Microenvironmental Determinants of Pancreatic Cancer

Heterogeneity and plasticity of cancer-associated fibroblasts in the pancreatic tumor microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a notably poor prognosis, in urgent need of improved treatment strategies. The desmoplastic PDAC tumor microenvironment (TME), marked by a high concentration of cancer-associated-fibroblasts (CAFs), is a dynamic part of PDAC pathophysiology which occasions a variety of effects throughout the course of pancreatic tumorigenesis and disease evolution. A better understanding of the desmoplastic TME and CAF biology in particular, should provide new opportunities for improving therapeutics. That CAFs have a tumor-supportive role in oncogenesis is well known, yet research evidence has shown that CAFs also have tumor-repressive functions. In this review, we seek to clarify the intriguing heterogeneity and plasticity of CAFs and their ambivalent role in PDAC tumorigenesis and progression. Additionally, we provide recommendations to advance the implementation of CAF-directed PDAC care. An improved understanding of CAFs' origins, spatial location, functional diversity, and marker determination, as well as CAF behavior during the course of PDAC progression and metastasis will provide essential knowledge for the future improvement of therapeutic strategies for patients suffering from PDAC.

Partial ligand shielding nanoparticles improve pancreatic ductal adenocarcinoma treatment via a multifunctional paradigm for tumor stroma reprogramming

The dense stroma that acts as a physical and biological barrier in the tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) leads to the failure of chemotherapeutic drug delivery. Cancer-associated fibroblasts (CAFs) and extracellular matrix (ECM) mainly constitute the refuge for cancer cells in PDAC. Herein, a CAF targeting drug delivery system (TDDS) based on RBC vesicles partial protection (RBC-Fn-NP) was established and investigated for reprogramming stroma, as well as enhancing tumor penetration and antitumor efficacy in PDAC. RBC vesicles were firstly used for partial protection of peptide from external influences. The exposed FnBPA5 peptide showed high affinity with both CAFs and the major components as collagen I and relaxed-fibronectin of ECM. Retinoic acid (RA) could disturb Golgi of CAFs, resulting in the reduction of protein secretion from the headstream. As expected, the strategy of RBC vesicles protected FnBPA5 targeting and RA-induced protein reduction was confirmed to reprogram the dense stroma and improve the penetration of Doxorubicin (Dox) in PDAC. RBC-Fn-NP inhibited tumor growth in both Pan02-orthotopic bearing model and Pan02-subcutaneous mice model. Hence, these partial ligand shielding nanoparticles offer a multifunctional and efficient approach to overcome penetration barriers and enhance the antitumor efficacy of chemotherapy in PDAC. STATEMENT OF SIGNIFICANCE: A partial ligand shielding nanoparticle platform (RBC-Fn-NP), which has the function of an RBC vesicle "shell" and thetargeting properties of a "core" to achieve superior therapeutic effects against PDAC, was established. The targeted ligand was modified on the surface of the nanoparticles instead of the RBC membranes. Three-dimensional PDAC stroma-rich spheroids were established to evaluate the penetration and tumor stroma remodeling. The targeting properties of FnBPA5 peptide, the effect of RA-induced Golgi disruption on the reduction of protein secretion, and the incomplete "camouflage" of the RBC vesicles were confirmed both in vitro and in vivo. As expected, our nanoplatform may provide a promising strategy for remolding dense stroma and enhancing the permeability in PDAC.

Activated Stellate Cell Paracrine HGF Exacerbated Pancreatic Cancer Cell Ferroptosis Resistance

As a refractory tumor, pancreatic carcinoma is more vulnerable to ferroptosis, a novel regulated cell death mode. However, the exact role of pancreatic stellate cells (PSCs) in pancreatic cancer ferroptosis is still unclear. Using the coculture system, we revealed that activated PSCs promote pancreatic cancer cell ferroptosis resistance. Mechanistically, activated PSCs secreted HGF, which further activated the HGF receptor, c-MET, in pancreatic cancer cells, prevented lipid peroxidation, and ultimately triggered pancreatic cancer cell ferroptosis resistance in vitro and in vivo. TCGA and GEPIA databases also revealed a strong correlation between c-MET and antiferroptosis indicators. Our study supplied the evidence for the cross-talk between activated PSCs and pancreatic cancer cells in ferroptosis, which suggested a strategy to inhibit PSC paracrine signaling for preventing pancreatic carcinoma ferroptosis resistance.

SQLE, A Key Enzyme in Cholesterol Metabolism, Correlates With Tumor Immune Infiltration and Immunotherapy Outcome of Pancreatic Adenocarcinoma

Background

Pancreatic adenocarcinoma (PAAD) is a treatment-refractory cancer with poor prognosis. Accumulating evidence suggests that squalene epoxidase (SQLE) plays a pivotal role in the development and progression of several cancer types in humans. However, the function and underlying mechanism of SQLE in PAAD remain unclear.

Methods

SQLE expression data were downloaded from The Cancer Genome Atlas and the Genotype-Tissue Expression database. SQLE alterations were demonstrated based on the cBioPortal database. The upstream miRNAs regulating SQLE expression were predicted using starBase. The function of miRNA was validated by Western blotting and cell proliferation assay. The relationship between SQLE expression and biomarkers of the tumor immune microenvironment (TME) was analyzed using the TIMER and TISIDB databases. The correlation between SQLE and immunotherapy outcomes was assessed using Tumor Immune Dysfunction and Exclusion. The log-rank test was performed to compare prognosis between the high and low SQLE groups.

Results

We demonstrated a potential oncogenic role of SQLE. SQLE expression was upregulated in PAAD, and it predicted poor disease-free survival (DFS) and overall survival (OS) in patients with PAAD. "Amplification" was the dominant type of SQLE alteration. In addition, this alteration was closely associated with the OS, disease-specific survival, DFS, and progression-free survival of patients with PAAD. Subsequently, hsa-miR-363-3p was recognized as a critical microRNA regulating SQLE expression and thereby influencing PAAD patient outcome. In vitro experiments suggested that miR-363-3p could knock down the expression of SQLE and inhibit the proliferation of PANC-1. SQLE was significantly associated with tumor immune cell infiltration, immune checkpoints (including PD-1 and CTLA-4), and biomarkers of the TME. KEGG and GO analyses indicated that cholesterol metabolism-associated RNA functions are implicated in the mechanisms of SQLE. SQLE was inversely associated with cytotoxic lymphocytes and predicted immunotherapy outcomes.

Conclusions

Collectively, our results indicate that cholesterol metabolism-related overexpression of SQLE is strongly correlated with tumor immune infiltration and immunotherapy outcomes in patients with PAAD.

Identification of a novel lipid metabolism-related gene signature within the tumour immune microenvironment for breast cancer

Background

Systemic factors can strongly affect how tumour cells behave, grow, and communicate with other cells in breast cancer. Lipid metabolic reprogramming is a systemic process that tumour cells undergo; however, the formation and dynamics of lipids associated with the tumour immune microenvironment (TIME) remain unclear. The investigation of the sophisticated bidirectional crosstalk of tumour cells with cancer metabolism, gene expression, and TIME could have the potential to identify novel biomarkers for diagnosis, prognosis, and immunotherapy. This study aimed to construct a prognostic signature to detect the bicrosstalk between the lipid metabolic system and the TIME of breast cancer.

Methods

To detect the expression of LRGs and execute GO/KEGG analysis, the R program was chosen. Considering the clinical information and pathological features, a prognostic gene signature was constructed by LASSO Cox regression analysis. TMB, MSI, and immune infiltration analyses were performed, and consensus cluster analysis of LRGs was also performed.

Results

These 16 lipid metabolism-related genes (LRGs) were mainly involved in the process of lipid metabolism and fatty acid binding in breast cancer. Prognosis analysis identified the prognostic value of FABP7(Fatty acid binding protein 7) and NDUFAB1(NADH:ubiquinone oxidoreductase subunit AB1) in breast cancer patients. The prognostic gene signature constructed with FABP7 and NDUFAB1 was significantly related to immune cell infiltration and could predict the overall survival rate with above average correctness of breast cancer patients. FABP7 and NDUFAB1 were proven to have relevance in immune cell infiltration and tumour mutation burden (TMB). Consensus cluster analysis identified that the upregulated mRNAs were mostly related to the oncogenesis process, while the downregulated mRNAs were associated with immune-related signalling pathways.

Conclusion

A comprehensive analysis was performed to evaluate the lipid metabolic system and identified a signature constructed by two prognostic genes for immunotherapies in breast cancer. The results also revealed evidence of vulnerabilities in the interplay between the lipid metabolic system and the TIME in breast cancer. Further data with clinical studies and experiments are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01651-9.

