Fibroblasts as architects of cancer pathogenesis

The role of FERMT2 in the tumor microenvironment and immunotherapy in pan-cancer using comprehensive single-cell and bulk sequencing

FERMT2 has been identified as a participant in integrin-linked kinase signaling pathways, influencing epithelial-mesenchymal transition and thereby affecting tumor initiation, progression, and invasion. While the character of FERMT2 in the tumor microenvironment (TME) as well as its implications for immunotherapy remain unclear. Thus, we conducted a comprehensive analysis to assess the prognostic significance of FERMT2 using Kaplan-Meier analysis. In addition, we employed enrichment analysis to uncover potential underlying molecular mechanisms. Using "Immunedeconv" package, we evaluated the immune characteristics of FERMT2 within TME. Furthermore, we determined the expression levels of FERMT2 in various cell types within TME, based on single-cell sequencing data. To confirm the co-expression of FERMT2 and markers of cancer-associated fibroblasts (CAFs), we performed multiplex immunofluorescence staining on tissue paraffin sections across various cancer types. Our analysis disclosed a significant correlation between elevated FERMT2 expression and unfavorable prognosis in specific cancer types. Furthermore, we identified a strong correlation between FERMT2 expression and diverse immune-related factors, including immune checkpoint molecules, immune cell infiltration, microsatellite instability (MSI), and tumor mutational burden (TMB). Additionally, there was a significant correlation between FERMT2 expression and immune-related pathways, particularly those associated with activating, migrating, and promoting the growth of fibroblasts in diverse cancer types. Interestingly, we observed consistent co-expression of FERMT2 in both malignant tumor cells and stromal cells, particularly within CAFs. Notably, our findings also indicated that FERMT2, in particular, exhibited elevated expression levels within tumor tissues and co-expressed with α-SMA in CAFs based on the multiplex immunofluorescence staining results.

Cancer-associated fibroblasts produce matrix-bound vesicles that influence endothelial cell function

Intercellular communication between different cell types in solid tumors contributes to tumor growth and metastatic dissemination. The secretome of cancer-associated fibroblasts (CAFs) plays major roles in these processes. Using human mammary CAFs, we showed that CAFs with a myofibroblast phenotype released extracellular vesicles that transferred proteins to endothelial cells (ECs) that affected their interaction with immune cells. Mass spectrometry-based proteomics identified proteins transferred from CAFs to ECs, which included plasma membrane receptors. Using THY1 as an example of a transferred plasma membrane-bound protein, we showed that CAF-derived proteins increased the adhesion of a monocyte cell line to ECs. CAFs produced high amounts of matrix-bound EVs, which were the primary vehicles of protein transfer. Hence, our work paves the way for future studies that investigate how CAF-derived matrix-bound EVs influence tumor pathology by regulating the function of neighboring cancer, stromal, and immune cells.

MMP-11 expression in early luminal breast cancer: associations with clinical, MRI, pathological characteristics, and disease-free survival

BACKGROUND

Early hormone-positive breast cancers typically have favorable outcomes, yet long-term surveillance is crucial due to the risk of late recurrences. While many studies associate MMP-11 expression with poor prognosis in breast cancer, few focus on early-stage cases. This study explores MMP-11 as an early prognostic marker in hormone-positive breast cancers.

METHODS

In this retrospective study, 228 women with early hormone-positive invasive ductal carcinoma, treated surgically between 2011 and 2016, were included. MMP-11 expression was measured by immunohistochemistry, and its association with clinical and MRI data was analyzed.

RESULTS

Among the patients (aged 31-89, median 60, with average tumor size of 15.7 mm), MMP-11 staining was observed in half of the cases. This positivity correlated with higher uPA levels and tumor grade but not with nodal status or size. Furthermore, MMP-11 positivity showed specific associations with MRI features. Over a follow-up period of 6.5 years, only 12 oncological events occurred. Disease-free survival was linked to Ki67 and MMP-11.

CONCLUSION

MMP-11, primarily present in tumor-surrounding stromal cells, correlates with tumor grade and uPA levels. MMP-11 immunohistochemical score demonstrates a suggestive trend in association with disease-free survival, independent of Ki67 and other traditional prognostic factors. This highlights the potential of MMP-11 as a valuable marker in managing early hormone-positive breast cancer.

Modulating the acetylation of α-tubulin by LncRNAs and microRNAs helps in the progression of cancer

Malignant tumor cells go through morphological and gene expression alterations, including rearrangement of cytoskeleton proteins that promote invasion and metastasis. Microtubules form a major cytoskeleton component that plays a significant role in regulating multiple cellular activities and function depending on the presence of posttranslational modification (PTM). Acetylation is a type of PTM that generally occurs in the lysine 40 region of α-tubulin and is known to be critically associated with cancer metastasis. Current evidence demonstrates that noncoding RNAs, such as long noncoding RNA (lncRNA) and microRNA (or miRNA), which are correlated with gene regulation modulate the expression of acetylated tubulin in the development and metastasis of cancer. This review provides an overview about the role of lncRNA and miRNA in regulation of tubulin acetylation in various types of cancer.

IL-8 activates fibroblasts to promote the invasion of HNSCC cells via STAT3-MMP1

Matrix metalloproteinase-1 (MMP1) has an aberrant expression relevant to various behaviors of cancers. As dominant components of the tumor stroma, fibroblasts constitute an important source of Matrix metalloproteinase (MMPs) including mainly MMP1. The impacts of MMP1 derived from fibroblasts in tumor microenvironment, however, is not well defined. In this study, we demonstrated a part of crosstalk between fibroblasts and cancer cells that enhanced the invasiveness of cancer cells, IL8-induced activation of STAT3 signaling pathway as a key promoter to elevated MMP1 level in fibroblasts that supports the migration and invasion of head and neck squamous cell carcinoma (HNSCC) cells by extracellular matrix degradation. Importantly, once exposed to the inhibitor of STAT3 phosphorylation (TPCA-1), the enhanced induction of HNSCC cells invasion triggered by fibroblasts was significantly impaired.

Mimicking 3D breast tumor-stromal interactions to screen novel cancer therapeutics

Most of the 3D breast tumor models used in drug screening studies only comprise tumor cells, keeping out other essential cell players of the tumor microenvironment. Tumor-associated macrophages and fibroblasts are frequently correlated with tumor progression and therapy resistance, and targeting these cells at the tumor site has been appointed as a promising therapeutic strategy. However, the translation of new therapies to the clinic has been hampered by the absence of cellular models that more closely mimic the features of in vivo breast tumor microenvironment. Therefore, the development of innovative 3D models able to provide consistent and predictive responses about the in vivo efficacy of novel therapeutics is still an unmet preclinical need. Herein, we have established an in vitro 3D heterotypic spheroid model including MCF-7 breast tumor cells, human mammary fibroblasts and human macrophages. To establish this model, different cell densities have been combined and characterized through the evaluation of the spheroid size and metabolic activity, as well as histological and immunohistochemistry analysis of the 3D multicellular structures. The final optimized 3D model consisted in a multicellular spheroid seeded at the initial density of 5000 cells and cell ratio of 1:2:1 (MCF-7:monocytes:fibroblasts). Our model recapitulates several features of the breast tumor microenvironment, including the formation of a necrotic core, spatial organization, and extracellular matrix production. Further, it was validated as a platform for drug screening studies, using paclitaxel, a currently approved drug for breast cancer treatment, and Gefitinib, a chemotherapeutic approved for lung cancer and in preclinical evaluation for breast cancer. Generally, the impact on the cell viability of the 3D model was less evident than in 2D model, reinforcing the relevance of such complex 3D models in addressing novel treatment approaches. Overall, the use of a 3D heterotypic spheroid of breast cancer could be a valuable tool to predict the therapeutic effect of new treatments for breast cancer patients, by recapitulating key features of the breast cancer microenvironment.

