Chimeric antibody targeting unique epitope on onco-mucin16 reduces tumor burden in pancreatic and lung malignancies.

Aberrantly expressed onco-mucin 16 (MUC16) and its post-cleavage generated surface tethered carboxy-terminal (MUC16-Cter) domain are strongly associated with poor prognosis and lethality of pancreatic (PC) and non-small cell lung cancer (NSCLC). To date, most anti-MUC16 antibodies are directed towards the extracellular domain of MUC16 (CA125), which is usually cleaved and shed in the circulation hence obscuring antibody accessibility to the cancer cells. Herein, we establish the utility of targeting a post-cleavage generated, surface-tethered oncogenic MUC16 carboxy-terminal (MUC16-Cter) domain by using a novel chimeric antibody in human IgG1 format, ch5E6, whose epitope expression directly correlates with disease severity in both cancers. ch5E6 binds and interferes with MUC16-associated oncogenesis, suppresses the downstream signaling pFAK(Y397)/p-p70S6K(T389)/N-cadherin axis and exert antiproliferative effects in cancer cells, 3D organoids, and tumor xenografts of both PC and NSCLC. The robust clinical correlations observed between MUC16 and N-cadherin in patient tumors and metastatic samples imply ch5E6 potential in targeting a complex and significantly occurring phenomenon of epithelial to mesenchymal transition (EMT) associated with disease aggressiveness. Our study supports evaluating ch5E6 with standard-of-care drugs, to potentially augment treatment outcomes in malignancies inflicted with MUC16-associated poor prognosis.

Muc4 loss mitigates epidermal growth factor receptor activity essential for PDAC tumorigenesis.

Mucin4 (MUC4) appears early during pancreatic intraepithelial neoplasia-1 (PanIN1), coinciding with the expression of epidermal growth factor receptor-1 (EGFR). The EGFR signaling is required for the onset of Kras-driven pancreatic ductal adenocarcinoma (PDAC); however, the players and mechanisms involved in sustained EGFR signaling in early PanIN lesions remain elusive. We generated a unique Esai-CRISPR-based Muc4 conditional knockout murine model to evaluate its effect on PDAC pathology. The Muc4 depletion in the autochthonous murine model carrying K-ras and p53 mutations (K-rasG12D; TP53R172H; Pdx-1cre, KPC) to generate the KPCM4-/- murine model showed a significant delay in the PanIN lesion formation with a significant reduction (p < 0.01) in EGFR (Y1068) and ERK1/2 (T202/Y204) phosphorylation. Further, a significant decrease (p < 0.01) in Sox9 expression in PanIN lesions of KPCM4-/- mice suggested the impairment of acinar-to-ductal metaplasia in Muc4-depleted cells. The biochemical analyses demonstrated that MUC4, through its juxtamembrane EGF-like domains, interacts with the EGFR ectodomain, and its cytoplasmic tail prevents EGFR ubiquitination and subsequent proteasomal degradation upon ligand stimulation, leading to sustained downstream oncogenic signaling. Targeting the MUC4 and EGFR interacting interface provides a promising strategy to improve the efficacy of EGFR-targeted therapies in PDAC and other MUC4-expressing malignancies.

Small molecule inhibitor against onco-mucins disrupts Src/FosL1 axis to enhance gemcitabine efficacy in pancreatic ductal adenocarcinoma.

Mucin MUC4 is an aberrantly expressed oncogene in pancreatic ductal adenocarcinoma (PDAC), yet no pharmacological inhibitors have been identified to target MUC4. Here, we adapted an in silico screening method using the Cancer Therapeutic Response Database (CTRD) to Identify Small Molecule Inhibitors against Mucins (SMIMs). We identified Bosutinib as a candidate drug to target oncogenic mucins among 126 FDA-approved drugs from CTRD screening. Functionally, Bosutinib treatment alone/and in combination with gemcitabine (Gem)/5' fluorouracil (5FU) reduced in vitro viability, migration, and colony formation in multiple PDAC cell lines as well as human PDAC organoid prolifertaion and growth and in vivo xenograft growth. Further, biochemical and molecular analyses showed that Bosutinib exhibited these functional effects by downregulating MUC4 mucin at both transcript and translation levels in a dose- and time-dependent manner. Mechanistically, global transcriptome analysis in PDAC cells upon treatment with Bosutinib revealed disruption of the Src-ERK/AKT-FosL1 pathway, leading to decreased expression of MUC4 and MUC5AC mucins. Taken together, Bosutinib is a promising, novel, and highly potent SMIMs to target MUC4/MUC5AC mucins. This mucin-targeting effect of Bosutinib can be exploited in the future with cytotoxic agents to treat mucinous tumors.

