PI3K/Akt信号转导通路在非小细胞肺癌中的作用

肺癌是当今世界严重威胁人类健康和生命的疾病,其中85%是非小细胞肺癌(NSCLC)。PI3K/Akt通路在NSCLC的发生、发展中具有重要的作用,可以调控细胞存活、增殖、抗凋亡、血管生成等影响肿瘤的发生发展,而且某些蛋白的表达还是NSCLC不良预后的标志。在此我们对PI3K/Akt通路在NSCLC中的分子机制进行总结,并进一步讨论NSCLC的多靶点治疗。     

Resveratrol-induced apoptosis in human T-cell acute lymphoblastic leukaemia MOLT-4 cells

Resveratrol (RES) is a natural occurring phytoalexin that has been shown to have chemopreventive activity. Resveratrol acts both by suppressing cell proliferation and inducing apoptosis in a variety of cancer cell lines. In this study, we show that RES induces apoptosis in MOLT-4 acute lymphoblastic leukaemia cells by modulating three different pathways that regulate cells survival and cell death. We show for the first time that RES inhibits the survival signalling pathways Notch and their down stream effector and modulates the operation of interacting signalling systems. It induces an increase in the levels of the pro-apoptotic proteins p53, its effector p21waf and Bax. We also show that RES inhibits the PI3K/Akt pathway and activates Gsk-3beta. The data presented here demonstrate unequivocally that RES induces apoptosis by inhibiting the Notch pathway and markedly influencing the operation of the interacting apoptosis pathways mediated by p53 and PI3K/Akt. These data support findings from other laboratories that have suggested the use of RES as a chemopreventive agent. Here, we have identified potential signalling pathways influenced by RES and this could lead to the identification of the targets of RES-induced apoptosis and growth control.     

Implication of NAG-1 in synergistic induction of apoptosis by combined treatment of sodium salicylate and PI3K/MEK1/2 inhibitors in A549 human lung adenocarcinoma cells

Aspirin is used as chemopreventive agents in a variety of human cancer cells including those of colon, lung, breast, and leukemia. Sodium salicylate (NaSal, the natural deacetylated form of aspirin) induced cell cycle arrest and apoptosis in a dose-dependent manner in A549 cells; high dose (20mM) of NaSal-induced apoptosis, whereas low dose (2-10mM) induced cell cycle arrest. We found that NaSal-activated Akt/PKB, ERK1/2, and p38MAPK signal cascades. Twenty micromolar of NaSal-induced apoptotic response of A549 cells was enhanced by the PI3K inhibitors (LY294002 and wortmannin) and in a less extent by the MEK1/2 inhibitors (U0126 and PD98059), whereas it was suppressed by the p38MAPK inhibitor (SB203580). Furthermore, simultaneous inhibition of the Akt/PKB and ERK1/2 signal cascades could lower the dose of NaSal to induce apoptosis to 2mM in A549 lung cancer cells. Similar enhancement was observed in cells treated with 2mM NaSal and 100muM genistein, an inhibitor of receptor tyrosine kinases (RTKs) that are upstream of PI3K and MEK1/2 signaling. We further demonstrated that NAG-1 plays a key role in apoptosis by NaSal-based combined treatment. Collectively, our findings indicate that inhibition of the pro-survival Akt/PKB and ERK1/2 signaling may increase the chemopreventive effects of NaSal and combined treatment of two natural compounds (NaSal and genistein) results in a highly synergistic induction of apoptosis, thereby increasing the chemopreventive effects of NaSal against cancer.     

Suppression of human lung cancer cell proliferation and metastasis in vitro by the transducer of ErbB-2.1 (TOB1)

Aim:

To investigate the effects of the transducer of ErbB-2.1 (TOB1) on the proliferation, migration and invasion of human lung cancer cells in vitro.

