Carcinoma-associated fibroblasts provide operational flexibility in metastasis

Diversified nanocarrier design to optimize glucose oxidase-mediated anti-tumor therapy: Strategy and progress

Given the inherent complexity and heterogeneity of tumors, current therapeutic approaches often fall short in meeting prognostic requirements. Starvation therapy (ST) utilizing glucose oxidase (GOx) has emerged as a promising strategy, specifically targeting tumor glucose consumption to disrupt nutrient supply. However, the therapeutic potential of GOx is significantly hampered by its inherent limitations as a protein, particularly its poor stability and short in vivo half-life. In recent years, the development of nanocarriors has provided an effective platform for intravenous and local tumor delivery of GOx. This review systematically examines three key strategies in GOx delivery: stimulus-response, biofilm modification, and local delivery. The progress in various carrier systems for GOx-mediated tumor therapy is comprehensively summarized, providing valuable insights for nanocarrier design. Furthermore, the existing challenges and future directions to advance the development of GOx-based tumor therapies are critically analyzed.

Promotion Mechanisms of Stromal Cell-Mediated Lung Cancer Development Within Tumor Microenvironment

Lung cancer, with its high incidence and mortality rates, has garnered significant attention in the medical community. The tumor microenvironment (TME), composed of tumor cells, stromal cells, extracellular matrix, surrounding blood vessels, and other signaling molecules, plays a pivotal role in the development of lung cancer. Stromal cells within the TME hold potential as therapeutic targets for lung cancer treatment. However, the precise and comprehensive mechanisms by which stromal cells contribute to lung cancer progression have not been fully elucidated. This review aims to explore the mechanisms through which stromal cells in the tumor microenvironment promote lung cancer development, with a particular focus on how immune cells, tumor-associated fibroblasts, and endothelial cells contribute to immune suppression, inflammation, and angiogenesis. The goal is to provide new insights and potential strategies for the diagnosis and treatment of lung cancer.

Ovarian cancer extracellular vesicle biomarkers

Ovarian cancer (OC) remains a significant women's health concern due to its high mortality rate and the challenges posed by late detection. Exploring novel biomarkers could lead to earlier, more specific diagnoses and improved survival rates for OC patients. This review focuses on biomarkers associated with extracellular vesicles (EVs) found in various proximal fluids, including urine, ascites, utero-tubal lavage fluid of OC patients. We highlight these proximal fluids as rich sources of potential biomarkers. The review explains the roles of EV biomarkers in ovarian cancer progression and discusses EV-related proteins and miRNAs as potential diagnostic or prognostic indicators and therapeutic targets. Finally, we highlighted the limitations of examining proximal fluids as sources of biomarkers and encourage researchers to proactively pursue innovative solutions to overcome these challenges.

Unraveling the role of cancer-associated fibroblasts in B cell lymphoma

Recent breakthroughs in research have sparked a paradigm shift in our understanding of cancer biology, uncovering the critical role of the crosstalk between tumor cells and the immune cells of the tumor microenvironment (TME) in malignant transformation. Fibroblasts have long been viewed as ancillary participants in cancer progression, often eclipsed by the prominence given to malignant cells. Novel investigations, however, have increasingly acknowledged the essential part played by the fibroblasts and their phenotypic doppelganger cancer-associated fibroblasts (CAFs) in fostering immunosuppression and promoting tumor progression. Here we review the cell-of-origin from which CAFs derive and their altered programs compared to their normal counterpart. We will also discuss the complex interplay between CAFs and the surrounding immune cells of the TME in the context of solid tumors and B cell lymphomas, with a focus on the "reprogrammable" role of CAFs in immunosuppression, immuno-activation and immuno-avoidance, and their implications on drug resistance. Finally, we will examine the existing and plausible therapeutic approaches targeting CAFs as a strategy to enhance treatment response.

Upregulation of FGF9 and NOVA1 in cancer-associated fibroblasts promotes cell proliferation, invasion and migration of triple negative breast cancer

Cancer-associated fibroblasts (CAFs) play a pivotal role in cancer progression. This study aimed to explore the roles of CAFs-derived Fibroblast growth factor 9 (FGF9) and Neuro-oncological ventral antigen 1 (NOVA1) in triple negative breast cancer (TNBC) progression. MDA-MB-231 and BT-549 cells were cocultured with CAF conditioned-medium (CAF-CM) or normal fibroblasts conditioned-medium (NF-CM). MTT, EdU, colony formation, wound healing, transwell migration, and invasion assays were employed to determine cell proliferation, migration and invasion, respectively. Western blot and RT-qPCR were carried out to examine the protein and mRNA expression of FGF9 and NOVA1. Xenograft tumor experiments were conducted to evaluate the effects of CAFs, FGF9, and NOVA1 on tumor growth in vivo. Our results showed that CAFs significantly promoted the proliferation, invasion, and migration of TNBC cells. FGF9 and NOVA1 were significantly upregulated in TNBC CAFs, tissues and cells. CAF-CM also could increase the expression of FGF9 and NOVA1 in TNBC cells. Knockdown of FGF9 or NOVA1 could hamper cell proliferation, invasion, migration, and EMT of TNBC cells. Moreover, CAFs with FGF9/NOVA1 knockdown also could inhibit TNBC progression. Besides, CAFs significantly accelerated tumor growth in vivo, which was blocked by FGF9/NOVA1 knockdown in nude mice. In conclusion, our results indicated the tumor-promoting role of CAFs in TNBC progression. FGF9 and NOVA1 upregulation in CAFs induced cell proliferation, migration and invasion in vitro, and facilitated tumor growth in vivo in TNBC development.

Extracellular vesicles as tools and targets in therapy for diseases

Extracellular vesicles (EVs) are nano-sized, membranous structures secreted into the extracellular space. They exhibit diverse sizes, contents, and surface markers and are ubiquitously released from cells under normal and pathological conditions. Human serum is a rich source of these EVs, though their isolation from serum proteins and non-EV lipid particles poses challenges. These vesicles transport various cellular components such as proteins, mRNAs, miRNAs, DNA, and lipids across distances, influencing numerous physiological and pathological events, including those within the tumor microenvironment (TME). Their pivotal roles in cellular communication make EVs promising candidates for therapeutic agents, drug delivery systems, and disease biomarkers. Especially in cancer diagnostics, EV detection can pave the way for early identification and offers potential as diagnostic biomarkers. Moreover, various EV subtypes are emerging as targeted drug delivery tools, highlighting their potential clinical significance. The need for non-invasive biomarkers to monitor biological processes for diagnostic and therapeutic purposes remains unfulfilled. Tapping into the unique composition of EVs could unlock advanced diagnostic and therapeutic avenues in the future. In this review, we discuss in detail the roles of EVs across various conditions, including cancers (encompassing head and neck, lung, gastric, breast, and hepatocellular carcinoma), neurodegenerative disorders, diabetes, viral infections, autoimmune and renal diseases, emphasizing the potential advancements in molecular diagnostics and drug delivery.

