Identification of novel vascular projections with cellular trafficking abilities on the microvasculature of pancreatic ductal adenocarcinoma

HIF-1α expression is associated with the pathological response to neoadjuvant chemotherapy in pancreatic ductal adenocarcinoma patients and can be predicted using CECT features

Background

Hypoxia-inducible factor-1-alpha (HIF-1α) has the potential to predict the neoadjuvant chemotherapy (NAC) response in pancreatic ductal adenocarcinoma (PDAC). This study aimed to assess the relationship between the pathological response and intratumoral HIF-1α expression in patients with PDAC receiving NAC, and investigate the predictive value of contrast-enhanced computed tomography (CECT) features in HIF-1α expression.

Methods

A total of 58 patients from three centers with pathologically confirmed PDAC who underwent NAC followed by surgery were retrospectively enrolled in this study. Immunohistochemistry was performed to detect intratumoral HIF-1α expression. The Chi-square test was used to evaluate the differences in intratumoral HIF-1α expression in PDAC responders and non-responders after NAC. Binary logistic regression and receiver operating characteristic (ROC) curves were used to determine the optimal correlation factors of different pathological responses in PDAC patients after NAC and to predict these factors using CECT features.

Results

Among the PDAC patients, 27 (46.55%) responders and 31 (53.45%) non-responders were identified via histopathological examination. Nuclear and cytoplasmic HIF-1α expression was significantly higher in the responders than the non-responders (P<0.001, P=0.036). However, HIF-1α expression in the stroma was not statistically significant (P=0.864). The multivariate logistic regression revealed that the %Δ carbohydrate antigen 19-9 (CA19-9), tumor differentiation, and nuclear HIF-1α were independent predictors of different pathological responses [odds ratio (OR) =9.005, P=0.037; OR =0.005, P=0.044; OR =0.352, P=0.018, respectively]. The ROC curve showed that nuclear HIF-1α expression was the optimal associated predictor of the pathologic response (area under the curve =0.873, 95% confidence interval: 0.782-0.964). The multivariate logistic regression also showed that of the CECT characteristics, the (post-NAC - pre-NAC) arterial phase (AP) was an independent predictive indicator of nuclear HIF-1α expression (OR =1.012, P=0.020).

Conclusions

Nuclear HIF-1α was the best predictor of the pathological response in patients with PDAC after NAC, and it can be predicted using CT feature of the (post-NAC - pre-NAC) AP.

Clinical Evaluation of the Pancreatic Cancer Microenvironment: Opportunities and Challenges

Advances in our understanding of pancreatic ductal adenocarcinoma (PDAC) and its tumor microenvironment (TME) have the potential to transform treatment for the hundreds of thousands of patients who are diagnosed each year. Whereas the clinical assessment of cancer cell genetics has grown increasingly sophisticated and personalized, current protocols to evaluate the TME have lagged, despite evidence that the TME can be heterogeneous within and between patients. Here, we outline current protocols for PDAC diagnosis and management, review novel biomarkers, and highlight potential opportunities and challenges when evaluating the PDAC TME as we prepare to translate emerging TME-directed therapies to the clinic.

Pancreatic cancer tumor microenvironment is a major therapeutic barrier and target

Pancreatic Ductal Adenocarcinoma (PDAC) is projected to become the 2nd leading cause of cancer-related deaths in the United States. Limitations in early detection and treatment barriers contribute to the lack of substantial success in the treatment of this challenging-to-treat malignancy. Desmoplasia is the hallmark of PDAC microenvironment that creates a physical and immunologic barrier. Stromal support cells and immunomodulatory cells face aberrant signaling by pancreatic cancer cells that shifts the complex balance of proper repair mechanisms into a state of dysregulation. The product of this dysregulation is the desmoplastic environment that encases the malignant cells leading to a dense, hypoxic environment that promotes further tumorigenesis, provides innate systemic resistance, and suppresses anti-tumor immune invasion. This desmoplastic environment combined with the immunoregulatory events that allow it to persist serve as the primary focus of this review. The physical barrier and immune counterbalance in the tumor microenvironment (TME) make PDAC an immunologically cold tumor. To convert PDAC into an immunologically hot tumor, tumor microenvironment could be considered alongside the tumor cells. We discuss the complex network of microenvironment molecular and cellular composition and explore how they can be targeted to overcome immuno-therapeutic challenges.

