The presence of stromal mast cells identifies a subset of invasive breast cancers with a favorable prognosis

Tumor draining lymph nodes connected to cold triple-negative breast cancers are characterized by Th2-associated microenvironment

Tumor draining lymph nodes (TDLN) represent a key component of the tumor-immunity cycle. There are few studies describing how TDLNs impact lymphocyte infiltration into tumors. Here we directly compare tumor-free TDLNs draining "cold" and "hot" human triple negative breast cancers (TDLNCold and TDLNHot). Using machine-learning-based self-correlation analysis of immune gene expression, we find unbalanced intranodal regulations within TDLNCold. Two gene pairs (TBX21/GATA3-CXCR1) with opposite correlations suggest preferential priming of T helper 2 (Th2) cells by mature dendritic cells (DC) within TDLNCold. This is validated by multiplex immunofluorescent staining, identifying more mature-DC-Th2 spatial clusters within TDLNCold versus TDLNHot. Associated with this Th2 priming preference, more IL4 producing mast cells (MC) are found within sinus regions of TDLNCold. Downstream, Th2-associated fibrotic TME is found in paired cold tumors with increased Th2/T-helper-1-cell (Th1) ratio, upregulated fibrosis growth factors, and stromal enrichment of cancer associated fibroblasts. These findings are further confirmed in a validation cohort and public genomic data. Our results reveal a potential role of IL4+ MCs within TDLNs, associated with Th2 polarization and reduced immune infiltration into tumors.

A review concerning the breast cancer-related tumour microenvironment

Breast cancer (BC) is currently the most common malignant tumour in women and one of the leading causes of their death around the world. New and increasingly personalised diagnostic and therapeutic tools have been introduced over the last few decades, along with significant advances regarding the study and knowledge related to BC. The tumour microenvironment (TME) refers to the tumour cell-associated cellular and molecular environment which can influence conditions affecting tumour development and progression. The TME is composed of immune cells, stromal cells, extracellular matrix (ECM) and signalling molecules secreted by these different cell types. Ever deeper understanding of TME composition changes during tumour development and progression will enable new and more innovative therapeutic strategies to become developed for targeting tumours during specific stages of its evolution. This review summarises the role of BC-related TME components and their influence on tumour progression and the development of resistance to therapy. In addition, an account on the modifications in BC-related TME components associated with therapy is given, and the completed or ongoing clinical trials related to this topic are presented.

Stabilizing Tumor-Resident Mast Cells Restores T-Cell Infiltration and Sensitizes Sarcomas to PD-L1 Inhibition

PURPOSE

To explore the cellular cross-talk of tumor-resident mast cells (MC) in controlling the activity of cancer-associated fibroblasts (CAF) to overcome tumor microenvironment (TME) abnormalities, enhancing the efficacy of immune-checkpoint inhibitors in sarcoma.

EXPERIMENTAL DESIGN

We used a coculture system followed by further validation in mouse models of fibrosarcoma and osteosarcoma with or without administration of the MC stabilizer and antihistamine ketotifen. To evaluate the contribution of ketotifen in sensitizing tumors to therapy, we performed combination studies with doxorubicin chemotherapy and anti-PD-L1 (B7-H1, clone 10F.9G2) treatment. We investigated the ability of ketotifen to modulate the TME in human sarcomas in the context of a repurposed phase II clinical trial.

RESULTS

Inhibition of MC activation with ketotifen successfully suppressed CAF proliferation and stiffness of the extracellular matrix accompanied by an increase in vessel perfusion in fibrosarcoma and osteosarcoma as indicated by ultrasound shear wave elastography imaging. The improved tissue oxygenation increased the efficacy of chemoimmunotherapy, supported by enhanced T-cell infiltration and acquisition of tumor antigen-specific memory. Importantly, the effect of ketotifen in reducing tumor stiffness was further validated in sarcoma patients, highlighting its translational potential.

CONCLUSIONS

Our study suggests the targeting of MCs with clinically administered drugs, such as antihistamines, as a promising approach to overcome resistance to immunotherapy in sarcomas.

Tumor-Infiltrating Mast Cells in Angiosarcoma Correlate With Immuno-Oncology Pathways and Adverse Clinical Outcomes

Recent studies have described several molecular subtypes and deregulation of immuno-oncologic signaling pathways in angiosarcoma. Interestingly, mast cells were enriched in subsets of angiosarcoma, although their significance remains unknown. In this study, we aim to verify this observation using immunohistochemistry (H scores) and NanoString transcriptomic profiling and explore the association between mast cells with clinical and biological features. In the study cohort (N = 60), H scores showed a significant moderate correlation with NanoString mast cell scores (r = 0.525; P < .001). Both H score and NanoString mast cell scores showed a significant positive correlation (P < .05) with head and neck location, nonepithelioid morphology, and lower tumor grade. Mast cell enrichment significantly correlated with higher NanoString regulatory T-cell scores (H score, r = 0.32; P = .01; NanoString mast cell score, r = 0.27; P = .04). NanoString mast cell scores positively correlated with signaling pathways relating to antigen presentation (r = 0.264; P = .0414) and negatively correlated with apoptosis (r = -0.366; P = .0040), DNA damage repair (r = -0.348; P = .0064), and cell proliferation (r = -0.542; P < .001). Interestingly, in the metastatic setting, patients with mast cell-enriched angiosarcoma showed poorer progression-free survival (median, 0.2 vs 0.4 years; hazard ratio = 3.05; P = .0489) along with a trend toward worse overall survival (median, 0.2 vs 0.6 years; hazard ratio, 2.86; P = .0574) compared with patients with mast cell-poor angiosarcoma. In conclusion, we demonstrated the presence of mast cells in human angiosarcoma and provided initial evidence of their potential clinical and biological significance. Future research will be required to elucidate their specific roles and mechanisms, which may uncover novel avenues for therapeutic intervention.

Comparison of Mast Cell Density and Prognostic Factors in Invasive Breast Carcinoma: A Single-Centre Study in Malaysia

Background

Mast cells influence tumour growth, neo-angiogenesis and the propensity for metastasis by contributing to innate and adaptive immune responses in the tumour microenvironment. The number of mast cells has increased in various malignant tumours and their abundance has been associated with either a favourable or unfavourable prognosis. This study investigated the significant difference in stromal mast cell density among multiple prognostic factor groups in invasive breast carcinoma.

Methods

CD117 (c-KIT) antibodies were used to stain 160 formalin-fixed and paraffin-embedded invasive breast carcinoma tissues to demonstrate the presence of mast cells. Then the labelled mast cells were counted in 10 fields at 400× magnification and the mean value was used to represent the mast cell density.

Results

The demographic distribution revealed that most patients were 40 years old or older (92.5%) and of Malay ethnicity (66.3%). With regard to prognostic factors, the most prevalent subtype was invasive carcinoma of no special type (80.6%), followed by tumour grade 3 (41.3%), T2 tumour size (63.1%), N0 lymph node stage (51.3%), presence of lymphovascular invasion (59.4%), positive oestrogen (64.4%) and progesterone receptors (53.1%), and negative human epidermal growth factor receptor 2 (HER2) expression (75.0%). However, there was no significant difference in stromal mast cell density among the different demographic and prognostic factor groups in invasive breast carcinoma.

Conclusion

The findings from this study suggest that stromal mast cells do not play a significant role in preventing or promoting tumour growth in invasive breast carcinoma.

