肿瘤相关成纤维细胞与肿瘤微环境

肿瘤的发展过程与肿瘤微环境密切相关,而肿瘤相关成纤维细胞(CAFs)是上述微环境中最主要的宿主细胞,CAFs是一类不同细胞源性的细胞群,可来源于多种细胞包括静止的成纤维细胞、上皮细胞、内皮细胞和间质干细胞的分化过程。体内和体外生物学实验均证实,成纤维细胞在肿瘤微环境中并不是被动的对肿瘤发展提供支持,而是发挥了至关重要的作用,所以靶向CAFs有望成为肿瘤治疗的新方向,对CAFs相关分子标记物和分子事件的进一步探索将为抗肿瘤的临床治疗提供新的思路。本文将对CAFs的来源以及CAFs对肿瘤发生发展、转移及VEGF耐受等方面的作用做一综述。     

肿瘤相关成纤维细胞促进肿瘤侵袭转移的作用机制

肿瘤相关成纤维细胞(cancer-associated fibroblasts,CAFs)是肿瘤微环境中最主要的成分之一,在肿瘤的发生发展中发挥着必不可少的作用。骨髓和脂肪的局部组织固有成纤维细胞及间充质干细胞是CAFs来源的主要前体细胞。大量研究表明,CAFs并不作为单独细胞在肿瘤周围存在,而是和肿瘤细胞相互作用,促进肿瘤的生长与存活并维持其恶性倾向。肿瘤细胞可以影响CAFs前体的招募,并诱导正常成纤维细胞活化为CAFs;同时,CAFs可以分泌多种细胞因子、生长因子和细胞外基质蛋白质,促进肿瘤细胞的增殖、耐药及侵袭转移,从而影响肿瘤的预后。CAFs还参与血管淋巴管的生成、细胞外基质重塑、免疫抑制以及肿瘤细胞上皮间质转化等有利于肿瘤发生发展的外源性途径,为肿瘤细胞提供了一个良好的微环境。大量研究显示,研发靶向CAFs的药物可以中断其与肿瘤细胞之间的联系,从而抑制肿瘤的生长和转移。因此,深入了解CAFs促肿瘤的作用机制将有利于肿瘤治疗新靶点的发现。本文将对CAFs促进肿瘤侵袭转移的作用机制加以综述。     

成纤维细胞激活蛋白α与肿瘤发展进程的研究

肿瘤微环境对肿瘤的发生、发展具有重要的意义。选择性表达于肿瘤微环境重要组成部分——肿瘤相关成纤维细胞（carcinoma associated fibroblasts,CAFs）表面的成纤维细胞激活蛋白α（fibroblast activation protein-α,FAPα）广泛参与了肿瘤的生长、侵袭、转移以及肿瘤细胞外基质重建、血管生成、免疫逃逸等过程,从而促进了肿瘤的发展进程。FAPα具有蛋白水解酶活性,并作用于细胞信号通路,但FAPα在肿瘤微环境中发挥功能的具体分子机制还有待进一步研究。由于FAPα的表达具有肿瘤组织特异性,因此,以FAPα作为肿瘤基质标志物,对肿瘤进行病理诊断和免疫治疗将成为新兴的研究靶点。对FAPα的主要生物学性状进行概述,并综述了其对肿瘤细胞的生长、侵袭、转移以及肿瘤细胞外基质重建、血管生成、免疫逃逸等方面的重要影响。     

肿瘤相关成纤维细胞与成纤维细胞活化蛋白在肿瘤免疫治疗中的研究进展

除了依赖于肿瘤细胞自身的恶性增殖以外,肿瘤的发生和发展还依赖于肿瘤细胞与肿瘤间质微环境的相互作用。肿瘤间质中存在的肿瘤相关成纤维细胞（tumor-associatedfibroblasts,TAF）能够诱导免疫抑制,是肿瘤免疫治疗中的一大障碍。在TAF上存在一种成纤维细胞激活蛋白（fibroblast activationprotein,FAP）,它在细胞表面发挥作用,是一种膜丝氨酸肽酶,是Ⅱ型丝氨酸蛋白酶家族成员之一,具有二肽肽酶及胶原酶活性,在肿瘤微环境中表达FAP的肿瘤相关成纤维细胞是最早被鉴定的一种肿瘤间质细胞类型。它由肿瘤问质中的成纤维细胞与癌细胞相互作用而活化,是肿瘤微环境中最主要的宿主细胞,具有促进肿瘤细胞生长、侵袭及免疫抑制的作用,而且基因组稳定不易耐药,有望成为肿瘤免疫治疗的新靶标。就靶向TAF和FAP在肿瘤免疫治疗中的研究做一综述,为基于肿瘤间质微环境的免疫治疗提供参考。     

