Stromal Infiltration of Tumor-Associated Macrophages Conferring Poor Prognosis of Patients with Basal-Like Breast Carcinoma

Tumor associated macrophages in breast cancer progression: implications and clinical relevance

Macrophages represent an immune cell population characterized by high plasticity and a range of properties and functions. Their activation status and specific phenotype are highly associated with their localization and the environmental cues they receive. The roles of macrophages in cancer development are diverse. Despite their antitumor effects at early stages of the disease, their presence in the tumor microenvironment (TME) has been linked to tumor promotion upon disease establishment. Tumor associated macrophages (TAMs) are key components of breast cancer TME and they have been associated with poor clinical outcomes. High TAM densities were found to correlate with tumor progression, increased metastatic potential and poor prognosis. Interestingly, considerably higher levels of TAMs were found in patients with triple negative breast cancer (TNBC)-the most aggressive type of breast cancer-compared to other types. The present review summarizes recent findings regarding the distinct TAM subsets in the TME and TAM involvement in breast cancer progression and metastasis. It highlights the constant interplay between TAMs and breast cancer cells and its major contribution to the progression of the disease, including such aspects as, polarization of macrophages toward a tumor promoting phenotype, induction of epithelial to mesenchymal transition (EMT) in cancer cells and enhancement of cancer stem cell properties. Further, we discuss the clinical relevance of these findings, focusing on how a better delineation of TAM involvement in breast cancer metastasis will facilitate the selection of more efficient treatment options.

Is overexpression of CD163 and CD47 in tumour cells of breast carcinoma implicated in the recruitment of tumour-associated macrophages (TAMs) in tumour microenvironment? immunohistochemical prognostic study

BACKGROUND

Now, targeted therapy and immunotherapy are promoted. tumour -Associated Macrophages (TAMs) are an essential component of immune-response in breast cancer(BC) with prognostic controversy. Additionally, their recruiting factors are still obscure. Purpose:This study aimed to evaluate the prognostic significance of CD163 and CD47 in BC of No Special Type (BC-NST) and to explore their suggested role in recruiting TAMs.

MATERIAL AND METHODS

This immunohistochemical study was conducted on 91 archival specimens of breast cases. Immunoreactivity scores were correlated with TAMs density, clinicopathological data, and survival.

RESULTS

Revealed the highest CD163 expression was detected in the pure DCIS group (p = 0.016), while the highest CD47 expression and high TAMs density were reported in the invasive group (p = 0.008, and p = 0.002 respectively) followed by the DCIS group. In IC-NSTs the CD163 and CD47 scores were associated with poor prognostic parameters like(high grade, advanced stage, distant metastasis, ER negativity,Ki67 index, post-surgical chemotherapy, poor NPI group, high mitotic count, dense infiltration of TAMs, shorter OS). Also, CD47 was associated with the dens infiltration of TAMs in DCIS (p = 0.001). There was a significant correlation between tumour cell expression of CD163 and CD47 in IC-NSTs and DCIS (p = 0.002 and p = 0.009 respectively).

CONCLUSIONS

High CD163 and CD47 expressions in both DCIS andIBC are intimately associated, significantly associated with poor prognosis and are important provoking factors of TAMs.

DNA-dependent protein kinase regulates cytosolic double-stranded DNA secretion from irradiated macrophages to increase radiosensitivity of tumors

BACKGROUND AND PURPOSE

To investigate the molecular mechanism by which irradiated macrophages secrete cytosolic double-stranded DNA (c-dsDNA) to increase radiosensitivity of tumors.

MATERIALS AND METHODS

Irradiated bone marrow-derived macrophages (BMDM) were co-incubated with irradiated EO771 or MC38 cancer cells to determine clonogenic survival. c-dsDNA were measured by agarose gel or enzyme-linked immunosorbent assay. BMDM or cancer cells were analyzed with immunostaining or western blot. Subcutaneously implanted MC38 cells in myeloid-specific Prkdc knockout (KO) mice or littermate control mice were irradiated with 8 Gy to determine radiosensitivity of tumors.

RESULTS

We observed that irradiated BMDM significantly increased radiosensitivity of cancer cells. By performing immunostaining, we found that there was a dose-dependent increase in the formation of c-dsDNA and phosphorylation in DNA-dependent protein kinase (DNA-PK) in irradiated BMDM. Importantly, c-dsDNA in irradiated BMDM could be secreted to the extracellular milieu and this process required DNA-PK, which phosphorylated myosin light chain to regulate the secretion. The secreted c-dsDNA from irradiated BMDM then activated toll-like receptor-9 and subsequent nuclear factor kappa-light-chain-enhancer of activated B cells signaling in the adjacent cancer cells inhibiting radiation-induced DNA double strand break repair. Lastly, we observed that irradiated tumors in vivo had a significantly increased number of tumor-associated macrophages (TAM) with phosphorylated DNA-PK expression in the cytosol. Furthermore, tumors grown in myeloid-specific Prkdc KO mice, in which TAM lacked phosphorylated DNA-PK expression were significantly more radioresistant than those of the wild-type control mice.

CONCLUSIONS

Irradiated macrophages can increase antitumor efficacy of radiotherapy through secretion of c-dsDNA under the regulation of DNA-PK.

Epithelial-to-mesenchymal transition in cancer progression: unraveling the immunosuppressive module driving therapy resistance

Cancer cells undergo phenotypic switching (cancer cell plasticity) in response to microenvironmental cues, including exposure to therapy/treatment. Phenotypic plasticity enables the cancer cells to acquire more mesenchymal traits promoting cancer cells' growth, survival, therapy resistance, and disease recurrence. A significant program in cancer cell plasticity is epithelial-to-mesenchymal transition (EMT), wherein a comprehensive reprogramming of gene expression occurs to facilitate the translational shift from epithelial-to-mesenchymal phenotypes resulting in increased invasiveness and metastasis. In addition, EMT plays a pivotal role in facilitating cancer cells' escape from the body's immune system using several mechanisms, such as the downregulation of major histocompatibility complex-mediated antigen presentation, upregulation of immune checkpoint molecules, and recruitment of immune-suppressive cells. Cancer cells' ability to undergo phenotypic switching and EMT-driven immune escape presents a formidable obstacle in cancer management, highlighting the need to unravel the intricate mechanisms underlying these processes and develop novel therapeutic strategies. This article discusses the role of EMT in promoting immune evasion and therapy resistance. We also discuss the ongoing research on developing therapeutic approaches targeting intrinsic and induced cell plasticity within the immune suppressive microenvironment. We believe this review article will update the current research status and equip researchers, clinicians, and other healthcare professionals with valuable insights enhancing their existing knowledge and shedding light on promising directions for future cancer research. This will facilitate the development of innovative strategies for managing therapy-resistant cancers and improving patient outcomes.

Unique macrophage phenotypes activated by BMP signaling in breast cancer bone metastases

Metastatic breast cancer (mBC) tissue in bone was systematically profiled to define the composition of the tumor microenvironment. Gene expression identified a high myeloid signature of patients with improved survival outcomes. Bone metastases were profiled by spatial proteomics to examine myeloid populations within the stroma that correlated with macrophage functions. Single-cell spatial analysis uncovered macrophage activation in the stroma of mBC bone lesions. Matched BC patient samples of primary breast tumor and bone metastasis tissues were compared for gene expression in the bone, where bone morphogenetic protein 2 (BMP2) was most significantly upregulated. Immune cell changes from breast to bone demonstrated a loss of lymphoid cells but a consistent population of macrophages. BMP-activated macrophages were increased uniquely in bone. Bone marrow-derived macrophage activation coupled with BMP inhibition increased inflammatory responses. Using experimental mouse models of mBC bone metastasis and trained immunity, we found that BMP inhibition restricts progression of metastases early in the macrophage activation state but not after tumors were established in the bone. This study revealed unique myeloid BMP activation states that are distinctly integrated with bone metastases.

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.

The preoperative platelet to neutrophil ratio and lymphocyte to monocyte ratio are superior prognostic indicators compared with other inflammatory biomarkers in ovarian cancer

Background

Previous studies have suggested that the ratios of immune-inflammatory cells could serve as prognostic indicators in ovarian cancer. However, which of these is the superior prognostic indicator in ovarian cancer remains unknown. In addition, studies on the prognostic value of the platelet to neutrophil ratio (PNR) in ovarian cancer are still limited.

Methods

A cohort of 991 ovarian cancer patients was analyzed in the present study. Receiver operator characteristic (ROC) curves were utilized to choose the optimal cut-off values of inflammatory biomarkers such as neutrophil to lymphocyte ratio (NLR), lymphocyte to monocyte ratio (LMR), platelet to lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and PNR. The correlation of inflammatory biomarkers with overall survival (OS) and relapse-free survival (RFS) was investigated by Kaplan-Meier methods and log-rank test, followed by Cox regression analyses.

