Panel Of Pancreatic Ductal Adenocarcinoma Cell Lines Research Articles

Dysregulation of a Subset of Circulating and Vesicle-Associated miRNA in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive neoplasia, characterized by early metastasis, low diagnostic rates at early stages, resistance to drugs, and poor prognosis. There is an urgent need to better characterize this disease in order to identify efficient diagnostic/prognostic biomarkers. Since microRNAs (miRNAs) contribute to oncogenesis and metastasis formation in PDAC, they are considered potential candidates for fulfilling this task. In this work, the levels of two miRNA subsets (involved in chemoresistance or with oncogenic/tumor suppressing functions) were investigated in a panel of PDAC cell lines and liquid biopsies of a small cohort of patients. We used RT-qPCR and droplet digital PCR (ddPCR) to measure the amounts of cellular- and vesicle-associated, and circulating miRNAs. We found that both PDAC cell lines, also after gemcitabine treatment, and patients showed low amounts of cellular-and vesicle-associated miR-155-5p, compared to controls. Interestingly, we did not find any differences when we analyzed circulating miR-155-5p. Furthermore, vesicle-related miR-27a-3p increased in cancer patients compared to the controls, while circulating let-7a-5p, miR-221-3p, miR-23b-3p and miR-193a-3p presented as dysregulated in patients compared to healthy individuals. Our results highlight the potential clinical significance of these analyzed miRNAs as non-invasive diagnostic molecular tools to characterize PDAC.

Abstract 955: Double-targeting of pancreatic ductal adenocarcinoma (PDAC): Unveiling the potent combination of NMS-873 and BAY-876

Abstract Pancreatic ductal adenocarcinoma (PDAC) stands out as one of the most aggressive and challenging-to-treat cancers known. Consequently, the development of effective therapeutic strategies holds significant importance in enhancing patient outcomes. In contrast to single-drug treatments, combination therapies offer the potential for improved results by addressing multiple pathways. This approach not only reduces the likelihood of drug resistance but also encourages synergistic effects, all while permitting the use of lower individual drug doses, thus minimizing potential side effects. In this study, we subjected a panel of PDAC cell lines with varying degrees of sensitivity to a high-throughput combinatorial drug screen. Mitochondrial complex 1/p97 inhibitor NMS-873 was tested in combination with 95 other compounds, revealing remarkable synergy when paired with Glut1 inhibitor BAY-876. In order to affirm the validity of these findings, we conducted further experiments involving multi-dose drug combinations within long-term clonogenic assays. These supplementary investigations also demonstrated significant synergistic effects between BAY-876 and NMS-873, as quantified through the calculation of Bliss and Zip scores. Notably, this combination exhibited superior efficacy when confronting PDAC cell lines that are more resistant to NMS-873, highlighting the potential of this combination to overcome therapy resistance. To gain insights into the underlying mechanisms behind these outcomes, we performed a gene enrichment analysis which revealed that the more sensitive cell lines exhibited elevated rates of cell division, while the more resistant ones demonstrated heightened cRNA processing and increased metabolic activity, particularly in protein, phospholipid, and lipid synthesis. The combination of BAY-876 and NMS-873 presents a promising avenue for the targeted treatment of PDAC. This study underscores the remarkable synergy observed in mouse PDAC cell lines with a particular emphasis on the heightened efficacy against cell populations that are more resistant to NMS-873. These results warrant further investigation to elucidate the underlying molecular mechanisms and validate these findings in clinical settings. Citation Format: Emily Rita Eppinger, Christian Schneeweis, Dieter Saur. Double-targeting of pancreatic ductal adenocarcinoma (PDAC): Unveiling the potent combination of NMS-873 and BAY-876 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 955.

A Novel 3DNA® Nanocarrier effectively delivers payloads to pancreatic tumors

IntroductionStandard-of-care systemic chemotherapies for pancreatic ductal adenocarcinoma (PDAC) currently have limited clinical benefits, in addition to causing adverse side effects in many patients. One factor known to contribute to the poor chemotherapy response is the poor drug diffusion into PDAC tumors. Novel treatment methods are therefore drastically needed to improve targeted delivery of treatments. Here, we evaluated the efficacy of the 3DNA® Nanocarrier (3DNA) platform to direct delivery of therapeutics to PDAC tumors in vivo. Materials and MethodsA panel of PDAC cell lines and a patient tissue microarray were screened for established tumor-specific proteins to identify targeting moieties for active targeting of the 3DNA. NRG mice with or without orthotopic MIA PaCa-2-luciferase PDAC tumors were treated intraperitoneally with 100 μl of fluorescently labeled 3DNA. ResultsFolic acid and transferrin receptors were significantly elevated in PDAC compared to normal pancreas. Accordingly, both folic acid- and transferrin-conjugated 3DNA treatments significantly increased delivery of 3DNA specifically to tumors in comparison to unconjugated 3DNA treatment. In the absence of tumors, there was an increased clearance of both folic acid-conjugated 3DNA and unconjugated 3DNA, compared to the clearance rate in tumor-bearing mice. Lastly, delivery of siLuciferase by folic acid-conjugated 3DNA in an orthotopic model of luciferase-expressing PDAC showed significant and prolonged suppression of luciferase protein expression and activity. ConclusionOur study progresses the 3DNA technology as a reliable and effective treatment delivery platform for targeted therapeutic approaches in PDAC.

