Regulatory T-cell Depletion Alters the Tumor Microenvironment and Accelerates Pancreatic Carcinogenesis

Pancreatic cancer precursor lesions - Can immunotherapy prevent progression into pancreatic ductal adenocarcinoma?

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers, with a 5-year survival rate of only 12.5 %. Early detection of PDAC or addressing risk factors for PDAC development are ways to improve outcomes. PDAC can arise from precursor lesions, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and less frequent, mucinous cystic neoplasm (MCN), and other rare precursor variants. High-risk precursor lesions harbor a substantial chance of evolving into PDAC. Such lesions can often be found in resected PDAC specimens adjacent to the cancer. Unfortunately, recognizing precursor lesions that need to be resected is often tricky, and resections frequently end in major surgical interventions. Thus, better ways to handle precursor lesions are desperately needed. We mapped the immune microenvironments (IMEs) of PanINs, IPMNs, and MCNs on a cellular level using multiplex immunofluorescence and computational imaging technology and compared the findings to PDACs and normal pancreatic tissues. We found distinct and potentially targetable mechanisms of immunosuppression between the two main precursor lesions, PanIN and IMPN. Immunosuppression in IPMNs seems partly mediated by programmed cell death protein 1 ligand (PD-L1) expression on antigen-presenting cells (APCs). By contrast, elevated numbers of regulatory T cells (Tregs) seem to be key players in the immunosuppression of PanINs. Thus, treating high-risk IPMNs with anti-PD-1 and high-risk PanINs with agents targeting Tregs, such as anti-lymphocyte associated protein 4 (anti-CTLA-4) antibodies, could reverse their immunosuppressive state. Reversal of immunosuppression will restore immunosurveillance and eventually prevent progression into PDAC. We also review relevant published and ongoing non-surgical treatment approaches for high-risk IPMNs and PanINs.

MCT4 is an independent prognostic factor and affects immune cell infiltration in patients with colorectal liver oligometastases

BACKGROUND

Monocarboxylate transporter 4 (MCT4) is a novel biomarker related to the level of immune cell infiltration, but its impact on tumor immune microenvironment (TIME) of colorectal liver oligometastases (CLO) remains unclear. The aim of this study was to assess MCT4 expression in primary tumor and liver oligometastases, investigate its impact on immune cell infiltration and its prognostic value for CLO patients undergoing liver resection.

METHODS

We retrospectively selected 135 CLO patients who underwent curative liver resection between June 1999 and December 2016, and samples included 74 primary tumor tissues and 122 liver metastases. Immunohistochemistry (IHC) was performed to detect MCT4 expression in paraffin-embedded specimens and tyramine signal amplification (TSA) was used to detect the density of tumor-infiltrating lymphocytes, including CD3 + , CD8 + and Foxp3 + . Recurrence-free survival (RFS) and overall survival (OS) were analyzed using the Kaplan-Meier method and log-rank test, and independent prognostic factors were identified with Cox regression modeling.

RESULTS

Survival analysis indicated that CLO patients with low MCT4 expression had better 3-year RFS and 3-year OS rates than those with high MCT4 expression. Multivariate analysis indicated that high MCT4 expression was independently associated with poor RFS and OS. High MCT4 expression was associated with a lower number of intratumoral CD3 + /CD8 + T cells and was associated with higher Foxp3 + T cells infiltration. Patients with low MCT4 expression and high levels of differential immune infiltration had longer survival.

CONCLUSIONS

MCT4 overexpression was associated with an unfavorable prognosis in patients with CLO and MCT4 expression level had an impact on intratumoral immune infiltration degree. A novel parameter that combined MCT4 expression level and differential immune infiltration level was constructed to stratify patients with CLO into different risk groups.

The tumor microenvironment is an ecosystem sustained by metabolic interactions

Cancer-associated fibroblasts (CAFs) and immune cells make up two major components of the tumor microenvironment (TME), contributing to an ecosystem that can either support or restrain cancer progression. Metabolism is a key regulator of the TME, providing a means for cells to communicate with and influence each other, modulating tumor progression and anti-tumor immunity. Cells of the TME can metabolically interact directly through metabolite secretion and consumption or by influencing other aspects of the TME that, in turn, stimulate metabolic rewiring in target cells. Recent advances in understanding the subtypes and plasticity of cells in the TME both open up new avenues and create challenges for metabolically targeting the TME to hamper tumor growth and improve response to therapy. This perspective explores ways in which the CAF and immune components of the TME could metabolically influence each other, based on current knowledge of their metabolic states, interactions, and subpopulations.

CXCR2P1 enhances the response of gastric cancer to PD-1 inhibitors through increasing the immune infiltration of tumors

Background

Recent years, immunotherapy has emerged as a pivotal approach in cancer treatment. However, the response of gastric cancer to immunotherapy exhibits significant heterogeneity. Therefore, the early identification of gastric cancer patients who are likely to benefit from immunotherapy and the discovery of novel therapeutic targets are of critical importance.

Materials and methods

We collected data from European Nucleotide Archive (ENA) and Gene Expression Omnibus (GEO) databases. In project PRJEB25780, we performed WGCNA analysis and Lasso regression and chose CXCR2P1 for the subsequent analysis. Then, we compared the expression difference of CXCR2P1 among different groups. Kaplan-Meier curve was used to analyze the prognostic value of CXCR2P1, which was validated by project IMvigor210 and GEO datasets. ESTIMATE and CIBERSORT algorithm were used to evaluate the reshaping effect of CXCR2P1 to immune microenvironment of tumor. Differentially expressed genes (DEG) analysis, enrichGO analysis, Gene Set Enrichment Analysis (GSEA) and co-expression analysis were used to explore the cell biological function and signaling pathway involved in CXCR2P1.

Results

WGCNA identified CXCR2P1 as a hub gene significantly associated with immune response to PD-1 inhibitors in gastric cancer. CXCR2P1 expression was elevated in responders and correlated with better prognosis. Functional analysis revealed its role in reshaping the tumor immune microenvironment by promoting immune cell infiltration, including M1 macrophages, activated CD4+ T cells, and follicular helper T cells. CXCR2P1 enhanced antigen presentation via the MHC-II complex, influenced key immune pathways, such as Toll-like receptor signaling and T-cell activation, which led to the up-regulation of expression of PD-L1. GSEA showed CXCR2P1 were correlated with microRNAs. Through DEG analysis and expression analysis, MIR215 was identified as a potential direct target of CXCR2P1.

Conclusion

High expression of CXCR2P1 is correlated with better response to PD-1 inhibitor. It reshapes the immune microenvironment by increasing immune infiltration and changing the fraction of immune cells. In tumor immune microenvironment, CXCR2P1 can promote inflammation, enhance antigen presentation and activate the PD-1/PD-L1-related signaling pathway, which might be achieved by CXCR2P1-MIR215 axis.

Elevated Lactate in the AML Bone Marrow Microenvironment Polarizes Leukemia-Associated Macrophages via GPR81 Signaling

Interactions between acute myeloid leukemia (AML) and the bone marrow microenvironment (BMME) are critical to leukemia progression and chemoresistance. In the solid tumor microenvironment, altered metabolite levels contribute to cancer progression. We performed a metabolomic analysis of AML patient bone marrow serum, revealing increased metabolites compared to age- and sex-matched controls. The most highly elevated metabolite in the AML BMME was lactate. Lactate signaling in solid tumors induces immunosuppressive tumor-associated macrophages and correlates with poor prognosis. This has not yet been studied in the leukemic BMME. Herein, we describe the role of lactate in the polarization of leukemia-associated macrophages (LAMs). Using a murine AML model of blast crisis chronic myelogenous leukemia (bcCML), we characterize the suppressive phenotype of LAMs by surface markers, transcriptomics, and cytokine profiling. Then, mice genetically lacking GPR81, the extracellular lactate receptor, were used to demonstrate GPR81 signaling as a mechanism of both the polarization of LAMs and the direct support of leukemia cells. Furthermore, elevated lactate diminished the function of hematopoietic progenitors and reduced stromal support for normal hematopoiesis. We report microenvironmental lactate as a mechanism of AML-induced immunosuppression and leukemic progression, thus identifying GPR81 signaling as an exciting and novel therapeutic target for treating this devastating disease.