Therapeutic advances targeting tumor angiogenesis in pancreatic cancer: Current dilemmas and future directions

Pancreatic cancer (PC) is one of the most lethal malignancies, which is generally resistant to various treatments. Tumor angiogenesis is deemed to be a pivotal rate-determining step for tumor growth and metastasis. Therefore, anti-angiogenetic therapy is a rational strategy to treat various cancers. However, numerous clinical trials on anti-angiogenetic therapies for PC are overwhelmingly disappointing. The unique characteristics of tumor blood vessels in PC, which are desperately lacking and highly compressed by the dense desmoplastic stroma, are reconsidered to explore some optimized strategies. In this review, we mainly focus on its specific characteristics of tumor blood vessels, discuss the current dilemmas of anti-angiogenic therapy in PC and their underlying mechanisms. Furthermore, we point out the future directions, including remodeling the abnormal vasculature or even reshaping the whole tumor microenvironment in which they are embedded to improve tumor microcirculation, and then create therapeutic vulnerabilities to the current available therapeutic strategies.

Combination, Modulation and Interplay of Modern Radiotherapy with the Tumor Microenvironment and Targeted Therapies in Pancreatic Cancer: Which Candidates to Boost Radiotherapy?

Pancreatic ductal adenocarcinoma cancer (PDAC) is a highly diverse disease with low tumor immunogenicity. PDAC is also one of the deadliest solid tumor and will remain a common cause of cancer death in the future. Treatment options are limited, and tumors frequently develop resistance to current treatment modalities. Since PDAC patients do not respond well to immune checkpoint inhibitors (ICIs), novel methods for overcoming resistance are being explored. Compared to other solid tumors, the PDAC's tumor microenvironment (TME) is unique and complex and prevents systemic agents from effectively penetrating and killing tumor cells. Radiotherapy (RT) has the potential to modulate the TME (e.g., by exposing tumor-specific antigens, recruiting, and infiltrating immune cells) and, therefore, enhance the effectiveness of targeted systemic therapies. Interestingly, combining ICI with RT and/or chemotherapy has yielded promising preclinical results which were not successful when translated into clinical trials. In this context, current standards of care need to be challenged and transformed with modern treatment techniques and novel therapeutic combinations. One way to reconcile these findings is to abandon the concept that the TME is a well-compartmented population with spatial, temporal, physical, and chemical elements acting independently. This review will focus on the most interesting advancements of RT and describe the main components of the TME and their known modulation after RT in PDAC. Furthermore, we will provide a summary of current clinical data for combinations of RT/targeted therapy (tRT) and give an overview of the most promising future directions.

Construction of a pancreatic cancer nerve invasion system using brain and pancreatic cancer organoids

Pancreatic cancer (PC) is a fatal malignancy in the human abdominal cavity that prefers to invade the surrounding nerve/nerve plexus and even the spine, causing devastating and unbearable pain. The limitation of available in vitro models restricts revealing the molecular mechanism of pain and screening pain-relieving strategies to improve the quality of life of end-stage PC patients. Here, we report a PC nerve invasion model that merged human brain organoids (hBrO) with mouse PC organoids (mPCO). After merging hBrOs with mPCOs, we monitored the structural crosstalk, growth patterns, and mutual interaction dynamics of hBrO with mPCOs for 7 days. After 7 days, we also analyzed the pathophysiological statuses, including proliferation, apoptosis and inflammation. The results showed that mPCOs tend to approximate and intrude into the hBrOs, merge entirely into the hBrOs, and induce the retraction/shrinking of neuronal projections that protrude from the margin of the hBrOs. The approximating of mPCOs to hBrOs accelerated the proliferation of neuronal progenitor cells, intensified the apoptosis of neurons in the hBrOs, and increased the expression of inflammatory molecules in hBrOs, including NLRP3, IL-8, and IL-1β. Our system pathophysiologically replicated the nerve invasions in mouse GEMM (genetically engineered mouse model) primary and human PCs and might have the potential to be applied to reveal the molecular mechanism of nerve invasion and screen therapeutic strategies in PCs.

