PI3K/Akt/mTOR信号通路与自噬及肿瘤的关系北大核心CSCD

自噬是一种以胞质内出现双层膜结构包裹长寿命蛋白和细胞器的自噬体为特征的细胞"自我消化"过程,在维持细胞内稳态、发育、肿瘤发生和感染中发挥重要作用。近来,诸多研究表明,自噬作为一把"双刃剑",对肿瘤的发生发展既有促进作用,也有抑制作用。PI3K/Akt/m TOR通路由PI3激酶(PI3K)、蛋白激酶B(PKB/Akt)和哺乳动物类雷帕霉素靶蛋白(m TOR)3个作用分子组成,是一个中心的调节机构,对肿瘤细胞的生长与增殖有促进作用,同时对自噬进行抑制。本文就PI3K/Akt/m TOR通路与自噬及肿瘤发生发展的关系作一综述。     

PI3K/Akt/mTOR信号通路及临床相关肿瘤抑制剂

哺乳动物雷帕霉素靶（mTOR）和蛋白激酶B（Akt/PKB）与肿瘤发生的密切关系已被广泛地认可.mTOR是一种丝/苏氨酸激酶,可以通过影响mRNA转录、代谢、自噬等方式调控细胞的生长.它既是PI3K的效应分子,也可以是PI3K的反馈调控因子.mTORC1 和mTORC2是mTOR的两种不同复合物. 对雷帕霉素敏感的mTORC1受到营养、生长因子、能量和应激4种因素的影响.生长因子通过PI3K/Akt信号通路调控mTORC1是最具特征性调节路径.而mTORC2最为人熟知的是作为Akt473磷酸化位点的上游激酶. 同样,Akt/PKB在细胞增殖分化、迁移生长过程中发挥着重要作用. 随着Thr308和Ser473两个位点激活,Akt/PKB也得以全面活化.因此,mTORC2-Akt-mTORC1的信号通路在肿瘤形成和生长中是可以存在的.目前临床肿瘤治疗中,PI3K/Akt/mTOR是重要的靶向治疗信号通路.然而,仅抑制mTORC1活性,不是所有的肿瘤都能得到预期控制.雷帕霉素虽然能抑制mTORC1,但也能反馈性地增加PI3K信号活跃度,从而影响治疗预后.近来发现的第二代抑制剂可以同时抑制mTORC1/2和PI3K活性,这种抑制剂被认为在肿瘤治疗上颇具前景.本综述着重阐述了PI3K/Akt/mTOR信号通路的传导、各因子之间的相互调控以及相关抑制剂的发展.     

白藜芦醇经PI3K/Akt/mTOR 信号通路诱导人肾癌786-O细胞自噬

白藜芦醇(resveratrol)可抑制人肾癌786-O细胞增殖,并诱导其凋亡,但是白藜芦醇对786-O细胞自噬(autophagy)的影响及机制尚不清楚。为探究其机制,体外培养786-O细胞,采用CCK-8检测786-O细胞活力;TUNEL染色检测786-O细胞凋亡;透射电子显微镜观察786-O细胞自噬体;吖啶橙染色观察786-O细胞自噬小泡;GFP-LC3质粒转染分析观察786-O细胞自噬体;Western印迹检测LC3、beclin-1、PI3K、p-PI3K、Akt、p-Akt、mTOR和p-mTOR的表达。结果显示,白藜芦醇以浓度和时间依赖性的方式抑制786-O细胞活力,并诱导细胞凋亡;与对照组相比,白藜芦醇使786-O细胞自噬增强;Western印迹结果显示,与对照组相比,白藜芦醇组LC3-II/LC3-I和Beclin-1显著增高(P0.01),表明白藜芦醇导致786-O细胞自噬体积累。与对照组相比,白藜芦醇使786-O细胞的p-PI3K/PI3K,p-Akt/Akt和p-mTOR/mTOR显著降低(P0.01),表明白藜芦醇可通过PI3K/Akt/mTOR信号通路增强自噬。综上所述,白藜芦醇通过抑制PI3K/Akt/mTOR信号通路从而诱导786-O细胞自噬。     

