Tumor-associated Macrophages In Lung Cancer Research Articles

Cutting edges and therapeutic opportunities on tumor-associated macrophages in lung cancer.

Lung cancer is a disease with remarkable heterogeneity. A deep understanding of the tumor microenvironment (TME) offers potential therapeutic strategies against this malignant disease. More and more attention has been paid to the roles of macrophages in the TME. This article briefly summarizes the origin of macrophages, the mutual regulation between anti-tumoral immunity and pro-tumoral statuses derived from macrophage polarization, and the therapeutic opportunities targeting alternately activated macrophages (AAM)-type macrophage polarization. Among them, cellular components including T cells, as well as acellular components represented by IL-4 and IL-13 are key regulators driving the polarization of AAM macrophages. Novel treatments targeting macrophage-associated mechanisms are mainly divided into small molecule inhibitors, monoclonal antibodies, and other therapies to re-acclimate AMM macrophages. Finally, we paid special attention to an immunosuppressive subgroup of macrophages with T cell immunoglobulin and mucin domain-3 (TIM-3) expression. Based on cellular interactions with cancer cells, TIM3+ macrophages facilitate the proliferation and progression of cancer cells, yet this process exposes targets blocking the ligand-receptor recognition. To sum up, this is a systematic review on the mechanism of tumor-associated macrophages (TAM) polarization, therapeutic strategies and the biological functions of Tim-3 positive macrophages that aims to provide new insights into the pathogenesis and treatment of lung cancer.

Advances in the Study of Tumor-associated Macrophages in Lung Cancer

肺癌是全球发病率和死亡率最高的恶性肿瘤之一。因此对于肺癌治疗手段的研究也在不断深入，目前临床上主要有全身化疗、针对驱动基因阳性的靶向治疗、免疫检查点抑制剂的应用、抗肿瘤血管生成治疗以及上述不同治疗方法的联合等，这些方案的使用明显改善了大多数肺癌患者的预后，但晚期患者预后仍然不尽如人意。近年来，与免疫相关的肿瘤微环境（tumor microenvironment, TME）的研究越来越受到重视。TME由免疫细胞、成纤维细胞、血管内皮细胞等细胞成分及相关的细胞因子等组成，是肿瘤细胞赖以生存、发展的基础。而肿瘤相关巨噬细胞（tumor-associated macrophages, TAMs）是TME重要的免疫细胞，指浸润于肿瘤组织中的巨噬细胞，可促进肿瘤细胞增殖，诱导肿瘤免疫耐受，刺激肿瘤血管生成，增加肿瘤细胞的侵袭及转移能力。因此，靶向TAMs已经成为肺癌免疫治疗的热点。本文就TAMs来源、表型及其在肺癌中的作用机制以及在未来治疗中的靶点进行综述，为肺癌最优化治疗提供参考。

A narrative review of tumor-associated macrophages in lung cancer: regulation of macrophage polarization and therapeutic implications.

Lung cancer is the deadliest malignancy worldwide. An inflammatory microenvironment is a key factor contributing to lung tumor progression. Tumor-Associated Macrophages (TAMs) are prominent components of the cancer immune microenvironment with diverse supportive and inhibitory effects on growth, progression, and metastasis of lung tumors. Two main macrophage phenotypes with different functions have been identified. They include inflammatory or classically activated (M1) and anti-inflammatory or alternatively activated (M2) macrophages. The contrasting functions of TAMs in relation to lung neoplasm progression stem from the presence of TAMs with varying tumor-promoting or anti-tumor activities. This wide spectrum of functions is governed by a network of cytokines and chemokines, cell-cell interactions, and signaling pathways. TAMs are promising therapeutic targets for non-small cell lung cancer (NSCLC) treatment. There are several strategies for TAM targeting and utilizing them for therapeutic purposes including limiting monocyte recruitment and localization through various pathways such as CCL2-CCR2, CSF1-CSF1R, and CXCL12-CXCR4, targeting the activation of TAMs, genetic and epigenetic reprogramming of TAMs to antitumor phenotype, and utilizing TAMs as the carrier for anti-cancer drugs. In this review, we will outline the role of macrophages in the lung cancer initiation and progression, pathways regulating their function in lung cancer microenvironment as well as the role of these immune cells in the development of future therapeutic strategies.

