Insights into Fibroblast Plasticity: Cellular Communication Network 2 Is Required for Activation of Cancer-Associated Fibroblasts in a Murine Model of Melanoma

Double-sided niche regulation in skin stem cell and cancer: mechanisms and clinical applications

The niche microenvironment plays a crucial role in regulating the fate of normal skin stem cells (SSCs) and cancer stem cells (CSCs). Therapeutically targeting the CSC niche holds promise as an effective strategy; however, the dual effects of shared SSC niche signaling in CSCs have contributed to the aggressive characteristics of tumors and poor survival rates in skin cancer patients. The lack of a clear underlying mechanism has significantly hindered drug development for effective treatment. This article explores recent advances in understanding how niche factors regulate cell fate determination between skin stem cells and skin CSCs, along with their clinical implications. The dual roles of key components of the adhesive niche, including the dermo-epidermal junction and adherens junction, various cell types-especially immune cells and fibroblasts-as well as major signaling pathways such as Sonic hedgehog (Shh), Wingless-related integration site (Wnt)/β-catenin, YAP (Yes-associated protein)/TAZ (transcriptional coactivator with PDZ-binding motif), and Notch, are highlighted. Additionally, recent advances in clinical trials and drug development targeting these pathways are discussed. Overall, this review provides valuable insights into the complex interactions between skin cancer stem cells and their microenvironment, laying the groundwork for future research and clinical strategies.

CCN2: A potential contributor to gingival overgrowth

BACKGROUND

Fibrotic responses in the gingiva are characterized by their hyperproliferative nature instead of scar tissue formation. Clinically, these conditions appear as "gingival overgrowth" (GO), which can be of drug-induced or genetic origin. Despite surgical removal, GO can recur. Therefore, non-invasive methods of treating GO are required. In other fibrotic systems, the matricellular protein CCN2 represents a potential therapeutic target. However, CCN2 has been relatively understudied in the context of GO.

HIGHLIGHT

Herein, we describe what is known regarding CCN2 expression in GO and gingival fibroblasts. Specifically, CCN2 is induced by agents that promote fibrogenesis in the oral cavity, such as transforming growth factor-β, and drugs that promote GO, such as cyclosporine, nifedipine, and phenytoin.

CONCLUSION

Although little is known regarding the possible function of CCN2 in GO, given the correlation between CCN2 expression and GO recurrence, we hope that this review will inspire further research on this topic.

Smooth muscle-specific deletion of cellular communication network factor 2 causes severe aorta malformation and atherosclerosis

AIMS

Cellular communication network factor 2 (CCN2) is a matricellular protein implicated in fibrotic diseases, with ongoing clinical trials evaluating anti-CCN2-based therapies. By uncovering CCN2 as abundantly expressed in non-diseased artery tissue, this study aimed to investigate the hypothesis that CCN2 plays a pivotal role in maintaining smooth muscle cell (SMC) phenotype and protection against atherosclerosis.

METHODS AND RESULTS

Global- and SMC-specific Ccn2 knockout mouse models were employed to demonstrate that Ccn2 deficiency leads to SMC de-differentiation, medial thickening, and aorta elongation under normolipidaemic conditions. Inducing hyperlipidaemia in both models resulted in severe aorta malformation and a 17-fold increase in atherosclerosis formation. Lipid-rich lesions developed at sites of the vasculature typically protected from atherosclerosis development by laminar blood flow, covering 90% of aortas and extending to other vessels, including coronary arteries. Evaluation at earlier time points revealed medial lipid accumulation as a lesion-initiating event. Fluorescently labelled LDL injection followed by confocal microscopy showed increased LDL retention in the medial layer of Ccn2 knockout aortas, likely attributed to marked proteoglycan enrichment of the medial extracellular matrix. Analyses leveraging data from the Athero-Express study cohort indicated the relevance of CCN2 in established human lesions, as CCN2 correlated with SMC marker transcripts across 654 transcriptomically profiled carotid plaques. These findings were substantiated through in situ hybridization showing CCN2 expression predominantly in the fibrous cap.

CONCLUSION

This study identifies CCN2 as a major constituent of the normal artery wall, critical in regulating SMC differentiation and aorta integrity and possessing a protective role against atherosclerosis development. These findings underscore the need for further investigation into the potential effects of anti-CCN2-based therapies on the vasculature.