IDO-1 inhibitor INCB24360 elicits distant metastasis of basal extruded cancer cells in pancreatic ductal adenocarcinoma

Neoplastic cells of non-immunogenic pancreatic ductal adenocarcinoma (PDAC) express indoleamine 2,3-dioxygenase 1 (IDO-1), an immunosuppressive enzyme. The metabolites of IDO-1 in cancers provide one-carbon units that annihilate effector T cells, and recruit immunosuppressive cells. In this study we investigated how IDO-1 affected the neoplastic cell behaviors in PDACs. Using multiple markers co-labeling method in 45-µm-thick tissue sections, we showed that IDO-1 expression was uniquely increased in the neoplastic cells extruded from ducts’ apical or basal domain, but decreased in lymph metastatic cells. IDO-1+ extruding neoplastic cells displayed increased vimentin expression and decreased cytokeratin expression in PDACs, characteristics of epithelial-mesenchymal transition (EMT). However, IDO-1 expression was uncorrelated with immunosuppressive infiltrates and clinicopathological characteristics of grim outcome. We replicated basal extrusion with EMT in murine KPIC PDAC organoids by long-term IFN-γ induction; application of IDO-1 inhibitor INCB24360 or 1-MT partially reversed basal extrusion coupled EMT. Ido-1 deletion in KPIC cells deprived its tumorigenicity in immunocompetent mice, decreased cellular proliferation and macropinocytic ability, and increased immunogenicity. KPIC organoids with IFN-γ-induced basal extrusion did not accelerate distant metastasis, whereas inhibition IFN-γ-induced IDO-1 with INB24360 but not 1-MT in KPIC organoids elicited liver metastasis of subcutaneous KPIC organoid tumors, suggesting that lower IDO-1 activity accelerated distant metastasis, whereas IDO-1 was indispensable for tumorigenicity of PDAC cells and supports the survival of extruding cells.

Hypoxia-Induced miR-210 Promotes Endothelial Cell Permeability and Angiogenesis via Exosomes in Pancreatic Ductal Adenocarcinoma

BACKGROUND

Exosomes have been proven to play important diagnostic, regulatory, or communication roles in tumorigenesis, tumor progression, or metastasis; in recent studies, lots of molecules, including miRNAs, were found to be aberrantly expressed in tumor exosomes and were correlated with tumor development. However, studies about the expression, relationship, or control mechanisms of miRNAs in exosomes in pancreatic ductal adenocarcinoma (PDAC) are scarce and urgently needed. The aim of this article was to identify and investigate abnormally expressed miRNAs in PDAC exosomes in vivo and in vitro.

METHODS

Microarray studies were used to detect aberrantly expressed miRNAs in PDAC exosomes, and miR-210 expression in cells or exosomes was further analyzed by qRT-PCR. Bioinformatics analyses, dual-luciferase assays, WB, and other assays were utilized to explore the miRNA molecular mechanisms. The living cell coculture model and immunofluorescence analysis were employed to image the communication between PDAC cells and endothelial cells. Other biological experiments in the study include a real-time intravital imaging system, EdU, transwell, xenograft models, and so on.

RESULTS

miR-210 is significantly expressed in PDAC exosomes and malignant cells. High miR-210 significantly facilitated tumor angiogenesis, cell invasion, and proliferation in PDAC cells. Further mechanistic detection revealed that miR-210 negatively regulated EFNA3 expression and participated in the PI3K/AKT/VEGFA or Wnt/Β-catenin/RHOA pathways, thus promoting tumor angiogenesis and cellular permeability. PDAC cells promote endothelial angiogenesis or permeability via miR-210 transmission by tumor exosomes. Exosomal miR-210 promotes PDAC progression in vivo. Further detection of PDAC plasma exosomal miR-210 suggests that exosomal miR-210 expression was high and significantly associated with vascular invasion and TNM stage and was an independent risk factor for PDAC overall survival.

