Mast Cells as an Indicator and Prognostic Marker in Molecular Subtypes of Breast Cancer

PGR-KITLG signaling drives a tumor-mast cell regulatory feedback to modulate apoptosis of breast cancer cells

The immune microenvironment constructed by tumor-infiltrating immune cells and the molecular phenotype defined by hormone receptors (HRs) have been implicated as decisive factors in the regulation of breast cancer (BC) progression. Here, we found that the infiltration of mast cells (MCs) informed impaired prognoses in HR(+) BC but predicted improved prognoses in HR(-) BC. However, molecular features of MCs in different BC remain unclear. We next discovered that HR(-) BC cells were prone to apoptosis under the stimulation of MCs, whereas HR(+) BC cells exerted anti-apoptotic effects. Mechanistically, in HR(+) BC, the KIT ligand (KITLG), a major mast cell growth factor in recruiting and activating MCs, could be transcriptionally upregulated by the progesterone receptor (PGR), and elevate the production of MC-derived granulin (GRN). GRN attenuates TNFα-induced apoptosis in BC cells by competitively binding to TNFR1. Furthermore, disruption of PGR-KITLG signaling by knocking down PGR or using the specific KITLG-cKIT inhibitor iSCK03 potently enhanced the sensitivity of HR(+) BC cells to MC-induced apoptosis and exerted anti-tumor activity. Collectively, these results demonstrate that PGR-KITLG signaling in BC cells preferentially induces GRN expression in MCs to exert anti-apoptotic effects, with potential value in developing precision medicine approaches for diagnosis and treatment.

Cellular interactions in tumor microenvironment during breast cancer progression: new frontiers and implications for novel therapeutics

The breast cancer tumor microenvironment (TME) is dynamic, with various immune and non-immune cells interacting to regulate tumor progression and anti-tumor immunity. It is now evident that the cells within the TME significantly contribute to breast cancer progression and resistance to various conventional and newly developed anti-tumor therapies. Both immune and non-immune cells in the TME play critical roles in tumor onset, uncontrolled proliferation, metastasis, immune evasion, and resistance to anti-tumor therapies. Consequently, molecular and cellular components of breast TME have emerged as promising therapeutic targets for developing novel treatments. The breast TME primarily comprises cancer cells, stromal cells, vasculature, and infiltrating immune cells. Currently, numerous clinical trials targeting specific TME components of breast cancer are underway. However, the complexity of the TME and its impact on the evasion of anti-tumor immunity necessitate further research to develop novel and improved breast cancer therapies. The multifaceted nature of breast TME cells arises from their phenotypic and functional plasticity, which endows them with both pro and anti-tumor roles during tumor progression. In this review, we discuss current understanding and recent advances in the pro and anti-tumoral functions of TME cells and their implications for developing safe and effective therapies to control breast cancer progress.

The prognostic significance of non-lymphoid immune cells of the tumor microenvironment, including neutrophils, eosinophils, and mast cells in breast carcinomas

BACKGROUND AND OBJECTIVE

The prognostic importance of lymphoid cells in the tumor microenvironment and their effect on treatment response have been demonstrated in many cancer types. However, there are limited studies on non-lymphoid immune cells. Conflicting results have been obtained regarding the effects of these cells on prognosis.

MATERIALS AND METHODS

A total of 331 patients who underwent surgery for breast cancer were included. Patients that received neoadjuvant chemotherapy and those with distant metastasis were excluded. CD 15 immunohistochemistry was performed to detect tumor-infiltrating neutrophils (TINs) and eosinophils (TIEs), while Toluidine Blue histochemistry was performed to detect tumor-infiltrating mast cells (TIMs).

RESULTS

High TINs were statistically associated with low ER expression (p < 0.001), low PR expression (p = 0.001), high Ki-67 proliferation index (p = 0.008), and HER2/TN molecular subtypes (p = 0.001). High TIEs were associated with low ER expression (p = 0.001), high Ki67 proliferation index (p = 0.005), and HER2/TN molecular subtype (p = 0.002). High TIMs were associated with high PR expression (p = 0.024), low Ki-67 proliferation index (p = 0.003), and high survival rate (p = 0.006). TIMs and TIEs were good prognostic factors for overall survival in Luminal A and Luminal B subtypes, while TINs and TIEs were found to be independent risk factors for disease-free survival.

