A peek into cancer-associated fibroblasts: origins, functions and translational impact

METI: deep profiling of tumor ecosystems by integrating cell morphology and spatial transcriptomics

Recent advances in spatial transcriptomics (ST) techniques provide valuable insights into cellular interactions within the tumor microenvironment (TME). However, most analytical tools lack consideration of histological features and rely on matched single-cell RNA sequencing data, limiting their effectiveness in TME studies. To address this, we introduce the Morphology-Enhanced Spatial Transcriptome Analysis Integrator (METI), an end-to-end framework that maps cancer cells and TME components, stratifies cell types and states, and analyzes cell co-localization. By integrating spatial transcriptomics, cell morphology, and curated gene signatures, METI enhances our understanding of the molecular landscape and cellular interactions within the tissue. We evaluate the performance of METI on ST data generated from various tumor tissues, including gastric, lung, and bladder cancers, as well as premalignant tissues. We also conduct a quantitative comparison of METI with existing clustering and cell deconvolution tools, demonstrating METI's robust and consistent performance.

Cancer-Associated-Fibroblast-Mediated Paracrine and Autocrine SDF-1/CXCR4 Signaling Promotes Stemness and Aggressiveness of Colorectal Cancers

Colorectal cancer (CRC) is a leading cause of cancer mortality worldwide, and cancer-associated fibroblasts (CAFs) play a major role in the tumor microenvironment (TME), which facilitates the progression of CRC. It is critical to understand how CAFs promote the progression of CRC for the development of novel therapeutic approaches. The purpose of this study was to understand how CAF-derived stromal-derived factor-1 (SDF-1) and its interactions with the corresponding C-X-C motif chemokine receptor 4 (CXCR4) promote CRC progression. Our study focused on their roles in promoting tumor cell migration and invasion and their effects on the characteristics of cancer stem cells (CSCs), which ultimately impact patient outcomes. Here, using in vivo approaches and clinical histological samples, we analyzed the influence of secreted SDF-1 on CRC progression, especially in terms of tumor cell behavior and stemness. We demonstrated that CAF-secreted SDF-1 significantly enhanced CRC cell migration and invasion through paracrine signaling. In addition, the overexpression of SDF-1 in CRC cell lines HT29 and HCT-116 triggered these cells to generate autocrine SDF-1 signaling, which further enhanced their CSC characteristics, including those of migration, invasion, and spheroid formation. An immunohistochemical study showed a close relationship between SDF-1 and CXCR4 expression in CRC tissue, and this significantly affected patient outcomes. The administration of AMD3100, an inhibitor of CXCR4, reversed the entire phenomenon. Our results strongly suggest that targeting this signaling axis in CRC is a feasible approach to attenuating tumor progression, and it may, therefore, serve as an alternative treatment method to improve the prognosis of patients with CRC, especially those with advanced, recurrent, or metastatic CRC following standard therapy.

Remodeling of tumor microenvironment by extracellular matrix protein 1a differentially regulates ovarian cancer metastasis

We previously reported that extracellular matrix protein 1 isoform a (ECM1a) promotes epithelial ovarian cancer (EOC) through autocrine signaling by binding to cell surface receptors αXβ2. However, the role of ECM1a as a secretory molecule in the tumor microenvironment is rarely reported. In this study, we constructed murine Ecm1-knockout mice and human ECM1a-knockin mice and further generated orthotopic or peritoneal xenograft tumor models to mimic the different metastatic stages of EOC. We show that ECM1a induces oncogenic metastasis of orthotopic xenograft tumors, but inhibits early-metastasis of peritoneal xenograft tumors. ECM1a remodels extracellular matrices (ECM) and promotes remote metastases by recruiting and transforming bone marrow mesenchymal stem cells (BMSCs) into platelet-derived growth factor receptor beta (PDGFRβ+) cancer-associated fibroblasts (CAFs) and facilitating the secretion of angiopoietin-like protein 2 (ANGPTL2). Competing with ECM1a, ANGPTL2 also binds to integrin αX through the P1/P2 peptides, resulting in negative effects on BMSC differentiation. Collectively, this study reveals the dual functions of ECM1a in remodeling of TME during tumor progression, emphasizing the complexity of EOC phenotypic heterogeneity and metastasis.

Activation of STING in pancreatic cancer-associated fibroblasts exerts an antitumor effect by enhancing tumor immunity

Pancreatic ductal adenocarcinoma (PDAC) has a high mortality rate; therefore, the development of effective treatments is a priority. The stimulator of interferon genes (STING) pathway enhances tumor immunity by inducing the production of type 1 interferon (IFN) and proinflammatory cytokines and chemokines and promoting the infiltration of cytotoxic T cells. To assess the function of STING on pancreatic tumorigenesis, Ptf1aER-Cre/+ LSL-KrasG12D/+ p53loxP/loxP mice (KPC mice) and Ptf1aER-Cre/+ LSL-KrasG12D/+ p53loxP/loxP/STING-/- mice (KPCS mice) were generated. However, STING deletion did not affect pancreatic tumorigenesis in mice. Because STING is expressed not only in immune cells but also in cancer-associated fibroblasts (CAFs), we evaluated the STING function in PDAC CAFs. A mouse STING agonist 5,6-Dimethyl-9-oxo-9H-xanthene-4-acetic acid (DMXAA) was administered to KPC mice and CAFs from KPC mice and the resulting immune response was evaluated. DMXAA activated STING in PDAC CAFs in KPC mice, promoting cytotoxic T cell infiltration by secreting proinflammatory cytokines and enhancing tumor immunity. We next generated STING-deficient PDAC cells and subcutaneous tumors in which STING was expressed only in CAFs by performing bone marrow transplantation and assessed the antitumor effect of STING-activated CAFs. The administration of DMXAA to subcutaneous tumors expressing STING only in CAFs sustained the antitumor effect of DMXAA. About half of human PDACs lacked STING expression in the cancer stroma, suggesting that STING activation in PDAC CAFs exerts an antitumor effect, and STING agonists can be more effective in tumors with high than in those with low STING expression in the stroma.

Cancer-associated fibroblasts and prostate cancer stem cells: crosstalk mechanisms and implications for disease progression

The functional heterogeneity and ecological niche of prostate cancer stem cells (PCSCs), which are major drivers of prostate cancer development and treatment resistance, have attracted considerable research attention. Cancer-associated fibroblasts (CAFs), which are crucial components of the tumor microenvironment (TME), substantially affect PCSC stemness. Additionally, CAFs promote PCSC growth and survival by releasing signaling molecules and modifying the surrounding environment. Conversely, PCSCs may affect the characteristics and behavior of CAFs by producing various molecules. This crosstalk mechanism is potentially crucial for prostate cancer progression and the development of treatment resistance. Using organoids to model the TME enables an in-depth study of CAF-PCSC interactions, providing a valuable preclinical tool to accurately evaluate potential target genes and design novel treatment strategies for prostate cancer. The objective of this review is to discuss the current research on the multilevel and multitarget regulatory mechanisms underlying CAF-PCSC interactions and crosstalk, aiming to inform therapeutic approaches that address challenges in prostate cancer treatment.

Identification of CAF-related lncRNAs at the pan-cancer level represents a potential carcinogenic risk

Cancer-associated fibroblasts (CAFs) are increasingly recognized as playing a crucial role in regulating cancer progression and metastasis. These cells can be activated by long non-coding RNAs (lncRNAs), promoting the malignant biological processes of tumor cells. Therefore, it is essential to understand the regulatory relationship between CAFs and lncRNAs in cancers. Here, we identified CAF-related lncRNAs at the pan-cancer level to systematically predict their potential regulatory functions. The identified lncRNAs were also validated using various external data at both tissue and cellular levels. This study has revealed that these CAF-related lncRNAs exhibit expression perturbations in cancers and are highly correlated with the infiltration of stromal cells, particularly fibroblasts and endothelial cells. By prioritizing a list of CAF-related lncRNAs, we can further distinguish patient subtypes that show survival and molecular differences. In addition, we have developed a web server, CAFLnc (https://46906u5t63.zicp.fun/CAFLnc/), to visualize our results. In conclusion, CAF-related lncRNAs hold great potential as a valuable resource for comprehending lncRNA functions and advancing the identification of biomarkers for cancer progression and therapeutic targets in cancer treatment.