Mechanical Forces in Tumor Growth and Treatment: Perspectives From Biology, Physics, Engineering, and Mathematical Modeling

The progression of tumors is influenced by mechanical forces and biological elements, such as hypoxia and angiogenesis. Mechanical factors, including stress, pressure, interstitial fluid pressure, and cellular traction forces, compromise normal tissue architecture, augmenting stiffness and thus promoting tumor growth and invasion. The selective elimination of specific tumor components can reduce growth-induced mechanical stress, thereby improving therapeutic efficacy. Furthermore, stress-relief drugs have the potential in enhancing chemotherapy outcomes. In this setting, computational modeling functions as an essential tool for quantitatively elucidating the mechanical principles underlying tumor formation. These models can precisely replicate the impact of mechanical pressures on solid tumors, offering insight into the regulation of tumor behavior by these forces. Tumor growth produces mechanical forces, including compression, displacement, and deformation, leading to irregular stress patterns, expedited tumor advancement, and reduced treatment efficacy. This review analyzes the impact of mechanical forces on carcinogenesis and solid tumor proliferation, emphasizing the significance of stress alleviation in regulating tumor growth. Furthermore, we investigate the influence of mechanical forces on tumor dissemination and emphasize the promise of integrating computational modeling with force-targeted cancer therapies to improve treatment efficacy by tackling the fundamental mechanics of tumor proliferation.

Threading the Needle: Navigating Novel Immunotherapeutics in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with a poor prognosis. Currently, chemotherapy is the only option for most patients with advanced-stage PDAC. Further, conventional immunotherapies and targeted therapies improve survival outcomes only in rare PDAC patient subgroups. To date, combinatory immunotherapeutic strategies to overcome the immune-hostile PDAC tumor microenvironment (TME) have resulted in limited efficacy in clinical studies. However, efforts are ongoing to develop new treatment strategies for patients with PDAC with the evolving knowledge of the TME, molecular characterization, and immune resistance mechanisms. Further, the growing arsenal of various immunotherapeutic agents, including novel classes of immune checkpoint inhibitors and oncolytic, chimeric antigen receptor T cell, and vaccine therapies, reinforces these efforts. This review will focus on the place of immunotherapy and future possible strategies in PDAC.

Distinct immune cell infiltration patterns in pancreatic ductal adenocarcinoma (PDAC) exhibit divergent immune cell selection and immunosuppressive mechanisms

Pancreatic ductal adenocarcinoma has a dismal prognosis. A comprehensive analysis of single-cell multi-omic data from matched tumour-infiltrated CD45+ cells and peripheral blood in 12 patients, and two published datasets, reveals a complex immune infiltrate. Patients have either a myeloid-enriched or adaptive-enriched tumour microenvironment. Adaptive immune cell-enriched is intrinsically linked with highly distinct B and T cell clonal selection, diversification, and differentiation. Using TCR data, we see the largest clonal expansions in CD8 effector memory, senescent cells, and highly activated regulatory T cells which are induced within the tumour from naïve cells. We identify pathways that potentially lead to a suppressive microenvironment, including investigational targets TIGIT/PVR and SIRPA/CD47. Analysis of patients from the APACT clinical trial shows that myeloid enrichment had a shorter overall survival compared to those with adaptive cell enrichment. Strategies for rationale therapeutic development in this disease include boosting of B cell responses, targeting immunosuppressive macrophages, and specific Treg cell depletion approaches.

Turning cold into hot: emerging strategies to fire up the tumor microenvironment

The tumor microenvironment (TME) is a complex, highly structured, and dynamic ecosystem that plays a pivotal role in the progression of both primary and metastatic tumors. Precise assessment of the dynamic spatiotemporal features of the TME is crucial for understanding cancer evolution and designing effective therapeutic strategies. Cancer is increasingly recognized as a systemic disease, influenced not only by the TME, but also by a multitude of systemic factors, including whole-body metabolism, gut microbiome, endocrine signaling, and circadian rhythm. In this review, we summarize the intrinsic, extrinsic, and systemic factors contributing to the formation of 'cold' tumors within the framework of the cancer-immunity cycle. Correspondingly, we discuss potential strategies for converting 'cold' tumors into 'hot' ones to enhance therapeutic efficacy.

LIM domain only 7: a novel driver of immune evasion through regulatory T cell differentiation and chemotaxis in pancreatic ductal adenocarcinoma

With advancements in genomics and immunology, immunotherapy has emerged as a revolutionary strategy for tumor treatment. However, pancreatic ductal adenocarcinoma (PDAC), an immunologically "cold" tumor, exhibits limited responsiveness to immunotherapy. This study aimed to address the urgent need to uncover PDAC's immune microenvironment heterogeneity and identify the molecular mechanisms driving immune evasion. Using single-cell RNA sequencing datasets and spatial proteomics, we discovered LIM domain only 7 (LMO7) in PDAC cells as a previously unrecognized driver of immune evasion through Treg cell enrichment. LMO7 was positively correlated with infiltrating regulatory T cells (Tregs) and dysfunctional CD8+ T cells. A series of in vitro and in vivo experiments demonstrated LMO7's significant role in promoting Treg cell differentiation and chemotaxis while inhibiting CD8+ T cells and natural killer cell cytotoxicity. Mechanistically, LMO7, through its LIM domain, directly bound and promoted the ubiquitination and degradation of Foxp1. Foxp1 negatively regulated transforming growth factor-beta (TGF-β) and C-C motif chemokine ligand 5 (CCL5) expression by binding to sites 2 and I/III, respectively. Elevated TGF-β and CCL5 levels contribute to Treg cell enrichment, inducing immune evasion in PDAC. Combined treatment with TGF-β/CCL5 antibodies, along with LMO7 inhibition, effectively reversed immune evasion in PDAC, activated the immune response, and prolonged mouse survival. Therefore, this study identified LMO7 as a novel facilitator in driving immune evasion by promoting Treg cell enrichment and inhibiting cytotoxic effector functions. Targeting the LMO7-Foxp1-TGF-β/CCL5 axis holds promise as a therapeutic strategy for PDAC. Graphical abstract revealing LMO7 as a novel facilitator in driving immune evasion by promoting Tregs differentiation and chemotaxis, inducing CD8+ T/natural killer cells inhibition.

TGF-β signaling orchestrates cancer-associated fibroblasts in the tumor microenvironment of human hepatocellular carcinoma: unveiling insights and clinical significance

Liver cancer, specifically hepatocellular carcinoma (HCC), stands out as one of the most formidable solid tumors, characterized by a dauntingly low survival rate. At the forefront of the tumor microenvironment (TME) orchestrating the initiation and advancement of HCC are cancer-associated fibroblasts (CAFs). TGF-β, widely recognized as a potent activator of CAFs, not only regulates their activity but also assumes a pivotal role in the metastatic journey of the tumor. In our recent study, drawing from the GEO database, we identified two fibroblast subtypes in HCC through single-cell RNA sequencing (scRNA-seq) and explore the expression and distribution of TGF-β and its receptors in the TME of HCC. Subsequently, we investigated the interactions between tumor cells expressing high levels (TGFB1high) and low levels (TGFB1low) of TGF-β in the HCC TME and the two subtypes of CAFs. We also employed multi-color immunohistochemistry (mIHC) technology to examine the expressions of FAP, α-SMA, CD4, Foxp3, and TGF-β in HCC tissues within a tissue microarray. Additionally, we analyzed clinical associations, prognostic values, and the correlation of these molecules. These insights advance our understanding of the molecular mechanisms driving HCC progression and underscore the intricate interplay between tumor cells and the stromal components of the TME.

Cytokines in cancer

Cytokines are proteins used by immune cells to communicate with each other and with cells in their environment. The pleiotropic effects of cytokine networks are determined by which cells express cytokines and which cells express cytokine receptors, with downstream outcomes that can differ based on cell type and environmental cues. Certain cytokines, such as interferon (IFN)-γ, have been clearly linked to anti-tumor immunity, while others, such as the innate inflammatory cytokines, promote oncogenesis. Here we provide an overview of the functional roles of cytokines in the tumor microenvironment. Although we have a sophisticated understanding of cytokine networks, therapeutically targeting cytokine pathways in cancer has been challenging. We discuss current progress in cytokine blockade, cytokine-based therapies, and engineered cytokine therapeutics as emerging cancer treatments of interest.