The role of extracellular vesicles in cholangiocarcinoma tumor microenvironment

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

Cancer-associated fibroblasts in hematologic malignancies: elucidating roles and spotlighting therapeutic targets

Hematologic malignancies comprise a diverse range of blood, bone marrow, and organ-related disorders that present significant challenges due to drug resistance, relapse, and treatment failure. Cancer-associated fibroblasts (CAFs) represent a critical component of the tumor microenvironment (TME) and have recently emerged as potential therapeutic targets. In this comprehensive review, we summarize the latest findings on the roles of CAFs in various hematologic malignancies, including acute leukemia, multiple myeloma, chronic lymphocytic leukemia, myeloproliferative neoplasms, and lymphoma. We also explore their involvement in tumor progression, drug resistance, and the various signaling pathways implicated in their activation and function. While the underlying mechanisms and the existence of multiple CAF subtypes pose challenges, targeting CAFs and their associated pathways offers a promising avenue for the development of innovative treatments to improve patient outcomes in hematologic malignancies.

KISS1 metastasis suppressor in tumor dormancy: a potential therapeutic target for metastatic cancers?

Present therapeutic approaches do not effectively target metastatic cancers, often limited by their inability to eliminate already-seeded non-proliferative, growth-arrested, or therapy-resistant tumor cells. Devising effective approaches targeting dormant tumor cells has been a focus of cancer clinicians for decades. However, progress has been limited due to limited understanding of the tumor dormancy process. Studies on tumor dormancy have picked up pace and have resulted in the identification of several regulators. This review focuses on KISS1, a metastasis suppressor gene that suppresses metastasis by keeping tumor cells in a state of dormancy at ectopic sites. The review explores mechanistic insights of KISS1 and discusses its potential application as a therapeutic against metastatic cancers by eliminating quiescent cells or inducing long-term dormancy in tumor cells.

Exosomes Derived from Immune Cells: The New Role of Tumor Immune Microenvironment and Tumor Therapy

Exosomes are small vesicles secreted by living cells, with a typical lipid bilayer structure. They carry a variety of proteins, lipids, RNA and other important information, play an important role in the transmission of substances and information between cells, and gradually become a marker for early diagnosis of many diseases and an important tool in drug delivery system. Immune cells are an important part of tumor microenvironment, and they can affect tumor progression by secreting a variety of immunoreactive substances. This review focuses on the effects of various immune cell-derived exosomes on tumor cells, different immune cells and other stromal cells in tumor microenvironment. Exosomes derived from different immune cells can not only reshape a pro-inflammatory microenvironment to inhibit tumor progression, but also promote tumor progression by inhibiting the killing effect of NK cells, CD8⁺T cells and other cells or promoting tumor cells and immunosuppressive immune cells. In addition, we also discussed that some exosomes derived from immune cells (such as DC, M1 macrophages and neutrophils) play a tumor inhibitory role after being engineered.

Anti-TGF-β/PD-L1 bispecific antibody promotes T cell infiltration and exhibits enhanced antitumor activity in triple-negative breast cancer

BACKGROUND

Agents blocking programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) have been approved for triple-negative breast cancer (TNBC). However, the response rate of anti-PD-1/PD-L1 is still unsatisfactory, partly due to immunosuppressive factors such as transforming growth factor-beta (TGF-β). In our previous pilot study, the bispecific antibody targeting TGF-β and murine PD-L1 (termed YM101) showed potent antitumor effect. In this work, we constructed a bispecific antibody targeting TGF-β and human PD-L1 (termed BiTP) and explored the antitumor effect of BiTP in TNBC.

METHODS

BiTP was developed using Check-BODYTM bispecific platform. The binding affinity of BiTP was measured by surface plasmon resonance, ELISA, and flow cytometry. The bioactivity was assessed by Smad and NFAT luciferase reporter assays, immunofluorescence, western blotting, and superantigen stimulation assays. The antitumor activity of BiTP was explored in humanized epithelial-mesenchymal transition-6-hPDL1 and 4T1-hPDL1 murine TNBC models. Immunohistochemical staining, flow cytometry, and bulk RNA-seq were used to investigate the effect of BiTP on immune cell infiltration.

RESULTS

BiTP exhibited high binding affinity to dual targets. In vitro experiments verified that BiTP effectively counteracted TGF-β-Smad and PD-L1-PD-1-NFAT signaling. In vivo animal experiments demonstrated that BiTP had superior antitumor activity relative to anti-PD-L1 and anti-TGF-β monotherapy. Mechanistically, BiTP decreased collagen deposition, enhanced CD8+ T cell penetration, and increased tumor-infiltrating lymphocytes. This improved tumor microenvironment contributed to the potent antitumor activity of BiTP.

CONCLUSION

BiTP retains parent antibodies' binding affinity and bioactivity, with superior antitumor activity to parent antibodies in TNBC. Our data suggest that BiTP might be a promising agent for TNBC treatment.

Extracellular Vesicles Derived from Lung Cancer Cells Induce Transformation of Normal Fibroblasts into Lung Cancer-Associated Fibroblasts and Promote Metastasis of Lung Cancer by Delivering lncRNA HOTAIR

Human lung cancer (LC) cells A549/H358, normal lung epithelial cells BEAS-2B, and lung normal fibroblasts (NFs) were cultured, followed by transfection of H358 cells with HOTAIR shRNA. Extracellular vesicles (EVs) extracted from H358 cells were identified. The internalization of Dil-labeled-EVs by NFs was tested, and protein levels of cancer-associated fibroblast (CAF) surface markers, inflammatory cytokines, cell proliferation, invasion, and migration, and lncRNA HOTAIR levels were determined. A549 cells were cultured in an H358-EVs-treated conditioned medium of NFs (NFCM), followed by intravenous injection of A549 cells into nude mice. The lesions and Ki-67-positive cells in lung tissues were measured. The results showed that tumor cell-derived EVs (T-EVs) motivated the transformation of NFs into CAFs. Specifically, EVs can be internalized by NFs, and the protein levels of CAF surface markers and inflammation levels were elevated in H358-EVs-treated NFs. The proliferation, invasion, and migration of A549 cells cultured in T-EVs-treated NFCM were increased. H358-EVs carried HOTAIR into NFs and promoted the transformation of NFs into CAFs. Inhibition of HOTAIR partially reversed the promoting effect of H358-EVs on the transformation of NFs into CAFs and invasion and migration of LC cells. T-EVs promoted metastasis of LC in vivo by transforming NFs into CAFs.

Epstein-Barr viral product-containing exosomes promote fibrosis and nasopharyngeal carcinoma progression through activation of YAP1/FAPα signaling in fibroblasts

Background

The progression of nasopharyngeal carcinoma (NPC) is profoundly affected by Epstein-Barr virus (EBV) infection. However, the role of EBV in the intercommunication between NPC and surrounding stromal cells has yet to be explored.

Methods

NPC biopsies were obtained for immunohistochemical (IHC) analyses. Clinical correlations between the expression of active YAP1/FAPα and the fibrotic response and between YAP1/FAPα and the density of cytotoxic CD8a+ T lymphocytes were determined. Survival times based on IHC scores were compared between groups using Kaplan-Meier survival and log-rank tests. Independent prognostic factors for metastasis/recurrence-free survival and overall survival were identified using univariate and multivariate Cox regression models. Fibroblasts were isolated from human nasopharyngeal biopsies. Exosomes were purified from culture supernatants of EBV+-positive NPC cells. The effects of EBV product-containing exosomes on fibroblast activation, fibrotic response, tumor growth, immune response, and correlations between the expression of featured genes were investigated using gel contraction assays, ELISAs, EdU incorporation assays, real-time impedance assays, RNA sequencing, immunostaining, 3D cancer spheroid coculture systems, and an NPC xenograft model.

