VEGF directly suppresses activation of T cells from ascites secondary to ovarian cancer via VEGF receptor type 2

Background:

Vascular endothelial growth factor action in tumour angiogenesis is well characterised; nevertheless, it functions as a key element in the promotion of the immune system''s evasion by tumours. We sought to investigate the possible direct effect of VEGF on T-cell activation and through which type of VEGF receptor it exerts this effect on cells isolated from ovarian cancer patients'' ascites.

Methods:

T cells isolated from the ascites of ovarian cancer patients were cultured with anti-CD3 and IL-2, with or without VEGF for 14 days and the number of viable T cells was counted. Cytotoxic activity of cultured T cells and expression of VEGF receptor-2 (VEGFR-2), was assayed.

Results:

The addition of VEGF in cultures significantly reduced the number and proliferation rate of T cells in a dose-dependent manner and CD3⁺ T cells expressed VEGFR-2 on their surface upon activation. Experiments with specific anti-VEGFR-2 antibodies revealed that the direct suppressive effect of VEGF on T-cell proliferation is mediated by VEGFR-2. We also showed that VEGF significantly reduced the cytotoxic activity of T cells.

Conclusion:

Our study showed that ascites-derived T cells secrete VEGF and express VEGFR-2 upon activation. Vascular endothelial growth factor directly suppresses T-cell activation via VEGFR-2.     

Up‐regulation of proliferative and migratory genes in regulatory T cells from patients with metastatic castration‐resistant prostate cancer

A higher frequency of regulatory T cells (Tregs) has been observed in peripheral blood mononuclear cells (PBMC) of patients with different types of solid tumors and hematological malignancies as compared to healthy donors. In prostate cancer patients, Tregs in PBMC have been shown to have increased suppressive function. Tumor‐induced biological changes in Tregs may enable tumor cells to escape immunosurveillance. We performed genome‐wide expression analyses comparing the expression levels of more than 38,500 genes in Tregs with similar suppressive activity, isolated from the peripheral blood of healthy donors and patients with metastatic castration‐resistant prostate cancer (mCRPC). The differentially expressed genes in mCRPC Tregs are involved in cell cycle processes, cellular growth and proliferation, immune responses, hematological system development and function and the interleukin‐2 (IL‐2) and transforming growth factor‐β (TGF‐β) pathways. Studies revealed that the levels of expression of genes responsible for T‐cell proliferation (C‐FOS, C‐JUN and DUSP1) and cellular migration (RGS1) were greater in Tregs from mCRPC patients as compared to values observed in healthy donors. Increased RGS1 expression in Tregs from mCRPC patients suggests a decrease in these Tregs' migratory ability. In addition, the higher frequency of CD4⁺CD25^highCD127^– Tregs in the peripheral blood of mCRPC patients may be the result of an increase in Treg proliferation capacity. Results also suggest that the alterations observed in gene expression profiles of Tregs in mCRPC patients may be part of the mechanism of tumor escape from host immune surveillance.     

Isolation and purification of vascular endothelial growth factor (VEGF) from ascitic fluid of ovarian cancer patients

Vascular Endothelial Growth Factor (VEGF) or Vascular Permeability Factor (VPF) is an angiogenic cytokine expressed by many human and animal tumors. Because of the importance of VEGF in animal tumors, we purified VEGF/VPF from ascitic fluid of ovarian cancer patients with heparin sepharose column. The purified protein gave protein bands of 37 and 26 kD, respectively in 12% SDS PAGE. The specificity of the purified protein was determined with dot blot, trans-immunoblot and ELISA using polyclonal goat anti-VEGF antibody (Santa Cruz Biotechnology). The vasodilatatory effect of the purified protein was confirmed by a vascular permeability assay on mouse. A polyclonal mouse antibody was raised against the purified protein, which recognized the same protein by ELISA, transimmunoblot and dot-blot analysis. It has been also found that the raised polyclonal antibody in mouse- and the commercial VEGF polyclonal antibody (Santa Cruz Biotechnology) both inhibited in vitrocell proliferation of human MCF-7 cell line. This study shows for the first time an effort to purify VEGF from human source.(Pathology Oncology Research Vol 10, No 2, 104–108)     

