The PTEN/PI3K/AKT signalling pathway in cancer, therapeutic implications

PTEN/PI3K/AKT constitutes an important pathway regulating the signaling of multiple biological processes such as apoptosis, metabolism, cell proliferation and cell growth. PTEN is a dual protein/lipid phosphatase which main substrate is the phosphatidyl-inositol,3,4,5 triphosphate (PIP3), the product of PI3K. Increase in PIP3 recruits AKT to the membrane where it is activated by other kinases also dependent on PIP3. Many components of this pathway have been described as causal forces in cancer. PTEN activity is lost by mutations, deletions or promoter methylation silencing at high frequency in many primary and metastatic human cancers. Germ line mutations of PTEN are found in several familial cancer predisposition syndromes. Activating mutations which have been reported for PI3K and AKT, in tumours are able to confer tumourigenic properties in several cellular systems. Additionally, the binding of PI3K to oncogenic ras is essential for the transforming properties of ras. In summary, the data strongly support the view of the PTEN/PI3K/AKT pathway as an important target for drug discovery.     

月腺大戟素A通过干扰PKD1介导的MEK/ERK和PI3K/AKT信号通路抑制乳腺癌细胞增殖的研究

目的乳腺癌是世界上最致命的恶性肿瘤之一。月腺大戟素A(EA)是从中药月腺大戟中提取的乙酰间苯三酚类化合物。探讨EA抑制乳腺癌细胞MCF-7增殖的具体机制,以期为乳腺癌的临床治疗提供新的思路。方法在乳腺癌细胞MCF-7中添加不同浓度的EA药物,检测PKD1蛋白表达水平的变化。构建PKD1的过表达质粒体并转染至细胞,用实时荧光定量PCR技术和Western Blot实验检测PKD1的mRNA和蛋白表达水平。CCK-8实验用于检测细胞增殖能力的变化。Western Blot实验用于检测PKD1介导的相关信号通路中关键蛋白的表达水平。结果EA以剂量依赖的方式抑制乳腺癌细胞中PKD1蛋白的表达(P<0.05)。当转染过表达质粒后,PKD1在mRNA和蛋白水平上显著升高(P<0.001)。同时过表达PKD1显著逆转EA对MCF-7的增殖抑制作用(P<0.001)。信号通路分析证实EA通过抑制PKD1介导的MEK/ERK和PI3K/AKT信号通路活性影响乳腺癌细胞的增殖能力(P<0.05)。结论EA通过调控PKD1介导MEK/ERK和PI3K/AKT信号通路,能够抑制乳腺癌细胞的增殖。     

PI3K/AKT/ERK在胃肠道肿瘤中的表达与临床病理的关系

目的探讨PI3K,Akt,ERKl/2在胃肠道肿瘤中的表达与临床病理的关系及意义。方法选取2009年5月至2011年5月北京安贞医院病理科有完整病历资料及分期的胃肠道恶性肿瘤组织标本共30例,其中胃癌14例,结肠癌9例,直肠癌7例。同时每例取其癌旁组织作对照。采用EnVisionTM二步法染色及S-P免疫组化法对PI3K,Akt,ERKl/2在胃肠道肿瘤组织中的表达进行测定。结果 PI3K/AKT在胃肠道肿瘤组织中阳性表达率分别为67%(20/30)和80%(24/30),明显高于癌旁组织中的表达20%(7/30)和20%(5/25),ERK1/2在胃肠道肿瘤组织中阳性表达率为57%(17/30),明显高于癌旁组织中的表达17%(5/30),差异有统计学意义(P均<0.05)。PI3K/AKT/ERK蛋白在胃肠道肿瘤组织中的表达与患者的年龄、病理分型、淋巴结转移、临床病理分期及有无远处转移均无显著关系(P>0.05)。结论 PI3K,Akt,ERKl/2在胃肠道肿瘤组织中高表达,但与临床病理无关,可能参与了肿瘤发生发展的早期事件。     

Exploiting the PI3K/AKT pathway for cancer drug discovery

Evolving studies with several different targeted therapeutic agents are demonstrating that patients with genomic alterations of the target, including amplification, translocation and mutation, are more likely to respond to the therapy. Recent studies indicate that numerous components of the phosphatidylinositol-3-kinase (PI3K)/AKT pathway are targeted by amplification, mutation and translocation more frequently than any other pathway in cancer patients, with resultant activation of the pathway. This warrants exploiting the PI3K/AKT pathway for cancer drug discovery.     