Results

Kaplan-Meier curves suggested that LMR<3.39, PLR≥181.46, and PNR≥49.20 had obvious associations with worse RFS (P<0.001, P=0.018, P<0.001). Multivariate analysis suggested that LMR (≥3.39 vs. <3.39) (P=0.042, HR=0.810, 95% CI=0.661-0.992) and PNR (≥49.20 vs. <49.20) (P=0.004, HR=1.351, 95% CI=1.103-1.656) were independent prognostic indicators of poor RFS. In addition, Kaplan-Meier curves indicated that PLR≥182.23 was significantly correlated with worse OS (P=0.039).

Conclusion

Taken together, PNR and LMR are superior prognostic indicators compared with NLR, PLR, and SII in patients with ovarian cancer.

Prognostic Role of CD68+ and CD163+ Tumour-Associated Macrophages and PD-L1 Expression in Oral Squamous Cell Carcinoma: A Meta-Analysis

Background: Oral squamous cell carcinoma (OSCC) is a common malignant cancer in humans. An abundance of tumour associated macrophages (TAMs) create an immunosuppressive tumour microenvironment (TME). TAM markers (CD163 and CD68) are seen to serve as prognostic factors in OSCC. PD-L1 has seen to widely modulate the TME but its prognostic significance remains controversial. The aim of this meta-analysis is to evaluate the prognostic role of CD163⁺, CD68⁺ TAMs and PD-L1 in OSCC patients. Methods: Searches in PubMed, Scopus and Web of Science were performed; 12 studies were included in this meta-analysis. Quality assessment of included studies was performed according to REMARK guidelines. Risk of bias across studies was investigated according to the rate of heterogeneity. Meta-analysis was performed to investigate the association of all three biomarkers with overall survival (OS). Results: High expression of CD163⁺ TAMs were associated with poor overall survival (HR = 2.64; 95% Cl: [1.65, 4.23]; p < 0.0001). Additionally, high stromal expression of CD163⁺ TAMs correlated with poor overall survival (HR = 3.56; 95% Cl: [2.33, 5.44]; p < 0.00001). Conversely, high CD68 and PD-L1 expression was not associated with overall survival (HR = 1.26; 95% Cl: [0.76, 2.07]; p = 0.37) (HR = 0.64; 95% Cl: [0.35, 1.18]; p = 0.15). Conclusion: In conclusion, our findings indicate CD163⁺ can provide prognostic utility in OSCC. However, our data suggests CD68⁺ TAMs were not associated with any prognostic relevance in OSCC patients, whereas PD-L1 expression may prove to be a differential prognostic marker dependent on tumour location and stage of progression.

Targeting molecular cross-talk between tumor cells and tumor associated macrophage as therapeutic strategy in triple negative breast cancer

Triple-negative Breast cancer (TNBC) is a subtype of breast cancer (BC) that lacks expression for ER/PR/Her2 receptors and is associated with aggressive disease pathogenesis and the worst prognosis among other subtypes of BC. Accumulating evidence-based studies indicate the high immunogenic ability of TNBC tumors and the applicability of immunotherapeutic strategies to overcome therapy resistance and tumor recurrence in TNBC patients. However, not all TNBC patients respond equally well to current immunotherapies that mainly target the adaptive immune system for tumor rejection. Recent studies are contemplating the efficacy of tumor-associated macrophage (TAM) targeted therapies since these subpopulations of cells comprise one of the major components of tumor-infiltrating immune cells (TIIs) in the TNBC tumor microenvironment (TME) and play an essential role in priming the adaptive immune response mediators towards both antitumorigenic and pro-tumorigenic response facilitated by intercellular cross-talk between tumor cells and TAM populations present within TNBC-TME. The present review discusses these molecular mechanisms and their consequence on the progression of TNBC tumors. Also, the therapeutic strategies targeting candidate genes/pathways involved in molecular cross-talk between TAM-TNBC cells and their impact on the development and progression of TNBC tumors are also discussed.

Breast Cancer Survival Outcomes and Tumor-Associated Macrophage Markers: A Systematic Review and Meta-Analysis

INTRODUCTION

Tumor-associated macrophages (TAMs) in breast cancer are associated with a poor prognosis. Early studies of TAMs were largely limited to the pan-macrophage marker CD68, however, more recently, an increasing number of studies have used CD163, a marker expressed by alternatively activated M2 macrophages and TAM subsets. We hypothesized that CD163-positive (CD163+) TAMs would be a better predictor of survival outcomes in breast cancer compared to CD68+  TAMs.

METHODS

We performed a systematic literature search of trials (from 1900 to August 2020) reporting overall survival (OS) or progression-free survival (PFS), breast cancer-specific survival (BCSS), TAM phenotype, and density. Thirty-two studies with 8446 patients were included. Meta-analyses were carried out on hazard ratios (HRs) for survival outcomes of breast cancer patients with a high density of TAMs (CD68+ and/or CD163+) compared to a low density of TAMs.

RESULTS

A high density of TAMs (CD68+ and/or CD163+) was associated with decreased OS (HR 1.69, 95% CI 1.37-2.07) and reduced PFS (HR 1.64; 95% CI 1.35-1.99). Subgrouping by CD marker type showed a lower OS for high density of CD163+ TAMs (HR 2.24; 95% CI 1.71-2.92) compared to a high density of CD68+  TAMs (HR 1.5; 95% CI 1.12-2). A high density of TAMs (CD68+  and/or CD163+) in triple-negative breast cancer (TNBC) cases was associated with lower OS (HR 2.81, 95% CI 1.35-5.84).

CONCLUSION

Compared to CD68+  TAMs, a high density of CD163+ TAMs that express a similar phenotype to M2 macrophages are a better predictor of poor survival outcomes in breast cancer.

Association of CD206 Protein Expression with Immune Infiltration and Prognosis in Patients with Triple-Negative Breast Cancer

Background: Triple-negative breast cancers (TNBCs) have a worse prognosis, but might respond to immunotherapies. Macrophages are plastic cells that can adopt various phenotypes and functions. Although they are a major immune population in TNBCs, the relationship between tumor-associated macrophages (TAMs) and TNBC progression has been rarely explored, with controversial results. Methods: We evaluated the prognostic impact of TAMs, quantified by immunohistochemistry with anti-CD68, -IRF8, -CD163, and -CD206 antibodies, in a well-described cohort of 285 patients with non-metastatic TNBC. Results: CD68 (p = 0.008), IRF8 (p = 0.001), and CD163 (p < 0.001) expression positively correlated with higher tumor grade, while CD206 was associated with smaller tumor size (p < 0.001). All macrophage markers were associated with higher tumor-infiltrating lymphocyte numbers and PD-L1 expression. Univariate survival analyses reported a significant positive correlation between CD163+ or CD206+ TAMs and relapse-free survival (respectively: HR = 0.52 [0.28−0.97], p = 0.027, and HR = 0.51 [0.31−0.82], p = 0.005), and between CD206+ TAMs and overall survival (HR = 0.54 [0.35−0.83], p = 0.005). In multivariate analysis, there was a trend for an association between CD206+ TAMs and relapse-free survival (HR = 0.63 [0.33−1.04], p = 0.073). Conclusions: These data suggest that CD206 expression defines a TAM subpopulation potentially associated with favorable outcomes in patients with TNBC. CD206 expression might identify an immune TNBC subgroup with specific therapeutic options.

Dynamics of tumor-associated macrophages in a quantitative systems pharmacology model of immunotherapy in triple-negative breast cancer

Quantitative systems pharmacology (QSP) modeling is an emerging mechanistic computational approach that couples drug pharmacokinetics/pharmacodynamics and the course of disease progression. It has begun to play important roles in drug development for complex diseases such as cancer, including triple-negative breast cancer (TNBC). The combination of the anti-PD-L1 antibody atezolizumab and nab-paclitaxel has shown clinical activity in advanced TNBC with PD-L1-positive tumor-infiltrating immune cells. As tumor-associated macrophages (TAMs) serve as major contributors to the immuno-suppressive tumor microenvironment, we incorporated the dynamics of TAMs into our previously published QSP model to investigate their impact on cancer treatment. We show that through proper calibration, the model captures the macrophage heterogeneity in the tumor microenvironment while maintaining its predictive power of the trial results at the population level. Despite its high mechanistic complexity, the modularized QSP platform can be readily reproduced, expanded for new species of interest, and applied in clinical trial simulation.

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A mechanistic model of quantitative systems pharmacology in immuno-oncology

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Dynamics of tumor-associated macrophages are integrated into our previous work

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Conducting in silico clinical trials to predict clinical response to cancer therapy

Tumor-associated mononuclear cells in the tumor bed of triple-negative breast cancer associate with clinical outcomes in the post-neoadjuvant chemotherapy setting

PURPOSE

To evaluate the clinical role of tumor-associated macrophages, including foamy (FM) and hemosiderin-laden macrophages (HLM) in the tumor bed (TB) of triple-negative breast cancer (TNBC) post-neoadjuvant chemotherapy (NACT).

