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.     

Activation of phosphatidylinositol 3-kinase, Akt, and mammalian target of rapamycin is necessary for hypoxia-induced pulmonary artery adventitial fibroblast proliferation.

In contrast to cell types in which exposure to hypoxia causes a general reduction of metabolic activity, a remarkable feature of pulmonary artery adventitial fibroblasts is their ability to proliferate in response to hypoxia. Previous studies have suggested that ERK1/2, phosphatidylinositol 3-kinase (PI3K), Akt, and mammalian target of rapamycin (mTOR) are activated by hypoxia and play a role in a variety of cell responses. However, the pathways involved in mediating hypoxia-induced proliferation are largely unknown. Using pharmacological inhibitors, we established that PI3K-Akt, mTOR-p70 ribosomal protein S6 kinase (p70S6K), and EKR1/2 signaling pathways play a critical role in hypoxia-induced adventitial fibroblast proliferation. We found that exposure of serum-starved fibroblasts to 3% O2 resulted in a time-dependent activation of PI3K and transient phosphorylation of Akt. However, activation of PI3K was not required for activation of ERK1/2, implying a parallel involvement of these pathways in the proliferative response of fibroblasts to hypoxia. We found that hypoxia induced significant increases in mTOR, p70S6K, 4E-BP1, and S6 ribosomal protein phosphorylation, as well as dramatic increases in p70S6K activity. The activation of p70S6K/S6 pathway was sensitive to inhibition by rapamycin and LY294002, indicating that mTOR and PI3K/Akt are upstream signaling regulators. However, the magnitude of hypoxia-induced p70S6K activity and phosphorylation suggests involvement of additional signaling pathways. Thus our data demonstrate that hypoxia-induced adventitial fibroblast proliferation requires activation and interaction of PI3K, Akt, mTOR, p70S6K, and ERK1/2 and provide evidence for hypoxic regulation of protein translational pathways in cells exhibiting the capability to proliferate under hypoxic conditions.     

B7-H4-mediated immunoresistance is supressed by PI3K/Akt/mTOR pathway inhibitors

B7-H4 plays an important role in tumor immune evasion. In previous studies we have found that B7-H4 can translocate to the nucleus, and the exposure to PI3K inhibitor Ly294002 affects B7-H4 subcellular distribution. In this study we report the role of PI3K/Akt pathway in the B7-H4 subcellular distribution and the effect of PI3K/Akt inhibitors on B7-H4-mediated immunoresistance. The involvement of PI3K/Akt pathway in B7-H4 subcellular distribution was evident in experiments with wortmannin, while MDM2 inhibitor nutlin-3 and the mTOR inhibitor rapamycin were used to dissect the signaling downstream of Akt. Wortmannin and rapamycin demonstrated similar effects on B7-H4 subcellular distribution. Exposure to any of these inhibitors decreased levels of membrane B7-H4 while at the same time inducing its nuclear accumulation, while exposure to nutlin-3 had no effect on B7-H4 subcellular distribution. In the T cell proliferation assay, both wortmannin and rapamycin effectively inhibited B7-H4 WT/293 cells-mediated T cell proliferation while exerting no effect on Mock/293 cells. PI3K/Akt/mTOR plays a role in B7-H4 subcellular distribution, while MDM2 does not take part in it. Moreover, we show that wortmannin and rapamycin inhibit B7-H4-mediated tumor immunoresistance through regulating B7-H4 subcellular distribution. Taken together, these results suggest that PI3K/Akt/mTOR inhibitors might be used for adjuvant therapy aimed at inhibition of immune evasion.     

Phosphatidylinositol 3-kinase activation attenuates the TLR2-mediated macrophage proinflammatory cytokine response to Francisella tularensis live vaccine strain