The oncogenic role of tubulin alpha-1c chain in human tumours

Tubulin alpha-1c chain (TUBA1C), a subtype of α-tubulin, has been shown to be involved in cell proliferation and cell cycle progression in several cancers and to influence cancer development and prognosis. However, a pancancer analysis of TUBA1C to reveal its immunological and prognostic roles has not been performed. In this study, we first downloaded raw data on TUBA1C expression in cancers from The Cancer Genome Atlas (TCGA) database and multiple other databases and analysed these data with R software to investigate the prognostic and immunological value of TUBA1C in cancers. Immunohistochemical analysis was performed in gliomas to further validate our findings. Overall, TUBA1C was overexpressed in most cancers, and overexpression of TUBA1C was linked to poor prognosis and higher tumour grade in patients. In addition, TUBA1C expression was associated with tumour mutation burden (TMB), microsatellite instability (MSI), the tumour microenvironment (TME) and the infiltration of immune cells. TUBA1C was also coexpressed with most immune-related genes and influenced immune-related pathways. Immunohistochemical analysis showed that TUBA1C expression was highest in glioblastoma (GBM) tissues, second highest in low-grade glioma (LGG) tissues and lowest in normal tissues. Our study indicated that TUBA1C might be a biomarker for predicting the immune status and prognosis of cancers, offering new ideas for cancer treatment.

Cascade Drug Delivery through Tumor Barriers of Pancreatic Cancer via Ultrasound in Combination with Functional Microbubbles

The abundant desmoplastic stroma and the lack of sufficient targets on pancreatic cancer cells render poor drug penetration and cellular uptake, which significantly compromise the chemotherapy efficacy. Herein, we reported a three-step cascade delivery strategy for selective delivery of paclitaxel (PTX) to achieve a targeted therapy for pancreatic cancer. cRGD and cCLT1 peptides, which could target the integrin and fibronectin, respectively, overexpressed in pancreatic cancer cells and stroma, were decorated on PTX-loaded microbubbles, resulting in the formation of dual-targeting PTX-RCMBs. In this strategy, ultrasound in combination with PTX-RCMBs first enhanced the permeability of tumor vessels via cavitation effects and simultaneously helped the generated PTX-RCNPs penetrate into the stroma. Then, the cCLT1 peptide modified on PTX-RCNPs selectively bound the fibronectin highly expressed in the stroma and later targeted the integrin (α5β1) on the cell surface. Finally, another targeting cRGD peptide modified on PTX-RCNPs would further promote PTX uptake via targeting the integrin (αvβ3) on the cell surface. This strategy significantly increased the delivery of PTX into tumor tissues. Moreover, the in vivo effective accumulation of PTX was monitored by ultrasound and fluorescence bimodal imaging. The tumor growth inhibition was investigated on subcutaneous tumor mouse models with 89.8% growth inhibition rate during 21 days of treatment, showing great potential for improving pancreatic cancer therapy.

The Impact of Epithelial-Mesenchymal Transition and Metformin on Pancreatic Cancer Chemoresistance: A Pathway towards Individualized Therapy

Globally, pancreatic ductal adenocarcinoma remains among the most aggressive forms of neoplastic diseases, having a dismal prognostic outcome. Recent findings elucidated that epithelial-mesenchymal transition (EMT) can play an important role in pancreatic tumorigenic processes, as it contributes to the manifestation of malignant proliferative masses, which impede adequate drug delivery. An organized literature search with PubMed, Scopus, Microsoft Academic and the Cochrane library was performed for articles published in English from 2011 to 2021 to review and summarize the latest updates and knowledge on the current understanding of EMT and its implications for tumorigenesis and chemoresistance. Furthermore, in the present paper, we investigate the recent findings on metformin as a possible neoadjuvant chemotherapy agent, which affects EMT progression and potentially provides superior oncological outcomes for PDAC patients. Our main conclusions indicate that selectively suppressing EMT in pancreatic cancer cells has a promising therapeutic utility by selectively targeting the chemotherapy-resistant sub-population of cancer stem cells, inhibiting tumor growth via EMT pathways and thereby improving remission in PDAC patients. Moreover, given that TGF-β1-driven EMT generates the migration of tumor-initiating cells by directly linking the acquisition of abnormal cellular motility with the maintenance of tumor initiating potency, the chemoprevention of TGF-β1-induced EMT may have promising clinical applications in the therapeutic management of PDAC outcomes.

The multifaceted role of Matricellular Proteins in health and cancer, as biomarkers and therapeutic targets

The extracellular matrix (ECM) is composed of a mesh of proteins, proteoglycans, growth factors, and other secretory components. It constitutes the tumor microenvironment along with the endothelial cells, cancer-associated fibroblasts, adipocytes, and immune cells. The proteins of ECM can be functionally classified as adhesive proteins and matricellular proteins (MCP). In the tumor milieu, the ECM plays a major role in tumorigenesis and therapeutic resistance. The current review encompasses thrombospondins, osteonectin, osteopontin, tenascin C, periostin, the CCN family, laminin, biglycan, decorin, mimecan, and galectins. The matrix metalloproteinases (MMPs) are also discussed as they are an integral part of the ECM with versatile functions in the tumor stroma. In this review, the role of these proteins in tumor initiation, growth, invasion and metastasis have been highlighted, with emphasis on their contribution to tumor therapeutic resistance. Further, their potential as biomarkers and therapeutic targets based on existing evidence are discussed. Owing to the recent advancements in protein targeting, the possibility of agents to modulate MCPs in cancer as therapeutic options are discussed.

SIRT7 is a Prognostic Biomarker in Kidney Renal Clear Cell Carcinoma That is Correlated with Immune Cell Infiltration

Background

SIRT7 has been shown to be expressed in many cancer types, including clear cell renal cell carcinoma (KIRC), but its functional role in this oncogenic context remains to be firmly defined. This study was designed to explore correlations between SIRT7 and KIRC characteristics using the TCGA database.

Methods

Relationships between SIRT7 expression and KIRC patient clinicopathological characteristics were assessed through Kruskal-Wallis tests, Wilcoxon signed-rank tests, and logistic regression analyses. Area under the ROC curve (AUC) values were used to assess the prognostic value of SIRT7 as a means of classifying clear cell renal cell carcinoma patients. The functional role of SIRT7 in this cancer type was assessed through GO/KEGG enrichment analyses and immune cell infiltration analyses.

Results

In KIRC patients, higher levels of SIRT7 expression were associated with Race, M stage, T stage (all P < 0.05). SIRT7 offered significant diagnostic value in ROC curve analyses (AUC = 0.912), and elevated SIRT7 levels were linked to worse patient overall survival (OS; P < 0.001). The expression of SIRT7 was independently related with KIRC patient OS (HR: 1.827; 95% CI: 1.346-2.481; P<0.001). In GO/KEGG analyses, SIRT7 was found to be associated with ubiquitin-mediated proteolysis and nucleotide excision repair. Higher SIRT7 expression was related to the enhanced infiltration of certain immune cells.

Conclusion

Increased SIRT7 expression was associated with a worse KIRC patient prognosis, and immune infiltrates, suggesting it may offer value as a prognostic biomarker for this cancer type.

Overexpressing PLOD Family Genes Predict Poor Prognosis in Pancreatic Cancer

Background

Pancreatic cancer is a common malignant tumor. Multiple studies have shown that procollagen lysyl-hydroxylase (PLOD) family genes were closely related to tumor progression and metastasis in a variety of human cancers. This study aimed to explore the prognosis and biological role of PLOD family genes in pancreatic adenocarcinoma (PAAD).

Methods

GEPIA, GEO, HPA, CCLE, Kaplan-Meier plotter, cBioPortal, LinkedOmics, DAVID6.8, STRING, and TIMER were employed to determine the prognostic values and biological function of PLOD family members in PAAD.

Results

The mRNA and protein expression patterns of PLOD family members were noticeably up-regulated in PAAD compared with normal tissues. PLOD family gene expression was also up-regulated in pancreatic cancer cell lines. PLOD1 was correlated with histological and pathological grades of pancreatic cancer. PLOD2 was related to histological grade. The high expression of PLOD1-2 was correlated with the poor overall survival rate and relapse-free survival rate in patients with PAAD. Additionally, PLODs showed high sensitivity and specificity in distinguishing pancreatic cancer from normal tissues. Through the functional enrichment analysis of PLOD-related genes in PAAD, we found that PLODs were enriched in collagen fiber tissue structure, lysine degradation, and collagen biosynthesis. Pathway analysis confirmed that PLODs regulated the proliferation, migration, and metastasis of pancreatic cancer through the RalGEF-Ral signaling pathway. Furthermore, the level of expression of PLOD1-2 was positively correlated with the activity of tumor-infiltrating immune cells, including CD8+T cells, neutrophils, macrophages, and dendritic cells. The level of expression of PLOD3 was inversely correlated with the level of infiltration of CD8+T cells. PLOD1 and PLOD2 were highly expressed in pancreatic cancer tissues with TP53 and KRAS mutations, respectively. However, the level of expression of PLOD3 in SMAD4 wild-type pancreatic cancer was increased.

