Tumor-conditioned macrophages secrete migration-stimulating factor: a new marker for M2-polarization, influencing tumor cell motility

Tumor microenvironment complexity and therapeutic implications at a glance

The dynamic interactions of cancer cells with their microenvironment consisting of stromal cells (cellular part) and extracellular matrix (ECM) components (non-cellular) is essential to stimulate the heterogeneity of cancer cell, clonal evolution and to increase the multidrug resistance ending in cancer cell progression and metastasis. The reciprocal cell-cell/ECM interaction and tumor cell hijacking of non-malignant cells force stromal cells to lose their function and acquire new phenotypes that promote development and invasion of tumor cells. Understanding the underlying cellular and molecular mechanisms governing these interactions can be used as a novel strategy to indirectly disrupt cancer cell interplay and contribute to the development of efficient and safe therapeutic strategies to fight cancer. Furthermore, the tumor-derived circulating materials can also be used as cancer diagnostic tools to precisely predict and monitor the outcome of therapy. This review evaluates such potentials in various advanced cancer models, with a focus on 3D systems as well as lab-on-chip devices. Video abstract.

Breast cancer models: Engineering the tumor microenvironment

The mechanisms behind cancer initiation and progression are not clear. Therefore, development of clinically relevant models to study cancer biology and drug response in tumors is essential. In vivo models are very valuable tools for studying cancer biology and for testing drugs; however, they often suffer from not accurately representing the clinical scenario because they lack either human cells or a functional immune system. On the other hand, two-dimensional (2D) in vitro models lack the three-dimensional (3D) network of cells and extracellular matrix (ECM) and thus do not represent the tumor microenvironment (TME). As an alternative approach, 3D models have started to gain more attention, as such models offer a platform with the ability to study cell-cell and cell-material interactions parametrically, and possibly include all the components present in the TME. Here, we first give an overview of the breast cancer TME, and then discuss the current state of the pre-clinical breast cancer models, with a focus on the engineered 3D tissue models. We also highlight two engineering approaches that we think are promising in constructing models representative of human tumors: 3D printing and microfluidics. In addition to giving basic information about the TME in the breast tissue, this review article presents the state-of-the-art tissue engineered breast cancer models. STATEMENT OF SIGNIFICANCE: Involvement of biomaterials and tissue engineering fields in cancer research enables realistic mimicry of the cell-cell and cell-extracellular matrix (ECM) interactions in the tumor microenvironment (TME), and thus creation of better models that reflect the tumor response against drugs. Engineering the 3D in vitro models also requires a good understanding of the TME. Here, an overview of the breast cancer TME is given, and the current state of the pre-clinical breast cancer models, with a focus on the engineered 3D tissue models is discussed. This review article is useful not only for biomaterials scientists aiming to engineer 3D in vitro TME models, but also for cancer researchers willing to use these models for studying cancer biology and drug testing.

RIPK3 Orchestrates Fatty Acid Metabolism in Tumor-Associated Macrophages and Hepatocarcinogenesis

Metabolic reprogramming is critical for the polarization and function of tumor-associated macrophages (TAM) and hepatocarcinogenesis, but how this reprogramming occurs is unknown. Here, we showed that receptor-interacting protein kinase 3 (RIPK3), a central factor in necroptosis, is downregulated in hepatocellular carcinoma (HCC)-associated macrophages, which correlated with tumorigenesis and enhanced the accumulation and polarization of M2 TAMs. Mechanistically, RIPK3 deficiency in TAMs reduced reactive oxygen species and significantly inhibited caspase1-mediated cleavage of PPAR. These effects enabled PPAR activation and facilitated fatty acid metabolism, including fatty acid oxidation (FAO), and induced M2 polarization in the tumor microenvironment. RIPK3 upregulation or FAO blockade reversed the immunosuppressive activity of TAMs and dampened HCC tumorigenesis. Our findings provide molecular basis for the regulation of RIPK3-mediated, lipid metabolic reprogramming of TAMs, thus highlighting a potential strategy for targeting the immunometabolism of HCC.

Standardized protocols for differentiation of THP-1 cells to macrophages with distinct M(IFNγ+LPS), M(IL-4) and M(IL-10) phenotypes

In vitro models of differing macrophage functions are useful since human monocyte-derived macrophages are short-lived, finite and vary from donor to donor. Published protocols using the promonocytic cell line THP-1 have tended to result in cells that closely resemble classically-activated macrophages, differentiated in IFNγ and LPS. However, no protocol, to date, has fully recapitulated polarization of THP-1 to the M(IL-4) or M(IL-10) macrophage phenotypes seen when human monocyte-derived macrophages are exposed to each cytokine. Here we present protocols that can be used to prepare M(IL-4) polarized THP-1 that transcribe CCL17, CCL26, CD200R and MRC1 and M(IL-10) cells which transcribe CD163, C1QA and SEPP1. We show that the inhibitory Fcγ Receptor IIb is preferentially expressed on the surface of M(IL-4) cells, altering the balance of activating to inhibitory Fcγ Receptors. Adoption of standardized experimental conditions for macrophage polarization will make it easier to compare downstream effector functions of different macrophage polarization states, where the impact of PMA exposure is minimized and rest periods and cytokine exposure have been optimized.

Oligo-Fucoidan Prevents M2 Macrophage Differentiation and HCT116 Tumor Progression

Reactive oxygen species (ROS) produced during intracellular metabolism or triggered by extrinsic factors can promote neoplastic transformation and malignant microenvironment that mediate tumor development. Oligo-Fucoidan is a sulfated polysaccharide isolated from the brown seaweed. Using human THP-1 monocytes and murine Raw264.7 macrophages as well as human HCT116 colorectal cancer cells, primary C6P2-L1 colorectal cancer cells and human MDA-MB231 breast cancer cells, we investigated the effect of Oligo-Fucoidan on inhibiting M2 macrophage differentiation and its therapeutic potential as a supplement in chemotherapy and tumor prevention. We now demonstrate that Oligo-Fucoidan is an antioxidant that suppresses intracellular ROS and mitochondrial superoxide levels in monocytes/macrophages and in aggressive cancer cells. Comparable to ROS inhibitors (DPI and NAC), Oligo-Fucoidan directly induced monocyte polarization toward M1-like macrophages and repolarized M2 macrophages into M1 phenotypes. DPI and Oligo-Fucoidan also cooperatively prevented M2 macrophage invasiveness. Indirectly, M1 polarity was advanced particularly when DPI suppressed ROS generation and supplemented with Oligo-Fucoidan in the cancer cells. Moreover, cisplatin chemoagent polarized monocytes and M0 macrophages toward M2-like phenotypes and Oligo-Fucoidan supplementation reduced these side effects. Furthermore, Oligo-Fucoidan promoted cytotoxicity of cisplatin and antagonized cisplatin effect on cancer cells to prevent M2 macrophage differentiation. More importantly, Oligo-Fucoidan inhibited tumor progression and M2 macrophage infiltration in tumor microenvironment, thus increasing of anti-tumor immunity.