An inadequate innate immune response appears to contribute to the virulence of Francisella tularensis following pulmonary infection. Studies in mice suggest that this poor response results from suppression of proinflammatory cytokine production early during infection, but the mechanisms involved are not understood. PI3K is known to regulate proinflammatory cytokine expression, but its exact role (positive versus negative) is controversial. We sought to clarify the role of PI3K in regulating proinflammatory signaling and cytokine production during infection with F. tularensis live vaccine strain (LVS). In this study, we demonstrate that the induction of TNF and IL-6 expression by LVS in mouse bone marrow-derived macrophages was markedly enhanced when PI3K activity was inhibited by either of the well-known chemical inhibitors, wortmannin or LY294002. The enhanced cytokine expression was accompanied by enhanced activation of p38 MAPK and ERK1/2, both of which were critical for LVS-induced expression of TNF and IL-6. LVS-induced MAPK activation and cytokine production were TLR2- and MyD88- dependent. PI3K/Akt activation was MyD88-dependent, but was surprisingly TLR2-independent. LVS infection also rapidly induced MAPK phosphatase-1 (MKP-1) expression; PI3K and TLR2 signaling were required. Peak levels of MKP-1 correlated closely with the decline in p38 MAPK and ERK1/2 phosphorylation. These data suggest that infection by LVS restrains the TLR2-triggered proinflammatory response via parallel activation of PI3K, leading to enhanced MKP-1 expression, accelerated deactivation of MAPKs, and suppression of proinflammatory cytokine production. This TLR2-independent inhibitory pathway may be an important mechanism by which Francisella suppresses the host's innate immune response.     

AKT isoforms modulate Th1‐like Treg generation and function in human autoimmune disease

Foxp3⁺ regulatory T cells (Tregs) exhibit plasticity, which dictates their function. Secretion of the inflammatory cytokine IFNγ, together with the acquisition of a T helper 1 (Th1)‐like effector phenotype as observed in cancer, infection, and autoimmune diseases, is associated with loss of Treg suppressor function through an unknown mechanism. Here, we describe the signaling events driving the generation of human Th1‐Tregs. Using a genome‐wide gene expression approach and pathway analysis, we identify the PI3K/AKT/Foxo1/3 signaling cascade as the major pathway involved in IFNγ secretion by human Tregs. Furthermore, we describe the opposing roles of AKT isoforms in Th1‐Treg generation ex vivo. Finally, we employ multiple sclerosis as an in vivo model with increased but functionally defective Th1‐Tregs. We show that the PI3K/AKT/Foxo1/3 pathway is activated in ex vivo‐isolated Tregs from untreated relapsing–remitting MS patients and that blockade of the pathway inhibits IFNγ secretion and restores the immune suppressive function of Tregs. These data define a fundamental pathway regulating the function of human Tregs and suggest a novel treatment paradigm for autoimmune diseases.     

Deoxycholyltaurine rescues human colon cancer cells from apoptosis by activating EGFR-dependent PI3K/Akt signaling

Recent studies indicate that secondary bile acids promote colon cancer cell proliferation but their role in maintaining cell survival has not been explored. We found that deoxycholyltaurine (DCT) markedly attenuated both unstimulated and TNF-alpha-stimulated programmed cell death in colon cancer cells by a phosphatidylinositol 3-kinase (PI3K)-dependent mechanism. To examine the role of bile acids and PI3K signaling in maintaining colon cancer cell survival, we explored the role of signaling downstream of bile acid-induced activation of the epidermal growth factor receptor (EGFR) in regulating both apoptosis and proliferation of HT-29 and H508 human colon cancer cells. DCT caused dose- and time-dependent Akt (Ser(473)) phosphorylation, a commonly used marker of activated PI3K/Akt signaling. Both EGFR kinase and PI3K inhibitors attenuated DCT-induced Akt phosphorylation and Akt activation, as demonstrated by reduced phosphorylation of a GSK-3-paramyosin substrate. Transfection of HT-29 cells with kinase-dead EGFR (K721M) reduced DCT-induced Akt phosphorylation. In HT-29 cells, EGFR and PI3K inhibitors as well as transfection with dominant negative AKT attenuated DCT-induced cell proliferation. DCT-induced PI3K/Akt activation resulted in downstream phosphorylation of GSK-3 (Ser(21/9)) and BAD (Ser(136)), and nuclear translocation (activation) of NF-kappaB, thereby confirming that DCT-induced activation of PI3K/Akt signaling regulates both proproliferative and prosurvival signals. Collectively, these results indicate that DCT-induced activation of post-EGFR PI3K/Akt signaling stimulates both colon cancer cell survival and proliferation.     