Methods:

Human lung cancer cell lines (95-D, A549, NCI-H1299, NCI-H1975, NCI-H661, NCI-H446, NCI-H1395, and Calu-3) and the normal human bronchial epithelial (HBE) cell line were tested. The expression levels of TOB1 in the cells were determined with Western blot and RT-PCR analyses. TOB1-overexpressing cell line 95-D/TOB1 was constructed using lipofectamine-induced TOB1 recombinant plasmid transfection and selective G418 cell culture. The A549 cells were transcend-transfected with TOB1-siRNA. MTT assay, flow cytometry and Western blot analysis were used to examine the effects of TOB1 on cancer cell proliferation and wound healing. Transwell invasive assay was performed to evaluate the effects of TOB1 on cancer cell migration and invasion. The activity of MMP2 and MMP9 was measured using gelatin zymography assay.

Results:

The expression levels of TOB1 in the 8 human lung cancer cell lines were significantly lower than that in HBE cells. TOB1 overexpression inhibited the proliferation of 95-D cells, whereas TOB1 knockdown with TOB1-siRNA promoted the growth of A549 cells. Decreased cell migration and invasion were detected in 95-D/TOB1 cells, and the suppression of TOB1 enhanced the metastasis in A549 cells. TOB1 overexpression not only increased the expression of the phosphatase and tensin homolog (PTEN), an important tumor suppressor, but also regulated the downstream effectors in the PI3K/PTEN signaling pathway, including Akt, ERK1/2, etc. In contrast, decreased expression of TOB1 oppositely regulated the expression of these factors. TOB1 also regulates the gelatinase activity of MMP2 and MMP9 in lung cancer cells.

Conclusion:

The results demonstrate that the PI3K/PTEN pathway, which is essential for carcinogenesis, angiogenesis, and metastasis, may be one of the possible signaling pathways for regulation of proliferation and metastasis of human lung cancer cells by TOB1 in vitro.     

Modulation of cell sensitivity to antitumor agents by targeting survival pathways

The advent of drugs targeting tumor-associated prosurvival alterations of cancer cells has changed the interest of antitumor drug development from cytotoxic drugs to target-specific agents. Although single-agent therapy with molecularly targeted agents has shown limited success in tumor growth control, a promising strategy is represented by the development of rational combinations of target-specific agents and conventional antitumor drugs. Activation of survival/antiapoptotic pathways is a common feature of cancer cells that converge in the development of cellular resistance to cytotoxic agents. The survival pathways implicated in cellular response to drug treatment are primarily PI3K/Akt and Ras/MAPK, which also mediate the signalling activated by growth factors and play a role in the regulation of critical processes including cell proliferation, metabolism, apoptosis and angiogenesis. Inhibitors of PI3K, Akt and mTOR have been shown to sensitize selected tumor cells to cytotoxic drugs through multiple downstream effects. Moreover, the MAPK pathway, also implicated in the regulation of gene expression in response to stress stimuli, can interfere with the chemotherapy-induced proapoptotic signals. Targeting Hsp90, which acts as a molecular chaperone for survival factors including Akt, may have the potential advantage to simultaneously block multiple oncogenic pathways. Overall, the available evidence supports the interest of rationally designed approaches to enhance the efficacy of conventional antitumor treatments through the inhibition of survival pathways and the notion that the concomitant targeting of multiple pathways may be a successful strategy to deal with tumor heterogeneity and to overcome drug resistance of tumor cells.     

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.     

牡丹苷A诱导人肺癌A549细胞凋亡的作用和机制

目的:研究牡丹苷A对人肺癌A549细胞株的作用以及其诱导人肺癌A549细胞株凋亡机制。方法:本研究采用MTT法检测牡丹苷A对体外人肺癌细胞株A549增殖率的影响。Annexin V/PI双标法检测牡丹苷A对A549凋亡率,蛋白免疫印迹法和细胞免疫细胞化学法分别检测牡丹苷A对A549细胞株PI3K,Akt,NF-κBp65,Bax,Bcl-2的表达,并采用PI3K/Akt/NF-κB通路的激动剂IGF-1和抑制剂wortmannin进一步探讨牡丹苷A对PI3K/Akt/NF-κB信号通路的作用。结果:牡丹苷A能够抑制A549的增殖,上调Bax蛋白的表达量,下调Bcl-2蛋白的表达量,Bcl-2/Bax比值显著降低,同时降低PI3K, NF-κBp65的蛋白表达,抑制Akt磷酸化。结论:牡丹苷A能够阻碍A549增殖,并促进其凋亡,其诱导凋亡的机制可能与抑制PI3K/Akt/NF-κB通路有关。     

