Fibroblastic FAP promotes intrahepatic cholangiocarcinoma growth via MDSCs recruitment

Fufang-Biejia-Ruangan tablet targeting both cancer-associated fibroblasts and tumor cells by HIPPO-PI3K/AKT cascades in intrahepatic cholangiocarcinoma treatment

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) ranks second among primary liver cancers in terms of prevalence, characterized by poor prognosis and scarce therapeutic interventions. Fufang-Biejia-Ruangan tablet (BJRG), a traditional Chinese herbal remedy, has been widely used for liver diseases. However, its therapeutic efficacy and underlying mechanisms in ICC remain poorly understood.

AIM OF THE STUDY

This study aims to systematically investigate the anti-ICC effects of BJRG, focusing on tumor progression and microenvironment modulation, through experimental and transcriptomic analyses.

METHODS

The chemical composition of BJRG was analyzed employing ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). In vitro assays were performed with QBC939 and LX-2 cell lines. Two primary ICC models (AKT/YAP and sgP53/KRAS) were established via hydrodynamic tail-vein injection of corresponding plasmids. A co-culture system for subcutaneous tumor formation was developed using cancer-associated fibroblasts (CAFs) derived from the AKT/YAP model and primary tumor cells derived from the sgP53/KRAS model.

RESULTS

UPLC-MS analysis identified 1091 chemical components, primarily terpenoids, sugars, glycosides, and phenylpropanoids. The therapeutic efficacy of BJRG was evaluated for the treatment of ICC. BJRG treatment slowed down the growth of both human ICC cell lines and AKT/YAP ICC mouse model. Mechanistically, BJRG inhibited HIPPO-PI3K/AKT signaling pathway in ICC tumor cells. Importantly, BJRG significantly inhibited the growth of CAFs via HIPPO-PI3K/AKT cascades. Of note, co-culture CAFs with ICC cell lines substantially sensitized the efficacy of BJRG in sgP53/KRAS syngeneic tumor model. Furthermore, BJRG therapy not only affected CAFs but also induced alterations in vascular structures and hypoxic conditions within lesions in the AKT/YAP model. This intervention promoted the infiltration of T lymphocytes and macrophages into the tumor microenvironment, which may further augment the anti-proliferative effects of BJRG by enhancing the immune response within ICC tumor tissues.

CONCLUSION

Our research demonstrates BJRG's anti-ICC efficacy via diverse pathways, including the suppression of tumor cell proliferation, regulation of CAFs activity, and promotion of immune cell infiltration. These findings underscore BJRG as a promising therapeutic candidate for ICC, offering novel mechanistic insights and highlighting its potential for clinical translation.

The important role of myeloid-derived suppressor cells: From hepatitis to liver cancer

Liver homeostasis is coordinated by crosstalk between resident and infiltrating inflammatory cells. Liver disease creates a dynamic inflammatory microenvironment characterized by aberrant metabolism and continuous hepatic regeneration, making it an important risk factor for hepatocellular carcinoma (HCC) as well as liver failure. Recent studies have revealed a critical heterogeneous population of myeloid-derived suppressor cells (MDSCs), which influence liver disease progression and malignancy by dynamically regulating the immune microenvironment. MDSCs play an important role in preventing excessive immune responses in the liver. However, MDSCs are also associated with the promotion of liver injury and liver cancer progression. The plasticity of MDSCs in liver disease is a unique challenge for therapeutic intervention strategies and requires a deeper understanding of the underlying mechanisms. Here, we review the role of MDSCs in the establishment and progression of liver disease and highlight the evidence for MDSCs as a priority target for current and future therapeutic strategies. We explore the fate of MDSCs from hepatitis to liver cancer, providing recent insights into potential targets for clinical intervention.

Genetic, Epigenetic, and Microenvironmental Drivers of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive and heterogeneous malignancy of the biliary tree that carries a poor prognosis. Multiple features at the genetic, epigenetic, and microenvironmental levels have been identified to better characterize CCA carcinogenesis. Genetic alterations, such as mutations in IDH1/2, BAP1, ARID1A, and FGFR2, play significant roles in CCA pathogenesis, with variations across different subtypes, races/ethnicities, and causes. Epigenetic dysregulation, characterized by DNA methylation and histone modifications, further contributes to the complexity of CCA, influencing gene expression and tumor behavior. Furthermore, CCA cells exchange autocrine and paracrine signals with other cancer cells and the infiltrating cell types that populate the microenvironment, including cancer-associated fibroblasts and tumor-associated macrophages, further contributing to an immunosuppressive niche that supports tumorigenesis. This review explores the multifaceted genetic, epigenetic, and microenvironmental drivers of CCA. Understanding these diverse mechanisms is essential for characterizing the complex pathways of CCA carcinogenesis and developing targeted therapies to improve patient outcomes.

FAP upregulates PD-L1 expression in cancer-associated fibroblasts to exacerbate T cells dysfunction and suppress anti-tumor immunity

FAP-positive cancer-associated fibroblasts (CAFs), recognized as a critical subset of CAFs, have been implicated in fostering an immunosuppressive tumor microenvironment in various cancers. However, their potential mechanisms of immunosuppression, particularly in modulating T cells, remain elusive. In this study, multiple internal cohorts consisting of 328 patients as well as 5 external cohorts were integrated to delineate the association between unfavorable prognosis or therapeutic resistance and FAP+ CAFs in gastric cancer patients. Subsequently, using in vivo mice models and in vitro co-culture system, we found that elevated infiltration levels of FAP+ CAF exacerbated immunosuppression in the tumor microenvironment by facilitating CD8+ T cells dysfunction. Mechanistically, FAP impeded the degradation of STAT1 protein in CAFs, thereby sustaining PD-L1 transcription and fostering T cell exhaustion. Treatment with PD-L1 neutralizing antibodies effectively attenuated FAP-mediated immunosuppression, restoring anti-tumor immunity of T cells. Overall, our findings underscore the vital role of FAP+ CAFs in directly suppressing T cell-mediated anti-tumor immunity via PD-L1 upregulation, paving the way for the development of FAP-targeted therapies in clinical settings.

Inflammation and Immunity in Liver Neoplasms: Implications for Future Therapeutic Strategies

Over the past two decades, the "hallmarks of cancer" have revolutionized cancer research and highlighted the crucial roles of inflammation and immunity. Protumorigenic inflammation promotes cancer development along with inhibition of antitumor immunity, shaping the tumor microenvironment (TME) toward a tumor-permissive state and further enhancing the malignant potential of cancer cells. This immunosuppressive TME allows tumors to evade immunosurveillance. Thus, understanding the complex interplay between tumors and the immune system within the TME has become pivotal, especially with the advent of immunotherapy. Although immunotherapy has achieved notable success in many malignancies, primary liver cancer, particularly hepatocellular carcinoma, presents unique challenges. The hepatic immunosuppressive environment poses obstacles to the effectiveness of immunotherapy, along with high mortality rates and limited treatment options for patients with liver cancer. In this review, we discuss current understanding of the complex immune-mediated mechanisms underlying liver neoplasms, focusing on hepatocellular carcinoma and liver metastases. We describe the molecular and cellular heterogeneity within the TME, highlighting how this presents unique challenges and opportunities for immunotherapy in liver cancers. By unraveling the immune landscape of liver neoplasms, this review aims to contribute to the development of more effective therapeutic interventions, ultimately improving clinical outcomes for patients with liver cancer.

The Immune-Genomics of Cholangiocarcinoma: A Biological Footprint to Develop Novel Immunotherapies

Cholangiocarcinoma (CCA) represents approximately 3% of all gastrointestinal cancers and is a highly heterogeneous and aggressive malignancy originating from the epithelial cells of the biliary tree. CCA is classified by anatomical location into intrahepatic (iCCA), extrahepatic (eCCA), gallbladder cancer (GBC), and ampullary cancers. Although considered a rare tumor, CCA incidence has risen globally, particularly due to the increased diagnosis of iCCA. Genomic and immune profiling studies have revealed significant heterogeneity within CCA, leading to the identification of molecular subtypes and actionable genetic alterations in 40-60% of cases, particularly in iCCA. Among these, FGFR2 rearrangements or fusions (7-15%) and IDH1 mutations (10-20%) are common in iCCA, while HER2 amplifications/overexpression are more frequent in eCCA and GBC. The tumor-immune microenvironment (TIME) of CCAs plays an active role in the pathogenesis and progression of the disease, creating a complex and plastic environment dominated by immune-suppressive populations. Among these, cancer-associated fibroblasts (CAFs) are a key component of the TIME and are associated with worse survival due to their role in maintaining a poorly immunogenic landscape through the deposition of stiff extracellular matrix and release of pro-tumor soluble factors. Improved understanding of CCA tumor biology has driven the development of novel treatments. Combination therapies of cisplatin and gemcitabine with immune checkpoint inhibitors (ICIs) have replaced the decade-long standard doublet chemotherapy, becoming the new standard of care in patients with advanced CCA. However, the survival improvements remain modest prompting research into more effective ways to target the TIME of CCAs. As key mechanisms of immune evasion in CCA are uncovered, novel immune molecules emerge as potential therapeutic targets. Current studies are exploring strategies targeting multiple immune checkpoints, angiogenesis, and tumor-specific antigens that contribute to immune escape. Additionally, the success of ICIs in advanced CCA has led to interest in their application in earlier stages of the disease, such as in adjuvant and neoadjuvant settings. This review offers a comprehensive overview of the immune biology of CCAs and examines how this knowledge has guided clinical drug development, with a focus on both approved and emergent treatment strategies.

