PI3K/AKT pathway activation in acute myeloid leukaemias is not associated with AKT1 pleckstrin homology domain mutation

Despite its' central role, the precise mechanisms of the phosphoinositide 3-kinase/Akt (PI3K)/Akt pathway activation in acute myeloid leukaemia (AML) have not been elucidated. Recently, a recurrent novel AKT1 pleckstrin homology domain (PHD) mutation leading to membrane translocation, constitutive AKT activation and leukaemia development in mice was described. To assess AKT1 PHD mutations in AML, we sequenced 57 specimens from 49 AML patients, all of whom showed PI3K/AKT pathway activation by analysis of total and phospho-protein expression for AKT, mTor, p70S6Kinase, S6ribosomal protein and PTEN. No mutations in AKT1 PHD were identified, making this mutation an unlikely cause of PI3K/AKT pathway activation in AML.     

Y-box binding protein 1 augments sorafenib resistance via the PI3K/Akt signaling pathway in hepatocellular carcinoma

BACKGROUNDSorafenib is the first-line treatment for patients with advanced hepatocellular carcinoma (HCC). Y-box binding protein 1 (YB-1) is closely correlated with tumors and drug resistance. However, the relationship between YB-1 and sorafenib resistance and the underlying mechanism in HCC remain unknown.AIMTo explore the role and related mechanisms of YB-1 in mediating sorafenib resistance in HCC.METHODSThe protein expression levels of YB-1 were assessed in human HCC tissues and adjacent nontumor tissues. Next, we constructed YB-1 overexpression and knockdown hepatocarcinoma cell lines with lentiviruses and stimulated these cell lines with different concentrations of sorafenib. Then, we detected the proliferation and apoptosis in these cells by terminal deoxynucleotidyl transferase dUTP nick end labeling, flow cytometry and Western blotting assays. We also constructed a xenograft tumor model to explore the effect of YB-1 on the efficacy of sorafenib in vivo. Moreover, we studied and verified the specific molecular mechanism of YB-1 mediating sorafenib resistance in hepatoma cells by digital gene expression sequencing (DGE-seq).RESULTSYB-1 protein levels were found to be higher in HCC tissues than in corresponding nontumor tissues. YB-1 suppressed the effect of sorafenib on cell proliferation and apoptosis. Consistently, the efficacy of sorafenib in vivo was enhanced after YB-1 was knocked down. Furthermore, KEGG pathway enrichment analysis of DGE-seq demonstrated that the phosphoinositide-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway was essential for the sorafenib resistance induced by YB-1. Subsequently, YB-1 interacted with two key proteins of the PI3K/Akt signaling pathway (Akt1 and PIK3R1) as shown by searching the BioGRID and HitPredict websites. Finally, YB-1 suppressed the inactivation of the PI3K/Akt signaling pathway induced by sorafenib, and the blockade of the PI3K/Akt signaling pathway by LY294002 mitigated YB-1-induced sorafenib resistance.CONCLUSIONOverall, we concluded that YB-1 augments sorafenib resistance through the PI3K/Akt signaling pathway in HCC and suggest that YB-1 is a key drug resistance-related gene, which is of great significance for the application of sorafenib in advanced-stage HCC.     

Ribonucleotide reductase M2 subunit silencing suppresses tumorigenesis in pancreatic cancer via inactivation of PI3K/AKT/mTOR pathway

