Tumor associated mast cells: biological roles and therapeutic applications

A single-cell atlas of bladder cancer unveils dynamic cellular composition and endothelial functional shifts during progression

PURPOSE

Bladder cancer (BC) is characterized by high heterogeneity, with non-muscle-invasive (NMIBC) and muscle-invasive (MIBC) stages differing significantly in clinical behavior and outcomes. The transition from NMIBC to MIBC involves extensive tumor microenvironment (TME) remodeling, particularly in endothelial cells (ECs), which drive angiogenesis and modulate immune and extracellular matrix (ECM) interactions. However, the precise roles of ECs in this progression remain poorly defined.

METHODS

Public single-cell RNA sequencing (scRNA-seq) datasets from 47 BC patients were analyzed to characterize endothelial cell heterogeneity and functional states across NMIBC and MIBC. Computational tools such as CellChat were applied to reconstruct cell-cell communication networks, focusing on pathways related to angiogenesis, immune crosstalk, and ECM remodeling.

RESULTS

Twelve major cell types were identified, with endothelial cells exhibiting distinct transcriptional profiles between NMIBC and MIBC. NMIBC-associated ECs promoted adhesion and migration through HMGB1 and CXCL12 signaling. In contrast, MIBC was enriched in an ADAM10+ endothelial subset associated with vascular remodeling and activation of Wnt signaling via CTNNB1. Key ligand-receptor interactions highlighted the dynamic roles of ECs in TME modulation during BC progression.

CONCLUSIONS

This study reveals stage-specific endothelial cell phenotypes and signaling networks in BC. The identification of an MIBC-specific ADAM10+ endothelial subset underscores its potential role in driving tumor progression and highlights opportunities for stage-adapted vascular-targeted therapies. These findings advance our understanding of BC pathogenesis and provide the foundation for novel therapeutic strategies.

Mast Cell Density in Squamous Cell Carcinoma of Skin in Dogs and Cats

The purpose of the present study was to evaluate mast cell density in squamous cell carcinoma tissues of dogs and cats to assess species differences. Skin squamous cell carcinoma tissues from dogs (n = 15: n = 10 from body sites and n = 5 nail bed specimens) and cats (n = 15, n = 10 from ears and n = 5 nasal planum specimens) were examined. Intratumoral mast cell density (IMCD), peritumoral mast cell density (PMCD) and total mast cells density (TMCD) as a sum of IMCD and PMCD were calculated from Giemsa-stained slides at high magnification in 1 mm2 using an Olympus microscope (Olympus BX41, Tokyo, Japan) equipped with a digital Olympus DP72 image camera and CellSensDimension software V1.16). Both intratumoral and peritumoral tissues of the squa.mous cell carcinoma were divided into two categories: (1) loose, well-vascularized, rich in lymphocytes and plasmocytes, macrophages and neutrophils; and (2) fibrous, with few or no lymphocytes, plasmocytes, macrophages and neutrophils (the presence of neutrophils can be associated with actinic keratosis, mechanical irritation of the tumor in some anatomical areas during scratching with teeth, but, in general, neutrophils are associated with more invasive squamous cell carcinoma). In cats, a markedly higher total number of mast cells was found, and the number was also higher in intratumoral and peritumoral tissues. A similar tendency was found in both dogs and cats-a markedly higher number of mastocytes was found in both peritumoral and intratumoral loose, well-vascularized connective tissue. Conversely, lower numbers of mast cells were found in both intratumoral and peritumoral compact fibrous tissue in both animal species.

Mitochondrial activity related genes of mast cells identify poor prognosis and metastasis of ovarian cancer

The pro-tumorigenic or anti-tumorigenic role of tumor infiltrating mast cells (TIMs) in tumors depends not only on the type of cancer and the degree of tumor progression, but also on their location in the tumor bulk. In our investigation, we employed immunohistochemistry to reveal that the mast cells (MCs) in the tumor stroma are positively correlated with metastasis of ovarian cancer (OC), but not in the tumor parenchyma. To delve deeper into the influence of different culture matrix stiffness on MCs' biological functions within the tumor parenchymal and stromal regions, we conducted a transcriptome analysis of the mouse MC line (P815) cultured in two-dimensional (2D) or three-dimensional (3D) culture system. Further research has found that the softer 3D extracellular matrix stiffness could improve the mitochondrial activity of MCs to promote proliferation by increasing the expression levels of mitochondrial activity-related genes, namely Pet100, atp5md, and Cox7a2. Furthermore, employing LASSO regression analysis, we identified that Pet100 and Cox7a2 were closely associated with the prognosis of OC patients. These two genes were subsequently employed to construct a risk score model, which revealed that the high-risk group model as one of the prognostic factors for OC patients. Additionally, the XCell algorithm analysis showed that the high-risk group displayed a broader spectrum of immune cell infiltrations. Our research revealed that TIMs in the tumor stroma could promote the metastasis of OC, and mitochondrial activity-related proteins Pet100/Cox7a2 can serve as biomarkers for prognostic evaluation of OC.