Malondialdehyde-Acetaldehyde Extracellular Matrix Protein Adducts Attenuate Unfolded Protein Response During Alcohol and Smoking-Induced Pancreatitis.

BACKGROUND & AIMS: Epidemiological studies have established alcohol and smoking as independent risk factors for recurrent acute pancreatitis and chronic pancreatitis. However, the molecular players responsible for the progressive loss of pancreatic parenchyma and fibroinflammatory response are poorly characterized. METHODS: Tandem mass tag-based proteomic and bioinformatics analyses were performed on the pancreata of mice exposed to alcohol, cigarette smoke, or a combination of alcohol and cigarette smoke. Biochemical, immunohistochemistry, and transcriptome analyses were performed on the pancreatic tissues and primary acinar cells treated with cerulein in combination with ethanol (50 mmol/L) and cigarette smoke extract (40 µg/mL) for the mechanistic studies. RESULTS: A unique alteration in the pancreatic proteome was observed in mice exposed chronically to the combination of alcohol and cigarette smoke (56.5%) compared with cigarette smoke (21%) or alcohol (17%) alone. The formation of toxic metabolites (P < .001) and attenuated unfolded protein response (P < .04) were the significantly altered pathways on combined exposure. The extracellular matrix (ECM) proteins showed stable malondialdehyde-acetaldehyde (MAA) adducts in the pancreata of the combination group and chronic pancreatitis patients with a history of smoking and alcohol consumption. Interestingly, MAA-ECM adducts significantly suppressed expression of X-box-binding protein-1, leading to acinar cell death in the presence of alcohol and smoking. The stable MAA-ECM adducts persist even after alcohol and smoking cessation, and significantly delay pancreatic regeneration by abrogating the expression of cyclin-dependent kinases (CDK7 and CDK5) and regeneration markers. CONCLUSIONS: The combined alcohol and smoking generate stable MAA-ECM adducts that increase endoplasmic reticulum stress and acinar cell death due to attenuated unfolded protein response and suppress expression of cell cycle regulators. Targeting aldehyde adducts might provide a novel therapeutic strategy for the management of recurrent acute pancreatitis and chronic pancreatitis.

Cytokines chattering in pancreatic ductal adenocarcinoma tumor microenvironment.

Pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME) consists of multiple cell types interspersed by dense fibrous stroma. These cells communicate through low molecular weight signaling molecules called cytokines. The cytokines, through their receptors, facilitate PDAC initiation, progression, metastasis, and distant colonization of malignant cells. These signaling mediators secreted from tumor-associated macrophages, and cancer-associated fibroblasts in conjunction with oncogenic Kras mutation initiate acinar to ductal metaplasia (ADM), resulting in the appearance of early preneoplastic lesions. Further, M1- and M2-polarized macrophages provide proinflammatory conditions and promote deposition of extracellular matrix, whereas myofibroblasts and T-lymphocytes, such as Th17 and T-regulatory cells, create a fibroinflammatory and immunosuppressive environment with a significantly reduced cytotoxic T-cell population. During PDAC progression, cytokines regulate the expression of various oncogenic regulators such as NFκB, c-myc, growth factor receptors, and mucins resulting in the formation of high-grade PanIN lesions, epithelial to mesenchymal transition, invasion, and extravasation of malignant cells, and metastasis. During metastasis, PDAC cells colonize at the premetastatic niche created in the liver, and lung, an organotropic function primarily executed by cytokines in circulation or loaded in the exosomes from the primary tumor cells. The indispensable contribution of these cytokines at every stage of PDAC tumorigenesis makes them exciting candidates in combination with immune-, chemo- and targeted radiation therapy.

