MircoRNA-214对吉非替尼敏感及耐药细胞增殖和凋亡的影响

摘 要：［目的］ 研究mircoRNA-214（miR-214）对PC9肺腺癌及吉非替尼耐药细胞（PC9/GR）增殖和凋亡的影响。［方法］ 在PC9细胞中转染miR-214模拟物及PC9/GR中转染miR-214抑制剂,使用定量逆转录PCR（qRT-PCR）检测其表达。MTT检测细胞转染miR-214模拟物或其抑制剂后的存活及增殖。在PC9细胞中顺时转染miR-214模拟物以检测上调miR-214对PC9细胞耐药性的影响,在PC9/GR细胞中顺时转染miR-214抑制物以检测下调miR-214对PC9/GR细胞耐药性的影响,并用流式细胞仪检测细胞的凋亡。Western blotting检测PTEN在PC9和PC9/GR细胞中的表达。构建PTEN 3’-UTR荧光素酶报告质粒验证miR-214的靶基因;建立异种移植模型检测miR-214抑制物对肺癌移植瘤的影响。［结果］ PC9细胞中miR-214低表达,上调miR-214的表达后PC9细胞对吉非替尼的敏感性降低,并且抵抗吉非替尼诱导的凋亡;而在PC9/GR细胞中低表达miR-214后,下调miR-214增加PC9/GR细胞对吉非替尼的敏感性,并且可以增强吉非替尼诱导的凋亡作用。荧光素酶报告载体实验证实PTEN是miR-214在细胞内的靶基因。动物异种移植模型表明miR-214抑制物可以增强PC9/GR对吉非替尼的敏感性。［结论］ MiR-214可能通过靶基因PTEN调控吉非替尼的获得性耐药。     

LncRNA MEG3靶向miR-181a-5p调控宫颈癌细胞放射敏感性

目的 研究LncRNA MEG3对宫颈癌细胞放射敏感性的影响,并探讨其作用机制。方法 运用qRT-PCR法检测放射抗性和放射敏感性宫颈癌细胞中LncRNA MEG3的表达;将过表达对照组(转染pcDNA 3.1)、过表达LncRNA MEG3组(转染pcDNA 3.1-LncRNA MEG3)、抑制miR-NC组(转染anti-miR-NC)、抑制miR-181a-5p组(转染anti-miR-181a-5p)、过表达LncRNA MEG3+过表达miR-NC组(共转染pcDNA 3.1-LncRNA MEG3和anti-miR-NC)、过表达LncRNA MEG3+过表达miR-181a-5p组(共转染pcDNA 3.1-LncRNA MEG3和anti-miR-181a-5p),均用脂质体法转染至SiHa细胞;克隆形成实验检测细胞的存活分数;流式细胞术检测细胞的凋亡率;双荧光素酶报告基因检测实验检测细胞的荧光活性;Western blot检测细胞中PTEN、p-Akt、Akt的蛋白表达。结果 与放射敏感组相比,放射抗性宫颈癌组织中LncRNA MEG3的表达明显降低(P<0.05),其表达量与宫颈癌细胞的放射敏感性呈正相关;过表达LncRNA MEG3、抑制miR-181a-5p均可显著增强宫颈癌细胞SiHa放射敏感性,促进凋亡(P<0.05);野生型LncRNA MEG3细胞的荧光活性受miR-181a-5p的抑制。过表达miR-181a-5p逆转了LncRNA MEG3对宫颈癌细胞放射增敏和促凋亡作用及对PTEN/Akt信号通路的调控。结论 长链非编码RNA LncRNA MEG3可增强宫颈癌细胞放射敏感性,其机制可能与靶向miR-181a-5p调控PTEN/Akt 信号通路有关,可为提高宫颈癌的预后提供新方向。     

