PM2.5引起的肿瘤新生血管形成和转移研究进展

 PM_2.5指直径≤2.5 μm 的颗粒物质,它很容易穿过呼吸道屏障,进入血液循环,可诱发肺癌等多种恶性肿瘤,已成为恶性肿瘤新的诱因。近年研究揭示,PM_2.5可刺激肿瘤细胞合成和分泌血管内皮生长因子（VEGF）,促进血管内皮细胞介导的肿瘤血管新生;并可激活肿瘤细胞,使其通过血管生成拟态直接形成肿瘤血管;还能使肿瘤干细胞向肿瘤内皮细胞转化,促进肿瘤新生血管形成。此外,PM_2.5可促进肿瘤细胞及其他多种细胞分泌趋化因子和白细胞介素,招募骨髓和血液中白细胞进入肿瘤组织,诱发局部慢性炎症反应,诱导上皮细胞-间充质细胞转化（EMT）的发生,增加肿瘤细胞干性、迁移和转移能力;还可破坏血管稳态,增加血管通透性,为肿瘤细胞的转移打开方便之门。PM_2.5在肿瘤的新生血管形成和转移中起了重要作用,然而,至今对其作用机制知之甚少。因此,进一步深入研究PM_2.5诱导的肿瘤新生血管形成及转移机制,能为PM_2.5引起的恶性肿瘤防治提供可靠的理论依据和新的应对策略。     

Blocking VEGFR-3 suppresses angiogenic sprouting and vascular network formation

Angiogenesis, the growth of new blood vessels from pre-existing vasculature, is a key process in several pathological conditions, including tumour growth and age-related macular degeneration. Vascular endothelial growth factors (VEGFs) stimulate angiogenesis and lymphangiogenesis by activating VEGF receptor (VEGFR) tyrosine kinases in endothelial cells. VEGFR-3 (also known as FLT-4) is present in all endothelia during development, and in the adult it becomes restricted to the lymphatic endothelium. However, VEGFR-3 is upregulated in the microvasculature of tumours and wounds. Here we demonstrate that VEGFR-3 is highly expressed in angiogenic sprouts, and genetic targeting of VEGFR-3 or blocking of VEGFR-3 signalling with monoclonal antibodies results in decreased sprouting, vascular density, vessel branching and endothelial cell proliferation in mouse angiogenesis models. Stimulation of VEGFR-3 augmented VEGF-induced angiogenesis and sustained angiogenesis even in the presence of VEGFR-2 (also known as KDR or FLK-1) inhibitors, whereas antibodies against VEGFR-3 and VEGFR-2 in combination resulted in additive inhibition of angiogenesis and tumour growth. Furthermore, genetic or pharmacological disruption of the Notch signalling pathway led to widespread endothelial VEGFR-3 expression and excessive sprouting, which was inhibited by blocking VEGFR-3 signals. Our results implicate VEGFR-3 as a regulator of vascular network formation. Targeting VEGFR-3 may provide additional efficacy for anti-angiogenic therapies, especially towards vessels that are resistant to VEGF or VEGFR-2 inhibitors.     

Molecular mechanisms and clinical applications of angiogenesis

Blood vessels deliver oxygen and nutrients to every part of the body, but also nourish diseases such as cancer. Over the past decade, our understanding of the molecular mechanisms of angiogenesis (blood vessel growth) has increased at an explosive rate and has led to the approval of anti-angiogenic drugs for cancer and eye diseases. So far, hundreds of thousands of patients have benefited from blockers of the angiogenic protein vascular endothelial growth factor, but limited efficacy and resistance remain outstanding problems. Recent preclinical and clinical studies have shown new molecular targets and principles, which may provide avenues for improving the therapeutic benefit from anti-angiogenic strategies.     

Role of FGF-2／FGFR signaling pathway in cancer and its signification in breast cancer

Fibroblast growth factor-2 (FGF-2) is a member of a large family of proteins that bind heparin and heparan sulfate and modulate the function of a wide range of cell types. It has been proved that FGF-2 stimulates the growth and development of new blood vessels (angiogenesis) that contribute to the pathogenesis of several diseases (i.e. cancer, atherosclerosis). However, many of the biological activities of FGF-2 have been found to depend on its receptor抯 intrinsic tyrosine kinase activity and second messengers such as the mitogen activated protein kinases. This review will focus on the mechanism of FGF-2/FGFR induced signaling pathway in tumor and human breast cancer.     