Induction of cytotoxic T lymphocytes against ovarian cancer-initiating cells

The majority of patients with stage III/IV ovarian carcinoma that respond initially to standard therapies ultimately undergo relapse due to the survival of small populations of cells with tumor-initiating potential. These ovarian cancer (OVCA)-initiating cells (OCIC) are sometimes called cancer stem cells (CSC) because they express stem cell markers, and can survive conventional therapies such as chemotherapy, which usually target rapidly replicating tumor cells, and give rise to recurrent tumors that are more chemo-resistant and more aggressive. Thus, it would be desirable to develop a therapy that could selectively target OCIC and be used to complement the conventional therapies. In this study, we isolated a subset of OVCA cells with a CD44(+) phenotype in samples from patients with OVCA that possess CSC properties including the formation of spheroids in culture, self-renewal and the ability to be engrafted in immune-compromised mice. We next explored the use of immunotherapy using fusions of dendritic cells and OCIC to specifically target the OCIC subpopulations. Fusion cells (FCs) prepared in this way activated T cells to express elevated levels of IFN-γ with enhanced killing of CD44(+) OVCA cells. We envision a combined approach where conventional therapies such as chemotherapy kill the bulk of tumor cells, whereas OCIC-reactive cytotoxic T lymphocytes target the resistant OCIC fraction. A combined therapy such as this may represent a promising approach for the treatment of OVCA.     

CTGF、VEGF在卵巢癌中的表达及临床意义

目的 研究结缔组织生长因子(CTGF)、血管内皮生长因子(VEGF)的表达在卵巢癌发生、发展中的作用及临床意义.方法 采用免疫组化法检测92例卵巢癌组织和11例正常卵巢组织中CTGF和VEGF的表达,比较CTGF、VEGF在卵巢癌中表达的关系,并分析其在卵巢癌发生、发展中的临床意义及对预后的影响.结果CTGF在卵巢癌组织中的阳性表达率为19.6%,明显低于正常卵巢组织的81.8%(P﹤0.001);VEGF在卵巢癌组织中的表达率为89.1%,明显高于正常卵巢组织的27.3%(P﹤0.001).CTGF的阴性表达与卵巢癌患者的FIGO分期及淋巴结转移有关(P﹤0.05),但与患者的年龄及病理分级无关(P﹥0.05);VEGF的阳性表达与卵巢癌患者的淋巴结转移有关(P﹤0.05),但与患者的年龄、病理分级及FIGO分期无关(P﹥0.05).CTGF与VEGF在卵巢癌组织中的表达呈负相关(r=-0.444,P﹤0.05).结论 CTGF和VEGF的表达可能与卵巢癌的发生、发展及预后密切相关.     

Evaluation of circulating endothelial cells, VEGF and VEGFR2 serum levels in patients with chronic myeloproliferative diseases

Authors evaluated some markers of angiogenetic activity in patients with chronic myeloproliferative diseases (CMDs). In this study by using a cytofluorimetric analysis we evaluated circulating endothelial progenitor cells (EPCs) in patients with chronic myeloproliferative disease. Moreover, in the same group of subjects, we evaluated serum levels of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR2). In our patients, we have found an increase in the number of endothelial progenitor cells in primary myelofibrosis (PMF) and polycythaemia vera (PV) patients, while an increase of circulating endothelial cells (CECs) was found in all patients with CMD. Moreover, we found higher serum levels of VEGF with respect to control subjects in every group of patients with CMD, and a not significant reduction of VEGFR2 levels in essential thrombocythaemia (ET) patients. A correlation was also found in PV patients between VEGF levels and erythrocyte number and in PMF subjects with the count of white cells. Our data suggest that some markers of angiogenesis are activated in CMD patients and angiogenesis may have a role in the pathophysiology of chronic myeloproliferative disorders.     