The Complex Role of Mast Cells in Head and Neck Squamous Cell Carcinoma: A Systematic Review

Background and Objectives: Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous malignancy influenced by various genetic and environmental factors. Mast cells (MCs), typically associated with allergic responses, have recently emerged as key regulators of the HNSCC tumor microenvironment (TME). This systematic review explores the role of MCs in HNSCC pathogenesis and their potential as prognostic markers and therapeutic targets. Materials and Methods: A systematic search was conducted in the PubMed, Scopus and ClinicalTrials.gov databases until 31 December 2023, using "Mast cells" AND "Head and neck squamous cell carcinoma" as search terms. Studies in English which reported on MCs and HNSCC were included. Screening, data extraction and analysis followed PRISMA guidelines. No new experiments were conducted. Results: Out of 201 articles, 52 studies met the inclusion criteria, 43 of which were published between 2020 and 2023. A total of 28821 HNSCC and 9570 non-cancerous tissue samples had been examined. MC density and activation varied among normal tissues and HNSCC. Genetic alterations associated with MCs were identified, with specific gene expressions correlating with prognosis. Prognostic gene signatures associated with MC density were established. Conclusions: MCs have arisen as multifaceted TME modulators, impacting various aspects of HNSCC development and progression. Possible site-specific or HPV-related differences in MC density and activation should be further elucidated. Despite conflicting findings on their prognostic role, MCs represent promising targets for novel therapeutic strategies, necessitating further research and clinical validation for personalized HNSCC treatment.

Characteristics of mast cell infiltration in lung adenocarcinoma and its impact on prognosis

BACKGROUND

The role of mast cells in malignancies remains unclear, and there is no clear correlation between mast cells and tumor microvessels, tumor growth, or lung adenocarcinoma (LUAD) prognosis. This study aims to explore the association between mast cell density (MCD) and intratumoral microvessel density (MVD), clinicopathological parameters, and prognosis in LUAD, by evaluating mast cell infiltration characteristics and their prognostic significance.

METHODS

This retrospective investigation involved 238 patients with LUAD undergoing complete resection. Tumor and normal lung tissue sections outside the tumor were immunohistochemically stained for MCD in the intratumoral and outside regions, respectively. CD34 polyclonal antibody was used to measure intratumoral MVD.

RESULTS

Intratumoral regions of LUAD had a higher MCD (P < 0.001) than normal lung tissue. In the intratumoral region, MCD and CD34-MVD were positively correlated (r = 0.411, P < 0.001). Intratumoral MCD correlated with sex, smoking history, tumor differentiation, pathological subtype, and tumor size. Female sex (P = 0.012), no smoking history (P = 0.002), acinar predominant type (P = 0.012), and tumor size ≤ 3 cm (P = 0.009) were associated with a higher MCD, whereas poorly differentiated (P = 0.039) and solid/micropapillary predominant types (P = 0.001) were associated with a lower MCD. Higher intratumoral MCD exhibited a marginally improved overall survival, and individuals with higher MCD infiltration ratios (intratumoral MCD/outside the MCD) had higher disease-free and overall survival rates (log-rank P < 0.001). A high MCD infiltration ratio was associated with decreased risk of tumor progression and death following complete resection.

CONCLUSION

The tumor microenvironment controls mast cell infiltration in LUAD, and patients with increased intratumoral mast cell infiltration have better prognosis.

The regulatory role and mechanism of mast cells in tumor microenvironment

Mast cells (MCs) have emerged as pivotal contributors to both the defensive immune response and immunomodulation. They also exhibit regulatory functions in modulating pathological processes across various allergic diseases. The impact of MC presence within tumor tissues has garnered considerable attention, yielding conflicting findings. While some studies propose that MCs within tumor tissues promote tumor initiation and progression, others advocate an opposing perspective. Notably, evidence emphasizes the dual role of MCs in cancer, both as promoters and suppressors, is crucial for optimizing cancer treatment strategies. These conflicting viewpoints have generated substantial controversy, underscoring the need for a comprehensive understanding of MC's role in tumor immune responses.