Biophysical perspectives to understanding cancer-associated fibroblasts

The understanding of cancer has evolved significantly, with the tumor microenvironment (TME) now recognized as a critical factor influencing the onset and progression of the disease. This broader perspective challenges the traditional view that cancer is primarily caused by mutations, instead emphasizing the dynamic interaction between different cell types and physicochemical factors within the TME. Among these factors, cancer-associated fibroblasts (CAFs) command attention for their profound influence on tumor behavior and patient prognoses. Despite their recognized importance, the biophysical and mechanical interactions of CAFs within the TME remain elusive. This review examines the distinctive physical characteristics of CAFs, their morphological attributes, and mechanical interactions within the TME. We discuss the impact of mechanotransduction on CAF function and highlight how these cells communicate mechanically with neighboring cancer cells, thereby shaping the path of tumor development and progression. By concentrating on the biomechanical regulation of CAFs, this review aims to deepen our understanding of their role in the TME and to illuminate new biomechanical-based therapeutic strategies.

Myxoid Pseudotumor Changes Affecting the Distal Ureter Associated With Urothelial Carcinoma In Situ

Myxoid pseudotumor is a pseudoneoplastic fibroblastic proliferation that has been described in the perinephric and renal sinus fat tissue. It is characterized by the presence of a myxoid matrix, intermingled with the adipocytes, and a hypocellular population of spindle-shaped and stellate cells. We report a myxoid pseudotumor involving the distal ureter, which broadens the spectrum of possible localizations of this lesion around the urinary tract. It occurred in an 80-year-old patient who underwent a nephroureterectomy indicated after an incidental radiological finding of a thickening of the distal left ureter wall which suggested a ureteral neoplasm. He had two voided urine and one ureteroscopic sample cytologies diagnosed as high-grade urothelial carcinoma, as well as a retrograde ureteroscopy ureteral biopsy which was diagnosed as urothelial carcinoma in situ. This emphasizes the problem of the possible misdiagnosis of myxoid pseudotumor as a ureteral infiltrative carcinoma due to the radiological findings being badly interpreted, compounded by the preoperative cytohistologic data on malignancy. A diffuse urothelial carcinoma in situ was seen in our specimen without infiltrative or papillary tumors. This would not support an obstructive pathogenetic mechanism as has been hypothesized for myxoid pseudotumor.

Exploring the multifaceted role of direct interaction between cancer cells and fibroblasts in cancer progression

The interaction between the tumor microenvironment (TME) and the cancer cells is a complex and mutually beneficial system that leads to rapid cancer cells proliferation, metastasis, and resistance to therapy. It is now recognized that cancer cells are not isolated, and tumor progression is governed among others, by many components of the TME. The reciprocal cross-talk between cancer cells and their microenvironment can be indirect through the secretion of extracellular matrix (ECM) proteins and paracrine signaling through exosomes, cytokines, and growth factors, or direct by cell-to-cell contact mediated by cell surface receptors and adhesion molecules. Among TME components, cancer-associated fibroblasts (CAFs) are of unique interest. As one of the most abundant components of the TME, CAFs play key roles in the reorganization of the extracellular matrix, facilitating metastasis and chemotherapy evasion. Both direct and indirect roles have been described for CAFs in modulating tumor progression. In this review, we focus on recent advances in understanding the role of direct contact between cancer cells and cancer-associated fibroblasts (CAFs) in driving tumor development and metastasis. We also summarize recent findings on the role of direct contact between cancer cells and CAFs in chemotherapy resistance.

Fibroblasts from HPV-negative oropharynx squamous cell carcinomas stimulate the release of osteopontin from cancer cells via the release of IL-6

Introduction

HPV-associated oropharyngeal squamous cell carcinoma (OPSCC) shows distinct biological and clinical behaviour when compared to HPV-negative OPSCC. The overall role of the tumour microenvironment (TME) in head and neck cancer progression and metastasis has been studied intensively, but differences in HPV-negative and HPV-positive OPSCCs are less understood.

Objective

To investigate the role of cancer-associated fibroblasts (CAFs) and the functional interactions of normal tonsil fibroblasts (NTFs) and OP CAFs with HPV+ and HPV- OPSCC cells and explore novel candidates in tumour-fibroblast crosstalk.

Materials and methods

A retrospective cohort of 143 primary OPSCCs was characterised using HPV16/18 RNAScope assay, p16 IHC and ɑ-SMA. Four OPSCC, three NTF and 2 new OPSCC CAF cultures were used to assess the cytokine-based interactions using cytokine arrays on conditioned media (CM), followed by co-culture approaches to identify the role of individual cell types and the role of OPN (SPP1) and IL-6 in SCC/fibroblast communication.

Results

HPV status was associated with better overall survival. Although ɑ-SMA expression was observed in both OPSCC subtypes, it provided survival stratification only in the HPV-positive group (Log-Rank p = 0.02). Three normal tonsillar fibroblast cultures (NTFs) were characterised by induction of myofibroblastic and senescent phenotypes with similar reactivity to our published NOF phenotype. The OPSCC-derived CAF cultures were characterised and their baseline myofibroblastic and senescence phenotypes varied. Cytokine array analysis of CM to identify novel candidates in the crosstalk between OPSCC tumour cells and NTFs/CAFs identified differences in the cytokine profiles on comparison of HPV+ and HPV- OPSCC cells. Osteopontin (OPN/SPP1) was identified, particularly in HPV-negative OPSCC cell analyses. We have demonstrated that OPN was produced by the OPSCC cells and revealed an associated upregulation of IL-6 in fibroblasts. Treatment of NTFs with rOPN showed alteration in phenotype, including increased contraction and IL-6 production. Antibody-mediated inhibition of CD44v6 attenuated the production of IL-6 by OPN in NTFs.

Conclusion

This investigation with OPSCC fibroblasts provides novel insights into the role of CAFs in OPSCC mediated by IL-6 stimulated release of OPN from HPV negative OPSCC cells. The details of HPV-positive SCC cell/fibroblast cytokine crosstalk remain elusive.

SERPINE1: Role in Cholangiocarcinoma Progression and a Therapeutic Target in the Desmoplastic Microenvironment

A heterogenous population of inflammatory elements, other immune and nonimmune cells and cancer-associated fibroblasts (CAFs) are evident in solid malignancies where they coexist with the growing tumor mass. In highly desmoplastic malignancies, CAFs are the prominent mesenchymal cell type in the tumor microenvironment (TME), where their presence and abundance signal a poor prognosis. CAFs play a major role in the progression of various cancers by remodeling the supporting stroma into a dense, fibrotic matrix while secreting factors that promote the maintenance of cancer stem-like characteristics, tumor cell survival, aggressive growth and metastasis and reduced sensitivity to chemotherapeutics. Tumors with high stromal fibrotic signatures are more likely to be associated with drug resistance and eventual relapse. Identifying the molecular underpinnings for such multidirectional crosstalk among the various normal and neoplastic cell types in the TME may provide new targets and novel opportunities for therapeutic intervention. This review highlights recent concepts regarding the complexity of CAF biology in cholangiocarcinoma, a highly desmoplastic cancer. The discussion focuses on CAF heterogeneity, functionality in drug resistance, contributions to a progressively fibrotic tumor stroma, the involved signaling pathways and the participating genes.

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.

Activated fibroblasts modify keratinocyte stem niche through TET1 and IL-6 to promote their rapid transformation in a mouse model of prenatal arsenic exposure

Early life exposure to environmental pollutants such as arsenic (As) can increase the risk of cancers in the offspring. In an earlier study, we showed that only prenatal As exposure significantly increases epidermal stem cell proliferation and accelerates skin tumorigenesis in BALB/c mouse offspring. In the present work, we have examined the role of As-conditioned dermal fibroblasts (DFs) in creating pro-tumorigenic niches for Keratinocyte stem cells (KSCs) in the offspring. DFs isolated from prenatally exposed animals showed increased levels of activation markers (α-SMA, Fibronectin, Collagen IV), induction of ten-eleven translocation methylcytosine dioxygenase 1(TET1), and secreted high levels of niche modifying IL-6. This led to enhanced proliferation, migration, and survival of KSCs. Increased IL-6 production in As-conditioned fibroblast was driven through TET1 mediated 5-mC to 5-hmC conversion at -698/-526 and -856/-679 region on its promoter. IL-6 further acted through downstream activation of JAK2-STAT3 signaling, promoting epithelial-to-mesenchymal transition (EMT) in KSCs. Inhibition of pSTAT3 induced by IL-6 reduced the EMT process in KSCs resulting in a significant decrease in their proliferation, migration, and colony formation. Our results indicate that IL-6 produced by prenatally conditioned fibroblasts plays a major role in regulating the KSC niche and promoting skin tumor development in As-exposed offspring.

