANC-1 than HPDE5 cells. Lastly, we found that the IEGPI score was higher in K-rasLSL.G12D/+, p53LSL.R172H/+, Pdx1Cre (KPC) mice model with anti-PD-L1 than that without anti-PD-L1.ConclusionUsing the immune escape-related genes, our study established and validated an IEGPI score in PDAC patients from the public dataset. IEGPI score has the potential to serve as a prognostic marker and as a tool for selecting tumor patients suitable for immunotherapy in clinical practice.

CDK7 inhibition augments response to multidrug chemotherapy in pancreatic cancer

BackgroundPancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with a dismal prognosis. Although combined treatment with gemcitabine and albumin-bound paclitaxel has improved the prognosis of PDAC, both intrinsic and acquired chemoresistance remain as severe hurtles towards improved prognosis. Thus, new therapeutic targets and innovative strategies are urgently needed.MethodsIn this study, we used the KPC mouse model-derived PDAC cell line TB32047 to perform kinome-wide CRISPR-Cas9 loss-of-function screening. Next-generation sequencing and MAGeCK-VISPR analysis were performed to identify candidate genes. We then conducted cell viability, clonogenic, and apoptosis assays and evaluated the synergistic therapeutic effects of cyclin-dependent kinase 7 (CDK7) depletion or inhibition with gemcitabine (GEM) and paclitaxel (PTX) in a murine orthotopic pancreatic cancer model. For mechanistic studies, we performed genome enrichment analysis (GSEA) and Western blotting to identify and verify the pathways that render PDAC sensitive to GEM/PTX therapy.ResultsWe identified several cell cycle checkpoint kinases and DNA damage-related kinases as targets for overcoming chemoresistance. Among them, CDK7 ranked highly in both screenings. We demonstrated that both gene knockout and pharmacological inhibition of CDK7 by THZ1 result in cell cycle arrest, apoptosis induction, and DNA damage at least predominantly through the STAT3-MCL1-CHK1 axis. Furthermore, THZ1 synergized with GEM and PTX in vitro and in vivo, resulting in enhanced antitumor effects.ConclusionsOur findings support the application of CRISPR-Cas9 screening in identifying novel therapeutic targets and suggest new strategies for overcoming chemoresistance in pancreatic cancer.

Cancer-Associated Fibroblasts Confer Gemcitabine Resistance to Pancreatic Cancer Cells through PTEN-Targeting miRNAs in Exosomes.

Simple SummaryPrevious studies have shown that cancer associated fibroblasts exposed to chemotherapy release exosomes which promote chemoresistance in recipient cells. However, the molecular mechanism responsible for this has not been fully elucidated. In this study, we found that gemcitabine treatment caused fibroblasts to release exosome which contain PTEN-targeting miRNAs. These findings shed light on how fibroblasts exposed to chemotherapy promote tumor growth and drug resistance.Pancreatic ductal adenocarcinoma (PDAC) is currently the third leading cause of cancer-related death in the United States. Even though the poor prognosis of PDAC is often attributed to late diagnosis, patients with an early diagnosis who undergo tumor resection and adjuvant chemotherapy still show tumor recurrence, highlighting a need to develop therapies which can overcome chemoresistance. Chemoresistance has been linked to the high expression of microRNAs (miRs), such as miR-21, within tumor cells. Tumor cells can collect miRs through the uptake of miR-containing lipid extracellular vesicles called exosomes. These exosomes are secreted in high numbers from cancer-associated fibroblasts (CAFs) within the tumor microenvironment during gemcitabine treatment and can contribute to cell proliferation and chemoresistance. Here, we show a novel mechanism in which CAF-derived exosomes may promote proliferation and chemoresistance, in part, through suppression of the tumor suppressor PTEN. We identified five microRNAs: miR-21, miR-181a, miR-221, miR-222, and miR-92a, that significantly increased in number within the CAF exosomes secreted during gemcitabine treatment which target PTEN. Furthermore, we found that CAF exosomes suppressed PTEN expression in vitro and that treatment with the exosome inhibitor GW4869 blocked PTEN suppression in vivo. Collectively, these findings highlight a mechanism through which the PTEN expression loss, often seen in PDAC, may be attained and lend support to investigations into the use of exosome inhibitors as potential therapeutics to improve the effectiveness of chemotherapy.