Mucin 5AC Serves as the Nexus for ß-Catenin/c-Myc Interplay to Promote Glutamine Dependency During Pancreatic Cancer Chemoresistance.

BACKGROUND & AIMS: A major clinical challenge for patients with pancreatic cancer (PC) is metabolic adaptation. Neoplastic cells harboring molecular perturbations suffice for their increased anabolic demand and nucleotide biosynthesis to acquire chemoresistance. The mucin 5AC expressed de novo in malignant pancreas promotes cancer cell stemness and is significantly associated with poor patient survival. Identification of MUC5AC-associated drivers of chemoresistance through metabolic alterations may facilitate the sculpting of a new combinatorial regimen. METHODS: The contributions of MUC5AC to glutaminolysis and gemcitabine resistance were examined by The Cancer Genome Atlas data analysis, RNA sequencing, and immunohistochemistry analysis on pancreatic tissues of KrasG12D;Pdx1-Cre (KC) and KrasG12D;Pdx1-Cre;Muc5ac-/- mice. These were followed by metabolite flux assays as well as biochemical and xenograft studies on MUC5AC-depleted human and murine PC cells. Murine and human pancreatic 3-dimensional tumoroids were used to evaluate the efficacy of gemcitabine in combination with ß-catenin and glutaminolysis inhibitors. RESULTS: Transcriptional analysis showed that high MUC5AC-expressing human and autochthonous murine PC tumors exhibit higher resistance to gemcitabine because of enhanced glutamine use and nucleotide biosynthesis. Gemcitabine treatment led to MUC5AC overexpression, resulting in disruption of E-cadherin/ß-catenin junctions and the nuclear translocation of ß-catenin, which increased c-Myc expression, with a concomitant rise in glutamine uptake and glutamate release. MUC5AC depletion and glutamine deprivation sensitized human PC cells to gemcitabine, which was obviated by glutamine replenishment in MUC5AC-expressing cells. Coadministration of ß-catenin and glutaminolysis inhibitors with gemcitabine abrogated the MUC5AC-mediated resistance in murine and human tumoroids. CONCLUSIONS: The MUC5AC/ß-catenin/c-Myc axis increases the uptake and use of glutamine in PC cells, and cotargeting this axis along with gemcitabine may improve therapeutic efficacy in PC.

Correction: Kaushal et al. Repurposing Niclosamide for Targeting Pancreatic Cancer by Inhibiting Hh/Gli Non-Canonical Axis of Gsk3ß. Cancers 2021, 13, 3105.

The authors would like to make a correction to their published paper [...].

Mucin Expression and Splicing Determine Novel Subtypes and Patient Mortality in Pancreatic Ductal Adenocarcinoma.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy demonstrating aberrant and progressive expression of mucins. The contribution of individual mucins has been extensively investigated in PDAC; however, comprehensive mucin profiling including splice variants in PDAC tumors has not been reported. EXPERIMENTAL DESIGN: Using publicly available RNA sequencing (RNA-seq) datasets, we assess the expression of mucin family members and their splice variants (SV) in PDAC tumor samples for the first time. Mucin SVs that are correlated with PDAC patient survival are validated in a cohort of patient tumor samples. Further, we use computational methods to derive novel pancreatic tumor subtypes using mucin expression signatures and their associated activated pathways. RESULTS: Principal component analysis identified four novel mucin-based PDAC subtypes. Pathway analysis implicated specific biological signatures for each subtype, labeled (i) immune activated, (ii) progressive, (iii) pancreatitis-initiated, and (iv) anti-inflammatory/PanIN-initiated. Assessing mucin SVs, significantly longer survival is observed with higher expression of 4 MUC1 and 1 MUC13 SVs, whereas patients expressing 2 MUC4 and 1 MUC16 SVs had shorter survival. Using a whole-transcriptome correlation, a three-gene panel, including ESRP2, PTK6, and MAGEH1, is designated to assess PDAC tumor sample cellularity by PCR. One MUC4 SV and one MUC13 SV are quantified in a separate PDAC patient cohort, and their effects on survival are experimentally validated. CONCLUSIONS: Altogether, we demonstrate the unique expression pattern of mucins, four mucin-based PDAC subtypes, and the contribution of MUC1, MUC4, and MUC16 SVs in PDAC patient survival.

