Cooperation Between Cancer and Fibroblasts in Vascular Mimicry and N2-Type Neutrophil Recruitment via Notch2-Jagged1 Interaction in Lung Cancer

Unlocking the Crucial Role of Cancer-Associated Fibroblasts in Tumor Metastasis: Mechanisms and Therapeutic Prospects

BACKGROUND

Tumor metastasis represents a stepwise progression and stands as a principal determinant of unfavorable prognoses among cancer patients. Consequently, an in-depth exploration of its mechanisms holds paramount clinical significance. Cancer-associated fibroblasts (CAFs), constituting the most abundant stromal cell population within the tumor microenvironment (TME), have garnered robust evidence support for their pivotal regulatory roles in tumor metastasis.

AIM

of Review This review systematically explores the roles of CAFs at eight critical stages of tumorigenic dissemination: 1) extracellular matrix (ECM) remodeling, 2) epithelial-mesenchymal transition (EMT), 3) angiogenesis, 4) tumor metabolism, 5) perivascular migration, 6) immune escape, 7) dormancy, and 8) premetastatic niche (PMN) formation. Additionally, we provide a compendium of extant strategies aimed at targeting CAFs in cancer therapy. Key Scientific Concepts of Review This review delineates a structured framework for the interplay between CAFs and tumor metastasis while furnishing insights for the potential therapeutic developments. It contributes to a deeper understanding of cancer metastasis within the TME, facilitating the utilization of CAF-targeting therapies in anti-metastatic approaches.

Navigating tumor angiogenesis: therapeutic perspectives and myeloid cell regulation mechanism

Sustained angiogenesis stands as a hallmark of cancer. The intricate vascular tumor microenvironment fuels cancer progression and metastasis, fosters therapy resistance, and facilitates immune evasion. Therapeutic strategies targeting tumor vasculature have emerged as transformative for cancer treatment, encompassing anti-angiogenesis, vessel normalization, and endothelial reprogramming. Growing evidence suggests the dynamic regulation of tumor angiogenesis by infiltrating myeloid cells, such as macrophages, myeloid-derived suppressor cells (MDSCs), and neutrophils. Understanding these regulatory mechanisms is pivotal in paving the way for successful vasculature-targeted cancer treatments. Therapeutic interventions aimed to disrupt myeloid cell-mediated tumor angiogenesis may reshape tumor microenvironment and overcome tumor resistance to radio/chemotherapy and immunotherapy.

CAFs vs. TECs: when blood feuds fuel cancer progression, dissemination and therapeutic resistance

Neoplastic progression involves complex interactions between cancer cells and the surrounding stromal milieu, fostering microenvironments that crucially drive tumor progression and dissemination. Of these stromal constituents, cancer-associated fibroblasts (CAFs) emerge as predominant inhabitants within the tumor microenvironment (TME), actively shaping multiple facets of tumorigenesis, including cancer cell proliferation, invasiveness, and immune evasion. Notably, CAFs also orchestrate the production of pro-angiogenic factors, fueling neovascularization to sustain the metabolic demands of proliferating cancer cells. Moreover, CAFs may also directly or indirectly affect endothelial cell behavior and vascular architecture, which may impact in tumor progression and responses to anti-cancer interventions. Conversely, tumor endothelial cells (TECs) exhibit a corrupted state that has been shown to affect cancer cell growth and inflammation. Both CAFs and TECs are emerging as pivotal regulators of the TME, engaging in multifaceted biological processes that significantly impact cancer progression, dissemination, and therapeutic responses. Yet, the intricate interplay between these stromal components and the orchestrated functions of each cell type remains incompletely elucidated. In this review, we summarize the current understanding of the dynamic interrelationships between CAFs and TECs, discussing the challenges and prospects for leveraging their interactions towards therapeutic advancements in cancer.