MiR-200c reprograms fibroblasts to recapitulate the phenotype of CAFs in breast cancer progression

Mesenchymal-epithelial plasticity driving cancer progression in cancer-associated fibroblasts (CAFs) is undetermined. This work identifies a subgroup of CAFs in human breast cancer exhibiting mesenchymal-to-epithelial transition (MET) or epithelial-like profile with high miR-200c expression. MiR-200c overexpression in fibroblasts is sufficient to drive breast cancer aggressiveness. Oxidative stress in the tumor microenvironment induces miR-200c by DNA demethylation. Proteomics, RNA-seq and functional analyses reveal that miR-200c is a novel positive regulator of NFκB-HIF signaling via COMMD1 downregulation and stimulates pro-tumorigenic inflammation and glycolysis. Reprogramming fibroblasts toward MET via miR-200c reduces stemness and induces a senescent phenotype. This pro-tumorigenic profile in CAFs fosters carcinoma cell resistance to apoptosis, proliferation and immunosuppression, leading to primary tumor growth, metastases, and resistance to immuno-chemotherapy. Conversely, miR-200c inhibition in fibroblasts restrains tumor growth with abated oxidative stress and an anti-tumorigenic immune environment. This work determines the mechanisms by which MET in CAFs via miR-200c transcriptional enrichment with DNA demethylation triggered by oxidative stress promotes cancer progression. CAFs undergoing MET trans-differentiation and senescence coordinate heterotypic signaling that may be targeted as an anti-cancer strategy.

Fibroblast heterogeneity and functions: insights from single-cell sequencing in wound healing, breast cancer, ovarian cancer and melanoma

Cancer has been described as the wound that does not heal, in large part due to fibroblast involvement. Activation of cancer-associated fibroblasts (CAFs) contributes to critical features of the tumor microenvironment, including upregulation of key marker proteins, recruitment of immune cells, and deposition of extracellular matrix (ECM)-similar to fibroblast activation in injury-induced wound healing. Prior to the widespread availability of single-cell RNA sequencing (scRNA seq), studies of CAFs or fibroblasts in wound healing largely relied on models guided by individual fibroblast markers, or methods with less resolution to unravel the heterogeneous nature of CAFs and wound healing fibroblasts (especially regarding scarring outcome). Here, insights from the enhanced resolution provided by scRNA sequencing of fibroblasts in normal wound healing, breast cancer, ovarian cancer, and melanoma are discussed. These data have revealed differences in expression of established canonical activation marker genes, epigenetic modifications, fibroblast lineages, new gene and proteins of clinical interest for further experimentation, and novel signaling interactions with other cell types that include spatial information.

Modulating tumoral exosomes and fibroblast phenotype using nanoliposomes augments cancer immunotherapy

Cancer cells program fibroblasts into cancer associated fibroblasts (CAFs) in a two-step manner. First, cancer cells secrete exosomes to program quiescent fibroblasts into activated CAFs. Second, cancer cells maintain the CAF phenotype via activation of signal transduction pathways. We rationalized that inhibiting this two-step process can normalize CAFs into quiescent fibroblasts and augment the efficacy of immunotherapy. We show that cancer cell-targeted nanoliposomes that inhibit sequential steps of exosome biogenesis and release from lung cancer cells block the differentiation of lung fibroblasts into CAFs. In parallel, we demonstrate that CAF-targeted nanoliposomes that block two distinct nodes in fibroblast growth factor receptor (FGFR)-Wnt/β-catenin signaling pathway can reverse activate CAFs into quiescent fibroblasts. Co-administration of both nanoliposomes significantly improves the infiltration of cytotoxic T cells and enhances the antitumor efficacy of αPD-L1 in immunocompetent lung cancer-bearing mice. Simultaneously blocking the tumoral exosome-mediated activation of fibroblasts and FGFR-Wnt/β-catenin signaling constitutes a promising approach to augment immunotherapy.

It's all about the base: stromal cells are central orchestrators of metastasis

The tumor microenvironment (TME) is an integral part of tumors and plays a central role in all stages of carcinogenesis and progression. Each organ has a unique and heterogeneous microenvironment, which affects the ability of disseminated cells to grow in the new and sometimes hostile metastatic niche. Resident stromal cells, such as fibroblasts, osteoblasts, and astrocytes, are essential culprits in the modulation of metastatic progression: they transition from being sentinels of tissue integrity to being dysfunctional perpetrators that support metastatic outgrowth. Therefore, better understanding of the complexity of their reciprocal interactions with cancer cells and with other components of the TME is essential to enable the design of novel therapeutic approaches to prevent metastatic relapse.

Prostate Cancer and the Mevalonate Pathway

Antineoplastic therapies for prostate cancer (PCa) have traditionally centered around the androgen receptor (AR) pathway, which has demonstrated a significant role in oncogenesis. Nevertheless, it is becoming progressively apparent that therapeutic strategies must diversify their focus due to the emergence of resistance mechanisms that the tumor employs when subjected to monomolecular treatments. This review illustrates how the dysregulation of the lipid metabolic pathway constitutes a survival strategy adopted by tumors to evade eradication efforts. Integrating this aspect into oncological management could prove valuable in combating PCa.

Forces at play: exploring factors affecting the cancer metastasis

Metastatic disease, a leading and lethal indication of deaths associated with tumors, results from the dissemination of metastatic tumor cells from the site of primary origin to a distant organ. Dispersion of metastatic cells during the development of tumors at distant organs leads to failure to comply with conventional treatments, ultimately instigating abrupt tissue homeostasis and organ failure. Increasing evidence indicates that the tumor microenvironment (TME) is a crucial factor in cancer progression and the process of metastatic tumor development at secondary sites. TME comprises several factors contributing to the initiation and progression of the metastatic cascade. Among these, various cell types in TME, such as mesenchymal stem cells (MSCs), lymphatic endothelial cells (LECs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), T cells, and tumor-associated macrophages (TAMs), are significant players participating in cancer metastasis. Besides, various other factors, such as extracellular matrix (ECM), gut microbiota, circadian rhythm, and hypoxia, also shape the TME and impact the metastatic cascade. A thorough understanding of the functions of TME components in tumor progression and metastasis is necessary to discover new therapeutic strategies targeting the metastatic tumor cells and TME. Therefore, we reviewed these pivotal TME components and highlighted the background knowledge on how these cell types and disrupted components of TME influence the metastatic cascade and establish the premetastatic niche. This review will help researchers identify these altered components' molecular patterns and design an optimized, targeted therapy to treat solid tumors and restrict metastatic cascade.

Extracellular vesicles released by hypoxia-induced tumor-associated fibroblasts impart chemoresistance to breast cancer cells via long noncoding RNA H19 delivery

Recently, extracellular vesicles (EVs) have been emphasized in regulating the hypoxic tumor microenvironment of breast cancer (BC), where tumor-associated fibroblasts (TAFs) play a significant role. In this study, we describe possible molecular mechanisms behind the pro-tumoral effects of EVs, secreted by hypoxia (HP)-induced TAFs, on BC cell growth, metastasis, and chemoresistance. These mechanisms are based on long noncoding RNA H19 (H19) identified by microarray analysis. We employed an in silico approach to identify differentially expressed lncRNAs that were associated with BC. Subsequently, we explored possible downstream regulatory mechanisms. We isolated EVs from TAFs that were exposed to HP, and these EVs were denoted as HP-TAF-EVs henceforth. MTT, transwell, flow cytometry, and TUNEL assays were performed to assess the malignant phenotypes of BC cells. A paclitaxel (TAX)-resistant BC cell line was constructed, and xenograft tumor and lung metastasis models were established in nude mice for in vivo verification. Our observation revealed that lncRNA H19 was significantly overexpressed, whereas miR-497 was notably downregulated in BC. HP induced activation of TAFs and stimulated the secretion of EVs. Coculture of HP-TAF-EVs and BC cells led to an increase in TAX resistance of the latter. HP-TAF-EVs upregulated methylation of miR-497 by delivering lncRNA H19, which recruited DNMT1, thus lowering the expression of miR-497. In addition, lncRNA H19-containing HP-TAF-EVs hindered miR-497 expression, enhancing tumorigenesis and TAX resistance of BC cells in vivo. Our study presents evidence for the contribution of lncRNA H19-containing HP-TAF-EVs in the reduction of miR-497 expression through the recruitment of DNMT1, which in turn promotes the growth, metastasis, and chemoresistance of BC cells.

