Prognostic impact of CD68+ tumor-associated macrophages in hepatocellular carcinoma: A meta-analysis.

BACKGROUND: Evidence from clinical research suggests that the tumor-associated macrophages (TAMs) were associated with prognosis in hepatocellular carcinoma (HCC). The aim of the present meta-analysis was to conduct a qualitative analysis to explore the prognostic value of CD68 + TAMs in HCC. METHODS: This study conducted a systematic search in Pubmed, Embase, the Cochrane Library and China National Knowledge Internet from inception of the databases to November 2023. The hazard ratio (HR) and 95% confidence interval (CI) were calculated employing fixed-effect or random-effect models depending on the heterogeneity of the included trials. The Newcastle-Ottawa Scale was used to evaluate the risk of prejudice. RESULTS: We analyzed 4362 HCC patients. The present research indicated that the expression levels Of CD68 + TAMs were significantly associated with overall survival (OS) (HR = 1.55, 95% CI: 1.30-1.84) and disease-free survival (DFS) (HR = 1.44, 95% CI: 1.17-1.78). Subgroup analysis based on cutoff values showed that the "Median" subgroup showed a pooled HR of 1.66 with a 95% CI ranging from 1.32 to 2.08, which was slightly higher than the "Others" subgroup that exhibited a pooled HR of 1.40 and a 95% CI of 1.07 to 1.84. The "PT" subgroup had the highest pooled HR of 1.68 (95% CI: 1.19-2.37), indicating a worse OS compared to the "IT" (pooled HR: 1.50, 95% CI: 1.13-2.01) and "Mix" (pooled HR: 1.52, 95% CI: 1.03-2.26) subgroups. Moreover, in the sample size-based analysis, studies with more than 100 samples (>100) exhibited a higher pooled HR of 1.57 (95% CI: 1.28 to 1.93) compared to studies with fewer than 100 samples (<100), which had a pooled HR of 1.45 (95% CI: 1.00-2.10). CONCLUSIONS: The analysis suggests that CD68 + TAMs were significantly associated with unfavorable OS and DFS in HCC patients, and may be served as a promising prognostic biomarker in HCC. However, more large-scale trials are needed to study the clinical value of TAMs in HCC.

Non-apoptotic regulated cell death mediates reprogramming of the tumour immune microenvironment by macrophages.

Tumour immune microenvironment (TIME) plays an indispensable role in tumour progression, and tumour-associated macrophages (TAMs) are the most abundant immune cells in TIME. Non-apoptotic regulated cell death (RCD) can avoid the influence of tumour apoptosis resistance on anti-tumour immune response. Specifically, autophagy, ferroptosis, pyroptosis and necroptosis mediate the crosstalk between TAMs and tumour cells in TIME, thus reprogram TIME and affect the progress of tumour. In addition, although some achievements have been made in immune checkpoint inhibitors (ICIs), there is still defect that ICIs are only effective for some people because non-apoptotic RCD can bypass the apoptosis resistance of tumour. As a result, ICIs combined with targeting non-apoptotic RCD may be a promising solution. In this paper, the basic molecular mechanism of non-apoptotic RCD, the way in which non-apoptotic RCD mediates crosstalk between TAMs and tumour cells to reprogram TIME, and the latest research progress in targeting non-apoptotic RCD and ICIs are reviewed.

Surgical tumor-derived nanoplatform targets tumor-associated macrophage for personalized postsurgical cancer immunotherapy.

Directly activating CD8+ T cells within the tumor through antigen-presenting cells (APCs) hold promise for tumor elimination. However, M2-like tumor-associated macrophages (TAMs), the most abundant APCs in tumors, hinder CD8+ T cell activation due to inefficient antigen cross-presentation. Here, we demonstrated a personalized nanotherapeutic platform using surgical tumor-derived galactose ligand-modified cancer cell membrane (CM)-coated cysteine protease inhibitor (E64)-loaded mesoporous silica nanoparticles for postsurgical cancer immunotherapy. The platform targeted M2-like TAMs and released E64 within lysosomes, which reshaped antigen cross-presentation and directly activated CD8+ T cells, thus suppressing B16-OVA melanoma growth. Furthermore, this platform, in combination with anti-PD-L1 antibodies, enhanced the therapeutic efficacy and substantially inhibited 4T1 tumor growth. CMs obtained from surgically resected tumors were used to construct a personalized nanotherapeutic platform, which, in synergy with immune checkpoint blockade (ICB), effectively inhibited postsurgical tumor recurrence in 4T1 tumor. Our work offered a robust, safe strategy for cancer immunotherapy and prevention of postsurgical tumor recurrence.

