GPC3的结构和功能及其在肝细胞癌诊治中的应用

磷脂酰肌醇蛋白聚糖3(glypican 3,GPC3)是磷脂酰肌醇蛋白聚糖家族的一员,它主要通过糖基磷脂酰肌醇(glycosylphosphatidylinositol,GPI)锚定在细胞膜外侧。在正常人的肝细胞、良性肝肿瘤和其他成熟体细胞表面几乎不能检测到它的存在,而在原发性肝细胞癌(hepatocellular carcinoma,HCC)呈现高表达。因此,GPC3可以作为标志物用以诊断HCC。此外,GPC3在血清和肝组织中过量表达的HCC病人往往预后较差。研究发现,GPC3主要通过激活经典的Wnt信号通路和其他一些通路来促进HCC的迁移和增殖。针对GPC3靶点的单克隆抗体、抗体偶联药物和对应的细胞疗法,可能成为临床治疗HCC的有力武器。     

磷脂酰肌醇 -3 激酶不直接调控PC12 细胞的分泌

磷脂酰肌醇-3激酶(PI3K)是磷脂酰肌醇代谢过程中一种重要的酶,通过其代谢产物参与了对多种细胞生理活动的调节,如囊泡运输、细胞骨架重组、细胞存活、吞噬作用、细胞凋亡等.为研究其对细胞分泌功能的作用,使用磷脂酰肌醇-3激酶家族的特异性抑制剂渥曼青霉素(wortmannin)阻断磷脂酰肌醇-3激酶的活性,以EGFP-2xFYVE融合蛋白与磷脂酰肌醇-3-磷酸(PtdIns-3-P)的结合为指征,使用荧光显微成像技术检测渥曼青霉素对磷脂酰肌醇-3激酶的抑制作用,采用膜片钳膜电容测量方法及光解钙离子释放技术检测渥曼青霉素对PC12细胞分泌功能的影响.实验结果表明,wortmannin阻断了磷脂酰肌醇-3激酶的活性,抑制了磷脂酰肌醇-3-磷酸(PtdIns-3-P)的产生,并使FYVE与PtdIns-3-P解离,但渥曼青霉素处理之前和处理30 min后的PC12细胞分泌反应的幅度、动力学特性和分泌的钙依赖性均无显著差异,表明磷脂酰肌醇-3激酶对PC12细胞的分泌无显著的直接影响.     

PIKfyve的生物学功能及与疾病的关系

含FYVE结构的磷酸肌醇3-磷酸5-激酶(FYVE domain-containing phosphatidylinositol 3-phosphate5-kinase,PIKfyve)是哺乳动物体内的一种磷脂酰肌醇脂质激酶。PIKfyve通过催化磷脂酰肌醇-3-磷酸[phosphatidylinositol 3-phosphate,PtdIns(3)P]生成磷脂酰肌醇-3,5-二磷酸[phosphatidylinositol-3,5-bisphosphate,PtdIns(3,5)P2]或磷脂酰肌醇-5-磷酸[phosphatidylinositol-5-phosphate,PtdIns(5)P],在调节膜运输以及维持溶酶体功能中发挥关键作用,还参与内体转运、转录调控和免疫调节等重要细胞生物学功能。近年来的研究表明,PIKfyve在炎症、病原微生物感染、神经退行性疾病和肿瘤的发生发展中起重要作用,可作为潜在的疾病防治靶点。本文就PIKfyve的生化特点、生物学功能及其在相关疾病中发挥的作用研究进展进行综述。     

Glypican-3结构、生物学功能及其肝细胞癌靶向治疗研究进展

肝细胞癌(hepatocellular carcinoma,HCC)是最常见的恶性肿瘤之一,但现有治疗方法效果均不甚理想.磷脂酰肌醇蛋白聚糖-3(glypican-3,GPC3)是肝癌诊断的特异性生物标志物,也是HCC靶向治疗的潜在靶标.近年来,针对GPC3蛋白的靶向治疗包括抗体、抗体-药物偶联物(ADC)、免疫毒素、...     

