Tumour-associated macrophages in gastric cancer: From function and mechanism to application

BACKGROUND

Gastric cancer (GC) is a malignant tumour, with high morbidity and mortality rates worldwide. The occurrence and development of GC is a complex process involving genetic changes in tumour cells and the influence of the surrounding tumour microenvironment (TME). Accumulative evidence shows that tumour-associated macrophages (TAMs) play a vital role in GC, acting as plentiful and active infiltrating inflammatory cells in the TME.

MAIN BODY

In this review, the different functions and mechanisms of TAMs in GC progression, including the conversion of phenotypic subtypes; promotion of tumour proliferation, invasion and migration; induction of chemoresistance; promotion of angiogenesis; modulation of immunosuppression; reprogramming of metabolism; and interaction with the microbial community are summarised. Although the role of TAMs in GC remains controversial in clinical settings, clarifying their significance in the treatment selection and prognostic prediction of GC could support optimising TAM-centred clinicaltherapy.

CONCLUSION

In summary, we reviewed the the phenotypic polarisation, function and molecular mechanism of TAMs and their potential applications in the treatment selection and prognostic prediction of GC.

Cell diversity and immune infiltration in the parathyroid tumour microenvironment

Tumour microenvironment has been recognized as a crucial factor influencing disease progression. However, relevant features and functions are insufficiently understood in parathyroid neoplasia. Single-cell RNA sequencing was performed to profile the transcriptome of 27,251 cells from 4 parathyroid adenoma (PA) tissue samples. External transcriptomic datasets and immunofluorescence staining of a tissue microarray were set for expression validation. Eight major cell types and various subpopulations were finely identified in PA. We found that a subcluster of tumour endocrine cells with low copy number variation probably presented as a resting state. Diverse infiltrating immune cell subtypes were identified, constructing an immunosuppressive microenvironment. Tumour-associated macrophages, which indicated an anti-inflammatory phenotype, were significantly increased in PA. Inflammatory tumour-associated fibroblasts (iTAFs) were newly verified and highlighted on the role of stromal-immune crosstalk. Positive correlation between iTAFs and increased CD163+ macrophages was uncovered. Moreover, CXCL12 receptor signalling is important for tumour angiogenesis and immune infiltration. Our findings provide a comprehensive landscape interpreting tumour cell heterogeneity, cell diversity, and immune regulation in parathyroid neoplasia. The valuable resources may promote the understanding of parathyroid tumour microenvironment.

A map of the spatial distribution and tumour-associated macrophage states in glioblastoma and grade-4 IDH-mutant astrocytoma

Tumour-associated macrophages (TAMs) abundantly infiltrate high-grade gliomas and orchestrate immune response, but their diversity in isocitrate dehydrogenase (IDH)-differential grade-4 gliomas remains largely unknown. This study aimed to dissect the transcriptional states, spatial distribution and clinicopathological significance of distinct monocyte-derived TAM (Mo-TAM) and microglia-derived TAM (Mg-TAM) clusters across glioblastoma-IDH-wildtype and astrocytoma-IDH-mutant-grade 4 (Astro-IDH-mut-G4). Single-cell RNA sequencing was performed on four cases of human glioblastoma and three cases of Astro-IDH-mut-G4. Cell clustering, single-cell regulatory network inference and gene set enrichment analysis were performed to characterize the functional states of myeloid clusters. Spatial distribution of TAM subsets was determined in human glioma tissues using multiplex immunostaining. The prognostic value of different TAM-cluster specific geneset was evaluated in the TCGA glioma cohort. Profiling and unbiased clustering of 24,227 myeloid cells from glioblastoma and Astro-IDH-mut-G4 identified 9 myeloid cell clusters including monocyte, six Mo/Mg-TAM subsets, dendritic cell, and proliferative myeloid cluster. Different Mo/Mg-TAM clusters manifest functional and transcriptional diversity controlled by specific regulons. Multiplex immunostaining of subset-specific markers identified spatial enrichment of distinct TAM clusters at peri-vascular/necrotic areas in tumour parenchyma or at tumour-brain interface. Glioblastoma harboured a substantially higher number of monocytes and Mo-TAM-inflammatory cluster, whereas Astro-IDH-mut-G4 was with higher proportion of TAM subset mediating antigen presentation. Glioblastomas with higher proportion of monocytes exhibited a mesenchymal signature, increased angiogenesis and worse patient outcome. Our findings provide insight into myeloid cell diversity and its clinical relevance in IDH-differential grade-4 gliomas, and may serve as a resource for immunotherapy development. This article is protected by copyright. All rights reserved.

