抑癌基因PTEN研究进展

目的：总结抑癌基因PTEN在常见恶性肿瘤中的研究进展。方法：查阅相关中外文献,分析PTEN的功能以及与常见恶性肿瘤的关系。结果：作为第1个具有双特异性磷酸酶活性的抑癌基因,PTEN基因的失表达与众多恶性肿瘤的发生、发展关系密切。结论：可以通过对PTEN基因的研究,为临床早期诊断及基因治疗提供新的思路和依据。     

PTEN基因的研究进展

PTEN基因是迄今发现的第一个具有双特异性磷酸酶活性的抑癌基因 ,该基因的突变失活与人类多数恶性肿瘤的发生发展密切相关 ,PTEN蛋白在细胞的生长发育、信号传导和细胞凋亡过程中起重要的作用     

PTEN基因的研究进展

PTEN基因是迄今发现的第一个具有双特异性磷酸酶活性的抑癌基因,该基因的突变失活怀人类多数恶性肿瘤的发生发展密切相关,PTEN蛋白在细胞的生长发育、信号传导和细胞凋亡过程中起重要的作用。     

PTEN基因与肿瘤

PTEN基因是迄今发现的第一个具有双特异性磷酸酶活性的抑癌基因,该基因的突变失活与人类多数恶性肿瘤的发生发展密切相关,PIEN蛋白在细胞的生长发育、信号转导和细胞凋亡过程中起重要作用.     

酪氨酸激酶抑制剂甲磺酸伊马替尼对PTEN介导的K562细胞侵袭的影响

目的:研究酪氨酸激酶抑制剂甲磺酸伊马替尼对K562细胞PTEN信号转导的调控,以及对细胞侵袭功能的影响.方法:不同浓度甲磺酸伊马替尼作用K562细胞不同时间后,通过荧光定量PCR检测BCR/ABL、PTEN、FAK水平变化及相互关系,免疫细胞化学染色检测FAK蛋白水平,Transwell小室检测K562细胞侵袭功能.结果:2μg/mL甲磺酸伊马替尼作用K562细胞在36 h内,随着BCR/ABL融合基因表达减低,PTEN mRNA表达上调,FAK mRNA及蛋白表达下调,K562细胞侵袭功能明显减弱.作用48 h后,随着BCR/ABL融合基因的抑制减弱,PrEN表达进而减低,而FAK表达升高.BCR/ABL mRNA与PTEN mRNA呈负相关趋势,与FAK mRNA呈正相关趋势.结论:甲磺酸伊马替尼通过抑制BCR/ABL融合基因调控PTEN/FAK信号转导通路,参与抑制白血病K562细胞侵袭作用.     

PTEN基因的生物学特性及其在恶性肿瘤中作用机制的研究进展

磷酸酶-张力蛋白同源物(phosphatase and tension homology deleted on chromsome ten,PTEN)是人类癌症中最常见的肿瘤抑制基因之一,PTEN的突变或丢失常引起许多恶性肿瘤和肿瘤综合症(PTEN错构瘤肿瘤综合征)的发生,如肝癌、子宫内膜癌、乳腺癌、鼻咽癌、宫颈癌、消化道肿瘤及Cowden病和Bannayan-Zonana综合征等。PTEN的过度表达对多种肿瘤的发生、发展有着重要影响,本文就近年来PTEN基因的生物学特性及其在恶性肿瘤发生和发展中的作用机制进行综述。     

PTEN与心肌纤维化关系的研究进展北大核心CSCD

人第10号染色体丢失的磷酸酶及张力蛋白同源的基因（phosphatase and tensin homolog on chromosome 10,PTEN）因在肿瘤及纤维化的病理生理过程中起到重要作用而长期受到关注,其在许多细胞,包括心肌细胞、血管平滑肌细胞和内皮细胞中广泛表达.新近研究发现,PTEN及其相关分子靶点在心肌纤维化中也起到重要作用.结合国内外研究进展,我们就PTEN的结构功能以及在心肌纤维化过程中所起作用及相关作用机制予以综述.     

