Mechanisms regulating the recruitment of macrophages into hypoxic areas of tumors and other ischemic tissues

Strontium Functionalized in Biomaterials for Bone Tissue Engineering: A Prominent Role in Osteoimmunomodulation

With the development of bone tissue engineering bio-scaffold materials by adding metallic ions to improve bone healing have been extensively explored in the past decades. Strontium a non-radioactive element, as an essential osteophilic trace element for the human body, has received widespread attention in the medical field due to its superior biological properties of inhibiting bone resorption and promoting osteogenesis. As the concept of osteoimmunology developed, the design of orthopedic biomaterials has gradually shifted from “immune-friendly” to “immunomodulatory” with the aim of promoting bone healing by modulating the immune microenvironment through implanted biomaterials. The process of bone healing can be regarded as an immune-induced procedure in which immune cells can target the effector cells such as macrophages, neutrophils, osteocytes, and osteoprogenitor cells through paracrine mechanisms, affecting pathological alveolar bone resorption and physiological bone regeneration. As a kind of crucial immune cell, macrophages play a critical role in the early period of wound repair and host defense after biomaterial implantation. Despite Sr-doped biomaterials being increasingly investigated, how extracellular Sr²⁺ guides the organism toward favorable osteogenesis by modulating macrophages in the bone tissue microenvironment has rarely been studied. This review focuses on recent knowledge that the trace element Sr regulates bone regeneration mechanisms through the regulation of macrophage polarization, which is significant for the future development of Sr-doped bone repair materials. We will also summarize the primary mechanism of Sr²⁺ in bone, including calcium-sensing receptor (CaSR) and osteogenesis-related signaling pathways.

Macrophage-Encapsulated Bioorthogonal Nanozymes for Targeting Cancer Cells

Macrophages migrate to tumor sites by following chemoattractant gradients secreted by tumor cells, providing a truly active targeting strategy for cancer therapy. However, macrophage-based delivery faces challenges of cargo loading, control of release, and effects of the payload on the macrophage vehicle. We present a strategy that employs bioorthogonal "nanozymes" featuring transition metal catalysts (TMCs) to provide intracellular "factories" for the conversion of prodyes and prodrugs into imaging agents and chemotherapeutics. These nanozymes solubilize and stabilize the TMCs by embedding them into self-assembled monolayer coating gold nanoparticles. Nanozymes delivered into macrophages were intracellularly localized and retained activity even after prolonged (72 h) incubation. Significantly, nanozyme-loaded macrophages maintained their inherent migratory ability toward tumor cell chemoattractants, efficiently killing cancer cells in cocultures. This work establishes the potential of nanozyme-loaded macrophages for tumor site activation of prodrugs, providing readily tunable dosages and delivery rates while minimizing off-target toxicity of chemotherapeutics.

Strategies to enhance drug delivery to solid tumors by harnessing the EPR effects and alternative targeting mechanisms

The Enhanced Permeability and Retention (EPR) effect has been recognized as the central paradigm in tumor-targeted delivery in the last decades. In the wake of this concept, nanotechnologies have reached phenomenal levels in research. However, clinical tumors display a poor manifestation of EPR effect. Factors including tumor heterogeneity, complicating tumor microenvironment, and discrepancies between laboratory models and human tumors largely contribute to poor efficiency in tumor-targeted delivery and therapeutic failure in clinical translation. In this article, approaches for evaluation of EPR effect in human tumor were overviewed as guidance to employ EPR effect for cancer treatment. Strategies to augment EPR-mediated tumoral delivery are discussed in different dimensions including enhancement of vascular permeability, depletion of tumor extracellular matrix and optimization of nanoparticle design. Besides, the recent development in alternative tumor-targeted delivery mechanisms are highlighted including transendothelial pathway, endogenous cell carriers and non-immunogenic bacteria-mediated delivery. In addition, the emerging preclinical models better reflect human tumors are introduced. Finally, more rational applications of EPR effect in other disease and field are proposed. This article elaborates on fundamental reasons for the gaps between theoretical expectation and clinical outcomes, attempting to provide some perspective directions for future development of cancer nanomedicines in this still evolving landscape.

Saga of monokines in shaping tumour-immune microenvironment: Origin to execution

Cellular communication mediated by cytokines is an important mechanism dictating immune responses, their cross talk and final immune output. Cytokines play a major role in dictating the immune outcome to cancer by regulating the events of development, differentiation and activation of innate immune cells. Cytokines are pleiotropic in nature, hence understanding their role individually or as member of network cytokines is critical to delineate their role in tumour immunity. Tumour systemically manipulates the immune system to evade and escape immune recognition for their uncontrollable growth and metastasis. The developing tumour comprise a large and diverse set of myeloid cells which are vulnerable to manipulation by the tumour-microenvironment. The innate immune cells of the monocytic lineage skew the fate of the adaptive immune cells and thus dictating cancer elimination or progression. Targeting cells at tumour cite is preposterous owing to their tight network, poor reach and abundance of immunosuppressive mechanisms. Monocytic lineage-derived cytokines (monokines) play crucial role in tumour regression or progression by either directly killing the tumour cells with TNFα or promoting its growth by TGFβ. In addition, the monokines like IL-12, IL-1β, IL-6, IL-10 and TGFβ direct the adaptive immune cells to secrete anti-tumour cytokines, TNFα, IFNγ, perforin and granzyme or pro-tumour cytokines, IL-10 and TGFβ. In this review, we elucidate the roles of monokines in dictating the fate of tumour by regulating responses at various stages of generation, differentiation and activation of immune cells along with the extensive cross talk. We have attempted to delineate the synergy and antagonism of major monokines among themselves or with tumour-derived or adaptive immune cytokines. The review provides an update on the possibilities of placing monokines to potential practical use as cytokine therapy against cancer.

c-Rel-dependent monocytes are potent immune suppressor cells in cancer

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of leukocytes that are important for tumorigenesis and tumor immunotherapy. They comprise up to 10% of leukocytes in the blood of tumor patients and their depletion may be required for successful tumor immunotherapy. However, the identity of MDSCs remains obscure, primarily due to their heterogeneity and lack of a known lineage-specific transcription factor specifying their differentiation. Using single-cell transcriptomics and gene knockout approaches, we now describe a subset of murine and human myeloid suppressor cells, named rel-dependent monocytes (rMos), which are programmed by the transcription factor c-Rel of the NF-κB family. Unlike MDSCs described previously, the c-Rel-dependent monocytes expressed a high amount of the proinflammatory cytokine IL-1β together with a low level of suppressive molecule arginase 1. Both in vitro and in tumor-bearing mice, these c-Rel⁺ IL-1β^hi Arg1^- monocytes promoted tumor growth by potently suppressing T cell function and showed a strong migratory phenotype, all of which were impaired by c-Rel deficiency or inhibition. Mechanistic studies revealed that c-Rel controlled the expression of monocyte signature genes through a unique transcriptional complex called the c-Rel enhanceosome, and IL-1β-CCL2 crosstalk between tumor cells and the rel-dependent monocytes maintained the suppressive tumor microenvironment. Thus, c-Rel specifies the development of a suppressive monocyte population and could be selectively targeted for treating cancer.

