转化生长因子β受体Ⅱ对微卫星不稳定结肠癌细胞凋亡和迁移的影响

目的 研究转化生长因子β受体Ⅱ(TGFβ RⅡ)表达对微卫星不稳定(MSI)结肠癌细胞凋亡和迁移的影响.方法 选择野生型PIK3CA HCT116细胞(HCT116 wt)作为MSI结肠癌细胞模型.将TGFβRⅡ转染HCT116 wt细胞获得HCT116 wt-RⅡ细胞,并以HCT116 wt空质粒细胞作为对照.通过生长因子缺失应激(GFDS)诱导细胞凋亡.采用Western印迹检测磷酸化Smad2(TGFβ信号通路关键因子)、磷酸化AKT (PI3K/AKT信号通路关键因子)、Bim (TGFβ信号通路下游因子)和Ecadherin(诱导上皮向间质转化的标志物)表达.采用DNA碎片ELISA分析检测HCT116 wt-RⅡ细胞凋亡情况.通过Transwell实验检测HCT116 wt-RⅡ细胞迁移活力.结果 加入TGFβ后,HCT116 wt-RⅡ细胞的TGFβ信号通路得以启动,GFDS诱导的HCT116 wt-RⅡ细胞凋亡受到显著抑制(DNA碎片值:0.69±0.02比0.41±0.04,P＜0.01);细胞迁移活力明显增强(2.10±0.15比4.03±0.48,P＜0.01).PI3K抑制剂(LY294002)可以逆转TGFβ对HCT116 wt-RⅡ细胞的凋亡抑制和迁移活力增强作用.TGFβ作用于HCT116 wt-RⅡ细胞后,Bim和E-cadherin表达明显减少.结论 TGFβRⅡ在MSI结肠癌细胞中的再表达可以增加MSI结肠癌细胞的存活能力和迁移活力,该作用依赖PI3K/AKT途径,从而为MSI结肠癌患者的良好预后提供了一个分子水平的解释.     

转化生长因子β受体的研究进展

转化生长因子β受体有3个亚型;Ⅰ型、Ⅱ型、Ⅲ型,其结构功能特点及在转导TGF-β信号过程中的作用机制不同,细胞在受体水平的变化影响TGF-β的功能。     

转化生长因子β及其受体与胃癌的研究进展

ＴＧＦβ在胃癌组织及胃癌患者血浆中水平升高显著，它促进胃癌间质中胶原形成，与胃癌的不同病理分型有关；可促进胃癌间质中血管生成，抑制机体免疫能力，从而影响胃癌的转移。ＴＧＦβⅡ型受体基因在胃癌中的突变及ＴＧＦβ型受体表达水平下降，使胃癌细胞对ＴＧＦβ的敏感性下降，从而逃避ＴＧＦβ的增殖抑制、诱导凋亡作用，而呈恶性增殖。     

转化生长因子—β与胃癌

胃癌细胞中转化生长因子 β(TGF β)呈高表达 ,TGF β虽具有抑制肿瘤细胞生长的作用 ,但亦能TGF β诱导血管的形成 ,抑制机体的免疫系统 ;同时 ,转化生长因子受体表达低下或功能失活能阻滞凋亡信号的转导 ,使癌细胞逃逸TGF β的负性调节 ,并 ;共同参与了胃癌的演进过程。     

转化生长因子β1及其受体与大肠癌

转化生长因子 β1(TGF β1)是人体多种组织细胞的生长调控因子 ,其对大多数正常细胞及上皮性肿瘤细胞具有生长抑制作用。转化生长因子 β1Ⅱ 型受体 (TβRⅡ)的表达减少是机体细胞逃逸TGF β1负调控作用从而发生癌变的一个重要改变。TGF β1及其受体的改变与大肠癌关系密切。     