Abnormal Cellular Populations Shape Thymic Epithelial Tumor Heterogeneity and Anti-Tumor by Blocking Metabolic Interactions in Organoids

A variety of abnormal epithelial cells and immature and mature immune cells in thymic epithelial tumors (TETs) affect histopathological features, the degree of malignancy, and the response to treatment. Here, gene expression, trajectory inference, and T cell antigen receptor (TCR)-based lineage tracking are profiled in TETs at single-cell resolution. An original subpopulation of KRT14+ progenitor cells with a spindle cell phenotype is shown. An abnormal infiltration of immature T cells with a TCR hyper-rearrangement state is revealed, due to the lack of CCL21+ medullary epithelial cells. For thymic carcinoma, the novel biomarkers of MSLN, CCL20, and SLC1A5 are identified and observed an elevated expression of LAG3 and HAVCR2 in malignant tumorn-infiltrating mature T cells. These common features based on the single-cell populations may inform pathological reclassification of TETs. Meanwhile, it is found that macrophages (MACs) attract thymic tumor cells through the LGALS9-SLC1A5 axis, providing them with glutamine to elicit metabolic reprogramming. This MAC-based metabolic pattern can promote malignancy progression. Additionally, an interactive immune environment in TETs is identified that correlates with the infiltration of abnormal FOXI1+ CFTR- ionocytes. Collectively, the data broaden the knowledge of TET cellular ecosystems, providing a basis for tackling histopathological diagnosis and related treatment.

Unveiling the Dynamic Interplay between Cancer Stem Cells and the Tumor Microenvironment in Melanoma: Implications for Novel Therapeutic Strategies

Cutaneous melanoma still represents a significant health burden worldwide, being responsible for the majority of skin cancer deaths. Key advances in therapeutic strategies have significantly improved patient outcomes; however, most patients experience drug resistance and tumor relapse. Cancer stem cells (CSCs) are a small subpopulation of cells in different tumors, including melanoma, endowed with distinctive capacities of self-renewal and differentiation into bulk tumor cells. Melanoma CSCs are characterized by the expression of specific biomarkers and intracellular pathways; moreover, they play a pivotal role in tumor onset, progression and drug resistance. In recent years, great efforts have been made to dissect the molecular mechanisms underlying the protumor activities of melanoma CSCs to provide the basis for novel CSC-targeted therapies. Herein, we highlight the intricate crosstalk between melanoma CSCs and bystander cells in the tumor microenvironment (TME), including immune cells, endothelial cells and cancer-associated fibroblasts (CAFs), and its role in melanoma progression. Specifically, we discuss the peculiar capacities of melanoma CSCs to escape the host immune surveillance, to recruit immunosuppressive cells and to educate immune cells toward an immunosuppressive and protumor phenotype. We also address currently investigated CSC-targeted strategies that could pave the way for new promising therapeutic approaches for melanoma care.

The role of yes activated protein (YAP) in melanoma metastasis

Hippo was first identified in a genetic screen as a protein that suppressed proliferation and cell growth. Subsequently, it was shown that hippo acted in a so-called canonical cascade to suppress Yorkie, the Drosophila equivalent of Yes-activated protein (YAP), a mechanosensitive transcriptional cofactor that enhances the activity of the TEAD family of transcription factors. YAP promotes fibrosis, activation of cancer-associated fibroblasts, angiogenesis and cancer cell invasion. YAP activates the expression of the matricellular proteins CCN1 (cyr61) and CCN2 (ctgf), themselves mediators of fibrogenesis and oncogenesis, and coordination of matrix deposition and angiogenesis. This review discusses how therapeutically targeting YAP through YAP inhibitors verteporfin and celastrol and its downstream mediators CCN1 and CCN2 might be useful in treating melanoma.

Immune Regulation and Immune Therapy in Melanoma: Review with Emphasis on CD155 Signalling

Melanoma is commonly diagnosed in a younger population than most other solid malignancies and, in Australia and most of the world, is the leading cause of skin-cancer-related death. Melanoma is a cancer type with high immunogenicity; thus, immunotherapies are used as first-line treatment for advanced melanoma patients. Although immunotherapies are working well, not all the patients are benefitting from them. A lack of a comprehensive understanding of immune regulation in the melanoma tumour microenvironment is a major challenge of patient stratification. Overexpression of CD155 has been reported as a key factor in melanoma immune regulation for the development of therapy resistance. A more thorough understanding of the actions of current immunotherapy strategies, their effects on immune cell subsets, and the roles that CD155 plays are essential for a rational design of novel targets of anti-cancer immunotherapies. In this review, we comprehensively discuss current anti-melanoma immunotherapy strategies and the immune response contribution of different cell lineages, including tumour endothelial cells, myeloid-derived suppressor cells, cytotoxic T cells, cancer-associated fibroblast, and nature killer cells. Finally, we explore the impact of CD155 and its receptors DNAM-1, TIGIT, and CD96 on immune cells, especially in the context of the melanoma tumour microenvironment and anti-cancer immunotherapies.