SUMO Modification of PAF1/PD2 Enables PML Interaction and Promotes Radiation Resistance in Pancreatic Ductal Adenocarcinoma.

RNA polymerase II-associated factor 1 (PAF1)/pancreatic differentiation 2 (PD2) is a core subunit of the human PAF1 complex (PAF1C) that regulates the RNA polymerase II function during transcriptional elongation. PAF1/PD2 has also been linked to the oncogenesis of pancreatic ductal adenocarcinoma (PDAC). Here, we report that PAF1/PD2 undergoes posttranslational modification (PTM) through SUMOylation, enhancing the radiation resistance of PDAC cells. We identified that PAF1/PD2 is preferentially modified by small ubiquitin-related modifier 1 (SUMO 1), and mutating the residues (K)-150 and 154 by site-directed mutagenesis reduces the SUMOylation. Interestingly, PAF1/PD2 was found to directly interact with the promyelocytic leukemia (PML) protein in response to radiation, and inhibition of PAF1/PD2 SUMOylation at K-150/154 affects its interaction with PML. Our results demonstrate that SUMOylation of PAF1/PD2 increased in the radiated pancreatic cancer cells. Furthermore, inhibition of SUMOylation or PML reduces the cell growth and proliferation of PDAC cells after radiation treatment. These results suggest that SUMOylation of PAF1/PD2 interacts with PTM for PDAC cell survival. Furthermore, abolishing the SUMOylation in PDAC cells enhances the effectiveness of radiotherapy. Overall, our results demonstrate a novel PTM and PAF1/PD2 interaction through SUMOylation, and inhibiting the SUMOylation of PAF1/PD2 enhance the therapeutic efficacy for PDAC.

Contribution of CXCR3-mediated signaling in the metastatic cascade of solid malignancies.

Metastasis is a significant cause of the mortality resulting from solid malignancies. The process of metastasis is complex and is regulated by numerous cancer cell-intrinsic and -extrinsic factors. CXCR3 is a chemokine receptor that is frequently expressed by cancer cells, endothelial cells and immune cells. CXCR3A signaling in cancer cells tends to promote the invasive and migratory phenotype of cancer cells. Indirectly, CXCR3 modulates the anti-tumor immune response resulting in variable effects that can permit or inhibit metastatic progression. Finally, the activity of CXCR3B in endothelial cells is generally angiostatic, which limits the access of cancer cells to key conduits to secondary sites. However, the interaction of these activities within a tumor and the presence of opposing CXCR3 splice variants clouds the picture of the role of CXCR3 in metastasis. Consequently, thorough analysis of the contributions of CXCR3 to cancer metastasis is necessary. This review is an in-depth examination of the involvement of CXCR3 in the metastatic process of solid malignancies.

Repurposing Niclosamide for Targeting Pancreatic Cancer by Inhibiting Hh/Gli Non-Canonical Axis of Gsk3ß.