Overexpression of laminin-5 gamma-2 promotes tumorigenesis of pancreatic ductal adenocarcinoma through EGFR/ERK1/2/AKT/mTOR cascade.

Pancreatic ductal adenocarcinoma (PDAC) is correlated with poor outcomes because of limited therapeutic options. Laminin-5 gamma-2 (LAMC2) plays a critical role in key biological processes. However, the detailed molecular mechanism and potential roles of LAMC2 in PDAC stay unexplored. The present study examines the essential role and molecular mechanisms of LAMC2 in the tumorigenesis of PDAC. Here, we identified that LAMC2 is significantly upregulated in microarray cohorts and TCGA RNA sequencing data of PDAC patients compared to non-cancerous/normal tissues. Patients with higher transcript levels of LAMC2 were correlated with clinical stages; dismal overall, as well as, disease-free survival. Additionally, we confirmed significant upregulation of LAMC2 in a panel of PDAC cell lines and PDAC tumor specimens in contrast to normal pancreatic tissues and cells. Inhibition of LAMC2 significantly decreased cell growth, clonogenic ability, migration and invasion of PDAC cells, and tumor growth in the PDAC xenograft model. Mechanistically, silencing of LAMC2 suppressed expression of ZEB1, SNAIL, N-cadherin (CDH2), vimentin (VIM), and induced E-cadherin (CDH1) expression leading to a reversal of mesenchymal to an epithelial phenotype. Interestingly, co-immunoprecipitation experiments demonstrated LAMC2 interaction with epidermal growth factor receptor (EGFR). Further, stable knockdown of LAMC2 inhibited phosphorylation of EGFR, ERK1/2, AKT, mTOR, and P70S6 kinase signaling cascade in PDAC cells. Altogether, our findings suggest that silencing of LAMC2 inhibited PDAC tumorigenesis and metastasis through repression of epithelial-mesenchymal transition and modulation of EGFR/ERK1/2/AKT/mTOR axis and could be a potential diagnostic, prognostic, and therapeutic target for PDAC.

Post-translational down-regulation of Nrf2 and YAP proteins, by targeting deubiquitinases, reduces growth and chemoresistance in pancreatic cancer cells

The intrinsic chemoresistance of pancreatic ductal adenocarcinoma (PDAC) represents the main obstacle in treating this aggressive malignancy. It has been observed that high antioxidant levels and upregulated Nrf2 and the YAP protein expression can be involved in PDAC chemoresistance. The mechanisms of Nrf2 and YAP increase need to be clarified.We chose a panel of PDAC cell lines with diverse sensitivity to cisplatin and gemcitabine. In PANC-1 chemoresistant cells, we found a low level of oxidative stress and high levels of Nrf2 and YAP protein expressions and their respective targets. On the contrary, in CFPAC-1 chemosensitive cells, we found high levels of oxidative stress and low level of these two proteins, as well as their respective targets. In MiaPaCa-2 cells with a middle chemoresistance, we observed intermediate features. When Nrf2 and YAP were inhibited in PANC-1 cells by Ailanthone, a plant extract, we observed a reduction of viability, thus sustaining the role of these two proteins in maintaining the PDAC chemoresistance.We then delved into the mechanisms of the Nrf2 and YAP protein upregulation in chemoresistance, discovering that it was at a post-translational level since the mRNA expressions did not match the protein levels. Treatments of PANC-1 cells with the proteasome inhibitor MG-132 and the protein synthesis inhibitor cycloheximide further confirmed this observation.The expression of DUB3 and OTUD1 deubiquitinases, involved in the control of Nrf2 and YAP protein level, respectively, was also investigated. Both protein expressions were higher in PANC-1 cells, intermediate in MiaPaCa-2 cells, and lower in CFPAC-1 cells. When DUB3 or OTUD1 were silenced, both Nrf2 and YAP expressions were downregulated.Importantly, in deubiquitinase-silenced cells, we observed a great reduction of proliferation and a higher sensitivity to gemcitabine treatment, suggesting that DUB3 and OTUD1 can represent a suitable target to overcome chemoresistance in PDAC cells.