Cancer-associated Fibroblast-specific Expression of the Matricellular Protein CCN1 Coordinates Neovascularization and Stroma Deposition in Melanoma Metastasis

Melanoma is the leading cause of skin cancer-related death. As prognosis of patients with melanoma remains problematic, identification of new therapeutic targets remains essential. Matricellular proteins are nonstructural extracellular matrix proteins. They are secreted into the tumor microenvironment to coordinate behavior among different cell types, yet their contribution to melanoma is underinvestigated. Examples of matricellular proteins include those comprising the CCN family. The CCN family member, CCN1, is highly proangiogenic. Herein, we show that, in human patients with melanoma, although found in several tumor cell types, CCN1 is highly expressed by a subset of cancer-associated fibroblasts (CAF) in patients with melanoma and this expression correlates positively with expression of proangiogenic genes and progressive disease/resistance to anti-PD1 checkpoint inhibitors. Consistent with these observations, in a syngeneic C57BL6 mouse model of melanoma, loss of CCN1 expression from Col1A2-Cre-, herein identified as "universal," fibroblasts, impaired metastasis of subcutaneously injected B16F10 tumor cells to lung, concomitant with disrupted neovascularization and collagen organization. Disruption of the extracellular matrix in the loss of CCN1 was validated using a novel artificial intelligence-based image analysis platform that revealed significantly decreased phenotypic fibrosis and composite morphometric collagen scores. As drug resistance is linked to matrix deposition and neoangiogenesis, these data suggest that CCN1, due to its multifaceted role, may represent a novel therapeutic target for drug-resistant melanoma. Our data further emphasize the essential role that cancer-associated, (universal) Col1A2-Cre-fibroblasts and extracellular matrix remodeling play in coordinating behavior among different cell types within the tumor microenvironment.

SIGNIFICANCE

In human patients, the expression of proangiogenic matricellular protein CCN1 in CAFs correlates positively with expression of stroma and angiogenic markers and progressive disease/resistance to checkpoint inhibitor therapy. In an animal model, loss of CCN1 from CAFs impaired metastasis of melanoma cells, neovascularization, and collagen deposition, emphasizing that CAFs coordinate cellular behavior in a tumor microenvironment and that CCN1 may be a novel target.

CD133-Dependent Activation of Phosphoinositide 3-Kinase /AKT/Mammalian Target of Rapamycin Signaling in Melanoma Progression and Drug Resistance

Melanoma frequently harbors genetic alterations in key molecules leading to the aberrant activation of PI3K and its downstream pathways. Although the role of PI3K/AKT/mTOR in melanoma progression and drug resistance is well documented, targeting the PI3K/AKT/mTOR pathway showed less efficiency in clinical trials than might have been expected, since the suppression of the PI3K/mTOR signaling pathway-induced feedback loops is mostly associated with the activation of compensatory pathways such as MAPK/MEK/ERK. Consequently, the development of intrinsic and acquired resistance can occur. As a solid tumor, melanoma is notorious for its heterogeneity. This can be expressed in the form of genetically divergent subpopulations including a small fraction of cancer stem-like cells (CSCs) and non-cancer stem cells (non-CSCs) that make the most of the tumor mass. Like other CSCs, melanoma stem-like cells (MSCs) are characterized by their unique cell surface proteins/stemness markers and aberrant signaling pathways. In addition to its function as a robust marker for stemness properties, CD133 is crucial for the maintenance of stemness properties and drug resistance. Herein, the role of CD133-dependent activation of PI3K/mTOR in the regulation of melanoma progression, drug resistance, and recurrence is reviewed.

Identification and targeting of cancer-associated fibroblast signature genes for prognosis and therapy in Cutaneous melanoma

BACKGROUND

Cancer-associated fibroblasts (CAFs) play pivotal roles in tumor invasion and metastasis. However, studies on CAF biomarkers in Cutaneous Melanoma (CM) are still scarce. This study aimed to explore the potential CAF biomarkers in CM, propose the potential therapeutic targets, and provide new insights for targeted therapy of CAFs in CM.

