Search Results (651)

Immune checkpoint blockade (ICB) has transformed cancer therapy, but clinical responses remain heterogeneous across tumor types and patient populations. Cancer-associated fibroblasts (CAFs) are key stromal components of the tumor microenvironment and can contribute to immunotherapy resistance through immune exclusion, extracellular matrix remodeling, chemokine signaling, and interactions with suppressive immune cells. Although CAF-directed strategies are under active investigation, their clinical translation is limited by marked CAF heterogeneity and the lack of scalable biomarkers for patient stratification. Computational pathology based on hematoxylin and eosin (H&E) whole-slide images (WSIs) provides a potential approach for extracting stromal and spatial features from routine histology, although digitized WSIs and the infrastructure required for large-scale AI analysis are not universally available. In this review, we synthesize current evidence on CAF classification, CAF-mediated immunotherapy resistance, H&E-based computational pathology, and emerging histology-based biomarker models. We further propose a conceptual roadmap for developing CAF-aware H&E spatial signatures with potential relevance to future immunotherapy stratification. Current evidence supports the biological rationale and computational feasibility of this approach, whereas its clinical utility remains to be established through rigorous external validation and prospective clinical evaluation. Full article

Chronic hepatitis B virus (CHB) infection remains a major cause of hepatocellular carcinoma (HCC), yet the premalignant microenvironment that links to HBV-associated HCC (HBV-HCC) is still poorly defined. This review synthesizes evidence that HBV-infected hepatocytes function as signaling hubs that, through microRNA (miRNA)-regulated crosstalk with Kupffer cells, liver sinusoidal endothelial cells, hepatic stellate cells and cancer-associated fibroblasts (CAFs), progressively remodel the liver from an antiviral tissue into a premalignant and early tumor microenvironment. Across the HBV-HCC continuum, a core set of dysregulated miRNAs, including miR-21, miR-29a/b, miR-122, miR-146a, miR-155, miR-200a, miR-126, miR-210 and the miR-130/301 family, coordinates transition from innate antiviral responses to HSC activation, extracellular matrix deposition, mechanotransduction, angiogenesis, chronic inflammation and cancer-associated CAF programing. By mapping these stage-specific miRNA networks onto acute infection, CHB, early fibrogenesis, advanced fibrosis and CAF-rich dysplastic states, the review reframes HBV-HCC pathogenesis as a sequence of miRNA-guided hepatocyte–stromal states rather than a purely hepatocyte-intrinsic process. This perspective suggests that composite, cell-type-resolved miRNA signatures in serum or liver tissue could serve as biomarkers for identifying CHB patients who are entering a premalignant microenvironment before conventional surveillance markers become abnormal. It further highlights miRNA hubs that couple antiviral, fibrogenic, angiogenic and CAF-associated signaling as potential therapeutic targets for reprograming the HBV-driven premalignant microenvironment, with the long-term goal of intercepting HBV-HCC development at earlier, microenvironmentally defined stages. Full article

Background: The efficacy of chemotherapy in triple-negative breast cancer (TNBC) is limited by intrinsic resistance and the tumor microenvironment (TME). Accumulating evidence reveals a mechanistic connection between programmed death-ligand 1 (PD-L1) and c-x-c motif chemokine receptor 4 (CXCR4), which dominate stroma barriers, immune escape, and cancer metastasis. Earlier studies have shown that dual suppression of c-x-c motif ligand 12 (CXCL12)/CXCR4 and programmed cell death-1 (PD-1)/PD-L1 pathways regulates extracellular matrix (ECM) deposition, activation of cancer-associated fibroblasts (CAFs), and epithelial–mesenchymal transition (EMT) of pancreatic cancer cells. Methods: We combined BsNb PX4, a bispecific nanobody targeting PD-L1 and CXCR4, with paclitaxel or gemcitabine in multiple tumor cell lines and human peripheral blood mononuclear cell (hPBMC)-reconstituted xenograft mouse models. Antitumor activity was assessed by CCK-8, flow cytometry, and ELISA, and immune cell infiltration and TME remodeling were examined by immunofluorescence, immunohistochemistry, cytokine assays, and RNA-seq. Results: In MDA-MB-231 cells, BsNb PX4 synergistically enhanced paclitaxel-induced growth inhibition and apoptosis via G₂/M cycle arrest. This combinatorial strategy profoundly remodeled tumor immunity by expanding CD8⁺ T cells and depleting Foxp3⁺ CD4⁺ regulatory T cells (Tregs), while concurrently restoring T-cell cytotoxicity and skewing the cytokine balance toward an antitumor state, with elevated IFN-γ and reduced TGF-β1. Notably, compared with paclitaxel monotherapy, the combination significantly elevated intratumoral CD8⁺ T-cell infiltration, decreased Treg abundance, and exerted robust inhibitory effects on tumor growth and metastasis in humanized TNBC xenografts. Conclusions: These findings reveal that dual blockade of PD-L1 and CXCR4 acts synergistically with chemotherapy by triggering tumor cell apoptotic effects and reversing the immunosuppressive microenvironment, thereby emerging as a promising therapeutic strategy for TNBC. Full article