Abstract 238: Targeting glutaminolysis potentiates the efficacy of chemotherapy in RAS-driven pancreatic cancers

Abstract Pancreatic cancer is an extremely aggressive and deadly malignancy. Despite a detailed understanding of pancreatic ductal adenocarcinoma (PDAC)'s biology, the outcome of the current therapeutic regimen remains grim. Chemotherapeutic treatment is one of the first-line systemic treatments for PDAC. However, creating resistance against chemotherapy remains a major challenge. Oncogenic K-Ras mutation is one of the most common events responsible for the initiation and progression of PDAC. K-Ras mutation also promotes the activation of a transcription factor called NRF2 that is crucial for tumor development and pancreatic cancer proliferation. Our study detects differential basal levels of NRF2 in a panel of PDAC cell lines. We hypothesized that this phenomenon might reflect a greater intrinsic capacity of PDAC cells to become resistant to chemotherapy. We then demonstrated that up-regulation of NRF2 creates resistance against chemotherapy in PDAC cells. Consequently, NRF2 activation rewires metabolic pathway networks. Importantly, our metabolomics analysis revealed that, upon NRF2 activation, several metabolic pathways are reprogrammed. Recent advances in tumor metabolism signify the critical role of glutamine as a key regulator of cancer therapy. Moreover, we observed that inhibiting glutamine metabolism enhances the efficacy of chemotherapeutic drugs in PDAC cells. Taken together, our finding holds promise as a novel combination therapy for patients with pancreatic cancer marked by developed resistance against chemotherapy. Finally, this treatment strategy further establishes the potential for exploiting metabolic changes in RAS-driven cancer cells that confer novel therapeutic opportunities. Citation Format: Suman Mukhopadhyay, Debanjan Goswami, Dwight V. Nissley, Frank McCormick. Targeting glutaminolysis potentiates the efficacy of chemotherapy in RAS-driven pancreatic cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 238.

Histoepigenetic analysis of the mesothelin network within pancreatic ductal adenocarcinoma cells reveals regulation of retinoic acid receptor gamma and AKT by mesothelin

To enable computational analysis of regulatory networks within the cancer cell in its natural tumor microenvironment, we develop a two-stage histoepigenetic analysis method. The first stage involves iterative computational deconvolution to estimate sample-specific cancer-cell intrinsic expression of a gene of interest. The second stage places the gene within a network module. We validate the method in simulation experiments, show improved performance relative to differential expression analysis from bulk samples, and apply it to illuminate the role of the mesothelin (MSLN) network in pancreatic ductal adenocarcinoma (PDAC). The network analysis and subsequent experimental validation in a panel of PDAC cell lines suggests AKT activation by MSLN through two known activators, retinoic acid receptor gamma (RARG) and tyrosine kinase non receptor 2 (TNK2). Taken together, these results demonstrate the potential of histoepigenetic analysis to reveal cancer-cell specific molecular interactions directly from patient tumor profiles.

Abstract A47: Targeting glutaminolysis potentiates the efficacy of chemotherapy in RAS-driven pancreatic cancers

Abstract Pancreatic cancer is an extremely aggressive and deadly malignancy. Despite a detailed understanding of pancreatic ductal adenocarcinoma (PDAC)’s biology, the outcome of the current therapeutic regimen remains grim. Chemotherapeutic treatment is one of the first-line systemic treatments for PDAC. However, creating resistance against chemotherapy remains a major challenge. Oncogenic K-Ras mutation is one of the most common events responsible for the initiation and progression of PDAC. K-Ras mutation also promotes the activation of a transcription factor called NRF2 that is crucial for tumor development and pancreatic cancer proliferation. Our study detects differential basal levels of NRF2 in a panel of PDAC cell lines. We hypothesized that this phenomenon might reflect a greater intrinsic capacity of PDAC cells to become resistant to chemotherapy. We then demonstrated that upregulation of NRF2 creates resistance against chemotherapy in PDAC cells. Consequently, NRF2 activation rewires metabolic pathway networks. Importantly, our metabolomics analysis revealed that, upon NRF2 activation, several metabolic pathways are reprogrammed. Recent advances in tumor metabolism signify the critical role of glutamine as a key regulator of cancer therapy. Moreover, we observed that inhibiting glutamine metabolism enhances the efficacy of chemotherapeutic drugs in PDAC cells. Taken together, our finding holds promise as a novel combination therapy for patients with pancreatic cancer marked by developed resistance against chemotherapy. Finally, this treatment strategy further establishes the potential for exploiting metabolic changes in RAS-driven cancer cells that confer novel therapeutic opportunities. Citation Format: Suman Mukhopadhyay, Pavan Adiseshaiah, Debanjan Goswami, Dwight V. Nissley, Frank McCormick. Targeting glutaminolysis potentiates the efficacy of chemotherapy in RAS-driven pancreatic cancers [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr A47.