METHODS

We conducted a pathologic review of 129 women, diagnosed with TNBC between 2002 and 2016 at our institute. The residual cancer burden (RCB) was calculated. We estimated the percentage of tumor-infiltrating lymphocytes (TILs) in the core needle biopsy (CNB), and FM, HLM, and TILs (in TB) [the combined cells are designated as tumor-associated mononuclear cells (TAMNC)]. The information on patient demographics, chemotherapy regimen, recurrence-free survival (RFS), and overall survival (OS) was extracted from the medical records.

RESULTS

Pathologic complete response (pCR) was achieved in 34.1% of the women. TILs (10% increment in CNB) only were associated with pCR in the multivariable analysis [odds ratio 1.04 (1.02, 1.06) (p = 0.0003)]. Immune cells associated with better OS included TAMNC (≤ 30%) [hazard ratio (HR) 4.32 (1.93, 9.66) (p = 0.0004)], and FM (0%) [HR 2.30 (1.06, 4.98) (p = 0.036)]. While increased HLM (10% increment) was statistically significant with HR 0.93 and 95% CI (0.88 to 0.98) (p = 0.0061), using a cutoff of 0%, HLM (0%: negative vs. ≥ 1%: positive) achieved only borderline significance with HR 2.05 (0.98, 4.31) (p = 0.058). Similarly, these immune cells were also associated with better RFS: TAMNC (≤ 30%) [HR 4.57 (2.04, 10.21) (p = 0.0002)], FM (0%) [HR 2.80 (1.23, 6.35) (p = 0.014)], and HLM (0%) [HR 2.34 (1.07, 5.11) (p = 0.03)]. TILs (in TB) were not associated with any clinical outcomes.

CONCLUSIONS

Although TILs may play a role in the response to NACT, they may not be critical to the prognosis after NACT. Instead, FM and HLM may assume this role. More studies are warranted.

The Prognostic and Clinical Value of Tumor-Associated Macrophages in Patients With Breast Cancer: A Systematic Review and Meta-Analysis

Background

The prognostic and clinical value of tumor-associated macrophages (TAMs) in patients with breast cancer (BCa) remains unclear. We conducted the current meta-analysis to systematically evaluate the association of CD68+ and CD163+ TAM density with the prognosis and clinicopathologic features of BCa patients.

Methods

Searches of Web of Science, PubMed, and EMBASE databases were performed up to January 31, 2022. The meta-analysis was conducted using hazard risks (HRs) and 95% confidence intervals (CIs) for survival data including overall survival (OS), disease-free survival (DFS), and BCa specific survival. Sensitivity and meta-regression analyses were also conducted to identify the robustness of the pooled estimates.

Results

Our literature search identified relevant articles involving a total of 8,496 patients from 32 included studies. Our analysis indicates that a high CD68+ TAM density in the tumor stoma was significantly linked with poor OS (HR 2.46, 95% CI, 1.83–3.31, P<0.001) and shorter DFS (HR 1.77, 95% CI, 1.08–2.89, P=0.02) compared to low CD68+ TAM density. A significant association was also found in the tumor nest. Analysis of CD163+ TAM density showed similar results (all P<0.001). Notably, the pooled analysis with multivariate-adjusted HRs for OS and DFS also found that a high TAM density was significantly related to poorer outcomes for BCa patients (all P<0.05). In addition, BCa patients with high TAM density were more likely to have larger tumors, no vascular invasion, and positive estrogen receptor expression (all P<0.05).

Conclusion

This meta-analysis indicates that a high CD68+ and CD163+ TAM density is associated with poor OS and shorter DFS in BCa patients. Further clinical studies and in vivo experiments are needed to elucidate the underlying mechanism of TAMs.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022304853, identifier CRD42022304853.

Mitochondrial transcription factor B2 overexpression increases M2 macrophage infiltration via cytosolic mitochondrial DNA-stimulated Interleukin-6 secretion in ovarian cancer

Mitochondrial transcription factor B2 (TFB2M) is a protein modulating both mitochondrial DNA (mtDNA) transcription and compacting. In this study, we explored the expression profile of TFB2M in ovarian cancer, its association with infiltration of tumor-associated macrophages (TAMs), and its influence on macrophage polarization. Serial sections of ovarian cancer tissue arrays were stained to detect TFB2M and CD163 expression. Epithelial ovarian cancer cell line OVISE and CAOV4 were used to assess the influence of TFB2M on IL-6 expression. THP-1 cells were utilized as an in vitro model for macrophage migration and polarization. Results showed that higher TFB2M expression is associated with poor survival in ovarian cancer patients. IHC staining confirmed a moderately positive correlation between TFB2M expression and the infiltration of CD163-positive cells in 68 primary ovarian cancer cases. TFB2M overexpression was associated with increased mtDNA outside the mitochondria and elevated IL-6 expression in ovarian cancer cells. When cytosolic mtDNA was selectively inhibited by DNase I, TFB2M-induced IL-6 upregulation was canceled. TFB2M overexpression could activate the nuclear factor kappa-B (NF-κB) signaling pathway via promoting nucleus entry of p65 and p-p65, which was abrogated by inhibiting cytosolic mtDNA, TLR9, or NF-κB signaling pathway. Conditioned medium from OIVSE cells with TFB2M overexpression could induce macrophage migration and M2 polarization. However, these inducing effects were abrogated by DNase I, TLR9 inhibitor, and anti-IL-6 R pretreatment. In conclusion, this study showed a novel role of TFB2M in the immunosuppressive tumor microenvironment. It promotes M2 macrophage infiltration via a cytosolic mtDNA/TLR9/NF-κB/IL-6 pathway in ovarian cancer.

Aging Leads to Increased Monocytes and Macrophages With Altered CSF-1 Receptor Expression and Earlier Tumor-Associated Macrophage Expansion in Murine Mesothelioma

Increased cancer incidence occurs with the emergence of immunosenescence, highlighting the indispensability of the immune system in preventing cancer and its dysregulation with aging. Tumor-associated macrophages (TAMs) are often present in high numbers and are associated with poor clinical outcomes in solid cancers, including mesothelioma. Monocytes and macrophages from the bone marrow and spleen can respond to tumor-derived factors, such as CSF-1, and initiation of the CSF-1R signaling cascade results in their proliferation, differentiation, and migration to the tumor. Age-related changes occur in monocytes and macrophages in terms of numbers and function, which in turn can impact tumor initiation and progression. Whether this is due to changes in CSF-1R expression with aging is currently unknown and was investigated in this study. We examined monocytes and macrophages in the bone marrow and spleen during healthy aging in young (3–4 months) and elderly (20–24 months) female C57BL/6J mice. Additionally, changes to these tissues and in TAMs were examined during AE17 mesothelioma tumor growth. Healthy aging resulted in an expansion of Ly6C^high monocytes and macrophages in the bone marrow and spleen. CSF-1R expression levels were reduced in elderly splenic macrophages only, suggesting differences in CSF-1R signaling between both cell type and tissue site. In tumor-bearing mice, Ly6C^high monocytes increased with tumor growth in the spleen in the elderly and increased intracellular CSF-1R expression occurred in bone marrow Ly6C^high monocytes in elderly mice bearing large tumors. Age-related changes to bone marrow and splenic Ly6C^high monocytes were reflected in the tumor, where we observed increased Ly6C^high TAMs earlier and expansion of Ly6C^low TAMs later during AE17 tumor growth in the elderly compared to young mice. F4/80^high TAMs increased with tumor growth in both young and elderly mice and were the largest subset of TAMs in the tumor. Together, this suggests there may be a faster transition of Ly6C^high towards F4/80^high TAMs with aging. Amongst TAM subsets, expression of CSF-1R was lowest in F4/80^high TAMs, however Ly6C^low TAMs had higher intracellular CSF-1R expression. This suggests downstream CSF-1R signaling may vary between macrophage subsets, which can have implications towards CSF-1R blockade therapies targeting macrophages in cancer.

Predictive value of collagen in cancer

Cancer is a complex disease and a significant cause of mortality worldwide. Over the course of nearly all cancer types, collagen within the tumor microenvironment influences emergence, progression, and metastasis. This review discusses collagen regulation within the tumor microenvironment, pathological involvement of collagen, and predictive values of collagen and related extracellular matrix components in main cancer types. A survey of predictive tests leveraging collagen assays using clinical cohorts is presented. A conclusion is that collagen has high predictive value in monitoring cancer processes and stratifying by outcomes. New approaches should be considered that continue to define molecular facets of collagen related to cancer.

Transition to invasive breast cancer is associated with progressive changes in the structure and composition of tumor stroma

Ductal carcinoma in situ (DCIS) is a pre-invasive lesion that is thought to be a precursor to invasive breast cancer (IBC). To understand the changes in the tumor microenvironment (TME) accompanying transition to IBC, we used multiplexed ion beam imaging by time of flight (MIBI-TOF) and a 37-plex antibody staining panel to interrogate 79 clinically annotated surgical resections using machine learning tools for cell segmentation, pixel-based clustering, and object morphometrics. Comparison of normal breast with patient-matched DCIS and IBC revealed coordinated transitions between four TME states that were delineated based on the location and function of myoepithelium, fibroblasts, and immune cells. Surprisingly, myoepithelial disruption was more advanced in DCIS patients that did not develop IBC, suggesting this process could be protective against recurrence. Taken together, this HTAN Breast PreCancer Atlas study offers insight into drivers of IBC relapse and emphasizes the importance of the TME in regulating these processes.