SHIP蛋白质的生物学特性及其与白血病的关系

含SH2结构域的肌醇磷酸酶(SHIP)属于5’磷酸酯酶家族成员。SHIP能将磷脂酰肌醇-3,4,5-三磷酸(PI-3,4,5-P3,PIP3)水解为磷脂酰肌醇-3,4-二磷酸(PI-3,4-P2),是主要表达于造血细胞的磷脂酰肌醇3-激酶(PI3K)信号抑制分子,通过参与调节PI3K途径而影响细胞增殖、存活及信号转导等诸多细胞活动,与白血病的发生发展密切相关。     

靶向Glypican-3的肝癌免疫治疗研究进展

磷脂酰肌醇蛋白聚糖3(Glypican-3)蛋白高特异性表达于肝细胞肝癌患者中,研究表明其与肝癌的发展和转移关系密切。目前以Glypican-3蛋白为靶点治疗肝癌的免疫研究主要包括治疗性抗体开发、CAR-T免疫疗法、免疫毒素及多肽疫苗等。现对Glypican-3的结构功能与肝癌的关系进行介绍,并简要描述靶向Glypican-3治疗肝癌的研究现状。     

磷酸－Tyr－Sepharose吸附法测定HL－60细胞中磷脂酰肌醇－3－激酶

 磷酸－Ｔｙｒ－Ｓｅｐｈａｒｏｓｅ吸附法测定ＨＬ－６０细胞中磷脂酰肌醇－３－激酶黄才,梁念慈（广东医学院医用生化研究所,湛江５２４０２３）磷脂酰肌醇－３－激酶（ＰＩ－３－Ｋ）催化磷脂酰肌醇（ＰＩ）和磷脂酰肌醇－４－磷酸（ＰＩ－４－Ｐ）的磷酸化分别生成磷...     

槲皮素对完整HL-60细胞中肌醇磷脂转换的抑制作用

槲皮素对完整ＨＬ┐６０细胞中肌醇磷脂转换的抑制作用康铁邦梁念慈（广东医学院医用生化研究所,湛江５２４０２３）肌醇磷脂信使系统在生物信号的跨膜传递方面起重要作用,并与细胞增殖及肿瘤形成有密切联系［１～５］,有报道：肿瘤细胞或组织中磷脂酰肌醇４－激酶（Ｐ...     

蛋白激酶B/Akt抑制剂

磷脂酰肌醇-3-激酶(phosphatidylinositol 3-kinase,PI3K)/蛋白激酶B(protein kinase B,PKB/Akt)信号通路在细胞生长与存活中起着关键作用,PI3K/Akt通路的过度激活在多种肿瘤中常见。Akt激酶本身以及Akt激酶上游调节分子,例如PTEN和PI3K,在超过50%的人类肿瘤中均有异常变化。因此Akt成为肿瘤预防和肿瘤靶向治疗的热点之一。许多小分子化合物通过不同机制抑制Akt活性,根据小分子抑制剂与激酶的结合部位和化学结构不同,主要分为ATP竞争性抑制剂、Akt变构抑制剂和磷脂酰肌醇类似物抑制剂。本文综述了PI3K/Akt通路与肿瘤的关系和Akt抑制剂的研究现状,为新型抗癌药物的设计研究提供参考。     

综述: Ⅲ型磷脂酰肌醇3-激酶复合物与自噬的研究进展

Ⅲ型磷脂酰肌醇3-激酶(class Ⅲ PI3K)是以磷脂酰肌醇(PtdIns)为底物催化产生PtdIns3 P的激酶,与多种不同的调节蛋白结合形成Ⅲ型PI3K(PI3KC3)复合物,在自噬及膜泡运输中起重要作用．PI3KC3复合物组成成员PI(3)KC3、p150、Beclin 1、ATG14L、UVRAG、Bif-1和Rubicon在进化上大多具有高度的同源性和保守性,并且与神经系统发育、胸腹腔内脏反位及肿瘤等多种疾病的发生和发展密切相关．     

Glypican-mediated endocytosis of Hedgehog has opposite effects in flies and mice

Glypicans are glycosylphosphatidylinositol-linked heparan sulfate proteoglycans that play an essential part in the regulation of morphogen signalling. Two new reports using Drosophila and mice have highlighted the importance of glypican endocytosis in the regulation of Hedgehog (Hh) signalling and in Wingless gradient formation. One Drosophila glypican, Dally-like, acts positively in Hh signalling, whereas mouse Glypican-3 is a negative regulator. This difference seems to be dependent on whether glypicans promote the internalization of Hh alone or as a complex with its receptor, Patched.     

Glypican-1 is a VEGF165 binding proteoglycan that acts as an extracellular chaperone for VEGF165