Identification of Immune Infiltration-Associated CC Motif Chemokine Ligands as Biomarkers and Targets for Colorectal Cancer Prevention and Immunotherapy

Colorectal cancer (CRC) is the third most common cancer globally, with limited effective biomarkers and sensitive therapeutic targets. An increasing number of studies have highlighted the critical role of tumor microenvironment (TME) imbalances, particularly immune escape due to impaired chemokine-mediated trafficking, in tumorigenesis and progression. Notably, CC chemokines (CCLs) have been shown to either promote or inhibit angiogenesis, metastasis, and immune responses in tumors, thereby influencing cancer development and patient outcomes. However, the diagnostic and prognostic significance of CCLs in CRC remains unclear. In this study, multiple online tools for bioinformatics analyses were utilized. The findings revealed that the mRNA expression levels of CCL3, CCL4, and CCL26 were significantly elevated in CRC tissues compared to normal tissues, whereas CCL2, CCL5, CCL11, CCL21, and CCL28 mRNA levels were markedly downregulated. Additionally, dysregulation of CCL4, CCL5, and CCL21 was strongly associated with clinical staging, and elevated levels of CCL4, CCL11, and CCL28 were linked to significantly prolonged survival in CRC patients. Functional enrichment analysis indicated that the cellular roles of CCLs were predominantly associated with the chemokine, Wnt, and Toll-like receptor signaling pathways, as well as protein kinase activity. Furthermore, transcriptional regulation of most CCLs involved RELA and NFKB1. Key downstream targets included members of the SRC family of tyrosine kinases (HCK, LYN, and LCK), serine/threonine kinases (ATR and ATM), and others such as CSNK1G2, NEK2, and CDK2. Moreover, CCLs (CCL2, CCL3, CCL4, CCL5, CCL11, CCL21, and CCL28) exhibited strong correlations with major infiltration-related immune cells, including B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells. In conclusion, our study provides novel insights into the potential utility of CCLs as biomarkers and therapeutic targets for CRC prevention and immunotherapy.

Cancer-associated fibroblasts as therapeutic targets for cancer: advances, challenges, and future prospects

Research into cancer treatment has been mainly focused on developing therapies to directly target cancer cells. Over the past decade, extensive studies have revealed critical roles of the tumour microenvironment (TME) in cancer initiation, progression, and drug resistance. Notably, cancer-associated fibroblasts (CAFs) have emerged as one of the primary contributors in shaping TME, creating a favourable environment for cancer development. Many preclinical studies have identified promising targets on CAFs, demonstrating remarkable efficacy of some CAF-targeted treatments in preclinical models. Encouraged by these compelling findings, therapeutic strategies have now advanced into clinical evaluation. We aim to provide a comprehensive review of relevant subjects on CAFs, including CAF-related markers and targets, their multifaceted roles, and current landscape of ongoing clinical trials. This knowledge can guide future research on CAFs and advocate for clinical investigations targeting CAFs.

Systematic review and meta-analysis of the prognostic role of fibroblast-activation protein in gastrointestinal cancers

Background

Gastrointestinal (GI) cancers, particularly pancreatic cancer, are characterized by a dense stromal tumor microenvironment where cancer-associated fibroblasts (CAFs) predominate. CAFs comprise highly heterogeneous subpopulations with different functions, which can be both tumor-promoting and tumor-restraining. This systematic review and meta-analysis aims to comprehensively assess the impact of the CAF marker fibroblast-activation protein (FAP) expression on clinical outcomes in GI cancers.

Methods

Adhering to PRISMA guidelines, we systematically searched PubMed/MEDLINE, Web of Science, Cochrane Library, and ClinicalTrials.gov for relevant articles. Inclusion criteria involved studies comparing GI cancer patients with and without FAP overexpression. Meta-analysis evaluated overall survival (OS), histological differentiation, local tumor invasion, lymph node metastases, and distant metastases. For each observational study, the risk of bias was assessed using the risk of bias in non-randomized studies of exposure (ROBINS-E) tool.

Results

The meta-analysis included 31 cohort studies from six countries, comprising 3,976 patients. Patients without FAP overexpression exhibited a favorable OS [hazard ratio (HR) =1.74; 95% confidence interval (CI): 1.51-2.01]. Subgroup analyses revealed consistent results across esophageal, pancreatic, colorectal, and gastric cancers. While one-year survival rates showed no significant difference, subsequent years displayed lower rates for FAP-overexpressing groups. Lymph node metastases were more frequent in FAP-overexpressing patients, whereas distant metastases did not differ. None of 31 studies systematically controlled confounding and adjusted data so that all studies were categorized as "high risk of bias" for the domain "risk of bias due to confounding". For domains "risk of bias arising from measurement of exposure", "risk of bias due to post-exposure interventions", "risk of bias arising from measurement of outcomes", and "risk of bias in selection of the reported result", all studies were categorized as "low risk of bias".

Conclusions

This meta-analysis underscores the potential adverse prognostic significance of FAP expression in GI cancers. Limitations include heterogeneity in FAP expression cutoffs and definitions. Future research should focus on delineating the precise roles and clinical implications of FAP in GI cancers.

The Immune Landscape and Its Potential for Immunotherapy in Advanced Biliary Tract Cancer

Biliary tract cancers (BTC) are a highly heterogeneous group of cancers at the genomic, epigenetic and molecular levels. The vast majority of patients initially present at an advanced (unresectable) disease stage due to a lack of symptoms and an aggressive tumour biology. Chemotherapy has been the mainstay of treatment in patients with advanced BTC but the survival outcomes and prognosis remain poor. The addition of immune checkpoint inhibitors (ICI) to chemotherapy have shown only a marginal benefit over chemotherapy alone due to the complex tumour immune microenvironment of these cancers. This review appraises our current understanding of the immune landscape of advanced BTC, including emerging transcriptome-based classifications, highlighting the mechanisms of immune evasion and resistance to ICI and their therapeutic implications. It describes the shifting treatment paradigm from traditional chemotherapy to immunotherapy combinations as well as the potential biomarkers for predicting response to ICI.

Immunohistochemical basis for FAP as a candidate theranostic target across a broad range of cholangiocarcinoma subtypes

Purpose

The aims of this study were to evaluate and compare fibroblast activation protein (FAP) expression and localization in surgically resected cholangiocarcinoma (CCA), primary and metastatic hepatocellular carcinoma (HCC), hepatocellular adenoma (HCA), and focal nodular hyperplasia (FNH), and to identify any association between CCA clinical or pathologic features and FAP expression.

Materials and methods

FAP immunostaining from surgically resected CCA (N = 58), primary intrahepatic and extrahepatic metastatic HCC (N = 148), HCA (N26), and FNH (N = 19) was scored (negative, weak positive, moderate positive or strong positive) from tissue microarrays. FAP expression was compared between groups. CCA FAP expression was compared to clinical and tumor pathology features.

Results

Moderate-strong FAP expression in the tumor stroma was present in 93.1% of CCA, 60.7% of extrahepatic metastatic HCC, 29.6% of primary HCC, 21.1% of FNH, and 11.6% of HCA. Moderate-strong FAP expression in tumor stroma was significantly more prevalent in CCA than HCC (p < 0.001), metastatic HCC (p = 0.005), HCA (p < 0.001) and FNH (p < 0.001). FAP was expressed in the stroma of all but one CCA (1.7%), and FAP expression in CCA tumor stroma was not associated with any clinical or tumor pathology features (p > 0.05, all).

