磷脂酰肌醇-3激酶/蛋白激酶B信号系统

质膜成分磷脂酰肌醇被其3位激酶(PI3K)活化后,可以使蛋白激酶B(PKB)由细胞浆定位于胞膜,继而被磷酸化激活。PKB是原癌基因akt的产物,具有丝/苏氨酸蛋白激酶活性,介导细胞代谢、生长、增殖等效应。PI3K/PKB系统是近年来发现的一个生长因子信号转导通路。     

磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶(PI3K/Akt)信号转导通路与子宫颈癌关系的研究现状

磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶(phosphateidylinositol 3 kinase/serine-threonine kinase,PI3K/Akt)信号转导通路作为细胞内重要的信号转导通路之一,通过诱导肿瘤细胞的增殖、抗凋亡、促进肿瘤血管的形成及拮抗放化疗等作用在肿瘤的演变过程中起着重要的作用.研究显示,PI3K/Akt信号转导通路与宫颈癌的发生、发展关系密切.本文就PI3K/Akt信号转导通路的结构与功能及其调控机制,在肿瘤发生、发展中的作用以及与子宫颈癌关系的研究进展作一综述.     

蛋白激酶A抑制剂H-89通过调节核糖体蛋白S6激酶1的磷酸化阻断SP600125诱导的CMK细胞多倍体化北大核心CSCD

目的研究核糖体蛋白S6激酶1(S6K1)翻译后修饰在巨核细胞倍体化调控方面的作用。方法 c-Jun氨基末端激酶(JNK)抑制剂SP600125和蛋白激酶A(PKA)抑制剂H-89单独或联合处理CMK原始巨核细胞白血病细胞。碘化丙啶(PI)染色,结合流式细胞术检测DNA的相对量,从而进行DNA倍体分析;Western blot法检测哺乳动物雷帕霉素靶蛋白(m TOR)下游靶分子S6K1表达和磷酸化修饰(Thr389和Thr421/Ser424)的变化。使用分子对接和激酶活性检测分析H-89与S6K1结合的关系以及对激酶活性的影响。结果 SP600125以时间和剂量依赖的方式诱导CMK细胞多倍体化,同时,上调S6K1的Thr421/Ser424磷酸化和下调Thr389的磷酸化。H-89不但部分阻断SP600125诱导CMK细胞多倍体化,而且下调S6K1的Thr421/Ser424磷酸化和上调Thr389磷酸化。分子对接和激酶活性分析发现H-89通过占据ATP结合位点,抑制S6K1活性。值得注意的是,H-89和SP600125均抑制PKA的活性,而且两者联合进一步抑制了PKA的活性,表明H-89阻断SP600125诱导CMK多倍体化与其对PKA的作用无关,而与S6K1磷酸化修饰状态的改变有关。结论 H-89通过调节S6K1磷酸化阻断SP600125诱导CMK细胞多倍体化。     

蛋白激酶A抑制剂H-89通过调节核糖体蛋白S6激酶1的磷酸化阻断SP600125诱导的CMK细胞多倍体化

目的研究核糖体蛋白S6激酶1(S6K1)翻译后修饰在巨核细胞倍体化调控方面的作用。方法 c-Jun氨基末端激酶(JNK)抑制剂SP600125和蛋白激酶A(PKA)抑制剂H-89单独或联合处理CMK原始巨核细胞白血病细胞。碘化丙啶(PI)染色,结合流式细胞术检测DNA的相对量,从而进行DNA倍体分析;Western blot法检测哺乳动物雷帕霉素靶蛋白(m TOR)下游靶分子S6K1表达和磷酸化修饰(Thr389和Thr421/Ser424)的变化。使用分子对接和激酶活性检测分析H-89与S6K1结合的关系以及对激酶活性的影响。结果 SP600125以时间和剂量依赖的方式诱导CMK细胞多倍体化,同时,上调S6K1的Thr421/Ser424磷酸化和下调Thr389的磷酸化。H-89不但部分阻断SP600125诱导CMK细胞多倍体化,而且下调S6K1的Thr421/Ser424磷酸化和上调Thr389磷酸化。分子对接和激酶活性分析发现H-89通过占据ATP结合位点,抑制S6K1活性。值得注意的是,H-89和SP600125均抑制PKA的活性,而且两者联合进一步抑制了PKA的活性,表明H-89阻断SP600125诱导CMK多倍体化与其对PKA的作用无关,而与S6K1磷酸化修饰状态的改变有关。结论 H-89通过调节S6K1磷酸化阻断SP600125诱导CMK细胞多倍体化。     