Genetics and biology of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) poses a grim prognosis for patients. Recent multidisciplinary research efforts have provided critical insights into its genetics and tumor biology, creating the foundation for rational development of targeted and immune therapies. Here, we review the PDAC genomic landscape and the role of specific oncogenic events in tumor initiation and progression, as well as their contributions to shaping its tumor biology. We further summarize and synthesize breakthroughs in single-cell and metabolic profiling technologies that have illuminated the complex cellular composition and heterotypic interactions of the PDAC tumor microenvironment, with an emphasis on metabolic cross-talk across cancer and stromal cells that sustains anabolic growth and suppresses tumor immunity. These conceptual advances have generated novel immunotherapy regimens, particularly cancer vaccines, which are now in clinical testing. We also highlight the advent of KRAS targeted therapy, a milestone advance that has transformed treatment paradigms and offers a platform for combined immunotherapy and targeted strategies. This review provides a perspective summarizing current scientific and therapeutic challenges as well as practice-changing opportunities for the PDAC field at this major inflection point.

Parkin modulates the hepatocellular carcinoma microenvironment by regulating PD-1/PD-L1 signalling

INTRODUCTION

Parkin-mediated mitophagy is essential for clearing damaged mitochondria, and it inhibits tumour development. The role of mitophagy in modulating tumour immunity is becoming clearer, but the underlying mechanism is still poorly understood.

OBJECTIVE

This study was designed to examine the role of Parkin in the immune microenvironment of liver tumours induced by carbon tetrachloride (CCl4).

METHODS

Single-cell RNA sequencing analysis, Western blot, immunofluorescence and co-immunoprecipitation were used to verify the mechanism of Parkin affecting the tumour microenvironment by altering the expression of PD-1.

RESULTS

Our data revealed that Park2-/- mice showed severe liver damage and increased malignancy. Single-cell RNA sequencing analysis of T lymphocytes in liver tumours showed that the number of cytotoxic CD8+ T cells (Gzmb/Ifng/Fasl) was significantly decreased and the number of exhausted CD8+ T cells (Pdcd1/Lag3/Tigit/Havcr2/Ctla4) was significantly increased in Park2-/- mice, indicating the immune suppressive microenvironment. Single-cell RNA sequencing analysis of myeloid-derived cells also displayed the increase of M2-like macrophages in Park2-/- mice. Through quantitative proteomic analysis, it was found that the differential protein expression between the two groups mainly localized in the plasma membrane and extracellular, including PD-1, MHC-Ⅰ molecules etc., and was mainly associated with PD-1 and antigen presentation pathways. It could impair the antitumour immune response with Parkin deficiency. Parkin deficiency leads to the decrease of hepatic mitophagy levels and the formation of an immune suppressive microenvironment, which promotes the tumourigenesis of liver cancer.

CONCLUSION

As an E3 ubiquitin ligase, Parkin induces the ubiquitination and degradation of PD-1 in liver cancer and could influence antitumour immunity through the PD-1/PD-L1 signalling pathway. Thus, remodeling the tumour microenvironment through the reintroduction of Parkin or enhancement of mitophagy could activate the anti-tumour immune response and improve the immunotherapy efficacy, which may be a promising strategy for the treatment of HCC.

Ex-Vivo 3D Cellular Models of Pancreatic Ductal Adenocarcinoma: From Embryonic Development to Precision Oncology

ABSTRACT

Pancreas is a vital gland of gastrointestinal system with exocrine and endocrine secretory functions, interweaved into essential metabolic circuitries of the human body. Pancreatic ductal adenocarcinoma (PDAC) represents one of the most lethal malignancies, with a 5-year survival rate of 11%. This poor prognosis is primarily attributed to the absence of early symptoms, rapid metastatic dissemination, and the limited efficacy of current therapeutic interventions. Despite recent advancements in understanding the etiopathogenesis and treatment of PDAC, there remains a pressing need for improved individualized models, identification of novel molecular targets, and development of unbiased predictors of disease progression. Here we aim to explore the concept of precision medicine utilizing 3-dimensional, patient-specific cellular models of pancreatic tumors and discuss their potential applications in uncovering novel druggable molecular targets and predicting clinical parameters for individual patients.

Multimodal single cell-resolved spatial proteomics reveal pancreatic tumor heterogeneity

Despite the advances in antibody-guided cell typing and mass spectrometry-based proteomics, their integration is hindered by challenges for processing rare cells in the heterogeneous tissue context. Here, we introduce Spatial and Cell-type Proteomics (SCPro), which combines multiplexed imaging and flow cytometry with ion exchange-based protein aggregation capture technology to characterize spatial proteome heterogeneity with single-cell resolution. The SCPro is employed to explore the pancreatic tumor microenvironment and reveals the spatial alternations of over 5000 proteins by automatically dissecting up to 100 single cells guided by multi-color imaging of centimeter-scale formalin-fixed, paraffin-embedded tissue slide. To enhance cell-type resolution, we characterize the proteome of 14 different cell types by sorting up to 1000 cells from the same tumor, which allows us to deconvolute the spatial distribution of immune cell subtypes and leads to the discovery of subtypes of regulatory T cells. Together, the SCPro provides a multimodal spatial proteomics approach for profiling tissue proteome heterogeneity.

Pathomic and bioinformatics analysis of clinical-pathological and genomic factors for pancreatic cancer prognosis

Pancreatic cancer exhibits a high degree of malignancy with a poor prognosis, lacking effective prognostic targets. Utilizing histopathological methodologies, this study endeavors to predict the expression of pathological features in pancreatic ductal adenocarcinoma (PAAD) and investigate their underlying molecular mechanisms. Pathological images, transcriptomic, and clinical data from TCGA-PAAD were collected for survival analysis. Image segmentation using unsupervised machine learning was employed to extract features, perform clustering, and establish models. The prognostic value of pathological features and associated clinical risk factors were evaluated; the correlation between pathological features and molecular mechanisms, gene mutations, and immune infiltration was analyzed. By clustering 45 effective pathological features, we divided PAAD patients into two groups: cluster 1 and cluster 2. Significant associations with poor prognosis were found for cluster 2 in both the training group (n = 113) and validation group (n = 75) (p = 0.006), with pathological stages II-IV identified as potential synergistic risk factors (HR = 2.421, 95% CI = 1.263-4.639, p = 0.008). Subsequently, through multi-omics correlation analysis, we further revealed a close association between cluster 2 and the oxidative phosphorylation mechanism. Within the cluster 2 group, 28 oxidative phosphorylation genes exhibited reduced expression, CDKN2A gene mutations were upregulated, and there was significant downregulation of Tregs infiltration and related immune gene expression. The pathomic model constructed using machine learning serves as a valuable prognostic target for PAAD. The histopathological features cluster 2 are closely associated with the downregulation of oxidative phosphorylation levels and Tregs immune infiltration.

Immunosenescence in digestive system cancers: Mechanisms, research advances, and therapeutic strategies

Increasing lifespans and external environmental factors have contributed to the increase of age-related diseases, particularly cancer. A decrease in immune surveillance and clearance of cancer cells is the result of immunosenescence, which involves the remodeling of immune organs, the changes and functional decline of immune cell subsets, in association with systemic low-grade chronic inflammation. Stem cells aging in bone marrow and thymic involution are the most important causes of immunosenescence. Senescent cancer cells promote the differentiation, recruitment, and functional upregulation of immune-suppressive cell subsets e.g. regulatory T cells (Tregs), myeloid-derived suppressor cell (MDSC), tumor-associated macrophages (TAMS) through senescence-associated secretory phenotype (SASP) further exacerbating the immunosuppressive microenvironment. For digestive system cancers, age-related damage to the intestinal mucosal barrier, the aging of gut-associated lymphoid tissue (GALT), exposure to xenobiotic stimuli throughout life, and dysbiosis make the local immune microenvironment more vulnerable. This article systematically reviews the research progress of immunosenescence and immune microenvironment in digestive system cancers, as well as the exploration of related therapy strategies, hoping to point out new directions for research in the digestive system cancers.

Pancreatic ductal adenocarcinoma cells reshape the immune microenvironment: Molecular mechanisms and therapeutic targets

Pancreatic ductal adenocarcinoma (PDAC) is a digestive system malignancy characterized by challenging early detection, limited treatment alternatives, and generally poor prognosis. Although there have been significant advancements in immunotherapy for hematological malignancies and various solid tumors in recent decades, with impressive outcomes in recent preclinical and clinical trials, the effectiveness of these therapies in treating PDAC continues to be modest. The unique immunological microenvironment of PDAC, especially the abnormal distribution, complex composition, and variable activation states of tumor-infiltrating immune cells, greatly restricts the effectiveness of immunotherapy. Undoubtedly, integrating data from both preclinical models and human studies helps accelerate the identification of reliable molecules and pathways responsive to targeted biological therapies and immunotherapies, thereby continuously optimizing therapeutic combinations. In this review, we delve deeply into how PDAC cells regulate the immune microenvironment through complex signaling networks, affecting the quantity and functional status of immune cells to promote immune escape and tumor progression. Furthermore, we explore the multi-modal immunotherapeutic strategies currently under development, emphasizing the transformation of the immunosuppressive environment into an anti-tumor milieu by targeting specific molecular and cellular pathways, providing insights for the development of novel treatment strategies.

