CD68+, but not stabilin-1+ tumor associated macrophages in gaps of ductal tumor structures negatively correlate with the lymphatic metastasis in human breast cancer

Tumor-associated macrophages: Potential therapeutic targets and diagnostic markers in cancer

Macrophages are plastic and functionally diverse, present in all tissues, and play a key role in organisms from development, homeostasis and repair, to immune responses to pathogens. They are central to many disease states and have emerged as important therapeutic targets for many diseases. Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME) and are key factors influencing cancer progression, metastasis and tumor recurrence. TAMs can be derived from different sources and exert different pro- or anti-tumor effects based on the type, stage and immune composition of the tumor. TAMs are highly heterogeneous and diverse, and have multiple functional phenotypes. There is still a great deal of controversy regarding the relationship between TAMs and prognosis of cancer patients. In this review, we summarize the characteristics of common markers of TAMs as well as explore the prognostic role of TAMs in different cancers including lung, breast, gastric, colorectal, esophageal and ovarian cancers.

Tumor-associated macrophages respond to chemotherapy by detrimental transcriptional reprogramming and suppressing stabilin-1 mediated clearance of EGF

Introduction

Tumor resistance to chemotherapy and metastatic relapse account for more than 90% of cancer specific mortality. Tumor-associated macrophages (TAMs) can process chemotherapeutic agents and impair their action. Little is known about the direct effects of chemotherapy on TAMs.

Methods

The effect of chemotherapeutic platinum agent cisplatin was assessed in the model system of human ex vivo TAMs. Whole-transcriptome sequencing for paired TAMs stimulated and not stimulated by cisplatin was analysed by NGS. Endocytic uptake of EGF was quantified by flow cytometry. Confocal microscopy was used to visualize stabilin-1-mediated internalization and endocytic trafficking of EGF in CHO cells expressing ectopically recombinant stabilin-1 and in stabilin-1+ TAMs. In cohort of patients with breast cancer, the effect of platinum therapy on the transcriptome of TAMs was validated, and differential expression of regulators of endocytosis was identified.

Results

Here we show that chemotherapeutic agent cisplatin can initiate detrimental transcriptional and functional programs in TAMs, without significant impairment of their viability. We focused on the clearance function of TAMs that controls composition of tumor microenvironment. For the first time we demonstrated that TAMs' scavenger receptor stabilin-1 is responsible for the clearance of epidermal growth factor (EGF), a potent stimulator of tumor growth. Cisplatin suppressed both overall and EGF-specific endocytosis in TAMs by bidirectional mode: suppression of positive regulators and stimulation of negative regulators of endocytosis, with strongest effect on synaptotagmin-11 (SYT11), confirmed in patients with breast cancer.

Conclusion

Our data demonstrate that synergistic action of cytostatic agents and innovative immunomodulators is required to overcome cancer therapy resistance.

Next Generation Sequencing of Reactive Stroma and Residual Breast Cancer Cells in Tumor Bed after Neoadjuvant Chemotherapy

Primary systemic or neoadjuvant chemotherapy of breast cancer has become a standard therapy option in locally advanced or predefined intrinsic subtypes such as triple negative or Her2 positive breast cancer. Neoadjuvant chemotherapy can result in complete pathological response without residual tumor cells (tumor bed) or partial response and non-response with different amounts of reactive stroma and residual tumor cells. The interaction between therapy regimens and tumoral driver mutations have been extensively studied, although the reactive stroma of the tumor bed received less attention. In this study, we characterized the mutational status of residual breast cancer cells and reactive tumor stroma devoid of residual tumor cells in partial or non-responders using next generation sequencing. Twenty-one post-therapeutic breast surgical specimens after neoadjuvant chemotherapy underwent pathogenic driver-mutation screening using microdissected residual breast cancer cells and in reactive stroma adjacent to tumor bed areas. In reactive stroma, no mutations could be validated. In residual breast cancer cells, mutations were detected in sixteen of twenty-one cases (76%). In nine of these twenty-one cases (43%), pathogenic driver mutations (PIK3CA, PTEN, TP53, FN1, PLAG1) were identified. Pathogenic driver-mutations are exclusively restricted to residual carcinoma cells and are absent in reactive stroma independently from intrinsic breast cancer subtypes or tumor stage. These data suggest that the absence of pathogenic mutations in a tumor bed without residual tumor cells may have prognostic implications after neoadjuvant chemotherapy.