Gene Coexpression Network Characterizing Microenvironmental Heterogeneity and Intercellular Communication in Pancreatic Ductal Adenocarcinoma: Implications of Prognostic Significance and Therapeutic Target.

BackgroundPancreatic ductal adenocarcinoma (PDAC) is characterized by intensive stromal involvement and heterogeneity. Pancreatic cancer cells interact with the surrounding tumor microenvironment (TME), leading to tumor development, unfavorable prognosis, and therapy resistance. Herein, we aim to clarify a gene network indicative of TME features and find a vulnerability for combating pancreatic cancer.MethodsSingle-cell RNA sequencing data processed by the Seurat package were used to retrieve cell component marker genes (CCMGs). The correlation networks/modules of CCMGs were determined by WGCNA. Neural network and risk score models were constructed for prognosis prediction. Cell–cell communication analysis was achieved by NATMI software. The effect of the ITGA2 inhibitor was evaluated in vivo by using a KrasG12D -driven murine pancreatic cancer model.ResultsWGCNA categorized CCMGs into eight gene coexpression networks. TME genes derived from the significant networks were able to stratify PDAC samples into two main TME subclasses with diverse prognoses. Furthermore, we generated a neural network model and risk score model that robustly predicted the prognosis and therapeutic outcomes. A functional enrichment analysis of hub genes governing gene networks revealed a crucial role of cell junction molecule–mediated intercellular communication in PDAC malignancy. The pharmacological inhibition of ITGA2 counteracts the cancer-promoting microenvironment and ameliorates pancreatic lesions in vivo.ConclusionBy utilizing single-cell data and WGCNA to deconvolute the bulk transcriptome, we exploited novel PDAC prognosis–predicting strategies. Targeting the hub gene ITGA2 attenuated tumor development in a PDAC mouse model. These findings may provide novel insights into PDAC therapy.

Exploring the metabolic landscape of pancreatic ductal adenocarcinoma cells using genome-scale metabolic modeling

SummaryPancreatic ductal adenocarcinoma (PDAC) is a major research focus because of its poor therapy response and dismal prognosis. PDAC cells adapt their metabolism to the surrounding environment, often relying on diverse nutrient sources. Because traditional experimental techniques appear exhaustive to find a viable therapeutic strategy, a highly curated and omics-informed PDAC genome-scale metabolic model was reconstructed using patient-specific transcriptomics data. From the model-predictions, several new metabolic functions were explored as potential therapeutic targets in addition to the known metabolic hallmarks of PDAC. Significant downregulation in the peroxisomal beta oxidation pathway, flux modulation in the carnitine shuttle system, and upregulation in the reactive oxygen species detoxification pathway reactions were observed. These unique metabolic traits of PDAC were correlated with potential drug combinations targeting genes with poor prognosis in PDAC. Overall, this study provides a better understanding of the metabolic vulnerabilities in PDAC and will lead to novel effective therapeutic strategies.

Circulating Nucleic Acids as Novel Biomarkers for Pancreatic Ductal Adenocarcinoma