Construction and Validation of a Novel T/NK-Cell Prognostic Signature for Pancreatic Cancer Based on Single-Cell RNA Sequencing

BACKGROUND

Evidence with regards to the distinction between primary and metastatic tumors in pancreatic cancer and driving factors for metastases remains limited.

METHODS

Single-cell RNA sequencing (scRNA-seq) was conducted on metastatic pancreatic cancer. Bioinformatics analysis on relevant sequencing data was used to construct a risk model to predict patient prognosis. Furthermore, immune infiltration and metabolic differences were assessed. The biological function of key differential genes was evaluated.

RESULTS

Paired primary and metastatic tumor tissues from 3 pancreatic cancer patients were collected and conducted scRNA-seq. Subsequently, the T/NK cell subgroup was the most different cell type between primary tumors and liver metastases and was selected for further analysis. Eventually, 6 specifically expressed genes of T/NK cells (B2M, ZFP36L2, ANXA1, ARL4C, TSPYL2, FYN) were used constructing the prognostic model. The stability of this model was validated by an external cohort. Meanwhile, different immune infiltration abundances occurred between high and low risk groups stratified by the model. The high-risk group had a stronger metabolic capability.

CONCLUSIONS

A novel prognostic T/NK-cell signature for pancreatic cancer was constructed based on scRNA-seq data and externally validated. The involved key genes may play a role in multiple metabolic pathways of metastasis and affect the tumor immune microenvironment.

A single-cell perspective on immunotherapy for pancreatic cancer: from microenvironment analysis to therapeutic strategy innovation

Pancreatic cancer remains one of the most lethal malignancies, with conventional treatment options providing limited efficacy. Recent advancements in immunotherapy have offered new hope, yet the unique tumor microenvironment (TME) of pancreatic cancer poses significant challenges to its successful application. This review explores the transformative impact of single-cell technology on the understanding and treatment of pancreatic cancer. By enabling high-resolution analysis of cellular heterogeneity within the TME, single-cell approaches have elucidated the complex interplay between various immune and tumor cell populations. These insights have led to the identification of predictive biomarkers and the development of innovative, personalized immunotherapeutic strategies. The review discusses the role of single-cell technology in dissecting the intricate immune landscape of pancreatic cancer, highlighting the discovery of T cell exhaustion profiles and macrophage polarization states that influence treatment response. Moreover, it outlines the potential of single-cell data in guiding the selection of immunotherapy drugs and optimizing treatment plans. The review also addresses the challenges and prospects of translating these single-cell-based innovations into clinical practice, emphasizing the need for interdisciplinary research and the integration of artificial intelligence to overcome current limitations. Ultimately, the review underscores the promise of single-cell technology in driving therapeutic strategy innovation and improving patient outcomes in the battle against pancreatic cancer.

Inflammatory Processes: Key Mediators of Oncogenesis and Progression in Pancreatic Ductal Adenocarcinoma (PDAC)

Associations between inflammation and cancer were first discovered approximately 160 years ago by Rudolf Virchow, who observed that tumors were infiltrated with inflammatory cells, and defined inflammation as a pathological condition. Inflammation has now emerged as one of the key mediators in oncogenesis and tumor progression, including pancreatic ductal adenocarcinoma (PDAC). However, the role of inflammatory processes in cancers is complicated and controversial, and the detailed regulatory mechanisms are still unclear. This review elucidates the dynamic interplay between inflammation and immune regulation, microenvironment alteration, metabolic reprogramming, and microbiome risk factors in PDAC, committing to exploring a deeper understanding of the role of crucial inflammatory pathways and molecules for providing insights into therapeutic strategies.

Oncogenic KRAS-Dependent Stromal Interleukin-33 Directs the Pancreatic Microenvironment to Promote Tumor Growth

Pancreatic cancer is characterized by an extensive fibroinflammatory microenvironment. During carcinogenesis, normal stromal cells are converted to cytokine-high cancer-associated fibroblasts (CAF). The mechanisms underlying this conversion, including the regulation and function of fibroblast-derived cytokines, are poorly understood. Thus, efforts to therapeutically target CAFs have so far failed. Herein, we show that signals from epithelial cells expressing oncogenic KRAS-a hallmark pancreatic cancer mutation-activate fibroblast autocrine signaling, which drives the expression of the cytokine IL33. Stromal IL33 expression remains high and dependent on epithelial KRAS throughout carcinogenesis; in turn, environmental stress induces interleukin-33 (IL33) secretion. Using compartment-specific IL33 knockout mice, we observed that lack of stromal IL33 leads to profound reprogramming of multiple components of the pancreatic tumor microenvironment, including CAFs, myeloid cells, and lymphocytes. Notably, loss of stromal IL33 leads to an increase in CD8+ T-cell infiltration and activation and, ultimately, reduced tumor growth. Significance: This study provides new insights into the mechanisms underlying the programming of CAFs and shows that during this process, expression of the cytokine IL33 is induced. CAF-derived IL33 has pleiotropic effects on the tumor microenvironment, supporting its potential as a therapeutic target.

CCR7/DUSP1 signaling Axis mediates iCAF to regulates head and neck squamous cell carcinoma growth

OBJECTIVE

C-C motif chemokine receptor 7 (CCR7) significantly influences tumors onset and progression, yet its impact on the tumor microenvironment (TME) and specific mechanisms remain elusive. Inflammatory Cancer-Associated Fibroblasts (iCAF), a vital subtype of Cancer-Associated Fibroblasts (CAF), play a critical role in regulating the TME and tumor growth, though the underlying molecular mechanisms are not fully understood. This study aims to determine whether CCR7 participates in tumor regulation by iCAF and to elucidate the specific mechanisms involved.

METHODS

Differential gene analysis of CAF subtypes in CCR7 knockout and wild-type groups was conducted using single-cell data. Animal models facilitated the extraction of primary iCAF cells via flow cytometry sorting. Changes in DUSP1 expression and the efficiency of lentivirus-mediated knockdown and overexpression were examined through qPCR and Western Blot. MOC1 and MOC2 cells were co-cultured with iCAF, with subsequent validation of changes in tumor cell proliferation, migration, and invasion using CCK8, EdU, and wound healing assays. ELISA was employed to detect changes in TGF-β1 concentration in the iCAF supernatant.

RESULTS

CAF was categorized into three subtypes-myCAF, iCAF, and apCAF-based on single-cell data. Analysis revealed a significant increase in DUSP1 expression in iCAF from the CCR7 knockout group, confirmed by in vitro experiments. Co-culturing MOC1 and MOC2 cells with iCAF exhibiting lentivirus-mediated DUSP1 knockdown resulted in inhibited tumor cell proliferation, invasion, and migration. In contrast, co-culture with iCAF overexpressing DUSP1 enhanced these capabilities. Additionally, the TGF-β1 concentration in the supernatant increased in the DUSP1 knockdown iCAF group, whereas it decreased in the DUSP1 overexpression group.

CONCLUSION

The CCR7/DUSP1 signaling axis regulates tumor growth by modulating TGF-β1 secretion in iCAF.

Panoramic tumor microenvironment in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is notorious for its resistance to various treatment modalities. The genetic heterogeneity of PDAC, coupled with the presence of a desmoplastic stroma within the tumor microenvironment (TME), contributes to an unfavorable prognosis. The mechanisms and consequences of interactions among different cell types, along with spatial variations influencing cellular function, potentially play a role in the pathogenesis of PDAC. Understanding the diverse compositions of the TME and elucidating the functions of microscopic neighborhoods may contribute to understanding the immune microenvironment status in pancreatic cancer. As we delve into the spatial biology of the microscopic neighborhoods within the TME, aiding in deciphering the factors that orchestrate this intricate ecosystem. This overview delineates the fundamental constituents and the structural arrangement of the PDAC microenvironment, highlighting their impact on cancer cell biology.