Conclusion

The findings showed that individual PLOD genes or PLOD family genes could be potential prognostic biomarkers for PAAD.

Concerted BAG3 and SIRPα blockade impairs pancreatic tumor growth

The BAG3- and SIRPα- mediated pathways trigger distinct cellular targets and signaling mechanisms in pancreatic cancer microenvironment. To explore their functional connection, we investigated the effects of their combined blockade on cancer growth in orthotopic allografts of pancreatic cancer mt4–2D cells in immunocompetent mice. The anti-BAG3 + anti-SIRPα mAbs treatment inhibited (p = 0.007) tumor growth by about the 70%; also the number of metastatic lesions was decreased, mostly by the effect of the anti-BAG3 mAb. Fibrosis and the expression of the CAF activation marker α-SMA were reduced by about the 30% in animals treated with anti-BAG3 mAb compared to untreated animals, and appeared unaffected by treatment with the anti-SIRPα mAb alone; however, the addition of anti-SIRPα to anti-BAG3 mAb in the combined treatment resulted in a > 60% (p < 0.0001) reduction of the fibrotic area and a 70% (p < 0.0001) inhibition of CAF α-SMA positivity. Dendritic cells (DCs) and CD8+ lymphocytes, hardly detectable in the tumors of untreated animals, were modestly increased by single treatments, while were much more clearly observable (p < 0.0001) in the tumors of the animals subjected to the combined treatment. The effects of BAG3 and SIRPα blockade do not simply reflect the sum of the effects of the single blockades, indicating that the two pathways are connected by regulatory interactions and suggesting, as a proof of principle, the potential therapeutic efficacy of a combined BAG3 and SIRPα blockade in pancreatic cancer.

Resveratrol inhibits the expression of RYR2 and is a potential treatment for pancreatic cancer

Resveratrol is a polyphonous natural compound that has cardioprotective, anticancer, and anti-inflammatory properties. Studies have proved that resveratrol (RES) inhibits cancer cell proliferation, migration, and invasion and promotes apoptosis. Elevated expression of ryanodine receptor type 2 (RYR2) may participate in the pathway responsible for calcium metabolism as well as anti-apoptosis and anti-autophagy events in malignant tumor cells. However, the underlying molecular mechanisms of RES anticancer effects with RYR2 are not completely understood in pancreatic cancer. The aim of the present study was tantamount to study the effect of RES in human pancreatic cancer and investigate the underlying mechanisms of RES. We found that RES inhibits proliferation, migration, and invasion and suppresses RYR2 expression in pancreatic cancer cells. In addition, RYR2 knockdown impedes the proliferation, migration, and invasiveness of pancreatic cancer cells. RYR2 knockdown can also increase PTEN expression, while increased RYR2 expression can inhibit PTEN expression. Moreover, RES can upregulate PTEN expression. Taken together, these results indicate that RES could play an antitumor role by decreasing RYR2 expression.

Recent advances in targeted drug delivery for the treatment of pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) has become a serious health problem with high impact worldwide. The heterogeneity of PDAC makes it difficult to apply drug delivery systems (DDS) used in other cancer models, for example, the poorly developed vascular system makes anti-angiogenic therapy ineffective. Due to its various malignant pathological changes, drug delivery against PDAC is a matter of urgent concern. Based on this situation, various drug delivery strategies specially designed for PDAC have been generated.

AREAS COVERED

This review will briefly describe how delivery systems can be designed through nanotechnology and formulation science. Most research focused on penetrating the stromal barrier, exploiting and alleviating the hypoxic microenvironment, targeting immune cells, or designing vaccines, and combination therapies. This review will summarize the ways to reverse the malignant pathological features of PDAC and hopefully provide ideas for subsequent studies.

EXPERT OPINION

Drug delivery systems designed to achieve penetrating functions or to alleviate hypoxia and activate immunity have achieved good therapeutic results in animal models in several studies. In future studies, there is a need to deliver PDAC therapeutics in a more precise manner, or the use of drug carriers for multiple functions simultaneously, are potential therapeutic strategy.

Schwann Cells in Digestive System Disorders

Proper functioning of the digestive system is ensured by coordinated action of the central and peripheral nervous systems (PNS). Peripheral innervation of the digestive system can be viewed as intrinsic and extrinsic. The intrinsic portion is mainly composed of the neurons and glia of the enteric nervous system (ENS), while the extrinsic part is formed by sympathetic, parasympathetic, and sensory branches of the PNS. Glial cells are a crucial component of digestive tract innervation, and a great deal of research evidence highlights the important status of ENS glia in health and disease. In this review, we shift the focus a bit and discuss the functions of Schwann cells (SCs), the glial cells of the extrinsic innervation of the digestive system. For more context, we also provide information on the basic findings regarding the function of innervation in disorders of the digestive organs. We find diverse SC roles described particularly in the mouth, the pancreas, and the intestine. We note that most of the scientific evidence concerns the involvement of SCs in cancer progression and pain, but some research identifies stem cell functions and potential for regenerative medicine.

N6-Methyladenosine Methylation Regulator RBM15 is a Potential Prognostic Biomarker and Promotes Cell Proliferation in Pancreatic Adenocarcinoma

RNA binding motif protein 15 (RBM15) is a key regulatory factor involved in N6-methyladenosine (m6A) methylation. It has been reported that RBM15 plays an important role in the progress of laryngeal squamous cell carcinoma (LSCC), promoting LSCC migration and invasion. However, the role of RBM15 in human different cancers remains unknown. This study aims to analyze the prognostic value of RBM15, and to demonstrate the correlation between RBM15 expression and tumor immunity, as well as to provide clues for further mechanism research. The results showed that RBM15 was mutated or copy number varied in 25 types of cancer. RBM15 mRNA was abnormally up-regulated across various cancers. Survival analysis suggested high expression of RBM15 was associated with poor prognosis in many cancer types. Among these, it affected patients’ overall survival (OS) in 10 cancer types, disease-free interval (DFI) in 8 cancer types, progression-free interval (PFI) in 12 cancer types and disease-specific survival (DSS) in 7 cancer types. Importantly, in pancreatic adenocarcinoma (PAAD), overexpression of RBM15 is associated with patients’ OS, DFI, PFI, or DSS. In addition, RBM15 expression was positively correlated with immune infiltrating cells in kidney renal clear cell carcinoma (KIRC), brain lower grade glioma (LGG), and PAAD. Moreover, RBM15 expression showed a strong correlation with immune checkpoint markers in PAAD. Cell counting kit-8 (CCK-8) assay showed that knockdown of RBM15 significantly inhibited the proliferation of pancreatic cancer cells. PPI analysis showed USP10, USP24, SMG1, NRAS were closely connected with RBM15 alterations. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that many biological processes (BP), cellular components (CC), molecular functions (MF), cancer related pathways including “sister chromatid cohesion”, “peptidyl-serine phosphorylation”, “cell division”, “nucleoplasm”, “nucleus”, “protein binding”, “protein serine/threonine kinase activity”, “T cell receptor signaling pathway”, “Cell cycle” were regulated by RBM15 alterations. Taken together, pan-cancer analysis of RBM15 suggested it may be served as a prognostic biomarker and immunotherapeutic target for PAAD.

Epigenetic Therapeutic Strategies to Target Molecular and Cellular Heterogeneity in Pancreatic Cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) remains a major challenge in cancer medicine and is characterized by a 5-year survival rate of <10%. Compelling evidence suggests that the devastating disease outcome of PDAC patients is linked to a high degree of intra- and interindividual tumor heterogeneity, which is predominantly installed at the level of gene transcription. The cellular and molecular complexities of the disease explain the poor efficacy of "one-size-fits-all" therapeutic approaches in PDAC treatment and strongly argue for pursuing tailored therapeutic strategies to tackle PDAC. In a highly dynamic manner, a network of transcription factors and epigenetic regulatory proteins temporally and spatially control the diverse transcriptomic states determining PDAC heterogeneity. Given the reversibility of epigenetic processes, pharmacological intervention with key epigenetic drivers of PDAC heterogeneity appeals as a promising concept to shift the transcriptomic phenotype of PDAC toward a less aggressive and more chemosensible state.