Background/objectivesRibonucleotide Reductase M2 subunit (RRM2) is elevated in pancreatic cancer and involved in DNA synthesis and cell proliferation. But its specific mechanism including genetic differences and upstream regulatory pathways remains unclear.MethodsWe analyzed RRM2 expression of 178 pancreatic cancer patients in Gene Expression Profiling Interactive Analysis (GEPIA) database. Besides, more pancreatic cancer specimens were collected and detected RRM2 expression by immunohistochemistry. RRM2 knockdown by shRNA was applied for functional and mechanism analysis in vitro. Xenograft tumor growth was significantly slower by RRM2 silencing in vivo.ResultsIt showed that high RRM2 expression had a poorer overall survival and disease free survival. RRM2 expression was higher in tumor grade 2 and 3 than grade 1. Immunohistochemistry data validated that high RRM2 expression predicted worse survival. RRM2 knockdown significantly reduced cell proliferation, inhibited colony formation and suppressed cell cycle progress. Further mechanism assay showed silencing RRM2 lead to inactivation of PI3K/AKT/mTOR pathway and inhibition of mutant p53, which induce S phase arrest and/or apoptosis. In panc-1 cells, S-phase arrest mediated by mutant p53 inhibition, p21 increase and cell cycle related proteins change. While in miapaca-2 cells, induction of apoptosis and S-phase arrest mediated by CDK1 played a coordinated role.ConclusionTaken together, high RRM2 expression was associated with worse prognosis. Importantly, RRM2 knockdown deactivated PI3K/AKT/mTOR pathway, resulting in cell cycle arrest and/or apoptosis. This study shed light on the molecular mechanism of RRM2 in pancreatic tumor progression and is expected to provide a new theoretical basis for pancreatic cancer treatment.     

Impaired PI3K/Akt signal pathway and hepatocellular injury in high-fat fed rats

AIM:To determine whether mitochondrial dysfunction resulting from high-fat diet is related to impairment of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt,also known as PKB) pathway. METHODS:Rat models of nonalcoholic fatty liver were established by high-fat diet feeding. The expression of total and phosphorylated P13K and Akt proteins in hepatocytes was determined by Western blotting. Degree of fat accumulation in liver was measured by hepatic triglyceride. Mitochondrial number and size were determined using quantitative morphometric analysis under transmission electron microscope. The permeability of the outer mitochondrial membrane was assessed by determining the potential gradient across this membrane.RESULTS:After Wistar rats were fed with high-fat diet for 16 wk,their hepatocytes displayed an accumulation of fat (103.1 ± 12.6 vs 421.5 ± 19.7,P < 0.01),deformed mitochondria (9.0% ± 4.3% vs 83.0% ± 10.9%,P < 0.05),and a reduction in the mitochondrial membrane potential (389.385% ± 18.612% vs 249.121% ± 13.526%,P < 0.05). In addition,the expression of the phosphorylated P13K and Akt proteins in hepatocytes was reduced,as was the expression of the anti-apoptotic protein Bcl-2,while expression of the pro-apoptotic protein caspase-3 was increased. When animals were treated with pharmacological inhibitors of P13K or Akt,instead of high-fat diet,a similar pattern of hepatocellular fat accumulation,mitochondrial impairment,and change in the levels of PI3K,Akt,Bcl-2 was observed. CONCLUSION:High-fat diet appears to inhibit the PI3K/Akt signaling pathway,which may lead to hepa-tocellular injury through activation of the mitochondrial membrane pathway of apoptosis.     

LY294002 potentiates the anti-cancer effect of oxaliplatin for gastric cancer via death receptor pathway

AIM:To examine the effects of combined treatment of oxaliplatin and phosphatidylinositol 3’-kinase inhibitor,2-(4-morpholinyl) -8-phenyl-4H-1-benzopyran-4-one(LY294002) for gastric cancer. METHODS:Cell viability was evaluated by 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide assay.Apoptotic cells were detected by flow cytometric analysis and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay.Western blotting and immuno-precipitation were used to examine protein expres...     

Phosphatidylethanolamine-binding protein 4 promotes lung cancer cells proliferation and invasion via PI3K/Akt/mTOR axis

Background

While phosphatidylethanolamine-binding protein 4 (PEBP4) is a key factor in the malignant proliferation and metastasis of tumor cells, the exact regulatory network governing its roles remains unclear. This study was designed to investigate the effect of PEBP4 on PI3K/Akt/mTOR pathway and explore its molecular network that governs the proliferation and metastasis of tumor cells.

