M2-polarized Tumor-associated Macrophages Research Articles

HHLA2 deficiency inhibits pancreatic cancer progression and THP-1 macrophage M2 polarization via EGFR/MAPK/ERK and mTOR/AKT pathway

BackgroundHuman endogenous retrovirus subfamily H long terminal repeat associating protein 2, (HHLA2), a member of B7 family, exhibits heightened expression in various malignant tumors. However, the exact functions of HHLA2 in pancreatic cancer (PC) remain incompletely elucidated.MethodsWe initially conducted an analysis of the B7 family members’ expression pattern in pancreatic tumor samples and adjacent normal tissues using The Cancer Genome Atlas (TCGA) database. Subsequently, immunohistochemistry, RT-qPCR and western blot methods were used to assess HHLA2 expression levels in PC tissues and cell lines. Furthermore, after silencing HHLA2 in PC cell lines, cell migration and proliferation of PC cells were detected by wound healing and CCK-8 assays, and cell invasion of PC cells was detected by transwell assays. We also investigated the regulation of epithelial-mesenchymal transition (EMT) markers and levels of EGFR, MEK, ERK1/2, mTOR and AKT via western blot analysis. Finally, the correlation between HHLA2 expression and immune infiltration was further explored.ResultsSilencing of HHLA2 resulted in the inhibition of PC cell proliferation, migration and invasion, potentially through the suppression of the EGFR/MAPK/ERK and mTOR/AKT signaling pathway. Additionally, silencing HHLA2 led to the inhibition of M2-type polarization of tumor associated macrophages (TAMs).ConclusionThe knockdown of HHLA2 was observed to inhibit the migration and invasion of PC cells through the regulation of the EMT process and EGFR/MAPK/ERK and mTOR/AKT pathway. Furthermore, silencing HHLA2 was found to modulate M2 polarization of TAMs. These finding suggest that HHLA2 could be a promising therapeutic target for Pancreatic cancer.

PDIA3 driven STAT3/PD-1 signaling promotes M2 TAM polarization and aggravates colorectal cancer progression.

This inquiry endeavors to delineate the influence of PDIA3 on tumor-associated macrophages within the realm of colorectal malignancies, whilst elucidating the intrinsic biochemical pathways. Leveraging bioinformatics, we scrutinized the symbiosis between PDIA3, STAT3, and CD274. A xenograft model in immunodeficient murine served to assess PDIA3's impact on colorectal carcinogenesis. Further, Western blot analysis quantified the protein expression of PDIA3, p-STAT3, PD-1, XBP-1, assorted enzymes, and IL-6. Moreover, in vitro assays gauged SW480 cellular dynamics inclusive of migration, invasive potential, and proliferation. Bioinformatics exploration exposed PDIA3's elevated presence in diverse cancers, with a marked expression in colorectal cancer, as per TCGA and GEO repositories. Correlative studies showed PDIA3 positively aligning with STAT3 and CD274, the latter also associated with monocyte-derived macrophages. Comparative analysis of colorectal neoplasms and normal colon samples unveiled heightened levels of PDIA3 markers which, when overexpressed in SW480 cells, escalated tumorigenicity and oncogenic behaviors, with a noted decrease upon PD-1 monoclonal antibody intervention. PDIA3 augments the M2 polarization of tumor-associated macrophages via modulation of the STAT3/PD-1 cascade, thus invigorating the tumorous proliferation and dissemination in colorectal cancer. Such revelations position PDIA3 as an auspicious target for PD-1 blockade therapeutics, offering a promising foundation for rectifying colorectal carcinoma.

M2 Tumor-Associated Macrophages-Derived Exosomal MALAT1 Promotes Glycolysis and Gastric Cancer Progression.