Lentinan inhibits cell invasion via M2 polarization of tumor-associated macrophages and Wnt/ß-catenin signaling in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is an aggressive and devastating cancer due to its metastasis induced by increased invasion. Lentinan is a polysaccharide exerting antitumor roles in multiple cancers, including lung cancer. However, the influence of lentinan on cell invasion in NSCLC remains unclear. Cell invasion was detected by transwell analysis. Matrix metallopeptidase 9 (MMP9) levels were measured through immunofluorescence staining. The markers arginase-1 (Arg-1), CD206 and interleukin (IL)-10 (IL-10) of M2 macrophages, Wnt3a, and ß-catenin levels were measured by western blot or enzyme linked immunosorbent assay. Lentinan did not affect cell viability and proliferation in NSCLC cells. Lentinan suppressed cell invasion and reduced the expression and secretion of MMP9. Lentinan attenuated also M2 polarization of tumor-associated macrophages. Moreover, lentinan mitigated the M2 macrophage conditioned medium-mediated cell invasion and MMP9 alterations in NSCLC cells. Lentinan inhibited the activation of the Wnt/ß-catenin signaling in NSCLC cells. The activated Wnt/ß-catenin pathway reversed the suppressive effects of lentinan on cell invasion and MMP9 level in NSCLC cells. In conclusion, lentinan reduces cell invasion in NSCLC cells by inhibiting the M2 polarization of tumor-associated macrophages and the Wnt/ß-catenin signaling.

Exosome-transmitted podoplanin promotes tumor-associated macrophage-mediated immune tolerance in glioblastoma.

AIMS: Glioblastoma is the most frequent and aggressive primary brain tumor, characterized by rapid disease course and poor treatment responsiveness. The abundance of immunosuppressive macrophages in glioblastoma challenges the efficacy of novel immunotherapy. METHODS: Bulk RNA-seq and single-cell RNA-seq of glioma patients from public databases were comprehensively analyzed to illustrate macrophage infiltration patterns and molecular characteristics of podoplanin (PDPN). Multiplexed fluorescence immunohistochemistry staining of PDPN, GFAP, CD68, and CD163 were performed in glioma tissue microarray. The impact of PDPN on macrophage immunosuppressive polarization was investigated using a co-culture system. Bone marrow-derived macrophages (BMDMs) and OT-II T cells isolated from BALB/c and OT-II mice respectively were co-cultured to determine T-cell adherence. Pathway alterations were probed through RNA sequencing and western blot analyses. RESULTS: Our findings demonstrated that PDPN is notably correlated with the expression of CD68 and CD163 in glioma tissues. Additionally, macrophages phagocytosing PDPN-containing EVs (EVsPDPN ) from GBM cells presented increased CD163 expression and augmented secretion of immunoregulatory cytokine (IL-6, IL-10, TNF-α, and TGF-ß1). PDPN within EVs was also associated with enhanced phagocytic activity and reduced MHC II expression in macrophages, compromising CD4+ T-cell activation. CONCLUSIONS: This investigation underscores that EVsPDPN derived from glioblastoma cells contributes to M2 macrophage-mediated immunosuppression and is a potential prognostic marker and therapeutic target in glioblastoma.

Prognostic and clinical significance of tumor-associated macrophages in esophageal squamous cell carcinoma after surgery: do biomarkers and distributions matter?

BACKGROUND: The role of tumor-associated macrophages (TAMs) in patients with esophageal squamous cell carcinoma (ESCC) following surgery remains controversial. Hence, we performed the present study to systematically analyze the prognostic and clinical significance of distinct TAMs biomarkers and distributions in ESCC patients underwent surgery. METHODS: PubMed, Web of Science, and EMBASE databases were searched up to March 31, 2023. The pooled analysis was conducted to evaluate the effects of TAMs on overall survival (OS), disease-free survival (DFS), and clinicopathological characteristics using fixed-effects or random-effect model. RESULTS: Involving a total of 2,502 ESCC patients underwent surgery from 15 studies, the results suggested that the total count of CD68+ TAMs was inversely associated with OS and DFS in ESCC patients, which was also noticed in the relationship of CD68+ TAMs in tumor islet (TI) with OS (all P<0.05), although no association between CD68+ TAMs in tumor stroma (TS) and OS (P>0.05). Moreover, either islet or stromal CD163+ TAMs density was a prognostic factor ESCC (all P<0.05). Similarly, an elevated CD204+ TAMs density in TI predicted a poor DFS (P<0.05), although CD204+ TAMs in TI had no relationship with OS (P>0.05). Besides, a high CD68+ TAMs density was significantly associated with lymphatic vessel invasion, vascular invasion, and lymph node metastasis (all P<0.05). CONCLUSION: Our results demonstrated the prognostic and clinical significance of TAMs in ESCC patients underwent surgery. TAMs should be considered a target that could improve prognostic stratification and clinical outcomes in ESCC after surgery.