Macrophage polarization in hypoxia and ischemia/reperfusion: Insights into the role of energetic metabolism

Macrophages, the key cells of innate immunity, possess wide phenotypical and functional heterogeneity. In vitro studies showed that microenvironment signals could induce the so-called polarization of macrophages into two phenotypes: classically activated macrophages (M1) or alternatively activated macrophages (M2). Functionally, they are considered as proinflammatory and anti-inflammatory/pro-regenerative, respectively. However, in vivo studies into macrophage states revealed a continuum of phenotypes from M1 to M2 state instead of the clearly distinguished extreme phenotypes. An important role in determining the type of polarization of macrophages is played by energy metabolism, including the activity of oxidative phosphorylation. In this regard, hypoxia and ischemia that affect cellular energetics can modulate macrophage polarization. Here, we overview the data on macrophage polarization during metabolic shift-associated pathologies including ischemia and ischemia/reperfusion in various organs and discuss the role of energy metabolism potentially triggering the macrophage polarization.

Hypoxia as a Modulator of Inflammation and Immune Response in Cancer

A clear association between hypoxia and cancer has heretofore been established; however, it has not been completely developed. In this sense, the understanding of the tumoral microenvironment is critical to dissect the complexity of cancer, including the reduction in oxygen distribution inside the tumoral mass, defined as tumoral hypoxia. Moreover, hypoxia not only influences the tumoral cells but also the surrounding cells, including those related to the inflammatory processes. In this review, we analyze the participation of HIF, NF-κB, and STAT signaling pathways as the main components that interconnect hypoxia and immune response and how they modulate tumoral growth. In addition, we closely examine the participation of the immune cells and how they are affected by hypoxia, the effects of the progression of cancer, and some innovative applications that take advantage of this knowledge, to suggest potential therapies. Therefore, we contribute to the understanding of the complexity of cancer to propose innovative therapeutic strategies in the future.

Matrix metalloproteinase-21 promotes metastasis via increasing the recruitment and M2 polarization of macrophages in HCC

MMP-21 is a newly identified member of the matrix metalloproteinase family and has been reported to regulate both embryonic development and tumor progression. However, the roles of MMP-21 in hemofiltrate C-C chemokine (HCC) remain largely unclear. In this study, we used western blot, qPCR and immunohistochemistry (IHC) to determine the upregulation of MMP-21 in HCC tissues, and showed that the increase in MMP-21 was associated with vascular invasion and poor prognosis. Although changing levels of MMP-21 in HCC cell lines had no significant effect on cell migration or invasion abilities in in vitro transwell tests, both IHC analysis and in vivo mouse models proved that upregulated MMP-21 promoted metastasis. Functional enrichments of MMP-21 using The Cancer Genome Atlas (TCGA) data suggested that MMP-21 might regulate metastasis via macrophages. Further experiments proved that MMP-21 enhanced macrophage recruitment by increasing CCL-14 levels and promoted M2-type polarization of macrophage by elevating the expression of CSF-1 and FGF-1. Taken together, this study revealed that MMP-21 controlled the tumor microenvironment remodeling and functional regulation of macrophages to regulate HCC metastasis.

Tenascin-C can Serve as an Indicator for the Immunosuppressive Microenvironment of Diffuse Low-Grade Gliomas

Purpose

The development and progression of glioma are associated with the tumor immune microenvironment. Diffuse low-grade gliomas (LGGs) with higher immunosuppressive microenvironment tend to have a poorer prognosis. The study aimed to find a biological marker that can reflect the tumor immune microenvironment status and predict prognosis of LGGs.

Methods

The target gene tenascin-C (TNC) was obtained by screening the Chinese Glioma Genome Atlas (CGGA) and the Cancer Genome Atlas (TCGA) databases. Then samples of LGGs were collected for experimental verification with immunohistochemistry, immunofluorescence, immunoblotting, quantitative real-time PCR. ELISA was employed to determine the content of TNC in serum and examine its relationship with the tumor immune microenvironment. Eventually, the sensitivity of immunotherapy was predicted on the basis of the content of TNC in LGGs.

Results

In the high-TNC subgroup, the infiltration of immunosuppressive cells was increased (MDSC: r=0.4721, Treg: r=0.3154, etc.), and immune effector cells were decreased [NKT, γδT, etc. (p<0.05)], immunosuppressive factors were elevated [TGF-β, IL10, etc. (p<0.05)], immunostimulatory factors, such as NKG2D, dropped (p<0.05), hypoxia scores increased (p<0.001), and less benefit from immunotherapy (p<0.05). Serum TNC level could be used to assess the status of tumor immune microenvironment in patients with grade II (AUC=0.8571; 95% CI: 0.6541-1.06) and grade III (AUC=0.8333; 95% CI: 0.6334-1.033) glioma.

Conclusions

Our data suggested that TNC could serve as an indicator for the immunosuppressive microenvironment status and the prognosis of LGGs. Moreover, it could also act as a predictor for the effect of immunotherapy on LGG patients.

Multipurposing CARs: Same engine, different vehicles

T cells genetically engineered to recognize and eliminate tumor cells through synthetic chimeric antigen receptors (CARs) have demonstrated remarkable clinical efficacy against B cell leukemia over the past decade. This therapy is a form of highly personalized medicine that involves genetically modifying a patient's T cells to recognize and kill cancer cells. With the FDA approval of 5 CAR T cell products, this approach has been validated as a powerful new drug in the therapeutic armamentarium against cancer. Researchers are now studying how to expand this technology beyond its use in conventional polyclonal αβ T cells to address limitations to the current therapy in cancer and applications beyond it. Considering the specific characteristics of immune cell from diverse lineages, several preclinical and clinical studies are under way to assess the advantages of CAR-redirected function in these cells and apply the lessons learned from CAR T cell therapy in cancer to other diseases.

Leveraging macrophages for cancer theranostics

As fundamental immune cells in innate and adaptive immunity, macrophages engage in a double-edged relationship with cancer. Dissecting the character of macrophages in cancer development facilitates the emergence of macrophages-based new strategies that encompass macrophages as theranostic targets/tools of interest for treating cancer. Herein, we provide a concise overview of the mixed roles of macrophages in cancer pathogenesis and invasion as a foundation for the review discussions. We survey the latest progress on macrophage-based cancer theranostic strategies, emphasizing two major strategies, including targeting the endogenous tumor-associated macrophages (TAMs) and engineering the adoptive macrophages to reverse the immunosuppressive environment and augment the cancer theranostic efficacy. We also discuss and provide insights on the major challenges along with exciting opportunities for the future of macrophage-based cancer theranostic approaches.

Circadian rhythms and cancers: the intrinsic links and therapeutic potentials

The circadian rhythm is an evolutionarily conserved time-keeping system that comprises a wide variety of processes including sleep-wake cycles, eating-fasting cycles, and activity-rest cycles, coordinating the behavior and physiology of all organs for whole-body homeostasis. Acute disruption of circadian rhythm may lead to transient discomfort, whereas long-term irregular circadian rhythm will result in the dysfunction of the organism, therefore increasing the risks of numerous diseases especially cancers. Indeed, both epidemiological and experimental evidence has demonstrated the intrinsic link between dysregulated circadian rhythm and cancer. Accordingly, a rapidly increasing understanding of the molecular mechanisms of circadian rhythms is opening new options for cancer therapy, possibly by modulating the circadian clock. In this review, we first describe the general regulators of circadian rhythms and their functions on cancer. In addition, we provide insights into the mechanisms underlying how several types of disruption of the circadian rhythm (including sleep-wake, eating-fasting, and activity-rest) can drive cancer progression, which may expand our understanding of cancer development from the clock perspective. Moreover, we also summarize the potential applications of modulating circadian rhythms for cancer treatment, which may provide an optional therapeutic strategy for cancer patients.