M2-polarized tumor-associated macrophages (M2 TAMs) promote cancer progression. Exosomes mediate cellular communication in the tumor microenvironment (TME). However, the roles of exosomes from M2 TAMs in gastric cancer progression are unclear. Herein, it is reported that M2 TAMs-derived exosomes induced aerobic glycolysis in gastric cancer cells and enhanced their proliferation, metastasis, and chemoresistance in a glycolysis-dependent manner. It is identified that MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) is enriched in M2 TAM exosomes and confirmed that MALAT1 transfer from M2 TAMs to gastric cancer cells via exosomes mediates this effect. Mechanistically, MALAT1 interacted with the δ-catenin protein and suppressed its ubiquitination and degradation by β-TRCP. In addition, MALAT1 upregulated HIF-1α expression by acting as a sponge for miR-217-5p. The activation of β-catenin and HIF-1α signaling pathways by M2 TAM exosomes collectively led to enhanced aerobic glycolysis in gastric cancer cells. Finally, a dual-targeted inhibition of MALAT1 in both gastric cancer cells and macrophages by exosome-mediated delivery of siRNA remarkably suppressed gastric cancer growth and improved chemosensitivity in mouse tumor models. Taken together, these results suggest that M2 TAMs-derived exosomes promote gastric cancer progression via MALAT1-mediated regulation of glycolysis. The findings offer a potential target for gastric cancer therapy.

1-Ethoxycarbonyl-beta-carboline inhibits the M2 polarization of tumor-associated macrophages: A study based on network pharmacology and molecular docking analyses

AimThrough network pharmacology, molecular docking, molecular dynamics in combination with experimentation, we explored the mechanism whereby 1-ethoxycarbonyl-beta-carboline (EBC) regulates the M2 polarization of tumor-associated macrophages. MethodsNetwork pharmacology was adopted for analyzing the targets and signaling pathways related to the M2 polarization of EBC-macrophages, small molecular-protein docking was employed to analyze the possibility of EBC bonding to related protein, and molecular dynamics was introduced to analyze the binding energy between EBC and HDAC2. The M2 polarization of RAW264.7 macrophages was triggered in vitro by IL-4. After EBC intervention, the expressions of M1/M2 polarization-related cytokines were detected, and the mechanism of EBC action was explored in HDAC2-knockout RAW264.7 macrophages. A tumor-bearing mouse model was established in vitro to find the impact of EBC on tumor-associated M2 macrophages. ResultsAs revealed by the network pharmacology, molecular docking and molecular dynamics analyses, EBC was associated with 51 proteins, including HDAC2, NF-κB and HDAC4. Molecular docking and dynamics analyses suggested that HDAC2 was the main target of EBC. In vitro experiments discovered that EBC could hinder the M2 polarization of RAW264.7 macrophages, which exerted insignificant effect on the M1-associated cytokines, but could lower the levels of M2-associated cytokines. After knocking out HDAC2, EBC could not further inhibit the M2 polarization of macrophages. At the mouse level, EBC could hinder the tumor growth and the tissue levels of M2 macrophages, whose effect was associated with HDAC2. ConclusionOur study combining multiple methods finds that EBC inhibits the HDAC2-mediated M2 polarization of macrophages, thereby playing an anti-tumor role.

Abstract 6629: Cancer-associated nerves regulate anti-tumor immunity in pancreatic cancer