Specific lineage transition of tumor-associated macrophages elicits immune evasion of ascitic tumor cells in gastric cancer with peritoneal metastasis.

BACKGROUND: Gastric cancer with peritoneal metastasis (PM-GC), recognized as one of the deadliest cancers. However, whether and how the tumor cell-extrinsic tumor microenvironment (TME) is involved in the therapeutic failure remains unknown. Thus, this study systematically assessed the immunosuppressive tumor microenvironment in ascites from patients with PM-GC, and its contribution to dissemination and immune evasion of ascites-disseminated tumor cells (aDTCs). METHODS: Sixty-three ascites and 43 peripheral blood (PB) samples from 51 patients with PM-GC were included in this study. aDTCs in ascites and circulating tumor cells (CTCs) in paired PB were immunophenotypically profiled. Using single-cell RNA transcriptional sequencing (scRNA-seq), crosstalk between aDTCs and the TME features of ascites was inspected. Further studies on the mechanism underlying aDTCs-immune cells crosstalk were performed on in vitro cultured aDTCs. RESULTS: Immune cells in ascites interact with aDTCs, prompting their immune evasion. Specifically, we found that the tumor-associated macrophages (TAMs) in ascites underwent a continuum lineage transition from cathepsinhigh (CTShigh) to complement 1qhigh (C1Qhigh) TAM. CTShigh TAM initially attracted the metastatic tumor cells to ascites, thereafter, transitioning terminally to C1Qhigh TAM to trigger overproliferation and immune escape of aDTCs. Mechanistically, we demonstrated that C1Qhigh TAMs significantly enhanced the expression of PD-L1 and NECTIN2 on aDTCs, which was driven by the activation of the C1q-mediated complement pathway. CONCLUSIONS: For the first time, we identified an immunosuppressive macrophage transition from CTShigh to C1Qhigh TAM in ascites from patients with PM-GC. This may contribute to developing potential TAM-targeted immunotherapies for PM-GC.

The regulatory role of autophagy between TAMs and tumor cells.

Cancer has become a global public health problem and its harmful effects have received widespread attention. Conventional treatments such as surgical resection, radiotherapy and other techniques are applicable to clinical practice, but new drugs are constantly being developed and other therapeutic approaches, such as immunotherapy are being applied. In addition to studying the effects on individual tumor cells, it is important to explore the role of tumor microenvironment on tumor cell development since tumor cells do not exist alone but in the tumor microenvironment. In the tumor microenvironment, tumor cells are interconnected with other stromal cells and influence each other, among which tumor-associated macrophages (TAMs) are the most numerous immune cells. At the same time, it was found that cancer cells have different levels of autophagy from normal cells. In cancer therapy, the occurrence of autophagy plays an important role in promoting tumor cell death or inhibiting tumor cell death, and is closely related to the environment. Therefore, elucidating the regulatory role of autophagy between TAMs and tumor cells may be an important breakthrough, providing new perspectives for further research on antitumor immune mechanisms and improving the efficacy of cancer immunotherapy.

Programmed Cell Death Ligand 1 Expression in CD163 + Tumor-associated Macrophages in Cancer Gland Rupture Microenvironment.