The Impact of Obesity, Adipose Tissue, and Tumor Microenvironment on Macrophage Polarization and Metastasis

Tumor metastasis is a major cause of death in cancer patients. It involves not only the intrinsic alterations within tumor cells, but also crosstalk between these cells and components of the tumor microenvironment (TME). Tumorigenesis is a complex and dynamic process, involving the following three main stages: initiation, progression, and metastasis. The transition between these stages depends on the changes within the extracellular matrix (ECM), in which tumor and stromal cells reside. This matrix, under the effect of growth factors, cytokines, and adipokines, can be morphologically altered, degraded, or reorganized. Many cancers evolve to form an immunosuppressive TME locally and create a pre-metastatic niche in other tissue sites. TME and pre-metastatic niches include myofibroblasts, immuno-inflammatory cells (macrophages), adipocytes, blood, and lymphatic vascular networks. Several studies have highlighted the adipocyte-macrophage interaction as a key driver of cancer progression and dissemination. The following two main classes of macrophages are distinguished: M1 (pro-inflammatory/anti-tumor) and M2 (anti-inflammatory/pro-tumor). These cells exhibit distinct microenvironment-dependent phenotypes that can promote or inhibit metastasis. On the other hand, obesity in cancer patients has been linked to a poor prognosis. In this regard, tumor-associated adipocytes modulate TME through the secretion of inflammatory mediators, which modulate and recruit tumor-associated macrophages (TAM). Hereby, this review describes the cellular and molecular mechanisms that link inflammation, obesity, and cancer. It provides a comprehensive overview of adipocytes and macrophages in the ECM as they control cancer initiation, progression, and invasion. In addition, it addresses the mechanisms of tumor anchoring and recruitment for M1, M2, and TAM macrophages, specifically highlighting their origin, classification, polarization, and regulatory networks, as well as their roles in the regulation of angiogenesis, invasion, metastasis, and immunosuppression, specifically highlighting the role of adipocytes in this process.

Establishment of a Novel Mouse Hepatocellular Carcinoma Model for Dynamic Monitoring of Tumor Development by Bioluminescence Imaging

In this study, a novel mouse model of hepatocellular carcinoma (HCC) was established by simultaneously knocking out Pten and p53 suppressor genes and overexpressing c-Met and △90-β-catenin proto-oncogenes in the livers of mice via hydrodynamic injection (HDI). The mutations were introduced using the CRISPR/Cas9 and Sleeping Beauty transposon systems. In this way, a primary liver cancer model was established within six weeks. In addition, macrophages expressing arginase-1(Arg1) promoter coupled with firefly luciferase were engineered for bioluminescence imaging (BLI) of the tumor microenvironment. This novel, rapidly-generated model of primary hepatocellular carcinoma can be monitored noninvasively, which can facilitate not only applications of the model, but also the development of new drugs and treatment strategies of HCC.

Ischemic-Trained Monocytes Improve Arteriogenesis in a Mouse Model of Hindlimb Ischemia

OBJECTIVE

Monocytes, which play an important role in arteriogenesis, can build immunologic memory by a functional reprogramming that modifies their response to a second challenge. This process, called trained immunity, is evoked by insults that shift monocyte metabolism, increasing HIF (hypoxia-inducible factor)-1α levels. Since ischemia enhances HIF-1α, we evaluate whether ischemia can lead to a functional reprogramming of monocytes, which would contribute to arteriogenesis after hindlimb ischemia.

METHODS AND RESULTS

Mice exposed to ischemia by 24 hours (24h) of femoral artery occlusion (24h trained) or sham were subjected to hindlimb ischemia one week later; the 24h trained mice showed significant improvement in blood flow recovery and arteriogenesis after hindlimb ischemia. Adoptive transfer using bone marrow-derived monocytes (BM-Mono) from 24h trained or sham donor mice, demonstrated that recipients subjected to hindlimb ischemia who received 24h ischemic-trained monocytes had remarkable blood flow recovery and arteriogenesis. Further, ischemic-trained BM-Mono had increased HIF-1α and GLUT-1 (glucose transporter-1) gene expression during femoral artery occlusion. Circulating cytokines and GLUT-1 were also upregulated during femoral artery occlusion.Transcriptomic analysis and confirmatory qPCR performed in 24h trained and sham BM-Mono revealed that among the 15 top differentially expressed genes, 4 were involved in lipid metabolism in the ischemic-trained monocytes. Lipidomic analysis confirmed that ischemia training altered the cholesterol metabolism of these monocytes. Further, several histone-modifying epigenetic enzymes measured by qPCR were altered in mouse BM-Mono exposed to 24h hypoxia.

CONCLUSIONS

Ischemia training in BM-Mono leads to a unique gene profile and improves blood flow and arteriogenesis after hindlimb ischemia.

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.

Immune tumoral microenvironment in gliomas: focus on CD3+ T cells, Vδ1+ T cells, and microglia/macrophages

Gliomas are histologically defined as low-grade gliomas (LGG) and high-grade gliomas (HGG). The most common type of HGG is the glioblastoma (GBM). We aimed to determine the immunological characteristics of CD3 T-cells, Vδ1 T-cells, and microglia/macrophages infiltrating brain gliomas. We collected 24 formalin-fixed paraffin-embedded samples issued from 19 cases of GBM and 5 cases of LGG. An immunohistochemical analysis was performed using anti-CD3, anti-Vδ1, and anti-iba-1 antibodies. Labelling indexes (LI) of CD3 and Vδ1 were evaluated quantitatively, and other CD3, Vδ1, and iba-1 staining characteristics were evaluated qualitatively. The median age of patients was 49 years in GBM and 52 years in LGG. The sex ratio was 1.4 and GBM predominated in males (p = 0.05). In GBM, the medians of CD3-LI and Vδ1-LI were 30 and 3.5 respectively. CD3-LI inversely correlated with survival in GBM cases (r =  - 0.543; p = 0.016). CD3 staining intensity correlated with CD3-LI (p < 0.0001) and with the survival in GBM cases (p = 0.003). Compared to LGG, the CD3-LI, the intensity of intra-tumoral Vδ1 staining, and the amount of iba-1 were higher in GBM (p = 0.042; p = 0.014; and p = 0.001 respectively). The iba-1 organization was more amoeboid in older patients and more branched in younger patients (p = 0.028) and tended to be more amoeboid in cases with high iba-1 amount (p = 0.09). Our results suggest that a high level of CD3-LI and a strong intra-tumoral infiltration of Vδ1 T-cells as well as a high involvement of TAM can be considered potential markers of poor prognosis of GBM. However, this requires further studies on more balanced GBM-LGG sample, including an expanded panel of biomarkers.

Macrophage membrane coated nanoparticles: a biomimetic approach for enhanced and targeted delivery

The enhanced and targeted drug delivery with low systemic toxicity and subsequent release of drugs is the major concern among researchers and pharmaceutics. Inspite of greater advancement and discoveries in...