Abstract Nerves serve an emerging component of the tumor microenvironment (TME), contributing to tumorigenesis and cancer progression. Neural invasion (NI) is a common feature of pancreatic ductal adenocarcinoma (PDAC), accounting for distant metastasis and local recurrence. However, the mechanism by which tumor associated nerves (TANs) regulate anti-tumor immunity remains largely elusive. Here, we investigated the association between TANs and immunosuppressive TME to develop more effective therapeutic strategies for PDAC. Using tumor samples of PDAC patients, we identified that the nerves invaded by cancer cells showed increased adrenergic activation accompanied with no parasympathetic or sensory innervation changes. Patients with severe NI were associated with increased catecholamine levels. Additionally, single-cell RNA-sequencing and spatial transcriptome analysis of tumors from patients with PDAC revealed that peri-neural niches of severe NI patients were characterized by decreased CD8+ T cells and increased activity of M2 polarization of tumor-associated macrophages (TAMs), and regulatory T (Treg) cells, which was validated by multiplexed immunofluorescence staining. We further identified that CD8+ T cells expressing β-adrenaline receptors (β-ARs) reduced proliferation and cytokine production when exposure to catecholamines in a dose-dependent manner or co-cultured with dorsal root ganglia pretreated with cancer cells. KrasLSL-G12D; p53LoxP; Pdx1-CreER (KPC) mice treated with catecholamines accelerated tumor progression by inhibiting T cell-mediated antitumor responses, which was abrogated by surgical sympathectomy of KPC mice. Especially, in an orthotopic PDAC model, nonselective β-blocker propranolol in combination with immune checkpoint blockade (ICB) significantly enhanced active CD8+ T cells with concurrent reduced tumor growth. We suggest a novel regulatory mechanism of inhibiting anti-tumor immunity that can promote cancer progression mediated by TANs invasion. These data establish a close connection between the nerves, cancer cells, and immune cells and provide the potential novel targets of therapeutic approaches in PDAC. Citation Format: Ruiyuan Xu, Jianlu Song, Yuan Chen, Xinpeng Yin, Chengcheng Wang, Yupei Zhao. Cancer-associated nerves regulate anti-tumor immunity in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6629.

LncRNAs act as modulators of macrophages within the tumor microenvironment.

Long non-coding RNAs (lncRNAs) have been established as pivotal players in various cellular processes, encompassing the regulation of transcription, translation, post-translational modulation of proteins, thereby influencing cellular functions. Notably, lncRNAs exert a regulatory influence on diverse biological processes, particularly in the context of tumor development. Tumor-associated macrophages (TAMs) exhibit the M2 phenotype, exerting significant impact on crucial processes such as tumor initiation, angiogenesis, metastasis, and immune evasion. Elevated infiltration of TAMs into the tumor microenvironment (TME) is closely associated with a poor prognosis in various cancers. LncRNAs within TAMs play a direct role in regulating cellular processes. Functioning as integral components of tumor-derived exosomes, lncRNAs prompt the M2-like polarization of macrophages. Concurrently, reports indicate that lncRNAs in tumor cells contribute to the expression and release of molecules that modulate TAMs within the TME. These actions of lncRNAs induce the recruitment, infiltration, and M2 polarization of TAMs, thereby providing critical support for tumor development. In this review, we survey recent studies elucidating the impact of lncRNAs on macrophage recruitment, polarization, and function across different types of cancers.

Lentinan inhibits cell invasion via M2 polarization of tumor-associated macrophages and Wnt/β-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 β-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/β-catenin signaling in NSCLC cells. The activated Wnt/β-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/β-catenin signaling.

RUNX1 promotes angiogenesis in colorectal cancer by regulating the crosstalk between tumor cells and tumor associated macrophages

Colorectal cancer (CRC) is a common malignancy worldwide. Angiogenesis and metastasis are the critical hallmarks of malignant tumor. Runt-related transcription factor 1 (RUNX1), an efficient transcription factor, facilitates CRC proliferation, metastasis and chemotherapy resistance. We aimed to investigate the RUNX1 mediated crosstalk between tumor cells and M2 polarized tumor associated macrophages (TAMs) in CRC, as well as its relationship with neoplastic angiogenesis. We found that RUNX1 recruited macrophages and induced M2 polarized TAMs in CRC by promoting the production of chemokine 2 (CCL2) and the activation of Hedgehog pathway. In addition, we found that the M2 macrophage-specific generated cytokine, platelet-derived growth factor (PDGF)-BB, promoted vessel formation both in vitro and vivo. PDGF-BB was also found to enhance the expression of RUNX1 in CRC cell lines, and promote its migration and invasion in vitro. A positive feedback loop of RUNX1 and PDGF-BB was thus formed. In conclusion, our data suggest that RUNX1 promotes CRC angiogenesis by regulating M2 macrophages during the complex crosstalk between tumor cells and TAMs. This observation provides a potential combined therapy strategy targeting RUNX1 and TAMs-related PDGF-BB in CRC.