Metabolic and Immunological Implications of MME+CAF-Mediated Hypoxia Signaling in Pancreatic Cancer Progression: Therapeutic Insights and Translational Opportunities

Pancreatic cancer is a devastating malignancy with a high mortality rate, poor prognosis, and limited treatment options. The tumor microenvironment (TME) plays a crucial role in tumor progression and therapy resistance. Multiple subpopulations of cancer-associated fibroblasts (CAFs) within the TME can switch between different states, exhibiting both antitumorigenic and protumorigenic functions in pancreatic cancer. It seems that targeting fibroblast-related proteins and other stromal components is an appealing approach to combat pancreatic cancer. This study employed single-cell transcriptome sequencing to identify MME (Membrane Metalloendopeptidase)-expressing CAFs in pancreatic cancer. Systematic screening was conducted based on tumor differentiation, lymph node metastasis, and T-stage parameters to identify and confirm the existence of a subpopulation of fibroblasts termed MME+CAFs. Subsequent analyses included temporal studies, exploration of intercellular communication patterns focusing on the hypoxia signaling pathway, and investigation of MME+CAF functions in the pancreatic cancer microenvironment. The pathway enrichment analysis and clinical relevance revealed a strong association between high MME expression and glycolysis, hypoxia markers, and pro-cancer inflammatory pathways. The role of MME+CAFs was validated through in vivo and in vitro experiments, including high-throughput drug screening to evaluate potential targeted therapeutic strategies. Single-cell transcriptome sequencing revealed tumor-associated fibroblasts with high MME expression, termed MME+CAF, exhibiting a unique end-stage differentiation function in the TME. MME+CAF involvement in the hypoxia signaling pathway suggested the potential effects on pancreatic cancer progression through intercellular communication. High MME expression was associated with increased glycolysis, hypoxia markers (VEGF), and pro-cancer inflammatory pathways in pancreatic cancer patients, correlating with lower survival rates, advanced disease stage, and higher oncogene mutation rates. Animal experiments confirmed that elevated MME expression in CAFs increases tumor burden, promotes an immunosuppressive microenvironment, and enhances resistance to chemotherapy and immunotherapy. The developed MME+CAF inhibitor IOX2 (a specific prolyl hydroxylase-2 (PHD2) inhibitor), combined with AG (Paclitaxel + Gemcitabine) and anti-PD1 therapy, demonstrated promising antitumor effects, offering a translational strategy for targeting MME in CAFs of pancreatic cancer. The study findings highlighted the significant role of MME+CAF in pancreatic cancer progression by shaping the TME and influencing key pathways. Targeting MME presented a promising strategy to combat the disease, with potential implications for therapeutic interventions aimed at disrupting MME+CAF functions and enhancing the efficacy of pancreatic cancer treatments.

TNFR1 signaling promotes pancreatic tumor growth by limiting dendritic cell number and function

Pancreatic adenocarcinoma (PDAC) is one the most intractable cancers, in part due to its highly inflammatory microenvironment and paucity of infiltrating dendritic cells (DCs). Here, we find that genetic ablation or antibody blockade of tumor necrosis factor receptor 1 (TNFR1) enhanced intratumor T cell activation and slowed PDAC growth. While anti-PD-1 checkpoint inhibition alone had little effect, it further enhanced intratumor T cell activation in combination with anti-TNFR1. The major cellular alteration in the tumor microenvironment in the absence of TNFR1 signaling was a large increase in DC number and immunostimulatory phenotype. This may reflect a direct effect on DCs, because TNF induced TNFR1-dependent apoptosis of bone-marrow-derived DCs. The therapeutic response to anti-TNFR1 alone was superior to the combination of DC-activating agonistic anti-CD40 and Flt3 ligand (Flt3L). These observations suggest that targeting TNFR1, perhaps in concert with other strategies that promote DC generation and mobilization, may have therapeutic benefits.

From Inception to Malignancy: the Co-evolution of Pancreatic Cancer and Its Immunosuppressive Microenvironment

Published in Cancer Research in 2007, Clark and colleagues first introduced the concept that the immune microenvironment evolves in lockstep with the progression of pancreatic cancer. Leveraging genetically engineered mouse models of the disease that were described a few years earlier, Clark and colleagues used a combination of approaches to describe the dynamics of immune evolution in precursor lesions all the way to overt malignancy. They discovered that immunosuppression is established at the earliest stages of carcinogenesis. Here, we discuss their findings, how they led to a wealth of functional work, and how they have been expanded upon since the advent of -omics technologies. See related article by Clark and colleagues, Cancer Res 2007;67:9518-27.

Noncoding Ribonucleic Acids (RNAs) May Improve Response to Immunotherapy in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is the seventh most common cause of cancer-related mortality. Despite different methods of treatment, nearly more than 90% of patients with PDAC die shortly after diagnosis. Contrary to promising results in other cancers, immune checkpoint inhibitors (ICIs) showed limited success in PDAC. Recent studies have shown that noncoding RNAs (ncRNAs) are extensively involved in PDAC cell-immune cell interaction and mediate immune evasion in this vicious cancer. PDAC cells recruit numerous ncRNAs to widely affect the phenotype and function of immune cells through various mechanisms. For instance, PDAC cells upregulate miR-301a and downregulate miR-340 to induce M2 polarization of macrophages or overexpress miR-203, miR-146a, and miR-212-3p to downregulate toll-like receptor 4 (TLR4), CD80, CD86, CD1a, major histocompatibility complex (MHC) II, and CD83, thereby evading recognition by dendritic cells. By downregulating miR-4299 and miR-153, PDAC cells can decrease the expression of NK group 2D (NKG2D) and MHC class I chain-related molecules A and B (MICA/B) to blunt the natural killer (NK) cell response. PDAC cells also highly express lncRNA AL137789.1, hsa_circ_0046523, lncRNA LINC00460, and miR-155-5p to upregulate immune checkpoint proteins and escape T cell cytotoxicity. On the other hand, ncRNAs derived from suppressive immune cells promote proliferation, invasion, and drug resistance in PDAC cells. ncRNAs can be applied to overcome resistance to ICIs, monitor the immune microenvironment of PDAC, and predict response to ICIs. This Review article comprehensively discusses recent findings regarding the roles of ncRNAs in the immune evasion of PDAC.

Barriers and opportunities in pancreatic cancer immunotherapy

Pancreatic ductal adenocarcinoma (PDAC) presents a fatal clinical challenge characterized by a dismal 5-year overall survival rate, primarily due to the lack of early diagnosis and limited therapeutic efficacy. Immunotherapy, a proven success in multiple cancers, has yet to demonstrate significant benefits in PDAC. Recent studies have revealed the immunosuppressive characteristics of the PDAC tumor microenvironment (TME), including immune cells with suppressive properties, desmoplastic stroma, microbiome influences, and PDAC-specific signaling pathways. In this article, we review recent advances in understanding the immunosuppressive TME of PDAC, TME differences among various mouse models of pancreatic cancer, and the mechanisms underlying resistance to immunotherapeutic interventions. Furthermore, we discuss the potential of targeting cancer cell-intrinsic pathways and TME components to sensitize PDAC to immune therapies, providing insights into strategies and future perspectives to break through the barriers in improving pancreatic cancer treatment.

Metabolic reprogramming and immune evasion: the interplay in the tumor microenvironment

Tumor cells possess complex immune evasion mechanisms to evade immune system attacks, primarily through metabolic reprogramming, which significantly alters the tumor microenvironment (TME) to modulate immune cell functions. When a tumor is sufficiently immunogenic, it can activate cytotoxic T-cells to target and destroy it. However, tumors adapt by manipulating their metabolic pathways, particularly glucose, amino acid, and lipid metabolism, to create an immunosuppressive TME that promotes immune escape. These metabolic alterations impact the function and differentiation of non-tumor cells within the TME, such as inhibiting effector T-cell activity while expanding regulatory T-cells and myeloid-derived suppressor cells. Additionally, these changes lead to an imbalance in cytokine and chemokine secretion, further enhancing the immunosuppressive landscape. Emerging research is increasingly focusing on the regulatory roles of non-tumor cells within the TME, evaluating how their reprogrammed glucose, amino acid, and lipid metabolism influence their functional changes and ultimately aid in tumor immune evasion. Despite our incomplete understanding of the intricate metabolic interactions between tumor and non-tumor cells, the connection between these elements presents significant challenges for cancer immunotherapy. This review highlights the impact of altered glucose, amino acid, and lipid metabolism in the TME on the metabolism and function of non-tumor cells, providing new insights that could facilitate the development of novel cancer immunotherapies.