METHODS

We utilized weighted gene co-expression network analysis to identify CAF signature genes in CM, and conducted comprehensive bioinformatics analysis on the CAF risk score established by these genes. Moreover, single-cell sequencing analysis, spatial transcriptome analysis, and cell experiments were utilized for verifying the expression and distribution pattern of signature genes. Furthermore, molecular docking was employed to screen potential target drugs.

RESULTS

FBLN1 and COL5A1, two crucial CAF signature genes, were screened to establish the CAF risk score. Subsequently, a comprehensive bioinformatic analysis of the CAF risk score revealed that high-risk score group was significantly enriched in pathways associated with tumor progression. Besides, CAF risk score was significantly negatively correlated with clinical prognosis, immunotherapy response, and tumor mutational burden in CM patients. In addition, FBLN1 and COL5A1 were further identified as CAF-specific biomarkers in CM by multi-omics analysis and experimental validation. Eventually, based on these two targets, Mifepristone and Dexamethasone were screened as potential anti-CAFs drugs.

CONCLUSION

The findings indicated that FBLN1 and COL5A1 were the CAF signature genes in CM, which were associated with the progression, treatment, and prognosis of CM. The comprehensive exploration of CAF signature genes is expected to provide new insight for clinical CM therapy.

Back to the future: targeting the extracellular matrix to treat systemic sclerosis

Fibrosis is the excessive deposition of a stable extracellular matrix (ECM); fibrotic tissue is composed principally of highly crosslinked type I collagen and highly contractile myofibroblasts. Systemic sclerosis (SSc) is a multisystem autoimmune connective tissue disease characterized by skin and organ fibrosis. The fibrotic process has been recognized in SSc for >40 years, but drugs with demonstrable efficacy against SSc fibrosis in ameliorating the lung involvement have only recently been identified. Unfortunately, these treatments are ineffective at improving the skin score in patients with SSc. Previous clinical trials in SSc have largely focused on the cross-purposing of anti-inflammatory drugs and the use of immunosuppressive drugs from the transplantation field, which address inflammatory and/or autoimmune processes. Limited examination has taken place of specific anti-fibrotic agents developed through their ability to directly target the ECM in SSc by, for example, alleviating the persistent matrix stiffness and mechanotransduction that might be required for both the initiation and maintenance of fibrosis, including in SSc. However, because of the importance of the ECM in the SSc phenotype, attempts have now been made to identify drugs that specifically target the ECM, including some drugs that are currently under consideration for the treatment of cancer.

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

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

MacroH2A restricts inflammatory gene expression in melanoma cancer-associated fibroblasts by coordinating chromatin looping

MacroH2A has established tumour suppressive functions in melanoma and other cancers, but an unappreciated role in the tumour microenvironment. Using an autochthonous, immunocompetent mouse model of melanoma, we demonstrate that mice devoid of macroH2A variants exhibit increased tumour burden compared with wild-type counterparts. MacroH2A-deficient tumours accumulate immunosuppressive monocytes and are depleted of functional cytotoxic T cells, characteristics consistent with a compromised anti-tumour response. Single cell and spatial transcriptomics identify increased dedifferentiation along the neural crest lineage of the tumour compartment and increased frequency and activation of cancer-associated fibroblasts following macroH2A loss. Mechanistically, macroH2A-deficient cancer-associated fibroblasts display increased myeloid chemoattractant activity as a consequence of hyperinducible expression of inflammatory genes, which is enforced by increased chromatin looping of their promoters to enhancers that gain H3K27ac. In summary, we reveal a tumour suppressive role for macroH2A variants through the regulation of chromatin architecture in the tumour stroma with potential implications for human melanoma.

Hiding in Plain Sight: Human Gingival Fibroblasts as an Essential, Yet Overlooked, Tool in Regenerative Medicine

Adult human gingival fibroblasts (HGFs), the most abundant cells in the oral cavity, are essential for maintaining oral homeostasis. Compared with other tissues, adult oral mucosal wounds heal regeneratively, without scarring. Relative to fibroblasts from other locations, HGFs are relatively refractory to myofibroblast differentiation, immunomodulatory, highly regenerative, readily obtained via minimally invasive procedures, easily and rapidly expanded in vitro, and highly responsive to growth factors and cytokines. Consequently, HGFs might be a superior, yet perhaps underappreciated, source of adult mesenchymal progenitor cells to use in tissue engineering and regeneration applications, including the treatment of fibrotic auto-immune connective tissue diseases such as scleroderma. Herein, we highlight in vitro and translational studies that have investigated the regenerative and differentiation potential of HGFs, with the objective of outlining current limitations and inspiring future research that could facilitate translating the regenerative potential of HGFs into the clinic.