Ferroptosis in Cancer Cell Biology

A major hallmark of cancer is successful evasion of regulated forms of cell death. Ferroptosis is a recently discovered type of regulated necrosis which, unlike apoptosis or necroptosis, is independent of caspase activity and receptor-interacting protein 1 (RIPK1) kinase activity. Instead, ferroptotic cells die following iron-dependent lipid peroxidation, a process which is antagonised by glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1). Importantly, tumour cells escaping other forms of cell death have been suggested to maintain or acquire sensitivity to ferroptosis. Therefore, therapeutic exploitation of ferroptosis in cancer has received increasing attention. Here, we systematically review current literature on ferroptosis signalling, cross-signalling to cellular metabolism in cancer and a potential role for ferroptosis in tumour suppression and tumour immunology. By summarising current findings on cell biology relevant to ferroptosis in cancer, we aim to point out new conceptual avenues for utilising ferroptosis in systemic treatment approaches for cancer.

Inflammatory response to magnesium-based biodegradable implant materials

Biodegradability and mechanical properties of magnesium alloys are attractive for orthopaedic and cardiovascular applications. In order to study their cytotoxicity usually bone cells are used. However, after implantation, diverse and versatile cells are recruited and interact. Among the first ones coming into play are cells of the immune system, which are responsible for the inflammatory reaction. Macrophages play a central role in the inflammatory process due to the production of cytokines involved in the tissue healing but also in the possible failure of the implants. In order to evaluate the in vitro influence of the degradation products of magnesium-based alloys on cytokine release, the extracts of pure magnesium and two magnesium alloys (with gadolinium and silver as alloying elements) were examined in an inflammatory in vitro model. Human promonocytic cells (U937 cells) were differentiated into macrophages and further cultured with magnesium-based extracts for 1 and 3 days (simulating early and late inflammatory reaction phases), either at 37 °C or at 39 °C (mimicking normal and inflammatory conditions, respectively). All extracts exhibit very good cytocompatibility on differentiated macrophages. Results suggest that M1 and even more M2 profiles of macrophage were stimulated by the extracts of Mg. Furthermore, Mg-10Gd and Mg-2Ag extracts introduced a nuancing effect by rather inhibiting macrophage M1 profile. Magnesium-based biomaterials could thus induce a faster inflammation resolution while improving tissue repair. STATEMENT OF SIGNIFICANCE: Macrophage are the key-cells during inflammation and can influence the fate of tissue healing and implant performance. Magnesium-based implants are biodegradable and bioactive. Here we selected an in vitro system to model early and late inflammation and effect of pyrexia (37 °C versus 39 °C). We showed the beneficial and nuancing effects of magnesium (Mg) and the selected alloying elements (silver (Ag) and gadolinium (Gd)) on the macrophage polarisation. Mg extracts exacerbated simultaneously the macrophage M1 and M2 profiles while Mg-2Ag and Mg-10Gd rather inhibited the M1 differentiation. Furthermore, 39 °C exhibited protective effect by either decreasing cytokine production or promoting anti-inflammatory ones, with or without extracts. Mg-based biomaterials could thus induce a faster inflammation resolution while improving tissue repair.

Fibronectin in Cancer: Friend or Foe

The role of fibronectin (FN) in tumorigenesis and malignant progression has been highly controversial. Cancerous FN plays a tumor-suppressive role, whereas it is pro-metastatic and associated with poor prognosis. Interestingly, FN matrix deposited in the tumor microenvironments (TMEs) promotes tumor progression but is paradoxically related to a better prognosis. Here, we justify how FN impacts tumor transformation and subsequently metastatic progression. Next, we try to reconcile and rationalize the seemingly conflicting roles of FN in cancer and TMEs. Finally, we propose future perspectives for potential FN-based therapeutic strategies.

Anti-Cancer Effects of Panax ginseng Berry Polysaccharides via Activation of Immune-Related Cells

Panax ginseng has long been used as natural medicine and health food all over the world. Cancer is a major cause of death worldwide and its prognosis likely depends on the immune system during tumor treatment. In this study, ginseng berry polysaccharides were evaluated for their immunostimulant and anti-cancer effects. Ginseng berry polysaccharide portion (GBPP) was used to investigate its effects on anti-complementary activity, peritoneal macrophage activation, and natural killer (NK) cell cytotoxicity. Moreover, both intravenous (i.v.) and oral administration of GBPP prior to B16-BL6 melanoma implantation in mice was evaluated. GBPP significantly increased the anti-complementary activity and cytokine production including interleukin (IL)-6, IL-12, and tumor necrosis factor (TNF)-α, dose-dependently. Splenocytes obtained after i.v. administration of GBPP showed cytolytic activity in Yac-1 cells in proportion to the E/T ratio. In addition, GBPP enhanced the production of interferon (IFN)-γ and granzyme B of NK cells. For the experimental lung cancer, compared with control mice, GBPP delivered by i.v. suppressed cancer by 48% at 100 μg/mouse, while a 37% reduction was achieved by oral administration. Deficient of NK cells in animal model demonstrated that the anti-cancer effect of GBPP was through NK cell activation. Results of this study suggest that ginseng berry polysaccharides, owing to their modulation of the immune response, can be a potential curative applicant for the prevention and treatment of tumors.

Methods for macrophage differentiation and in vitro generation of human tumor associated-like macrophages

Tumor-associated macrophages (TAMs) are becoming a promising target for cancer immunotherapy. Significant efforts have been made to study the detrimental role of TAMs both in vivo and in vitro. However, it remains challenging to isolate these macrophages to study their function in human cancers and there is the need to seek alternatives to address these limitations. In this review, we will focus on the three most relevant approaches to obtain in vitro fully differentiated macrophages i.e. peripheral blood, immortalized cell lines such as THP-1 or human induced pluripotent stem cells. We will also provide protocols for the polarization of human macrophages to a TAM-like cells in vitro.