Simple SummaryPancreatic ductal adenocarcinoma (PDAC) is a particularly aggressive and deadly cancer, primarily due to failure to identify early-stage disease. PDAC is often diagnosed at a late stage due to nonspecific symptoms, and a distinct lack of reliable biomarkers for timely diagnosis. Current PDAC biomarkers are inadequate for the monitoring of a patient’s response to treatment. The aim of this review is to highlight the potential use of circulating nucleic acid-based biomarkers, along with technology facilitating their detection, in liquid biopsies. These biomarkers primarily focus on the detection of PDAC-specific genetic mutations, both freely circulating and contained within exosomes.Despite considerable advancements in the clinical management of PDAC it remains a significant cause of mortality. PDAC is often diagnosed at advanced stages due to vague symptoms associated with early-stage disease and a lack of reliable diagnostic biomarkers. Late diagnosis results in a high proportion of cases being ineligible for surgical resection, the only potentially curative therapy for PDAC. Furthermore, a lack of prognostic biomarkers impedes clinician’s ability to properly assess the efficacy of therapeutic interventions. Advances in our ability to detect circulating nucleic acids allows for the advent of novel biomarkers for PDAC. Tumor derived circulating and exosomal nucleic acids allow for the detection of PDAC-specific mutations through a non-invasive blood sample. Such biomarkers could expand upon the currently limited repertoire of tests available. This review outlines recent developments in the use of molecular techniques for the detection of these nucleic acids and their potential roles, alongside current techniques, in the diagnosis, prognosis and therapeutic governance of PDAC.

Robust Validation and Comprehensive Analysis of a Novel Signature Derived from Crucial Metabolic Pathways of Pancreatic Ductal Adenocarcinoma.

Simple SummaryPancreatic ductal adenocarcinoma (PDAC) has a high mortality rate and a poor prognosis. To solve the above limitations of multiomics studies of metabolism in PDAC and optimize the prognosis of PDAC clinically, we demonstrated a 16-gene prognostic signature based on the metabolic pathways called gbcxMRS. The prognostic value varied in six public datasets and our own data cohort in Shanghai Cancer Center by RT-PCR. Notably, gbcxMRS also accurately predicted poor PDAC subtypes and recurrence. It also highly associated with immune infiltration cells. Furthermore, high gbcxMRS may indicate high sensitivity to irinotecan, docetaxel, and CTLA4 inhibitor immunotherapy.Pancreatic ductal adenocarcinoma (PDAC) is a malignant tumor with a dismal prognosis. PDAC have extensively reprogrammed metabolic characteristics influenced by interactions with normal cells, the effects of the tumor microenvironment and oncogene-mediated cell-autonomous pathways. In this study, we found that among all cancer hallmarks, metabolism played an important role in PDAC. Subsequently, a 16-gene prognostic signature was established with genes derived from crucial metabolic pathways, including glycolysis, bile acid metabolism, cholesterol homeostasis and xenobiotic metabolism (gbcx). The signature was used to distinguish overall survival in multiple cohorts from public datasets as well as a validation cohort followed up by us at Shanghai Cancer Center. Notably, the gbcx-related risk score (gbcxMRS) also accurately predicted poor PDAC subtypes, such as pure-basal-like and squamous types. At the same time, it also predicted PDAC recurrence. The gbcxMRS was also associated with immune cells, especially CD8 T cells, Treg cells. Furthermore, a high gbcxMRS may indicate high drug sensitivity to irinotecan and docetaxel and CTLA4 inhibitor immunotherapy. Taken together, these results indicate a robust and reproducible metabolic-related signature based on analysis of the overall pathogenesis of pancreatic cancer, which may have excellent prognostic and therapeutic implications for PDAC.

Up-Regulated MISP Is Associated With Poor Prognosis and Immune Infiltration in Pancreatic Ductal Adenocarcinoma.