Antiplatelet Drug Ticagrelor Enhances Chemotherapeutic Efficacy by Targeting the Novel P2Y12-AKT Pathway in Pancreatic Cancer Cells.

Background: Extensive research has reported that extracellular ADP in the tumour microenvironment can stimulate platelets through interaction with the platelet receptor P2Y12. In turn, activated platelets release biological factors supporting cancer progression. Experimental data suggest that the tumour microenvironment components, of which platelets are integral, can promote chemotherapy resistance in pancreatic ductal adenocarcinoma (PDAC). Thus, overcoming chemoresistance requires combining multiple inhibitors that simultaneously target intrinsic pathways in cancer cells and extrinsic factors related to the tumour microenvironment. We aimed to determine whether ticagrelor, an inhibitor of the ADP–P2Y12 axis and a well-known antiplatelet drug, could be a therapeutic option for PDAC. Methods: We investigated a functional P2Y12 receptor and its downstream signalling in a panel of PDAC cell lines and non-cancer pancreatic cells termed hTERT-HPNE. We tested the synergistic effect of ticagrelor, a P2Y12 inhibitor, in combination with chemotherapeutic drugs (gemcitabine, paclitaxel and cisplatin), in vitro and in vivo. Results: Knockdown studies revealed that P2Y12 contributed to epidermal growth factor receptor (EGFR) activation and the expression of SLUG and ZEB1, which are transcriptional factors implicated in metastasis and chemoresistance. Studies using genetic and pharmacological inhibitors showed that the P2Y12–EGFR crosstalk enhanced cancer cell proliferation. Inhibition of P2Y12 signalling significantly reduced EGF-dependent AKT activation and promoted the anticancer activity of anti-EGFR treatment. Importantly, ticagrelor significantly decreased the proliferative capacity of cancer but not normal pancreatic cells. In vitro, synergism was observed when ticagrelor was combined with several chemodrugs. In vivo, a combination of ticagrelor with gemcitabine significantly reduced tumour growth, whereas gemcitabine or ticagrelor alone had a minimal effect. Conclusions: These findings uncover a novel effect and mechanism of action of the antiplatelet drug ticagrelor in PDAC cells and suggest a multi-functional role for ADP-P2Y12 signalling in the tumour microenvironment.

Hyaluronan activated-metabolism phenotype (HAMP) in pancreatic ductal adenocarcinoma.

Background: The aggressiveness of pancreatic ductal adenocarcinoma (PDAC) is enhanced by its interactions with stromal extracellular matrix, notably with hyaluronan (HA). Our previous studies have demonstrated increased expression of genes involved in HA synthesis and degradation in PDAC, suggesting the presence of an autocrine mechanism which accelerates the production of low-molecular-weight HA. Results: A subset of PDAC (20% of cell lines and 25% of tissues) showed overexpression of multiple genes encoding both HA-synthesizing and HA-degrading enzymes, displaying a phenotype defined as an HA activated-metabolism phenotype (HAMP). Interestingly, HAMP+ cells were more susceptible to the treatment with an HA synthesis inhibitor and HA degradation inhibitor than HAMP- cells. Patients with HAMP+ tumors were significantly associated with shorter survival than those with HAMP- tumors (P = 0.049). Methods: We investigated transcriptional profiling of genes involved in HA synthesis (including HAS2 and HAS3) and degradation (including HYAL1 and KIAA1199) in a panel of PDAC cell lines and primary tissues. Response of PDAC cells to treatment with an HA synthesis inhibitor (4-methylumbelliferone) or HA degradation inhibitor (dextran sulfate) was examined by cell migration assay. Survival was determined by Kaplan–Meier curve and compared by log-rank test. Conclusions: The present study identified a novel phenotype, HAMP, characterized by activation of HA metabolism pathways, in PDAC. HAMP should be further investigated as a prognostic marker as well as a target for personalized medicine.

Selective Inhibition of Histone Deacetylases 1/2/6 in Combination with Gemcitabine: A Promising Combination for Pancreatic Cancer Therapy.