Mechanical Property Changes in Breast Cancer Cells Induced by Stimulation with Macrophage Secretions in Vitro

The contribution of secretions from tumor-associated macrophage (TAM)-like cells to the stimulation of mechanical property changes in murine breast cancer cells was studied using an in vitro model system. A murine breast cancer cell line (FP10SC2) was stimulated by adding macrophage (J774.2) cultivation medium containing stimulation molecules secreted from the macrophages, and changes in mechanical properties were compared before and after stimulation. As a result, cell elasticity decreased, degradation ability of the extracellular matrix increased, and the expression of plakoglobin was upregulated. These results indicate that cancer cell malignancy is upregulated by this stimulation. Moreover, changes in intercellular adhesion strengths between pairs of cancer cells were measured before and after stimulation using atomic force microscopy (AFM). The maximum force required to separate cells was increased by stimulation with the secreted factors. These results indicate the possibility that TAMs cause changes in the mechanical properties of cancer cells in tumor microenvironments, and in vitro measurements of mechanical property changes in cancer cells will be useful to study interactions between cells in tumor microenvironments.

Direct and Indirect Roles of Macrophages in Hypertrophic Scar Formation

Hypertrophic scars are pathological scars that result from abnormal responses to trauma, and could cause serious functional and cosmetic disability. To date, no optimal treatment method has been established. A variety of cell types are involved in hypertrophic scar formation after wound healing, but the underlying molecular mechanisms and cellular origins of hypertrophic scars are not fully understood. Macrophages are major effector cells in the immune response after tissue injury that orchestrates the process of wound healing. Depending on the local microenvironment, macrophages undergo marked phenotypic and functional changes at different stages during scar pathogenesis. This review intends to summarize the direct and indirect roles of macrophages during hypertrophic scar formation. The in vivo depletion of macrophages or blocking their signaling reduces scar formation in experimental models, thereby establishing macrophages as positive regulatory cells in the skin scar formation. In the future, a significant amount of attention should be given to molecular and cellular mechanisms that cause the phenotypic switch of wound macrophages, which may provide novel therapeutic targets for hypertrophic scars.

Acquired resistance to cancer immunotherapy: Role of tumor-mediated immunosuppression

In the tumor microenvironment (TME), tumor cells are constantly evolving to reduce neoantigen generation and the mutational burden to escape the anti-tumor response. This will lower tumor reactivity to the adaptive immune response and give rise to tumor intrinsic factors, such as altered expression of immune regulatory molecules on tumor cells. Tumor-extrinsic factors, such as immunosuppressive cells, soluble suppressive molecules or inhibitory receptors expressed by immune cells will alter the composition and activity of tumor-infiltrating lymphocytes (TILs) (by increasing T regulatory cells:T effector cells ratio and inhibiting T effector cell function) and promote tumor growth and metastasis. Together, these factors limit the response rates and clinical outcomes to a particular cancer therapy. Within the TME, the cross-talks between immune and non-immune cells result in the generation of positive feedback loops, which augment immunosuppression and support tumor growth and survival (termed as tumor-mediated immunosuppression). Cancer immunotherapies, such as immune checkpoint inhibitors (ICIs) and adoptive cell transfer (ACT), have shown therapeutic efficacy in hematologic cancers and different types of solid tumors. However, achieving durable response rates in some cancer patients remains a challenge as a result of acquired resistance and tumor immune evasion. This could be driven by the cellular and molecular suppressive network within the TME or due to the loss of tumor antigens. In this review, we describe the contribution of the immunosuppressive cellular and molecular tumor network to the development of acquired resistance against cancer immunotherapies. We also discuss potential combined therapeutic strategies which could help to overcome such resistance against cancer immunotherapies, and to enhance anti-tumor immune responses and improve clinical outcomes in patients.

Distribution and prognostic impact of microglia/macrophage subpopulations in gliomas

While the central nervous system is considered an immunoprivileged site and brain tumors display immunosuppressive features, both innate and adaptive immune responses affect glioblastoma (GBM) growth and treatment resistance. However, the impact of the major immune cell population in gliomas, represented by glioma-associated microglia/macrophages (GAMs), on patients' clinical course is still unclear. Thus, we aimed at assessing the immunohistochemical expression of selected microglia and macrophage markers in 344 gliomas (including gliomas from WHO grade I-IV). Furthermore, we analyzed a cohort of 241 IDH1R132H-non-mutant GBM patients for association of GAM subtypes and patient overall survival. Phenotypical properties of GAMs, isolated from high-grade astrocytomas by CD11b-based magnetic cell sorting, were analyzed by immunocytochemistry, mRNA microarray, qRT-PCR and bioinformatic analyses. A higher amount of CD68-, CD163- and CD206-positive GAMs in the vital tumor core was associated with beneficial patient survival. The mRNA expression profile of GAMs displayed an upregulation of factors that are considered as pro-inflammatory M1 (eg, CCL2, CCL3L3, CCL4, PTGS2) and anti-inflammatory M2 polarization markers (eg, MRC1, LGMN, CD163, IL10, MSR1), the latter rather being associated with phagocytic functions in the GBM microenvironment. In summary, we present evidence that human GBMs contain mixed M1/M2-like polarized GAMs and that the levels of different GAM subpopulations in the tumor core are positively associated with overall survival of patients with IDH1R132H-non-mutant GBMs.

Attenuated inflammatory response of monocyte-derived macrophage from patients with BD: a preliminary report

BACKGROUND

Innate immune system dysfunction has been recognized as an important element in the pathophysiology of bipolar disorder (BD). We aimed to investigate whether there are differences in the response of macrophages derived from patients in the early stages and late stages of BD and healthy subjects.

METHODS

Human monocytes purified from peripheral blood mononuclear cells (PBMCs) of patients with BD type I (n = 18)-further classified into early- and late stage BD patients according to their functioning- and from healthy individuals (n = 10) were differentiated into macrophages in vitro. Monocyte-derived macrophages (M) were exposed to IFNγ plus LPS-M(IFNγ + LPS)- or IL-4-M(IL-4)-to induce their polarization into the classical (also called M1) or alternative (also called M2) activation phenotypes, respectively; or either Mψ were not exposed to any stimuli characterizing the resting state (denominated M0). In vitro secretion of cytokines, such as IL-1β, IL-6, IL-10, and TNF-α, was used as an index of macrophage activity.