High ANO1 expression is a prognostic factor and correlated with an immunosuppressive tumor microenvironment in pancreatic cancer

Background

Aminooctylamine (ANO1) plays an oncogenic role in various cancers. However. its role in pancreatic cancer (PC) has rarely been studied. This study investigated the prognostic value of ANO1 and its correlation with the tumor microenvironment (TME) in PC.

Methods

Consecutive patients with PC (n = 119) were enrolled. The expression of ANO1 in cancer cells, the expression of fibroblast activation protein (FAP) and alpha smooth muscle actin in cancer-associated fibroblasts (CAFs), and the numbers of CD8- and FOXP3-positive tumor-infiltrating lymphocytes (TILs) were evaluated using immunohistochemistry. The prognostic value of ANO1 and its correlation with CAF subgroups and TILs were analyzed. The possible mechanism of ANO1 in the TME of PC was predicted using the the Cancer Genome Atlas (TCGA) dataset.

Results

The expression of AN01 was correlated with overall survival (OS) and disease-free survival. Multi-factor analysis showed that high ANO1 expression was an independent adverse prognostic factor for OS (hazard ratio, 4.137; P = 0.001). ANO1 expression was positively correlated with the expression of FAP in CAFs (P < 0.001) and negatively correlated with the number of CD8-positive TILs (P = 0.005), which was also validated by bioinformatics analysis in the TCGA dataset. Moreover, bioinformatic analysis of the TCGA dataset revealed that ANO1 may induce an immunosuppressive tumor microenvironment in pancreatic cancer in a paracrine manner.

Conclusion

ANO1 is a prognostic factor in patients with PC after radical resection. ANO1 may induce an immunosuppressive tumor microenvironment in PC in a paracrine manner, suggesting that ANO1 may be a novel therapeutic target.

The biological role of extracellular vesicles in gastric cancer metastasis

Gastric cancer (GC) is a tumor characterized by high incidence and mortality, with metastasis being the primary cause of poor prognosis. Extracellular vesicles (EVs) are an important intercellular communication medium. They contain bioactive substances such as proteins, nucleic acids, and lipids. EVs play a crucial biological role in the process of GC metastasis. Through mechanisms such as remodeling the tumor microenvironment (TME), immune suppression, promoting angiogenesis, and facilitating epithelial-mesenchymal transition (EMT) and mesothelial-mesenchymal transition (MMT), EVs promote invasion and metastasis in GC. Further exploration of the biological roles of EVs will contribute to our understanding of the mechanisms underlying GC metastasis and may provide novel targets and strategies for the diagnosis and treatment of GC. In this review, we summarize the mechanisms by which EVs influence GC metastasis from four aspects: remodeling the TME, modulating the immune system, influencing angiogenesis, and modulating the processes of EMT and MMT. Finally, we briefly summarized the organotropism of GC metastasis as well as the potential and limitations of EVs in GC.

Protein cargo in extracellular vesicles as the key mediator in the progression of cancer

Exosomes are small vesicles of endosomal origin that are released by almost all cell types, even those that are pathologically altered. Exosomes widely participate in cell-to-cell communication via transferring cargo, including nucleic acids, proteins, and other metabolites, into recipient cells. Tumour-derived exosomes (TDEs) participate in many important molecular pathways and affect various hallmarks of cancer, including fibroblasts activation, modification of the tumour microenvironment (TME), modulation of immune responses, angiogenesis promotion, setting the pre-metastatic niche, enhancing metastatic potential, and affecting therapy sensitivity and resistance. The unique exosome biogenesis, composition, nontoxicity, and ability to target specific tumour cells bring up their use as promising drug carriers and cancer biomarkers. In this review, we focus on the role of exosomes, with an emphasis on their protein cargo, in the key mechanisms promoting cancer progression. We also briefly summarise the mechanism of exosome biogenesis, its structure, protein composition, and potential as a signalling hub in both normal and pathological conditions. Video Abstract.

68Ga-FAPI-04 Positron Emission Tomography Distinguishes Malignancy From 18F-FDG-Avid Colorectal Lesions

PURPOSE

Lesions with a high uptake of 18F-fluorodeoxyglucose (18F-FDG) on positron emission tomography-computed tomography (PET-CT) can be benign and malignant. New radiotracers, such as the gallium 68 (68Ga)-labeled fibroblast activation protein inhibitor 4 (FAPI-04), could be used to diagnose colorectal carcinoma. This study aimed to evaluate the efficacy of 68Ga-FAPI-04 PET in differentiating benign from malignant 18F-FDG-avid colorectal lesions.

METHODS AND MATERIALS

An azoxymethane/dextran sodium sulfate (AOM/DSS)-induced rat colorectal tumor model was developed. Double-tracer 68Ga-FAPI-04 and 18F-FDG PET-CT were applied in the rat model and 22 patients. The PET-CT data were analyzed with enteroscopy, histopathologic observations, immunohistochemistry (IHC) staining, and radioautography results. One hundred seventy-two patients with pathologically confirmed colorectal lesions were enrolled in FAP IHC staining.

RESULTS

We found that 68Ga-FAPI-04 PET-CT imaging accurately distinguished the malignant from benign inflammatory lesions in an AOM/DSS-induced rat colorectal tumor model. Of 22 patients with gastric cancer but without colorectal carcinoma, 8 had 18F-FDG uptake in the colorectum, but 68Ga-FAPI-04 PET was negative in these sites. An inflammatory lesion or adenoma did not interfere with 68Ga-FAPI-04 PET imaging. Among the 18F-FDG-avid colorectal lesions, 80 of 94 pathologically malignant lesions (85.1%) were FAP-positive, and only 16 of the 78 premalignant or benign lesions (20.5%) had a weak 68Ga-FAPI-04 uptake.

CONCLUSIONS

68Ga-FAPI-04 PET-CT could be used to distinguish between benign and malignant 18F-FDG-avid colorectal lesions.

Mesenchymal stem cells and cancer-associated fibroblasts as a therapeutic strategy for breast cancer

Breast cancer is the most common type of cancer and the leading cause of death among women. Recent evidence suggests that mesenchymal stromal/stem cells and cancer-associated fibroblasts (CAFs) have an essential role in cancer progression, invasion and therapy resistance. Therefore, they are considered as highly promising future therapeutic targets against breast cancer. The intrinsic tumour tropism and immunomodulatory capacities of mesenchymal stromal/stem cells are of special relevance for developing mesenchymal stromal/stem cells-based anti-tumour therapies that suppress primary tumour growth and metastasis. In addition, the utilization of therapies that target the stromal components of the tumour microenvironment in combination with standard drugs is an innovative tool that could improve patients' response to therapies and their survival. In this review, we discuss the currently available information regarding the possible use of mesenchymal stromal/stem cells-derived anti-tumour therapies, as well as the utilization of therapies that target CAFs in breast cancer microenvironment. Finally, these data can serve as a guide map for future research in this field, ultimately aiding the effective transition of these results into the clinic. LINKED ARTICLES: This article is part of a themed issue on Cancer Microenvironment and Pharmacological Interventions. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.2/issuetoc.

Detection of lymph node metastasis in colon cancer by ectopically expressed fibroblast markers FOXQ1 and THBS2

Introduction

Approximately 25% of colon cancer (CC) patients having curative surgery will relapse. Therefore, it is crucial to identify patients with increased recurrence risk to offer them adjuvant chemotherapy. Three markers with prominent expression in fibroblasts: forkhead box Q1 (FOXQ1), matrix metalloproteinase-11 (MMP11), and thrombospondin-2 (THBS2), and the fibroblast expressed chemokine CXCL12 were selected for studies because of the critical role of fibroblasts in the microenvironment of the tumor.

Methods

The expression levels of the biomarkers were assessed in primary CC tumors, lymph nodes of CC patients and controls, and CC cell lines at mRNA and protein levels by real-time qRT-PCR and immunohistochemistry, respectively.