Mast cells in colorectal cancer tumour progression, angiogenesis, and lymphangiogenesis

The characteristics of the tumour cells, as well as how tumour cells interact with their surroundings, affect the prognosis of cancer patients. The resident cells in the tumour microenvironment are mast cells (MCs), which are known for their functions in allergic responses, but their functions in the cancer milieu have been hotly contested. Several studies have revealed a link between MCs and the development of tumours. Mast cell proliferation in colorectal cancer (CRC) is correlated with angiogenesis, the number of lymph nodes to which the malignancy has spread, and patient prognosis. By releasing angiogenic factors (VEGF-A, CXCL 8, MMP-9, etc.) and lymphangiogenic factors (VEGF-C, VEGF-D, etc.) stored in granules, mast cells play a significant role in the development of CRC. On the other hand, MCs can actively encourage tumour development via pathways including the c-kit/SCF-dependent signaling cascade and histamine production. The impact of MC-derived mediators on tumour growth, the prognostic importance of MCs in patients with various stages of colorectal cancer, and crosstalk between MCs and CRC cells in the tumour microenvironment are discussed in this article. We acknowledge the need for a deeper comprehension of the function of MCs in CRC and the possibility that targeting MCs might be a useful therapeutic approach in the future.

Mast cells inhibit colorectal cancer development by inducing ER stress through secreting Cystatin C

Mast cells (MCs) are abundantly distributed in the human intestinal mucosa and submucosa. However, their roles and mechanisms in the development of colorectal cancer (CRC) are still unclear. In the present research, we found that the infiltration density of MCs in CRC tissues was positively correlated with improved patients' prognoses. Moreover, MCs suppressed the growth and induced the apoptosis of CRC cells in vitro and in vivo but had no effect on normal colonic epithelial cells. The present study revealed that MCs specifically induced endoplasmic reticulum stress (ERS) and activated the unfolded protein response (UPR) in CRC cells but not in normal cells, which led to the suppression of CRC development in vivo. Furthermore, we found that the secreted Cystatin C protein was the key factor for the MC-induced ERS in CRC cells. This work is of significance for uncovering the antitumor function of MCs in CRC progression and identifying the potential of CRC to respond to MC-targeted immunotherapy.

Reciprocal Interactions Between the Gut Microbiome and Mammary Tissue Mast Cells Promote Metastatic Dissemination of HR+ Breast Tumors

Establishing commensal dysbiosis, defined as an inflammatory gut microbiome with low biodiversity, before breast tumor initiation, enhances early dissemination of hormone receptor-positive (HR+) mammary tumor cells. Here, we sought to determine whether cellular changes occurring in normal mammary tissues, before tumor initiation and in response to dysbiosis, enhanced dissemination of HR+ tumors. Commensal dysbiosis increased both the frequency and profibrogenicity of mast cells in normal, non-tumor-bearing mammary tissues, a phenotypic change that persisted after tumor implantation. Pharmacological and adoptive transfer approaches demonstrated that profibrogenic mammary tissue mast cells from dysbiotic animals were sufficient to enhance dissemination of HR+ tumor cells. Using archival HR+ patient samples, we determined that enhanced collagen levels in tumor-adjacent mammary tissue positively correlated with mast cell abundance and HR+ breast cancer recurrence. Together, these data demonstrate that mast cells programmed by commensal dysbiosis activate mammary tissue fibroblasts and orchestrate early dissemination of HR+ breast tumors.

Mast Cells and Dendritic Cells as Cellular Immune Checkpoints in Immunotherapy of Solid Tumors

The immune checkpoint inhibitors have revolutionized cancer immunotherapy. These inhibitors are game changers in many cancers and for many patients, sometimes show unprecedented therapeutic efficacy. However, their therapeutic efficacy is largely limited in many solid tumors where the tumor-controlled immune microenvironment prevents the immune system from efficiently reaching, recognizing, and eliminating cancer cells. The tumor immune microenvironment is largely orchestrated by immune cells through which tumors gain resistance against the immune system. Among these cells are mast cells and dendritic cells. Both cell types possess enormous capabilities to shape the immune microenvironment. These capabilities stage these cells as cellular checkpoints in the immune microenvironment. Regaining control over these cells in the tumor microenvironment can open new avenues for breaking the resistance of solid tumors to immunotherapy. In this review, we will discuss mast cells and dendritic cells in the context of solid tumors and how these immune cells can, alone or in cooperation, modulate the solid tumor resistance to the immune system. We will also discuss how this modulation could be used in novel immunotherapeutic modalities to weaken the solid tumor resistance to the immune system. This weakening could then help other immunotherapeutic modalities engage against these tumors more efficiently.

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.

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.

Dual Effect of Immune Cells within Tumour Microenvironment: Pro- and Anti-Tumour Effects and Their Triggers

Our body is constantly exposed to pathogens or external threats, but with the immune response that our body can develop, we can fight off and defeat possible attacks or infections. Nevertheless, sometimes this threat comes from an internal factor. Situations such as the existence of a tumour also cause our immune system (IS) to be put on alert. Indeed, the link between immunology and cancer is evident these days, with IS being used as one of the important targets for treating cancer. Our IS is able to eliminate those abnormal or damaged cells found in our body, preventing the uncontrolled proliferation of tumour cells that can lead to cancer. However, in several cases, tumour cells can escape from the IS. It has been observed that immune cells, the extracellular matrix, blood vessels, fat cells and various molecules could support tumour growth and development. Thus, the developing tumour receives structural support, irrigation and energy, among other resources, making its survival and progression possible. All these components that accompany and help the tumour to survive and to grow are called the tumour microenvironment (TME). Given the importance of its presence in the tumour development process, this review will focus on one of the components of the TME: immune cells. Immune cells can support anti-tumour immune response protecting us against tumour cells; nevertheless, they can also behave as pro-tumoural cells, thus promoting tumour progression and survival. In this review, the anti-tumour and pro-tumour immunity of several immune cells will be discussed. In addition, the TME influence on this dual effect will be also analysed.

Outcome and Immune Correlates of a Phase II Trial of High-Dose Interleukin-2 and Stereotactic Ablative Radiotherapy for Metastatic Renal Cell Carcinoma

PURPOSE

This phase II clinical trial evaluated whether the addition of stereotactic ablative radiotherapy (SAbR), which may promote tumor antigen presentation, improves the overall response rate (ORR) to high-dose IL2 (HD IL2) in metastatic renal cell carcinoma (mRCC).

PATIENTS AND METHODS

Patients with pathologic evidence of clear cell renal cell carcinoma (RCC) and radiographic evidence of metastasis were enrolled in this single-arm trial and were treated with SAbR, followed by HD IL2. ORR was assessed based on nonirradiated metastases. Secondary endpoints included overall survival (OS), progression-free survival (PFS), toxicity, and treatment-related tumor-specific immune response. Correlative studies involved whole-exome and transcriptome sequencing, T-cell receptor sequencing, cytokine analysis, and mass cytometry on patient samples.

RESULTS

Thirty ethnically diverse mRCC patients were enrolled. A median of two metastases were treated with SAbR. Among 25 patients evaluable by RECIST v1.1, ORR was 16% with 8% complete responses. Median OS was 37 months. Treatment-related adverse events (AE) included 22 grade ≥3 events that were not dissimilar from HD IL2 alone. There were no grade 5 AEs. A correlation was observed between SAbR to lung metastases and improved PFS (P = 0.0165). Clinical benefit correlated with frameshift mutational load, mast cell tumor infiltration, decreased circulating tumor-associated T-cell clones, and T-cell clonal expansion. Higher regulatory/CD8+ T-cell ratios at baseline in the tumor and periphery correlated with no clinical benefit.

CONCLUSIONS

Adding SAbR did not improve the response rate to HD IL2 in patients with mRCC in this study. Tissue analyses suggest a possible correlation between frameshift mutation load as well as tumor immune infiltrates and clinical outcomes.

