Pancreatic Ductal Adenocarcinoma Metastasis Research Articles

HDAC4 Mediates Smoking-Induced Pancreatic Cancer Metastasis.

Cigarette smoking is an established risk factor for pancreatic ductal adenocarcinoma (PDAC). In this project, we investigated the effect of smoking and the role of histone deacetylase 4 (HDAC4) in PDAC invasion and metastasis. Cells were treated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and cigarette smoke extract and the mRNA levels of HDACs were measured by real-time polymerase chain reaction. Invasion was measured using the Matrigel Invasion Assay. Syngeneic PDAC mice were treated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and metastasis measured. Human PDAC primary and metastatic tissues were analyzed by immunohistochemistry. Levels of HDAC4 mRNA were increased by smoking. Smoking compounds significantly promoted invasion of cancer cells and promoted metastasis of PDAC cells to different organs, including the liver and the lung, whereas inhibition of HDAC4 prevented this effect. The effect of HDAC4 inhibition on preventing smoking-induced metastasis was greater in the liver compared with the lung. We found that HDAC4 is highly expressed in primary and metastatic PDAC tumors. We found that HDAC4 is the only HDAC induced by smoking among all HDACs analyzed. We found that smoking promotes invasion and metastasis of PDAC cells through a mechanism that involves HDAC4 and that HDAC4 is a promising target for preventing PDAC metastasis.

Real-world clinical outcomes and molecular features of lung-specific and liver-specific metastases in pancreatic ductal adenocarcinoma (PDAC).

532 Background: PDAC remains one of the most lethal malignancies following metastatic presentation, typically to the liver or lung. Previous studies have observed that advanced PDAC patients have variable outcomes depending on site of involvement. Here, we aim to understand survival outcomes and molecular features for PDAC based on involvement of lung vs liver. Methods: We retrospectively analyzed longitudinal clinical outcomes across 787 patients with PDAC with next generation sequencing (NGS) from Perthera’s Real-World Evidence database whose tumors first metastasized to either the lung or the liver. Median overall survival (mOS) was measured from either the date of initial diagnosis (resectable cases only, stage I-III) or advanced diagnosis (stage IV) until death. Differences in survival and frequencies of mutations were evaluated between patients with lung-specific and liver-specific metastases using Cox regression and Fisher's exact test, respectively. Results: Among resectable PDAC, mOS from initial diagnosis was significantly shorter in patients that developed liver only metastasis (Table, left) compared to those patients that developed lung only metastasis (p=2.4e-08, HR=3.04 [2.06-4.49]). In the advanced PDAC cohort, mOS from diagnosis of advanced disease was also significantly shorter (Table, right) in liver only versus lung only metastasis (p=0.0013, HR=1.62 [1.21-2.18]). Differences in treatment-specific outcomes were not significant supporting a potential prognostic role for lung only metastases. PDAC tumors presenting to the liver first were modestly enriched (unadjusted p<0.05) for TP53 mutations (81.4% in liver vs 69.2% in lung), MYC amplifications (8.6% vs 3.0%), and inactivating CDK2NA alterations (51.5% vs 39.1%) whereas lung-specific mutation frequencies were higher for STK11 mutations (2.4% in liver vs 7.5% in lung), CCND1 amplifications (0.5% vs 3.0%), GNAS alterations (2.0% vs 8.5%). No differences in KRAS mutations nor specific isoforms were noted between lung vs liver only metastasis. Conclusions: Lung only metastasis in both resectable and advanced PDAC confers a significant survival advantage compared to liver only metastasis. Deeper investigation into the molecular drivers of site-specific metastases is warranted.[Table: see text]

Phase 1b study of vactosertib in combination with nal-IRI plus 5FU/LV in patients with metastatic pancreatic ductal adenocarcinoma who have failed first-line gemcitabine/nab-paclitaxel.