GE11 peptide conjugated selenium nanoparticles for EGFR targeted oridonin delivery to achieve enhanced anticancer efficacy by inhibiting EGFR-mediated PI3K/AKT and Ras/Raf/MEK/ERK pathways

Selenium nanoparticles (Se NPs) have attracted increasing interest in recent decades because of their anticancer, immunoregulation, and drug carrier functions. In this study, GE11 peptide-conjugated Se NPs (GE11-Se NPs), a nanosystem targeting EGFR over-expressed cancer cells, were synthesized for oridonin delivery to achieve enhanced anticancer efficacy. Oridonin loaded and GE11 peptide conjugated Se NPs (GE11-Ori-Se NPs) were found to show enhanced cellular uptake in cancer cells, which resulted in enhanced cancer inhibition against cancer cells and reduced toxicity against normal cells. After accumulation into the lysosomes of cancer cells and increase of oridonin release under acid condition, GE11-Ori-Se NPs were further transported into cytoplasm after the damage of lysosomal membrane integrity. GE11-Ori-Se NPs were found to induce cancer cell apoptosis by inducting reactive oxygen species (ROS) production, activating mitochondria-dependent pathway, inhibiting EGFR-mediated PI3K/AKT and inhibiting Ras/Raf/MEK/ERK pathways. GE11-Se NPs were also found to show active targeting effects against the tumor tissue in esophageal cancer bearing mice. And in nude mice xenograft model, GE11-Ori-Se NPs significantly inhibited the tumor growth via inhibition of tumor angiogenesis by reducing the angiogenesis-marker CD31 and activation of the immune system by enhancing IL-2 and TNF-α production. The selenium contents in mice were found to accumulate into liver, tumor, and kidney, but showed no significant toxicity against liver and kidney. This cancer-targeted design of Se NPs provides a new strategy for synergistic treating of cancer with higher efficacy and reduced side effects, introducing GE11-Ori-Se NPs as a candidate for further evaluation as a chemotherapeutic agent for EGFR over-expressed esophageal cancers.     

Investigational PI3K/AKT/mTOR inhibitors in development for endometrial cancer

Introduction: Endometrial cancer (EC) is the most common neoplasm of the female genital tract in developed countries. Despite the progress in early detection and treatment, a significant number of cases of advanced ECs are still diagnosed. These patients have few treatment options and a poor prognosis. Our understanding of EC pathogenesis and progression has been enhanced by recent genomic studies. Among the relevant biological pathways, phosphatidylinositol 3-kinase/AKT (PIK3/AKT)-mammalian target of rapamycin (mTOR) signaling is frequently upregulated in this cancer.

Areas covered: This review covers investigational EC therapeutics acting on the PI3K/AKT/mTOR pathway. The authors review the results of clinical studies and highlight ongoing trials.

Expert opinion: Several new agents are under evaluation for treating patients with metastatic, recurrent, and persistent EC. Clinical trials investigating PI3K/AKT/mTOR inhibitors have yielded controversial results. In the near future, new studies with dual inhibitors or multi-pathways inhibitors as mono or combination therapies with conventional chemotherapy (CT) or other targeted drugs may provide more promising data. Moreover, the evaluation of new serum and histological biomarkers is an attractive strategy for patient selection.     

PI3K/AKT信号通路在银屑病发病机制中的研究进展

银屑病是一种免疫介导的多因素炎症性皮肤病,以表皮角质形成细胞异常增殖、毛细血管扩张、中性粒细胞浸润为主要病理表现。磷脂酰肌醇3-激酶（phosphatidylinositol 3-kinase,PI3K）/蛋白激酶B（protein kinase B,AKT）信号通路在表皮细胞增殖、细胞自噬、血管生成、脂质代谢等过程中...     