Clever-1 positive macrophages in breast cancer

Purpose

Common Lymphatic Endothelial and Vascular Endothelial Receptor 1 (Clever-1) is expressed by a subset of immunosuppressive macrophages and targeting the receptor with therapeutic antibodies has been shown to activate T-cell-mediated anti-cancer immunity. The aim of this research was to study Clever-1 expression in breast cancer. Specifically, how Clever-1 + macrophages correlate with clinicopathologic factors, Tumor Infiltrating Lymphocytes (TILs) and prognosis.

Methods

Tissue microarray blocks were made from 373 primary breast cancer operation specimens. Hematoxylin and Eosin (H&E-staining) and immunohistochemical staining with Clever-1, CD3, CD4 and CD8 antibodies were performed. Differences in quantities of Clever-1 + macrophages and TILs were analyzed. Clever-1 + cell numbers were correlated with 25-year follow-up survival data and with breast cancer clinicopathologic parameters.

Results

Low numbers of intratumoral Clever-1 + cells were found to be an independent adverse prognostic sign. Increased numbers of Clever-1 + cells were found in high grade tumors and hormone receptor negative tumors. Tumors that had higher amounts of Clever-1 + cells also tended to have higher amounts of TILs.

Conclusion

The association of intratumoral Clever-1 + macrophages with better prognosis might stem from the function of Clever as a scavenger receptor that modulates tumor stroma. The association of Clever-1 + macrophages with high number of TILs and better prognosis indicates that immunosuppression by M2 macrophages is not necessarily dampening adaptive immune responses but instead keeping them in control to avoid excess inflammation.

Tumor-associated macrophages (TAMs) modulate response to HER2-targeted agents in a humanized mouse model of breast cancer

PURPOSE

Tumor-associated macrophages (TAM) may participate to antitumor activity of anti-HER2-targeted therapies (Pertuzumab, Trastuzumab) in breast cancers harbouring HER-2 overexpression through antibody-dependent phagocytosis. Additive antitumor effect of concurrent cytotoxic chemotherapies, including Paclitaxel, may be counterbalanced by alteration in TAM infiltrate. The aim of this study is to evaluate the role of TAM in tumor response to anti-HER2-targeted therapies and chemotherapy in an experimental model of HER2-amplified breast cancer.

METHODS

A xenograft mouse model was built by subcutaneous injection of the SKBR-3 human HER2-amplified breast cancer cell line in Hu-CD34+ mice. Animals were randomized to receive weekly administration of Cremophor (control), Trastuzumab+Pertuzumab (TP), and Paclitaxel+Trastuzumab+Pertuzumab (PTP) with or without macrophage depletion with clodronate (C). At week 4, mice were euthanised and tumors were harvested for immunohistochemical analysis of TAM infiltration (RBP-J CD163 and CD68 for M1, M2, and overall TAM, respectively).

RESULTS

Tumor size was significantly lower in mice treated with TP, PTP, and PTP+C as compared to control, while no meaningful difference was observed in the TP+C arm. Analysis of TAM infiltrate showed significantly lower CD68 and CD163 expression in PTP, TP+C, and PTP+C as compared to TP and control arm. RBP-J expression was significantly decreased in mice treated with clodronate depletion.

CONCLUSIONS

Activity of TP is modulated by TAM infiltrate, that is inhibited by concurrent administration of Paclitaxel. To enhance the effect of anti-HER2-targeted therapies and minimize chemotherapy-related side effects, modulation of TAM should be considered in novel therapeutic combinations.

Tumor Properties Mediate the Relationship Between Peripheral Blood Monocytes and Tumor-Associated Macrophages in Breast Cancer

In cancer patients, circulating monocytes show functional alterations. Since monocytes are precursors of tumor-associated macrophages (TAMs), TAMs ensuring tumor viability are potentially replenished through the recruitment of monocytes with specific properties. We demonstrated that locoregional metastasis and circulating factors, such as CD45-EpCAM + CD44 + CD24-/low circulating tumor cells, and serum MCP-1 and HMGB1 were statistically associated with modulation of the monocyte features in breast cancer patients. The count of circulating CD45-EpCAM + cells correlated with CD68+, CD163 + monocyte in blood, and with density of CD68 + TAM in breast cancer tumors. Overall, the relationship between monocytes and TAMs is mediated by the tumor in breast cancer patients.

