DADS通过MAPK和PI3K/Akt 信号通路下调Mcl-1诱导白血病细胞凋亡*

目的:二烯丙基二硫（DADS）为天然植物大蒜中的提取物,能抑制多种肿瘤细胞生长,本文探讨丝裂原激活的蛋白激酶（MAPKs）、3- 磷酸肌醇激酶（PI 3K/Akt）信号通路和Bcl- 2 家族成员在DADS诱导的人白血病HL- 60细胞凋亡中的作用。方法:利用流式细胞术检测DADS 诱导的白血病细胞凋亡,Western blot研究MAPKs和PI 3K/Akt信号通路在DADS 诱导的人白血病HL- 60细胞凋亡中的变化及对Bcl- 2 家族凋亡相关蛋白表达的影响。结果:DADS呈浓度和时间依赖性地诱导人白血病HL- 60细胞凋亡,在此过程中ERK/MAPK 和PI 3K/Akt信号通路被抑制,而p38MAPK 信号通路被激活,ERK/MAPK 和PI 3K/Akt信号通路通过降低Mcl-1（myeloid cell leukemia-1）和升高Bax 的表达诱导人白血病细胞凋亡,而p38MAPK 则不是通过调控Mcl-1 和Bax 的表达诱导人白血病细胞凋亡,进一步利用RNA干扰技术沉默Mcl-1 基因可增加DADS对HL- 60细胞增殖抑制和诱导凋亡作用。结论:MAPK 和PI 3K/Akt信号通路通过下调Mcl-1 的表达参与了DADS诱导的HL- 60细胞凋亡作用。      

PI3K/Akt信号转导通路在恶性肿瘤中的研究进展

信号转导通路的异常改变是肿瘤细胞的重要生物学特性,其中PI3K/Akt信号转导通路在维持细胞恶性生物学特性中起重要作用。细胞在一系列内外因素的作用下,通过启动PI3K/Akt信号转导通路,诱导细胞的增殖、分化,避免细胞发生凋亡。近年来研究表明,PI3K/Akt信号转导通路在肿瘤细胞恶性增殖、血管新生和转移以及对放化疗的拮抗中起着重要作用。本文就PI3K/Akt信号转导通路的结构特点、调节过程及其对放化疗的影响作一综述。     

PI3K/Akt信号通路与肿瘤血管新生的研究进展

PI3K/Akt信号通路在多种细胞中活化,参与细胞的增殖、分化、凋亡、血管新生等病理、生理过程。血管的生成需要PI3K/Akt信号通路的激活,PI3K/Akt活化后可以广泛诱导鸡胚尿囊膜血管的生成。PI3K/Akt信号通路与其下游信号分子mTOR及多种促血管新生因子,如VEGF、HIF等相互作用,从而促进肿瘤血管新生。PI3K/Akt信号通路抑制剂能够抑制其血管新生作用,因此靶向PI3K/Akt信号通路为恶性肿瘤靶向治疗提供了新方法。     

PTEN信号转导通路与肿瘤的多药耐药

基因调控、信号转导通路异常均可引起细胞增殖失控,导致肿瘤发生。肿瘤细胞对化疗药物耐药是肿瘤患者死亡的主要原因。细胞内药物有效浓度的降低、DNA损伤的修复障碍、基因的突变及异常表达、信号转导通路的异常等均参与了肿瘤细胞的多药耐药。张力蛋白同源10号染色体缺失的磷酸酶基因（phosphatase and tension homology deleted on chromosome ten gene,PTEN）是具有磷酸酶活性的抑癌基因,在多种肿瘤细胞中异常表达,主要通过抑制PI3K/Akt/mTOR（mammalian target of rapamycin, mTOR）等多种信号转导通路参与细胞的增殖、凋亡及化疗耐药。因此,上调野生型PTEN的表达,或使用PI3K/Akt/mTOR信号通路抑制剂,可逆转肿瘤细胞的多药耐药,提高传统化疗的疗效。     

PI3K/Akt信号传导通路在妇科肿瘤中的研究进展

磷脂酰肌醇3激酶/蛋白激酶B( PI3K/Akt)信号传导通路具有重要的细胞调节功能,对肿瘤的发生、发展也发挥着重要的作用.本文主要探讨PI3K/Akt信号转导途径与妇科肿瘤的关系.     

