Promotion of cholangiocarcinoma growth by diverse cancer-associated fibroblast subpopulations

Modulating PCGF4 Stability Is an Efficient Metastasis-Regulatory Strategy Used by Distinct Subtypes of Cancer-Associated Fibroblasts in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a highly malignant neoplasm and prone to metastasis. It is unclear if cancer-associated fibroblasts (CAFs) affect the metastasis of ICC. Here, we have established ICC patient-derived CAF lines and related cancerous cell lines and analyzed the effects of CAFs on the tumor progressive properties of the ICC cancerous cells. Results demonstrated that CAFs can be classified into cancer-restraining or cancer-promoting categories based on distinct tumorigenic effects. The RNA-sequencing analyses of ICC cancerous cell lines identified B-lymphoma Mo-MLV insertion region 1 (PCGF4; alias BMI1) as a potential metastasis regulator. Strikingly, the changes of PCGF4 levels in ICC cells perfectly mirrored the restraining or promoting effects of CAFs on ICC migration. Our immunohistochemical analyses on the ICC tissue microarrays indicated that PCGF4 was negatively correlated to overall survival of ICC. We confirmed the promoting effects of PCGF4 on cell migration, drug resistance activity, and stemness properties. Mechanistically, cancer-restraining CAFs triggered the proteasome-dependent degradation of PCGF4, whereas cancer-promoting CAFs enhanced the stability of PCGF4 via activating the IL-6/phosphorylated STAT3 pathway. In summary, our data identified roles of CAFs on ICC metastasis and revealed a new mechanism of the CAFs on ICC progression in which PCGF4 acted as the key effector by both categories of CAFs. These findings shed light on developing comprehensive therapeutic strategies for ICC.

Identification and validation of a lactate metabolism-related six-gene prognostic signature in intrahepatic cholangiocarcinoma

PURPOSE

Intrahepatic cholangiocarcinoma (iCCA) is a highly malignant and fatal liver tumor with increasing incidence worldwide. Lactate metabolism has been recently reported as a crucial contributor to tumor progression and immune regulation in the tumor microenvironment. However, it remains poorly identified about the biological functions of lactate metabolism in iCCA, which hinders the development of prognostic tools and therapeutic interventions.

METHODS

The univariate Cox regression analysis and Boruta algorithm were utilized to identify key lactate metabolism-related genes (LMRGs), and a prognostic signature was constructed based on LMRG scores. Genomic variations and immune cell infiltration were evaluated in the high and low LMRG score groups. Finally, the biological functions of key LMRGs were verified with in vitro and in vivo experiments.

RESULTS

Patients in the high LMRG score group exhibit a poor prognosis compared to those in the low LMRG score group, with a high frequency of TP53 and KRAS mutations. Moreover, the infiltration and function of NK cells were compromised in the high LMRG score group, consistent with the results from two independent single-cell RNA sequencing datasets and immunohistochemistry of tissue microarrays. Experimental data revealed that lactate dehydrogenase A (LDHA) knockdown inhibited proliferation and migration in iCCA cell lines and tumor growth in immunocompetent mice.

CONCLUSION

Our study revealed the biological roles of LDHA in iCCA and developed a reliable lactate metabolism-related prognostic signature for iCCA, offering promising therapeutic targets for iCCA in the clinic.

Recent advances in cancer-associated fibroblast: Biomarkers, signaling pathways, and therapeutic opportunities

ABSTRACT

Anti-cancer therapies usually focus on tumor cells, but non-tumor stromal components in the tumor microenvironment also play vital roles in tumor initiation and progression, which may be the prognostic factors and potential therapeutic targets. Cancer-associated fibroblasts (CAFs) are the essential component in the tumor environment, exhibiting high heterogeneity in their cell origin and phenotype with diverse functions that influence tumor angiogenesis, immune systems, and metabolism. Single-cell RNA sequencing and genetically engineered mouse models have increased our understanding of CAF diversity, and many subtypes have been defined. However, the precise functions of these subtypes need to be studied and validated. Studies of signaling pathways and epigenetic changes in CAFs facilitate understanding of the phenotypes of CAFs and the crosstalk between tumor cells and CAFs to provide potential therapeutic targets. Some clinical trials, including phase III trials targeting CAFs, have been performed recently. However, few of these trials have generated promising results, which indicates that the complexity of CAFs in the tumor microenvironment remains largely unknown, and in-depth investigations of CAFs should be performed. This review summarizes the research on CAFs, focusing on the heterogeneity of their phenotypes and functions, specific signaling pathways, and the therapeutic strategies involving CAFs. Additionally, we briefly discuss the current technologies commonly used in CAF studies and describe the challenges and future perspectives of CAF research.