Results

FOXQ1, MMP11, and THBS2 mRNAs were expressed at significantly higher levels in primary tumors compared to normal colon (P=0.002, P<0.0001, and P<0.0001, respectively). In contrast, CXCL12 mRNA levels were higher in normal colon tissue. FOXQ1, MMP11, and THBS2 levels were also expressed at significantly higher levels in metastasis-positive lymph nodes compared to both metastasis-negative- and control nodes (P<0.0001/P=0.002, P<0.0001/P<0.0001, and P<0.0001/P<0.0001, respectively). Immuno-morphometry revealed that 30-40% of the tumor cells expressed FOXQ1, MMP11, and THBS2. FOXQ1 and THBS2 were barely detected in normal colon epithelium (P<0.0001), while MMP11 was expressed in normal colon epithelium at high levels.

Discussion

We conclude that CC tumor cells show ectopic expression of FOXQ1 and THBS2 possibly making these tumor cells independent of fibroblast cell support. The high expression levels of these two biomarkers in metastatic lymph nodes suggest that they are potential indicators of patients at risk for recurrence.

Heterogeneous response to TGF-β1/3 isoforms in fibroblasts of different origins: implications for wound healing and tumorigenesis

Identification of therapeutic targets for treating fibrotic diseases and cancer remains challenging. Our study aimed to investigate the effects of TGF-β1 and TGF-β3 on myofibroblast differentiation and extracellular matrix deposition in different types of fibroblasts, including normal/dermal, cancer-associated, and scar-derived fibroblasts. When comparing the phenotype and signaling pathways activation we observed extreme heterogeneity of studied markers across different fibroblast populations, even within those isolated from the same tissue. Specifically, the presence of myofibroblast and deposition of extracellular matrix were dependent on the origin of the fibroblasts and the type of treatment they received (TGF-β1 vs. TGF-β3). In parallel, we detected activation of canonical signaling (pSMAD2/3) across all studied fibroblasts, albeit to various extents. Treatment with TGF-β1 and TGF-β3 resulted in the activation of canonical and several non-canonical pathways, including AKT, ERK, and ROCK. Among studied cells, cancer-associated fibroblasts displayed the most heterogenic response to TGF-β1/3 treatments. In general, TGF-β1 demonstrated a more potent activation of signaling pathways compared to TGF-β3, whereas TGF-β3 exhibited rather an inhibitory effect in keloid- and hypertrophic scar-derived fibroblasts suggesting its clinical potential for scar treatment. In summary, our study has implications for comprehending the role of TGF-β signaling in fibroblast biology, fibrotic diseases, and cancer. Future research should focus on unraveling the mechanisms beyond differential fibroblast responses to TGF-β isomers considering inherent fibroblast heterogeneity.

Helicobacter pylori-activated fibroblasts as a silent partner in gastric cancer development

The discovery of Helicobacter pylori (Hp) infection of gastric mucosa leading to active chronic gastritis, gastroduodenal ulcers, and MALT lymphoma laid the groundwork for understanding of the general relationship between chronic infection, inflammation, and cancer. Nevertheless, this sequence of events is still far from full understanding with new players and mediators being constantly identified. Originally, the Hp virulence factors affecting mainly gastric epithelium were proposed to contribute considerably to gastric inflammation, ulceration, and cancer. Furthermore, it has been shown that Hp possesses the ability to penetrate the mucus layer and directly interact with stroma components including fibroblasts and myofibroblasts. These cells, which are the source of biophysical and biochemical signals providing the proper balance between cell proliferation and differentiation within gastric epithelial stem cell compartment, when exposed to Hp, can convert into cancer-associated fibroblast (CAF) phenotype. The crosstalk between fibroblasts and myofibroblasts with gastric epithelial cells including stem/progenitor cell niche involves several pathways mediated by non-coding RNAs, Wnt, BMP, TGF-β, and Notch signaling ligands. The current review concentrates on the consequences of Hp-induced increase in gastric fibroblast and myofibroblast number, and their activation towards CAFs with the emphasis to the altered communication between mesenchymal and epithelial cell compartment, which may lead to inflammation, epithelial stem cell overproliferation, disturbed differentiation, and gradual gastric cancer development. Thus, Hp-activated fibroblasts may constitute the target for anti-cancer treatment and, importantly, for the pharmacotherapies diminishing their activation particularly at the early stages of Hp infection.

MDA-9/Syntenin in the tumor and microenvironment defines prostate cancer bone metastasis

Bone metastasis is a frequent and incurable consequence of advanced prostate cancer (PC). An interplay between disseminated tumor cells and heterogeneous bone resident cells in the metastatic niche initiates this process. Melanoma differentiation associated gene-9 (mda-9/Syntenin/syndecan binding protein) is a prometastatic gene expressed in multiple organs, including bone marrow-derived mesenchymal stromal cells (BM-MSCs), under both physiological and pathological conditions. We demonstrate that PDGF-AA secreted by tumor cells induces CXCL5 expression in BM-MSCs by suppressing MDA-9-dependent YAP/MST signaling. CXCL5-derived tumor cell proliferation and immune suppression are consequences of the MDA-9/CXCL5 signaling axis, promoting PC disease progression. mda-9 knockout tumor cells express less PDGF-AA and do not develop bone metastases. Our data document a previously undefined role of MDA-9/Syntenin in the tumor and microenvironment in regulating PC bone metastasis. This study provides a framework for translational strategies to ameliorate health complications and morbidity associated with advanced PC.

Exploration of s new biomarker in osteosarcoma and association with clinical outcomes: TOP2A+ cancer associated fibroblasts

BACKGROUND

Osteosarcoma (OS) is the leading malignant primary bone tumor in young adults and children and has a high mortality rate. Cancer-associated fibroblasts (CAFs) are major components of the tumor microenvironment, influencing cancer progression and metastasis. However, there is no systematic study on the role of CAF in OS.

METHODS

We collected six OS patients' single-cell RNA sequencing data from the TISCH database, which was processed using the Seurat package. We selected gene sets from the well-known MSigDB database and resorted to the clusterprofiler package for gene set enrichment analysis (GSEA). The least absolute shrinkage and selection operator (LASSO) regression model was used for identification of the variables. Receiver operating characteristic and decision curve analyses were utilized for determining the efficacy of the monogram model.

RESULTS

TOP2A+ CAFs was recognized as the carcinogenic CAFs subset, given its intense interaction with OS malignant cells and association with the critical cancer driver pathway. We intersected the differentially expressed genes of TOP2A+ CAFs with the prognostic genes selected from 88 OS samples. The acquired gene set was selected using the LASSO regression model and integrated with clinical factors to obtain a monogram model of high prognosis predicting power (area under the curve of 5 year survival at 0.883). Functional enrichment analysis revealed the detailed difference between two risk groups.

CONCLUSION

We identified TOP2A+ CAFs as a subset of oncogenic CAFs in OS. Based on differentially expressed genes derived from TOP2A+ CAFs, combined with bulk transcriptome prognostic genes, we constructed a risk model that can efficiently predict OS prognosis. Collectively, our study may provide new insights for future studies to elucidate the role of CAF in OS.

PD-L1-expressing cancer-associated fibroblasts induce tumor immunosuppression and contribute to poor clinical outcome in esophageal cancer

The programmed cell death 1 protein (PD-1)/programmed cell death ligand 1 (PD-L1) axis plays a crucial role in tumor immunosuppression, while the cancer-associated fibroblasts (CAFs) have various tumor-promoting functions. To determine the advantage of immunotherapy, the relationship between the cancer cells and the CAFs was evaluated in terms of the PD-1/PD-L1 axis. Overall, 140 cases of esophageal cancer underwent an immunohistochemical analysis of the PD-L1 expression and its association with the expression of the α smooth muscle actin, fibroblast activation protein, CD8, and forkhead box P3 (FoxP3) positive cells. The relationship between the cancer cells and the CAFs was evaluated in vitro, and the effect of the anti-PD-L1 antibody was evaluated using a syngeneic mouse model. A survival analysis showed that the PD-L1+ CAF group had worse survival than the PD-L1- group. In vitro and in vivo, direct interaction between the cancer cells and the CAFs showed a mutually upregulated PD-L1 expression. In vivo, the anti-PD-L1 antibody increased the number of dead CAFs and cancer cells, resulting in increased CD8+ T cells and decreased FoxP3+ regulatory T cells. We demonstrated that the PD-L1-expressing CAFs lead to poor outcomes in patients with esophageal cancer. The cancer cells and the CAFs mutually enhanced the PD-L1 expression and induced tumor immunosuppression. Therefore, the PD-L1-expressing CAFs may be good targets for cancer therapy, inhibiting tumor progression and improving host tumor immunity.