RhoGDI2与PI3K/Akt/mTOR信号通路在肺癌细胞中的相关性研究

目的探讨肿瘤转移相关因子RhoGDI2与PI3K/Akt/mTOR信号通路在肺癌侵袭转移过程中的作用及相关机制。方法利用PI3K/Akt/mTOR信号通路上特异性的抑制剂,采用MTT法,伤口愈合实验及侵袭实验观察不同浓度药物对肺癌95D细胞生长侵袭转移能力的影响,通过Western Blot方法观察RhoGDI2蛋白水平的变化。结果PI3K抑制剂LY294002及mTOR抑制剂Rapamycin都能抑制肺癌细胞95D的侵袭转移能力,联合应用抑制作用更强。PI3K抑制剂LY294002处理组RhoGDI2蛋白的表达量增加,且随浓度增加RhoGDI2蛋白表达也增加。mTOR抑制剂Rapamycin组,在低浓度时增加RhoGDI2蛋白的表达,但增大Rapamycin的浓度,RhoGDI2蛋白的表达反而降低。低浓度LY294002组和Rapa-mycin组联合应用可以明显增加RhoGDI2蛋白的表达。结论PI3K/Akt/mTOR信号通路中Akt的活化与RhoGDI2密切相关,RhoGDI2可能直接或间接通过与Akt的相互作用参与调节肺癌的侵袭转移的过程。     

PI3K/Akt/mTOR信号传导通路与成人T淋巴细胞白血病关系的研究进展

成人T淋巴细胞白血病(ATL)是严重危害人类健康的一种疾病,它是由与H IV类似的逆转录病毒HTLV-I感染CD4+T细胞而诱发的恶性肿瘤。HTLV-Ⅰ导致ATL中起主要作用的是Tax蛋白,其反式激活作用占有重要地位,它可以激活PI3K/AKT/mTOR信号途径。PI3K/Akt/mTOR被认为是蛋白质合成的主要信号调节通路,研究表明该信号传导通路是与细胞增殖和细胞凋亡关系最密切的信号传导通路之一,其在成人T淋巴细胞白血病的发生、发展治疗及转归中发挥重要作用,并且已经成为治疗的新靶点。本文就PI3K/Akt/mTOR信号传导通路以及与ATL关系的研究进展作如下综述。     

miR-145、miR-186表达与非小细胞肺癌组织临床病理特征和PI3K/Akt/ mTOR信号通路的关系

摘要 目的：探讨微小核糖核酸（miR）-145、miR-186表达与非小细胞肺癌（NSCLC）临床病理特征和磷脂酰肌醇3-激酶（PI3K）/蛋白激酶B（Akt）/哺乳动物雷帕霉素靶蛋白（mTOR）信号通路的关系。方法：选择2020年3月至2023年3月我院收治的128例行肺癌根治手术治疗的NSCLC患者,取其术中癌组织和癌旁组织（距离癌组织5 cm以上）,采用实时荧光定量聚合酶链式反应（qRT-PCR）检测miR-145、miR-186以及PI3K mRNA、Akt mRNA、mTOR mRNA表达。分析miR-145、miR-186表达与NSCLC患者临床病理特征的关系;Pearson检验分析NSCLC患者癌组织miR-145、miR-186表达与PI3K mRNA、Akt mRNA、mTOR mRNA表达的相关性。结果：癌组织miR-145、miR-186表达低于癌旁组织（P＜0.05）,低分化、TNM ⅢA期、淋巴结转移的NSCLC组织miR-145、miR-186表达低于中高分化、TNM Ⅰ～Ⅱ期、未发生淋巴结转移的NSCLC组织（P＜0.05）。癌组织PI3K mRNA、Akt mRNA 、mTOR mRNA表达均高于癌旁组织（P＜0.05）,癌组织miR-145、miR-186表达与PI3K mRNA、Akt mRNA、mTOR mRNA表达均呈负相关（P＜0.05）。结论：NSCLC组织中miR-145、miR-186表达下调,miR-145、miR-186表达下调可能激活PI3K/ Akt/mTOR信号通路促使NSCLC进展,且与NSCLC患者癌组织低分化、TNM ⅢA期、淋巴结转移有关。     