Protective effects of luteolin against lipopolysaccharide-induced acute lung injury involves inhibition of MEK/ERK and PI3K/Akt pathways in neutrophils

Aim:

To investigate whether luteolin, the major polyphenolic components of Lonicera japonica, has beneficial effects against lipopolysaccharide (LPS)-induced acute lung injury (ALI) and to determine whether the protective mechanism involves anti-inflammatory effects on neutrophils.

Methods:

ALI was induced with intratracheal instillation of LPS in mice. The level of ALI was determined by measuring the cell count and protein content in bronchoalveolar lavage (BAL) fluid. Neutrophils were stimulated with formyl-Met-Leu-Phe (fMLP) or LPS in vitro. Chemotaxis and superoxide anion generation were measured to evaluate neutrophil activation. The potential involvement of intracellular signaling molecules in regulating neutrophil activation was analyzed by using Western blot.

Results:

LPS induced ALI in mice, as evidenced with leukocyte infiltration and protein leakage into the lungs. Luteolin attenuated LPS-induced leukocyte infiltration and protein extravasation. In cell studies, luteolin attenuated the fMLP-induced neutrophil chemotaxis and respiratory burst (IC₅₀ 0.2±0.1 μmol/L and 2.2±0.8 μmol/L, respectively), but had a negligible effect on superoxide anion generation during phorbol myristate acetate stimulation. Furthermore luteolin effectively blocked MAPK/ERK kinase 1/2 (MEK), extracellular signal-regulated kinase (ERK), and Akt phosphorylation in fMLP- and LPS-stimulated neutrophils.

Conclusion:

These results indicate that luteolin has beneficial effects against LPS-induced ALI in mice, and the attenuation of neutrophil chemotaxis and respiratory burst by luteolin involves the blockade of MEK-, ERK-, and Akt-related signaling cascades.     

Bisphenol A induce ovarian cancer cell migration via the MAPK and PI3K/Akt signalling pathways

Bisphenol A (BPA), is present in a multitude of products, including food and water containers, food can linings, dentistry sealants, and thermal paper. BPA can induce the growth of human ovarian cancer cell lines. Reduction of adhesion and the initiation of metastasis are important events in cancer progression; therefore, this study investigated the effects of BPA (0.1–100 nM) on the migration of OVCAR-3 ovarian cancer cells and the expression levels of metalloproteinases (MMPs) and cadherins. The oestrogenic compound 17β-estradiol (40 nM) was used as a positive control for estrogenic properties of bisphenol A. BPA stimulated cell migration, and the effect of BPA was similar to that of 17β-estradiol. BPA-induced cell migration was accompanied by up-regulation of the migration-related factors MMP-2, MMP-9 and N-cadherin, but E-cadherin expression and activity was unaffected. The stimulatory effects of BPA on cell migration were abolished by pre-treatment of the cells with inhibitors of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase pathways (PI3K). In conclusion, the results presented here show that BPA induces OVCAR-3 cells migration by activating MAPK and PI3K/Akt signalling pathways.     

The calcium-sensing receptor mediates hypoxia-induced proliferation of rat pulmonary artery smooth muscle cells through MEK1/ERK1,2 and PI3K pathways