CONCLUSION

The evaluation of components of the tumor microenvironment including TINs, TIEs, and TIMs is easy and practical. High TIMs and TIEs are independent prognostic factors, especially in luminal molecular subtype of invasive breast carcinoma. However, to use this parameter in routine pathology practice, more studies from different centers and standard evaluation are needed.

Mast Cells as a Target-A Comprehensive Review of Recent Therapeutic Approaches

Mast cells (MCs) are the immune cells distributed throughout nearly all tissues, mainly in the skin, near blood vessels and lymph vessels, nerves, lungs, and the intestines. Although MCs are essential to the healthy immune response, their overactivity and pathological states can lead to numerous health hazards. The side effect of mast cell activity is usually caused by degranulation. It can be triggered by immunological factors, such as immunoglobulins, lymphocytes, or antigen-antibody complexes, and non-immune factors, such as radiation and pathogens. An intensive reaction of mast cells can even lead to anaphylaxis, one of the most life-threatening allergic reactions. What is more, mast cells play a role in the tumor microenvironment by modulating various events of tumor biology, such as cell proliferation and survival, angiogenesis, invasiveness, and metastasis. The mechanisms of the mast cell actions are still poorly understood, making it difficult to develop therapies for their pathological condition. This review focuses on the possible therapies targeting mast cell degranulation, anaphylaxis, and MC-derived tumors.

Associations of breast cancer related exposures and gene expression profiles in normal breast tissue-The Norwegian Women and Cancer normal breast tissue study

BACKGROUND

Normal breast tissue is utilized in tissue-based studies of breast carcinogenesis. While gene expression in breast tumor tissue is well explored, our knowledge of transcriptomic signatures in normal breast tissue is still incomplete. The aim of this study was to investigate variability of gene expression in a large sample of normal breast tissue biopsies, according to breast cancer related exposures (obesity, smoking, alcohol, hormone therapy, and parity).

METHODS

We analyzed gene expression profiles from 311 normal breast tissue biopsies from cancer-free, post-menopausal women, using Illumina bead chip arrays. Principal component analysis and K-means clustering was used for initial analysis of the dataset. The association of exposures and covariates with gene expression was determined using linear models for microarrays.

RESULTS

Heterogeneity of the breast tissue and cell composition had the strongest influence on gene expression profiles. After adjusting for cell composition, obesity, smoking, and alcohol showed the highest numbers of associated genes and pathways, whereas hormone therapy and parity were associated with negligible gene expression differences.

CONCLUSION

Our results provide insight into associations between major exposures and gene expression profiles and provide an informative baseline for improved understanding of exposure-related molecular events in normal breast tissue of cancer-free, post-menopausal women.

New C3H KitN824K/WT cancer mouse model develops late-onset malignant mammary tumors with high penetrance

Gastro-intestinal stromal tumors and acute myeloid leukemia induced by activating stem cell factor receptor tyrosine kinase (KIT) mutations are highly malignant. Less clear is the role of KIT mutations in the context of breast cancer. Treatment success of KIT-induced cancers is still unsatisfactory because of primary or secondary resistance to therapy. Mouse models offer essential platforms for studies on molecular disease mechanisms in basic cancer research. In the course of the Munich N-ethyl-N-nitrosourea (ENU) mutagenesis program a mouse line with inherited polycythemia was established. It carries a base-pair exchange in the Kit gene leading to an amino acid exchange at position 824 in the activation loop of KIT. This KIT variant corresponds to the N822K mutation found in human cancers, which is associated with imatinib-resistance. C3H Kit^N824K/WT mice develop hyperplasia of interstitial cells of Cajal and retention of ingesta in the cecum. In contrast to previous Kit-mutant models, we observe a benign course of gastrointestinal pathology associated with prolonged survival. Female mutants develop mammary carcinomas at late onset and subsequent lung metastasis. The disease model complements existing oncology research platforms. It allows for addressing the role of KIT mutations in breast cancer and identifying genetic and environmental modifiers of disease progression.

Association of mast cell density, microvascular density and endothelial area with clinicopathological parameters and prognosis in canine mammary gland carcinomas

Background

Mast cell density has been shown to have both enhancing and inhibiting effects on tumour progression and the ability to predict breast cancer behaviour in humans. However, prognostic results have been contradictory. Some previous studies suggested involvement of mast cells in the progression of canine mammary tumours. This study investigated total, intratumoural and peritumoural mast cell densities by Giemsa staining, and their association with clinicopathological parameters and the disease outcome of canine mammary tumours. In addition, since mast cells promote angiogenesis, the microvascular density and endothelial area were evaluated by CD31 immunostaining.