Tumor Microenvironment in Breast Cancer-Updates on Therapeutic Implications and Pathologic Assessment

The tumor microenvironment (TME) in breast cancer comprises local factors, cancer cells, immune cells and stromal cells of the local and distant tissues. The interaction between cancer cells and their microenvironment plays important roles in tumor proliferation, propagation and response to therapies. There is increasing research in exploring and manipulating the non-cancerous components of the TME for breast cancer treatment. As the TME is now increasingly recognized as a treatment target, its pathologic assessment has become a critical component of breast cancer management. The latest WHO classification of tumors of the breast listed stromal response pattern/fibrotic focus as a prognostic factor and includes recommendations on the assessment of tumor infiltrating lymphocytes and PD-1/PD-L1 expression, with therapeutic implications. This review dissects the TME of breast cancer, describes pathologic assessment relevant for prognostication and treatment decision, and details therapeutic options that interacts with and/or exploits the TME in breast cancer.

New Angiogenic Regulators Produced by TAMs: Perspective for Targeting Tumor Angiogenesis

Simple Summary

Since the targeting of a single pro-angiogenic factor fails to improve oncological disease outcome, significant efforts have been made to identify new pro-angiogenic factors that could compensate for the deficiency of current therapy or act independently as single drugs. Our review aims to present the state-of-the art for well-known and recently described factors produced by macrophages that induce and regulate angiogenesis. A number of positive and negative regulators of angiogenesis in the tumor microenvironment are produced by tumor-associated macrophages (TAMs). Accumulating evidence has indicated that, apart from the well-known angiogenic factors, there are plenty of novel angiogenesis-regulating proteins that belong to different classes. We summarize the data regarding the direct or indirect mechanisms of the interaction of these factors with endothelial cells during angiogenesis. We highlight the recent findings that explain the limitations in the efficiency of current anti-angiogenic therapy approaches.

Abstract

Angiogenesis is crucial to the supply of a growing tumor with nutrition and oxygen. Inhibition of angiogenesis is one of the main treatment strategies for colorectal, lung, breast, renal, and other solid cancers. However, currently applied drugs that target VEGF or receptor tyrosine kinases have limited efficiency, which raises a question concerning the mechanism of patient resistance to the already developed drugs. Tumor-associated macrophages (TAMs) were identified in the animal tumor models as a key inducer of the angiogenic switch. TAMs represent a potent source not only for VEGF, but also for a number of other pro-angiogenic factors. Our review provides information about the activity of secreted regulators of angiogenesis produced by TAMs. They include members of SEMA and S100A families, chitinase-like proteins, osteopontin, and SPARC. The COX-2, Tie2, and other factors that control the pro-angiogenic activity of TAMs are also discussed. We highlight how these recent findings explain the limitations in the efficiency of current anti-angiogenic therapy. Additionally, we describe genetic and posttranscriptional mechanisms that control the expression of factors regulating angiogenesis. Finally, we present prospects for the complex targeting of the pro-angiogenic activity of TAMs.

Tumor-Associated Macrophages in Human Breast, Colorectal, Lung, Ovarian and Prostate Cancers

Tumor-associated macrophages (TAMs) are major innate immune cells that constitute up to 50% of the cell mass of human tumors. TAMs are highly heterogeneous cells that originate from resident tissue-specific macrophages and from newly recruited monocytes. TAMs' variability strongly depends on cancer type, stage, and intratumor heterogeneity. Majority of TAMs are programmed by tumor microenvironment to support primary tumor growth and metastatic spread. However, TAMs can also restrict tumor growth and metastasis. In this review, we summarized the knowledge about the role of TAMs in tumor growth, metastasis and in the response to cancer therapy in patients with five aggressive types of cancer: breast, colorectal, lung, ovarian, and prostate cancers that are frequently metastasize into distant organs resulting in high mortality of the patients. Two major TAM parameters are applied for the evaluation of TAM correlation with the cancer progression: total amount of TAMs and specific phenotype of TAMs identified by functional biomarkers. We summarized the data generated in the wide range of international patient cohorts on the correlation of TAMs with clinical and pathological parameters of tumor progression including lymphatic and hematogenous metastasis, recurrence, survival, therapy efficiency. We described currently available biomarkers for TAMs that can be measured in patients' samples (tumor tissue and blood). CD68 is the major biomarker for the quantification of total TAM amounts, while transmembrane receptors (stabilin-1, CD163, CD206, CD204, MARCO) and secreted chitinase-like proteins (YKL-39, YKL-40) are used as biomarkers for the functional TAM polarization. We also considered that specific role of TAMs in tumor progression can depend on the localization in the intratumoral compartments. We have made the conclusion for the role of TAMs in primary tumor growth, metastasis, and therapy sensitivity for breast, colorectal, lung, ovarian, and prostate cancers. In contrast to other cancer types, majority of clinical studies indicate that TAMs in colorectal cancer have protective role for the patient and interfere with primary tumor growth and metastasis. The accumulated data are essential for using TAMs as biomarkers and therapeutic targets to develop cancer-specific immunotherapy and to design efficient combinations of traditional therapy and new immunomodulatory approaches.