Methods

After the recombinant plasmid pcDNA3.1-PEBP4 was constructed, the recombinant plasmid pcDNA3.1-PEBP4 and PEBP4-targeting siRNA were transfected into lung cancer HCC827 cell line. The expressions of PI3K/Akt/mTOR pathway components in HCC827 cells in each group were determined using Western blotting. In the HCC827 cells, the effect of PI3K pathway inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 on the expressions of PI3K/Akt/mTOR pathway components under the effect of PEBP4 was determined using Western blotting, and the effects of {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 on the cell viability, proliferation, and migration capabilities under the overexpression of PEBP4 were determined using MTT method, flow cytometry, and Transwell migration assay. Furthermore, the effect of mTOR inhibitor rapamycin (RAPA) on the expressions of PI3K/Akt/mTOR pathway components under the effect of PEBP4 was determined using Western blotting, and the effects of RAPA on the cell viability, proliferation, and migration capabilities under the overexpression of PEBP4 were determined using MTT method, flow cytometry, and Transwell migration assay.

Results

As shown by Western blotting, the protein expressions of p-Akt and phosphorylated mTOR (p-mTOR) were significantly higher in the pcDNA3.1-PEBP4-transfected group than in the normal control group and PEBP4 siRNA group (P<0.05); furthermore, the protein expressions of p-Akt and p-mTOR significantly decreased in the PEBP4 targeting siRNA-transfected group (P<0.05). Treatment with {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 significantly inhibited the protein expressions of p-Akt and p-mTOR in HCC827 cells (P<0.05). In contrast, treatment with RAPA only significantly inhibited the protein expression of p-mTOR (P<0.05). As shown by MTT, flow cytometry, and Transwell migration assay, both {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 and RAPA could significantly lower the viability of HCC827 cells and inhibit their proliferation and invasion (P<0.05); meanwhile, they could reverse the effect of PEBP4 in promoting the proliferation and migration of HCC827 cells (P<0.05).

Conclusions

The overexpression of PEBP4 increases the phosphorylation levels of Akt and mTOR in lung cancer cells. The PI3K/Akt/mTOR signaling axis may be a key molecular pathway via which PEBP4 promotes the proliferation and invasion of non-small cell lung cancer (NSCLC) cells; also, it may serve as a potential therapeutic target.     

磷脂酰肌醇3-激酶/蛋白激酶B信号通路对CD40介导胃癌细胞侵袭与转移的研究

目的 探讨可溶性CD40配体(sCD40L)联合磷脂酰肌醇3-激酶/蛋白激酶B(P13K/Akt)信号通路特异性阻断剂LY294002对胃癌AGS细胞体外增殖及侵袭、转移的影响;初步探讨其可能的作用机制.方法 将细胞分成对照组(仅加入含10%胎牛血清的RPMI 1640培养液)、LY294002组(20μmol/L)、sCD40L组(2μg/ml)和LY294002+sCD40L组.四甲基偶氮唑盐法检测不同浓度sCD401,及联合LY294002对细胞增殖的影响;Transwell实验和划痕实验分析细胞侵袭、转移能力的改变;Western印迹检测细胞P13K、p-Akt、血管内皮生长因子(VEGF)蛋白表达的变化.结果 LY294002作用后细胞生存率为65.7%,sCD40L作用后为70.1%,LY294002+sCD40L组生存率为41.3 0A,差异有统计学意义(P<0.05).LY294002+sCD40L组细胞的划痕愈合速度较sCD40L和LY294002组明显减慢.LY294002+sCD40L组平均每个视野的细胞数较sCD40L和LY294002组明显减少.与对照组相比,sCD40L使P13K、p-Akt、VEGF蛋白表达升高,与LY294002联合作用后,P13K,p-Akt、VEGF蛋白表达明显降低.结论 阻断P13K/Akt信号途径可显著增强sCD40L对人胃癌AGS细胞增殖及侵袭、转移的抑制作用,为胃癌的生物治疗提供一种新的方法.     