Results

NPC patients who developed metastasis had significantly higher levels of active YAP1 and FAPα in their tumor stroma, which was further correlated with tumor fibrosis and poorer metastasis-free survival. Exosomes released from EBV+-NPC cells contained abundant FAPα protein and EBV-encoded latent membrane protein 1. Viral product-containing exosomes markedly enhanced the fibrotic response and tumor growth in a mouse xenograft model. IHC analyses of human NPC and NPC xenografts revealed positive correlations between levels of active YAP1 and FAPα, YAP1 and the fibrotic response, and FAPα and the fibrotic response. Mechanistic studies showed that treatment of fibroblasts with viral product-containing exosomes promoted the characteristics of cancer-associated fibroblasts by stimulating YAP1 signaling and the production of the immunosuppressive cytokines IL8, CCL2, and IL6. Inhibition of YAP1 activation markedly reversed these exosome-mediated protumoral effects, resulting in reduced contractility, inactivation of YAP1 signaling, and decreased production of immunosuppressive cytokines in fibroblasts. Furthermore, fibroblasts stimulated with these viral product-containing exosomes promoted NPC resistance to T cell-mediated cytotoxicity within tumor spheroids. In NPC tissues, a significant negative correlation was found between YAP1/FAPα and the density of CD8a+ T lymphocytes with a granzyme B signature.

Conclusion

EBV orchestrates interactions with the host and surrounding stroma by stimulating the functions of YAP1 and FAPα in fibroblasts through exosome cargos to create a more immunosuppressive, proinvasive microenvironment.

The cellular and molecular mediators of metastasis to the lung

Organ-specific metastasis to secondary organs is dependent on the formation of a supportive pre-metastatic niche. This tissue-specific microenvironmental response is thought to be mediated by mutational and epigenetic changes to primary tumour cells resulting in altered cross-talk between cell types. This response is augmented through the release of tumour and stromal signalling mediators including cytokines, chemokines, exosomes and growth factors. Although researchers have elucidated some of the cancer-promoting features that are bespoke to organotropic metastasis to the lungs, it remains unclear if these are organ-specific or generic between organs. Understanding the mechanisms that mediate the metastasis-promoting synergy between the host microenvironment, immunity, and pulmonary structures may elucidate predictive, prognostic and therapeutic markers that could be targeted to reduce the metastatic burden of disease. Herein, we give an updated summary of the known cellular and molecular mechanisms that contribute to the formation of the lung pre-metastatic niche and tissue-specific metastasis.

Exosomal miRNAs and lncRNAs: The Modulator Keys of Cancer-Associated Fibroblasts in the Genesis and Progression of Malignant Neoplasms

The tumor microenvironment is made up of a universe of molecular and cellular components that promote or inhibit the development of neoplasms. Among the molecular elements are cytokines, metalloproteinases, proteins, mitochondrial DNA, and nucleic acids, within which the ncRNAs: miRNAs and lncRNAs stand out due to their direct modulating effects on the genesis and progression of various cancers. Regarding cellular elements, the solid tumor microenvironment is made up of tumor cells, healthy adjacent epithelial cells, immune system cells, endothelial cells, and stromal cells, such as cancer-associated fibroblasts, which are capable of generating a modulating communication network with the other components of the tumor microenvironment through, among other mechanisms, the secretion of exosomal vesicles loaded with miRNAs and lncRNAs. These ncRNAs are key pieces in developing neoplasms since they have diverse effects on cancer cells and healthy cells, favoring or negatively regulating protumoral cellular events, such as migration, invasion, proliferation, metastasis, epithelial-mesenchymal transition, and resistance to treatment. Due to the growing number of relevant evidence in recent years, this work focused on reviewing, analyzing, highlighting, and showing the current state of research on exosomal ncRNAs derived from cancer-associated fibroblasts and their effects on different neoplasms. A future perspective on using these ncRNAs as real therapeutic tools in the treatment of cancer patients is also proposed.

Metastatic colorectal cancer: Perspectives on long non-coding RNAs and promising therapeutics

Metastatic colorectal cancer (mCRC) has long been lethal despite the continuous efforts of researchers worldwide to discover and improve therapeutic regimens. Thanks to the emergence of long non-coding RNAs (lncRNAs), which has strongly reshaped our inherent perspectives on the pathophysiological patterns of disease, research in the field has been reinvigorated. Here, we focus on current understanding of the modes of action of lncRNAs, and review their regulatory roles in metastatic colorectal cancer, and discuss correlated potential lncRNA-based therapeutics. All of the discussed studies share clear and promising perspectives on future diagnostic and therapeutic remedies for metastatic colorectal cancer.

Cancer: a mirrored room between tumor bulk and tumor microenvironment

It has been well documented that the tumor microenvironment (TME) plays a key role in the promotion of drug resistance, the support of tumor progression, invasiveness, metastasis, and even the maintenance of a cancer stem-like phenotype. Here, we reviewed TME formation presenting it as a reflection of a tumor’s own organization during the different stages of tumor development. Interestingly, functionally different groups of stromal cells seem to have specific spatial distributions within the TME that change as the tumor evolves into advanced stage progression which correlates with the fact that cancer stem-like cells (CSCs) are located in the edges of solid tumor masses in advanced tumors.

We also focus on the continuos feedback that is established between a tumor and its surroundings. The “talk” between tumor mass cells and TME stromal cells, marks the evolution of both interlocuting cell types. For instance, the metabolic and functional transformations that stromal cells undergo due to tumor corrupting activity.

Moreover, the molecular basis of metastatic spread is also approached, making special emphasis on the site-specific pre-metastatic niche formation as another reflection of the primary tumor molecular signature.

Finally, several therapeutic approaches targeting primary TME and pre-metastatic niche are suggested. For instance, a systematic analysis of the TME just adjacent to the tumor mass to establish the proportion of myofibroblasts-like cancer-associated fibroblasts (CAFs) which may in turn correspond to stemness and metastases-promotion. Or the implementation of “re-education” therapies consisting of switching tumor-supportive stromal cells into tumor-suppressive ones. In summary, to improve our clinical management of cancer, it is crucial to understand and learn how to manage the close interaction between TME and metastasis.

Cancer-associated fibroblasts-mediated ATF4 expression promotes malignancy and gemcitabine resistance in pancreatic cancer via the TGF-β1/SMAD2/3 pathway and ABCC1 transactivation

Cancer-associated fibroblasts (CAFs) contribute to malignant progression and chemoresistance in pancreatic ductal adenocarcinoma (PDAC). However, little is known about the underlying mechanism. In this study, we investigated the potential role and mechanisms of activating transcription factor 4 (ATF4) in CAFs-induced malignancy and gemcitabine resistance. We demonstrated that ATF4 is overexpressed in PDAC and associated with a poor prognosis. Silencing ATF4 expression decreased proliferation, colony formation, migration, gemcitabine sensitivity, and sphere formation. Subsequently, we revealed that CAFs secrete TGF-β1 to upregulate the expression of ATF4 in PDAC cells via the SMAD2/3 pathway and induce cancer progression, cancer stemness, and gemcitabine resistance. Furthermore, we demonstrated that ATF4 directly binds to the ABCC1 promoter region to activate transcription. In summary, these data demonstrate that CAFs contribute to malignancy and gemcitabine resistance in PDAC by upregulating the expression of ATF4 via the TGF-β1/SMAD2/3 axis and highlight that ATF4 is an attractive therapeutic target for combating gemcitabine resistance in PDAC.