Implicating the cholecystokinin B receptor in liver stem cell oncogenesis

Hepatocellular carcinoma (HCC) is the fastest-growing cause of cancer-related deaths worldwide. Chronic inflammation and fibrosis are the greatest risk factors for the development of HCC. Although the cell of origin for HCC is uncertain, many theories believe this cancer may arise from liver progenitor cells or stem cells. Here, we describe the activation of hepatic stem cells that overexpress the cholecystokinin-B receptor (CCK-BR) after liver injury with either a DDC diet (0.1% 3, 5-diethoxy-carbonyl 1,4-dihydrocollidine) or a NASH-inducing CDE diet (choline-deficient ethionine) in murine models. Pharmacologic blockade of the CCK-BR with a receptor antagonist proglumide or knockout of the CCK-BR in genetically engineered mice during the injury diet reduces the expression of hepatic stem cells and prevents the formation of three-dimensional tumorspheres in culture. RNA sequencing of livers from DDC-fed mice treated with proglumide or DDC-fed CCK-BR knockout mice showed downregulation of differentially expressed genes involved in cell proliferation and oncogenesis and upregulation of tumor suppressor genes compared with controls. Inhibition of the CCK-BR decreases hepatic transaminases, fibrosis, cytokine expression, and alters the hepatic immune cell signature rendering the liver microenvironment less oncogenic. Furthermore, proglumide hastened recovery after liver injury by reversing fibrosis and improving markers of synthetic function. Proglumide is an older drug that is orally bioavailable and being repurposed for liver conditions. These findings support a promising therapeutic intervention applicable to patients to prevent the development of HCC and decrease hepatic fibrosis.NEW & NOTEWORTHY This investigation identified a novel pathway involving the activation of hepatic stem cells and liver oncogenesis. Receptor blockade or genetic disruption of the cholecystokinin-B receptor (CCK-BR) signaling pathway decreased the activation and proliferation of hepatic stem cells after liver injury without eliminating the regenerative capacity of healthy hepatocytes.

Sterile inflammation via TRPM8 RNA-dependent TLR3-NF-kB/IRF3 activation promotes antitumor immunity in prostate cancer

Inflammation is a common condition of prostate tissue, whose impact on carcinogenesis is highly debated. Microbial colonization is a well-documented cause of a small percentage of prostatitis cases, but it remains unclear what underlies the majority of sterile inflammation reported. Here, androgen- independent fluctuations of PSA expression in prostate cells have lead us to identify a prominent function of the Transient Receptor Potential Cation Channel Subfamily M Member 8 (TRPM8) gene in sterile inflammation. Prostate cells secret TRPM8 RNA into extracellular vesicles (EVs), which primes TLR3/NF-kB-mediated inflammatory signaling after EV endocytosis by epithelial cancer cells. Furthermore, prostate cancer xenografts expressing a translation-defective form of TRPM8 RNA contain less collagen type I in the extracellular matrix, significantly more infiltrating NK cells, and larger necrotic areas as compared to control xenografts. These findings imply sustained, androgen-independent expression of TRPM8 constitutes as a promoter of anticancer innate immunity, which may constitute a clinically relevant condition affecting prostate cancer prognosis.

Molecular portraits of patients with intrahepatic cholangiocarcinoma who diverge as rapid progressors or long survivors on chemotherapy

OBJECTIVE

Cytotoxic agents are the cornerstone of treatment for patients with advanced intrahepatic cholangiocarcinoma (iCCA), despite heterogeneous benefit. We hypothesised that the pretreatment molecular profiles of diagnostic biopsies can predict patient benefit from chemotherapy and define molecular bases of innate chemoresistance.

DESIGN

We identified a cohort of advanced iCCA patients with comparable baseline characteristics who diverged as extreme outliers on chemotherapy (survival <6 m in rapid progressors, RP; survival >23 m in long survivors, LS). Diagnostic biopsies were characterised by digital pathology, then subjected to whole-transcriptome profiling of bulk and geospatially macrodissected tissue regions. Spatial transcriptomics of tumour-infiltrating myeloid cells was performed using targeted digital spatial profiling (GeoMx). Transcriptome signatures were evaluated in multiple cohorts of resected cancers. Signatures were also characterised using in vitro cell lines, in vivo mouse models and single cell RNA-sequencing data.

RESULTS

Pretreatment transcriptome profiles differentiated patients who would become RPs or LSs on chemotherapy. Biologically, this signature originated from altered tumour-myeloid dynamics, implicating tumour-induced immune tolerogenicity with poor response to chemotherapy. The central role of the liver microenviroment was confrmed by the association of the RPLS transcriptome signature with clinical outcome in iCCA but not extrahepatic CCA, and in liver metastasis from colorectal cancer, but not in the matched primary bowel tumours.

CONCLUSIONS

The RPLS signature could be a novel metric of chemotherapy outcome in iCCA. Further development and validation of this transcriptomic signature is warranted to develop precision chemotherapy strategies in these settings.