三氧化二砷对人卵巢癌SKOV3细胞VEGF表达的影响

目的：从转录及翻译两个水平观察As2O3对卵巢癌SKOV3细胞VEGF表达的影响,从而明确As2O3是否可以通过抑制卵巢癌细胞表达VEGF而达到抗卵巢癌血管生成的目的。方法：RT-PCR半定量法测定不同浓度As2O3作用于SKOV3细胞24h后VEGF mRNA含量的变化。用ELISA法测定不同浓度和作用时间下As2O3对SKOV3细胞培养上清液中VEGF蛋白表达的影响。结果：1μmol/L-4μmol/L As2O3能显著抑制VEGF mRNA的表达,且具有浓度依赖性。1μmol/L-4μmol/L As2O3能明显降低培养上清中VEGF蛋白表达,具有浓度依赖性,但随时间延长抑制作用减弱。结论：As2O3能通过降低卵巢癌SKOV3细胞VEGF mRNA表达及VEGF蛋白分泌抑制肿瘤血管生成。     

Functional significance of VEGFR‐2 on ovarian cancer cells

Vascular endothelial growth factor receptor (VEGFR) has recently been discovered on ovarian cancer cells, but its functional significance is unknown and is the focus of this study. By protein analysis, A2780‐par and HeyA8 ovarian cancer cell lines expressed VEGFR‐1 and HeyA8 A2774, and SKOV3ip1 expressed VEGFR‐2. By in situ hybridization (ISH), 85% of human ovarian cancer specimens showed moderate to high VEGFR‐2 expression, whereas only 15% showed moderate to high VEGFR‐1 expression. By immunofluorescence, little or no VEGFR‐2 was detected in normal ovarian surface epithelial cells, whereas expression was detected in 75% of invasive ovarian cancer specimens. To differentiate between the effects of tumor versus host expression of VEGFR, nude mice were injected with SKOV3ip1 cells and treated with either human VEGFR‐2 specific antibody (1121B), murine VEGFR‐2 specific antibody (DC101) or the combination. Treatment with 1121B reduced SKOV3ip1 cell migration by 68% (p < 0.01) and invasion by 72% (p < 0.01), but exposure to VEGFR‐1 antibody had no effect. Treatment with 1121B effectively blocked VEGF‐induced phosphorylation of p130Cas. In vivo treatment with either DC101 or 1121B significantly reduced tumor growth alone and in combination in the SKOV3ip1 and A2774 models. Decreased tumor burden after treatment with DC101 or 1121B correlated with increased tumor cell apoptosis, decreased proliferative index, and decreased microvessel density. These effects were significantly greater in the combination group (p < 0.001). We show functionally active VEGFR‐2 is present on most ovarian cancer cells. The observed anti‐tumor activity of VEGF‐targeted therapies may be mediated by both anti‐angiogenic and direct anti‐tumor effects. © 2008 Wiley‐Liss, Inc.     

上皮源性卵巢癌干细胞的研究进展

肿瘤干细胞(cancer stem cells,CSCs)是肿瘤组织内具有自我更新能力以及无限增殖和多向分化潜能的一群细胞,对化疗药物耐受.卵巢癌干细胞(epithelial ovarian cancer stem cells,EOCSCs)在卵巢癌的发生发展、侵袭转移和耐药复发过程中都起到了重要作用.传统的肿瘤细胞减灭术联合顺铂、紫杉醇全身化疗对减小肿瘤体积,缓解临床症状具有一定的作用,但治疗后残留的EOCSCs能够短时间内重建肿瘤组织,是卵巢癌复发和难治的根本原因.深入了解EOCSCs的生物学特性,探索EOCSCs的发生发展机制,研究针对EOCSCs的靶向治疗药物,是抗肿瘤治疗的关键.     

Matrilysin (MMP-7) promotes invasion of ovarian cancer cells by activation of progelatinase