Glypican-1 is a member of a family of glycosylphosphatidylinositol anchored cell surface heparan sulfate proteoglycans implicated in the control of cellular growth and differentiation. The 165-amino acid form of vascular endothelial growth factor (VEGF165) is a mitogen for endothelial cells and a potent angiogenic factor in vivo. Heparin binds to VEGF165 and enhances its binding to VEGF receptors. However, native HSPGs that bind VEGF165 and modulate its receptor binding have not been identified. Among the glypicans, glypican-1 is the only member that is expressed in the vascular system. We have therefore examined whether glypican-1 can interact with VEGF165. Glypican-1 from rat myoblasts binds specifically to VEGF165 but not to VEGF121. The binding has an apparent dissociation constant of 3 x 10(-10) M. The binding of glypican-1 to VEGF165 is mediated by the heparan sulfate chains of glypican-1, because heparinase treatment abolishes this interaction. Only an excess of heparin or heparan sulfates but not other types of glycosaminoglycans inhibited this interaction. VEGF165 interacts specifically not only with rat myoblast glypican-1 but also with human endothelial cell-derived glypican-1. The binding of 125I-VEGF165 to heparinase-treated human vascular endothelial cells is reduced following heparinase treatment, and addition of glypican-1 restores the binding. Glypican-1 also potentiates the binding of 125I-VEGF165 to a soluble extracellular domain of the VEGF receptor KDR/flk-1. Furthermore, we show that glypican-1 acts as an extracellular chaperone that can restore the receptor binding ability of VEGF165, which has been damaged by oxidation. Taken together, these results suggest that glypican-1 may play an important role in the control of angiogenesis by regulating the activity of VEGF165, a regulation that may be critical under conditions such as wound repair, in which oxidizing agents that can impair the activity of VEGF are produced, and in situations were the concentrations of active VEGF are limiting.     

Cellular changes resulting from forced expression of glypican-3 in hepatocellular carcinoma cells

Glypican-3 (GPC3) is a member of the glypican family, which encodes cell-surface heparan-sulfate proteoglycans, and is frequently upregulated in hepatocellular carcinoma (HCC). We have recently reported that blocking endogenous GPC3 expression promotes the growth of HCC cell lines, suggesting that GPC3 plays a negative role in HCC cell proliferation. Here, we report that forced expression of GPC3 reduced the growth of HCC cells. We also found that FGF2-mediated cell proliferation was inhibited by GPC3. In addition, we observed that the adhesion of HCC cells to collagen type I and fibronectin was decreased by GPC3, whereas cellular migration and invasiveness were stimulated. Collectively, these results suggest that progression of hepatocellular carcinoma is associated with upregulation of GPC3.     

Heparan sulfate proteoglycans as regulators of fibroblast growth factor-2 signaling in brain endothelial cells. Specific role for glypican-1 in glioma angiogenesis

Fibroblast growth factor-2 (FGF2) is a potent angiogenic factor in gliomas. Heparan sulfate promotes ligand binding to receptor tyrosine kinase and regulates signaling. The goal of this study was to examine the contribution of heparan sulfate proteoglycans (HSPGs) to glioma angiogenesis. Here we show that all brain endothelial cell HSPGs carry heparan sulfate chains similarly capable of forming a ternary complex with FGF2 and fibroblast growth factor receptor-1c and of promoting a mitogenic signal. Immunohistochemical analysis revealed that glypican-1 was overexpressed in glioma vessel endothelial cells, whereas this cell-surface HSPG was consistently undetectable in normal brain vessels. To determine the effect of increased glypican-1 expression on FGF2 signaling, we transfected normal brain endothelial cells, which express low base-line levels of glypican-1, with this proteoglycan. Glypican-1 expression enhanced growth of brain endothelial cells and sensitized them to FGF2-induced mitogenesis despite the fact that glypican-1 remained a minor proteoglycan. In contrast, overexpression of syndecan-1 had no effect on growth or FGF2 sensitivity. We conclude that the glypican-1 core protein has a specific role in FGF2 signaling. Glypican-1 overexpression may contribute to angiogenesis and the radiation resistance characteristic of this malignancy.     

Expression profile analysis of aorta-gonad-mesonephros region-derived stromal cells reveals genes that regulate hematopoiesis

The aorta-gonad-mesonephros (AGM) region is involved in the generation and maintenance of the first definitive hematopoietic stem cells (HSCs). A mouse AGM-derived cell line, AGM-S3, was shown to support the development of HSCs. To elucidate the molecular mechanisms regulating early hematopoiesis, we obtained subclones from AGM-S3, one of which was hematopoiesis supportive (S3-A9) and the other one of which was non-supportive (S3-A7), and we analyzed their gene expression profiles by gene chip analysis. In the present study, we found that Glypican-1 (GPC1) was highly expressed in the supportive subclone AGM-S3-A9. Over-expression of GPC1 in non-supportive cells led to the proliferation of progenitor cells in human cord blood when cocultured with the transfected-stromal cells. Thus, GPC1 may have an important role in the establishment of a microenvironment that supports early events in hematopoiesis.     