Clinical and biomarker analyses of sintilimab plus gemcitabine and cisplatin as first-line treatment for patients with advanced biliary tract cancer

The prognosis of biliary tract cancer (BTC) remains unsatisfactory. This single-arm, phase II clinical trial (ChiCTR2000036652) investigated the efficacy, safety, and predictive biomarkers of sintilimab plus gemcitabine and cisplatin as the first-line treatment for patients with advanced BTCs. The primary endpoint was overall survival (OS). Secondary endpoints included toxicities, progression-free survival (PFS), and objective response rate (ORR); multi-omics biomarkers were assessed as exploratory objective. Thirty patients were enrolled and received treatment, the median OS and PFS were 15.9 months and 5.1 months, the ORR was 36.7%. The most common grade 3 or 4 treatment-related adverse events were thrombocytopenia (33.3%), with no reported deaths nor unexpected safety events. Predefined biomarker analysis indicated that patients with homologous recombination repair pathway gene alterations or loss-of-function mutations in chromatin remodeling genes presented better tumor response and survival outcomes. Furthermore, transcriptome analysis revealed a markedly longer PFS and tumor response were associated with higher expression of a 3-gene effector T cell signature or an 18-gene inflamed T cell signature. Sintilimab plus gemcitabine and cisplatin meets pre-specified endpoints and displays acceptable safety profile, multiomics potential predictive biomarkers are identified and warrant further verification.

Histaminergic System and Inflammation-Related Genes in Normal Large Intestine and Adenocarcinoma Tissues: Transcriptional Profiles and Relations

Transcriptional analyses such as microarray data have contributed to the progress in the diagnostics and therapy of colorectal cancer (CRC). The need for such research is still present because of the disease being common in both men and women with a high second position in cancer rankings. Little is known about the relations between the histaminergic system and inflammation in the large intestine and CRC. Therefore, the aim of this study was to evaluate the expression of genes related to the histaminergic system and inflammation in the CRC tissues at three cancer development designs: all tested CRC samples, low (LCS) and high (HCS) clinical stage, and four clinical stages (CSI-CSIV), to the control. The research was carried out at the transcriptomic level, analysing hundreds of mRNAs from microarrays, as well as carrying out RT-PCR analysis of histaminergic receptors. The following histaminergic mRNAs: GNA15, MAOA, WASF2A, and inflammation-related: AEBP1, CXCL1, CXCL2, CXCL3, CXCL8, SPHK1, TNFAIP6, were distinguished. Among all analysed transcripts, AEBP1 can be considered the most promising diagnostic marker in the early stage of CRC. The results showed 59 correlations between differentiating genes of the histaminergic system and inflammation in the control, control and CRC, and CRC. The tests confirmed the presence of all histamine receptor transcripts in both the control and colorectal adenocarcinoma. Significant differences in expression were stated for HRH2 and HRH3 in the advanced stages of CRC adenocarcinoma. The relations between the histaminergic system and inflammation-linked genes in both the control and the CRC have been observed.

Harnessing the Anti-Tumor Mediators in Mast Cells as a New Strategy for Adoptive Cell Transfer for Cancer

The emergence of cancer immunotherapies utilizing adoptive cell transfer (ACT) continues to be one of the most promising strategies for cancer treatment. Mast cells (MCs) which occur throughout vascularized tissues, are most commonly associated with Type I hypersensitivity, bind immunoglobin E (IgE) with high affinity, produce anti-cancer mediators such as tumor necrosis factor alpha (TNF-α) and granulocyte macrophage colony-stimulating factor (GM-CSF), and generally populate the tumor microenvironments. Yet, the role of MCs in cancer pathologies remains controversial with evidence for both anti-tumor and pro-tumor effects. Here, we review the studies examining the role of MCs in multiple forms of cancer, provide an alternative, MC-based hypothesis underlying the mechanism of therapeutic tumor IgE efficacy in clinical trials, and propose a novel strategy for using tumor-targeted, IgE-sensitized MCs as a platform for developing new cellular cancer immunotherapies. This autologous MC cancer immunotherapy could have several advantages over current cell-based cancer immunotherapies and provide new mechanistic strategies for cancer therapeutics alone or in combination with current approaches.