CONCLUSIONS

PDAC cell-secreted exosomes could promote angiogenesis and cellular permeability of neighboring endothelial angiogenesis or permeability via miR-210 transmission. Exosomal miR-210 may play important roles in tumor biology and may be a useful prognostic marker in PDAC.

Cell Surface Engineering Enables Surfaceome Profiling

Cell surface proteins (CSPs) are vital molecular mediators for cells and their extracellular environment. Thus, understanding which CSPs are displayed on cells, especially in different cell states, remains an important endeavor in cell biology. Here, we describe the integration of cell surface engineering with radical-mediated protein biotinylation to profile CSPs. This method relies on the prefunctionalization of cells with cholesterol lipid groups, followed by sortase-catalyzed conjugation with an APEX2 ascorbate peroxidase enzyme. In the presence of biotin-phenol and H₂O₂, APEX2 catalyzes the formation of highly reactive biotinyl radicals that covalently tag electron-rich residues within CSPs for subsequent streptavidin-based enrichment and analysis by quantitative mass spectrometry. While APEX2 is traditionally used to capture proximity-based interactomes, we envisioned using it in a "baitless" manner on cell surfaces to capture CSPs. We evaluate this strategy in light of another CSP labeling method that relies on the presence of cell surface sialic acid. Using the APEX2 strategy, we describe the CSPs found in three mammalian cell lines and compare CSPs in adherent versus three-dimensional pancreatic adenocarcinoma cells.

Application of dynamic contrast enhanced ultrasound in distinguishing focal-type autoimmune pancreatitis from pancreatic ductal adenocarcinoma

OBJECTIVE

To explore the value of dynamic contrast enhanced ultrasound (DCE-US) in preoperative differential diagnosis of focal-type autoimmune pancreatitis (AIP) and pancreatic ductal adenocarcinoma (PDAC).

PATIENTS AND METHODS

From May 2016 to March 2020, patients with biopsy and histopathologically confirmed focal-type AIP (n = 9) were retrospectively included. All patients received contrast enhanced ultrasound (CEUS) examinations one week before surgery/biopsy. Dynamic analysis was performed by VueBox® software (Bracco, Italy). Eighteen cases of resection and histopathologically proved PDAC lesions were also included as control group. B mode ultrasound (BMUS) features, CEUS enhancement patterns, time intensity curves (TICs) and CEUS quantitative parameters were obtained and compared between AIP and PDAC lesions.

RESULTS

After injection of ultrasound contrast agents, most focal-type AIP lesions displayed hyper-enhancement (2/9, 22.2%) or iso-enhancement (6/9, 66.7%) during arterial phase of CEUS, while most of PDAC lesions showed hypo-enhancement (88.9%) (P < 0.01). During late phase, most of AIP lesions showed iso-enhancement (8/9, 88.9%), while most of PDAC lesions showed hypo-enhancement (94.4%) (P < 0.001). Compared with PDAC lesions, TICs of AIP lesions showed delayed and higher enhancement. Among all CEUS perfusion parameters, ratio of PE (peak enhancement), WiAUC (wash-in area under the curve), WiR (wash-in rate), WiPI (wash-in perfusion index, WiPI = WiAUC/ rise time), WoAUC (wash-out area under the curve), WiWoAUC (wash-in and wash-out area under the curve) and WoR (wash-out rate) between pancreatic lesion and surrounding normal pancreatic tissue were significantly higher in AIP lesions than PDAC lesions (P < 0.05).

CONCLUSION

DCE-US with quantitative analysis has the potential to make preoperative differential diagnosis between focal-type AIP and PDAC non-invasively.

The Expression and Survival Significance of Glucose Transporter-1 in Pancreatic Cancer: Meta-Analysis, Bioinformatics Analysis and Retrospective Study

To explore the expression profile and prognostic relevance of GLUT-1 in pancreatic cancer, a meta-analysis, bioinformatics analysis based on Gene Expression Omnibus (GEO), Oncomine dataset and The Cancer Genome Atlas (TCGA) database, and immunohistochemistry in tumor and normal tissue from 88 pancreatic ductal adenocarcinoma (PDAC) patients were performed. GLUT-1 was significantly overexpressed in pancreatic cancer but it could not be a significant biomarker for prognosis. TNM stage and pathological grade could be biomarker of poor prognosis of patients with pancreatic cancer.