15-HETE protects rat pulmonary arterial smooth muscle cells from apoptosis via the PI3K/Akt pathway

15-Hydroxyeicosatetraenoic acid (15-HETE), a metabolic product of arachidonic acid (AA), plays an important role in pulmonary vascular smooth muscle remodeling. Although its effects on the apoptotic responses are known, the underlying mechanisms are still poorly understood. Since Akt is a critical regulator of cell survival and vascular remodeling, there may be a crosstalk between 15-HETE anti-apoptotic process and PI3K/Akt survival effect in rat pulmonary arterial smooth muscle cells (PASMCs). To test this hypothesis, we studied the effect of 15-HETE on cell survival and apoptosis using Western blot, cell viability measurement, nuclear morphology determination, TUNEL assay and mitochondrial potential analysis. We found that activation of the PI3K/Akt signaling system was necessary for the 15-HETE to suppress PASMC apoptosis and improve cell survival. Our results indicated that 15-HETE inhibited the apoptotic responses of PASMCs, including morphological alterations, mitochondrial depolarization and the expression apoptosis-specific proteins. These effects were likely to be mediated through the activation of PI3K/Akt. Two downstream signal molecules of PI3K/Akt were identified. Both FasL and Bad were down-regulated by 15-HETE and 15-HETE phosphorylated Bad. These changes depended on the PI3K/Akt signaling pathway in PASMCs. Thus a signal transduction pathway was demonstrated which is necessary for the effects of 15-HETE in protection PASMCs from apoptosis.     

gC1q receptor ligation selectively down-regulates human IL-12 production through activation of the phosphoinositide 3-kinase pathway

gC1qR, a complement receptor for C1q, plays a pivotal role in the regulation of inflammatory and antiviral T cell responses. Several pathogens, including hepatitis C virus, exploit gC1qR-dependent regulatory pathways to manipulate host immunity. However, the molecular mechanism(s) of gC1qR signaling involved in regulating inflammatory responses remains unknown. We report the selective inhibition of TLR4-induced IL-12 production after cross-linking of gC1qR on the surface of macrophages and dendritic cells. Suppression of IL-12 did not result from increased IL-10 or TGF-beta, but was dependent on PI3K activation. Activation of PI3K and subsequent phosphorylation of Akt define an intracellular pathway mediating gC1qR signaling and cross-talk with TLR4 signaling. This is the first report to identify signaling pathways used by gC1qR-mediated immune suppression, and it establishes a means of complement-mediated immune suppression to inhibit Th1 immunity crucial for clearing pathogenic infection.     

Scaffolding protein Grb2-associated binder 1 sustains epidermal growth factor-induced mitogenic and survival signaling by multiple positive feedback loops

Grb2-associated binder 1 (GAB1) is a scaffold protein involved in numerous interactions that propagate signaling by growth factor and cytokine receptors. Here we explore in silico and validate in vivo the role of GAB1 in the control of mitogenic (Ras/MAPK) and survival (phosphatidylinositol 3-kinase (PI3K)/Akt) signaling stimulated by epidermal growth factor (EGF). We built a comprehensive mechanistic model that allows for reliable predictions of temporal patterns of cellular responses to EGF under diverse perturbations, including different EGF doses, GAB1 suppression, expression of mutant proteins, and pharmacological inhibitors. We show that the temporal dynamics of GAB1 tyrosine phosphorylation is significantly controlled by positive GAB1-PI3K feedback and negative MAPK-GAB1 feedback. Our experimental and computational results demonstrate that the essential function of GAB1 is to enhance PI3K/Akt activation and extend the duration of Ras/MAPK signaling. By amplifying positive interactions between survival and mitogenic pathways, GAB1 plays the critical role in cell proliferation and tumorigenesis.     