PI3K/Akt信号转导通路与Basal-like型乳腺癌的分子治疗

磷脂酰肌醇-3激酶/蛋白激酶B (PI3K/Akt)信号转导通路与肿瘤的发生、发展密切相关.研究表明,PI3K/Akt信号通路的活化具有促进乳腺癌细胞增殖及减少细胞凋亡、分化的作用.基底细胞样(Basal-like)乳腺癌是乳腺癌的一种亚型,因其分子表型独特无明确的治疗靶点且恶性程度高、预后差.随着对PI3K/Akt信号转导通路及基底细胞样型乳腺癌发生、发展的研究不断深入,开发应用PI3K/Akt信号通路抑制剂可能为Basal-like型乳腺癌提供有效的分子治疗药物.     

PI3K/Akt/mTOR信号通路抑制剂在乳腺癌中的研究进展

目的:总结PI3K/Akt/mTOR信号通路靶向治疗在乳腺癌中的研究进展.方法:以“PI3K/Akt/mTOR、信号通路和乳腺癌”等为关键词,检索2000-01-2011-06 PubMed、Ovid和Springer等数据库的相关文献.纳入标准:1)关于PI3K/Akt/mTOR信号通路的组成、功能特点;2)PI3K/Akt/mTOR信号通路与乳腺癌的关系研究;3)以PI3K/Akt/mTOR信号通路中关键分子为靶点的乳腺癌治疗.根据纳入标准,符合分析的文献40篇.结果:信号转导通路的异常是肿瘤发生、发展的重要步骤,PI3K/Akt/mTOR信号通路与人类多种肿瘤密切相关,其在肿瘤细胞的增殖、存活、抵抗凋亡、血管发生和转移以及对放化疗抵抗中发挥了重要作用.乳腺癌中常见PI3K/Akt/mTOR信号通路的异常激活,以此通路为靶点的药物已成为乳腺癌治疗的研究热点.结论:靶向PI3K/Akt/mTOR通路中关键分子的众多药物在乳腺癌开展了一系列相关的临床试验研究,一部分显示出较好的安全性和有效性.随着对PI3K/Akt/mTOR通路的分子生物学机制的深入研究,期待靶向此通路的抑制剂将会在乳腺癌治疗中发挥巨大的作用,进一步提高乳腺癌患者的疗效和改善预后.     

PI3K—Akt信号通路与胃癌的研究进展

细胞内信号传导通路PI3K—Akt与胃癌的发生、生长及化疗耐药关系密切。本文概述了PI3K—Akt的分类结构、PI3K—Akt信号转导通路的调节、与胃癌细胞凋亡及血管生成的关系及化疗耐药和放疗的机制。     

VES对MDA-MB-453细胞PI3K/Akt信号通路的影响

目的：检测维生素E琥珀酸酯（vitamin E succinate,VES）对MDA-MB-453乳腺癌细胞PI3K/Akt信号通路中PI3K及Akt表达的影响。方法：不同浓度VES作用于人乳腺癌细胞MDA-MB-453（Her-2过表达株）24h和48h,VES的浓度分别为5、10和20μg/ml。RT-PCR法检测VES作用前后PI3K及Akt的mR-NA表达变化。结果：VES对MDA-MB-453乳腺癌细胞PI3 K/Akt信号通路中PI3 K有抑制作用（P〈0.05）,并呈时间-剂量依赖关系;而对Akt无明显的抑制作用（P〉0.05）。结论：VES可能是通过作用于PI3K/Akt信号通路而发挥其对MDA-MB-453乳腺癌细胞的抑制及凋亡作用。     

PI3K/Akt/mTOR信号传导通路与恶性肿瘤浸润和转移的研究进展

PI3K/Akt/mTOR信号通路作为细胞内重要信号传导通路之一,通过影响下游多种效应分子的活化状态,在细胞内发挥着抑制凋亡、促进增殖的关键作用,它与人类多种肿瘤的发生发展密切相关.本文综述了PI3K/Akt/mTOR信号通路的组成与功能、调节以及其抗肿瘤细胞凋亡作用机理等方面的研究进展,并就其抗细胞凋亡作用在肿瘤治疗中的应用作了评述,期待为以PI3K/Akt/mTOR信号通路中关键分子为靶点的肿瘤治疗研究提供参考.     