The Glycolytic Pathway as a Target for Novel Onco-Immunology Therapies in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal forms of human cancer, characterized by unrestrained progression, invasiveness and treatment resistance. To date, there are limited curative options, with surgical resection as the only effective strategy, hence the urgent need to discover novel therapies. A platform of onco-immunology targets is represented by molecules that play a role in the reprogrammed cellular metabolism as one hallmark of cancer. Due to the hypoxic tumor microenvironment (TME), PDA cells display an altered glucose metabolism-resulting in its increased uptake-and a higher glycolytic rate, which leads to lactate accumulation and them acting as fuel for cancer cells. The consequent acidification of the TME results in immunosuppression, which impairs the antitumor immunity. This review analyzes the genetic background and the emerging glycolytic enzymes that are involved in tumor progression, development and metastasis, and how this represents feasible therapeutic targets to counteract PDA. In particular, as the overexpressed or mutated glycolytic enzymes stimulate both humoral and cellular immune responses, we will discuss their possible exploitation as immunological targets in anti-PDA therapeutic strategies.

Hydrogel Models with Stiffness Gradients for Interrogating Pancreatic Cancer Cell Fate

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and has seen only modest improvements in patient survival rate over the past few decades. PDAC is highly aggressive and resistant to chemotherapy, owing to the presence of a dense and hypovascularized fibrotic tissue, which is composed of stromal cells and extracellular matrices. Increase deposition and crosslinking of matrices by stromal cells lead to a heterogeneous microenvironment that aids in PDAC development. In the past decade, various hydrogel-based, in vitro tumor models have been developed to mimic and recapitulate aspects of the tumor microenvironment in PDAC. Advances in hydrogel chemistry and engineering should provide a venue for discovering new insights regarding how matrix properties govern PDAC cell growth, migration, invasion, and drug resistance. These engineered hydrogels are ideal for understanding how variation in matrix properties contributes to the progressiveness of cancer cells, including durotaxis, the directional migration of cells in response to a stiffness gradient. This review surveys the various hydrogel-based, in vitro tumor models and the methods to generate gradient stiffness for studying migration and other cancer cell fate processes in PDAC.

Basal microvilli define the metabolic capacity and lethal phenotype of pancreatic cancer

Apical microvilli of polarized epithelial cells govern the absorption of metabolites and the transport of fluid in tissues. Previously, we reported that tall and dense basal microvilli present on the endothelial cells of pancreatic cancers, a lethal malignancy with a high metabolism and unusual hypomicrovascularity, contain nutrient trafficking vesicles and glucose; their length and density were related to the glucose uptake of pancreatic cancers in a small-scale analysis. However, the implications of basal microvilli on pancreatic cancers are unknown. Here, we evaluated the clinical implications of basal microvilli in 106 pancreatic cancers. We found that basal microvilli are a dominant change in pancreatic cancers. The presence of longer and denser basal microvilli on the microvessels in pancreatic cancer tissues positively correlated with increased glucose uptake and higher metastatic (or invasive) and proliferative potentials of neoplastic cells and vice versa. Clinically, postoperative patients with longer and denser basal microvilli were more prone to unfavorable pathological characteristics and dismal prognoses. They were even more refractory to adjuvant therapy than those with shorter and thinner basal microvilli were. Our findings show that basal microvilli define the metabolic capacity and lethal phenotype of pancreatic cancers. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Besieging the Tumoral Sites: Could It Be an Alternative Therapeutic Strategy in Ductal Pancreatic Adenocarcinoma?

Pancreatic ductal adenocarcinoma is characterized by its high morbidity, and curative drugs are still lacking. In addition to immunotherapy, other molecular targeted therapeutics, such as stroma depleting agents, have been evaluated, given the abundant desmoplastic stroma that is considered a protective shield for tumor cells. However, the unexpected poor outcome has raised the debate on whether desmoplasia promotes or restrains tumor cell spread. After reviewing these key points in this paper, an approach taking advantage of desmoplasia and immune cells to besiege the tumoral sites will be proposed. Based on the available literature, the feasibility and potential limitations of this strategy will be discussed.