Although matrilysin (MMP-7) is overexpressed in various malignancies, few studies have evaluated its role in epithelial ovarian cancer (EOC) invasion and metastasis. We report that the secretion of MMP-7 in EOC is stimulated significantly by vascular endothelial growth factor (VEGF) and interlukin-8 (IL-8). We also examined the in vivo expression of MMP-7 in EOC and its effects on the in vitro invasion and progelatinase activation. We report that MMP-7 is overexpressed in ovarian cancer cell lines and EOC surgical specimens. DOV13 cells incubated with active rhMMP-7 significantly increased cellular invasion and proMMP-2 activation. RhMMP-7 also showed the ability to activate proMMP-2 and proMMP-9 in immortalized ovarian epithelial cell (IOSE-29) conditioned medium. In addition, rhMMP-7 was able to activate progelatinase in a concentration-dependent manner in vitro. TIMP-2 or the generic MMP inhibitor-GM6001 inhibited both the activation of proMMP-2 and the increased invasion of DOV13 cells promoted by rhMMP-7. By incubation of MMP2-TIMP-2 complex with equal molar rhMMP-7, MMP-2 was dissociated from the complex and activated in a time-dependent manner, suggesting that TIMP-2 helps to keep the latency of MMP-2. TIMP-2 also showed inhibitory effects on the MMP-7 induced increase of gelatinolytic activity in DOV13 and IOSE-29 conditioned media. A strong co-localization of MMP-7 and MMP-2 was observed in DOV13 cells and ovarian carcinoma permanent tissue sections. These results indicate MMP-7 is overexpressed in malignant ovarian epithelium and suggest MMP-7 may facilitate tumor cell invasion in vivo partly through the induction of progelatinase activation.     

上皮性卵巢癌患者血清可溶性白细胞介素-2受体、人附睾蛋白4、T淋巴细胞亚群水平及临床意义

目的探讨上皮性卵巢癌患者的血清可溶性白细胞介素-2受体(SIL-2R)、人附睾蛋白4(HE4)、T淋巴细胞亚群水平及临床意义。方法选择100例上皮性卵巢癌患者和100例卵巢良性肿瘤患者,分别作为观察组和对照组,比较两组患者的血清SIL-2R、HE4及T淋巴细胞亚群(CD3⁺、CD4⁺、CD8⁺和CD4⁺/CD8⁺)水平,分析不同临床特征上皮性卵巢癌患者的血清SIL-2R、HE4及T淋巴细胞亚群水平。结果观察组患者的血清SIL-2R、HE4水平均明显高于对照组,差异均有统计学意义(P﹤0.01)。观察组患者的血清CD3⁺、CD4⁺水平及CD4⁺/CD8⁺均明显低于对照组,CD8⁺水平明显高于对照组,差异均有统计学意义(P﹤0.01)。临床分期为Ⅲ~Ⅳ期、中/低分化、有腹腔积液的上皮性卵巢癌患者的血清SIL-2R、HE4水平分别高于临床分期为Ⅰ~Ⅱ期、高分化、无腹腔积液的患者,差异均有统计学意义(P﹤0.01)。中/低分化、有淋巴结转移、有腹腔积液上皮性卵巢癌患者的血清CD3⁺、CD4⁺水平分别低于高分化、无淋巴结转移、无腹腔积液的患者,CD8⁺水平分别高于高分化、无淋巴结转移、无腹腔积液的患者,差异均有统计学意义(P﹤0.05)。上皮性卵巢癌患者的血清SIL-2R、HE4水平与CD3⁺、CD4⁺、CD4⁺/CD8⁺均呈负相关(P﹤0.05),与CD8⁺呈正相关(P﹤0.05)。结论上皮性卵巢癌患者血清中SIL-2R、HE4水平均较高,T淋巴细胞亚群CD3⁺、CD4⁺水平及CD4⁺/CD8⁺均较低,SIL-2R、HE4水平与T淋巴细胞亚群之间具有相关性。     

人反义VEGF基因表达载体的构建及其对卵巢癌细胞增殖的影响

目的：构建人反义VEGF基因真核表达载体,进行抗血管生成治疗卵巢癌实验。方法：RT－PCR法获得人VEGF基因,将VEGF基因反向克隆入真核表达载体pcDNA3中,酶切鉴定结果。用此真核表达载体转染人卵巢癌细胞HO－8910,G418筛选获得阳性克隆,RNA斑点杂交鉴定HO－8910细胞中VEGF表达。Western blot及间接免疫荧光法检测转染前后HO－8910 细胞中VEGF蛋白表达。检测转染前后瘤细胞的生物学性状及裸鼠体内致瘤性。结果：RT－PCR法得到VEGF基因,并获得反向构建的VEGF真核表达载体。VEGF反义RNA部分阻断了HO－8910细胞中VEGF表达,转染后单个细胞的克隆形成能力明显减弱;细胞周期中,G1期细胞增多,S期细胞减少,细胞增殖能力降低;形态学超微结构显示细胞器扩张和肿胀,核染色质边集,凝集成块,可见明显的凋亡改变。裸鼠体内致瘤性降低。结论：成功构建了反义VEGF基因真核表达载体,该载体可明显抑制卵巢癌细胞增殖,为卵巢癌的基因治疗提供了一定的实验依据。     