The Role of Tumor Microenvironment in Pancreatic Cancer Immunotherapy: Current Status and Future Perspectives

Pancreatic cancer comprises different subtypes, where most cases include ductal adenocarcinoma (PDAC). It is one of the deadliest tumor types, with a poor prognosis. In the majority of patients, the disease has already spread by the time of diagnosis, making full recovery unlikely and increasing mortality risk. Despite developments in its detection and management, including chemotherapy, radiotherapy, and targeted therapies as well as advances in immunotherapy, only in about 13% of PDAC patients does the overall survival exceed 5 years. This may be attributed, at least in part, to the highly desmoplastic tumor microenvironment (TME) that acts as a barrier limiting perfusion, drug delivery, and immune cell infiltration and contributes to the establishment of immunologically 'cold' conditions. Therefore, there is an urgent need to unravel the complexity of the TME that promotes PDAC progression and decipher the mechanisms of pancreatic tumors' resistance to immunotherapy. In this review, we provide an overview of the major cellular and non-cellular components of PDAC TME, as well as their biological interplays. We also discuss the current state of PDAC therapeutic treatments and focus on ongoing and future immunotherapy efforts and multimodal treatments aiming at remodeling the TME to improve therapeutic efficacy.

Aryl Hydrocarbon Receptor Knockout Accelerates PanIN Formation and Fibro-Inflammation in a Mutant Kras -Driven Pancreatic Cancer Model

OBJECTIVES

The pathogenesis of pancreas cancer (PDAC) remains poorly understood, hindering efforts to develop a more effective therapy for PDAC. Recent discoveries show the aryl hydrocarbon receptor (AHR) plays a crucial role in the development of several cancers and can be targeted for therapeutic effect. However, its involvement in the pathogenesis of PDAC remains unclear. To address this gap, we evaluated the role of AHR in the development of PDAC precancerous lesions in vivo .

MATERIALS AND METHODS

We created a global AHR-null, mutant Kras -driven PDAC mouse model (A -/- KC) and evaluated the changes in PDAC precursor lesion formation (PanIN-1, 2, and 3) and associated fibro-inflammation between KC and A -/- KC at 5 months of age. We then examined the changes in the immune microenvironment followed by single-cell RNA-sequencing analysis to evaluate concomitant transcriptomic changes.

RESULTS

We identified a significant increase in PanIN-1 lesion formation and PanIN-1 associated fibro-inflammatory infiltrate in A -/- KC versus KC mice. This was associated with significant changes in the adaptive immune system, particularly a decrease in the CD4+/CD8+ T-cell ratio, as well as a decrease in the T-regulatory/Th17 T-cell ratio suggesting unregulated inflammation.

CONCLUSIONS

These findings show the loss of AHR results in heightened Kras -induced PanIN formation, through modulation of immune cells within the pancreatic tumor microenvironment.

Engineering Bimetallic Polyphenol for Mild Photothermal Osteosarcoma Therapy and Immune Microenvironment Remodeling by Activating Pyroptosis and cGAS-STING Pathway

The immunosuppressive tumor microenvironment (ITME) of osteosarcoma (OS) poses a significant obstacle to the efficacy of existing immunotherapies. Despite the attempt of novel immune strategies such as immune checkpoint inhibitors and tumor vaccines, their effectiveness remains suboptimal due to the inherent difficulty in mitigating ITME simultaneously from both the tumor and immune system. The promotion of anti-tumor immunity through the induction of immunogenic cell death and activation of the cGAS-STING pathway has emerged as potential strategies to counter the ITME and stimulate systemic antitumor immune responses. Here, a bimetallic polyphenol-based nanoplatform (Mn/Fe-Gallate nanoparticles coated with tumor cell membranes is presented, MFG@TCM) which combines with mild photothermal therapy (PTT) for reversing ITME via simultaneously inducing pyroptosis in OS cells and activating the cGAS-STING pathway in dendritic cells (DCs). The immunostimulatory pathways, through the syngeneic effect, exerted a substantial positive impact on promoting the secretion of damage-associated molecular patterns (DAMPs) and proinflammatory cytokines, which favors remodeling the immune microenvironment. Consequently, effector T cells led to a notable antitumor immune response, effectively inhibiting the growth of both primary and distant tumors. This study proposes a new method for treating OS using mild PTT and immune mudulation, showing promise in overcoming current treatment limitations.

Deciphering Regulatory T-Cell Dynamics in Cancer Immunotherapy: Mechanisms, Implications, and Therapeutic Innovations

This Review explores how tumor-associated regulatory cells (Tregs) affect cancer immunotherapy. It shows how Tregs play a role in keeping the immune system in check, how cancers grow, and how well immunotherapy work. Tregs use many ways to suppress the immune system, and these ways are affected by the tumor microenvironment (TME). New approaches to cancer therapy are showing promise, such as targeting Treg checkpoint receptors precisely and using Fc-engineered antibodies. It is important to tailor treatments to each patient's TME in order to provide personalized care. Understanding Treg biology is essential for creating effective cancer treatments and improving the long-term outcomes of immunotherapy.

Breaking Down Barriers in Drug Delivery by Stromal Remodeling Approaches in Pancreatic Cancer

Pancreatic cancer remains a formidable challenge in oncology due to its aggressive nature and limited treatment options. The dense stroma surrounding pancreatic tumors not only provides structural support but also presents a formidable barrier to effective therapy, hindering drug penetration and immune cell infiltration. This review delves into the intricate interplay between stromal components and cancer cells, highlighting their impact on treatment resistance and prognosis. Strategies for stromal remodeling, including modulation of cancer-associated fibroblasts (CAFs), pancreatic stellate cells (PSCs) activation states, and targeting extracellular matrix (ECM) components, are examined for their potential to enhance drug penetration and improve therapeutic efficacy. Integration of stromal remodeling with conventional therapies, such as chemotherapy and immunotherapy, is discussed along with the emerging field of intelligent nanosystems for targeted drug delivery. This comprehensive overview underscores the importance of stromal remodeling in pancreatic cancer treatment and offers insights into promising avenues for future research and clinical translation.

Focus on Pancreatic Cancer Microenvironment

Pancreatic ductal adenocarcinoma remains one of the most lethal solid tumors due to its local aggressiveness and metastatic potential, with a 5-year survival rate of only 13%. A robust connection between pancreatic cancer microenvironment and tumor progression exists, as well as resistance to current anticancer treatments. Pancreatic cancer has a complex tumor microenvironment, characterized by an intricate crosstalk between cancer cells, cancer-associated fibroblasts and immune cells. The complex composition of the tumor microenvironment is also reflected in the diversity of its acellular components, such as the extracellular matrix, cytokines, growth factors and secreted ligands involved in signaling pathways. Desmoplasia, the hallmark of the pancreatic cancer microenvironment, contributes by creating a dense and hypoxic environment that promotes further tumorigenesis, provides innate systemic resistance and suppresses anti-tumor immune invasion. We discuss the complex crosstalk among tumor microenvironment components and explore therapeutic strategies and opportunities in pancreatic cancer research. Better understanding of the tumor microenvironment and its influence on pancreatic cancer progression could lead to potential novel therapeutic options, such as integration of immunotherapy and cytokine-targeted treatments.

Harnessing the tumor microenvironment to boost adoptive T cell therapy with engineered lymphocytes for solid tumors

Adoptive cell therapy (ACT) using Chimeric Antigen Receptor (CAR) and T Cell Receptor (TCR) engineered T cells represents an innovative therapeutic approach for the treatment of hematological malignancies, yet its application for solid tumors is still suboptimal. The tumor microenvironment (TME) places several challenges to overcome for a satisfactory therapeutic effect, such as physical barriers (fibrotic capsule and stroma), and inhibitory signals impeding T cell function. Some of these obstacles can be faced by combining ACT with other anti-tumor approaches, such as chemo/radiotherapy and checkpoint inhibitors. On the other hand, cutting edge technological tools offer the opportunity to overcome and, in some cases, take advantage of TME intrinsic characteristics to boost ACT efficacy. These include: the exploitation of chemokine gradients and integrin expression for preferential T-cell homing and extravasation; metabolic changes that have direct or indirect effects on TCR-T and CAR-T cells by increasing antigen presentation and reshaping T cell phenotype; introduction of additional synthetic receptors on TCR-T and CAR-T cells with the aim of increasing T cells survival and fitness.