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with a five-year survival rate below 10%. Cancer-associated fibroblasts (CAFs) promote epithelial–mesenchymal transition (EMT) and metastasis, yet the specific CAF subtypes and molecular axes driving PDAC progression remain incompletely understood. Here, using multi-omics data from PDAC samples, we identified a malignant ductal subpopulation, termed Ductal-T0, characterized by the highest EMT activity and prominent acquisition of myofibroblastic CAF (myCAF)-like transcriptional programs. Computationally, we predicted that myCAF-secreted THBS2 and FN1 engage the ITGA3/ITGB1/SDC1/SDC4 receptor axes in Ductal-T0 cells, which could activate TNF, NF-κB, TGF-β, and PI3K-AKT-signaling pathways to promote EMT. Pseudotime trajectory and velocity analyses suggested that Ductal-T0 cells exhibited the highest propensity to acquire myCAF-like features among all ductal subpopulations. Survival analysis revealed that an increased proportion of Ductal-T0 cells and elevated abundance of THBS2-ITGA3/ITGB1 and THBS2-SDC1 ligand–receptor pairs were significantly associated with poor prognosis. Spatial transcriptomics further revealed that myCAFs and Ductal-T0 cells co-localized at the tumor margin, which may contribute to reduced immune cell presence via dense extracellular matrix (ECM) barrier formation—a computationally inferred model of EMT-associated immune exclusion and metastatic progression—and identify THBS2 as a promising candidate for future therapeutic investigation to disrupt CAF–tumor crosstalk in PDAC. Full article

Breast cancer (BC) progression is strongly influenced by the extracellular matrix (ECM), whose remodelling regulates tumour growth, invasion, metastasis, immune modulation, and therapeutic response. Among ECM components, collagens have emerged as both structural proteins and active mediators of mechanotransduction, stromal interactions, and tumour cell behaviour. This narrative review analyses collagen families and collagen-associated proteins implicated in BC, integrating evidence on their expression patterns, biological functions, clinical significance, and translational potential. We examine fibrillar and non-fibrillar collagens, including fibril-associated collagens with interrupted triple helices (FACITs), membrane-associated collagens with interrupted triple helices (MACITs), basement membrane (BM) collagens, and multiplexins, together with their interactions with cancer-associated fibroblasts (CAFs), immune cells, and signalling pathways involved in tumour progression. Alterations in collagen composition, organization, crosslinking, and degradation regulate ECM stiffness, epithelial–mesenchymal transition (EMT), invasion, metastatic dissemination, and therapy resistance. Several collagen types and collagen-derived fragments also show promise as prognostic biomarkers and therapeutic targets, particularly in aggressive BC subtypes such as human epidermal growth factor receptor 2 (HER2)-positive and triple-negative breast cancer (TNBC). Overall, this review highlights the collagenome as a dynamic component of the breast tumour microenvironment (TME) and supports collagen-informed strategies for improved patient stratification and targeted therapies. Full article