Targeting the phosphatidylinositol-3 kinase/Akt pathway for the treatment of cancer

Phosphatidylinositol-3 kinase (PI3K)/Akt is overactivated in a wide range of tumor types, and this triggers a cascade of responses, from cell growth and proliferation to survival, motility, epithelial-mesenchymal transition and angiogenesis. Therefore, this pathway presents an exciting target for molecular therapeutics. In addition, ectopic expression of PI3K or Akt, especially constitutively activated PI3K (p110alpha) or Akt, is sufficient to induce the oncogenic transformation of cells and tumor formation in transgenic mice, as well as the development of chemoresistance. Inhibition of PI3K/Akt signaling induces apoptosis and inhibits the growth of tumor cells that have elevated Akt levels. The dependence of certain tumors on PI3K/Akt signaling for survival and growth has wide implications for cancer therapy, offering the potential for preferential tumor cell killing. In the past few years, a number of inhibitors of the Akt pathway have been identified by combinatorial chemistry, high-throughput and virtual screening, or traditional medicinal chemistry. This review focuses on ongoing translational efforts to therapeutically target the PI3K/Akt pathway.     

抑制PI3K/Akt信号通路对HER-2/neu诱导的Ishikawa细胞增殖的影响

目的研究抑制磷脂酰肌醇3激酶(PI3K)/蛋白激酶B(Akt)信号通路对表皮生长因子受体2(HER-2/neu)诱导的雌激素依赖性子宫内膜癌细胞增殖的拮抗作用。方法①表皮生长因子(EGF)处理Ishika-wa细胞株及转染HER-2/neu的Ishikawa细胞株,蛋白印迹法检测转染细胞前后总Akt(t-Akt)及磷酸化Akt(p-Akt)蛋白、环氧化酶(COX)-2蛋白的表达。酶联免疫吸附试验(ELISA)方法检测细胞培养上清液中雌二醇(E2)的含量。②用PI3K/Akt的抑制剂LY294002抑制信号通路,以不同时间(浓度为20μmol/L时,分别作用10,20,40和60min)和不同浓度(5,10,20和40μmol/L)作用30min后,再次检测COX-2的表达水平,ELISA检测E2水平。结果 HER-2/neu可引起子宫内膜癌细胞Akt活化,经EGF刺激后p-Akt/t-Akt比值、COX-2及细胞上清液中E2的表达量在转染组显著高于未转染组(P<0.05)。应用抑制剂抑制PI3K/Akt通路后,转染HER-2/neu的Ishikawa细胞株中COX-2的表达水平低于正常的Ishikawa细胞株,同时细胞上清液中肿瘤E2的含量于转染HER-2/neu的Ishikawa细胞株明显低于正常Ishikawa细胞株(P<0.05);随药物浓度的增加及作用时间的延长,2组细胞COX-2及E2的表达均逐渐减少,且抑制作用与浓度及作用时间呈依赖关系。结论 HER-2/neu可能通过PI3K/Akt通路来诱导COX-2的转录,进而导致雌激素的分泌增多,使子宫内膜癌细胞无限生长。     

Ginsenoside Rd prevents and rescues rat intestinal epithelial cells from irradiation-induced apoptosis