RESULTS

M(IFNγ + LPS) from late-stage BD patients produced less amount of IL-1β, IL-6, and IL-10 when compared to early-stage BD patients and healthy controls. Following alternative activation, M(IL-4) derived from late-stage patients secreted less IL-6 compared to the other groups. TNFα was less secreted by all macrophage phenotypes derived from late-stage patients when compared to healthy controls only (p < 0.005). Mψ from late-stage patients exhibited lower production of IL-1β and IL-10 compared to macrophages from healthy subjects and early-stage patients respectively. Interestingly, cytokines secretion from M(IFNγ + LPS), M(IL-4) and Mψ were similar between early-stage patients and healthy controls.

CONCLUSION

Our results suggest a progressive dysfunction in the response of peripheral innate immune cells of BD patients in the late stages of the illness. This failure in the regulation of the immune system function may be implicated in the multisystemic progression of BD.

Osteopontin as a multifaceted driver of bone metastasis and drug resistance

Metastasis to bone frequently occurs in majority of patients with advanced breast cancer and prostate cancer, leading to devastating skeletal-related events and substantially reducing the survival of patients. Currently, the crosstalk between tumor cells and the bone stromal compartment was widely investigated for bone metastasis and the resistance to many conventional therapeutic methods. Osteopontin (OPN), also known as SPP1 (secreted phosphoprotein 1), a secreted and chemokine-like glyco-phosphoprotein is involved in tumor progression such as cell proliferation, angiogenesis, and metastasis. The expression of OPN in tumor tissue and plasma has been clinically proved to be correlated to poor prognosis and shortened survival in patients with breast cancer and prostate cancer. This review summarizes the multifaceted roles that OPN plays in bone microenvironment and drug resistance, with emphasis on breast and prostate cancers, via binding to αvβ3 integrin and CD44 receptor and inducing signaling cascades. We further discuss the promising therapeutic strategy for OPN targeting, mainly inhibiting OPN at transcriptional or protein level or blocking it binding to receptor or its downstream signaling pathways. The comprehending of the function of OPN in bone microenvironment is crucial for the development of novel biomarker and potential therapeutic target for the diagnosis and treatment of bone metastasis and against the emergence of drug resistance in advanced cancers.

MCT-1/miR-34a/IL-6/IL-6R signaling axis promotes EMT progression, cancer stemness and M2 macrophage polarization in triple-negative breast cancer

Background

Triple-negative breast cancer (TNBC) is a poor prognostic breast cancer with the highest mutations and limited therapeutic choices. Cytokine networking between cancer cells and the tumor microenvironment (TME) maintains the self-renewing subpopulation of breast cancer stem cells (BCSCs) that mediate tumor heterogeneity, resistance and recurrence. Immunotherapy of those factors combined with targeted therapy or chemoagents may advantage TNBC treatment.

Results

We found that the oncogene Multiple Copies in T-cell Malignancy 1 (MCT-1/MCTS1) expression is a new poor-prognosis marker in patients with aggressive breast cancers. Overexpressing MCT-1 perturbed the oncogenic breast epithelial acini morphogenesis and stimulated epithelial-mesenchymal transition and matrix metalloproteinase activation in invasive TNBC cells, which were repressed after MCT-1 gene silencing. As mammary tumor progression was promoted by oncogenic MCT-1 activation, tumor-promoting M2 macrophages were enriched in TME, whereas M2 macrophages were decreased and tumor-suppressive M1 macrophages were increased as the tumor was repressed via MCT-1 knockdown. MCT-1 stimulated interleukin-6 (IL-6) secretion that promoted monocytic THP-1 polarization into M2-like macrophages to increase TNBC cell invasiveness. In addition, MCT-1 elevated the soluble IL-6 receptor levels, and thus, IL-6R antibodies antagonized the effect of MCT-1 on promoting M2-like polarization and cancer cell invasion. Notably, MCT-1 increased the features of BCSCs, which were further advanced by IL-6 but prevented by tocilizumab, a humanized IL-6R antibody, thus MCT-1 knockdown and tocilizumab synergistically inhibited TNBC stemness. Tumor suppressor miR-34a was induced upon MCT-1 knockdown that inhibited IL-6R expression and activated M1 polarization.

Conclusions

The MCT-1 pathway is a novel and promising therapeutic target for TNBC.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-0988-0) contains supplementary material, which is available to authorized users.

Programming of macrophages by UV-irradiated apoptotic cancer cells inhibits cancer progression and lung metastasis

Apoptotic cell clearance by phagocytes is essential in tissue homeostasis. We demonstrated that conditioned medium (CM) from macrophages exposed to apoptotic cancer cells inhibits the TGFβ1-induced epithelial–mesenchymal transition (EMT), migration, and invasion of cancer cells. Apoptotic 344SQ (ApoSQ) cell-induced PPARγ activity in macrophages increased the levels of PTEN, which was secreted in exosomes. Exosomal PTEN was taken up by recipient lung cancer cells. ApoSQ-exposed CM from PTEN knockdown cells failed to enhance PTEN in 344SQ cells, restore cellular polarity, or exert anti-EMT and anti-invasive effects. The CM that was deficient in PPARγ ligands, including 15-HETE, lipoxin A4, and 15d-PGJ₂, could not reverse the suppression of PPARγ activity or the PTEN increase in 344SQ cells and consequently failed to prevent the EMT process. Moreover, a single injection of ApoSQ cells inhibited lung metastasis in syngeneic immunocompetent mice with enhanced PPARγ/PTEN signaling both in tumor-associated macrophages and in tumor cells. PPARγ antagonist GW9662 reversed the signaling by PPARγ/PTEN; the reduction in EMT-activating transcription factors, such as Snai1 and Zeb1; and the antimetastatic effect of the ApoSQ injection. Thus, the injection of apoptotic lung cancer cells may offer a new strategy for the prevention of lung metastasis.