Background: The aggressive progression of mesothelioma is driven not only by intrinsic tumor cell plasticity but also by dynamic interactions between tumor cells and the surrounding stromal microenvironment; however, the mechanisms by which stromal populations regulate epithelial–mesenchymal transition (EMT), tumor evolution, and therapeutic resistance remain unclear. Methods: We integrated longitudinal transcriptomic profiling with single-cell RNA sequencing in a murine intraperitoneal mesothelioma model spanning disease progression from week 0 to week 8 to identify stromal-EMT programs associated with tumor progression. In vitro fibroblast–tumor co-culture systems were used to assess how different fibroblast-to-tumor cell ratios influence transcriptional reprogramming and mesenchymal transition. Results: Single-cell analysis revealed marked stromal heterogeneity, identifying eight distinct cancer-associated fibroblast (CAF) subtypes: myCAF, mCAF, iCAF, TGF-βCAF, vCAF, plCAF, apCAF, and meCAF. These subsets showed specialized transcriptional programs associated with developmental signaling and metabolic adaptation. Functional analyses demonstrated coordinated intercellular communication across six interconnected modules, including mesenchymal transition, fibrotic remodeling, TGF-β/metabolic adaptation, adhesion signaling, WNT activation, and inflammatory crosstalk. Notably, mCAF, TGF-βCAF, and plCAF populations showed transcriptional convergence, suggesting cooperative formation of a desmoplastic, immunoregulatory niche. Co-culture experiments confirmed that fibroblast-derived signaling induces ratio-dependent transcriptional changes, promoting a shift from epithelioid to mesenchymal phenotypes. Conclusions: These findings highlight stromal regulation of EMT as a key driver of mesothelioma progression, sarcomatoid transition, and therapy resistance, and identify tumor–stroma signaling networks as potential therapeutic targets. Full article

Background: Although the tumor coagulome interacts with the tumor immune microenvironment (TME) in solid tumors, its role in osteosarcoma (OS) remains uncharacterized. This study aimed to delineate this transcriptomic interplay and identify potential prognostic targets. Methods: This study was performed with bulk RNA sequencing (RNA-seq), single-cell RNA sequencing (scRNA-seq), and clinical phenotype data. Bioinformatic approaches were employed at the transcriptomic level to investigate the impact of the tumor coagulome on the TME and prognosis in OS. We validated the above findings using immunohistochemistry and immunofluorescence. Results: The activity of a coagulation-related transcriptional signature was found to correlate with the degree of malignancy in OS. Its activity score demonstrated predictive value for OS prognosis, with a maximum area under the curve (AUC) of 0.802. scRNA-seq analysis indicated that inflammatory cancer-associated fibroblasts (iCAFs) and APOE⁺ macrophages were predominantly enriched in the high coagulation score subgroup. Our data further suggest that iCAFs may facilitate the M2 polarization of APOE⁺ macrophages via the C3–C3AR1 axis, potentially contributing to poorer clinical outcomes in patients with OS. Conclusions: These findings imply that within a high coagulation-related transcriptional score group, the interaction between iCAFs and APOE⁺ macrophages, likely mediated by the C3–C3AR1 axis, could facilitate OS progression. Consequently, the C3–C3AR1 signaling pathway might represent a promising target for future therapeutic strategies and coagulome monitoring in OS. Full article

Brain metastases have traditionally been investigated primarily with regard to interactions between tumor cells, the surrounding brain microenvironment, and associated inflammatory responses. By contrast, the presence of a true intratumoral stromal compartment in brain metastases has received much less attention, partly because the normal brain parenchyma lacks classical interstitial fibroblasts. However, recent histological, transcriptomic, and spatial studies suggest that at least a subset of carcinoma brain metastases contains fibroblast-like or cancer-associated fibroblast-like cells associated with collagen-rich extracellular matrix deposition. This raises a fundamental biological question: where do these cells come from? In this review, we discuss seven non-mutually exclusive hypotheses for the origin of cancer-associated fibroblast (CAF)-like cells in brain metastases, including pseudostromal mimics, meningeal or perivascular fibroblast-related cells, vascular mural cells, glial cells, cancer stem cell plasticity, tumor–stroma clusters, and circulating mesenchymal precursors. We compare the current findings for each hypothesis and highlight their major limitations. Overall, the available data support a heterogeneous and context-dependent model rather than a single universal origin. A better understanding of these stromal cell states may help refine the biological classification of brain metastases and support the future development of more targeted stromal therapies. Full article