Conclusion

FAP is expressed in the stroma of a high proportion (93%) of primary CCA independent of patient clinical or tumor pathology features. As such, these data provide the tissue basis for systematically evaluating FAP as a theranostic target across a broad range of CCA subtypes.

Prognostic impact of the tumour microenvironment in intrahepatic cholangiocarcinoma: identification of a peritumoural fibro-immune interface

The tumour microenvironment (TME) of intrahepatic cholangiocarcinoma (iCCA) is complex and plays a role in prognosis and resistance to treatments. We aimed to decipher the iCCA TME phenotype using multiplex sequential immunohistochemistry (MS-IHC) to investigate which cell types and their spatial location may affect its prognosis. This was a retrospective study of 109 iCCA resected samples. For all cases, we used an open-source software to analyse a panel of markers (αSMA, FAP, CD8, CD163) by MS-IHC for characterize the different TME cells and their location. RNA sequencing was performed to determine the main iCCA transcriptomic classes. The association of the TME composition with overall survival (OS) was assessed by univariate and multivariate analyses. A high proportion of activated fibroblasts (FAP +) was significantly associated with poor OS (HR = 2.33, 95%CI = 1.43-3.81, p = 0.001). CD8 T lymphocytes excluded from the epithelial compartment were significantly associated with worse OS (HR = 1.86, 95% CI = 1.07-3.22, p = 0.014). The combination of a high proportion of FAP + fibroblasts and CD8 T lymphocytes excluded from the epithelial compartment, observed in 21 cases (19%), was significantly associated with poor OS on univariate (HR = 2.49, 95% CI = 1.44-4.28, p = 0.001) and multivariate analyses (HR = 2.77, 95% CI = 1.56-4.92, p < 0.001). In these cases, CD8 T lymphocytes were predominantly located at the tumour/non-tumour interface (19/21, 90%), and an association with the transcriptomic inflammatory stroma class was observed (10/21, 48%). Our results confirm the TME prognostic role in iCCA, highlighting the impact in the process of spatial heterogeneity, especially cell colocalization of immune and fibroblastic cells creating a peritumoural fibro-immune interface.

Extracellular vesicles reshape the tumor microenvironment to improve cancer immunotherapy: Current knowledge and future prospects

Tumor immunotherapy has revolutionized cancer treatment, but limitations remain, including low response rates and immune complications. Extracellular vesicles (EVs) are emerging as a new class of therapeutic agents for various diseases. Recent research shows that changes in the amount and composition of EVs can reshape the tumor microenvironment (TME), potentially improving the effectiveness of immunotherapy. This exciting discovery has sparked clinical interest in using EVs to enhance the immune system's response to cancer. In this Review, we delve into the world of EVs, exploring their origins, how they're generated, and their complex interactions within the TME. We also discuss the crucial role EVs play in reshaping the TME during tumor development. Specifically, we examine how their cargo, including molecules like PD-1 and non-coding RNA, influences the behavior of key immune cells within the TME. Additionally, we explore the current applications of EVs in various cancer therapies, the latest advancements in engineering EVs for improved immunotherapy, and the challenges faced in translating this research into clinical practice. By gaining a deeper understanding of how EVs impact the TME, we can potentially uncover new therapeutic vulnerabilities and significantly enhance the effectiveness of existing cancer immunotherapies.

Development and validation of a stromal-immune signature to predict prognosis in intrahepatic cholangiocarcinoma

BACKGROUNDS/AIMS

Intrahepatic cholangiocarcinoma (ICC) is a highly desmoplastic tumor with poor prognosis even after curative resection. We investigated the associations between the composition of the ICC stroma and immune cell infiltration and aimed to develop a stromal-immune signature to predict prognosis in surgically treated ICC.

METHODS

We recruited 359 ICC patients and performed immunohistochemistry to detect α-smooth muscle actin (α-SMA), CD3, CD4, CD8, Foxp3, CD68, and CD66b. Aniline was used to stain collagen deposition. Survival analyses were performed to detect prognostic values of these markers. Recursive partitioning for a discrete-time survival tree was applied to define a stromal-immune signature with distinct prognostic value. We delineated an integrated stromal-immune signature based on immune cell subpopulations and stromal composition to distinguish subgroups with different recurrence-free survival (RFS) and overall survival (OS) time.

RESULTS

We defined four major patterns of ICC stroma composition according to the distributions of α-SMA and collagen: dormant (α-SMAlow/collagenhigh), fibrogenic (α-SMAhigh/collagenhigh), inert (α-SMAlow/collagenlow), and fibrolytic (α-SMAhigh/collagenlow). The stroma types were characterized by distinct patterns of infiltration by immune cells. We divided patients into six classes. Class I, characterized by high CD8 expression and dormant stroma, displayed the longest RFS and OS, whereas Class VI, characterized by low CD8 expression and high CD66b expression, displayed the shortest RFS and OS. The integrated stromal-immune signature was consolidated in a validation cohort.

CONCLUSION

We developed and validated a stromal-immune signature to predict prognosis in surgically treated ICC. These findings provide new insights into the stromal-immune response to ICC.

Exploring the role of the immune microenvironment in hepatocellular carcinoma: Implications for immunotherapy and drug resistance

Hepatocellular carcinoma (HCC), the most common type of liver tumor, is a leading cause of cancer-related deaths, and the incidence of liver cancer is still increasing worldwide. Curative hepatectomy or liver transplantation is only indicated for a small population of patients with early-stage HCC. However, most patients with HCC are not candidates for radical resection due to disease progression, leading to the choice of the conventional tyrosine kinase inhibitor drug sorafenib as first-line treatment. In the past few years, immunotherapy, mainly immune checkpoint inhibitors (ICIs), has revolutionized the clinical strategy for HCC. Combination therapy with ICIs has proven more effective than sorafenib, and clinical trials have been conducted to apply these therapies to patients. Despite significant progress in immunotherapy, the molecular mechanisms behind it remain unclear, and immune resistance is often challenging to overcome. Several studies have pointed out that the complex intercellular communication network in the immune microenvironment of HCC regulates tumor escape and drug resistance to immune response. This underscores the urgent need to analyze the immune microenvironment of HCC. This review describes the immunosuppressive cell populations in the immune microenvironment of HCC, as well as the related clinical trials, aiming to provide insights for the next generation of precision immunotherapy.

Focusing on the Immune Cells: Recent Advances in Immunotherapy for Biliary Tract Cancer

Biliary tract cancer (BTC) represents a challenging malignancy characterized by aggressive behavior, high relapse rates, and poor prognosis. In recent years, immunotherapy has revolutionized the treatment landscape for various cancers, but its efficacy in BTC remains limited. This article provides a comprehensive overview of the advances in preclinical and clinical studies of immunotherapy for BTC. We explore the potential of immune checkpoint inhibitors in reshaping the management of BTC. Despite disappointing results thus far, ongoing clinical trials are investigating the combination of immunotherapy with other treatment modalities. Furthermore, research on the tumor microenvironment has unveiled novel targets for immunotherapeutic interventions. By understanding the current state of immunotherapy in BTC and highlighting future directions, this article aims to fuel further exploration and ultimately improve patient outcomes in this challenging disease.

Mesenchymal Stromal Cells Increase the Natural Killer Resistance of Circulating Tumor Cells via Intercellular Signaling of cGAS-STING-IFNβ-HLA

Circulating tumor cells (CTCs) shed from primary tumors must overcome the cytotoxicity of immune cells, particularly natural killer (NK) cells, to cause metastasis. The tumor microenvironment (TME) protects tumor cells from the cytotoxicity of immune cells, which is partially executed by cancer-associated mesenchymal stromal cells (MSCs). However, the mechanisms by which MSCs influence the NK resistance of CTCs remain poorly understood. This study demonstrates that MSCs enhance the NK resistance of cancer cells in a gap junction-dependent manner, thereby promoting the survival and metastatic seeding of CTCs in immunocompromised mice. Tumor cells crosstalk with MSCs through an intercellular cGAS-cGAMP-STING signaling loop, leading to increased production of interferon-β (IFNβ) by MSCs. IFNβ reversely enhances the type I IFN (IFN-I) signaling in tumor cells and hence the expression of human leukocyte antigen class I (HLA-I) on the cell surface, protecting the tumor cells from NK cytotoxicity. Disruption of this loop reverses NK sensitivity in tumor cells and decreases tumor metastasis. Moreover, there are positive correlations between IFN-I signaling, HLA-I expression, and NK tolerance in human tumor samples. Thus, the NK-resistant signaling loop between tumor cells and MSCs may serve as a novel therapeutic target.

