LTBP-2 confers pleiotropic suppression and promotes dormancy in a growth factor permissive microenvironment in nasopharyngeal carcinoma

This study identified LTBP-2 as a pleiotropic tumor suppressor in nasopharyngeal carcinoma, which safeguards against critical malignant behaviors of tumor cells. LTBP-2 expression was significantly decreased or lost in up to 100% of NPC cell lines (7/7) and 80% of biopsies (24/30). Promoter hypermethylation was found to be involved in LTBP-2 silencing. Using a tetracycline-regulated inducible expression system, we unveiled functional roles of LTBP-2 in suppressing colony formation, anchorage-independent growth, cell migration, angiogenesis, VEGF secretion, and tumorigenicity. Three-dimensional culture studies suggested the involvement of LTBP-2 in maintenance of tumor cell dormancy in a growth factor favorable microenvironment.     

Tumor microenvironment modifications induced by soluble VEGF receptor expression in a rat liver metastasis model

Vascular endothelial growth factor is a potent pro-angiogenic growth factor which is also known to alter tumor microenvironment by inhibiting dendritic cell differentiation and promoting accumulation of myeloid-derived suppressor cells. In the present study, we analyzed the modifications induced by intratumoral expression of sFLT-1, a soluble VEGF receptor, in a rat metastatic colon carcinoma model. We generated colon cancer cell lines stably expressing sFLT-1 or a mock construct. Human umbilical vein endothelial cells cultured with conditioned medium from sFLT-1-expressing tumor cells exhibit a significantly decreased survival, demonstrating the functionality of the secreted sFLT-1. Invivo, sFLT-1 expression induced a 30% decrease in microvessel density in 15-day old experimental liver metastasis from colon carcinoma. Tumor growth was inhibited by 63% and 52% in left and right liver lobes respectively within 25 days. In these tumors, sFLT-1 expression was associated with a decreased myeloid cell infiltration and a modification in the expression of several cytokines/chemokines. Altogether, these results suggest that VEGF trapping by sFLT-1 intratumoral expression results in reduced vascularization, tumor growth inhibition and modification of immune tumor microenvironment.     

Tumor macrophages as a target for Capsaicin mediated immunotherapy

Tumor microenvironment contributes to a large extent for failure of immunological destruction of antigenic tumors. Most solid tumors adapt to the microenvironment and escape the host immune system. The dramatic and systemic effectiveness of neuro-immune ligand Capsaicin (CP) in regression of established solid tumors led us to investigate its immunomodulatory role in tumor microenvironment. In this report we demonstrate that CP induced tumor cell apoptosis leads to increased sensitization of the surrounding stroma manifested by enhanced antigen presentation by stromal macrophages and its destruction by tumor specific T-cells. Further, CP injection alters the tumor microenvironment with regards to tumor-infiltrating Treg cells as well as the cytokine milieu at the tumor site. Our data collectively demonstrates that injection of CP sets in motion, a cascade of several independent innate and adaptive immunological events initiated at the tumor environment.     

Targeting the vascular endothelial growth factor pathway in the treatment of multiple myeloma

Multiple myeloma is a clonal plasma cell malignancy within the bone marrow associated with bone loss, renal disease and immunodeficiency. Despite new insights into the pathogenesis of multiple myeloma and novel targeted therapies, the median survival remains 3–5 years. It is now well established that the intimate relation between the tumor cells and components of the microenvironment plays a key role in multiple myeloma pathogenesis. Specifically, tumor cells impact the bone marrow and thereby cause immune suppression and lytic bone lesions; conversely, components of the bone marrow provide signals that influence the behavior of multiple myeloma cells, including tumor cell growth, survival, migration and drug resistance. Important contributing effectors are tumor cell–stroma cell and cell–extracellular matrix contacts, the bone marrow vasculature, and a variety of cytokines and growth factors in the bone marrow milieu.     

Cytotoxic T cells - stroma interactions

The tumor microenvironment is a complex system playing an important role in tumor development and progression. Besides tumor cells, the tumor microenvironment harbours a variety of host-derived cells, such as endothelial cells, fibroblasts, innate and adaptive immune cells, as well as extracellular matrix (ECM) fibers, cytokines, and other mediators. This review discusses the potential role of hypoxia and endothelial cells within tumor microenvironment and emphasizes their interaction with antigen specific killer cells.     

Stromal fibroblasts synergize with hypoxic oxidative stress to enhance melanoma aggressiveness

On the basis of recent advances indicating a key role of microenvironment for tumor progression, we investigated the role of fibroblasts, macrophages and hypoxia, for primary melanoma aggressiveness. Our data indicate a key role of hypoxia in stromal reactivity, acting on both myofibroblasts and machrophages differentiation. Hypoxic myofibroblasts are more active than macrophages in inducing melanoma invasiveness and exploit their oxidative stress due to hypoxia to secrete soluble factors favouring melanoma invasion and chemotaxis. We underscore the key role of microenviroment on melanoma malignancy, highlighting reactive fibroblasts, intratumoral hypoxia and oxidative stress as promising targets for melanoma antimetastatic strategies.     