SUMMARY

In this review, we discuss the chances and pitfalls of epigenetic treatment strategies in overcoming and shifting molecular and cellular PDAC heterogeneities in order to combat PDAC. To this end, we utilized the keywords "pancreatic cancer," "heterogeneity," and "epigenetics" to search for relevant articles on the database PubMed and selected interventional studies enrolling PDAC patients as displayed in clinicaltrails.gov to generate a synopsis of clinical trials involving epigenetic targeting.

KEY MESSAGES

Targeting epigenetic regulators in PDAC represents a promising concept to reprogram molecular and cellular tumor heterogeneities in the pancreas and hence to modulate the PDAC phenotype in favor of a less aggressive and more therapy susceptible disease course. However, we just start to understand the complex interactions of epigenetic regulators in controlling PDAC plasticity, and a clinical breakthrough utilizing epigenetic targeting in PDAC patients has not been achieved yet. Nevertheless, increasing translational efforts which consider the pleiotropic effects of targeting epigenetic regulation in different cellular compartments of the tumor and that focus on the utility and sequence of combinatory treatment approaches might pave the way toward novel epigenetic treatment strategies in PDAC therapy.

Membrane-camouflaged supramolecular nanoparticles for co-delivery of chemotherapeutic and molecular-targeted drugs with siRNA against patient-derived pancreatic carcinoma

Pancreatic cancer remains one of the most lethal malignancies worldwide. The combination of the first-line standard agent gemcitabine (GEM) with the molecular-targeted drug erlotinib (Er) has emerged as a promising strategy for pancreatic cancer treatment. However, the clinical benefit from this combination is still far from satisfactory due to the unfavorable drug antagonism and the fibrotic tumor microenvironment. Herein, we propose a membrane-camouflaged dual stimuli-responsive delivery system for the co-delivery of GEM and Er into pancreatic cancer cells and tissues to block the antagonism, as well as reshapes profibrotic tumor microenvironment via simultaneous delivery of small interference RNA (siRNA) for synergistic pancreatic cancer treatment. This “all-in-one” delivery system exhibits sensitive GSH and pH-dependent drug release profiles and enhances the inhibitory effects on the proliferation and migration of tumor cells in vitro. Excitingly, the systemic injection of such a biomimetic drug co-delivery system not only resulted in superior inhibitory effects against orthotopic pancreatic tumor and patient-derived tumor (PDX), but also greatly extended the survival rate of tumor-bearing mice. Our findings provide a promising therapeutic strategy against pancreatic cancer through the enhanced synergistic effect of target therapy, chemotherapy and anti-fibrotic therapy, which represents an appealing way for pancreatic cancer treatment.

Emerging Role of Epigenetic Alterations as Biomarkers and Novel Targets for Treatments in Pancreatic Ductal Adenocarcinoma

Simple Summary

Epigenetic alterations cause changes in gene expression without affecting the DNA sequence and are found to affect several molecular pathways in pancreatic tumors. Such changes are reversible, making them potential drug targets. Furthermore, epigenetic alterations occur early in the disease course and may thus be explored for early detection. Hence, a deeper understanding of epigenetics in pancreatic cancer may lead to improved diagnostics, treatments, and prognostication.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with limited treatment options. Emerging evidence shows that epigenetic alterations are present in PDAC. The changes are potentially reversible and therefore promising therapeutic targets. Epigenetic aberrations also influence the tumor microenvironment with the potential to modulate and possibly enhance immune-based treatments. Epigenetic marks can also serve as diagnostic screening tools, as epigenetic changes occur at early stages of the disease. Further, epigenetics can be used in prognostication. The field is evolving, and this review seeks to provide an updated overview of the emerging role of epigenetics in the diagnosis, treatment, and prognostication of PDAC.

Tumor Microenvironment in Pancreatic Intraepithelial Neoplasia

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive neoplasm with a poor survival rate. This is mainly due to late detection, which substantially limits therapy options. A better understanding of the early phases of pancreatic carcinogenesis is fundamental for improving patient prognosis in the future. In this article, we focused on the tumor microenvironment (TME), which provides the biological niche for the development of PDAC from its most common precursor lesions, PanIN (pancreatic intraepithelial neoplasias).

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive tumors with a poor prognosis. A characteristic of PDAC is the formation of an immunosuppressive tumor microenvironment (TME) that facilitates bypassing of the immune surveillance. The TME consists of a desmoplastic stroma, largely composed of cancer-associated fibroblasts (CAFs), immunosuppressive immune cells, immunoregulatory soluble factors, neural network cells, and endothelial cells with complex interactions. PDAC develops from various precursor lesions such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasms (IPMN), mucinous cystic neoplasms (MCN), and possibly, atypical flat lesions (AFL). In this review, we focus on the composition of the TME in PanINs to reveal detailed insights into the complex restructuring of the TME at early time points in PDAC progression and to explore ways of modifying the TME to slow or even halt tumor progression.

Circulating EVs long RNA-based subtyping and deconvolution enable prediction of immunogenic signatures and clinical outcome for PDAC

Identification of clinically applicable molecular subtypes of pancreatic ductal adenocarcinoma (PDAC) is crucial to improving patient outcomes. However, the traditional tissue-dependent transcriptional subtyping strategies are invasive and not amenable to routine clinical evaluation. In this study, we developed a circulating extracellular vesicle (cEV) long RNA (exLR)-based PDAC subtyping method and provided exLR-derived signatures for predicting immunogenic features and clinical outcomes in PDAC. We enrolled 426 individuals, among which 227 PDACs served as an internal cohort, 118 PDACs from two other medical centers served as an independent validation cohort, and 81 healthy individuals served as the control. ExLR sequencing was performed on all plasma samples. We found that PDAC could be categorized into three subtypes based on plasma exLR profiles. Each subpopulation showed its own molecular features and was associated with patient clinical prognosis. The immunocyte-derived cEV fractions were altered among PDAC subtypes and interconnected with tumor-infiltrating lymphocytes in cancerous tissue. Additionally, we found a significant concordance of immunoregulators between tissue and blood EVs, and we harvested potential PDAC therapeutic targets. Most importantly, we constructed a nine exLR-derived, tissue-applicable signature for prognostic assessment of PDAC. The circulating exLR-based features may offer an attractive platform for personalized treatment and predicting patient outcomes in multiple types of cancer.

Nine Pyroptosis-Related lncRNAs are Identified as Biomarkers for Predicting the Prognosis and Immunotherapy of Endometrial Carcinoma

Background

Endometrial carcinoma (EC) is one of the most common malignancies. Immunotherapy has shown promising effects in the treatment against specific subtypes of EC.

Methods

The RNA and clinical information of patients with EC were acquired from The Cancer Gene Atlas (TCGA) database. Firstly, the differentially expressed pyroptosis-related lncRNAs (PRLs) were screened between the tumor and normal control tissue. Secondly, the PRLs closely related to survival were identified by univariate and multivariate regression analysis, based on which, we evaluated the risk score for each EC patient to construct a risk signature. Moreover, we assessed the prognostic value, clinical relevance immunity, and immunotherapy based on this signature.

Results

We screened out 9 individual PRLs (AC087491.1, AL353622.1, AL035530.2, LINC02036, AL021578.1, AL390195.2, AC009097.2, AC004585.1, and AC244517.7) closely related to the prognosis of EC. Kaplan–Meier analyses showed a poorer prognosis for the patients in the high-risk FRLs signature (P < 0.001). The area under the curve (AUC) for 1 year, 2 years, 3 years was 0.693, 0.694, 0.750, respectively. Our risk model could be considered as an independent prognostic marker for EC (P < 0.001, HR:2.172, 95% CI:1.532–3.079). Moreover, immune functions and checkpoints were generally different in the 2 groups. Simulation analysis by termed immunophenoscores hinted that immunotherapy might bring optimal therapeutic effect in the low-risk group.

Conclusion

We successfully developed a novel signature with 9 lncRNAs related to pyroptosis, which may be used as biomarkers to evaluate the prognosis and immune treatment of EC.