超声造影观察小鼠两种皮下移植瘤的血管生成

目的 应用高频小动物超声观察人 BT-B 膀胱癌和人 Huh7 肝癌两种皮下移植瘤的血管生成情况,探讨超声 造影评价肿瘤血管生成情况的价值。 方法 采用皮下注射建立人 BT-B 膀胱癌和人 Huh7 肝癌两种皮下移植瘤模 型,采用高频小动物超声成像系统的多种超声模式观察两种肿瘤内部结构和血管特性;采用探头式活体激光共聚 焦观察肿瘤的小血管数量和大小;采用免疫组化法观察肿瘤的血管标志物 CD31 表达,计算微血管密度。 结果 两 组裸鼠均成功荷瘤。 B 超模式显示 Huh7 与 BT-B 皮下瘤均为不均质低回声结节;彩色多普勒模式及频谱多普勒模 式显示 BT-B 皮下瘤血流信号和血流速度多于 Huh7 皮下瘤;超声造影显示 Huh7 肝癌组血管分布紊乱,BT-B 膀胱 癌组血管分布呈“分支状” ,与探头式活体激光共聚焦结果及病理结果一致。 超声造影参数峰值强度( PI) 与 MVD 呈正相关( r = 0. 844,P<0. 05) 。 结论 超声造影可以更好地显示肿瘤血管的分布情况,且 PI 与病理 MVD 呈正相 关,可提示肿瘤血管的增殖情况,可以作为无创评价肿瘤血管生成的可靠方法。     

软骨血管生成抑制因子抑制血管生成及其抗肿瘤作用的研究

测定了小牛软骨血管生成抑制因子对血管内皮细胞细胞毒作用,对内皮细胞骨架系统及其运动迁移的抑制效应,对小鼠肿瘤生长的对抑制效应。     

A Hybrid Mathematical Model of Tumor-Induced Angiogenesis with Blood Perfusion

Angiogenesis, the growth of new blood vessel from existing ones, is a pivotal stage in cancer development,and is an important target for cancer therapy. We develop a hybrid mathematical model to understand the mechanisms behind tumor-induced angiogenesis. This model describes uptake of Tumor Angiogenic Factor（TAF）at extracellular level, uses partial differential equation to describe the evolution of endothelial cell density including TAF induced proliferation, chemotaxis to TAF, and haptotaxis to extracellular matrix. In addition we also consider the phenomenon of blood perfusion in the micro-vessels. The model produces sprout formation with realistic morphological and dynamical features, including the so-called brush border effect, the dendritic branching and fusing of the capillary sprouts forming a vessel network. The model also demonstrates the effects of individual mechanisms in tumor angiogenesis： Chemotaxis to TAF is the key driving mechanisms for the extension of sprout cell; endothelial proliferation is not absolutely necessary for sprout extension; haptotaxis to Extra Cellular Matrix（ECM） gradient provides additional guidance to sprout extension, suggesting potential targets for anti-angiogenic therapies.     

Expression and function of a new angiogenic factor AA98 target molecule at the maternal-embryonic boundary of rhesus monkey

The target molecule of monoclonal antibody AA98 (AA for short) is a new vascular endothelial cell related factor and plays a role in angiogenesis as indicated by the previous data. To investigate its role in angiogenesis and placentation in primate, we examined its expression in the implantation sites on D17, 19, 28 and 34 of gestation in rhesus monkey by immunohistochemistry and Western immunoblot. Western blot analysis showed that the primary antibody used in this study was specific for its epitope. AA protein was mainly expressed in small blood vessels and in some cytotrophoblast cells. The AA staining was found mainly in the endothelial cells and vascular small muscle. This observation supported the AA‘s role in angiogenesis. AA was spatio-temporarily expressed in cytotrophoblasts: weak in proliferating trophoblast within cell column and endovascular trophoblast, strong in trophoblastic subpopulation within the basal plate and vascular trophoblast; AA staining within the basal plate was down-regulated during early placentation. The shift of AA98 expression in extravillous trophoblasts suggestes a role of this new factor during the course of cytotrophoblast metastasis and spiral artery remodeling. The spatio-temporarily expression indicats that AA98 could be also used as a trophoblast cellular marker to characterize the acquisition of a vascular endothelial and invasive phenotype.     