Influence of Estrogen on the NSCLC Microenvironment: A Comprehensive Picture and Clinical Implications

Lung cancer mortality represents the leading cause of cancer related deaths in the United States and worldwide. Almost half of these deaths occur in female patients, making lung cancer the most common cause of cancer mortality in women with a higher annual mortality rate than breast, uterine, and ovarian cancers combined. The distinct epidemiological, histological and biological presentation of non-small cell lung cancer (NSCLC) in women combined with extensive preclinical data have demonstrated that the female sex hormone β-estradiol (E2) plays an important role in NSCLC tumorigenesis, prognosis, and treatment response. Estrogen receptors are widely expressed on stromal and immune cells, and estrogen-linked signaling pathways are known to be involved in regulating the response of both the innate and adaptive immune system. Immune evasion has been recognized as a “hallmark” of cancer and immunotherapy has re-defined standard of care treatment for NSCLC. Despite these advancements, the low response rates observed in patients treated with immune checkpoint inhibitors has led to a search for mediators of immunosuppression and ways to augment the action of these agents. We focus on emerging data describing sex differences that modulate immunotherapy efficacy in NSCLC, immunosuppressive properties of E2 that lead to a pro-tumor microenvironment (TME), and the translational potential of altering the immune microenvironment by targeting the estrogen signaling pathway. E2-induced modulation affects multiple cell types within the TME, including cancer-associated fibroblasts, tumor infiltrating myeloid cells, and tumor infiltrating lymphocytes, all of which interplay with lung tumor cells via E2 and estrogen receptor engagement, ultimately shaping the TME that may, in part, be responsible for the sex-based disparities observed in NSCLC. An improved understanding of the role of the estrogen pathway in NSCLC anti-cancer immunity may lead to novel therapeutic approaches for altering the TME to improve the efficacy of immunotherapy agents.

Antitumor properties of triptolide: phenotype regulation of macrophage differentiation

Tumor-associated macrophages (TAMs), which generally exhibit an M2-like phenotype, play a critical role in tumor development. Triptolide exerts a unique bioactive spectrum of anticancer activities. The aim of this study was to determine whether triptolide has any effect on the activation of TAMs and the production of tumor-promoting mediators. ICR-1 mice with azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colon tumors and BALB/c mice co-inoculated with 4T1 cells and M2-polarized RAW264.7 cells were used to examine whether the inhibitory effect of triptolide on tumor progression was mediated by the targeting of TAMs. Real-time PCR, Western blot, immunofluorescence staining, and flow cytometry assays were performed to determine the expression of cell surface markers and cytokine production. The results showed that triptolide inhibited macrophage differentiation toward the M2 phenotype and abolished M2 macrophage-mediated tumor progression. Furthermore, triptolide inhibited the expression of M2 markers, such as CD206, Arginase 1, and CD204, and inhibited the secretion of anti-inflammatory cytokines. Thus our study indicated that triptolide selectively inhibited the functions of M2-polarized macrophages and TAMs, and this inhibitory effect of triptolide on TAM viability, differentiation, and cytokine production might elucidate the major mechanisms underlying its antitumor activity. Our findings provide important information for the potential clinical application of triptolide in cancer therapy.

Microlocalization and clinical significance of stabilin-1+ macrophages in treatment-naïve patients with urothelial carcinoma of the bladder

Purpose

Emerging evidence has shown that macrophages (Mφs) at different tumor sites have diverse clinical attributes. Stabilin-1 is a multi-functional scavenger marker for specialized tumor-associated Mφs. This study investigates the relationship between the density and microlocalization of stabilin-1⁺ Mφs within tumors and the clinical outcomes of patients with urothelial carcinoma of the bladder (UCB).

Methods

In this retrospective study, 283 UCB patients who received radical cystectomy or transurethral resection were examined. Immunohistochemistry and immunofluorescence analyses were used to colocalize the expression of stabilin-1 with other markers for Mφs (CD14, CD68, CD163, and CD206). Kaplan–Meier analysis and Cox proportional hazards regression models were applied to estimate overall survival (OS) and recurrence-free survival (RFS).