In this study, we aimed to examine the relationship among cancer gland rupture microenvironment, programmed cell death ligand 1 (PD-L1) expression in CD163 + tumor-associated macrophages (TAMs), and prognosis in colon adenocarcinoma. A total of 122 patients were diagnosed with colon adenocarcinoma between 2010 and 2019. PD-L1 + (clone 22C3) "macrophage scores" in the microenvironment of cancer gland rupture were calculated. The effects of these variables on prognosis were statistically analyzed. CD163 + TAMs were denser in the cancer gland rupture microenvironment. PD-L1 + TAMs were observed in the tumor periphery, and there was a significant difference between the rates of PD-L1 expression in TAMs and survival time (log-rank = 10.46, P = 0.015), clinical stage 2 ( P = 0.038), and primary tumor 3 and primary tumor 4 cases ( P = 0.004, P = 0.013). The risk of mortality was 4.070 times higher in patients with a PD-L1 expression rate of ≥1% in CD163 + TAMs. High PD-L1 expression in CD163 + TAMs is associated with poor overall survival. Therefore, blocking PD-L1 in CD163 + TAMs can be used as a target for immunotherapy.

Tumor-associated macrophages in non-small-cell lung cancer: From treatment resistance mechanisms to therapeutic targets.

Non-small cell lung cancer (NSCLC) remains one of the leading causes of cancer-related deaths worldwide. Different treatment approaches are typically employed based on the stage of NSCLC. Common clinical treatment methods include surgical resection, drug therapy, and radiation therapy. However, with the introduction and utilization of immune checkpoint inhibitors, cancer treatment has entered a new era, completely revolutionizing the treatment landscape for various cancers and significantly improving overall patient survival. Concurrently, treatment resistance often poses a critical challenge, with many patients experiencing disease progression following an initial response due to treatment resistance. Increasing evidence suggests that the tumor microenvironment (TME) plays a pivotal role in treatment resistance. Tumor-associated macrophages (TAMs) within the TME can promote treatment resistance in NSCLC by secreting various cytokines activating signaling pathways, and interacting with other immune cells. Therefore, this article will focus on elucidating the key mechanisms of TAMs in treatment resistance and analyze how targeting TAMs can reduce the levels of treatment resistance in NSCLC, providing a comprehensive understanding of the principles and approaches to overcome treatment resistance in NSCLC.

Expression of CD68+ Tumor associated macrophages in relation to ß-catenin in carcinoma stomach.

Background: With no unified system for tumor associated macrophages (TAMs) density assessment, limited information is available on their relationship with ß-catenin expression. Aim: To evaluate the density of CD68+ TAMs in gastric adenocarcinoma samples by immunohistochemistry and correlate it with grade, stage, invasion, and beta-catenin. Designs and Settings: Formalin fixed paraffin embedded (FFPE) blocks from gastrectomy specimens of proven gastric adenocarcinoma were prospectively and retrospectively were studied over a period of two years. Materials and Methods: Immunohistochemistry with CD68 and ß-catenin was performed. TAM density was qualitatively compared in "tumor" versus "stroma" and "tumor" versus "non-tumor" regions. Quantitative CD68+ TAM density was assessed using different methods and compared. Cases were classified as high and low TAM based on the median value and correlated with histologic type, location, grade, stage and ß-catenin expression pattern. Statistical Analysis: Spearman's rank correlation test was used to compare the different methods of TAM density evaluation. The categorical variables were studied using Pearson's Chi-square or Fisher's exact test. CD68+ TAM density and ß-catenin expression were correlated by analysis of variance. A P value ≤ 0.05 was taken as statistically significant. Results: The CD68+ TAMs in the "tumor" versus "non-tumor" area (p = 0.34) and "tumor" versus "stroma distribution" (p = 0.81) did not show any statistical significance. All methods of TAM density were found to be comparable. High TAM group is significantly associated with lymphovascular invasion, tumor depth, lymph node metastasis, and abnormal ß-catenin expression. Conclusion: TAMs density plays an important role in the tumor stage. Macrophages may possibly induce gastric cancer invasiveness by activating ß-catenin pathway.

Regulation of regulatory T cells and tumor-associated macrophages in gastric cancer tumor microenvironment.

INTRODUCTION: Despite advancements in the methods for prevention and early diagnosis of gastric cancer (GC), GC continues to be the fifth in incidence among major cancers and the third most common cause of cancer-related death. The therapeutic effects of surgery and drug treatment are still unsatisfied and show notable differences according to the tumor microenvironment (TME) of GC. METHODS: Through screening Pubmed, Embase, and Web of Science, we identified and summarized the content of recent studies that focus on the investigation of Helicobacter pylori (Hp) infection, regulatory T cells (Tregs), and tumor-associated macrophages (TAMs) in the TME of GC. Furthermore, we searched and outlined the clinical research progress of various targeted drugs in GC treatment including CTLA-4, PD-1\PD-L1, and VEGF/VEGFR. RESULTS: In this review, the findings indicate that Hp infection causes local inflammation and leads to immunosuppressive environment. High Tregs infiltration in the TME of GC is associated with increased induction and recruitment; the exact function of infiltrated Tregs in GC was also affected by phenotypes and immunosuppressive molecules. TAMs promote the development and metastasis of tumors, the induction, recruitment, and function of TAMs in the TME of gastric cancer are also regulated by various factors. CONCLUSION: Discussing the distinct tumor immune microenvironment (TIME) of GC can deepen our understanding on the mechanism of cancer immune evasion, invasion, and metastasis, help us to reduce the incidence of GC, and guide the innovation of new therapeutic targets for GC eventually.

