Forskolin对放射性转化细胞TGF基因及部分癌基因表达的影响

3~H-TdR放射性转化细胞(TC3H/10)经1×10~(-5)mol/L Foskolin处理24 h后,TGFα、c-myc、c-K-ras基因的mRNA表达下降,TGFβ、c-fos基因表达无明显变化。非转化细胞(NC3H/10)经相同条件处理,TGFα、TGFβ、c-myc及c-K-ras基因表达无显著改变。提示:Forskolin介导的转化细胞的生长抑制作用与TGFa、cmyc、c-K-ras基因的转录表达下降有关。     

胃肠道肿瘤TGF－α基因表达的研究

用分子杂交技术及流式细胞方法研究了转化生长因子α(TGFα)在人胃肠道肿瘤组织中的表达.结果表明,胃癌、结肠癌和直肠癌组织较相应癌旁组织TGFαmRNA水平增高.佛波脂(TPA 100μg/L)作用胃癌细胞MGc80-3后4h,可使细胞中TGFαmRNA水平增高,作用6h可使S期细胞百分比明显增加.这些结果提示:TGFα在胃肠道肿瘤中起重要作用,其表达可受TPA的调节.     

转化的小鼠肝细胞能表达TGFαmRNA

转化生长因子α(TGFα)可以由许多细胞、尤其是转化细胞产生。细胞转化能启动并维持TGFαmRNA的表达及其多肽产物的生成。TGFα与表皮生长因子(EGF)的受体结合,以自分泌的方式刺激细胞生长。曾有报道,EGF可诱导体外培养正常角化细胞的TGFαmRNA聚集,雌激素对大鼠乳癌细胞也有此种作用,说明     

人膀胱癌转化生长因子α的研究

应用Northern印渍杂交和放射免疫分析技术证明了膀胱癌组织和细胞中TGFαmRNA的表达,并发现TPA能提高人膀胱移行上皮癌BIU-87细胞中TCFαmRNA和TGFα活性分子的水平,但对TGFα的功能受体(EGF受体)具有负调节作用。提示TGFα在膀胱肿瘤细胞的恶性增殖过程中起一定作用,蛋白激酶C的激活可能是调节TGFα基因表达的途径之一。     

m6A RNA甲基转移酶METTL3对肠癌细胞上皮间质转化及侵袭能力的影响

摘要 目的：探讨METTL3对肠癌细胞上皮间质转化及侵袭能力的影响。方法：TGFβ诱导肠癌细胞HCT116和SW480发生上皮间质转化;细胞划痕实验和Transwell-Matrigeal穿膜试验分别检测细胞转移侵袭能力;实时荧光定量PCR检测靶基因转录水平;siRNA干扰技术敲减肠癌细胞METTL3水平。结果：细胞划痕修复实验表明：TGFβ诱导组相对愈合面积与对照组相比显著增大（P<0.0001）,而TGFβ+敲减METTL3联合组处理组相对愈合面积与TGFβ诱导组相比显著减少（P<0.0001）。Transwell-Matrigeal细胞穿膜试验表明：TGFβ诱导组穿膜细胞数较对照组细胞显著增多（P<0.0001）,而TGFβ+敲减METTL3联合组处理组与TGFβ诱导组相比显著减少。TGFβ诱导组可显著诱导肠癌细胞发生上皮间充质转化,即增加核心转录因子Snail1和ZEB1水平,减低CDH1及上调Vimentin（VIM）水平,METTL3表达随TGFβ处理时间逐步上调。TGFβ+敲减METTL3联合组较TGFβ诱导组ZEB1和Snail1转录水平显著减低。结论：METTL3在TGFβ介导肠癌细胞EMT中起到关键作用,敲减METTL3可削弱肠癌细胞转移和侵袭能力,靶向抑制METTL3可能成为干预结直肠转移的重要分子靶点。     

TGFα反义寡聚核苷酸对膀胱癌BIU 87细胞株的作用

报道了23碱基组成的TGFα反义寡聚核苷酸和对照寡聚核苷酸对人膀胱移行细胞癌BIU87细胞增殖及其TGFα mRNA表达的作用,结果表明:TGFα反义寡聚核苷酸抑制体外培养的BIU87细胞的增殖、DNA合成和TGFα mRNA的表达,进一步证明了TGFα在BIU87细胞恶性增殖中的重要作用.     