儿茶素通过蛋白激酶B抑制兔晶状体上皮细胞增殖

目的:探讨绿茶提取物表没食子儿茶素没食子酸酯(EGCG)抑制兔晶状体上皮细胞增殖时,磷脂酰肌醇-3(羟基)激酶/蛋白激酶B(PI3K/PKB)信号转导通路所起的作用。方法: 用组织块培养法获取新西兰白兔晶状体上皮细胞,用噻唑蓝比色法(MTT比色法)研究晶状体上皮细胞增殖作用;用Western blot法研究PKB的磷酸化和非磷酸化水平。结果: (1)预先分别加入25,50 μmol/L的PI3K的特异性抑制剂LY294002孵育1 h后,100、200 μmol/L EGCG对晶状体上皮细胞的抑制率明显大于对照组(P＜0.05),而50 μmol/L EGCG无抑制作用(P＞0.05)。(2)在晶状体上皮细胞,磷酸化的PKB 基础水平很高;加入200 μmol/L EGCG时PKB磷酸化水平轻度增加,但随EGCG浓度的下降而逐渐减弱;加入EGCG后早期,PKB的磷酸化水平最高,随时间的延长而逐渐下降。各组的非磷酸化PKB水平始终保持不变。结论: EGCG可能通过调控PKB的磷酸化水平而抑制晶状体上皮细胞的增殖,并不影响总蛋白含量。     

白细胞介素-4对哮喘大鼠T淋巴细胞磷脂酰肌醇-3激酶表达的影响

磷脂酰肌醇-3激酶(PI3K)是T淋巴细胞内重要的信号转导分子,它通过催化底物磷脂酰肌醇发生磷酸化而将活化信号传人细胞内。有研究显示PI3K途径介导了生理情况下IL-4受体诱导的T细胞增殖。IL-4是否通过对哮喘T细胞PI3K通路的作用影响了T细胞的增殖目前尚不清楚。通过对IL-4处理的不同组之间T细胞PI3K表达的研究,探讨IL-4对哮喘T细胞PI3K的影响。     

FoxO3a与肿瘤的发生和发展

叉头转录因子O亚型(forkhead box O,FoxO)3a是FoxO家族一员,具有抑癌基因的作用,调控多种肿瘤的发生发展,包括乳腺癌、前列腺癌、白血病、胶质母细胞瘤等。FoxO3a作为磷脂酰肌醇3-激酶/蛋白激酶B(phosphatidylinositol 3-kinase/protein kinase B,PI3K/Akt)信号通路的重要靶分子,主要通过AKT磷酸化与去磷酸化起作用,调节其活性以及下游信号分子如细胞死亡调解因子、Fas配体和细胞周期蛋白依赖性激酶等转录作用,诱导肿瘤细胞凋亡。药物调控FoxO3a的活性和分布有望成为癌症治疗的新思路。     

Akt/PKB异常与消化系统肿瘤的研究进展

Akt/PKB信号通路是细胞内信号传导的重要环节,参与腚细胞代谢、生存/凋亡、分化和增殖等过程.细胞内Akt/PKB活性状态依赖于其磷酸化与去磷酸化之间的平衡.蛋白磷酸酶PP2A使Akt/PKB去磷酸化而失活,而Ser/Thr蛋白磷酸酶抑制剂冈田酸(okadaic acid)可以增加活化的Akt/PKB.Akt/PKB信号通路调节异常可见于肿瘤、糖尿病甚至精神分裂症等.肿瘤组织中Akt/PKB活性水平高可以是Akt/PKB信号通路上游调节异常造成的,如P13K亚基或:PTEN的基因突变,或者Akt/PKB基凶扩增造成的.Akt/PKB被认为参与了多种肿瘤的发生、发展及侵袭转移.近年Akt/PKB信号通路正逐渐成为肿瘤发牛机制及治疗的研究热点,本文就Akt/PKB异常与消化系统肿瘤的研究进展作一综述.     