Upper gastrointestinal (GI) cancers, including esophageal, gastric, and pancreatic cancers, remain among the most lethal malignancies worldwide, mainly because they resist nearly every therapeutic modality, from platinum-based chemotherapy, and anti-HER2 and anti-VEGF agents, to immune checkpoint inhibitors. Although tumor cell-intrinsic resistance is well characterized, an increasing share of treatment failure traces to the tumor microenvironment (TME), where cancer-associated fibroblasts (CAFs) and the extracellular matrix (ECM) act not as passive stroma but as active orchestrators of resistance. Here we argue that the functional heterogeneity of CAFs, spanning myofibroblastic (myCAF), inflammatory (iCAF), and antigen-presenting (apCAF) subtypes, and the desmoplastic ECM they construct converge on a small number of shared resistance programs. Those include paracrine signaling, metabolic reprogramming, extracellular vesicle (EV) transfer, and biomechanical remodeling that together drive chemoresistance, targeted therapy evasion, and immune exclusion. Emerging spatial multi-omics now resolves these programs to define niches within upper GI tumors, reframing resistance as a spatially organized property of the tissue rather than the tumor cell alone. We bring this evidence together and evaluate strategies aimed at CAF reprogramming and ECM normalization, arguing that spatially resolved targeting of the stroma represents a tractable path to overcoming resistance in these refractory cancers. Full article

Background: Lung adenocarcinoma (LUAD) develops through a stepwise pathological status from atypical adenomatous hyperplasia (AAH), adenocarcinoma in situ (AIS), and minimally invasive adenocarcinoma (MIA) to invasive adenocarcinoma (IA). Although malignant epithelial evolution during this process has been increasingly characterized, the dynamic remodeling of cancer-associated fibroblasts (CAFs) and their contribution to the immunosuppressive tumor microenvironment (TME) remain incompletely explored. Methods: Single-cell RNA sequencing data from treatment-naïve LUAD lesions, including AAH, AIS, MIA, and IA, were analyzed together with external bulk transcriptomic cohorts. CAF subsets were characterized according to their transcriptional features, inferred developmental states, transcription factor activity, functional programs, and predicted cell–cell interactions. Ligand–receptor analysis was used to examine MIF-related communication between epithelial cells and CAFs. MIF-related genes were then used to develop a machine learning-based prognostic signature in the TCGA-LUAD cohort, followed by validation in independent GEO cohorts. Results: Single-cell transcriptomic analysis of 131,639 cells from 25 treatment-naïve LUAD lesions identified six CAF subtypes, including alveolar CAFs, antigen-presenting CAFs, extracellular matrix CAFs, EndMT-like CAFs, inflammatory CAFs, and myofibroblastic CAFs. CAF composition differed across pathological stages, with MIA lesions showing a distinct enrichment of eCAFs and reduced proportions of inflammatory and myofibroblastic CAF populations. Compared with pre-invasive lesions, IA lesions exhibited increased proportions of exhausted CD4+ and CD8+ T cells together with reduced cytotoxic features. Cell–cell communication analysis identified enhanced epithelial–CAF interactions in IA, including enrichment of MIF-CD74/CD44 signaling. Based on MIF-related genes, a machine learning prognostic signature was developed and validated in independent cohorts, consistently stratifying patients into distinct risk groups with significantly different survival outcomes. Conclusions: These findings suggest that CAF-related stromal remodeling is associated with immune suppression during LUAD progression. MIF-mediated epithelial–CAF communication may be involved in the formation of an immunosuppressive microenvironment and is associated with poor prognosis. The MIF-related signature may provide a useful approach for prognostic stratification in LUAD. Full article