Overcoming Resistance to Immune Checkpoint Blockade in Liver Cancer with Combination Therapy: Stronger Together?

Primary liver cancer, represented mainly by hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (CCA), is one of the most common and deadliest tumors worldwide. While surgical resection or liver transplantation are the best option in early disease stages, these tumors often present in advanced stages and systemic treatment is required to improve survival time. The emergence of immune checkpoint inhibitor (ICI) therapy has had a positive impact especially on the treatment of advanced cancers, thereby establishing immunotherapy as part of first-line treatment in HCC and CCA. Nevertheless, low response rates reflect on the usually cold or immunosuppressed tumor microenvironment of primary liver cancer. In this review, we aim to summarize mechanisms of resistance leading to tumor immune escape with a special focus on the composition of tumor microenvironment in both HCC and CCA, also reflecting on recent important developments in ICI combination therapy. Furthermore, we discuss how combination of ICIs with established primary liver cancer treatments (e.g. multikinase inhibitors and chemotherapy) as well as more complex combinations with state-of-the-art therapeutic concepts may reshape the tumor microenvironment, leading to higher response rates and long-lasting antitumor immunity for primary liver cancer patients.

Heterogeneity, crosstalk, and targeting of cancer-associated fibroblasts in cholangiocarcinoma

Cholangiocarcinoma (CCA) comprises diverse tumors of the biliary tree and is characterized by late diagnosis, short-term survival, and chemoresistance. CCAs are mainly classified according to their anatomical location and include diverse molecular subclasses harboring inter-tumoral and intratumoral heterogeneity. Besides the tumor cell component, CCA is also characterized by a complex and dynamic tumor microenvironment where tumor cells and stromal cells crosstalk in an intricate network of interactions. Cancer-associated fibroblasts, one of the most abundant cell types in the tumor stroma of CCA, are actively involved in cholangiocarcinogenesis by participating in multiple aspects of the disease including extracellular matrix remodeling, immunomodulation, neo-angiogenesis, and metastasis. Despite their overall tumor-promoting role, recent evidence indicates the presence of transcriptional and functional heterogeneous CAF subtypes with tumor-promoting and tumor-restricting properties. To elucidate the complexity and potentials of cancer-associated fibroblasts as therapeutic targets in CCA, this review will discuss the origin of cancer-associated fibroblasts, their heterogeneity, crosstalk, and role during tumorigenesis, providing an overall picture of the present and future perspectives toward cancer-associated fibroblasts targeting CCA.

Disruption of LPA-LPAR1 pathway results in lung tumor growth inhibition by downregulating B7-H3 expression in fibroblasts

BACKGROUND

Lysophosphatidic acids (LPAs) belong to a class of bioactive lysophospholipids with multiple functions including immunomodulatory roles in tumor microenvironment (TME). LPA exerts its biological effects via its receptors that are highly expressed in fibroblasts among other cell types. As cancer-associated fibroblasts (CAFs) are a key component of the TME, it is important to understand LPA signaling and regulation of receptors in fibroblasts or CAFs and associated regulatory roles on immunomodulation-related molecules.

METHODS

Cluster analysis, immunoblotting, real-time quantitative-PCR, CRISPR-Cas9 gene editing system, immunohistochemical staining, coculture model, and in vivo xenograft model were used to investigate the effects of LPA-LPAR1 on B7-H3 in tumor promotion of CAFs.

RESULTS

In this study, we found that LPAR1 and CD276 (B7-H3) were generally highly expressed in fibroblasts with good expression correlation. LPA induced B7-H3 up-expression through LPAR1, and stimulated fibroblasts proliferation that could be inhibited by silencing LPAR1 or B7-H3 as well as small molecule LPAR1 antagonist (Ki16425). Using engineered fibroblasts and non-small cell lung carcinoma (NSCLC) cell lines, subsequent investigations demonstrated that CAFs promoted the proliferation of NSCLC in vitro and in vivo, and such effect could be inhibited by knocking out LPAR1 or B7-H3.

CONCLUSION

The present study provided new insights for roles of LPA in CAFs, which could lead to the development of innovative therapies targeting CAFs in the TME. It is also reasonable to postulate a combinatory approach to treat malignant fibrous tumors (such as NSCLC) with LPAR1 antagonists and B7-H3 targeting therapies.

The Roles of Myeloid-Derived Suppressor Cells in Liver Disease

Liver disease-related mortality is a major cause of death worldwide. Hepatic innate and adaptive immune cells play diverse roles in liver homeostasis and disease. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells. MDSCs can be broadly divided into monocytic MDSCs and polymorphonuclear or granulocytic MDSCs, and they functionally interact with both liver parenchymal and nonparenchymal cells, such as hepatocytes and regulatory T cells, to impact liver disease progression. The infiltration and activation of MDSCs in liver disease can be regulated by inflammatory chemokines and cytokines, tumor-associated fibroblasts, epigenetic regulation factors, and gut microbiota during liver injury and cancer. Given the pivotal roles of MDSCs in advanced liver diseases, they can be targeted to treat primary and metastatic liver cancer, liver generation, alcoholic and nonalcoholic liver disease, and autoimmune hepatitis. Currently, several treatments such as the antioxidant and anti-inflammatory agent berberine are under preclinical and clinical investigation to evaluate their therapeutic efficacy on liver disease and their effect on MDSC infiltration and function. Phenotypic alteration of MDSCs in different liver diseases that are in a model-dependent manner and lack special markers for distinct MDSCs are challenges for targeting MDSCs to treat liver disease. Multi-omics study is an option to uncover the features of disease-specific MDSCs and potential gene or protein targets for liver disease treatment. In summary, MDSCs play important roles in the pathogenesis and progression of liver disease by regulating both intrahepatic innate and adaptive immune responses.

The role of extracellular vesicles in cholangiocarcinoma tumor microenvironment

Cholangiocarcinoma (CCA) is a highly aggressive malignant tumor that originates from the biliary system. With restricted treatment options at hand, the challenging aspect of early CCA diagnosis leads to a bleak prognosis. Besides the intrinsic characteristics of tumor cells, the generation and progression of CCA are profoundly influenced by the tumor microenvironment, which engages in intricate interactions with cholangiocarcinoma cells. Of notable significance is the role of extracellular vesicles as key carriers in enabling communication between cancer cells and the tumor microenvironment. This review aims to provide a comprehensive overview of current research examining the interplay between extracellular vesicles and the tumor microenvironment in the context of CCA. Specifically, we will emphasize the significant contributions of extracellular vesicles in molding the CCA microenvironment and explore their potential applications in the diagnosis, prognosis assessment, and therapeutic strategies for this aggressive malignancy.

Igniting cold tumors of intrahepatic cholangiocarcinoma: An insight into immune evasion and tumor immune microenvironment

<p>Intrahepatic cholangiocarcinoma (ICC) is a rare hepatobiliary cancer that originates from the epithelium of the intrahepatic bile duct. The various treatments for ICC, such as chemotherapy, radiotherapy, and locoregional therapy, confer only modest improvements in survival rates. Immunotherapy, although revolutionary in cancer treatment, has found limited application in the treatment of ICCs due to the “cold” nature of these tumors, which is marked by scant T-cell infiltration. This characteristic makes immune checkpoint inhibitors (ICIs) unsuitable for the majority of ICC patients. Therefore, comprehensively understanding the mechanisms underlying these “cold” tumors is crucial for harnessing the potential of immunotherapy for treating ICC patients. This paper explores immune evasion mechanisms and the complex tumor immune microenvironment of ICC. This study provides a comprehensive overview of therapeutic strategies aimed at activating cold tumors and enhancing their immunogenicity. Furthermore, potential and promising targets for cancer vaccines and adoptive cellular therapy in the context of ICC are discussed. This endeavor strives to reveal new pathways for innovative immunotherapy strategies, with a focus on overcoming the key challenge of triggering an effective immune response in ICC patients.</p>

The Tumor Immune Microenvironment plays a Key Role in Driving the Progression of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is an epithelial cancer distinguished by bile duct cell differentiation and is also a fibroproliferative tumor. It is characterized by a dense mesenchyme and a complex tumor immune microenvironment (TME). The TME comprises both cellular and non-cellular components. The celluar component includes CCA cells, immune cells and mesenchymal cells represented by the cancer-associated fibroblasts (CAFs), while the non-cellular component is represented by mesenchymal elements such as the extracellular matrix (ECM). Recent studies have demonstrated the important role of the TME in the development, progression, and treatment resistance of CCA. These cell-associated prognostic markers as well as intercellular connections, may serve as potential therapeutic targets and could inspire new treatment approaches for CCA in the future. This paper aims to summarize the current understanding of CCA's immune microenvironment, focusing on immune cells, mesenchymal cells, ECM, intercellular interactions, and metabolism within the microenvironment.