A Subset of Colon Cancer Cell Lines Displays a Cytokine Profile Linked to Angiogenesis, EMT and Invasion Which Is Modulated by the Culture Conditions In Vitro

Colorectal cancer (CRC) is one of the deadliest cancers worldwide. The dysregulation of secretory pathways is a crucial driver of CRC progression, since it modulates cell proliferation, angiogenesis and survival. This study explores the changes in the CRC cytokine profile depending on the culture conditions and the presence of fibroblasts and macrophages as cellular components of the tumor microenvironment in 2D and in 3D formed spheroids. Upon analysis of 45 different cytokines, chemokines and growth factors, 20 CRC cell lines were categorized into high and low secretors. In the high secretor group cytokines related to angiogenesis, EMT and invasion were significantly upregulated. LIF and HFG were identified as the best discriminator between both groups. Independent of this grouping, the addition of normal as well as cancer-associated fibroblasts had a similar impact on the cytokine profile by increasing the total amount of secreted cytokines in most of the investigated cell lines. In contrast, the differentiation and polarization of macrophages was modulated differently by normal vs. cancer-associated fibroblasts. In summary, we identified two groups of CRC cell lines that differ in their cytokine profile. The dependance of this profile was analyzed in detail-not only from the tumor cell line but as well from the culture condition in vitro. Key cytokines that discriminate the two groups were identified and their importance as promising biomarker candidates for CRC discussed.

Tissue Biology: In Search of a New Paradigm

Animal tissues are made up of multiple cell types that are increasingly well-characterized, yet our understanding of the core principles that govern tissue organization is still incomplete. This is in part because many observable tissue characteristics, such as cellular composition and spatial patterns, are emergent properties, and as such, they cannot be explained through the knowledge of individual cells alone. Here we propose a complex systems theory perspective to address this fundamental gap in our understanding of tissue biology. We introduce the concept of cell categories, which is based on cell relations rather than cell identity. Based on these notions we then discuss common principles of tissue modularity, introducing compositional, structural, and functional tissue modules. Cell diversity and cell relations provide a basis for a new perspective on the underlying principles of tissue organization in health and disease.

miRNAs as key modulators between normal cells and tumor microenvironment interactions

The tumor microenvironment (TME) is well-defined target for understanding tumor progression and various cell types. Major elements of the tumor microenvironment are the followings: endothelial cells, fibroblasts, signaling molecules, extracellular matrix, and infiltrating immune cells. MicroRNAs (miRNAs) are a group of small noncoding RNAs with major functions in the gene expression regulation at post-transcriptional level that have also appeared to exerts key functions in the cancer initiation/progression in diverse biological processes and the tumor microenvironment. This study summarized various roles of miRNAs in the complex interactions between the tumor and normal cells in their microenvironment.

Collagen code in tumor microenvironment: Functions, molecular mechanisms, and therapeutic implications

The tumor microenvironment (TME) is crucial in cancer progression, and the extracellular matrix (ECM) is an important TME component. Collagen is a major ECM component that contributes to tumor cell infiltration, expansion, and distant metastasis during cancer progression. Recent studies reported that collagen is deposited in the TME to form a collagen wall along which tumor cells can infiltrate and prevent drugs from working on the tumor cells. Collagen-tumor cell interaction is complex and requires the activation of multiple signaling pathways for biochemical and mechanical signaling interventions. In this review, we examine the effect of collagen deposition in the TME on tumor progression and discuss the interaction between collagen and tumor cells. This review aims to illustrate the functions and mechanisms of collagen in tumor progression in the TME and its role in tumor therapy. The findings indicated collagen in the TME appears to be a better target for cancer therapy.

Communicator Extraordinaire: Extracellular Vesicles in the Tumor Microenvironment Are Essential Local and Long-Distance Mediators of Cancer Metastasis

Human tumors are increasingly being described as a complex "ecosystem", that includes many different cell types, secreted growth factors, extracellular matrix (ECM) components, and microvessels, that altogether create the tumor microenvironment (TME). Within the TME, epithelial cancer cells control the function of surrounding stromal cells and the non-cellular ECM components in an intricate orchestra of signaling networks specifically designed for cancer cells to exploit surrounding cells for their own benefit. Tumor-derived extracellular vesicles (EVs) released into the tumor microenvironment are essential mediators in the reprogramming of surrounding stromal cells, which include cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), tumor-infiltrating lymphocytes (TILs), and tumor endothelial cells (TECs), which are responsible for the promotion of neo-angiogenesis, immune cell evasion, and invasion which are essential for cancer progression. Perhaps most importantly, tumor-derived EVs play critical roles in the metastatic dissemination of tumor cells through their two-fold role in initiating cancer cell invasion and the establishment of the pre-metastatic niche, both of which are vital for tumor cell migration, homing, and colonization at secondary tumor sites. This review discusses extracellular vesicle trafficking within the tumor microenvironment and pre-metastatic niche formation, focusing on the complex role that EVs play in orchestrating cancer-to-stromal cell communication in order to promote the metastatic dissemination of cancer cells.

Skin Cancer Microenvironment: What We Can Learn from Skin Aging?

Aging is a natural intrinsic process associated with the loss of fibrous tissue, a slower cell turnover, and a reduction in immune system competence. In the skin, the continuous exposition of environmental factors superimposes extrinsic damage, mainly due to ultraviolet radiation causing photoaging. Although not usually considered a pathogenic event, photoaging affects cutaneous biology, increasing the risk of skin carcinogenesis. At the cellular level, aging is typified by the rise of senescence cells a condition characterized by reduced or absent capacity to proliferate and aberrant hyper-secretory activity. Senescence has a double-edged sword in cancer biology given that senescence prevents the uncontrolled proliferation of damaged cells and favors their clearance by paracrine secretion. Nevertheless, the cumulative insults and the poor clearance of injured cells in the elderly increase cancer incidence. However, there are not conclusive data proving that aged skin represents a permissive milieu for tumor onset. On the other hand, tumor cells are capable of activating resident fibroblasts onto a pro-tumorigenic phenotype resembling those of senescent fibroblasts suggesting that aged fibroblasts might facilitate cancer progression. This review discusses changes that occur during aging that can prime neoplasm or increase the aggressiveness of melanoma and non-melanoma skin cancer.

Dissecting pulmonary fibroblasts heterogeneity in lung development, health and diseases

Lung fibroblasts are the major components in the connective tissue of the pulmonary interstitium and play essential roles in the developing of postnatal lung, synthesizing the extracellular matrix and maintaining the integrity of the lung architecture. Fibroblasts are activated in various disease conditions and exhibit functional heterogeneities according to their origin, spatial location, activated state and microenvironment. In recent years, advances in technology have enabled researchers to identify fibroblast subpopulations in both mouse and human. Here, we discuss pulmonary fibroblast heterogeneity, focusing on the developing, healthy and pathological lung conditions. We firstly review the expression profiles of fibroblasts during lung development, and then consider fibroblast diversity according to different anatomical sites of lung architecture. Subsequently, we discuss fibroblast heterogeneity in genetic lineage. Finally, we focus on how fibroblast heterogeneity may shed light on different pathological lung conditions such as fibrotic diseases, infectious diseases including COVID-19, and lung cancers. We emphasize the importance of comparative studies to illuminate the overlapping characteristics, expression profiles and signaling pathways of the fibroblast subpopulations across disease conditions, a better characterization of the functional complexity rather than the expression of a particular gene may have important therapeutic applications.

Biological differences between normal and cancer-associated fibroblasts in breast cancer

Background

Cancer-associated fibroblasts (CAFs) constitute the primary constituents of the tumor microenvironment (TME) and exert significant influences on cancer progression. However, adequate comprehension of CAF profiles in breast cancer, as well as the precise mechanisms underlying their promotion of cancer, remains lacking.