Novel insights into Notch signaling in tumor immunity: potential targets for cancer immunotherapy

Notch signaling pathway is a highly conserved system of cell-to-cell communication that participates in various biological processes, such as stem cell maintenance, cell fate decision, cell proliferation and death during homeostasis and development. Dysregulation of Notch signaling has been associated with many aspects of cancer biology, such as maintenance of cancer stem-like cells (CSCs), cancer cell metabolism, angiogenesis and tumor immunity. Particularly, Notch signaling can regulate antitumor or pro-tumor immune cells within the tumor microenvironment (TME). Currently, Notch signaling has drawn significant attention in the therapeutic development of cancer treatment. In this review, we focus on the role of Notch signaling pathway in remodeling tumor immune microenvironment. We describe the impact of Notch signaling on the efficacy of cancer immunotherapies. Furthermore, we summarize the results of relevant preclinical and clinical trials of Notch-targeted therapeutics and discuss the challenges in their clinical application in cancer therapy. An improved understanding of the involvement of Notch signaling in tumor immunity will open the door to new options in cancer immunotherapy treatment.

Dynamic phenotypic reprogramming and chemoresistance induced by lung fibroblasts in small cell lung cancer

Small cell lung cancer (SCLC) is heterogenous in phenotype and microenvironment. Dynamic phenotypic reprogramming, leading to heterogeneity, is prevalent in SCLC, while the mechanisms remain incompletely understood. Cancer-associated fibroblasts (CAFs) possess comprehensive roles in cancer progression, while their function in phenotypic reprogramming of SCLC remain elusive. Here, we obtained transcriptome data of SCLC tissues from publicly available databases, subsequently estimated abundance of CAFs. We found CAF-abundant SCLC exhibited non-neuroendocrine (Non-NE) characteristics. Supporting this, the positive correlation of expression level of α-SMA, the CAF marker, and expression level of REST, protein typically expressed in Non-NE type SCLC, was identified in SCLC tissue arrays. Moreover, we revealed that fibroblasts inhibited NE markers expression and cell proliferation of SCLC cells in the co-culture system comprising lung fibroblasts and SCLC cells, indicating a phenotypic reprogramming from NE to Non-NE. During this process, fibroblast-derived IL-6 activated the JAK2/STAT3 signaling, upregulated c-MYC expression, and subsequently activated the NOTCH pathway, driving phenotypic reprogramming. Moreover, CAF-enriched SCLC exhibited increased immune cell infiltration, elevated expression of immune activation-related signatures, and checkpoint molecules. Our data also highlighted the chemoresistance induced by fibroblasts in SCLC cells, which was effectively reversed by JAK inhibitor. In conclusion, fibroblasts induced phenotypic reprogramming of SCLC cells from NE to Non-NE, likely contributes to inflamed immune microenvironment and chemoresistance. These findings provide novel insights into the clinical implications of CAFs in SCLC.

Bruceine D suppresses CAF-promoted TNBC metastasis under TNF-α stimulation by inhibiting Notch1-Jagged1/NF-κB(p65) signaling

BACKGROUND

Triple-negative breast cancer (TNBC) has a poor prognosis because of its high degree of malignancy and the lack of effective treatment options. Cancer-associated fibroblasts (CAFs) comprise the most abundant stromal cells in the tumor microenvironment (TME), leading to functional impairments and facilitating tumor metastasis. Excessive TNF-α further promotes cross-talk between different cells in TME. Therefore, there is an urgent need to develop more effective therapies and potential drugs that target the key factors that promote TNBC metastasis.

PURPOSE

The study aimed to evaluate the efficacy of Bruceine D, an active compound derived from the Chinese herb Brucea javanica, in inhibiting metastasis and elucidate the underlying mechanism of action in TNBC.

METHODS

In vitro, the clonogenic and the Transwell assays were used to assess the effects of Bruceine D on the proliferation, migration and invasion abilities of co-cultured CAFs and MDA-MB-231 (4T1) cells under TNF-α stimulation. TNF-α, IL-6, CXCL12, TGF-β1, and MMP9 levels in the supernatant of co-cultured cells were determined using ELISA. Western blotting was utilized to detect the expression levels of proteins related to the Notch1-Jagged1/NF-κB(p65) pathway. In vivo, the anti-tumor growth and anti-metastatic effectiveness of Bruceine D was evaluated by determining tumor weight, number of metastatic lesions, and pathological changes in the tumor and lung/liver tissues. The inhibitory effect of Bruceine D on α-SMA+ CAFs activation and CAF-medicated extracellular matrix remodeling was accessed using immunohistochemistry, immunofluorescence, and Masson and Sirius Red staining. The expression levels of Notch1, Jagged1 and p-NF-κB(p65) proteins in the primary tumors were measured by immunohistochemistry and western blotting.

