肿瘤相关巨噬细胞对恶性肿瘤临床预后和治疗的影响

肿瘤相关巨噬细胞(tumor-associated macrophages,TAMs)作为肿瘤微环境中(tumor microenvi-ronment,TME)的核心调控者在肿瘤的发生发展中具有重要作用.活化的肿瘤相关巨噬细胞可分化出具有不同活化状态和功能的M1型和M2型,M1型肿瘤相关巨噬细胞主要介导抗肿瘤免疫效应,...     

Clinical significance of macrophage heterogeneity in human malignant tumors

The fact that various immune cells, including macrophages, can be found in tumor tissue has long been known. With the recent introduction of the novel concept of macrophage differentiation into a classically activated phenotype (M1) and an alternatively activated phenotype (M2), the role of tumor‐associated macrophages (TAMs) is gradually beginning to be elucidated. Specifically, in human malignant tumors, TAMs that have differentiated into M2 macrophages act as “protumoral macrophages” and contribute to the progression of disease. Based on recent basic and preclinical research, TAMs that have differentiated into protumoral or M2 macrophages are believed to be intimately involved in the angiogenesis, immunosuppression, and activation of tumor cells. In this paper, we specifically discuss both the role of TAMs in human malignant tumors and the cell–cell interactions between TAMs and tumor cells.     

Tumor versus tumor-associated macrophages: how hot is the link?

One of the functions of macrophages is to provide a defense mechanism against tumor cells. In contrast, tumor-associated macrophages (TAMs), which represent the major inflammatory component of the stroma of many tumors, are associated with tumor progression and metastasis. TAMs, in contrast with normal macrophages, exhibit the M2 phenotype, and thereby exhibit pro-tumoral functions, including angiogenesis and matrix remodeling. This review will discuss the role of TAMs in tumor progression and provide an overview of their significant part in tumor metastasis and angiogenesis.     

肿瘤相关巨噬细胞在鼻咽癌中的研究进展

肿瘤相关巨噬细胞(tumor-associated?macrophages,?TAMs)是肿瘤微环境中重要的免疫细胞,主要分为两种类型,即经典活化的M1型巨噬细胞和替代性活化的M2型巨噬细胞.TAMs在许多肿瘤组织中发挥M2型作用,即促进肿瘤的增殖、血管生成,诱导肿瘤细胞侵袭和转移,目前有关肿瘤相关巨噬细胞与肿瘤细胞之...     

Role of tumor-associated macrophages in common digestive system malignant tumors

Many digestive system malignant tumors are characterized by high incidence and mortality rate. Increasing evidence has revealed that the tumor microenvironment(TME) is involved in cancer initiation and tumor progression. Tumor-associated macrophages(TAMs) are a predominant constituent of the TME, and participate in the regulation of various biological behaviors and influence the prognosis of digestive system cancer. TAMs can be mainly classified into the antitumor M1 phenotype and protumor M2 ph...     

TAMs为靶点的抗肿瘤治疗研究进展

肿瘤微环境与肿瘤细胞通过分子和细胞间的相互作用,在肿瘤的发生发展和转移扩散中具有重要意义。肿瘤相关巨噬细胞（TAMs）作为肿瘤微环境中数量最多的炎症细胞群之一,在肿瘤进展中起到重要作用。肿瘤细胞通过释放多种趋化因子、细胞因子和生长因子招募巨噬细胞,并使其向M2型巨噬细胞类似的特性发展。同时,巨噬细胞释放多种因子,促进肿瘤细胞的生长、血管新生、迁移、侵袭、侵入血管并最终形成远处转移。TAMs在肿瘤组织中的密度与肿瘤患者治疗失败和不良预后密切相关,以TAMs为靶点的抗肿瘤治疗相关研究近年来取得重大进展。在肿瘤发生发展中根据TAMs的作用机制,以TAMs为靶点的抗肿瘤治疗策略是抑制肿瘤微环境中巨噬细胞招募、TAMs生存能力、TAMs表型即由M2型转化为M1型的重塑。本文就TAMs为靶点的抗肿瘤治疗最新进展进行综述。      