Colitis-associated carcinogenesis: crosstalk between tumors, immune cells and gut microbiota

Colorectal cancer (CRC) is the third most common cancer worldwide. One of the main causes of colorectal cancer is inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD). Intestinal epithelial cells (IECs), intestinal mesenchymal cells (IMCs), immune cells, and gut microbiota construct the main body of the colon and maintain colon homeostasis. In the development of colitis and colitis-associated carcinogenesis, the damage, disorder or excessive recruitment of different cells such as IECs, IMCs, immune cells and intestinal microbiota play different roles during these processes. This review aims to discuss the various roles of different cells and the crosstalk of these cells in transforming intestinal inflammation to cancer, which provides new therapeutic methods for chemotherapy, targeted therapy, immunotherapy and microbial therapy.

An injectable supramolecular hydrogel as a self-drug-delivery system for local chemoimmunotherapy against melanoma

Skin-cancer melanoma caused 57k death in 2020. Some of the available therapies are: topical application of a gel loaded with an anti-skin cancer drug and intravenous injection of immune cytokines; however, both the approaches have drawbacks such as inefficient internalization of the drug in cancer cells and a short half-life with severe side effects, respectively. Interestingly, we observed for the first time that a subcutaneously implanted hydrogel designed and synthesized by coordinating NSAIDs and 5-AP with Zn(II) can effectively combat melanoma cell (B16-F10)-induced tumors in C57BL/6 mice. Both in vitro and in vivo results show that it can effectively reduce PGE2 expression, consequently upregulating IFN-γ and IL-12 that eventually engage M1-macrophages for activating T cells (CD8+), triggering apoptosis. This unique all-in-one self-drug-delivery approach, wherein the hydrogel implant is made from the drug molecules itself providing both chemotherapy and immunotherapy in combating deadly melanoma, highlights the supramolecular chemistry-based bottom-up approach in cancer therapy.

Fluorescence microscopy imaging of mitochondrial metabolism in cancer cells

Mitochondrial metabolism is an important contributor to cancer cell survival and proliferation that coexists with enhanced glycolytic activity. Measuring mitochondrial activity is useful to characterize cancer metabolism patterns, to identify metabolic vulnerabilities and to identify new drug targets. Optical imaging, especially fluorescent microscopy, is one of the most valuable tools for studying mitochondrial bioenergetics because it provides semiquantitative and quantitative readouts as well as spatiotemporal resolution of mitochondrial metabolism. This review aims to acquaint the reader with microscopy imaging techniques currently used to determine mitochondrial membrane potential (ΔΨm), nicotinamide adenine dinucleotide (NADH), ATP and reactive oxygen species (ROS) that are major readouts of mitochondrial metabolism. We describe features, advantages, and limitations of the most used fluorescence imaging modalities: widefield, confocal and multiphoton microscopy, and fluorescent lifetime imaging (FLIM). We also discus relevant aspects of image processing. We briefly describe the role and production of NADH, NADHP, flavins and various ROS including superoxide and hydrogen peroxide and discuss how these parameters can be analyzed by fluorescent microscopy. We also explain the importance, value, and limitations of label-free autofluorescence imaging of NAD(P)H and FAD. Practical hints for the use of fluorescent probes and newly developed sensors for imaging ΔΨm, ATP and ROS are described. Overall, we provide updated information about the use of microscopy to study cancer metabolism that will be of interest to all investigators regardless of their level of expertise in the field.

Cracking the code: Deciphering the role of the tumor microenvironment in osteosarcoma metastasis

Osteosarcoma (OS) is the most common malignant bone tumor in children and adolescents. It is characterized by a rapid progression, poor prognosis, and early pulmonary metastasis. Over the past 30 years, approximately 85% of patients with osteosarcoma have experienced metastasis. The five-year survival of patients with lung metastasis during the early stages of treatment is less than 20%. The tumor microenvironment (TME) not only provides conditions for tumor cell growth but also releases a variety of substances that can promote the metastasis of tumor cells to other tissues and organs. Currently, there is limited research on the role of the TME in osteosarcoma metastasis. Therefore, to explore methods for regulating osteosarcoma metastasis, further investigations must be conducted from the perspective of the TME. This will help to identify new potential biomarkers for predicting osteosarcoma metastasis and assist in the discovery of new drugs that target regulatory mechanisms for clinical diagnosis and treatment. This paper reviews the research progress on the mechanism of osteosarcoma metastasis based on TME theory, which will provide guidance for the clinical treatment of osteosarcoma.

Cancer-associated fibroblasts in the invasive tumour front promote the metastasis of oral squamous cell carcinoma through MFAP5 upregulation

Cancer-associated fibroblasts (CAFs) are widely involved in the development and progression of tumours. As a direct junction between tumour and normal host tissue, the tumour invasive front can remodel host tissue to generate a microenvironment more suitable for tumour invasion. However, whether CAFs derived from the invasive front (CAFs-F) have a greater ability to promote tumour invasion than CAFs derived from the superficial tumour (CAFs-S) is unclear. In this study, we characterized primary CAFs from different spatial locations of tumours. We demonstrated that CAFs-F had an increased ability to promote oral squamous cell carcinoma (OSCC) proliferation and invasion in vitro and significantly enhanced tumour growth in vivo compared to CAFs-S. Mechanistically, transcriptome profiling analysis revealed that the expression of MFAP5, encoding microfibril associated protein 5, was dramatically increased in CAFs-F compared to CAFs-S, which further confirmed that the MFAP5 protein level was elevated in head and neck squamous cell carcinoma (HNSCC) and that this increase was correlated with poor survival. Genetic ablation of MFAP5 impaired the preinvasive capabilities of CAFs-F. Together, our findings demonstrated that CAFs-F had a greater ability to promote tumour invasion than CAFs-S and that MFAP5 might be involved in this process.

Fibroblasts in cancer: Unity in heterogeneity

Tumor cells do not exist in isolation in vivo, and carcinogenesis depends on the surrounding tumor microenvironment (TME), composed of a myriad of cell types and biophysical and biochemical components. Fibroblasts are integral in maintaining tissue homeostasis. However, even before a tumor develops, pro-tumorigenic fibroblasts in close proximity can provide the fertile 'soil' to the cancer 'seed' and are known as cancer-associated fibroblasts (CAFs). In response to intrinsic and extrinsic stressors, CAFs reorganize the TME enabling metastasis, therapeutic resistance, dormancy and reactivation by secreting cellular and acellular factors. In this review, we summarize the recent discoveries on CAF-mediated cancer progression with a particular focus on fibroblast heterogeneity and plasticity.

A novel molecular imaging probe [99mTc]Tc-HYNIC-FAPI targeting cancer-associated fibroblasts

Fibroblast activation protein (FAP) is higher expressed on cancer-associated fibroblasts (CAFs) in most malignant epithelial neoplasms, which is lower expressed in normal tissues. As a promising small molecular probe, FAP inhibitor (FAPI) shows the specific binding to FAP. This study aimed to explore a novel molecular probe [^99mTc]Tc-HYNIC-FAPI targeting CAFs. The in vitro characteristics of the probe were also evaluated. The FAPI targeting FAP was designed, synthesized and conjugated with the chelator 6-hydrazinylnicotinic acid (HYNIC) for radiolabeling with ^99mTc. The radiolabeling yield, radiochemical purity and stability were evaluated by Instant thin-layer chromatography (ITLC) and High performance liquid chromatography (HPLC). Lipophilicity was performed by the distribution coefficient test. The binding and migration ability of the probe was assessed using the FAP transfected tumor cell line. The radiolabeling yield of [^99mTc]Tc-HYNIC-FAPI was (97.29 ± 0.46) %. The radiochemical purity was more than 90% and kept stable until 6 h. The radioligand was shown as lower lipophilicity, of which logD7.4 value was - 2.38 [Formula: see text] 0.13. In vitro experiments, the results indicated that the probe showed binding properties, and inhibited the migration of tumor cells. The novel [^99mTc]Tc-HYNIC-FAPI probe was successfully radiosynthesized and exhibited good radiochemical purity, stability and in vitro binding ability to tumor cells. The [^99mTc]Tc-HYNIC-FAPI will be a promising SPECT/CT imaging probe.