The physiological characteristics of the basal microvilli microvessels in pancreatic cancers

Pancreatic cancer (PC) is a highly lethal tumor with controversial high glucose uptake and hypomicrovascularity, and the hypomicrovasculature, which is considered to have poor perfusion, blocks the delivery of drugs to tumors. The preferential existence of a novel endothelial projection with trafficking vesicles in PCs, referring to basal microvilli, was described previously. However, the perfusion and nutrients delivering status of the basal microvilli microvessels are unknown. Here, we used the perfusion of fluorescently labeled CD31 antibody, lectin, and 2‐NBDG to autochthonous PC‐bearing mice, immunostaining, probe‐based confocal laser endoscopy and three‐dimensional (3D) reconstruction to study the nutrient trafficking, and perfusion status of the basal microvilli microvasculature in PC. Our data showed that the coperfusion of lectin and CD31 is an efficient way to show the microcirculation in most healthy organs. However, coperfusion with lectin and CD31 is inefficient for showing the microcirculation in PCs compared with that in healthy organs and immunostaining. This method does not reflect the nutrient trafficking status in the microvessels, especially in basal microvilli microvessels of PCs. In basal microvilli microvessels that were poorly labeled by lectin, we observed large vesicle‐like structures with 2‐NBDG preferentially located at the base of the basal microvilli or in basal microvilli, and there were long filopodia on the luminal surface of the human PC microvasculature. Our observations suggest that the PC microvasculature, especially basal microvilli microvessels, is well perfused and might be highly efficient in the trafficking of glucose or other nutrients, indicating that macropinocytosis might participate in the nutrient trafficking.

Evaluation of the antitumor mechanism of antibody-drug conjugates against tissue factor in stroma-rich allograft models

Tissue factor (TF) is known to be overexpressed in various cancers including pancreatic cancer. The upregulation of TF expression has been observed not only in tumor cells, but also in tumor stromal cells. Because of the potential of TF as a delivery target, several studies investigated the effectiveness of Ab-drug conjugates (ADCs) against TF for cancer therapy. However, it is still unclear whether anti-TF ADC can exert toxicity against both tumor cells and tumor stromal cells. Here, we prepared ADC using a rat anti-mouse TF mAb (clone.1157) and 2 types of in vivo murine pancreatic cancer models, one s.c. and other orthotopic with an abundant tumor stroma. We also compared the feasibility of bis-alkylating conjugation (bisAlk) with that of conventional maleimide-based conjugation (MC). In the s.c. models, anti-TF ADC showed greater antitumor effects than control ADC. The results also indicated that the bisAlk linker might be more suitable than the MC linker for cancer treatments. In the orthotopic model, anti-TF ADC showed greater in vivo efficacy and more extended survival time control ADC. Treatment with anti-TF ADC (20 mg/kg, three times a week) did not affect mouse body weight changes in any in vivo experiment. Furthermore, immunofluorescence staining indicated that anti-TF ADC delivered agents not only to TF-positive tumor cells, but also to TF-positive tumor vascular endothelial cells and other tumor stromal cells. We conclude that anti-TF ADC should be a selective and potent drug for pancreatic cancer therapy.

Angiogenesis in Pancreatic Cancer: Pre-Clinical and Clinical Studies

Angiogenesis is a crucial event in tumor development and progression, occurring by different mechanisms and it is driven by pro- and anti-angiogenic molecules. Pancreatic cancer vascularization is characterized by a high microvascular density, impaired microvessel integrity and poor perfused vessels with heterogeneous distribution. In this review article, after a brief introduction on pancreatic cancer classification and on angiogenesis mechanisms involved in its progression, the pre-clinical and clinical trials conducted in pancreatic cancer treatment using anti-angiogenic inhibitors will be described. Finally, we will discuss the anti-angiogenic therapy paradox between the advantage to abolish vessel supply to block tumor growth and the disadvantage due to reduction of drug delivery at the same time. The purpose is to identify new anti-angiogenic molecules that may enhance treatment regimen.