Results

In UCB tissues, stabilin-1 was primarily expressed on Mφs, as evident from triple immunofluorescence staining for stabilin-1 and Mφ markers. Stabilin-1⁺ Mφs were often more prominent in stromal regions rather than intratumoral regions in UCB tissues (P < 0.0001). After dichotomization at the median cell density for stabilin-1⁺ Mφs, only intratumoral stabilin-1⁺ Mφ density was a predictor of poor OS (P < 0.001) and RFS (P = 0.026). Moreover, intratumoral stabilin-1⁺ Mφ density was positively associated with tumor stage (P < 0.01) and histological grade (P < 0.01), and emerged as an independent prognostic factor for OS (HR 2.371; P < 0.0001), but not for RFS (HR 1.491; P = 0.061).

Conclusions

Our findings indicate that intratumoral stabilin-1⁺ Mφs could potentially be used as a pro-tumoral prognostic marker for UCB patients.

Electronic supplementary material

The online version of this article (10.1007/s00345-019-02853-0) contains supplementary material, which is available to authorized users.

Interaction of tumor-associated macrophages and cancer chemotherapy

It has been recently recognized that the tumor microenvironment (TME) is an essential factor that defines the efficiency of chemotherapy. The local TME, consisting of immune cells with diverse phenotypes and functions, can strongly modulate the response to chemotherapy. Tumor-associated macrophages (TAMs) that display pronounced heterogeneity and phenotypic plasticity are the major innate immune component in the microenvironment of solid tumors. In our review, we elucidate the complex role of TAMs in the progression of different types of solid tumors, summarize the current knowledge about the effects of different anticancer chemotherapeutic agents on monocytes/macrophages, and describe the mechanisms of chemotherapy resistance mediated by TAMs.

Interaction of tumor-associated macrophages and cancer chemotherapy

It has been recently recognized that the tumor microenvironment (TME) is an essential factor that defines the efficiency of chemotherapy. The local TME, consisting of immune cells with diverse phenotypes and functions, can strongly modulate the response to chemotherapy. Tumor-associated macrophages (TAMs) that display pronounced heterogeneity and phenotypic plasticity are the major innate immune component in the microenvironment of solid tumors. In our review, we elucidate the complex role of TAMs in the progression of different types of solid tumors, summarize the current knowledge about the effects of different anticancer chemotherapeutic agents on monocytes/macrophages, and describe the mechanisms of chemotherapy resistance mediated by TAMs.

Not CD68 but stabilin-1 expression is associated with the risk of recurrence in patients with oral cavity squamous cell carcinoma

BACKGROUND

This study's aim was to identify CD68 and stabilin-1 expressions and their prognostic implications in patients with oral cavity cancer (OCC).

METHODS

Stabilin-1 and CD68 immunochemical staining was conducted in samples from patients with OCC who underwent curative surgery in our institute. We retrospectively analyzed patients' clinical information. We investigated the relationship between CD68 and stabilin-1 expression levels and their effect on prognostic factors and survival.

RESULTS

Fifty-four patients' data were analyzed. CD68 and stabilin-1 expressions were positively correlated (P = .008). CD68 and stabilin-1 expressions were not correlated with other prognostic factors (eg, T classification or lymph node metastasis). Stabilin-1 expression and tumor recurrence risk were positively correlated (P = .015). CD68 expression was neither associated with recurrence-free nor OCC-specific survival.

CONCLUSION

CD68 and stabilin-1 expressions in OCC were positively correlated. Stabilin-1 expression was significantly associated with OCC recurrence risk, but the prognostic value of CD68 was not confirmed.

Breaking through to the Other Side: Microenvironment Contributions to DCIS Initiation and Progression

Refinements in early detection, surgical and radiation therapy, and hormone receptor-targeted treatments have improved the survival rates for breast cancer patients. However, the ability to reliably identify which non-invasive lesions and localized tumors have the ability to progress and/or metastasize remains a major unmet need in the field. The current diagnostic and therapeutic strategies focus on intrinsic alterations within carcinoma cells that are closely associated with proliferation. However, substantial accumulating evidence has indicated that permissive changes in the stromal tissues surrounding the carcinoma play an integral role in breast cancer tumor initiation and progression. Numerous studies have suggested that the stromal environment surrounding ductal carcinoma in situ (DCIS) lesions actively contributes to enhancing tumor cell invasion and immune escape. This review will describe the current state of knowledge regarding the mechanisms through which the microenvironment interacts with DCIS lesions focusing on recent studies that describe the contributions of myoepithelial cells, fibroblasts and immune cells to invasion and subsequent progression. These mechanisms will be considered in the context of developing biomarkers for identifying lesions that will progress to invasive carcinoma and/or developing approaches for therapeutic intervention.