Results

Intratumoural mast cell density was associated with tumour size, lymph node involvement and tumour-infiltrating lymphocyte count, while peritumoural mast cell density was associated with grade. The endothelial area was associated with grade, mitotic index, tubular formation and proliferation index. Tumours with a high grade, high total intratumoural mast cell density and a larger endothelial area were associated with shorter disease-free survival. Intratumoural mast cell density and grade were found to be independent prognostic factors.

Conclusions

These results suggest that intratumoural mast cell density and the endothelial area can be used to evaluate the aggressiveness of canine mammary carcinomas, while intratumoural mast cell density could be of use as an independent predictor of a prognosis of disease-free survival. Peritumoural mast cell density does not seem to influence tumour behaviour.

Few, but Efficient: The Role of Mast Cells in Breast Cancer and Other Solid Tumors

Tumor outcome is determined not only by cancer cell-intrinsic features but also by the interaction between cancer cells and their microenvironment. There is great interest in tumor-infiltrating immune cells, yet mast cells have been less studied. Recent work has highlighted the impact of mast cells on the features and aggressiveness of cancer cells, but the eventual effect of mast cell infiltration is still controversial. Here, we review multifaceted findings regarding the role of mast cells in cancer, with a particular focus on breast cancer, which is further complicated because of its classification into subtypes characterized by different biological features, outcome, and therapeutic strategies.

Mast cell density in the primary tumor predicts lymph node metastases in patients with breast cancer

Breast cancer (BrCa) is the most frequent neoplastic disease in female, with high morbidity and mortality. Most of the researches were focused on tumor cells concerning their natural evolution, molecular profile, and potential response to therapy. Few and uncertain data are available about the tumor microenvironment and its impact on the progression of the disease. Mast cells (MCs) associated to BrCa have been reported many years ago, but their real and specific role in the biology of this disease remained elusive. In the current study, we have investigated the predictive role of MCs from the primary tumor on lymph node metastasis on patients stratified based on the molecular classification. We investigated 156 patients with BrCa, stratified as luminal A, luminal B, human epidermal growth factor receptor 2 (HER2) type, basal-like, and unclassified. MCs were identified with anti-MC tryptase antibody in a double immunohistochemical reaction combined with anti-cluster of differentiation 34 (CD34) antibody. Mast cell density (MCD) was calculated based on the hot-spot method, on three fields with maximum density of MCs in each case. The final result was the arithmetic media that was compared with the molecular profile and lymph node metastases. We found no significant correlation between MCD and the molecular profile of the primary tumor, but we noticed a strong correlation between intratumor MCD and lymph node metastases, regardless of the molecular type.

Histamine in cancer immunology and immunotherapy. Current status and new perspectives

Cancer is the second leading cause of death globally and its incidence and mortality are rapidly increasing worldwide. The dynamic interaction of immune cells and tumor cells determines the clinical outcome of cancer. Immunotherapy comes to the forefront of cancer treatments, resulting in impressive and durable responses but only in a fraction of patients. Thus, understanding the characteristics and profiles of immune cells in the tumor microenvironment (TME) is a necessary step to move forward in the design of new immunomodulatory strategies that can boost the immune system to fight cancer. Histamine produces a complex and fine-tuned regulation of the phenotype and functions of the different immune cells, participating in multiple regulatory responses of the innate and adaptive immunity. Considering the important actions of histamine-producing immune cells in the TME, in this review we first address the most important immunomodulatory roles of histamine and histamine receptors in the context of cancer development and progression. In addition, this review highlights the current progress and foundational developments in the field of cancer immunotherapy in combination with histamine and pharmacological compounds targeting histamine receptors.