Ghrelin活化人T细胞翻译起始分子通过mTOR信号转导通路

目的:探讨Ghrelin活化人T细胞翻译起始分子的信号转导机理。方法:采用微柱法分离人外周血T细胞,采用Western blot方法检测mTOR信号通路分子和蛋白质翻译调控分子的磷酸化状态和含量。采用mTOR抑制剂:雷帕霉素,PI3KⅠ抑制剂:LY294002,PI3KⅢ抑制剂:3-甲基腺嘌呤,Ghrelin拮抗剂:Des-Lys-3-GHRP6和AKT抑制剂:A443654和Ghrelin研究相应信号通路。结果:①人T细胞表面有Ghrelin受体(GHSR1a)表达。②Ghrelin与GHSR1a结合后可活化mTOR。③Ghrelin磷酸化两个mTOR下游靶分子4E-BP-1和P70 S6K,P70 S6K进一步磷酸化核糖体S6蛋白。④Ghrelin磷酸化蛋白质翻译起始帽子结构的两个重要分子eIF4E和eIF4G。结论:Ghrelin促进人T细胞mRNA翻译起始的机理是活化mTOR信号转导通路。     

PI3K/AKT信号通路调控股骨头坏死的相关机制

文题释义： 股骨头坏死：又称股骨头缺血性坏死,由多种因素造成股骨头血供障碍,从而引起软骨下区的软骨细胞和骨细胞得不到所需的营养物质而坏死并伴随局部骨质疏松,最终因外力导致股骨头塌陷。该病常易引起股骨头功能活动障碍,致残率较高,已成为骨科临床常见复杂性疾病之一。 PI3K/AKT信号通路：磷脂酰肌醇(PI3K)是一种位于胞质的脂质激酶,而AKT是PI3K通路中的一种关键激酶(丝氨酸/苏氨酸激酶),亦名蛋白激酶。AKT激活需要丝氨酸473(AktSer473)和苏氨酸308(Akt-Thr 308)的膜相互作用和磷酸化,经多种因素刺激后,PH结构域与PI3K产生的磷脂酰肌醇3,4,5-三磷酸(PIP3)相互作用,使胞浆AKT进入质膜;接着Akt-PIP3相互作用,通过域间构象变化将AKT诱导为开放的构象异构体,暴露Thr308和Ser473以用于磷酸肌醇依赖性蛋白激酶的后续磷酸化,而Thr308和Ser473的磷酸化完全激活AKT,从而通过磷酸化各种下游激酶,参与多种调节细胞的增殖和发育,在多个领域如癌症、血管再生、骨质疏松发挥了重要的调节作用从而通过磷酸化各种下游激酶,参与多种调节细胞的增殖和发育,在多个领域如癌症、血管再生、骨质疏松发挥了重要的调节作用。 背景：近年来随着医学研究不断深入,发现PI3K/AKT信号通路对血管修复再生、成骨细胞分化增殖、破骨细胞骨分化有调控作用,这对治疗股骨头坏死来说至关重要。 目的：就近年来PI3K/AKT信号通路调控股骨头坏死相关机制的主要研究进展做一简要概述,旨在为今后股骨头坏死的治疗提供新思路。 方法：检索PubMed、MEDLINE数据库、万方、CNKI、维普及中国生物医学文献数据库2012至2019年相关国内外文献,包括：①股骨头坏死的流行病学及相关病因病机研究文献;②PI3K/AKT通路相关机制研究文献;③PI3K/AKT对血管修复再生相关因素的影响研究文献;④PI3K/AKT对成骨细胞分化增殖相关因素调控的研究文献;⑤PI3K/AKT对破骨细胞分化等功能相关因素的调控研究文献。共纳入62篇文献分析总结。 结果与结论：①PI3K/AKT信号通路经多项动物实验已证实可对血管修复再生、成骨细胞分化增殖凋亡与破骨细胞分化相关因素进行有效调控,在认识这些通路机制基础上研发相关药物提高股骨头坏死早期保守治疗成功率具有远大发展前景及潜力,为未来治疗股骨头坏死开辟了新道路,也给患者及其家属带来新希望;②而根据患者不同股骨头坏死情况如何运用PI3K/AKT信号通路指导治疗成为该项技术的突破点及挑战,需要后期更多研究去探索。 ORCID: 0000-0002-3771-335X(宋世雷) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Cytokine-mediated inhibition of apoptosis in non-transformed T cells and neutrophils can be dissociated from protein kinase B activation