Pathophysiological Integration of Metabolic Reprogramming in Breast Cancer

Simple Summary

Tumors exhibit metabolic changes that differentiate them from the normal tissues from which they derive. These metabolic changes favor tumor growth, are primarily induced by cancer cells, and produce metabolic and functional changes in the surrounding stromal cells. There is a close functional connection between the metabolic changes in tumor cells and those that appear in the surrounding stroma. A better understanding of intratumoral metabolic interactions may help identify new vulnerabilities that will facilitate new, more individualized treatment strategies against cancer. We review the metabolic changes described in tumor and stromal cells and their functional changes and then consider, in depth, the metabolic interactions between the cells of the two compartments. Although these changes are generic, we illustrate them mainly with reference to examples in breast cancer.

Abstract

Metabolic changes that facilitate tumor growth are one of the hallmarks of cancer. The triggers of these metabolic changes are located in the tumor parenchymal cells, where oncogenic mutations induce an imperative need to proliferate and cause tumor initiation and progression. Cancer cells undergo significant metabolic reorganization during disease progression that is tailored to their energy demands and fluctuating environmental conditions. Oxidative stress plays an essential role as a trigger under such conditions. These metabolic changes are the consequence of the interaction between tumor cells and stromal myofibroblasts. The metabolic changes in tumor cells include protein anabolism and the synthesis of cell membranes and nucleic acids, which all facilitate cell proliferation. They are linked to catabolism and autophagy in stromal myofibroblasts, causing the release of nutrients for the cells of the tumor parenchyma. Metabolic changes lead to an interstitium deficient in nutrients, such as glucose and amino acids, and acidification by lactic acid. Together with hypoxia, they produce functional changes in other cells of the tumor stroma, such as many immune subpopulations and endothelial cells, which lead to tumor growth. Thus, immune cells favor tissue growth through changes in immunosuppression. This review considers some of the metabolic changes described in breast cancer.

Spatial Metrics of Interaction between CD163-Positive Macrophages and Cancer Cells and Progression-Free Survival in Chemo-Treated Breast Cancer

Tumor-associated macrophages (TAMs) promote progression of breast cancer and other solid malignancies via immunosuppressive, pro-angiogenic and pro-metastatic effects. Tumor-promoting TAMs tend to express M2-like macrophage markers, including CD163. Histopathological assessments suggest that the density of CD163-positive TAMs within the tumor microenvironment is associated with reduced efficacy of chemotherapy and unfavorable prognosis. However, previous analyses have required research-oriented pathologists to visually enumerate CD163+ TAMs, which is both laborious and subjective and hampers clinical implementation. Objective, operator-independent image analysis methods to quantify TAM-associated information are needed. In addition, since M2-like TAMs exert local effects on cancer cells through direct juxtacrine cell-to-cell interactions, paracrine signaling, and metabolic factors, we hypothesized that spatial metrics of adjacency of M2-like TAMs to breast cancer cells will have further information value. Immunofluorescence histo-cytometry of CD163+ TAMs was performed retrospectively on tumor microarrays of 443 cases of invasive breast cancer from patients who subsequently received adjuvant chemotherapy. An objective and automated algorithm was developed to phenotype CD163+ TAMs and calculate their density within the tumor stroma and derive several spatial metrics of interaction with cancer cells. Shorter progression-free survival was associated with a high density of CD163+ TAMs, shorter median cancer-to-CD163+ nearest neighbor distance, and a high number of either directly adjacent CD163+ TAMs (within juxtacrine proximity <12 μm to cancer cells) or communicating CD163+ TAMs (within paracrine communication distance <250 μm to cancer cells) after multivariable adjustment for clinical and pathological risk factors and correction for optimistic bias due to dichotomization.

Tumor Associated Macrophages: Origin, Recruitment, Phenotypic Diversity, and Targeting

The tumor microenvironment (TME) is known to have a strong influence on tumorigenesis, with various components being involved in tumor suppression and tumor growth. A protumorigenic TME is characterized by an increased infiltration of tumor associated macrophages (TAMs), where their presence is strongly associated with tumor progression, therapy resistance, and poor survival rates. This association between the increased TAMs and poor therapeutic outcomes are stemming an increasing interest in investigating TAMs as a potential therapeutic target in cancer treatment. Prominent mechanisms in targeting TAMs include: blocking recruitment, stimulating repolarization, and depletion methods. For enhancing targeting specificity multiple nanomaterials are currently being explored for the precise delivery of chemotherapeutic cargo, including the conjugation with TAM-targeting peptides. In this paper, we provide a focused literature review of macrophage biology in relation to their role in tumorigenesis. First, we discuss the origin, recruitment mechanisms, and phenotypic diversity of TAMs based on recent investigations in the literature. Then the paper provides a detailed review on the current methods of targeting TAMs, including the use of nanomaterials as novel cancer therapeutics.

Fluorinated PLGA-PEG-Mannose Nanoparticles for Tumor-Associated Macrophage Detection by Optical Imaging and MRI

Tumor-associated macrophages (TAMs) promote cancer growth and metastasis, but their role in tumor development needs to be fully understood due to the dynamic changes of tumor microenvironment (TME). Here, we report an approach to visualize TAMs by optical imaging and by Fluorine-19 (19F) magnetic resonance imaging (MRI) that is largely applied to track immune cells in vivo. TAMs are targeted with PLGA-PEG-mannose nanoparticles (NPs) encapsulating perfluoro-15-crown-5-ether (PFCE) as MRI contrast agent. These particles are preferentially recognized and phagocytized by TAMs that overexpress the mannose receptor (MRC1/CD206). The PLGA-PEG-mannose NPs are not toxic and they were up-taken by macrophages as confirmed by in vitro confocal microscopy. At 48 h after intravenous injection of PLGA-PEG-mannose NPs, 4T1 xenograft mice were imaged and fluorine-19 nuclear magnetic resonance confirmed nanoparticle retention at the tumor site. Because of the lack of 19F background in the body, observed 19F signals are robust and exhibit an excellent degree of specificity. In vivo imaging of TAMs in the TME by 19F MRI opens the possibility for detection of cancer at earlier stage and for prompt therapeutic interventions in solid tumors.

Prognostic significance of CD163+ tumor-associated macrophages in colorectal cancer

Background

This study aimed to explore the prognostic significance of tumor-associated macrophage (TAM) infiltration in colorectal cancer (CRC) patients.

Methods

Tissue microarray and immunohistochemistry were used to detect the infiltration of CD163+ TAMs in 209 CRC samples, and the Kaplan–Meier method was used for survival analysis. Cox proportional hazards analysis was used for univariate analysis and multivariate analysis of clinically relevant confounders.

Results

The samples were divided into low-level (n = 105) and high-level infiltration groups (n = 104) by the median number of CD163+ TAMs detected. The overall survival (OS) and disease-free survival (DFS) of CRC patients in the low-level CD163+ TAM infiltration group were longer than those in the high-level CD163+ TAM infiltration group (P < 0.001). Infiltration of CD163+ TAMs in CRC tissues was a negative prognostic factor for CRC patients. Risks of death and disease recurrence for CRC patients in the low-level CD163+ TAM infiltration group were lower than those in the high-level CD163+ TAM infiltration group (HR_OS = 0.183, 95% CI 0.052–0.647, P = 0.008; HR_DFS = 0.191, 95% CI 0.078–0.470, P = 0.000).

Conclusions

The infiltration of CD163+ TAMs in CRC tissue is an independent adverse factor for the prognosis of CRC patients. High-level infiltration of CD163+ TAMs is associated with shorter OS and DFS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02299-y.

M2 tumor-associated macrophages play important role in predicting response to neoadjuvant chemotherapy in triple-negative breast carcinoma

PURPOSE

Two types of macrophages are present in tumor microenvironment. M1 macrophages exhibit potent anti-tumor properties, while M2 macrophages play the pro-tumoral roles. The presence of M2 macrophages is associated with worsened overall survival in triple-negative breast carcinoma (TNBC) patients. However, the relationship between M2 macrophages and response to neoadjuvant chemotherapy (NAC) is unknown.

METHODS

M2 macrophages were investigated on biopsy whole sections from 66 TNBCs treated with NAC by CD163 together with other immune checkpoint markers (PD1, PD-L1 and CD8) using a multi-color immunohistochemical multiplex assay.

RESULTS

Incomplete response was significantly associated with older age, lower PD-L1 expression (tumor and stroma), lower levels of CD8-positive TILs in stroma, but higher level of CD163-positive macrophages, with the level of CD163-positive M2 macrophages in peritumoral area as the strongest factor.