圣草酚调控Akt/mTOR通路对胶质瘤细胞自噬的影响CSCD

为研究圣草酚对胶质瘤细胞自噬的影响,探讨其通过调控Akt/mTOR通路在胶质瘤自噬过程中的作用。本研究采用CCK8和细胞克隆形成实验检测圣草酚对胶质瘤细胞增殖的影响。构建GFP-mRFP-LC3B稳定表达的细胞株,圣草酚(100μmol/L)处理48 h,观察自噬小体的形成情况;然后分别用圣草酚(100μmol/L)、雷帕霉素(200 nmol/L)以及圣草酚(100μmol/L)+雷帕霉素(200 nmol/L)处理48 h后观察自噬流的情况。利用蛋白免疫印迹法检测圣草酚对自噬及Akt/mTOR通路相关蛋白表达水平的影响。建立裸鼠皮下移植瘤模型,观察圣草酚在体内对胶质瘤自噬过程的影响。实验结果显示,圣草酚能够显著抑制胶质瘤细胞的增殖,且呈时间—剂量依赖性(P<0.05)。圣草酚使胶质瘤细胞中绿色自噬小体明显增多,LC3Ⅱ、Beclin 1、ATG5蛋白表达上调。圣草酚处理GFP-mRFP-LC3B稳转细胞株48 h后呈亮黄色,且减弱了雷帕霉素对自噬流的促进作用,并上调P62蛋白的表达。此外,圣草酚可抑制p-Akt、p-mTOR的表达,但该作用被Akt激动剂740 Y-P逆转。体内实验结果同体外一致。说明圣草酚能够抑制胶质瘤细胞的增殖和自噬流,其影响自噬过程的作用机制可能与下调Akt/mTOR通路有关。     

基于PI3K/AKT/mTOR通路的三百棒促进脂多糖诱导的RAW 264.7细胞自噬并抑制炎症CSCD

三百棒来源于芸香科植物飞龙掌血Toddalia asiatica(L.)Lam的根,是一种天然土家族中草药,具有抗炎、抗风湿、抗肿瘤、抗微生物等药理活性。其毒副作用小,疗效显著的特点使之成为当前研究热点。许多天然产物已被证明可通过靶向PI3K/AKT/mTOR介导的自噬来抑制炎症及自身免疫性疾病,本项研究通过调节PI3K/AKT/mTOR信号通路来研究三百棒醇提物(Toddalia asiatica alcohol extract,TAAE)对自噬的影响,用脂多糖(LPS)诱导单核巨噬细胞(RAW 264.7)建立炎症模型,通过细胞毒性检测试剂盒检测TAAE对细胞活力的影响,并筛选出药物的浓度及干预时间,透射电镜和单丹磺酰尸胺染色检测巨噬细胞的生物学功能,酶联免疫吸附法检测上清液中相关炎症因子水平,Western blot检测自噬和通路相关蛋白的表达水平;并采用自噬早期抑制剂(3-MA)和通路PI3K激动剂(740Y-P)进一步验证自噬对炎症和信号通路的影响。实验结果表明TAAE可能通过抑制PI3K/AKT/mTOR信号通路,促进自噬泡的形成、自噬体溶酶体融合和降解,降低LPS处理的RAW 264.7细胞中炎性细胞因子的表达和分泌。总体而言,本研究结果为三百棒的抗炎机制的研究提供了新的线索,并为临床更好的应用三百棒治疗炎症性疾病提供理论依据。     

PI3K/Akt信号传导通路与肿瘤

信号转导通路的异常激活是肿瘤细胞的发生、发展重要步骤,PI3K/Akt 信号通路在人类绝大多数恶性肿瘤中被异常激活,其在肿瘤的增殖、存活、细胞运动、抵抗凋亡、血管发生和转移以及对化疗耐药、放疗抗拒中发挥了重要作用.因此,通过对PI3K/Akt 通路的研究进一步了解肿瘤的发生、发展机制,并寻求抗肿瘤药物的新靶点,本文就 PI3K/Akt 信号转导通路的结构特点、与肿瘤发生、发展的关系及其时放化疗的影响作一综述.     