FAP expression in adipose tissue macrophages promotes obesity and metabolic inflammation

Adipose tissue macrophages (ATM) are key players in the development of obesity and associated metabolic inflammation which contributes to systemic metabolic dysfunction. We here found that fibroblast activation protein α (FAP), a well-known marker of cancer-associated fibroblast, is selectively expressed in murine and human ATM among adipose tissue-infiltrating leukocytes. Macrophage FAP deficiency protects mice against diet-induced obesity and proinflammatory macrophage infiltration in obese adipose tissues, thereby alleviating hepatic steatosis and insulin resistance. Mechanistically, FAP specifically mediates monocyte chemokine protein CCL8 expression by ATM, which is further upregulated upon high-fat-diet (HFD) feeding, contributing to the recruitment of monocyte-derived proinflammatory macrophages with no effect on their classical inflammatory activation. CCL8 overexpression restores HFD-induced metabolic phenotypes in the absence of FAP. Moreover, macrophage FAP deficiency enhances energy expenditure and oxygen consumption preceding differential body weight after HFD feeding. Such enhanced energy expenditure is associated with increased levels of norepinephrine (NE) and lipolysis in white adipose tissues, likely due to decreased expression of monoamine oxidase, a NE degradation enzyme, by Fap-/- ATM. Collectively, our study identifies FAP as a previously unrecognized regulator of ATM function contributing to diet-induced obesity and metabolic inflammation and suggests FAP as a potential immunotherapeutic target against metabolic disorders.

Extracellular vesicles remodel tumor environment for cancer immunotherapy

Tumor immunotherapy has transformed neoplastic disease management, yet low response rates and immune complications persist as major challenges. Extracellular vesicles including exosomes have emerged as therapeutic agents actively involved in a diverse range of pathological conditions. Mounting evidence suggests that alterations in the quantity and composition of extracellular vesicles (EVs) contribute to the remodeling of the immune-suppressive tumor microenvironment (TME), thereby influencing the efficacy of immunotherapy. This revelation has sparked clinical interest in utilizing EVs for immune sensitization. In this perspective article, we present a comprehensive overview of the origins, generation, and interplay among various components of EVs within the TME. Furthermore, we discuss the pivotal role of EVs in reshaping the TME during tumorigenesis and their specific cargo, such as PD-1 and non-coding RNA, which influence the phenotypes of critical immune cells within the TME. Additionally, we summarize the applications of EVs in different anti-tumor therapies, the latest advancements in engineering EVs for cancer immunotherapy, and the challenges encountered in clinical translation. In light of these findings, we advocate for a broader understanding of the impact of EVs on the TME, as this will unveil overlooked therapeutic vulnerabilities and potentially enhance the efficacy of existing cancer immunotherapies.

Development and Characterization of Novel FAP-Targeted Theranostic Pairs: A Bench-to-Bedside Study

Fibroblast activation protein (FAP) is among the most popular targets in nuclear medicine imaging and cancer theranostics. Several small-molecule moieties (FAPI-04, FAPI-46, etc.) are used for developing FAP-targeted theranostic agents. Nonetheless, the circulation time of FAP inhibitors is relatively short, resulting in rapid clearance via kidneys, low tumor uptake, and associated unsatisfactory treatment efficacy. To address the existing drawbacks, we engineered 3 peptides named FD1, FD2, and FD3 with different circulation times through solid-phase peptide synthesis. All the 3 reported peptides bind to human and murine FAP with single-digit nanomolar affinity measured by surface plasmon resonance. The diagnostic and therapeutic potential of the agents labeled with 68Ga and 177Lu was assessed in several tumor models exhibiting different levels of FAP expression. While radiolabeled FD1 was rapidly excreted from kidneys, radiolabeled FD2/FD3 have significantly prolonged circulation, increased tumor uptake, and decreased kidney accumulation. Our findings indicated that [68Ga]Ga-DOTA-FD1 positron emission tomography (PET) effectively detected FAP dynamics, whereas [177Lu]Lu-DOTA-FD2 and [177Lu]Lu-DOTA-FD3 exhibited remarkable therapeutic efficacy in FAP-overexpressing tumor models, including pancreatic cancer cell models characterized by abundant stroma. Moreover, a pilot translational investigation demonstrated that [68Ga]Ga-DOTA-FD1 had the capability to identify both primary and metastatic tumors with precision and distinction. In summary, we developed [68Ga]Ga-DOTA-FD1 for same-day PET imaging of FAP dynamics and [177Lu]Lu-DOTA-FD2 and [177Lu]Lu-DOTA-FD3 for effective radioligand therapy of FAP-overexpressing tumors.

Association between high expression of intratumoral fibroblast activation protein and survival in patients with intrahepatic cholangiocarcinoma

BACKGROUND

Cancer-associated fibroblasts (CAFs) have been reported to exhibit protumorigenic effects. Among the well-known CAF markers such as smooth muscle actin (SMA) and fibroblast activation protein (FAP), high expression of SMA in the peritumoral stroma has been reported to be a prognostic factor in various cancers. However, the effect of high FAP expression in intrahepatic cholangiocarcinoma (IHCC) has not been fully clarified. We evaluated the expression of CAF markers, focusing on FAP expression in the peripheral and intratumoral regions, to clarify the association with survival in patients with IHCC.

METHODS

The study cohort comprised 37 patients who underwent curative resection for IHCC. The FAP expressions were evaluated in the peripheral and intratumoral regions of the resected tissues. Clinicopathological factors and survival outcomes were investigated between patients with high versus low FAP expression. Uni- and multivariate analyses were performed to identify the prognostic factors for overall survival and relapse-free survival.

RESULTS

The median area percentages of FAP expression in the peripheral and intratumoral regions were 15.5% and 17.8%, respectively. High FAP expression in the intratumoral region was significantly associated with worse overall survival and disease-free survival than low FAP expression in the intratumoral region. Multivariate analysis identified high intratumoral FAP expression as a risk factor for worse overall survival (hazard ratio, 2.450; p = 0.049) and relapse-free survival (hazard ratio, 2.743; p = 0.034).

CONCLUSIONS

High intratumoral FAP expression was associated with worse survival, suggesting that intratumoral FAP expression represents malignant progression in patients with IHCC.

Nicotinamide N -methyltransferase promotes M2 macrophage polarization by IL6 and MDSC conversion by GM-CSF in gallbladder carcinoma

BACKGROUND AND AIMS

Nicotinamide N -methyltransferase (NNMT), an enzyme responsible for the methylation of nicotinamide, is involved in many metabolic pathways in adipose tissue and the liver. However, the role of NNMT in editing the tumor immune microenvironment is not well understood.

APPROACH AND RESULTS

Here, we identified that NNMT can promote IL6 and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression by decreasing the tri-methyl-histone H3 levels on the promoters of IL6 and CSF2 (encoding GM-CSF) and CCAAT/Enhancer Binding Protein, an essential transcription factor for IL6 expression, thus promoting differentiation of macrophages into M2 type tumor-associated macrophages and generation of myeloid-derived suppressor cells from peripheral blood mononuclear cells. Treatment of xenografted tumor models overexpressing NNMT gallbladder carcinoma (GBC) cells with the NNMT inhibitor JBSNF-000088 resulted in compromised tumor development and decreased expression levels of IL6, GM-CSF, tumor-associated macrophage marker CD206, and myeloid-derived suppressor cell marker CD33 but increased expression levels of CD8. In addition, elevated expression of NNMT in tumors of patients with GBC was correlated with increased expression levels of CD206 and CD33 but with decreased levels of CD8 and survival of patients.

CONCLUSIONS

These data highlight the critical role of NNMT in GBC progression. Inhibition of NNMT by JBSNF-000088 is a potential molecular target for GBC immunotherapy.