miR-200c增强肺癌A549细胞对紫杉醇及吉非替尼的敏感度及相关机制

目的 观察上调肺癌A549细胞中miR-200c的表达对紫杉醇、吉非替尼敏感度及两药联合作用的影响及其作用机制。方法 用miR-200c转染肺癌A549细胞,Real-time PCR检测miR-200c表达,MTT法和流式细胞仪检测转染miR-200c后A549细胞对紫杉醇、吉非替尼单药及两药联合的敏感度和细胞凋亡的影响,Western blot检测TUBB3蛋白、EGFR、Akt、MAPK磷酸化蛋白及总蛋白的表达。结果 上调miR-200c表达可增强A549细胞对紫杉醇及吉非替尼敏感度并促进细胞凋亡,对两药联合无明显作用。Western blot显示转染miR-200c联合紫杉醇可下调A549细胞中TUBB3蛋白表达,联合吉非替尼下调EGFR和Akt磷酸化蛋白表达,与两药联合对EGFR和Akt磷酸化蛋白表达无明显影响。 结论 miR-200c可增强肺癌A549细胞对紫杉醇、吉非替尼的敏感度,可能分别与抑制TUBB3表达、抑制EGFR和Akt磷酸化蛋白表达有关,而对两药联合无协同抗肿瘤作用。     

Mir-7上调增强肺腺癌对吉非替尼敏感性的机制研究

目的:探索上调Mir-7的表达使肺腺癌A549细胞增强吉非替尼的敏感性及其机制。方法:用lipo-fectamine2000携带Mir-7对A549细胞进行瞬时转染。将A549细胞分为对照组、转染组、吉非替尼组与联合组。MTT法测各组细胞增殖率变化,Transwell检测细胞侵袭性,Real time PCR检测E-Cadherin及N-Cad-herin的mRNA表达的变化,Western blot检测他们的蛋白表达的变化。结果:上调A549细胞中Mir-7的表达与吉非替尼共同作用较单独吉非替尼作用有更显著的抑制作用。用Mir-7转染后,肺腺癌A549细胞的侵袭力下降。转染与吉非替尼联合组E-Cadherin的信使RNA及蛋白的表达变化不大,但N-Cadherin表达下降。结论:上调Mir-7的表达可以增强肺腺癌细胞对吉非替尼的敏感性,其机制可能是过量表达的Mir-7抑制了IGF-1R信号通路及肿瘤上皮细胞间质化。     

PTEN基因转染的子宫内膜癌细胞对阿霉素诱导凋亡的敏感性

目的 探讨PTEN基因是否增强子宫内膜癌细胞系Ishikawa细胞对阿霉素的敏感性。方法 将PTEN基因转染前、后的Ishikawa细胞分别暴露于系列浓度的阿霉素,以MTT法测定这些细胞对阿霉素的敏感性,并通过Hoechst33258染色荧光显微镜观察细胞凋亡情况。同时,以免疫沉淀Western blot法观察阿霉素对Bad和Akt／PKB蛋白磷酸化的影响。结果 阿霉素以剂量依赖方式诱导全部细胞系的细胞凋亡,但对表达PTEN的克隆细胞所诱导的凋亡比对亲本株Ishikawa细胞更明显。低浓度阿霉素（0．1μmol／L）不引起PTEN蛋白缺失的Ishikawa细胞凋亡,但却能诱导表达PTEN蛋白克隆细胞凋亡;高浓度阿霉素（1μmol／L）诱导全部细胞系的细胞凋亡,但凋亡的发生率在表达PTEN的克隆细胞中明显高于亲本株Ishikawa细胞。在表达PTEN的克隆细胞中,磷酸化Akt／PKB和磷酸化Bad（Ser-136）的水平均下降。阿霉素降低了全部细胞系的磷酸化Akt／PKB和磷酸化Bad（Set-136）水平,但在表达PTEN的克隆细胞中降低最明显。结论 PTEN基因转染明显地增强了Ishikawa细胞对阿霉素的化学敏感性,阿霉素可能是通过下调P13k／Akt／PKB信号途径而与PTEN蛋白共同发挥凋亡诱导作用。     

