Target For Pancreatic Ductal Adenocarcinoma Research Articles

Molecular Pathogenesis of Pancreatic Ductal Adenocarcinoma: Impact of miR-30c-5p and miR-30c-2-3p Regulation on Oncogenic Genes.

Simple SummaryA total of 10 genes (YWHAZ, F3, TMOD3, NFE2L3, ENDOD1, ITGA3, RRAS, PRSS23, TOP2A, and LRRFIP1) were identified as tumor suppressive miR-30c-5p and miR-30c-2-3p targets in pancreatic ductal adenocarcinoma (PDAC), and expression of these genes were independent prognostic factors for patient survival. Furthermore, aberrant expression of TOP2A and its transcriptional activators (SP1 and HMGB2) enhanced malignant transformation of PDAC cells.Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive types of cancer, and its prognosis is abysmal; only 25% of patients survive one year, and 5% live for five years. MicroRNA (miRNA) signature analysis of PDAC revealed that both strands of pre-miR-30c (miR-30c-5p, guide strand; miR-30c-2-3p, passenger strand) were significantly downregulated, suggesting they function as tumor-suppressors in PDAC cells. Ectopic expression assays demonstrated that these miRNAs attenuated the aggressiveness of PDAC cells, e.g., cell proliferation, migration, and invasiveness. Through a combination of in silico analyses and gene expression data, we identified 216 genes as putative oncogenic targets of miR-30c-5p and miR-30c-2-3p regulation in PDAC cells. Among these, the expression of 18 genes significantly predicted the 5-year survival rates of PDAC patients (p < 0.01). Importantly, the expression levels of 10 genes (YWHAZ, F3, TMOD3, NFE2L3, ENDOD1, ITGA3, RRAS, PRSS23, TOP2A, and LRRFIP1) were found to be independent prognostic factors for patient survival (p < 0.01). We focused on TOP2A (DNA Topoisomerase II Alpha) and investigated its potential as a therapeutic target for PDAC. The overexpression of TOP2A and its transcriptional activators (SP1 and HMGB2) was detected in PDAC clinical specimens. Moreover, the knockdown of TOP2A enhanced the sensitivity of PDAC cells to anticancer drugs. Our analyses of the PDAC miRNA signature and tumor-suppressive miRNAs provide important insights into the molecular pathogenesis of PDAC.

Immunological Gene Signature Associated With the Tumor Microenvironment of Pancreatic Cancer After Neoadjuvant Chemotherapy.

Neoadjuvant chemotherapy (NAC) has improved overall survival in patients with pancreatic ductal adenocarcinoma (PDAC), but its effects on immune gene signatures are unknown. Here, we examined the immune transcriptome after NAC for PDAC. Resected tumor specimens were obtained from 140 patients with PDAC who received surgery first (n = 93) or NAC (n = 47). Six patients were randomly selected from each group, and RNA was extracted from tumor tissues. We compared 770 immune-related genes among the 2 groups using nCounterPanCancer Immune Profiling (NanoString Technologies, Seattle, Wash). Gene clusters were classified into 14 immune function groups based on gene ontology argolism by nSolver 4.0 software (NanoString Technologies), and corresponding immune cell function scores were compared. Eleven genes (LY86, SH2D1A, CD247, TIGIT, CR2, CD83, LAMP3, CXCR4, DUSP4, SELL, and IL2RA) were significantly downregulated in the NAC group. Gene expression analysis showed that the functions of regulatory T cells, B cells, and natural killer CD56 dim cells were significantly decreased in the NAC group. Neoadjuvant chemotherapy may suppress regulatory T cells and B-cell function in the PDAC microenvironment. The 11 identified genes could be useful for predicting the efficacy of NAC and could be therapeutic targets for PDAC.

MYEOV increases HES1 expression and promotes pancreatic cancer progression by enhancing SOX9 transactivity.