LAMC1 upregulation via TGFβ induces inflammatory cancer‐associated fibroblasts in esophageal squamous cell carcinoma via NF‐κB–CXCL1–STAT3

Cancer‐associated fibroblasts (CAF) are a heterogeneous cell population within the tumor microenvironment,and play an important role in tumor development. By regulating the heterogeneity of CAF, transforming growth factor β (TGFβ) influences tumor development. Here, we explored oncogenes regulated by TGFβ1 that are also involved in signaling pathways and interactions within the tumor microenvironment. We analyzed sequencing data of The Cancer Genome Atlas (TCGA) and our own previously established RNA microarray data ({"type":"entrez-geo","attrs":{"text":"GSE53625","term_id":"53625"}}GSE53625), as well as esophageal squamous cell carcinoma (ESCC) cell lines with or without TGFβ1 stimulation. We then focused on laminin subunit gamma 1 (LAMC1), which was overexpressed in ESCC cells, affecting patient prognosis, which could be upregulated by TGFβ1 through the synergistic activation of SMAD family member 4 (SMAD4) and SP1. LAMC1 directly promoted the proliferation and migration of tumor cells, mainly via Akt–NFκB–MMP9/14 signaling. Additionally, LAMC1 promoted CXCL1 secretion, which stimulated the formation of inflammatory CAF (iCAF) through CXCR2–pSTAT3. Inflammatory CAF promoted tumor progression. In summary, we identified the dual mechanism by which the upregulation of LAMC1 by TGFβ in tumor cells not only promotes ESCC proliferation and migration, but also indirectly induces carcinogenesis by stimulating CXCL1 secretion to promote the formation of iCAF. This finding suggests that LAMC1 could be a potential therapeutic target and prognostic marker for ESCC.     

沉默或抑制TAK1表达能够通过NF-κB信号通路改善卵巢癌细胞的紫杉醇耐药性

目的:探究利用小干扰RNA(small interfering RNA,siRNA)或转化生长因子 β活化激酶1[transfor-ming growth factor-β(TGF-β)-activated kinase 1,TAK1]抑制剂5 Z-7-oxozeaenol进行靶向沉默或抑制TAK1表达对卵巢癌细胞紫杉...     

癌相关成纤维细胞通过Gro-α激活NF-кB核转位和VEGF表达促进卵巢癌的生长

背景与目的：卵巢癌相关成纤维细胞(cancer-associated fibroblasts,CAF)促进上皮肿瘤的发生,其分泌的趋化因子即生长调节致癌基因α(growth-regulated oncogene alpha,Gro-α)蛋白在肿瘤间质微环境中促进上皮卵巢癌的发生,但其作用机制并不清楚。本研究拟测定Gro-α蛋白是否通过激活间质成纤维细胞中NF-кB核转位和VEGF表达,促进卵巢癌的生长。方法：本研究采用ELISA法测定了两株卵巢癌CAF和两株正常卵巢组织成纤维细胞(normal fibroblasts,NF)条件培养基(conditioned medium,CM)中Gro-α的表达;用CAF-CM或Gro-α分别处理NF,并以NF-кB抑制剂处理作为对照;用蛋白质印迹法(Western blot)测定样品处理前后NF-кB和血管内皮细胞生长因子(vascular endothelial growth factor,VEGF)等分子的变化;然后用CAF或NF分别与卵巢癌细胞系OVCA429混合接种BALB/c裸小鼠,或在有、无NF-кB抑制剂PS1145处理的NF中,用CAFCM或Gro-α处理后,分别与OVCA429混合接种动物,观察和比较动物移植瘤生长及移植瘤组织中微血管形成情况。结果：Gro-α在CAF中比在NF中高5～6倍;与对照组相比,用CAF条件培养基或Gro-α处理的NF中NF-кB p65的核转位升高,且VEGF上升,但血管生成抑制因子-血小板反应蛋白1下降;用NF-кB抑制剂同时处理NF,可以逆转其VEGF和TSP-1的表达水平;动物试验结果发现CAF要比NF更易促进肿瘤生长,而CAF-CM或Gro-α处理的NF细胞可以促进动物移植瘤的快速增长和移植瘤组织中微血管的生成,但用NF-кB抑制剂处理的NF则抑制肿瘤生长和血管形成能力。结论：卵巢癌CAF在肿瘤微环境中通过自分泌Gro-α,激活NF-кB核转位和VEGF表达,促进卵巢癌组织血管增生和肿瘤的生长。     