Objectives

To discerns the biological differences between normal fibroblasts (NFs) and CAFs in breast cancer and explore the underlying mechanism.

Methods

Three pairs of CAFs and NFs were isolated from breast cancer patients of diverse subtypes who had not undergone prior radiotherapy or chemotherapy. Morphological characteristics of CAFs and NFs were assessed through optical and electron microscopy, their biological attributes were examined using cell counting kits and transwell assays, and their impact on breast cancer cells was simulated using a coculture system. Furthermore, the miRNA profiles of CAFs and NFs were sequenced via an Illumina HiSeq 2500 platform.

Results

CAFs exhibited higher growth rate and motility than NFs and a stronger potential to promote the malignancy of breast cancer cells. RNA sequencing of both NFs and CAFs revealed differentially expressed miRNAs with notable variability among distinct patients within their NFs and CAFs, while the enrichment of the target genes of differentially expressed miRNAs within both GO terms and KEGG pathways demonstrated significant similarity across patients with different profiles.

Conclusion

CAFs have greater malignancy and higher potential to influence the growth, migration, invasion and chemoresistance of cocultured breast cancer cells than NFs. In addition, the miRNAs that are differentially expressed in CAFs when compared to NFs display substantial variability across patients with distinct breast cancer subtypes, while the enrichment of target genes regulated by these miRNAs, within GO terms and KEGG pathways, remains remarkably consistent among patients with varying profiles.

Cancer-on-chip: a 3D model for the study of the tumor microenvironment

The approval of anticancer therapeutic strategies is still slowed down by the lack of models able to faithfully reproduce in vivo cancer physiology. On one hand, the conventional in vitro models fail to recapitulate the organ and tissue structures, the fluid flows, and the mechanical stimuli characterizing the human body compartments. On the other hand, in vivo animal models cannot reproduce the typical human tumor microenvironment, essential to study cancer behavior and progression. This study reviews the cancer-on-chips as one of the most promising tools to model and investigate the tumor microenvironment and metastasis. We also described how cancer-on-chip devices have been developed and implemented to study the most common primary cancers and their metastatic sites. Pros and cons of this technology are then discussed highlighting the future challenges to close the gap between the pre-clinical and clinical studies and accelerate the approval of new anticancer therapies in humans.

Targeting Melanoma-Associated Fibroblasts (MAFs) with Activated γδ (Vδ2) T Cells: An In Vitro Cytotoxicity Model

The tumor microenvironment (TME) has gained considerable scientific attention by playing a role in immunosuppression and tumorigenesis. Besides tumor cells, TME is composed of various other cell types, including cancer-associated fibroblasts (CAFs or MAFs when referring to melanoma-derived CAFs) and tumor-infiltrating lymphocytes (TILs), a subpopulation of which is labeled as γδ T cells. Since the current anti-cancer therapies using γδ T cells in various cancers have exhibited mixed treatment responses, to better understand the γδ T cell biology in melanoma, our research group aimed to investigate whether activated γδ T cells are capable of killing MAFs. To answer this question, we set up an in vitro platform using freshly isolated Vδ2-type γδ T cells and cultured MAFs that were biobanked from our melanoma patients. This study proved that the addition of zoledronic acid (1-2.5 µM) to the γδ T cells was necessary to drive MAFs into apoptosis. The MAF cytotoxicity of γδ T cells was further enhanced by using the stimulatory clone 20.1 of anti-BTN3A1 antibody but was reduced when anti-TCR γδ or anti-BTN2A1 antibodies were used. Since the administration of zoledronic acid is safe and tolerable in humans, our results provide further data for future clinical studies on the treatment of melanoma.

Autophagy and autophagy-related pathways in cancer

Maintenance of protein homeostasis and organelle integrity and function is critical for cellular homeostasis and cell viability. Autophagy is the principal mechanism that mediates the delivery of various cellular cargoes to lysosomes for degradation and recycling. A myriad of studies demonstrate important protective roles for autophagy against disease. However, in cancer, seemingly opposing roles of autophagy are observed in the prevention of early tumour development versus the maintenance and metabolic adaptation of established and metastasizing tumours. Recent studies have addressed not only the tumour cell intrinsic functions of autophagy, but also the roles of autophagy in the tumour microenvironment and associated immune cells. In addition, various autophagy-related pathways have been described, which are distinct from classical autophagy, that utilize parts of the autophagic machinery and can potentially contribute to malignant disease. Growing evidence on how autophagy and related processes affect cancer development and progression has helped guide efforts to design anticancer treatments based on inhibition or promotion of autophagy. In this Review, we discuss and dissect these different functions of autophagy and autophagy-related processes during tumour development, maintenance and progression. We outline recent findings regarding the role of these processes in both the tumour cells and the tumour microenvironment and describe advances in therapy aimed at autophagy processes in cancer.

Identification of fibroblast-related genes based on single-cell and machine learning to predict the prognosis and endocrine metabolism of pancreatic cancer

Background

Single-cell sequencing technology has become an indispensable tool in tumor mechanism and heterogeneity studies. Pancreatic adenocarcinoma (PAAD) lacks early specific symptoms, and comprehensive bioinformatics analysis for PAAD contributes to the developmental mechanisms.

Methods

We performed dimensionality reduction analysis on the single-cell sequencing data GSE165399 of PAAD to obtain the specific cell clusters. We then obtained cell cluster-associated gene modules by weighted co-expression network analysis and identified tumorigenesis-associated cell clusters and gene modules in PAAD by trajectory analysis. Tumor-associated genes of PAAD were intersected with cell cluster marker genes and within the signature module to obtain genes associated with PAAD occurrence to construct a prognostic risk assessment tool by the COX model. The performance of the model was assessed by the Kaplan-Meier (K-M) curve and the receiver operating characteristic (ROC) curve. The score of endocrine pathways was assessed by ssGSEA analysis.

Results

The PAAD single-cell dataset GSE165399 was filtered and downscaled, and finally, 17 cell subgroups were filtered and 17 cell clusters were labeled. WGCNA analysis revealed that the brown module was most associated with tumorigenesis. Among them, the brown module was significantly associated with C11 and C14 cell clusters. C11 and C14 cell clusters belonged to fibroblast and circulating fetal cells, respectively, and trajectory analysis showed low heterogeneity for fibroblast and extremely high heterogeneity for circulating fetal cells. Next, through differential analysis, we found that genes within the C11 cluster were highly associated with tumorigenesis. Finally, we constructed the RiskScore system, and K-M curves and ROC curves revealed that RiskScore possessed objective clinical prognostic potential and demonstrated consistent robustness in multiple datasets. The low-risk group presented a higher endocrine metabolism and lower immune infiltrate state.

Conclusion

We identified prognostic models consisting of APOL1, BHLHE40, CLMP, GNG12, LOX, LY6E, MYL12B, RND3, SOX4, and RiskScore showed promising clinical value. RiskScore possibly carries a credible clinical prognostic potential for PAAD.

Aspirin Affects MDA-MB-231 Vesicle Production and Their Capacity to Induce Fibroblasts towards a Pro-Invasive State

Long-term administration of aspirin (ASA, acetylsalicylic acid) in oncogenic patients has been related to a reduction in cancer risk incidence, but its precise mechanism of action is unclear. The activation of cancer-associated fibroblasts (CAFs) is a key element in tumor progression and can be triggered by cancer-derived extracellular vesicles (EVs). Targeting the communication between cancer cells and the surrounding tumor microenvironment (TME) may control cancer progression. Our aim was to investigate the effect of ASA on breast cancer cells, focusing on EV secretion and their effect on the biological properties of CAFs. As a result, ASA was shown to reduce the amount and alter the size distribution of EVs produced by MDA-MB-231 tumor cells. Fibroblasts stimulated with EVs derived from MDA-MB-231 treated with ASA (EV-ASA) showed a lower expression of alpha-smooth muscle actin (α-SMA), matrix metalloproteinase-2 (MMP2) but not fibroblast activation protein (FAP) in respect to the ones stimulated with EVs from untreated breast cancer cells (EV-CTR). Furthermore, invasion assays using a three-dimensional (3D) fibroblast spheroid model showed reduced MDA-MB-231 invasion towards fibroblast spheroids pretreated with EV-ASA as compared to spheroids prepared with EV-CTR-stimulated fibroblasts. This suggests that ASA partially inhibits the ability of tumor EVs to stimulate CAFs to promote cancer invasion. In conclusion, ASA can interfere with tumor communication by reducing EV secretion by breast tumor cells as well as by interfering with their capacity to stimulate fibroblasts to become CAFs.