Activation of the calcium-sensing receptor (CaSR) leads to an increase of intracellular calcium concentration and alteration of cellular activities. High level of intracellular calcium is involved in hypoxia-induced proliferation of pulmonary arterial smooth muscle cells (PASMCs). However, whether the CaSR is expressed in PAMSCs and is related to the hypoxia-induced proliferation of PASMCs is unclear. In this study, the expression and distribution of CaSRs were detected by RT-PCR, western blotting and immunofluorescence; the intracellular concentration of free calcium ([Ca(2+) ](i) ) was determined by confocal laser scanning microscopy; cell proliferation was tested using an MTT and BrdU incorporation assay; cell cycle analysis was carried out using a flow cytometric assay; and the expression of proliferating cell nuclear antigen (PCNA), extracellular signal-regulated protein kinase 1,2 (ERK1,2) and AKT were analysed by western blotting. We observed that both CaSR mRNA and protein were expressed in rat PASMCs. Lowering of oxygen from 21% to 2.5% led to increased [Ca(2+) ](i) and CaSR expression. This condition of hypoxia also stimulated PASMCs proliferation accompanying with increased phosphorylation of ERK1,2 and AKT. GdCl(3) (an agonist of CaSR) or NPS2390 (an antagonist of CaSR) amplified or weakened the effect of hypoxia, respectively. PD98059 (a MEK1 inhibitor) or LY294002 (a PI3K inhibitors) decreased the up-regulation of PCNA expression and the increase of the cell proliferation index induced by hypoxia and GdCl(3) in PASMCs. Our results suggest that CaSR is expressed in rat PASMCs, and that CaSR activation through MEK1/ERK1,2 and PI3 kinase pathways is involved in hypoxia-induced proliferation of PASMCs.     

PI3K/AKT/mTOR信号通路参与自身免疫性

自身免疫性疾病（autoimmune disease,AD）是机体因自身抗原免疫耐受障碍而对自身抗原产生免疫反应,从而引起机体组织损伤的一类疾病。近年研究发现,磷脂酰肌醇-3-激酶/蛋白激酶B/雷帕霉素靶蛋白（phosphatidylin ositol 3-kinase/protein kinase B/mechanistic target ofrapamycin kinase,PI3K/AKT/mTOR）信号通路与AD发病密切相关,其主要参与免疫细胞增殖分化、炎性细胞因子分泌、自噬及氧化应激等过程。本文重点概述PI3K/AKT/mTOR信号通路参与AD发病机理的研究进展。     

EZH2对HSC-T6细胞增殖活化的影响及其部分机制研究

目的探讨Zeste基因增强子同源物2(enhancer of zeste homolog 2,EZH2)表达沉默对大鼠肝星状细胞HSC-T6细胞增殖活化的影响,及其部分调控机制。方法应用EZH2的抑制剂DZNep(3-Deazaneplanocin A)作用于TGF-β1诱导活化的HSC-T6细胞,采用Western blot法检测蛋白EZH2、p-ERK、p-AKT和α-SMA的表达;根据EZH2的碱基序列设计并合成小干扰RNA(small interfering RNA,si RNA),通过脂质体LipofectamineTM2000转染到HSC-T6细胞内,应用四甲基偶氮唑盐(MTT)法检测HSC-T6细胞的增殖变化,Western blot法检测蛋白EZH2、p-ERK、p-AKT和α-SMA的表达。结果将DZNep加入TGF-β1诱导活化的HSC-T6细胞后,EZH2蛋白水平明显降低,同时p-ERK、pAKT和α-SMA蛋白水平亦明显降低;将EZH2-si RNA转染活化的HSC-T6细胞内,HSC-T6细胞的增殖可明显被抑制,同时EZH2、p-ERK、p-AKT和α-SMA蛋白水平亦明显降低。结论抑制EZH2的表达可明显抑制HSC-T6细胞的增殖活化,EZH2可能是潜在的治疗肝纤维化的靶点。     

Targeting MAPK (Ras/ERK) and PI3K/Akt pathways in pituitary tumorigenesis

Background: Pituitary adenomas are common intracranial neoplasms, comprising 10 – 15% of all brain tumors. Data from autopsy studies suggest that pituitary adenomas develop in 17 – 25% of the population. Nevertheless, the pathogenesis of sporadic pituitary tumors still remains obscure. Objective: In this review, the roles of MAPK (mainly Ras/extracellular signal-regulated protein kinase (ERK)) and PI3K/Akt signaling pathways in pituitary tumorigenesis are summarised. Methods: A full data search was performed through PubMed over the years 2000 – 2009 with key words ‘pituitary, pituitary tumor, molecular biology, Akt, MAPK, PI3K, ERK’, and all relevant publications have been included, together with selected publications prior to that date. Growth factor receptor mutations and overexpression, G protein mutations, other signaling pathway abnormalities or genetic syndromes associated with pituitary tumors are not discussed as these topics are behind the scope of this review. Conclusions: There are preclinical data and human pituitary tumor studies that are compatible with increased Ras/ERK and/or PI3K/Akt pathway activity in pituitary tumors. Future research focusing on scaffold proteins and signaling modulators regulating these pathways may help identify the initiating transforming events and accordingly new strategies may be developed targeting these pathways in pituitary tumors.     