BackgroundPancreatic ductal adenocarcinoma (PDAC) is a highly malignant disease with a poor prognosis. More effective biomarkers and treatment options remain to be discovered. Mitotic Spindle Positioning (MISP), also called C19orf21, has been reported to be upregulated in several malignancies. However, the effects of MISP on PDAC have yet to be investigated.Materials and MethodsThe differential expression of MISP at the mRNA and protein levels were evaluated using Gene Expression Profiling Interactive Analysis 2 (GEPIA 2), Gene Expression Omnibus (GEO), and the Human Protein Atlas (HPA) databases, and was further verified by quantitative real-time PCR and western blotting in PDAC cell lines. Correlations between MISP expression and clinical characteristics were explored using Kaplan-Meier Plotter Database and clinical data from The Cancer Genome Atlas (TCGA). CCK-8 assays, Transwell assays, and immunoblotting were used to determine the role of MISP in PDAC proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were executed by the R package ‘clusterProfiler’. Correlations between MISP expression and immune cell infiltration, immune checkpoints, immunophenoscore (IPS) and the tumor mutational burden (TMB) in PDAC were explored using the R package ‘CIBERSORT’, the Tumor Immune Estimation Resource 2.0 (TIMER2.0), and The Cancer Immunome Atlas (TCIA) database based on TCGA data.ResultMISP expression was significantly higher in pancreatic cancer tissues compared to normal pancreas tissues, which was associated with a poor prognosis. Increased expression of MISP was related to the proliferation, migration and invasion of PDAC cell lines. GO and KEGG pathway analyses determined that MISP is involved in the Ras signaling pathway and immune regulation. Higher expression of MISP was associated with decreased infiltration levels of activated CD4+ memory T cells, CD8+ T cells, M2 macrophages and neutrophils. Furthermore, increased MISP was associated with lower expression of immune checkpoint molecules, higher gene mutation burden and IPS.ConclusionsThis study reveals that MISP, which is associated with the progression and prognosis of PDAC, may exert a potential regulatory effect on immune infiltration and predict the response to immunotherapy in PDAC.

Pivotal antitumor role of the immune checkpoint molecule B7-H1 in pancreatic cancer

Immune checkpoint molecule B7-H1 plays a decisive immune regulatory role in different pathologies including cancer, and manipulation of B7-H1 expression became an attractive approach in cancer immunotherapy. Pancreatic cancer (PDAC) is characterized by pronounced immunosuppressive environment and B7-H1 expression correlates with PDAC prognosis. However, the first attempts to diminish B7-H1 expression in patients were not so successful. This points the complicity of PDAC immunosuppressive network and requires further examinations. We investigated the effect of B7-H1 deficiency in PDAC. Our results clearly show that partial or complete B7-H1 inhibition in vivo let to reduced tumor volume and improved survival of PDAC-bearing mice. This oncological benefit is due to the abrogation of immunosuppression provided by MDSC, macrophages, DC and Treg, which resulted in simultaneous restoration of anti-tumor immune response, namely improved accumulation and functionality of effector-memory CD4 and CD8 T cells. Our results underline the potential of B7-H1 molecule to control immunosuppressive network in PDAC and provide new issues for further clinical investigations.

Tumor Microenvironment Features and Chemoresistance in Pancreatic Ductal Adenocarcinoma: Insights into Targeting Physicochemical Barriers and Metabolism as Therapeutic Approaches.

Simple SummaryPancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis. The lack of early diagnosis and the absence of suitable biomarkers coupled with resistance to available therapeutic options has made PDAC one of the deadliest cancers. Despite advances in diagnostics and therapeutics, the prognosis of PDAC remains dismal. PDAC has a prominent desmoplastic stromal microenvironment that includes a dense extracellular matrix together with a series of activated cell types, hypoxia, and an acidic extracellular pH. This activated desmoplastic stroma compromises treatments yet, despite the recognition of its importance, it has not been comprehensively studied in this role. Moreover, PDAC metabolic reprogramming has also been found to be one of the key factors involved in treatment failure. Here, we critically review the role of the various stromal components in determining resistance to available therapeutics with the hope that its comprehensive understanding, if employed in the appropriate combination therapy, may make this recalcitrant cancer more manageable.Currently, the median overall survival of PDAC patients rarely exceeds 1 year and has an overall 5-year survival rate of about 9%. These numbers are anticipated to worsen in the future due to the lack of understanding of the factors involved in its strong chemoresistance. Chemotherapy remains the only treatment option for most PDAC patients; however, the available therapeutic strategies are insufficient. The factors involved in chemoresistance include the development of a desmoplastic stroma which reprograms cellular metabolism, and both contribute to an impaired response to therapy. PDAC stroma is composed of immune cells, endothelial cells, and cancer-associated fibroblasts embedded in a prominent, dense extracellular matrix associated with areas of hypoxia and acidic extracellular pH. While multiple gene mutations are involved in PDAC initiation, this desmoplastic stroma plays an important role in driving progression, metastasis, and chemoresistance. Elucidating the mechanisms underlying PDAC resistance are a prerequisite for designing novel approaches to increase patient survival. In this review, we provide an overview of the stromal features and how they contribute to the chemoresistance in PDAC treatment. By highlighting new paradigms in the role of the stromal compartment in PDAC therapy, we hope to stimulate new concepts aimed at improving patient outcomes.