硫化氢与自噬:一把双刃剑

硫化氢(hydrogen sulfide, H_2S)被认为是第三种气体信号分子,在许多生理及病理生理情况下发挥重要的调节作用。然而,在硫化氢对自噬的作用这一方面仍有一些争论。许多信号通路参与硫化氢的促自噬作用,例如AMPK/mTOR、LKB1/STRAD/MO25以及MiR-30c信号通路。同时,也有许多信号通路在硫化氢的抗自噬作用中发挥重要作用,例如SR-A、PI3K/SGK1/GSK3β、PI3K/AKT/mTOR、Nrf2-ROS-AMPK、AMPK/mTOR以及JNK1信号通路。在治疗人类疾病时,可以设计研发新型硫化氢相关药物,通过调节自噬增加疗效。本文主要讨论硫化氢在其介导的自噬信号通路中的作用。     

Coordinate Autophagy and mTOR Pathway Inhibition Enhances Cell Death in Melanoma

The phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway promotes melanoma tumor growth and survival while suppressing autophagy, a catabolic process through which cells collect and recycle cellular components to sustain energy homeostasis in starvation. Conversely, inhibitors of the PI3K/AKT/mTOR pathway, in particular the mTOR inhibitor temsirolimus (CCI-779), induce autophagy, which can promote tumor survival and thus, these agents potentially limit their own efficacy. We hypothesized that inhibition of autophagy in combination with mTOR inhibition would block this tumor survival mechanism and hence improve the cytotoxicity of mTOR inhibitors in melanoma. Here we found that melanoma cell lines of multiple genotypes exhibit high basal levels of autophagy. Knockdown of expression of the essential autophagy gene product ATG7 resulted in cell death, indicating that survival of melanoma cells is autophagy-dependent. We also found that the lysosomotropic agent and autophagy inhibitor hydroxychloroquine (HCQ) synergizes with CCI-779 and led to melanoma cell death via apoptosis. Combination treatment with CCI-779 and HCQ suppressed melanoma growth and induced cell death both in 3-dimensional (3D) spheroid cultures and in tumor xenografts. These data suggest that coordinate inhibition of the mTOR and autophagy pathways promotes apoptosis and could be a new therapeutic paradigm for the treatment of melanoma.     

Inhibition of autophagy enhances apoptosis induced by the PI3K/AKT/mTor inhibitor NVP‐BEZ235 in renal cell carcinoma cells

The PI3K/AKT/mTOR pathway plays a key role in the development of the hypervascular tumor renal cell carcinoma (RCC). NVP‐BEZ235 (NVP), a novel dual PI3K/mTOR inhibitor, showed great antitumor benefit and provided a treatment strategy in RCC. In this study, we test the effect of NVP on survival rate, apoptosis and autophagy in the RCC cell line, 786‐0. We also explore the hypothesis that NVP, in combination with autophagy inhibitors, leads to apoptosis enhancement in 786‐0 cells. The results showed that the PI3K/AKT/mTOR pathway proteins p‐AKT and p‐P70S6K were highly expressed in RCC tissue. We also showed that NVP inhibited cell growth and induced apoptosis and autophagy in RCC cells. The combination treatment of NVP with autophagy inhibitors enhanced the effect of NVP on suppressing 786‐0 growth and induction of apoptosis. This study proposes a novel treatment paradigm where combining PI3K/AKT/mTOR pathway inhibitors and autophagy inhibitors lead to enhanced RCC cell apoptosis. Copyright © 2012 John Wiley & Sons, Ltd.     