Targeting the pancreatic tumor microenvironment by plant-derived products and their nanoformulations

Pancreatic cancer remains a significant health issue with limited treatment options. The tumor stroma, a complex environment made up of different cells and proteins, plays a crucial role in tumor growth and chemoresistance. Targeting tumor stroma, consisting of diverse non-tumor cells such as fibroblasts, extracellular matrix (ECM), immune cells, and also pre-vascular cells is encouraging for remodeling solid cancers, such as pancreatic cancer. Remodeling the stroma of pancreas tumors can be suggested as a strategy for reducing resistance to chemo/immunotherapy. Several studies have shown that phytochemicals from plants can affect the tumor environment and have anti-cancer properties. By targeting key pathways involved in stromal activation, phytochemicals may disrupt communication between the tumor and stroma and make tumor cells more sensitive to different treatments. Additionally, phytochemicals have immunomodulatory and anti-angiogenic properties, all of which contribute to their potential in treating pancreatic cancer. This review will provide a detailed look at how phytochemicals impact the tumor stroma and their effects on pancreatic tumor growth, spread, and response to treatment. It will also explore the potential of combining phytochemicals with other treatment options like chemotherapy, immunotherapy, and radiation.

T-cell responses in colorectal peritoneal metastases are recapitulated in a humanized immune system mouse model

Background

The occurrence of peritoneal metastasis (PM) in patients with colorectal cancer (CRC) has a dismal prognosis. There is often limited response to systemic- and immunotherapy, even in microsatellite unstable (MSI) CRC. To overcome therapy resistance, it is critical to understand local immune environment in the peritoneal cavity, and to develop models to study anti-tumor immune responses. Here, we defined the peritoneal immune system (PerIS) in PM-CRC patients and evaluate the pre-clinical potential of a humanized immune system (HIS) mouse model for PM-CRC.

Methods

We studied the human PerIS in PM-CRC patients (n=20; MSS 19/20; 95%) and in healthy controls (n=3). HIS mice (NODscid gamma background; n=18) were generated, followed by intraperitoneal injection of either saline (HIS control; n=3) or human MSS/MSI CRC cell lines HUTU80, MDST8 and HCT116 (HIS-PM, n=15). Immune cells in peritoneal fluid and peritoneal tumors were analyzed using cytometry by time of flight (CyTOF).

Results

The human and HIS mouse homeostatic PerIS was equally populated by NK cells and CD4+- and CD8+ T cells, however differences were observed in macrophage and B cell abundance. In HIS mice, successful peritoneal engraftment of both MSI and MSS tumors was observed (15/15; 100%). Both in human PM-CRC and in the HIS mouse PM-CRC model, we observed that MSS PM-CRC triggered a CD4+ Treg response in the PerIS, while MSI PM-CRC drives CD8+ TEMs responses.

Conclusion

In conclusion, T cell responses in PM-CRC in HIS mice mirror those in human PM-CRC, making this model suitable to study antitumor T cell responses in PM-CRC.

Complex Role of Regulatory T Cells (Tregs) in the Tumor Microenvironment: Their Molecular Mechanisms and Bidirectional Effects on Cancer Progression

Regulatory T cells (Tregs) possess unique immunosuppressive activity among CD4-positive T cells. Tregs are ubiquitously present in mammals and function to calm excessive immune responses, thereby suppressing allergies or autoimmune diseases. On the other hand, due to their immunosuppressive function, Tregs are thought to promote cancer progression. The tumor microenvironment (TME) is a multicellular system composed of many cell types, including tumor cells, infiltrating immune cells, and cancer-associated fibroblasts (CAFs). Within this environment, Tregs are recruited by chemokines and metabolic factors and impede effective anti-tumor responses. However, in some cases, their presence can also improve patient's survival rates. Their functional consequences may vary across tumor types, locations, and stages. An in-depth understanding of the precise roles and mechanisms of actions of Treg is crucial for developing effective treatments, emphasizing the need for further investigation and validation. This review aims to provide a comprehensive overview of the complex and multifaceted roles of Tregs within the TME, elucidating cellular communications, signaling pathways, and their impacts on tumor progression and highlighting their potential anti-tumor mechanisms through interactions with functional molecules.

Immune cells and checkpoints in pancreatic adenocarcinoma: Association with clinical and pathological characteristics

INTRODUCTION

Pancreatic adenocarcinoma is an extremely aggressive neoplasm, with many challenges to be overcome in order to achieve a truly effective treatment. It is characterized by a mostly immunosuppressed environment, with dysfunctional immune cells and active immunoinhibitory pathways that favor tumor evasion and progression. Thus, the study and understanding of the tumor microenvironment and the various cells subtypes and their functional capacities are essential to achieve more effective treatments, especially with the use of new immunotherapeutics.

METHODS

Seventy cases of pancreatic adenocarcinoma divided into two groups 43 with resectable disease and 27 with unresectable disease were analyzed using immunohistochemical methods regarding the expression of programmed cell death ligand 1 (PD-L1), programmed cell death ligand 2 (PD-L2), and human leukocyte antigen G (HLA-G) molecules as well as the populations of CD4+ and CD8+ T lymphocytes, regulatory T cells (Tregs), and M2 macrophages (MM2). Several statistical tests, including multivariate analyses, were performed to examine how those immune cells and immunoinhibitory molecules impact the evolution and prognosis of pancreatic adenocarcinoma.

RESULTS

CD8+ T lymphocytes and M2 macrophages predominated in the group operated on, and PD-L2 expression predominated in the unresectable group. PD-L2 was associated with T stage, lymph node metastasis, and clinical staging, while in survival analysis, PD-L2 and HLA-G were associated with a shorter survival. In the inoperable cases, Tregs cells, MM2, PD-L1, PD-L2, and HLA-G were positively correlated.

CONCLUSIONS

PD-L2 and HLA-G expression correlated with worse survival in the cases studied. Tumor microenvironment was characterized by a tolerant and immunosuppressed pattern, mainly in unresectable lesions, where a broad positive influence was observed between immunoinhibitory cells and immune checkpoint proteins expressed by tumor cells.

The tumor immune microenvironment remodeling and response to HER2-targeted therapy in HER2-positive advanced gastric cancer

Combination therapy with anti-HER2 agents and immunotherapy has demonstrated significant clinical benefits in gastric cancer (GC), but the underlying mechanism remains unclear. In this study, we used multiplex immunohistochemistry to assess the changes of the tumor microenvironment in 47 advanced GC patients receiving anti-HER2 therapy. Additionally, we performed single-cell transcriptional sequencing to investigate potential cell-to-cell communication and molecular mechanisms in four HER2-positive GC baseline samples. We observed that post-treated the infiltration of NK cells, CD8+ T cells, and B lymphocytes were significantly higher in patients who benefited from anti-HER2 treatment than baseline. Further spatial distribution analysis demonstrated that the interaction scores between NK cells and CD8+ T cells, B lymphocytes and M2 macrophages, B lymphocytes and Tregs were also significantly higher in benefited patients. Cell-cell communication analysis from scRNA sequencing showed that NK cells utilized CCL3/CCL4-CCR5 to recruit CD8+ T cell infiltration. B lymphocytes employed CD74-APP/COPA/MIF to interact with M2 macrophages, and utilized TNF-FAS/ICOS/TNFRSR1B to interact with Tregs. These cell-cell interactions contribute to inhibit the immune resistance of M2 macrophages and Tregs. Our research provides potential guidance for the use of anti-HER2 therapy in combination with immune therapy.

Senescence Defines a Distinct Subset of Myofibroblasts That Orchestrates Immunosuppression in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) therapeutic resistance is largely attributed to a unique tumor microenvironment embedded with an abundance of cancer-associated fibroblasts (CAF). Distinct CAF populations were recently identified, but the phenotypic drivers and specific impact of CAF heterogeneity remain unclear. In this study, we identify a subpopulation of senescent myofibroblastic CAFs (SenCAF) in mouse and human PDAC. These SenCAFs are a phenotypically distinct subset of myofibroblastic CAFs that localize near tumor ducts and accumulate with PDAC progression. To assess the impact of endogenous SenCAFs in PDAC, we used an LSL-KRASG12D;p53flox;p48-CRE;INK-ATTAC (KPPC-IA) mouse model of spontaneous PDAC with inducible senescent cell depletion. Depletion of senescent stromal cells in genetic and pharmacologic PDAC models relieved immune suppression by macrophages, delayed tumor progression, and increased responsiveness to chemotherapy. Collectively, our findings demonstrate that SenCAFs promote PDAC progression and immune cell dysfunction. Significance: CAF heterogeneity in PDAC remains poorly understood. In this study, we identify a novel subpopulation of senescent CAFs that promotes PDAC progression and immunosuppression. Targeting CAF senescence in combination therapies could increase tumor vulnerability to chemo or immunotherapy. See related article by Ye et al., p. 1302.