Tumor-associated macrophages in colorectal cancer metastasis: molecular insights and translational perspectives.

Metastasis is the leading cause of high mortality in colorectal cancer (CRC), which is not only driven by changes occurring within the tumor cells, but is also influenced by the dynamic interaction between cancer cells and components in the tumor microenvironment (TME). Currently, the exploration of TME remodeling and its impact on CRC metastasis has attracted increasing attention owing to its potential to uncover novel therapeutic avenues. Noteworthy, emerging studies suggested that tumor-associated macrophages (TAMs) within the TME played important roles in CRC metastasis by secreting a variety of cytokines, chemokines, growth factors and proteases. Moreover, TAMs are often associated with poor prognosis and drug resistance, making them promising targets for CRC therapy. Given the prognostic and clinical value of TAMs, this review provides an updated overview on the origin, polarization and function of TAMs, and discusses the mechanisms by which TAMs promote the metastatic cascade of CRC. Potential TAM-targeting techniques for personalized theranostics of metastatic CRC are emphasized. Finally, future perspectives and challenges for translational applications of TAMs in CRC development and metastasis are proposed to help develop novel TAM-based strategies for CRC precision medicine and holistic healthcare.

Neutrophil-lymphocyte ratio reflects tumour-infiltrating lymphocytes and tumour-associated macrophages and independently predicts poor outcome in breast cancers with neoadjuvant chemotherapy.

AIMS: The neutrophil-lymphocyte ratio (NLR) is a systemic reflection of cancer-associated inflammation and a prognostic marker for breast cancer. For the local tumour microenvironment, tumour-infiltrating lymphocytes (TILs) and tumour-associated macrophages (TAMs) are also highly correlated with breast cancer survival. This study aimed to explore the relationship between the circulating and local immune microenvironment, and to further delineate the prognostic role of NLR in breast cancer patients receiving neoadjuvant chemotherapy (NAC). METHODS: A cohort of breast cancer patients receiving NAC with subsequent surgery was retrieved. Clinical data were reviewed. Histological slides and CD8 immunohistochemistry from biopsy (pre-chemotherapy) and excision (postchemotherapy) specimens were assessed for TILs and TAMs. RESULTS: A total of 146 patients were included. There was a significant positive correlation between pre- and postsurgery NLR at a cut-off of 2.6 (median pre-chemotherapy NLR) (P < 0.001). NLR pre-chemotherapy was associated positively with necrosis on biopsy (P = 0.027) and excision (P = 0.021) and TAMs on excision (P = 0.049). NLR 1 year postsurgery was associated with high tumour stage (P = 0.050) and low histological grade (P = 0.008). TIL count was lower in NLR-high cases at almost all time-points by histological assessment and CD8 immunostaining (P < 0.050). In multivariate analysis, postsurgery NLR is an independent predictor for overall survival [OS; hazard ratio (HR) = 9.524, P < 0.001], breast cancer-specific survival (BCSS) (HR = 10.059, P = 0.001) and disease-free survival (DFS; HR = 2.824, P = 0.016). CONCLUSIONS: The association between NLR with tumour necrosis, TAMs and TILs illustrates an interaction between the circulating and local immune microenvironment. Late NLR is a strong indicator of outcome and may be useful for prognostication and disease monitoring.

Comprehensive Proteomics Analysis Reveals Dynamic Phenotypes of Tumor-Associated Macrophages and Their Precursor Cells in Tumor Progression.