RESULTS

In vitro, Bruceine D significantly inhibited the migration and invasion of co-cultured CAFs and MDA-MB-231 (4T1) cells under TNF-α stimulation, reduced the expression of tumor-promoting and matrix-remodeling cytokines secreted by CAFs, and hindered the mutual activation of Notch1-Jagged1 and NF-κB(p65). In vivo, Bruceine D significantly suppressed tumor growth and the formation of lung and liver metastases by decreasing TNF-α stimulated α-SMA+ CAFs activation, collagen fibers, MMPs production, and inhibited Notch1-Jagged1/NF-κB(p65) signaling in TNBC-bearing mice.

CONCLUSION

Bruceine D effectively weakened the "tumor-CAF-inflammation" network by inhibiting the mutual activation of Notch1-Jagged1 and NF-κB(p65) and thereby suppressed TNBC metastasis. This study first explored that Bruceine D disrupted the cross-talk between CAFs and tumor cells under TNF-α stimulation to inhibit the metastasis of TNBC, and highlighted the potential of Bruceine D as therapeutic agent for suppressing tumor metastasis.

Identifying the cancer-associated fibroblast signature to predict the prognosis and immunotherapy response in patients with lung squamous cell carcinoma

Cancer-associated fibroblasts (CAFs) are an important component of the tumor microenvironment that contribute toward the development of tumors. This study aimed to establish a new algorithm based on CAF scores to predict the prognosis and immunotherapy response in patients with lung squamous cell carcinoma (LUSC). The RNA-seq data of LUSC patients were obtained from two databases and merged after removing inter-batch differences. The CAF-related data for each sample were obtained through three different algorithms. Consistency cluster analysis was performed to obtain different CAF clusters, which were analyzed to identify differentially expressed genes. These were subjected to uniform cluster analysis to obtain different gene clusters. The Boruta algorithm was used to calculate the CAF score. Three CAF clusters and two gene clusters were obtained, all of which differed in their patient prognoses and the content of infiltrating immune cells. Patients with high CAF scores exhibited worse overall survival, higher expression of biomarkers related to immune checkpoints and immune activity, and lower tumor mutation burden. The CAF score could also predict the immunotherapy response of patients. This study suggests that the CAF score can accurately predict the prognosis and immunotherapy response of LUSC patients.

Define cancer-associated fibroblasts (CAFs) in the tumor microenvironment: new opportunities in cancer immunotherapy and advances in clinical trials

Despite centuries since the discovery and study of cancer, cancer is still a lethal and intractable health issue worldwide. Cancer-associated fibroblasts (CAFs) have gained much attention as a pivotal component of the tumor microenvironment. The versatility and sophisticated mechanisms of CAFs in facilitating cancer progression have been elucidated extensively, including promoting cancer angiogenesis and metastasis, inducing drug resistance, reshaping the extracellular matrix, and developing an immunosuppressive microenvironment. Owing to their robust tumor-promoting function, CAFs are considered a promising target for oncotherapy. However, CAFs are a highly heterogeneous group of cells. Some subpopulations exert an inhibitory role in tumor growth, which implies that CAF-targeting approaches must be more precise and individualized. This review comprehensively summarize the origin, phenotypical, and functional heterogeneity of CAFs. More importantly, we underscore advances in strategies and clinical trials to target CAF in various cancers, and we also summarize progressions of CAF in cancer immunotherapy.