Emerging evidence indicates that myeloma overexpressed (MYEOV) is an oncogene and plays crucial roles in multiple human cancers. However, its roles in the development of pancreatic ductal adenocarcinoma (PDAC) remain elusive. Here, we provide evidence of essential roles of MYEOV in the development and progression of PDAC. In tumor specimens derived from pancreatic cancer patients, MYEOV was overexpressed and associated with poor prognosis. In addition, MYEOV expression in PDAC was upregulated through promoter hypomethylation. MYEOV depletion impaired metastatic ability and proliferation of PDAC cells both in vitro and in vivo, whereas its overexpression had the opposite effect. Mechanistic investigations revealed that MYEOV interacted with SRY-Box Transcription Factor 9 (SOX9), a well-known oncogenic transcription factor in PDAC. This interaction occurred mainly in the nuclei of PDAC cells and increased transcriptional activity of SOX9. Furthermore, MYEOV promoted the expression of Hairy and enhancer of split homolog-1 (HES1), a SOX9 target gene, by enhancing SOX9 DNA-binding ability to the HES1 enhancer without affecting the protein level and subcellular localization of SOX9. HES1 knockdown partly abrogated the oncogenic effect of MYEOV. Our findings suggest that MYEOV could be a potential prognostic biomarker and therapeutic target for PDAC.

Use of ratiometrically designed nanocarrier targeting CDK4/6 and autophagy pathways for effective pancreatic cancer treatment

Aberrant cell cycle machinery and loss of the CDKN2A tumor suppressor locus make CDK4/6 a potential target in pancreatic ductal adenocarcinoma (PDAC). However, a vast majority of PDAC cases do not harbor a durable response to monotherapy of CDK4/6 inhibitor. Utilizing remote loading to co-encapsulate CDK4/6 inhibitor palbociclib (PAL) and an autophagy inhibitor hydroxychloroquine (HCQ), we demonstrate a ratiometrically designed mesoporous silica nanoformulation with synergistic efficacy in subcutaneous and orthotopic PDAC mouse models. The synergism is attributed to the effective intratumoral buildup of PAL/HCQ, which otherwise exhibit distinctly different circulatory and biodistribution profile. PAL/HCQ co-delivery nanoparticles lead to the most effective shrinkage of PDAC compared to various controls, including free drug mixture. Immunohistochemistry reveals that PAL/HCQ co-delivery nanoparticles trigger anti-apoptotic pathway after repetitive intravenous administrations in mice. When combined with a Bcl inhibitor, the performance of co-delivery nanoparticles is further improved, leading to a long-lasting anti-PDAC effect in vivo.

Abstract 6041: LAMC2 as a therapeutic target in pancreatic ductal adenocarcinoma

Abstract BACKGROUND. Pancreatic cancer stands as one of the deadliest tumors, in part due to the limited efficacy of currently existing therapies. Pancreatic ductal adenocarcinoma (PDAC) represents the predominant subtype (around 85% of total cases), where KRAS is the most frequently mutated oncogene. Tumor microenvironment in PDAC is characterized by a desmoplastic stroma which is composed, among other molecules, of collagens of different types, fibronectin and laminins. A member of the laminin family, LAMININ γ2 or LAMC2, was previously identified by our group as part of a cross-tumors KRAS signature whose high expression was a marker of poor survival in PDAC patients. Given the relevant functional implication of other members of the cross-tumors KRAS signature in PDAC, we aimed to investigate the role of LAMC2 in this tumor type. METHODS. A meta-analysis of several human PDAC data sets (n=6) and survival analysis of the TCGA data were performed to query the expression levels and prognosis significance of LAMC2. Human and mouse PDAC cell lines as well as a mouse model of PDAC (Kras, Tp53f/f, Ptf1aCre) were used to assess LAMC2 expression. In vitro (2D and 3D organoids) and in vivo models derived from human and mouse PDAC cell lines or primary tumors were used to define the functional role of LAMC2 in PDAC. Lastly, cellular and molecular analysis were deployed to dissect the mechanism of action of LAMC2 in PDAC. RESULTS. At the clinical level, we have observed that LAMC2 is overexpressed in human PDAC patients with regard to normal tissue and that its high levels identify the group of patients with the worst survival. The overexpression of LAMC2 was recapitulated in human and mouse cell lines. Genetic depletion of LAMC2 had an adverse effect in 2D proliferation, clonogenic efficiency, 3D organoid growth, and PDAC-based xenograft/allograft tumor development. This deleterious effect is driven by an induction in apoptosis and a decrease in S phase consistent across species. Mechanistically, LAMC2 is mainly linked to the KRAS pathway through ERK1/2 and is transcriptionally regulated by the transcription factor FOSL1/AP1, which was also a member of the cross-tumors signature. These data suggest that LAMC2 is involved in the control of different functions related to the PDAC phenotype induced by KRAS. CONCLUSION. LAMC2 is a molecular target in PDAC with clinical implications based on the potential development of new therapeutic and diagnostic strategies for PDAC patients. Citation Format: Oihane Erice, Ester Blanco, Karmele Valencia, Elizabeth Guruceaga, Haritz Moreno, Fernando Lecanda, Vincenzo Corbo, Daniel Ölund, Mariano Ponz-Sarvise, Vicent Silve. LAMC2 as a therapeutic target in pancreatic ductal adenocarcinoma [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 6041.