The Preventive Effect of the Phenotype of Tumour-Associated Macrophages, Regulated by CD39, on Colon Cancer in Mice

Background: This study was designed to investigate the effect of cluster differentiation (CD)39 and CD73 inhibitors on the expresion of tumour-associated macrophages (TAMs), M1- versus M2-tumour phenotypes in mice with colon cancer. Methods: An in vitro study of co-culture with colon cancer cells and immune cells from the bone marrow (BM) of mice was performed. After the confirmation of the effect of polyoxotungstate (POM-1) as an inhibitor of CD39 on TAMs, the mice were randomly divided into a control group without POM-1 and a study group with POM-1, respectively, after subcutaneous injection of CT26 cells. On day 14 after the injection, the mice were sacrificed, and TAMs were evaluated using fluorescence-activated cell sorting. Results: In the in vitro study, the co-culture with POM-1 significantly increased the apoptosis of CT26 cells. The cell population from the co-culture with POM-1 showed significant increases in the expression of CD11b⁺ for myeloid cells, lymphocyte antigen 6 complex, locus C (Ly6C⁺) for monocytes, M1-tumour phenotypes from TAMs, and F4/80⁺ for macrophages. In the in vivo study, tumour growth in the study group with POM-1 was significantly limited, compared with the control group without POM-1. The expressions of Ly6C⁺ and major histocompatibility complex class II⁺ for M1-tumour phenotypes from TAMs on F4/80⁺ from the tumour tissue in the study group had significantly higher values compared with the control group. Conclusion: The inhibition of CD39 with POM-1 prevented the growth of colon cancer in mice, and it was associated with the increased expression of M1-tumour phenotypes from TAMs in the cancer tissue.

Prostaglandin E3 attenuates macrophage-associated inflammation and prostate tumour growth by modulating polarization

Alternative polarization of macrophages regulates multiple biological processes. While M1‐polarized macrophages generally mediate rapid immune responses, M2‐polarized macrophages induce chronic and mild immune responses. In either case, polyunsaturated fatty acid (PUFA)‐derived lipid mediators act as both products and regulators of macrophages. Prostaglandin E₃ (PGE₃) is an eicosanoid derived from eicosapentaenoic acid, which is converted by cyclooxygenase, followed by prostaglandin E synthase successively. We found that PGE₃ played an anti‐inflammatory role by inhibiting LPS and interferon‐γ‐induced M1 polarization and promoting interleukin‐4‐mediated M2 polarization (M2a). Further, we found that although PGE₃ had no direct effect on the growth of prostate cancer cells in vitro, PGE₃ could inhibit prostate cancer in vivo in a nude mouse model of neoplasia. Notably, we found that PGE₃ significantly inhibited prostate cancer cell growth in a cancer cell‐macrophage co‐culture system. Experimental results showed that PGE₃ inhibited the polarization of tumour‐associated M2 macrophages (TAM), consequently producing indirect anti‐tumour activity. Mechanistically, we identified that PGE₃ regulated the expression and activation of protein kinase A, which is critical for macrophage polarization. In summary, this study indicates that PGE₃ can selectively promote M2a polarization, while inhibiting M1 and TAM polarization, thus exerting an anti‐inflammatory effect and anti‐tumour effect in prostate cancer.

Existence of Staphylococcus aureus correlates with the progression of extramammary Paget's disease: potential involvement of interleukin-17 and M2-like macrophage polarization

BACKGROUND

The microbiome plays an important role in the tumour microenvironment (TME).

OBJECTIVES

In this study, we investigated the clinical significance of the microbiota in extramammary Paget's disease (EMPD).