Niclosamide (Nic), an FDA-approved anthelmintic drug, is reported to have anti-cancer efficacy and is being assessed in clinical trials for various solid tumors. Based on its ability to target multiple signaling pathways, in the present study, we evaluated the therapeutic efficacy of Nic on pancreatic cancer (PC) in vitro. We observed an anti-cancerous effect of this drug as shown by the G0/G1 phase cell cycle arrest, inhibition of PC cell viability, colony formation, and migration. Our results revealed the involvement of mitochondrial stress and mTORC1-dependent autophagy as the predominant players of Nic-induced PC cell death. Significant reduction of Nic-induced reactive oxygen species (ROS) and cell death in the presence of a selective autophagy inhibitor spautin-1 demonstrated autophagy as a major contributor to Nic-mediated cell death. Mechanistically, Nic inhibited the interaction between BCL2 and Beclin-1 that supported the crosstalk of autophagy and apoptosis. Further, Nic treatment resulted in Gsk3ß inactivation by phosphorylating its Ser-9 residue leading to upregulation of Sufu and Gli3, thereby negatively impacting hedgehog signaling and cell survival. Nic induced autophagic cell death, and p-Gsk3b mediated Sufu/Gli3 cascade was further confirmed by Gsk3ß activator, LY-294002, by rescuing inactivation of Hh signaling upon Nic treatment. These results suggested the involvement of a non-canonical mechanism of Hh signaling, where p-Gsk3ß acts as a negative regulator of Hh/Gli1 cascade and a positive regulator of autophagy-mediated cell death. Overall, this study established the therapeutic efficacy of Nic for PC by targeting p-Gsk3ß mediated non-canonical Hh signaling and promoting mTORC1-dependent autophagy and cell death.

Molecular mechanisms of pancreatic myofibroblast activation in chronic pancreatitis and pancreatic ductal adenocarcinoma.

Pancreatic fibrosis (PF) is an essential component of the pathobiology of chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC). Activated pancreatic myofibroblasts (PMFs) are crucial for the deposition of the extracellular matrix, and fibrotic reaction in response to sustained signaling. Consequently, understanding of the molecular mechanisms of PMF activation is not only critical for understanding CP and PDAC biology but is also a fertile area of research for the development of novel therapeutic strategies for pancreatic pathologies. This review analyzes the key signaling events that drive PMF activation including, initiating signals from transforming growth factor-ß1, platelet derived growth factor, as well as other microenvironmental cues, like hypoxia and extracellular matrix rigidity. Further, we discussed the intracellular signal events contributing to PMF activation, and crosstalk with different components of tumor microenvironment. Additionally, association of epidemiologically established risk factors for CP and PDAC, like alcohol intake, tobacco exposure, and metabolic factors with PMF activation, is discussed to comprehend the role of lifestyle factors on pancreatic pathologies. Overall, this analysis provides insight into the biology of PMF activation and highlights salient features of this process, which offer promising therapeutic targets.

Neutrophil Gelatinase-Associated Lipocalin Protects Acinar Cells From Cerulein-Induced Damage During Acute Pancreatitis.

OBJECTIVES: Elevated neutrophil gelatinase-associated lipocalin (NGAL) is a promising marker for severe acute pancreatitis (SAP) and multiple organ failure, suggesting systemic and local contributions during pancreatitis. We investigated the role of NGAL locally on acinar cell biology. METHODS: Western blot, reverse transcriptase-polymerase chain reaction, and immunohistochemistry analysis were performed to analyze the levels of NGAL receptors, apoptotic and regeneration markers, and 4-hydroxynonenal (4HNE) levels, 3-[4,5-Dimethylthiazole-2-yl]-2, 5-diphenyltetrazolium bromide assay, and annexin V/propidium iodide staining were used to evaluate cell viability, and effect on endothelial cells was accessed by endothelial permeability assay. RESULTS: Cerulein treatment at 20 µM for 12 hours significantly reduced acinar cell viability by 40%, which was rescued by NGAL at 800 and 1600 ng/mL concentrations, observed during mild and SAP, respectively. Mechanistically, NGAL significantly reduced the levels of reactive oxygen species and 4HNE adduct formation in a 24p3R-dependent manner and upregulated the expression of acinar cell regeneration markers, like CDK-2, CDK-4, and C-myc. However, SAP levels of NGAL significantly increased endothelial permeability and downregulated the levels of ZO-1, and cerulein treatment in NGAL knockout mice showed increased levels of 4HNE adducts. CONCLUSIONS: Neutrophil gelatinase-associated lipocalin rescues intracellular reactive oxygen species during pancreatitis and promotes survival and regeneration of acinar cells.

CXCR3 and Cognate Ligands are Associated with Immune Cell Alteration and Aggressiveness of Pancreatic Ductal Adenocarcinoma.