Silencing glypican-3 expression induces apoptosis in human hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is one of the most common internal malignant tumors. Glypican-3 (GPC3) is involved in the biological and molecular events in the tumorigenesis of HCC. We used RNA interference to evaluate the molecular effects of GPC3 suppression at the translational level and demonstrated for the first time that GPC3 silencing results in a significant elevation of the Bax/Bcl-2 ratio, the release of cytochrome c from mitochondria and the activation of caspase-3. The results suggest that GPC3 regulates cell proliferation by enhancing the resistance to apoptosis through the dysfunction of the Bax/Bcl-2/cytochrome c/caspase-3 signaling pathway and therefore plays a critical role in the tumorigenesis of HCC. Thus, the knockdown of GPC3 should be further investigated as an attractive novel approach for the targeted gene therapy of HCC.     

Down-regulation of fibroblast growth factor 2 and its co-receptors heparan sulfate proteoglycans by resveratrol underlies the improvement of cardiac dysfunction in experimental diabetes

Cardiac remodeling in diabetes involves cardiac hypertrophy and fibrosis, and fibroblast growth factor 2 (FGF2) is an important mediator of this process. Resveratrol, a polyphenolic antioxidant, reportedly promotes the improvement of cardiac dysfunction in diabetic rats. However, little information exists linking the amelioration of the cardiac function promoted by resveratrol and the expression of FGF2 and its co-receptors, heparan sulfate proteoglycans (HSPGs: Glypican-1 and Syndecan-4), in cardiac muscle of Type 2 diabetic rats. Diabetes was induced experimentally by the injection of streptozotocin and nicotinamide, and the rats were treated with resveratrol for 6 weeks. According to our results, there is an up-regulation of the expression of genes and/or proteins of Glypican-1, Syndecan-4, FGF2, peroxisome proliferator-activated receptor gamma and AMP-activated protein kinase in diabetic rats. On the other hand, resveratrol treatment promoted the attenuation of left ventricular diastolic dysfunction and the down-regulation of the expression of all proteins under study. The trigger for the changes in gene expression and protein synthesis promoted by resveratrol was the presence of diabetes. The negative modulation conducted by resveratrol on FGF2 and HSPGs expression, which are involved in cardiac remodeling, underlies the amelioration of cardiac function.     

靶向磷脂酰肌醇蛋白聚糖-3治疗肝细胞癌的临床应用前景

磷脂酰肌醇蛋白聚糖-3（glypican-3, GPC3）是一种锚附着在细胞膜表面的癌胚蛋白质, 在肝细胞癌中过表达。GPC3可以作为肝细胞癌的生物标志物, 肝癌病人的血清GPC3水平对于预后评估存在重要价值。此外, 肝癌细胞中GPC3具有免疫反应性, 可以作为治疗靶点, 有关靶向GPC3治疗肝细胞癌的临床试验已经展开。本文简述了GPC3的结构及其在肝细胞癌发生发展中的作用, 回顾了靶向GPC3治疗肝细胞癌的临床研究结果, 并总结了GPC3相关临床应用的最新进展：新的抗GPC3抗体正在研发, 它们与其它靶向药物联用的临床试验正在展开;有关GPC3靶向的TRAB、GPC3疫苗和GPC3基于嵌合抗原受体(CAR)-T疗法的研究正在进行。我们认为,靶向GPC3治疗肝细胞癌的方案具有广阔的临床应用前景, 期待更多的研究聚焦于此, 为靶向GPC3疗法提供更充分的科学依据。     

Modulation of turkey myogenic satellite cell differentiation through the shedding of glypican-1

Glypican-1 is a cell membrane heparan sulfate proteoglycan. It is composed of a core protein with covalently attached glycosaminoglycan, and N-linked glycosylated (N-glycosylated) chains, and is attached to the cell membrane by a glycosylphosphatidylinositol (GPI) linkage. Glypican-1 plays a key role in the growth and development of muscle by regulating fibroblast growth factor 2 (FGF2). The GPI anchor of glypican-1 can be cleaved, resulting in glypican-1 being secreted or shed into the extracellular matrix environment. The objective of the current study was to investigate the role of glypican-1 shedding and the glycosaminoglycan and N-glycosylated chains in regulating the differentiation of turkey myogenic satellite cells. A glypican-1 construct without the GPI anchor was cloned into the mammalian expression vector pCMS-EGFP, and glypican-1 without the GPI anchor and glycosaminoglycan and N-glycosylated chains were also cloned. These constructs were co-transfected into turkey myogenic satellite cells with a small interference RNA targeting the GPI anchor of endogenous glypican-1. The soluble glypican-1 mutants were not detected in the satellite cells but in the cell medium, suggesting the secretion of the soluble glypican-1 mutants. Soluble glypican-1 increased satellite cell differentiation and enhanced myotube formation in the presence of exogenous FGF2. The increase in differentiation was supported by the elevated expression of myogenin. In conclusion, the shedding of glypican-1 from the satellite cell surface acts as a positive regulator of satellite cell differentiation and sequesters FGF2, permitting further differentiation.