TPS632 Background: Pancreatic ductal adenocarcinoma (PDAC) remains one of the most aggressive malignancies and the leading cause of cancer-related death in the world, although recent advances in chemotherapies for metastatic PDAC provide better clinical outcomes. TGF-β is strongly involved in the tumor microenvironment of PDAC, and dysregulation of TGF-β signaling is a frequent molecular disturbance in PDAC progression and metastasis. Vactosertib is an orally bioavailable TGF-β signaling inhibitor that targets the TGF-β type I receptor kinase. In in vivo studies, vactosertib reduces cancer cell migration, invasion, and metastasis of various cancers, and combination of vactosertib with nal-IRI/5-FU/LV improves pancreatic cancer survival by suppressing cell migration, invasion, and epithelial-mesenchymal transition (EMT), highlighting a potential clinical application of this approach for PDAC patients (Hong et al, 2020). Based on this preclinical study, we develop a phase 1b study to determine the recommended phase 2 dose (RP2D) and to evaluate the safety of vactosertib in combination with nal-IRI/5FU/LV in patients with metastatic PDAC who have failed first-line gemcitabine/ nab-paclitaxel. Methods: Eligible patients have histologically confirmed PDAC who have failed first-line gemcitabine/ nab-paclitaxel with adequate organ function and performance status. This study is composed of two parts; dose escalation and dose expansion. In the dose escalation part (phase 1b), different dose levels of vactosertib (100 mg bid, 200 mg bid, and 300 mg bid) for escalation will be tested, starting with dose level 0 (DL 0, 200 mg bid) with 3 to 6 subjects recruited in each cohort. DL -1 is only tested when DL 0 is unacceptable. In the dose expansion part, one or two additional backfill cohorts among DL -1 through DL 2 will be opened for determination of the final RP2D. For each cohort, a maximum of 12 patients can be enrolled including the dose escalation and dose expansion phase. Patients in each cohort will receive vactosertib 100-300 mg orally twice per day 1-5 & day 8-12 with nal-IRI 70mg/m2 intravenously day 1, LV 400mg/m2 IV day 1, and continuous 5-FU 2400mg/m2 infusion over 48 hours every 2 weeks. The primary endpoint is to determine RP2D and to evaluate safety of this combination. The key secondary endpoints are progression free survival, overall response rate, disease control rate based on RECIST 1.1 and overall survival. As of September 2021, 5 patients have been enrolled in DL 0 and 1 DLT has been reported in DL 0. This study is prospectively registered on ClinicalTrials.gov, NCT04258072. Clinical trial information: NCT04258072.

MicroRNA-21 Regulates Stemness in Pancreatic Ductal Adenocarcinoma Cells.

Pancreatic ductal adenocarcinoma (PDAC) is the most common and aggressive type of pancreatic cancer (PCa) with a low survival rate. microRNAs (miRs) are endogenous, non-coding RNAs that moderate numerous biological processes. miRs have been associated with the chemoresistance and metastasis of PDAC and the presence of a subpopulation of highly plastic “stem”-like cells within the tumor, known as cancer stem cells (CSCs). In this study, we investigated the role of miR-21, which is highly expressed in Panc-1 and MiaPaCa-2 PDAC cells in association with CSCs. Following miR-21 knockouts (KO) from both MiaPaCa-2 and Panc-1 cell lines, reversed expressions of epithelial–mesenchymal transition (EMT) and CSCs markers were observed. The expression patterns of key CSC markers, including CD44, CD133, CX-C chemokine receptor type 4 (CXCR4), and aldehyde dehydrogenase-1 (ALDH1), were changed depending on miR-21 status. miR-21 (KO) suppressed cellular invasion of Panc-1 and MiaPaCa-2 cells, as well as the cellular proliferation of MiaPaCa-2 cells. Our data suggest that miR-21 is involved in the stemness of PDAC cells, may play roles in mesenchymal transition, and that miR-21 poses as a novel, functional biomarker for PDAC aggressiveness.

Magnetic Resonance Imaging Radiomics-Based Nomogram From Primary Tumor for Pretreatment Prediction of Peripancreatic Lymph Node Metastasis in Pancreatic Ductal Adenocarcinoma: A Multicenter Study.