PI3K/Akt/mTOR signaling orchestrates the phenotypic transition and chemo-resistance of small cell lung cancer

Small cell lung cancer(SCLC) is a phenotypically heterogeneous disease with an extremely poor prognosis,which is mainly attributed to the rapid development of resistance to chemotherapy. However, the relation between the growth phenotypes and chemo-resistance of SCLC remains largely unclear. Through comprehensive bioinformatic analyses, we found that the heterogeneity of SCLC phenotype was significantly associated with different sensitivity to chemotherapy. Adherent or semiadherent SCLC cells were enriched with activation of the PI3K/Akt/mTOR pathway and were highly chemoresistant. Mechanistically,activation of the PI3K/Akt/mTOR pathway promotes the phenotypic transition from suspension to adhesion growth pattern and confers SCLC cells with chemo-resistance. Such chemo-resistance could be largely overcome by combining chemotherapy with PI3K/Akt/mTOR pathway inhibitors. Our findings support that the PI3K/Akt/mTOR pathway plays an important role in SCLC phenotype transition and chemo-resistance,which holds important clinical implications for improving SCLC treatment.     

FRS2α is essential for the fibroblast growth factor to regulate the mTOR pathway and autophagy in mouse embryonic fibroblasts

Although the fibroblast growth factor (FGF) signaling axis plays important roles in cell survival, proliferation, and differentiation, the molecular mechanism underlying how the FGF elicits these diverse regulatory signals is not well understood. By using the Frs2α null mouse embryonic fibroblast (MEF) in conjunction with inhibitors to multiple signaling pathways, here we report that the FGF signaling axis activates mTOR via the FGF receptor substrate 2α (FRS2α)-mediated PI3K/Akt pathway, and suppresses autophagy activity in MEFs. In addition, the PI3K/Akt pathway regulated mTOR is crucial for the FGF signaling axis to suppress autophagy in MEFs. Since autophagy has been proposed to play important roles in cell survival, proliferation, and differentiation, the findings suggest a novel mechanism for the FGF signaling axis to transmit regulatory signals to downstream effectors.     

Vertical inhibition of the PI3K/Akt/mTOR pathway for the treatment of osteoarthritis

Osteoarthritis is characterized by degenerative alterations of articular cartilage including both the degradation of extracellular matrix and the death of chondrocytes. The PI3K/Akt pathway has been demonstrated to involve in both processes. Inhibition of its downstream target NF‐kB reduces the degradation of extracellular matrix via decreased production of matrix metalloproteinases while inhibition of mTOR increased autophagy to reduce chondrocyte death. However, mTOR feedback inhibits the activity of the PI3K/Akt pathway and inhibition of mTOR could result in increased activity of the PI3K/Akt/NF‐kB pathway. We proposed that the use of dual inhibitors of PI3K and mTOR could be a promising approach to more efficiently inhibit the PI3K/Akt pathway than rapamycin or PI3K inhibitor alone and produce better treatment outcome. J. Cell. Biochem. 114: 245–249, 2013. © 2012 Wiley Periodicals, Inc.     

hnRNP A1 promotes keratinocyte cell survival post UVB radiation through PI3K/Akt/mTOR pathway

hnRNP A1 acts as a critical splicing factor in regulating many alternative splicing events in various physiological and pathophysiological progressions. hnRNP A1 is capable of regulating UVB-induced hdm2 gene alternative splicing according to our previous study. However, the biological function and underlying molecular mechanism of hnRNP A1 in cell survival and cell cycle in response to UVB irradiation are still unclear. In this study, silencing hnRNP A1 expression by siRNA transfection led to decreased cell survival after UVB treatment, while promoting hnRNP A1 by lentiviruse vector resulted in increased cell survival. hnRNP A1 remarkably enhanced PI3K/Akt/mTOR signaling pathway by increasing phosphorylation of Akt, mTOR and P70S6 protein. Inhibition of PI3K/Akt signaling by LY294002 suppressed the expression of hnRNP A1. While mTOR signaling inhibitors, rapamycin and AZD8055, did not influence hnRNP A1 expression in HaCaT cells, suggesting that hnRNP A1 may be an upstream mediator of mTOR signaling. Furthermore, hnRNP A1 could alleviate UVB-provoked cell cycle arrest at G0/G1 phase and promoted cell cycle progression at G2/M phase. Our results indicate that hnRNP A1 promotes cell survival and cell cycle progression following UVB radiation.     