Cancer-associated fibroblasts (CAFs) in thyroid papillary carcinoma: molecular networks and interactions

In 1989, Stephen Paget proposed the 'seed and soil' theory of cancer metastasis. This theory has led to previous researchers focusing on the role of a tumour as a cancer seed and antiangiogenesis agents as cancer soil fumigant; for the latter to be effective, it is important for them to be able to distinguish cancer cells from stromal cells. However, antiangiogenesis agents have not produced dramatic survival benefits in vivo. This may be related to their inability to destroy the supporting stroma that promote cancer cell growth. Therefore, in order to effectively arrest cancer cell growth for therapeutic purposes, a paradigm shift is required in our fundamental approach to decipher the molecular events and networks in the stromal environment that cancer cells can thrive and proliferate. The pathogenesis of cancer is a multidimensional process of pathological molecular and cellular pathways, influencing different stromal properties and achieving a mutually negotiated crosstalk between cancer cells and stromal cells. This review summarises the clinical presentation of current knowledge of classical papillary thyroid carcinoma (PTC), emerging molecular diagnostics and future directions of classical PTC research.

Her2-Targeted Multifunctional Nano-Theranostic Platform Mediates Tumor Microenvironment Remodeling and Immune Activation for Breast Cancer Treatment

Purpose

The treatment of breast cancer is often ineffective due to the protection of the tumor microenvironment and the low immunogenicity of tumor cells, leading to a poor therapeutic effect. In this study, we designed a nano-theranostic platform for these obstacles: a photothermal effect mediated by a gold shell could remodel the tumor microenvironment by decreasing cancer-associated fibroblasts (CAFs) and promote the release of doxorubicin (DOX) from nanoparticles. In addition, it could realize photoacoustic (PA)/MRI dual-model imaging for diagnose breast cancer and targeted identification of Her2-positive breast cancer.

Methods

Her2-DOX-superparamagnetic iron oxide nanoparticles (SPIOs)@Poly (D, L-lactide-co-glycolide) acid (PLGA)@Au nanoparticles (Her2-DSG NPs) were prepared based on a single emulsion oil-in-water (O/W) solvent evaporation method, gold seed growing method, and carbon diimide method. The size distribution, morphology, PA/MRI imaging, drug loading capacity, and drug release were investigated. Cytotoxicity, antitumor effect, cellular uptake, immunogenic cell death (ICD) effect, and targeted performance on human Her2-positive BT474 cell line were investigated in vitro. BT474/Adr cells were constructed and the antitumor effect of NPs on it was evaluated in vitro. Moreover, chemical-photothermal therapy effect, PA/MRI dual-model imaging, ICD effect induced by NPs, and tumor microenvironment remodeling in human BT474 breast cancer nude mice model were also investigated.

Results

Nanoparticles were spherical, uniform in size and covered with a gold shell. NPs had a photothermal effect, and can realize photothermal-controlled drug release in vitro. Chemical-photothermal therapy had a good antitumor effect on BT474/Adr cells and on BT474 cells in vitro. The targeting evaluation in vitro showed that Her2-DSG NPs could actively target and identify Her2-positive tumor cells. The PA/MRI imaging was successfully validated in vitro/vivo. Similarly, NPs could enhance the ICD effect in vitro/vivo, which could activate an immune response. Immunofluorescence results also proved that photothermal effect could decrease CAFs to remodel the tumor microenvironment and enhance the accessibility of NPs to tumor cells. According to the toxicity results, targeted drug delivery combined with photothermal-responsive drug release proved that NPs had good biosafety in vivo. Chemical-photothermal therapy of Her2-targeted NPs has a good antitumor effect in the BT474 nude mice model.

Conclusion

Our study showed that chemical-photothermal therapy combined with tumor microenvironment remodeling and immune activation based on the Her2-DSG NPs we developed are very promising for Her2-positive breast cancer.

Autophagy in fibroblasts induced by cigarette smoke extract promotes invasion in lung cancer cells

We investigated the effects of cigarette smoke extract (CSE) on lung fibroblasts and found that the invasiveness of lung cancer cells was facilitated by the conditioned medium from CSE-treated fibroblasts. CSE induced autophagy in fibroblasts and increased the expression of autophagy-related proteins, including optineurin and Ras-related protein Rab1B. Afterward, the fibroblasts produced high levels of interleukin-8 (IL-8), which promoted cancer cell invasion. The inhibition of either optineurin or Rab1B abrogated a rise in microtubule-associated protein 1 light chain 3 β and a decrease in p62 protein, as well as the production of IL-8, in CSE-treated fibroblasts. A three-dimensional invasion assay using cancer cell spheroids revealed that the invasion of cancer cells alone and the fibroblast-led cancer cell invasion were both enhanced by the conditioned media from CSE-treated fibroblasts. These results suggest that cigarette smoke may induce autophagy and IL-8 secretion in lung fibroblasts and modify the microenvironment to favor invasion of lung cancer cells.

Micro-strains in the extracellular matrix induce angiogenesis

An improved understanding of biomechanical factors that control tumor development, including angiogenesis, could explain why few of the promising treatment strategies discovered via in vitro models translate well into in vivo or clinical studies. The ability to manipulate and in real-time study the multiple independent biomechanical properties on cellular activity has been limited, primarily due to limitations in traditional in vitro platforms or the inability to manipulate such factors in vivo. We present a novel microfluidic platform that mimics the vascularized tumor microenvironment with independent control of interstitial flow and mechanical strain. The microtissue platform design isolates mechanically-stimulated angiogenesis in the tumor microenvironment, by manipulating interstitial flow to eliminate soluble factors that could drive blood vessel growth. Our studies demonstrate that enhanced mechanical strain induced by cancer-associated fibroblasts (CAFs) promotes angiogenesis in microvasculature models, even when preventing diffusion of soluble factors to the growing vasculature. Moreover, small but significant decreases in micro-strains induced by inhibited CAFs were sufficient to reduce angiogenesis. Ultimately, we believe this platform represents a significant advancement in the ability to investigate biomechanical signals while controlling for biochemical signals, with a potential to be utilized in fields beyond cancer research.

Research Progress and Existing Problems for Abscopal Effect

Radiation therapy plays a vital role in the treatment of tumours. In particular, the occurrence of the “abscopal effect” brings about a favourable turn for the treatment of patients with advanced metastatic malignant tumours. Because of the abscopal effect, non-irradiated areas are also treated. However, the abscopal effect occurs by chance, not through seeking. Although the abscopal effect has been studied enthusiastically, the desired result does not appear to be achieved. Moreover, its combination with immunotherapy appears to be overwhelming. There is an opinion that abscopal effect is difficult to achieve by irradiation of a single tumour, and irradiation of multiple or total lesions is advocated to increase the possibility of obtaining clinically meaningful outcomes. Obviously, there are still questions about the mechanism, condition and possibility underlying the occurrence of the abscopal effect. Can the abscopal effect truly change the future treatment strategy as the researchers expect? What are the current problems? This article reviewed the research in recent years to explore the progress and controversy surrounding the abscopal effect of radiation therapy.