Abstract PO-082: Delineating the molecular basis of early dissemination of pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is often diagnosed at advanced stages rendering the already limited therapeutic options ineffective for many patients. Earlier diagnosis permits for “curative” surgery; however, 95% of these patients experience recurrence locally or distally and die within ten years of treatment. One hypothesis that can explain high recurrence is the early dissemination of PDAC progression. At the time of surgery, systemic subclinical dissemination of predominantly dormant cells found ubiquitously within patient livers has already occurred prior to the development of overt metastatic disease or bona fide recurrent PDAC. However, remarkably little is known about early PDAC cell dissemination despite these dismal outcomes, mainly due to the lack of human models to study disease progression. We previously demonstrated the cellular reprogramming “proof-of-principle” to model human PDAC progression (designated “10-22 cells”) and its use as a discovery tool for early biomarkers by unveiling a marker for stage 1 PDAC in human patients. We further analyzed transcriptomes of genetically tagged 10-22 cells progressing from pancreatic intraepithelial neoplasia (PanIN) to PDAC in mice and validated the results using the TCGA PDAC dataset, human clinical PanIN, PDAC tissues, and a well-established murine PDAC model. We found that extracellular vesicle transport and neuronal cell differentiation pathways were derepressed in the progression of PanINs to PDAC. HMG-Box Transcription Factor 1 (HBP1) emerged as a potential master factor regulating dynamically expressed genes in neuronal cell differentiation and dissemination during PDAC progression. HBP1 expression are aberrantly regulated in human and murine PanINs and PDAC tissue samples, and their mRNA expressions are inversely correlated with PDAC patients' prognosis. Ectopic overexpression of HBP1 increased proliferation and migration of normal and cancerous pancreatic cells. Conversely, knocking out HBP1 in PDAC cells decreased proliferation and migration. Altogether, our data indicate that HBP1 may confer the cell dissemination capacity in early PDAC progression. We are on the way to further dissect the mechanisms by which HBP1 regulates pancreatic cell migration and confers neuronal migratory phenotypes and how these signaling influence PDAC progression and prognosis. Citation Format: Taelor J. Ekstrom, Dmytro Grygoryev, Terry Morgan, Kenneth S. Zaret, Jungsun Kim. Delineating the molecular basis of early dissemination of pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-082.

Comprehensive analysis of the transcriptional expressions and prognostic value of S100A family in pancreatic ductal adenocarcinoma