结直肠癌免疫微环境中肿瘤相关巨噬细胞的作用

结直肠癌（colorectal cancer,CRC）的发生、发展不仅与肿瘤细胞本身的特性相关,也与肿瘤微环境（tumor microenvironment,TME）密切相关。肿瘤细胞及其微环境通过分泌多种细胞因子,将循环血液中的单核细胞招募至TME并使其极化为肿瘤相关巨噬细胞（tumor-associated macrophages,TAMs）。作为TME中最丰富的免疫细胞之一,TAMs的功能和特点与M2型巨噬细胞相似,TAMs主要具有刺激肿瘤细胞增殖、血管生成、基质重塑和促进肿瘤细胞侵袭及转移等作用。在多数肿瘤中,TAMs主要发挥促肿瘤作用并与患者的不良预后相关;但在CRC中,TAMs的作用仍存争议。本文主要就CRC免疫微环境中TAMs的作用及其机制进行综述,以展示TAMs对CRC患者的病程进展及预后的影响并探讨TAMs作为CRC免疫治疗靶点的可行性。      

外泌体在肿瘤细胞与TAMs之间相互作用中“桥梁”和调控作用的研究进展北大核心

外泌体是一类直径为30~100 nm的圆盘囊泡,其内包含许多组分,诸如复杂RNA和蛋白质等,主要参与细胞间的信号转导。肿瘤相关巨噬细胞(tumor-associated macrophages,TAMs)是肿瘤微环境中普遍存在的巨噬细胞,通过对肿瘤生长、免疫逃逸、侵袭和转移、耐药性等多方面的作用影响肿瘤进程。外泌体在肿瘤相关巨噬细胞的招募、极化及抗肿瘤免疫调控等方面发挥着重要的调节功能。同时,TAMs以外泌体为媒介作用于肿瘤细胞,从而构成了外泌体、TAMs与肿瘤细胞之间相互作用的调控通路。综上所述,本文旨在阐明肿瘤细胞与TAMs之间,以外泌体为“桥梁”相互影响的潜在机制,以及靶向肿瘤细胞和TAMs来源的外泌体在恶性肿瘤治疗中的展望。     

肿瘤相关巨噬细胞在肿瘤微环境中的作用新进展

众所周知,在肿瘤发生发展的各个阶段都有单核细胞通过血管壁进入肿瘤组织,这些单核细胞可分化形成具有独特表型的巨噬细胞,即肿瘤相关巨噬细胞（tumor-associated macrophages,TAMs）。TAMs是肿瘤微环境的重要组成部分,参与了肿瘤的发生、生长、侵袭及转移过程,其中,向肿瘤组织的转移是肿瘤恶性发展的关键步骤。本文将TAMs在肿瘤微环境形成中发挥作用的最新进展进行了总结,特别值得注意的是,细胞及动物实验研究表明,TAMs可为肿瘤的发生发展进程提供一个有利的微环境;同时,临床病理实验表明,TAMs在肿瘤内的累积与较差的临床疗效相关。最后,本文讨论了靶向TAMs的治疗手段作为一种间接癌症治疗新方法的可行性。     

Clinical significance of CD163+ tumor‐associated macrophages in patients with adult T‐cell leukemia/lymphoma

In several malignant tumors including lymphoma, macrophages that infiltrate tumor tissues are called tumor‐associated macrophages (TAMs). We discovered that TAMs, especially the CD163⁺ alternatively activated phenotype (M2), were closely involved with progression of adult T‐cell leukemia/lymphoma (ATLL). We used CD68 (a pan‐macrophage marker) and CD163 (an M2 marker) to immunostain 58 ATLL samples. Statistical analyses showed that a high number of CD68⁺ TAMs and an increased percentage of CD163⁺ cells among the TAMs were associated with a worse clinical prognosis; multivariate analysis indicated that the percentage of CD163⁺ cells was an independent prognostic factor. We also carried out in vitro coculture experiments with ATLL cell lines (ATN‐1 and TL‐Mor) and monocyte‐derived macrophages and found that direct coculture with M2 macrophages significantly increased BrdU incorporation into ATLL cell lines. A cytokine array analysis showed that macrophage‐derived soluble factors including C5a, tumor necrosis factor‐α, growth‐related oncogene‐α, CCL1/I‐309, and interleukin‐6 stimulated ATLL cell lines. CD163 expression in macrophages was strongly induced by direct contact with ATN‐1 cells, and downregulation of CD163 in macrophages significantly suppressed growth of cocultured ATN‐1 cells. These results suggest that interaction between M2 macrophages and lymphoma cells may be an appropriate target in treatment of patients with ATLL.     