综述: 细胞外基质与肿瘤相关成纤维细胞

肿瘤的发生发展是一个肿瘤细胞与其微环境相互促进,共同演化的动态过程．实体肿瘤的发生发展过程伴随细胞外基质的过量沉积及其组织形式的异常以及成纤维细胞的活化和富集．细胞外基质与肿瘤相关成纤维细胞不仅是实体肿瘤的重要病理特征,同时也是恶性肿瘤发展的重要驱动力量．细胞外基质与肿瘤相关成纤维细胞通过多种机制促进了肿瘤的发生、发展和转移．针对细胞外基质与肿瘤相关成纤维细胞进行肿瘤治疗,可以为肿瘤的临床治疗提供新的思路．     

斑马鱼肝癌细胞与肿瘤相关成纤维细胞可视化转移模型的构建

目的 利用斑马鱼构建肝癌细胞与肿瘤相关成纤维细胞(cancer associated fibroblasts, CAFs)可视化转移模型,为CAFs介导的肿瘤转移患者的机制研究和药效评价提供临床前模型。方法 建立肝癌Huh7细胞与CAFs体外共培养体系,分别采用CCK8和Transwell小室检测Huh7细胞的增殖和迁移能力。同时将不同颜色荧光标记的Huh7细胞和CAFs注射到斑马鱼卵黄周隙中,构建可视化转移模型,观察CAFs对Huh7细胞迁移的影响以及Huh7细胞与CAFs在血管中的结合情况。结果 与CAFs共培养的Huh7细胞的增殖和迁移能力显著增加。此外,成功建立斑马鱼肝癌细胞和CAFs可视化转移模型。与CAFs共注射的Huh7细胞的迁移能力和结合率显著增加。结论 CAFs促进肝癌细胞的迁移,并且在远端转移中,大多数肝癌细胞与CAFs仍处于紧密结合状态。因此在临床上可以靶向实体瘤的成纤维成分,阻断其对肿瘤的支持作用,为肿瘤治疗提供新策略。     

胃癌组织中肿瘤相关成纤维细胞与正常成纤维细胞之间转录组学研究及验证

胃癌组织中肿瘤相关成纤维细胞(carcinoma associated fibroblasts, CAFs)是胃癌微环境的重要成分,主要来源于正常成纤维细胞(normal fibroblasts, NFs)的活化,对胃癌的发生发展有重要作用,但是两者之间的基因表达差异并不完全清楚。本研究选取从人胃癌组织中分离获得的CAFs及NFs 各3组,进行转录组学研究,筛选出3组细胞中交集且差异倍数较大的基因12个,用Omicsbean在线工具对差异基因进行Gene Ontology (GO)功能及KEGG通路富集,构建蛋白质相互作用调控网络;最后用RT-qPCR验证CAFs和NFs中差异基因的表达。结果显示,筛选出的12个差异表达基因主要参与NF-κB信号、炎症、细胞黏附、细胞表面受体和细胞因子等功能,上述功能均与肿瘤的发生发展密切相关。RT-qPCR检测发现,与NFs相比,CAFs中BCL2A1、NKX3-2、CXCL12、TNFAIP3、FOS、CDH4及CLDN1表达上调;ATF3、CYFIP2、CCL11、KLF2及GDF15基因表达下调,差异均具有统计学意义(P＜0.05)。结果提示,胃癌CAFs与NFs中存在肿瘤相关的差异表达基因,这些差异基因可能在胃癌微环境中发挥重要作用。     

结缔组织生成和肿瘤

肿瘤的发生并不只是由肿瘤细胞本身恶化引起的,肿瘤基质也发挥了非常重要的作用,肿瘤发生是肿瘤细胞和围绕它的肿瘤基质相互作用的产物。肿瘤细胞可以通过各种途径激活与其相邻的间质,促进成纤维细胞的增生、细胞外基质的沉积、免疫细胞浸润和血管生成,这种现象被称为结缔组织生成。结缔组织生成形成了一个支持肿瘤发展的微环境,通过多种途径促进了肿瘤的发生、发展和转移。针对结缔组织生成进行肿瘤治疗可以为肿瘤的临床治疗提供新的思路。     

成纤维细胞激活蛋白alpha与肿瘤免疫抑制的研究进展

成纤维细胞激活蛋白alpha（Fibroblast activation protein-alpha,FAP-alpha）是一种跨膜丝氨酸蛋白酶,高度表达在90 %的上皮性肿瘤的 间质--肿瘤相关成纤维细胞（Tumor association fibroblast,TAF）上。FAPalpha在促进上皮性肿瘤的恶性进展中起着十分重要的作用, 近年来研究发现,FAP琢在肿瘤微环境中发挥免疫抑制的作用。研究FAPalpha在肿瘤免疫抑制中的作用,已成为肿瘤研究的新的热 点。为基于以FAP-alpha为靶标的抗肿瘤免疫治疗提供参考,本文围绕引起肿瘤免疫抑制的因素、FAPalpha与肿瘤免疫抑制的研究进展 以及FAP-alpha在肿瘤的发展进程的作用作一综述。     