BackgroundPancreatic ductal adenocarcinoma (PDAC) remains a treatment-refractory malignancy with poor prognosis. It is urgent to identify novel and valid biomarkers to predict the progress and prognosis of PDAC. The S100A family have been identified as being involved in cell proliferation, migration and differentiation progression of various cancer types. However, the expression patterns and prognostic values of S100As in PDAC remain to be analyzed.MethodsWe investigated the transcriptional expressions, methylation level and prognostic value of S100As in PDAC patients from the Oncomine, GEPIA2, Linkedomics and cBioPortal databases. Real-time PCR was used to detect the expressions of S100A2/4/6/10/14/16 in four pancreatic cancer cell lines and pancreatic cancer tissues from PDAC patients undergoing surgery. To verify the results further, immunohistochemistry was used to measure the expression of S100A2/4/6/10/14/16 in 43 PDAC patients’ tissue samples. The drug relations of S100As were analyzed by using the Drugbank database.ResultsThe results suggested that, the expression levels of S100A2/4/6/10/14/16 were elevated to PDAC tissues than in normal pancreatic tissues, and the promoter methylation levels of S100A S100A2/4/6/10/14/16 in PDAC (n = 10) were lower compared with normal tissue (n = 184) (P < 0.05). In addition, their expressions were negatively correlated with PDAC patient survival.ConclusionsTaken together, these results suggest that S100A2/4/6/10/14/16 might be served as prognostic biomarkers for survivals of PDAC patients.

Comprehensive analysis of abnormal expression, prognostic value and oncogenic role of the hub gene FN1 in pancreatic ductal adenocarcinoma via bioinformatic analysis and in vitro experiments.

BackgroundPancreatic ductal adenocarcinoma (PDAC) is one of the most commonly diagnosed cancers with a poor prognosis worldwide. Although the treatment of PDAC has made great progress in recent years, the therapeutic effects are still unsatisfactory. Methods. In this study, we identified differentially expressed genes (DEGs) between PDAC and normal pancreatic tissues based on four Gene Expression Omnibus (GEO) datasets (GSE15471, GSE16515, GSE28735 and GSE71729). A protein–protein interaction (PPI) network was established to evaluate the relationship between the DEGs and to screen hub genes. The expression levels of the hub genes were further validated through the Gene Expression Profiling Interactive Analysis (GEPIA), ONCOMINE and Human Protein Atlas (HPA) databases, as well as the validation GEO dataset GSE62452. Additionally, the prognostic values of the hub genes were evaluated by Kaplan–Meier plotter and the validation GEO dataset GSE62452. Finally, the mechanistic roles of the most remarkable hub genes in PDAC were examined through in vitro experiments.ResultsWe identified the following nine hub genes by performing an integrated bioinformatics analysis: COL1A1, COL1A2, FN1, ITGA2, KRT19, LCN2, MMP9, MUC1 and VCAN. All of the hub genes were significantly upregulated in PDAC tissues compared with normal pancreatic tissues. Two hub genes (FN1 and ITGA2) were associated with poor overall survival (OS) rates in PDAC patients. Finally, in vitro experiments indicated that FN1 plays vital roles in PDAC cell proliferation, colony formation, apoptosis and the cell cycle.ConclusionsIn summary, we identified two hub genes that are associated with the expression and prognosis of PDAC. The oncogenic role of FN1 in PDAC was first illustrated by performing an integrated bioinformatic analysis and in vitro experiments. Our results provide a fundamental contribution for further research aimed finding novel therapeutic targets for overcoming PDAC.

Abstract 3173: NetrinG1's pro-tumor role on stroma-derived extracellular vesicles in pancreatic cancer