干扰TGF-βⅡ型受体表达对NB4细胞增殖、分化及凋亡的影响

目的:研究干扰TGF-βⅡ型受体(TβRⅡ)表达对人急性早幼粒细胞白血病NB4细胞生长、分化及凋亡的影响。方法:应用慢病毒介导RNA干扰技术,下调NB4细胞TβRⅡ基因的表达,获得TβRⅡ-shRNA NB4细胞,CCK-8法检测细胞的活力,流式细胞术检测CD11b表达,并用瑞氏-吉姆萨染色法检测全反式维甲酸对细胞分化的影响; Annexin V-FITC/PI双荧光标记法及AO/EB染色观察三氧化二砷对细胞凋亡的影响。结果:TβRⅡ-shRNA NB4细胞的活力高于NB4细胞。采用不同浓度(0. 01、0. 02、0. 04、0. 08和0. 1μmol/L)的全反式维甲酸进行96 h的孵育后,2组细胞均出现分化现象(CD11b表达增加),并呈剂量依赖性,但TβRⅡ-shRNA NB4细胞的分化率低于NB4细胞。不同浓度(2、4和8μmol/L)的三氧化二砷孵育24 h后,2组细胞均出现凋亡现象(AO/EB染色),呈剂量依赖性,但TβRⅡ-shRNA NB4细胞凋亡率显著低于NB4细胞,其中用8μmol/L三氧化二砷孵育TβRⅡ-shRNA NB4细胞和NB4细胞24 h,凋亡率分别是(49. 15±2. 05)%和(66. 85±2. 41)%(P 0. 01)。结论:下调TβRII可以促进NB4细胞的生长,部分拮抗全反式维甲酸诱导的细胞分化及三氧化二砷诱导的细胞凋亡。     

转化生长因子β的结构、受体及作用方式

TGF－β是一大类多功能的细胞因子，在体内广泛分布，并参与多种生理与病理过程。本综述重点介绍TGF-β的分子结构、受体、作用方式以及其他分子生物学特征。     

转化生长因子βⅡ型受体在小鼠肾发育中的表达

目的:观察转化生长因子βⅡ型受体(TβRⅡ)在小鼠肾发育中的时空性表达,探讨转化生长因子β(TGF-β)与肾发育的关系。方法:采用免疫组织化学法、体视学和免疫印迹法测定不同胚龄(E)12、14、16和18d及生后日龄(P)1、3、7、14、21、28和42d小鼠肾内TβRⅡ的表达及其含量变化。结果:免疫组织化学结果显示TβRⅡ在各期肾小体、肾小管及集合管内均有表达,但在各期近端小管强烈表达,各期集合管表达较强,而各期肾小体、远端小管内表达较弱。体视学测量结果显示TβRⅡ在各期肾小体、肾小管及集合管的表达量均逐渐增加。免疫印迹结果显示TGF-βRⅡ随着肾的发育其表达量逐渐增加。结论:TGF-β可能对肾各结构的发育以及成熟肾各结构的维持起重要作用,尤其在近端小管的发育方面作用更为显著。     

石蜡包埋人胰腺癌组织中Smad4蛋白和转化生长因子β1及其Ⅱ型受体的表达

目的：探讨转化生长因子（TGF）－β通路中Smad4蛋白,TGFβ1和转化生长因子βⅡ型受体（TβRⅡ）的关系及它们在胰腺癌中的可能作用机制。方法：用EnVision免疫组织化学技术检测56份石蜡包埋人胰腺癌标本Smad4蛋白,TGFβ1和TβRⅡ蛋白表达的情况。结果：56份胰腺癌组织Smad4,TGFβ1和TβRII阳性率分别为58．93％（33）,66．07％（37）和60．71（34）,对应正常胰腺组织阳性率分别为89．29％（50）,25．00％（14）和25．00％（14）,TGFβ1的表达与临床分期,肿瘤的有无转移相关（P＜0．05）,TGFβ1和TβRII之间也有相关关系（P＜0．05）,结论：胰腺癌组织中Smad4表达降低,TGFβ1与TβRII则呈过表达,TGFβ1和TβRII对胰腺癌的发生可能有协同作用。Smad在TGF－β诱导基因表达调控和随后的生长抑制中是关键的转录因子,但TGFβ有时也可能以与Smad4无关的形式起作用。     

伴有微卫星不稳定性的散发性结直肠癌转化生长因子-betaⅡ型受体基因突变的研究

目的:为了探讨在散发性结直肠癌的发生过程中转化生长因子βⅡ型受体基因(RII)的突变与微卫星不稳定性(RER)间的关系。方法: 我们应用PCR-SSCP-银染方法检测了50例散发性结直肠癌中的RER状态及RII基因突变情况(近端结肠19例,远端31例)。结果: RER+的共有13例(8例在近端,5例在远端),RII基因突变的共有5例。所有5例RII基因突变者均同时伴有RER+,而所有RER-病例均无RII基因突变。其中4例RII基因突变者位于回盲部肿瘤中。结论: 这些数据提示在散发性结直肠癌中,尤其是在回盲部肿瘤中,TGF-β RII基因的A₁₀重复序列是微卫星不稳定性的靶点,在肿瘤形成过程中可能起重要作用。     