Hospicells derived from ovarian cancer stroma inhibit T‐cell immune responses

With metastatic disease at diagnosis for 70% of patients, ovarian cancer represents the most lethal gynecological malignancy. Ovarian carcinomas are aggressive malignancies that can evade immune surveillance and frequently develop into metastases. The tumor microenvironment is decisive for preventing immune attack but, in the case of ovarian carcinoma, the mechanisms are unclear. We recently isolated a novel type of stromal cell from the ascitis of patients with ovarian carcinoma that interacts with epithelial ovarian cancers conferring them chemoresistance. These cells, called Hospicells, have the cell surface markers CD9, CD10, CD29, CD146 and CD166. Here, we investigated whether Hospicells also have immunomodulatory functions that might interfere with immunity to cancer. We report that Hospicells inhibit the proliferation of human CD4⁺, CD8⁺ and Vγ9Vδ2 T cells in vitro and the production of cytokines by these immune cells. The immunosuppression of CD4⁺ T cells is independent of direct contact with the Hospicells and is mainly due to nitric oxide produced by the inducible nitric oxide synthase and to products of the tryptophan degradation by indoleamine 2,3‐dioxygenase. We proposed that Hospicells in the microenvironment of the tumor mediate immunosuppression of T cells and thus allow ovarian cancers to evade immune surveillance. Targeting of Hospicells could be an alternative to strong chemotherapy through the recovery of immune responses against tumor cells.     

NK depletion results in increased CCL22 secretion and Treg levels in Lewis Lung Carcinoma via the accumulation of CCL22‐secreting CD11b+CD11c+ cells

Tumor‐induced immune suppression involves the accumulation of suppressive infiltrates in the tumor microenvironment such as regulatory T‐cells (Tregs). Previous studies demonstrated that NK‐dependant increases in CCL22 secretion selectively recruit Tregs toward murine lungs bearing Lewis Lung Carcinoma (LLC). To extend the in vitro studies, the present studies utilized in vivo depletion of NK cells to ascertain the contribution of NK‐derived CCL22 toward total CCL22 and subsequent Treg levels in both normal and LLC‐bearing lungs. However, NK depletion had the unexpected effect of increasing both CCL22 secretion and Treg levels in the lungs of NK‐depleted LLC‐bearing mice. This was concurrent with an increase in tumor burden. Flow cytometry and a series of both immunomagnetic and FACS isolations were used to identify the CCL22‐producing cellular fractions in LLC‐bearing lungs. A novel CD11b⁺CD11c⁺ cell population was identified that accumulates in large numbers in NK‐depleted LLC‐bearing lung tissue. These CD11b⁺CD11c⁺ cells secreted large amounts of CCL22 that may overcompensate for the loss of NK‐derived CCL22 in the lungs of NK‐depleted LLC‐bearing mice. Taken together, these data suggest that NK cells play both a positive and negative role in the regulation of CCL22 secretion and, in turn, the recruitment of Tregs toward LLC‐bearing lungs.     

卵巢癌患者外周血来源树突细胞的生物学特性

背景与目的：树突细胞（dendritic cells,DCs）是体内功能最强的抗原递呈细胞．在抗肿瘤免疫治疗中起着重要的作用。既往对DCs生物学特性的研究数据大多来自健康个体,而来自肿瘤患者的DCs的特性尚不清楚。本研究旨在探讨卵巢癌患者外周血单核细胞来源的树突细胞（monocyte—derived dendritic cells,MoDCs）的生物学特性。方法：收集8名上皮性卵巢癌患者及13名健康女性志愿者的外周静脉血标本,从中分离出单核细胞,将其置于含人白细胞介素4（interleukin4,IL4）及粒细胞．巨噬细胞集落刺激因子（granulocyte-macrophag ecolony stimulating factor,GM-CSF）的RPMI-1640完全培养基中培养,用肿瘤坏死因子-α（tumornecrosisfactor-α,TNF-α）刺激其成熟。对诱导7d后的MoDCs进行细胞形态、表型及刺激异体淋巴细胞增殖能力分析。结果：卵巢癌患者及健康妇女外周血单核细胞培养7d后,均诱导出形态学上典型的成熟MoDCs。两组MoDCs均表达丰富的HLA-ABC（MHC-Ⅰ）、HLA-DR（MHC-Ⅱ）和大量共刺激分子CD86和CD80。卵巢癌组HLA-ABC、HLA-DR、CD86及CD80的平均荧光强度（mean fluorescence intensity,MFI）与健康妇女组差异无统计学意义（P〉0．05）。混合淋巴细胞反应（mixed leukocytes reaction,MLR）结果显示,卵巢癌各组（按MoDCs与淋巴细胞的比例分组）的吸光度值均明显低于健康妇女相应各比例组（P〈0．05）。结论：卵巢癌患者的MoDCs刺激异体淋巴细胞增殖能力较健康妇女降低,提示其存在一定程度的免疫学功能异常。     