Abstract Pancreatic Ductal Adenocarcinoma (PDAC) is a devastating disease which is in part driven, and supported by changes in its microenvironment, or stroma. These changes occur early, yet PDAC is usually undetected until the disease has metastasized, causing survival rates to drop dramatically. Therefore, there exists an urgency to detect this disease as early as possible and understand its progression. This project dissects the intercellular communication that exists between the primary stromal component, cancer-associated fibroblasts (CAFs), and PDAC cells. Specifically, we focus on how CAF-secreted extracellular vesicles (EVs) promote PDAC progression, with an additional goal to identify biomarkers suitable to generate a non-invasive “liquid biopsy” test for early PDAC detection and prognosis. PDAC communicates with its microenvironment, in part, through the exchange of specific types of EVs, which include exosomes and recently characterized “ectosomes.” We observe distinct types of CAF-derived EVs containing unique surface receptors. One novel surface protein, NetrinG1, is expressed on the plasma membrane of pancreatic CAFs, but not their normal/healthy counterparts. Further, PDAC cells, but not healthy pancreatic epithelial cells, upregulate NetrinG1's lone binding partner, suggesting a role for these factors in PDAC-selective EV uptake. Functional assays designed to test PDAC viability in nutrient deprivation show that CAF-EVs are capable of protecting PDAC cells from the induction of programmed cell death. Further, we show NetrinG1's expression in CAFs is necessary for this EV-mediated survival effect. We also determine that NetrinG1 localizes to the novel “ectosome” EV sub-population, suggesting it possesses unique cargo and is packaged into EVs and secreted through a yet-unknown mechanism separate from canonical exosome trafficking. We also determine, that sub-populations of EVs can be “filtered” locally by the extracellular matrix, based on various EV surface markers. This suggests that the extracellular matrix can play an important role in determining the fate of secreted EVs; which has significant implications for what sub-populations maybe be found circulating systemically in blood, or acting locally in the tumor microenvironment. Pursuing our biomarker goal, we confirm stromal NetrinG1 expression precedes tumorigenesis and are currently seeking to validate the prognostic potential of NetrinG1(+)EVs in blood of PDAC patients. Altogether, this research shines light on a novel mechanism of tumor-stroma communication, and introduces EV biomarkers potentially capable of identifying both early PDAC occurrences and predicted efficacy of certain adjuvant interventions. Citation Format: Kristopher Raghavan, Debora Vendramini, Ralph Francescone, Janusz Franco-Barraza, Edna Cukierman. NetrinG1's pro-tumor role on stroma-derived extracellular vesicles in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3173.

CA19.9 Serum Level Predicts Lymph-Nodes Status in Resectable Pancreatic Ductal Adenocarcinoma: A Retrospective Single-Center Analysis

BackgroundThe choice between upfront surgery or neoadjuvant treatments (NAT) for resectable pancreatic ductal adenocarcinoma (R-PDAC) is controversial. R-PDAC with potential nodal involvement could benefit from NT. Ca (Carbohydrate antigen) 19.9 and serum albumin levels, alone or in combination, have proven their efficacy in assessing PDAC prognosis. The objective of this study was to evaluate the role of Ca 19.9 serum levels in predicting nodal status in R-PDAC.MethodsPreoperative Ca 19.9, as well as serum albumin levels, of 165 patients selected for upfront surgery have been retrospectively collected and correlated to pathological nodal status (N), resection margins status (R) and vascular resections (VR). We further performed ROC curve analysis to identify optimal Ca 19.9 cut-off for pN+, R+ and vascular resection prediction.ResultsIncreased Ca 19.9 levels in 114 PDAC patients were significantly associated with pN+ (p <0.001). This ability, confirmed in all the series by ROC curve analysis (Ca 19.9 ≥32 U/ml), was lost in the presence of hypoalbuminemia. Furthermore, Ca 19.9 at the cut off >418 U/ml was significantly associated with R+ (87% specificity, 36% sensitivity, p 0.014). Ca 19.9, at the cut-off >78 U/ml, indicated a significant trend to predict the need for VR (sensitivity 67%, specificity 53%; p = 0.059).ConclusionsIn R-PDAC with normal serum albumin levels, Ca 19.9 predicts pN+ and R+, thus suggesting a crucial role in deciding on NAT.

Construction and Validation of Novel Nomograms for Predicting Prognosis of Pancreatic Ductal Adenocarcinoma After Surgery According to Different Primary Cancer Locations.