Pancreatic ductal adenocarcinoma (PDAC) has a five-year survival rate of <10% due in part to a lack of effective therapies. Pan-histone deacetylase (HDAC) inhibitors have shown preclinical efficacy against PDAC but have failed in the clinic due to toxicity. Selective HDAC inhibitors may reduce toxicity while retaining therapeutic efficacy. However, their use requires identification of the specific HDACs that mediate the therapeutic effects of HDAC inhibitors in PDAC. We determined that the HDAC1/2/3 inhibitor Mocetinostat synergizes with the HDAC4/5/6 inhibitor LMK-235 in a panel of PDAC cell lines. Furthermore, while neither drug alone synergizes with gemcitabine, the combination of Mocetinostat, LMK-235, and gemcitabine showed strong synergy. Using small interfering (si)RNA-mediated knockdown, this synergy was attributed to inhibition of HDACs 1, 2, and 6. Pharmacological inhibition of HDACs 1 and 2 with Romidepsin and HDAC6 with ACY-1215 also potently synergized with gemcitabine in a panel of PDAC cell lines, and this drug combination potentiated the antitumor effects of gemcitabine against PDAC xenografts in vivo. Collectively, our data show that inhibition of multiple HDACs is required for therapeutic effects of HDAC inhibitors and support the development of novel strategies to inhibit HDACs 1, 2, and 6 for PDAC therapy.

Abstract 4264: Lysosome inhibition sensitizes pancreatic cancer to replication stress by aspartate depletion

Abstract Objective: Functional lysosomes are required for autophagy and macropinocytosis, the intra- and extracellular scavenging pathways cancer cells engage for nutrient acquisition. Pancreatic ductal adenocarcinoma (PDAC) tumors exhibit high basal lysosomal activity, and genetic or pharmacologic inhibition of lysosome function suppresses PDAC cell proliferation and tumor growth. However, the codependencies induced by lysosomal inhibition in PDAC have not been systematically explored. We hypothesized that identification and targeting the lysosomal inhibition-induced codependencies in PDAC cells would be an effective therapeutic strategy. Methods: A comprehensive pharmacological inhibition screen of the protein kinome was performed to identified lysosomal inhibition-induced codependency. LC-MS/MS-MRM and LC-MS methods were used to examine nucleotide biosynthesis and amino acid levels, respectively, to understand the mechanism of the identified codependency. A broad panel of PDAC cell lines, primary PDAC culture models, two- and three-dimentional culture models, a PDAC cell/stroma spheroid coculture model, and xenograft and syngeneic PDAC animal models were used to evaluate the treatment efficacy. Results: We found that replication stress response (RSR) inhibitors were synthetically lethal with chloroquine (CQ) and other lysosomal inhibitors in PDAC cells. CQ treatment reduced de novo nucleotide biosynthesis and induced replication stress. We found that CQ treatment caused mitochondrial dysfunction and depletion of aspartate, an essential precursor for de novo nucleotide synthesis, as an underlying mechanism. Supplementation with aspartate in PDAC cell culture and overexpression of the aspartate transporter SLC1A3 in xenograft PDAC tumors partially rescued the phenotypes induced by CQ. The synergy of CQ and the RSR inhibitor VE-822 was comprehensively validated in a broad panel of PDAC cell lines and primary PDAC cultures, in two- and three-dimentional PDAC cultures, in heterotypic spheroid culture with cancer-associated fibroblasts, and in in vivo xenograft and syngeneic PDAC mouse models. Conclusion: We discovered a codependency on functional lysosomes and an intact RSR pathway in PDAC, and developed the combination of CQ and RSR inhibitors as a translational therapeutic approach for PDAC. Citation Format: Shili Xu, Irmina A. Elliott, Amanda M. Dann, Stephanie S. Kim, Evan R. Abe, Woosuk Kim, Soumya Poddar, Alexandra Moore, Lei Zhou, Jennifer L. Williams, Joseph R. Capri, Razmik Ghukasyan, Cynthia Matsumura, D. Andrew Tucker, Wesley R. Armstrong, Anthony E. Cabebe, Nanping Wu, Luyi Li, Thuc M. Le, Caius G. Radu, Timothy R. Donahue. Lysosome inhibition sensitizes pancreatic cancer to replication stress by aspartate depletion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4264.

Mesothelin and TGF-α predict pancreatic cancer cell sensitivity to EGFR inhibitors and effective combination treatment with trametinib.