Friend or foe? The elusive role of hepatic stellate cells in liver cancer

Liver fibrosis is a substantial risk factor for the development and progression of liver cancer, which includes hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Studies utilizing cell fate mapping and single-cell transcriptomics techniques have identified quiescent perisinusoidal hepatic stellate cells (HSCs) as the primary source of activated collagen-producing HSCs and liver cancer-associated fibroblasts (CAFs) in HCC and liver metastasis, complemented in iCCA by contributions from portal fibroblasts. At the same time, integrative computational analysis of single-cell, single-nucleus and spatial RNA sequencing data have revealed marked heterogeneity among HSCs and CAFs, with distinct subpopulations displaying unique gene expression signatures and functions. Some of these subpopulations have divergent roles in promoting or inhibiting liver fibrogenesis and carcinogenesis. In this Review, we discuss the dual roles of HSC subpopulations in liver fibrogenesis and their contribution to liver cancer promotion, progression and metastasis. We review the transcriptomic and functional similarities between HSC and CAF subpopulations, highlighting the pathways that either promote or prevent fibrosis and cancer, and the immunological landscape from which these pathways emerge. Insights from ongoing studies will yield novel strategies for developing biomarkers, assessing prognosis and generating new therapies for both HCC and iCCA prevention and treatment.

The recent progress of myeloid-derived suppressor cell and its targeted therapies in cancers

Myeloid-derived suppressor cells (MDSCs) are an immature group of myeloid-derived cells generated from myeloid cell precursors in the bone marrow. MDSCs appear almost exclusively in pathological conditions, such as tumor progression and various inflammatory diseases. The leading function of MDSCs is their immunosuppressive ability, which plays a crucial role in tumor progression and metastasis through their immunosuppressive effects. Since MDSCs have specific molecular features, and only a tiny amount exists in physiological conditions, MDSC-targeted therapy has become a promising research direction for tumor treatment with minimal side effects. In this review, we briefly introduce the classification, generation and maturation process, and features of MDSCs, and detail their functions under various circumstances. The present review specifically demonstrates the environmental specificity of MDSCs, highlighting the differences between MDSCs from cancer and healthy individuals, as well as tumor-infiltrating MDSCs and circulating MDSCs. Then, we further describe recent advances in MDSC-targeted therapies. The existing and potential targeted drugs are divided into three categories, monoclonal antibodies, small-molecular inhibitors, and peptides. Their targeting mechanisms and characteristics have been summarized respectively. We believe that a comprehensive in-depth understanding of MDSC-targeted therapy could provide more possibilities for the treatment of cancer.

Preclinical and clinical studies of immunotherapy for the treatment of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare primary liver cancer associated with high mortality and few systemic treatment options. The behaviour of the immune system has come into focus as a potential treatment modality for many cancer types, but immunotherapy has yet to dramatically alter the treatment paradigm for CCA as it has for other diseases. Herein, we review recent studies describing the relevance of the tumour immune microenvironment (TIME) in CCA. Various non-parenchymal cell types are critically important in controlling CCA progression, prognosis, and response to systemic therapy. Knowledge of the behaviour of these leukocytes could help generate hypotheses to guide the development of potential immune-directed therapies. Recently, an immunotherapy-containing combination was approved for the treatment of advanced-stage CCA. However, despite level 1 evidence demonstrating the improved efficacy of this therapy, survival remained suboptimal. In the current manuscript, we provide a comprehensive review of the TIME in CCA, preclinical studies of immunotherapies against CCA, as well as ongoing clinical trials applying immunotherapies for the treatment of CCA. Particular emphasis is placed on microsatellite unstable tumours, a rare CCA subtype that demonstrates heightened sensitivity to approved immune checkpoint inhibitors. We also discuss the challenges involved in applying immunotherapies to the treatment of CCA and the importance of understanding the TIME.

Immunology and immunotherapy of cholangiocarcinoma

Cholangiocarcinoma is the second most common primary liver cancer. Its incidence is low in the Western world but is rising globally. Surgery, chemotherapy and radiation therapy have been the only treatment options for decades. Progress in our molecular understanding of the disease and the identification of druggable targets, such as IDH1 mutations and FGFR2 fusions, has provided new treatment options. Immunotherapy has emerged as a potent strategy for many different types of cancer and has shown efficacy in combination with chemotherapy for cholangiocarcinoma. In this Review, we discuss findings related to key immunological aspects of cholangiocarcinoma, including the heterogeneous landscape of immune cells within the tumour microenvironment, the immunomodulatory effect of the microbiota and IDH1 mutations, and the association of immune-related signatures and patient outcomes. We introduce findings from preclinical immunotherapy studies, discuss future immune-mediated treatment options, and provide a summary of results from clinical trials testing immune-based approaches in patients with cholangiocarcinoma. This Review provides a thorough survey of our knowledge on immune signatures and immunotherapy in cholangiocarcinoma.

Current Role and Future Perspectives of Immunotherapy and Circulating Factors in Treatment of Biliary Tract Cancers

Biliary tract cancers (BTCs) are a heterogenous group of malignancies arising from the epithelial cells of the biliary tree and the gallbladder. They are often locally advanced or already metastatic at the time of the diagnosis and therefore prognosis remains dismal. Unfortunately, the management of BTCs has been limited by resistance and consequent low response rate to cytotoxic systemic therapy. New therapeutic approaches are needed to improve the survival outcomes for these patients. Immunotherapy, one of the newest therapeutic options, is changing the approach to the oncological treatment. Immune checkpoint inhibitors are by far the most promising group of immunotherapeutic agents: they work by blocking the tumor-induced inhibition of the immune cellular response. Immunotherapy in BTCs is currently approved as second-line treatment for patients whose tumors have a peculiar molecular profile, such as high levels of microsatellites instability, PD-L1 overexpression, or high levels of tumor mutational burden. However, emerging data from ongoing clinical trials seem to suggest that durable responses can be achieved in other subsets of patients. The BTCs are characterized by a highly desmoplastic microenvironment that fuels the growth of cancer tissue, but tissue biopsies are often difficult to obtain or not feasible in BTCs. Recent studies have hence proposed to use liquid biopsy approaches to search the blood circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) to use as biomarkers in BTCs. So far studies are insufficient to promote their use in clinical management, however trials are still in progress with promising preliminary results. Analysis of blood samples for ctDNA to research possible tumor-specific genetic or epigenetic alterations that could be linked to treatment response or prognosis was already feasible. Although there are still few data available, ctDNA analysis in BTC is fast, non-invasive, and could also represent a way to diagnose BTC earlier and monitor tumor response to chemotherapy. The prognostic capabilities of soluble factors in BTC are not yet precisely determined and more studies are needed. In this review, we will discuss the different approaches to immunotherapy and tumor circulating factors, the progress that has been made so far, and the possible future developments.

What is new in cancer-associated fibroblast biomarkers?

The tumor microenvironment is one of the important drivers of tumor development. Cancer-associated fibroblasts (CAFs) are a major component of the tumor stroma and actively participate in tumor development, invasion, metastasis, drug resistance, and other biological behaviors. CAFs are a highly heterogeneous group of cells, a reflection of the diversity of their origin, biomarkers, and functions. The diversity of CAF origin determines the complexity of CAF biomarkers, and CAF subpopulations expressing different biomarkers may play contrasting roles in tumor progression. In this review, we provide an overview of these emerging CAF biomarkers and the biological functions that they suggest, which may give a better understanding of the relationship between CAFs and tumor cells and be of great significance for breakthroughs in precision targeted therapy for tumors. Video Abstract.

Role and mechanism of fibroblast-activated protein-α expression on the surface of fibroblast-like synoviocytes in rheumatoid arthritis

Fibroblast-activated protein-α (FAP) is a type II integrated serine protease expressed by activated fibroblasts during fibrosis or inflammation. Fibroblast-like synoviocytes (FLSs) in rheumatoid arthritis (RA) synovial sites abundantly and stably overexpress FAP and play important roles in regulating the cellular immune, inflammatory, invasion, migration, proliferation, and angiogenesis responses in the synovial region. Overexpression of FAP is regulated by the initial inflammatory microenvironment of the disease and epigenetic signaling, which promotes RA development by regulating FLSs or affecting the signaling cross-linking FLSs with other cells at the local synovium and inflammatory stimulation. At present, several treatment options targeting FAP are in the process of development. This review discusses the basic features of FAP expressed on the surface of FLSs and its role in RA pathophysiology and advances in targeted therapies.