Ferroptosis in life: To be or not to be

Ferroptosis is a novel type of programmed cell death, characterized by a dysregulated iron metabolism and accumulation of lipid peroxides. It features the alteration of mitochondria and aberrant accumulation of excessive iron as well as loss of the cysteine-glutathione-GPX4 axis. Eventually, the accumulated lipid peroxides result in lethal damage to the cells. Ferroptosis is induced by the overloading of iron and the accumulation of ROS and can be inhibited by the activation of the GPX4 pathway, FS1-CoQ10 pathway, GCH1-BH4 pathway, and the DHODH pathway, it is also regulated by the oncogenes and tumor suppressors. Ferroptosis involves various physiological and pathological processes, and increasing evidence indicates that ferroptosis play a critical role in cancers and other diseases. It inhibits the proliferation of malignant cells in various types of cancers and inducing ferroptosis may become a new method of cancer treatment. Many inhibitors targeting the key factors of ferroptosis such as SLC7A11, GPX4, and iron overload have been developed. The application of ferroptosis is mainly divided into two directions, i.e. to avoid ferroptosis in healthy cells and selectively induce ferroptosis in cancers. In this review, we provide a critical analysis of the concept, and regulation pathways of ferroptosis and explored its roles in various diseases, we also summarized the compounds targeting ferroptosis, aiming to promote the speed of clinical use of ferroptosis induction in cancer treatment.

Different Expression and Clinical Implications of Cancer-Associated Fibroblast (CAF) Markers in Brain Metastases

Aims: This study assessed the expression and clinical relevance of cancer-asssociated fibroblast (CAF)-related biomarkers in brain metastasis (BM). Moreover, molecular characterization of patient-derived primary CAFs and normal fibroblasts (NFs) was performed. Methods: Sixty-eight patients with BM from various primary cancer types were selected. Immunohistochemistry (IHC) and immunofluorescence (IF) staining were performed to evaluate the expression of various CAF-related biomarkers. CAFs and NFs were isolated from fresh tissues. Results: Various CAF-related biomarkers were expressed in CAFs in BMs of different primary cancers. However, only PDGFR-β, α-SMA, and collagen type I were associated with BM size. PDGFR-β and α-SMA were associated with BM recurrence after resection. PDGFR-β was associated with recurrence-free survival (RFS). Interestingly, high expression of PDGFR-β and α-SMA was found in the patients with previous chemotherapy or radiotherapy for primary cancer. In primary cell culture, PDGFR-β and α-SMA were expressed at higher levels in patient-derived CAFs than in NFs or cancer cells. The origins of CAF in BM were presumed to be pericytes of blood vessels, circulating endothelial progenitor cells, or transformed astrocytes of the peritumoral glial stroma. Conclusion: Our results suggest that high expression of CAF-related biomarkers, particularly PDGFR-β and α-SMA, is associated with poor prognosis and recurrence in patients with BM. With the elucidation of the role and origins of CAF in the tumor microenvironment, CAF can be a new imperative target for BM immunotherapy.

The Medium Obtained from the Culture of Hodgkin Lymphoma Cells Affects the Biophysical Characteristics of a Fibroblast Cell Model

The neoplastic Hodgkin-Reed-Sternberg (HRS) cells in Hodgkin lymphoma (HL) represent only 1-10% of cells and are surrounded by an inflammatory microenvironment. The HL cytokine network is a key point for the proliferation of HRS cells and for the maintenance of an advantageous microenvironment for HRS survival. In the tumor microenvironment (TME), the fibroblasts are involved in crosstalk with HRS cells. The aim of this work was to study the effect of lymphoma cell conditioned medium on a fibroblast cell population and evaluate modifications of cell morphology and proliferation. Hodgkin lymphoma-derived medium was used to obtain a population of "conditioned" fibroblasts (WS-1 COND). Differences in biophysical parameters were detected by the innovative device Celector^®. Fibroblast-HL cells interactions were reproduced in 3D co-culture spheroids. WS-1 COND showed a different cellular morphology with an enlarged cytoplasm and enhanced metabolism. Area and diameter cell values obtained by Celector^® measurement were increased. Co-culture spheroids created with WS-1 COND showed a tighter aggregation than those with non-conditioned WS-1. The presence of soluble factors derived from HRS cells in the conditioned medium was adequate for the proliferation of fibroblasts and conditioned fibroblasts in a 3D HL model allowed to develop a representative model of the in vivo TME.

From the Catastrophic Objective Irreproducibility of Cancer Research and Unavoidable Failures of Molecular Targeted Therapies to the Sparkling Hope of Supramolecular Targeted Strategies

The unprecedented non-reproducibility of the results published in the field of cancer research has recently come under the spotlight. In this short review, we try to highlight some general principles in the organization and evolution of cancerous tumors, which objectively lead to their enormous variability and, consequently, the irreproducibility of the results of their investigation. This heterogeneity is also extremely unfavorable for the effective use of molecularly targeted medicine. Against the seemingly comprehensive background of this heterogeneity, we single out two supramolecular characteristics common to all tumors: the clustered nature of tumor interactions with their microenvironment and the formation of biomolecular condensates with tumor-specific distinctive features. We suggest that these features can form the basis of strategies for tumor-specific supramolecular targeted therapies.

Tumor microenvironment in ovarian cancer peritoneal metastasis

Ovarian cancer (OC) is one of the most common gynecological malignancies with high morbidity and mortality. The peritoneum is one of the most common metastatic sites in ovarian cancer, involving large amounts of ascites. However, its mechanism is unclear. The peritoneal microenvironment composed of peritoneal effusion and peritoneum creates favorable conditions for ovarian cancer progression and metastasis. Here, we reviewed the peritoneal metastasis patterns and molecular mechanisms of ovarian cancer, as well as major components of the peritoneal microenvironment, peritoneal effusion, and immune microenvironment, and investigated the relationship between the peritoneal microenvironment and ovarian cancer metastasis.

Ginsenoside Rg3 liposomes regulate tumor microenvironment for the treatment of triple negative breast cancer

OBJECTIVE

To improve the solubility and targeting of Ginsenoside Rg3 (G-Rg3), in the current study, we constructed a novel targeting functional material folic acid -poly(2-ethyl-2-oxazoline)-cholesteryl methyl carbonate (FA-PEOz-CHMC, FPC) modified G-Rg3 liposomes (FPC-Rg3-L).

METHODS

FPC was synthesized by using folic acid (FA) as a targeted head coupling with acid-activated poly(2-ethyl-2-oxazoline)-cholesteryl methyl carbonate. The inhibitory effects of the G-Rg3 preparations on mouse breast cancer cells (4T1) were investigated by CCK-8 assay. Paraffin sections of female BALB/c mice viscera were taken for hematoxylin-eosin (H&E) staining after continuous tail vein injection of G-Rg3 preparations. BALB/c mice bearing triple-negative breast cancer (TNBC) were used as animal models to investigate the inhibition of G-Rg3 preparations on tumor growth and improving quality of life. Transforming growth factor-β1 (TGF-β1) and α-smooth muscular actin (α-SMA) were used to investigate the expression of two fibrosis factors in tumor tissues by western blotting.