Nanoparticle-based delivery systems modulate the tumor microenvironment in pancreatic cancer for enhanced therapy

Pancreatic cancer is one of the most lethal malignant tumors with a low survival rate, partly because the tumor microenvironment (TME), which consists of extracellular matrix (ECM), cancer-associated fibroblasts (CAFs), immune cells, and vascular systems, prevents effective drug delivery and chemoradiotherapy. Thus, modulating the microenvironment of pancreatic cancer is considered a promising therapeutic approach. Since nanoparticles are one of the most effective cancer treatment strategies, several nano-delivery platforms have been developed to regulate the TME and enhance treatment. Here, we summarize the latest advances in nano-delivery systems that alter the TME in pancreatic cancer by depleting ECM, inhibiting CAFs, reversing immunosuppression, promoting angiogenesis, or improving the hypoxic environment. We also discuss promising new targets for such systems. This review is expected to improve our understanding of how to modulate the pancreatic cancer microenvironment and guide the development of new therapies.

Long Noncoding Competing Endogenous RNA Networks in Pancreatic Cancer

Pancreatic cancer (PC) is a highly malignant disease characterized by insidious onset, rapid progress, and poor therapeutic effects. The molecular mechanisms associated with PC initiation and progression are largely insufficient, hampering the exploitation of novel diagnostic biomarkers and development of efficient therapeutic strategies. Emerging evidence recently reveals that noncoding RNAs (ncRNAs), including long ncRNAs (lncRNAs) and microRNAs (miRNAs), extensively participate in PC pathogenesis. Specifically, lncRNAs can function as competing endogenous RNAs (ceRNAs), competitively sequestering miRNAs, therefore modulating the expression levels of their downstream target genes. Such complex lncRNA/miRNA/mRNA networks, namely, ceRNA networks, play crucial roles in the biological processes of PC by regulating cell growth and survival, epithelial-mesenchymal transition and metastasis, cancer stem cell maintenance, metabolism, autophagy, chemoresistance, and angiogenesis. In this review, the emerging knowledge on the lncRNA-associated ceRNA networks involved in PC initiation and progression will be summarized, and the potentials of the competitive crosstalk as diagnostic, prognostic, and therapeutic targets will be comprehensively discussed.

TNF-α-producing macrophages determine subtype identity and prognosis via AP1 enhancer reprogramming in pancreatic cancer

Large-scale genomic profiling of pancreatic cancer (PDAC) has revealed two distinct subtypes: 'classical' and 'basal-like'. Their variable coexistence within the stromal immune microenvironment is linked to differential prognosis; however, the extent to which these neoplastic subtypes shape the stromal immune landscape and impact clinical outcome remains unclear. By combining preclinical models, patient-derived xenografts, as well as FACS-sorted PDAC patient biopsies, we show that the basal-like neoplastic state is sustained via BRD4-mediated cJUN/AP1 expression, which induces CCL2 to recruit tumor necrosis factor (TNF)-α-secreting macrophages. TNF-α+ macrophages force classical neoplastic cells into an aggressive phenotypic state via lineage reprogramming. Integration of ATAC-, ChIP- and RNA-seq data revealed distinct JUNB/AP1 (classical) and cJUN/AP1 (basal-like)-driven regulation of PDAC subtype identity. Pharmacological inhibition of BRD4 led to suppression of the BRD4-cJUN-CCL2-TNF-α axis, restoration of classical subtype identity and a favorable prognosis. Hence, patient-tailored therapy for a cJUNhigh/TNF-αhigh subtype is paramount in overcoming highly inflamed and aggressive PDAC states.

miR‑32‑5p suppresses the proliferation and migration of pancreatic adenocarcinoma cells by targeting TLDC1

Pancreatic adenocarcinoma (PAAD) is one of the most fatal types of cancer in humans. However, the molecular mechanisms underlying the migration and invasion abilities of PAAD cells remain unclear. The aim of the present study was to explore the regulatory roles of microRNA (miR)‑32‑5p in PAAD cells. miR‑32‑5p mimic and inhibitor were used to transfect the human PAAD AsPC‑1 cell line to determine the role of miR‑32‑5p in cell proliferation and metastasis. The starBase database predicted the binding of miR‑32‑5p to the target gene TBC/LysM‑associated domain containing 1 (TLDC1). Further analyses were performed to assess miR‑32‑5p and TLDC1 expression levels in healthy and PAAD tissues, as well as the association between miR‑32‑5p or TLDC1 expression and the prognosis of patients with PAAD. The interaction between miR‑32‑5p and TLDC1 was verified using the dual‑luciferase reporter assay. miR‑32‑5p and TLDC1 expression levels were detected by reverse transcription‑quantitative PCR and western blotting, respectively. The Cell Counting Kit‑8 assay was utilised to assess cell proliferation, whereas the wound‑healing and Transwell assays were conducted to assess cell migration and invasion, respectively. miR‑32‑5p expression levels were markedly lower in PAAD tissue compared with those in healthy tissue, and were significantly lower in PAAD cell lines compared with those in the human pancreatic duct cell line HPDE6, which corresponded with poor prognosis. miR‑32‑5p significantly inhibited the proliferation of PAAD cells and markedly reduced migration and invasion compared with the negative controls. miR‑32‑5p was shown to target TLDC1, with miR‑32‑5p expression in PAAD being negatively correlated with TLDC1 expression. High TLDC1 expression levels were associated with a poorer prognosis compared with low TLDC1 expression levels. Co‑transfection of miR‑32‑5p mimic and pcDNA/TLDC1 demonstrated that TLDC1 significantly reversed miR‑32‑5p‑mediated inhibition of the proliferation, migration and invasion of PAAD cells. Overall, the present study demonstrated that miR‑32‑5p may serve as a tumor‑suppressor gene by inhibiting the proliferation and migration and invasion of PAAD cells via the downregulation of TLDC1. Therefore, miR‑32‑5p may serve as a potential diagnostic or prognostic marker for PAAD.

Clinical M2 macrophages-related genes to aid therapy in pancreatic ductal adenocarcinoma

Background

Increasing evidence supports that infiltration M2 Macrophages act as pivotal player in tumor progression of pancreatic ductal adenocarcinoma (PDAC). Nonetheless, comprehensive analysis of M2 Macrophage infiltration and biological roles of hub genes (FAM53B) in clinical outcome and immunotherapy was lack.

Method

The multiomic data of PDAC samples were downloaded from distinct datasets. CIBERSORT algorithm was performed to uncover the landscape of TIME. Weighted gene co-expression network analysis (WGCNA) was performed to identify candidate module and significant genes associated with M2 Macrophages. Kaplan-Meier curve and receiver operating characteristic (ROC) curves were applied for prognosis value validation. Mutation data was analyzed by using “maftools” R package. Gene set variation analysis (GSVA) was employed to assign pathway activity estimates to individual sample. Immunophenoscore (IPS) was implemented to estimate immunotherapeutic significance of risk score. The half-maximal inhibitory concentration (IC50) of chemotherapeutic drugs was predicted by using the pRRophetic algorithm. Finally, quantitative real-time polymerase chain reaction was used to determine FAM53B mRNA expression and TIMER database was utilized to uncover its possible role in immune infiltration of PDAC.

Results

Herein, 17,932 genes in 234 samples (214 tumor and 20 normal) were extracted from three platforms. Taking advantage of WGCNA, significant module (royalblue) and 135 candidate genes were considered as M2 Macrophages-related genes. Subsequently, risk signature including 5 hub genes was developed by multiple analysis, which exhibited excellent prognostic performance. Besides, comprehensive prognostic nomogram was constructed to quantitatively estimate risk. Then, intrinsic link between risk score with tumor mutation burden (TMB) was explored. Additionally, risk score significantly correlated with diversity of tumor immune microenvironment (TIME). PDAC samples within different risk presented diverse signaling pathways activity and experienced significantly distinct sensitivity to administering chemotherapeutic or immunotherapeutic agents. Finally, the biological roles of FAM53B were revealed in PDAC.

Conclusions

Taken together, comprehensive analyses of M2 Macrophages profiling will facilitate prognostic prediction, delineating complexity of TIME, and contribute insight into precision therapy for PDAC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02289-w.

Current status of immunotherapy for pancreatic cancer

Pancreatic cancer is a kind of digestive tract malignant tumor with a poor prognosis. Radical surgery is the preferred alternative choice for patients with pancreatic cancer, but most patients have no chance of radical surgery when they are diagnosed. At present, a number of studies have been carried out on immunotherapies for pancreatic cancer, mainly including immune checkpoint inhibitors, tumor vaccines, and adoptive cell therapy, which are expected to become a new strategy for the treatment of pancreatic cancer, and ultimately achieve the purpose of improving the overall prognosis of patients with pancreatic cancer. In this paper, we summarize the current status of pancreatic cancer immunotherapy and analyze the future trend of immunotherapy for pancreatic cancer.