转化生长因子β1诱导肺支气管上皮细胞发生上皮间质转化

目的:研究转化生长因子β1(TGF-β1)对人肺支气管上皮细胞(HBEC)的细胞形态和上皮间质转化(EMT)标志基因表达的影响。方法:TGF-β1处理HBEC 0、1、2、3、4和5 d,观察细胞形态;运用免疫荧光实验,观察TGF-β1处理HBEC 4 d时的细胞骨架;TGF-β1分别处理0、1、3、6 h和0、1、2、3、4、5 d,提取总RNA后反转录并进行实时荧光定量PCR检测EMT标志基因α-SMA、β-catenin、SNAI1和E-cadherin的mRNA表达情况。结果:TGF-β1处理HBEC 2 d时就能够引起类似EMT的形态改变,在处理3、4和5 d时细胞形态改变尤为明显,大多数细胞变为纺锤形;免疫荧光实验结果显示,细胞骨架的分布随细胞形态发生改变;实时荧光定量PCR结果显示,SNAI1在3 h和Ecadherin在6 h的mRNA表达量显著升高;α-SMA和β-catenin的mRNA表达量在各时间点均显著降低;SNAI1和Ecadherin的mRNA表达量在1 d时显著升高,随后各时间点mRNA表达量都呈现不同程度的下降,SNAI1在3和4 d时mRNA表达量显著降低,α-SMA在2、4和5 d时mRNA表达量显著降低;E-cadherin各时间点mRNA表达量都呈现不同程度的降低,2、3和5 d的mRNA表达量显著降低;β-catenin的mRNA表达量在不同时间点均无显著变化。结论:TGF-β1刺激HBEC可观察到发生类似EMT的细胞形态改变,但EMT标志基因mRNA的表达量变化反复。     

肺泡型细胞内表皮生长因子和转化生长因子α、β_1及其受体基因表达的研究

分离培养成年大鼠的肺泡 型细胞 ,通过斑点杂交、原位杂交和免疫组织化学染色 ,研究肺泡 型细胞内表皮生长因子 (EGF)、转化生长因子 α和 β1 (TGFα、TGFβ1 )及其受体基因的表达。结果显示肺泡 型细胞可表达 EGF、TGFα和TGFβ1 ,也可表达相应的 EGF受体 (EGFR)、TGFβ受体 型和 型 (TβR 、TβR )。表明肺泡 型细胞是合成和分泌 EGF、TGFα和 TGFβ1 的细胞之一 ;细胞凭借其 EGFR、TβR的存在 ,其增殖与分化可能受 EGF、TGFα和 TGFβ1 的旁分泌和自分泌两种途径调控。     

转化生长因子

转化生长因子(transforming growth fact-or,简称TGF)最初是指小鼠肉瘤病毒转化3 T3细胞系所产生的肉瘤生长因子。由于其能刺激正常细胞在软琼脂层锚着不依赖性生长,故后被称为TGF。进一步发现TGF包括TGFα和TGFβ。虽然两者名字类似,但结构和功能却彼此截然不同。越来越多的证据表明,TGF除了能使正常细胞转化外,在细胞增殖、生长和分化等基本活动中行使多种重要的调节作用和其他生物学效应。     

肺泡Ⅱ型细胞表皮生长因子和转化生长因子α、β1及其受体表达的研究

分离培养成年大鼠的肺泡Ⅱ型细胞,通过斑点杂交、原位杂交和免疫组织化学染色,研究肺泡Ⅱ型细胞内表皮生长因子（EGF）、转化生长因子α和β1（TGFα、TGFβ1）及其受体基因的表达。结果显示肺泡Ⅱ型细胞可表达EGF、TGFα和TGFβ1,也可表达相应的EGF受体（EGFR）、TGFβ受体Ⅰ型和Ⅱ型（TβRⅠ、TβRⅡ）。表明肺泡Ⅱ型细胞是合成和分泌EGF、TGFα和TGFβ1的细胞之一;细胞凭借其EGFR、TβR的存在,其增殖与分化可能受EGF、TGFα和TGFβ1的旁分泌和自分泌两种途径调控。     