IGF-1R抑制剂联用可增强人非小细胞肺癌PC9/G细胞对吉非替尼的敏感性

目的:观察单用表皮生长因子受体(epidermal growth factor receptor, EGFR)的酪氨酸激酶抑制剂吉非替尼 (ge? tinib) 或联合胰岛素生长因子-1受体(insulin-like growth factor-1 receptor,IGF-1R)的酪氨酸激酶抑制剂AG1024作用于人非小细胞肺癌耐药株PC9/G细胞后,该细胞对吉非替尼耐药性的影响,并探讨IGF-1R与肿瘤细胞耐药的相关机制。方法:用吉非替尼和AG1024单独或联合作用于PC9/G细胞后,采用MTT法分别检测各组细胞的增殖情况,并利用中效原理判断两药联用的效果;FCM法检测各组细胞的凋亡情况;Western印迹法检测各组细胞的磷酸化EGFR(phosphorylated EGFR, p-EGFR)、磷酸化Akt(phosphorylated Akt,p-Akt)和磷酸化细胞外信号调节激酶(phosphorylated extracellular signal-regulated kinase,p-ERK)的表达水平。结果:吉非替尼和AG1024单独作用于PC9/G细胞后,均出现不同程度的细胞增殖抑制作用和细胞凋亡促进作用;而吉非替尼和AG1024联合作用,能更显著地抑制细胞增殖,且凋亡细胞显著增加(P<0.05)。 Western印迹法检测发现,联合用药组的p-EGFR、p-Akt和p-ERK蛋白表达量明显减少。结论:IGF-1R抑制剂AG1024和EGFR抑制剂吉非替尼联用具有较好的协同作用,可能通过抑制细胞增殖和促进细胞凋亡,提高耐药细胞对吉非替尼的敏感性。     

下调miR-23a对EGFR突变非小细胞肺癌细胞吉非替尼耐药的影响研究

目的 探讨抑制miR-23a对EGFR T790M突变非小细胞肺癌H1975细胞吉非替尼耐药性的影响及其可能机制。方法 选取吉非替尼耐药的对数生长期H1975细胞为研究样本,合成miR-23a抑制物（miR-23a inhibitor）,应用脂质体转染H1975细胞以抑制其miR-23a表达（抑制组）,同时设未经转染处理的非转染组和转染无关序列的阴性对照组,实时荧光定量PCR（qRT-PCR）验证转染效果;采用CCK-8法检测转染24、48、72及96 h后各组的增殖情况,同时于转染48 h后用吉非替尼（0.03～300 μmol／L）处理各组细胞以评价对吉非替尼的药物敏感性变化情况;分别用流式细胞术检测各组的凋亡率（FITC-Annexin V／PI双染）和细胞周期（PI单染）情况,免疫印迹法检测各组多药耐药相关蛋白1（MRP1）、肺耐药相关蛋白（LRP）及谷胱甘肽转移酶π（GST-π）的表达变化。结果 抑制组在转染24～96 h出现miR-23a水平的持续下降,其miR-23a水平均低于其余两组,转染 96 h后的miR-23a水平分别为非转染组的（32.06±4.68）％和阴性对照组的（31.77±3.18）％,且吉非替尼对抑制组的半数抑制浓度（IC₅₀）为（2.82±0.46）μmol／L,均低于其余两组,以上差异均有统计学意义（P＜0.05）;与其余两组相比,抑制组转染后增殖抑制率、凋亡率及G0／G1期比例均升高,S期、G2／M期比例均下降且耐药蛋白MRP1、LRP及GST-π蛋白水平亦下调,以上差异均有统计学意义（P＜0.05）。结论 下调miR-23a可逆转H1975细胞的吉非替尼耐药性,同时可抑制细胞增殖、诱导凋亡及细胞周期阻滞,可能与降低耐药蛋白表达有关。     