Association between single nucleotide polymorphisms in the hMSH3 gene and sporadic colon cancer with microsatellite instability

The association between three single nucleotide polymorphisms (SNPs) in the hMSH3 gene and sporadic colon cancer with microsatellite instability (MSI) was analyzed. Of the three SNPs observed in this population, SNPs at residues 235 and 693 were novel, while that at residue 3133 was previously described. The SNPs at residues 235 and 3133 caused amino acid substitutions, V79I and T1045A, respectively. We analyzed the allele frequencies of the three SNPs in samples from 19 patients with sporadic colon cancer with MSI and 90 healthy controls. We found that the V79 allele frequency was significantly higher in the tumor samples than in controls. In addition, the frequency of the G693 allele showed a higher trend in the tumor samples than in controls. These results indicated that some SNPs in the hMSH3 gene were associated with colon cancer with MSI. Received: February 16, 2000 / Accepted: February 25, 2000     

Decreased expression of transforming growth factor-beta II receptor is associated with that of p27KIP1 in giant cell tumor of bone: a possible link between transforming growth factor-beta and cell cycle-related protein

Transforming growth factor (TGF)-beta is a potential regulator of cell growth that sends its signals through a heteromeric complex composed of type I and II receptors (IR and IIR). This study examined a correlation between TGF-beta1, TGF-beta-IR and -IIR, and cell cycle-related proteins in giant cell tumor (GCT) of bone, using immunohistochemical and Western blot analysis. First, an immunohistochemical study for TGF-beta1, TGF-beta-IR and -IIR, p27KIP1 (p27), p21WAF1 (p21), cyclin D1, and cyclin E was carried out on 92 cases of GCT of bone; the expression of these proteins was evaluated in multinucleated giant cells (MGCs) and mononucleated stromal cells (MSCs) separately; and proliferative activity was assessed using MIB-1. Next, to confirm our immunohistochemical results, Western blot analysis was performed in 19 cases for which frozen samples were available. Immunoreactivity for TGF-beta-IR and -IIR showed a tendency to be greater in MGCs than in MSCs; however, no differences were observed in TGF-beta1. Cyclin D1 expression was correlated with the occurrence of vascular invasion in both MGCs and MSCs (P = 0.0255 and 0.0183, respectively). The expression of TGF-beta-IIR and p27 was concordantly decreased in both MGSs and MSCs (P = 0.0014 and 0.0317, respectively). The expression for TGF-beta-IIR and p27 in Western blot analysis was related to the results from immunohistochemical analysis, and the expression of TGF-beta-IIR and p27 was concordant in almost all GCT cases. Furthermore, there was a statistically significant inverse relationship between p27 expression and MIB-1 labeling index in MSCs (P = 0.0397). In GCT of bone, TGF-beta-IIR and p27 expression were concordantly decreased; this result supports the possibility that these 2 factors may play an important role in cell proliferation of this tumor. Furthermore, our results provide a possible link between the effects of extracellular growth factors and cell cycle control. In addition, p27 expression may be a useful indicator of cell proliferation in MSCs of this tumor.     

Colorectal neoplasms detected colonoscopically in at-risk members of colorectal cancer families stratified by the demonstration of DNA microsatellite instability

This study compared colonoscopic findings in families meeting the Amsterdam criteria (A) for hereditary non-polyposis colorectal cancer (HNPCC) but stratified according to whether the familial cancers showed DNA microsatellite instability. DNA was extracted from paired samples of normal and cancer, and microsatellite instability was analysed at up to six loci. Families were termed replication error positive (RER⁺) when at least 50% of tumours tested per family were positive. Of 26 families studied 17 were RER⁺ and 9 were RER^-. Cancers in the A/RER^- families showed no right-sided predilection (P<0.001). Colonoscopies have been performed on 182 at-risk members of A/RER⁺ families and 60 members of A/RER^- families. More of the at-risk members of A/RER^- families were found to have adenomas at colonoscopy (P=0.095), but these were smaller than those of A/RER⁺ families (P=0.19). The adenoma:carcinoma ratio was twice as high in A/RER^- families (131) as in A/RER⁺ families (71). One of the A/RER^- families had hyperplastic polyposis. The others do not appear to have attenuated familial adenomatous polyposis and are similar to the adenoma families or late-onset colorectal cancer families described by others. This study illustrates the importance of molecular technology in separating HNPCC from syndromes with overlapping phenotypes.Abbreviations A Amsterdam criteriz - CRC Colorectal cancer - FAP Familial adenomatous polyposis - HNPCC Hereditary non-polyposis colorectal cancer - RER Replication error     