Panax ginseng has been shown to have a protective effect for irradiated animals or cells. Ginsenosides are the most active components isolated from ginseng, and ginsenoside Rd has been identified as one of the effective compounds responsible for the pharmaceutical actions of ginseng. In the present study, we studied the molecular mechanisms for the radio-protective action of ginsenoside Rd in rat intestinal epithelial IEC-6 cells. Cells were irradiated with gamma-ray, and apoptosis was examined using Hoechst staining and Western blot analysis. Treatment with ginsenoside Rd before gamma-irradiation inhibited irradiation-induced apoptosis in IEC-6 cells. Administration of Rd after irradiation also inhibited apoptosis in these cells. Irradiation of IEC-6 cells resulted in inactivation of Akt phosphorylation that was abrogated by Rd. On the other hand, irradiation activated phosphorylation of ERK1/2 but did not affect that of p38 MAPK. Inhibition of Akt phosphorylation prevented the reduction of apoptosis by Rd following irradiation. Pretreatment with an inhibitor of the MEK pathway further decreased the number of apoptotic cells. Rd decreased the ratios of Bax/Bcl-2 and Bax/Bcl-xL, the levels of cytochrome c, and the cleaved form of caspase-3 in irradiated IEC-6 cells. Our results suggest that ginsenoside Rd protects and rescues rat intestinal epithelial cells from irradiation-induced apoptosis through a pathway requiring activation of PI3K/Akt, inactivation of MEK, and also inhibition of a mitochondria/caspase pathway.     

PI3K and Akt as molecular targets for cancer therapy: current clinical outcomes

The PI3K-Akt pathway is a vital regulator of cell proliferation and survival. Alterations in the PIK3CA gene that lead to enhanced PI3K kinase activity have been reported in many human cancer types, including cancers of the colon, breast, brain, liver, stomach and lung. Deregulation of PI3K causes aberrant Akt activity. Therefore targeting this pathway could have implications for cancer treatment. The first generation PI3K-Akt inhibitors were proven to be highly effective with a low IC₅₀, but later, they were shown to have toxic side effects and poor pharmacological properties and selectivity. Thus, these inhibitors were only effective in preclinical models. However, derivatives of these first generation inhibitors are much more selective and are quite effective in targeting the PI3K-Akt pathway, either alone or in combination. These second-generation inhibitors are essentially a specific chemical moiety that helps to form a strong hydrogen bond interaction with the PI3K/Akt molecule. The goal of this review is to delineate the current efforts that have been undertaken to inhibit the various components of the PI3K and Akt pathway in different types of cancer both in vitro and in vivo. Our focus here is on these novel therapies and their inhibitory effects that depend upon their chemical nature, as well as their development towards clinical trials.     

miR-29a对口腔鳞癌细胞增殖、迁移和侵袭的影响

目的 以PIK3R2为靶点,探讨miR-29a介导的PI3K/Akt信号通路对口腔鳞癌SCC-9细胞增殖、迁移和侵袭的影响.方法 以RT-PCR法检测miR-29a在SCC-9细胞中的表达.以MTT法、细胞划痕实验、Transwell法和Western blot检测SCC-9细胞的增殖、迁移、侵袭和蛋白表达水平.结果 ...     

Ellagic acid prevents rat colon carcinogenesis induced by 1, 2 dimethyl hydrazine through inhibition of AKT-phosphoinositide-3 kinase pathway

Colon cancer is the third most malignant neoplasm in the world and chemoprevention through dietary intervention is an emerging option to reduce its mortality. Ellagic acid (EA) a major component of berries possesses attractive biological deeds. This study is aimed to investigate the effect of ellagic acid in fostering apoptosis in 1,2-dimethyl hydrazine (DMH) mediated experimental colon carcinogenesis model. Wistar male rats were segregated into four groups: group I-control rats, group II-rats received ellagic acid (60 mg/kg body weight p.o. every day), rats in group III-induced with DMH (20 mg/kg body weight, s.c.) for 15 weeks, DMH-induced group IV rats were initiated with ellagic acid treatment. The present study is designed to explore the significance of phosphoinositide-3-kinase (PI3K)/Akt molecular pathway as well as ellagic acid's chemopreventive effect in colon cancer. DMH-induced rats exhibited elevated expressions of PI3K and Akt as confirmed by immunofluorescence, immunoblot and confocal microscopic analysis. Mechanistically, ellagic acid was found to prevent PI3K/Akt activation that in turn, results in modulation of its downstream Bcl-2 family proteins. Bax expression and caspase-3 activation was noted after ellagic acid supplementation leading to elevation of cytochrome c (cyt c) levels and finally cell death. These observations were supported by the DNA fragmentation results, which showed the occurrence of apoptosis. This study reveals the involvement of PI3K-Akt signaling through which ellagic acid induces apoptosis and subsequently suppresses colon cancer during DMH-induced rat colon carcinogenesis. In conclusion, our findings demonstrate that ellagic acid begets apoptosis in DMH-induced colon carcinoma.     