PURPOSE: The cytokine milieu in pancreatic ductal adenocarcinoma (PDAC) promotes tumor progression and immune suppression, contributing to the dismal prognosis of patients with PDAC. The roles of many of these cytokines, however, have not been thoroughly investigated in PDAC. EXPERIMENTAL DESIGN: PDAC microarray and The Cancer Genome Atlas datasets were analyzed to identify cytokines and cognate receptors overexpressed in PDAC and associated with survival. Pathway and CIBERSORT analyses were used to elucidate potential mechanisms of altered patient survival. Comparative analysis of cytokine expression in KPC (K-rasG12D; TP53R172H; Pdx-1cre) and KC (K-rasG12D; Pdx-1cre) PDAC models and multicolor immunofluorescence (IF) staining of human PDAC-resected samples were used to validate these findings. RESULTS: CXCL9 and CXCL10 were among the most highly overexpressed cytokines by bioinformatics analyses, while their receptor, CXCR3, was significantly overexpressed by IHC analysis. Higher CXCR3 ligand expression was associated with shorter overall survival, while high CXCR3 expression was associated with better survival. The CXCR3 ligands, CXCL4, 9, and 10, were overexpressed in KPC compared with KC mice. Pathway analysis of CXCR3- and CXCR3 ligand-associated genes showed that CXCR3 is a marker of antitumor immunity, while its ligands may promote immunosuppression. CIBERSORT and IF studies of PDAC tissues demonstrated that high CXCR3 expression was associated with increased CD8+ T-cell and naïve B-cell signatures and loss of plasma cell signatures. CXCR3 ligand expression was associated with increased CD8+ T-cell signatures and loss of natural killer-cell signatures. CONCLUSIONS: CXCR3 ligands are overexpressed in PDAC and are associated with poor survival likely related to alterations in tumor immune infiltrate/activity.

Alcohol and Smoking Mediated Modulations in Adaptive Immunity in Pancreatitis.

Pancreatitis is a condition of pancreatic inflammation driven by injury to the pancreatic parenchyma. The extent of acinar insult, intensity, and type of immune response determines the severity of the disease. Smoking, alcohol and autoimmune pancreatitis are some of the predominant risk factors that increase the risk of pancreatitis by differentially influencing the adaptive immune system. The overall decrease in peripheral lymphocyte (T-, B- and (natural killer T-) NKT-cell) count and increased infiltration into the damaged pancreatic tissue highlight the contribution of adaptive immunity in the disease pathology. Smoking and alcohol modulate the responsiveness and apoptosis of T- and B-cells during pancreatic insult. Acute pancreatitis worsens with smoking and alcohol, leading to the development of systemic inflammatory response syndrome and compensatory anti-inflammatory response syndrome, suggesting the critical role of adaptive immunity in fatal outcomes such as multiple organ dysfunction. The presence of CD4+ and CD8+ T-lymphocytes and perforin-expressing cells in the fibrotic tissue in chronic pancreatitis modulate the severity of the disease. Due to their important role in altering the severity of the disease, attempts to target adaptive immune mediators will be critical for the development of novel therapeutic interventions.

Role of non-Genetic Risk Factors in Exacerbating Alcohol-related organ damage.

This review provides a summary of the symposium titled "Role of Non-Genetic Risk Factors in Exacerbating Alcohol-Related Organ Damage", which was held at the 42nd Annual Meeting of the Research Society on Alcoholism. The goals of the symposium were to provide newer insights into the role of non-genetic factors, including specific external factors, notably infectious agents or lifestyle factors, that synergistically act to exacerbate alcohol pathogenicity to generate more dramatic downstream biological defects. This summary of the symposium will benefit junior/senior basic scientists and clinicians currently investigating/treating alcohol-induced organ pathology, as well as undergraduate, graduate, and post-graduate students and fellows.

Utilizing cell line-derived organoids to evaluate the efficacy of a novel LIFR-inhibitor, EC359 in targeting pancreatic tumor stroma.