Clinical trials of EGFR inhibitors in combination with gemcitabine for the treatment of pancreatic ductal adenocarcinoma (PDAC) have generated mixed results partially due to the poorly defined effectiveness of EGFR inhibitors in PDAC. Here, we studied a panel of PDAC cell lines to compare the IC50s of the EGFR inhibitors gefitinib and cetuximab. We found that gefitinib induced biphasic inhibition in over 50% of PDAC cells, with the initial growth inhibition occurring at nanomolar concentrations and a second growth inhibition occurring outside the clinical range. In contrast to gefitinib, cetuximab produced a single phase growth inhibition in a subset of PDAC cells. Using this sensitivity data, we screened for correlations between cell morphology proteins and EGFR ligands to EGFR inhibitor sensitivity, and found that mesothelin and the EGFR ligand TGF-α have a strong correlation to gefitinib and cetuximab sensitivity. Analysis of downstream signaling pathways indicated that plc-γ1 and c-myc were consistently inhibited by EGFR inhibitor treatment in sensitive cell lines. While an inconsistent additive effect was observed with either cetuximab or gefitinib in combination with gemcitabine, the cell pathway data indicated consistent ERK activation, leading us to pursue EGFR inhibitors in combination with trametinib, a MEK1/2 inhibitor. Both cetuximab and gefitinib in combination with trametinib produced an additive effect in all EGFR sensitive cell lines. Our results indicate that mesothelin and TGF-α can predict PDAC sensitivity to EGFR inhibitors and a combination of EGFR inhibitors with trametinib could be a novel effective treatment for PDAC.

Upregulated circular RNA circ_0007534 indicates an unfavorable prognosis in pancreatic ductal adenocarcinoma and regulates cell proliferation, apoptosis, and invasion by sponging miR-625 and miR-892b.

Circular RNAs (circRNAs) have been regarded as critical regulators of human diseases and biological markers in some types of malignancies, including pancreatic ductal adenocarcinoma (PDAC). Recently, circ_0007534 has been identified as a novel cancer-related circRNA. Nevertheless, its clinical relevance, functional roles,and mechanism have not been studied in PDAC. In the current study, real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of circ_0007534 in 60-paired PDAC tissue samples and different cell lines. Loss-of-function and gain-of-function assays were performed to detect cell proliferation, apoptosis, and metastatic properties affected by circ_0007534. Ananimal study was also carried out. The luciferase reporter assay was performed to uncover the underlying mechanism of circ_0007534. As a result, circ_0007534 was overexpressed not only in PDAC tissues but also in a panel of PDAC cell lines, and this overexpression is closely associated with advanced tumor stage and positive lymph node invasion. In addition, circ_0007534 may be regarded as an independent prognostic factor for patients with PDAC. For the part of functional assays, circ_0007534 significantly increased cell proliferation, migratory, and invasive potential of PDAC cells. Circ_0007534 could inhibit cell apoptosis partly via aBcl-2/caspase-3 pathway. The xenograft study further confirmed the cell growth promoting therole of circ_0007534. Mechanistically, miR-625 and miR-892b were sponged by circ_0007534. The oncogenic functions of circ_0007534 is partly dependent on its regulation of miR-625 and miR-892b. In conclusion, our study illuminates a novel circRNA that confers an oncogenic function in PDAC.

Upregulated long noncoding RNA LINC01296 indicates a dismal prognosis for pancreatic ductal adenocarcinoma and promotes cell metastatic properties by affecting EMT.

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease that responds poorly to chemotherapy and radiotherapy and whose incidence has increased worldwide. Long noncoding RNAs have been demonstrated to play important roles in cancer initiation and progression. Long intergenic non-coding RNA 01296 (LINC01296) has been reported to be upregulated in several malignancies, but the clinical relevance and biological role of LINC01296 in PDAC are still unclear. RT-qPCR was performed to evaluate the expression of LINC01296 in 85 pared PDAC tissue samples and a panel of PDAC cell lines. The clinical value and prognostic role of LINC01296 in patients with PDAC were further explored. Furthermore, we explored the functional roles of LINC01296 depletion in PANC-1 and SW1990 cells, including cell proliferation, apoptosis, migration, invasion, and epithelial-to-mesenchymal transition (EMT). LINC01296 was enhanced in PDAC tissues and cell lines, and this overexpression was correlated with advanced tumor stages and positive lymph node metastasis in patients with PDAC. In addition, upregulation of LINC01296 was an independent prognostic predictor for patients with PDAC after surgery. Moreover, silencing of LINC01296 followed by treatment with small interfering RNAs suppressed cell proliferation and promoted cell apoptosis by affecting the Bcl-2/caspase-3 pathway. Importantly, LINC01296 attenuation impaired the migratory and invasive potential partly by reversing EMT. Overall, our work may help to develop a novel prognostic biomarker and therapeutic target for PDAC.