Integrated multi-omics profiling to dissect the spatiotemporal evolution of metastatic hepatocellular carcinoma

Comprehensive molecular analyses of metastatic hepatocellular carcinoma (HCC) are lacking. Here, we generate multi-omic profiling of 257 primary and 176 metastatic regions from 182 HCC patients. Primary tumors rich in hypoxia signatures facilitated polyclonal dissemination. Genomic divergence between primary and metastatic HCC is high, and early dissemination is prevalent. The remarkable neoantigen intratumor heterogeneity observed in metastases is associated with decreased T cell reactivity, resulting from disruptions to neoantigen presentation. We identify somatic copy number alterations as highly selected events driving metastasis. Subclones without Wnt mutations show a stronger selective advantage for metastasis than those with Wnt mutations and are characterized by a microenvironment rich in activated fibroblasts favoring a pro-metastatic phenotype. Finally, metastases without Wnt mutations exhibit higher enrichment of immunosuppressive B cells that mediate terminal exhaustion of CD8+ T cells via HLA-E:CD94-NKG2A checkpoint axis. Collectively, our results provide a multi-dimensional dissection of the complex evolutionary process of metastasis.

Cholangiocarcinoma-on-a-chip: A human 3D platform for personalised medicine

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a primary liver tumour characterised by a poor prognosis and limited therapeutic options. Available 3D human CCA models fail to faithfully recapitulate the tumour niche. We aimed to develop an innovative patient-specific CCA-on-chip platform.

METHODS

A CCA tumour microenvironment was recapitulated on a microfluidic three-channel chip using primary CCA cells, cancer-associated fibroblasts (CAFs), endothelial cells, and T cells isolated from CCA specimens (n = 6). CAF and CCA cells were co-cultured in the central channel, flanked by endothelial cells in one lateral channel, recreating a tubular structure. An extensive characterisation of this platform was carried out to investigate its diffusion ability, hydrogel properties, and changes in matrix composition. Cell phenotype and functional properties were assessed.

RESULTS

Primary cells seeded on the microfluidic device were shown to reproduce the architectural structure and maintain the original phenotype and functional properties. The tumour niche underwent a deep remodelling in the 3D device, with an increase in hydrogel stiffness and extracellular matrix deposition, mimicking in vivo CCA characteristics. T cells were incorporated into the device to assess its reliability for immune cell interaction studies. Higher T cell migration was observed using cells from patients with highly infiltrated tumours. Finally, the drug trial showed the ability of the device to recapitulate different drug responses based on patient characteristics.

CONCLUSIONS

We presented a 3D CCA platform that integrates the major non-immune components of the tumour microenvironment and the T cell infiltrate, reflecting the CCA niche. This CCA-on-chip represents a reliable patient-specific 3D platform that will be of help to further elucidate the biological mechanisms involved in CCA and provide an efficient tool for personalised drug testing.

IMPACT AND IMPLICATIONS

An innovative patient-specific cholangiocarcinoma (CCA)-on-chip platform was successfully developed, integrating the major components of the tumour microenvironment (tumour cells, cancer-associated fibroblasts, endothelial cells, and immune infiltrate) and faithfully mimicking the CCA niche. This CCA-on-chip represents a powerful tool for unravelling disease-associated cellular mechanisms in CCA and provides an efficient tool for personalised drug testing.

Single-cell dissection reveals the role of aggrephagy patterns in tumor microenvironment components aiding predicting prognosis and immunotherapy on lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) is one of the leading malignant cancers. Aggrephagy plays a critical role in key genetic events for various cancers; yet, how aggrephagy functions within the tumor microenvironment (TME) in LUAD remains to be elucidated.

METHODS

In this study, by sequential non-negative matrix factorization (NMF) algorithm, pseudotime analysis, cell-cell interaction analysis, and SCENIC analysis, we have shown that aggrephagy genes demonstrated various patterns among different cell types in LUAD TME. LUAD and Immunotherapy cohorts from public repository were used to determine the prognosis and immune response of aggrephagy TME subtypes. The aggrephagy-deprived prognostic score (ADPS) was quantified based on machine learning algorithms.

RESULTS

The cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and CD8+ T cells have various aggrephagy patterns, which enhance the intensity of intercellular communication and transcription factor activation. Furthermore, based on the signatures of the newly defined aggrephagy cell subtypes and expression profiles of large cohorts in LUAD patients, we determine that DYNC1I2+CAF-C1, DYNLL1+CAF-C2, PARK7+CAF-C3, VIM+Mac-C1, PARK7+Mac-C2, VIM+CD8+T_cells-C1, UBA52+CD8+T_cells-C2, TUBA4A+CD8+T_ cells-C3, and TUBA1A+CD8+T_cells-C4 are crucial prognostic factors for LUAD patients. The developed ADPS could predict survival outcomes and immunotherapeutic response across ten cohorts (n = 1838), and patients with low ADPS owned a better prognosis, lower genomic alterations, and are more sensitive to immunotherapy. Meanwhile, based on PRISM, CTRP, and CMAP databases, PLK inhibitor BI-2536, may be a potential agent for patients with high ADPS.

CONCLUSIONS

Taken together, our novel and systematic single-cell analysis has revealed the unique role of aggrephagy in remodeling the TME of LUAD. As a newly demonstrated biomarker, the ADPS facilitates the clinical management and individualized treatment of LUAD.