Structural Biology of the Tumor Microenvironment

Cancers can be described as "rogue organs" (Balkwill FR, Capasso M, Hagemann T, J Cell Sci 125:5591-5596, 2012) because they are composed of multiple cell types and tissues. The transformed cells can recruit and alter healthy cells from surrounding tissues for their own benefit. It is these interactions that create the tumor microenvironment (TME). The TME describes the cells, factors, and extracellular matrix proteins that make up the tumor and the area around it; the biology of the TME influences tumor progression. Changes in the TME can lead to the growth and development of the tumor, the death of the tumor, or tumor metastasis. Metastasis is the process by which cancer spreads from its initial site to a different part of the body. Metastasis occurs when cancer cells enter the circulatory system or lymphatic system after they break away from a tumor. Once the cells leave, they can travel to a different part of the body and form new tumors. Therefore, understanding the TME is critical to fully understand cancer and find a way to successfully combat it. Knowledge of the TME can better inform researchers of the ability of potential therapies to reach tumor cells. It can also give researchers potential targets to kill the tumor. Instead of directly killing the cancer cells, therapies can target an aspect of the TME which could then halt tumor development or lead to tumor death. In other cases, targeting another aspect of the TME could make it easier for another therapy to kill the cancer cells, for example, using nanoparticles with collagenases to target the collagen in the surrounding environment to expose the cancer cells to drugs (Zinger A, et al, ACS Nano 13(10):11008-11021, 2019).The TME can be split simply into cells and the structural matrix. Within these groups are fibroblasts, structural proteins, immune cells, lymphocytes, bone marrow-derived inflammatory cells, blood vessels, and signaling molecules (Spill F, et al, Curr Opin Biotechnol 40:41-48, 2016; Del Prete A, et al, Curr Opin Pharmacol 35:40-47, 2017; Arneth B, Medicina (Kaunas) 56(1), 2019). From structure to providing nutrients for growth, each of these components plays a critical role in tumor maintenance. Together these components impact cancer growth, development, and resistance to therapies (Hanahan D, Coussens LM, Cancer Cell 21:309-322, 2012). In this chapter, we will describe the TME and express the importance of the cellular and structural elements of the TME.

Multifaceted Roles of Chemokines and Chemokine Receptors in Tumor Immunity

Simple Summary

Various immune cells are involved in host immune responses to cancer. T-helper (Th) 1 cells, cytotoxic CD8⁺ T cells, and natural killer cells are the major effector cells in anti-tumor immunity, whereas cells such as regulatory T cells and myeloid-derived suppressor cells are negatively involved in anti-tumor immunity. Th2 cells and Th17 cells have been shown to have both pro-tumor and anti-tumor activities. The migratory properties of various immune cells are essential for their function and critically regulated by the chemokine superfamily. In this review, we summarize the roles of various immune cells in tumor immunity and their migratory regulation by the chemokine superfamily. We also assess the therapeutic possibilities of targeting chemokines and chemokine receptors in cancer immunotherapy.

Abstract

Various immune cells are involved in host tumor immune responses. In particular, there are many T cell subsets with different roles in tumor immunity. T-helper (Th) 1 cells are involved in cellular immunity and thus play the major role in host anti-tumor immunity by inducing and activating cytotoxic T lymphocytes (CTLs). On the other hand, Th2 cells are involved in humoral immunity and suppressive to Th1 responses. Regulatory T (Treg) cells negatively regulate immune responses and contribute to immune evasion of tumor cells. Th17 cells are involved in inflammatory responses and may play a role in tumor progression. However, recent studies have also shown that Th17 cells are capable of directly inducting CTLs and thus may promote anti-tumor immunity. Besides these T cell subsets, there are many other innate immune cells such as dendritic cells (DCs), natural killer (NK) cells, and myeloid-derived suppressor cells (MDSCs) that are involved in host immune responses to cancer. The migratory properties of various immune cells are critical for their functions and largely regulated by the chemokine superfamily. Thus, chemokines and chemokine receptors play vital roles in the orchestration of host immune responses to cancer. In this review, we overview the various immune cells involved in host responses to cancer and their migratory properties regulated by the chemokine superfamily. Understanding the roles of chemokines and chemokine receptors in host immune responses to cancer may provide new therapeutic opportunities for cancer immunotherapy.

Hypoxia-Related Gene-Based Signature Can Evaluate the Tumor Immune Microenvironment and Predict the Prognosis of Colon Adenocarcinoma Patients

Background

Colon adenocarcinoma (COAD) is a common gastrointestinal tumor and often occurs in the left colon with a poor prognosis. The progression of COAD is closely related to the tumor microenvironment, especially the hypoxia. Currently, few studies have reported the correlation between hypoxia-related genes and the prognosis of COAD patients. Furthermore, we constructed a prognostic model using four hypoxia-related genes to predict the prognosis of COAD patients.

Methods

The mRNA expression profiles and corresponding clinicopathological data were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). The string online analysis tool was used to construct a protein–protein interaction network (PPI) of hypoxia-related genes. Kaplan–Meier curve was used to analyze the relationship of hypoxia risk score and the overall survival of COAD patients, and the receiver operating characteristic (ROC) curve was used to assess the reliability.

Results

We screened out four hypoxia genes, including TKTL1 (transketolase like 1), SLC2A3 (solute carrier family 2 member 3), ALDOB (aldolase, fructose-bisphosphate B) and ENO3 (enolase 3), which were used to construct a hypoxia risk model to predict the overall survival of COAD patients. Besides, we also found that the hypoxia risk score was correlated with the immunosuppression of tumor microenvironment.

Conclusion

The model we constructed with four survival-related hypoxia genes, including TKTL1, SLC2A3, ALDOB and ENO3, could be used to predict the overall survival of COAD patients with high stability.

Understanding and improving cellular immunotherapies against cancer: From cell-manufacturing to tumor-immune models

The tumor microenvironment (TME) is shaped by dynamic metabolic and immune interactions between precancerous and cancerous tumor cells and stromal cells like epithelial cells, fibroblasts, endothelial cells, and hematopoietically-derived immune cells. The metabolic states of the TME, including the hypoxic and acidic niches, influence the immunosuppressive phenotypes of the stromal and immune cells, which confers resistance to both host-mediated tumor killing and therapeutics. Numerous in vitro TME platforms for studying immunotherapies, including cell therapies, are being developed. However, we do not yet understand which immune and stromal components are most critical and how much model complexity is needed to answer specific questions. In addition, scalable sourcing and quality-control of appropriate TME cells for reproducibly manufacturing these platforms remain challenging. In this regard, lessons from the manufacturing of immunomodulatory cell therapies could provide helpful guidance. Although immune cell therapies have shown unprecedented results in hematological cancers and hold promise in solid tumors, their manufacture poses significant scale, cost, and quality control challenges. This review first provides an overview of the in vivo TME, discussing the most influential cell populations in the tumor-immune landscape. Next, we summarize current approaches for cell therapies against cancers and the relevant manufacturing platforms. We then evaluate current immune-tumor models of the TME and immunotherapies, highlighting the complexity, architecture, function, and cell sources. Finally, we present the technical and fundamental knowledge gaps in both cell manufacturing systems and immune-TME models that must be addressed to elucidate the interactions between endogenous tumor immunity and exogenous engineered immunity.