Poly(I:C) stimulation is superior than Imiquimod to induce the antitumoral functional profile of tumor-conditioned macrophages

Macrophage plasticity is the ability of mononuclear phagocytes to change phenotype, function, and genetic reprogramming upon encounter of specific local stimuli. In the tumor microenvironment, Tumor-Associated Macrophages (TAMs) acquire an immune-suppressive and tumor-promoting phenotype. With the aim to re-educate TAMs to antitumor effectors, in this study, we used two immunestimulatory compounds: the TLR7 agonist Imiquimod (IMQ) and the TLR3 agonist Poly(I:C). To better mimic in vitro the response of TAMs, we used Tumor-Conditioned Macrophages (TC-Mϕ) differentiated in the presence of tumor cell supernatants. Our results show that TC-Mϕ respond differently from conventional M2-polarized macrophages. Upon stimulation with IMQ, TC-Mϕ did not upregulate major histocompatibility complex (MHC II) molecules and unexpectedly expressed increased CD206. With both compounds, TC-Mϕ produced higher levels of inflammatory cytokines than M2 macrophages. IMQ and Poly(I:C) differed in the types of regulated genes and secreted mediators. Reflecting their signaling pathways, only IMQ significantly induced IL-1β and IL-6, while only Poly(I:C) stimulated CXCL10, and both upregulated CCL5. Of note, using a novel cytotoxicity assay, Poly(I:C), but not IMQ, was effective in triggering the cytotoxic activity of TC-Mϕ against cancer cells. Overall, the results demonstrate that Poly(I:C) stimulation of TC-Mϕ is superior than IMQ in terms of macrophage re-education toward antitumor effectors.

Current progress in the inflammatory background of angiogenesis in gynecological cancers

A tumor growth depends on the potency of the tumor to support itself with nutrients and oxygen. The development of a vascular network within the tumor is key to its survival. The permanent contest between the tumor and its host involves tumor cells on one side and an immunological system and tissue stroma on the other. The angiogenesis is not only a specialty of the tumor, but it also depends on this complex multidirectional interaction. The most common gynecological cancers, cervical, endometrial and ovarian carcinoma are good examples for studying this problem. In this review, we aim to show that an inflammatory response against a tumor can be reverted into an undesirable process leading to the development of a vascular network within the tumor and, subsequently, further growth of the tumor and progression of a disease. Therefore, a key for tumor management should be searched within the immunological system, rather than focused on cell cycle and anti-angiogenic treatment only.

Exosomes Released from Tumor-Associated Macrophages Transfer miRNAs That Induce a Treg/Th17 Cell Imbalance in Epithelial Ovarian Cancer

The immune microenvironment is crucial for epithelial ovarian cancer (EOC) progression and consists of tumor-associated macrophages (TAM) and T lymphocytes, such as regulatory T cells (Treg) and T helper 17 (Th17) cells. In this study, the Treg/Th17 ratio was significantly higher in EOC in situ and in metastatic peritoneal tissues than in benign ovarian tumors and benign peritoneum. The Treg/Th17 ratio was associated with histologic grade and was an independent prognostic factor for overall survival of EOC patients. On the basis of microarray analysis of exosomes derived from TAMs, we identified miRNAs enriched in the exosomes, including miR-29a-3p and miR-21-5p. When the two miRNA mimics were transfected into CD4⁺ T cells, they directly suppressed STAT3 and regulated Treg/Th17 cells, inducing an imbalance, and they had a synergistic effect on STAT3 inhibition. Taken together, these results indicate that exosomes mediate the interaction between TAMs and T cells, generating an immune-suppressive microenvironment that facilitates EOC progression and metastasis. These findings suggest that targeting these exosomes or their associated miRNAs might pave the way for the development of novel treatments for EOC.

Tumor-driven like macrophages induced by conditioned media from pancreatic ductal adenocarcinoma promote tumor metastasis via secreting IL-8

Tumor-associated macrophages (TAMs) are abundant population of inflammatory cells which play an essential role in remodeling tumor microenvironment and tumor progression. Previously, we found the high density of TAMs was correlated with lymph node metastasis and poor prognosis in pancreatic ductal adenocarcinoma (PDAC). Therefore, this study was designed to investigate the mechanisms of interaction between TAMs and PDAC. THP-1 monocytes were the exposure to conditioned media (CM) produced by PDAC cells; then, monocyte recruitment and macrophage differentiation were assessed. CM from PDAC attracted and polarized THP-1 monocytes to tumor-driven like macrophages. mRNA expression cytokine profiling and ELISA identified the IL-8 secretion was increasing in tumor-driven like macrophages, and STAT3 pathway was involved. Addition of exogenous recombinant human IL-8 promoted PDAC cells motility in vitro and metastasis in vivo via upregulating Twist expression, which mediated epithelial-mesenchymal transition in cancer cells. What is more, IL-8 expression level in tumor stroma by immunohistochemical analysis was related to lymph node metastasis, the number of tumor CD68 but not CD163 positive macrophages and patient outcome. Taken together, these findings shed light on the important interplay between cancer cells and TAMs in tumor microenvironment and suggested that IL-8 signaling might be a potential therapeutic target for PDAC.

Roles for selenium and selenoprotein P in the development, progression, and prevention of intestinal disease

Selenium (Se) is a micronutrient essential to human health, the function of which is mediated in part by incorporation into a class of proteins known as selenoproteins (SePs). As many SePs serve antioxidant functions, Se has long been postulated to protect against inflammation and cancer development in the gut by attenuating oxidative stress. Indeed, numerous studies over the years have correlated Se levels with incidence and severity of intestinal diseases such as inflammatory bowel disease (IBD) and colorectal cancer (CRC). Similar results have been obtained with the Se transport protein, selenoprotein P (SELENOP), which is decreased in the plasma of both IBD and CRC patients. While animal models further suggest that decreases in Se or SELENOP augment colitis and intestinal tumorigenesis, large-scale clinical trials have yet to show a protective effect in patient populations. In this review, we discuss the function of Se and SELENOP in intestinal diseases and how research into these mechanisms may impact patient treatment.