Targeting PI3K/AKT/mTOR pathway in non small cell lung cancer

While PI3K/AKT/mTOR pathway is altered in a variety of cancers including non small cell lung cancer, abnormalities in this pathway are more common in squamous cell lung carcinoma than in adenocarcinoma of the lung. Moreover, aberrant activation of PI3K/AKT/mTOR pathway is one of the mechanisms of acquired resistance to EGFR-TK inhibitors in patients with adenocarcinoma carrying EGFR activating mutations.     

Inhibition of histamine receptor H3 suppresses the growth and metastasis of human non-small cell lung cancer cells via inhibiting PI3K/Akt/mTOR and MEK/ERK signaling pathways and blocking EMT

Recent evidence shows that the expression levels of histamine receptor H3 (Hrh3) are upregulated in several types of cancer. However, the role of Hrh3 in non-small cell lung cancer (NSCLC) has not been elucidated. In the present study, we showed that the expression levels of Hrh3 were significantly increased in NSCLC samples, and high levels of Hrh3 were associated with poor overall survival (OS) in NSCLC patients. In five human NSCLC cell lines tested, Hrh3 was significantly upregulated. In NSCLC cell lines H1975, H460, and A549, Hrh3 antagonist ciproxifan (CPX, 10–80 μM) exerted moderate and concentration-dependent inhibition on the cell growth and induced apoptosis, whereas its agonist RAMH (80 μM) reversed these effects. Furthermore, inhibition of Hrh3 by CPX or siRNA retarded the migration and invasion of NSCLC cells through inhibiting epithelial-mesenchymal transition (EMT) progression via reducing the phosphorylation of PI3K/Akt/mTOR and MEK/ERK signaling pathways. In nude mice bearing H1975 cell xenograft or A549 cell xenograft, administration of CPX (3 mg/kg every other day, intraperitoneal) significantly inhibited the tumor growth with increased E-cadherin and ZO-1 expression and decreased Fibronectin expression in tumor tissue. In conclusion, this study reveals that Hrh3 plays an important role in the growth and metastasis of NSCLC; it might be a potential therapeutic target against the lung cancer.     

Long non-coding RNA DDX11-AS1 promotes non-small cell lung cancer development via regulating PI3K/AKT signalling

Non-small cell lung cancer (NSCLC) has been considered to be the most common category of lung cancer, comprising approximately 80% of lung cancers. Long non-coding RNAs (lncRNAs) were diffusely documented to modulate carcinogenesis or progression of tumours. However, the role of DDX11-AS1 was still unclear in NSCLC. Bioinformatics analysis and experimental assays including hematoxylin and eosin (H&E) staining, RT-qPCR, colony formation, CCK-8, flow cytometry, western blot and xenograft assays were applied to investigate the biological role and molecular mechanism of DDX11-AS1 in NSCLC. The level of lncRNA DDX11-AS1 was up-regulated in NSCLC tumour tissues and cells. In function aspect, knockdown of DDX11-AS1 caused an apparent inhibitive effect on cell proliferation in vitro and in vivo. DDX11-AS1 inhibition promoted cell apoptosis in vitro. In mechanism, the protein level of phosphorylated AKT was reduced by DDX11-AS1 inhibition but increased by DDX11-AS1 overexpression. These results indicated that DDX11-AS1 exacerbated NSCLC progression via activating PI3K/AKT signalling pathway. All in all, DDX11-AS1 promotes NSCLC development via regulating PI3K/AKT signalling.