Proliferation of cardiomyocytes derived from human embryonic stem cells is mediated via the IGF/PI 3-kinase/Akt signaling pathway

Cardiomyocytes from common experimental animals rapidly exit the cell cycle upon isolation, impeding studies of basic cell biology and applications such as myocardial repair. Here we examined proliferation of cardiomyocytes derived from human and mouse embryonic stem (ES) cells. While mouse ES cell-derived cardiomyocytes showed little proliferation, human cardiomyocytes were highly proliferative under serum-free conditions (15-25% BrdU+/sarcomeric actin+). The cells exhibited only a small serum dose-response, and proliferation gradually slowed with increasing differentiation of the cells. Neither cell density nor different matrix attachment factors affected cardiomyocyte proliferation. Blockade of phosphatidylinositol 3-kinase (PI 3-kinase) and Akt significantly reduced cardiomyocyte proliferation, whereas MEK inhibition had no effect. Antibody blocking of the insulin-like growth factor-1 (IGF-1) receptor significantly inhibited cardiomyocyte proliferation, while addition of IGF-1 or IGF-2 stimulated cardiomyocyte proliferation in a dose-dependent manner. Thus, cardiomyocytes derived from human ES cells proliferate extensively in vitro, and their proliferation appears to be mediated primarily via the PI 3-kinase/Akt signaling pathway, using the IGF-1 receptor as one upstream activator. This system should permit identification of regulatory pathways for human cardiomyocyte proliferation and may facilitate expansion of cardiomyocytes from human ES cells for therapeutic purposes.     

TBL1XR1 induces cell proliferation and inhibit cell apoptosis by the PI3K/AKT pathway in pancreatic ductal adenocarcinoma

BACKGROUND Pancreatic ductal adenocarcinoma(PDAC) is one of the deadliest solid tumors. Identification of diagnostic and therapeutic biomarkers for PDAC is urgently needed. Transducin(β)-like 1 X-linked receptor 1(TBL1 XR1) has been linked to the progression of various human cancers. Nevertheless, the function and role of TBL1 XR1 in pancreatic cancers are unclear.AIM To elucidate the function and potential mechanism of TBL1 XR1 in the development of PDAC.METHODS Ninety patients with histologically-confirmed PDAC were included in this study. PDAC tumor samples and cell lines were used to determine the expression of TBL1 XR1. CCK-8 assays and colony formation assays were carried out to assess PDAC cell viability. Flow cytometry was performed to measure the changes in the cell cycle and cell apoptosis. Changes in related protein expression were measured by western blot analysis. Animal analysis was conducted to confirm the impact of TBL1 XR1 in vivo.RESULTS Patients with TBL1 XR1-positive tumors had worse overall survival than those with TBL1 XR1-negative tumors. Moreover, we found that TBL1 XR1 strongly promoted PDAC cell proliferation and inhibited PDAC cell apoptosis. Moreover, knockdown of TBL1 XR1 induced G0/G1 phase arrest. In vivo animal studies confirmed that TBL1 XR1 accelerated tumor cell growth. The results of western blot analysis showed that TBL1 XR1 might play a key role in regulating PDAC cell proliferation and apoptosis via the PI3 K/AKT pathway.CONCLUSION TBL1 XR1 promoted PDAC cell progression and might be an effective diagnostic and therapeutic marker for pancreatic cancer.     

Up-regulated Wnt1-inducible signaling pathway protein 1 correlates with poor prognosis and drug resistance by reducing DNA repair in gastric cancer