5-aza-2'-deoxycytidine enhances susceptibility of renal cell carcinoma to paclitaxel by decreasing LEF1/phospho-β-catenin expression

We investigated the molecular mechanisms by which 5-aza-2′-deoxycytidine (DAC) and paclitaxel (PTX) use lymphoid enhancer-binding factor 1 (LEF1) and the Wnt/β-catenin pathway to synergistically interact against renal cell carcinoma (RCC). LEF1 expression was examined by real-time PCR and immunohistochemistry. The regulation of LEF1/β-catenin protein expression by DAC and/or PTX was examined by Western blot and immunoprecipitation. To analyze the effect of LEF1 on the proliferative ability of RCC cells and the synergy of DAC and PTX against RCC cells, an expression vector containing the full-length cDNA for LEF1 was transfected into RCC cells, and LEF1 expression was also decreased using siRNA technology. Our results confirmed that DAC and PTX synergistically decreased the expression of LEF1 in vivo and in vitro. Moreover, treatment of RCC cell lines with the combination of DAC and PTX caused a synergistic decrease in LEF1/phospho-β-catenin. Our study also demonstrated a negative correlation between LEF1 expression and the proliferative ability of RCC cells. Although interfering with LEF1 expression did not abolish the synergy between the two agents, RCC cells expressing high levels of LEF1 displayed an increased synergistic effect compared with RCC cells expressing low levels of LEF1. This study suggests that LEF1 can enhance the proliferation of RCC cells and that the LEF1/β-catenin complex plays an important role in the synergy of DAC and PTX against RCC cells. Moreover, the synergy between DAC and PTX may be more effective in RCC cells expressing high levels of LEF1.     

苦参碱对视网膜母细胞瘤细胞增殖、凋亡及PI3K/Akt信号通路的影响

目的 探讨苦参碱（Mat）对视网膜母细胞瘤细胞Y79细胞增殖、凋亡及PI3K/Akt信号通路的影响。方法 Y79细胞经0.5、1.0、1.5 g/L Mat处理24 h后,采用CCK-8试剂盒检测细胞增殖情况,磷酯酰丝氨酸结合蛋白-异硫氢酸荧光素/碘化丙啶（Annexin V-FITC/PI）双标记流式细胞术检测细胞凋亡情况,Western blotting免疫印迹检测各浓度Mat处理后凋亡相关蛋白Bcl-2及Bax、PI3K/Akt信号通路重要蛋白PI3K p85亚基、Akt及其磷酸化形式p-Akt的蛋白水平。结果 不同浓度Mat作用Y79细胞24 h后,可呈浓度依赖性方式抑制细胞增殖,增加细胞凋亡率（P＜0.05）。Western blotting检测发现,Mat可明显增加促凋亡蛋白Bax表达,降低抗凋亡蛋白Bcl-2水平并可降低PI3K p85α亚基及磷酸化Akt的蛋白水平（P＜0.05）,对总Akt水平无明显影响。结论 Mat可抑制人视网膜母细胞瘤增殖并诱导其凋亡,可能与抑制PI3K/Akt 信号通路有关。     