Determining the absence or presence of peripancreatic lymph nodal metastasis (PLNM) is important to the pathologic staging, prognostication, and guidance of treatment in pancreatic ductal adenocarcinoma (PDAC) patients. Computed tomography and MRI had a poor sensitivity and diagnostic accuracy in the assessment of PLNM. To develop and validate a 3T MRI primary tumor radiomics-based nomogram from multicenter datasets for pretreatment prediction of the PLNM in PDAC patients. Retrospective. A total of 251 patients (156 men and 95 women; mean age, 60.85 ± 8.23 years) with histologically confirmed pancreatic ductal adenocarcinoma from three hospitals. A 3.0 T and fat-suppressed T1-weighted imaging. Quantitative imaging features were extracted from fat-suppressed T1-weighted (FS T1WI) images at the arterial phase. Normally distributed data were compared by using t-tests, while the Mann-Whitney U test was used to evaluate non-normally distributed data. The diagnostic performances of the preoperative and postoperative nomograms were assessed in the external validation cohort with the area under receiver operating characteristics curve (AUC), calibration curve, and decision curve analysis (DCA). AUCs were compared with the De Long test. A p value below 0.05 was considered to be statistically significant. The AUCs of magnetic resonance imaging (MRI) Rad-score were 0.868 (95% confidence level [CI]: 0.613-0.852) and 0.772 (95% CI: 0.659-0.879) in the training and internal validation cohort, respectively. The preoperative and postoperative nomograms could accurately predict PLNM in the training cohort (AUC=0.909 and 0.851) and were validated in both the internal and external cohorts (AUC=0.835 and 0.805, 0.808 and 0.733, respectively). DCA indicated that the two novel nomograms are of similar clinical usefulness. Pre-/postoperative nomograms and the constructed radiomics signature from primary tumor based on FS T1WI of arterial phase could serve as a potential tool to predict PLNM in patients with PDAC. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 2.

Radiomics nomogram for the preoperative prediction of lymph node metastasis in pancreatic ductal adenocarcinoma

PurposeTo develop and validate a radiomics nomogram for the preoperative prediction of lymph node (LN) metastasis in pancreatic ductal adenocarcinoma (PDAC).Materials and methodsIn this retrospective study, 225 patients with surgically resected, pathologically confirmed PDAC underwent multislice computed tomography (MSCT) between January 2014 and January 2017. Radiomics features were extracted from arterial CT scans. The least absolute shrinkage and selection operator method was used to select the features. Multivariable logistic regression analysis was used to develop the predictive model, and a radiomics nomogram was built and internally validated in 45 consecutive patients with PDAC between February 2017 and December 2017. The performance of the nomogram was assessed in the training and validation cohort. Finally, the clinical usefulness of the nomogram was estimated using decision curve analysis (DCA).ResultsThe radiomics signature, which consisted of 13 selected features of the arterial phase, was significantly associated with LN status (p < 0.05) in both the training and validation cohorts. The multivariable logistic regression model included the radiomics signature and CT-reported LN status. The individualized prediction nomogram showed good discrimination in the training cohort [area under the curve (AUC), 0.75; 95% confidence interval (CI), 0.68–0.82] and in the validation cohort (AUC, 0.81; 95% CI, 0.69–0.94) and good calibration. DCA demonstrated that the radiomics nomogram was clinically useful.ConclusionsThe presented radiomics nomogram that incorporates the radiomics signature and CT-reported LN status is a noninvasive, preoperative prediction tool with favorable predictive accuracy for LN metastasis in patients with PDAC.

CircRTN4 promotes pancreatic cancer progression through a novel CircRNA-miRNA-lncRNA pathway and stabilizing epithelial-mesenchymal transition protein

BackgroundCircular RNAs (circRNAs) play important roles in many biological processes. However, the detailed mechanism underlying the critical roles of circRNAs in cancer remains largely unexplored. We aim to explore the molecular mechanisms of circRTN4 with critical roles in pancreatic ductal adenocarcinoma (PDAC).MethodsCircRTN4 expression level was examined in PDAC primary tumors. The oncogenic roles of circRTN4 in PDAC tumor growth and metastasis were studied in mouse tumor models. Bioinformatics analysis, luciferase assay and miRNA pulldown assay were performed to study the novel circRTN4-miRNA-lncRNA pathway. To identify circRTN4-interacting proteins, we performed circRNA-pulldown and mass spectrometry in PDAC cells. Protein stability assay and 3-Dimensional structure modeling were performed to reveal the role of circRTN4 in stabilizing RAB11FIP1.ResultsCircRTN4 was significantly upregulated in primary tumors from PDAC patients. In vitro and in vivo functional studies revealed that circRTN4 promoted PDAC tumor growth and liver metastasis. Mechanistically, circRTN4 interacted with tumor suppressor miR-497-5p in PDAC cells. CircRTN4 knockdown upregulated miR-497-5p to inhibit the oncogenic lncRNA HOTTIP expression. Furthermore, we identified critical circRTN4-intercting proteins by circRNA-pulldown in PDAC cells. CircRTN4 interacted with important epithelial-mesenchymal transition (EMT)- driver RAB11FIP1 to block its ubiquitination site. We found that circRTN4 knockdown promoted the degradation of RAB11FIP1 by increasing its ubiquitination. Also, circRTN4 knockdown inhibited the expression of RAB11FIP1-regulating EMT-markers Slug, Snai1, Twist, Zeb1 and N-cadherin in PDAC.ConclusionThe upregulated circRTN4 promotes tumor growth and liver metastasis in PDAC through the novel circRTN4-miR-497-5p-HOTTIP pathway. Also, circRTN4 stabilizes RAB11FIP1 to contribute EMT.Graphical abstract