Development of Natural-Based Bone Cement for a Controlled Doxorubicin-Drug Release

Osteosarcoma (OS) accounts for 60% of all global bone cancer diagnoses. Intravenous administration of Doxorubicin Hydrochloride (DOXO) is the current form of OS treatment, however, systemic delivery has been linked to the onset of DOXO induced cardiomyopathy. Biomaterials including calcium phosphate cements (CPCs) and nanoparticles (NPs) have been tested as localized drug delivery scaffolds for OS cells. However, the tumor microenvironment is critical in cancer progression, with mesenchymal stem cells (MSCs) thought to promote OS metastasis and drug resistance. The extent of MSC assisted survival of OS cells in response to DOXO delivered by CPCs is unknown. In this study, we aimed at investigating the effect of DOXO release from a new formulation of calcium phosphate-based bone cement on the viability of OS cells cocultured with hMSC in vitro. NPs made of PLGA were loaded with DOXO and incorporated in the formulated bone cement to achieve local drug release. The inclusion of PLGA-DOXO NPs into CPCs was also proven to increase the levels of cytotoxicity of U2OS cells in mono- and coculture after 24 and 72 h. Our results demonstrate that a more effective localized DOXO delivery can be achieved via the use of CPCs loaded with PLGA-DOXO NPs compared to CPCs loaded with DOXO, by an observed reduction in metabolic activity of U2OS cells in indirect coculture with hMSCs. The presence of hMSCs offer a degree of DOXO resistance in U2OS cells cultured on PLGA-DOXO NP bone cements. The consideration of the tumor microenvironment via the indirect inclusion of hMSCs in this study can act as a starting point for future direct coculture and in vivo investigations.

Extracellular Vesicles in Cancer Metastasis: Potential as Therapeutic Targets and Materials

The vast majority of cancer-related deaths are due to metastasis of the primary tumor that develops years to decades after apparent cures. However, it is difficult to effectively prevent or treat cancer metastasis. Recent studies have shown that communication between cancer cells and surrounding cells enables cancer progression and metastasis. The comprehensive term "extracellular vesicles" (EVs) describes lipid bilayer vesicles that are secreted to outside cells; EVs are well-established mediators of cell-to-cell communication. EVs participate in cancer progression and metastasis by transferring bioactive molecules, such as proteins and RNAs, including microRNAs (miRNAs), between cancer and various cells in local and distant microenvironments. Clinically, EVs functioning as diagnostic biomarkers, therapeutic targets, or even as anticancer drug-delivery vehicles have been emphasized as a result of their unique biological and pathophysiological characteristics. The potential therapeutic effects of EVs in cancer treatment are rapidly emerging and represent a new and important area of research. This review focuses on the therapeutic potential of EVs and discusses their utility for the inhibition of cancer progression, including metastasis.

Research progress of tumor microenvironment and tumor-associated macrophages

Cancer is a health issue causing utmost concern and continuing to be one of the leading causes of mortality worldwide. Effective tumor eradication methods that will improve the prognosis and prolong human life are an important topic in modern medicine. Increasing amounts of evidence indicate that the tumor microenvironment plays a significant role in tumor development and migration. Macrophages are important immune cells that commonly infiltrate the tumor microenvironment. Several studies found that macrophages play different roles in the process of cancer development. This article focuses on the tumor microenvironment and the generation, classification, and function of tumor-associated macrophages as well as their significance for tumor immunotherapy and other aspects, it summarizes nearly 10 years of tumor microenvironment and tumor-associated macrophage research, providing a novel insight for tumor immunotherapy.

Altered expression of fibroblast activation protein-α (FAP) in colorectal adenoma-carcinoma sequence and in lymph node and liver metastases

Colorectal cancer (CRC) is a major health problem in elderly people because of its high incidence and high mortality rate. Despite early screening programs, more than half of CRC patients are diagnosed at advanced stages. Fibroblast activation protein-α (FAP) expression in cancer-associated fibroblasts (CAFs) has been associated with a higher risk of metastases and poor survival. Here, we have analyzed the immunohistochemical expression of FAP in 41 adenoma-carcinoma sequences. In addition, FAP expression was analyzed individually and in combination with β-catenin (BCAT), CD44 and Cyclin-D1 expression in primary tumors and in their corresponding lymph node and liver metastases (n=294). Finally, soluble FAP (sFAP) levels in plasma from CRC patients (n=127) were also analyzed by ELISA. FAP was expressed only in CRC tissue and its expression level was found to be higher in tumors exhibiting deeper local invasion and poorer cancer cell differentiation. FAP and concomitant nuclear BCAT expression in cancer cells at the infiltrating front of primary tumors and in lymph node metastases was independently associated with 5- and 10-year cancer specific and disease-free survival. Moreover, lower sFAP levels correlated with poorer survival. These findings support the potential importance of FAP as a biomarker of CRC development and progression.

Relevance of CTC Clusters in Breast Cancer Metastasis

Metastasis is the major cause of mortality in patients with breast cancer; however, the mechanisms of tumor cell dissemination and metastasis formation are not well established yet. The study of circulating tumour cells (CTCs), the metastatic precursors of distant disease, may help in this search. CTCs can be found in the blood of cancer patients as single cells or as tumor cell aggregates, known as CTC clusters. CTC clusters have differential biological features such as an enhanced survival and metastatic potential, and they hold great promises for the evaluation of prognosis, diagnosis and therapy of the metastatic cancer. The analysis of CTC clusters offers new insights into the mechanism of metastasis and can guide towards the development of new diagnostic and therapeutic strategies to suppress cancer metastasis. This has become possible thanks to the development of improved technologies for detection of CTCs and CTC clusters. However, more efficient methods are needed in order to address important questions regarding the metastatic potential of CTC and future clinical applications. In this chapter, we explore the current knowledge on the role of CTC clusters in breast cancer metastasis, their origin, metastatic advantages and clinical importance.

TGF-β-Induced Endothelial to Mesenchymal Transition in Disease and Tissue Engineering

Endothelial to mesenchymal transition (EndMT) is a complex biological process that gives rise to cells with multipotent potential. EndMT is essential for the formation of the cardiovascular system during embryonic development. Emerging results link EndMT to the postnatal onset and progression of fibrotic diseases and cancer. Moreover, recent reports have emphasized the potential for EndMT in tissue engineering and regenerative applications by regulating the differentiation status of cells. Transforming growth factor β (TGF-β) engages in many important physiological processes and is a potent inducer of EndMT. In this review, we first summarize the mechanisms of the TGF-β signaling pathway as it relates to EndMT. Thereafter, we discuss the pivotal role of TGF-β-induced EndMT in the development of cardiovascular diseases, fibrosis, and cancer, as well as the potential application of TGF-β-induced EndMT in tissue engineering.

Matrix Metalloproteinases' Role in Tumor Microenvironment

Cancer cells evolve in the tumor microenvironment (TME) by the acquisition of characteristics that allow them to initiate their passage through a series of events that constitute the metastatic cascade. For this purpose, tumor cells maintain a crosstalk with TME non-neoplastic cells transforming them into their allies. "Corrupted" cells such as cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and tumor-associated neutrophils (TANs) as well as neoplastic cells express and secrete matrix metalloproteinases (MMPs). Moreover, TME metabolic conditions such as hypoxia and acidification induce MMPs' synthesis in both cancer and stromal cells. MMPs' participation in TME consists in promoting events, for example, epithelial-mesenchymal transition (EMT), apoptosis resistance, angiogenesis, and lymphangiogenesis. MMPs also facilitate tumor cell migration through the basement membrane (BM) and extracellular matrix (ECM). The aim of the present chapter is to discuss MMPs' contribution to the evolution of cancer cells, their cellular origin, and their influence in the main processes that take place in the TME.