RESULTS

Compared with G-Rg3 solution (Rg3-S) and Rg3-L, FPC-Rg3-L had a significant inhibitory effect on 4T1 cells (p < .01), and the half maximal inhibitory concentration (IC₅₀) of FPC-Rg3-L was significantly lower (p < .01). The H&E results showed that the injection of FPC-Rg3-L and Rg3-S did not cause damage to the organs of mice. Compared with the control group, tumor growth was significantly inhibited in mice treated with FPC-Rg3-L and G-Rg3 solutions (p < .01).

CONCLUSIONS

This study presents a new and safe treatment for TNBC, reduces the toxic and side effects of the drug, and provides a reference for the efficient use of Chinese herbal medicine components.

Invasion characteristics and clinical significance of tumor-associated macrophages in gastrointestinal Krukenberg tumors

Background

Tumor-associated macrophages (TAMs) have been used as potential drug targets in preclinical research and clinical trials of various cancers. However, their distribution in Krukenberg tumors (KTs) remains unclear. We investigated the expression and prognostic value of TAMs in patients with gastrointestinal cancer with KTs.

Methods

The infiltration of various types of TAMs was detected in surgical tissues of 35 patients with KTs using immunohistochemical staining. The level of infiltration of TAMs in tumor nests (TN), tumor stroma (TS), and invasive margin (IM) areas was evaluated. The Kaplan-Meier method and univariate/multivariate Cox regression risk models were used to analyze the relationship between the degree of TAMs invasion and overall survival (OS) and progression-free survival (PFS).

Results

The distribution of TAMs exhibited spatial heterogeneity between TN, TS, and IM regions in primary tumor (PT) and KT tissues. TAMs infiltrated in the TN had greater prognostic value and were barely influenced by preoperative neoadjuvant therapy, despite similar grades of invasion in PT and KT tissues. Moreover, the number of CD68+ TAMs in TN of KT tissues was an independent risk factor affecting patient OS, whereas tumor resection scope might be an independent risk factor affecting patient PFS.

Conclusions

In view of the close relationship between TAMs, the tumor microenvironment and patient prognosis, targeting TAMs combined with chemotherapy is expected to become a new approach for the treatment of patients with KTs.

Exosomal long non-coding RNAs: novel molecules in gastrointestinal cancers' progression and diagnosis

Gastrointestinal (GI) cancers arise in the GI tract and accessory organs, including the mouth, esophagus, stomach, liver, biliary tract, pancreas, small intestine, large intestine, and rectum. GI cancers are a major cause of cancer-related morbidity and mortality worldwide. Exosomes act as mediators of cell-to-cell communication, with pleiotropic activity in the regulation of homeostasis, and can be markers for diseases. Non-coding RNAs (ncRNAs), such as long non-coding RNAs (lncRNAs), can be transported by exosomes derived from tumor cells or non-tumor cells. They can be taken by recipient cells to alter their function or remodel the tumor microenvironment. Moreover, due to their uniquely low immunogenicity and excellent stability, exosomes can be used as natural carriers for therapeutic ncRNAs in vivo. Exosomal lncRNAs have a crucial role in regulating several cancer processes, including angiogenesis, proliferation, drug resistance, metastasis, and immunomodulation. Exosomal lncRNA levels frequently alter according to the onset and progression of cancer. Exosomal lncRNAs can therefore be employed as biomarkers for the diagnosis and prognosis of cancer. Exosomal lncRNAs can also monitor the patient's response to chemotherapy while also serving as potential targets for cancer treatment. Here, we discuss the role of exosomal lncRNAs in the biology and possible future treatment of GI cancer.

Pan-cancer analysis identifies NT5E as a novel prognostic biomarker on cancer-associated fibroblasts associated with unique tumor microenvironment

Background: Ecto-5'-nucleotidase (NT5E) encodes the cluster of differentiation 73 (CD73), whose overexpression contributes to the formation of immunosuppressive tumor microenvironment and is related to exacerbated prognosis, increased risk of metastasis and resistance to immunotherapy of various tumors. However, the prognostic significance of NT5E in pan-cancer is obscure so far. Methods: We explored the expression level of NT5E in cancers and adjacent tissues and revealed the relationship between the NT5E expression level and clinical outcomes in pan-cancer by utilizing the UCSC Xena database. Then, correlation analyses were performed to evaluate the relationship between NT5E expression and immune infiltration level via EPIC, MCP-counter and CIBERSORT methods, and the enrichment analysis were employed to identify NT5E-interacting molecules and functional pathways. Furthermore, we conducted single-cell analysis to explore the potential role of NT5E on single-cell level based on the CancerSEA database. Meanwhile, gene set enrichment analysis (GSEA) in single-cell level was also conducted in TISCH database and single-cell signature explorer was utilized to evaluate the epithelial-mesenchymal transition (EMT) level in each cell type. Results: The expression level of NT5E was aberrant in almost all cancer types, and was correlated with worse prognosis in several cancers. Notably, NT5E overexpression was related to worse overall survival (OS) in pancreatic adenocarcinoma (PAAD), head and neck squamous cell carcinoma (HNSC), mesothelioma (MESO), stomach adenocarcinoma (STAD), uveal melanoma (UVM) and cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) (p < 0.01). NT5E-related immune microenvironment analysis revealed that NT5E is associated positively with the degree of infiltration of cancer-associated fibroblasts (CAFs) and endothelial cells in most cancers. Enrichment analysis of cellular component (CC) demonstrated the critical part of NT5E played in cell-substrate junction, cell-substrate adherens junction, focal adhesion and external side of plasma membrane. Finally, single-cell analysis of NT5E illuminated that EMT function of CAFs was elevated in basal cell carcinoma (BCC), skin cutaneous melanoma (SKCM), HNSC and PAAD. Conclusion: NT5E could serve as a potential prognostic biomarker for cancers. The potential mechanism may be related to the upregulated EMT function of CAFs, which provides novel inspiration for immunotherapy by targeting CAFs with high NT5E expression.

Estrogen-responsive cancer-associated fibroblasts promote invasive property of gastric cancer in a paracrine manner via CD147 production

Estrogen signaling has been extensively studied, especially in cancers that express estrogen receptor alpha (ERα). However, little is known regarding the effect of estrogen on cancer-associated fibroblasts (CAFs). Here, we explored the role of estrogen signaling of CAFs in gastric cancer (GC) progression. We investigated the phenotypic changes in CAFs upon 17β-estradiol (E2) treatment using ERα-negative/positive CAFs, and the conditioned media (CM) collected from these were compared with regard to cancer cell proliferation, migration, and invasion. A paracrine factor was found using a cytokine array and was confirmed using qRT-PCR, western blotting, and enzyme-linked immunosorbent assays. ERα-CD147-matrix metalloproteinase (MMP) axis was confirmed by knockdown experiments using specific siRNAs. We found that a subset of CAFs expressed ERα. ERα-positive CAFs were responsive to E2, inducing ERα expression in a dose-dependent manner. Although E2 did not induce the proliferation of ERα-positive CAFs, the CM from E2-bound ERα-positive CAFs significantly promoted cancer cell migration and invasion. Cytokine array revealed that CD147 was induced in ERα-positive CAFs upon E2 treatment; this was mediated via ERα. Increased CD147 upregulated MMP2 and MMP9 in CAFs, and also influenced cancer cells in a paracrine manner to increase MMPs and CD147 in cancer cells. High CD147 expression in tumor tissue was associated with a worse prognosis in GC patients. Our data suggest that estrogen signaling activation in CAFs and the byproduct CD147 are among the critical mediators between the interplay of CAFs and cancer cells to facilitate cancer progression.