CONCLUSIONS

Our data have demonstrated that the level of CD163-positive M2 macrophages was significantly higher in TNBC patients with incomplete response than patients with complete response, suggesting M2 macrophages' important role in predicting TNBC patients' response to NAC.

The immunological impact of preoperative chemoradiotherapy on the tumor microenvironment of pancreatic cancer

Several therapeutic regimens, including neoadjuvant chemoradiation therapy (NACRT), have been reported to serve as anticancer immune effectors. However, there remain insufficient data regarding the immune response after NACRT in pancreatic ductal adenocarcinoma (PDAC) patients. Data from 40 PDAC patients that underwent surgical resection after NACRT (NACRT group) and 30 PDAC patients that underwent upfront surgery (US group) were analyzed to examine alterations in immune cell counts/distribution using a multiplexed fluorescent immunohistochemistry system. All immune cells were more abundant in the cancer stroma than in the cancer cell nest regardless of preoperative therapy. Although the stromal counts of CD4+ T cells, CD20+ B cells, and Foxp3+ T cells in the NACRT group were drastically decreased in comparison with those of the US group, counts of these cell types in the cancer cell nest were not significantly different between the two groups. In contrast, CD204+ macrophage counts in the cancer stroma were similar between the NACRT and US groups, while those in the cancer cell nests were significantly reduced in the NACRT group. Following multivariate analysis, only a high CD204+ macrophage count in the cancer cell nest remained an independent predictor of shorter relapse-free survival (odds ratio = 2.37; P = .033). NACRT for PDAC decreased overall immune cell counts, but these changes were heterogeneous within the cancer cell nests and cancer stroma. The CD204+ macrophage count in the cancer cell nest is an independent predictor of early disease recurrence in PDAC patients after NACRT.

An Efficient Prognostic Immune Scoring System For Colorectal Cancer Patients With Peritoneal Metastasis

Immunoscore can accurately predict the prognosis of patients with stage I–III colorectal cancer. However, whether it can be used to predict the prognosis of colorectal cancer peritoneal metastases (CRCPM) remains to be validated. We analyzed peritoneal and ovarian metastases in 68 patients with CRCPM. The immunoscore (IS) was based on the infiltration level of CD3+ and CD8+ T cells, whereas the TBM score was derived from the infiltration level of CD3+, CD8+, CD20+ and CD163+ cells to tumor microenvironment (TME). The predictive value of IS and TBM scores for relapse-free survival (RFS) and overall survival (OS) of patients with CRCPM was analyzed using Kaplan Meier curve and Cox multivariate models. Significant difference in the infiltration levels of different immune cell subtypes in primary lesions, peritoneal metastasis and ovarian metastasis were compared using t-test.CRCPM patients with high IS (>1), high TBM1 score (≥2) or high TBM2 score (≥2) had a significantly longer OS (IS: median OS, not reached vs 23 months, p = .0078; TBM1: not reached vs 21.5 months, p = .013; TBM2: 39.3 months vs 15.2 months, p = .001). On the other hand, patients with high IS had a trend of improved RFS (13.4 months vs 11.0 months, p = .067). However, TBM1 and TBM2 score has no predictive utility for RFS. Multivariate analysis revealed that IS, TBM1 and TBM2 can accurately predict OS, but not RFS. Finally, the infiltration level of CD3+ T cells, CD8+ T cells, CD20+ B cells, and CD68+ macrophage was significantly higher in peritoneal metastatic tissue and ovarian metastatic tissue, relative to primary tumor tissues.The IS and TBM score of peritoneal metastases could effectively predict OS of patients with CRCPM. Peritoneal metastasis of colorectal cancer decreased the infiltration level of T and B cells.

Hyperglycemia and Chemoresistance in Breast Cancer: From Cellular Mechanisms to Treatment Response

Female breast cancer is a complex, multifactorial disease. Studies have shown that hyperglycemia is one of the most important contributing factors to increasing the risk of breast cancer that also has a major impact on the efficacy of chemotherapy. At the cellular level, hyperglycemia can promote the proliferation, invasion, and migration of breast cancer cells and can also induce anti-apoptotic responses to enhance the chemoresistance of tumors via abnormal glucose metabolism. In this article, we focus on the latest progress in defining the mechanisms of chemotherapy resistance in hyperglycemic patients including the abnormal behaviors of cancer cells in the hyperglycemic microenvironment and the impact of abnormal glucose metabolism on key signaling pathways. To better understand the advantages and challenges of breast cancer treatments, we explore the causes of drug resistance in hyperglycemic patients that may help to better inform the development of effective treatments.

NR3C2-Related Transcriptome Profile and Clinical Outcome in Invasive Breast Carcinoma

Background

Increasing evidence has indicated that the nuclear receptor subfamily 3 group C member 2 (NR3C2) may be associated with tumorigenesis and patient prognosis for certain types of tumors. However, the clinical significance of NR3C2 is unclear in invasive breast carcinoma (BRCA).

Methods

We used bioinformatics to broadly investigate and obtain a deeper understanding of the prognostic significance between NR3C2 and BRCA. RNA-sequencing data and clinical information of patients with BRCA from the Cancer Genome Atlas database were collected for subsequent analysis. The diagnostic efficacy of NR3C2 was evaluated by calculating the receiver operating characteristic curve. The prognostic value of NR3C2 was evaluated by Kaplan-Meier analysis and Cox regression analysis for patients with BRCA. Moreover, the OSbrca database was used to validate NR3C2 as a prognostic biomarker for BRCA. Gene set enrichment analysis (GSEA) and tumor immune infiltration analysis were conducted to explore the molecular mechanism of NR3C2 in BRCA.

Results

The expression level of NR3C2 in BRCA tissues decreased compared to that in normal breast tissues (P < 0.001). NR3C2 presented good diagnostic efficacy (AUC = 0.908). Moreover, the expression of NR3C2 was verified using the Oncomine database. High expression of NR3C2 was statistically associated with prolonged overall survival (HR = 0.65, 95% CI: 0.47-0.91, and P = 0.012), progression-free interval (HR = 0.68, 95% CI: 0.49-0.95, and P = 0.024), and disease-specific survival (HR = 0.57, 95% CI: 0.36-0.89, and P = 0.015) for patients with BRCA. Besides, the prognostic value of NR3C2 was verified by the OSbrca database. GSEA results suggested that enriched pathways included neuroactive ligand-receptor interaction, focal adhesion, and ECM-receptor interaction. NR3C2 expression was moderately correlated with mast cells and some T cell subsets in BRCA.

Conclusion

NR3C2 is a potential prognostic biomarker that could help clinicians develop more appropriate treatment plans for individual patients with BRCA.

Cytotoxic T cells response with decreased CD4/CD8 ratio during mammary tumors inhibition in rats induced by non-contact electric fields

Background: Breast cancer is the most common cancer in women worldwide and is the leading cause of death in women with cancer. One novel therapy used for breast cancer treatment is non-contact electric fields called electro-capacitive cancer therapy (ECCT) with intermediate frequency (100 kHz) and low intensity (18 Vpp). The objective of this study was to examine the effect of ECCT on mammary tumors growth in rats and observing the immune responses that play a role in fighting the tumor. Methods: Female SD rats were used and divided into four groups, namely control (NINT), placebo (NIT), non- therapy (INT), and therapy (IT) groups with 6 biological replicates in each group. Rats in INT and IT groups were treated with 7,12-dimethylbenz[a]anthracene for mammary tumor induction. Only rats in NIT and IT groups were exposed to ECCT individually for 10 hours per day for 21 days. The size of all tumors was measured with a digital caliper. The distributions of PCNA, ErbB2, caspase-3, CD68, CD4 and CD8-positive cells were observed with immunohistochemistry and scoring with ImageJ. Results: The growth rate of mammary tumors in IT group was significantly lower (p<0.05) than that in the INT group. The number of mitotic figures and the percentage of PCNA, caspase-3, and CD68- positive cells in IT group were significantly lower (p<0.05) than those in INT group. Conversely, the percentage of CD8-positive T cells in IT group was significantly higher (p<0.05) than that in INT group. Moreover, the CD4/CD8 ratio in IT group was decreased. Some tumor tissues were blackened and detached from the surrounding tissue, resulting in an open wound which then healed up upon exposure. Conclusions: Non-contact electric fields exposure showed inhibition on mammary tumor growth in rats while inducing CD8+ T cells that lead to tumor cells death and potentially helps wound healing.