Morphometric Analysis of Mast Cells in Tumor Predicts Recurrence of Hepatocellular Carcinoma After Liver Transplantation

Tumor-infiltrating immune cells are relevant prognostic and immunotherapeutic targets in hepatocellular carcinoma (HCC). Mast cells play a key role in allergic response but may also be involved in anticancer immunity. Digital morphometric analysis of patient tissue sections has become increasingly available for clinical routine and provides unbiased quantitative data. Here, we apply morphometric analysis of mast cells to retrospectively evaluate their relevance for HCC recurrence in patients after orthotopic liver transplantation (OLT). A total of 173 patients underwent OLT for HCC at the Medical University of Vienna (21 women, 152 men; 55.2 ± 7.9 years; 74 beyond Milan criteria, 49 beyond up-to-7 criteria for liver transplantation). Tissue arrays from tumors and corresponding surrounding tissues were immunohistochemically stained for mast cell tryptase. Mast cells were quantified by digital tissue morphometric analysis and correlated with HCC recurrence. Mast cells were detected in 93% of HCC tumors and in all available surrounding liver tissues. Tumor tissues revealed lower mast cell density than corresponding surrounding tissues (P < 0.0001). Patients lacking intratumoral mast cells (iMCs) displayed larger tumors and higher tumor recurrence rates both in the whole cohort (hazard ratio [HR], 2.74; 95% confidence interval [CI], 1.09-6.93; P = 0.029) and in patients beyond transplant criteria (Milan HR, 2.81; 95% CI, 1.04-7.62; P = 0.01; up-to-7 HR, 3.58; 95% CI, 1.17-10.92; P = 0.02). Notably, high iMC identified additional patients at low risk classified outside the Milan and up-to-7 criteria, whereas low iMC identified additional patients at high risk classified within the alpha-fetoprotein French and Metroticket criteria. iMCs independently predicted tumor recurrence in a multivariate Cox regression analysis (Milan HR, 2.38; 95% CI, 1.16-4.91; P = 0.019; up-to-7 HR, 2.21; 95% CI, 1.05-4.62; P = 0.035). Conclusion: Hepatic mast cells might be implicated in antitumor immunity in HCC. Morphometric analysis of iMCs refines prognosis of HCC recurrence after liver transplantation.

Identification of Mast Cell-Based Molecular Subtypes and a Predictive Signature in Clear Cell Renal Cell Carcinoma

Background: Kidney renal clear cell carcinoma (KIRC) is a common malignant tumor of the urinary system. Surgery is the preferred treatment option; however, the rate of distant metastasis is high. Mast cells in the tumor microenvironment promote or inhibit tumorigenesis depending on the cancer type; however, their role in KIRC is not well-established. Here, we used a bioinformatics approach to evaluate the roles of mast cells in KIRC.

Methods: To quantify mast cell abundance based on gene sets, a single-sample gene set enrichment analysis (ssGSEA) was utilized to analyze three datasets. Weighted correlation network analysis (WGCNA) was used to identify the genes most closely related to mast cells. To identify new molecular subtypes, the nonnegative matrix factorization algorithm was used. GSEA and least absolute shrinkage and selection operator (LASSO) Cox regression were used to identify genes with high prognostic value. A multivariate Cox regression analysis was performed to establish a prognostic model based on mast cell-related genes. Promoter methylation levels of mast cell-related genes and relationships between gene expression and survival were evaluated using the UALCAN and GEPIA databases.

Results: A prolonged survival in KIRC was associated with a high mast cell abundance. KIRC was divided into two molecular subtypes (cluster 1 and cluster 2) based on mast cell-related genes. Genes in Cluster 1 were enriched for various functions related to cancer development, such as the TGFβ signaling pathway, renal cell carcinoma, and mTOR signaling pathway. Based on drug sensitivity predictions, sensitivity to doxorubicin was higher for cluster 2 than for cluster 1. By a multivariate Cox analysis, we established a clinical prognostic model based on eight mast cell-related genes.

Conclusion: We identified eight mast cell-related genes and constructed a clinical prognostic model. These results improve our understanding of the roles of mast cells in KIRC and may contribute to personalized medicine.

Surfactin exerts an anti-cancer effect through inducing allergic reactions in melanoma skin cancer

Surfactin is a mast cell degranulator, that increases the immune response via the degranulation of mast cells. Recently, numerous studies reported that allergic reactions play an important role in the reduction of melanoma development. So, this study aimed to investigate the anti-cancer effects of surfactin in a melanoma skin cancer in vivo model and a melanoma cell line, B16F10. Oral administration of surfactin significantly increased survival rate and reduced tumor growth and tumor weight on melanoma skin cancer in vivo model. Surfactin significantly increased infiltration of mast cells and levels of histamine. Surfactin significantly enhanced levels of IgE and immune-enhancing mediators, such as interferon-γ, interleukin (IL)-2, IL-6, IL-12, and tumor necrosis factor-α in serum and melanoma tissues. Activities of caspase-3, 8, and 9 were significantly enhanced by oral administration of surfactin. In vitro model, surfactin significantly increased B16F10 cell death via activation of caspase-3, 8, and 9 in a dose-dependent manner. Overall, our results indicate that surfactin has a significant anti-cancer effect on melanoma skin cancer through indirectly or directly inducing apoptosis of B16F10 melanoma cells. Also, these findings suggest that it will contribute to a novel perception into the role of allergic reactions in melanoma.

A Ferroptosis-Related Prognostic Signature Based on Antitumor Immunity and Tumor Protein p53 Mutation Exploration for Guiding Treatment in Patients With Head and Neck Squamous Cell Carcinoma

Background: Due to the lack of accurate guidance of biomarkers, the treatment of head and neck squamous cell carcinoma (HNSCC) has not been ideal. Ferroptosis plays an important role in tumor suppression and treatment of patients. However, tumor protein p53 (TP53) mutation may promote tumor progression through ferroptosis. Therefore, it is particularly important to mine prognostic-related differentially expressed ferroptosis-related genes (PR-DE-FRGs) in HNSCC to construct a prognostic model for accurately guiding clinical treatment. Methods: First, the HNSCC data obtained from The Cancer Genome Atlas (TCGA) was used to identify PR-DE-FRGs for screening candidate genes to construct a prognostic model. We not only used a variety of methods to verify the accuracy of the model for predicting prognosis but also explored the role of ferroptosis in the development of HNSCC from the perspective of the immune microenvironment and mutation. Finally, we explored the correlation between the prognostic model and clinical treatment and drew a high-precision nomogram to predict the prognosis. Results: Seventeen of the 29 PR-DE-FRGs were selected to construct a prognostic model with good predictive performance. Patients in the low-risk group were found to have a greater number of CD8 + T cells, follicular helper T cells, regulatory T cells, mast cells, T-cell costimulations, and type II interferon responses. A higher tumor mutation burden (TMB) was observed in the low-risk group and was associated with a better prognosis. A higher risk score was found in the TP53 mutation group and was associated with a worse prognosis. The risk score is closely related to the expression of immune checkpoint inhibitors (ICIs)-related genes such as PD-L1 and the IC50 of six chemotherapeutic drugs. The nomogram we constructed performs well in predicting prognosis. Conclusion: Ferroptosis may participate in the progression of HNSCC through the immune microenvironment and TP53 mutation. The model we built can be used as an effective predictor of immunotherapy and chemotherapy effects and prognosis of HNSCC patients.

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.