Angiogenesis in pancreatic cancer: current research status and clinical implications

Pancreatic cancer is one of the most lethal malignancies worldwide. Although the standard of care in pancreatic cancer has improved, prognoses for patients remain poor with a 5-year survival rate of < 5%. Angiogenesis, namely, the formation of new blood vessels from pre-existing vessels, is an important event in tumor growth and hematogenous metastasis. It is a dynamic and complex process involving multiple mechanisms and is regulated by various molecules. Inhibition of angiogenesis has been an established therapeutic strategy for many solid tumors. However, clinical outcomes are far from satisfying for pancreatic cancer patients receiving anti-angiogenic therapies. In this review, we summarize the current status of angiogenesis in pancreatic cancer research and explore the reasons for the poor efficacy of anti-angiogenic therapies, aiming to identify some potential therapeutic targets that may enhance the effectiveness of anti-angiogenic treatments.

Stroma - A Double-Edged Sword in Pancreatic Cancer: A Lesson From Targeting Stroma in Pancreatic Cancer With Hedgehog Signaling Inhibitors

Pancreatic cancer is a uniformly lethal malignancy with an abundant dense desmoplastic stroma. Because of its dense stroma, conventional drugs were considered to not penetrate this physical barrier, and this caused a systemic drug resistance. Thus, abolishing this barrier with targeted agents is considered to improve the efficiency of chemotherapeutic treatment. The Hedgehog (Hh) signaling pathway is a critical regulator of pancreas development and plays diversified roles in pancreatic cancer stroma and neoplastic cells. Increasing Hh expression in neoplastic cells added desmoplastic stroma accumulation in orthotopic tumors, and Hh inhibitors that target the stroma have an ability to prolong the overall survival of Pdx-1-Cre/KrasG12D/p53R172H mice models via deleting the stromal components and increasing vascularity in pancreatic tumor. However, the failure of translation from bench to bedside indicate the complexity of the relationship between Hh signaling and desmoplastic stroma, and more insights into the complex relationships between Hh signaling pathway and stroma, even tumor cells, might help redesign Hh-targeted therapy. In this review, we discuss the possible mechanism of translation of Hh inhibitor in the clinic from pathology to molecular mechanism.

BRSK2 induced by nutrient deprivation promotes Akt activity in pancreatic cancer via downregulation of mTOR activity

Neoplastic cells in pancreatic ductual adenocarcinoma (PDAC) survive in an energy-deprived milieu, and hyper-activation of Akt is thought to contribute to the neoplastic cell survival in PDAC. Kras activating mutations, common in PDAC, was believed to be the major driver of Akt activation. However, the inhibitor to Kras was not therapeutic for PDAC patients. This implied that PDAC cells might harbor an intrinsic merit that strengthens Akt activity. Here we showed that BRSK2, a serine/threonine-protein kinase of AMPK family, was induced by nutrient deprivation in PDAC cells and suppressed mTORC1 activity via phosphorylation of tuberous sclerosis complex 2 (TSC2). The suppression of mTORC1 activity in PDAC results in a dominant loss of feedback inhibition on Akt activity by mTORC1, consequently enhancing cell survival. This finding indicates that the intrinsic molecular merit that BRSK2 provides is a survival advantage to PDAC cells and strengthens the invasiveness of these neoplastic cells in energy-deprived environments.

β-Catenin signaling is essential for mammalian larynx recanalization and the establishment of vocal fold progenitor cells

Congenital laryngeal webs result from failure of vocal fold separation during development in utero Infants present with life-threatening respiratory problems at birth, and extensive lifelong difficulties in breathing and voicing. The molecular mechanisms that instruct vocal fold formation are rarely studied. Here, we show, for the first time, that conditional inactivation of the gene encoding β-catenin in the primitive laryngopharyngeal epithelium leads to failure in separation of the vocal folds, which approximates the gross phenotype of laryngeal webbing. These defects can be traced to a series of morphogenesis defects, including delayed fusion of the epithelial lamina and formation of the laryngeal cecum, failed separation of the larynx and esophagus with reduced and disorganized cartilages and muscles. Parallel to these morphogenesis defects, inactivation of β-catenin disrupts stratification of epithelial cells and establishment of p63⁺ basal progenitors. These findings provide the first line of evidence that links β-catenin function to the cell proliferation and progenitor establishment during larynx and vocal fold development.