Cancer-Associated Fibroblasts in Gastrointestinal Cancers: Unveiling Their Dynamic Roles in the Tumor Microenvironment

Gastrointestinal cancers are highly aggressive malignancies with significant mortality rates. Recent research emphasizes the critical role of the tumor microenvironment (TME) in these cancers, which includes cancer-associated fibroblasts (CAFs), a key component of the TME that have diverse origins, including fibroblasts, mesenchymal stem cells, and endothelial cells. Several markers, such as α-SMA and FAP, have been identified to label CAFs, and some specific markers may serve as potential therapeutic targets. In this review article, we summarize the literature on the multifaceted role of CAFs in tumor progression, including their effects on angiogenesis, immune suppression, invasion, and metastasis. In addition, we highlight the use of single-cell transcriptomics to understand CAF heterogeneity and their interactions within the TME. Moreover, we discuss the dynamic interplay between CAFs and the immune system, which contributes to immunosuppression in the TME, and the potential for CAF-targeted therapies and combination approaches with immunotherapy to improve cancer treatment outcomes.

Integrated analysis of single-cell RNA-seq and bulk RNA-seq unravels the heterogeneity of cancer-associated fibroblasts in TNBC

BACKGROUND

The treatment of triple-negative breast cancer (TNBC) is one of the main focuses and key difficulties because of its heterogeneity, and the source of this heterogeneity is unclear.

METHODS

Single-cell RNA (scRNA) and transcriptomics data of TNBC and normal breast samples were retrieved from Gene Expression Omnibus (GEO) database and TCGA-BRCA database. These cells were clustered using the t-SNE and UMAP method, and the marker genes for each cluster were found. We annotated the clusters using the published literature, CellMarker database and "SingleR" R package.

RESULTS

A total of 1535 cells and 21785 genes from 6 TNBC patients and 2068 cells and 15868 genes from 3 normal breast tissues were used for downstream analyses. The scRNA data were divided into 14 clusters labeled into 8 cell types, including epithelial cells, immunocytes, CAFs/fibroblasts and etc. In the TNBC samples, CAFs were divided into three clusters and labelled as prCAFs, myCAFs and emCAFs, and the marker genes were DCN, FAP and RGS5, respectively. The prCAF subgroup is functionally characterized by promoting proliferation and multi drug resistance; myCAF subgroup is involved in constituting the extracellular matrix and collagen production, matrix composition and collagen production, and the emCAF functionally characterized by energy metabolism.

CONCLUSIONS

TNBC has inter- and intra-tumor heterogeneity, and CAF is one of the sources of this heterogeneity. CD74, SASH3, CD2, TAGAP and CCR7 served as significant marker genes with prognostic and therapeutic value.

Targeting the hedgehog pathway in MET mutation cancers and its effects on cells associated with cancer development

The mutation of MET plays a crucial role in the initiation of cancer, while the Hedgehog (Hh) pathway also plays a significant role in cell differentiation and the maintenance of tumor stem cells. Conventional chemotherapy drugs are primarily designed to target the majority of cell populations within tumors rather than tumor stem cells. Consequently, after a brief period of remission, tumors often relapse. Moreover, the exclusive targeting of tumor stemness cell disregards the potential for other tumor cells to regain stemness and acquire drug resistance. As a result, current drugs that solely target the HGF/c-MET axis and the Hh pathway demonstrate only moderate efficacy in specific types of cancer. Mounting evidence indicates that these two pathways not only play important roles in cancer but also exert significant influence on the development of resistance to single-target therapies through the secretion of their own ligands. In this comprehensive review, we analyze and compare the potential impact of the Hh pathway on the tumor microenvironment (TME) in HGF/c-MET-driven tumor models, as well as the interplay between different cell types. Additionally, we further substantiate the potential and necessity of dual-pathway combination therapy as a critical target in MET addicted cancer treatment. Video Abstract.

Dissecting the tumor ecosystem of liver cancers in the single-cell era

Primary liver cancers (PLCs) are a broad class of malignancies that include HCC, intrahepatic cholangiocarcinoma, and combined hepatocellular and intrahepatic cholangiocarcinoma. PLCs are often associated with a poor prognosis due to their high relapse and low therapeutic response rates. Importantly, PLCs exist within a dynamic and complex tumor ecosystem, which includes malignant, immune, and stromal cells. It is critical to dissect the PLC tumor ecosystem to uncover the underlying mechanisms associated with tumorigenesis, relapse, and treatment resistance to facilitate the discovery of novel therapeutic targets. Single-cell and spatial multi-omics sequencing techniques offer an unprecedented opportunity to elucidate spatiotemporal interactions among heterogeneous cell types within the complex tumor ecosystem. In this review, we describe the latest advances in single-cell and spatial technologies and review their applications with respect to dissecting liver cancer tumor ecosystems.