In the absence of survival-inducing cytokines activated T cells and neutrophils enter apoptosis spontaneously. Phosphatidylinositol 3-kinase (PI3 K) activation and signaling through PKB/AKT have been widely linked to the inhibition of apoptosis by cytokines. Here we have investigated the role of PKB in the inhibition of spontaneous apoptosis of activated human CD4+ T cells and neutrophils. We used a range of cytokines known to induce survival and/or activation of PKB. We found activation of PKB in T cells treated with IL-2 and insulin, and neutrophils cultured with N-formyl-Met-Leu-Phe (fMLP), insulin or granulocyte-macrophage colony-stimulating factor. Insulin did not inhibit apoptosis in neutrophils or T cells and fMLP did not delay neutrophil apoptosis. Intriguingly, IFN-beta induced PI3 K-dependent survival in both cell types, but did not activate PKB. IL-2 mediated rescue of T cells from apoptosis but no induction of proliferation occurred in thepresence of LY294002, an inhibitor of PI3 K, which also blocked subsequent PKB activation. The main role of PI3 K in IL-2-mediated signaling may therefore be in the regulation of proliferation. These findings suggest that activation of PKB and inhibition of apoptosis can be dissociated in cytokine-mediated rescue of non-transformed CD4+ T cells and neutrophils.     

Ligation of the T cell co-stimulatory receptor CD28 activates the serine-threonine protein kinase protein kinase B

The intracellular signaling pathways activated upon ligation of the co-stimulatory receptor CD28 remain relatively ill-defined, although CD28 ligation does result in the strong association with, and activation of, phosphatidylinositol (PI) 3-kinase. The downstream effector targets of the CD28-activated PI 3-kinase-dependent signaling pathway remain poorly defined, but recent evidence from other systems has shown that Akt/protein kinase B (PKB) is a major target of PI 3-kinase and have indicated that a major function of PKB is the regulation of cell survival events. Given the strong coupling of CD28 to PI 3-kinase and the known protective effects of both CD28 and PI 3-kinase against apoptosis in different cell models, we investigated the effects of CD28 on PKB activation. We demonstrate that ligation of CD28 by either anti-CD28 monoclonal antibodies or the natural ligand B7.1, results in the marked activation of PKB in both the leukemic T cell line Jurkat and freshly isolated human peripheral blood-derived normal T lymphocytes. Our data suggest therefore, that PKB may be an important intracellular signal involved in CD28 signal transduction and demonstrate CD28 coupling to downstream elements of a signaling cascade known to promote cell survival.     

Neuroprotection by c-Jun NH2-terminal kinase inhibitor SP600125 against potassium deprivation–induced apoptosis involves the Akt pathway and inhibition of cell cycle reentry

Increasing evidence implicates the c-Jun NH₂-terminal kinase (JNK) pathway in the regulation of apoptosis in neurodegenerative diseases. In this study, we examined the neuroprotective effect of SP600125, a selective JNK inhibitor, in cerebellar granule cells (CGNs) deprived of serum and potassium (S/K withdrawal). S/K withdrawal-induced apoptosis occurs via activation of multiple pro-apoptotic pathways, including re-entry into the cell cycle, activation of glycogen synthase kinase-3 beta (GSK-3β), cyclin-dependent kinase 5 (cdk5/p35) breakdown, formation of cdk5/p25 and JNK activation. Here we demonstrate that SP600125 is able to inhibit all these pro-apoptotic pathways via the inhibition of JNK. Further, we found that JNK inhibition maintains the phosphorylation/activation of Akt after S/K withdrawal. For further confirmation of this result, we studied several targets downstream of Akt including GSK-3β, p-FOXO1, p-CREB and p35. In addition, the specific PI3K/Akt inhibitor LY294002 greatly diminished the antiapoptotic effects of SP600125 upon S/K withdrawal, confirming that Akt is involved in the neuroprotection achieved by SP600125. These results suggest that the maintenance of the PI3-kinase/Akt pathway by inhibition of JNK contributes to the prevention of apoptosis in rat cerebellar granule neurons mediated by S/K withdrawal. Furthermore, we propose that JNK may regulate the cell cycle re-entry by a novel mechanism that involves Akt, GSK-3β and Rb phosphorylation.     