Plasmacytoid dendritic cells recruited by HIF-1α/eADO/ADORA1 signaling induce immunosuppression in hepatocellular carcinoma

Plasmacytoid dendritic cells (pDCs) play immunosuppressive roles in the tumor microenvironment (TME). However, the molecular mechanisms underlying the recruitment and dysfunction of pDCs in the TME remain largely elusive, especially in hepatocellular carcinoma (HCC). In this study, we observed the accumulation of pDCs in the blood, tumor tissue, and ascitic fluid of HCC patients. A high density of tumor-infiltrating pDCs was correlated with poor prognosis in patients with HCC. Hypoxia-induced extracellular adenosine (eADO) significantly enhanced pDC recruitment into tumors via the adenosine A1 receptor (ADORA1). Mechanistically, hypoxia-inducible factor 1-alpha (HIF-1α) transcriptionally upregulated the expression of the ectonucleotidases CD39 and CD73 in HCC cells, both of which are essential for the generation of eADO. Moreover, eADO-stimulated pDCs promoted the induction of regulatory T cells and suppressed proliferation and cytotoxicity of CD8⁺ T cells. Depletion of pDCs using a monoclonal antibody or an ADORA1 antagonist significantly improved antitumor immunity and suppressed HCC growth in the immunocompetent HCC mouse model. Thus, targeting pDC recruitment may serve as a potential adjuvant strategy for immunotherapies in HCC.

The effect of hypoxia on PD-L1 expression in bladder cancer

INTRODUCTION

Recent data has demonstrated that hypoxia drives an immunosuppressive tumour microenvironment (TME) via various mechanisms including hypoxia inducible factor (HIF)-dependent upregulation of programmed death ligand 1 (PD-L1). Both hypoxia and an immunosuppressive TME are targetable independent negative prognostic factors for bladder cancer. Therefore we sought to investigate whether hypoxia is associated with upregulation of PD-L1 in the disease.

MATERIALS AND METHODS

Three human muscle-invasive bladder cancer cell lines (T24, J82, UMUC3) were cultured in normoxia (20% oxygen) or hypoxia (1 and 0.1% oxygen) for 24 h. Differences in PD-L1 expression were measured using Western blotting, quantitative polymerase chain reaction (qPCR) and flow cytometry (≥3 independent experiments). Statistical tests performed were unpaired t tests and ANOVA. For in silico work an hypoxia signature was used to apply hypoxia scores to muscle-invasive bladder cancers from a clinical trial (BCON; n = 142) and TCGA (n = 404). Analyses were carried out using R and RStudio and statistical tests performed were linear models and one-way ANOVA.

RESULTS

When T24 cells were seeded at < 70% confluence, there was decreased PD-L1 protein (p = 0.009) and mRNA (p < 0.001) expression after culture in 0.1% oxygen. PD-L1 protein expression decreased in both 0.1% oxygen and 1% oxygen in a panel of muscle-invasive bladder cancer cells: T24 (p = 0.009 and 0.001), J82 (p = 0.008 and 0.013) and UMUC3 (p = 0.003 and 0.289). Increasing seeding density decreased PD-L1 protein (p < 0.001) and mRNA (p = 0.001) expression in T24 cells grown in both 20 and 1% oxygen. Only when cells were 100% confluent, were PD-L1 protein and mRNA levels higher in 1% versus 20% oxygen (p = 0.056 and p = 0.037). In silico analyses showed a positive correlation between hypoxia signature scores and PD-L1 expression in both BCON (p = 0.003) and TCGA (p < 0.001) cohorts, and between hypoxia and IFNγ signature scores (p < 0.001 for both).

CONCLUSION

Tumour hypoxia correlates with increased PD-L1 expression in patient derived bladder cancer tumours. In vitro PD-L1 expression was affected by cell density and decreased PD-L1 expression was observed after culture in hypoxia in muscle-invasive bladder cancer cell lines. As cell density has such an important effect on PD-L1 expression, it should be considered when investigating PD-L1 expression in vitro.

Targeting Metabolism to Control Immune Responses in Cancer and Improve Checkpoint Blockade Immunotherapy

Over the past decade, advances in cancer immunotherapy through PD1-PDL1 and CTLA4 immune checkpoint blockade have revolutionized the management of cancer treatment. However, these treatments are inefficient for many cancers, and unfortunately, few patients respond to these treatments. Indeed, altered metabolic pathways in the tumor play a pivotal role in tumor growth and immune response. Thus, the immunosuppressive tumor microenvironment (TME) reprograms the behavior of immune cells by altering their cellular machinery and nutrient availability to limit antitumor functions. Today, thanks to a better understanding of cancer metabolism, immunometabolism and immune checkpoint evasion, the development of new therapeutic approaches targeting the energy metabolism of cancer or immune cells greatly improve the efficacy of immunotherapy in different cancer models. Herein, we highlight the changes in metabolic pathways that regulate the differentiation of pro- and antitumor immune cells and how TME-induced metabolic stress impedes their antitumor activity. Finally, we propose some drug strategies to target these pathways in the context of cancer immunotherapy.

Targeting hypoxia and hypoxia-inducible factor-1 in the tumor microenvironment for optimal cancer immunotherapy

The development of new strategies of anticancer immunotherapies has provided promising approaches in the treatment of solid tumors. However, despite the improved survival in responders, most of the patients show incomplete responses with a lack of remarkable clinical improvement. Hypoxia has been identified as a common characteristic of solid tumors contributing to different aspects of tumor progression, including invasion, metastasis, and the creation of the immunosuppressive tumor microenvironment. Hypoxia, through its main mediator, hypoxia-inducible factor-1 (HIF-1) is also associated with the limited efficacy of immunotherapies. Therefore, designing new strategies for immunotherapy implicating therapeutic targeting of HIF-1 molecules may enhance the clinical effectiveness of immunotherapy. Here, we discuss the contribution of hypoxia to the development of the immunosuppressive tumor microenvironment. We will also outline different strategies for targeting hypoxia to provide insight into the therapeutic potential of the application of such strategies to improve the clinical benefit of cancer immunotherapy.

Tumor-Associated Macrophages and Their Functional Transformation in the Hypoxic Tumor Microenvironment

Tumor-associated macrophages (TAMs) are some of the most abundant immune cells within tumors and perform a broad repertoire of functions via diverse phenotypes. On the basis of their functional differences in tumor growth, TAMs are usually categorized into two subsets of M1 and M2. It is well established that the tumor microenvironment (TME) is characterized by hypoxia along with tumor progression. TAMs adopt an M1-like pro-inflammatory phenotype at the early phases of oncogenesis and mediate immune response that inhibits tumor growth. As tumors progress, anabatic hypoxia of the TME gradually induces the M2-like functional transformation of TAMs by means of direct effects, metabolic influence, lactic acidosis, angiogenesis, remodeled stroma, and then urges them to participate in immunosuppression, angiogenesis and other tumor-supporting procedure. Therefore, thorough comprehension of internal mechanism of this TAM functional transformation in the hypoxic TME is of the essence, and might provide some novel insights in hypoxic tumor immunotherapeutic strategies.