Genetic aberration of PTEN in peripheral T cell lymphoma, not otherwise specified

目的 观察非特指外周T细胞淋巴瘤(peripheral T cell lymphoma,not otherwise specified,PTCL-NOS)中抑癌基因(phosphatase and tensin homolog deleted on chromosome ten,PTEN)的改变情况,探讨其与肿瘤生物学行为的关系,为阐明PTCL-NOS的发生、发展机制提供科学依据.方法应用间期双色荧光原位杂交(fluorescence in situ hybridization,FISH)技术检测36例PTCL-NOS石蜡包埋组织中PTEN基因的改变情况,分析其改变与各临床参数的关系.结果 36例PTCL-NOS中8例出现PTEN杂合性缺失(loss of heterozygosity,LOH);Kaplan-Meier生存分析显示该基因异常组较正常组生存期明显缩短(P<0.05);PTEN基因改变与病理分期、发生部位、年龄、性别、乳酸脱氢酶(LDH)水平均无相关性(P>0.05).结论 PTCL-NOS存在的抑癌基因PTEN杂合性缺失,在PTCL-NOS发生、发展中可能起重要作用,是评估该肿瘤预后的重要指标.     

PTEN在消化道肿瘤的研究进展

PTEN是迄今发现的第一个具有双重特异性磷酸酶活性的肿瘤抑制基因,在细胞的生长发育、凋亡、迁移、信号传递等方面起着重要的调控作用,虽然已经证实PTEN基因的表达水平与多数消化系统肿瘤的发生、发展及预后存在相关性,但其精确作用点、作用机制以及它在消化系统肿瘤发生中的重要性等,均有待于进一步阐述。现对国内外PTEN基因在消化系统肿瘤中的研究进展作一综述。     

下调uPAR表达抑制高侵袭性人膀胱癌细胞系T24的迁移与侵袭

目的探究尿激酶型纤溶酶原激活物受体(u PAR)的表达对高侵袭性人膀胱癌细胞系T24体外增殖与侵袭的影响,以及哺乳动物靶向雷帕霉素靶蛋白复合物2(m TORC2)可能的作用。方法设计合成针对u PAR、Rictor、PTEN基因的siRNA和阴性对照NC siRNA。将对数增殖期T24细胞随机分为5组,并设为实验组siu PAR、siRictor、siRictor+siu PAR、siu PAR+si PTEN和对照组NC。用瞬时转染法将以上siRNA及相应组合分别转入5组T24细胞;分别用RT-qPCR和Western blot检测mRNA及蛋白的表达;用MTT法和Transwell侵袭实验分别检测u PAR siRNA对T24细胞增殖及侵袭的影响。结果 T24细胞中u PAR mRNA和蛋白的表达量显著上调(P0. 05)。沉默u PAR能够显著下调T24细胞中磷酸化Akt Serine-473(P-Akt S473)的表达量(P0. 05),并抑制T24细胞的迁移与侵袭(P0. 05)。敲除PTEN基因的T24细胞中,沉默u PAR基因促进Akt S473磷酸化(P0. 05)。结论沉默u PAR能够抑制T24细胞的迁移与侵袭,在T24细胞中u PAR可能是m TORC2的上游调控因子。     