Cytotoxic T cells response with decreased CD4/CD8 ratio during mammary tumors inhibition in rats induced by non-contact electric fields

Background: Breast cancer is the most common cancer in women worldwide and is the leading cause of death amongst women with cancer. One novel therapy used for breast cancer treatment constitutes non-contact electric fields and is called electro-capacitive cancer therapy (ECCT) with intermediate frequency and low intensity. The objective of this study was to examine the effect of ECCT on mammary tumors growth in rats and observing the immune responses that play a role in fighting the tumor. Methods: Female SD rats were used and divided into four groups, namely control (NINT), placebo (NIT), non- therapy (INT), and therapy (IT) groups with 6 biological replicates in each group. Rats in INT and IT groups were treated with 7,12-dimethylbenz[a]anthracene for mammary tumor induction. Only rats in NIT and IT groups were exposed to ECCT individually for 10 hours per day for 21 days. The size of all tumors was measured with a digital caliper. The distributions of PCNA, ErbB2, caspase-3, CD68, CD4, and CD8-positive cells were observed with immunohistochemistry and scoring with ImageJ. Results: The growth rate of mammary tumors in IT group was significantly lower (p<0.05) than that in INT group. The number of mitotic figures and the percentage of PCNA, caspase-3, and CD68-positive cells in IT group were significantly lower (p<0.05) than those in INT group. Conversely, the percentage of CD8-positive T cells in IT group was significantly higher (p<0.05) than that in INT group. Moreover, the CD4/CD8 ratio in IT group was found to have decreased. Some tumor tissues were blackened and detached from the surrounding tissue, resulting in an open wound which then healed upon exposure. Conclusions: Non-contact electric fields exposure showed inhibition on mammary tumor growth in rats while inducing CD8+ T cells, leading to tumor cell death and potentially helping wounds heal.

Photodynamic therapy exploiting the anti-tumor activity of mannose-conjugated chlorin e6 reduced M2-like tumor-associated macrophages

M2-like tumor-associated macrophages (M2-TAMs) in cancer tissues are intimately involved in cancer immunosuppression in addition to growth, invasion, angiogenesis, and metastasis. Hence, considerable attention has been focused on cancer immunotherapies targeting M2-TAMs. However, systemic therapies inhibit TAMs as well as other macrophages important for normal immune responses throughout the body. To stimulate tumor immunity with fewer side effects, we targeted M2-TAMs using photodynamic therapy (PDT), which damages cells via a nontoxic photosensitizer with harmless laser irradiation. We synthesized a light-sensitive compound, mannose-conjugated chlorin e6 (M-chlorin e6), which targets mannose receptors highly expressed on M2-TAMs. M-chlorin e6 accumulated more in tumor tissue than normal skin tissue of syngeneic model mice and was more rapidly excreted than the second-generation photosensitizer talaporfin sodium. Furthermore, M-chlorin e6 PDT significantly reduced the volume and weight of tumor tissue. Flow cytometric analysis revealed that M-chlorin e6 PDT decreased the proportion of M2-TAMs and increased that of anti-tumor macrophages, M1-like TAMs. M-chlorin e6 PDT also directly damaged and killed cancer cells in vitro. Our data indicate that M-chlorin e6 is a promising new therapeutic agent for cancer PDT.

Tumor microenvironment and Oral Squamous Cell Carcinoma: A crosstalk between the inflammatory state and tumor cell migration

OBJECTIVES

To analyze the inflammatory millieu in oral squamous cell carcinoma (OSCC) tumors and the influence of macrophages related-cytokines on the tumor cell migration.

MATERIALS AND METHODS

Inflammatory protein profile and macrophage population (M2/M1 ratio) of human OSCC fragments were analyzed by proteomic analysis and flow cytometry assay respectively. To evaluate the effects of inflammation on OSCC behavior, we analyzed the role of polarized macrophages and cytokines (IL-6, IL-1β and TNF-α) on OSCC cell lines (SCC25 and Cal27) responsiveness by western blotting (cell signaling) and time-lapse (cell migration). Also, it was addressed the crosstalk of IL-6-STAT3 axis with cell migration signaling using a STAT3 inhibitor (Stattic®) and a pull down assay for the RhoGTPase Rac1 activity.

RESULTS

It was observed a ~2 fold predominance of M2 over M1 macrophages and a pro-inflammatory state in OSCC fragments. The M2 conditioned media increased migration speed and directionality of highly invasive OSCC cells (SCC25). OSCC cell lines were responsive to cytokine stimuli (IL6, IL-1β and TNF-α), but only IL-6 increased migration properties of OSCC cells. This effect was dependent on STAT3-phosphorylation levels, which interfered with Rac1 activation levels.

CONCLUSION

Our results suggest that the inflammatory milieu might favor invasion and metastasis of OSCC by the direct effect of macrophage-related cytokines on tumor migration.

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.

Clinical significance of tumor-associated immune cells in patients with oral squamous cell carcinoma

BACKGROUND

The expression of PD-L1 in tumor cells and infiltration of tumor-associated immune cells (TAICs) might reflect the tumor biology of head and neck cancer. We aimed to characterize their prognostic roles in oral squamous cell carcinomas (OSCCs).

METHODS

We enrolled 103 OSCC patients who underwent definitive surgery. Immune expression levels of PD-L1, PD-1, CD3, CD4, CD8, and CD68 were assessed in surgically resected specimens. We evaluated the effects of immune marker expression and localization on survival outcomes.

RESULTS

Multivariate analysis results adjusted by the pathological stage, resection margin, and extracapsular extension showed that a high number of PD-1⁺ TAICs and intratumoral CD68⁺ TAICs were independent positive and negative prognostic markers (hazard ratio: 0.20 and 4.15, respectively; P = .02 and .01, respectively).

CONCLUSION

PD-1⁺ TAICs in the tumor microenvironment and CD68⁺ TAICs in the intratumoral area could act as novel biomarkers for predicting overall survival outcomes in OSCC patients.

Emerging role of tumor cell plasticity in modifying therapeutic response

Resistance to cancer therapy is a major barrier to cancer management. Conventional views have proposed that acquisition of resistance may result from genetic mutations. However, accumulating evidence implicates a key role of non-mutational resistance mechanisms underlying drug tolerance, the latter of which is the focus that will be discussed here. Such non-mutational processes are largely driven by tumor cell plasticity, which renders tumor cells insusceptible to the drug-targeted pathway, thereby facilitating the tumor cell survival and growth. The concept of tumor cell plasticity highlights the significance of re-activation of developmental programs that are closely correlated with epithelial-mesenchymal transition, acquisition properties of cancer stem cells, and trans-differentiation potential during drug exposure. From observations in various cancers, this concept provides an opportunity for investigating the nature of anticancer drug resistance. Over the years, our understanding of the emerging role of phenotype switching in modifying therapeutic response has considerably increased. This expanded knowledge of tumor cell plasticity contributes to developing novel therapeutic strategies or combination therapy regimens using available anticancer drugs, which are likely to improve patient outcomes in clinical practice.

FOXO1 promotes tumor progression by increased M2 macrophage infiltration in esophageal squamous cell carcinoma

Objective: The transcription factor forkhead box protein O1 (FOXO1) is critical for regulating cytokine and chemokine secretion. However, its function in the tumor microenvironment (TME) remains largely unexplored. In this study, we characterized the prognostic value of FOXO1 and the interaction between tumor-derived FOXO1 and M2 macrophages in esophageal squamous cell carcinoma (ESCC).

Methods: FOXO1 expression and macrophage infiltration in clinical samples and mouse models were quantified using quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry staining. Western blotting, qRT-PCR, and enzyme-linked immunosorbent assay were used to evaluate chemokine ligand 20 (CCL20) and colony stimulating factor 1 (CSF-1) expression in FOXO1(+) and FOXO1(-) tumor cells. Macrophage phenotypes were determined using qRT-PCR, flow cytometry, and RNA sequencing. Transcriptional activity was measured using chromatin immunoprecipitation (ChIP)-qPCR. Tumor viability was investigated using XTT proliferation and foci formation assays.

Results: FOXO1 upregulation in tumor tissues was found to drive the polarization of M0 macrophages and infiltration of M2 macrophages into the TME, resulting in worse prognosis in ESCC patients. CSF-1, a vital factor inducing M0-to-M2 polarization, was upregulated via a FOXO1-mediated mechanism. RNA sequencing results corroborated that the FOXO1-induced macrophages exhibited similar molecular signatures to the IL4-stimulated M2 macrophages. The transwell assays showed that FOXO1 promoted the migration of M2 macrophages via CCL20 secretion, which could be inhibited using an anti-CCL20 antibody. FOXO1(+) tumor-induced M2 macrophages promoted tumor proliferation via the FAK-PI3K-AKT pathway and the PI3K inhibitor could effectively impede the oncogenical process.

Conclusions: FOXO1 facilitated M0-to-M2 polarization and the recruitment of M2 macrophages in the TME via the transcriptional modulation of CCL20 and CSF-1. Our data deciphered the FOXO1-dependent mechanism in M2 macrophage infiltration in the TME of ESCC, which has implications for the development of novel prognostic and therapeutic targets to optimize the current treatment against ESCC.