Survival of pancreatic cancer (PC) patient is poor due to lack of effective treatment modalities, which is partly due to the presence of dense desmoplasia that impedes the delivery of chemotherapeutics. Therefore, PC stroma-targeting therapies are expected to improve the efficacy of chemotherapeutics. However, in vitro evaluation of stromal-targeted therapies requires a culture system which includes components of both tumor stroma and parenchyma. We aim to generate a cell line-derived 3D organoids to test the efficacy of stromal-targeted, LIFR-inhibitor EC359. Murine PC (FC1245) and stellate (ImPaSC) cells were cultured to generate organoids that recapitulated the histological organization of PC with the formation of ducts by epithelial cells surrounded by activated fibroblasts, as indicated by CK19 and α-SMA staining, respectively. Analysis by qRT-PCR demonstrated a significant downregulation of markers of activated stroma, POSTN, FN1, MMP9, and SPARC (p<0.0001), when treated with gemcitabine in combination with EC359. Concurrently, collagen proteins including COL1A1, COL1A2, COL3A1, and COL5A1 were significantly downregulated (p <0.0001) after treatment with gemcitabine in combination with EC359. Overall, our study demonstrates the utility of cell lines-derived 3D organoids to evaluate the efficacy of stroma-targeted therapies as well as the potential of EC359 to target activated stroma in PC.

Cancer-associated mucins: role in immune modulation and metastasis.

Mucins (MUC) protect epithelial barriers from environmental insult to maintain homeostasis. However, their aberrant overexpression and glycosylation in various malignancies facilitate oncogenic events from inception to metastasis. Mucin-associated sialyl-Tn (sTn) antigens bind to various receptors present on the dendritic cells (DCs), macrophages, and natural killer (NK) cells, resulting in overall immunosuppression by either receptor masking or inhibition of cytolytic activity. MUC1-mediated interaction of tumor cells with innate immune cells hampers cross-presentation of processed antigens on MHC class I molecules. MUC1 and MUC16 bind siglecs and mask Toll-like receptors (TLRs), respectively, on DCs promoting an immature DC phenotype that in turn reduces T cell effector functions. Mucins, such as MUC1, MUC2, MUC4, and MUC16, interact with or form aggregates with neutrophils, macrophages, and platelets, conferring protection to cancer cells during hematological dissemination and facilitate their spread and colonization to the metastatic sites. On the contrary, poor glycosylation of MUC1 and MUC4 at the tandem repeat region (TR) generates cancer-specific immunodominant epitopes. The presence of MUC16 neo-antigen-specific T cell clones and anti-MUC1 antibodies in cancer patients suggests that mucins can serve as potential targets for developing cancer therapeutics. The present review summarizes the molecular events involved in mucin-mediated immunomodulation, and metastasis, as well as the utility of mucins as targets for cancer immunotherapy and radioimmunotherapy.

Emerging trends in the immunotherapy of pancreatic cancer.

Pancreatic cancer (PC) is the fourth leading cause of cancer-related deaths in the U.S., claiming approximately 43,000 lives every year. Much like other solid tumors, PC evades the host immune surveillance by manipulating immune cells to establish an immunosuppressive tumor microenvironment (TME). Therefore, targeting and reinstating the patient's immune system could serve as a powerful therapeutic tool. Indeed, immunotherapy has emerged in recent years as a potential adjunct treatment for solid tumors including PC. Immunotherapy modulates the host's immune response to tumor-associated antigens (TAAs), eradicates cancer cells by reducing host tolerance to TAAs and provides both short- and long-term protection against the disease. Passive immunotherapies like monoclonal antibodies or engineered T-cell based therapies directly target tumor cells by recognizing TAAs. Active immunotherapies, like cancer vaccines, on the other hand elicit a long-lasting immune response via activation of the patient's immune cells against cancer cells. Several immunotherapy strategies have been tested for anti-tumor responses alone and in combination with standard care in multiple preclinical and clinical studies. In this review, we discuss various immunotherapy strategies used currently and their efficacy in abrogating self-antigen tolerance and immunosuppression, as well as their ability to eradicate PC.