MMP11 as a prognostic biomarker correlated with immune infiltrates in pancreatic adenocarcinoma

BACKGROUND

Matrix metalloproteinase 11 (MMP11) plays a vital role in cell proliferation, apoptosis, tumor angiogenesis, migration, and other basic processes. Currently, few studies have examined the value of MMP11 in pancreatic cancer in relation to prognostic risk, diagnostic indicators, and immunotherapy. This study aims to explore the association between MMP11 and the tumor immune microenvironment in pancreatic adenocarcinoma (PAAD).

METHODS

We selected clinical samples and data downloaded from The Cancer Genome Atlas and Genotype-Tissue Expression, in addition, we use other online data for further analysis. Through a comprehensive bioinformatics investigation, we systematically analyzed the clinical significance and expression level of MMP11 in pancreatic cancer.

RESULTS

MMP11 was overexpressed in many cancers, and a higher expression of MMP11 was associated with a poorer prognosis in pancreatic cancer. Conversely, the hypermethylation of MMP11 was associated with better overall survival. The MMP11 expression network had widespread effects on the prognosis and immune activation of PAAD. The expression of MMP11 was significantly associated with a variety of tumor-infiltrating immune cells. An association was also found between MMP11 expression and chemokines in PAAD. High MMP11 expression might be involved in immune cell migration to the tumor microenvironment.

CONCLUSIONS

MMP11 is a prognostic biomarker for patients in pancreatic cancer and may regulate the tumor immune microenvironment. The potential effects and mechanisms of MMP11 in PAAD require further exploring.

Type I conventional dendritic cells facilitate immunotherapy in pancreatic cancer

Inflammation and tissue damage associated with pancreatitis can precede or occur concurrently with pancreatic ductal adenocarcinoma (PDAC). We demonstrate that in PDAC coupled with pancreatitis (ptPDAC), antigen-presenting type I conventional dendritic cells (cDC1s) are specifically activated. Immune checkpoint blockade therapy (iCBT) leads to cytotoxic CD8+ T cell activation and elimination of ptPDAC with restoration of life span even upon PDAC rechallenge. Using PDAC antigen-loaded cDC1s as a vaccine, immunotherapy-resistant PDAC was rendered sensitive to iCBT with elimination of tumors. cDC1 vaccination coupled with iCBT identified specific CDR3 sequences in the tumor-infiltrating CD8+ T cells with potential therapeutic importance. This study identifies a fundamental difference in the immune microenvironment in PDAC concurrent with, or without, pancreatitis and provides a rationale for combining cDC1 vaccination with iCBT as a potential treatment option.

TGF-β1 inhibitor enhances the therapeutic effect of microwave ablation on hepatocellular carcinoma

BACKGROUND

Microwave ablation (MWA) is a widely adopted treatment technique for hepatocellular carcinoma (HCC). However, MWA alone is of limited use and has a high recurrence rate. Transforming growth factor-β1 (TGF-β1) is recognized as a potential therapeutic target for HCC patients. Therefore, this study was designed to investigate whether the TGF-β1 inhibitor could increase the efficacy of MWA therapy for HCC treatment.

METHODS

In vitro, HCC cells challenged with TGF-β1 inhibitor (SB-525334), or normal saline were then heated by microwave. Methyl tetrazolium assays were performed to detect cell survival rate and half-maximal drug inhibitory concentration (IC50). Cell viability and apoptosis were detected by cell counting kit-8 assays, flow cytometry and western blotting. In vivo, the mice injected with HepG2 cells received oral gavage of SB-525334 (20 mg/kg) or normal saline and MWA at a power of 15 W. Tumor volume was recorded. Expression of Ki67 and apoptosis-related proteins were detected by immunohistochemistry and western blotting. TUNEL assays were used to detect cell death ratio. Histopathological changes were examined by hematoxylin and eosin staining. The mechanisms associated with the function of MWA combined with TGF-β1 inhibitor in HCC development were explored by western blotting.

RESULTS

Combination of MWA and SB-525334 decreased the survival rate and promoted the apoptosis of HCC cells compared with MWA alone. SB-525334 enhanced the suppressive effect of MWA on tumor growth and amplified cell apoptosis. Mechanistically, MWA collaborated with SB-525334 inhibitor inactivated the TGF-β1/Smad2/Smad3 pathway.

CONCLUSION

TGF-β1 inhibitor enhances the therapeutic effect of MWA on HCC.

The Macrophage migration inhibitory factor is a vital player in Pan-Cancer by functioning as a M0 Macrophage biomarker

BACKGROUND

The role of the macrophage migration inhibitory factor (MIF) has recently attracted considerable attention in cancer research; nonetheless, the insights provided by current investigations remain constrained. Our main objective was to investigate its role and the latent mechanisms within the pan-cancer realm.

METHODS

We used comprehensive pan-cancer bulk sequencing data and online network tools to investigate the association between MIF expression and patient prognosis, genomic instability, cancer cell stemness, DNA damage repair, and immune infiltration. Furthermore, we validated the relationship between MIF expression and M0 macrophages using single-cell datasets, the SpatialDB database, and fluorescence staining. Additionally, we assessed the therapeutic response using the ROC plotter tool.

RESULTS

We observed the upregulation of MIF expression across numerous cancer types. Notably, elevated MIF levels were associated with a decline in genomic stability. We found a significant correlation between increased MIF expression and increased expression of mismatch repair genes, stemness features, and homologous recombination genes across diverse malignancies. Subsequently, through an analysis using ESTIMATE and cytokine results, we revealed the involvement of MIF in immune suppression. Then, we validated MIF as a hallmark of the M0 macrophages involved in tumor immunity. Our study suggests an association with other immune-inhibitory cellular populations and restraint of CD8 + T cells. In addition, we conducted a comparative analysis of MIF expression before and after treatment in three distinct sets of therapy responders and non-responders. Intriguingly, we identified notable disparities in MIF expression patterns in bladder urothelial carcinoma and ovarian cancer following particular therapeutic interventions.

CONCLUSION

Comprehensive pan-cancer analysis revealed notable enrichment of MIF within M0 macrophages, exerting a profound influence on tumor-associated immunosuppression and the intricate machinery of DNA repair.

Tumor microenvironment as niche constructed by cancer stem cells: Breaking the ecosystem to combat cancer

BACKGROUND

Cancer stem cells (CSCs) are a distinct subpopulation of cancer cells with the capacity to constantly self-renew and differentiate, and they are the main driver in the progression of cancer resistance and relapse. The tumor microenvironment (TME) constructed by CSCs is the "soil" adapted to tumor growth, helping CSCs evade immune killing, enhance their chemical resistance, and promote cancer progression.

AIM OF REVIEW

We aim to elaborate the tight connection between CSCs and immunosuppressive components of the TME. We attempt to summarize and provide a therapeutic strategy to eradicate CSCs based on the destruction of the tumor ecological niche.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review is focused on three main key concepts. First, we highlight that CSCs recruit and transform normal cells to construct the TME, which further provides ecological niche support for CSCs. Second, we describe the main characteristics of the immunosuppressive components of the TME, targeting strategies and summarize the progress of corresponding drugs in clinical trials. Third, we explore the multilevel insights of the TME to serve as an ecological niche for CSCs.

Current and future immunotherapeutic approaches in pancreatic cancer treatment

Pancreatic cancer is a major cause of cancer-related death, but despondently, the outlook and prognosis for this resistant type of tumor have remained grim for a long time. Currently, it is extremely challenging to prevent or detect it early enough for effective treatment because patients rarely exhibit symptoms and there are no reliable indicators for detection. Most patients have advanced or spreading cancer that is difficult to treat, and treatments like chemotherapy and radiotherapy can only slightly prolong their life by a few months. Immunotherapy has revolutionized the treatment of pancreatic cancer, yet its effectiveness is limited by the tumor's immunosuppressive and hard-to-reach microenvironment. First, this article explains the immunosuppressive microenvironment of pancreatic cancer and highlights a wide range of immunotherapy options, including therapies involving oncolytic viruses, modified T cells (T-cell receptor [TCR]-engineered and chimeric antigen receptor [CAR] T-cell therapy), CAR natural killer cell therapy, cytokine-induced killer cells, immune checkpoint inhibitors, immunomodulators, cancer vaccines, and strategies targeting myeloid cells in the context of contemporary knowledge and future trends. Lastly, it discusses the main challenges ahead of pancreatic cancer immunotherapy.