Amphiregulin exosomes increase cancer cell invasion

Autocrine, paracrine, and juxtacrine are recognized modes of action for mammalian EGFR ligands including EGF, TGF-α (TGFα), amphiregulin (AREG), heparin-binding EGF-like growth factor (HB-EGF), betacellulin, epiregulin, and epigen. We identify a new mode of EGFR ligand signaling via exosomes. Human breast and colorectal cancer cells release exosomes containing full-length, signaling-competent EGFR ligands. Exosomes isolated from MDCK cells expressing individual full-length EGFR ligands displayed differential activities; AREG exosomes increased invasiveness of recipient breast cancer cells 4-fold over TGFα or HB-EGF exosomes and 5-fold over equivalent amounts of recombinant AREG. Exosomal AREG displayed significantly greater membrane stability than TGFα or HB-EGF. An average of 24?AREG molecules are packaged within an individual exosome, and AREG exosomes are rapidly internalized by recipient cells. Whether the composition and behavior of exosomes differ between nontransformed and transformed cells is unknown. Exosomes from DLD-1?colon cancer cells with a mutant KRAS allele exhibited both higher AREG levels and greater invasive potential than exosomes from isogenically matched, nontransformed cells in which mutant KRAS was eliminated by homologous recombination. We speculate that EGFR ligand signaling via exosomes might contribute to diverse cancer phenomena such as field effect and priming of the metastatic niche.     

Transforming growth factor-beta (TGF beta) inhibits TGF alpha expression in bovine anterior pituitary-derived cells.

Transforming growth factor-beta 1 (TGF beta 1) is a multifunctional regulator of cell growth and differentiation. We report here that TGF beta 1 decreased the proliferation of nontransformed bovine anterior pituitary-derived cells grown in culture. We have previously demonstrated that these cells express both TGF alpha and its receptor [the epidermal growth factor (EGF) receptor] and that expression can be stimulated by phorbol ester (TPA) and EGF. TGF beta 1 treatment over a 2-day period decreased the proliferation of pituitary cells. This decreased growth rate was accompanied by a decrease in the TGF alpha mRNA level. The effect of TGF beta 1 on TGF alpha mRNA down-regulation was both dose dependent (maximal effect observed at 1.0 ng/ml TGF beta 1) and time dependent (minimum of 2-day treatment with TGF beta 1 was required before a decrease in TGF alpha mRNA was observed). Studies on TGF alpha mRNA stability indicated that TGF beta 1 did not alter the TGF alpha mRNA half-life. Treatment of the TGF beta 1 down-regulated cells with EGF resulted in the stimulation of TGF alpha mRNA levels; thus, the TGF beta 1-treated cells remained responsive to EGF. The decreased proliferation in response to TGF beta 1 could be only partially reversed by simultaneous treatment of the cells with EGF (10(-9)M) and TGF beta 1 (3.0 ng/ml). Qualitatively, the TGF beta 1-induced reduction of TGF alpha mRNA content was independent of cell density. TGF beta 1 treatment of the anterior pituitary-derived cells also reduced the levels of c-myc and EGF receptor mRNA. These results represent the first demonstration of the down-regulation of TGF alpha synthesis by a polypeptide growth factor and suggest that TGF beta 1 may be a physiological regulator of TGF alpha production in vivo.     

Growth regulation of ovarian cancer cells by epidermal growth factor and tranforming growth factors α and β1