NCAM regulates the proliferation,apoptosis, autophagy,EMT, and migration of human melanoma cells via the Src/Akt/mTOR/cofilin signaling pathway

The neural cell adhesion molecule (NCAM) plays critical roles in multiple cellular processes in neural cells, mesenchymal stem cells, and various cancer cells. However, the effect and mechanism of NCAM in human melanoma cells are still unclear. In this study, we found that NCAM regulated the proliferation, apoptosis, autophagy, migration, and epithelial-to-mesenchymal transition of human melanoma cells by determining the biological behavior of NCAM knockdown A375 and M102 human melanoma cells. Further studies revealed that NCAM knockdown impaired the organization of actin cytoskeleton and reduced the phosphorylation of cofilin, an actin-cleaving protein. When cells were transfected with cofilin S3A (dephosphorylated cofilin), biological behavior similar to that of NCAM knockdown cells was observed. Research on the underlying molecular mechanism showed that NCAM knockdown suppressed activation of the Src/Akt/mTOR pathway. Specific inhibitors of Src and PI3K/Akt were employed to further verify the relationship between Src/Akt/mTOR signaling and cofilin, and the results showed that the phosphorylation level of cofilin decreased following inhibition of the Src/Akt/mTOR pathway. These results indicated that NCAM may regulate the proliferation, apoptosis, autophagy, migration, and epithelial-to-mesenchymal transition of human melanoma cells via the Src/Akt/mTOR/cofilin pathway-mediated dynamics of actin cytoskeleton.     

A mechanism for synergy with combined mTOR and PI3 kinase inhibitors

Dysregulation of the mammalian target of rapamycin (mTOR) signaling has been found in many human cancers, particularly those with loss of the tumor suppressor PTEN. However, mTORC1 inhibitors such as temsirolimus have only modest activity when used alone and may induce acquired resistance by activating upstream mTORC2 and Akt. Other tumors that do not depend upon PI3K/Akt/mTOR signaling for survival are primarily resistant. This study tested the hypothesis that the limited clinical efficacy of temsirolimus is due to a compensatory increase in survival signaling pathways downstream of Akt as well as an incomplete block of 4E-BP1-controlled proliferative processes downstream of mTOR. We explored the addition of a PI3K inhibitor to temsirolimus and identified the mechanism of combinatorial synergy. Proliferation assays revealed that BEZ235 (dual PI3K/mTOR inhibitor) or ZSTK474 (pan PI3K inhibitor) combined with temsirolimus synergistically inhibited cell growth compared to cells treated with any of the agents alone. Co-treatment resulted in G0/G1 cell cycle arrest and up-regulation of p27. Cell death occurred through massive autophagy and subsequent apoptosis. While molecular profiling revealed that, in most cases, sensitivity to temsirolimus alone was most marked in cells with high basal phospho-Akt resulting from PTEN inactivation, combining a PI3K inhibitor with temsirolimus prevented compensatory Akt phosphorylation and synergistically enhanced cell death regardless of PTEN status. Another molecular correlate of synergy was the finding that temsirolimus treatment alone blocks downstream S6 kinase signaling, but not 4E-BP1. Adding BEZ235 completely abrogated 4E-BP1 phosphorylation. We conclude that the addition of a PI3K inhibitor overcomes cellular resistance to mTORC1 inhibitors regardless of PTEN status, and thus substantially expands the molecular phenotype of tumors likely to respond.