Abstract 1720: Preclinical treatment of pancreatic ductal adenocarcinoma using targetable self-assembled gemcitabine nanoparticles

Abstract The prognosis of pancreatic ductal adenocarcinoma (PDAC) patients remains poor, and new effective therapies are urgently needed. Cytotoxic gemcitabine (GEM) is currently used as a standard-of-care drug for PDAC treatment but its efficacy is greatly compromised mainly due to quick metabolism in the body and drug resistance. Here we introduce a new simple approach to effectively deliver GEM to PDAC-derived tumors through the combination of a prodrug strategy, nanoparticle formulation, and PDAC-specific targeting strategy. By covalently conjugating GEM with a hydrophobic moiety (i.e. linoleic acid) via amide linkage, the resulting GEM prodrug was conferred with an amphiphilic feature and showed spontaneously self-assembling behavior in aqueous solution. The self-assembled nanoparticles were spherical and monodispersed in water with a diameter less than 100 nm. To optimize the nanoparticles for the in vivo use, DSPE-PEG2k was used to co-assemble with the prodrug. A PDAC-specific peptide was further decorated on the particle surface to endow the nanoparticles with PDAC targeting effect. In vitro assays on PDAC cell lines showed that the modified GEM nanoparticles exhibited superior efficacy than free GEM, and the conjugation of the targeting peptide significantly facilitated the internalization of the nanoparticles into the targeted cancer cells. Furthermore, in vivo evaluation in xenograft-bearing animal models derived from either established cancer cells or patient tumor tissues showed that these GEM nanoparticles were remarkably effective to inhibit tumor growth with alleviated side effects. These data confirmed the effectiveness of our self-assembling GEM prodrug strategy. Moreover, this cost-effective strategy can potentially be applied broadly to many other chemotherapeutic drugs that are insufficiently effective because of pharmacologic obstacles. Citation Format: Zhang Fu. Preclinical treatment of pancreatic ductal adenocarcinoma using targetable self-assembled gemcitabine nanoparticles [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 1720.

Depletion of Macrophages Improves Therapeutic Response to Gemcitabine in Murine Pancreas Cancer.

Background: The tumor microenvironment (TME) is composed of fibro-inflammatory cells and extracellular matrix (ECM) components. However, the exact contribution of the various TME compartments towards therapeutic response is unknown. Here, we aim to dissect the specific contribution of tumor-associated macrophages (TAMs) towards drug delivery and response in pancreatic ductal adenocarcinoma (PDAC). Methods: The effect of gemcitabine was assessed in human and murine macrophages, human pancreatic stellate cells (hPSCs), and tumor cells (L3.6pl, BxPC3 and KPC) in vitro. The drug metabolism of gemcitabine was analyzed by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Preclinical studies were conducted using KrasG12D;p48-Cre and KrasG12D;p53172H;Pdx-Cre mice to investigate gemcitabine delivery at different stages of tumor progression and upon pharmacological TAM depletion. Results: Gemcitabine accumulation was significantly increased in murine PDAC tissue compared to pancreatic intraepithelial neoplasia (PanIN) lesions and healthy control pancreas tissue. In vitro, macrophages accumulated and rapidly metabolized gemcitabine resulting in a significant drug scavenging effect for gemcitabine. Finally, pharmacological TAM depletion enhanced therapeutic response to gemcitabine in tumor-bearing KPC mice. Conclusion: Macrophages rapidly metabolize gemcitabine in vitro, and pharmacological depletion improves the therapeutic response to gemcitabine in vivo. Our study supports the notion that TAMs might be a promising therapeutic target in PDAC.