R280T mutation of p53 gene promotes proliferation of human glioma cells through GSK-3β/PTEN pathway

p53 mutation is associated with “gain-of-function” capabilities of human cancers. We aim to identify p53 mutations in human glioma cells and to explore the potential mechanism for mutant p53-promoted cellular growth. Whole genomic DNA was isolated from SWO-38, a human glioma cell line and amplified for the region of exons 5, 6, and 8 in p53 gene using polymerase chain reaction (PCR). By means of direct sequencing of PCR products and alignment analysis using BLAST database, a mutation of G to C transition at codon 280 of p53 exon 8 (AGA → ACA), i.e. R280T was detected in SWO-38 cells. Knockdown of R280T mutant p53 by RNA interference inhibited the GSK-3β/PTEN associated cell proliferation, and PI3K/Akt but not Wnt/β-catenin signaling pathway was involved in this process. Furthermore, depletion or overexpression of PTEN alone did not affect cell proliferation and cell cycle, implicating the impairment of PTEN function in SWO-38 cells. However, knockdown of both PTEN and p53 mutation could significantly rescue the p53 depletion-mediated growth inhibition, suggesting that the R280T mutation in glioma may promote the proliferation through an underlying mechanism related to PTEN. Our observations indicate that the R280T mutation of p53 regulates the proliferation of human glioma cells related to the GSK-3β/PTEN pathway. These findings provide valuable insights for better understanding the molecular mechanism of uncontrolled growth of glioma cells.     

PTEN permits acute increases in D3-phosphoinositide levels following TCR stimulation but inhibits distal signaling events by reducing the basal activity of Akt

Phosphoinositide 3-kinase (PI3K) is important in TCR signaling. PI3K generates phosphatidylinositol 3, 4, 5-trisphosphate (PI-3,4,5-P3), which regulates membrane localization and/or activity of multiple signaling proteins. PTEN (phosphatase and tensin homologue deleted on chromosome 10) opposes PI3K, reversing this reaction. Maintaining the balance between these two enzymes is important for normal T cell function. Here we use the PTEN-null Jurkat T cell line to address the role of PTEN in modulating proximal and distal TCR-signaling events. PTEN expression at levels that restored low basal Akt phosphorylation (an indicator of PI-3,4,5-P3 levels), but which were not themselves cytotoxic, had minimal effect on TCR-stimulated activation of phospholipase Cgamma1 and Ca2+ flux, but reduced the duration of extracellular signal-regulated kinase (Erk) activation. Distal signaling events, including nuclear factor of activated T cells (NFAT) activation, CD69 expression and IL-2 production, were all inhibited by PTEN expression. Notably, PTEN did not block TCR-stimulated PI-3,4,5-P3 accumulation. The effect of PTEN on distal TCR signaling events was strongly correlated with the loss of the constitutive Akt activation and glycogen synthase kinase-3 (GSK3) inhibition that is typical of Jurkat cells, and could be reversed by expression of activated Akt or pharmacologic inhibition of GSK3. These results suggest that PTEN acts in T cells primarily to control basal PI-3,4,5-P3 levels, rather than opposing PI3K acutely during TCR stimulation.     

The PKC gene module: molecular biosystematics to resolve its T cell functions

Summary: The distinct protein kinase C (PKC) multigene family (PKC gene module) is known to be the ‘classic’ intracellular receptor for mitogenic phorbol esters, and it is widely accepted in the scientific community that the ‘PKC effect’ is essential in activation, differentiation, adhesion and motility, as well as in cellular survival, of T cells. Nevertheless, the first concepts about PKC isotype heterogeneity of cellular localization and function emerged only recently, when the PKC‐θ pathways were mapped to critical signaling networks that control T cell receptor (TCR)/CD3‐dependent interleukin (IL)‐2 production and proliferation in T lymphocytes. This review summarizes the current knowledge about T cell expressed PKC gene products, their known and/or suspected regulation and cellular effector pathways, as well as physiological functions in T lymphocytes (as determined by molecular cell biology and ongoing mouse genetic studies). Given PKCs integral role in T cell function but today's very fragmentary molecular understanding of directly PKC‐mediated effector functions in transmembrane signaling, a ‘molecular biosystematics’ approach is suggested to resolve the isotype‐selective functions of this PKC gene family. Such an approach has to be based not only on genomic/cytogenetic analysis to establish its genetic relationships but also on biochemical/cell biology and genetic studies to resolve its functional diversity and, ultimately, nonredundant roles in real T cell physiology.     