TGF-β-induced IRAK-M expression in tumor-associated macrophages regulates lung tumor growth

Tumor-associated macrophages (TAMs) constitute a major component of the immune cell infiltrate observed in the tumor microenvironment (TME). Factors present in the TME, including tumor growth factor-β (TGF-β), allow tumors to circumvent host-mediated immune responses to promote tumor progression. However, the molecular mechanism(s) involved are not clear. Toll-like receptors (TLRs) are important mediators of innate immune responses by immune cells, whose activation triggers the production of molecules required for anti-tumoral responses. Interleukin (IL) receptor-associated kinase (IRAK)-M is an inactive serine/threonine kinase, predominantly expressed in macrophages and is a potent negative regulator of TLR signaling. In this study, we show that TAMs express significantly higher levels of IRAK-M compared with peritoneal macrophages in a syngeneic mouse model of lung cancer. Subcutaneous implantation of Lewis lung carcinoma cells in IRAK-M(-/-) mice resulted in a five-fold reduction in tumor growth as compared with tumors in wild-type (WT) animals. Furthermore, compared with WT TAMs, TAMs isolated from IRAK-M(-/-) mice displayed features of a classically activated (M1) rather than alternatively activated (M2) phenotype, as manifest by greater expression of IL-12, interferon-γ (IFN-γ) and inducible nitric oxide synthase. Human lung cancer cells induced IRAK-M expression in human peripheral blood mononuclear cells (PBMCs) when co-cultured together. Tumor cell-induced expression of IRAK-M was dependent on the activation of TGF-β pathway. Similarly, treatment of human PBMCs or mouse macrophage cell line, RAW 264.4, with TGF-β, induced IRAK-M expression. Interestingly, IRAK-M gene expression in 439 human lung adenocarcinoma tumors correlated with poor survival in patients with lung cancer. Together, our data demonstrates that TGF-β-dependent induction of IRAK-M expression is an important, clinically relevant mechanism by which tumors may circumvent anti-tumor responses of macrophages.     

肿瘤相关巨噬细胞的极化方式及其对乳腺癌进展的影响

乳腺癌是严重威胁女性健康的恶性肿瘤之一，在全球范围内，其发病率呈逐年升高以及年轻化的趋势。肿瘤相关巨噬细胞（tumor-associated macrophages,TAMs）是乳腺癌肿瘤微环境中重要的免疫细胞，功能多样，具有高度的可塑性。当前的研究认为，TAMs在乳腺癌形成早期常表现为M1样表型，而在乳腺癌进展的过程中则极化为M2样表型，M2型TAMs能够促进乳腺癌的细胞增殖、血管生成、免疫抑制以及耐药性，与乳腺癌的预后呈负相关。因此，对TAMs极化方向的干预可作为乳腺癌抗癌治疗的一个新的研究方向。本文主要对乳腺癌中TAMs极化的分子机制以及对乳腺癌进展的影响进行综述。     

肿瘤相关巨噬细胞在结直肠癌中的研究进展

肿瘤的进展和转移不仅与肿瘤自身的特性有关, 还与肿瘤所处的微环境密不可分。肿瘤相关巨噬细胞(tumor-associated macrophages, TAMs)是肿瘤微环境中数量最多的肿瘤相关炎性细胞, 在不同的信号刺激下可分化成抗肿瘤的M1型巨噬细胞或促肿瘤的M2型巨噬细胞。在许多恶性肿瘤中, TAMs被证实参与了肿瘤的进展和转移, M2型巨噬细胞较多。然而在结直肠癌中, 大部分研究却得出了相反的结论, 认为TAMs促进了炎症的发展, 抑制了肿瘤的进展和转移。但一些体内和体外实验却发现TAMs促进了结肠癌的增殖和转移, M2型巨噬细胞居多。此外, 还有研究发现在结直肠癌中TAMs的功能随位置、肿瘤分期的不同而变化, 而且并不以单纯的M1或M2形式存在, 往往同时表现出M1和M2的一些特点。本文就TAMs在结直肠癌中的研究现状做一综述, 以期全面了解TAMs在结直肠癌中的作用, 为进一步深入研究二者的关系提供线索。      

Metformin prevents cancer metastasis by inhibiting M2-like polarization of tumor associated macrophages