Expression of platelet-derived growth factor-beta receptor and bovine papillomavirus E5 and E7 oncoproteins in equine sarcoid

Equine sarcoids are benign fibroblastic skin tumours that are recognized throughout the world. Infection with bovine papillomavirus (BPV) types 1 and 2 has been implicated as a major factor in disease development; however, the cellular mechanisms underlying fibroblast transformation remain poorly defined. The present study further characterizes aspects of the association with BPV in 15 equine sarcoids. BPV DNA was demonstrated in 12/15 tumours collected from different areas of Italy. Nine of these 12 tumours expressed the BPV oncoproteins E5 and E7, but these oncoproteins were not expressed by normal equine cells. The BPV E5 protein is known to bind to the platelet-derived growth factor-beta receptor (PDGF-betaR) and this molecule was expressed by 11 of the 12 sarcoids in which E5 was demonstrated. These findings add further weight to the theory that BPV and the PDGF-betaR may have a role in the pathogenesis of this disease.     

人肺癌细胞中生长因子的自泌循环和癌基因表达

用Ｎｏｒｔｈｅｒｎ核酸杂交技术对４个人肺癌细胞系进行了表皮生长因子（ＥＧＦ）、转化生长因子α（ＴＧＦα）以及表皮生长因子受体（ＥＧＦＲ）的基因表达研究，发现这些肺癌细胞系中均有ＥＧＦ和ＴＧＦ＿α的基因表达，３／４中亦有ＥＧＦＲ的基因表达。这些癌细胞系中自泌的生长因子作用于自身的ＥＧＦ受体形成的自泌循环，不断刺激其自身的增殖，这可能是癌细胞无休止生长的主要原因之一。Ｎｏｒｔｈｅｒｎ核酸杂交结果还表明：在这４个肺癌细胞系中，无ｃ－ｍｙｃ癌基因表达的细胞系中有大量的ＥＧＦ和ＴＧＦα的基因表达。用ＥＧＬ抗ＥＧＦ和抗ＥＧＦＲ抗体处理这些人肺癌细胞系，抗ＥＧＦ和抗ＥＧＦＲ抗体在一定程度上可抑制其增殖，这也说明这些癌细胞中生长因子自泌环路的存在。     

Distinctive patterns of p53 protein expression and microsatellite instability in human colorectal cancer

Although evidence suggests an inverse relationship between microsatellite instability and p53 alterations in colorectal cancer, no study has thoroughly examined the use of p53 immunohistochemistry in phenotyping colorectal cancers. We investigated the value of p53 immunohistochemistry in microsatellite instability–positive colorectal cancers prescreening and attempted to clarify the relationship between DNA mismatch repair system and p53 pathway. In a series of 104 consecutive colorectal cancers, we performed p53 immunohistochemistry, TP53 mutational analysis, DNA mismatch repair system efficiency evaluation (DNA mismatch repair system immunohistochemistry, microsatellite instability status, MLH1/MSH2 germ line, and BRAF, murine double minute 2, and p21 immunohistochemistry. Microsatellite instability high was observed in 25 of 104 colorectal cancers, with DNA mismatch repair system protein loss (24/25) and germ line (8/25) or BRAF mutations (8/25). p53 immunohistochemistry revealed 3 distinct patterns of expression: complete negative immunostaining associated with truncating TP53 mutations (P < .0001), diffuse overexpression associated with missense TP53 mutations (P < .0001), and restricted overexpression characterized by a limited number of homogenously scattered strongly positive tumor cells in 36.5% of colorectal cancers. This latest pattern was associated with wild-type TP53 and microsatellite instability high colorectal cancers (P < .0001) including all Lynch tumors (8/8), but its presence among 22% of DNA mismatch repair system–competent colorectal cancers decreased its positive predictive value (55.2% [95% confidence interval, 45%-65%]). It was also correlated with murine double minute 2 overexpression (P < .0001) and inversely with p21 loss (P = .0002), independently of microsatellite instability status. In conclusion, a restricted pattern of p53 overexpression is preferentially associated with microsatellite instability high phenotype and could, therefore, be of clinical use as signal for microsatellite instability analysis in a large-scale tumor screening. Its association with concomitant murine double minute 2 overexpression suggests an alternative mechanism of p53 pathway deregulation.