血小板衍生生长因子PDGF与肿瘤血管生成的研究进展

血小板衍生生长因子（platelet-derived growth factor,PDGF）是由多种细胞产生的重要多肽生长因子,可促进结缔组织细胞（如血管内皮细胞、平滑肌细胞）增殖等。PDGF家族目前已知的有4个成员,即PDGF-A,B,C,D。具有生物活性的PDGF分子一般以二硫键连接的同源二聚体或异源二聚体形式组成。PDGF经其受体PDGFR（platelet-derived growth factor receptor,PDGFR）介导后产生相应的生物学效应。体内外研究证实PDGF与肿瘤血管生成密切相关,PDGF主要通过募集周细胞刺激肿瘤血管生成,且周细胞的募集有利于肿瘤血管的成熟、稳定和存活。靶向PDGF的抗血管生成药物已成为肿瘤血管生成抑制剂中新的重要成员。     

Tumour vascularization via endothelial differentiation of glioblastoma stem-like cells

Glioblastoma is a highly angiogenetic malignancy, the neoformed vessels of which are thought to arise by sprouting of pre-existing brain capillaries. The recent demonstration that a population of glioblastoma stem-like cells (GSCs) maintains glioblastomas indicates that the progeny of these cells may not be confined to the neural lineage. Normal neural stem cells are able to differentiate into functional endothelial cells. The connection between neural stem cells and the endothelial compartment seems to be critical in glioblastoma, where cancer stem cells closely interact with the vascular niche and promote angiogenesis through the release of vascular endothelial growth factor (VEGF) and stromal-derived factor 1 (refs 5-9). Here we show that a variable number (range 20-90%, mean 60.7%) of endothelial cells in glioblastoma carry the same genomic alteration as tumour cells, indicating that a significant portion of the vascular endothelium has a neoplastic origin. The vascular endothelium contained a subset of tumorigenic cells that produced highly vascularized anaplastic tumours with areas of vasculogenic mimicry in immunocompromised mice. In vitro culture of GSCs in endothelial conditions generated progeny with phenotypic and functional features of endothelial cells. Likewise, orthotopic or subcutaneous injection of GSCs in immunocompromised mice produced tumour xenografts, the vessels of which were primarily composed of human endothelial cells. Selective targeting of endothelial cells generated by GSCs in mouse xenografts resulted in tumour reduction and degeneration, indicating the functional relevance of the GSC-derived endothelial vessels. These findings describe a new mechanism for tumour vasculogenesis and may explain the presence of cancer-derived endothelial-like cells in several malignancies.     

Combretastatin B-1的化学合成及结构衍生化研究

近来,Combretastatin B-1（CB1）由于在抗肿瘤活性尤其在靶向恶性肿瘤血管的选择性方面引起了医学界广泛关注.该化合物提取自药用植物Combretum caffrum,其抑制肿瘤细胞生长,抑制血管生成和微管蛋白聚合方面的应用前景激发了人们对CB1化学合成的极大兴趣.CB1及其衍生物是一类具有广泛生物活性和良好应用前景的化合物,因此CB1的化学合成及结构衍生化研究显得极为重要.     

Oxidative stress induces angiogenesis by activating TLR2 with novel endogenous ligands

Reciprocity of inflammation, oxidative stress and neovascularization is emerging as an important mechanism underlying numerous processes from tissue healing and remodelling to cancer progression. Whereas the mechanism of hypoxia-driven angiogenesis is well understood, the link between inflammation-induced oxidation and de novo blood vessel growth remains obscure. Here we show that the end products of lipid oxidation, ω-(2-carboxyethyl)pyrrole (CEP) and other related pyrroles, are generated during inflammation and wound healing and accumulate at high levels in ageing tissues in mice and in highly vascularized tumours in both murine and human melanoma. The molecular patterns of carboxyalkylpyrroles are recognized by Toll-like receptor 2 (TLR2), but not TLR4 or scavenger receptors on endothelial cells, leading to an angiogenic response that is independent of vascular endothelial growth factor. CEP promoted angiogenesis in hindlimb ischaemia and wound healing models through MyD88-dependent TLR2 signalling. Neutralization of endogenous carboxyalkylpyrroles impaired wound healing and tissue revascularization and diminished tumour angiogenesis. Both TLR2 and MyD88 are required for CEP-induced stimulation of Rac1 and endothelial migration. Taken together, these findings establish a new function of TLR2 as a sensor of oxidation-associated molecular patterns, providing a key link connecting inflammation, oxidative stress, innate immunity and angiogenesis.     