The class I PI3K/Akt pathway is critical for cancer cell survival in dogs and offers an opportunity for therapeutic intervention

ABSTRACT: BACKGROUND: Using novel small-molecular inhibitors, we explored the feasibility of the class I PI3K/Akt/mTORC1 signaling pathway as a therapeutic target in canine oncology either by using pathway inhibitors alone, in combination or combined with conventional chemotherapeutic drugs in vitro. RESULTS: We demonstrate that growth and survival of the cell lines tested are predominantly dependent on class I PI3K/Akt signaling rather than mTORC1 signaling. In addition, the newly developed inhibitors ZSTK474 and KP372-1 which selectively target pan-class I PI3K and Akt, respectively, and Rapamycin which has been well-established as highly specific mTOR inhibitor, decrease viability of canine cancer cell lines. All inhibitors demonstrated inhibition of phosphorylation of pathway members. Annexin V staining demonstrated that KP372-1 is a potent inducer of apoptosis whereas ZSTK474 and Rapamycin are weaker inducers of apoptosis. Simultaneous inhibition of class I PI3K and mTORC1 by ZSTK474 combined with Rapamycin additively or synergistically reduced cell viability whereas responses to the PI3K pathway inhibitors in combination with conventional drug Doxorubicin were cell linedependent. CONCLUSION: This study highlighted the importance of class I PI3K/Akt axis signaling in canine tumour cells and identifies it as a promising therapeutic target.     

PS1 activates PI3K thus inhibiting GSK-3 activity and tau overphosphorylation: effects of FAD mutations

Phosphatidylinositol 3-kinase (PI3K) promotes cell survival and communication by activating its downstream effector Akt kinase. Here we show that PS1, a protein involved in familial Alzheimer's disease (FAD), promotes cell survival by activating the PI3K/Akt cell survival signaling. This function of PS1 is unaffected by gamma-secretase inhibitors. Pharmacological and genetic evidence indicates that PS1 acts upstream of Akt, at or before PI3K kinase. PS1 forms complexes with the p85 subunit of PI3K and promotes cadherin/PI3K association. Furthermore, conditions that inhibit this association prevent the PS1-induced PI3K/Akt activation, indicating that PS1 stimulates PI3K/Akt signaling by promoting cadherin/PI3K association. By activating PI3K/Akt signaling, PS1 promotes phosphorylation/inactivation of glycogen synthase kinase-3 (GSK-3), suppresses GSK-3-dependent phosphorylation of tau at residues overphosphorylated in AD and prevents apoptosis of confluent cells. PS1 FAD mutations inhibit the PS1-dependent PI3K/Akt activation, thus promoting GSK-3 activity and tau overphosphorylation at AD-related residues. Our data raise the possibility that PS1 may prevent development of AD pathology by activating the PI3K/Akt signaling pathway. In contrast, FAD mutations may promote AD pathology by inhibiting this pathway.     

Ability of the Activated PI3K/Akt Oncoproteins to Synergize with MEK1 and Induce Cell Cycle Progression and Abrogate the Cytokine-Dependence of Hematopoietic Cells

Multiple signal transduction pathways, including the Raf/MEK/ERK and PI3K/Akt kinase cascades, play critical roles in transducing growth signals from activated cell surface receptors. Using conditionally and constitutively-active forms of MEK1 and either PI3K or Akt, we demonstrate synergy between these kinases in relieving cytokine-dependence of the FDC-P1 hematopoietic cell line. Cytokine-independent cells were obtained from ?MEK1:ER-infected cells at a frequency of 5 x 10-5 indicating that low frequency of cells expressing ?-estradiol-regulated ?MEK1:ER became factor-independent, while activated PI3K or Akt by themselves did not relieve cytokine-dependence. In contrast, cytokine-independent cells were recovered approximately 25 to 250-fold more frequently from ?MEK1:ER infected cells also infected with either activated PI3K or Akt. MEK/PI3K and MEK/Akt-responsive cells could be maintained long-term as long as either ?-estradiol or the estrogen receptor antagonist 4-hydroxy-tamoxifen (4HT) were provided. The MEK/PI3K/Akt responsive cells were sensitive to both MEK and PI3K/Akt/p70S6K inhibitors. Synergy was observed when inhibitors which targeted both pathways were added together. These results indicate that there is synergy between the Raf/MEK/ERK and PI3K/Akt pathways in terms of abrogation of cytokine-dependence of hematopoietic cells. Likewise, suppression of multiple signal transduction pathways is a more effective means to inhibit cell cycle progression and induce apoptosis in leukemic cells.     