SEMA3B对人非小细胞肺癌NCI-H1299细胞Akt磷酸化调控作用的实验研究

目的:研究SEMA3B作为潜在的肺癌治疗药物诱导细胞凋亡作用的机制.方法:将pcDNA3.1/pcDNA3.1-SEMA3B质粒转染至Cos7细胞,400μg/ml G418筛选后建立稳定表达SEMA3B的Cos7细胞系.利用含有SEMA3B-Cos7细胞的培养上清液、特异性siRNA、实时定量PCR和蛋白免疫印迹方法,检测SEMA3B蛋白对Akt磷酸化及下游基因表达的影响及分子机制.结果:在细胞培养上清及细胞裂解液中稳定表达SEMA3B的Cos7细胞模型建立;利用含有SEMA3B蛋白的Cos7培养上清液及对照组培养上清液处理NCI-H1299细胞24小时后,含有SEMA3B蛋白组可显著降低H1299细胞内pAkt-ser473的蛋白表达及下游基因MDM2 mRNA表达,增加Caspase3 mRNA表达;特异性siRNA阻断IGFBP6表达,可部分消除SEMA3B抑制Akt磷酸化的作用,并影响其对MDM2和Caspase3的作用.结论:SEMA3B是通过IGFBP6介导其抑制Akt磷酸化作用及其下游基因表达,而发挥诱导非小细胞肺癌细胞凋亡的作用,进一步提示在非小细胞肺癌中SEMA3B的抑癌作用及其潜在的治疗药物价值.     

桦木酸通过抑制STAT3 的活化提高胰腺癌细胞对吉非替尼的敏感性

[摘要] 目的：探讨桦木酸（BEA）提高胰腺癌Panc-1、Miapaca-2 细胞对吉非替尼的敏感性及其潜在的作用机制。方法：细胞培养完成后,将对吉非替尼不敏感的Panc-1、Miapaca-2 细胞随机分为4 组：对照组、BEA组、吉非替尼组及BEA联合吉非替尼组,分别予以不处理、BEA、吉非替尼及BEA联合吉非替尼处理。MTS法检测BEA对2 种细胞的增敏效果,集落形成实验检测BEA协同吉非替尼的治疗效果,WB实验检测BEA对Panc-1 细胞凋亡相关蛋白的影响,流式细胞术检测BEA对Panc-1 细胞凋亡的影响,表面等离子体共振（SPR）实验验证信号转导子和转录激活子3（STAT3）和BEA的直接结合,分子对接和分子动力学模拟实验预测STAT3 和BEA的结合模式。结果：BEA协同增强Panc-1、Miapaca-2 细胞对吉非替尼的敏感性（P<0.05）,使其对两种细胞的IC50值均降低至原值的50%以下。吉非替尼联合BEA较单用吉非替尼或BEA促进Panc-1 细胞的凋亡以及凋亡相关蛋白cleaved-PARP和Bax 的表达,减少对凋亡抑制蛋白Bcl-2 的表达（均P<0.05 或P<0.01）。BEA对Panc-1 细胞中STAT3 的活化有剂量依赖性抑制作用（P<0.01）。BEA通过与STAT3 的Lys-591、Ser-613 形成氢键而稳定BEA与STAT3 的结合作用,同时BEA稳定在STAT3 的蛋白结合位点内,以此阻断STAT3 二聚发挥增敏作用。结论：联用BEA和吉非替尼显著抑制胰腺癌Panc-1、Miapaca-2 细胞的增殖并促进其凋亡,这种增敏作用可能是由BEA对STAT3 抑制作用所介导。     