结缔组织生成和肿瘤

肿瘤的发生并不只是由肿瘤细胞本身恶化引起的,肿瘤基质也发挥了非常重要的作用,肿瘤发生是肿瘤细胞和围绕它的肿瘤基质相互作用的产物。肿瘤细胞可以通过各种途径激活与其相邻的间质,促进成纤维细胞的增生、细胞外基质的沉积、免疫细胞浸润和血管生成,这种现象被称为结缔组织生成。结缔组织生成形成了一个支持肿瘤发展的微环境,通过多种途径促进了肿瘤的发生、发展和转移。针对结缔组织生成进行肿瘤治疗可以为肿瘤的临床治疗提供新的思路。     

Extracellular vesicle-orchestrated crosstalk between cancer-associated fibroblasts and tumors

Communication networks in the tumor microenvironment (TME) play a crucial role in tumor progression. Cancer-associated fibroblasts (CAFs) are among the most abundant stromal cells in the TME. Bidirectional signal transduction between cancer cells and CAFs within the TME is important for cancer development and treatment responsiveness. Extracellular vesicles (EVs) carrying proteins, miRNAs, and other biomolecules are secreted into the extracellular matrix (ECM), which has been demonstrated to be an important communication medium between tumors and CAFs. Tumors regulate the activation of CAFs by secreting EVs. Conversely, CAFs can also affect tumor proliferation, metastasis, and therapeutic resistance through EVs. Here, we will classify EV cargoes and discuss the role of EV-mediated interactions between CAFs and tumors, reviewing current knowledge in combination with our confirmed results.     

Extracellular vesicle-orchestrated crosstalk between cancer-associated fibroblasts and tumors

Communication networks in the tumor microenvironment (TME) play a crucial role in tumor progression. Cancer-associated fibroblasts (CAFs) are among the most abundant stromal cells in the TME. Bidirectional signal transduction between cancer cells and CAFs within the TME is important for cancer development and treatment responsiveness. Extracellular vesicles (EVs) carrying proteins, miRNAs, and other biomolecules are secreted into the extracellular matrix (ECM), which has been demonstrated to be an important communication medium between tumors and CAFs. Tumors regulate the activation of CAFs by secreting EVs. Conversely, CAFs can also affect tumor proliferation, metastasis, and therapeutic resistance through EVs. Here, we will classify EV cargoes and discuss the role of EV-mediated interactions between CAFs and tumors, reviewing current knowledge in combination with our confirmed results.     

Autophagic secretion of HMGB1 from cancer-associated fibroblasts promotes metastatic potential of non-small cell lung cancer cells via NFκB signaling

Tumor progression requires the communication between tumor cells and tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are major components of stromal cells. CAFs contribute to metastasis process through direct or indirect interaction with tumor cells; however, the underlying mechanism is largely unknown. Here, we reported that autophagy was upregulated in lung cancer-associated CAFs compared to normal fibroblasts (NFs), and autophagy was responsible for the promoting effect of CAFs on non-small cell lung cancer (NSCLC) cell migration and invasion. Inhibition of CAFs autophagy attenuated their regulation on epithelial–mesenchymal transition (EMT) and metastasis-related genes of NSCLC cells. High mobility group box 1 (HMGB1) secreted by CAFs mediated CAFs’ effect on lung cancer cell invasion, demonstrated by using recombinant HMGB1, HMGB1 neutralizing antibody, and HMGB1 inhibitor glycyrrhizin (GA). Importantly, the autophagy blockade of CAFs revealed that HMGB1 release was dependent on autophagy. We also found HMGB1 was responsible, at least in part, for autophagy activation of CAFs, suggesting CAFs remain active through an autocrine HMGB1 loop. Further study demonstrated that HMGB1 facilitated lung cancer cell invasion by activating the NFκB pathway. In a mouse xenograft model, the autophagy specific inhibitor chloroquine abolished the stimulating effect of CAFs on tumor growth. These results elucidated an oncogenic function for secretory autophagy in lung cancer-associated CAFs that promotes metastasis potential, and suggested HMGB1 as a novel therapeutic target.Subject terms: Cancer microenvironment, Non-small-cell lung cancer, Metastasis, Translational research     

Crosstalk between cancer‐associated fibroblasts and immune cells in cancer

Multiple studies have shown that cancer‐associated fibroblasts (CAFs) play an important role in tumour progression, including carcinogenesis, invasion, metastasis and the chemoresistance of cancer cells. Immune cells, including macrophages, natural killer cells, dendritic cells and T cells, play a dual role in the tumour microenvironment. Although increasing research has focused on studying interactions between distinct cells in the tumour microenvironment, the complex relationships between CAFs and immune cells remain unclear and need further study. Here, we summarize our current understanding of crosstalk between CAFs and immune cells, which may help clarify their diagnostic and therapeutic value in tumour progression.     