Mast-Cell Tryptase Release Contributes to Disease Progression in Lymphangioleiomyomatosis

Rationale: Lymphangioleiomyomatosis (LAM) is a multisystem disease that causes lung cysts and respiratory failure. Loss of TSC (tuberous sclerosis complex) gene function results in a clone of "LAM cells" with dysregulated mTOR (mechanistic target of rapamycin) activity. LAM cells and fibroblasts form lung nodules that also contain mast cells, although their significance is unknown. Objectives: To understand the mechanism of mast-cell accumulation and the role of mast cells in the pathogenesis of LAM. Methods: Gene expression was examined using transcriptional profiling and qRT-PCR. Mast cell/LAM nodule interactions were examined in vitro using spheroid TSC2-null cell/fibroblast cocultures and in vivo using an immunocompetent Tsc2-null murine homograft model. Measurements and Main Results: LAM-derived cell/fibroblast cocultures induced multiple CXC chemokines in fibroblasts. LAM lungs had increased tryptase-positive mast cells expressing CXCRs (CXC chemokine receptors) (P < 0.05). Mast cells located around the periphery of LAM nodules were positively associated with the rate of lung function loss (P = 0.016). LAM spheroids attracted mast cells, and this process was inhibited by pharmacologic and CRISPR/cas9 inhibition of CXCR1 and CXCR2. LAM spheroids caused mast-cell tryptase release, which induced fibroblast proliferation and increased LAM-spheroid size (1.36 ± 0.24-fold; P = 0.0019). The tryptase inhibitor APC366 and sodium cromoglycate (SCG) inhibited mast cell-induced spheroid growth. In vivo, SCG reduced mast-cell activation and Tsc2-null lung tumor burden (vehicle: 32.5.3% ± 23.6%; SCG: 5.5% ± 4.3%; P = 0.0035). Conclusions: LAM-cell/fibroblast interactions attract mast cells where tryptase release contributes to disease progression. Repurposing SCG for use in LAM should be studied as an alternative or adjunct to mTOR inhibitor therapy.

Exploring the long noncoding RNAs-based biomarkers and pathogenesis of malignant transformation from dysplasia to oral squamous cell carcinoma by bioinformatics method

Long noncoding RNAs (lncRNAs) play an important role in many biological processes and carcinogenesis. We aimed to explore lncRNA-based pathogenesis, diagnostic biomarkers, and predictive factors of malignant transformation from dysplasia to oral squamous cell carcinoma (OSCC). Microarray data of GSE30784 consisting of 167 OSCC, 17 dysplasia, and 45 normal oral tissues were downloaded from the GEO database. The differentially expressed genes (DEGs) and lncRNAs between the three samples were identified using R, followed by lncRNA-mRNA coexpression and coregulation network analysis for the prediction of lncRNA target genes. Gene Ontology and Kyoto encydopedia of gene and genomes pathway analysis were performed to further characterize potential interactions. A total of 4462 DEGs and 76 differentially expressed lncRNAs were screened between the three groups, and 200 DEGs and only double homeobox A pseudogene 10 (DUXAP10) were screened among the three groups. A total of 1662 interactions of 46 lncRNAs and their coexpressed target genes were predicted, and 38 pairs of lncRNA-lncRNA coregulated 843 target genes. The coregulated target genes significantly enriched in antigen adaptive immune response, activation of phagocytosis receptor signaling, mast granule NF-κB inflammation, etc. Overall, lncRNAs were differentially expressed in OSCC and dysplasia. The target genes might play an important role in the carcinogenesis and development of OSCC. These results improve our understanding regarding the lncRNA-based pathogenesis and identify some potential targets for early diagnosis of malignant transformation from dysplasia to OSCC.

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.

Mast Cells as a Double Edged Sword in Immunity: Disorders of Mast Cell Activation and Therapeutic Management. Second of Two Parts

Mast cells (MCs) bear many receptors that allow them to respond to a variety of exogenous and endogenous stimuli. However, MC function is dual since they can initiate pathological events or protect the host against infectious challenges. The role of MCs in disease will be analyzed in a broad sense, describing cellular and molecular mechanisms related to their involvement in auto-inflammatory diseases, asthma, autoimmune diseases and cancer. On the other hand, their protective role in the course of bacterial, fungal and parasitic infections will also be illustrated. As far as treatment of MC-derived diseases is concerned, allergen immunotherapy as well as other attempts to reduce MC-activation will be outlined according to the recent data. Finally, in agreement with current literature and our own data polyphenols have been demonstrated to attenuate type I allergic reactions and contact dermatitis in response to nickel. The use of polyphenols in these diseases will be discussed also in view of MC involvement.

The Crosstalk Between Tumor Cells and the Immune Microenvironment in Breast Cancer: Implications for Immunotherapy

Breast cancer progression is a complex process controlled by genetic and epigenetic factors that coordinate the crosstalk between tumor cells and the components of tumor microenvironment (TME). Among those, the immune cells play a dual role during cancer onset and progression, as they can protect from tumor progression by killing immunogenic neoplastic cells, but in the meanwhile can also shape tumor immunogenicity, contributing to tumor escape. The complex interplay between cancer and the immune TME influences the outcome of immunotherapy and of many other anti-cancer therapies. Herein, we present an updated view of the pro- and anti-tumor activities of the main immune cell populations present in breast TME, such as T and NK cells, myeloid cells, innate lymphoid cells, mast cells and eosinophils, and of the underlying cytokine-, cell–cell contact- and microvesicle-based mechanisms. Moreover, current and novel therapeutic options that can revert the immunosuppressive activity of breast TME will be discussed. To this end, clinical trials assessing the efficacy of CAR-T and CAR-NK cells, cancer vaccination, immunogenic cell death-inducing chemotherapy, DNA methyl transferase and histone deacetylase inhibitors, cytokines or their inhibitors and other immunotherapies in breast cancer patients will be reviewed. The knowledge of the complex interplay that elapses between tumor and immune cells, and of the experimental therapies targeting it, would help to develop new combination treatments able to overcome tumor immune evasion mechanisms and optimize clinical benefit of current immunotherapies.

A review on the relationship of mast cells and macrophages in breast cancer - Can herbs or natural products facilitate their anti-tumor effects?

Breast cancer is an inflammation-related cancer whose tumor microenvironment is largely infiltrated by inflammatory cells. These inflammatory cells including mast cells and macrophages have been elucidated to be vital participants in breast tumor proliferation, survival, invasion and migration. However, the functions of mast cells and macrophages in breast cancer are quite distinct based on recent data. Mast cells exhibit both anti-tumoral and pro-tumoral functions on breast cancer, while high number of tumor-associated macrophages (TAMs) are strongly correlated with poor prognosis and higher risk of distant metastasis in breast cancer patients. Besides, many natural products/extracts have been reported to regulate mast cells and macrophages. In this review, the roles of mast cells and macrophages play in breast cancer are discussed and a summary of those natural products/herbs regulating the functions of mast cells or macrophages is also presented.

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.

TGF-β y células cebadas: reguladores del desarrollo del tumor

El Factor de crecimiento transformante β (TGF-β) es una citocina pleiotrópica implicada en distintas condiciones patológicas, como desórdenes autoinmunes, alergias y en los últimos años, en el cáncer. Esta citocina ejerce efectos supresores de tumores que las células cancerosas deben evadir para lograr la progresión del tumor. Sin embargo, paradójicamente, el TGF-β también modula procesos inflamatorios que favorecen la progresión del tumor, como el reclutamiento de células del sistema inmune al sitio del mismo; entre estas células se encuentran las células cebadas (CCs), las cuales, a su vez también participan en la regulación del tumor, a través de la secreción de distintos mediadores proinflamatorios, proangiogénicos y factores de crecimiento. En esta revisión se describen algunos avances en la comprensión del papel del TGF-β en la regulación de las CCs y la contribución de éstas en el desarrollo y la metástasis de tumores sólidos. El entendimiento de la función del TGF-β y de las células cebadas durante el desarrollo del cáncer es fundamental para el diseño de nuevas terapias que inhiban la progresión del tumor.