Sindbis virus replication, is insensitive to rapamycin and torin1, and suppresses Akt/mTOR pathway late during infection in HEK cells

Genetically engineered Sindbis viruses (SIN) are excellent oncolytic agents in preclinical models. Several human cancers have aberrant Akt signaling, and kinase inhibitors including rapamycin are currently tested in combination therapies with oncolytic viruses. Therefore, it was of interest to delineate possible cross-regulation between SIN replication and PI3K/Akt/mTOR signaling. Here, using HEK293T cells as host, we report the following key findings: (a) robust SIN replication occurs in the presence of mTOR specific inhibitors, rapamycin and torin1 or Ly294002 – a PI3K inhibitor, suggesting a lack of requirement for PI3K/Akt/mTOR signaling; (b) suppression of phosphorylation of Akt, mTOR and its effectors S6, and 4E-BP1 occurs late during SIN infection: a viral function that may be beneficial in counteracting cellular drug resistance to kinase inhibitors; (c) Ly294002 and SIN act additively to suppress PI3K/Akt/mTOR pathway with little effect on virus release; and (d) SIN replication induces host translational shut off, phosphorylation of eIF2α and apoptosis. This first report on the potent inhibition of Akt/mTOR signaling by SIN replication, bolsters further studies on the development and evaluation of engineered SIN genotypes in vitro and in vivo for unique cytolytic functions.     

Protection against myocardial ischemia/reperfusion injury in TLR4-deficient mice is mediated through a phosphoinositide 3-kinase-dependent mechanism

TLRs play a critical role in the induction of innate and adaptive immunity. However, TLRs have also been reported to mediate the pathophysiology of organ damage following ischemia/reperfusion (I/R) injury. We have reported that TLR4(-/-) mice show decreased myocardial injury following I/R; however, the protective mechanisms have not been elucidated. We examined the role of the PI3K/Akt signaling pathway in TLR4(-/-) cardioprotection following I/R injury. TLR4(-/-) and age-matched wild-type (WT) mice were subjected to myocardial ischemia for 45 min, followed by reperfusion for 4 h. Pharmacologic inhibitors of PI3K (wortmannin or LY294002) were administered 1 h before myocardial I/R. Myocardial infarct size/area at risk was reduced by 51.2% in TLR4(-/-) vs WT mice. Cardiac myocyte apoptosis was also increased in WT vs TLR4(-/-) mice following I/R. Pharmacologic blockade of PI3K abrogated myocardial protection in TLR4(-/-) mice following I/R. Specifically, heart infarct size/area at risk was increased by 98% in wortmannin and 101% in LY294002-treated TLR4(-/-) mice, when compared with control TLR4(-/-) mice. These data indicate that protection against myocardial I/R injury in TLR4(-/-) mice is mediated through a PI3K/Akt-dependent mechanism. The mechanisms by which PI3K/Akt are increased in the TLR4(-/-) myocardium may involve increased phosphorylation/inactivation of myocardial phosphatase and tensin homolog deleted on chromosome 10 as well as increased phosphorylation/inactivation of myocardial glycogen synthase kinase-3beta. These data implicate innate immune signaling pathways in the pathology of acute myocardial I/R injury. These data also suggest that modulation of TLR4/PI3K/Akt-dependent signaling pathways may be a viable strategy for reducing myocardial I/R injury.     

Survival signaling in type II pneumocytes activated by surfactant protein-A

Surfactant-associated protein-A (SP-A) is a component of pulmonary surfactant that acts as a cytokine through interaction with a cell-surface receptor (SPAR) on lung epithelial cells. SP-A regulates important physiological processes including surfactant secretion, gene expression, and protection against apoptosis. Tyrosine kinase and PI3K inhibitors block effects of SP-A, suggesting that SPAR may be a receptor tyrosine kinase and activate the PI3K-PKB/Akt pathway. Here we report that SP-A treatment leads to rapid tyrosine-specific phosphorylation of several important proteins in lung epithelial cells including insulin receptor substrate-1 (IRS-1), an upstream activator of PI3K. Analysis of anti-apoptotic signaling species downstream of IRS-1 showed activation of PKB/Akt but not of MAPK. Phosphorylation of IkappaB was minimally affected by SP-A as was NFkappaB gel shift activity. However, FKHR was rapidly phosphorylated in response to SP-A and its DNA-binding activity was significantly reduced. Since FKHR is pro-apoptotic, this may play an important role in signaling the anti-apoptotic effects of SP-A. Therefore, we have characterized survival-enhancing signaling activated by SP-A leading from SPAR through IRS-1, PI3K, PKB/Akt, and FKHR. The activity of this pathway may explain, in part, the resilience of type II cells to lung injury and their survival to repopulate alveolar epithelium after peripheral lung damage.     