Heterogeneity of Cholangiocarcinoma Immune Biology

Cholangiocarcinomas (CCAs) are aggressive tumors arising along the biliary tract epithelium, whose incidence and mortality are increasing. CCAs are highly desmoplastic cancers characterized by a dense tumor microenvironment (TME), in which each single component plays a fundamental role in shaping CCA initiation, progression and resistance to therapies. The crosstalk between cancer cells and TME can affect the recruitment, infiltration and differentiation of immune cells. According to the stage of the disease and to intra- and inter-patient heterogeneity, TME may contribute to either protumoral or antitumoral activities. Therefore, a better understanding of the effect of each immune cell subtype may open the path to new personalized immune therapeutic strategies for the management of CCA. In this review, we describe the role of immune cells in CCA initiation and progression, and their crosstalk with both cancer-associated fibroblasts (CAFs) and the cancer-stem-cell-like (CSC) niche.

Cancer-Associated Fibroblasts in Hepatocellular Carcinoma and Cholangiocarcinoma

Primary liver cancer (PLC) includes hepatocellular carcinoma and intrahepatic cholangiocarcinoma and is the sixth most common cancer worldwide with poor prognosis. PLC is characterized by an abundant stromal reaction in which cancer-associated fibroblasts (CAFs) are one of the major stromal components. Solid evidence has demonstrated the crucial role of CAFs in tumor progression, and CAF abundance is often correlated with poor clinical outcomes. Although CAFs are regarded as an attractive and promising target for PLC treatment, a poor understanding of CAF origins and heterogeneity and a lack of specific CAF markers are the major hurdles to efficient CAF-specific therapy. In this review, we examine recent advances in the understanding of CAF diversity in the context of biomarkers, subtypes, and functions in PLC. The regulatory roles of CAFs in extracellular matrix remodeling, metastasis, cancer stemness, and therapeutic resistance are summarized. With an increasing link between CAF abundance and reduced antitumor immune responses, we provide updated knowledge on the crosstalk between CAFs and immune cells within the tumor microenvironment, which leads to immune resistance. In addition, we present current CAF-targeted therapies and describe some future perspectives. A better understanding of CAF biology will shed light on a novel therapeutic strategy against PLC.

Bioinformatics Analysis of Inflammation Gene Signature in Indicating Cholangiocarcinoma Prognosis

Aim. We studied inflammatory response-related genes in cholangiocarcinoma by bioinformatics analysis. Methods. The expression profiles and clinical information of cholangiocarcinoma patients were downloaded from the TCGA cohort and the Gene Expression Omnibus. The greatest absolute shrinking and selecting operator Cox analyses were utilized to build a multigene predictive signature. Results. An inflammation response-related gene profile was generated using LASSO-Cox regression analysis of Homo sapiens bestrophin 1 (BEST1), Chemokine (C–C motif) ligand 2 (CCL2), and plasminogen activator, urokinase receptor (PLAUR). Individuals in the highest category had a significantly lower overall survival time than those from the low-risk group. A receiver operating curve analysis was used to demonstrate the predictive ability of the predictive gene signature. Through multivariate Cox analysis, the risk score was discovered to be a predictor of overall survival (OS). According to functional assessments, the immunological state and milieu of the two risk areas were significantly different. The expression levels of predictive genes were found to be strongly linked to the sensitivity of cancer cells to antitumor therapy. Conclusion. A new signature made up of three respective response-relevant genes is found to be a promising indicator of prognosis by influencing the immune condition and tumor microenvironment.

Advances of cancer-associated fibroblasts in liver cancer

Liver cancer is one of the most common malignant tumors worldwide, it is ranked sixth in incidence and fourth in mortality. According to the distinct origin of malignant tumor cells, liver cancer is mainly divided into hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). Since most cases are diagnosed at an advanced stage, the prognosis of liver cancer is poor. Tumor growth depends on the dynamic interaction of various cellular components in the tumor microenvironment (TME). As the most abundant components of tumor stroma, cancer-associated fibroblasts (CAFs) have been involved in the progression of liver cancer. The interplay between CAFs and tumor cells, immune cells, or vascular endothelial cells in the TME through direct cell-to-cell contact or indirect paracrine interaction, affects the initiation and development of tumors. Additionally, CAFs are not a homogeneous cell population in liver cancer. Recently, single-cell sequencing technology has been used to help better understand the diversity of CAFs in liver cancer. In this review, we mainly update the knowledge of CAFs both in HCC and CCA, including their cell origins, chemoresistance, tumor stemness induction, tumor immune microenvironment formation, and the role of tumor cells on CAFs. Understanding the context-dependent role of different CAFs subsets provides new strategies for precise liver cancer treatment.

Targeting tumor microenvironment for cholangiocarcinoma: Opportunities for precision medicine

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CCA has a dismal prognosis, and it is usually diagnosed in advanced stage for which available treatments have limited efficacy.

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CCA TME presents an abundant desmoplastic stroma and exhibits a high heterogeneity.

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TME plays a central role in cancer development and in the resistance to treatments.

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Treatments targeting the TME in association with cytotoxic agents could represent a promising therapeutic strategy.

Systemic treatments (e.g., chemotherapy and targeted therapies) have limited efficacy for patients with locally advanced – unresectable – and metastatic cholangiocarcinoma (CCA), with an overall survival of less than a year. Tumor microenvironment (TME) represents the ecosystem surrounding the tumor which comprises immune cells, fibroblasts, endothelial cells, and a wide range of soluble factors. CCA TME is characterized by an abundant desmoplastic stroma, exhibits a high heterogeneity and it plays a central role in cancer onset and progression. There is growing evidence suggesting that it is possible to target TME in association with other treatment modalities, such as cytotoxic chemotherapy or targeted therapies, paving the way to possible combination strategies with a synergistic effect. Herein, we describe the components of CCA TME – such as cancer-associated fibroblasts and other cells of pivotal importance - with their most relevant interactions, focusing on the preclinical rationale for the development of effective anticancer treatments.

Insights into the role of STAT3 in intrahepatic cholangiocarcinoma (Review)

Intrahepatic cholangiocarcinoma (ICC) is a primary malignant liver tumour whose incidence is second only to that of hepatocellular carcinoma. ICC is a highly heterogeneous disease arising from neoplastic transformation of intrahepatic biliary epithelial cells (cholangiocytes), and it is characterized by a very poor prognosis. Signal transducer and activator of transcription 3 (STAT3) is an important oncogene that is widely expressed in numerous cancers. STAT3 is a candidate target for the treatment of ICC. However, studies on STAT3 and the occurrence and development of ICC require improvements. Therefore, the present review summarized the mechanism of STAT3 in ICC and provided a theoretical basis for STAT3 to become an effective target for determining the prognosis and treatment of ICC.

FAP imaging in rare cancer entities-first clinical experience in a broad spectrum of malignancies

PURPOSE

68 Ga-FAPI (fibroblast activation protein inhibitor) is a rapidly evolving and highly promising radiotracer for PET/CT imaging, presenting excellent results in a variety of tumor entities, particularly in epithelial carcinomas. This retrospective analysis sought to evaluate the potential and impact of FAPI-PET/CT in rare cancer diseases with respect to improvement in staging and therapy, based on tracer uptake in normal organs and tumors.

MATERIAL AND METHODS

Fifty-five patients with rare tumor entities, defined by a prevalence of 1 person out of 2000 or less, received a 68 Ga-FAPI-PET/CT scan. Fourteen women and 41 men (median age 60) were included within the following subgroups: cancer of unknown primary (n = 10), head and neck cancer (n = 13), gastrointestinal and biliary-pancreatic cancer (n = 17), urinary tract cancer (n = 4), neuroendocrine cancer (n = 4), and others (n = 7). Tracer uptake was quantified by standardized uptake values SUVmax and SUVmean and the tumor-to-background ratio (TBR) was determined (SUVmax tumor/SUVmean organ).

RESULTS

In 20 out of 55 patients, the primary tumor was identified and 31 patients presented metastases (n = 88), characterized by a high mean SUVmax in primary (10.1) and metastatic lesions (7.6). The highest uptake was observed in liver metastases (n = 6) with a mean SUVmax of 9.8 and a high TBR of 8.7, closely followed by peritoneal carcinomatosis (n = 16) presenting a mean SUVmax of 9.8 and an excellent TBR of 29.6. In terms of the included subgroups, the highest uptake regarding mean SUVmax was determined in gastrointestinal and biliary-pancreatic cancer with 9.8 followed closely by urinary tract cancer with 9.5 and head and neck cancer (9.1).

CONCLUSION

Due to excellent tumor visualization and, thereby, sharp contrasts in terms of high TBRs in primary and metastatic lesions in different rare malignancies, 68 Ga-FAPI-PET/CT crystallizes as a powerful and valuable imaging tool, particularly with respect to epithelial carcinomas, and therefore an enhancement to standard diagnostics imaging methodologies. The realization of further and prospective studies is of large importance to confirm the potential of FAP imaging in oncology.