Calcitriol promotes M2 polarization of tumor-associated macrophages in 4T1 mouse mammary gland cancer via the induction of proinflammatory cytokines

Our research found that vitamin D3 (VD3) treatment increased lung metastasis in mice with 4T1 murine breast cancer (BC). This study aims to investigate the impact of VD3 on the activation of tumor-associated macrophages (TAMs) in BC. Mice bearing 4T1, E0771, 67NR BC cells, and healthy mice, were fed diets with varying VD3 contents (100—deficient, 1000—normal, and 5000 IU/kg—elevated). Some mice in the 1000 and 100 IU/kg groups received calcitriol. We studied bone metastasis and characterized TAMs and bone marrow-derived macrophages (BMDMs). 4T1 cells had higher bone metastasis potential in the 5000 IU/kg and calcitriol groups. In the same mice, an elevated tumor osteopontin level and M2 polarization of TAMs (MHCIIlow CD44high phenotype) were observed. Gene expression analysis confirmed M2 polarization of 4T1 (but not 67NR) TAMs and BMDMs, particularly in the 100 IU + cal group (increased Mrc1, Il23, and Il6). This polarization was likely due to COX-2/PGE2 induction in 4T1 calcitriol-treated cells, leading to increased proinflammatory cytokines like IL-6 and IL-23. Future studies will explore COX-2/PGE2 as a primary mediator of calcitriol-stimulated inflammation in the BC microenvironment, especially relevant for BC patients with VD3 deficiency and supplementation.

NAMPT-Driven M2 Polarization of Tumor-Associated Macrophages Leads to an Immunosuppressive Microenvironment in Colorectal Cancer.

Nicotinamide phosphoribosyltransferase (NAMPT) is a metabolic enzyme with key roles in inflammation. Previous studies have examined the consequences of its upregulated expression in cancer cells themselves, but studies are limited with respect to its role in the other cells within the tumor microenvironment (TME) during colorectal cancer (CRC) progression. Using single-cell RNA sequencing (scRNA-seq) data, it is founded that NAMPT is highly expressed in SPP1+ tumor-associated macrophages (TAMs), a unique subset of TAMs associated with immunosuppressive activity. A NAMPThigh gene signature in SPP1+ TAMs correlated with worse prognostic outcomes in CRC patients. The effect of Nampt deletion in the myeloid compartment of mice during CRC development is explored. NAMPT deficiency in macrophages resulted in HIF-1α destabilization, leading to reduction in M2-like TAM polarization. NAMPT deficiency caused significant decreases in the efferocytosis activity of macrophages, which enhanced STING signaling and the induction of type I IFN-response genes. Expression of these genes contributed to anti-tumoral immunity via potentiation of cytotoxic T cell activity in the TME. Overall, these findings suggest that NAMPT-initiated TAM-specific genes can be useful in predicting poor CRC patient outcomes; strategies aimed at targeting NAMPT may provide a promising therapeutic approach for building an immunostimulatory TME in CRC progression.

The immune regulatory function of B7-H3 in malignancy: spotlight on the IFN-STAT1 axis and regulation of tumor-associated macrophages.

B7-H3 is a member of the B7 superfamily and a putative inhibitory immune checkpoint molecule. Several early-phase clinical trials have reported promising anti-tumor activity and safety of anti-cancer drugs targeting B7-H3, suggesting that it may be a promising target for a potential next-generation immune checkpoint inhibitor. Despite ongoing clinical studies, most B7-H3-targeted drugs being currently investigated rely on direct cytotoxicity as their mechanisms of action rather than modulating its function as an immune checkpoint, at least in part due to its incompletely understood immune regulatory function. Recent studies have begun to elucidate the role of B7-H3 in regulating the tumor microenvironment (TME). Emerging evidence suggests that B7-H3 may regulate the interferon-STAT1 axis in the TME and promote immune suppression. Similarly, increasing evidence shows B7-H3 may be implicated in promoting M1 to M2 polarization of tumor-associated macrophages (TAMs). There is also accumulating evidence suggesting that B7-H3 may play a role in the heterotypic fusion of cancer stem cells and macrophages, thereby promoting tumor invasion and metastasis. Here, we review the recent advances in the understanding of B7-H3 cancer immunobiology with a focus on highlighting its potential role in the interferon priming of TAMs and the heterotypic fusion of TAMs with cancer stem cells and suggest future direction in elucidating its immune checkpoint function.