Prognostic significance of infiltrating immune cell subtypes in invasive ductal carcinoma of the breast

PURPOSE

To explore the correlation between tumor-infiltrating immune cell subsets and breast cancer prognosis.

MATERIALS AND METHODS

Specimens of 102 patients with invasive ductal carcinoma of the breast were analyzed for immune-related markers (CD8, CD20, FOXP3 and CD68). The number of positive cells in the 3 most highly stained intratumoral stroma areas of the primary tumor was counted. The mean number was calculated and used to divide patients into 2 groups for each marker (CD8-high/CD8-low, CD20-high/CD20-low, FOXP3-high/FOXP3-low, and CD68-high/CD68-low).

RESULTS

Kaplan-Meier survival analysis showed (a) for all patients that high tumor-infiltrating CD8+ and CD20+ B lymphocytes, low tumor-infiltrating FOXP3+ regulatory T cells (Tregs), and CD68+ macrophages all increased OS and DFS (p<0.05); (b) for both the 35 ER-negative and 45 lymph-node-negative patients, high CD8+ cytotoxic T lymphocytes (CTLs) increased OS and DFS (p<0.05). Multivariate analysis of OS and DFS showed that for all patients high CD8+ CTLs and low FOXP3+ Tregs were related to good OS and DFS (p<0.05).

CONCLUSION

High numbers of tumor-infiltrating CD8+ and low numbers of FOXP3+ T lymphocytes both could function as potential independent prognostic markers for invasive ductal breast carcinoma.

Tumor-associated macrophages in human breast cancer produce new monocyte attracting and pro-angiogenic factor YKL-39 indicative for increased metastasis after neoadjuvant chemotherapy

In breast cancer, the tumor microenvironment plays a critical role in the tumor progression and responses to therapy. Tumor-associated macrophages (TAMs) are major innate immune cells in tumor microenvironment that regulate intratumoral immunity and angiogenesis by secretion of cytokines, growth factors as well as chitinase-like proteins (CLPs), that combine properties of cytokines and growth factors. YKL-39 is a chitinase-like protein found in human and absent in rodents, and its expression in TAMs and role in breast cancer progression was not studied to date. Here for the first time we demonstrate that YKL-39 is expressed on TAMs, predominantly positive for stabilin-1, but not by malignant cells or other stromal cells in human breast cancer. TGF-beta in combination with IL-4, but not IL-4 alone was responsible of the stimulation of the production of YKL-39 in human primary macrophages. Mechanistically, stabilin-1 directly interacted with YKL-39 and acted as sorting receptor for targeting YKL-39 into the secretory pathway. Functionally, purified YKL-39 acted as a strong chemotactic factor for primary human monocytes, and induced angiogenesis in vitro. Elevated levels of YKL-39 expression in tumors after neoadjuvant chemotherapy (NAC) were predictive for increased risk of distant metastasis and for poor response to NAC in patients with nonspecific invasive breast carcinoma. Our findings suggest YKL-39 as a novel therapeutic target, and blocking of its activity can be combined with NAC in order to reduce the risk of metastasis in breast cancer patients.

Prognostic significance of tumor-associated macrophages in breast cancer: a meta-analysis of the literature

Purpose

Tumor associated macrophages (TAMs) are important prognostic factors and have been proved to be associated with the invasion and migration of various cancer. However, the relationship between TAMs and breast cancer outcomes remains unclear.

Experimental Design

Sixteen studies with a total of 4,541 breast cancer patients were included in this meta-analysis. Correlation of TAMs with overall survival (OS), disease-free survival(DFS), relapse-free survival (RFS), breast cancer special survival (BCSS) and clinicopathological features were analyzed. Survival data and clinicopathological value were integrated by analyzing hazard ratio(HR) and odds ratio(OR) separately and using Fixed-effect or Random-effect model according to heterogeneity. All statistical tests were two-sided.