Immunotherapeutic strategies in pancreatic ductal adenocarcinoma (PDAC): current perspectives and future prospects.

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest human malignancies with a dismal prognosis. During PDAC progression, the immune response is affected as cancer cells evade detection and elimination. Recently, there have been advances in the treatment of PDAC using immunotherapy, although a lot more work is yet to be done. In this review, we discuss these advances, challenges and potentials. We focus on existing and potential immune targets for PDAC, drugs used to target them, and some clinical trials conducted so far with them. Finally, novel targets in the tumour microenvironment such as stromal cells and other potential future areas to explore including bacterial therapy and the use of neoantigens in immunotherapy are highlighted.

TRPM7/RPSA Complex Regulates Pancreatic Cancer Cell Migration.

Pancreatic ductal adenocarcinoma (PDAC) is a malignancy with a very poor prognosis due to highly metastatic profile. Cell migration is an essential step of the metastatic cascade allowing cancer cells to spread toward target tissues. Recent studies strongly suggest that bioactive elastin peptides, also named elastokines or elastin-derived peptides (EDPs), are released in the extracellular microenvironment during tumoral remodeling of the stroma. EDPs stimulate cancer cell migration by interacting with their membrane receptor, ribosomal protein SA (RPSA). Others membrane proteins like ion channels are also involved in cancer cell migration. It has been recently shown that the transient receptor potential melastatin-related 7 (TRPM7) channel regulates PDAC cell migration and invasion. The objective of this work was to study the effect of EDPs on TRPM7 channel in human pancreatic cancer cells. We showed that EDPs promote MIA PaCa-2 cell migration using Boyden chamber assay. Cells transfected with a siRNA targeting TRPM7 were not able to migrate in response to EDPs indicating that TRPM7 regulated cell migration induced by these peptides. Moreover, EDPs were able to stimulate TRPM7 currents recorded by Patch-Clamp. Finally, we showed that TRPM7 channels and RPSA receptors are colocalized at the plasma membrane of human pancreatic cancer cells. Taken together, our data suggest that TRPM7/RPSA complex regulated human pancreatic cancer cell migration. This complex may be a promising therapeutic target in PDAC.

PAICS, a De Novo Purine Biosynthetic Enzyme, Is Overexpressed in Pancreatic Cancer and Is Involved in Its Progression

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with an extremely poor prognosis. There is an urgent need to identify new therapeutic targets and also understand the mechanism of PDAC progression that leads to aggressiveness of the disease. To find therapeutic targets, we analyzed data related to PDAC transcriptome sequencing and found overexpression of the de novo purine metabolic enzyme phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS). Immunohistochemical analysis of PDAC tissues showed high expression of the PAICS protein. To assess the biological roles of PAICS, we used RNA interference and knock down of its expression in PDAC cell lines that caused a reduction in PDAC cell proliferation and invasion. Furthermore, results of chorioallantoic membrane assays and pancreatic cancer xenografts demonstrated that PAICS regulated pancreatic tumor growth. Our data also showed that, in PDAC cells, microRNA-128 regulates and targets PAICS. PAICS depletion in PDAC cells caused upregulation in E-cadherin, a marker of the epithelial-mesenchymal transition. In PDAC cells, a BET inhibitor, JQ1, reduced PAICS expression. Thus, our investigations show that PAICS is a therapeutic target for PDAC and, as an enzyme, is amenable to targeting by small molecules.