TGF-β1 secreted by M2 phenotype macrophages enhances the stemness and migration of glioma cells via the SMAD2/3 signalling pathway

The positive correlation between the number of M2 phenotype TAMs (M2-TAMs) and tumour development suggests a supportive role of M2-TAMs in glioma progression. In the present study, the molecular link between glioma cells and M2-TAMs was investigated and it was demonstrated that transforming growth factor-β1 (TGF-β1) secreted by M2-TAMs is key in facilitating the stemness and migration of glioma cells. Cluster of differentiation (CD)133 and CD44, markers for the M2 phenotype, were assessed by western blotting. A sphere formation assay and trans-well assay were applied to test the stemness and migration abilities of glioma cells following co-cultured with M2-TAMs. Stemness markers CD133 and CD44, epithelial-mesenchymal transition-associated markers and mothers against decapentaplegic homolog (SMAD)2/3 and sex determining region Y-box 4/2 (SOX4/2) levels were also evaluated by western blotting. A xenograft tumor mouse model was used to demonstrate the tumor forming ability of glioma cells. The results showed that the U251 glioma cells co-cultured with M2-TAMs exhibited high level of sphere formation, stemness and migration ability. Recombinant TGF-β1 protein treatment was able to achieve the same effects on U251 cells, whereas a TGF-β pathway inhibitor reversed the stemness and migration abilities of the glioma cells induced by M2-TAMs. It was also demonstrated that TGF-β1 secreted by M2-TAMs upregulated the phosphorylation of SMAD2/3 and the expression of SOX4/2 in glioma cells. In a mouse xenograft model, solid tumours formed by U251 cells co-cultured with M2-TAMs or pre-treated with TGF-β1 were larger in size and had a higher growth rate. Taken together, results of the present study demonstrated that M2-TAMs promoted the stemness and migration abilities of glioma cells by secreting TGF-β1, which activated the SMAD2/3 pathway and induced the expression of SOX4 and SOX2. These results highlight the mechanism by which M2-TAMs and glioma interact and demonstrate potential therapeutic strategies for glioma treatment.

Influence of transcriptional variants on metastasis

Cancer metastasis is defined as the dissemination of malignant cells from the primary tumor site, leading to colonization of distant organs and the establishment of a secondary tumor. Metastasis is frequently associated with chemoresistance and is the major cause of cancer-related mortality. Metastatic cells need to acquire the ability to resist to stresses provided by different environments, such as reactive oxygen species, shear stress, hemodynamic forces, stromal composition, and immune responses, to colonize other tissues. Hence, only a small population of cells has a metastasis-initiating potential. Several studies have revealed the misregulation of transcriptional variants during cancer progression, and many splice events can be used to distinguish between normal and tumoral tissue. These variants, which are abnormally expressed in malignant cells, contribute to an adaptive response of tumor cells and the success of the metastatic cascade, promoting an anomalous cell cycle, cellular adhesion, resistance to death, cell survival, migration and invasion. Understanding the different aspects of splicing regulation and the influence of transcriptional variants that control metastatic cells is critical for the development of therapeutic strategies. In this review, we describe how transcriptional variants contribute to metastatic competence and discuss how targeting specific isoforms may be a promising therapeutic strategy.

Manipulating the tumor microenvironment by adoptive cell transfer of CAR T-cells

T-cells expressing synthetic chimeric antigen receptors (CARs) have revolutionized immuno-oncology and highlighted the use of adoptive cell transfer, for the treatment of cancer. The phenomenal clinical success obtained in the treatment of hematological malignancies with CAR T-cells has not been reproduced in the treatment of solid tumors, mainly due to the suppressive and hostile tumor microenvironment (TME). This review will address the immunosuppressive features of the TME, which include the stroma, cytokine and chemokine milieu, suppressive regulatory cells and hypoxic conditions, which can all pose formidable barriers for the effective anti-tumor function of CAR T-cells. Some of the novel next generation CARs that have been developed and tested against the TME, will be discussed, to highlight the status of current research in CAR T-cell therapy for solid tumors.

The biology and mathematical modelling of glioma invasion: a review

Adult gliomas are aggressive brain tumours associated with low patient survival rates and limited life expectancy. The most important hallmark of this type of tumour is its invasive behaviour, characterized by a markedly phenotypic plasticity, infiltrative tumour morphologies and the ability of malignant progression from low- to high-grade tumour types. Indeed, the widespread infiltration of healthy brain tissue by glioma cells is largely responsible for poor prognosis and the difficulty of finding curative therapies. Meanwhile, mathematical models have been established to analyse potential mechanisms of glioma invasion. In this review, we start with a brief introduction to current biological knowledge about glioma invasion, and then critically review and highlight future challenges for mathematical models of glioma invasion.

M1-like tumor-associated macrophages activated by exosome-transferred THBS1 promote malignant migration in oral squamous cell carcinoma

BACKGROUND

Treatment strategies targeting tumor-associated macrophages (TAMs) have been proposed in cancer areas. The functional alterations of macrophages in the microenvironment during the tumorigenesis of human epithelial cancer remain poorly understood. Here, we explored phenotypic alteration of macrophages during the development of oral squamous cell carcinoma (OSCC).

METHODS

Conditioned media (CM) and exosome supernatants were harvested from normal oral epithelium, oral leukoplakia cells and OSCC cells. We measured phenotypic alteration of macrophages using flow cytometry, luminex assays, and quantitative real-time PCR assay. Intracellular signaling pathway analysis, mass spectrometry proteomics, western blotting, enzyme-linked immunosorbent assay, immunohistochemical staining, and bioinformatics analysis were performed to uncover the underlying mechanisms.

RESULTS

THP-1-derived and PBMCs derived macrophages exhibited an M1-like phenotype but not M2-like phenotype, when treated with CM from OSCC cells but not with the CM from normal epithelium or leukoplakia cells. Further investigations revealed that macrophages were activated by taking up exosomes released from OSCC cells through p38, Akt, and SAPK/JNK signaling at the early phase. We further provided evidences that THBS1 derived from OSCC exosomes participated in the polarization of macrophages to an M1-like phenotype. Reciprocally, CM from exosomes induced M1-like TAMs and significantly promoted migration of OSCC cells.

CONCLUSIONS

We proposed a novel paracrine loop between cancer cells and macrophages based on exosomes from OSCC. Therefore, target management of M1-like TAMs polarized by exosomes shows great potential as a therapeutic target for the control of cancerous migration in OSCC.

MiR-98 modulates macrophage polarization and suppresses the effects of tumor-associated macrophages on promoting invasion and epithelial-mesenchymal transition of hepatocellular carcinoma

BACKGROUND

Tumor-associated macrophages (TAMs) are generally recognized as a promoter of tumor progression. miR-98 has been shown to suppress the proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) of hepatocellular carcinoma (HCC) cells. Here, we aim to investigate the role of miR-98-mediated macrophage polarization in HCC progression.