Using the Bleomycin-Induced Model of Fibrosis to Study the Contribution of CCN Proteins to Scleroderma Fibrosis

Approximately 45% of the deaths in the developed world result from conditions with a fibrotic component. Although no specific, focused anti-fibrotic therapies have been approved for clinical use, a long-standing concept is that targeting CCN proteins may be useful to treat fibrosis. Herein, we summarize current data supporting the concept that targeting CCN2 may be a viable anti-fibrotic approach to treat scleroderma. Testing this hypothesis has been made possible by using a mouse model of inflammation-driven skin and lung fibrosis.

Role of Peritoneal Mesothelial Cells in the Progression of Peritoneal Metastases

Peritoneal metastatic cancer comprises a heterogeneous group of primary tumors that originate in the peritoneal cavity or metastasize into the peritoneal cavity from a different origin. Metastasis is a characteristic of end-stage disease, often indicative of a poor prognosis with limited treatment options. Peritoneal mesothelial cells (PMCs) are a thin layer of cells present on the surface of the peritoneum. They display differentiated characteristics in embryonic development and adults, representing the first cell layer encountering peritoneal tumors to affect their progression. PMCs have been traditionally considered a barrier to the intraperitoneal implantation and metastasis of tumors; however, recent studies indicate that PMCs can either inhibit or actively promote tumor progression through distinct mechanisms. This article presents a review of the role of PMCs in the progression of peritoneum implanted tumors, offering new ideas for therapeutic targets and related research.

Excessive activation of IL‑33/ST2 in cancer‑associated fibroblasts promotes invasion and metastasis in ovarian cancer

Ovarian cancer is highly prevalent and has high mortality rates due to metastasis and relapse. The cross communication between cancer-associated fibroblasts (CAFs) and cancer-associated macrophages (CAMs) in the ovarian tumor microenvironment leads to cancer cell invasion and metastasis. However, the role of overproduction of IL-33/ST2 in the CAFs of ovarian cancer is still unclear. The expression of IL-33, ST2, apoptosis-related proteins and epithelial-mesenchymal transition (EMT) markers was measured by western blotting. Primary normal fibroblasts and CAFs from ovarian cancerous tissue were isolated and cultured in vitro, and the medium was used to stimulate blood-derived monocytes. Flow cytometry analysis was used to detect the frequency of M2-like macrophages in blood-derived monocytes from patients with ovarian cancer. Cell invasion were evaluated using Transwell assays. A xenograft model was used to study tumor growth in ST2-knockout and wild-type NOD-SCID mice. The results demonstrated higher expression of IL-33 and ST2 in carcinoma tissues compared with in para-carcinoma tissues, and there was a survival improvement associated with elevated IL-33. IL-33 and culture supernatants from CAFs, rather than normal ovarian fibroblasts, led to a higher expression of M2 macrophage marker genes in human blood-derived monocytes. Invasion and migration were aggravated in COC1 cells co-cultured with CAF-induced CAMs, and the EMT marker genes were upregulated. It was reported that EMT marker genes were downregulated and tumor volumes were significantly reduced in ST2-deficient mice. Overall, the IL-33/ST2 axis in ovarian cancer might integrate IL-33-expressing CAFs with M2 type-like CAMs, which aggravated invasion and metastasis by promoting EMT.

The CCN axis in cancer development and progression

Since the authors first reviewed this subject in 2016 significant progress has been documented in the CCN field with advances made in the understanding of how members of the CCN family of proteins, CCN1-6, contribute to the pathogenesis and progression, positive and negative, of a larger variety of cancers. As termed matricellular proteins, and more recently the connective communication network, it has become clearer that members of the CCN family interact complexly with other proteins in the extracellular microenvironment, membrane signaling proteins, and can also operate intracellularly at the transcriptional level. In this review we expand on this earlier information providing new detailed information and insights that appropriate a much greater involvement and importance of their role in multiple aspects of cancer. Despite all the new information many more questions have been raised and intriguing results generated that warrant greater investigation. In order to permit the reader to smoothly integrate the new information we discuss all relevant CCN members in the context of cancer subtypes. We have harmonized the nomenclature with CCN numbering for easier comparisons. Finally, we summarize what new has been learned and provide a perspective on how our knowledge about CCN1-6 is being used to drive new initiatives on cancer therapeutics.