Extracellular Influences: Molecular Subclasses and the Microenvironment in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is the most prevalent form of pancreatic cancer and carries the worst prognosis of all common cancers. Five-year survival rates have not surpassed 6% for some decades and this lack of improvement in outcome urges a better understanding of the PDAC-specific features which contribute to this poor result. One of the most defining features of PDAC known to contribute to its progression is the abundance of non-tumor cells and material collectively known as the stroma. It is now well recognized that the different non-cancer cell types, signalling molecules, and mechanical properties within a tumor can have both tumor-promoting as well as –inhibitory effects. However, the net effect of this intratumour heterogeneity is not well understood. Heterogeneity in the stromal makeup between patients is even less well established. Such intertumour heterogeneity is likely to be affected by the relative contributions of individual stromal constituents, but how these contributions exactly relate to existing classifications that demarcate intertumour heterogeneity in PDAC is not fully known. In this review, we give an overview of the available evidence by delineating the elements of the PDAC stroma and their contribution to tumour growth. We do so by interpreting the heterogeneity at the gene expression level in PDAC, and how stromal elements contribute to, or interconnect, with this.

LSL-KrasG12D; LSL-Trp53R172H/+; Ink4flox/+; Ptf1/p48-Cre mice are an applicable model for locally invasive and metastatic pancreatic cancer

Pancreatic cancer (PC) accumulates multiple genetic mutations, including activating KRAS mutations and inactivating TP53, SMAD4 and CDKN2A mutations, during progression. The combination of mutant KRAS with a single inactivating TP53, SMAD4 or CDKN2A mutation in genetically engineered mouse models (GEMMs) showed that these mutations exert different synergistic effects in PC. However, the effect of the combination of TP53, CDKN2A and KRAS mutations on the trajectory of PC progression is unknown. Here, we report a GEMM that harbors KRAS (Kras^G12D), TP53 (Trp53^R172H/+), CDKN2A (Ink4^flox/+) and Ptf1/p48-Cre (KPIC) mutations. Histopathology showed that KPIC mice developed adenocarcinoma that strongly resembled the pathology of human PC, characterized by rich desmoplastic stroma and low microvascularity. The median survival of KPIC mice was longer than that of LSL-Kras^G12D; Ink4^flox/flox; Ptf1/p48-Cre mice (KIC) (89 vs 62 days) and shorter than that of KRAS (Kras^G12D), TP53 (Trp53^R172H/+) and Ptf1/p48-Cre (KPC) mice. Moreover, the neoplastic cells of KPIC mice were epithelial, highly proliferative tumor cells that exhibited ERK and MAPK pathway activation and high glucose uptake. Isolated neoplastic cells from spontaneous KPIC tumors showed all molecular profiles and cellular behaviors of spontaneous KPIC tumors, including epithelial-mesenchymal transition (EMT) under drug stress as well as tumorigenic, metastatic and invasive abilities in immunocompetent mice. Furthermore, orthotopic and metastatic tumors of KPIC cells almost recapitulated the pathology of spontaneous KPIC tumors. These data show that in addition to spontaneous KPIC tumors, KPIC cells are a valuable tool for preclinical studies of locally invasive and metastatic PC.

Feeding cancer's sweet tooth: specialized tumour vasculature shuttles glucose in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal neoplasm characterized by a 'fortress' of thick collagen fibres, abundant myofibroblasts, and paradoxically reduced vascularization compared to normal pancreas. Despite these features, PDAC shows no reduction in the uptake of glucose that fuels tumour cell survival. In new work published in The Journal of Pathology, Saiyin and colleagues have identified a novel adaptation of PDAC tumour endothelium; namely, 'hairy-like' basal microvilli that increase the total vascular surface area and correlate with regions of highest glucose uptake. Since basal microvilli are not present on normal pancreatic blood vessels, their presence may add diagnostic value and blocking their function is a potential new treatment strategy for PDAC. This novel finding of basal microvilli on PDAC endothelium is a striking example of how phenotypic plasticity in tumour blood vessels contributes to tumour growth and progression, independent of conventional modes of angiogenesis.