Increase in Chymase-Positive Mast Cells in Recurrent Pleomorphic Adenoma and Carcinoma Ex Pleomorphic Adenoma of the Parotid Gland

Incomplete excision of pleomorphic adenoma (PA) may result in recurrent pleomorphic adenoma (RPA). Furthermore, long-term neglected PA may become carcinoma ex pleomorphic adenoma (CXPA). In the present study, the relationships between mast cell-derived chymase and these tumors were examined. The tumor tissues of PA consisted of either or both glandular and fibrotic structures. Histological features of RPA were almost similar to those of PA, except that they showed multinodular structures. CXPA is composed of a mixture of PA and carcinoma. The main stromal cells in PA were myofibroblasts, whereas fibroblasts constituted the main cellular portion in the stromal tissue of RPA. Cancer-associated fibroblasts (CAFs) were present abundantly in CXPA. With increased VEGF expression, neovascularization tended to increase in RPA or CXPA. Compared with PA, chymase-positive mast cells, as well as chymase gene expression, were increased in the tumor tissues from patients with RPA or CXPA. SCF, TGFβ1, and PCNA-positive staining was widely observed in these tumor tissues. The above results suggest that mast cell-derived chymase through its direct or cooperative effects with other mediators may participate in the pathophysiology of RPA and CXPA.

Mast cells: Therapeutic targets for COVID-19 and beyond

Mast cells (MCs) are innate immune cells that widely distribute throughout all tissues and express a variety of cell surface receptors. Upon activation, MCs can rapidly release a diverse array of preformed mediators residing within their secretory granules and newly synthesize a broad spectrum of inflammatory and immunomodulatory mediators. These unique features of MCs enable them to act as sentinels in response to rapid changes within their microenvironment. There is increasing evidence now that MCs play prominent roles in other pathophysiological processes besides allergic inflammation. In this review, we highlight the recent findings on the emerging roles of MCs in the pathogenesis of coronavirus disease-2019 (COVID-19) and discuss the potential of MCs as novel therapeutic targets for COVID-19 and other non-allergic inflammatory diseases.

Tumor-Associated Mast Cells in Urothelial Bladder Cancer: Optimizing Immuno-Oncology

Urothelial bladder cancer (UBC) is one of the most prevalent and aggressive malignancies. Recent evidence indicates that the tumor microenvironment (TME), including a variety of immune cells, is a critical modulator of tumor initiation, progression, evolution, and treatment resistance. Mast cells (MCs) in UBC are possibly involved in tumor angiogenesis, tissue remodeling, and immunomodulation. Moreover, tumor-infiltration by MCs has been reported in early-stage UBC patients. This infiltration is linked with a favorable or unfavorable prognosis depending on the tumor type and location. Despite the discrepancy of MC function in tumor progression, MCs can modify the TME to regulate the immunity and infiltration of tumors by producing an array of mediators. Nonetheless, the precise role of MCs in UBC tumor progression and evolution remains unknown. Thus, this review discusses some critical roles of MCs in UBC. Patients with UBC are treated at both early and late stages by immunotherapeutic methods, including intravenous bacillus Calmette–Guérin instillation and immune checkpoint blockade. An understanding of the patient response and resistance mechanisms in UBC is required to unlock the complete potential of immunotherapy. Since MCs are pivotal to understand the underlying processes and predictors of therapeutic responses in UBC, our review also focuses on possible immunotherapeutic treatments that involve MCs.

Pathophysiological Roles of Histamine Receptors in Cancer Progression: Implications and Perspectives as Potential Molecular Targets

High levels of histamine and histamine receptors (HRs), including H1R~H4R, are found in many different types of tumor cells and cells in the tumor microenvironment, suggesting their involvement in tumor progression. This review summarizes the latest evidence demonstrating the pathophysiological roles of histamine and its cognate receptors in cancer biology. We also discuss the novel therapeutic approaches of selective HR ligands and their potential prognostic values in cancer treatment. Briefly, histamine is highly implicated in cancer development, growth, and metastasis through interactions with distinct HRs. It also regulates the infiltration of immune cells into the tumor sites, exerting an immunomodulatory function. Moreover, the effects of various HR ligands, including H1R antagonists, H2R antagonists, and H4R agonists, on tumor progression in many different cancer types are described. Interestingly, the expression levels of HR subtypes may serve as prognostic biomarkers in several cancers. Taken together, HRs are promising targets for cancer treatment, and HR ligands may offer novel therapeutic potential, alone or in combination with conventional therapy. However, due to the complexity of the pathophysiological roles of histamine and HRs in cancer biology, further studies are warranted before HR ligands can be introduced into clinical settings.