Results

OS and DFS were correlated with high density of TAMs with HR= 1.504(1.200, 1.884)/ 2.228(1.716, 2.892) respectively. And subgroup analysis of location and biomarker in OS and DFS group showed prognosis was associated with TAMs distribution and biomarker selection. Besides, TAMs high infiltration was significantly related to age, size, histologic grade, ER/PR status, basal phenotype and vascular invasion.

Conclusion

High density of TAMs was associated with poor survival rates of breast cancer. TAMs in stroma are associated with worse outcome than that in nest and using CD68 as a biomarker for TAMs to evaluate the risk is better than CD163 or CD206 alone. Moreover, high infiltration of TAMs was significantly associated with negative hormone receptor status and malignant phenotype. TAMs infiltration can serve as a novel prognostic factor in breast cancer patients.

Targeting myeloid cells in the tumor sustaining microenvironment

Myeloid cells are the most abundant cells in the tumor microenvironment (TME). The tumor recruits and modulates endogenous myeloid cells to tumor-associated macrophages (TAM), dendritic cells (DC), myeloid-derived suppressor cells (MDSC) and neutrophils (TAN), to sustain an immunosuppressive environment. Pathologically overexpressed mediators produced by cancer cells like granulocyte-macrophage colony-stimulating- and vascular endothelial growth factor induce myelopoiesis in the bone marrow. Excess of myeloid cells in the blood, periphery and tumor has been associated with tumor burden. In cancer, myeloid cells are kept at an immature state of differentiation to be diverted to an immunosuppressive phenotype. Here, we review human myeloid cells in the TME and the mechanisms for sustaining the hallmarks of cancer. Simultaneously, we provide an introduction into current and novel therapeutic approaches to redirect myeloid cells from a cancer promoting to a rather inflammatory, cancer inhibiting phenotype. In addition, the role of platelets for tumor promotion is discussed.

The effect of neoadjuvant chemotherapy on the correlation of tumor-associated macrophages with CD31 and LYVE-1

Angiogenesis and lymphangiogenesis play a crucial role in tumor growth, invasion and metastasis. Tumor-associated macrophages (TAM) induce both angiogenesis and lymphangiogenesis in mouse breast cancer models and positively correlate with these processes in human breast cancer patients. Neoadjuvant chemotherapy (NAC) is a widely used therapeutic option for cancer treatment. However, the effect of NAC on the distribution of TAM within intratumoral compartments and their correlation with angiogenesis and lymphangiogenesis remained unknown. In the present study we analyzed the effect of NAC on the distribution of CD68+ and stabilin-1+ TAM in five functionally distinct areas of human breast cancer and their correlations with microvessel density (MVD) and lymphatic microvessel density (LMVD), identified by CD31 and LYVE1, respectively. We found that NAC enhances blood vessel density in soft fibrous stroma and in coarse fibrous stroma. Without NAC the amount of CD68+ TAM in gaps of ductal tumor structures positively correlate with CD31+ microvessel density in soft fibrous stroma. NAC had enhancing effect on the amount of CD68+ TAM but not stabilin-1+ TAM in soft fibrous stroma. However, no correlation between TAM and CD31+ microvessel density was identified after NAC. NAC did not enhance the lymphatic microvessel density. But after NAC stabilin-1 expressing subpopulation of TAM positively correlated with expression of LYVE-1. We hypothesized that CD68+ TAM can support tumor angiogenesis primarily before NAC, while stabilin-1+ TAM can contribute to the maintenance of lymphatic microvessel density after NAC.

Intratumoral heterogeneity of macrophages and fibroblasts in breast cancer is associated with the morphological diversity of tumor cells and contributes to lymph node metastasis

Recent studies have highlighted the heterogeneity of the tumor microenvironment (ME) and the importance of its analysis to the understanding of its impact on clinical outcomes. In this study, we aimed to analyze the intratumoral distribution of macrophages and fibroblasts in breast cancer (BC) based on the morphological diversity of tumor cells (tubular, alveolar, solid, trabecular and discrete structures) and the clinicopathological parameters of the disease. Thirty-six patients with invasive breast carcinoma of no special type were included in the study. The distribution of macrophages and fibroblasts in the MEs of different morphological structures was assessed using laser microdissection-assisted quantitative RT-PCR analysis of marker genes and double immunofluorescence staining for the CD68, RS1, aSMA, and FAP proteins. Gene expression microarrays were used to determine the expression of genes involved in the regulation of macrophage and fibroblast phenotypes in different morphological structures. We found that different macrophage and fibroblast subpopulations were simultaneously observed in the MEs of morphologically distinct structures but that the frequency of their detection and number of cells detected varied significantly among these structures. In particular, macrophages and fibroblasts were more frequently detected in the ME of solid structures and were rarely observed in tubular structures. A high number of CD68⁺RS1⁺ macrophages in the ME of solid structures was found to be associated with an increased frequency of lymph node metastasis in luminal B HER2^- BC. In contrast, in luminal B HER2⁺ BC, lymph node involvement was related to the high representation of aSMA⁺FAP⁺ fibroblasts around trabecular structures. Morphologically distinct structures differed in the mechanisms regulating the macrophage and fibroblast phenotypes. The highest number of overexpressed genes controlling macrophage and fibroblast functions was observed in discrete groups of tumor cells, and the lowest number was observed in alveolar and solid structures. Taken together, our findings indicate the heterogeneous distribution of macrophages and fibroblasts in breast tumors and its close relation to the intratumoral morphological diversity of BC and contribution to lymph node metastasis.