Ganodermanontriol regulates tumor-associated M2 macrophage polarization in gastric cancer.

We focused on investigating the role and mechanism of ganodermanontriol (GAN) in regulating the M2 polarization of tumor-associated macrophages in the gastric cancer microenvironment. M2 polarization of RAW264.7 macrophages was induced by IL-4 or co-culture with MFC, and the expression levels of M1 macrophage markers (TNF-α, IFN-γ, IL-1β) and M2 macrophage markers (IL-10, TGF-β, Arg-1) were detected by enzyme-linked immunosorbed assay (ELISA). The protein expression was assayed by Western-Blotting. For in vitro experiments, a tumor-bearing mouse model was established, with which the CD206 level was detected by histochemistry, and the binding mode between GAN and STAT6 was simulated through molecular dynamics. Both IL-4 and MFC could induce the M2 polarization of macrophages. GAN could inhibit such polarization, which produced unobvious effects on M1 markers, but could suppress the levels of M2 markers. GAN could inhibit the phosphorylated expression of STAT6, and M2 macrophages treated by it had a weakened ability to promote malignant behavior of MFC. According to the results of in vitro experiments, GAN could inhibit tumor growth, suppress the tissue infiltration of CD206 cells, and inhibit the phosphorylated expression of STAT6. Our results show that GAN can inhibit the M2 macrophage polarization in gastric cancer microenvironment, whose mechanism of action is associated with the regulation of STAT6 phosphorylation.

Characterizing ligand-receptor interactions and unveiling the pro-tumorigenic role of CCL16-CCR1 axis in the microenvironment of hepatocellular carcinoma.

The heterogeneity of the tumor microenvironment significantly influences the prognosis of hepatocellular carcinoma (HCC) patients, with cell communication through ligand-receptor complexes playing a central role. We conducted single-cell transcriptomic analysis on ten HCC tissues to identify ligand-receptor genes involved in malignant HCC cell communication using CellChat. Leveraging RNA-Seq data from the TCGA Liver Cancer (TCGA-LIHC) and Liver Cancer - RIKEN, JP (LIRI-JP) cohorts, we employed Cox regression analysis to screen for prognosis-related genes. Prognostic risk models were constructed through unsupervised clustering and differential gene expression analysis. Subsequently, a co-culture system involving tumor cells and macrophages was established. A series of experiments, including Transwell assays, immunofluorescence staining, immunoprecipitation, flow cytometry, and immunohistochemistry, were conducted to elucidate the mechanism through which HCC cells recruit macrophages via the CCL16-CCR1 axis. Single-cell analysis unveiled significant interactions between malignant HCC cells and macrophages, identifying 76 related ligand-receptor genes. Patients were classified into three subtypes based on the expression patterns of eight prognosis-related ligand-receptor genes. The subtype with the worst prognosis exhibited reduced infiltration of T cell-related immune cells, downregulation of immune checkpoint genes, and increased M2-like tumor-associated macrophage scores. In vitro experiments confirmed the pivotal role of the CCL16-CCR1 axis in the recruitment and M2 polarization of tumor-associated macrophages. Clinical samples demonstrated a significant association between CCL16 protein expression levels and advanced stage, lymph node metastasis, and distant metastasis. Immunohistochemistry and immunofluorescence staining further confirmed the correlation between CCL16 and CCR1, CD68, and CD206, as well as CD68+CCR1+ macrophage infiltration. Our study identified molecular subtypes, a prognostic model, and immune microenvironment features based on ligand-receptor interactions in malignant HCC cell communication. Moreover, we revealed the pro-tumorigenic role of HCC cells in recruiting M2-like tumor-associated macrophages through the CCL16-CCR1 axis.