ETV4 promotes pancreatic ductal adenocarcinoma metastasis through activation of the CXCL13/CXCR5 signaling axis.

Pancreatic ductal adenocarcinoma (PDAC) has the highest fatality rate of any solid tumor, with a five-year survival rate of only 10% in the USA. PDAC is characterized by early metastasis. More than 50% of patients present with distant metastases at the time of diagnosis, and the majority of patients will develop metastasis within 4 years after tumor resection. Despite extensive studies, the molecular mechanisms underlying PDAC metastasis remain unclear. The polyoma enhancer activator protein (PEA3) subfamily was reported to play a vital role in the initiation and progression of multiple tumors. Herein, we found that ETS variant 4 (ETV4) was highly expressed in PDAC tissues and associated with poor survival. Univariate and multivariate analyses revealed that ETV4 expression was an independent prognostic factor for patient survival. Further experiments showed that ETV4 overexpression promoted PDAC invasion and metastasis both in vitro and in vivo. For the first time, we demonstrated that, mechanistically, ETV4 increased CXCR5 expression by directly binding to the CXCR5 promoter region. Knockdown of CXCR5 significantly reversed ETV4-mediated PDAC migration and invasion, while CXCR5 overexpression exerted the opposite effects. Intriguingly, we found that CXCL13, a specific ligand of CXCR5, increased ETV4 expression and promoted PDAC invasion and metastasis by activating the ERK1/2 pathway. ETV4 knockdown significantly abrogated the enhanced migratory and invasive abilities induced by the CXCL13/CXCR5 axis. In addition, a CXCR5 neutralizing antibody disrupted the CXCL13/ETV4/CXCR5 positive feedback loop and inhibited cell migration and invasion. Overall, in this study, we demonstrated that ETV4 plays a vital role in PDAC metastasis and defined a novel CXCL13/ETV4/CXCR5 positive feedback loop. Targeting this pathway has implications for potential therapeutic strategies for PDAC treatment.

Peptidase Inhibitor 16 Promote Proliferation and Metastasis in Pancreatic Ductal Adenocarcinoma via Oligoadenylate Synthetase L

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a highly invasive cancer with poor prognosis. As a member of the CAP superfamily, Peptidase inhibitor 16 (Pi16) is still unclear in most tumor studies. In our recent research, we were the first to find that Pi16 is highly expressed in PDAC tissues, and might regulate the proliferation and metastasis of PDAC by combining with Oligoadenylate synthetase L (OASL). Method: Immunohistochemistry and quantitative RT-PCR methods were used to detect the expression levels of Pi16 protein and mRNA in PDAC patients. The CRISPR-Cas9 technology was used to knocked out the expression of Pi16 in PDAC cell lines. Tests in vivo and in vitro were used to verify the effect of Pi16 on PDAC proliferation and metastasis. By RNA sequencing, we found that OASL can serve as a potential downstream of Pi16. Results: The expression of Pi16 was higher in cancer tissues compared with matched adjacent tissues. High expression of Pi16 was associated with PDAC progression and poor prognosis. Overexpression of ROBO1 could promote the proliferation and metastasis of PDAC cells in vitro. It was found that Pi16 could bind to OASL by bioinformatics analysis and Co-immunoprecipitation (Co-IP) assay. Moreover, the function recovery test confirmed that Pi16 could promote the proliferation and metastasis of PDAC via OASL. Conclusions: Our present study demonstrates that Pi16 might participate in the occurrence and development of PDAC by regulating cell proliferation and metastasis by combining with OASL, and indicates that Pi16 might be a new promising therapeutic target for PDAC.Tabled 1VariablePi16 expressionHighLowP valueAge (year) ≤ 607140.267> 602224Histological grade I/I-II19260.802II/II-III/III1012T stage T1,T222310.568T3,T477Clinical stage I-IIa11240.041IIb-IV1814 Open table in a new tab