Therapeutic antibodies - natural and pathological barriers and strategies to overcome them

Antibody-based therapeutics have become a major class of therapeutics with over 120 recombinant antibodies approved or under review in the EU or US. This therapeutic class has experienced a remarkable expansion with an expected acceleration in 2021-2022 due to the extraordinary global response to SARS-CoV2 pandemic and the public disclosure of over a hundred anti-SARS-CoV2 antibodies. Mainly delivered intravenously, alternative delivery routes have emerged to improve antibody therapeutic index and patient comfort. A major hurdle for antibody delivery and efficacy as well as the development of alternative administration routes, is to understand the different natural and pathological barriers that antibodies face as soon as they enter the body up to the moment they bind to their target antigen. In this review, we discuss the well-known and more under-investigated extracellular and cellular barriers faced by antibodies. We also discuss some of the strategies developed in the recent years to overcome these barriers and increase antibody delivery to its site of action. A better understanding of the biological barriers that antibodies have to face will allow the optimization of antibody delivery near its target. This opens the way to the development of improved therapy with less systemic side effects and increased patients' adherence to the treatment.

RNA m6A Demethylase ALKBH5 Protects Against Pancreatic Ductal Adenocarcinoma via Targeting Regulators of Iron Metabolism

Although RNA m6A regulators have been implicated in the tumorigenesis of several different types of tumors, including pancreatic cancer, their clinical relevance and intrinsic regulatory mechanism remain elusive. This study analyzed eight m6A regulators (METTL3, METTL14, WTAP, FTO, ALKBH5, and YTHDF1-3) in pancreatic ductal adenocarcinoma (PDAC) and found that only RNA m6A demethylase ALKBH5 serves as an independent favorable prognostic marker for this tumor. To better understand the molecular mechanism underlying the protective effect conferred by ALKBH5 against pancreatic tumorigenesis, we performed a transcriptome-wide analysis of m6A methylation, gene expression, and alternative splicing (AS) using the MIA PaCa-2 stable cell line with ALKBH5 overexpression. We demonstrated that ALKBH5 overexpression induced a reduction in RNA m6A levels globally. Furthermore, mRNAs encoding ubiquitin ligase FBXL5, and mitochondrial iron importers SLC25A28 and SLC25A37, were identified as substrates of ALKBH5. Mechanistically, the RNA stabilities of FBXL5 and SLC25A28, and the AS of SLC25A37 were affected, which led to their upregulation in pancreatic cancer cell line. Particularly, we observed that downregulation of FBXL5 in tumor samples correlated with shorter survival time of patients. Owing to FBXL5-mediated degradation, ALKBH5 overexpression incurred a significant reduction in iron-regulatory protein IRP2 and the modulator of epithelial-mesenchymal transition (EMT) SNAI1. Notably, ALKBH5 overexpression led to a significant reduction in intracellular iron levels as well as cell migratory and invasive abilities, which could be rescued by knocking down FBXL5. Overall, our results reveal a previously uncharacterized mechanism of ALKBH5 in protecting against PDAC through modulating regulators of iron metabolism and underscore the multifaceted role of m6A in pancreatic cancer.

Rationale for MYC imaging and targeting in pancreatic cancer

The incidence and lethality of pancreatic ductal adenocarcinoma (PDAC) will continue to increase in the next decade. For most patients, chemotherapeutic combination therapies remain the standard of care. The development and successful implementation of precision oncology in other gastrointestinal tumor entities point to opportunities also for PDAC. Therefore, markers linked to specific therapeutic responses and important subgroups of the disease are needed. The MYC oncogene is a relevant driver in PDAC and is linked to drug resistance and sensitivity. Here, we update recent insights into MYC biology in PDAC, summarize the connections between MYC and drug responses, and point to an opportunity to image MYC non-invasively. In sum, we propose MYC-associated biology as a basis for the development of concepts for precision oncology in PDAC.

Iodine concentration and tissue attenuation in dual-energy contrast-enhanced CT as a potential quantitative parameter in early detection of local pancreatic carcinoma recurrence after surgical resection

PURPOSE

Due to the difficult differentiation from non-specific postoperative soft tissue formation (PSF), early diagnosis of pancreatic carcinoma recurrence remains challenging. Thus, we investigated the diagnostic potential of dual-energy (DE) contrast-enhanced CT.

METHOD

After potentially curative pancreatic carcinoma resection, 31 consecutive patients with PSF were examined via DE perfusion CT, acquiring 34 images (80 kVp/140 kVp) every 1.5 s, as the initial purpose of this study was evaluating CT-Perfusion. Corresponding time points of arterial, pancreatic, and early venous phase were calculated from bolus trigger times in prior conventional CT. Iodine and 120 kVp-equivalent images were calculated. Regions of interest were placed in each soft tissue formation. Diagnosis of local recurrence was confirmed by regular follow-up or histopathology.

RESULTS

Final diagnosis was local recurrence in 17 patients and non-specific PSF in 14 patients. Iodine concentrations in early venous phase were significantly higher in recurrent carcinoma than in non-specific PSF (1.47 mg/ml vs. 0.96 mg/ml, p = 0.007). In earlier contrast phases iodine concentrations tended to be higher, but not significantly. CT numbers in recurrent carcinoma in 120 kVp-equivalent images in venous phase were significantly higher, too (74HU vs 47HU, p = 0.002). ROC-curve analysis for iodine concentrations in early venous phase suggests a cut-off value of ≥ 1.55 mg/ml for local recurrence (AUC = 0.78, specificity = 1.0, sensitivity = 0.53) and for CT numbers in 120kVp-equivalent images a cut-off value of ≥ 57HU (AUC = 0.82, specificity = 0.82, sensitivity = 0.71).

CONCLUSION

In difficult cases, measuring iodine concentrations or CT numbers in PSF in (early) venous phase DECT could be a valuable additional parameter for differentiating local recurrence from non-specific PSF.

The Heterogeneity of the Tumor Microenvironment as Essential Determinant of Development, Progression and Therapy Response of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is commonly diagnosed at advanced stages and most anti-cancer therapies have failed to substantially improve prognosis of PDAC patients. As a result, PDAC is still one of the deadliest tumors. Tumor heterogeneity, manifesting at multiple levels, provides a conclusive explanation for divergent survival times and therapy responses of PDAC patients. Besides tumor cell heterogeneity, PDAC is characterized by a pronounced inflammatory stroma comprising various non-neoplastic cells such as myofibroblasts, endothelial cells and different leukocyte populations which enrich in the tumor microenvironment (TME) during pancreatic tumorigenesis. Thus, the stromal compartment also displays a high temporal and spatial heterogeneity accounting for diverse effects on the development, progression and therapy responses of PDAC. Adding to this heterogeneity and the impact of the TME, the microbiome of PDAC patients is considerably altered. Understanding this multi-level heterogeneity and considering it for the development of novel therapeutic concepts might finally improve the dismal situation of PDAC patients. Here, we outline the current knowledge on PDAC cell heterogeneity focusing on different stromal cell populations and outline their impact on PDAC progression and therapy resistance. Based on this information, we propose some novel concepts for treatment of PDAC patients.

Proteogenomic characterization of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with poor patient survival. Toward understanding the underlying molecular alterations that drive PDAC oncogenesis, we conducted comprehensive proteogenomic analysis of 140 pancreatic cancers, 67 normal adjacent tissues, and 9 normal pancreatic ductal tissues. Proteomic, phosphoproteomic, and glycoproteomic analyses were used to characterize proteins and their modifications. In addition, whole-genome sequencing, whole-exome sequencing, methylation, RNA sequencing (RNA-seq), and microRNA sequencing (miRNA-seq) were performed on the same tissues to facilitate an integrated proteogenomic analysis and determine the impact of genomic alterations on protein expression, signaling pathways, and post-translational modifications. To ensure robust downstream analyses, tumor neoplastic cellularity was assessed via multiple orthogonal strategies using molecular features and verified via pathological estimation of tumor cellularity based on histological review. This integrated proteogenomic characterization of PDAC will serve as a valuable resource for the community, paving the way for early detection and identification of novel therapeutic targets.

Firing up the Tumor Microenvironment with Nanoparticle-Based Therapies

Therapies mobilizing host immunity against cancer cells have profoundly improved prognosis of cancer patients. However, efficacy of immunotherapies depends on local immune conditions. The "cold" tumor, which is characterized by lacking inflamed T cells, is insensitive to immunotherapy. Current strategies of improving the "cold" tumor microenvironment are far from satisfying. Nanoparticle-based therapies provide novel inspiration in firing up the tumor microenvironment. In this review, we presented progress and limitations of conventional immunotherapies. Then, we enumerate advantages of nanoparticle-based therapies in remodeling the "cold" tumor microenvironment. Finally, we discuss the prospect of nanoparticle-based therapies in clinical application.