Cancer-Associated Fibroblast Heterogeneity and Its Influence on the Extracellular Matrix and the Tumor Microenvironment

The tumor microenvironment comprises multiple cell types, like cancer cells, endothelial cells, fibroblasts, and immune cells. In recent years, there have been massive research efforts focusing not only on cancer cells, but also on other cell types of the tumor microenvironment, thereby aiming to expand and determine novel treatment options. Fibroblasts represent a heterogenous cell family consisting of numerous subtypes, which can alter immune cell fractions, facilitate or inhibit tumor growth, build pre-metastatic niches, or stabilize vessels. These effects can be achieved through cell-cell interactions, which form the extracellular matrix, or via the secretion of cytokines or chemokines. The pro- or antitumorigenic fibroblast phenotypes show variability not only among different cancer entities, but also among intraindividual sites, including primary tumors or metastatic lesions. Commonly prescribed for arterial hypertension, the inhibitors of the renin-angiotensin system have recently been described as having an inhibitory effect on fibroblasts. This inhibition leads to modified immune cell fractions and increased tissue stiffness, thereby contributing to overcoming therapy resistance and ultimately inhibiting tumor growth. However, it is important to note that the inhibition of fibroblasts can also have the opposite effect, potentially resulting in increased tumor growth. We aim to summarize the latest state of research regarding fibroblast heterogeneity and its intricate impact on the tumor microenvironment and extracellular matrix. Specifically, we focus on highlighting recent advancements in the comprehension of intraindividual heterogeneity and therapy options within this context.

Cholangiocarcinoma - novel biological insights and therapeutic strategies

In the past 5 years, important advances have been made in the scientific understanding and clinical management of cholangiocarcinoma (CCA). The cellular immune landscape of CCA has been characterized and tumour subsets with distinct immune microenvironments have been defined using molecular approaches. Among these subsets, the identification of 'immune-desert' tumours that are relatively devoid of immune cells emphasizes the need to consider the tumour immune microenvironment in the development of immunotherapy approaches. Progress has also made in identifying the complex heterogeneity and diverse functions of cancer-associated fibroblasts in this desmoplastic cancer. Assays measuring circulating cell-free DNA and cell-free tumour DNA are emerging as clinical tools for detection and monitoring of the disease. Molecularly targeted therapy for CCA has now become a reality, with three drugs targeting oncogenic fibroblast growth factor receptor 2 (FGFR2) fusions and one targeting neomorphic, gain-of-function variants of isocitrate dehydrogenase 1 (IDH1) obtaining regulatory approval. By contrast, immunotherapy using immune-checkpoint inhibitors has produced disappointing results in patients with CCA, underscoring the requirement for novel immune-based treatment strategies. Finally, liver transplantation for early stage intrahepatic CCA under research protocols is emerging as a viable therapeutic option in selected patients. This Review highlights and provides in-depth information on these advances.

Impact of immune tolerance mechanisms on the efficacy of immunotherapy in primary and secondary liver cancers

The liver is a functionally unique organ with an immunosuppressive microenvironment. The liver is the sixth most common site of primary cancer in humans and is a frequent site of metastasis from other solid tumors. The development of effective therapies for primary and metastatic liver cancer has been challenging due to the complex metabolic and immune microenvironment of the liver. The liver tumor microenvironment (TME) in primary and secondary (metastatic) liver cancers is heterogenous and consists of unique immune and stromal cell populations. Crosstalk between these cell populations and tumor cells creates an immunosuppressive microenvironment within the liver which potentiates cancer progression. Immune checkpoint inhibitors (ICIs) are now clinically approved for the management of primary and secondary liver cancer and can partially overcome liver immune tolerance, but their efficacy is limited. In this review, we describe the liver microenvironment and the use of immunotherapy in primary and secondary liver cancer. We discuss emerging combination strategies utilizing locoregional and systemic therapy approaches which may enhance efficacy of immunotherapy in primary and secondary liver cancer. A deeper understanding of the immunosuppressive microenvironment of the liver will inform novel therapies and therapeutic combinations in order to improve outcomes of patients with primary and secondary liver cancer.

The role of tumor microenvironment reprogramming in primary liver cancer chemotherapy resistance

Primary liver cancer (PLC), including hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC), and other rare tumours, is the second leading cause of cancer-related mortality. It has been a major contributor to the cancer burden worldwide. Of all primary liver cancer, HCC is the most common type. Over the past few decades, chemotherapy, immunotherapy and other therapies have been identified as applicable to the treatment of HCC. However, evidence suggests that chemotherapy resistance is associated with higher mortality rates in liver cancer. The tumour microenvironment (TME), which includes molecular, cellular, extracellular matrix(ECM), and vascular signalling pathways, is a complex ecosystem. It is now increasingly recognized that the tumour microenvironment plays a pivotal role in PLC prognosis, progression and treatment response. Cancer cells reprogram the tumour microenvironment to develop resistance to chemotherapy drugs distinct from normal differentiated tissues. Chemotherapy resistance mechanisms are reshaped during TME reprogramming. For this reason, TME reprogramming can provide a powerful tool to understand better both cancer-fate processes and regenerative, with the potential to develop a new treatment. This review discusses the recent progress of tumour drug resistance, particularly tumour microenvironment reprogramming in tumour chemotherapy resistance, and focuses on its potential application prospects.