BACKGROUND Wnt1-inducible signaling pathway protein 1(WISP1) is upregulated in several types of human cancer,and has been implicated in cancer progression.However,its clinical implications in gastric cancer(GC) remain unclear.AIM To explore the expression pattern and clinical significance of WISP1 in GC METHODS Public data portals,including Oncomine,The Cancer Genome Atlas database,Coexpedia,and Kaplan-Meier plotter,were analyzed for the expression and clinical significance of WISP1 mRNA levels in GC.One hundred and fifty patients who underwent surgery for GC between February 2010 and October 2012 at the Affiliated Hospital of Jiangnan University were selected for validation study.WISP1 levels were measured at both the mRNA and protein levels by RTqPCR,Western blot analysis,and immunohistochemistry(IHC).In addition,the in situ expression of WISP1 in the GC tissues was determined by IHC,and the patients were accordingly classified into high-and low-expression groups.The correlation of WISP1 expression status with patient prognosis was then determined by univariate and multivariate Cox regression analyses.WISP1 was knocked down by RNA interference.The 50% inhibitory concentration of oxaliplatin was detected by CellTiter-Blue assay.RESULTS WISP1 levels at both the mRNA and protein levels were remarkably upregulated in GC tissues compared to normal tissues.Moreover,IHC revealed that WISP1 expression was associated with T stage and chemotherapy outcome,but not with lymph node metastasis,age,gender,histological grade,or histological type.GC patients with high WISP1 expression showed a poor overall survival.Multivariate survival analysis indicated that WISP1 was an important prognostic factor for GC patients.Mechanistically,knock-down of WISP1 expression enhanced sensitivity to oxaliplatin by reducing DNA repair and enhancing DNA damage.CONCLUSION Significantly upregulated WISP1 expression is associated with cancer progression,chemotherapy outcome,and prognosis in GC.Mechanistically,knock-down of WISP1 expression enhances oxaliplatin sensitivity by reducing DNA repair and enhancing DNA damage.WISP1 may be a potential therapeutic target for GC treatment or a potential biomarker for diagnosis and prognosis.     

PTEN/PI3K/AKT蛋白、miR-21在青海藏族及汉族胃癌患者癌组织中的表达差异

目的探讨PTEN/PI3K/AKT蛋白、miR-21在青海藏族及汉族胃癌患者癌组织中的表达差异。方法选取2016年12月至2018年12月我院胃肠外科进行手术的78例胃癌患者为研究对象(藏族38例,汉族40例)。采用实时荧光定量PCR法检测癌组织标本及癌旁组织中miR-21水平,采用免疫组化染色法检测PTEN/PI3K/AKT蛋白,分析不同民族胃癌患者不同组织PTEN/PI3K/AKT蛋白、miR-21表达情况,同时分析其与临床病理特征之间的关系。结果汉族、藏族胃癌患者癌组织中miR-21表达水平高于癌旁组织(P<0.05),且汉族癌组织中miR-21表达水平明显高于藏族(P<0.05)。汉族、藏族胃癌患者癌组织中PTEN、PI3K、AKT蛋白阳性率比较,差异均有统计学意义(P<0.05),其中汉族胃癌组织中PTEN蛋白阳性率低于藏族,但PI3K、AKT蛋白阳性率高于藏族(P<0.05)。两民族胃癌组织中的PTEN、AKT蛋白、miR-21表达与TNM分期、分化程度、淋巴转移相关(P<0.05),PI3K蛋白表达与TNM分期、淋巴转移相关(P<0.05)。在汉族、藏族胃癌患者中,miR-21与PTEN蛋白均呈负相关,与PI3K、AKT蛋白均呈正相关(P<0.05)。结论PTEN在藏族、汉族胃癌患者中表达水平降低,且汉族表达低于藏族,且PTEN与PI3K、AKT呈负相关,miR-21可能通过抑制PTEN,激活PI3K、AKT信号通路从而参与胃癌患者的发生、发展。     

白芨多糖对心肌梗死大鼠PI3K/AKT/GRP78信号通路及心肌细胞内质网应激凋亡的影响

目的 探究白芨多糖对心肌梗死(MI)大鼠磷脂酰肌醇-3-激酶(PI3K)/蛋白激酶B(AKT)及葡萄糖调节蛋白(GRP)78信号通路蛋白表达及对心肌细胞内质网(ERS)凋亡的影响.方法 SD大鼠随机分为假手术组、模型组、白芨多糖低(100 mg/kg)、中(200 mg/kg)、高(400 mg/kg)剂量组、阳性对照...     

肿瘤相关成纤维细胞外泌体调控PI3K/AKT/mTOR信号通路影响肺癌细胞的生长和转移

目的 探究肿瘤相关成纤维细胞外泌体对肺癌细胞生长和转移的影响及机制.方法 取肺癌患者的癌组织和癌旁组织分离肿瘤相关成纤维细胞(Cancer-associated fibroblasts,CAFs)和成纤维细胞(Nor-mal Fibroblasts,NFs),免疫荧光和Western blot鉴定CAFs和NFs中α-...