Recent advances in the genetic analysis of PTEN and PI3K innate immune properties

The role of the PI3-kinase pathway and its antagonist PTEN in the regulation of innate immune responses has only recently attracted the attention of the scientific community. The PI3K/PTEN signaling axis is most renowned for its critical involvement in the malignant transformation of cells leading to tumorigenesis. PI3K function in the regulation of innate immunity, either pro-inflammatory or anti-inflammatory, is still a controversial issue. Undoubtedly, PI3K serves as an essential pro-inflammatory signaling molecule to activate leukocytes, initiate migration and facilitate phagocytosis. Nevertheless, it is less clear how PI3K and PTEN modulate the amplitude of immune responses. Here, we review recent advances on the immune biology by means of reverse genetics analyzing the role of the PI3K/PTEN signaling cascade in innate immunity.     

Phosphatase and tensin homolog deleted on chromosome 10 regulates sensory cell proliferation and differentiation of hair bundles in the mammalian cochlea

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that regulates cell proliferation, differentiation and growth. It regulates neural and glioma stem/progenitor cell renewal and PTEN deletion can drive expansion of epithelial progenitors in the lung, enhancing their capacity for regeneration. Because it is expressed at relatively high levels in developing mammalian auditory hair cells we have analyzed the phenotype of the auditory epithelium in PTEN knock-out mice. PTEN^+/− heterozygous littermates have only one functional copy of the gene and show clear evidence for haploinsufficiency in the organ of Corti. Auditory sensory epithelial progenitors withdraw from the cell cycle later than in wild-type animals and this is associated with increases in the numbers of both inner and outer hair cells. The cytoskeletal differentiation of hair cells was also affected. While many hair bundles on the hair cells appeared to develop normally, others were structurally disorganized and a number were missing, apparently lost after they had been formed. The results show that PTEN plays a novel role in regulating cell proliferation and differentiation of hair bundles in auditory sensory epithelial cells and suggest that PTEN signaling pathways may provide therapeutic targets for auditory sensory regeneration     

MicroRNA-181d-5p通过PTEN参与睾丸支持细胞间紧密连接损伤

目的:探讨miR-181d-5p通过与人第10号染色体缺失的磷酸酶和张力蛋白同源的基因(PTEN)mRNA 3'UTR区相互作用,参与小鼠睾丸支持细胞TM4细胞间紧密连接损伤及其可能机制.方法:通过网站预测miR-181d-5p的靶基因为PTEN mRNA,采用双荧光素酶报告基因分析实验在293T细胞上验证其与靶基因3...     

PTEN deficiency in endometrioid endometrial adenocarcinomas predicts sensitivity to PARP inhibitors

PTEN (phosphatase and tensin homolog) loss of function is the most common genetic aberration in endometrioid endometrial carcinomas. In addition to its well-described role in cell signaling, PTEN is involved in the maintenance of genomic stability. Loss of PTEN function causes defects in repair of DNA double-strand breaks by homologous recombination and, therefore, sensitizes cells to inhibition of the poly(adenosine diphosphate ribose) polymerase (PARP). Here, we determined the PTEN status of eight endometrioid endometrial carcinoma cell lines and correlated it with in vitro sensitivity to the PARP inhibitor KU0058948. PTEN-deficient cells showed a significantly greater sensitivity to KU0058948 than the two endometrioid endometrial carcinoma cell lines with wild-type PTEN. The cell lines lacking PTEN expression were unable to elicit a homologous recombination damage response as assayed by RAD51 focus function (a marker of competent homologous recombination DNA repair) upon irradiation and treatment with PARP inhibitors. PTEN silencing in PTEN wild-type Hec-1b cells resulted in reduced RAD51 foci formation after DNA damage and increased sensitivity to PARP inhibition. PTEN reexpression in PTEN-null cell lines resulted in enhanced RAD51 foci formation and in relative resistance to KU0058948. Given that up to 80% of endometrioid endometrial cancers lack PTEN expression, our results suggest that PARP inhibitors may be therapeutically useful for a subset of endometrioid endometrial cancers.     