Acidic and Hypoxic Microenvironment in Melanoma: Impact of Tumour Exosomes on Disease Progression

The mechanisms of melanoma progression have been extensively studied in the last decade, and despite the diagnostic and therapeutic advancements pursued, malignant melanoma still accounts for 60% of skin cancer deaths. Therefore, research efforts are required to better define the intercellular molecular steps underlying the melanoma development. In an attempt to represent the complexity of the tumour microenvironment (TME), here we analysed the studies on melanoma in acidic and hypoxic microenvironments and the interactions with stromal and immune cells. Within TME, acidity and hypoxia force melanoma cells to adapt and to evolve into a malignant phenotype, through the cooperation of the tumour-surrounding stromal cells and the escape from the immune surveillance. The role of tumour exosomes in the intercellular crosstalk has been generally addressed, but less studied in acidic and hypoxic conditions. Thus, this review aims to summarize the role of acidic and hypoxic microenvironment in melanoma biology, as well as the role played by melanoma-derived exosomes (Mexo) under these conditions. We also present a perspective on the characteristics of acidic and hypoxic exosomes to disclose molecules, to be further considered as promising biomarkers for an early detection of the disease. An update on the use of exosomes in melanoma diagnosis, prognosis and response to treatment will be also provided and discussed.

Atractylenolide-I Sensitizes Triple-Negative Breast Cancer Cells to Paclitaxel by Blocking CTGF Expression and Fibroblast Activation

This investigation was conducted to elucidate whether atractylenolide-I (ATL-1), which is the main component of Atractylodes macrocephala Koidz, can sensitize triple-negative breast cancer (TNBC) cells to paclitaxel and investigate the possible mechanism involved. We discovered that ATL-1 could inhibit tumor cell migration and increase the sensitivity of tumor cells to paclitaxel. ATL-1 downregulated the expression and secretion of CTGF in TNBC cells. Apart from inhibiting TNBC cell migration via CTGF, ATL-1 downregulated the expression of CTGF in fibroblasts and decreased the ability of breast cancer cells to transform fibroblasts into cancer-associated fibroblasts (CAFs), which in turn increased the sensitivity of TNBC cells to paclitaxel. In a mouse model, we found that ATL-1 treatments could enhance the chemotherapeutic effect of paclitaxel on tumors and reduce tumor metastasis to the lungs and liver. Primary cultured fibroblasts derived from inoculated tumors in mice treated with ATL-1 combined with paclitaxel expressed relatively low levels of CAF markers. Collectively, our data indicate that ATL-1 can sensitize TNBC cells to paclitaxel by blocking CTGF expression and fibroblast activation and could be helpful in future research to determine the value of ATL-1 in the clinical setting.

Blisters on your fingers

Mesenchymal progenitor cells play a key role in fibrogenesis. An exciting paper was recently published showed that blister fluid from the skin patients with the autoimmune connective tissue disease scleroderma (systemic sclerosis, SSc) preferentially activated mesenchymal progenitor cells (Taki et al. in Arthritis Rheumatol 72(8):1361-1374, 2020). These data provide new and invaluable insights into the complex interactions in the connective tissue microenvironment that ultimately result in persistent, pathological fibrosis.

CCN2 (Cellular Communication Network factor 2) in the bone marrow microenvironment, normal and malignant hematopoiesis