Pirfenidone-loaded exosomes derived from pancreatic ductal adenocarcinoma cells alleviate fibrosis of premetastatic niches to inhibit liver metastasis.

Given the metastasis-promoting effect of pancreatic ductal adenocarcinoma (PDAC)-derived exosomes through activation of fibrotic premetastatic niches, targeting and intervening in premetastatic organs to inhibit distant metastasis have challenged researchers and clinicians. Herein, a self-biomimetic drug delivery system based on exosomes derived from PDAC (PF@PCCEs) was constructed to precisely deliver an antifibrotic drug (pirfenidone, PF) to fibrotic premetastatic organs. First, PDAC-derived exosomes were confirmed to remarkably promote liver fibrosis. Then the prepared PF@PCCEs were actively internalized by HSCs (hepatic stellate cells) and subsequently alleviated the activation of HSCs. Delivery of PF to the premetastatic liver affected the niche suitable for the colonization of circulating tumour cells, further suppressing liver metastasis of PDAC. Thus, the strategy for intervening in the formation of fibrotic premetastatic niches to inhibit liver metastasis of PDAC using PF@PCCEs might offer inspiration for the treatment of tumour metastasis.

Survival Benefit of Resection Surgery for Pancreatic Ductal Adenocarcinoma with Liver Metastases: A Propensity Score-Matched SEER Database Analysis.

Simple SummaryPancreatic ductal adenocarcinoma is a devastating illness but guidelines consider it unresectable once metastasized. However, resection of the primary tumor is carried out in select cases and retrospective analyses indicate that this may improve survival. Even so, these analyses are limited to single centers or fail to account for biased patient selection. We overcome these limitations with a propensity score-matched SEER database analysis that reliably demonstrates surgery can extend overall survival. Furthermore, we identify prognostic factors that could aid the selection of patients for randomized controlled trials. Thus, this study paves the way for future work that aims to update treatment guidelines in accordance with surgical developments.Guidelines do not recommend resection surgery for oligometastatic pancreatic ductal adenocarcinoma (PDAC). However, reports in small samples of selected patients suggest that surgery extends survival. Thus, this study aims to gather evidence for the benefits of cancer-directed surgery (CDS) by analyzing a national cohort and identifying prognostic factors that aid the selection of candidates for CDS or recruitment into experimental trials. Data for patients with PDAC and hepatic metastasis were extracted from the population-based Surveillance, Epidemiology, and End Results database (SEER). The bias between CDS and non-CDS groups was minimized with Propensity Score Matching (PSM), and the prognostic role of CDS was investigated by comparing Kaplan-Meier estimators and Cox proportional hazard models. A total of 12,018 patients were extracted from the database, including 259 patients who underwent CDS that were 1:1 propensity score-matched with patients who did not receive CDS. CDS appeared to significantly prolong median overall survival from 5 to 10 months. Multivariate analysis revealed chemotherapy as a protective prognostic, whilst survival was impaired by old age and tumors that were poorly differentiated (Grades III–IV). These factors can be used to select patients likely to benefit from CDS treatment, which may facilitate recruitment into randomized controlled trials.

HDAC2 Facilitates Pancreatic Cancer Metastasis.

HDAC2 has a context-specific role in undifferentiated PDAC and the capacity to disseminate systemically, implicating HDAC2 as targetable protein to prevent metastasis.