Targeting folate receptor \u03b2 positive tumor-associated macrophages in lung cancer with a folate-modified liposomal complex

Tumor-associated macrophages (TAMs) facilitate cancer progression by promoting tumor invasion, angiogenesis, metastasis, inflammatory responses, and immunosuppression. Folate receptor β (FRβ) is overexpressed in TAMs. However, the clinical significance of FRβ-positive macrophages in lung cancer remains poorly understood. In this study, we verified that FRβ overexpression in lung cancer TAMs was associated with poor prognosis. We utilized a folate-modified lipoplex comprising a folate-modified liposome (F-PLP) delivering a BIM-S plasmid to target both lung cancer cells and FRβ-positive macrophages in the tumor microenvironment. Transfection of LL/2 cells and MH-S cells with F-PLP/pBIM induced cell apoptosis. Injection of F-PLP/pBIM into LL/2 and A549 lung cancer models significantly depleted FRβ-positive macrophages and reduced tumor growth. Treatment of tumor-bearing mice with F-PLP/pBIM significantly inhibited tumor growth in vivo by inducing tumor cell and macrophage apoptosis, reducing tumor proliferation, and inhibiting tumor angiogenesis. In addition, a preliminary safety evaluation demonstrated a good safety profile of F-PLP/pBIM as a gene therapy administered intravenously. This work describes a novel application of lipoplexes in lung cancer targeted therapy that influences the tumor microenvironment by targeting TAMs.

USP7 targeting modulates anti-tumor immune response by reprogramming Tumor-associated Macrophages in Lung Cancer.

Background: Tumor associated macrophages (TAMs) have strong plasticity and if reprogrammed, can clear tumor cells and regulate the adaptive immune system for cancer immunotherapy. Deubiquitinating enzymes (DUBs), which can remove ubiquitin (Ub) from Ub-modified substrates, have been associated with oncogenic metabolism but are not well-known for regulating TAMs repolarization.Methods: The expression of DUB related genes in macrophages (MΦs) was detected by reverse transcription-PCR. Flow cytometry and immunofluorescence were used to detect the changes of immune cells in the tumor microenvironment and spleen, including M1 (CD11b+F4/80+CD86+CD206-), and M2 (CD11b+F4/80+CD86-CD206+) MΦs, and IFN-γ+CD8+T cells. A proliferation assay was used to determine the effect of M2 MΦs treated with a USP7 inhibitor on T cell proliferation. Western blotting was used to detect the expression of USP7 and the activation of the MAPK pathway. The TGCA database was used to assess the role of USP7 in the immune microenvironment of human lung adenocarcinoma (LUAD).Results: 51 DUB genes were screened and USP7 was identified as a highly expressed gene in M2 but not M1 MΦs. Specific silencing of USP7 using siRNA or USP7 inhibitors led to phenotypical and functional changes in M2 MΦs, favoring CD8+T cells proliferation in vitro. USP7 inhibitors delayed tumor growth in mice with Lewis lung carcinoma, and promoted tumor infiltration of M1 MΦs and IFN-γ+CD8+T cells. Depletion of TAMs attenuated these therapeutic effects. USP7 inhibition was shown to mediate MΦs reprogramming by activating the p38 MAPK pathway. Administration of USP7 inhibitors increased the expression of programmed cell death ligand 1 (PD-L1) in tumors, while blocking programmed cell death protein 1 (PD-1) provided an effective anti-tumor response. Clinical databases suggest that high expression of USP7 in LUAD was negatively correlated with innate and adaptive immunity.Conclusions: Taken together, these results provide evidence to suggest that therapeutic approaches targeting USP7, in combination with immunotherapy, should be considered for lung cancer treatment.