A peptide fusion protein inhibits angiogenesis and tumor growth by blocking VEGF binding to KDR

Vascular endothelial growth factor (VEGF) binding to its tyrosine kinase receptors (KDR/FLK1, Flt-1) induces angiogenesis. In search of the peptides blocking VEGF binding to its receptor KDR/FLK1 to inhibit tumorangiogenesis and growth, we screened a phage display peptide library with KDR as target protein, and some candidate peptides were isolated. In this study, we cloned the DNA fragment coding the peptide K237 from the library, into a vector pQE42 to express fusion protein DHFR-K237 in E. coli M15. The affection of fusion protein DHFR-K237 on endothelial cell proliferation and angiogenesis was investigated. In vitro, DHFR-K237 could completely block VEGF binding to KDR and significantly inhibit the VEGF-mediated proliferation of the human vascular endothelial cells. In vivo, DHFR-K237 inhibited angiogenesis in chick embryo chorioallantoric membrane and tumor growth in nude mice. These results suggest that K237 is an effective antagonist of VEGF binding to KDR, and could be a potential agent for cancer biotherapy.     

Expression of vascular endothelial growth factor in rat uterus during peri-implantation

The first distinct mark of rodent implantation is the increased vascular permeability and significant angiogenesis at the sites of blastocyst implantation, but its mechanism is not clearly defined. Vascular endothelial growth factor (VEGF) is the key mediator for angiogenesis during embryogenesis and adult span and also serves as a vascular permeability factor. The aim of this study is to explore VEGF regulation mechanism and the possible role that VEGF plays in implantation by studying the VEGF expression and angiogenesis in the rat uterus during estrous cycle, ovarioectomized and peri-implantation stages usingin situ message RNA hybridization and confocal laser scanning techniques. The results indicated that VEGF was regulated by ovarian steroid hormones. VEGF expression before implantation was localized at luminal epithelium, shifted to stroma as implantation initiated and extensively located at the decidualizing stroma region after implantation. Bandeiraea simplicifolia-1 (BS-1) agglutinin and antibody against von Willebrand factor (vWF) were used to mark the endothelial cells and blood vessels. The results showed that the active angiogenesis occurred during the implantation process and this effect was probably mediated by VEGF. The results suggest that under the regulation of ovarian steroid hormones, VEGF plays an essential role in angiogenesis and increasing vascular permeability in endometrium, which are necessary for successful implantation.     

Macrophage-induced angiogenesis is mediated by tumour necrosis factor-alpha

Macrophages are important in the induction of new blood vessel growth during wound repair, inflammation and tumour growth. We show here that tumour necrosis factor-alpha (TNF-alpha), a secretory product of activated macrophages that is believed to mediate tumour cytotoxicity, is a potent inducer of new blood vessel growth (angiogenesis). In vivo, TNF-alpha induces capillary blood vessel formation in the rat cornea and the developing chick chorioallantoic membrane at very low doses. In vitro, TNF-alpha stimulates chemotaxis of bovine adrenal capillary endothelial cells and induces cultures of these cells grown on type-1 collagen gels to form capillary-tube-like structures. The angiogenic activity produced by activated murine peritoneal macrophages is completely neutralized by a polyclonal antibody to TNF-alpha, suggesting immunological features are common to TNF-alpha and the protein responsible for macrophage-derived angiogenic activity. In inflammation and wound repair, TNF-alpha could augment repair by stimulating new blood vessel growth; in tumours, TNF-alpha might both stimulate tumour development by promoting vessel growth and participate in tumour destruction by direct cytotoxicity.     

Dll4 signalling through Notch1 regulates formation of tip cells during angiogenesis

In sprouting angiogenesis, specialized endothelial tip cells lead the outgrowth of blood-vessel sprouts towards gradients of vascular endothelial growth factor (VEGF)-A. VEGF-A is also essential for the induction of endothelial tip cells, but it is not known how single tip cells are selected to lead each vessel sprout, and how tip-cell numbers are determined. Here we present evidence that delta-like 4 (Dll4)-Notch1 signalling regulates the formation of appropriate numbers of tip cells to control vessel sprouting and branching in the mouse retina. We show that inhibition of Notch signalling using gamma-secretase inhibitors, genetic inactivation of one allele of the endothelial Notch ligand Dll4, or endothelial-specific genetic deletion of Notch1, all promote increased numbers of tip cells. Conversely, activation of Notch by a soluble jagged1 peptide leads to fewer tip cells and vessel branches. Dll4 and reporters of Notch signalling are distributed in a mosaic pattern among endothelial cells of actively sprouting retinal vessels. At this location, Notch1-deleted endothelial cells preferentially assume tip-cell characteristics. Together, our results suggest that Dll4-Notch1 signalling between the endothelial cells within the angiogenic sprout serves to restrict tip-cell formation in response to VEGF, thereby establishing the adequate ratio between tip and stalk cells required for correct sprouting and branching patterns. This model offers an explanation for the dose-dependency and haploinsufficiency of the Dll4 gene, and indicates that modulators of Dll4 or Notch signalling, such as gamma-secretase inhibitors developed for Alzheimer's disease, might find usage as pharmacological regulators of angiogenesis.     