Cancer-associated fibroblasts: Origin, function, imaging, and therapeutic targeting

The tumor microenvironment (TME) is emerging as one of the primary barriers in cancer therapy. Cancer-associated fibroblasts (CAF) are a common inhabitant of the TME in several tumor types and play a critical role in tumor progression and drug resistance via different mechanisms such as desmoplasia, angiogenesis, immune modulation, and cancer metabolism. Due to their abundance and significance in pro-tumorigenic mechanisms, CAF are gaining attention as a diagnostic target as well as to improve the efficacy of cancer therapy by their modulation. In this review, we highlight existing imaging techniques that are used for the visualization of CAF and CAF-induced fibrosis and provide an overview of compounds that are known to modulate CAF activity. Subsequently, we also discuss CAF-targeted and CAF-modulating nanocarriers. Finally, our review addresses ongoing challenges and provides a glimpse into the prospects that can spearhead the transition of CAF-targeted therapies from opportunity to reality.

Cancer-Associated Fibroblasts: The Origin, Biological Characteristics and Role in Cancer-A Glance on Colorectal Cancer

Simple Summary

Tumor microenvironment is a major contributor to tumor growth, metastasis and resistance to therapy. It consists of many cancer-associated fibroblasts (CAFs), which derive from different types of cells. CAFs detected in different tumor types are linked to poor prognosis, as in the case of colorectal cancer. Although their functions differ according to their subtype, their detection is not easy, and there are no established markers for such detection. They are possible targets for therapeutic treatment. Many trials are ongoing for their use as a prognostic factor and as a treatment target. More research remains to be carried out to establish their role in prognosis and treatment.

Abstract

The therapeutic approaches to cancer remain a considerable target for all scientists around the world. Although new cancer treatments are an everyday phenomenon, cancer still remains one of the leading mortality causes. Colorectal cancer (CRC) remains in this category, although patients with CRC may have better survival compared with other malignancies. Not only the tumor but also its environment, what we call the tumor microenvironment (TME), seem to contribute to cancer progression and resistance to therapy. TME consists of different molecules and cells. Cancer-associated fibroblasts are a major component. They arise from normal fibroblasts and other normal cells through various pathways. Their role seems to contribute to cancer promotion, participating in tumorigenesis, proliferation, growth, invasion, metastasis and resistance to treatment. Different markers, such as a-SMA, FAP, PDGFR-β, periostin, have been used for the detection of cancer-associated fibroblasts (CAFs). Their detection is important for two main reasons; research has shown that their existence is correlated with prognosis, and they are already under evaluation as a possible target for treatment. However, extensive research is warranted.

Mesenchymal stem cells derived from adipose tissue accelerate the progression of colon cancer by inducing a MTCAF phenotype via ICAM1/STAT3/AKT axis

Previous studies have shown that the risk of colon cancer is greatly increased in people with obesity, and fat content in colorectal cancer tissue is increased in people with obesity. As an important part of tumor microenvironment, adipose-derived mesenchymal stem cells (MSCs) are also another important source of cancer-associated fibroblasts (CAFs), which may be one of the important mechanisms of affecting tumor progression. However, the mechanism is poorly defined. In the present study, CAFs were transformed from MSCs [MSC-transformed CAFs (MTCAFs)] by co-culturing with HCT116 cells. Bioinformatics and Western blotting analysis indicated a positive correlation between intercellular adhesion molecule-1(ICAM-1) and the progression of colon cancer. In clinical colon cancer specimens, we found that ICAM-1 was highly expressed and related to shorter disease-free survival, which might act as an indication for the progression of clinical colon cancer. Our data showed that ICAM-1 secreted from MTCAFs could positively promote the proliferation, migration, and invasion of colon cancer cells by activating signal transducer and activator of transcription 3 (STAT3) and Serine/threonine-protein kinase (AKT) signaling and that blocking ICAM-1 in MTCAFs reversed these effects. We further verified that ICAM-1 secreted from MTCAFs promoted tumor progression in vivo. Taken together, ICAM-1 plays a critical role in regulating tumor growth and metastasis, which could be a potential therapeutic target in colon cancer.

Fight the Cancer, Hit the CAF!

Simple Summary

In the last 20 years, the tumor microenvironment (TME) has raised an increasing interest from the therapeutic point of view. Indeed, different strategies targeting either the endothelial or the immune component have been implemented. Furthermore, cancer-associated fibroblasts (CAF) have attracted even more interest due to their ability to prime the TME in order to favor tumor progression and metastasis. This current review provides a comprehensive overview on the latest discoveries regarding CAF, more specifically on their complex characterization and on preclinical studies and clinical trials that target CAF within the TME.

Abstract

The tumor microenvironment (TME) is comprised of different cellular components, such as immune and stromal cells, which co-operate in unison to promote tumor progression and metastasis. In the last decade, there has been an increasing focus on one specific component of the TME, the stromal component, often referred to as Cancer-Associated Fibroblasts (CAF). CAF modulate the immune response and alter the composition of the extracellular matrix with a decisive impact on the response to immunotherapies and conventional chemotherapy. The most recent publications based on single-cell analysis have underlined CAF heterogeneity and the unique plasticity that strongly impact the TME. In this review, we focus not only on the characterization of CAF based on the most recent findings, but also on their impact on the immune system. We also discuss clinical trials and preclinical studies where targeting CAF revealed controversial results. Therefore, future efforts should focus on understanding the functional properties of individual subtypes of CAF, taking into consideration the peculiarities of each pathological context.

Epigenetic alterations at distal enhancers are linked to proliferation in human breast cancer

Aberrant DNA methylation is an early event in breast carcinogenesis and plays a critical role in regulating gene expression. Here, we perform genome-wide expression-methylation Quantitative Trait Loci (emQTL) analysis through the integration of DNA methylation and gene expression to identify disease-driving pathways under epigenetic control. By grouping the emQTLs using biclustering we identify associations representing important biological processes associated with breast cancer pathogenesis including regulation of proliferation and tumor-infiltrating fibroblasts. We report genome-wide loss of enhancer methylation at binding sites of proliferation-driving transcription factors including CEBP-β, FOSL1, and FOSL2 with concomitant high expression of proliferation-related genes in aggressive breast tumors as we confirm with scRNA-seq. The identified emQTL-CpGs and genes were found connected through chromatin loops, indicating that proliferation in breast tumors is under epigenetic regulation by DNA methylation. Interestingly, the associations between enhancer methylation and proliferation-related gene expression were also observed within known subtypes of breast cancer, suggesting a common role of epigenetic regulation of proliferation. Taken together, we show that proliferation in breast cancer is linked to loss of methylation at specific enhancers and transcription factor binding and gene activation through chromatin looping.

The functional multipotency of transforming growth factor β signaling at the intersection of senescence and cancer

The transforming growth factor β (TGF-β) family of cytokines comprises a group of proteins, their receptors, and effector molecules that, in a coordinated manner, modulate a plethora of physiological and pathophysiological processes. TGF-β1 is the best known and plausibly most active representative of this group. It acts as an immunosuppressant, contributes to extracellular matrix remodeling, and stimulates tissue fibrosis, differentiation, angiogenesis, and epithelial-mesenchymal transition. In recent years, this cytokine has been established as a vital regulator of organismal aging and cellular senescence. Finally, the role of TGF-β1 in cancer progression is no longer in question. Because this protein is involved in so many, often overlapping phenomena, the question arises whether it can be considered a molecular bridge linking some of these phenomena together and governing their reciprocal interactions. In this study, we reviewed the literature from the perspective of the role of various TGF-β family members as regulators of a complex mutual interplay between senescence and cancer. These aspects are then considered in a broader context of remaining TGF-β-related functions and coexisting processes. The main narrative axis in this work is centered around the interaction between the senescence of normal peritoneal cells and ovarian cancer cells. The discussion also includes examples of TGF-β activity at the interface of other normal and cancer cell types.