Failure of anti tumor-derived endothelial cell immunotherapy depends on augmentation of tumor hypoxia

We have previously demonstrated that Tenascin-C (TNC)⁺ human neuroblastoma (NB) cells transdifferentiate into tumor-derived endothelial cells (TDEC), which have been detected both in primary tumors and in tumors formed by human NB cell lines in immunodeficient mice. TDEC are genetically unstable and may favor tumor progression, suggesting that their elimination could reduce tumor growth and dissemination. So far, TDEC have never been targeted by antibody-mediated immunotherapy in any of the tumor models investigated.To address this issue, immunodeficient mice carrying orthotopic NB formed by the HTLA-230 human cell line were treated with TDEC-targeting cytotoxic human (h)CD31, that spares host-derived endothelial cells, or isotype-matched mAbs. hCD31 mAb treatment did not affect survival of NB-bearing mice, but increased significantly hypoxia in tumor microenvironment, where apoptotic and proliferating TDEC coexisted, indicating the occurrence of vascular remodeling.Tumor cells from hCD31 mAb treated mice showed i) up-regulation of epithelial-mesenchymal transition (EMT)-related and vascular mimicry (VM)-related gene expression, ii) expression of endothelial (i.e. CD31 and VE-cadherin) and EMT-associated (i.e. Twist-1, N-cadherin and TNC) immunophenotypic markers, and iii) up-regulation of high mobility group box-1 (HMGB-1) expression. In vitro experiments with two NB cell lines showed that hypoxia was the common driver of all the above phenomena and that human recombinant HMGB-1 amplified EMT and TDEC trans-differentiation.In conclusion, TDEC targeting with hCD31 mAb increases tumor hypoxia, setting the stage for the occurrence of EMT and of new waves of TDEC trans-differentiation. These adaptive responses to the changes induced by immunotherapy in the tumor microenvironment allow tumor cells to escape from the effects of hCD31 mAb.     

Effect of a hypoxic microenvironment after radiofrequency ablation on residual hepatocellular cell migration and invasion

Clinical observations have shown that the boundary of tumor ablation is often less than safe border and that the use of radiofrequency ablation (RFA) in the treatment of hepatocellular carcinoma (HCC) may probably accelerate its recurrence and metastasis. RFA can cause the formation of a transition zone between normal liver tissues and necrotic coagulation, where blood stagnation and thrombosis expose residual cancer cells to a hypoxic microenvironment. As the blocked vessels are slowly reperfused, the oxygen supply is gradually restored. Here, HCC cells underwent heat treatment and were cultured under hypoxic conditions to mimic the aforementioned situation, and morphological changes were observed in the surviving cells. Compared with their parental cells, hypoxic HCC cells showed changes that include enhanced invasive, metastatic, and chemoresistant abilities as well as mesenchymal characteristics. There was also a higher percentage of stem‐like cells. However, either improving the hypoxic microenvironment or silencing hypoxia inducible factor (HIF)‐1α signaling significantly reduced the invasive, metastatic, and chemoresistant potential and reversed the epithelial‐mesenchymal transition to varying degrees. Together, these results indicated that a sustained hypoxic microenvironment after RFA may exert a negative impact on the prognosis of HCC patients, and minimizing exposure to a hypoxic microenvironment and targeting HIF‐1α signaling might be effective strategies for patients who experience insufficient RFA therapy.     

Fibroblast growth factor-2, derived from cancer-associated fibroblasts,stimulates growth and progression of human breast cancer cells via FGFR1 signaling

Cancer-associated fibroblasts (CAFs) constitute a major compartment of the tumor microenvironment. In the present study, we investigated the role for CAFs in breast cancer progression and underlying molecular mechanisms. Human breast cancer MDA-MB-231 cells treated with the CAF-conditioned media manifested a more proliferative phenotype, as evidenced by enhanced messenger RNA (mRNA) expression of Cyclin D1, c-Myc, and proliferating cell nuclear antigen. Analysis of data from The Cancer Genome Atlas revealed that fibroblast growth factor-2 (FGF2) expression was well correlated with the presence of CAFs. We noticed that the mRNA level of FGF2 in CAFs was higher than that in normal fibroblasts. FGF2 exerts its biological effects through interaction with FGF receptor 1 (FGFR1). In the breast cancer tissue array, 42% estrogen receptor-negative patients coexpressed FGF2 and FGFR1, whereas only 19% estrogen receptor-positive patients exhibited coexpression. CAF-stimulated MDA-MB-231 cell migration and invasiveness were abolished when FGF2-neutralizing antibody was added to the conditioned media of CAFs. In a xenograft mouse model, coinjection of MDA-MB-231 cells with activated fibroblasts expressing FGF2 dramatically enhanced tumor growth, and this was abrogated by silencing of FGFR1 in cancer cells. In addition, treatment of MDA-MB-231 cells with FGF2 enhanced expression of Cyclin D1, a key molecule involved in cell cycle progression. FGF2-induced cell migration and upregulation of Cyclin D1 were abolished by siRNA-mediated FGFR1 silencing. Taken together, the above findings suggest that CAFs promote growth, migration and invasion of MDA-MB-231 cells via the paracrine FGF2-FGFR1 loop in the breast tumor microenvironment.     