Circular RNA circBFAR promotes the progression of pancreatic ductal adenocarcinoma via the miR-34b-5p/MET/Akt axis

BackgroundAccumulating evidence suggests that circular RNAs (circRNAs) are important participants in cancer progression. However, the biological processes and underlying mechanisms of circRNAs in pancreatic ductal adenocarcinoma (PDAC) are unclear.MethodCircRNAs were verified by Sanger sequencing. Colony formation, 5-Ethynyl-2′-deoxyuridine (EdU), and Transwell assays were performed to investigate the effect of circBFAR on the proliferation, invasion, and migration of PDAC cells in vitro. RNA pull-down assays were conducted to verify the binding of circBFAR with microRNA miR-34b-5p.ResultsIn the present study, we identified a novel circRNA (termed as circBFAR, hsa_circ_0009065) that was upregulated in a 208-case cohort of patients with PDAC. The ectopic expression of circBFAR correlated positively with the tumor-node-metastasis (TNM) stage and was related to poorer prognosis of patients with PDAC. Moreover, circBFAR knockdown dramatically inhibited the proliferation and motility of PDAC cells in vitro and their tumor-promoting and metastasis properties in in vivo models. Mechanistically, circBFAR upregulated mesenchymal-epithelial transition factor (MET) expression via sponging miR-34b-5p. Additionally, circBFAR overexpression increased the expression of MET and activated downstream phosphorylation of Akt (Ser 473) and further activated the MET/PI3K/Akt signaling pathway, which ultimately promoted the progression of PDAC cells. Importantly, application of MET inhibitors could significantly attenuate circBFAR-mediated tumorigenesis in vivo.ConclusionsOur findings showed that circBFAR plays an important role in the proliferation and metastasis of PDAC, which might be explored as a potential prognostic marker and therapeutic target for PDAC.

CYR61/CCN1 expression in resected pancreatic ductal adenocarcinoma: A retrospective pilot study of the interaction between the tumors and their surrounding microenvironment

BackgroundCCN1 is an extracellular matrix-associated protein thought to be implicated in tumor-stromal interaction in several solid tumors. The aim of our pilot study was to evaluate the correlation between CCN1 expression in stromal cells, pancreatic intraepithelial neoplasia (PanIN) and pancreatic ductal adenocarcinoma cells in resected pancreatic ductal adenocarcinoma (PDAC) specimens, and correlate that clinically. MethodsA total of 42 paraffin-embedded PDAC tumor specimens were stained for CCN1 and evaluated via immunohistochemical (IHC) analysis. Statistical analysis was performed to correlate between CCN1 expression profiles in tumor tissues and clinicopathological parameters of patients. ResultsOur results showed CCN1 (CYR61) gene was highly expressed in PDAC tissues relative to other organ specific tumor tissues. Also, moderate and overexpression of CCN1 in PanIN was associated with PanIN grade 3 tissues. A statistically significant association was found between PanIN CCN1 scores on one hand and cancer stage, cancer grade, and CCN1 expression among ductal tumor cells and adjacent stromal cells on the other hand. DiscussionThe associations demonstrated suggest that CCN1 might be contributing to a substantial role in the interaction between the pancreatic tumors on one hand and their surrounding microenvironment and their precursors on the other hand; hence, it might serve as a potential therapeutic target for PDAC.

MiR-93 is related to poor prognosis in pancreatic cancer and promotes tumor progression by targeting microtubule dynamics

Biomarkers and effective therapeutic agents to improve the dismal prognosis of pancreatic ductal adenocarcinoma (PDAC) are urgently required. We aimed to analyze the prognostic value and mechanistic action of miR-93 in PDAC. Correlation of miR-93 tumor levels from 83 PDAC patients and overall survival (OS) was analyzed by Kaplan–Meier. MiR-93 depletion in PANC-1 and MIA PaCa-2 cells was achieved by CRISPR/Cas9 and miR-93 overexpression in HPDE cells by retroviral transduction. Cell proliferation, migration and invasion, cell cycle analysis, and in vivo tumor xenografts in nude mice were assessed. Proteomic analysis by mass spectrometry and western-blot was also performed. Finally, miR-93 direct binding to candidate mRNA targets was evaluated by luciferase reporter assays. High miR-93 tumor levels are significantly correlated with a worst prognosis in PDAC patients. MiR-93 abolition altered pancreatic cancer cells phenotype inducing a significant increase in cell size and a significant decrease in cell invasion and proliferation accompanied by a G2/M arrest. In vivo, lack of miR-93 significantly impaired xenograft tumor growth. Conversely, miR-93 overexpression induced a pro-tumorigenic behavior by significantly increasing cell proliferation, migration, and invasion. Proteomic analysis unveiled a large group of deregulated proteins, mainly related to G2/M phase, microtubule dynamics, and cytoskeletal remodeling. CRMP2, MAPRE1, and YES1 were confirmed as direct targets of miR-93. MiR-93 exerts oncogenic functions by targeting multiple genes involved in microtubule dynamics at different levels, thus affecting the normal cell division rate. MiR-93 or its direct targets (CRMP2, MAPRE1, or YES1) are new potential therapeutic targets for PDAC.