Low Stromal Mast Cell Density in Canine Mammary Gland Tumours Predicts a Poor Prognosis

Tumour histological classification and grade are frequently used to predict the prognosis of canine mammary gland tumours. While these techniques provide some information about tumour behaviour, it is currently difficult to predict which tumours will metastasize. Mast cell density has been shown to predict metastasis in human breast cancer. The present study investigated whether the average mast cell density in 10 high-power (×400) microscopical fields (10 HPFs), evaluated by toluidine blue staining, similarly predicted the behaviour of canine mammary gland tumours. Mast cell density was evaluated in 53 canine mammary neoplasms for which the clinical outcome was known. Stromal mast cell density in malignant tumours that had subsequently developed radiographical evidence of metastasis (n = 21) was significantly lower (P <0.001) than in malignant tumours that did not show evidence of metastases (n = 20) or in benign tumours (n = 12). The density of stromal mast cells that best predicted the disease outcome was ≤10/10 HPFs. Eighty-one percent of malignant tumours with ≤10 stromal mast cells/10 HPFs subsequently metastasized, while only 9.5% of malignant tumours with >10 stromal mast cells/10 HPFs developed metastases. There was a positive correlation between stromal mast cell density and survival time (r_s = 0.50, P <0.001). These findings suggest that assessing stromal mast cell density using toluidine blue staining may represent an easy to perform and cost-effective histopathological measure that, in conjunction with classification and grading, could better predict the behaviour of canine mammary neoplasms.

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.

Investigating the significance of tumor-infiltrating immune cells for the prognosis of lung squamous cell carcinoma

Objective

Increasing evidence has indicated an association between immune cells infiltration in LSCC and clinical outcome. The aim of this research was tantamount to comprehensively investigate the effect of 22 tumor infiltrating immune cells (TIICs) on the prognosis of LSCC patients.

Methods

In our research, the CIBERSORT algorithm was utilized to calculate the proportion of 22 TIICs in 502 cases from the TCGA cohort. Cases with a CIBERSORT P-value of <0.05 were kept for further study. Using the CIBERSORT algorithm, we first investigated the difference of immune infiltration between normal tissue and LSCC in 22 subpopulations of immune cells. Kaplan-Meier analysis was used to analyze the effect of 22 TIICs on the prognosis of LSCC. An immune risk score model was constructed based on TIICs correlated with LSCC-related recurrence. Multivariate cox regression analysis was used to investigate whether the immune risk score was an independent factor for prognosis prediction of LSCC. Nomogram was under construction to comprehensively predict the survival rate of LSCC.

Results

The results of the different analysis showed that except of memory B cells, naive CD4+T cells, T cells and activated NK cells, the remaining immune cells all had differential infiltration in normal tissues and LSCC (p < 0.05). Kaplan-Meier analysis revealed two immune cells statistically related to LSCC-related recurrence, including activated mast cells and follicular helper T cells. Immune risk score model was constructed based on three immune cells including resting memory CD4+T cells, activated mast cells and follicular helper T cells retained by forward stepwise regression analysis. The Kaplan-Meier curve indicated that patients in the high-risk group linked to poor outcome (P = 8.277e−03). ROC curve indicated that the immune risk score model was reliable in predicting recurrence risk (AUC = 0.614). Multivariate cox regression analysis showed that the immune risk score model was just an independent factor for prognosis prediction of LSCC (HR = 2.99, 95% CI [1.65–5.40]; P = 0.0002). The nomogram model combined immune risk score and clinicopathologic parameter score to predict 3-year survival in patients with LSCC.

Conclusions

Collectively, tumor-infiltrating immune cells play a major role in the prognosis of LSCC.

Human Skin-Derived Mast Cells Spontaneously Secrete Several Angiogenesis-Related Factors

Mast cells are classically recognized as cells that cause IgE-mediated allergic reactions. However, their ability to store and secrete vascular endothelial growth factor (VEGF) suggests a role in vascular development and tumorigenesis. The current study sought to determine if other angiogenesis-related factors, in addition to VEGF, were also secreted by human tissue-derived mast cells. Using proteome array analysis and ELISA, we found that human skin-derived mast cells spontaneously secrete CXCL16, DPPIV, Endothelin-1, GM-CSF, IL-8, MCP-1, Pentraxin 3, Serpin E1, Serpin F1, TIMP-1, Thrombospondin-1, and uPA. We identified three groups based on their dependency for stem cell factor (SCF), which is required for mast cell survival: Endothelin-1, GM-CSF, IL-8, MCP-1, and VEGF (dependent); Pentraxin 3, Serpin E1, Serpin F1, TIMP-1, and Thrombospondin-1 (partly dependent); and CXCL16, DPPIV, and uPA (independent). Crosslinking of FcεRI with multivalent antigen enhanced the secretion of GM-CSF, Serpin E1, IL-8, and VEGF, and induced Amphiregulin and MMP-8 expression. Interestingly, FcεRI signals inhibited the spontaneous secretion of CXCL16, Endothelin-1, Serpin F1, Thrombospondin-1, MCP-1 and Pentraxin-3. Furthermore, IL-6, which we previously showed could induce VEGF, significantly enhanced MCP-1 secretion. Overall, this study identified several angiogenesis-related proteins that, in addition to VEGF, are spontaneously secreted at high concentrations from human skin-derived mast cells. These findings provide further evidence supporting an intrinsic role for mast cells in blood vessel formation.

Poor Response to Neoadjuvant Chemotherapy Correlates with Mast Cell Infiltration in Inflammatory Breast Cancer

Our understanding is limited concerning the tumor immune microenvironment of inflammatory breast cancer (IBC), an aggressive form of primary cancer with low rates of pathologic complete response to current neoadjuvant chemotherapy (NAC) regimens. We retrospectively identified pretreatment (N = 86) and matched posttreatment tissue (N = 27) from patients with stage III or de novo stage IV IBC who received NAC followed by a mastectomy. Immune profiling was performed including quantification of lymphoid and myeloid infiltrates by IHC and T-cell repertoire analysis. Thirty-four of 86 cases in this cohort (39.5%) achieved a pathologic complete response. Characterization of the tumor microenvironment revealed that having a lower pretreatment mast cell density was significantly associated with achieving a pathologic complete response to NAC (P = 0.004), with responders also having more stromal tumor-infiltrating lymphocytes (P = 0.035), CD8⁺ T cells (P = 0.047), and CD20⁺ B cells (P = 0.054). Spatial analysis showed close proximity of mast cells to CD8⁺ T cells, CD163⁺ monocytes/macrophages, and tumor cells when pathologic complete response was not achieved. PD-L1 positivity on tumor cells was found in fewer than 2% of cases and on immune cells in 27% of cases, but with no correlation to response. Our results highlight the strong association of mast cell infiltration with poor response to NAC, suggesting a mechanism of treatment resistance and a potential therapeutic target in IBC. Proximity of mast cells to immune and tumor cells may suggest immunosuppressive or tumor-promoting interactions of these mast cells.

Mast Cells, Angiogenesis and Lymphangiogenesis in Human Gastric Cancer

Gastric cancer is diagnosed in nearly one million new patients each year and it remains the second leading cause of cancer-related deaths worldwide. Although gastric cancer represents a heterogeneous group of diseases, chronic inflammation has been shown to play a role in tumorigenesis. Cancer development is a multistep process characterized by genetic and epigenetic alterations during tumour initiation and progression. The stromal microenvironment is important in maintaining normal tissue homeostasis or promoting tumour development. A plethora of immune cells (i.e., lymphocytes, macrophages, mast cells, monocytes, myeloid-derived suppressor cells, Treg cells, dendritic cells, neutrophils, eosinophils, natural killer (NK) and natural killer T (NKT) cells) are components of gastric cancer microenvironment. Mast cell density is increased in gastric cancer and there is a correlation with angiogenesis, the number of metastatic lymph nodes and the survival of these patients. Mast cells exert a protumorigenic role in gastric cancer through the release of angiogenic (VEGF-A, CXCL8, MMP-9) and lymphangiogenic factors (VEGF-C and VEGF-F). Gastric mast cells express the programmed death ligands (PD-L1 and PD-L2) which are relevant as immune checkpoints in cancer. Several clinical undergoing trials targeting immune checkpoints could be an innovative therapeutic strategy in gastric cancer. Elucidation of the role of subsets of mast cells in different human gastric cancers will demand studies of increasing complexity beyond those assessing merely mast cell density and microlocalization.