The tumor microenvironment and radiotherapy response; a central role for cancer-associated fibroblasts

Tumor growth is not only dictated by events involving tumor cells, but also by the environment they reside in, the so-called tumor microenvironment (TME). In the TME, cancer-associated fibroblasts (CAFs) are often the predominant cell type. CAFs were long considered to be of limited importance in the TME, but are now recognized for their pivotal role in cancer progression. Recently, it has become evident that different subsets of CAFs exist, with certain CAF subtypes having protumorigenic properties, whereas others show more antitumorigenic characteristics. Currently, the intricate interaction between the different subsets of CAFs with tumor cells, but also with immune cells that reside in the TME, is still poorly understood. This crosstalk of CAFs with tumor and immune cells in the TME largely dictates how a tumor responds to therapy and whether the tumor will eventually be eliminated, stay dormant or will progress and metastasize. Radiotherapy (RT) is a widely used and mostly very effective local cancer treatment, but CAFs are remarkably RT resistant. Although radiation does cause persistent DNA damage, CAFs do not die upon clinically applied doses of RT, but rather become senescent. Through the secretion of cytokines and growth factors they have been implicated in the induction of tumor radioresistance and recruitment of specific immune cells to the TME, thereby affecting local immune responses. In this review we will discuss the versatile role of CAFs in the TME and their influence on RT response.

Are Synapse-Like Structures a Possible Way for Crosstalk of Cancer with Its Microenvironment?

The failure of therapies directed at targets within cancer cells highlight the necessity for a paradigm change in cancer therapy. The attention of researchers has shifted towards the disruption of cancer cell interactions with the tumor microenvironment. A typical example of such a disruption is the immune checkpoint cancer therapy that disrupts interactions between the immune and the cancer cells. The interaction of cancer antigens with T cells occurs in the immunological synapses. This is characterized by several special features, i.e., the proximity of the immune cells and their target cells, strong intercellular adhesion, and secretion of signaling cytokines into the intercellular cleft. Earlier, we hypothesized that the cancer-associated fibroblasts interacting with cancer cells through a synapse-like adhesion might play an important role in cancer tumors. Studies of the interactions between cancer cells and cancer-associated fibroblasts showed that their clusterization on the membrane surface determined their strength and specificity. The hundreds of interacting pairs are involved in the binding that may indicate the formation of synapse-like structures. These interactions may be responsible for successful metastasis of cancer cells, and their identification and disruption may open new therapeutic possibilities.

The life cycle of cancer-associated fibroblasts within the tumour stroma and its importance in disease outcome

The tumour microenvironment (TME) determines vital aspects of tumour development, such as tumour growth, metastases and response to therapy. Cancer-associated fibroblasts (CAFs) are abundant and extremely influential in this process and interact with cellular and matrix TME constituents such as endothelial and immune cells and collagens, fibronectin and elastin, respectively. However, CAFs are also the recipients of signals—both chemical and physical—that are generated by the TME, and their phenotype effectively evolves alongside the tumour mass during tumour progression. Amid a rising clinical interest in CAFs as a crucial force for disease progression, this review aims to contextualise the CAF phenotype using the chronological framework of the CAF life cycle within the evolving tumour stroma, ranging from quiescent fibroblasts to highly proliferative and secretory CAFs. The emergence, properties and clinical implications of CAF activation are discussed, as well as research strategies used to characterise CAFs and current clinical efforts to alter CAF function as a therapeutic strategy.

Extracellular vesicles of carcinoma-associated fibroblasts creates a pre-metastatic niche in the lung through activating fibroblasts

Objectives

Carcinoma-associated fibroblasts (CAFs) have been known to promote cancer progression by modifying the primary tumor microenvironment. We aimed to elucidate the intercellular communication between CAFs and secondary organs in salivary adenoid cystic carcinoma (SACC) metastasis.

Methods

Pre-metastatic and metastatic animal models of SACC were established using extracellular vesicles (EVs) from CAFs and SACC cells. Lung fibroblasts (LFs) were treated with EVs and their transcriptomic alterations were identified by RNA sequencing. ITRAQ were performed to analyze EV cargos. TC I-15 was used to inhibit EV uptake by LFs and SACC lung metastasis in vivo.

Results

Here, we show that CAF EVs induced lung pre-metastatic niche formation in mice and consequently increased SACC lung metastasis. The pre-metastatic niche induced by CAF EVs was different from that induced by SACC EVs. CAF EVs presented a great ability for matrix remodeling and periostin is a potential biomarker characterizing the CAF EV-induced pre-metastatic niche. We found that lung fibroblast activation promoted by CAF EVs was a critical event at the pre-metastatic niche. Integrin α2β1 mediated CAF EV uptake by lung fibroblasts, and its blockage by TC I-15 prevented lung pre-metastatic niche formation and subsequent metastasis. Plasma EV integrin β1 was considerably upregulated in the mice bearing xenografts with high risk of lung metastasis.

Conclusions

We demonstrated that CAF EVs participated in the pre-metastatic niche formation in the lung. Plasma EV integrin β1 might be a promising biomarker to predict SACC metastasis at an early stage. An integrated strategy targeting both tumor and stromal cells is necessary to prevent SACC metastasis.

HIC-5 in cancer-associated fibroblasts contributes to esophageal squamous cell carcinoma progression

Esophageal squamous cell carcinoma (ESCC) remains one of the most common malignancies in China and has a high metastasis rate and poor prognosis. Cancer-associated fibroblasts (CAFs), a prominent component of the tumor microenvironment, can affect tumor progression and metastasis, but the underlying mechanism remains unclear. There are no studies that explore the role of hydrogen peroxide-inducible clone 5 (HIC-5) in ESCC or compare the role of HIC-5 in CAFs and adjacent noncancerous normal fibroblasts (NFs). In this study, we isolated primary CAFs and NFs from ESCC patients. HIC-5 was highly expressed in CAFs from the tumor stroma of human ESCC patients. HIC-5 knockdown in CAFs inhibited the migration and invasion of ESCC cells in vitro. Supernatant CCL2 levels of CAFs were significantly higher after TGF-β stimulation and lower after knocking down HIC-5 expression, independent of TGF-β treatment. HIC-5 knockdown in CAFs led xenograft tumors derived from ESCC cells mixed with CAFs to present more regular morphology, express higher CDH1, and lower CCL2. Further RNA-seq data showed that HIC-5 has distinct biological functions in CAFs vs. NFs, especially in cell movement and the Rho GTPase signaling kinase pathway, which was verified by wound-healing assays and western blotting. An ESCC tissue microarray revealed that increased HIC-5 expression in the tumor stroma was associated with positive lymph node metastasis and a higher TNM stage. In summary, we identified that stromal HIC-5 was a predictive risk factor for lymph node metastasis in human ESCC and that CAF-derived HIC-5 regulated ESCC cell migration and invasion by regulating cytokines and modifying the ECM.