LncRNA-HOXC-AS2 regulates tumor-associated macrophage polarization through the STAT1/SOCS1 and STAT1/CIITA pathways to promote the progression of non-small cell lung cancer

Tumor-associated macrophages (TAMs) mainly exhibit the characteristics of M2-type macrophages, and the regulation of TAM polarization is a new target for cancer therapy, among which lncRNAs are key regulatory molecules. This study aimed to explore the effects of lncRNA-HOXC-AS2 on non-small cell lung cancer (NSCLC) by regulating TAM polarization. THP-1 cells were used to differentiate into macrophages, and TAMs were obtained by coculture with A549 cells. The M1/M2 cell phenotype and HOXC-AS2 expression were detected, and A549-derived exosomes (A549-exo) were used to elucidate the effects of A549 on macrophage polarization and HOXC-AS2 expression. Then, by interfering with HOXC-AS2 or STAT1, the effects of HOXC-AS2 regulation of STAT1 on the TAM phenotype and STAT1/SOCS1 and STAT1/CIITA pathways were analyzed, and the proliferation and metastasis of NSCLC cells in the coculture system were also detected. Results showed that HOXC-AS2 expression in M2 macrophages and TAMs was significantly higher than that in M1 macrophages, and A549-exo promoted HOXC-AS2 expression and M2 polarization. Intervention HOXC-AS2 resulted in increased M1 marker expression, decreased M2 marker expression, and activation of STAT1/SOCS1 and STAT1/CIITA pathways in TAMs. In addition, HOXC-AS2 was mainly expressed in the cytoplasm of TAMs and could bind to STAT1. Further experiments confirmed that intervention HOXC-AS2 promoted the M1 polarization of TAMs by targeting STAT1 and weakened the promoting effects of TAMs on the proliferation and metastasis of NSCLC. In conclusion, HOXC-AS2 inhibited the activation of STAT1/SOCS1 and STAT1/CIITA pathways and promoted M2 polarization of TAMs by binding with STAT1, thus promoting NSCLC.

Gab2 promotes the growth of colorectal cancer by regulating the M2 polarization of tumor‑associated macrophages.

Tumor‑associated macrophages (TAMs) are pivotal components in colorectal cancer (CRC) progression, markedly influencing the tumor microenvironment through their polarization into the pro‑inflammatory M1 or pro‑tumorigenic M2 phenotypes. Recent studies have highlighted that the Grb2‑associated binder 2 (Gab2) is a critical gene involved in the development of various types of tumor, including CRC. However, the precise role of Gab2 in mediating TAM polarization remains incompletely elucidated. In the present study, it was discovered that Gab2 was highly expressed within CRC tissue TAMs, and was associated with a poor prognosis of patients with CRC. Functionally, it was identified that the tumor‑conditioned medium (TCM) induced Gab2 expression, facilitating the TAMs towards an M2‑like phenotype polarization. Of note, the suppression of Gab2 expression using shRNA markedly inhibited the TCM‑induced expression of M2‑associated molecules, without affecting M1‑type markers. Furthermore, the xenotransplantation model demonstrated that Gab2 deficiency in TAMs inhibited tumor growth in the mouse model of CRC. Mechanistically, Gab2 induced the M2 polarization of TAMs by regulatingthe AKT and ERK signaling pathways, promoting CRC growth and metastasis. In summary, the present study study elucidates that decreasing Gab2 expression hinders the transition of TAMs towards the M2 phenotype, thereby suppressing the growth of CRC. The exploration of the regulatory mechanisms of Gab2 in TAM polarization may enhance the current understanding of the core molecular pathways of CRC development and may thus provide a foundation for the development of novel immunotherapeutic strategies targeted against TAMs.