Trichostatin A alters cytoskeleton and energy metabolism of pancreatic adenocarcinoma cells: An in depth proteomic study.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal of all human cancers with a high mortality rate. Resistance to conventional treatments and chemotherapeutics is a typical feature of PDAC. To investigate the causes of drug resistance it is essential to deeply investigate the mechanism of action of chemotherapeutics. In this study, we performed an in depth shotgun proteomic approach using the label-free proteomic SWATH-MS analysis to investigate novel insights of the mechanism of action of the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) in PDAC cells. This proteomic analysis in PaCa44 cells and data elaboration of TSA-regulated proteins by bioinformatics showed an overall up-regulation of cytokeratins and other proteins related to the cytoskeleton organization, keratinization, and apoptotic cell death. On the contrary, a large amount of the down-regulated proteins by TSA treatment belongs to the cellular energetic metabolism and to the machinery of protein synthesis, such as ribosomal proteins, determining synergistic cell growth inhibition by the combined treatment of TSA and the glycolytic inhibitor 2-deoxy-d-glucose in a panel of PDAC cell lines. Data are available via ProteomeXchange with identifier PXD007801.

USP5 promotes tumorigenesis and progression of pancreatic cancer by stabilizing FoxM1 protein

Increased ubiquitin-specific protease 5 (USP5) has been associated with tumorigenesis of malignancy including glioblastoma, melanoma and hepatocellular carcinoma. However, the role of USP5 in tumorigenesis of pancreatic ductal adenocarcinoma (PDAC) has not been studied yet. In this study, we demonstrated that USP5 was significantly upregulated in a panel of PDAC cell lines and correlated with FoxM1 protein expression. USP5 knockdown inhibited proliferation of PANC-1 and SW1990, two PDAC cell lines. In the mouse xenografted pancreatic tumor model, suppression of USP5 significantly decreased tumor growth, correlated with down regulation of FoxM1. Additionally, we found that overexpression of USP5 stabilized the FoxM1 protein in PDAC cells. Overexpression of USP5 extended the half-life of FoxM1. Knockdown of USP5 in PANC-1 cells decreased FoxM1 protein level while the proteasome inhibitor MG-132 treatment restored FoxM1 expression. We also found that endogenous USP5 was coimmunoprecipitated with an endogenous FoxM1 from PANC-1 cells while FoxM1 was also coimmunoprecipitated with USP5. Furthermore, we also confirmed that USP5 regulated proliferation of PDAC via FoxM1 by rescuing the inhibitory effect of USP5 knockdown with ectopic expression of FoxM1 in USP5-depleted cells. Taken together, our study demonstrates that USP5 plays a critical role in tumorigenesis and progression of pancreatic cancer by stabilizing FoxM1 protein, and provides a rationale for USP5 being a potential therapeutic approach against PDAC.

Novel p21-Activated Kinase 4 (PAK4) Allosteric Modulators Overcome Drug Resistance and Stemness in Pancreatic Ductal Adenocarcinoma.

The p21-activated kinase 4 (PAK4) is a key downstream effector of the Rho family GTPases and is found to be overexpressed in pancreatic ductal adenocarcinoma (PDAC) cells but not in normal human pancreatic ductal epithelia (HPDE). Gene copy number amplification studies in PDAC patient cohorts confirmed PAK4 amplification making it an attractive therapeutic target in PDAC. We investigated the antitumor activity of novel PAK4 allosteric modulators (PAM) on a panel of PDAC cell lines and chemotherapy-resistant flow-sorted PDAC cancer stem cells (CSC). The toxicity and efficacy of PAMs were evaluated in multiple subcutaneous mouse models of PDAC. PAMs (KPT-7523, KPT-7189, KPT-8752, KPT-9307, and KPT-9274) show antiproliferative activity in vitro against different PDAC cell lines while sparing normal HPDE. Cell growth inhibition was concurrent with apoptosis induction and suppression of colony formation in PDAC. PAMs inhibited proliferation and antiapoptotic signals downstream of PAK4. Co-immunoprecipitation experiments showed disruption of PAK4 complexes containing vimentin. PAMs disrupted CSC spheroid formation through suppression of PAK4. Moreover, PAMs synergize with gemcitabine and oxaliplatin in vitro KPT-9274, currently in a phase I clinical trial (clinicaltrials.gov; NCT02702492), possesses desirable pharmacokinetic properties and is well tolerated in mice with the absence of any signs of toxicity when 200 mg/kg daily is administered either intravenously or orally. KPT-9274 as a single agent showed remarkable antitumor activity in subcutaneous xenograft models of PDAC cell lines and CSCs. These proof-of-concept studies demonstrated the antiproliferative effects of novel PAMs in PDAC and warrant further clinical investigations. Mol Cancer Ther; 16(1); 76-87. ©2016 AACR.