Regulation of ovarian cancer growth is poorly understood. In this study, the effects of EGT, TGFα and TGFβ1 on two ovarian cancer cell lines (OVCAR-3 and CAOV-3) were investigated. The results showed that EGF/TGFα stimulated cell growth and DNA synthesis in OVCAR-3 cell, but inhibited cell proliferation and DNA synthesis in CAOV-3 cells. TGFβ1 invariably inhibited cell proliferation and DNA synthesis in both cell lines. These efefects on growth factors are dose dependent. The interaction of TGFβ1 and EGF/TGFα was antagonistic in OVCAR-3 cells. In contrast, EGF/TGFα and TGFβ1 had an additive inhibitory effect on CAOV-3 cells. Our results demonstrated that mature and functional EGF receptors are present in both cell lines and that they are capable of ligand binding, internalization, processing and ligand-enhanced autophosphorylation. Both high- and low-affinity binding are present in these cell lines, with CAOV-3 cells having about 2–3 fold higher total receptors than OVCAR-3 cells. These results together with those from our previous studies show that these cells express TGFα, TGFβ1 and EGF receptors and that cell growth may be modulated by these growth factors in an autocrine can paracrine manner. This report presents evidence supporting the important roles of growth factors in ovarian cancer growth and provides a foundation for futher study into the mechanism of growth regulation by growth factors in these cell lines.     

Selective expression of high molecular weight basic fibroblast growth factor confers a unique phenotype to NIH 3T3 cells.

The phenotypes of NIH 3T3 cells transfected with basic fibroblast growth factor (bFGF) cDNAs that express only the high molecular weight (HMW) forms of bFGF, the 18-kDa form, or all forms were examined. Cells producing the 18 kDa or all forms of bFGF were transformed at high levels of growth factor expression but were nontransformed at low levels. Cell producing low levels of HMW forms of bFGF were growth impaired when compared with the parental cells. These cells tended to form multinucleated giant cells, did not grow in soft agar, were nontumorigenic, had a normal bFGF receptor number, and had a nontransformed morphology. Cells expressing high levels of HMW bFGFs had a transformed morphology and were tumorigenic. These data suggest a specific functional role for HMWbFGF.     

Vectorial TGFβ signaling in polarized intestinal epithelial cells

Polarized gastrointestinal epithelial cells form tight junctions that spatially separate apical and basolateral cell membrane domains. These domains harbor functionally distinct proteins that contribute to cellular homeostasis and morphogenesis. Transforming growth factor β (TGFβ) is a critical regulator of gastrointestinal epithelial cell growth and differentiation. Functional assays of vectorial TGFβ signaling and immunofluorescence techniques were used to determine the localization of TGFβ receptors and ligand secretion in polarizing Caco‐2 cells, a colon cancer cell line. Results were compared to the nontransformed MDCK cell line. In both Caco‐2 and MDCK cells, addition of TGFβ1 to the basolateral medium resulted in phosphorylation of Smad2. No phosphorylation was observed when TGFβ1 was added to the apical chamber, indicating that receptor signaling is localized at the basolateral membrane. In support of this, immunofluorescence and biotinylation assays show receptor localization along the basolateral membrane. Secretion of TGFβ1 from MDCK and Caco‐2 cells into the apical or basolateral medium was measured by ELISA. Interestingly, secretion was exclusively apical in the nontransformed MDCK line and basolateral in transformed Caco‐2 cells. Collectively, these results show basolateral domain specificity in localization of the TGFβ receptor signaling apparatus. These observations have important implications for understanding the biology of TGFβ in polarized epithelia, including elements of communication between epithelial and mesenchymal layers, and will prove useful in the design of therapeutics that target TGFβ function. J. Cell. Physiol. 224: 398–404, 2010. © 2010 Wiley‐Liss, Inc.     

B cell stimulatory factor-1/interleukin-4 mRNA is expressed by normal and transformed mast cells

BSF-1/interleukin-4, a product of activated T cells, has multiple biological activities that affect cells of most hematopoietic lineages. Among these is the ability of BSF-1 to costimulate the growth of mast cells and regulate the production of IgE. We demonstrate here that BSF-1 mRNA is expressed by a majority of transformed mast cell lines and by 5 IL-3-dependent non-transformed mast cell lines. BSF-1 activity, including the ability to enhance the growth of IL-3-dependent mast cells, was detected in the supernatants of transformed mast cells. The role of BSF-1 as a mast cell growth factor, its constitutive production by transformed mast cells, and the lack of IL-3 production by most of these cells raise the possibility that BSF-1 may act as an autocrine growth factor for some transformed mast cells. Furthermore, production of BSF-1 mRNA by nontransformed cells indicates that mast cells may be an important physiologic source of this factor.