Abstract 4157: IL-6 glycoforms differentially modulate the polarization of tumor-associated macrophages in lung cancer

Abstract Interleukin-6 (IL-6) is critical in modulating both tumor growth and anti-tumor immunity. Here, we describe the glycosylation pattern of lung cancer cell-secreted IL-6 and examine the function of the IL-6 glycoforms in polarization of tumor-associated macrophages (TAMs). IL-6 with different molecular weights were detected in various lung cancer cells. Because in NetNGlyc 1.0 Server, one possible N-glycosylation site has been predicted at N73 on IL-6, we used tunicamycin treatment and site-directed mutagenesis on N73 to demonstrate that lung cancer cell-secreted IL-6 is modified by N-glycosylation. To explore more detailed attached glycans, we measured the expression of glycosyltransferases by qPCR and found that the expression of fucosyltransferase 8 (FUT8), responsible for core fucosylation on N-glycosylated proteins, was higher in lung cancer cells than normal bronchial cells. Core fucosylation on IL-6 was reduced by silencing FUT8. We generated AS2-IL6, AS2-IL6-shFUT8, and AS2-IL6-N73Q cells for producing full-glycosylated IL-6 (G-IL6), core fucose-depleted IL-6 (DeCF-IL6), and Asn73-N-glycan-depleted IL-6 (N73Q-IL6). To examine the effect of the IL-6 glycoforms on differentiation of TAMs, THP-1 monocytic leukemic cells were incubated with phorbol-12-myristate 13-acetate for transforming to macrophages, followed by co-culture with the AS2 cell derivatives to mimic the education of TAMs. The co-cultured TAMs of each AS2 derivative showed distinct morphology. Intriguingly, the G-IL6-producing cells promote the expression of M2-TAM markers CD204, CCR1, arginase-1, and M2-specific cytokines that benefit anti-tumor activity, while DeCF-IL6 and N73Q-IL6 favored the formation of M1 macrophages. The phagocytosis capacity of cocultured macrophages is also altered by different IL-6 glycoform-secreting cells. On the other hand, the Stat3 activation status induced by IL-6 glycoforms is concordant to our previous results, in which the G-IL6 can induce a persistant Stat3 activation that is not observed in the DeCF-IL6- and N73Q-IL6-induced macrophages. We subsequently examined the distribution and polarization of TAMs in in vivo xenograft tumor model by both subcutaneous and intravenous injection of the IL-6 glycoform-overexpressing cells. Higher proportion of M2 TAM was attracted by the N73Q-IL6 tumor than other glycoform tumors. Together, we report the presence of specific IL-6 glycoforms secreted from lung cancer cells. Moreover, the glycosylation on IL-6 changes its activity on the polarization of TAMs, suggesting the pivotal role of soluble factor(s) in orchestrating the tumor microenvironment of lung cancer. Citation Format: Chun-Hua Hung, Hao-Chen Wang, Hsuan-Heng Yeh, Chien-Chung Lin, Wu-Chou Su. IL-6 glycoforms differentially modulate the polarization of tumor-associated macrophages in lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4157.

TREM-1low is a novel characteristic for tumor-associated macrophages in lung cancer.