Tumor-associated macrophages (TAMs) are key regulators in tumor progression, but the precise role of bone marrow-derived monocytes (Mons) as TAM precursors and their dynamic phenotypes regulated by the tumor microenvironment (TME) remain unclear. Here, we developed an optimized microproteomics workflow to analyze low-cell-number mouse myeloid cells. We sorted TAMs and their corresponding Mons (1 × 105 per sample) from individual melanoma mouse models at both the early and late stages. We established the protein expression profiles for these cells by mass spectrometry. Subsequently, we analyzed the dynamics phenotypes of TAMs and identified a characteristic protein expression profile characterized by upregulated cholesterol metabolism and downregulated immune responses during tumor progression. Moreover, we found the downregulation of both STAT5 and PYCARD expression not only in late-stage TAMs but also in late-stage Mons, indicating a loss of the ability to induce inflammatory responses prior to Mons infiltration into TME. Taken together, our study provides valuable insights into the progression-dependent transitions between TAMs and their precursor cells, as well as the cross-organ communications of tumor and bone marrow.

Bexmarilimab Activates Human Tumor-Associated Macrophages to Support Adaptive Immune Responses in Interferon-Poor Immune Microenvironments.

Immune checkpoint inhibitors (ICI) show substantially greater efficacy in inflamed tumors characterized by preexisting T-cell infiltration and IFN signaling than in noninflamed "cold" tumors, which often remain immunotherapy resistant. The cancer immunotherapy bexmarilimab, which inhibits the scavenger receptor Clever-1 to release macrophage immunosuppression and activate adaptive immunity, has shown treatment benefit in subsets of patients with advanced solid malignancies. However, the mechanisms that determine bexmarilimab therapy outcome in individual patients are unknown. Here we characterized bexmarilimab response in ovarian cancer ascites macrophages ex vivo using single-cell RNA sequencing and demonstrated increased IFN signaling and CXCL10 secretion following bexmarilimab treatment. We further showed that bexmarilimab was most efficacious in macrophages with low baseline IFN signaling, as chronic IFNγ priming abolished bexmarilimab-induced TNFα release. These results highlight an approach to target immunologically cold tumors and to increase the likelihood of their subsequent response to ICIs.

The clinicopathological impact of tumor-associated macrophages in patients with cutaneous malignant melanoma.

BACKGROUND: Tumor-associated macrophages (TAMs) are an immune component of the cutaneous malignant melanoma (CMM) microenvironment and affect tumor growth. TAMs can polarize into different phenotypes, that is, proinflammatory M1 and anti-inflammatory M2 macrophages. However, the role of the macrophage phenotype in CMM remains unclear. METHODS: We examined 88 patients with CMM. Tissue microarrays were constructed, and the density of M1 and M2 macrophages was analyzed by immunohistochemistry. Immune cells coexpressing CD68 and phosphorylated signal transducer and activator of transcription 1 (pSTAT1) were considered M1 macrophages, whereas those coexpressing CD68 and c-macrophage activating factor (c-Maf) were defined as M2 macrophages. These TAMs were counted, and the relationships between the density of M1 and M2 macrophages and clinicopathological factors including prognosis were investigated. RESULTS: The CD68/c-Maf score ranged from 0 to 34 (median: 5.5). The patients were divided based on the median score into the CD68/c-Maf high (≥5.5) and low (<5.5) expression groups. Univariate and multivariate analyses revealed that CD68/c-Maf expression was an independent predictive factor for progression-free survival and an independent prognostic factor for overall survival. CD68/pSTAT1 expression was found in only two patients. CONCLUSION: We suggest that CD68/pSTAT1 coexpression is rarely observed in patients with CMM, and high CD68/c-Maf expression is a predictor of worse prognosis in these patients.

Tumor-associated Macrophages Mediate Gefitinib Resistance in Lung Cancer through HGF/c-met Signaling Pathway.

BACKGROUND: The biological behavior of cells changes after they develop drug resistance, and the degree of resistance will be affected by the tumor microenvironment. In this study, we aimed to study the effects of M2 macrophages on gefitinib resistance. METHODS: We polarized THP-1 cells into M0 and M2 macrophages, and conducted various experiments to investigate the effects of M2 macrophages on gefitinib resistance in lung cancer. RESULTS: We found that M2 macrophages promote gefitinib resistance in HCC827 and PC9 cells. In addition, we used ELISA to measure the secretion level of HGF. HGF secretion levels were significantly increased in M2 macrophages. Exogenous HGF remarkably increased the proliferation and invasion in HCC827 and PC9 cells. However, the addition of anti-HGF antibodies abolished the proliferation and invasion of both HCC827 and PC9 cells promoted by M2 macrophages. Furthermore, M2 macrophages or exogenous HGF significantly increased the expression of p-met and p-ERK in HCC827 and PC9 cells, while anti-HGF antibodies diminished the expression of p-met and p-ERK by neutralizing HGF in M2 macrophages. CONCLUSION: Our results revealed that M2 macrophages promote gefitinib resistance by activating ERK and HGF/c-met signaling pathways in HCC827 and PC9 cells. Our findings provide a new therapeutic strategy for gefitinib resistance in lung cancer.