MATERIALS & METHODS

Patients with EMPD, treated between March 2007 and September 2019 at Kumamoto University Hospital, were investigated retrospectively. Inclusion criteria included: histological diagnosis of EMPD, inspection of the bacterial culture of the cancer lesion using swab sampling, and availability of sufficient tissue in paraffin blocks for immunohistochemistry. For the latter, primary antibodies against IL-17, CD163 and ionized calcium-binding adapter molecule 1 (Iba1) were used.

RESULTS

Bacterial cultures of the cancer lesion revealed that Staphylococcus aureus (S. aureus) was highly prevalent in EMPD patients, with dermal invasion or lymph node metastasis, compared to patients without these findings. Furthermore, the number of IL-17-positive cells and CD163-positive M2-like macrophages (pro-tumour macrophages) were increased in EMPD tissues with S. aureus. Moreover, the number of IL-17-producing cells in EMPD tissues positively correlated with the accumulation of CD163-positive M2-like macrophages. In addition, the percentage of CD163-positive cells within Iba-1-positive macrophages (total macrophages) was also significantly elevated in EMPD tissues with S. aureus.

CONCLUSION

Based on these findings, S. aureus may exacerbate the pathological condition of EMPD via the accumulation of IL-17 and M2-like macrophages.

Tumor-associated macrophage polarization promotes the progression of esophageal carcinoma

The immune response facilitated by tumor-associated macrophages is a vital determinant of tumor progression. We identified differentially expressed genes between various macrophage phenotypes in the Gene Expression Omnibus, and used Kaplan-Meier Plotter to determine which of them altered the prognosis of esophageal carcinoma patients. Fibrinogen-like protein 2 (FGL2), an immunosuppressive factor in the tumor microenvironment of various cancers, was upregulated in M2 macrophages, and higher FGL2 expression was associated with poorer survival in esophageal carcinoma patients. Using the TIMER database, we found that FGL2 expression correlated positively with the levels of immune markers of infiltrating B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils and dendritic cells in esophageal carcinoma samples. Correlation analyses in cBioPortal revealed that the mRNA levels of FGL2 correlated strongly with those of interleukin 10, matrix metalloproteinase 9, C-C motif chemokine ligand 5, T-cell immunoglobulin mucin 3, interleukin 13, vascular cell adhesion molecule 1, macrophage colony-stimulating factor and fibroblast growth factor 7 in esophageal carcinoma tissues. The same cytokines were upregulated when esophageal squamous cell carcinoma cells were co-cultured with M2-like tumor-associated macrophages. Thus, by secreting FGL2, M2-like tumor-associated macrophages may create an immunosuppressive tumor microenvironment that induces the occurrence and progression of esophageal carcinoma.

CSF-1R inhibition disrupts the dialog between leukaemia cells and macrophages and delays leukaemia progression

Research in the last few years has revealed that leukaemic cells can remodel the bone marrow niche into a permissive environment favouring leukaemic stem cell expansion. Tumour-associated macrophages (TAMs) are prominent components of the tumour microenvironment and play an important role in the onset and progression of solid tumours. However, little is known about their role in the development of acute lymphoblastic leukaemia (ALL). Using a unique mouse model of T-ALL induced by injection of EL4 T-cell lymphoma cells to syngeneic C57BL/6 mice, we report herein that ALL leads to the invasion of leukaemia-associated monocyte-derived cells (LAMs) into the bone marrow and spleen of T-ALL mice. Furthermore, we found that leukaemia cells could polarize bone marrow-derived macrophages (BMDMs) into LAMs. In turn, LAMs were able to protect leukaemia cells from drug-induced apoptosis in vitro. Therapies targeted against the TAMs by inhibiting colony stimulating factor-1 receptor (CSF-1R) have emerged as a promising approach for cancer treatment. In this study, we demonstrate that CSF-1R inhibition inhibits the viability of BMDMs, blocks LAMs polarization and reduces the abundance of LAMs in T-ALL mice. In vivo, combination treatment of CSF-1R inhibitor and vincristine (VCR) dramatically increased the survival of T-ALL mice and delayed leukaemia progression compared with VCR monotherapy. Finally, these data reinforce the role of microenvironments in leukaemia and suggest that macrophages are a potential target for the development of novel therapeutic strategies in T-ALL.