HIF-1α 对人肝癌Hep G2细胞生长的影响

 目的 研究缺氧诱导因子-1α(HIF-1α)对人肝癌细胞株HepG₂体内生长的影响，并探讨其可能机制。方法 将HIF-1α转入人肝癌细胞HepG₂中，建立人肝癌裸鼠模型，观察其生长。切除瘤灶、称瘤重。标本用免疫组化和Western-blot检测HIF-1α和血管内皮生长因子(VEGF)蛋白的表达。结果 HepG₂细胞对HIF-1α敏感，细胞生长速度加快。结论 HIF-1α体内可促进肝癌HepG₂的生长，其机制可能与其促血管生成有关。     

NF-κBp65对人非霍奇金淋巴瘤细胞HIF-1α-VEGF途径调节及其机制的探讨

目的:研究NF-κB对人非霍奇金淋巴瘤(NHL)HIF-1α-VEGF途径的调控及其机制。方法:应用Echinomycin(EC)处理人NHL细胞,将HIF-1α反义质粒转染至肿瘤细胞中,采用蛋白质印迹法检测经两种方法处理后各细胞系中VEGF表达水平。以NF-κB特异性抑制剂quinazoline(QNZ)及Bay11-7082预处理人NHL细胞,检测各细胞系中HIF-1α蛋白的表达水平,同时采用实时定量PCR方法检测HIF-1αmRNA变化。应用QNZ处理NHL细胞后检测HIF-1α下游调控靶点VEGF的蛋白表达水平。结果:通过应用HIF-1α特异性抑制剂和转染反义质粒两种方法均能够抑制HIF-1α,明显下调了VEGF蛋白表达水平,与对照组相比差异均有统计学意义,P<0.05。NF-κB抑制剂QNZ及Bay11-7082能够降低NHL细胞HIF-1α蛋白及基因水平的表达,同时下调其下游调控靶点VEGF蛋白的表达,P<0.05。结论:抑制NF-κB可阻断人NHL细胞HIF-1α-VEGF通路,其机制可能与NF-κB调控HIF-1α的基因与蛋白表达有关。     

肠癌小鼠高血糖下的血清胰岛素样生长因子-1变化及瘤体血管内皮生长因子表达

 目的　观察小鼠肠癌移植瘤在高血糖下的生长并检测瘤体血管内皮生长因子（VEGF）表达以及血清胰岛素样生长因子-1（IGF-1）的变化情况,探讨2型糖尿病（T2DM）是否为促进结直肠癌的发生与进展的危险因素。方法　建立肠癌移植瘤合并T2DM的小鼠模型,观察移植瘤体积大小变化,5周末处死小鼠检测血清IGF-1及瘤体组织VEGF表达。结果　肠癌糖尿病组小鼠瘤体体积[（1628.5±882）mm3]大于肠癌组小鼠瘤体体积[（1950.2±726）mm3]（P＜0.05）,其血清IGF-1[（105.33±32.32）ng／ml]高于正常组[（69.83±25.57）ng／ml]及肠癌组小鼠[（70.17±25.27）ng／ml]（P＜0.05）,瘤体组织VEGF表达[（70.0±11.5）%]强于肠癌组[（42.9±7.5）%]（P＜0.05）。结论　T2DM可能为促进肠癌生长的原因之一,其可能机制与血液中升高的IGF-1作用有关,并通过诱导VEGF基因转录,上调VEGF的表达,促使肿瘤组织血管生成,从而导致肿瘤的发生和转移有关。     

Role of the Tumor Microenvironment in Mediating Response to Anti-angiogenic Therapy

Despite the development of innovative anti-angiogenic strategies, early clinical trials have not replicated the results observed from preclinical models. One reason for this apparent discrepancy is the fact that tumor endothelium is phenotypically distinct from normal tissue endothelium. Moreover, it has recently become apparent that each individual tumor may display a different angiogenic phenotype. The expression of angiogenic factors in tumors is controlled by both intrinsic factors in the tumor cell and the influence of the host microenvironment. The diversity of angiogenic factor expression in tumors growing at different sites, combined with the fact that endothelial cells in different organs and tumors are phenotypically distinct, constitutes a formidable challenge for the development of effective anti-angiogenic regimens. This review provides an overview of how the microenvironment regulates tumor angiogenesis and affects the efficacy of anti-angiogenic therapy.