Identifying Drug Targets in Pancreatic Ductal Adenocarcinoma Through Machine Learning, Analyzing Biomolecular Networks, and Structural Modeling.

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer-related death and has an extremely poor prognosis. Thus, identifying new disease-associated genes and targets for PDAC diagnosis and therapy is urgently needed. This requires investigations into the underlying molecular mechanisms of PDAC at both the systems and molecular levels. Herein, we developed a computational method of predicting cancer genes and anticancer drug targets that combined three independent expression microarray datasets of PDAC patients and protein-protein interaction data. First, Support Vector Machine–Recursive Feature Elimination was applied to the gene expression data to rank the differentially expressed genes (DEGs) between PDAC patients and controls. Then, protein-protein interaction networks were constructed based on the DEGs, and a new score comprising gene expression and network topological information was proposed to identify cancer genes. Finally, these genes were validated by “druggability” prediction, survival and common network analysis, and functional enrichment analysis. Furthermore, two integrins were screened to investigate their structures and dynamics as potential drug targets for PDAC. Collectively, 17 disease genes and some stroma-related pathways including extracellular matrix-receptor interactions were predicted to be potential drug targets and important pathways for treating PDAC. The protein-drug interactions and hinge sites predication of ITGAV and ITGA2 suggest potential drug binding residues in the Thigh domain. These findings provide new possibilities for targeted therapeutic interventions in PDAC, which may have further applications in other cancer types.

SETDB1 Inhibits p53-Mediated Apoptosis and Is Required for Formation of Pancreatic Ductal Adenocarcinomas in Mice

SETDB1, a histone methyltransferase that trimethylates histone H3 on lysine 9, promotes development of several tumor types. We investigated whether SETDB1 contributes to development of pancreatic ductal adenocarcinoma (PDAC). We performed studies with Ptf1aCre; KrasG12D; Setdb1f/f, Ptf1aCre; KrasG12D; Trp53f/+; Setdb1f/f, and Ptf1aCre; KrasG12D; Trp53f/f; Setdb1f/f mice to investigate the effects of disruption of Setdb1 in mice with activated KRAS-induced pancreatic tumorigenesis, with heterozygous or homozygous disruption of Trp53. We performed microarray analyses of whole-pancreas tissues from Ptf1aCre; KrasG12D; Setdb1f/f, and Ptf1aCre; KrasG12D mice and compared their gene expression patterns. Chromatin immunoprecipitation assays were performed using acinar cells isolated from pancreata with and without disruption of Setdb1. We used human PDAC cells for SETDB1 knockdown and inhibitor experiments. Loss of SETDB1 from pancreas accelerated formation of premalignant lesions in mice with pancreata that express activated KRAS. Microarray analysis revealed up-regulated expression of genes in the apoptotic pathway and genes regulated by p53 in SETDB1-deficient pancreata. Deletion of Setdb1 from pancreas prevented formation of PDACs, concomitant with increased apoptosis and up-regulated expression of Trp53 in mice heterozygous for disruption of Trp53. In contrast, pancreata of mice with homozygous disruption of Trp53 had no increased apoptosis, and PDACs developed. Chromatin immunoprecipitation revealed that SETDB1 bound to the Trp53 promoter to regulate its expression. Expression of an inactivated form of SETDB1 in human PDAC cells with wild-type TP53 resulted in TP53-induced apoptosis. We found that the histone methyltransferase SETDB1 is required for development of PDACs, induced by activated KRAS, in mice. SETDB1 inhibits apoptosis by regulating expression of p53. SETDB1 might be a therapeutic target for PDACs that retain p53 function.