Prognostic Role of Immune Markers in Triple Negative Breast Carcinoma

Tumor immune microenvironment (TIME) is a significant prognostic parameter for triple negative breast carcinomas (TNBC) due to being a target for immunotherapeutic agents and its essential role during the cancer immunoediting process. In this study, CD8, FOXP3, CD163, PD-L1/SP142 and PD-L1/SP263 antibodies were examined in a sample of 51 TNBC cases. Patients who received neoadjuvant therapy were excluded. CD8, FOXP3 and CD163 antibodies were evaluated separately in intratumoral area (ITA) and tumor stroma (TS). PD-L1 status was also examined in tumor cells (TC) and immune cells (IC) using both SP142 and SP263 antibodies. In multivariate Cox regressions, the only antibody that was found to be significantly associated with survival was SP142. SP142-positivity in TC and IC was related to increased overall survival. Higher CD163 expression in ITA and SP263-positivity in IC were associated with younger age. Lymphatic/angioinvasion was more frequent in cases with negative/low CD8 and FOXP3 expressions. Moreover, metastatic axillary lymph node(s) was associated with negative/low FOXP3 expression in TS. CD8, FOXP3, CD163, SP142 and SP263 expressions were positively correlated with each other, except a mild discordance caused by CD163 in ITA. Although PD-L1 status with both SP142 and SP263 antibodies were concordant in the majority of cases, 33.3% and 13.7% of the cases showed SP142-negative/SP263-positive pattern in TC and IC respectively. In conclusion, we suggest that composition, density and localization of the immune cells and the check point molecules are important prognostic parameters in TNBC. Immunohistochemistry can be used as an accessible and less expensive tool to demonstrate TIME.

CD68- and CD163-positive tumor-associated macrophages in triple negative cancer of the breast

Tumor-associated macrophages (TAMs) have recently been reported as an important factor in tumor growth and the progression of cancer. The prognostic significance of localizations and densities of TAMs in triple negative cancer (TNC) of the breast is not well understood. The aim of this study was to assess the localizations and densities of the TAMs subtype in TNC and examine their clinicopathological features. The study was based on 107 TNC cases operated on at Dokkyo Medical University Hospital using the pan-macrophage marker CD68 and the M2 macrophage marker CD163 in the tumor stroma (TS) and tumor nest (TN), respectively, and examined the clinicopathological significance. Multivariate Cox regression analyses revealed that age and CD163+ TAMs in both the TS and TN were independent prognostic factors for relapse-free survival and overall survival. No correlation was found between the number of CD68+ cells or the CD163/CD68 ratio either in TS or TN, or clinicopathological features. Our study found that infiltration of CD163+ TAMs, rather than CD68+, in both TS and TN was associated with poor prognosis in TNC patients by multivariate analysis. This suggests that CD163+ TAMs may affect the prognosis of TNC by not only regulating the immune reaction by TAMs in TS, but also because of their direct influence on TN.

Breast Tumor Microenvironment: Emerging target of therapeutic phytochemicals

Triple negative breast cancer (TNBC) is the most aggressive and challenging form of breast cancers. Tumor microenvironment (TME) of TNBC is associated with induction of metastasis, immune system suppression, escaping immune detection and drug resistance. TME is highly complex and heterogeneous, consists of tumor cells, stromal cells and immune cells. The rapid expansion of tumors induce hypoxia, which concerns the reprogramming of TME components. The reciprocal communication of tumor cells and TME cells predisposes cancer cells to metastasis by modulation of developmental pathways, Wnt, notch, hedgehog and their related mechanisms in TME. Dietary phytochemicals are non-toxic and associated with various human health benefits and remarkable spectrum of biological activities. The phytochemicals serve as vital resources for drug discovery and also as a source for breast cancer therapy. The novel properties of dietary phytochemicals propose platform for modulation of tumor signaling, overcoming drug resistance, and targeting TME. Therefore, TME could serve as promising target for the treatment of TNBC. This review presents current status and implications of experimentally evaluated therapeutic phytochemicals as potential targeting agents of TME, potential nanosystems for targeted delivery of phytochemicals and their current challenges and future implications in TNBC treatment. The dietary phytochemicals especially curcumin with significant delivery system could prevent TNBC development as it is considered safe and well tolerated in phase II clinical trials.

Modeling chemical effects on breast cancer: the importance of the microenvironment in vitro

Accumulating evidence suggests that our ability to predict chemical effects on breast cancer is limited by a lack of physiologically relevant in vitro models; the typical in vitro breast cancer model consists of the cancer cell and excludes the mammary microenvironment. As the effects of the microenvironment on cancer cell behavior becomes more understood, researchers have called for the integration of the microenvironment into in vitro chemical testing systems. However, given the complexity of the microenvironment and the variety of platforms to choose from, identifying the essential parameters to include in a chemical testing platform is challenging. This review discusses the need for more complex in vitro breast cancer models and outlines different approaches used to model breast cancer in vitro. We provide examples of the microenvironment modulating breast cancer cell responses to chemicals and discuss strategies to help pinpoint what components should be included in a model.

Pathologic assessment of tumor-associated macrophages and their histologic localization in invasive breast carcinoma

BACKGROUND

Tumor-associated macrophages (TAMs) are important in regulating cross-talk between tumor cells and tumor microenvironment. TAMs are involved in multiple steps of tumor progression and invasion. This study aimed to compare CD163 expression with the widely used CD68 pan-macrophage marker in invasive breast carcinoma. Furthermore, it focused on assessing the significance of TAMs localization in relation to clinicopathological parameters.

RESULTS

CD68 and CD163 immunohistochemical expressions within TAMs infiltrating both tumor nest (TN) and tumor stroma (TS) were evaluated in 60 specimens with invasive breast carcinoma. High CD68-positive stromal TAMs was significantly related to larger tumor, nodal metastasis and vascular invasion (p = 0.003, 0.037, 0.032, respectively), whereas high CD163-positive stromal TAMs was significantly related to larger tumors, nodal metastasis, stage III tumors, vascular invasion, estrogen receptor (ER) negativity, and triple-negative subtype (p = 0.023, < 0.001, 0.001, 0.022, 0.002, 0.017, respectively). On multivariate analysis, high CD68-positive TAMs infiltrating TS was significantly associated with larger tumor and positive nodal metastasis (p = 0.006 and 0.016, respectively), whereas high CD163 TAMs density within TS was significantly associated with positive vascular invasion, nodal metastasis, and molecular subtypes (p = 0.003, 0.001, and 0.009, respectively).

CONCLUSION

TAMs within tumor stroma and tumor nest have different levels of association with poor prognostic parameters. So, it is of great importance to consider the histologic localization of TAMs in addition to the degree of TAMs infiltration.

Evaluating the Polarization of Tumor-Associated Macrophages Into M1 and M2 Phenotypes in Human Cancer Tissue: Technicalities and Challenges in Routine Clinical Practice

Tumor-associated macrophages (TAMs) as immune cells within the tumor microenvironment have gained much interests as basic science regarding their roles in tumor progression unfolds. Better understanding of their polarization into pro-tumoral phenotype to promote tumor growth, tumor angiogenesis, immune evasion, and tumor metastasis has prompted various studies to investigate their clinical significance as a biomarker of predictive and prognostic value across different cancer types. Yet, the methodologies to investigate the polarization phenomena in solid tumor tissue vary. Nonetheless, quantifying the ratio of M1 to M2 TAMs has emerged to be a prevailing parameter to evaluate this polarization phenomena for clinical application. This mini-review focuses on recent studies exploring clinical significance of M1/M2 TAM ratio in human cancer tissue and critically evaluates the technicalities and challenges in quantifying this parameter for routine clinical practice. Immunohistochemistry appears to be the preferred methodology for M1/M2 TAM evaluation as it is readily available in clinical laboratories, albeit with certain limitations. Recommendations are made to standardize the quantification of TAMs for better transition into clinical practice and for better comparison among studies in various populations of patients and cancer types.

Matrix-Targeting Immunotherapy Controls Tumor Growth and Spread by Switching Macrophage Phenotype

The interplay between cancer cells and immune cells is a key determinant of tumor survival. Here, we uncovered how tumors exploit the immunomodulatory properties of the extracellular matrix to create a microenvironment that enables their escape from immune surveillance. Using orthotopic grafting of mammary tumor cells in immunocompetent mice and autochthonous models of breast cancer, we discovered how tenascin-C, a matrix molecule absent from most healthy adult tissues but expressed at high levels and associated with poor patient prognosis in many solid cancers, controls the immune status of the tumor microenvironment. We found that, although host-derived tenascin-C promoted immunity via recruitment of proinflammatory, antitumoral macrophages, tumor-derived tenascin-C subverted host defense by polarizing tumor-associated macrophages toward a pathogenic, immune-suppressive phenotype. Therapeutic monoclonal antibodies that blocked tenascin-C activation of Toll-like receptor 4 reversed this phenotypic switch in vitro and reduced tumor growth and lung metastasis in vivo, providing enhanced benefit in combination with anti-PD-L1 over either treatment alone. Combined tenascin-C:macrophage gene-expression signatures delineated a significant survival benefit in people with breast cancer. These data revealed a new approach to targeting tumor-specific macrophage polarization that may be effective in controlling the growth and spread of breast tumors.