Proteomics and its applications in breast cancer

Breast cancer is an individually unique, multi-faceted and chameleonic disease, an eternal challenge for the new era of high-integrated precision diagnostic and personalized oncomedicine. Besides traditional single-omics fields (such as genomics, epigenomics, transcriptomics and metabolomics) and multi-omics contributions (proteogenomics, proteotranscriptomics or reproductomics), several new "-omics" approaches and exciting proteomics subfields are contributing to basic and advanced understanding of these "multiple diseases termed breast cancer": phenomics/cellomics, connectomics and interactomics, secretomics, matrisomics, exosomics, angiomics, chaperomics and epichaperomics, phosphoproteomics, ubiquitinomics, metalloproteomics, terminomics, degradomics and metadegradomics, adhesomics, stressomics, microbiomics, immunomics, salivaomics, materiomics and other biomics. Throughout the extremely complex neoplastic process, a Breast Cancer Cell Continuum Concept (BCCCC) has been modeled in this review as a spatio-temporal and holistic approach, as long as the breast cancer represents a complex cascade comprising successively integrated populations of heterogeneous tumor and cancer-associated cells, that reflect the carcinoma's progression from a "driving mutation" and formation of the breast primary tumor, toward the distant secondary tumors in different tissues and organs, via circulating tumor cell populations. This BCCCC is widely sustained by a Breast Cancer Proteomic Continuum Concept (BCPCC), where each phenotype of neoplastic and tumor-associated cells is characterized by a changing and adaptive proteomic profile detected in solid and liquid minimal invasive biopsies by complex proteomics approaches. Such a profile is created, beginning with the proteomic landscape of different neoplastic cell populations and cancer-associated cells, followed by subsequent analysis of protein biomarkers involved in epithelial-mesenchymal transition and intravasation, circulating tumor cell proteomics, and, finally, by protein biomarkers that highlight the extravasation and distant metastatic invasion. Proteomics technologies are producing important data in breast cancer diagnostic, prognostic, and predictive biomarkers discovery and validation, are detecting genetic aberrations at the proteome level, describing functional and regulatory pathways and emphasizing specific protein and peptide profiles in human tissues, biological fluids, cell lines and animal models. Also, proteomics can identify different breast cancer subtypes and specific protein and proteoform expression, can assess the efficacy of cancer therapies at cellular and tissular level and can even identify new therapeutic target proteins in clinical studies.

Controversial role of mast cells in breast cancer tumor progression and angiogenesis

Breast cancer is a neoplastic disease and is a cause of cancer-related mortality for women. Among cellular and molecular regulators of the microenvironment, mast cells and vascular endothelial growth factor (VEGF), are correlated with tumor progression and prognosis in breast cancer. Clinical and experimental studies on breast cancer have revealed a marked correlation between increased angiogenesis, metastasization, and poorer prognosis. After a brief introduction on angiogenesis evidence and angiogenic factors role in different breast cancer subtypes, in this article, we have discerned the relationship between mast cell infiltration, angiogenesis, and tumor progression in human breast cancer with particular reference to the dual role of mast cells, in terms of both pro- or anti-tumoral activity and poor or good biomarker.

Crosstalk between Tumor-Infiltrating Immune Cells and Cancer-Associated Fibroblasts in Tumor Growth and Immunosuppression of Breast Cancer

Signals from the tumor microenvironment (TME) have a profound influence on the maintenance and progression of cancers. Chronic inflammation and the infiltration of immune cells in breast cancer (BC) have been strongly associated with early carcinogenic events and a switch to a more immunosuppressive response. Cancer-associated fibroblasts (CAFs) are the most abundant stromal component and can modulate tumor progression according to their secretomes. The immune cells including tumor-infiltrating lymphocytes (TILs) (cytotoxic T cells (CTLs), regulatory T cells (Tregs), and helper T cell (Th)), monocyte-infiltrating cells (MICs), myeloid-derived suppressor cells (MDSCs), mast cells (MCs), and natural killer cells (NKs) play an important part in the immunological balance, fluctuating TME between protumoral and antitumoral responses. In this review article, we have summarized the impact of these immunological players together with CAF secreted substances in driving BC progression. We explain the crosstalk of CAFs and tumor-infiltrating immune cells suppressing antitumor response in BC, proposing these cellular entities as predictive markers of poor prognosis. CAF-tumor-infiltrating immune cell interaction is suggested as an alternative therapeutic strategy to regulate the immunosuppressive microenvironment in BC.