ObjectiveTo explore the expression feature and biological functions of TREM-1 on tumor-associated macrophages (TAMs) in lung cancer.ResultsThe levels of TREM-1 on tissue-infiltrating monocytes/macrophage from tumor nest were significantly lower than those from nonturmor tissue or peripheral blood samples. Clinical analysis indicated that the levels of TREM-1-related TAMs were significantly decreased during cancer stages progression. The tumor-bearing mouse model further confirmed that the expression of TREM-1 on TAMs was significantly decreased with tumor growth. In addition, we found the activation of TREM-1 could significantly enhance the secretion of IL-1β by TAM in vitro. Furthermore, T-bet but not Eomes was found to be the key transcription factor for the TREM-1 expression on monocytes/macrophage.MethodsA total of 40 patients with non-small cell lung cancer (NSCLC) were enrolled in this study. The expression characteristics of TREM-1 in blood and tissue-infiltrating monocytes/macrophage were examined by flow cytometry analysis. After the treatment of TREM-1 antibody, which is an agonist of TREM-1, cytokines secreted by TAM were then analyzed. In LLC-tumor bearing mouse model, we further investigated the dynamic expression feature of TREM-1 on macrophage with tumor growth. Moreover, we explored the transcription factor for regulating TREM-1 expression on monocyes/macrophage with wildtype, T-bet Ko or Eomes Ko mice.ConclusionThe levels of TREM-1 were remarkably decreased during tumor progression. The low expression level of TREM-1 might be a characteristic for TAMs in lung cancer.

Inverse role of distinct subsets and distribution of macrophage in lung cancer prognosis: a meta-analysis.

BackgroundTumor-associated macrophages (TAMs) play a crucial role in the regulation of local inflammatory and immune response of tumor microenvironment, being associated with worse outcome of several solid tumors. But the prognostic value of tumor-infiltrating TAMs in lung cancer is still controversial.MethodsWe conduct a meta-analysis of 3055 patients in 21 studies searched from PubMed and Medline to investigate the correlation between tumor-infiltrating TAMs, including distinct TAM subsets and tissue distribution, and survival of lung cancer. Survival data were computed into odds ratios (ORs) and pooled using Mantel–Haenszel random-effect model. All statistical tests were two-sided.ResultsHigh density of tumor-infiltrating TAMs was significantly associated with worse overall survival (OS) at 3 years (OR = 2.45, 95% CI = 1.25 to 4.80, P = 0.009) and 5 years (OR = 2.04, 95% CI = 1.03 to 4.01, P = 0.04) of lung cancer. Results for disease free survival (DFS) were similar. M2 subset was associated with worse 3 year-OS and 5 year-OS, whereas M1 subset was associated with better 3-year OS and 5-year OS. Elevated TAM density in tumor stroma was associated with worse OS at 3 years and 5 years, while elevated TAMs in tumor islet/tumor stroma were associated with better OS at 3 years and 5 years.ConclusionsIncreased tumor-infiltrating TAMs are associated with poor prognosis of lung cancer. M2 subset and TAMs in tumor stroma were associated with worse survival, while M1 subset and TAMs in tumor islet were associated with favorable survival of lung cancer.

Clinical significance of PD-L1 protein expression on tumor-associated macrophages in lung cancer

Tumor PD-L1 expression is associated with increased tumor-infiltrating lymphocytes (TILs) in diverse solid tumors, including lung cancer. In addition, PD-L1 upregulation in tumor and/or stromal immune cells has been associated with increased clinical benefit to PD-1/PD-L1 axis blockers. The significance of PD-L1 expression in different immune cell subpopulations at the tumor microenvironment remains poorly understood. Here, we measured PD-L1 protein specifically in tumor-associated macrophages using objective methods and analyzed its clinical significance in human lung cancer.

Role of tumor-associated macrophages in lung cancer

The percentage of tumor-associated macrophages recovered (TAMR) and antitumoral activity of tumor-associated macrophages (TAM) were examined in 77 patients with resectable primary lung cancer. TAM was obtained by plastic adherence following trypsinization. TAMR increased from Stage I to Stage II and decreased in Stage III. It also increased in N1 as compared with N0 and N2 but was unrelated to tumor size. However, the cytostatic activity of TAM declined with advance in stage of the disease and an increase of tumor size, but it was relatively unaffected by the presence of metastasis to regional lymph nodes. There was no correlation between TAMR and the recurrence rate; however, cytostatic activity of TAM was correlated significantly with the prognosis of totally resected cases. TAMR and cytostatic activity of TAM tended to be lower in palliatively resected cases. These results suggest that the assessment of the antitumor activity of TAM, but not merely TAMR, may give prognostic information for lung cancer patients.