Triple knockdown of CDC37, HSP90-alpha and HSP90-beta diminishes extracellular vesicles-driven malignancy events and macrophage M2 polarization in oral cancer

Evidence has been accumulating to indicate that extracellular vesicles (EVs), including exosomes, released by cancer cells can foster tumour progression. The molecular chaperones – CDC37, HSP90α and HSP90β play key roles in cancer progression including epithelial-mesenchymal transition (EMT), although their contribution to EVs-mediated cell–cell communication in tumour microenvironment has not been thoroughly examined. Here we show that triple depletion of the chaperone trio attenuates numerous cancer malignancy events exerted through EV release. Metastatic oral cancer-derived EVs (MEV) were enriched with HSP90α HSP90β and cancer-initiating cell marker CD326/EpCAM. Depletion of these chaperones individually induced compensatory increases in the other chaperones, whereas triple siRNA targeting of these molecules markedly diminished the levels of the chaperone trio and attenuated EMT. MEV were potent agents in initiating EMT in normal epithelial cells, a process that was attenuated by the triple chaperone depletion. The migration, invasion, and in vitro tumour initiation of oral cancer cells were significantly promoted by MEV, while triple depletion of CDC37/HSP90α/β reversed these MEV-driven malignancy events. In metastatic oral cancer patient-derived tumours, HSP90β was significantly accumulated in infiltrating tumour-associated macrophages (TAM) as compared to lower grade oral cancer cases. HSP90-enriched MEV-induced TAM polarization to an M2 phenotype, a transition known to support cancer progression, whereas the triple chaperone depletion attenuated this effect. Mechanistically, the triple chaperone depletion in metastatic oral cancer cells effectively reduced MEV transmission into macrophages. Hence, siRNA-mediated knockdown of the chaperone trio (CDC37/HSP90α/HSP90β) could potentially be a novel therapeutic strategy to attenuate several EV-driven malignancy events in the tumour microenvironment.

Abbreviations

CDC37: cell division control 37; EMT: epithelial-mesenchymal transmission; EV: extracellular vesicles; HNSCC: head and neck squamous cell carcinoma; HSP90: heat shock protein 90; TAM: tumour-associated macrophage

Resolvin D1 and D2 inhibit tumour growth and inflammation via modulating macrophage polarization

Plastic polarization of macrophage is involved in tumorigenesis. M1-polarized macrophage mediates rapid inflammation, entity clearance and may also cause inflammation-induced mutagenesis. M2-polarized macrophage inhibits rapid inflammation but can promote tumour aggravation. ω-3 long-chain polyunsaturated fatty acid (PUFA)-derived metabolites show a strong anti-inflammatory effect because they can skew macrophage polarization from M1 to M2. However, their role in tumour promotive M2 macrophage is still unknown. Resolvin D1 and D2 (RvD1 and RvD2) are docosahexaenoic acid (DHA)-derived docosanoids converted by 15-lipoxygenase then 5-lipoxygenase successively. We found that although dietary DHA can inhibit prostate cancer in vivo, neither DHA (10 μmol/L) nor RvD (100 nmol/L) can directly inhibit the proliferation of prostate cancer cells in vitro. Unexpectedly, in a cancer cell-macrophage co-culture system, both DHA and RvD significantly inhibited cancer cell proliferation. RvD1 and RvD2 inhibited tumour-associated macrophage (TAM or M2d) polarization. Meanwhile, RvD1 and RvD2 also exhibited anti-inflammatory effects by inhibiting LPS-interferon (IFN)-γ-induced M1 polarization as well as promoting interleukin-4 (IL-4)-mediated M2a polarization. These differential polarization processes were mediated, at least in part, by protein kinase A. These results suggest that regulation of macrophage polarization using RvDs may be a potential therapeutic approach in the management of prostate cancer.

Circulating extracellular vesicle-associated CD163 and CD206 in multiple myeloma

OBJECTIVES

Extracellular vesicles (EVs) are important for intercellular signalling in cancer. Tumour-associated macrophages, expressing the haemoglobin-haptoglobin and mannose receptors CD163 and CD206, are crucial for cancer progression. We recently identified CD163 on EVs in the circulation as a fraction of total soluble CD163 (sCD163). Here, we investigated the presence of CD163 and CD206-positive EVs (EV-CD163, EV-CD206) in patients with multiple myeloma (MM).