[Vasculogenic mimicry]

Anti-angiogenic drugs are used as an established approach of malignant neoplasms therapy. It has been established that the development of the phenomenon of vasculogenic mimicry - a specific variant of tumor neoangiogenesis, which is formed in highly aggressive solid tumors, is associated with a decrease in the effectiveness of antitumor therapy. This review highlights the mechanisms of development of vasculogenic mimicry in malignant neoplasms, which is one of the alternative options for tumor blood supply. In the formation of vasculogenic mimicry, an important role is assigned to the tumor microenvironment, primarily tumor-associated macrophages and fibroblasts. The signaling pathways that regulate the formation of vasculogenic mimicry channels in tumors have been characterized. The prospects for a targeted impact on molecular targets that initiate and promote vasculogenic mimicry, the impact on which can increase the effectiveness of antitumor therapy, are shown. The review discusses experimental studies of the mechanisms of vasculogenic mimicry formation in malignant neoplasms and the prospects for targeted action on molecules that are components of signaling cascades involved in the development of this model of neoangiogenesis.

Single-Cell Transcriptomic Profiles of Lung Pre-Metastatic Niche Reveal Neutrophil and Lymphatic Endothelial Cell Roles in Breast Cancer

The establishment of a pre-metastatic niche (PMN) is critical for cancer metastasis. However, it remains unclear as to which phenotypes induce changes in the PMN. Single-cell transcriptomic profiling of all cells of the lung in cancer-bearing MMTV-PyVT mice revealed an increased infiltration of N2-type neutrophils and classical monocytes associated with chronic inflammation; notably, lung neutrophils isolated from mice with primary cancer exhibited similar N2-type phenotypes and expressed high levels of inflammatory and angiogenic factors. We also discovered a new cluster of Ki67-upregulated lymphatic endothelial cells (ECs) that activated several cell division-related pathways. Receptor-ligand interactions within the lung potentially mediated PMN formation; these were exemplified by the cross talk of lymphatic EC-N2-type neutrophil via S100A6. In vitro study revealed S100A6 impaired EC tight junction and increased the transendothelial migration of neutrophils. Our results highlight the molecular mechanisms that shape lung PMN and inspire preventive strategies for lung metastasis in breast cancer.

Diverse Neutrophil Functions in Cancer and Promising Neutrophil-Based Cancer Therapies

Neutrophils represent the most abundant cell type of leukocytes in the human blood and have been considered a vital player in the innate immune system and the first line of defense against invading pathogens. Recently, several studies showed that neutrophils play an active role in the immune response during cancer development. They exhibited both pro-oncogenic and anti-tumor activities under the influence of various mediators in the tumor microenvironment. Neutrophils can be divided into several subpopulations, thus contradicting the traditional concept of neutrophils as a homogeneous population with a specific function in the innate immunity and opening new horizons for cancer therapy. Despite the promising achievements in this field, a full understanding of tumor-neutrophil interplay is currently lacking. In this review, we try to summarize the current view on neutrophil heterogeneity in cancer, discuss the different communication pathways between tumors and neutrophils, and focus on the implementation of these new findings to develop promising neutrophil-based cancer therapies.

Interference in melanoma CD248 function reduces vascular mimicry and metastasis

Background

Tumor vascular mimicry is an emerging issue that affects patient survival while having no treatment at the current moment. Despite several factors implicated in vascular mimicry, little is known about stromal factors that modulate tumor microenvironment and shape malignant transformation. CD248, a type-I transmembrane protein dominantly expressed in stromal cells, mediates the interaction between cells and extracellular matrix proteins. CD248 protein expression is associated with the metastatic melanoma phenotype and promotes tumor progression in the stromal cells. This study aimed to explore the cell-autonomous effects of CD248 in melanoma vascular mimicry to aid cancer therapy development.

Methods

Loss-of-function approaches in B16F10 melanoma cells were used to study the cell-autonomous effects of CD248 on cell adhesion, migration, proliferation, and vascular mimicry. A solid-phase binding assay was performed to identify the interaction between CD248 and fibronectin. Horizontal and vertical cell migration assays were performed to analyze cell migration activity, and cell-patterned network formation on Matrigel was used to evaluate vascular mimicry activity. Recombinant CD248 (rCD248) proteins were generated, and whether rCD248 interfered with melanoma CD248 functions was evaluated in vitro. An experimental lung metastasis mouse model was used to investigate the effect of rCD248 treatment in vivo.