Abstract B77: Vitamin D suppresses pancreatic cancer growth through inhibition of autocrine Wnt/β-catenin signaling

Abstract Epidemiological studies indicate higher vitamin D levels are associated with a reduced risk for pancreatic ductal adenocarcinoma (PDAC) and other malignancies. Although vitamin D analogs inhibit the growth of some PDAC cell lines in vitro and in vivo, a clinical trial with an active metabolite of vitamin D (seocalcitol) demonstrated no objective response in patients with inoperable PDAC. In addition to initiating vitamin D receptor (VDR) mediated transcription, vitamin D is known to inhibit Wnt/β-catenin signaling, a pathway recently shown to play a critical role in pancreatic cancer initiation and progression. For this study we chose to explore a possible link between these two signaling pathways. Initially, we found VDR expression strongly correlated with endogenous Wnt/β-catenin signaling activity across a large panel of PDAC cell lines, suggesting VDR may serve as a critical mediator of Wnt/β-catenin signaling in PDAC and/or that VDR itself may be a transcriptional target of the Wnt pathway. Therefore, we next determined whether the growth inhibitory effects of vitamin D analog calcipotriol in PDAC cell lines could be mechanistically linked to its action on Wnt/β-catenin signaling. Using a β-catenin-activated reporter, we found calcipotriol inhibited Wnt/β-catenin signaling and anchorage-dependent growth in a dose-dependent manner and with greater efficacy in those PDAC cell lines with high levels of endogenous Wnt/β-catenin signaling (Wnt high). In parallel, calcipotriol also inhibited anchorage-independent growth of the same Wnt high PDAC lines in soft agar assays, a phenotype we have previously shown to be critically linked to autocrine Wnt/β-catenin signaling activity. Previously published work in colorectal cancer finds vitamin D initiates a physical interaction between VDR and β-catenin that translocates β-catenin from the nucleus to the plasma membrane to inhibit Wnt/β-catenin mediated transcription. However, in exploring this potential biochemical interaction in PDAC cell lines we have been unable to co-immunoprecipitate VDR and β-catenin, leading us to speculate that vitamin D disrupts Wnt/β-catenin signaling through a novel alternative mechanism that we are currently investigating. In conclusion, the present study identifies a subset of PDAC cell lines defined by higher levels of Wnt/β-catenin signaling that show increased sensitivity to vitamin D-mediated growth inhibition. These results may be of clinical utility in stratifying patients most likely to benefit from vitamin D-based therapy. Citation Format: Michael Dawson Arensman, Claire Ostertag-Hill, Anna Rose Lay, David Dawson. Vitamin D suppresses pancreatic cancer growth through inhibition of autocrine Wnt/β-catenin signaling. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B77.

Investigating autophagy and glutamine metabolism as therapeutic targets for pancreatic cancer.

381 Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer, for which new therapeutic approaches are urgently needed. We are developing novel combination therapy approaches based on the inhibition of glutamine metabolism and autophagy, to improve current treatments for PDAC. Since both processes are key mediators of multiple cancer hallmarks, and have inter-related but non-redundant roles, this combination may result in a more efficient disruption of cancer cell resistance to treatments. Methods: We interrogated the Pancreas Centre BC tissue micro-array, containing the epithelial component of 252 PDAC samples, for expression of three key glutamine-metabolizing proteins and two autophagy-related proteins: glutamine synthetase (GLUL), asparagine synthetase (ASNS), glutaminase C (GLS-GAC), microtubule-associated protein 1 light chain 3 beta (MAP1-LC3B or LC3B) and autophagy-related protein 4B (ATG4B). While previous efforts by other groups have focused on GLS-GAC, the role of GLUL in cancer has remained less well understood. We thus investigated the functional relevance of GLUL using a panel of PDAC cell lines. We are also investigating interactions between glutamine metabolism and autophagy, including the exploration of strategies to target GLUL and the evaluation of a new class of ATG4B inhibitors for the treatment of pancreatic cancers. Results: We found that GLUL, ASNS, GLS-GAC, LC3B and ATG4B were expressed in 31%, 58%, 99%, 51% and 73%, respectively, of PDAC samples. Furthermore, higher LC3B expression correlated with poor outcome. Our functional studies revealed that various PDAC cells express GLUL, which can be upregulated upon glutamine deprivation. In all cell lines tested, GLUL knockdown sensitized them to gemcitabine, as assessed by a long-term recovery assay. We also found that the candidate ATG4B inhibitors, shown to inhibit this target in cell-free assays, effectively inhibit PDAC cell proliferation at micromolar concentrations. Conclusions: Our study reveals that glutamine metabolism and autophagy are clinically relevant in PDAC and may have potential as therapeutic targets. Supported by Pancreas Centre BC, BC Cancer Foundation and VGH Foundation.