Targeted intervention of eIF4A1 inhibits EMT and metastasis of pancreatic cancer cells via c-MYC/miR-9 signaling

BackgroundOwing to the lack of effective treatment options, early metastasis remains the major cause of pancreatic ductal adenocarcinoma (PDAC) recurrence and mortality. However, the molecular mechanism of early metastasis is largely unknown. We characterized the function of eukaryotic translation initiation factors (eIFs) in epithelial-mesenchymal-transition (EMT) and metastasis in pancreatic cancer cells to investigate whether eIFs and downstream c-MYC affect EMT and metastasis by joint interference.MethodsWe used The Cancer Genome Atlas (TCGA) and Genome Tissue Expression (GTEx) databases to analyze eIF4A1 expression in PDAC tissues and further validated the findings with a microarray containing 53 PDAC samples. Expression regulation and pharmacological inhibition of eIF4A1 and c-MYC were performed to determine their role in migration, invasion, and metastasis in pancreatic cancer cells in vitro and in vivo.ResultsElevated eIF4A1 expression was positively correlated with lymph node infiltration, tumor size, and indicated a poor prognosis. eIF4A1 decreased E-cadherin expression through the c-MYC/miR-9 axis. Loss of eIF4A1 and c-MYC decreased the EMT and metastasis capabilities of pancreatic cancer cells, whereas upregulation of eIF4A1 attenuated the inhibition of EMT and metastasis induced by c-MYC downregulation. Treatment with the eIF4A1 inhibitor rocaglamide (RocA) or the c-MYC inhibitor Mycro3 either alone or in combination significantly decreased the expression level of EMT markers in pancreatic cancer cells in vitro. However, the efficiency and safety of RocA alone were not inferior to those of the combination treatment in vivo.ConclusionOverexpression of eIF4A1 downregulated E-cadherin expression through the c-MYC/miR-9 axis, which promoted EMT and metastasis of pancreatic cancer cells. Despite the potential feedback loop between eIF4A1 and c-MYC, RocA monotherapy is a promising treatment inhibiting eIF4A1-induced PDAC metastasis.

Therapeutic Targeting of Autophagy in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease characterized by early metastasis, late detection, and poor prognosis. Progress towards effective therapy has been slow despite significant efforts. Novel treatment approaches are desperately needed and autophagy, an evolutionary conserved process through which proteins and organelles are recycled for use as alternative energy sources, may represent one such target. Although incompletely understood, there is growing evidence suggesting that autophagy may play a role in PDAC carcinogenesis, metastasis, and survival. Early clinical trials involving autophagy inhibiting agents, either alone or in combination with chemotherapy, have been disappointing. Recently, evidence has demonstrated synergy between the MAPK pathway and autophagy inhibitors in PDAC, suggesting a promising therapeutic intervention. In addition, novel agents, such as ONC212, have preclinical activity in pancreatic cancer, in part through autophagy inhibition. We discuss autophagy in PDAC tumorigenesis, metabolism, modulation of the immune response, and preclinical and clinical data with selected autophagy modulators as therapeutics.

Reciprocal regulation of LOXL2 and HIF1\u03b1 drives the Warburg effect to support pancreatic cancer aggressiveness

Hypoxic microenvironment is common in solid tumors, particularly in pancreatic ductal adenocarcinoma (PDAC). The Warburg effect is known to facilitate cancer aggressiveness and has long been linked to hypoxia, yet the underlying mechanism remains largely unknown. In this study, we identify that lysyl oxidase-like 2 (LOXL2) is a hypoxia-responsive gene and is essential for the Warburg effect in PDAC. LOXL2 stabilizes hypoxia-inducible factor 1α (HIF1α) from prolyl hydroxylase (PHD)-dependent hydroxylation via hydrogen peroxide generation, thereby facilitating the transcription of multiple glycolytic genes. Therefore, a positive feedback loop exists between LOXL2 and HIF1α that facilitates glycolytic metabolism under hypoxia. Moreover, LOXL2 couples the Warburg effect to tumor growth and metastasis in PDAC. Hijacking glycolysis largely compromises LOXL2-induced oncogenic activities. Collectively, our results identify a hitherto unknown hypoxia-LOXL2-HIF1α axis in regulating the Warburg effect and provide an intriguing drug target for PDAC therapy.