转录因子XBP1S对人肝癌HepG2细胞增殖及凋亡的影响

目的:探讨人剪接型X盒结合蛋白1(X-box binding protein1spliced,XBP1S)对肝癌HepG2细胞增殖和凋亡的影响。方法:应用衣霉素(tunicamycin,Tm)和毒胡萝卜素(thapsigargin,Tg)建立HepG2细胞的内质网应激(endoplasmic reticulum stress,ERS)模型。将XBP1S真核表达载体pcDNA3.1(-)-XBP1S和靶向XBP1S的RNA干扰质粒pSUPER-XBP1S转染HepG2细胞,MTT法检测细胞的增殖能力,荧光显微镜下观察细胞的形态学变化,FCM法检测细胞凋亡率,Western印迹法检测caspase12的表达。结果:转染pSUPER-XBP1S可有效抑制细胞增殖,而转染pcDNA3.1(-)-XBP1S可促进细胞增殖。荧光显微镜下可见Tm处理组细胞出现细胞凋亡的形态学改变,进一步下调XBP1S的表达可使这一改变增强。对照组、Tm组、Tm+pSUPER-XBP1S转染组和Tm+pcDNA3.1(-)-XBP1S转染组细胞的凋亡率分别为5.21%、41.51%、52.15%和35.87%,差异有统计学意义(P<0.05)。HepG2细胞中caspase12的表达,Tm组高于对照组,Tm+pSUPER-XBP1S转染组高于Tm组,Tm+pcDNA3.1(-)-XBP1S转染组低于Tm组。结论:XBP1S可以促进肝癌HepG2细胞增殖,抑制或促进XBP1S表达可调节ERS介导的细胞凋亡。     

LncRAN MEG3 regulates the radiosensitivity of cervical cancer cells by targeting miR-181a-5p

Objective To evaluate the effect of long-chain non-coding RNA MEG3(LncRNA MEG3) on the radiosensitivity of cervical cancer cells, and to explore its underlying mechanism. Methods The expression of LncRNA MEG3 in cervical cancer cells was detected by qRT-PCR. In the overexpression control group (transfected with pcDNA 3.1), LncRNA MEG3 overexpression group (transfected with pcDNA 3.1-LncRNA MEG3), miR-NC inhibition group (transfected with anti-miR-NC), miR-181a-5p inhibition group (transfected with anti-miR-181a-5p), LncRNA MEG3+miR-NC overexpression group (co-transfected with pcDNA3.1-LncRNA MEG3 and anti-miR-NC), LncRNA MEG3+miR-181a-5p overexpression group (co-transfected with pcDNA 3.1-LncRNA MEG3 and anti-miR-181a-5p), all plasmids were transfected into SiHa cells by liposome method. The cell survival fraction was assessed by colony formation assay. The cell apoptosis rate was evaluated by flow cytometry. The cell fluorescence activity was assessed by dual luciferase reporter assay. The expression levels of PTEN, p-Akt and Akt proteins were detected by Western blot. Results Compared with the radiosensitive group, the expression of LncRNA MEG3 was significantly down-regulated in radiation-resistant cervical cancer tissues (P<0.05), and its expression level was positively correlated with the sensitivity of cervical cancer cells. Overexpression of LncRNA MEG3 or inhibition of miR-181a-5p could significantly enhance the irradiation sensitivity and promote the apoptosis of cervical cancer cell line SiHa (both P<0.05). The fluorescence activity of wild-type LncRNA MEG3 cells was inhibited by miR-181a-5p. Overexpression of miR-181a-5p reversed the irradiation sensitization and pro-apoptosis effect of LncRNA MEG3 and the regulation of the PTEN/Akt signaling pathway on cervical cancer cell. Conclusion LncRNA MEG3 can enhance the sensitivity of cervical cancer cells to radiation exposure, probably by targeting the miR-181a-5p and regulating the PTEN/Akt signaling pathway, which will provide a new direction for improving clinical prognosis of cervical cancer patients.     