Important role of Nfkb2 in the KrasG12D-driven carcinogenesis in the pancreas

BACKGROUND

Oncogenic Kras initiates and drives carcinogenesis in the pancreas by complex signaling networks, including activation of the NFκB pathway. Although recent evidence has shown that oncogenic gains in Nfκb2 collaborate with Kras in the carcinogenesis, no data at the level of genetics for the contribution of Nfκb2 is available so far.

METHODS

We used Nfkb2 knock-out mice to decipher the role of the gene in Kras-driven carcinogenesis in vivo.

RESULTS

We show that the Nfkb2 gene is needed for cancer initiation and progression in Kras^G12D-driven models and this requirement of Nfkb2 is mechanistically connected to proliferative pathways. In contrast, Nfκb2 is dispensable in aggressive pancreatic ductal adenocarcinoma (PDAC) models relying on the simultaneous expression of the Kras oncogene and the mutated tumor suppressor p53.

CONCLUSIONS

Our data add to the understanding of context-dependent requirements of oncogenic Kras signaling during pancreatic carcinogenesis.

3D heterospecies spheroids of pancreatic stroma and cancer cells demonstrate key phenotypes of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, partly due to the dense desmoplasia and a lack of suitable model systems to study. In the present work, we developed a 3D heterospecies spheroid model to study the microenvironmental interactions between tumor cells and stellate cells which can also be employed to test therapeutic regimens. We set up monospheroids and heterospheroids made up from murine pancreatic stellate cells (mPSCs) and human PDAC cells (Panc1), which allowed for direct isolation of mRNA from a mixed cell population followed by an in silico separation of the RNA-seq reads. Global transcript level changes for cells in heterospheroids versus monospheroids were calculated, followed by gene set enrichment analysis and molecular subtype analysis. We observed an apparent shift of Panc1 from the classical to the squamous/basal-like phenotype upon co-culture with mPSCs. Moreover, mPSCs acquired a different cancer-associated fibroblast-related phenotype upon co-culture with Panc1. We analyzed the tumor cell-specific chemosensitivities towards gemcitabine, paclitaxel and SN38 and compared these to published pharmacotranscriptomic signatures. In conclusion, our heterospecies spheroid model reflected key aspects of PDAC and facilitated the study of intercellular interactions between tumor and stroma while additionally proving to be a good model for studying therapeutic responses.

A quantitative score of immune cell infiltration predicts the prognosis in pancreatic ductal adenocarcinoma

Pancreatic Ductal Adenocarcinoma (PDAC) is characterized by an extensive and dense fibrous stroma, which plays an active role in tumor growth and metastasis. Despite the growing importance of the tumor microenvironment in PDAC prognosis, the immune cell infiltration landscape of PDAC has not been elucidated. In this study, we applied a credible computational algorithm to comprehensively estimate the immune cell infiltration (ICI) patterns of 876 PDAC patients. Two ICI phenotypes were identified, and a ICIscore was constructed using ssGSEA algorithm. The ICIscore could significantly predict the prognosis and chemotherapy benefit of PDAC patients in both the discovery and the five validation cohorts. Multivariate cox analysis also identified the independent predictive role of the ICIscore in PDAC prognosis. A high ICIscore subtype was characterized by immune-active signaling pathways and anti-tumor immunity while a low ICIscore subtype was associated with tumor progressive signaling pathways. Four immunotherapy cohorts further supported the use of the ICIscore as a prognostic biomarker for patients receiving immune checkpoint inhibitors in other cancer types. The ICIscore reveals a close relationship between the ICI environment and prognosis and may provide new treatment strategies for PDAC patients.

Delta HU is a potential marker to predict chemotherapy response for unresectable pancreatic ductal adenocarcinoma

BACKGROUND

FOLFIRINOX and gemcitabine plus albumin-bound paclitaxel (AG) regimens are recommended as first-line therapy for both locally advanced and metastatic pancreatic cancer. However, there were no specific markers to conduct personalized regimen choice. The research is to assess delta Housfield unit (delta HU), which is the difference in CT attenuation value (in HU) between enhanced and nonenhanced phase of region of interest, as a marker for predicting chemotherapy response of unresectable pancreatic cancer.

METHODS

A total of 179 unresectable pancreatic cancer patients were enrolled in the study. Kaplan-Meier analysis and COX regression analysis were performed for progression-free survival (PFS) and overall survival. The differences of clinical characteristics were analyzed by χ 2test. Microvessel density (MVD) was calculated by immunochemistry staining of CD34.

RESULTS

Delta HU was an independent risk factor for unresectable pancreatic cancer (P = 0.017, HR 0.672, 95%CI 0.485-0.930). Patients with higher delta HU were associated with better PFS (P = 0.004). For modified FOLFIRINOX (mFOLFIRINOX) group, delta HU was an independent risk factor (P = 0.045, HR 0.571), but not for AG group (P = 0.473, HR 0.855). Delta HU was correlated with stroma MVD (P = 0.000, R = 0.483), not with parenchyma MVD (P = 0.074, R = 0.199).

CONCLUSIONS

Delta HU was a marker predicting chemotherapy response for unresectable pancreatic cancer. Higher delta HU was associated with better survival for patients receiving mFOLFIRINOX rather than AG. The delta HU was positively correlated with stroma MVD, explaining the relationship between delta HU and prognosis.

Tumor restriction by type I collagen opposes tumor-promoting effects of cancer-associated fibroblasts

Cancer-associated fibroblasts (CAF) may exert tumor-promoting and tumor-suppressive functions, but the mechanisms underlying these opposing effects remain elusive. Here, we sought to understand these potentially opposing functions by interrogating functional relationships among CAF subtypes, their mediators, desmoplasia, and tumor growth in a wide range of tumor types metastasizing to the liver, the most common organ site for metastasis. Depletion of hepatic stellate cells (HSC), which represented the main source of CAF in mice and patients in our study, or depletion of all CAF decreased tumor growth and mortality in desmoplastic colorectal and pancreatic metastasis but not in nondesmoplastic metastatic tumors. Single-cell RNA-Seq in conjunction with CellPhoneDB ligand-receptor analysis, as well as studies in immune cell-depleted and HSC-selective knockout mice, uncovered direct CAF-tumor interactions as a tumor-promoting mechanism, mediated by myofibroblastic CAF-secreted (myCAF-secreted) hyaluronan and inflammatory CAF-secreted (iCAF-secreted) HGF. These effects were opposed by myCAF-expressed type I collagen, which suppressed tumor growth by mechanically restraining tumor spread, overriding its own stiffness-induced mechanosignals. In summary, mechanical restriction by type I collagen opposes the overall tumor-promoting effects of CAF, thus providing a mechanistic explanation for their dual functions in cancer. Therapeutic targeting of tumor-promoting CAF mediators while preserving type I collagen may convert CAF from tumor promoting to tumor restricting.

PERK-eIF2α-ERK1/2 axis drives mesenchymal-endothelial transition of cancer-associated fibroblasts in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterized by remarkable desmoplasia, usually driven by cancer-associated fibroblasts (CAFs), influencing patient prognosis. CAFs are a group of plastic cells responsible for tumor growth and metastasis. Fibroblasts have been reported to directly contribute to angiogenesis by undergoing mesenchymal-endothelial transition (MEndoT) after ischemic injury in the heart, brain, and hindlimbs. However, whether CAFs can undergo similar transdifferentiation in the hostile tumor microenvironment and directly contribute to tumor angiogenesis remains unclear. Herein, we provide evidence that CAFs can adopt an endothelial cell-like phenotype and directly contribute to tumor angiogenesis in vitro and in vivo. Furthermore, this program is regulated by the PERK-eIF2α-ERK1/2 axis. Pharmacological inhibition of PERK with GSK2606414 limited the phenotypic transition of CAFs. In conclusion, our results suggest that CAFs contribute to tumor angiogenesis by undergoing the MEndoT, thus representing therapeutic targets for improving PDAC prognosis.