PTEN modulates hepatitis B virus-X protein induced survival signaling in Chang liver cells

PTEN gene, a novel tumor suppressor is frequently mutated or deleted in several malignancies including human hepatocellular carcinoma (HCC). We report previously that human hepatitis B virus-X (HBx) protein achieves protection from apoptotic cell death through-PI3K-Akt-Bad signaling that is p53-independent in liver cells (JBC; 276, 16969 (2000)). In this report, we demonstrated the PTEN effect on HBx induced anti-apoptotic signaling in Chang liver cells (CHL). Expression of PTEN in CHL cells downregulate HBx induced PI3K, Akt activities, Akt, Bad phosphorylations, decreased caspase 3 activity and protection from DNA fragmentations. PTEN suppression of CHL cell growth at G1 phase (JBC;278,4057(2003)) in cell cycle analysis, which is overcome by HBx activated Akt/PKB further confirmed that same PI3K/Akt pathway is involved in cell survival and apoptosis by HBx and PTEN. PTEN suppression of HBx-mediated cell survival through PI3K pathway is specific, since PTEN does not suppress the effect of HBx on the protection from Fas-mediated apoptosis. Taken together, these findings demonstrate that PTEN potently modulate HBx-mediated signaling and is a viable target in therapeutic approaches to inhibit the formation of HCC caused by HBV infections.     

The phosphatidylinositol phosphatase PTEN is under control of costimulation and regulates proliferation in human T cells

The phosphatidylinositol phosphatase gene PTEN is a dual specific phosphatase acting on phospho amino acids but also on three phosphorylated inositol phospholipids. Present results demonstrate that PTEN is inducible by costimulatory signals in human CD4(+) T cells. PTEN expression was up-regulated on RNA and protein level in freshly isolated human CD4(+) T cells following stimulation with CD28 or CD2. In contrast, PTEN expression was high but remained CD28 and CD2 unresponsive in lymphoma cells. Intracellular staining revealed PTEN expression in CD4(+) T cell populations stimulated with anti-CD28 or anti-CD28 / anti-CD3. Stimulation with anti-CD3 alone did not induce PTEN expression. Inhibition of PTEN expression by antisense oligonucleotides in CD4(+) T cells stimulated with non-mitogenic anti-CD28 resulted in massively increased proliferation, which was sensitive to the phosphatidylinositol 3-kinase (PI3 K) inhibitor wortmannin. Although CD28 and CD2 induce PI3 K signal transduction, wortmannin did not block PTEN up-regulation by CD28 or CD2 indicating that PTEN gene expression is PI3 K independent. These results demonstrate that PTEN negatively controls costimulatory signals by antagonizing PI3 K activity in the absence of TCR engagement.     

Subcellular localization of intracellular protein tyrosine phosphatases in T cells

A high protein tyrosine phosphatase (PTPase) activity is required to maintain circulating T lymphocytes in a resting phenotype, and to limit the initiation of T cell activation. We report that 15 of the currently known 24 intracellular PTPases are expressed in T cells, namely HePTP, TCPTP, SHP1, SHP2, PEP, PTP-PEST, PTP-MEG2, PTEN, PTPH1, PTP-MEG1, PTP36, PTP-BAS, LMPTP, PRL-1 and OV-1. Most were found in the cytosol and many were enriched at the plasma membrane. Only TCPTP and PTP-MEG2 had subcellular localizations that essentially excludes them from a direct role in early T cell antigen receptor signaling events. Overexpression of 6 of the PTPases reduced IL-2 gene activation, 3 of them thereby identified as novel candidates for negative regulators of TCR signaling. Our findings expand the repertoire of PTPases that should be considered for a regulatory role in T cell activation.