Differentiating mTOR inhibitors in renal cell carcinoma

PI3K/Akt/mTOR signalling is dysregulated in many cancers, including renal cell carcinoma (RCC), and activation of this pathway has been suggested to correlate with aggressive behavior and poor prognosis in RCC tumors. mTOR inhibition plays a principal role in the targeted treatment of many cancer types, including RCC. Although mTOR inhibitors share the same mechanism of action, differences in metabolism, formulation and dosing schedule underpin distinct PK/PD profiles such that they may be differentiated for use in a variety of treatment niches. Approved mTOR inhibitors temsirolimus and everolimus serve as important therapeutic options within the current RCC treatment paradigm, although their recommended applications differ in setting and patient population characteristics. Clinical practice guidelines recommend temsirolimus for use in treatment-naive patients with poor-prognosis metastatic RCC of any histology (predominant clear cell or non-clear cell histology). Everolimus provides a standard-of-care therapy for patients with metastatic RCC whose disease has progressed after previous vascular endothelial growth factor receptor-tyrosine kinase inhibitor therapy. As therapeutic failure impacts the vast majority of patients with RCC, sequencing strategies of available agents or simultaneous targeting of multiple members of the PI3K/Akt/mTOR pathway may provide additional clinical benefit. Various classes of agents targeting the PI3K/Akt/mTOR pathway are currently being investigated, including mTORC1/mTORC2 kinase domain inhibitors, mTOR/PI3K dual inhibitors, PI3K-selective inhibitors, and programmed cell death 6 modulators. Clinical trials of mTOR inhibitors in a variety of tumor types are ongoing, and the role of mTOR inhibitors continues to evolve across the RCC treatment landscape.     

PI3K/Akt/mTOR pathway inhibitors in the therapy of pancreatic neuroendocrine tumors

The phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is implicated in the pathogenesis of pancreatic neuroendocrine tumors (pNETs). Activation of this pathway is driven by aberrant tyrosine kinase receptor activities. Mutations in the PI3K/Akt/mTOR pathway occur in 15% of pNETs, and expression of genes of the PI3K/Akt/mTOR pathway is altered in the majority of pNETs. The mTOR inhibitor everolimus has been approved by the FDA for the treatment of pNET, but its efficacy may be limited by its inability to prevent mTORC2-mediated activation of Akt. Specific inhibitors of PI3K, Akt, or other pathway nodes, and their concomitant use with mTOR inhibitors, or agents with dual activity, may be more effective. Preclinical studies demonstrate that inhibitors of the PI3K pathway have antitumor activity in pNET cells, either through direct inhibition of individual pathway nodes or indirect inhibition of molecular chaperones such as heat-shock protein 90. Clinical studies are underway evaluating individual node and dual node inhibitors.     

COX-2抑制剂Mavacoxib对骨肉瘤干细胞增殖、凋亡及相关信号通路的影响

目的 探讨COX-2抑制剂Mavacoxib对骨肉瘤干细胞增殖、凋亡及相关信号通路的影响。方法 体外培养人骨肉瘤MG-63细胞以获取骨肉瘤干细胞,经Mavacoxib（0、1、10、50、100 μmol/L）处理后采用四甲基偶氮唑盐（MTT）比色法检测增殖抑制率的变化,同时采用流式细胞术Annexin-FITC/PI双染法及PI单染法检测不同浓度Mavacoxib处理24、48 h的凋亡情况（早、晚期凋亡率）及48 h的细胞周期情况,Western blotting检测不同浓度Mavacoxib 处理48 h的骨肉瘤干细胞中PI3K/Akt及Wnt/β-catenin信号通路的影响。结果 在10～100 μmol/L范围内,Mavacoxib可呈剂量和时间依赖的方式升高骨肉瘤干细胞的增殖抑制率,差异均有统计学意义（P＜0.05）;与0 μmol/L相比,除1 μmol/L 24 h的晚期凋亡率无统计学差异,10～100 μmol/L的早晚期凋亡率、G0/G1期细胞比例均升高,S期、G2/M期细胞比例均降低（P＜0.05）。Mavacoxib处理后的PI3K/Akt通路中的PTEN水平升高,Akt水平降低;Wnt/β-catenin通路中β-catenin、C-myc和Cyclin D1水平均降低（P＜0.05）。结论 Mavacoxib 对骨肉瘤干细胞有毒性作用,且可诱导其凋亡及细胞周期阻滞并抑制PI3K/Akt和Wnt/β-catenin信号通路的激活。     