PTEN基因通过Akt-mTOR对乳腺癌细胞增殖与凋亡的影响

目的:探讨PTEN基因通过Akt-mTOR对乳腺癌细胞增殖与凋亡的影响。方法:人乳腺癌MDA-MB-231细胞随机分为两组:pcDNA3.0组与pcDNA3.0-PTEN组,分别转染pcDNA3.0质粒、pcDNA3.0-PTEN质粒2 μg,转染48 h收集细胞。采用CCK-8法检测细胞存活率,双染法检测细胞凋亡,Western-blot检测细胞蛋白表达。结果:pcDNA3.0-PTEN组的细胞存活率低于pcDNA3.0组,对比差异有统计学意义(P＜0.05)。与pcDNA3.0组对比,pcDNA3.0-PTEN组的细胞凋亡率显著上升,对比差异有统计学意义(P＜0.05)。pcDNA3.0-PTEN组的PTEN蛋白表达量高于pcDNA3.0组,Akt、mTOR蛋白表达量低于pcDNA3.0组,对比差异有统计学意义(P＜0.05)。结论:PTEN基因过表达可通过抑制Akt-mTOR信号通路,提高乳腺癌细胞凋亡指数,降低细胞增殖活性,从而发挥抑癌作用。     

抑癌基因PTEN依赖其磷酸活性诱导人膀胱癌细胞BIU-87失巢凋亡机制

Objective： To investigate the effects and mechanisms of tumor suppressor gene PTEN on the induction of anoikis of human bladder transitional carcinoma cells BIU-87. Methods： BIU-87 cells were transfected with GFP plasmids containing wild-type PTEN or phosphatase inactivating mutant PTEN （C124A-PTEN） in vitro. The PTEN expression and the phosphorylation levels of focal adhesion kinase （FAK） and protein kinase B （PKB/Akt） were detected by Western blotting. Flow cytometry assay and laser scanning confocal microscopy were used to analyze apoptosis in adherent and non-adherent cells. Results： Compared with the control group; PTEN expression in the cells transfected with wild-type PTEN increased to 210%-260%, while the phosphorylation level of FAK and Akt decreased 59% （ P 〈 0.01） and 89% （ P 〈 0.01）, respectively. And the anoikis percentage increased from 8,32 ± 0.57% to 37.62 ± 2.12%, In the cells transfected with C124A-PTEN, neither the phosphorylation of FAK and Akt nor the anoikis percentage had obviously changed, although the PTEN expression enhanced remarkably in comparison with the control. Conclusion： Through its phosphatase activity, tumor suppressor gene PTEN can suppress the phosphorylation of FAK and Akt, and induce anoikis in human bladder transitional carcinoma cells BIU-87.     

PTEN依赖其磷酸酶活性诱导肝癌细胞发生失巢凋亡机制的探讨

目的 研究抑癌基因PTEN对人肝癌SMMC-7721细胞失巢凋亡的影响并探讨其可能的机制。方法 将携有野生型PTEN基因及无磷酸活性的突变型C124A-PTEN基因的真核表达载体转染SMMC-7721细胞,利用Western印迹杂交法,检测PTEN蛋白表达与蛋白激酶B(PKB／Akt)、焦点黏附激酶(FAK)磷酸化水平的变化,并应用流式细胞仪技术和激光共聚焦显微镜技术,分析各种细胞在黏附与失黏附状态下的凋亡。结果 与对照细胞相比,转染野生型PTEN的SMMC-7721细胞中,FAK和Akt的磷酸化水平分别降低了65．2％和89．1％,且失巢凋亡率由9．5％增至31．3％;而转染C124A-PTEN的SMMC-7721细胞中,FAK和Akt的磷酸化水平及失巢凋亡率均无明显变化。结论 抑癌基因PTEN可依赖其磷酸酶活性抑制FAK和Akt的磷酸化,并诱导肝癌细胞发生失巢调亡。     

PTEN sensitizes prostate cancer cells to death receptor-mediated and drug-induced apoptosis through a FADD-dependent pathway.