血管内皮生长因子与急性白血病骨髓的血管新生

目的:探讨血管内皮生长因子(VEGF)在急性白血病及其骨髓的新生血管之间的关系,为白血病的治疗寻找新的治疗方法。方法:查阅总结近15年来国内外相关文献,对VEGF的性质作用特点以及与急性白血病的关系进行综述。结果:白血病细胞表达较高的VEGF,VEGF促使血管生成和内皮细胞增生,白血病细胞与骨髓新生血管之间存在密切的关系。结论:抗VEGF和抗新生血管治疗有可能成为治疗急性白血病的新的思路和方法。     

Angiogenesis in life, disease and medicine

The growth of blood vessels (a process known as angiogenesis) is essential for organ growth and repair. An imbalance in this process contributes to numerous malignant, inflammatory, ischaemic, infectious and immune disorders. Recently, the first anti-angiogenic agents have been approved for the treatment of cancer and blindness. Angiogenesis research will probably change the face of medicine in the next decades, with more than 500 million people worldwide predicted to benefit from pro- or anti-angiogenesis treatments.     

WAVE2 is required for directed cell migration and cardiovascular development

WAVE2, a protein related to Wiskott-Aldrich syndrome protein, is crucial for Rac-induced membrane ruffling, which is important in cell motility. Cell movement is essential for morphogenesis, but it is unclear how cell movement is regulated or related to morphogenesis. Here we show the physiological functions of WAVE2 by disruption of the WAVE2 gene in mice. WAVE2 was expressed predominantly in vascular endothelial cells during embryogenesis. WAVE2-/- embryos showed haemorrhages and died at about embryonic day 10. Deficiency in WAVE2 had no significant effect on vasculogenesis, but it decreased sprouting and branching of endothelial cells from existing vessels during angiogenesis. In WAVE2-/- endothelial cells, cell polarity formed in response to vascular endothelial growth factor, but the formation of lamellipodia at leading edges and capillaries was severely impaired. These findings indicate that WAVE2-regulated actin reorganization might be required for proper cell movement and that a lack of functional WAVE2 impairs angiogenesis in vivo.     

A microRNA regulon that mediates endothelial recruitment and metastasis by cancer cells

Metastatic progression of cancer is a complex and clinically daunting process. We previously identified a set of human microRNAs (miRNAs) that robustly suppress breast cancer metastasis to lung and bone and which display expression levels that predict human metastasis. Although these findings revealed miRNAs as suppressors of cell-autonomous metastatic phenotypes, the roles of non-coding RNAs in non-cell-autonomous cancer progression processes remain unknown. Here we reveal that endogenous miR-126, an miRNA silenced in a variety of common human cancers, non-cell-autonomously regulates endothelial cell recruitment to metastatic breast cancer cells, in vitro and in vivo. It suppresses metastatic endothelial recruitment, metastatic angiogenesis and metastatic colonization through coordinate targeting of IGFBP2, PITPNC1 and MERTK--novel pro-angiogenic genes and biomarkers of human metastasis. Insulin-like growth factor binding protein 2 (IGFBP2) secreted by metastatic cells recruits endothelia by modulating IGF1-mediated activation of the IGF type-I receptor on endothelial cells; whereas c-Mer tyrosine kinase (MERTK) receptor cleaved from metastatic cells promotes endothelial recruitment by competitively antagonizing the binding of its ligand GAS6 to endothelial MERTK receptors. Co-injection of endothelial cells with breast cancer cells non-cell-autonomously rescues their miR-126-induced metastatic defect, revealing a novel and important role for endothelial interactions in metastatic initiation. Through loss-of-function and epistasis experiments, we delineate an miRNA regulatory network's individual components as novel and cell-extrinsic regulators of endothelial recruitment, angiogenesis and metastatic colonization. We also identify the IGFBP2/IGF1/IGF1R and GAS6/MERTK signalling pathways as regulators of cancer-mediated endothelial recruitment. Our work further reveals endothelial recruitment and endothelial interactions in the tumour microenvironment to be critical features of metastatic breast cancer.