A Review of the Potential Role of Human Cytomegalovirus (HCMV) Infections in Breast Cancer Carcinogenesis and Abnormal Immunity

Previously recognized classical human onco-viruses can regulate complex neoplastic events, and are estimated to play a role during carcinogenesis in 15-20% of cancer cases. Although the DNA and gene products of several viruses have been found in breast tumors, none of the classical onco-viruses have definitely been linked to the initiation of breast cancer. However, recent evidence shows that human cytomegalovirus (HCMV) gene products are found in >90% of tumors and metastases of breast cancers, and their increased expression can be correlated to a more aggressive breast cancer phenotype. Supporting the active role of HCMV in breast cancer, a specific HCMV strain, HCMV-DB, was recently shown to exert oncogenic transformational activity in breast epithelial cells in vitro, and to give rise to fast-growing, triple-negative breast tumors when injected into immune deficient mice. The same observation holds true for clinical studies implying increased HCMV protein expression in triple negative breast cancer biopsies. In addition to functionally being able to hijack tumor-promoting cellular events, HCMV is known to exhibit a wide range of immunosuppressive effects, which can have radical impact on the tumor microenvironment. HCMV infected cells can avoid recognition and elimination by the immune system by orchestrating polarization of immunosuppressive type II macrophages, preventing antigen presentation, by expressing T cell inhibitory molecules, and possibly, by the induction of regulatory T (Treg) cell responses. These actions would be especially deleterious for the antigenic activation and proliferation of tumor specific CD8⁺ cytotoxic T lymphocytes (CTLs), whose effector functions have recently been targeted by successful, experimental immunotherapy protocols. The recognition of alternative causes and drivers of breast cancer is a pivotal research topic for the development of diagnostics and novel, effective preventive and therapeutic strategies targeting both tumor cells and their microenvironments.

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.

Metabolic crosstalk in the breast cancer microenvironment

During tumorigenesis, breast tumour cells undergo metabolic reprogramming, which generally includes enhanced glycolysis, tricarboxylic acid cycle activity, glutaminolysis and fatty acid biosynthesis. However, the extension and functional importance of these metabolic alterations may diverge not only according to breast cancer subtypes, but also depending on the interaction of cancer cells with the complex surrounding microenvironment. This microenvironment comprises a variety of non-cancerous cells, such as immune cells (e.g. macrophages, lymphocytes, natural killer cells), fibroblasts, adipocytes and endothelial cells, together with extracellular matrix components and soluble factors, which influence cancer progression and are predictive of clinical outcome. The continuous interaction between cancer and stromal cells results in metabolic competition and symbiosis, with oncogenic-driven metabolic reprogramming of cancer cells shaping the metabolism of neighbouring cells and vice versa. This review addresses current knowledge on this metabolic crosstalk within the breast tumour microenvironment (TME). Improved understanding of how metabolism in the TME modulates cancer development and evasion of tumour-suppressive mechanisms may provide clues for novel anticancer therapeutics directed to metabolic targets.

Differences in intra-tumoral macrophage infiltration and radiotherapy response among intrinsic subtypes in pT1-T2 breast cancers treated with breast-conserving surgery

Breast cancer (BC) intrinsic subtype classification is based on the expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and proliferation marker Ki-67. The expression of these markers depends on both the genetic background of the cancer cells and the surrounding tumor microenvironment. In this study, we explore macrophage traits in cancer cells and intra-tumoral M2-macrophage infiltration (MI) in relation to intrinsic subtypes in non-metastatic invasive BC treated with breast conserving surgery, with and without postoperative radiotherapy (RT). Immunostaining of M2-macrophage-specific antigen CD163 in cancer cells and MI were evaluated, together with ER, PR, HER2, and Ki-67-expression in cancer cells. The tumors were classified into intrinsic subtypes according to the ESMO guidelines. The immunostaining of these markers, MI, and clinical data were analyzed in relation to ipsilateral local recurrence (ILR) as well as recurrence-free (RFS) and disease-free specific (DFS) survival. BC intrinsic subtypes are associated with T-stage, Nottingham Histologic Grade (NHG), and MI. Macrophage phenotype in cancer cells is significantly associated with NHG3-tumors. Significant differences in macrophage infiltration were observed among the intrinsic subtypes of pT1-T2 stage BC. Shorter RFS was observed in luminal B HER2neg tumors after RT, suggesting that this phenotype may be more resistant to irradiation. Ki-67-expression was significantly higher in NHG3 and CD163-positive tumors, as well as those with moderate and high MI. Cancer cell ER expression is inversely related to MI and thus might affect the clinical staging and assessment of BC.

Prognostic value of lymphocyte-to-monocyte ratio in ovarian cancer: a meta-analysis

INTRODUCTION

Prognostic biomarkers are highly needed to properly manage patients with cancer and improve their clinical courses. The relationship between lymphocyte-to-monocyte ratio (LMR) at diagnosis and ovarian cancer prognosis has been extensively studied, but little consensus has been reached regarding its utility as a biomarker of poor outcome. Thus, this study aimed to investigate the potential prognostic value of pretreatment LMR in such patients to shed light on this issue.

METHODS

We searched the scientific databases of MEDLINE, Embase, Cochrane Library, and WangFang for relevant studies about the inflammatory prognostic factor LMR in ovarian cancer, based on specific inclusion and exclusion criteria. The following parameters were analyzed among others: LMR values and respective cut-offs, patient's overall survival (OS) and progression-free survival (PFS), and clinicopathological features.

RESULTS

Eight studies, including 2259 patients, were eligible for inclusion in this meta-analysis. We found that low LMR was associated with both poor OS [Hazard ratio (HR): 1.92; 95% confidence interval (CI): 1.58-2.34; p < 0.001] and PFS (HR: 1.70; 95% CI: 1.54-1.88; p < 0.001). Moreover, our findings revealed that low LMR was correlated with high G2/G3 histological grade (OR: 1.67; 95% CI: 1.26-2.20; p < 0.001) and late III-IV FIGO stage tumors (OR: 3.55; 95% CI: 2.68-4.70; p < 0.001), high serum CA-125 level (OR: 2.18; 95% CI: 1.71-2.77; p < 0.001), and presence of malignant ascites (OR: 1.87; 95% CI: 1.11-3.14; p = 0.02) and lymph node metastases (OR: 1.70; 95% CI: 1.13-2.54; p = 0.01).

CONCLUSION

Pretreatment LMR is a potential prognostic marker of poor outcome in ovarian cancer patients and may thus be important in clinical care and disease control.

Low Preoperative Lymphocyte to Monocyte Ratio Serves as a Worse Prognostic Marker in Patients with Esophageal Squamous Cell Carcinoma Undergoing Curative Tumor Resection

Preoperative lymphocyte to monocyte ratio (LMR) has been considered a prognostic factor in various cancers. However, the application of LMR in the assessment of patients with esophageal squamous cell carcinoma (ESCC) remains controversial. This study aimed to investigate whether preoperative LMR could serve as a prognostic marker in patients with ESCC undergoing curative tumor resection. Medical records of 680 patients of ESCC after curative surgery without preoperative adjuvant therapy were obtained. The median of LMR was determined as the optimal cut off value. The association of LMR with clinical features of ESCC was analyzed using chi-square tests. Spearman's correlation coefficient was used to calculate the correlation. Disease-free survival (DFS) and overall survival (OS) stratified by LMR were evaluated using Kaplan-Meier method and log-rank test. The LMR was negatively correlated with sex (r=-0.245, P<0.001). Low LMR (LMR<3.17) predicted a shorter DFS and OS in patients with ESCC. Multivariate analyses revealed that LMR was independently correlated with DFS (hazard ratios 0.854; 95% confidence interval 0.768-0.949; P=0.003) and OS (hazard ratios 0.864; 95% confidence interval 0.779-0.958; P=0.006). Our study indicated that low LMR could serve as an independent worse prognostic marker in patients with ESCC.

Strategies to Interfere with Tumor Metabolism through the Interplay of Innate and Adaptive Immunity

The inflammatory tumor microenvironment is an important regulator of carcinogenesis. Tumor-infiltrating immune cells promote each step of tumor development, exerting crucial functions from initiation, early neovascularization, to metastasis. During tumor outgrowth, tumor-associated immune cells, including myeloid cells and lymphocytes, acquire a tumor-supportive, anti-inflammatory phenotype due to their interaction with tumor cells. Microenvironmental cues such as inflammation and hypoxia are mainly responsible for creating a tumor-supportive niche. Moreover, it is becoming apparent that the availability of iron within the tumor not only affects tumor growth and survival, but also the polarization of infiltrating immune cells. The interaction of tumor cells and infiltrating immune cells is multifaceted and complex, finally leading to different activation phenotypes of infiltrating immune cells regarding their functional heterogeneity and plasticity. In recent years, it was discovered that these phenotypes are mainly implicated in defining tumor outcome. Here, we discuss the role of the metabolic activation of both tumor cells and infiltrating immune cells in order to adapt their metabolism during tumor growth. Additionally, we address the role of iron availability and the hypoxic conditioning of the tumor with regard to tumor growth and we describe the relevance of therapeutic strategies to target such metabolic characteristics.