慢病毒载体介导SHIP基因抑制K562细胞增殖及对P13K／Akt信号通路的调控

背景与目的：SHIP基因主要表达于造血细胞,通过降解PIP3抑制P13K／Akt信号通路而在造血细胞增殖和存活中起重要负调控作用。本研究通过慢病毒载体介导SHIP基因转染K562细胞,探讨SHIP基因改变及功能丢失与白血病发病的关系。方法：将携带SHIP基因的慢病毒感染K562细胞．FQ—PCR法检测SHIP转录水平,Western blot法检测转染后SHIP蛋白表达及Akt磷酸化水平的变化;比较SHIP基因表达前后细胞增殖、形态的变化。结果：K562细胞中SHIP蛋白阴性。以携带SHIP基因的慢病毒载体转染K562细胞后．细胞增殖抑制率升高,K562-wtSHIP—FIV—G细胞的增殖抑制率由转染第3天的（9．9±1．5）％升到第5天的（40．6±2．3）％;伴有Akt磷酸化水平明显减弱;转染后,K562．wtSHIP—FIV—G组细胞p-Akt的表达水平由0．533降低到0．245（P〈0．01）,细胞增殖明显被抑制。此外,SHIP蛋白还能使K562细胞出现凋亡特征,Hoechst33342染色结果转染wtSHIP基因组K562细胞第5天早期凋亡率[（38．3±4．3）％]明显高于K562-FIV—G组细胞[（8．2±0．9）％]和未转染组K562细胞[（7．7±0．8）％]。结论：SHIP基因具有重要的抑制细胞增殖和促进凋亡的能力,SHIP基因缺失导致K562细胞P13K／Akt信号途径失调,促进K562细胞增殖。     

P13-K抑制剂LY294002逆转P-gP介导的白血病和胃癌细胞耐药

背景与目的：磷脂酰肌醇3-激酶／蛋白激酶B[phosphatidylinositol-3-kinase（P13-K）／proteinkinaseB（Akt）,P13-K／Aktl通路是调控细胞生存的重要信号转导通路之一。本研究旨在探讨P13-K抑制剂LY294002对P-gP过表达的人类白血病K562／DNR和胃癌SGC7901／ADR细胞多药耐药性的逆转作用。方法：将细胞分为单纯药物组和LY294002预处理组,单纯药物组分别以柔红霉素（daunorubicin,DNR）、阿霉素（adriamycin,ADR）、长春新碱（vincristine,VCR）和依托泊甙（etoposide,VP-16）处理,LY294002预处理组在加药前以LY294002进行预处理。用台盼蓝拒染法及MTT法检测药物敏感性及LY294002对细胞耐药性的影响。Westernblot检测K562／DNR和SGC7901／ADR细胞中P．gP及p-Akt的表达。流式细胞术检测细胞内药物浓度。结果：2．5μmol／LLY294002预处理显著降低DNR、ADR、VCR和VP-16对K562／DNR细胞的IC50,相对逆转效率分别为72．4％、64．9％、60．4％和52．8％。此外,LY294002部分逆转SGC7901／ADR对ADR的耐药性,相对逆转效率为31．0％。LY294002预处理可部分抑制p-Akt和P-gP的表达。随着处理时间的延长．K562／DNR、SGC7901／ADR细胞内DNR、ADR的蓄积效应有增强的趋势。结论：LY294002通过抑制P13-K／Akt信号转导通路,部分逆转P-gp介导的白血病和胃癌细胞的多药耐药。     

Potential Targets for Prevention of Colorectal Cancer: a Focus on PI3K/Akt/mTOR and Wnt Pathways

Colorectal cancer (CRC) is one of the most common cancers in many parts of the world. Its development is a multi-step process involving three distinct stages, initiation that alters the molecular message of a normal cell, followed by promotion and progression that ultimately generates a phenotypically altered transformed malignant cell. Reports have suggested an association of the phosphoinositide-3-kinase (PI3K)/Akt pathway with colon tumorigenesis. Activation of Akt signaling and impaired expression of phosphatase and tensin homolog (PTEN) (a negative regulator of Akt) has been reported in 60-70% of human colon cancers and inhibitors of PI3K/Akt signaling have been suggested as potential therapeutic agents. Around 80% of human colon tumors possess mutations in the APC gene and half of the remainder feature β-catenin gene mutations which affect downstream signaling of the PI3K/Akt pathway. In recent years, there has been a great focus in targeting these signaling pathways, with natural and synthetic drugs reducing the tumor burden in different experiment models. In this review we survey the role of PI3K/Akt/mTOR and Wnt signaling in CRC.