Accumulated evidence suggests that M2-like polarized tumor associated macrophages (TAMs) plays an important role in cancer progression and metastasis, establishing TAMs, especially M2-like TAMs as an appealing target for therapy intervention. Here we found that metformin significantly suppressed IL-13 induced M2-like polarization of macrophages, as illustrated by reduced expression of CD206, down-regulation of M2 marker mRNAs, and inhibition of M2-like macrophages promoted migration of cancer cells and endothelial cells. Metformin triggered AMPKα1 activation in macrophage and silencing of AMPKα1 partially abrogated the inhibitory effect of metformin in IL-13 induced M2-like polarization. Administration of AICAR, another activator of AMPK, also blocked the M2-like polarization of macrophages. Metformin greatly reduced the number of metastases of Lewis lung cancer without affecting tumor growth. In tumor tissues, the percentage of M2-like macrophage was decreased and the area of pericyte-coated vessels was increased. Further, the anti-metastatic effect of metformin was abolished when the animals were treated with macrophages eliminating agent clodronate liposome. These findings suggest that metformin is able to block the M2-like polarization of macrophages partially through AMPKα1, which plays an important role in metformin inhibited metastasis of Lewis lung cancer.     

Tumor-Associated Macrophages Facilitate the Proliferation and Migration of Cervical Cancer Cells

Tumor-associated macrophages (TAMs) are important components in tumor microenvironment. This study intended to explore the influence of TAMs on cervical cancer cells proliferation and migration. The expression levels of TAMs markers, CD68 and CD163, in tissues were examined by immunohistochemistry and increased with the progression of cervical lesions (p < 0.05). TAMs with M2-like phenotype (PMA(Polymethacrylate) induced THP-1 cells) were noticed to promote the proliferation of cervical cancer cells and improve the migration ability of tumor cells. These enhancements were attributed to secreting soluble components and the physical contact between macrophages and tumor cells. The tumor formation and tumor growth were significantly faster in the mixed group of induced THP-1 cells and SiHa than in the SiHa cells alone group (p < 0.05). The results indicated that the interaction of macrophages and cervical cancer cells, including the secretion of soluble components and physical contact, were responsible for shaping immunosuppression microenvironments and in promoting tumor cell proliferation and migration.     

The role of tumor-associated macrophages in gastric cancer development and their potential as a therapeutic target

Gastric cancer (GC) represents the fifth cause of cancer-related death worldwide. Molecular biology has become a central area of research in GC and there are currently at least three major classifications available to elucidate the mechanisms that drive GC oncogenesis. Further, tumor microenvironment seems to play a crucial role, and tumor-associated macrophages (TAMs) are emerging as key players in GC development. TAMs are cells derived from circulating chemokine- receptor-type 2 (CCR2) inflammatory monocytes in blood and can be divided into two main types, M1 and M2 TAMs. M2 TAMs play an important role in tumor progression, promoting a pro-angiogenic and immunosuppressive signal in the tumor. The diffuse GC subtype, in particular, seems to be strongly characterized by an immuno-suppressive and pro-angiogenic phenotype. No molecular targets in this subgroup have yet been identified. There is an urgent need to understand the molecular pathways and tumor microenvironment features in the GC molecular subtypes. The role of anti-angiogenics and checkpoint inhibitors has recently been clinically validated in GC. Both ramucirumab, a fully humanized IgG1 monoclonal anti-vascular endothelial growth factor receptor 2 (VEGFR2) antibody, and checkpoint inhibitors in Epstein Bar Virus (EBV) and Microsatellite Instable (MSI) subtypes, have proved beneficial in advanced GC. Nevertheless, there is a need to identify predictive markers of response to anti-angiogenics and immunotherapy in clinical practice for a personalized treatment approach. The importance of M2 TAMs in development of solid tumors is currently gaining increasing interest. In this literature review we analyze immune microenvironment composition and signaling related to M1 and M2 TAMs in GC as well as its potential role as a therapeutic target.     

Impact of tumor‐associated macrophages on invasive ductal carcinoma of the pancreas head

Tumor‐associated macrophages (TAMs) are candidate histological factors in invasive ductal carcinoma (IDC) of the pancreas. Tumor‐associated macrophages can be affected by cancer‐related inflammation and pancreatitis and interact with important invasive behavior in a recurrent manner in pancreatic IDC. These features may help elucidate the aggressiveness of pancreatic IDC. The aim of this study was to characterize TAMs in pancreatic IDC in comparison with chronic pancreatitis (CP) and to reveal TAM‐related factors and the clinical impact of TAMs. CD68 (a pan‐macrophage marker) and CD204 (an M2 macrophage marker) immunohistochemistry was carried out in pancreas head specimens from 107 IDC cases and 11 CP cases. Immunopositive cell areas were calculated at the periphery and center of the tumor. The distributions of macrophages in IDC and CP and the relationship between TAMs and histological tumor factors, survival, and recurrence were evaluated. Macrophages were more frequently observed in the lesion periphery than the center in IDC and CP. The density of macrophages was elevated in IDC compared to CP. Dense M2 macrophages at the tumor periphery were frequently seen in large tumors and showed an independent impact on overall survival and disease‐free time. Early recurrence in the liver or the local manipulated area was associated with high accumulation of peripheral M2 macrophages. More M2 macrophages were seen in IDC than in CP in both the periphery and the center. High numbers of peripheral M2 macrophages were associated with large tumor size, early recurrence in the liver, local recurrence, and shortened survival time in patients with pancreatic IDC. (Cancer Sci, doi: 10.1111/j.1349‐7006.2012.02411.x, 2012)     