Cancer-Associated Fibroblasts in Cholangiocarcinoma: Current Knowledge and Possible Implications for Therapy

Cholangiocarcinoma (CCA) is an aggressive neoplasia with an increasing incidence and mortality. It is characterized by a strong desmoplastic stroma surrounding cancer cells. Cancer-associated fibroblasts (CAFs) are the main cell type of CCA stroma and they have an important role in modulating cancer microenvironments. CAFs originate from multiple lines of cells and mainly consist of fibroblasts and alpha-smooth muscle actin (α-SMA) positive myofibroblast-like cells. The continuous cross-talking between CCA cells and desmoplastic stroma is permitted by CAF biochemical signals, which modulate a number of pathways. Stromal cell-derived factor-1 expression increases CAF recruitment to the tumor reactive stroma and influences apoptotic pathways. The Bcl-2 family protein enhances susceptibility to CAF apoptosis and PDGFRβ induces fibroblast migration and stimulates tumor lymphangiogenesis. Many factors related to CAFs may influence CCA prognosis. For instance, a better prognosis is associated with IL-33 expression and low stromal IL-6 (whose secretion is stimulated by microRNA). In contrast, a worst prognosis is given by the expression of PDGF-D, podoplanin, SDF-1, α-SMA high expression, and periostin. The maturity phenotype has a prognostic relevance too. New therapeutic strategies involving CAFs are currently under study. Promising results are obtained with anti-PlGF therapy, nintedanib (BIBF1120), navitoclax, IPI-926, resveratrol, and controlled hyperthermia.

Low expression of lncRNA APTR promotes gastric cancer progression

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APTR is actively expressed in gastric cancer cells.

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Low expression of APTR is associated with poor clinical characteristics in patients with gastric cancer.

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Silencing APTR promotes gastric cancer proliferation and invasiveness.

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APTR expression is negatively associated with inflammatory signaling in the gastric tumor microenvironment.

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LncRNA APRT is a potential biomarker for gastric cancer patients' diagnosis and prognosis, and could be a potential therapeutic target.

Background

Gastric cancer (GC) is one of the most common cancers worldwide and the majority of GC patients are diagnosed at advanced stages due to the lack of early detection biomarkers. LncRNAs have been shown to play important roles in various diseases and could be predictive biomarkers and therapeutic targets. Our study demonstrated that low expression of lncRNA APTR could promote gastric cancer progression.

Methods

Differentiated expressed lncRNAs were identified through analyzing TCGA paired GC RNA sequencing data. LncRNA APTR's clinical relevance was analyzed using the TCGA dataset and GEO datasets. APTR expression in patient samples was detected through qPCR. The proliferation, colony formation, and migration of GC cells were tested. Bioinformatic analyses were performed to explore APTR-affected signaling pathways in GC.

Results

LncRNA APTR is lower expressed in gastric tumor samples and low expression of APTR predicts a poor diagnosis and outcome in GC patients. Silencing APTR promotes gastric cancer proliferation and invasiveness. APTR expression is negatively correlated with inflammatory signaling in the gastric tumor microenvironment.

Conclusion

Our study showed that low expression of lncRNA APTR in gastric cancer is correlated with tumorigenesis and poor diagnosis and prognosis, which is a potential biomarker for gastric cancer patients' diagnosis and treatment.

Senescent Fibroblasts Generate a CAF Phenotype through the Stat3 Pathway

Aging has been recently reported to promote lung cancer initiation and progression. Senescent fibroblasts gain a cancer-associated fibroblast (CAF) phenotype, and exert a powerful influence on cancer behavior, such as tumor cell growth and metastasis. However, mechanisms linking fibroblast senescence with CAF activation remain poorly understood. Our study shows that senescent fibroblasts displayed CAF properties, including the highly expressed CAF markers, α-SMA and Vimentin, and CAF-specific factors, CXCL12, FGF10, IL6 and COL1A1, which significantly increased collagen contractile activity and promoted the migration and invasion of lung cancer cells, H1299 and A549. We were further able to show that CAF characteristics in senescent fibroblasts could be regulated by the Stat3 pathway. Intracellular ROS accumulation activates the Stat3 pathway during senescence. Thus, our findings indicate that senescent fibroblasts mediate a CAF function with the Stat3 pathway. We further propose a novel Stat3 dependent targetable mechanism, which is instrumental in mediating the migration and invasion of lung cancer cells.

Serum Levels of CXCL13 Are an Independent Predictor of Survival Following Resection of Biliary Tract Cancer

Simple Summary

Biliary tract cancer (BTC) is a primary liver malignancy with poor outcome. The identification of the ideal surgical candidates is often challenging and stratification algorithms comprising the parameters of individual tumor biology are missing. Here, we investigated a potential role of circulating CXCL1, CXCL10 and CXCL13 in patients with resectable BTC as novel biomarkers and could show that elevated levels of CXCL13 both before and after tumor resection identified a subgroup of patients with significantly impaired outcomes following tumor resection. Thus, the present study supports a fundamental role of the CXC chemokine family in BTC and identifies circulating levels of CXCL13 as a previously unrecognized marker for predicting outcomes following the resection of BTC.