Emerging Role of miR-345 and Its Effective Delivery as a Potential Therapeutic Candidate in Pancreatic Cancer and Other Cancers.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with high mortality, poor prognosis, and palliative treatments, due to the rapid upregulation of alternative compensatory pathways and desmoplastic reaction. miRNAs, small non-coding RNAs, have been recently identified as key players regulating cancer pathogenesis. Dysregulated miRNAs are associated with molecular pathways involved in tumor development, metastasis, and chemoresistance in PDAC, as well as other cancers. Targeted treatment strategies that alter miRNA levels in cancers have promising potential as therapeutic interventions. miRNA-345 (miR-345) plays a critical role in tumor suppression and is differentially expressed in various cancers, including pancreatic cancer (PC). The underlying mechanism(s) and delivery strategies of miR-345 have been investigated by us previously. Here, we summarize the potential therapeutic roles of miR-345 in different cancers, with emphasis on PDAC, for miRNA drug discovery, development, status, and implications. Further, we focus on miRNA nanodelivery system(s), based on different materials and nanoformulations, specifically for the delivery of miR-345.

Magnetic resonance molecular imaging of extradomain B fibronectin enables detection of pancreatic ductal adenocarcinoma metastasis

Extradomain-B Fibronectin (EDB-FN) is an oncomarker that can be visualized with magnetic resonance molecular imaging (MRMI) to detect pancreatic ductal adenocarcinoma (PDAC) metastasis. In this study, we sought to assess the expression of EDB-FN in clinical samples of PDAC and to evaluate MRMI of PDAC metastasis with an EDB-FN-specific gadolinium-based contrast agent (MT218) in an orthotopic KPC-GFP-Luc mouse model. EDB-FN expression was evaluated in PDAC tissue samples through immunohistochemistry. RNA-Seq data obtained from the GEPIA2 project was evaluated to demonstrate EDB-FN expression in large patient cohorts. FLASH-3D MRI at 3 T of the KPC-GFP-Luc metastasis model was performed following injection of MT218. Tumor enhancement in MR images was correlated to postmortem distribution of KPC-GFP-Luc tumors using fluorescent and bright-field cryo-imaging and anatomical landmarks. EDB-FN immunohistochemical staining scores of human metastatic tumor stroma, (2.17 ± 0.271), metastatic tumor parenchyma (2.08 ± 0.229), primary tumor stroma (1.61 ± 0.26), and primary tumor parenchyma (1.61 ± 0.12) were significantly (p < 0.0001) higher than normal pancreas stroma (0.14 ± 0.10) and normal pancreas parenchyma (0.14 ± 0.14). EDB-FN mRNA expression in tumors is 4.98 log2(TPM + 1) and 0.18 log2(TPM + 1) in normal tissue (p < 0.01). A mouse model of EDB-FN rich PDAC metastasis exhibited T1-weighted contrast to noise (CNR) changes of 21.80 ± 4.34 in perimetastatic regions and 8.38 ± 0.79 in metastatic regions identified through cryo-imaging, significantly higher (p < 0.05) than CNR changes found in normal liver (−6.43 ± 0.92), mesentery (2.24 ± 0.92), spleen (−3.06 ± 2.38) and intestine (1.08 ± 2.15). We conclude that EDB-FN is overexpressed in metastatic and primary PDAC tumors and MRMI with MT218 enables the detection of metastatic and perimetastatic tissues.

Abstract PO-006: CircRTN4 promotes pancreatic cancer progression through a novel circRNA-miRNA-lncRNA pathway and stabilizing epithelial-mesenchymal transition protein