Conditioned medium from asbestos-exposed fibroblasts affects proliferation and invasion of lung cancer cell lines

The importance of the role of fibroblasts in cancer microenvironment is well-recognized. However, the relationship between fibroblasts and asbestos-induced lung cancer remains underexplored. To investigate the effect of the asbestos-related microenvironment on lung cancer progression, lung cancer cells (NCI-H358, Calu-3, and A549) were cultured in media derived from IMR-90 lung fibroblasts exposed to 50 mg/L asbestos (chrysotile, amosite, and crocidolite) for 24 h. The kinetics and migration of lung cancer cells in the presence of asbestos-exposed lung fibroblast media were monitored using a real-time cell analysis system. Proliferation and migration of A549 cells increased in the presence of media derived from asbestos-exposed lung fibroblasts than in the presence of media derived from normal lung fibroblasts. We observed no increase in proliferation and migration in lung cancer cells cultured in asbestos-exposed lung cancer cell medium. In contrast, increased proliferation and migration in lung cancer cells exposed to media from asbestos-exposed lung fibroblasts was observed for all types of asbestos. Media derived from lung fibroblasts exposed to other stressors, such as hydrogen peroxide and UV radiation didn't show as similar effect as asbestos exposure. An enzyme-linked immunosorbent assay (ELISA)-based cytokine array identified interleukin (IL)-6 and IL-8, which show pleiotropic regulatory effects on lung cancer cells, to be specifically produced in higher amounts by the three types of asbestos-exposed lung fibroblasts than normal lung fibroblasts. Thus, the present study demonstrated that interaction of lung fibroblasts with asbestos may support the growth and metastasis of lung cancer cells and that chrysotile exposure can lead to lung cancer similar to that caused by amphibole asbestos (amosite and crocidolite).

Impact of Cancer-Associated Fibroblast on the Radiation-Response of Solid Xenograft Tumors

Increasing evidence indicates that the heterogeneous tumor stroma supports therapy resistance at multiple levels. Fibroblasts, particularly cancer-associated fibroblasts (CAFs) are critical components of the tumor stroma. However, the impact of CAFs on the outcome of radiotherapy (RT) is poorly understood. Here, we investigated if and how fibroblasts/CAFs modulate the radiation response of malignant tumors by altering cancer cell radiosensitivity or radioresistance in vitro and in vivo. The influence of fibroblasts on cancer cell proliferation, cell death induction and long-term survival after RT was studied using different sets of fibroblasts and cancer cells in an indirect co-culture (2D) system to analyse potential paracrine interactions or a 3D model to study direct interactions. Paracrine signals from embryonic NIH-3T3 fibroblasts promoted MPR31.4 prostate and Py8119 breast cancer cell proliferation. Indirect co-culture with L929 skin fibroblasts induced higher levels of apoptosis in irradiated MPR31.4 cells, while they promoted proliferation of irradiated Py8119 cells. In addition, NIH-3T3 fibroblasts promoted long-term clonogenic survival of both tumor cell types upon irradiation in the 3D co-culture system when compared to non-irradiated controls. Also in vivo, co-implantation of cancer cells and fibroblasts resulted in different effects depending on the respective cell combinations used: co-implantation of MPR31.4 cells with NIH-3T3 fibroblasts or of Py8119 cells with L929 fibroblasts led to increased tumor growth and reduced radiation-induced tumor growth delay when compared to the respective tumors without co-implanted fibroblasts. Taken together, the impact of fibroblasts on cancer cell behavior and radiation sensitivity largely depended on the respective cell types used as they either exerted a pro-tumorigenic and radioresistance-promoting effect, an anti-tumorigenic effect, or no effect. We conclude that the plasticity of fibroblasts allows for such a broad spectrum of activities by the same fibroblast and that this plasticity is at least in part mediated by cancer cell-induced fibroblast activation toward CAFs.

Pancreatic (pro)enzymes treatment suppresses BXPC-3 pancreatic Cancer Stem Cell subpopulation and impairs tumour engrafting

Cancer stem cells (CSCs) subpopulation within the tumour is responsible for metastasis and cancer relapse. Here we investigate in vitro and in vivo the effects of a pancreatic (pro)enzyme mixture composed of Chymotrypsinogen and Trypsinogen (PRP) on CSCs derived from a human pancreatic cell line, BxPC3. Exposure of pancreatic CSCs spheres to PRP resulted in a significant decrease of ALDEFLUOR and specific pancreatic CSC markers (CD 326, CD 44 and CxCR4) signal tested by flow cytometry, further CSCs markers expression was also analyzed by western and immunofluorescence assays. PRP also inhibits primary and secondary sphere formation. Three RT² Profiler PCR Arrays were used to study gene expression regulation after PRP treatment and resulted in, (i) epithelial-mesenchymal transition (EMT) inhibition; (ii) CSCs related genes suppression; (iii) enhanced expression of tumour suppressor genes; (iv) downregulation of migration and metastasis genes and (v) regulation of MAP Kinase Signalling Pathway. Finally, in vivo anti-tumor xenograft studies demonstrated high anti-tumour efficacy of PRP against tumours induced by BxPC3 human pancreatic CSCs. PRP impaired engrafting of pancreatic CSC’s tumours in nude mice and displayed an antigrowth effect toward initiated xenografts. We concluded that (pro)enzymes treatment is a valuable strategy to suppress the CSC population in solid pancreatic tumours.

Cancer-associated fibroblasts-heroes or villains?

Cancer-associated fibroblasts (CAFs) were originally presumed to represent a homogeneous population uniformly driving tumorigenesis, united by their morphology and peritumoural location. Our understanding of CAFs has since been shaped by sophisticated in vitro and in vivo experiments, pathological association and, more recently, ablation, and it is now widely appreciated that CAFs form a group of highly heterogeneous cells with no single overarching marker. Studies have demonstrated that the CAF population contains different subtypes based on the expression of marker proteins with the capacity to promote or inhibit cancer, with their biological role as accomplices or adversaries dependent on many factors, including the cancer stage. So, while CAFs have been endlessly shown to promote the growth, survival and spread of tumours via improvements in functionality and an altered secretome, they are also capable of retarding tumorigenesis via largely unknown mechanisms. It is important to reconcile these disparate results so that the functions of, or factors produced by, tumour-promoting subtypes can be specifically targeted to improve cancer patient outcomes. This review will dissect out CAF complexity and CAF-directed cancer treatment strategies in order to provide a case for future, rational therapies.

Cancer-associated fibroblasts as key regulators of the breast cancer tumor microenvironment

Tumor cells exist in close proximity with non-malignant cells. Extensive and multilayered crosstalk between tumor cells and stromal cells tailors the tumor microenvironment (TME) to support survival, growth, and metastasis. Fibroblasts are one of the largest populations of non-malignant host cells that can be found within the TME of breast, pancreatic, and prostate tumors. Substantial scientific evidence has shown that these cancer-associated fibroblasts (CAFs) are not only associated with tumors by proximity but are also actively recruited to developing tumors where they can influence other cells of the TME as well as influencing tumor cell survival and metastasis. This review discusses the impact of CAFs on breast cancer biology and highlights their heterogeneity, origin and their role in tumor progression, ECM remodeling, therapy resistance, metastasis, and the challenges ahead of targeting CAFs to improve therapy response.