Results

CD248 protein expression in melanoma cells was increased by a fibroblast-conditioned medium. Knockdown of CD248 expression significantly decreased cell adhesion to fibronectin, cell migration, and vascular mimicry in melanoma cells. The lectin domain of CD248 was directly involved in the interaction between CD248 and fibronectin. Furthermore, rCD248 proteins containing its lectin domain inhibited cell adhesion to fibronectin and slowed down cell migration and vascular mimicry. Treatment with rCD248 protein could reduce pulmonary tumor burden, accompanied by a reduction in vascular mimicry in mice with melanoma lung metastasis.

Conclusion

CD248 expression in melanoma cells promotes malignant transformation by increasing the activity of cell adhesion, migration, and vascular mimicry, whereas rCD248 protein functions as a molecular decoy interfering with tumor-promoting effects of CD248 in melanoma cells.

Calculated Tumor-Associated Neutrophils Are Associated with the Tumor−Stroma Ratio and Predict a Poor Prognosis in Advanced Gastric Cancer

The tumor-associated neutrophils (TANs) value and tumor—stroma ratio (TSR) are promising prognostic parameters in the tumor microenvironment. We aimed to evaluate the prognostic role and relationship of TANs and TSR in gastric cancer. Our study comprised 157 patients who underwent gastrectomy for advanced gastric cancer. TANs were assessed by immunohistochemical staining (CD15 and CD66b) and were analyzed with an image analyzer. TANs have been known to have different functional subpopulations of N1 (anti-tumor) and N2 (pro-tumor). We developed “calculated TANs with pro-tumor function (cN2; CD15 minus CD66b)”. The TSR was evaluated using hematoxylin and eosin staining. High-grade CD15-positive, cN2 in the tumor center, and TSR were significantly related to poor disease-free survival (DFS). TSR and cN2 were independent prognostic factors for DFS (hazard ratio (HR) = 2.614; p = 0.001, HR = 3.976; p = 0.002) and cN2 in the tumor center showed a positive correlation with TSR (R = 0.179, p = 0.025). While CD66b stained both N1 and N2, CD15 detected most of N2. Combining both markers revealed a novel cN2, which was an independent marker of poor prognosis. The transformation from N1 to N2 predominantly occurred in the tumor center, and was associated with TSR.

The Good, the Bad, and the Ugly: Neutrophils, Angiogenesis, and Cancer

Angiogenesis, the formation of new blood vessels from already existing vasculature, is tightly regulated by pro- and anti-angiogenic stimuli and occurs under both physiological and pathological conditions. Tumor angiogenesis is central for tumor development, and an “angiogenic switch” could be initiated by multiple immune cells, such as neutrophils. Tumor-associated neutrophils promote tumor angiogenesis by the release of both conventional and non-conventional pro-angiogenic factors. Therefore, neutrophil-mediated tumor angiogenesis should be taken into consideration in the design of novel anti-cancer therapy. This review recapitulates the complex role of neutrophils in tumor angiogenesis and summarizes neutrophil-derived pro-angiogenic factors and mechanisms regulating angiogenic activity of tumor-associated neutrophils. Moreover, it provides up-to-date information about neutrophil-targeting therapy, complementary to anti-angiogenic treatment.

Modulation of the antitumor immune response by cancer-associated fibroblasts: mechanisms and targeting strategies to hamper their immunosuppressive functions

Cancer-associated fibroblasts (CAFs) are highly heterogeneous players that shape the tumor microenvironment and influence tumor progression, metastasis formation, and response to conventional therapies. During the past years, some CAFs subsets have also been involved in the modulation of immune cell functions, affecting the efficacy of both innate and adaptive anti-tumor immune responses. Consequently, the implication of these stromal cells in the response to immunotherapeutic strategies raised major concerns. In this review, current knowledge of CAFs origins and heterogeneity in the tumor stroma, as well as their effects on several immune cell populations that explain their immunosuppressive capabilities are summarized. The current development of therapeutic strategies for targeting this population and their implication in the field of cancer immunotherapy is also highlighted.