CCN2, formerly termed Connective Tissue Growth Factor, is a protein belonging to the Cellular Communication Network (CCN)-family of secreted extracellular matrix-associated proteins. As a matricellular protein it is mainly considered to be active as a modifier of signaling activity of several different signaling pathways and as an orchestrator of their cross-talk. Furthermore, CCN2 and its fragments have been implicated in the regulation of a multitude of biological processes, including cell proliferation, differentiation, adhesion, migration, cell survival, apoptosis and the production of extracellular matrix products, as well as in more complex processes such as embryonic development, angiogenesis, chondrogenesis, osteogenesis, fibrosis, mechanotransduction and inflammation. Its function is complex and context dependent, depending on cell type, state of differentiation and microenvironmental context. CCN2 plays a role in many diseases, especially those associated with fibrosis, but has also been implicated in many different forms of cancer. In the bone marrow (BM), CCN2 is highly expressed in mesenchymal stem/stromal cells (MSCs). CCN2 is important for MSC function, supporting its proliferation, migration and differentiation. In addition, stromal CCN2 supports the maintenance and longtime survival of hematopoietic stem cells, and in the presence of interleukin 7, stimulates the differentiation of pro-B lymphocytes into pre-B lymphocytes. Overexpression of CCN2 is seen in the majority of B-acute lymphoblastic leukemias, especially in certain cytogenetic subgroups associated with poor outcome. In acute myeloid leukemia, CCN2 expression is increased in MSCs, which has been associated with leukemic engraftment in vivo. In this review, the complex function of CCN2 in the BM microenvironment and in normal as well as malignant hematopoiesis is discussed. In addition, an overview is given of data on the remaining CCN family members regarding normal and malignant hematopoiesis, having many similarities and some differences in their function.

Verteporfin inhibits the persistent fibrotic phenotype of lesional scleroderma dermal fibroblasts

Fibrosis is perpetuated by an autocrine, pro-adhesive signaling loop maintained by the synthetic and contractile abilities of myofibroblasts and the stiff, highly-crosslinked extracellular matrix. Transcriptional complexes that are exquisitely responsive to mechanotransduction include the co-activator YAP1, which regulates the expression of members of the CCN family of matricellular proteins such as CCN2 and CCN1. Although selective YAP1 inhibitors exist, the effect of these inhibitors on profibrotic gene expression in fibroblasts is largely unknown, and is the subject of our current study. Herein, we use genome-wide expression profiling, real-time polymerase chain reaction and Western blot analyses, cell migration and collagen gel contraction assays to assess the ability of a selective YAP inhibitor verteporfin (VP) to block fibrogenic activities in dermal fibroblasts from healthy individual human controls and those from isolated from fibrotic lesions of patients with diffuse cutaneous systemic sclerosis (dcSSc). In control fibroblasts, VP selectively reduced expression of fibrogenic genes and also blocked the ability of TGFbeta to induce actin stress fibers in dermal fibroblasts. VP also reduced the persistent profibrotic phenotype of dermal fibroblasts cultured from fibrotic lesions of patients with dcSSc. Our results are consistent with the notion that, in the future, YAP1 inhibitors may represent a novel, valuable method of treating fibrosis as seen in dcSSc.

A Framework of Major Tumor-Promoting Signal Transduction Pathways Implicated in Melanoma-Fibroblast Dialogue

Simple Summary

Melanoma cells reside in a complex stromal microenvironment, which is a critical component of disease onset and progression. Mesenchymal or fibroblastic cell type are the most abundant cellular element of tumor stroma. Factors secreted by melanoma cells can activate non-malignant associated fibroblasts to become melanoma associate fibroblasts (MAFs). MAFs promote tumorigenic features by remodeling the extracellular matrix, supporting tumor cells proliferation, neo-angiogenesis and drug resistance. Additionally, environmental factors may contribute to the acquisition of pro-tumorigenic phenotype of fibroblasts. Overall, in melanoma, perturbed tissue homeostasis contributes to modulation of major oncogenic intracellular signaling pathways not only in tumor cells but also in neighboring cells. Thus, targeted molecular therapies need to be considered from the reciprocal point of view of melanoma and stromal cells.

Abstract

The development of a modified stromal microenvironment in response to neoplastic onset is a common feature of many tumors including cutaneous melanoma. At all stages, melanoma cells are embedded in a complex tissue composed by extracellular matrix components and several different cell populations. Thus, melanomagenesis is not only driven by malignant melanocytes, but also by the altered communication between melanocytes and non-malignant cell populations, including fibroblasts, endothelial and immune cells. In particular, cancer-associated fibroblasts (CAFs), also referred as melanoma-associated fibroblasts (MAFs) in the case of melanoma, are the most abundant stromal cells and play a significant contextual role in melanoma initiation, progression and metastasis. As a result of dynamic intercellular molecular dialogue between tumor and the stroma, non-neoplastic cells gain specific phenotypes and functions that are pro-tumorigenic. Targeting MAFs is thus considered a promising avenue to improve melanoma therapy. Growing evidence demonstrates that aberrant regulation of oncogenic signaling is not restricted to transformed cells but also occurs in MAFs. However, in some cases, signaling pathways present opposite regulation in melanoma and surrounding area, suggesting that therapeutic strategies need to carefully consider the tumor–stroma equilibrium. In this novel review, we analyze four major signaling pathways implicated in melanomagenesis, TGF-β, MAPK, Wnt/β-catenin and Hyppo signaling, from the complementary point of view of tumor cells and the microenvironment.