Meaningful connections: Interrogating the role of physical fibroblast cell-cell communication in cancer

As part of the connective tissue, activated fibroblasts play an important role in development and disease pathogenesis, while quiescent resident fibroblasts are responsible for sustaining tissue homeostasis. Fibroblastic activation is particularly evident in the tumor microenvironment where fibroblasts transition into tumor-supporting cancer-associated fibroblasts (CAFs), with some CAFs maintaining tumor-suppressive functions. While the tumor-supporting features of CAFs and their fibroblast-like precursors predominantly function through paracrine chemical communication (e.g., secretion of cytokine, chemokine, and more), the direct cell-cell communication that occurs between fibroblasts and other cells, and the effect that the remodeled CAF-generated interstitial extracellular matrix has in these types of cellular communications, remain poorly understood. Here, we explore the reported roles fibroblastic cell-cell communication play within the cancer stroma context and highlight insights we can gain from other disciplines.

Integrated analysis of gene expression and DNA methylation datasets identified key genes and a 6-gene prognostic signature for primary lung adenocarcinoma

Lung adenocarcinoma (LUAD) is the main subtype of non-small cell lung cancer with a poor survival prognosis. In our study, gene expression, DNA methylation, and clinicopathological data of primary LUAD were utilized to identify potential prognostic markers for LUAD, which were recruited from The Cancer Genome Atlas (TCGA) database. Univariate regression analysis showed that there were 21 methylation-associated DEGs related to overall survival (OS), including 9 down- and 12 up-regulated genes. The 12 up-regulated genes with hypomethylation may be risky genes, whereas the other 9 down-regulated genes with hypermethylation might be protective genes. By using the Step-wise multivariate Cox analysis, a methylation-associated 6-gene (consisting of CCL20, F2, GNPNAT1, NT5E, B3GALT2, and VSIG2) prognostic signature was constructed and the risk score based on this gene signature classified patients into high- or low-risk groups. Patients of the high-risk group had shorter OS than those of the low-risk group in both the training and validation cohort. Multivariate Cox analysis and the stratified analysis revealed that the risk score was an independent prognostic factor for LUAD patients. The methylation-associated gene signature may serve as a prognostic factor for LUAD patients and the represent hypermethylated or hypomethylated genes might be potential targets for LUAD therapy.

Understanding the Role of Fibroblasts following a 3D Tumoroid Implantation for Breast Tumor Formation

An understanding of the participation and modulation of fibroblasts during tumor formation and growth is still unclear. Among many speculates, one might be the technical challenge to reveal the versatile function of fibroblasts in tissue complexity, and another is the dynamics in tissue physiology and cell activity. The histology of most solid tumors shows a predominant presence of fibroblasts, suggesting that tumor cells recruit fibroblasts for breast tumor growth. In this review paper, therefore, the migration, activation, differentiation, secretion, and signaling systems that are associated with fibroblasts and cancer-associated fibroblasts (CAFs) after implantation of a breast tumoroid, i.e., a lab-generated tumor tissue into an animal, are discussed.

The Role of Curcumin in Cancer Treatment

Curcumin is a polyphenol extracted from the rhizomes of the turmeric plant, Curcuma longa which has anti-inflammatory, and anticancer properties. Chronic inflammation is associated with the development of cancer. Curcumin acts on the regulation of various immune modulators, including cytokines, cyclooxygenase-2 (COX-2), and reactive oxygen species (ROS), which partly explains its anticancer effects. It also takes part in the downregulation of growth factors, protein kinases, oncogenic molecules and various signaling pathways, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), c-Jun N-terminal kinase (JNK) and signal transducer and activator of transcription 3 (STAT3) signaling. Clinical trials of curcumin have been completed or are ongoing for various types of cancer. This review presents the molecular mechanisms of curcumin in different types of cancer and the evidence from the most recent clinical trials.

18F-labeled tracers targeting fibroblast activation protein

Background

Cancer-associated fibroblasts are found in the stroma of epithelial tumors. They are characterized by overexpression of the fibroblast activation protein (FAP), a serine protease which was already proven as attractive target for chelator-based theranostics. Unfortunately, the value of gallium-68 labeled tracers is limited by their batch size and the short nuclide half-life. To overcome this drawback, radiolabeling with aluminum fluoride complexes and 6-fluoronicotinamide derivatives of the longer-lived nuclide fluorine-18 was established. The novel compounds were tested for their FAP-specific binding affinity. Uptake and binding competition were studied in vitro using FAP expressing HT-1080 cells. HEK cells transfected with the closely related dipeptidyl peptidase-4 (HEK-CD26) were used as negative control. Small animal positron emission tomography imaging and biodistribution experiments were performed in HT-1080-FAP xenografted nude mice. [¹⁸F]AlF-FAPI-74 was selected for PET/CT imaging in a non-small cell lung cancer (NSCLC) patient.

Results

In vitro, ¹⁸F-labeled FAPI-derivatives demonstrated high affinity (EC₅₀ = < 1 nm to 4.2 nm) and binding of up to 80% to the FAP-expressing HT1080 cells while no binding to HEK-CD26 cells was observed. While small animal PET imaging revealed unfavorable biliary excretion of most of the ¹⁸F-labeled compounds, the NOTA bearing compounds [¹⁸F]AlF-FAPI-74 and -75 achieved good tumor-to-background ratios, as a result of their preferred renal excretion. These two compounds showed the highest tumor accumulation in PET imaging. The organ distribution values of [¹⁸F]AlF-FAPI-74 were in accordance with the small animal PET imaging results. Due to its less complex synthesis, fast clearance and low background values, [¹⁸F]AlF-FAPI-74 was chosen for clinical imaging. PET/CT of a patient with metastasized non-small cell lung cancer (NSCLC), enabled visualization of the primary tumor and its metastases at the hepatic portal and in several bones. This was accompanied by a rapid clearance from the blood pool and low background in healthy organs.

Conclusion

[¹⁸F]AlF-labeled FAPI derivatives represent powerful tracers for PET. Owing to an excellent performance in PET imaging, FAPI-74 can be regarded as a promising precursor for [¹⁸F]AlF-based FAP-imaging.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41181-021-00144-x.

CAFs Interacting With TAMs in Tumor Microenvironment to Enhance Tumorigenesis and Immune Evasion

Cancer associated fibroblasts (CAFs) and tumor associated macrophages (TAMs) are among the most important and abundant players of the tumor microenvironment. CAFs as well as TAMs are known to play pivotal supportive roles in tumor growth and progression. The number of CAF or TAM cells is mostly correlated with poor prognosis. Both CAFs and TAMs are in a reciprocal communication with the tumor cells in the tumor milieu. In addition to such interactions, CAFs and TAMs are also involved in a dynamic and reciprocal interrelationship with each other. Both CAFs and TAMs are capable of altering each other's functions. Here, the current understanding of the distinct mechanisms about the complex interplay between CAFs and TAMs are summarized. In addition, the consequences of such a mutual relationship especially for tumor progression and tumor immune evasion are highlighted, focusing on the synergistic pleiotropic effects. CAFs and TAMs are crucial components of the tumor microenvironment; thus, they may prove to be potential therapeutic targets. A better understanding of the tri-directional interactions of CAFs, TAMs and cancer cells in terms of tumor progression will pave the way for the identification of novel theranostic cues in order to better target the crucial mechanisms of carcinogenesis.

Cancer-Associated Fibroblasts: Implications for Cancer Therapy

Tumour cells do not exist as an isolated entity. Instead, they are surrounded by and closely interact with cells of the environment they are emerged in. The tumour microenvironment (TME) is not static and several factors, including cancer cells and therapies, have been described to modulate several of its components. Fibroblasts are key elements of the TME with the capacity to influence tumour progression, invasion and response to therapy, which makes them attractive targets in cancer treatment. In this review, we focus on fibroblasts and their numerous roles in the TME with a special attention to recent findings describing their heterogeneity and role in therapy response. Furthermore, we explore how different therapies can impact these cells and their communication with cancer cells. Finally, we highlight potential strategies targeting this cell type that can be employed for improving patient outcome.