Three-dimensional Co-culture Model for Tumor-stromal Interaction

Cancer progression (initiation, growth, invasion and metastasis) occurs through interactions between malignant cells and the surrounding tumor stromal cells. The tumor microenvironment is comprised of a variety of cell types, such as fibroblasts, immune cells, vascular endothelial cells, pericytes and bone-marrow-derived cells, embedded in the extracellular matrix (ECM). Cancer-associated fibroblasts (CAFs) have a pro-tumorigenic role through the secretion of soluble factors, angiogenesis and ECM remodeling. The experimental models for cancer cell survival, proliferation, migration, and invasion have mostly relied on two-dimensional monocellular and monolayer tissue cultures or Boyden chamber assays. However, these experiments do not precisely reflect the physiological or pathological conditions in a diseased organ. To gain a better understanding of tumor stromal or tumor matrix interactions, multicellular and three-dimensional cultures provide more powerful tools for investigating intercellular communication and ECM-dependent modulation of cancer cell behavior. As a platform for this type of study, we present an experimental model in which cancer cells are cultured on collagen gels embedded with primary cultures of CAFs.     

MicroRNA regulation in cancer-associated fibroblasts

The microenvironment of cancer cells has proven to be a critical component of tumors that strongly influences cancer development and progression into invasive and metastatic disease. Compared to normal tissue, dramatic differences in gene expression occur in multiple cell types that constitute the tumor microenvironment including cancer-associated fibroblasts (CAFs) that are important stromal components of growing tumors. In this review, we present recent advances in understanding how microRNAs are deregulated in cancer-associated fibroblasts (CAFs) and how this affects tumor biology. The microRNA signature of CAFs is discussed with respect to their functional relevance to tumor cells as well as other cell types involved in tumor homeostasis.     

Hematopoietic stem cell-derived adipocytes and fibroblasts in the tumor microenvironment

The tumor microenvironment(TME) is complex and constantly evolving. This is due, in part, to the crosstalk between tumor cells and the multiple cell types that comprise the TME, which results in a heterogeneous population of tumor cells and TME cells. This review will focus on two stromal cell types, the cancerassociated adipocyte(CAA) and the cancer-associated fibroblast(CAF). In the clinic, the presence of CAAs and CAFs in the TME translates to poor prognosis in multiple tumor types. CAAs and CAFs have an activated phenotype and produce growth factors, inflammatory factors, cytokines, chemokines, extracellular matrix components, and proteases in an accelerated and aberrant fashion. Through this activated state, CAAs and CAFs remodel the TME, thereby driving all aspects of tumor progression, including tumor growth and survival, chemoresistance, tumor vascularization, tumor invasion, and tumor cell metastasis. Similarities in the tumorpromoting functions of CAAs and CAFs suggest that a multipronged therapeutic approach may be necessary to achieve maximal impact on disease. While CAAs and CAFs are thought to arise from tissues adjacent to the tumor, multiple alternative origins for CAAs and CAFs have recently been identified. Recent studies from our lab and others suggest that the hematopoietic stem cell, through the myeloid lineage, may serve as a progenitor for CAAs and CAFs. We hypothesize that the multiple origins of CAAs and CAFs may contribute to the heterogeneity seen in the TME. Thus, a better understanding of the origin of CAAs and CAFs, how this origin impacts their functions in the TME, and thetemporal participation of uniquely originating TME cells may lead to novel or improved anti-tumor therapeutics.     

Cancer-associated fibroblasts: Mediators of head and neck tumor microenvironment remodeling

Cancer-associated fibroblasts (CAFs) are involved in critical aspects of head and neck squamous cell carcinoma (HNSCC) pathogenesis, such as the formation of a tumor-permissive extracellular matrix structure, angiogenesis, or immune and metabolic reprogramming of the tumor microenvironment (TME), with implications for metastasis and resistance to radiotherapy and chemotherapy. The pleiotropic effect of CAFs in TME is likely to reflect the heterogeneity and plasticity of their population, with context-dependent effects on carcinogenesis. The specific properties of CAFs provide many targetable molecules that could play an important role in the future therapy of HNSCC. In this review article, we will focus on the role of CAFs in the TME of HNSCC tumors. We will also discuss clinically relevant agents targeting CAFs, their signals, and signaling pathways, which are activated by CAFs in cancer cells, with the potential for repurposing for HNSCC therapy.