METHODS

We enrolled patients with MM (n = 32), monoclonal gammopathy of undetermined significance (MGUS) (n = 8) and healthy donors (n = 16). Plasma protein levels were determined by ELISA before and after vesicle precipitation. Monocytes were examined by flow cytometry, and leucocyte CD163 mRNA by qPCR.

RESULTS

Fractions of EV-CD163 and EV-CD206 were significantly elevated in patients with newly diagnosed MM (median = 39.8%, 76.5%, respectively) compared to patients with relapse (15.6%, P = .02, 42.5%, P = .003), remission (16.9%, P < .0001, 25.2%, P < .0001), MGUS (17.8%, P < .01, 33.1%, P = .0005) and healthy donors (14.8%, P < .0001, 35.5%, P < .0001). Whole blood CD163 mRNA did not vary between the groups. The intermediate monocyte subset showed a higher CD163 expression in newly diagnosed patients.

CONCLUSIONS

Our results indicate that macrophage-derived EVs may play a role in the late phase of malignant progression of MM, and encourage further EV investigations in functional experiments.

Regulatory T cells and M2-polarized tumour-associated macrophages are associated with the oncogenesis and progression of oral squamous cell carcinoma

Regulatory T cells (Tregs) and tumour-associated macrophages (TAMs) contribute to the tumour microenvironment by inhibiting anti-tumour immune responses. This study was performed to investigate the roles of Tregs and TAMs in oral squamous cell carcinoma (OSCC) and oral epithelial precursor lesions (OEPL). The expression of Treg markers CD25 and FoxP3 and TAM markers CD163 and CD204 was investigated in 82 OSCC and 45 OEPL specimens, and their associations with clinicopathological parameters were analyzed. Correlations were found among CD25, FoxP3, CD163, and CD204 levels (P <  0.001), and these targets were up-regulated in OSCC compared to OEPL (P <  0.001). In OSCC, infiltration of Tregs and/or M2 TAMs was associated with sex and clinicopathological features, such as tumour size, nodal metastasis, tissue differentiation, stromal reaction, invasive behaviour, and invasive depth. In OEPL, CD25, FoxP3, CD163, and CD204 immunoreactivities were significantly associated with sex, postoperative recurrence, and cancerization to OSCC. This study is novel in showing that the infiltration of Tregs and M2 TAMs is significantly associated with the progression of premalignant lesions to OSCC. This suggests that these cells represent prognostic biomarkers for premalignant lesion progression and that immunotherapeutic approaches to control Treg/M2 TAM numbers could protect against progression to malignancy.

Helicobacter pylori-induced exosomal MET educates tumour-associated macrophages to promote gastric cancer progression

Helicobacter pylori (H. pylori) infection triggers chronic inflammation that has been associated with gastric cancer (GC). Exosomes are small extracellular vesicles that have become the key mediators of intercellular communication. In this study, we investigated exosome‐mediated communication between H. pylori‐infected GC cells and macrophages, focusing on the transfer of activated mesenchymal‐epithelial transition factor (MET). We observed a significant decrease in MET protein expression in GC cells after infection with H. pylori, whereas MET mRNA levels remained unchanged. Intriguingly, MET expression, specifically the phosphorylated active form, was increased in exosomes released from H. pylori‐infected GC cells. Confocal microscopy and Western blotting analyses showed that these exosomes containing MET were delivered to and internalized by macrophages. Indeed, in human GC tissues positive for H. pylori, we also observed that activated MET was highly expressed in tumour‐infiltrating macrophages. After internalization, exosomal MET then appeared to educate the macrophages towards a pro‐tumorigenesis phenotype. This included exosomal MET‐mediated stimulation of proinflammatory cytokine secretion IL‐1β, which subsequently promoted tumour growth and progression in vitro and in vivo. Taken together, these data were the first to demonstrate H. pylori infection‐induced upregulation of activated MET in exosomes and the pro‐tumorigenic effect on tumour‐associated macrophages.