Single-cell transcriptomic analysis of endometriosis provides insights into fibroblast fates and immune cell heterogeneity

Background

Endometriosis is an oestrogen-dependent disease with an unclear aetiology and pathogenesis affecting 6–10% of the global female population, predominantly those of reproductive age. Herein, we profile the transcriptomes of approximately 55,000 single cells from three groups including ectopic endometrium, eutopic endometrium from women with endometriosis, and eutopic endometrium from healthy women to create a single-cell transcriptome atlas of endometriosis.

Results

We have identified 9 cell types and performed single-cell analysis of fibroblasts, and determined a potential developmental trajectory associated with endometriosis. We also identified fibroblast subpopulations related to endometriosis development and found that StAR played an important role in this process. Moreover, T cells in endometriosis were less activated or inflammatory with decreased effector CD8 + T cells, while the composition ratio of natural killer cells decreased and the percentage of monocytes/macrophages increased in endometriosis cysts. In addition, the effectiveness of immune cells in endometriosis lesions, eutopic endometrium from women with endometriosis, and eutopic endometrium from healthy women was distinct. Cell–cell interaction analyses highlighted the imbalanced immune environment in endometriosis lesions and immune cells in endometriosis could promote the development of the disease.

Conclusion

Our study provided a systematic characterisation of endometriosis and insights into the aetiology and pathology of endometriosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00637-x.

Effects of CAF-Derived MicroRNA on Tumor Biology and Clinical Applications

Cancer-associated fibroblasts (CAFs), prominent cell components of the tumor microenvironment (TME) in most types of solid tumor, play an essential role in tumor cell growth, proliferation, invasion, migration, and chemoresistance. MicroRNAs (miRNAs) are small, non-coding, single-strand RNAs that negatively regulate gene expression by post-transcription modification. Increasing evidence has suggested the dysregulation of miRNAs in CAFs, which facilitates the conversion of normal fibroblasts (NFs) into CAFs, then enhances the tumor-promoting capacity of CAFs. To understand the process of tumor progression, as well as the development of chemoresistance, it is important to explore the regulatory function of CAF-derived miRNAs and the associated molecular mechanisms, which may become potential diagnostic and prognostic biomarkers and targets of anti-tumor therapeutics. In this review, we describe miRNAs that are differentially expressed by NFs and CAFs, summarize the modulating role of CAF-derived miRNAs in fibroblast activation and tumor advance, and eventually identify a potential clinical application for CAF-derived miRNAs as diagnostic/prognostic biomarkers and therapeutic targets in several tumors.

Embryonic protein NODAL regulates the breast tumor microenvironment by reprogramming cancer-derived secretomes

The tumor microenvironment (TME) is an important mediator of breast cancer progression. Cancer-associated fibroblasts constitute a major component of the TME and may originate from tissue-associated fibroblasts or infiltrating mesenchymal stromal cells (MSCs). The mechanisms by which cancer cells activate fibroblasts and recruit MSCs to the TME are largely unknown, but likely include deposition of a pro-tumorigenic secretome. The secreted embryonic protein NODAL is clinically associated with breast cancer stage and promotes tumor growth, metastasis, and vascularization. Herein, we show that NODAL expression correlates with the presence of activated fibroblasts in human triple-negative breast cancers and that it directly induces Cancer-associated fibroblasts phenotypes. We further show that NODAL reprograms cancer cell secretomes by simultaneously altering levels of chemokines (e.g., CXCL1), cytokines (e.g., IL-6) and growth factors (e.g., PDGFRA), leading to alterations in MSC chemotaxis. We therefore demonstrate a hitherto unappreciated mechanism underlying the dynamic regulation of the TME.

Fibroblasts in cancer dormancy: foe or friend?

Cancer dormancy is defined that the residual cancer cells could enter into a state of quiescence and patients remain asymptomatic for years or even decades after anti-tumor therapies. Fibroblasts, which represent a predominant cell type in tumor microenvironment, play a pivotal role in determining the ultimate fate of tumor cells. This review recapitulates the pleiotropic roles of fibroblasts which are divided into normal, senescent, cancer-associated fibroblasts (CAFs) and circulation CAFs in tumor dormancy, relapse, metastasis and resistance to therapy to help the treatment of cancer metastasis.

CD169 Expression on Lymph Node Macrophages Predicts in Patients With Gastric Cancer

The induction of an anti-cancer immune responses is potentially associated with the efficacy of anti-cancer therapy. Recent studies have indicated that sinus macrophages in regional lymph nodes are involved in anti-cancer immune responses in the cancer microenvironment. In the present study, we investigated the correlation between lymphocyte infiltration in cancer tissues and macrophage activation in regional lymph nodes. We retrospectively identified 294 patients with gastric cancer who underwent surgery from 2008 to 2012. Using immunohistochemistry, we evaluated CD169-expression on CD68-positive macrophages, and the density of CD8-postive lymphocytes in tumor microenvironment. We statistically examined the correlation between CD169 and CD8 expression, and performed Cox regression analysis of potential prognostic factors, including CD169 and CD8 expression, for cancer-specific survival (CSS) in patients with total and advanced gastric cancer. CD169 overexpression in lymph node sinus macrophages (LySMs) was positively correlated to the density of CD8-positive lymphocytes in primary cancer tissues (R = 0.367, p < 0.001). A high density of CD8-positive T lymphocytes in the primary site and a high level of CD169 expression in LySMs were independently associated with greater CSS in patients with total and advanced gastric cancer (p < 0.05 for all). The expression on CD169 in LySMs is a predictor of a favorable clinical course in patients with gastric cancer, and might be useful for evaluating anti-cancer immune responses.

Tumor-secreted exosomal Wnt2B activates fibroblasts to promote cervical cancer progression

The activation of stromal fibroblasts into cancer-associated fibroblasts (CAFs) has been suggested to promote primary tumor growth and progression; however, the mechanisms underlying the crosstalk between tumors and fibroblasts that drives stromal heterogeneity remain unknown. Here, we show that high Wnt2B levels were positively correlated with the number of CAFs in cervical cancer (CC). More importantly, Wnt2B was characteristically enriched in CC cell-secreted exosomes and transferred into fibroblasts to promote fibroblast activation via Wnt/β-catenin signaling, and inhibiting exosomal release or the Wnt/β-catenin signaling pathway diminished the activation induced by exosomal Wnt2B. Moreover, circulating exosomal Wnt2B also promoted CAF conversion in vitro and its expression was significantly higher in CC patients. In conclusion, our findings indicate that CC cell-derived Wnt2B can induce the activation of fibroblasts into CAFs, mainly via exosome-dependent secretion, thus providing directions for the development of diagnostic and therapeutic targets for CC progression.

Lipid Metabolism in Tumor-Associated Fibroblasts

Tumor- or cancer-associated fibroblasts (TAFs), one of the most abundant stromal cell types in various carcinomas, consist of a heterogeneous cell population. Typically, TAFs are assigned with pro-tumor activities to promote tumor growth and progression. One of the key features of solid tumors is the metabolic reprogramming that induces alterations of bioenergetics and biosynthesis in both tumor cells and TAFs. Therefore, this review emphasizes TAFs lipid metabolism related to both TAFs differentiation process and TAFs crosstalk with cancer cells. We hope that this review will help understand lipid metabolism in tumor microenvironment, and support the rational design of metabolism-based approaches to improve the efficacy of cancer therapy.