不同表型肿瘤相关巨噬细胞在肿瘤进展中的作用

随着对肿瘤发生、侵袭和转移过程研究的不断深入,临床发现肿瘤相关巨噬细胞（tumor associated macrophage,TAM）在肿瘤微环境中扮演重要角色。由于经典活化的巨噬细胞（M1）/替代性活化的巨噬细胞（M2）理论过度简化了TAM在肿瘤微环境中的多种作用,目前临床大多根据表面蛋白表达的不同将TAM重新分为CD68+TAM、CD163+TAM、CD204+TAM、CD169+TAM、CCL18+TAM等。各型TAM表达的表面蛋白具有不同类型的配体并调控着不同的信号通路和细胞因子。因此,这些亚型的TAM具有促进或抑制肿瘤的类似作用,但其所牵涉的机制以及带来的临床表现均不相同。本文将就TAM各类表型对各类肿瘤的生长、转移、预后的影响及其临床关联进行综述。      

Role of tumor-associated macrophages at the invasive front in human colorectal cancer progression

Macrophages are an essential component of antitumor activity; however, the role of tumor-associated macrophages (TAMs) in colorectal cancer (CRC) remains controversial. Here, we elucidated the role of TAMs in CRC progression, especially at the early stage. We assessed the TAM number, phenotype, and distribution in 53 patients with colorectal neoplasia, including intramucosal neoplasia, submucosal invasive colorectal cancer (SM-CRC), and advanced cancer, using double immunofluorescence for CD68 and CD163. Next, we focused on the invasive front in SM-CRC and association between TAMs and clinicopathological features including lymph node metastasis, which were evaluated in 87 SM-CRC clinical specimens. The number of M2 macrophages increased with tumor progression and dynamic changes were observed with respect to the number and phenotype of TAMs at the invasive front, especially at the stage of submucosal invasion. A high M2 macrophage count at the invasive front was correlated with lymphovascular invasion, low histological differentiation, and lymph node metastasis; a low M1 macrophage count at the invasive front was correlated with lymph node metastasis. Furthermore, receiver operating characteristic curve analysis revealed that the M2/M1 ratio was a better predictor of the risk of lymph node metastasis than the pan-, M1, or M2 macrophage counts at the invasive front. These results suggested that TAMs at the invasive front might play a role in CRC progression, especially at the early stages. Therefore, evaluating the TAM phenotype, number, and distribution may be a potential predictor of metastasis, including lymph node metastasis, and TAMs may be a potential CRC therapeutic target.     

SLC3A2 promotes tumor-associated macrophage polarization through metabolic reprogramming in lung cancer

Tumor-associated macrophages (TAMs) are one of the most abundant immunosuppressive cells in the tumor microenvironment and possess crucial functions in facilitating tumor progression. Emerging evidence indicates that altered metabolic properties in cancer cells support the tumorigenic functions of TAMs. However, the mechanisms and mediators the underly the cross-talk between cancer cells and TAMs remain largely unknown. In the present study, we revealed that high solute carrier family 3 member 2 (SLC3A2) expression in lung cancer patients was associated with TAMs and poor prognosis. Knockdown of SLC3A2 in lung adenocarcinoma cells impaired M2 polarization of macrophages in a coculture system. Using metabolome analysis, we identified that SLC3A2 knockdown altered the metabolism of lung cancer cells and changed multiple metabolites, including arachidonic acid, in the tumor microenvironment. More importantly, we showed that arachidonic acid was responsible for SLC3A2-mediated macrophage polarization in the tumor microenvironment to differentiate into M2 type both in vitro and in vivo. Our data illustrate previously undescribed mechanisms responsible for TAM polarization and suggest that SLC3A2 acts as a metabolic switch on lung adenocarcinoma cells to induce macrophage phenotypic reprogramming through arachidonic acid.