M1 macrophage exosomes engineered to foster M1 polarization and target the IL-4 receptor inhibit tumor growth by reprogramming tumor-associated macrophages into M1-like macrophages

M2-polarized, pro-tumoral tumor-associated macrophages (TAMs) express the interleukin-4 receptor (IL4R) at higher levels compared with M1-polarized, anti-tumoral macrophages. In this study, we harnessed M1 macrophage-derived exosomes engineered to foster M1 polarization and target IL4R for the inhibition of tumor growth by reprogramming TAMs into M1-like macrophages. M1 exosomes were transfected with NF-κB p50 siRNA and miR-511-3p to enhance M1 polarization and were surface-modified with IL4RPep-1, an IL4R-binding peptide, to target the IL4 receptor of TAMs (named IL4R-Exo(si/mi). IL4R-Exo(si/mi) were internalized and downregulated target gens in M2 macrophages and decreased M2 markers, while increasing M1 markers, more efficiently compared with untargeted and control peptide-labeled exosomes and exosomes from non-immune, normal cells. Whole-body fluorescence imaging showed that IL4R-Exo(si/mi) homed to tumors at higher levels compared with the liver, unlike untargeted and control peptide-labeled exosomes. Systemic administration of IL4R-Exo(si/mi) inhibited tumor growth, downregulated target genes, and decreased the levels of M2 cytokines and immune-suppressive cells, while increasing the levels of M1 cytokines and immune-stimulatory cells, more efficiently than untargeted and control peptide-labeled exosomes. These results suggest that IL4R-Exo(si/mi) inhibits tumor growth by reprogramming TAMs into M1-like macrophages and increasing anti-tumor immunity, thus representing a novel cancer immunotherapy.

Genome Scale Modeling to Study the Metabolic Competition between Cells in the Tumor Microenvironment

The tumor's physiology emerges from the dynamic interplay of numerous cell types, such as cancer cells, immune cells and stromal cells, within the tumor microenvironment. Immune and cancer cells compete for nutrients within the tumor microenvironment, leading to a metabolic battle between these cell populations. Tumor cells can reprogram their metabolism to meet the high demand of building blocks and ATP for proliferation, and to gain an advantage over the action of immune cells. The study of the metabolic reprogramming mechanisms underlying cancer requires the quantification of metabolic fluxes which can be estimated at the genome-scale with constraint-based or kinetic modeling. Constraint-based models use a set of linear constraints to simulate steady-state metabolic fluxes, whereas kinetic models can simulate both the transient behavior and steady-state values of cellular fluxes and concentrations. The integration of cell- or tissue-specific data enables the construction of context-specific models that reflect cell-type- or tissue-specific metabolic properties. While the available modeling frameworks enable limited modeling of the metabolic crosstalk between tumor and immune cells in the tumor stroma, future developments will likely involve new hybrid kinetic/stoichiometric formulations.

Angiogenesis induction in breast cancer: A paracrine paradigm

Breast cancer is the most prevalent type of cancer among women globally. Angiogenesis contributes significantly to breast cancer progression and dissemination. Neovascularization is concurrent with the progression and growth of breast cancer. Breast cancer cells control angiogenesis by secreting pro-angiogenic factors like fibroblast growth factor, vascular endothelial growth factor, interleukin, transforming growth factor-β, platelet-derived growth factor and several others. These pro-angiogenic factors trigger neovascularization, and thereby lead to breast cancer development and metastasis. The hypoxia-inducible factor (HIF)-regulated angiogenesis cascade is a crucial underlying factor in breast cancer growth and metastasis. To that end, several efforts have been made to identify druggable targets within the HIF-angiogenesis components. However, escape pathways are a major hindrance for targeted therapies against angiogenesis. Thus, understanding the key factors that trigger breast cancer angiogenesis is critical in elucidating ways to inhibit breast cancer. The current review provides an overview of the key growth factors that trigger breast cancer angiogenesis.

Multifunctional biomaterials that modulate oxygen levels in the tumor microenvironment

A characteristic feature of solid tumors is their low oxygen tension, which confers resistance to radiotherapy, photodynamic therapy, and chemotherapy. Therefore, to improve treatment outcomes, it is critical to develop biomaterials capable of targeted modulation of oxygen levels in tumors. In this review, we summarize four types of oxygen-modulating biomaterials, namely, oxygen-carrying biomaterials to deliver oxygen into tumors (e.g., perfluorocarbon and hemoglobin), oxygen-generating biomaterials to promote in situ oxygen generation (e.g., MnO2, catalase, and CuO), oxygen-consuming biomaterials to starve tumors (e.g., photosensitizer, glucose oxidase, and magnesium silicide), and oxygen-circulating biomaterials capable of both providing and consuming oxygen (e.g., ENBS-B). The current literature suggests that these biomaterials are useful for anticancer therapeutics. We present the key molecular mechanisms involved in modulating oxygen levels and the potential applications of these biomaterials in the context of hypoxic tumor treatment.

Hidden Treasures: Macrophage Long Non-Coding RNAs in Lung Cancer Progression

Ever since RNA sequencing of whole genomes and transcriptomes became available, numerous RNA transcripts without having the classic function of encoding proteins have been discovered. Long non-coding RNAs (lncRNAs) with a length greater than 200 nucleotides were considered as "junk" in the beginning, but it has increasingly become clear that lncRNAs have crucial roles in regulating a variety of cellular mechanisms and are often deregulated in several diseases, such as cancer. Lung cancer is the leading cause of cancer-related deaths and has a survival rate of less than 10%. Immune cells infiltrating the tumor microenvironment (TME) have been shown to have a great effect on tumor development with macrophages being the major cell type within the TME. Macrophages can inherit an inflammatory M1 or an anti-inflammatory M2 phenotype. Tumor-associated macrophages, which are predominantly polarized to M2, favor tumor growth, angiogenesis, and metastasis. In this review, we aimed to describe the complex roles and functions of lncRNAs in macrophages and their influence on lung cancer development and progression through the TME.

Multi-Parameter Quantitative Imaging of Tumor Microenvironments Reveals Perivascular Immune Niches Associated With Anti-Tumor Immunity

Tumors are populated by a multitude of immune cell types with varied phenotypic and functional properties, which can either promote or inhibit anti-tumor responses. Appropriate localization and function of these cells within tumors is critical for protective immunity, with CD8 T cell infiltration being a biomarker of disease outcome and therapeutic efficacy. Recent multiplexed imaging approaches have revealed highly complex patterns of localization for these immune cell subsets and the generation of distinct tumor microenvironments (TMEs), which can vary among cancer types, individuals, and within individual tumors. While it is recognized that TMEs play a pivotal role in disease progression, a better understanding of their composition, organization, and heterogeneity, as well as how distinct TMEs are reshaped with immunotherapy, is necessary. Here, we performed spatial analysis using multi-parameter confocal imaging, histocytometry, and CytoMAP to study the microanatomical organization of immune cells in two widely used preclinical cancer models, the MC38 colorectal and KPC pancreatic murine tumors engineered to express human carcinoembryonic antigen (CEA). Immune responses were examined in either unperturbed tumors or after immunotherapy with a CEA T cell bispecific (CEA-TCB) surrogate antibody and anti-PD-L1 treatment. CEA-TCB mono and combination immunotherapy markedly enhanced intra-tumoral cellularity of CD8 T cells, dominantly driven by the expansion of TCF1-PD1+ effector T cells and with more minor increases in TCF1+PD1+ resource CD8 T cells. The majority of infiltrating T cells, particularly resource CD8 T cells, were colocalized with dendritic cells (DCs) or activated MHCII+ macrophages, but largely avoided the deeper tumor nest regions composed of cancer cells and non-activated macrophages. These myeloid cell - T cell aggregates were found in close proximity to tumor blood vessels, generating perivascular immune niches. This perivascular TME was present in untreated samples and markedly increased after CEA-TCB therapy, with its relative abundance positively associated with response to therapy. Together, these studies demonstrate the utility of advanced spatial analysis in cancer research by revealing that blood vessels are key organizational hubs of innate and adaptive immune cells within tumors, and suggesting the likely relevance of the perivascular immune TME in disease outcome.