TGFβ Signaling in the Tumor Microenvironment

Transforming growth factor beta (TGFβ) is a pleiotropic growth factor. Under normal physiological conditions, TGFβ maintains homeostasis in mammalian tissues by restraining the growth of cells and stimulating apoptosis. However, the role of TGFβ signaling in the carcinogenesis is complex. TGFβ acts as a tumor suppressor in the early stages of disease and as a tumor promoter in its later stages where cancer cells have been relieved from TGFβ growth controls. Overproduction of TGFβ by cancer cells lead to a local fibrotic and immune-suppressive microenvironment that fosters tumor growth and correlates with invasive and metastatic behavior of the cancer cells. Here, we present an overview of the complex biology of the TGFβ family, and we discuss the roles of TGFβ signaling in carcinogenesis and how this knowledge is being leveraged to develop TGFβ inhibition therapies against the tumor.

Cancer-associated fibroblasts and their influence on tumor immunity and immunotherapy

Fibroblasts play an essential role in organogenesis and the integrity of tissue architecture and function. Growth in most solid tumors is dependent upon remodeling 'stroma', composed of cancer-associated fibroblasts (CAFs) and extracellular matrix (ECM), which plays a critical role in tumor initiation, progression, metastasis, and therapeutic resistance. Recent studies have clearly established that the potent immunosuppressive activity of stroma is a major mechanism by which stroma can promote tumor progression and confer resistance to immune-based therapies. Herein, we review recent advances in identifying the stroma-dependent mechanisms that regulate cancer-associated inflammation and antitumor immunity, in particular, the interactions between fibroblasts and immune cells. We also review the potential mechanisms by which stroma can confer resistance to immune-based therapies for solid tumors and current advancements in stroma-targeted therapies.

Advanced co-culture 3D breast cancer model for investigation of fibrosis induced by external stimuli: optimization study

Radiation-induced fibrosis (RIF) is the main late radiation toxicity in breast cancer patients. Most of the current 3D in vitro breast cancer models are composed by cancer cells only and are unable to reproduce the complex cellular homeostasis within the tumor microenvironment to study RIF mechanisms. In order to account complex cellular interactions within the tumor microenvironment, an advanced 3D spheroid model, consisting of the luminal breast cancer MCF-7 cells and MRC-5 fibroblasts, was developed. The spheroids were generated using the liquid overlay technique in culture media into 96-well plates previously coated with 1% agarose (m/v, in water). In total, 21 experimental setups were tested during the optimization of the model. The generated spheroids were characterized using fluorescence imaging, immunohistology and immunohistochemistry. The expression of ECM components was confirmed in co-culture spheroids. Using α-SMA staining, we confirmed the differentiation of healthy fibroblasts into myofibroblasts upon the co-culturing with cancer cells. The induction of fibrosis was studied in spheroids treated 24 h with 10 ng/mL TGF-β and/or 2 Gy irradiation. Overall, the developed advanced 3D stroma-rich in vitro model of breast cancer provides a possibility to study fibrosis mechanisms taking into account 3D arrangement of the complex tumor microenvironment.

Altered Tissue and Plasma Levels of Fibroblast Activation Protein-α (FAP) in Renal Tumours

Simple Summary

Malignant epithelial tumour’s behaviour in the kidney has traditionally been analysed attending to different prognostic parameters focussed on the proliferating neoplastic cell. This is the case of renal cell carcinoma (RCC), in which a large tumour diameter, high histological grade, and the presence of necrosis, among other factors, have been related with a high risk of distant metastasis and, therefore, worse survival. Recently, several elements of the tumour microenviroment, such as cancer-associated fibroblasts (CAFs), are being studied in order to develop more accurate diagnostic and therapeutic approaches. We present data that support that the fibroblast activation protein-α (FAP), a CAF biomarker, provides interesting information both in tumour tissues and in plasma from patients with RCC.

Abstract

(1) Background: Renal cell carcinoma (RCC) is a heterogeneous and complex disease with only partial response to therapy, high incidence of metastasis and recurrences, and scarce reliable biomarkers indicative of progression and survival. Cancer-associated fibroblasts (CAFs) play an important role supporting and promoting renal cancer progression. (2) Methods: In this study, we analysed fibroblast activation protein-α (FAP) immunohistochemical expression and its soluble isoform (sFAP) in tumour tissues and plasma from 128 patients with renal tumours. (3) Results: FAP is expressed in the cell surface of CAFs of the tumour centre and infiltrating front from clear cell renal cell carcinomas (CCRCC, n = 89), papillary renal cell carcinomas (PRCC, n = 21), and chromophobe renal cell carcinomas (ChRCC, n = 8), but not in the benign tumour renal oncocytoma (RO, n = 10). A high expression of FAP and low levels sFAP are significantly associated with high tumour diameter, high grade, and high pT stage, lymph node invasion, development of early metastases, and worse 5-year cancer specific survival of CCRCC patients. (4) Conclusions: These findings corroborate the potential usefulness of FAP immunohistochemistry and plasma sFAP as a biomarker of CCRCC progression and point to CAF-related proteins as promising immunohistochemical biomarkers for the differential diagnosis of ChRCC and RO.

Periostin+ cancer-associated fibroblasts promote lymph node metastasis by impairing the lymphatic endothelial barriers in cervical squamous cell carcinoma

Lymph node metastasis (LNM), a critical prognostic determinant in cancer patients, is critically influenced by the presence of numerous heterogeneous cancer‐associated fibroblasts (CAFs) in the tumor microenvironment. However, the phenotypes and characteristics of the various pro‐metastatic CAF subsets in cervical squamous cell carcinoma (CSCC) remain unknown. Here, we describe a CAF subpopulation with elevated periostin expression (periostin⁺CAFs), located in the primary tumor sites and metastatic lymph nodes, that positively correlated with LNM and poor survival in CSCC patients. Mechanistically, periostin⁺CAFs impaired lymphatic endothelial barriers by activating the integrin‐FAK/Src‐VE‐cadherin signaling pathway in lymphatic endothelial cells and consequently enhanced metastatic dissemination. In contrast, inhibition of the FAK/Src signaling pathway alleviated periostin‐induced lymphatic endothelial barrier dysfunction and its related effects. Notably, periostin^‐CAFs were incapable of impairing endothelial barrier integrity, which may explain the occurrence of CAF‐enriched cases without LNM. In conclusion, we identified a specific periostin⁺CAF subset that promotes LNM in CSCC, mainly by impairing the lymphatic endothelial barriers, thus providing the basis for potential stromal fibroblast‐targeted interventions that block CAF‐dependent metastasis.

Single-Cell RNA Sequencing Unravels Heterogeneity of the Stromal Niche in Cutaneous Melanoma Heterogeneous Spheroids

Heterogeneous spheroids have recently acquired a prominent position in melanoma research because they incorporate microenvironmental cues relevant for melanoma. In this study, we focused on the analysis of microenvironmental factors introduced in melanoma heterogeneous spheroids by different dermal fibroblasts. We aimed to map the fibroblast diversity resulting from previously acquired damage caused by exposure to extrinsic and intrinsic stimuli. To construct heterogeneous melanoma spheroids, we used normal dermal fibroblasts from the sun-protected skin of a juvenile donor. We compared them to the fibroblasts from the sun-exposed photodamaged skin of an adult donor. Further, we analysed the spheroids by single-cell RNA sequencing. To validate transcriptional data, we also compared the immunohistochemical analysis of heterogeneous spheroids to melanoma biopsies. We have distinguished three functional clusters in primary human fibroblasts from melanoma spheroids. These clusters differed in the expression of (a) extracellular matrix-related genes, (b) pro-inflammatory factors, and (c) TGFβ signalling superfamily. We observed a broader deregulation of gene transcription in previously photodamaged cells. We have confirmed that pro-inflammatory cytokine IL-6 significantly enhances melanoma invasion to the extracellular matrix in our model. This supports the opinion that the aspects of ageing are essential for reliable melanoma 3D modelling in vitro.