The role of extracellular vesicles from different origin in the microenvironment of head and neck cancers

The proliferation and metastasis ability of tumors are mediate by the "mutual dialogue" between cells in the tumor microenvironment (TME). Extracellular vesicles (EVs), mainly exosomes and microvesicles, play an important role in achieving intercellular substance transport and information transfer in the TME. Initially considered "garbage dumpsters" and later referred to as "signal boxes", EVs carry "cargo" (proteins, lipids, or nucleic acids) that can redirect the function of a recipient cell. Currently, the molecular mechanisms and clinical applications of EVs in head and neck cancers (HNCs) are still at an early stage and need to be further investigate. In this review, we provide insight into the TME of HNCs, classifying and summarizing EVs derived from different cell types and illuminating their complex signaling networks involved in mediating tumor proliferation, invasion and metastasis, vascular angiogenesis and cancer drug resistance. In addition, we highlight the application of EVs in HNCs, underlining the special pathological and physiological environment of HNCs. The application of tumor heterogeneous EVs in saliva and circulating blood diagnostics will provide a new perspective for the early screening, real-time monitoring and prognostic risk assessment of HNCs. Given the concept of precise and individual therapy, nanostructured EVs are equipped with superior characteristics of biocompatibility, low immunogenicity, loadability and modification ability, making these molecules one of the new strategies for HNCs treatment.

Cancer-associated fibroblasts as abettors of tumor progression at the crossroads of EMT and therapy resistance

In the last decades, the role of the microenvironment in tumor progression and therapeutic outcome has gained increasing attention. Cancer-associated fibroblasts (CAFs) have emerged as key players among stromal cells, owing to their abundance in most solid tumors and their diverse tumor-restraining/promoting roles. The interplay between tumor cells and neighboring CAFs takes place by both paracrine signals (cytokines, exosomes and metabolites) or by the multifaceted functions of the surrounding extracellular matrix. Here, we dissect the most recent identified mechanisms underlying CAF-mediated control of tumor progression and therapy resistance, which include induction of the epithelial-to-mesenchymal transition (EMT), activation of survival pathways or stemness-related programs and metabolic reprogramming in tumor cells. Importantly, the recently unveiled heterogeneity in CAFs claims tailored therapeutic efforts aimed at eradicating the specific subset facilitating tumor progression, therapy resistance and relapse. However, despite the large amount of pre-clinical data, much effort is still needed to translate CAF-directed anti-cancer strategies from the bench to the clinic.

Quantification of stromal reaction in breast carcinoma and its correlation with tumor grade and free progression survival

Cancer progression results from a complex interplay between tumor cells and the extracellular milieu. In breast carcinoma, the stromal microenvironment has been suggested to play a major role in promoting tumor growth, progression, and invasion. The stroma of 154 resected specimens of invasive breast carcinoma of no special type was quantified using a digital image analyzer. Statistical analyses were performed between the quantity of stroma and survival, as well as between progression-free survival and clinicopathological data. Levels of myofibroblastic stroma varied from 0-46%, with a median of 15.1% and a standard deviation of 7.5. The myofibroblastic stromal reaction was statistically greater in grade 2 and 3 tumors (p = 0.029). Furthermore, there was a trend for worse progression-free survival in the group of node-negative tumors with strong smooth-muscle actin stromal expression (Log rank = 0.075). The present study demonstrates that the myofibroblastic reaction of breast invasive carcinoma of no special type is not merely a passive reaction, but seems to be an integral part of the neoplastic process by facilitating tumor progression and invasion. Additional, larger studies on mechanisms of stromal change are needed and may potentially lead to novel treatments.

Cancer-associated fibroblasts promote progression and gemcitabine resistance via the SDF-1/SATB-1 pathway in pancreatic cancer

Cancer-associated fibroblasts (CAFs), a dominant component of the pancreatic tumor microenvironment, are mainly considered as promotors of malignant progression, but the underlying molecular mechanism remains unclear. Here, we show that SDF-1 secreted by CAFs stimulates malignant progression and gemcitabine resistance in pancreatic cancer, partially owing to paracrine induction of SATB-1 in pancreatic cancer cells. CAF-secreted SDF-1 upregulated the expression of SATB-1 in pancreatic cancer cells, which contributed to the maintenance of CAF properties, forming a reciprocal feedback loop. SATB-1 was verified to be overexpressed in human pancreatic cancer tissues and cell lines by quantitative real-time PCR, western blot, and immunohistochemical staining, which correlated with tumor progression and clinical prognosis in pancreatic cancer patients. We found that SATB-1 knockdown inhibited proliferation, migration, and invasion in SW1990 and PANC-1 cells in vitro, whereas overexpression of SATB-1 in Capan-2 and BxPC-3 cells had the opposite effect. Immunofluorescence staining showed that conditioned medium from SW1990 cells expressing SATB-1 maintained the local supportive function of CAFs. Furthermore, downregulation of SATB-1 inhibited tumor growth in mouse xenograft models. In addition, we found that overexpression of SATB-1 in pancreatic cancer cells participated in the process of gemcitabine resistance. Finally, we investigated the clinical correlations between SDF-1 and SATB-1 in human pancreatic cancer specimens. In summary, these findings demonstrated that the SDF-1/CXCR4/SATB-1 axis may be a potential new target of clinical interventions for pancreatic cancer patients.

Revisiting the dynamic cancer stem cell model: Importance of tumour edges

The lack of an effective treatment against cancer is not only due to its huge heterogeneity, but also to the fact that we don't have an answer to the question on how cancer originates. Among the proposed models to explain the development of cancer, the hierarchical model has been widely accepted. Nevertheless, this model fails to explain several experimental observations such as the cancer stem cells (CSCs) location inside a tumour or the differences between primary and metastatic tumours. Moreover, increasing evidence shows that the CSC phenotype is not a rigid state. Here, we present a critical review on the assumed tumour development models emphasizing the relevance of the dynamic and changing nature of cancer and the CSCs population in which the tumour microenvironment plays a crucial role and we propose a new model of tumour origin that could have an impact on new therapeutic strategies.

Syndecan-1 induction in lung microenvironment supports the establishment of breast tumor metastases

Background

Syndecan-1 (Sdc1), a cell surface heparan sulfate proteoglycan normally expressed primarily by epithelia and plasma cells, is aberrantly induced in stromal fibroblasts of breast carcinomas. Stromal fibroblast-derived Sdc1 participates in paracrine growth stimulation of breast carcinoma cells and orchestrates stromal extracellular matrix fiber alignment, thereby creating a migration and invasion-permissive microenvironment. Here, we specifically tested the role of stromal Sdc1 in metastasis.

Methods

The metastatic potential of the aggressive mouse mammary carcinoma cell lines, 4T1 and E0776, was tested in wild-type and genetically Sdc1-deficient host animals. Metastatic lesions were characterized by immunohistochemical analysis.

Results

After orthotopic inoculation, the lung metastatic burden was reduced in Sdc1−/− animals by 97% and more than 99%, in BALB/cJ and C57BL/6 animals, respectively. The difference in metastatic efficiency was maintained when the tumor cells were injected into the tail vein, suggesting that host Sdc1 exerts its effect during later stages of the metastatic cascade. Co-localization studies identified Sdc1 expression in stromal fibroblasts within the metastatic microenvironment and in normal airway epithelial cells but not in other cells (endothelial cells, α-smooth muscle actin positive cells, leucocytes, macrophages). The Ki67 proliferation index and the rate of apoptosis of the metastatic tumor cells were diminished in Sdc1−/− vs. Sdc1+/+ animals, and leucocyte density was indistinguishable. Sdc1-mediated metastatic efficiency was abolished when the animals were housed at a thermoneutral ambient temperature of 31 °C, suggesting that the host Sdc1 effect on metastasis requires mild cold stress.

Conclusions

In summary, Sdc1 is induced in the lung microenvironment after mammary carcinoma cell dissemination and promotes outgrowth of metastases in a temperature-dependent manner.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0995-x) contains supplementary material, which is available to authorized users.