Human Mast Cells From Adipose Tissue Target and Induce Apoptosis of Breast Cancer Cells

Mast cells (MC) are important immune sentinels found in most tissue and widely recognized for their role as mediators of Type I hypersensitivity. However, they also secrete anti-cancer mediators such as tumor necrosis factor alpha (TNF-α) and granulocyte-macrophage colony-stimulating factor (GM-CSF). The purpose of this study was to investigate adipose tissue as a new source of MC in quantities that could be used to study MC biology focusing on their ability to bind to and kill breast cancer cells. We tested several cell culture media previously demonstrated to induce MC differentiation. We report here the generation of functional human MC from adipose tissue. The adipose-derived mast cells (ADMC) are phenotypically and functionally similar to connective tissue expressing tryptase, chymase, c-kit, and FcεRI and capable of degranulating after cross-linking of FcεRI. The ADMC, sensitized with anti-HER2/neu IgE antibodies with human constant regions (trastuzumab IgE and/or C6MH3-B1 IgE), bound to and released MC mediators when incubated with HER2/neu-positive human breast cancer cells (SK-BR-3 and BT-474). Importantly, the HER2/neu IgE-sensitized ADMC induced breast cancer cell (SK-BR-3) death through apoptosis. Breast cancer cell apoptosis was observed after the addition of cell-free supernatants containing mediators released from FcεRI-challenged ADMC. Apoptosis was significantly reduced when TNF-α blocking antibodies were added to the media. Adipose tissue represents a source MC that could be used for multiple research purposes and potentially as a cell-mediated cancer immunotherapy through the expansion of autologous (or allogeneic) MC that can be targeted to tumors through IgE antibodies recognizing tumor specific antigens.

Prognostic significance of mast cell and microvascular densities in malignant peripheral nerve sheath tumor with and without neurofibromatosis type 1

Malignant peripheral nerve sheath tumors (MPNSTs) are rare and aggressive soft tissue sarcomas with a significant susceptibility to metastasize early in their course. Pathogenesis is yet to be fully elucidated. Recently, the essential role of mast cells in the tumor onset of neurofibromatosis type 1 (NF1)‐associated neurofibromas and MPNSTs was confirmed in both experimental and human studies. In this study, we investigate mast cell density (MCD), microvascular density (MVD), and proliferation index (Ki‐67) in MPNST. A secondary aim was to correlate histological staining to clinical data and survival in patients with and without NF1. In total, 34 formalin‐fixed paraffin‐embedded MPNST tissues from 29 patients were eligible. MCD, MVD, and Ki‐67 labeling index (LI) were analyzed in all stained tissues by a computer‐based quantitative algorithm (Aperio ImageScope). In addition, chart review was performed for clinical data and survival analysis. Overall, MCD, MVD, and Ki‐67 LI were evenly distributed throughout tumor tissue. There was a negative correlation of NF1 status (affected, P = 0.037), tumor size (>10 cm, P = 0.023), and MVD in the tumor periphery (higher tercile, P = 0.002) to survival. Multivariate analysis confirmed the association of MVD in the tumor periphery (higher tercile, P = 0.019) with a decreased overall survival. Diverse mast cell and microvascular distributions suggest that angiogenesis in MPNST occurs independently. The role of mast cells in tumor progression is unclear and lacks prognostic value. Higher MVD has prognostic significance with possible therapeutic implications in MPNST.

Human mast cells and basophils-How are they similar how are they different?

Mast cells and basophils are key contributors to allergies and other inflammatory diseases since they are the most prominent source of histamine as well as numerous additional inflammatory mediators which drive inflammatory responses. However, a closer understanding of their precise roles in allergies and other pathological conditions has been marred by the considerable heterogeneity that these cells display, not only between mast cells and basophils themselves but also across different tissue locations and species. While both cell types share the ability to rapidly degranulate and release histamine following high-affinity IgE receptor cross-linking, they differ markedly in their ability to either react to other stimuli, generate inflammatory eicosanoids or release immunomodulating cytokines and chemokines. Furthermore, these cells display considerable pharmacological heterogeneity which has stifled attempts to develop more effective anti-allergic therapies. Mast cell- and basophil-specific transcriptional profiling, at rest and after activation by innate and adaptive stimuli, may help to unravel the degree to which these cells differ and facilitate a clearer understanding of their biological functions and how these could be targeted by new therapies.

The dual role of mast cells in tumor fate

The exact role of mast cells in tumor growth is not clear and multifaceted. In some cases, mast cells stimulate while in others inhibit this process. This dual role may be explained to some extent by the huge number of bioactive molecules stored in mast cell granules, as well as differences between tumor microenvironment, tumor type, and tumor phase of development.

Relationship between the inflammatory tumor microenvironment and different histologic types of canine mammary tumors

Mammary neoplasms are the tumors with higher incidence in female dogs. Among the factors that contribute for the development of this and other neoplasms, the inflammatory tumor microenvironment plays a crucial role. Several studies reported important roles for lymphocytes, macrophages, plasma cells, neutrophils, eosinophils and mast cells in this context. In the present study, our aim was to evaluate the number of profile cells of inflammatory cells and area of tumor fibrosis and the relation of these features with canine mammary tumors of different histologic and clinical presentation (benign mixed tumor, carcinoma in mixed tumor, solid carcinoma and tubular carcinoma) Counting and staining of inflammatory cells and tumor fibrosis were performed through histochemistry, while counting and staining of CD4⁺, TCD8⁺ and FOXP3⁺ lymphocytes were performed through immunohistochemistry. Statistical analysis of the association between densities of inflammatory cells, tumor fibrosis and histologic types revealed significant difference for plasma cells (p = .035), neutrophils (p = .0113), macrophages (p = .0047), and tumor fibrosis (p = .05). The found data suggest associations between high number of neutrophils and aggressive mammary tumors, between high densities of plasma cells, macrophages and CD8⁺ cells and between low number of profile cells of CD4⁺ cells and less aggressive tumors. Larger areas of tumor fibrosis showed relation to more aggressive canine mammary tumors.

Mast cells promote melanoma colonization of lungs

Mast cells have been implicated in malignant processes, mainly through clinical correlative studies and by experiments performed using animals lacking mast cells due to defective c-kit signaling. However, mast cell-deficient mouse models based on c-kit defects have recently been questioned for their relevance. Here we addressed the effect of mast cells in a tumor setting by using transgenic Mcpt5-Cre⁺ R-DTA⁺ mice, in which the deficiency of mast cells is independent of c-kit defects. Melanoma cells (B16.F10) were administered either subcutaneously or intravenously into Mcpt5-Cre⁺ R-DTA⁺ mice or Mcpt5-Cre⁻ R-DTA⁺ littermate controls, followed by the assessment of formed tumors. In the subcutaneous model, mast cells were abundant in the tumor stroma of control mice but were absent in Mcpt5-Cre⁺ R-DTA⁺ mice. However, the absence of mast cells did not affect tumor size. In contrast, after intravenous administration of B16.F10 cells, melanoma colonization of the lungs was markedly reduced in Mcpt5-Cre⁺ R-DTA⁺ vs. Mcpt5-Cre⁻ R-DTA⁺ animals. Decreased melanoma colonization of the lungs in Mcpt5-Cre⁺ R-DTA⁺ animals was accompanied by increased inflammatory cell recruitment into the bronchoalveolar lavage fluid, suggesting that mast cells suppress inflammation in this setting. Further, qPCR analysis revealed significant alterations in the expression of Twist and E-cadherin in lungs of Mcpt5-Cre⁺ R-DTA⁺ vs. control Mcpt5-Cre⁻ R-DTA⁺ animals, suggesting an impact of mast cells on epithelial-mesenchymal transition. In conclusion, this study reveals that mast cells promote melanoma colonization of the lung.