Background/AimsPancreatic ductal adenocarcinoma (PDAC) can occur in different parts of the pancreas. This study aimed to identify clinicopathological characteristics independently correlated with the prognosis of PDAC of the pancreatic head/uncinate (PHC) or body-tail (PBTC), and to develop novel nomograms for predicting cancer-specific survival (CSS) according to different primary cancer locations.Methods1160 PDAC patients were retrospectively enrolled and assigned to training and test sets with each set divided into PHC and PBTC groups. Comparative analysis of clinicopathologic characteristics, survival analysis, and multivariate analysis were performed. Independent factors were identified and used for constructing nomograms. The performance of the nomograms was validated in the test set.ResultsPrimary tumor location was an independent risk factor for prognosis of PDAC after surgery. Specially, gender, fasting blood glucose, and preoperative cancer antigen 19-9 were significantly associated with prognosis of PHC, whereas age, body mass index, and lymph nodes were significantly correlated with the prognosis of PBTC. A significant difference in prognosis was found between PHC and PBTC in stage Ia and stage III. Three nomograms were established for predicting the prognosis for PDAC, PHC, and PBTC. Notably, these nomograms were calibrated modestly (c-indexes of 0.690 for PDAC, 0.669 for PHC, and 0.704 for PBTC), presented better accuracy and reliability than the 8th AJCC staging system, and achieved clinical validity.ConclusionsPHC and PBTC share the differential clinical-pathological characteristics and survival. The nomograms show good performance for predicting prognosis in PHC and PBTC. Therefore, these nomograms hold potential as novel approaches for predicting survival of PHC and PBTC patients after surgery.

Abstract PR004: NetrinG1’s pro-tumor role on stroma-derived extracellular vesicles in pancreatic cancer

Abstract Pancreatic Ductal Adenocarcinoma (PDAC) is a devastating disease which is, in part, driven and supported by changes in its microenvironment, or stroma. These changes occur early, yet PDAC is usually undetected until the disease has metastasized, causing survival rates to drop dramatically. Therefore, there exists a grave importance to detect this disease as early as possible and understand its progression. This project dissects the intercellular communication that exists between the primary stromal component, cancer-associated fibroblasts (CAFs), and PDAC cells. Specifically, we focus on how CAF-secreted extracellular vesicles (EVs) promote PDAC progression, with an additional goal to identify biomarkers suitable to generate a non-invasive “liquid biopsy” test for early PDAC detection and prognosis. PDAC communicates with its microenvironment, in part, through the exchange of specific types of EVs, which include exosomes and recently characterized “ectosomes.” We observe distinct types of CAF-derived EVs containing unique surface receptors. One novel surface protein, NetrinG1, is expressed on the plasma membrane of pancreatic CAFs, but not their normal/healthy counterparts. Further, PDAC cells, but not healthy pancreatic epithelial cells, upregulate NetrinG1’s lone binding partner, suggesting a role for these factors in PDAC-selective EV uptake. Functional assays designed to test PDAC viability in nutrient deprivation show that CAF-EVs are capable of protecting PDAC cells from the induction of programmed cell death. Further, we show NetrinG1’s expression in CAFs is necessary for this EV-mediated survival effect. We also determine that NetrinG1 localizes to the novel “ectosome” EV sub-population, suggesting it possesses unique cargo and is packaged into EVs and secreted through a yet-unknown mechanism separate from canonical exosome trafficking. We also determine, that sub-populations of EVs can be “filtered” locally by the extracellular matrix, based on various EV surface markers. This suggests that the extracellular matrix can play an important role in determining the fate of secreted EVs; which has significant implications for what sub-populations maybe be found circulating systemically in blood, or acting locally in the tumor microenvironment. Pursuing our biomarker goal, we confirm stromal NetrinG1 expression precedes tumorigenesis and are currently seeking to validate the prognostic potential of NetrinG1(+)-EVs in blood of PDAC patients. Altogether, this research shines light on a novel mechanism of tumor-stroma communication, and introduces EV biomarkers potentially capable of identifying both early PDAC occurrences and predicted efficacy of certain adjuvant interventions. Citation Format: Kristopher Raghavan, Ralph Francescone, Janusz Franco-Barraza, Edna Cukierman. NetrinG1’s pro-tumor role on stroma-derived extracellular vesicles in pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PR004.