Loss of BAP1 Leads to More YAPing in Pancreatic Cancer.

Pancreatic cancer is increasing in incidence and is expected to be the second leading cause of cancer-related mortality by the year 2030. Understanding molecular pathways that contribute to pancreatic cancer initiation and progression provides the opportunity to uncover potential molecular vulnerabilities that can be exploited therapeutically. In this issue of Cancer Research, Lee and colleagues provide compelling evidence that BRCA1-associated protein (BAP1) functions as a tumor suppressor in pancreatic cancer by promoting the activity of the Hippo tumor suppressor pathway, highlighting YAP and TAZ, Hippo effectors, as attractive therapeutic targets in pancreatic ductal adenocarcinoma, especially in BAP1-deficient or low tumors.See related article by Lee et al., p. 1656.

Upregulation of ASPM, BUB1B and SPDL1 in tumor tissues predicts poor survival in patients with pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a major cause of cancer-associated mortality, with poor patient outcome. The present study aimed to identify key candidate genes and investigate the potential molecular mechanisms associated with the progression of PDAC. The GSE46234 dataset was downloaded from the Gene Expression Omnibus database, in order to identify the upregulated differentially expressed genes (DEGs) in PDAC. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to determine the biological functions and pathways of the upregulated DEGs, and a protein-protein interaction (PPI) network was subsequently constructed to screen the hub genes. Subsequently, survival analyses of the hub genes were undertaken in patients with PDAC, using The Cancer Genome Atlas dataset. Reverse transcription-quantitative (RT-q)PCR analysis was performed to assess the mRNA expression levels of the hub genes associated with the prognosis of patients with PDAC. In the present study, 65 upregulated DEGs were identified. GO analysis suggested that the DEGs were enriched in response to hypoxia, calcium ion and negative regulation of catecholamine. KEGG analysis demonstrated that the DEGs were enriched in gastric acid secretion, the ECM-receptor interaction and the cGMP-PKG signaling pathway. Among the 18 hub genes determined by module screening of the PPI network, upregulation of three key genes, abnormal spindle-like microcephaly-associated protein (ASPM), mitotic checkpoint serine/threonine-protein kinase BUB1 β (BUB1B) and protein spindly (SPDL1), was significantly associated with worse overall survival and disease-free survival time in patients with PDAC. Furthermore, ASPM, BUB1B and SPDL1 were demonstrated to be associated with advanced tumor stage, and their upregulation in PDAC tumor tissues was validated using RT-qPCR analysis. Taken together, the results of the present study demonstrate that ASPM, BUB1B and SPDL1 may have the potential to function as prognostic markers and therapeutic targets for PDAC.

MiR-29a Is Repressed by MYC in Pancreatic Cancer and Its Restoration Drives Tumor-Suppressive Effects via Downregulation of LOXL2.

Pancreatic ductal adenocarcinoma (PDAC) is an intractable cancer with a dismal prognosis. miR-29a is commonly downregulated in PDAC; however, mechanisms for its loss and role still remain unclear. Here, we show that in PDAC, repression of miR-29a is directly mediated by MYC via promoter activity. RNA sequencing analysis, integrated with miRNA target prediction, identified global miR-29a downstream targets in PDAC. Target enrichment coupled with gene ontology and survival correlation analyses identified the top five miR-29a-downregulated target genes (LOXL2, MYBL2, CLDN1, HGK, and NRAS) that are known to promote tumorigenic mechanisms. Functional validation confirmed that upregulation of miR-29a is sufficient to ablate translational expression of these five genes in PDAC. We show that the most promising target among the identified genes, LOXL2, is repressed by miR-29a via 3'-untranslated region binding. Pancreatic tissues from a PDAC murine model and patient biopsies showed overall high LOXL2 expression with inverse correlations with miR-29a levels. Collectively, our data delineate an antitumorigenic, regulatory role of miR-29a and a novel MYC-miR-29a-LOXL2 regulatory axis in PDAC pathogenesis, indicating the potential of the molecule in therapeutic opportunities. IMPLICATIONS: This study unravels a novel functional role of miR-29a in PDAC pathogenesis and identifies an MYC-miR-29a-LOXL2 axis in regulation of the disease progression, implicating miR-29a as a potential therapeutic target for PDAC. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/18/2/311/F1.large.jpg.