Abstract

Background: The prognosis of biliary tract cancer (BTC) has remained very poor. Although tumor resection represents a potentially curative therapy for selected patients, tumor recurrence is common, and 5-year survival rates have remained below 50%. As stratification algorithms comprising the parameters of individual tumor biology are missing, the identification of ideal patients for extensive tumor surgery is often challenging. The CXC chemokine family exerts decisive functions in cell–cell interactions and has only recently been associated with cancer, but little is known about their function in BTC. Here, we aim to evaluate a potential role of circulating CXCL1, CXCL10 and CXCL13 in patients with resectable BTC. Methods: Serum levels of CXCL1, CXCL10 and CXCL13 were measured by multiplex immunoassay in a cohort of 119 BTC patients undergoing tumor resection and 50 control samples. Results: Circulating levels of CXCL1, CXCL10 and CXCL13 were all significantly elevated in BTC patients compared to healthy controls and increased the diagnostic power of established tumor markers such as CA19-9 when used in combination. Importantly, elevated levels of CXCL13 both before and after tumor resection identified a subgroup of patients with significantly impaired outcomes following tumor resection. As such, BTC patients with initial CXCL13 levels above the ideal prognostic cut-off value (25.01 pg/mL) had a median overall survival (OS) of 290 days compared to 969 days for patients with low initial CXCL13 levels. The prognostic value of circulating CXCL13 was further confirmed by uni- and multivariate Cox regression analyses. Finally, the individual kinetics of CXCL13 before and after tumor resection were also indicative of patient outcomes. Conclusion: Our data support a fundamental role of the CXC chemokine family in BTC and identified circulating levels of CXCL13 as a previously unrecognized marker for predicting outcomes following the resection of BTC.

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.

Identification of a Gene Signature of Cancer-Associated Fibroblasts to Predict Prognosis in Ovarian Cancer

Ovarian cancer (OvCa) is one of the most widespread malignant tumors, which has the highest morbidity and unsatisfactory clinical outcomes among all gynecological malignancies in the world. Previous studies found that cancer-associated fibroblasts (CAFs) play significant roles in tumor growth, progression, and chemoresistance. In the current research, weighted gene co-expression network analysis (WGCNA), univariable COX regression, and the least absolute shrinkage and selection operator (LASSO) analysis were applied to recognize CAF-specific genes. After multiple bioinformatic analyses, four genes (AXL, GPR176, ITGBL1, and TIMP3) were identified as OvCa-specific CAF markers and used to construct the prognostic signature (CAFRS). Furthermore, the specificity of the four genes' expression was further validated at the single-cell level, which was high-selectively expressed in CAFs. In addition, our results showed that CAFRS is an independent significant risk factor affecting the clinical outcomes of OvCa patients. Meanwhile, patients with higher CAFRS were more likely to establish chemoresistance to platinum. Besides, the CAFRS were notably correlated with well-known signal pathways that were related to tumor progression. In summary, our study identifies four CAF-specific genes and constructs a novel prognostic signature, which may provide more insights into precise prognostic assessment in OvCa.

Cellular senescence and the tumor microenvironment

The senescence‐associated secretory phenotype (SASP), where senescent cells produce a variety of secreted proteins including inflammatory cytokines, chemokines, matrix remodelling factors, growth factors and so on, plays pivotal but varying roles in the tumour microenvironment. The effects of SASP on the surrounding microenvironment depend on the cell type and process of cellular senescence induction, which is often associated with innate immunity. Via SASP‐mediated paracrine effects, senescent cells can remodel the surrounding tissues by modulating the character of adjacent cells, such as stromal, immune cells, as well as cancer cells. The SASP is associated with both tumour‐suppressive and tumour‐promoting effects, as observed in senescence surveillance effects (tumour‐suppressive) and suppression of anti‐tumour immunity in most senescent cancer‐associated fibroblasts and senescent T cells (tumour‐promoting). In this review, we discuss the features and roles of senescent cells in tumour microenvironment with emphasis on their context‐dependency that determines whether they promote or suppress cancer development. Potential usage of recently developed drugs that suppress the SASP (senomorphics) or selectively kill senescence cells (senolytics) in cancer therapy are also discussed.

Single-Cell Transcriptomics of Liver Cancer: Hype or Insights?

Hepatocellular carcinoma (HCC) is characterized by its high degrees of both inter- and intratumoral heterogeneity. Its complex tumor microenvironment is also crucial in promoting tumor progression. Recent advances in single-cell RNA sequencing provide an important highway to characterize the underlying pathogenesis and heterogeneity of HCC in an unprecedented degree of resolution. This review discusses the up-to-date discoveries from the latest studies of HCC with respect to the strength of single-cell RNA sequencing. We discuss its use in the dissection of the landscape of the intricate HCC ecosystem and highlight the major features at cellular levels, including the malignant cells, different immune cell types, and the various cell-cell interactions, which are crucial for developing effective immunotherapies. Finally, its translational applications will be discussed. Altogether, these explorations may give us some hints at the tumor growth and progression and drug resistance and recurrence, particularly in this era of personalized medicine.