Integrative analysis of imaging and transcriptomic data of the immune landscape associated with tumor metabolism in lung adenocarcinoma: Clinical and prognostic implications

Although metabolic modulation in the tumor microenvironment (TME) is one of the key mechanisms of cancer immune escape, there is a lack of understanding of the comprehensive immune landscape of the TME and its association with tumor metabolism based on clinical evidence. We aimed to investigate the relationship between the immune landscape in the TME and tumor glucose metabolism in lung adenocarcinoma. Methods: Using RNA sequencing and image data, we developed a transcriptome-based tumor metabolism estimation model. The comprehensive TME cell types enrichment scores and overall immune cell enrichment (ImmuneScore) were estimated. Subjects were clustered by cellular heterogeneity in the TME and the clusters were characterized by tumor glucose metabolism and immune cell composition. Moreover, the prognostic value of ImmuneScore, tumor metabolism and the cell type-based clusters was also evaluated. Results: Four clusters were identified based on the cellular heterogeneity in the TME. They showed distinct immune cell composition, different tumor metabolism, and close relationship with overall survival. A cluster with high regulatory T cells showed relative hypermetabolism and poor prognosis. Another cluster with high mast cells and CD4+ central memory T cells showed relative hypometabolism and favorable prognosis. A cluster with high ImmuneScore showed favorable prognosis. Multivariate Cox analysis demonstrated that ImmuneScore was a predictive prognostic factor independent of other clinical features. Conclusions: Our results showed the association between predicted tumor metabolism and immune cell composition in the TME. Our studies also suggest that tumor glucose metabolism and immune cell infiltration in the TME can be clinically applicable for developing a prognostic stratification model.

Mast Cell, the Neglected Member of the Tumor Microenvironment: Role in Breast Cancer

Mast cells are unique tissue-resident immune cells that secrete a diverse array of biologically active compounds that can stimulate, modulate, or suppress the immune response. Although mounting evidence supports that mast cells are consistently infiltrating tumors, their role as either a driving or an opposite force for cancer progression is still controversial. Particularly, in breast cancer, their function is still under discussion. While some studies have shown a protective role, recent evidence indicates that mast cells enhance blood and lymphatic vessel formation. Interestingly, one of the most important components of the mast cell cargo, the serine protease tryptase, is a potent angiogenic factor, and elevated serum tryptase levels correlate with bad prognosis in breast cancer patients. Likewise, histamine is known to induce tumor cell proliferation and tumor growth. In agreement, mast cell depletion reduces the size of mammary tumors and metastasis in murine models that spontaneously develop breast cancer. In this review, we will discuss the evidence supporting protumoral and antitumoral roles of mast cells, emphasizing recent findings placing mast cells as important drivers of tumor progression, as well as the potential use of these cells or their mediators as therapeutic targets.

Quantitative assessment of tumor-associated tissue eosinophilia and mast cells in tumor proper and lymph nodes of oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC) is the most common cancer of the oral cavity. Tumor stage, thickness, lymph node metastasis (LNM), extranodal spread, perineural invasion, tumor differentiation, mutations, human papillomavirus infection and tumor microenvironment are independent prognostic indicators of OSCC. However, clinically, among all factors, LNM is considered an important prognostic factor in OSCC as it not only determines the stage of disease but also the strongest independent factor which predicts recurrence of disease. Further research proves that there are several biologically important factors in tumor tissue and LNs which promote or defend LNM. While it is proposed that tumor-associated tissue eosinophils (TATE) and mast cells (MCs) have "immuno-protective" effect, this remains unproven and various researchers have conflicting opinion.

Aim

The aim is to determine the presence of TATE and MCs in OSCC and to evaluate if any association exists between them and LNM.

Study Design

It is a comparative retrospective study between two groups including 35 OSCC cases positive and 35 negative for LNM.

Materials and Methodology

Quantification of cells was done by counting total number of cells in 10 high-power fields under ×40 objective lens using "zigzag" method and dividing it by total number of fields. Eosinophils stained bright red with carbol chromotrope and MCs purple-violet with toluidine blue.

Statistics

Independent t-test and Pearson's correlation were done using STATA IC 0.2 software. The level of significance was at 5%. Comparison of eosinophil and MC infiltration was done based on gender, metastatic, nonmetastatic LN and in tumor proper.

Results and Conclusion

Our study showed weak positive correlation between mean eosinophils count in tumor and LNs which implies a definite association between the microenvironment of tumor, its progression and LNM. There was a significant association between MC density and decreased LNM also. We conclude that an increased number of immunological cells (TATE and MCs) are a favorable prognostic indicator in OSCC. There is evidence of reduction in LNM with increasing density of these immunological cells. Recognition of TATE and MCs as integral to tumor biology opens an avenue for novel approaches to cancer therapies.

Risk of solid cancer in patients with mast cell activation syndrome: Results from Germany and USA

Background:  It has been shown repeatedly that mast cells can promote or prevent cancer development and growth. If development and/or progression of a solid cancer is substantially influenced by mast cell activity, the frequencies of occurrence of solid cancers in patients with primary mast cells disorders would be expected to differ from the corresponding prevalence data in the general population. In fact, a recent study demonstrated that patients with systemic mastocytosis (i.e., a rare neoplastic variant of the primary mast cell activation disease) have increased risk for solid cancers, in particular melanoma and non-melanoma skin cancers. The aim of the present study is to examine whether the risk of solid cancer is increased in systemic mast cell activation syndrome (MCAS), the common systemic variant of mast cell activation disease. Methods: In the present descriptive study, we have analysed a large (n=828) patient group with MCAS, consisting of cohorts from Germany and the USA, for occurrence of solid forms of cancer and compared the frequencies of the different cancers with corresponding prevalence data for German and U.S. general populations. Results: Sixty-eight of the 828 MCAS patients (46 female, 22 male) had developed a solid tumor before the diagnosis of MCAS was made. Comparison of the frequencies of the malignancies in the MCAS patients with their prevalence in the general population revealed a significantly increased prevalence for melanoma and cancers of the breast, cervix uteri, ovary, lung, and thyroid in MCAS patients. Conclusions: Our data support the view that mast cells may promote development of certain malignant tumors. These findings indicate a need for increased surveillance of certain types of cancer in MCAS patients irrespective of its individual clinical presentation.

Functional proteomics outlines the complexity of breast cancer molecular subtypes

Breast cancer is a heterogeneous disease comprising a variety of entities with various genetic backgrounds. Estrogen receptor-positive, human epidermal growth factor receptor 2-negative tumors typically have a favorable outcome; however, some patients eventually relapse, which suggests some heterogeneity within this category. In the present study, we used proteomics and miRNA profiling techniques to characterize a set of 102 either estrogen receptor-positive (ER+)/progesterone receptor-positive (PR+) or triple-negative formalin-fixed, paraffin-embedded breast tumors. Protein expression-based probabilistic graphical models and flux balance analyses revealed that some ER+/PR+ samples had a protein expression profile similar to that of triple-negative samples and had a clinical outcome similar to those with triple-negative disease. This probabilistic graphical model-based classification had prognostic value in patients with luminal A breast cancer. This prognostic information was independent of that provided by standard genomic tests for breast cancer, such as MammaPrint, OncoType Dx and the 8-gene Score.

Are Mast Cells MASTers in Cancer?