CTHRC1 promotes colorectal cancer progression by recruiting tumor-associated macrophages via up-regulation of CCL15.

Tumor-associated macrophages (TAMs) represent a key factor in the tumor immune microenvironment (TME), exerting significant influence over tumor migration, invasion, immunosuppressive features, and drug resistance. Collagen triple helix repeat containing 1 (CTHRC1), a 30 KDa protein which was secreted during the tissue-repair process, is highly expressed in several malignant tumors, including colorectal cancer (CRC). Previous studies demonstrated that CTHRC1 expression in TAMs was positively correlated to M2 macrophage polarization and liver metastasis, while our discovery suggesting a novel mechanism that CTHRC1 secreted from cancer cell could indirectly interplay with TAMs. In this study, the high expression level of CTHRC1 was evaluated in CRC based on GEO and TCGA databases. Further, CTHRC1 was detected high in all stages of CRC patients by ELISA and was correlated to poor prognosis. Multispectral imaging of IHC demonstrated that M2 macrophage infiltration was increased accompanied with CTHRC1 enrichment, suggesting that CTHRC1 may have chemotactic effect on macrophages. In vitro, CTHRC1 could have chemotactic ability of macrophage in the presence of HT-29 cell line. Cytokine microarray revealed that CTHRC1 could up-regulate the CCL15 level of HT-29, pathway analysis demonstrated that CTHRC1 could regulate CCL15 by controlling the TGFß activation and Smad phosphorylation level. In vivo, knocking down of CTHRC1 from CT-26 also inhibits tumor formation. In conclusion, CTHRC1 could promote the chemotactic ability of macrophages by up-regulating CCL15 via TGFß/Smad pathway; additionally, a high level of CTHRC1 could promote macrophage's M2 polarization. This discovery may be related to tumor immune tolerance and tumor immunotherapy resistance in CRC. KEY MESSAGES: CTHRC1 promotes CRC progression by up-regulating CCL15 via TGF-ß/Smad pathways to further recruit tumor-associated macrophages. By the means of autocrine or paracrine, CTHRC1 can indeed promote macrophage chemotaxis and enhance the infiltration of macrophages in tumor tissues but in the presence of tumor cells. CAFs were another source of CTHRC1, indicating CTHRC1 can infiltrate tumor islet as well as the stomal and be secreted from both tumor cells and CAFs. This study validated CTHRC1 as a potential immune therapy target CRC.

SILAC proteomics based on 3D cell spheroids unveils the role of RAC2 in regulating the crosstalk between triple-negative breast cancer cells and tumor-associated macrophages.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, and is characterized by a high infiltration of tumor-associated macrophages (TAMs). TAMs contribute significantly to tumor progression by intricately interacting with tumor cells. Deeply investigating the interaction between TNBC cells and TAMs is of great importance for finding potential biomarkers and developing novel therapeutic strategies to further improve the clinical outcomes of TNBC patients. In this study, we confirmed the interplay using both 3D and 2D co-culture models. The stable-isotype labeling by amino acids in cell culture (SILAC)-based quantitative proteomics was conducted on 3D cell spheroids containing TNBC cells and macrophages to identify the potential candidate in regulating the crosstalk between TNBC and TAMs. Ras-related C3 botulinum toxin substrate 2 (RAC2) was identified as a potential molecule for further exploration, given its high expression in TNBC and positive correlation with M2 macrophage infiltration. The suppression of RAC2 inhibited TNBC cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro. Meanwhile, knocking down RAC2 in TNBC cells impaired macrophage recruitment and M2 polarization. Mechanistically, RAC2 exerted its roles in TNBC cells and TAMs by regulating the activation of P65 NF-κB and P38 MAPK, while TAMs further elevated RAC2 expression and P65 NF-κB activation by secreting soluble mediators including IL-10. These findings highlight the significance of RAC2 as a crucial molecule in the crosstalk between TNBC and TAMs, suggesting it could be a promising therapeutic target in TNBC.