Understanding dendritic cell immunotherapy in ovarian cancer

Introduction: Approximately eighty percent of patients with ovarian cancer are diagnosed with advanced disease. Even with cutting edge surgical techniques and the best regimens of standard therapies most patients relapse and die of drug resistant disease within five years of diagnosis. Dendritic cell (DC) immunotherapy can induce anti-tumor T cell immunity in patients and holds great potential in the era of modern anti-cancer treatment.

Areas Covered: This review outlines critical factors regulating the outcome of DC immunotherapy in ovarian cancer, summarizes the important findings in ovarian cancer DC clinical trials, and discusses new directions which may improve the effectiveness of DC immunotherapy.

Expert Commentary: Administration of DC vaccines with other forms of immunotherapy may enhance the efficacy of these treatments, ultimately increasing cures for this disease.     

人卵巢癌细胞系干/祖细胞分离及其鉴定

目的:自人卵巢癌细胞系SK-OV-3中分离干/祖细胞并进行鉴定。方法:采用无血清球形体形成法从SKOV-3中分离培养卵巢癌干/祖细胞;采用实时定量PCR和蛋折质印迹法测定球形体细胞干/祖细胞相关标志ABCG2、Oct-4、Nanog基因和蛋白的表达;流式细胞仪检测其耐药性;双层软琼脂检测其克隆形成能力;NOD/SCID小鼠检测其体内致瘤性。结果:球形体细胞表达干/祖细胞相关标志Oct-4、ABCG2、Nanog;对顺铂高耐药;在双层软琼脂上克隆形成率达(13.67±1.48)%;1 000个球形体形成细胞就能在NOD/SCID鼠中成瘤。结论:采用无血清培养基中球形体形成法从SKOV-3细胞系中可以分离出具有干/祖特性的卵巢癌细胞,可为今后研究卵巢癌的发生、发展、复发及其化疗药物筛选提供简便实用的体外模型。     

胃癌患者血清VEGF、COX-2表达的检测及临床意义

目的：检测胃癌患者血清中血管内皮生长因子（VEGF）、环氧合酶2（COX-2）的表达水平,探讨二者相关性及临床意义.方法：采用酶联免疫吸附试验（ELISA法）定量检测60例胃癌患者和30例健康人血清VEGF和COX-2水平.比较胃癌患者与健康人血清VEGF、COX-2浓度的差异.同时比较不同分期肿瘤患者血清VEGF、COX-2浓度的差异,并进行二者相关性分析.结果：胃癌患者血清VEGF水平（424.07±81.85pg/ml）明显高于健康人（117.23±20.09pg/ml） （P ＜0.01）.其水平与肿瘤大小、浸润深度、分化程度、有无转移、TNM分期有关（P＜0.05）.血清COX-2水平（41.43±9.52ng/ml）也明显高于健康人（16.88±6.27ng/ml）（P＜0.05）.其含量与胃癌分化程度、有无转移、TNM分期有关（P＜0.05）.二者的表达呈显著正相关（r=0.618,P＜0.01）.结论：胃癌患者血清中VEGF和COX-2高表达,其表达水平与肿瘤的分期相关,提示VEGF和COX-2在胃癌的发生和发展中发挥重要的作用.二者密切相关,在胃癌的诊断、治疗和预后评价中具有一定价值.