Prognostic analysis of lung adenocarcinoma based on cancer-associated fibroblasts genes using scRNA-sequencing

Cancer-associated fibroblasts (CAFs) are an important component of the tumor microenvironment (TME). CAFs can promote tumor occurrence and metastasis by promoting cancer cell proliferation, angiogenesis, extracellular matrix (ECM) remodeling, and drug resistance. Nevertheless, how CAFs are related to Lung adenocarcinoma (LUAD) has not yet been revealed, especially since the CAFs-related prediction model has yet to be established. We combined Single-cell RNA-sequencing (scRNA-seq) and Bulk-RNA data to develop a predictive model of 8 CAFs-associated genes. Our model predicted LUAD prognosis and immunotherapy efficacy. TME, mutation landscape and drug sensitivity differences were also systematically analyzed between the LUAD patients of high- and low-risk. Moreover, the model prognostic performance was validated in four independent validation cohorts in the Gene expression omnibus (GEO) and the IMvigor210 immunotherapy cohort.

The role of cancer-associated fibroblasts in breast cancer metastasis

Breast cancer deaths are primarily caused by metastasis. There are several treatment options that can be used to treat breast cancer. There are, however, a limited number of treatments that can either prevent or inhibit the spread of breast tumor metastases. Thus, novel therapeutic strategies are needed. Studies have increasingly focused on the importance of the tumor microenvironment (TME) in metastasis of breast cancer. As the most abundant cells in the TME, cancer-associated fibroblasts (CAFs) play important roles in cancer pathogenesis. They can remodel the structure of the extracellular matrix (ECM) and engage in crosstalk with cancer cells or other stroma cells by secreting growth factors, cytokines, and chemokines, as well as components of the ECM, which assist the tumor cells to invade through the TME and cause distant metastasis. Clinically, CAFs not only foster the initiation, growth, angiogenesis, invasion, and metastasis of breast cancer but also serve as biomarkers for diagnosis, therapy, and prediction of prognosis. In this review, we summarize the biological characteristics and subtypes of CAFs and their functions in breast cancer metastasis, focusing on their important roles in the diagnosis, prognosis, and treatment of breast cancer. Recent studies suggest that CAFs are vital partners of breast cancer cells that assist metastasis and may represent ideal targets for prevention and treatment of breast cancer metastasis.

B7-H3-targeted CAR T cell activity is enhanced by radiotherapy in solid cancers

Adoptive cell therapy utilizing T cells genetically modified to express a chimeric antigen receptor (CAR) has demonstrated promising clinical results in hematological malignancies. However, solid cancers have not seen a similar success due to multiple obstacles. Investigating these escape mechanisms and designing strategies to counteract such limitations is crucial and timely. Growing evidence in the literature supports the hypothesis that radiotherapy has the potential to enhance the susceptibility of solid tumors to CAR T cell therapy, by overcoming mechanisms of resistance. Radiation treatment can increase the susceptibility of different types of solid cancers (TNBC, HNSCC, PDAC) to B7-H3 CAR T cell-mediated eradication. Multiple mechanisms, including reduced cancer cell proliferation, upregulation of the targeted antigen, modulation of apoptotic molecules may contribute to this signal. The information in the literature and the results we describesupport the ability of radiotherapy to improve the efficacy of CAR T cell therapy in solid tumors.

Chemotherapy-induced PDL-1 expression in cancer-associated fibroblasts promotes chemoresistance in NSCLC

OBJECTIVES

A cure for cancer is out of reach for most patients due to chemoresistance. Cancer-associated fibroblasts (CAFs) play a vital role in cancer chemoresistance, but detailed understanding of the process particularly in chemoresistant lung cancer is lacking. In this study, we investigated programmed death-ligand 1 (PDL-1) as a potential biomarker for CAF-induced chemoresistance and evaluated its role and the underlying mechanisms of chemoresistance in non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

A systemic search of gene expression profiles of multiple tissues in NSCLC was carried out to determine the expression intensities of traditional fibroblast biomarkers and CAF-secreted protumorigenic cytokines. PDL-1 expression in CAFs was analyzed by ELISA, Western blotting, and flow cytometry. Human cytokine array was used to identify specific cytokines secreted from CAFs. Role of PDL-1 in NSCLC chemoresistance was assessed using CRISPR/Cas9 knockdown and various functional assays including MTT, cell invasion, sphere formation, and cell apoptosis. In vivo experiments were conducted using a co-implantation xenograft mouse model with live cell imaging and immunohistochemistry.

RESULTS

We demonstrated that chemotherapy-stimulated CAFs promoted tumorigenic and stem cell-like properties of NSCLC cells, which contribute to their chemoresistance. Subsequently, we revealed that PDL-1 expression is upregulated in chemotherapy-treated CAFs and is associated with poor prognosis. Silencing PDL-1 expression suppressed CAFs' ability to promote stem cell-like properties and invasiveness of lung cancer cells, favoring chemoresistance. Mechanistically, an upregulation of PDL-1 in chemotherapy-treated CAFs led to an increase in hepatocyte growth factor (HGF) secretion, which stimulates cancer progression, cell invasion, and stemness of lung cancer cells, while inhibiting apoptosis.

CONCLUSION

Our results show that PDL-1-positive CAFs modulate stem cell-like properties of NSCLC cells by secreting elevated HGF, thereby promoting chemoresistance. Our finding supports PDL-1 in CAFs as a chemotherapy response biomarker and as a drug delivery and therapeutic target for chemoresistant NSCLC.

Measuring cell deformation by microfluidics

Microfluidics is an increasingly popular method for studying cell deformation, with various applications in fields such as cell biology, biophysics, and medical research. Characterizing cell deformation offers insights into fundamental cell processes, such as migration, division, and signaling. This review summarizes recent advances in microfluidic techniques for measuring cellular deformation, including the different types of microfluidic devices and methods used to induce cell deformation. Recent applications of microfluidics-based approaches for studying cell deformation are highlighted. Compared to traditional methods, microfluidic chips can control the direction and velocity of cell flow by establishing microfluidic channels and microcolumn arrays, enabling the measurement of cell shape changes. Overall, microfluidics-based approaches provide a powerful platform for studying cell deformation. It is expected that future developments will lead to more intelligent and diverse microfluidic chips, further promoting the application of microfluidics-based methods in biomedical research, providing more effective tools for disease diagnosis, drug screening, and treatment.

Development and validation of cancer-associated fibroblasts-related gene landscape in prognosis and immune microenvironment of bladder cancer

Backgrounds

Bladder cancer (BLCA) is one of the most prevalent cancers of the genitourinary system, the clinical outcomes of patients with BLCA are bad, and the morbidity rate is high. One of the key components of the tumor microenvironment (TME) is cancer-associated fibroblasts (CAFs) which are critically involved in BLCA tumorigenesis. Previous studies have shown the involvement of CAFs in tumor growth, cancer progression, immune evasion, angiogenesis, and chemoresistance in several cancers such as breast, colon, pancreatic, ovarian, and prostate cancers. However, only a few studies have shown the role of CAFs in the occurrence and development of BLCA.

Methods

We have retrieved and merged the data on RNA-sequencing of patients with BLCA from databases including "the Cancer Genome Atlas" and "Gene Expression Omnibus." Next, we compared the differences in CAFs-related genes (CRGs) expression between normal and BLCA tissues. Based on CRGs expression, we randomly divided patients into two groups. Next, we determined the correlation between CAFs subtypes and differentially expressed CRGs (DECRGs) between the two subtypes. Furthermore, the "Gene Ontology" and "Kyoto Encyclopedia of Genes and Genomes pathway" enrichment analyses were conducted to determine the functional characteristics between the DECRGs and clinicopathology.

Results

We identified five genes (POF1B, ARMCX1, ALDOC, C19orf33, and KRT13) using multivariate COX regression and "Least Absolute Shrinkage and Selection Operator (LASSO) COX regression analysis" for developing a prognostic model and calculating the CRGs-risk score. The TME, mutation, CSC index, and drug sensitivity were also analyzed.

Conclusion

We constructed a novel five- CRGs prognostic model, which sheds light on the roles of CAFs in BLCA.