The Trinity: Interplay among Cancer Cells, Fibroblasts, and Immune Cells in Pancreatic Cancer and Implication of CD8+ T Cell-Orientated Therapy

The microenvironment in tumors is complicated and is constituted by different cell types and stromal proteins. Among the cell types, the abundance of cancer cells, fibroblasts, and immune cells is high and these cells work as the “Trinity” in promoting tumorigenesis. Although unidirectional or bidirectional crosstalk between two independent cell types has been well characterized, the multi-directional interplays between cancer cells, fibroblasts, and immune cells in vitro and in vivo are still unclear. We summarize recent studies in addressing the interaction of the “Trinity” members in the tumor microenvironment and propose a functional network for how these members communicate with each other. In addition, we discuss the underlying mechanisms mediating the interplay. Moreover, correlations of the alterations in the distribution and functionality of cancer cells, fibroblasts, and immune cells under different circumstances are reviewed. Finally, we point out the future application of CD8⁺ T cell-oriented therapy in the treatment of pancreatic cancer.

Immune Modulatory Properties of Collagen in Cancer

During tumor growth the extracellular matrix (ECM) undergoes dramatic remodeling. The normal ECM is degraded and substituted with a tumor-specific ECM, which is often of higher collagen density and increased stiffness. The structure and collagen density of the tumor-specific ECM has been associated with poor prognosis in several types of cancer. However, the reason for this association is still largely unknown. Collagen can promote cancer cell growth and migration, but recent studies have shown that collagens can also affect the function and phenotype of various types of tumor-infiltrating immune cells such as tumor-associated macrophages (TAMs) and T cells. This suggests that tumor-associated collagen could have important immune modulatory functions within the tumor microenvironment, affecting cancer progression as well as the efficacy of cancer immunotherapy. The effects of tumor-associated collagen on immune cells could help explain why a high collagen density in tumors is often correlated with a poor prognosis. Knowledge about immune modulatory functions of collagen could potentially identify targets for improving current cancer therapies or for development of new treatments. In this review, the current knowledge about the ability of collagen to influence T cell activity will be summarized. This includes direct interactions with T cells as well as induction of immune suppressive activity in other immune cells such as macrophages. Additionally, the potential effects of collagen on the efficacy of cancer immunotherapy will be discussed.

Review: Challenges of In Vitro CAF Modelling in Liver Cancers

Simple Summary

Liver cancer and tumours spreading from other organs to the liver are associated with high death rates. Current treatments include surgical removal of the tumour and chemotherapy. Unfortunately, patients are often re-diagnosed with liver nodules in the years after cessation of the treatment. Therefore, scientists are looking for alternative treatment strategies, and these include targeting the tumour environment. The tumour environment includes the cancer-associated fibroblasts, which could be an interesting target for therapy in combination with current strategies. In this review paper we summarize the current models to investigate the effect of the tumour on the cancer-associated fibroblasts. Not many studies focus on the cancer-associated fibroblasts in non-animal models and this should improve in order to better understand the role of the cancer-associated fibroblasts and to evaluate the potential of cancer-associated fibroblast-directed therapies.

Abstract

Primary and secondary liver cancer are the third cause of death in the world, and as the incidence is increasing, liver cancer represents a global health burden. Current treatment strategies are insufficient to permanently cure patients from this devastating disease, and therefore other approaches are under investigation. The importance of cancer-associated fibroblasts (CAFs) in the tumour microenvironment is evident, and many pre-clinical studies have shown increased tumour aggressiveness in the presence of CAFs. However, it remains unclear how hepatic stellate cells are triggered by the tumour to become CAFs and how the recently described CAF subtypes originate and orchestrate pro-tumoural effects. Specialized in vitro systems will be needed to address these questions. In this review, we present the currently used in vitro models to study CAFs in primary and secondary liver cancer and highlight the trend from using oversimplified 2D culture systems to more complex 3D models. Relatively few studies report on the impact of cancer (sub)types on CAFs and the tumour microenvironment, and most studies investigated the impact of secreted factors due to the nature of the models.

Cholangiocarcinoma: what are the most valuable therapeutic targets - cancer-associated fibroblasts, immune cells, or beyond T cells?

INTRODUCTION

CCAs are dense and desmoplastic tumors with an abundant tumor microenviroment (TME). The evolving TME is characterized by reciprocal interactions between cancer cells and their environment and is essential in facilitating tumor progression. The TME has nonimmune and immune components. Nonimmune cell types include cancer-associated fibroblasts (CAFs) and endothelial cells accompanying tumor angiogenesis. Immune cell types include elements of the innate and adaptive immune response, and can have pro-tumor or antitumor roles. The TME can shape treatment response and resistance. Therefore, elements of the TME are attractive therapeutic targets. TME targeting therapies have been evaluated in preclinical and clinical studies but only a small subset of patients has a meaningful response.

AREAS COVERED

We discuss the TME components and potential TME targeting strategies. Literature search was performed on PubMed and ClinicalTrials.gov until October 2021.

EXPERT OPINION

Elucidating the CCA TME is essential for developing effective treatment strategies. Preclinical models that recapitulate the disease (such as organoids) are important tools in uncovering the intricate cross talk in the CCA TME. Characterization of patient-derived specimens using multi-omic and single-omic technologies can dissect the cellular interplay in the CCA TME, which can guide development of effective treatment strategies and identify biomarkers for patient stratification.