Conjunction junction, what's the function? CCN proteins as targets in fibrosis and cancers

Cellular communication network (CCN) proteins are matricellular proteins that coordinate signaling among extracellular matrix, secreted proteins, and cell surface receptors. Their specific in vivo function is context-dependent, but they play profound roles in pathological conditions, such as fibrosis and cancers. Anti-CCN therapies are in clinical consideration. Only recently, however, has the function of these complex molecules begun to emerge. This review summarizes and interprets our current knowledge regarding these fascinating molecules and provides experimental evidence for their utility as therapeutic targets.

Identification of key microRNAs of plasma extracellular vesicles and their diagnostic and prognostic significance in melanoma

Melanoma is one of the most highly metastatic, aggressive and fatal malignant tumors in skin cancer. This study employs bioinformatics to identify key microRNAs and target genes (TGs) of plasma extracellular vesicles (pEVs) and their diagnostic and prognostic significance in melanoma. The gene expression microarray dataset (GSE100508) was downloaded from the Gene Expression Omnibus database. Differential analysis of miRNAs in pEVs was performed to compare melanoma samples and healthy samples. Then, TGs of the differential miRNAs (DE-miRNAs) in melanoma were selected, and differential genes were analyzed by bioinformatics (including Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment, protein–protein interaction network and prognostic analysis). A total of 55 DE-miRNAs were found, and 3,083 and 1,351 candidate TGs were diagnostically correlated with the top ten upregulated DE-miRNAs and all downregulated DE-miRNAs, respectively. Prognostic analysis results showed that high expression levels of hsa-miR-550a-3p, CDK2 and POLR2A and low expression levels of hsa-miR-150-5p in melanoma patients were associated with significantly reduced overall survival. In conclusion, bioinformatics analysis identified key miRNAs and TGs in pEVs of melanoma, which may represent potential biomarkers for the early diagnosis and treatment of this cancer.

Slow train coming: an anti-CCN2 strategy reverses a model of chronic overuse muscle fibrosis

One of the first targets proposed as an anti-fibrotic therapy was CCN2. Proof of its involvement in fibrosis was initially difficult, due to the lack of appropriate reagents and general understanding of the molecular mechanisms responsible for persistent fibrosis. As these issues have been progressively resolved over the last twenty-five years, it has become clear that CCN2 is a bone fide target for anti-fibrotic intervention. An anti-CCN2 antibody (FG-3019) is in Phase III clinical trials for idiopathic pulmonary fibrosis and pancreatic cancer, and in Phase II for Duschenne’s muscular dystrophy. An exciting paper recently published by Mary Barbe and the Popoff group has shown that FG-3019 reduces established muscle fibrosis (Barbe et al., FASEB J 34:6554–6569, 2020). Intriguingly, FG-3019 blocked the decreased expression of the anti-fibrotic protein CCN3, caused by the injury model. These important data support the notion that targeting CCN2 in the fibrotic microenvironment may reverse established fibrosis, making it the first agent currently in development to do so.

Breathe, breathe in the air: the anti-CCN2 antibody pamrevlumab (FG-3019) completes a successful phase II clinical trial for idiopathic pulmonary fibrosis

Pirfenidone and nintedanib have been approved for idiopathic pulmonary fibrosis (IPF) due to their ability to statistically slow, over a year, the rate of decline in lung forced vital capacity (FVC), neither drug has been reported to have o positive effects on high-resolution computed tomography (HRCT) of the chest, symptoms, or quality of life. Moreover, pirfenidone and nintedanib have substantial gastrointestinal tolerability issues. Overall, these data highly suggest that novel therapeutic approached are needed. CCN2 has been shown to be a mediator of fibrosis in many preclinical models. Anti-CCN2 strategies are in clinical development for IPF, A recent study by Richeldi and colleagues described the recent Phase II clinical trial for FG-3019 in IPF, and the results were highly encouraging. This commentary contextualizes and summarizes these exciting findings.