METHODS

Human blood monocytes were isolated from healthy male donors and incubated with culture medium collected from HepG2 cells for 7 days. The phenotype of the macrophages was detected. The protein expression was detected by Western blot. Levels of cytokines secreted in culture medium were measured using the specific enzyme-linked immunosorbent assay kits. To explore the role of miR-98 in HCC-conditioned TAMs, HCC cells HepG2 and SMMC7721 were cultured with conditioned medium from HCC-conditioned TAMs that had been transfected with miR-98 mimic/inhibitor. Cell proliferation, migration and invasion assays were performed.

RESULTS

HCC-conditioned TAMs possessed M2-like phenotype, including increased protein expression of CD163 and TNF-αlow, IL-1βlow, TGF-βhigh and IL-10high phenotype. HCC-conditioned TAMs also promoted proliferation, migration, invasion and EMT of HepG2 and SMMC7721 cells. Furthermore, miR-98 modulated macrophage polarization from M2 to M1 in HCC-conditioned TAMs, as evidenced by the alteration of M1- or M2-related cytokines. Moreover, miR-98 mimic significantly suppressed the HCC-conditioned TAMs-mediated promotion of cell migration, invasion and EMT in HepG2 and SMMC7721 cells compared with negative control, whereas miR-98 inhibitor exerted reversed effects.

CONCLUSIONS

miR-98 may play a vital role in regulating macrophage polarization, thereby suppressing the TAMs-mediated promotion of invasion and EMT in HCC.

IL-1β from M2 macrophages promotes migration and invasion of ESCC cells enhancing epithelial-mesenchymal transition and activating NF-κB signaling pathway

Despite the phenotype has been established that M2 macrophages promotes the metastasis of ESCC, question still remains as to how the M2 macrophages facilitated metastasis of ESCC cells. To begin with, immunohistochemistry was performed to detect the expression of CD163, one typical surface marker of M2 macrophages in 90 paired ESCC and its normal controls after meta-analyzing the relevant studies regarding M2 macrophages in ESCC, confirming that infiltration of M2 macrophages was significantly linked with lymph node metastasis, T classification, and inferior overall survival of ESCC. To explore the mechanism behind, protein factors secreted by M2 macrophages were identified using antibody microarray. Six different significantly differential protein factors were screened out, including IL-1β, TIMP1, IL-1α, MDC, TGF-β1, and TGF-β2. Among which, IL-1β was picked up as cytokine as interest based on previous reports and its absolute fold. Functional analysis of IL-1β showed that IL-1β was able to promote migration and invasion of ESCC cells, enhancing epithelial-mesenchymal transition, and activating NF-κB pathway. Our study supports the promoting role of M2 macrophages in metastasis of ESCC cells, enriching the profile of protein factors released from M2 macrophages.

Macrophages induce "budding" in aggressive human colon cancer subtypes by protease-mediated disruption of tight junctions

Primary human colorectal tumors with a high stromal content have an increased capacity to metastasize. Cancer-associated fibroblasts (CAFs) promote metastasis, but the contribution of other stromal cell types is unclear. Here we searched for additional stromal cell types that contribute to aggressive tumor cell behavior. By making use of the ‘immunome compendium’—a collection of gene signatures reflecting the presence of specific immune cell-types—we show that macrophage signatures are most strongly associated with a high CAF content and with poor prognosis in multiple large cohorts of primary tumors and liver metastases. Co-culturing macrophages with patient-derived colonospheres promoted ‘budding’ of small clusters of tumor cells from the bulk. Immunohistochemistry showed that budding tumor clusters in stroma-rich areas of T1 colorectal carcinomas were surrounded by macrophages. In vitro budding was accompanied by reduced levels of the tight junction protein occludin, but OCLN mRNA levels did not change, nor did markers of epithelial mesenchymal transition. Budding was accompanied by nuclear accumulation of β-catenin, which was also observed in budding tumor cell clusters in situ. The NFκB inhibitor Sanguinarine resulted in a decrease in MMP7 protein expression and both NFκB inhibitor Sanguinarine and MMP inhibitor Batimastat prevented occludin degradation and budding.

We conclude that macrophages contribute to the aggressive nature of stroma-rich colon tumors by promoting an MMP-dependent pathway that operates in parallel to classical EMT and leads to tight junction disruption.

Matrix stiffness and tumor-associated macrophages modulate epithelial to mesenchymal transition of human adenocarcinoma cells

The tumor microenvironment (TME) is gaining increasing attention in oncology, as it is recognized to be functionally important during tumor development and progression. Tumors are heterogeneous tissues that, in addition to tumor cells, contain tumor-associated cell types such as immune cells, fibroblasts, and endothelial cells. These other cells, together with the specific extracellular matrix (ECM), create a permissive environment for tumor growth. While the influence of tumor-infiltrating cells and mechanical properties of the ECM in tumor invasion and progression have been studied separately, their interaction within the complex TME and the epithelial -to-mesenchymal transition (EMT) is still unclear. In this work, we develop a 3D co-culture model of lung adenocarcinoma cells and macrophages in an interpenetrating network hydrogel, to investigate the influence of the macrophage phenotype and ECM stiffness in the induction of EMT. Rising ECM stiffness increases both tumor cell proliferation and invasiveness. The presence of tumor-associated macrophages and the ECM stiffness jointly contribute to an invasive phenotype, and modulate the expression of key EMT-related markers. Overall, these findings support the utility of in vitro 3D cancer models that allow one to study interactions among key components of the TME.

Tumor suppressor ARF regulates tissue microenvironment and tumor growth through modulation of macrophage polarization

Tumor microenvironment has been described to play a key role in tumor growth, progression, and metastasis. Macrophages are a major cellular constituent of the tumor stroma, and particularly tumor associated macrophages (TAMs or M2-like macrophages) exert important immunosuppressive activity and a pro-tumoral role within the tumor microenvironment. Alternative-reading frame (ARF) gene is widely inactivated in human cancer. We have previously demonstrated that ARF deficiency severely impairs inflammatory response establishing a new role for ARF in the regulation of innate immunity. On the basis of these observations, we hypothesized that ARF may also regulates tumor growth through recruitment and modulation of the macrophage phenotype in the tumor microenvironment. Xenograft assays of B16F10 melanoma cells into ARF-deficient mice resulted in increased tumor growth compared to those implanted in WT control mice. Tumors from ARF-deficient mice exhibited significantly increased number of TAMs as well as microvascular density. Transwell assays showed crosstalk between tumor cells and macrophages. On the one hand, ARF-deficient macrophages modulate migratory ability of the tumor cells. And on the other, tumor cells promote the skewing of ARF-/- macrophages toward a M2-type polarization. In conclusion, these results demonstrate that ARF deficiency facilitates the infiltration of macrophages into the tumor mass and favors their polarization towards a M2 phenotype, thus promoting tumor angiogenesis and tumor growth. This work provides novel information about the critical role of ARF in the modulation of tumor microenvironment.