基于PI3K-Akt信号通路研究罗哌卡因对肺癌细胞A549细胞生物学功能的影响

目的 探讨罗哌卡因(Ropivacaine)通过磷脂酰肌醇-3激酶(Phospoinositide 3-kinase,PI3K)/蛋白激酶B(Protein kinase B,Akt)信号通路影响肺癌细胞A549增殖、迁移、侵袭和凋亡.方法 采用细胞计数试剂盒8(CCK-8)法检测(0、100、200和400 μg/m...     

PI3K/Akt/mTOR pathway dual inhibitor BEZ235 suppresses the stemness of colon cancer stem cells

Colon cancer is one of the most common cancers worldwide with high mortality. A major issue in colon cancer treatment is drug‐resistance and metastasis that have been ascribed to the cancer stem cells. In this study, colon cancer stem cells were isolated through sphere culture and verified with the cancer stem cell markers CD133, CD44, and CD24. It was demonstrated that the PI3K/Akt/mTOR signalling pathway was highly activated in the colon cancer stem cells and that inhibition of the PI3K/Akt/mTOR pathway by the inhibitor BEZ235 suppressed the colon cancer stem cell proliferation with reduced stemness indicated by CD133 and Lgr5 expressions. Treatment with insulin as a known activator of the PI3K/Akt pathway increased CD133 expression and decreased the effects of BEZ235 on colon cancer proliferation and survival. The data presented here collectively suggest that the PI3K/Akt/mTOR pathway underpins the stemness of colon cancer stem cells and BEZ235 is potentially a good drug candidate for treatment of colon cancer drug resistance and metastasis.     

Apigenin inhibits HGF-promoted invasive growth and metastasis involving blocking PI3K/Akt pathway and beta 4 integrin function in MDA-MB-231 breast cancer cells

Hepatocyte growth factor (HGF) and its receptor, Met, known to control invasive growth program have recently been shown to play crucial roles in the survival of breast cancer patients. The diet-derived flavonoids have been reported to possess anti-invasion properties; however, knowledge on the pharmacological and molecular mechanisms in suppressing HGF/Met-mediated tumor invasion and metastasis is poorly understood. In our preliminary study, we use HGF as an invasive inducer to investigate the effect of flavonoids including apigenin, naringenin, genistein and kaempferol on HGF-dependent invasive growth of MDA-MB-231 human breast cancer cells. Results show that apigenin presents the most potent anti-migration and anti-invasion properties by Boyden chamber assay. Furthermore, apigenin represses the HGF-induced cell motility and scattering and inhibits the HGF-promoted cell migration and invasion in a dose-dependent manner. The effect of apigenin on HGF-induced signaling activation involving invasive growth was evaluated by immunoblotting analysis, it shows that apigenin blocks the HGF-induced Akt phosphorylation but not Met, ERK, and JNK phosphorylation. In addition to MDA-MB-231 cells, apigenin exhibits inhibitory effect on HGF-induced Akt phosphorylation in hepatoma SK-Hep1 cells and lung carcinoma A549 cells. By indirect immunofluorescence microscopy assay, apigenin inhibits the HGF-induced clustering of beta 4 integrin at actin-rich adhesive site and lamellipodia through PI3K-dependent manner. Treatment of apigenin inhibited HGF-stimulated integrin beta 4 function including cell-matrix adhesion and cell-endothelial cells adhesion in MDA-MB-231 cells. By Akt-siRNA transfection analysis, it confirmed that apigenin inhibited HGF-promoted invasive growth involving blocking PI3K/Akt pathway. Finally, we evaluated the effect of apigenin on HGF-promoted metastasis by lung colonization of tumor cells in nude mice and organ metastasis of tumor cells in chick embryo. By histological and gross examination of mouse lung and real-time PCR analysis of human alu in host tissues, it showed that apigenin, wortmannin, as well as anti-beta 4 antibody all inhibit HGF-promoted metastasis. These data support the inhibitory effect of apigenin on HGF-promoted invasive growth and metastasis involving blocking PI3K/Akt pathway and integrin beta 4 function.     