Decoding the Myeloid-Derived Suppressor Cells in Lymphoid Malignancies

Myeloid-derived suppressor cells (MDSCs) are immature myeloid precursors which emerged as a potent regulator of the immune system, exerting suppressive properties in diverse disease settings. In regards to cancer, MDSCs have an established role in solid tumors; however, their contribution to immune regulation during hematologic malignancies and particularly in lymphomas remains ill-defined. Herein focused on lymphoma, we discuss the literature on MDSC cells in all histologic types, and we also refer to lessons learned by animal models of lymphoma. Furthermore, we elaborate on future directions and unmet needs and challenges in the MDSC field related to lymphoma malignancies which may shed light on the complex nature of the immune system in malignancies.

Nanomedicine Applications in Treatment of Primary Central Nervous System Lymphoma: Current State of the Art

Primary central nervous system lymphoma (PCNSL) is a rare but highly aggressive subtype of extra nodal non-Hodgkin lymphoma (NHL), which is confined in the central nervous system (CNS). Despite recent advancements in treatment options, the overall prognosis of PCNSL remains poor. Among many unfavorable factors affecting efficacy, inadequate drug delivery into the CNS is still the thorniest challenge. Blood-brain barrier (BBB) constitutes a significant impediment, restricting entry of most therapeutics to the brain. Nanotechnology has offered great promise for brain diseases, as various nano-based drug delivery systems (NDDSs) have been developed for delivery of theranostic agents in to the CNS. These drug delivery systems possess significant advantages, including good feasibility, reliable safety profile, excellent BBB penetration and potent antitumor effects. As for treatment of PCNSL, numerous well-developed BBB-crossing nano-based strategies can be applied with proper modifications and improvements. Some exquisitely designed NDDSs specific for PCNSL have shown great potential. In this review, we provide a summary on current status of diagnosis and treatment of PCNSL, followed by an overview of BBB-crossing strategies applied in management of PCNSL, both novel and wellestablished. Finally, challenges and future perspectives in this field are also discussed.

Consequences of Extracellular Matrix Remodeling in Headway and Metastasis of Cancer along with Novel Immunotherapies: A Great Promise for Future Endeavor

Tissues are progressively molded by bidirectional correspondence between denizen cells and extracellular matrix (ECM) via cell-matrix connections along with ECM remodeling. The composition and association of ECM are spatiotemporally directed to control cell conduct and differentiation; however, dysregulation of ECM dynamics prompts the development of diseases, for example, cancer. Emerging information demonstrates that hypoxia may have decisive roles in metastasis. In addition, the sprawling nature of neoplastic cells and chaotic angiogenesis are increasingly influencing microcirculation as well as altering the concentration of oxygen. In various regions of the tumor microenvironment, hypoxia, an essential player in the multistep phase of cancer metastasis, is necessary. Hypoxia can be turned into an advantage for selective cancer therapy because it is much more severe in tumors than in normal tissues. Cellular matrix gives signaling cues that control cell behavior and organize cells' elements in tissue development and homeostasis. The interplay between intrinsic factors of cancer cells themselves, including their genotype and signaling networks, and extrinsic factors of tumor stroma, for example, ECM and ECM remodeling, together decide the destiny and behavior of tumor cells. Tumor matrix encourages the development, endurance, and invasion of neoplastic and immune cell activities to drive metastasis and debilitate treatment. Incipient evidence recommends essential parts of tumor ECM segments and their remodeling in controlling each progression of the cancer-immunity cycle. Scientists have discovered that tumor matrix dynamics as well as matrix remodeling in perspective to anti-tumor immune reactions are especially important for matrix-based biomarkers recognition and followed by immunotherapy and targeting specific drugs.

Role of Systemic Inflammatory Reaction in Female Genital Organ Malignancies - State of the Art

Systemic inflammatory reaction (SIR) is an unfavorable prognostic factor in many malignancies and has a role in all stages of the neoplastic process: initiation, promotion, and disease progression. Analysis of SIR can be performed by assessing indicators (eg, lymphocyte-to-neutrophil, platelet-to-lymphocyte, and monocyte-to-neutrophil ratios) and products of neutrophils and lymphocytes (ie, the systemic immune-inflammation index), or by examining the relationship between levels of C-reactive protein and albumin (based on the Glasgow Prognostic Score, modified Glasgow Prognostic Score, and C-reactive protein-to-albumin ratio). Risk stratification is essential in the clinical management of cancer; hence, the evaluation of these factors has potential applications in the clinical management of patients with cancer and in the development of new therapeutic targets. This review summarizes the current knowledge on SIR indicators and presents their clinical utility in malignancies of the female genital organs.

Tumor Necrosis with Adjunction of Preoperative Monocyte-to-Lymphocyte Ratio as a New Risk Stratification Marker Can Independently Predict Poor Outcomes in Upper Tract Urothelial Carcinoma

OBJECTIVES

This study aimed at investigating the prognostic impact of tumor necrosis and preoperative monocyte-to-lymphocyte ratio (MLR) in patients treated with radical nephroureterectomy (RNU) for upper tract urothelial carcinoma (UTUC).

METHODS

A total of 521 patients with UTUC treated with RNU from January 2008 to June 2019 at our institution were enrolled. Histological tumor necrosis was defined as the presence of microscopic coagulative necrosis. The optimal value of MLR was determined as 0.4 by receiver operating characteristic (ROC) analysis based on cancer-specific mortality. The Kaplan-Meier method with log-rank test and Cox proportional hazards regression models were performed to evaluate the impact of tumor necrosis and MLR on overall (OS), cancer-specific (CSS), and recurrence-free survival (RFS). Furthermore, ROC analysis was used to estimate the predictive ability of potential prognostic factors for oncological outcomes.

RESULTS

Tumor necrosis was present in 106 patients (20%), which was significantly associated with tumor location, high pathological tumor stage, lymph node metastasis, high tumor grade, lymphovascular invasion, tumor size, and increased monocyte counts. On multivariate analysis, the combination of tumor necrosis and preoperative MLR was an independent prognosticator of OS, CSS, and RFS (all p < 0.05). Moreover, ROC analyses revealed the predictive accuracy of a combination of tumor necrosis and preoperative MLR for OS, CSS, and RFS with the area under the ROC curve of 0.745, 0.810, and 0.782, respectively (all p < 0.001).

CONCLUSIONS

The combination of tumor necrosis and preoperative MLR can be used as an independent prognosticator in patients with UTUC after RNU. The identification of this combination could help physicians to recognize high-risk patients with unfavorable outcomes and devise more appropriate postoperative treatment plans.