蛋白激酶B/Akt抑制剂

磷脂酰肌醇-3-激酶(phosphatidylinositol 3-kinase,PI3K)/蛋白激酶B(protein kinase B,PKB/Akt)信号通路在细胞生长与存活中起着关键作用,PI3K/Akt通路的过度激活在多种肿瘤中常见。Akt激酶本身以及Akt激酶上游调节分子,例如PTEN和PI3K,在超过50%的人类肿瘤中均有异常变化。因此Akt成为肿瘤预防和肿瘤靶向治疗的热点之一。许多小分子化合物通过不同机制抑制Akt活性,根据小分子抑制剂与激酶的结合部位和化学结构不同,主要分为ATP竞争性抑制剂、Akt变构抑制剂和磷脂酰肌醇类似物抑制剂。本文综述了PI3K/Akt通路与肿瘤的关系和Akt抑制剂的研究现状,为新型抗癌药物的设计研究提供参考。     

Dual Inhibition of PI3K/Akt Signaling and the DNA Damage Checkpoint in p53-Deficient Cells with Strong Survival Signaling: Implications for Cancer Therapy

Natural (intrinsic) resistance of many tumor types to DNA damaging agents is closely associated with their capacity to undergo robust cell cycle arrest in G2/M. G2 arrest is regulated by the DNA damage checkpoint and by survival signaling, with a potential role of PI3K/Akt in checkpoint function. In this work, we wanted to clarify if inhibition of multiple checkpoint/survival pathways may confer better efficacy in the potentiation of genotoxic agents compared to inhibition of either pathway alone. We compared the influence of UCN-01, which affects both the DNA damage checkpoint and PI3K/Akt-mediated survival signaling, with the PI3K inhibitors wortmannin and LY294002 in p53-deficient M1 acute myeloid leukemia cells treated with the DNA damaging agent cisplatin. Our results show that direct inhibition of PI3K/Akt in G2-arrested cells by wortmannin or LY294002 strongly enhanced the cytotoxicity of cisplatin without influencing the G2 checkpoint. Unexpectedly, dual inhibition of both survival and checkpoint signaling by UCN-01, also increased the cytotoxicity of cisplatin, but to a lesser degree than wortmannin or LY294002. The differences in cytotoxicity were accompanied by differences in cell death pathways: direct inhibition of PI3K/Akt was accompanied by rapid apoptotic cell death during G2, whereas cells underwent mitotic transit and cell division followed by cell death during G1 when both checkpoint and survival signaling were inhibited. Our results elucidate a novel function for PI3K/Akt as a survival factor during DNA damage-induced G2 arrest and could have important pharmacological consequences for the application of response modulators in p53-deficient tumors with strong survival signaling.     

CXCL9对单个核细胞的趋化作用及其机制探讨

目的 观察趋化因子CXCL9对人外周血单个核细胞的趋化作用,并探讨其对CXCR3受体后信号通路的影响.方法 分离人外周血单个核细胞并进行培养,Transwell小室趋化实验检测不同浓度的趋化因子CXCL9对外周血单个核细胞的趋化作用;Western blot方法检测CXCL9刺激外周血单个核细胞时ERK1/2及PI3K/Akt信号通路的蛋白表达变化,并检测上述通路抑制剂PD98059和Wortmannin处理细胞后,CXCL9对ERK1/2、PI3K/Akt信号通路的影响有无变化.结果 与空白对照组相比,不同浓度的CXCL9刺激对人外周血单个核细胞均有明显的趋化作用,并且CXCL9刺激人外周血单个核细胞能激活ERK1/2及PI3K/Akt信号通路,其关键蛋白ERK1/2及Akt磷酸化水平显著增加;通路特异性抑制剂PD98059和Wortmannin的应用能明显抑制CXCL9对这两条信号通路的激活.结论 CXCL9能趋化人外周血单个核细胞发生迁移,ERK1/2及PI3K/Akt信号通路可能在此过程中发挥重要作用.