TMEM147 aggravates the progression of HCC by modulating cholesterol homeostasis, suppressing ferroptosis, and promoting the M2 polarization of tumor-associated macrophages

BackgroundThe endoplasmic reticulum (ER) regulates critical processes, including lipid synthesis, which are affected by transmembrane proteins localized in the ER membrane. One such protein, transmembrane protein 147 (TMEM147), has recently been implicated for its role in hepatocellular carcinoma (HCC) tumorigenesis; however, the mechanisms remain unclear. We investigated the role of TMEM147 in HCC and the underlying mechanisms.MethodsTMEM147 expression was examined in human HCC cells and adjacent non-tumorous tissues using quantitative reverse transcription-polymerase chain reaction, western blotting, and immunohistochemistry. In vitro and in vivo studies were conducted to investigate the impact of TMEM147 on the progression of HCC. Proteins interacting with TMEM147 were identified via RNA-seq, immunoprecipitation, and mass spectrometry analyses. Lipidomic analysis and enzyme-linked immunosorbent assay (ELISA) were employed to determine and analyze cholesterol and 27-hydroxycholesterol (27HC) contents. Extensive experimental techniques were used to study ferroptosis in HCC cells. The fatty acid content of macrophages affected by TMEM147 was quantified using ELISA. Macrophage phenotypes were determined using immunofluorescence assay and flow cytometric analysis.ResultsTMEM147 mRNA and protein levels were increased in HCC cells, and the increased TMEM147 expression was associated with a poor survival. TMEM147 promoted tumor cell proliferation and metastases in vitro and in vivo. The protein was found to interact with the key enzyme 7-dehydrocholesterol reductase (DHCR7), which affected cellular cholesterol homeostasis and increased the extracellular levels of 27HC in HCC cells. TMEM147 also promoted the expression of DHCR7 by enhancing the activity of signal transducer and activator of transcription 2. 27HC expression upregulated glutathione peroxidase 4 in HCC, leading to ferroptosis resistance and promotion of HCC proliferation. HCC cell-derived 27HC expression increased the lipid metabolism in macrophages and activated peroxisome proliferator-activated receptor-γ signaling, thereby activating M2 macrophage polarization and promoting HCC cell invasion and migration.ConclusionsOur results indicate that TMEM147 confers ferroptosis resistance and M2 macrophage polarization, which are primarily dependent on the upregulation of cellular cholesterol homeostasis and 27HC secretion, leading to cancer growth and metastasis. These findings suggest that the TMEM147/STAT2/DHCR7/27HC axis in the tumor microenvironment may serve as a promising therapeutic target for HCC.Graphical

Prognostic and immunological role of acetaldehyde dehydrogenase 1B1 in human tumors: A pan-cancer analysis.

Acetaldehyde dehydrogenases (ALDH) 1B1 is associated with a poor prognosis in pancreatic cancer, colorectal cancer, and osteosarcoma. Overexpression of ALDH also impairs tumor immunity. However, it is unclear how ALDH1B1 is associated with patient prognosis and immune infiltration in different cancer types. This is an original research based on bioinformatics analysis. In this study, we investigated the expression and prognostic value of ALDH1B1 in pan-cancer specimens using several databases, including GEPIA2 and Kaplan-Meier Plotter. The GEPIA2 and TIMER2 databases were used to explore correlations between ALDH1B1 expression and immune infiltration in cancers, especially head and neck squamous cell carcinoma (HNSC) and stomach adenocarcinoma (STAD). Finally, the expression of ALDH1B1 was validated by qPCR and immunohistochemistry. The expression of ALDH1B1 differed in most cancers compared to normal tissue controls. ALDH1B1 has an important impact on the prognosis different cancer types, and the high expression of ALDH1B1 is inversely associated with survival in patients with HNSC. A significant positive correlation was identified between ALDH1B1 expression in HNSC and immune infiltration. The poor prognosis associated with high expression of ALDH1B1 may be related to the promotion of M2 polarization of tumor-associated macrophages. Furthermore, markers of immune cell infiltration, such as exhausted T cells and regulatory T cells showed different patterns of ALDH1B1-associated immune infiltration. ALDH1B1 can serve as a prognostic biomarker in pan-cancer types and is correlated with immune infiltration.