IRE1α inhibition by natural compound genipin on tumour associated macrophages reduces growth of hepatocellular carcinoma

Accumulating evidences postulated the influential roles of macrophages in mediating hepatocellular carcinoma (HCC) initiation and progression. In this study, we demonstrate that a small molecule, genipin reduced HCC growth through suppressing IRE1α-mediated infiltration and priming of tumour associated macrophages (TAMs). Oral administration of genipin (30mg/kg/2days) suppressed orthotopic HCC tumour growth without challenging the viability and proliferation of HCC cells. Genipin reduced infiltration of inflammatory monocytes into liver and tumour thereby suppressed TAMs presence in HCC microenvironment. Suppression of HCC growth was diminished in HCC-implanted mice with depletion of TAMs by liposome clodronate. Genipin inhibited the TAMs migration, and reduced expression of TAMs-derived inflammatory cytokines that favors HCC proliferation. This is revealed by the in vivo deletion of IRE1α on TAMs in genipin-treated HCC-implanted mice. Diminishing IRE1α neutralised the inhibitory effect of genipin on TAMs. Silencing the expression of IRE1α greatly reduced TAMs migration and expression of inflammatory cytokines that prime HCC proliferation. Suppression of IRE1α led to reduced XBP-1 splicing and NF-κB activation. The reduced association of IRE1α with TRAF2 and IKK complex may be responsible for the genipin-mediated inactivation of NF-κB. The findings show the important role of TAMs in inhibitory effect of genipin on HCC, and TAMs-expressing IRE1α as a promising target for disrupting the tumour environment that favor of HCC development.

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.

γ-Secretase inhibitor reduces immunosuppressive cells and enhances tumour immunity in head and neck squamous cell carcinoma

Immune evasion is a hallmark feature of cancer, and it plays an important role in tumour initiation and progression. In addition, tumour immune evasion severely hampers the desired antitumour effect in multiple cancers. In this study, we aimed to investigate the role of the Notch pathway in immune evasion in the head and neck squamous cell carcinoma (HNSCC) microenvironment. We first demonstrated that Notch1 signaling was activated in a Tgfbr1/Pten-knockout HNSCC mouse model. Notch signaling inhibition using a γ-secretase inhibitor (GSI-IX, DAPT) decreased tumour burden in the mouse model after prophylactic treatment. In addition, flow cytometry analysis indicated that Notch signaling inhibition reduced the sub-population of myeloid-derived suppressor cells (MDSCs), tumour-associated macrophages (TAMs) and regulatory T cells (Tregs), as well as immune checkpoint molecules (PD1, CTLA4, TIM3 and LAG3), in the circulation and in the tumour. Immunohistochemistry (IHC) of human HNSCC tissues demonstrated that elevation of the Notch1 downstream target HES1 was correlated with MDSC, TAM and Treg markers and with immune checkpoint molecules. These results suggest that modulating the Notch signaling pathway may decrease MDSCs, TAMs, Tregs and immune checkpoint molecules in HNSCC.

Collaboration of cancer-associated fibroblasts and tumour-associated macrophages for neuroblastoma development

Neuroblastoma is the most common extracranial solid tumour in children and is histologically classified by its Schwannian stromal cells. Although having fewer Schwannian stromal cells is generally associated with more aggressive phenotypes, the exact roles of other stromal cells (mainly macrophages and fibroblasts) are unclear. Here, we examined 41 cases of neuroblastoma using immunohistochemistry for the tumour-associated macrophage (TAM) markers CD68, CD163, and CD204, and a cancer-associated fibroblast (CAF) marker, alpha smooth muscle actin (αSMA). Each case was assigned to low/high groups on the basis of the number of TAMs or three groups on the basis of the αSMA-staining area for CAFs. Both the number of TAMs and the area of CAFs were significantly correlated with clinical stage, MYCN amplification, bone marrow metastasis, histological classification, histological type, and risk classification. Furthermore, TAM settled in the vicinity of the CAF area, suggesting their close interaction within the tumour microenvironment. We next determined the effects of conditioned medium of a neuroblastoma cell line (NBCM) on bone marrow-derived mesenchymal stem cells (BM-MSCs) and peripheral blood mononuclear cell (PBMC)-derived macrophages in vitro. The TAM markers CD163 and CD204 were significantly up-regulated in PBMC-derived macrophages treated with NBCM. The expression of αSMA by BM-MSCs was increased in NBCM-treated cells. Co-culturing with CAF-like BM-MSCs did not enhance the invasive ability but supported the proliferation of tumour cells, whereas tumour cells co-cultured with TAM-like macrophages had the opposite effect. Intriguingly, TAM-like macrophages enhanced not only the invasive abilities of tumour cells and BM-MSCs but also the proliferation of BM-MSCs. CXCL2 secreted from TAM-like macrophages plays an important role in tumour invasiveness. Taken together, these results indicate that PBMC-derived macrophages and BM-MSCs are recruited to a tumour site and activated into TAMs and CAFs, respectively, followed by the formation of favourable environments for neuroblastoma progression. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The impact of inflammatory cells in malignant ascites on small intestinal ICCs' morphology and function