Abstract Background &amp; Aims: Circular RNAs (circRNAs) play important roles in many biological processes. However, the detailed mechanism underlying the critical roles of circRNAs in cancer remains largely unexplored. We aim to explore the molecular mechanisms of circRTN4 with critical roles in pancreatic ductal adenocarcinoma (PDAC). Methods: CircRTN4 expression level was examined in PDAC primary tumors. The oncogenic roles of circRTN4 in PDAC tumor growth and metastasis were studied in mouse tumor models. Bioinformatics analysis, luciferase assay and miRNA pulldown assay were performed to study the novel circRTN4-miRNA-lncRNA pathway. To identify circRTN4-interacting proteins, we performed circRNA-pulldown and mass spectrometry in PDAC cells. Protein stability assay and 3-Dimensional structure modeling were performed to reveal the role of circRTN4 in stabilizing RAB11FIP1. Results: circRTN4 was significantly upregulated in primary tumors from PDAC patients. In vitro and in vivo functional studies revealed that circRTN4 promoted PDAC tumor growth and liver metastasis. Mechanistically, circRTN4 interacted with tumor suppressor miR-497-5p in PDAC cells. CircRTN4 knockdown upregulated miR-497-5p to inhibit the oncogenic lncRNA HOTTIP expression. Furthermore, we identified critical circRTN4-intercting proteins by circRNA-pulldown in PDAC cells. CircRTN4 interacted with important epithelial-mesenchymal transition (EMT)- driver RAB11FIP1 to block its ubiquitination site. We found that circRTN4 knockdown promoted the degradation of RAB11FIP1 by increasing its ubiquitination. Also, circRTN4 knockdown inhibited the expression of RAB11FIP1-regulating EMT-markers Slug, Snai1, Twist, Zeb1 and N-cadherin in PDAC. Conclusion: The upregulated circRTN4 promotes tumor growth and liver metastasis in PDAC through the novel circRTN4-miR-497-5p-HOTTIP pathway. Also, circRTN4 stabilizes RAB11FIP1 to contribute EMT. Citation Format: Chi Hin Wong, Ut Kei Lou, Frederic Khe-Cheong Fung, Joanna H. M. Tong, Ka-Fai To, Stephen Lam Chan, Yangchao Chen. CircRTN4 promotes pancreatic cancer progression through a novel circRNA-miRNA-lncRNA pathway and stabilizing epithelial-mesenchymal transition protein [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-006.

The next "sweet" spot for pancreatic ductal adenocarcinoma: Glycoprotein for early detection.

Pancreatic ductal adenocarcinoma (PDAC) is the most common neoplastic disease of the pancreas, accounting for more than 90% of all pancreatic malignancies. As a highly lethal malignancy, PDAC is the fourth leading cause of cancer-related deaths worldwide with a 5-year overall survival of less than 8%. The efficacy and outcome of PDAC treatment largely depend on the stage of disease at the time of diagnosis. Surgical resection followed by adjuvant chemotherapy remains the only possibly curative therapy, yet 80%-90% of PDAC patients present with nonresectable PDAC stages at the time of clinical presentation. Despite our advancing knowledge of PDAC, the prognosis remains strikingly poor, which is primarily due to the difficulty of diagnosing PDAC at the early stages. Recent advances in glycoproteomics and glycomics based on mass spectrometry have shown that aberrations in protein glycosylation plays a critical role in carcinogenesis, tumor progression, metastasis, chemoresistance, and immuno-response of PDAC and other types of cancers. A growing interest has thus been placed upon protein glycosylation as a potential early detection biomarker for PDAC. We herein take stock of the advancements in the early detection of PDAC that were carried out with mass spectrometry, with special focus on protein glycosylation.

Genomic Landscape in Neoplasm-Like Stroma Reveals Distinct Prognostic Subtypes of Pancreatic Ductal Adenocarcinoma.

As a main component of the tumor microenvironment, the stroma is critical in development, progression, and metastasis of pancreatic ductal adenocarcinoma (PDAC). The genomic status and its relationship of neoplastic and stromal components remain unclear in PDAC. We performed targeted sequencing for 1,021 cancer-suspected genes on parallel microdissected stromal and neoplastic components from 50 operable PDAC patients. Clonality analysis of mutations was conducted to reconstruct the evolutionary trajectory, and then molecular subtypes were established. Multi-lineage differentiation potential and mesenchymal transformation of KRAS-mutant cell line Panc1 were evaluated using RT-PCR and immunofluorescence staining. In this study, 39 (78.0%) were genomically altered in stroma, with KRAS (71.8%), TP53 (61.5%), and CDKN2A (23.1%) as the most commonly mutated genes. The majority of stromal mutations (89.8%) were detected in matched neoplastic components. Patients with KRAS/TP53-mut stroma demonstrated a higher tumor cell fraction (TCF) than did those with wild-type (WT) stroma (p = 0.0371, p = 0.0014). In both components, mutants KRAS and TP53 often occurred as clonal events, and the allele frequencies presented linear correlation in the same specimen. All neoplasm-like stroma (characterized with all or initial neoplastic clones and driver events in stroma) harbored KRAS or TP53 mutations. Neoplasm-like and KRAS-mutant stroma was associated with shorter disease-free survival. It is a new finding for the existence of driver gene mutations in PDAC stroma. These data suggest that genomic features of stromal components may serve as prognostic biomarkers in resectable PDAC and might help to guide a more precise treatment paradigm in therapeutic options.