The PTEN tumor suppressor is frequently mutated in human tumors. Loss of PTEN function is associated with constitutive survival signaling through the phosphatidylinositol-3 kinase/Akt pathway. Therefore, we asked if reconstitution of PTEN function would lead to the reversal of resistance to apoptosis in prostate cancer cells. Adenovirus-mediated expression of PTEN completely suppressed constitutive Akt activation in LNCaP prostate cancer cells and enhanced apoptosis induced by a broad range of apoptotic stimuli. PTEN expression sensitized cells to death receptor-mediated apoptosis induced by tumor necrosis factor, anti-Fas antibody, and TRAIL. PTEN also sensitized cells to non-receptor mediated apoptosis induced by a kinase inhibitor staurosporine and chemotherapeutic agents mitoxantrone and etoposide. PTEN-mediated apoptosis was accompanied by caspase-3 and caspase-8 activation and was inhibited by a broad specificity caspase inhibitor Z-VAD-fmk. Bcl-2 overexpression also blocked PTEN-mediated apoptosis. Lipid phosphatase activity of PTEN is required for apoptosis as the PTEN G129E mutant selectively deficient in lipid phosphatase activity was unable to sensitize cells to apoptosis. PTEN-mediated apoptosis involves a FADD-dependent pathway for both death receptor-mediated and drug-induced apoptosis as coexpression of a dominant negative FADD mutant blocked PTEN-mediated apoptosis. Since in death receptor signaling, FADD mediates activation of caspase-8, which in turn cleaves BID, and since caspase-8 is activated in PTEN-mediated apoptosis, we examined BID cleavage in PTEN-mediated apoptosis. PTEN facilitated BID cleavage after treatment with low doses of staurosporine and mitoxantrone. BID cleavage was inhibited by dominant negative FADD. Taken together, these data are consistent with the hypothesis that PTEN promotes drug-induced apoptosis by facilitating caspase-8 activation and BID cleavage through a FADD-dependent pathway.     

PTEN/PI3K/Akt信号通路对K562细胞凋亡调控的研究

 目的 探讨PTEN/PI3K/Akt信号传导通路对人慢性粒细胞白血病细胞系K562的增殖、凋亡调控的研究及可能的分子作用机制。 方法 将携带有野生型PTEN及绿色荧光蛋白的腺病毒（Ad-PTEN-GFP）及空载体（Ad-GFP）腺病毒,转染人慢性粒细胞白血病细胞系K562。通过MTT检测细胞生长曲线,流式细胞术检测细胞凋亡率和细胞增殖指数,同时用细胞光镜、电镜形态等方法检测细胞凋亡,荧光定量PCR（FQ-PCR）检测PTEN及凋亡相关基因Bcl-2、Bcl-_xL、Bax mRNA水平变化,Western blot检测PTEN及Akt、p-Akt蛋白水平变化。 结果 与Ad-GFP组相比,Ad-PTEN-GFP 转染K562细胞后,细胞增殖受抑,增殖指数降低,凋亡率增加,p-Akt表达降低,抗凋亡相关基因Bcl-2、Bcl-_xL mRNA表达降低,促凋亡基因Bax mRNA表达增加。 结论 过表达PTEN可能通过抑制PI3K/Akt通路抑制K562细胞系增殖,促进细胞凋亡。     

Enhanced cytotoxicity induced by gefitinib and specific inhibitors of the Ras or phosphatidyl inositol-3 kinase pathways in non-small cell lung cancer cells

In this study, we have characterized a panel of NSCLC cell lines with differential sensitivity to gefitinib for activating mutations in egfr, pik3ca, and k-ras, and basal protein expression levels of PTEN. The egfr mutant NSCLC cell line H1650 as well as the egfr wild type cell lines H292 and A431 were highly sensitive to gefitinib treatment, indicating that other factors determine gefitinib-sensitivity in egfr wild type cells. Activating k-ras mutations were specifically detected in gefitinib-resistant cells, suggesting that the occurrence of k-ras mutations is correlated with resistance to EGFR antagonists. No pik3ca mutations were detected within the panel of cell lines, and PTEN protein expression levels did not correlate with gefitinib sensitivity. Gefitinib effectively blocked Akt and Erk phosphorylation in two gefitinib-sensitive NSCLC cell lines, further supporting our previous findings that persistent activity of the PI3K/Akt and/or Ras/Erk pathways is associated with gefitinib-resistance of NSCLC cell lines. Gefitinib-resistant NSCLC cell lines, showing EGFR-independent activity of the PI3K/Akt or Ras/Erk pathways, were treated with gefitinib in combination with specific inhibitors of mTOR, P13K, Ras, and MEK. Additive cytotoxicity was observed in A549 cells co-treated with gefitinib and the MEK inhibitor U0126 or the farnesyl transferase inhibitor SCH66336 and in H460 cells treated with gefitinib and the PI3K inhibitor LY294002, but not in H460 cells treated with gefitinib and rapamycin. These data suggest that combination treatment of NSCLC cells with gefitinib and specific inhibitors of the PI3K/Akt and Ras/Erk pathways may provide a successful strategy.     