Adrenaline potentiates insulin-stimulated PKB activation in the rat fast-twitch epitrochlearis muscle without affecting IRS-1-associated PI 3-kinase activity

We have previously shown in the rat slow-twitch soleus muscle that adrenaline greatly potentiates insulin-stimulated protein kinase B (PKB) phosphorylation without having an effect alone. However, insulin signalling capacity through the PKB pathway is higher in soleus than in fast-twitch muscles, whereas adrenaline activates phosphorylase more strongly in epitrochlearis. Therefore, the aim of the present study was to investigate the interaction between adrenaline and insulin signalling in the fast-twitch epitrochlearis muscle. Insulin increased insulin receptor substrate-1 (IRS-1)-associated phosphoinositide (PI) 3-kinase activity threefold, and adrenaline did not influence basal or insulin-stimulated PI 3-kinase activity. Insulin but not adrenaline increased PKB activity and phosphorylation of Ser(473) and Thr(308). It is interesting to note that adrenaline potentiated insulin-stimulated PKB activity and PKB Ser(473) and Thr(308) phosphorylation. These effects were mimicked by dibutyryl-cyclic adenosine monophosphate (db-cAMP). Adrenaline and db-cAMP increased glycogen synthase kinase (GSK)-3beta Ser(9) phosphorylation independently of PKB activation and enhanced insulin-stimulated GSK-3beta Ser(9) phosphorylation. Although adrenaline increased GSK-3 phosphorylation (inhibiting activity), phosphorylation of its target sites on glycogen synthase was increased, and adrenaline blocked insulin-stimulated glycogen synthase dephosphorylation of Ser(641) and Ser(645,649,653,657), glycogen synthase activation and glycogen synthesis. Insulin-stimulated glucose transport was not influenced by adrenaline despite the increased PKB activation. In conclusion, as in the slow-twitch soleus muscle, adrenaline potentiates insulin-stimulated PKB activation in the fast-twitch glycolytic epitrochlearis muscle without increasing IRS-1-associated PI 3-kinase activity. Furthermore, adrenaline induces phosphorylation of a pool of GSK-3 that is not involved in the regulation of glycogen metabolism. These results indicate that the combination of adrenaline and insulin may activate novel signalling molecules rather than just summing up their effects on linear pathways.     

PKB在类胰蛋白酶诱导基因表达中的作用

目的：探讨蛋白激酶B(PKB)在类胰蛋白酶（tryptase）诱导基因表达中的作用。 方法： 采用RT-PCR和Western blotting 方法，检测tryptase对ECV304细胞PKB（Akt）的表达及其活性和对转录因子AP-1、NF-κB p65亚单位、JNK、p38MAPK、趋化因子IL-8表达的影响。 结果： 在ECV304中1 μg/L tryptase可使PKB蛋白质磷酸化水平增加并促进PKB、转录因子NF-κB P65亚单位、AP-1和趋化因子IL-8的表达，但对JNK、p38MAPK表达影响不大。PI3K特异性抑制剂LY294002可抑制PKB的表达增加，同时可抑制NF-κB P65亚单位和IL-8的表达增加；反义PKB质粒瞬时转染ECV304，可抑制PKB、AP1、NF-κB P65亚单位和IL-8的表达增加；PAR2的抗体可抑制PKB的磷酸化，但不能阻断PKB表达。 结论： 在ECV304细胞tryptase经其膜受体PAR2通过PI3K促进PKB的磷酸化而激活之，通过其下游途径促进趋化因子IL-8、转录因子AP-1、NF-κB P65亚单位和PKB本身的表达增加。     

Real-time quantitative RT-PCR identifies distinct c-RET, RET/PTC1 and RET/PTC3 expression patterns in papillary thyroid carcinoma

RET/PTC1 and RET/PTC3 are the markers for papillary thyroid carcinoma. Their reported prevalence varies broadly. Nonrearranged c-RET has also been detected in a variable proportion of papillary carcinomas. The published data suggest that a wide range in expression levels may contribute to the different frequency of c-RET and, particularly, of RET/PTC detection. However, quantitative expression analysis has never been systematically carried out. We have analyzed by real-time RT-PCR 25 papillary carcinoma and 12 normal thyroid samples for RET/PTC1, RET/PTC3 and for RET exons 10-11 and 12-13, which are adjacent to the rearrangement site. The variability in mRNA levels was marked and four carcinoma groups were identified: one lacking RET/PTC rearrangement with balanced RET exon levels similar to those of the normal samples (7/25 cases, 28%), the second (6/25 cases, 24%) with balanced RET expression and very low levels of RET/PTC1, the third with unbalanced RET exons 10-11 and 12-13 expression, high RET/PTC1 levels but no RET/PTC3 (7/25 cases, 28%), and the fourth with unbalanced RET expression, high RET/PTC1 levels and low levels of RET/PTC3 (5/25 cases, 20%). Papillary carcinomas with high RET/PTC1 expression showed an association trend for large tumor size (P=0.063). Our results indicate that the variability in c-RET and RET/PTC mRNA levels contributes to the apparent inconsistencies in their reported detection rates and should be taken into account not only for diagnostic purposes but also to better understand the role of c-RET activation in thyroid tumorigenesis.     