C5aR1 blockade reshapes immunosuppressive tumor microenvironment and synergizes with immune checkpoint blockade therapy in high-grade serous ovarian cancer

ABSTRACT High-grade serous ovarian cancer (HGSC), with a modest response to immune checkpoint blockade (ICB) targeting PD-1/PD-L1 monotherapy, is densely infiltrated by M2-polarized tumor-associated macrophages (TAMs) and regulatory T (Treg) cells. The complement C5a/C5aR1 axis contributes to the programming of the immunosuppressive phenotype of TAMs in solid tumors and represents a promising immunomodulatory target for treating HGSCs. Here, we aimed to identify the relevance of C5aR1 in prognosis, immune microenvironment, and immunotherapy response in HGSCs. The expression and relationship of C5aR1 with tumor-infiltrating immune cells were assessed by immunohistochemistry and flow cytometry in the training cohort (n = 120) and fresh HGSC tissues (n = 36). Transcriptomic analyses of the xenografts delineated the mechanisms driving the immunomodulatory activity of PMX53, an orally bioavailable C5aR1 inhibitor. Therapeutic relevance was confirmed in ex vivo tumor cultures and The Cancer Genome Atlas (TCGA) datasets. C5aR1 expression independently predicted dismal prognosis and was linked to the immunoevasive subtype of HGSC, characterized by increased infiltration of pro-tumor cells (Treg cells, M2-polarized macrophages, and neutrophils) and impaired CD8+T functions. PMX53 antagonized subcutaneous tumor growth, modulated immunosuppressive mechanisms and synergized with aPD-1 in several tumor types. Single-cell RNA-seq analysis revealed predominant C5aR1 expression in TAMs, with an immunosuppressive-related expression signature in C5aR1+TAMs. Furthermore, the combination of C5aR1 and PD-L1 was associated with specific molecular characteristics and matched clinical response annotations. Therefore, the abundance of C5aR1 could predict an inferior prognosis in HGSCs, and incorporating PD-L1 may serve as a novel predictive biomarker to guide therapeutic options.

High-Dose Acetaminophen with N-acetylcysteine Rescue Inhibits M2 Polarization of Tumor-Associated Macrophages.

High-dose acetaminophen (AAP) with N-acetylcysteine (NAC) rescue is among the few treatments that has shown activity in phase I trials without achieving dose-limiting toxicity that has not progressed to evaluation in later line studies. While the anti-tumor effects of AAP/NAC appear not to be mediated by glutathione depletion and free radical injury, the mechanism of anti-tumor effects of AAP/NAC has not been definitively characterized. In vitro, the effects of AAP/NAC were evaluated on bone marrow derived macrophages. Effects of AAP on IL-4/STAT6 (M2) or IFN/LPS/STAT1 (M1) signaling and downstream gene and protein expression were studied. NAC reversed the AAP toxicity in the normal liver but did not reverse AAP cytotoxicity against tumor cells in vitro. AAP/NAC selectively inhibited IL-4-induced STAT6 phosphorylation but not IFN/LPS-induced STAT1 phosphorylation. Downstream, AAP/NAC inhibited IL-4 induction of M2-associated genes and proteins but did not inhibit the IFN/LPS induction of M1-associated genes and proteins. In vivo, AAP/NAC inhibited tumor growth in EF43.fgf4 and 4T1 triple-negative breast tumors. Flow cytometry of tumor-associated macrophages revealed that AAP/NAC selectively inhibited M2 polarization. The anti-tumor activity of high-dose AAP/NAC is lost in macrophage-depleted mouse syngeneic tumor models, suggesting a macrophage-dependent mechanism of action. In conclusion, our study is the first to show that high-dose AAP/NAC has profound effects on the tumor immune microenvironment that facilitates immune-mediated inhibition of tumor growth.

Epinephrine promotes tumor progression and M2 polarization of tumor-associated macrophages by regulating the TRIM2- NF-κB pathway in colorectal cancer cells

Epinephrine promotes tumor progression and M2 polarization of tumor-associated macrophages by regulating the TRIM2- NF-κB pathway in colorectal cancer cells