Prolonged low-grade inflammation or smoldering inflammation is a hallmark of cancer. Mast cells form a heterogeneous population of immune cells with differences in their ultra-structure, morphology, mediator content, and surface receptors. Mast cells are widely distributed throughout all tissues and are stromal components of the inflammatory microenvironment that modulates tumor initiation and development. Although canonically associated with allergic disorders, mast cells are a major source of pro-tumorigenic (e.g., angiogenic and lymphangiogenic factors) and antitumorigenic molecules (e.g., TNF-α and IL-9), depending on the milieu. In certain neoplasias (e.g., gastric, thyroid and Hodgkin's lymphoma) mast cells play a pro-tumorigenic role, in others (e.g., breast cancer) a protective role, whereas in yet others they are apparently innocent bystanders. These seemingly conflicting results suggest that the role of mast cells and their mediators could be cancer specific. The microlocalization (e.g., peritumoral vs intratumoral) of mast cells is another important aspect in the initiation/progression of solid and hematologic tumors. Increasing evidence in certain experimental models indicates that targeting mast cells and/or their mediators represent a potential therapeutic target in cancer. Thus, mast cells deserve focused consideration also as therapeutic targets in different types of tumors. There are many unanswered questions that should be addressed before we understand whether mast cells are an ally, adversary, or innocent bystanders in human cancers.

Relationship of mast cell density with lymphangiogenesis and prognostic parameters in breast carcinoma

In many cancers, mast cell density (MCD) in the tumor microenvironment is associated with tumor progression and, to a greater extent, angiogenesis. Our study was designed to investigate the correlation between MCD, tumor lymphangiogenesis, and several well-established prognostic parameters in breast cancer. One hundred and four cases of invasive breast carcinoma diagnosed in our clinic between 2007 and 2011 were included. Mast cells and lymphatic vessels were stained with toluidine blue and D2-40, respectively, and their densities were calculated in various areas of tumors and lymph nodes. The variables of MCD and lymphatic vessel density (LVD) were compared using prognostic parameters as well as with each other. As tumor size and volume increased, MCD increased comparably in metastatic lymph nodes; intratumoral and peritumoral LVD also increased. Lymphovascular invasion, lymphatic invasion, perineural invasion, and estrogen receptor positivity were positively related to intratumoral MCD. The relationship between peritumoral MCD and nontumoral breast tissue MCD was statistically significant. Stage was correlated with MCD in metastatic lymph nodes. Metastatic lymph node MCD and intratumoral MCD were also significantly related. Stage, lymphatic invasion, perineural invasion, lymphovascular invasion, and metastatic lymph node MCD were all correlated with intratumoral and/or peritumoral LVD. As nuclear grade increased, intratumoral LVD became higher. In breast carcinoma, MCD, depending on its location, was related to several prognostic parameters. Notably, mast cells may have at least some effect on lymphangiogenesis, which appears to be a predictor of tumor progression.

Mast Cells Are Abundant in Primary Cutaneous T-Cell Lymphomas: Results from a Computer-Aided Quantitative Immunohistological Study

Background

Mast cells (MC) are bone marrow derived haematopoetic cells playing a crucial role not only in immune response but also in the tumor microenvironment with protumorigenic and antitumorigenic functions. The role of MC in primary cutaneous T-cell lymphomas (CTCL), a heterogeneous group of non-Hodgkin lymphomas with initial presentation in the skin, is largely unknown.

Objective

To gain more accurate information about presence, number, distribution and state of activation (degranulated vs. non-degranulated) of MC in CTCL variants and clinical stages.

Materials and Methods

We established a novel computer-aided tissue analysis method on digitized skin sections. Immunohistochemistry with an anti-MC tryptase antibody was performed on 34 biopsies of different CTCL subtypes and on control skin samples. An algorithm for the automatic detection of the epidermis and of cell density based CTCL areas was developed. Cells were stratified as being within the CTCL infiltrate, in P1 (a surrounding area 0–30 μm away from CTCL), or in P2 (30–60 μm away from CTCL) area.

Results

We found high MC counts within CTCL infiltrates and P1 and a decreased MC number in the surrounding dermis P2. Higher MC numbers were found in MF compared to all other CTCL subgroups. Regarding different stages of MF, we found significantly higher mast cell counts in stages IA and IB than in stages IIA and IIB. Regarding MC densities, we found a higher density of MC in MF compared to all other CTCL subgroups. More MC were non-degranulated than degranulated.

Conclusion

Here for the first time an automated method for MC analysis on tissue sections and its use in CTCL is described. Eliminating error from investigator bias, the method allows for precise cell identification and counting. Our results provide new insights on MC distribution in CTCL reappraising their role in the pathophysiology of CTCL.

Controversial role of mast cells in skin cancers

Cancer development is a multistep process characterized by genetic and epigenetic alterations during tumor initiation and progression. The stromal microenvironment can promote tumor development. Mast cells, widely distributed throughout all tissues, are a stromal component of many solid and haematologic tumors. Mast cells can be found in human and mouse models of skin cancers such as melanoma, basal and squamous cell carcinomas, primary cutaneous lymphomas, haemangiomas and Merkel cell carcinoma. However, human and animal studies addressing potential functions of mast cells and their mediators in skin cancers have provided conflicting results. In several studies, mast cells play a pro-tumorigenic role, whereas in others, they play an anti-tumorigenic role. Other studies have failed to demonstrate a clear role for tumor-associated mast cells. Many unanswered questions need to be addressed before we understand whether tumor-associated mast cells are adversaries, allies or simply innocent bystanders in different types and subtypes of skin cancers.

Relevance of Tumor-Infiltrating Immune Cell Composition and Functionality for Disease Outcome in Breast Cancer

Background

Not all breast cancer patients benefit from neoadjuvant or adjuvant therapy, resulting in considerable undertreatment or overtreatment. New insights into the role of tumor-infiltrating immune cells suggest that their composition, as well as their functionality, might serve as a biomarker to enable optimal patient selection for current systemic therapies and upcoming treatment options such as immunotherapy.

Methods

We performed several complementary unbiased in silico analyses on gene expression profiles of 7270 unrelated tumor samples of nonmetastatic breast cancer patients with known clinical follow-up. CIBERSORT was used to estimate the fraction of 22 immune cell types to study their relations with pathological complete response (pCR), disease-free survival (DFS), and overall survival (OS). In addition, we used four previously reported immune gene signatures and a CD8+ T-cell exhaustion signature to assess their relationships with breast cancer outcome. Multivariable binary logistic regression and multivariable Cox regression were used to assess the association of immune cell-type fractions and immune signatures with pCR and DFS/OS, respectively.

Results

Increased fraction of regulatory T-cells in human epidermal growth factor receptor 2 (HER2)-positive tumors was associated with a lower pCR rate (odds ratio [OR] = 0.15, 95% confidence interval [CI] = 0.03 to 0.69), as well as shorter DFS (hazard ratio [HR] = 3.13, 95% CI = 1.23 to 7.98) and OS (HR = 7.69, 95% CI = 3.43 to 17.23). A higher fraction of M0 macrophages in estrogen receptor (ER)-positive tumors was associated with worse DFS (HR = 1.66, 95% CI = 1.18 to 2.33) and, in ER-positive/HER2-negative tumors, with worse OS (HR = 1.71, 95% CI = 1.12 to 2.61). Increased fractions of γδ T-cells in all breast cancer patients related to a higher pCR rate (OR = 1.55, 95% CI = 1.01 to 2.38), prolonged DFS (HR = 0.68, 95% CI = 0.48 to 0.98), and, in HER2-positive tumors, with prolonged OS (HR = 0.27, 95% CI = 0.10 to 0.73). A higher fraction of activated mast cells was associated with worse DFS (HR = 5.85, 95% CI = 2.20 to 15.54) and OS (HR = 5.33, 95% CI = 2.04 to 13.91) in HER2-positive tumors. The composition of relevant immune cell types frequently differed per breast cancer subtype. Furthermore, a high CD8+ T-cell exhaustion signature score was associated with shortened DFS in patients with ER-positive tumors regardless of HER2 status (HR = 1.80, 95% CI = 1.07 to 3.04).

Conclusions

The main hypothesis generated in our unbiased in silico approach is that a multitude of immune cells are related to treatment response and outcome in breast cancer.