Hypoxia induces inflammatory microenvironment by priming specific macrophage polarization and modifies LSC behaviour via VEGF-HIF1α signalling

BACKGROUND

Leukemia stem cells (LSCs) play pivotal roles in leukemogenesis, and are closely implicated in leukemia relapse and chemoresistance. LSCs are tightly modulated by hypoxic exposure and macrophage-conditioned microenvironment. Nevertheless, the impacts on the biology of LSCs imposed by the interaction of hypoxia and macrophage polarization remain elusive.

METHODS

In the study, LSCs characterized by CD34+CD38- immunophenotype sorted from KG1α and primary AML cells were employed as in vitro and ex vivo cell models. mRNA and protein expressions of cytokine/chemokine of cells under normoxic and hypoxic conditions were determined by RT-PCR and western blot. Macrophage polarization, cell cycle and apoptosis were determined by flowcytometry. Cell viability was assayed by CCK-8.

RESULTS

Macrophages preferentially presented with M2 polarization phenotype characterized by upregulated VEGF and CCL17 cytokine/chemokine profile, when stimulated by specific set of cytokines under hypoxic exposure, and induced an anti-inflammatory microenvironment. LSCs exhibited significantly increased cell viability, colony-forming capacity and chemoresistance when co-incubated in hypoxic conditioned medium (H-CM) primed by polarized M1 macrophages. VEGF expression was upregulated in LSCs which in turn activated survivin expression. VEGF-mediated upregulation of survivin could be abolished by inhibition of VEGF receptor, but not blocked by survivin-targeting siRNA. In addition, survivin upregulation exerted antiapoptotic effects and was associated with increased chemoresistance. Finally, VEGF mediated transcriptional induction of HIF-1α of LSCs coincubated in H-CM, and HIF-1α induction in turn enhanced chemoresistance and reduced cell apoptosis.

CONCLUSIONS

To our best knowledge, this is the first study that focus to explore molecule players and interacting signal pathways regulating LSC biology under hypoxic exposure. It reveals that hypoxia preferentially skew macrophage M2 polarization with specific cytokine profile and proinflammatory microenvironment, which impacts malignant behavior of LSCs. VEGF-HIF-1α interaction is closely implicated in sustaining LSCs survival under hypoxic exposure and might be of potential target of novel therapy.

Perspectives on Hypoxia Signaling in Tumor Stroma

Hypoxia is a well-known characteristic of solid tumors that contributes to tumor progression and metastasis. Oxygen deprivation due to high demand of proliferating cancer cells and standard of care therapies induce hypoxia. Hypoxia signaling, mainly mediated by the hypoxia-inducible transcription factor (HIF) family, results in tumor cell migration, proliferation, metabolic changes, and resistance to therapy. Additionally, the hypoxic tumor microenvironment impacts multiple cellular and non-cellular compartments in the tumor stroma, including disordered tumor vasculature, homeostasis of ECM. Hypoxia also has a multifaceted and often contradictory influence on immune cell function, which contributes to an immunosuppressive environment. Here, we review the important function of HIF in tumor stromal components and summarize current clinical trials targeting hypoxia. We provide an overview of hypoxia signaling in tumor stroma that might help address some of the challenges associated with hypoxia-targeted therapies.

Tumor-Associated Macrophages as Multifaceted Regulators of Breast Tumor Growth

Breast cancer is the most commonly occurring cancer in women of Western countries and is the leading cause of cancer-related mortality. The breast tumor microenvironment contains immune cells, fibroblasts, adipocytes, mesenchymal stem cells, and extracellular matrix. Among these cells, macrophages or tumor-associated macrophages (TAMs) are the major components of the breast cancer microenvironment. TAMs facilitate metastasis of the breast tumor and are responsible for poor clinical outcomes. High TAM density was also found liable for the poor prognosis of breast cancer. These observations make altering TAM function a potential therapeutic target to treat breast cancer. The present review summarizes the origin of TAMs, mechanisms of macrophage recruitment and polarization in the tumor, and the contributions of TAMs in tumor progression. We have also discussed our current knowledge about TAM-targeted therapies and the roles of miRNAs and exosomes in re-educating TAM function.

Correlation between the number of viable tumor cells and immune cells in the tumor microenvironment in non-small cell lung cancer after induction therapy

This study aims to determine the correlation between the percent viable tumor cells (%VTC) and the tumor microenvironment in resected non-small cell lung cancer after induction therapy. We enrolled 72 patients with non-small cell lung cancer (NSCLC) who received chemoradiotherapy (CRT) or chemotherapy (CT) prior to surgery. The ratio of the area of viable tumor cells to the total tumor area was calculated to obtain the %VTC. We also examined the number of CD4 (+), CD8 (+), CD20 (+) and FOXP3 (+) tumor-infiltrating lymphocytes (TILs), podoplanin (PDPN) (+) cancer-associated fibroblasts (CAFs), and CD204 (+) tumor-associated macrophages (TAMs) by immunohistochemistry (IHC). In the CRT group (n = 37), the tumors had significantly lower %VTC than the CT group (n = 35) (P < 0.001). In both of the CT group and CRT group, the %VTC showed a significant positive correlation with the number of CD204 (+)-TAMs (P = 0.014 and 0.005, respectively). Only in the CRT group, a higher number of CD204 (+) TAMs was associated with a shorter overall survival (OS) (P = 0.007) and recurrence-free survival (RFS) (P = 0.015). In the CRT group, the number of CD204 (+) TAMs is associated with %VTC and prognosis, suggesting that these cells may have tumor-promoting effects on the residual lung cancer in specific microenvironments after CRT.

Transcriptional and Microenvironmental Landscape of Macrophage Transition in Cancer: A Boolean Analysis

The balance between pro- and anti-inflammatory immune system responses is crucial to face and counteract complex diseases such as cancer. Macrophages are an essential population that contributes to this balance in collusion with the local tumor microenvironment. Cancer cells evade the attack of macrophages by liberating cytokines and enhancing the transition to the M2 phenotype with pro-tumoral functions. Despite this pernicious effect on immune systems, the M1 phenotype still exists in the environment and can eliminate tumor cells by liberating cytokines that recruit and activate the cytotoxic actions of TH1 effector cells. Here, we used a Boolean modeling approach to understand how the tumor microenvironment shapes macrophage behavior to enhance pro-tumoral functions. Our network reconstruction integrates experimental data and public information that let us study the polarization from monocytes to M1, M2a, M2b, M2c, and M2d subphenotypes. To analyze the dynamics of our model, we modeled macrophage polarization in different conditions and perturbations. Notably, our study identified new hybrid cell populations, undescribed before. Based on the in vivo macrophage behavior, we explained the hybrid macrophages’ role in the tumor microenvironment. The in silico model allowed us to postulate transcriptional factors that maintain the balance between macrophages with anti- and pro-tumoral functions. In our pursuit to maintain the balance of macrophage phenotypes to eliminate malignant tumor cells, we emulated a theoretical genetically modified macrophage by modifying the activation of NFκB and a loss of function in HIF1-α and discussed their phenotype implications. Overall, our theoretical approach is as a guide to design new experiments for unraveling the principles of the dual host-protective or -harmful antagonistic roles of transitional macrophages in tumor immunoediting and cancer cell fate decisions.