Comprehensive analysis of clinical prognosis and molecular immune characterization of tropomyosin 4 in pancreatic cancer

Pancreatic cancer (PC) is one of the most lethal human solid malignancies with devastating prognosis, making biomarker detection considerably important. Immune infiltrates in microenvironment is associated with patients' survival in PC. The role of Tropomyosin 4 (TPM4) gene in PC has not been reported. Our study first identifies TPM4 expression and its potential biological functions in PC. The potential oncogenic roles of TPM4 was examined using the datasets of TCGA (The cancer genome atlas) and GEO (Gene expression omnibus). We investigated the clinical significance and prognostic value of TPM4 gene based on The Gene Expression Profiling Interactive Analysis (GEPIA) and survival analysis. TIMER and TISIDB databases were used to analyze the correlations between TPM4 gene and tumor-infiltrating immune cells. We found that the expression level of TPM4 was upregulated in PC malignant tissues with the corresponding normal tissues as controls. High TPM4 expression was correlated with the worse clinicopathological features and poor prognosis in PC cohorts. The positive association between TPM4 expression and tumor-infiltrating immune cells was identified in tumor microenvironment (TME). Moreover, functional enrichment analysis suggested that TPM4 might participate in cell adhesion and promote tumor cell migration. This is the first comprehensive study to disclose that TPM4 may serve as a novel prognostic biomarker associating with immune infiltrates and provide a potential therapeutic target for the treatment of PC.

[The microarchitecture of pancreatic cancer from the point of view of the pathologist and the radiologist]

Die diagnostische Radiologie ist gemeinsam mit der diagnostischen Pathologie eines der klinisch-morphologischen Fächer, welche in unterschiedlicher makroskopischer bzw. mikroskopischer Auflösung zur Detektion, Charakterisierung sowie zum Ausbreitungsmuster eines Tumors führen. Die klinischen Disziplinen sind oft voneinander getrennt, wenngleich es vor allem in klinischen Tumorboards immer stärkere Verzahnungen gibt. Am Beispiel des Pankreaskarzinoms sind die Korrelationen radiologischer und pathologischer Diagnostik dargestellt.

Pancreatic cancer is suppressed by fibroblast-derived collagen I

Clinical implementation of anti-stromal therapies in pancreatic cancer has been delayed by unanticipated tumor-restraining properties of the desmoplastic stroma. In confronting these challenges, Chen et al. demonstrate in this issue of Cancer Cell that fibroblast-specific deletion of collagen I, in the background of oncogenic Kras-induced spontaneous murine pancreatic ductal adenocarcinoma, enhances immune suppression and accelerates progression of disease.

Cancer-associated fibroblasts-mediated ATF4 expression promotes malignancy and gemcitabine resistance in pancreatic cancer via the TGF-β1/SMAD2/3 pathway and ABCC1 transactivation

Cancer-associated fibroblasts (CAFs) contribute to malignant progression and chemoresistance in pancreatic ductal adenocarcinoma (PDAC). However, little is known about the underlying mechanism. In this study, we investigated the potential role and mechanisms of activating transcription factor 4 (ATF4) in CAFs-induced malignancy and gemcitabine resistance. We demonstrated that ATF4 is overexpressed in PDAC and associated with a poor prognosis. Silencing ATF4 expression decreased proliferation, colony formation, migration, gemcitabine sensitivity, and sphere formation. Subsequently, we revealed that CAFs secrete TGF-β1 to upregulate the expression of ATF4 in PDAC cells via the SMAD2/3 pathway and induce cancer progression, cancer stemness, and gemcitabine resistance. Furthermore, we demonstrated that ATF4 directly binds to the ABCC1 promoter region to activate transcription. In summary, these data demonstrate that CAFs contribute to malignancy and gemcitabine resistance in PDAC by upregulating the expression of ATF4 via the TGF-β1/SMAD2/3 axis and highlight that ATF4 is an attractive therapeutic target for combating gemcitabine resistance in PDAC.

Identification of tumor antigens and immune subtypes of pancreatic adenocarcinoma for mRNA vaccine development

BACKGROUND

Although mRNA vaccines have been effective against multiple cancers, their efficacy against pancreatic adenocarcinoma (PAAD) remains undefined. Accumulating evidence suggests that immunotyping can indicate the comprehensive immune status in tumors and their immune microenvironment, which is closely associated with therapeutic response and vaccination potential. The aim of this study was to identify potent antigens in PAAD for mRNA vaccine development, and further distinguish immune subtypes of PAAD to construct an immune landscape for selecting suitable patients for vaccination.

METHODS

Gene expression profiles and clinical information of 239 PAAD datasets were extracted from ICGC, and RNA-Seq data of 103 samples were retrieved from TCGA. GEPIA was used to calculate differential expression levels and prognostic indices, cBioPortal program was used to compare genetic alterations, and TIMER was used to explore correlation between genes and immune infiltrating cells. Consensus cluster was used for consistency matrix construction and data clustering, DAVID was used for functional annotation, and graph learning-based dimensional reduction was used to depict immune landscape.

RESULTS

Six overexpressed and mutated tumor antigens associated with poor prognosis and infiltration of antigen presenting cells were identified in PAAD, including ADAM9, EFNB2, MET, TMOD3, TPX2, and WNT7A. Furthermore, five immune subtypes (IS1-IS5) and nine immune gene modules of PAAD were identified that were consistent in both patient cohorts. The immune subtypes showed distinct molecular, cellular and clinical characteristics. IS1 and IS2 exhibited immune-activated phenotypes and correlated to better survival compared to the other subtypes. IS4 and IS5 tumors were immunologically cold and associated with higher tumor mutation burden. Immunogenic cell death modulators, immune checkpoints, and CA125 and CA199, were also differentially expressed among the five immune subtypes. Finally, the immune landscape of PAAD showed a high degree of heterogeneity between individual patients.

CONCLUSIONS

ADAM9, EFNB2, MET, TMOD3, TPX2, and WNT7A are potent antigens for developing anti-PAAD mRNA vaccine, and patients with IS4 and IS5 tumors are suitable for vaccination.

CXCL10 is a Tumor Microenvironment and Immune Infiltration Related Prognostic Biomarker in Pancreatic Adenocarcinoma

Pancreatic adenocarcinoma (PAAD) is the 10th most common cancer worldwide and the outcomes for patients with the disease remain extremely poor. Precision biomarkers are urgently needed to increase the efficiency of early diagnosis and to improve the prognosis of patients. The tumor microenvironment (TME) and tumor immune infiltration are thought to impact the occurrence, progression, and prognosis of PAAD. Novel biomarkers excavated originating from the TME and immune infiltration may be effective in predicting the prognosis of PAAD patients. In the current study, the ESTIMATE and CIBERSORT algorithms were applied to estimate the division of immune and stromal components and the proportion of tumor-infiltrating immune cells in 182 PAAD cases downloaded from The Cancer Genome Atlas database. Intersection analyses of the Protein-Protein Interaction networks and Cox regression analysis identified the chemokine (CXC-motif) ligand 10 (CXCL10) as a predictive biomarker. We verified that CXCL10 in the TME negatively correlates with prognosis in PAAD and positively correlates with tumor cell differentiation. GSE62452 from the GEO database and cumulative survival analysis were performed to validate CXCL10 expression as an independent prognostic indicator. We also found that memory B cells, regulatory T cells, and macrophages M0 and M1 were correlated with the expression of CXCL10 indicating that expression of CXCL10 influenced the immune activity of the TME. Our data suggest that CXCL10 is beneficial as a prognostic indicator in PAAD patients and highlights the potential for immune targeted therapy in the treatment of PAAD.

Effect of Glucose Variability on Pancreatic Cancer Through Regulation of COL6A1

Background

Pancreatic cancer (PC), a devastating cancer worldwide, remains dismal prognosis due to its clinical elusiveness, especially in relation to diabetes mellitus (DM). The study aims to investigate the effect of glucose variability on COL6A1 in PC cancer cells and the prognostic potential of COL6A1 for PC patient associated with DM.

Methods

After PC cancer cell lines of AsPC-1 and BxPC-3 were treated with hyperglycemia and hypoglycemia, Giemsa staining and Transwell chamber were performed to assay plate clone formation, migration and invasion. Expressions of COL6A1 of PC cancer cell lines under different extracellular glucose levels were detected by qRT-PCR and Western blotting. The level of COL6A1 expression in PC patients with/without DM was further observed with immunohistochemistry. The prognostic impact of COL6A1 on PC patients with DM was assessed by Kaplan–Meier survival curve analysis.

Results

Hyperglycemia promoted proliferation, migration and invasion of PC cancer cells compared with hypoglycemia. Glucose variability could regulate expression of COL6A1 in PC cancer cells, both Col6a1 mRNA and COL6A1 protein upregulated in cancer cells cultured with hyperglycemic than that with hypoglycemic. The level of COL6A1 expression was higher in PC patients with DM than that without DM. Besides, COL6A1 was significantly associated with the clinical prognosis of PC patients with DM, higher COL6A1 leading to lower overall survival (OS).

Conclusion

Glucose variability had effect on PC cancer cells through regulation of COL6A1. Accordingly, COL6A1 was associated with poorer prognosis in PC patients with DM.