α-Tomatine inactivates PI3K/Akt and ERK signaling pathways in human lung adenocarcinoma A549 cells: Effect on metastasis

This study first investigates the anti-metastastic effect of α-tomatine in the human lung adenocarcinoma cell line: A549. In this study, we first noted α-tomatine inhibited A549 cells invasion and migration by wound-healing assay and Boyden chamber assay. The data also showed α-tomatine could inhibit phosphorylation of Akt and extracellular signal-regulated kinase 1 and 2 (ERK1/2), which is involved in the up-regulating matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) or urokinase-type plasminogen activator (u-PA), whereas it did not affect phosphorylation of c-Jun N-terminal kinase (JNK) and p38. Next, α-tomatine significantly decreased the nuclear levels of nuclear factor kappa B (NF-κB), c-Fos, and c-Jun. Also, treating A549 cells with α-tomatine also leads to a dose-dependent inhibition on the binding abilities of NF-κB and activator protein-1 (AP-1). Further, the treatment of inhibitors specific for PI3K (Wortmannin) or ERK (U0126) to A549 cells could cause reduced activities of MMP-2, MMP-9, and u-PA. These results showed α-tomatine could inhibit the metastatic ability of A549 cells by reducing MMP-2, MMP-9, and u-PA activities through suppressing phosphoinositide 3-kinase/Akt (PI3K/Akt) or ERK1/2 signaling pathway and inhibition NF-κB or AP-1 binding activities. These findings proved α-tomatine might be an anti-metastastic agent against human lung adenocarcinoma.     

Effects and mechanism of proteasome inhibitor YSY01-A alone or in combination with cisplatin against A549 cells in vitro

YSY01-A, as a novel proteasome inhibitor, has shown remarkable proliferation inhibitory effect on certain types of tumor cells. However, few studies have reported its effect on non-small cell lung cancer (NSCLC), and its underlying mechanism remains unknown. In our present study, we aimed to figure out the inhibitory effects as well as the mechanism of proteasome inhibitor YSY01-A against A549 cells both individually and in combination with cisplatin. A549 cell proliferation inhibition was assessed by SRB assay. Its related protein expression levels were determined by western blot assay. Moreover, the change of intracellular cisplatin accumulation was examined by ICP-MS assay. The results suggested that YSY01-A significantly (P<0.001) inhibited the proliferation of A549 cells (IC₅₀ was 36.2 nM for 72 h) in a concentration-dependent and time-dependent manner. Compared with the negative control group, YSY01-A (60 nM, 48 h) down-regulated PI3K/Akt pathway in A549 cells by increasing the expression level of PTEN (P<0.01), and decreasing the expression level of PI3K (P<0.001) and p-Akt/Akt (P<0.001). When combined with cisplatin, YSY01-A of different concentrations (5, 10, 20 nM) could significantly increase the inhibition effects on A549 cells compared with the cisplatin alone treatment, showing a synergistic effect. At the same time, YSY01-A could remarkably block the cisplatin-induced down-regulation of hCTR1 in a concentration-dependent manner and increase cisplatin uptake from 2.01 to 2.47 fold (P<0.001). In conclusion, compound YSY01-A could significantly inhibit proliferation of NSCLC A549 cells, showing a strong synergistic effect when combined with cisplatin. Down-regulation of PI3K/Akt pathway might be the mechanism of inhibitory effect of YSY01-A, and the combination with cisplatin might increase the expression of CTR1 and intracellular cisplatin accumulation.