Mast Cells and Skin and Breast Cancers: A Complicated and Microenvironment-Dependent Role

Mast cells are important sentinel cells in host defense against infection and major effector cells in allergic disease. The role of these cells in cancer settings has been widely debated. The diverse range of mast cell functions in both immunity and tissue remodeling events, such as angiogenesis, provides multiple opportunities for mast cells to modify the tumor microenvironment. In this review, we consider both skin and breast cancer settings to address the controversy surrounding the importance of mast cells in the host response to tumors. We specifically address the key mediators produced by mast cells which impact tumor development. The role of environmental challenges in modifying mast cell responses and opportunities to modify mast cell responses to enhance anti-tumor immunity are also considered. While the mast cell's role in many cancer contexts is complicated and poorly understood, the activities of these tissue resident and radioresistant cells can provide important opportunities to enhance anti-cancer responses and limit cancer development.

An In Vitro Model of Mast Cell Recruitment and Activation by Breast Cancer Cells Supports Anti-Tumoral Responses

Breast cancer (BrC) affects millions of women yearly. Mast cells (MCs) are common components of breast tumors with documented agonistic and antagonistic roles in tumor progression. Understanding the participation of MCs in BrC may lead to new therapies to control tumor growth. In this study, we looked into mechanistic models of MC responses triggered by BrC cells (BrCC), assessing both early degranulation and late transcriptional activities. We used aggressive and non-aggressive BrCC to model the progressive staging of the disease over HMC1 and LAD-2 human MC lines. We found that both MC lines were chemoattracted by all BrCC, but their activation was preferentially induced by aggressive lines, finding differences in their active transcriptional programs, both at basal level and after stimulation. Among those genes with altered expression were down-regulated SPP1, PDCD1, IL17A and TGFB1 and up-regulated KITLG and IFNG. A low expression of SPP1 and a high expression of KITLG and IFNG were associated with increased overall survival of BrC patients from public databases. The set of altered genes is more often associated with tumor stromas enriched with anti-tumoral signals, suggesting that MCs may participate in tumor control.

Infiltrating Mast Cell-Mediated Stimulation of Estrogen Receptor Activity in Breast Cancer Cells Promotes the Luminal Phenotype

Tumor growth and development is determined by both cancer cell-autonomous and microenvironmental mechanisms, including the contribution of infiltrating immune cells. Because the role of mast cells (MC) in this process is poorly characterized and even controversial, we investigated their part in breast cancer. Crossing C57BL/6 MMTV-PyMT mice, which spontaneously develop mammary carcinomas, with MC-deficient C57BL/6-KitW-sh/W-sh (Wsh) mice, showed that MCs promote tumor growth and prevent the development of basal CK5-positive areas in favor of a luminal gene program. When cocultured with breast cancer cells in vitro, MCs hindered activation of cMET, a master regulator of the basal program, and simultaneously promoted expression and activation of estrogen receptor (ESR1/ER) and its target genes (PGR, KRT8/CK8, BCL2), which are all luminal markers. Moreover, MCs reduced ERBB2/HER2 levels, whose inhibition further increased ESR1 expression. In vivo and in silico analysis of patients with breast cancer revealed a direct correlation between MC density and ESR1 expression. In mice engrafted with HER2-positive breast cancer tumors, coinjection of MCs increased tumor engraftment and outgrowth, supporting the link between MCs and increased risk of relapse in patients with breast cancer. Together, our findings support the notion that MCs influence the phenotype of breast cancer cells by stimulating a luminal phenotype and ultimately modifying the outcome of the disease. SIGNIFICANCE: Mast cells impact breast cancer outcome by directly affecting the phenotype of tumor cells through stimulation of the estrogen receptor pathway.

Mast Cells in the Tumor Microenvironment

Mast cells are tissue-resident, innate immune cells that play a key role in the inflammatory response and tissue homeostasis. Mast cells accumulate in the tumor stroma of different human cancer types, and increased mast cell density has been associated to either good or poor prognosis, depending on the tumor type and stage. Mast cells play a multifaceted role in the tumor microenvironment by modulating various events of tumor biology, such as cell proliferation and survival, angiogenesis, invasiveness, and metastasis. Moreover, tumor-associated mast cells have the potential to shape the tumor microenvironment by establishing crosstalk with other tumor-infiltrating cells. This chapter reviews the current understanding of the role of mast cells in the tumor microenvironment. These cells have received much less attention than other tumor-associated immune cells but are now recognized as critical components of the tumor microenvironment and could hold promise as a potential target to improve cancer immunotherapy.