High-grade serous ovarian carcinoma (HGSOC) shows limited benefit from immune checkpoint blockade, partly because stromal barriers impair antitumor immunity. We developed a cancer-associated fibroblast (CAF)-associated mitochondrial metabolic and matrix-remodeling signature, termed CMMS, to characterize this immune-suppressive stromal state. CMMS integrated contractile/myCAF, extracellular matrix (ECM), and mitochondrial metabolic genes. Its clinical, metabolic, and immune relevance was evaluated in TCGA-HGSOC, independent GEO cohorts, single-cell RNA-seq datasets, and an anti-PD-L1-treated cohort, followed by cell–cell communication and experimental validation. LASSO-weighted CMMS stratified overall survival, with high CMMS indicating poorer prognosis. CMMS-high tumors exhibited ECM/TGFβ activation; associations with COL1A1, POSTN, and LOX; and a hypoxia-dominant metabolic phenotype. Mediation analysis suggested that hypoxia largely linked CMMS to glycolytic remodeling. Immune profiling revealed stromal-rich immune exclusion, checkpoint activation, and exhaustion-prone T-cell dysfunction. Single-cell analysis localized CMMS mainly to myCAF-like ECM-remodeling CAFs. In validation datasets, CMMS-high CAFs were associated with reduced CD8 abundance, increased CD8 exhaustion, and stronger matrix- and chemokine-related communication with T cells. Experiments further supported a link between TGFβ-related fibroblast activation, ECM-remodeling features, and impaired CD8⁺ T-cell effector function. Overall, CMMS defines a CAF-enriched fibrotic–hypoxic stromal program associated with immune exclusion-related features, exhaustion-prone T-cell dysfunction, and poor outcome in HGSOC. Full article

Introduction: Cutaneous T cell lymphoma (CTCL), most commonly known as mycosis fungoides (MF), is characterized by an increasingly immunosuppressive tumor microenvironment (TME) as the disease progresses. Cancer-associated fibroblasts (CAFs) are key stromal components that support a permissive niche, in part through the secretion of small extracellular vesicles (sEVs), predominantly exosomes, that mediate intercellular communication. We investigated the immunomodulatory role of exosome-enriched sEVs derived from MF fibroblasts (MF-Fs) compared to normal fibroblasts (N-Fs). Materials and Methods: Primary MF-Fs from early-stage MF biopsies and N-Fs from healthy skin were cultured in vitro. sEVs enriched with exosomes were isolated by ultracentrifugation and characterized by flow cytometry (CD81), electron microscopy, Nanosight analysis, and protein quantification, and their uptake by normal peripheral blood mononuclear cells (nPBMCs) was confirmed using PKH26-labeled sEVs. nPBMCs, monocytes, CD4⁺ and CD8⁺ T cells from healthy donors were exposed to MF-F or N-F sEVs. Cell viability was assessed using MTT and trypan blue exclusion assays. Mass cytometry (CyTOF) profiled immune subsets and regulatory proteins for preliminary observation. Monocyte polarization was evaluated by flow cytometry for M1 (CD80, CD86) and M2 (CD163, CD206) markers and PD-L1 expression; M1/M2-associated cytokines and sEV-microRNAs were quantified by qRT-PCR. Results: Both MF-F and N-F sEVs were internalized by nPBMCs and reduced their viability, with a more pronounced effect observed for MF-F sEVs. In nPBMCs, MF-F sEVs also increased the frequency of M2-like macrophages, decreased M1 polarization, and enhanced PD-L1 expression. In primary monocytes, MF-F- compared with N-F-derived sEVs upregulated M2-associated cytokines (IL-10, TGF-β), increased PD-L1 expression, and generated M2-like cells that suppressed CD4⁺ and CD8⁺ T cell viability. Conclusions: MF-F sEVs promote an immunosuppressive TME and represent potential therapeutic or biomarker targets in MF. Full article

Pancreatic ductal adenocarcinoma (PDAC) remains among the most therapeutically intractable malignancies, with a 5-year survival rate of approximately 10% and near-universal resistance to immune checkpoint inhibitor (ICI) therapy. This refractoriness arises from the convergence of pronounced intratumoral heterogeneity (ITH) and a profoundly immunosuppressive tumor microenvironment (TME), which together configure PDAC as a prototypical immune-excluded tumor. Beyond low tumor mutational burden, PDAC exhibits layered genetic, epigenetic, transcriptional, and metabolic heterogeneity that enables rapid adaptation and immune evasion under selective pressure, while dense desmoplastic stroma, cancer-associated fibroblasts (CAFs), and immunosuppressive immune populations collectively impose formidable physical and immunologic barriers to antitumor immunity. In this review, we synthesize multi-omics, spatial transcriptomic, and immunologic evidence to elucidate how ITH and the TME dynamically interact to reinforce immune resistance. We examine reciprocal crosstalk mechanisms—including immune-driven clonal selection, interclonal cooperation, metabolic niche specialization, and metabolic–epigenetic coupling—and discuss emerging platforms such as single-cell spatial omics, patient-derived organoid immune co-culture systems, and longitudinal circulating tumor DNA monitoring that enable high-resolution mapping of ITH–TME dynamics. Finally, we evaluate ITH–TME-guided combination therapeutic strategies targeting oncogenic drivers, stromal architecture, myeloid suppression, and metabolic checkpoints, and propose a prioritized framework for near-term and speculative clinical translation in PDAC. Full article