The potential of Tenascin C in the tumor-nerve microenvironment to enhance perineural invasion and correlate with locoregional recurrence-related poor prognosis in pancreatic ductal adenocarcinoma.

748 Background: Perineural invasion (PNI) is commonly seen in pancreatic ductal adenocarcinoma (PDAC) and worsens the postoperative prognosis. However, the detail mechanisms of PNI in PDAC remain unclear. Tenascin C (TNC), an extracellular matrix glycoprotein, is abundant in cancer stroma and modulates tumor progression. In this study, we hypothesized that TNC could enhance PNI in PDAC. The aim of this study was to investigate the roles of TNC in the tumor-nerve microenvironment of PDAC. Methods: We immunohistochemically examined TNC expression in 78 resected PDAC specimens. TNC staining intensity in perineural sites at the invasive front was classified as low or high, by comparison with adjacent non-cancerous tissues in the same section. The relationships between TNC expression and clinicopathological features were retrospectively analyzed. Furthermore, interactions between cancer cells and nerves after supplementation with TNC were investigated using in vitro co-culture model with a PDAC cell line and neonatal mouse dorsal root ganglion (DRG). Results: High perineural TNC expression at the invasive front, seen in 30 (38%) patients, was associated with the presence of PNI (p = 0.006), pathological T stage ≥ 3 (p = 0.01), and postoperative locoregional recurrence (p = 0.002). It was independently associated with postoperative, poor recurrence-free survival in multivariate analysis (p = 0.045). In the in vitro co-culture model, TNC supplementation significantly enhanced both neurotropism of PDAC cells and tumor tropism of a DRG. On the other hand, when PDAC cells and a DRG were cultured separately, TNC did not affect cancer cell proliferation or neural outgrowth. Furthermore, the knockdown of Annexin A2, which is known to be a receptor for TNC, cancelled the neurotropism of PDAC cell toward DRGs. Conclusions: Strong perineural TNC expression was a prognostic indicator of locoregional recurrence-related poor prognosis. The neurotropism of PDAC induced by TNC and TNC-Annexin A2 signaling pathway could be the potential therapeutic target for PDAC by regulating PNI.

MiR-24-3p Inhibits the Progression of Pancreatic Ductal Adenocarcinoma Through LAMB3 Downregulation.

Pancreatic ductal adenocarcinoma (PDAC) is associated with several genetic syndromes. However, the molecular mechanism underlying PDAC progression is still unknown. In this study, we showed that Laminin Subunit Beta 3 (LAMB3) was aberrantly overexpressed in PDAC and was closely associated with the overall survival rate of patients with PDAC. Functional studies demonstrated that LAMB3 played important roles in cell proliferation, the cell cycle, and invasion capacity. Using bioinformatics analysis, we determined that miR-24-3p was an upstream miRNA of LAMB3, and further experiments verified that miR-24-3p regulated LAMB3 expression in PDAC cells. A dual-luciferase reporter system demonstrated that miR-24-3p directly targeted the LAMB3 3'UTR, and FISH assay confirmed that miR-24-3p and LAMB3 mRNA mostly resided in cytoplasm, accounting for their post-translational regulation. Rescue assay demonstrated that miR-24-3p exerted its anti-cancer role by suppressing LAMB3 expression. Finally, by using a subcutaneous xenotransplanted tumor model, we demonstrated that miR-24-3p overexpression inhibited the proliferation of PDAC by suppressing LAMB3 expression in vivo. Collectively, our results provide evidence that the miR-24-3p/LAMB3 axis plays a vital role in the progression of PDAC and indicate that the miR-24-3p/LAMB3 axis may represent a novel therapeutic target for PDAC.