RET oncogene activation in papillary thyroid carcinoma.

The RET proto-oncogene encodes a cell membrane tyrosine-kinase receptor protein whose ligands belong to the glial cell line-derived neurotrophic factor. RET functions as a multicompetent receptor complex that includes alphaGFRs and RET. Somatic rearrangements of RET designated as RET/PTC (from papillary thyroid carcinoma) were identified in papillary thyroid carcinoma before RET was recognized as the susceptibility gene for MEN2. There are now at least at least 15 types of RET/PTC rearrangements involving RET and 10 different genes. RET/PTC1 and RET/PTC3 are by far the most common rearrangements. All of the rearrangements are due to DNA damage and result in the fusion of the RET tyrosine-kinase (RET-TK) domain to the 5'-terminal region of heterologous genes. RET/PTC rearrangements are very common in radiation-induced tumors but have been detected in variable proportions of sporadic (i.e., non-radiation associated) papillary carcinomas. It is estimated that up to approximately half the papillary thyroid carcinomas in the United States and Canada harbor RET/PTC rearrangements, most commonly RET/PTC-1, followed by RET/PTC-3 and occasionally RET/PTC-2. The cause of these rearrangements in sporadic papillary carcinomas is not known, but the close association between their presence and the papillary carcinoma phenotype indicates that they play a causative role in tumor development. The proposed mechanisms of RET/PTC-induced tumorigenesis and the clinical and pathologic implications of RET/PTC activation are discussed.     

Potent mitogenicity of the RET/PTC3 oncogene correlates with its prevalence in tall-cell variant of papillary thyroid carcinoma.

The tall-cell variant (TCV) of papillary thyroid carcinoma (PTC), characterized by tall cells bearing an oxyphilic cytoplasm, is more clinically aggressive than conventional PTC. RET tyrosine kinase rearrangements, which represent the most frequent genetic alteration in PTC, lead to the recombination of RET with heterologous genes to generate chimeric RET/PTC oncogenes. RET/PTC1 and RET/PTC3 are the most prevalent variants. We have found RET rearrangements in 35.8% of TCV (14 of 39 cases). Whereas the prevalences of RET/PTC1 and RET/PTC3 were almost equal in classic and follicular PTC, all of the TCV-positive cases expressed the RET/PTC3 rearrangement. These findings prompted us to compare RET/PTC3 and RET/PTC1 in an in vitro thyroid model system. We have expressed the two oncogenes in PC Cl 3 rat thyroid epithelial cells and found that RET/PTC3 is endowed with a strikingly more potent mitogenic effect than RET/PTC1. Mechanistically, this difference correlated with an increased signaling activity of RET/PTC3. In conclusion, we postulate that the correlation between the RET/PTC rearrangement type and the aggressiveness of human PTC is related to the efficiency with which the oncogene subtype delivers mitogenic signals to thyroid cells.     

Overexpression of wild-type c-RET and zero prevalence of RET/PTC rearrangements are associated with papillary thyroid cancer (PTC) in Kuwait

Background

Papillary thyroid carcinoma (PTC) is common in Kuwait. The activation of the RET oncogene by DNA rearrangement (RET/PTC) is known to have an important role in PTC carcinogenesis. However, the real frequency of the RET/PTC expression in PTC is variable between different studies. This study seeks to determine the prevalence of RET/PTC and to analyze the RET oncogene expression associated with PTC in Kuwait.

Methods

RET expression and DNA rearrangements (RET/PTC 1, RET/PTC 2 and RET/PTC 3) were studied by RT–PCR in different thyroid diseases. Results were confirmed by the Southern blot and by immunohistochemistry. Quantitative real-time PCR was used to determine the level of RET mRNA expression in PTCs.

Results

Wild-type (nonrearranged) c-RET oncogene was overexpressed in 60% of PTC cases and absent in follicular thyroid carcinoma (FTC), anaplastic thyroid carcinoma (ATC), follicular adenomas (FA) or normal thyroid. No RET/PTC rearrangement was detected in any sample. The c-RET expression in Hashimoto's thyroiditis and multinodular goiter was limited to follicular cells with PTC-like nuclear changes.

Conclusions

The overexpression of wild-type c-RET is a characteristic molecular event of PTCs in Kuwait. The prevalence of RET/PTC is zero and among the lowest recorded in the world.