CAFs shape myeloid-derived suppressor cells to promote stemness of intrahepatic cholangiocarcinoma through 5-lipoxygenase

BACKGROUND AND AIMS

We previously demonstrated that cancer-associated fibroblasts (CAFs) promote tumor growth through recruitment of myeloid-derived suppressor cells (MDSCs). 5-lipoxygenase (5-LO) is highly expressed in myeloid cells and is critical for synthesizing leukotriene B4 (LTB4), which is involved in tumor progression by activating its receptor leukotriene B4 receptor type 2 (BLT2). In this study, we investigated whether and how CAFs regulate MDSC function to enhance cancer stemness, the driving force of the cancer aggressiveness and chemotherapy refractoriness, in highly desmoplastic intrahepatic cholangiocarcinoma (ICC).

APPROACH AND RESULTS

RNA-sequencing analysis revealed enriched metabolic pathways but decreased inflammatory pathways in cancer MDSCs compared with blood MDSCs from patients with ICC. Co-injection of ICC patient-derived CAFs promoted cancer stemness in an orthotopic ICC model, which was blunted by MDSC depletion. Conditioned media (CM) from CAF-educated MDSCs drastically promoted tumorsphere formation efficiency and stemness marker gene expression in ICC cells. CAF-CM stimulation increased expression and activity of 5-LO in MDSCs, while 5-LO inhibitor impaired the stemness-enhancing capacity of MDSCs in vitro and in vivo. Furthermore, IL-6 and IL-33 primarily expressed by CAFs mediated hyperactivated 5-LO metabolism in MDSCs. We identified the LTB4-BLT2 axis as the critical downstream metabolite signaling of 5-LO in promoting cancer stemness, as treatment with LTB4 was elevated in CAF-educated MDSCs, or blockade of BLT2 (which was preferentially expressed in stem-like ICC cells) significantly reduced stemness-enhancing effects of CAF-educated MDSCs. Finally, BLT2 blockade augmented chemotherapeutic efficacy in ICC patient-derived xenograft models.

CONCLUSIONS

Our study reveals a role for CAFs in orchestrating the optimal cancer stemness-enhancing microenvironment by educating MDSCs, and suggests the 5-LO/LTB4-BLT2 axis as promising therapeutic targets for ICC chemoresistance by targeting cancer stemness.

Development and Validation of a Novel Prognosis Prediction Model for Patients With Stomach Adenocarcinoma

Background: Stomach adenocarcinoma (STAD) is a significant global health problem. It is urgent to identify reliable predictors and establish a potential prognostic model.

Methods: RNA-sequencing expression data of patients with STAD were downloaded from the Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) database. Gene expression profiling and survival analysis were performed to investigate differentially expressed genes (DEGs) with significant clinical prognosis value. Overall survival (OS) analysis and univariable and multivariable Cox regression analyses were performed to establish the prognostic model. Protein–protein interaction (PPI) network, functional enrichment analysis, and differential expression investigation were also performed to further explore the potential mechanism of the prognostic genes in STAD. Finally, nomogram establishment was undertaken by performing multivariate Cox regression analysis, and calibration plots were generated to validate the nomogram.

Results: A total of 229 overlapping DEGs were identified. Following Kaplan–Meier survival analysis and univariate and multivariate Cox regression analysis, 11 genes significantly associated with prognosis were screened and five of these genes, including COL10A1, MFAP2, CTHRC1, P4HA3, and FAP, were used to establish the risk model. The results showed that patients with high-risk scores have a poor prognosis, compared with those with low-risk scores (p = 0.0025 for the training dataset and p = 0.045 for the validation dataset). Subsequently, a nomogram (including TNM stage, age, gender, histologic grade, and risk score) was created. In addition, differential expression and immunohistochemistry stain of the five core genes in STAD and normal tissues were verified.

Conclusion: We develop a prognostic-related model based on five core genes, which may serve as an independent risk factor for survival prediction in patients with STAD.

Emerging Roles of Myeloid-Derived Suppressor Cells in Diabetes

Diabetes is a syndrome characterized by hyperglycemia with or without insulin resistance. Its etiology is attributed to the combined action of genes, environment and immune cells. Myeloid-derived suppressor cell (MDSC) is a heterogeneous population of immature cells with immunosuppressive ability. In recent years, different studies have debated the quantity, activity changes and roles of MDSC in the diabetic microenvironment. However, the emerging roles of MDSC have not been fully documented with regard to their interactions with diabetes. Here, the manifestations of MDSC and their subsets are reviewed with regard to the incidence of diabetes and diabetic complications. The possible drugs targeting MDSC are discussed with regard to their potential of treating diabetes. We believe that understanding MDSC will offer opportunities to explain pathological characteristics of different diabetes. MDSC also will be used for personalized immunotherapy of diabetes.

Engineered exosome-like nanovesicles suppress tumor growth by reprogramming tumor microenvironment and promoting tumor ferroptosis

Tumor vaccines that induce effective and sustained antitumor immunity are highly promising for cancer therapy. However, the antitumor potential of these vaccines is weakened due to the immunosuppressive characteristics of the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are the most abundant stromal cells within the TME; they play an important role in tumor growth, metastasis, immunosuppression, and drug resistance. Fibroblast activation protein-α (FAP) is overexpressed in CAFs in more than 90% of human tumor tissues. Further, FAP⁺CAFs are an ideal interstitial target for the immunotherapy of solid tumors. Exosomes derived from tumor cells contain many tumor antigens, which can be used as the basis of tumor vaccines that elicit strong antitumor immunity. Almost all exosome-based cancer vaccines have been designed and developed for tumor parenchymal cells. Moreover, the exosome production is very low and the purification is very difficult, limiting their clinical application as tumor vaccines. In this study, we developed FAP gene-engineered tumor cell-derived exosome-like nanovesicles (eNVs-FAP) as a tumor vaccine that can be prepared easily and in large quantities. The eNVs-FAP vaccine inhibited tumor growth by inducing strong and specific cytotoxic T lymphocyte (CTL) immune responses against tumor cells and FAP⁺CAFs and reprogramming the immunosuppressive TME in the colon, melanoma, lung, and breast cancer models. Moreover, eNVs-FAP vaccine-activated cellular immune responses could promote tumor ferroptosis by releasing interferon-gamma (IFN-γ) from CTLs and depleting FAP⁺CAFs. Thus, eNVs-FAP is a candidate tumor vaccine targeting both the tumor parenchyma and the stroma. STATEMENT OF SIGNIFICANCE: Nanovaccines can activate immune cells and promote an antitumor immune response. In this study, we developed the fibroblast activation protein-α (FAP) gene-engineered tumor cell-derived exosome-like vesicle vaccines (eNVs-FAP). A large number of eNVs-FAP were obtained by continuously squeezing FAP gene-engineered tumor cells. eNVs-FAP showed excellent antitumor effects in a variety of tumor-bearing mouse models. The mechanistic analysis showed that eNVs-FAP promoted the maturation of dendritic cells (DCs), increased the infiltration of effector T cells into target tumor cells and FAP-positive cancer-associated fibroblasts (FAP⁺CAFs), and reduced the proportion of immunosuppressive cells, including M2-like tumor-associated macrophages (M2-TAMs), myeloid-derived suppressor cells (MDSCs), and regulatory T cells (Tregs), in the tumor microenvironment (TME). Moreover, the clearance of FAP⁺CAFs helped enhance interferon-gamma-induced tumor cell ferroptosis.

Fibroblast Activation Protein-α as a Target in the Bench-to-Bedside Diagnosis and Treatment of Tumors: A Narrative Review

Fibroblast activation protein-α (FAP) is a type II integral serine protease that is specifically expressed by activated fibroblasts. Cancer-associated fibroblasts (CAFs) in the tumor stroma have an abundant and stable expression of FAP, which plays an important role in promoting tumor growth, invasion, metastasis, and immunosuppression. For example, in females with a high incidence of breast cancer, CAFs account for 50–70% of the cells in the tumor’s microenvironment. CAF overexpression of FAP promotes tumor development and metastasis by influencing extracellular matrix remodeling, intracellular signaling, angiogenesis, epithelial-to-mesenchymal transition, and immunosuppression. This review discusses the basic biological characteristics of FAP and its applications in the diagnosis and treatment of various cancers. We review the emerging basic and clinical research data regarding the use of nanomaterials that target FAP.