Malignant ascites is one of the common complication at the late stage of abdominal cancers, which may deteriorate the environment of abdominal cavity and lead to potential damage of functional cells. Interstitial cells of Cajal (ICCs) are mesoderm-derived mesenchymal cells that function normal gastrointestinal motility. The pathological changes of ICCs or the reduced number may lead to the motility disorders of gastrointestinal tract. In this study, through analysis of malignant ascites which were obtained from cancer patients, we found that inflammatory cells, including tumour-infiltrating lymphocytes, accounted for 17.26 ± 1.31% and tumour-associated macrophages, occupied 19.06 ± 2.27% of total cells in the ascites, suggesting these inflammatory cells, in addition to tumour cells, may exert important influence on the tumour environment of abdominal cavity. We further demonstrated that the number of mice ICCs were significant decreased, as well as morphological and functional damage when ICCs were in the simulated tumour microenvironment in vitro. Additionally, we illustrated intestinal myoelectrical activity reduced and irregular with morphological changes of ICCs using the mice model of malignant ascites. In conclusion, our data suggested that inflammatory cells in malignant ascites may damage ICCs of the small intestine and lead to intestinal motility disorders.

High numbers of macrophages, especially M2-like (CD163-positive), correlate with hyaluronan accumulation and poor outcome in breast cancer

AIMS

High amounts of tumour-associated macrophages (TAMs) and hyaluronan (HA) correlate with tumour aggressiveness in breast cancer, but the relationship between these parameters is unclear. The aim of this study was to assay the numbers of TAMs in 278 human breast cancer cases, and their correlations with HA-related factors, clinical variables, and outcome.

METHODS AND RESULTS

The immunoreactivities for CD163 and CD68 were considered as indicators for M2-like and all TAMs, respectively. The numbers of TAMs were counted in at least four hot spots, and averaged to represent the numbers of TAMs in each section. In the statistical analyses, the numbers were graded as either low or high according to the median. High numbers of TAMs correlated with a high tumour HA content, HA synthases, CD44 positivity, and poor outcome. The number of CD163-positive cells represented a strong independent prognostic factor. There was also a significant correlation between obesity and a high number of CD163-positive cells.

CONCLUSIONS

Concurrent increases in TAMs and HA in breast cancer indicate that the accumulation of HA facilitates macrophage infiltration and inflammatory responses during human breast cancer progression.

Muscle wasting in cancer

Skeletal muscle loss appears to be the most significant clinical event in cancer cachexia and is associated with a poor outcome. With regard to such muscle loss, despite extensive study in a range of models, there is ongoing debate as to whether a reduction in protein synthesis, an increase in degradation or a combination of both is the more relevant. Each model differs in terms of key mediators and the pathways activated in skeletal muscle. Certain models do suggest that decreased synthesis accompanied by enhanced protein degradation via the ubiquitin proteasome pathway (UPP) is important. Murine models tend to involve rapid development of cachexia and may represent more acute muscle atrophy rather than the chronic wasting observed in humans. There is a paucity of human data both at a basic descriptive level and at a molecular/mechanism level. Progress in treating the human form of cancer cachexia can only move forwards through carefully designed large randomised controlled clinical trials of specific therapies with validated biomarkers of relevance to underlying mechanisms. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.