miR-142-5p对人上皮性卵巢癌细胞增殖和凋亡的影响

目的:探讨miR-142-5p靶向PTEN-PI3K/Akt信号调控人上皮性卵巢癌SKOV3细胞增殖和凋亡的具体机制。方法:Real-time PCR检测miR-142-5p在人卵巢癌组织及各卵巢癌细胞系中的表达情况。利用MTT、细胞克隆形成实验观察miR-142-5p对SKOV3细胞增殖活力的影响；Caspase-3活力检测miR-142-5p对SKOV3细胞凋亡情况；信号通路抑制剂处理及Western blot检测miR-142-5p、PTEN与PI3K/Akt信号通路的关系及PI3K/Akt信号下游基因Akt、FOXO1、cyclin D1等的表达情况；Luciferase实验验证miR-142-5p和PTEN 3' UTR的结合。结果:人上皮性卵巢癌组织及其细胞系中miR-142-5p表达显著增加（P<0.05)。与对照组相比，SKOV3细胞转染miR-142-5p mimics后活细胞数量显著增加，增殖能力显著上升，细胞凋亡下降（P<0.05)；与之相反的，转染miR-142-5p inhibitor后SKOV3细胞增殖能力下调，凋亡增加。信号通路抑制剂处理显示miR-142-5p过表达激活PI3K/Akt信号通路。Luciferase实验显示miR-142-5p与PTEN 3' UTR直接结合。与对照组相比，miR-142-5p mimics组PTEN表达显著降低，p-Akt蛋白表达则显著上调（P<0.05），同时过表达PTEN后p-Akt表达则显著降低（P<0.05）。结论:miR-142-5p通过抑制PTEN基因表达活化PI3K/Akt信号通路，促进人上皮性卵巢癌组织及SKOV3细胞增殖存活，抑制细胞凋亡。     

Suppression of PTEN function increases breast cancer chemotherapeutic drug resistance while conferring sensitivity to mTOR inhibitors

Ectopic expression of mutant forms of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) lacking lipid (G129E) or lipid and protein (C124S) phosphatase activity decreased sensitivity of MCF-7 breast cancer cells, which have wild-type PTEN, to doxorubicin and increased sensitivity to the mammalian target of rapamycin (mTOR) inhibitor rapamycin. Cells transfected with a mutant PTEN gene lacking both lipid and protein phosphatase activities were more resistant to doxorubicin than cells transfected with the PTEN mutant lacking lipid phosphatase activity indicating that the protein phosphatase activity of PTEN was also important in controlling the sensitivity to doxorubicin, while no difference was observed between the lipid (G129E) and lipid and protein (C124S) phosphatase PTEN mutants in terms of sensitivity to rapamycin. A synergistic inhibitory interaction was observed when doxorubicin was combined with rapamycin in the phosphatase-deficient PTEN-transfected cells. Interference with the lipid phosphatase activity of PTEN was sufficient to activate Akt/mTOR/p70S6K signaling. These studies indicate that disruption of the normal activity of the PTEN phosphatase can have dramatic effects on the therapeutic sensitivity of breast cancer cells. Mutations in the key residues which control PTEN lipid and protein phosphatase may act as dominant-negative mutants to suppress endogenous PTEN and alter the sensitivity of breast cancer patients to chemo- and targeted therapies.