Cancer remains one of the most formidable health challenges worldwide. Extensive research has shown that tumor progression is not driven solely by malignant cells but is profoundly shaped by the tumor microenvironment (TME), which influences cancer initiation, immune evasion, and metastatic spread. Consequently, the TME has become an increasingly compelling therapeutic target. Nanotechnology has transformed cancer diagnostics and therapy, with metallic nanoparticles (mNPs) gaining particular attention due to their distinctive physicochemical properties and broad therapeutic potential. However, their interactions within the TME remain insufficiently understood, particularly with the non-cancerous cellular components, such as Cancer-Associated Fibroblasts (CAFs), Tumor-Associated Macrophages (TAMs), Dendritic Cells (DCs), Natural Killer (NK) cells, and T cells. Most existing reviews emphasize nanoparticle interactions with non-cellular TME components, such as the extracellular matrix, while far less attention has been given to their effects on cellular constituents (a gap this work specifically addresses). Although several molecular pathways through which mNPs modulate TME-resident cells have been identified, these likely represent only a small portion of the underlying mechanisms explored in this review. Progress in the field is further hindered by the limited availability of physiologically relevant experimental models; current in vitro and in vivo systems often fail to capture the complexity and dynamic heterogeneity of the TME. These limitations highlight the urgent need for more comprehensive and mechanistically grounded studies to validate the TME as a viable therapeutic target for nanoparticle-based cancer interventions. In particular, deeper insights into how mNPs influence immune regulation, stromal remodeling, and metabolic reprogramming within the TME will be essential for unlocking their full therapeutic potential in oncology. Full article

Fibroblast activation protein (FAP) has emerged as a promising target for the development of cancer radiotheranostics due to its selective overexpression in cancer-associated fibroblasts (CAFs) within the tumor stroma. Affinity and selectivity refer to the binding affinities of FAP inhibitors toward FAP and related family members, whereas the accumulation of radiolabeled-FAP inhibitors varies by tumor type. Although monomeric FAP inhibitors (FAPIs) have shown extraordinary utility in diagnostic imaging, their clinical application in radiotherapy has been limited by short tumor retention times and heterogeneous uptake. To address these challenges, homomultimeric FAPI ligands—featuring two or more identical FAP-targeting motifs—have been developed with the aim of enhancing binding avidity and prolonging tumor residence. This review comprehensively examines the evolution of homomultimeric FAPI ligands, from molecular design and preclinical validation to early clinical implementation. We highlight how dimeric and higher-order multimeric constructs improve tumor retention and therapeutic efficacy compared to monomers, while also discussing the impact of linker chemistry, valency, and scaffold architecture on pharmacokinetics and targeting efficiency. Preclinical studies demonstrate that optimized dimers and trimers achieve superior tumor-to-background ratios and sustained tumor uptake, whereas excessive multimerization can lead to steric hindrance and reduced efficacy. Clinical data from pioneering studies using agents such as [¹⁷⁷Lu]Lu-DOTAGA.(SA.FAPi)₂ and [¹⁷⁷Lu]Lu-DOTAGA.Glu.(FAPi)₂ confirm prolonged tumor retention, encouraging therapeutic responses and a favorable safety profile in advanced cancers. However, translational challenges remain, including the need for better preclinical models that reflect stromal FAP heterogeneity, optimized radiometal–chelator pairs, and standardized dosing protocols for comparative clinical trials. Overall, homomultimeric FAPI ligands represent a significant advance in FAP-targeted theranostics, offering a robust platform for personalized cancer management. Full article