Tumor Associated Macrophages in Kidney Cancer

Tumor associated macrophages (TAMs) are an important element of tumor stroma. They originate from blood monocytes attracted by chemokines and cytokines produced by tumor cells and, being instructed by tumor microenvironment, develop into potent tumor-supporting cell population. TAMs were demonstrated to directly stimulate tumor cell proliferation and to promote angiogenesis. Further TAMs provide for efficient immune escape by producing immunosuppressive cytokines and facilitate tumor dissemination by producing extracellular matrix remodeling enzymes. In renal cell carcinoma (RCC), numerous studies were performed for elucidation of the role of TAM in tumor progression. Using pan-macrophages marker CD68 and type 2 macrophage (M2) markers CD163 and CD206, it was demonstrated that increased density of TAMs is associated with poor survival of patients. Although most of the studies are focused on M2 population in RCC, several markers rather typical for type 1 macrophages (M1) were also characterized. Macrophages isolated from RCC tumors were shown to produce proinflammatory cytokines TNFα, IL-1β, IL-6, and CCL2. It can be concluded that RCC is an excellent example of a tumor with hybrid phenotype of TAMs that share both M1 and M2 properties. Moreover, TAMs seem to be an attractive therapeutic target as well. Further investigations are needed for identification of RCC-specific TAM markers with high predictive capacity and/or suitable for therapeutic targeting.

Perspectives for Monocyte/Macrophage-Based Diagnostics of Chronic Inflammation

Low-grade chronic inflammation underlies the development of the most dangerous cardiometabolic disorders including type 2 diabetes and its vascular complications. In contrast to acute inflammation induced by bacteria and viruses, chronic inflammation can be driven by abnormal reaction to endogenous factors, including Th2 cytokines, metabolic factors like advanced glycation end products (AGEs), modified lipoproteins, or hyperglycemia. The key innate immune cells that recognize these factors in blood circulation are monocytes. Inflammatory programming of monocytes which migrate into tissues can, in turn, result into generation of tissue macrophages with pathological functions. Therefore, determination of the molecular and functional phenotype of circulating monocytes is a very promising diagnostic tool for the identification of hidden inflammation, which can precede the development of the pathology. Here we propose a new test system for the identification of inflammatory programming of monocytes: surface biomarkers and ex vivo functional system. We summarize the current knowledge about surface biomarkers for monocyte subsets, including CD16, CCR2, CX3CR1, CD64, stabilin-1 and CD36, and their association with inflammatory human disorders. Furthermore, we present the design of an ex vivo monocyte-based test system with minimal set of parameters as a potential diagnostic tool for the identification of personalized inflammatory responses.

Macrophages: Regulators of the Inflammatory Microenvironment during Mammary Gland Development and Breast Cancer

Macrophages are critical mediators of inflammation and important regulators of developmental processes. As a key phagocytic cell type, macrophages evolved as part of the innate immune system to engulf and process cell debris and pathogens. Macrophages produce factors that act directly on their microenvironment and also bridge innate immune responses to the adaptive immune system. Resident macrophages are important for acting as sensors for tissue damage and maintaining tissue homeostasis. It is now well-established that macrophages are an integral component of the breast tumor microenvironment, where they contribute to tumor growth and progression, likely through many of the mechanisms that are utilized during normal wound healing responses. Because macrophages contribute to normal mammary gland development and breast cancer growth and progression, this review will discuss both resident mammary gland macrophages and tumor-associated macrophages with an emphasis on describing how macrophages interact with their surrounding environment during normal development and in the context of cancer.