Influence of Tumor Cell Culture Supernatants on Macrophage Functional Polarization: In Vitro Models of Macrophage-tumor Environment Interaction

Aims and background

Macrophages are heterogeneous cells with extensive functional plasticity; they can change their functional profiles repeatedly in response to environmental changes anywhere between their extreme phenotypical programs (labeled as M1 and M2 polarization, respectively). In terms of antitumoral immune response, M1 macrophages are considered to be beneficial, while M2 macrophages supposedly promote tumor progression. Tumor-associated macrophages (TAMs) represent a major leukocyte population present in many tumors. Although many studies indicate that TAMs elicit several M2-associated protumoral functions, including promotion of angiogenesis, matrix remodeling and suppression of adaptive immunity, their role regarding tumor progression is still controversial. The aim of the present study was to develop an appropriate in vitro model to study the effect of tumor-secreted soluble factors on the functional phenotype of macrophages.

Methods and study design

THP-1 human monocytic line cells and peripheral blood mononuclear cells from healthy volunteers were used for macrophage differentiation; primary tumor cell culture supernatants or tumor cell line supernatants were employed along with various cytokines, growth factors and other stimuli to design different model variants and to better mimic the in vivo tumor microenvironment.

Results

The cytokine secretion patterns of these macrophages suggest that primary tumor cell culture supernatants are able to switch the macrophage phenotype or to induce functional polarization of macrophages toward a mixed M1/M2 phenotype.

Conclusions

These data support the hypothesis that TAM behavior is modulated by the tumor microenvironment itself.

Deoxyschizandrin, Isolated from Schisandra Berries, Induces Cell Cycle Arrest in Ovarian Cancer Cells and Inhibits the Protumoural Activation of Tumour-Associated Macrophages

Deoxyschizandrin, a major lignan of Schisandra berries, has been demonstrated to have various biological activities such as antioxidant, hepatoprotective, and antidiabetic effects. However, the anti-cancer effects of deoxyschizandrin are poorly characterized. In the present study, we investigated the anti-cancer effect of deoxyschizandrin on human ovarian cancer cell lines and tumour-associated macrophages (TAMs). Deoxyschizandrin induced G₀/G₁ phase cell cycle arrest and inhibited cyclin E expression in human ovarian cancer cells. Overexpression of cyclin E significantly reversed the deoxyschizandrin-induced cell growth inhibition. Interestingly, increased production of reactive oxygen species and decreased activation of Akt were observed in A2780 cells treated with deoxyschizandrin, and the antioxidant compromised the deoxyschizandrin-induced cell growth inhibition and Akt inactivation. Moreover, deoxyschizandrin-induced cell growth inhibition was markedly suppressed by Akt overexpression. In addition, deoxyschizandrin was found to inhibit the expression of the M2 phenotype markers CD163 and CD209 in TAMs, macrophages stimulated by the ovarian cancer cells. Moreover, expression and production of the tumour-promoting factors MMP-9, RANTES, and VEGF, which are highly enhanced in TAMs, was significantly suppressed by deoxyschizandrin treatment. Taken together, these data suggest that deoxyschizandrin exerts anti-cancer effects by inducing G₀/G₁ cell cycle arrest in ovarian cancer cells and reducing the protumoural phenotype of TAMs.

Prospects for chimeric antigen receptor-modified T cell therapy for solid tumors

The potential for adoptive cell immunotherapy as a treatment against cancers has been demonstrated by the remarkable response in some patients with hematological malignancies using autologous T cells endowed with chimeric antigen receptors (CARs) specific for CD19. Clinical efficacy of CAR-T cell therapy for the treatment of solid tumors, however, is rare due to physical and biochemical factors. This review focuses on different aspects of multiple mechanisms of immunosuppression in solid tumors. We characterize the current state of CAR-modified T cell therapy and summarize the various strategies to combat the immunosuppressive microenvironment of solid tumors, with the aim of promoting T cell cytotoxicity and enhancing tumor cell eradication.

Evolving notions on immune response in colorectal cancer and their implications for biomarker development

INTRODUCTION

Colorectal cancer (CRC) still represents the third most commonly diagnosed type of cancer in men and women worldwide. CRC is acknowledged as a heterogeneous disease that develops through a multi-step sequence of events driven by clonal selections; this observation is sustained by the fact that histologically similar tumors may have completely different outcomes, including a varied response to therapy.

METHODS

In "early" and "intermediate" stage of CRC (stages II and III, respectively) there is a compelling need for new biomarkers fit to assess the metastatic potential of their disease, selecting patients with aggressive disease that might benefit from adjuvant and targeted therapies. Therefore, we review the actual notions on immune response in colorectal cancer and their implications for biomarker development.

RESULTS

The recognition of the key role of immune cells in human cancer progression has recently drawn attention on the tumor immune microenvironment, as a source of new indicators of tumor outcome and response to therapy. Thus, beside consolidated histopathological biomarkers, immune endpoints are now emerging as potential biomarkers.

CONCLUSIONS

The introduction of immune signatures and cellular and molecular components of the immune system as biomarkers is particularly important considering the increasing use of immune-based cancer therapies as therapeutic strategies for cancer patients.

Exosomal microRNA: a novel biomarker for breast cancer

Breast cancer is the most common invasive malignancy among females worldwide. microRNAs (miRNAs) are small noncoding RNAs that regulate post-transcriptional gene expression by binding to the 3'-untranslated regions of targeted mRNAs. Recently, exosomes have been recognized to play critical roles in breast cancer. miRNAs, as the most important inclusions in exosomes, are stable in the blood and other body fluids, making them ideal candidate biomarkers. In this review, we provide a complex overview of exosomal miRNAs in breast cancer. Particularly, we summarized their critical roles in tumorigenesis and tumor progression, expecting to lay the foundation for future studies using these potential biomarkers.