miR-21促进肺癌EGFR-TKI耐药细胞株上皮—间质细胞转化的研究

[目的]研究miR-21是否可以调控上皮—间质转化（EMT）而参与肺癌获得性耐药。[方法]使用HCC827细胞（EGFR基因19外显子缺少的肺腺癌细胞株）,在此细胞的基础上培养吉非替尼耐药细胞株HCC827/GR。检测耐药细胞株中miR-21的表达,同时观察耐药细胞的形态变化,及在耐药细胞株中抑制miR-21表达后检测耐药细胞株的侵袭能力及EMT相关蛋白E-cadherin和Vimentin的表达。[结果]与敏感细胞株HCC827相比,HCC827/GR细胞株对吉非替尼的耐药倍数约为100倍;同时在耐药细胞株中我们发现miR-21较敏感株表达增高约5.3倍,同时细胞形态发生了明显变化。通过检测EMT相关蛋白,我们发现耐药细胞株中间质相关蛋白Vimentin明显高表达,而上皮相关蛋白E-cadherin明显低表达,当miR-21被抑制后,耐药细胞株侵袭能力下降,同时Vimentin表达量下降,而E-cadherin表达量增高。[结论]miR-21可能通过促进EMT参与肺癌EGFR-TKI的获得性耐药。     

吉非替尼敏感性不同的非小细胞肺癌中miRNA-7表达的差异及临床意义

目的检测吉非替尼敏感性不同的非小细胞肺癌中miR-7的表达差异,并探讨其临床意义。方法采用吉非替尼(Gefitinib)药物大剂量冲击法诱导H827,建立耐吉非替尼肺癌细胞亚系H827-7/GR,有限稀释法将H827-7/GR细胞单克隆化,CCK-8法检测耐药前后细胞株及各单克隆细胞对吉非替尼的敏感性;RT-PCR方法检测H827、H827-7/GR和耐药单克隆细胞株以及其他对吉非替尼敏感性不同的肺癌细胞株A549、H358、H1299、H1650和H1975中miR-7的表达差异。结果 H827/GR耐药指数大于100;获得的6株耐药单克隆细胞株对吉非替尼的半生长抑制浓度(the half growth inhibition concentration,IC50)值不同;和吉非替尼敏感株H827相比,诱导的耐药细胞株H827/GR、耐药单克隆细胞株和吉非替尼耐药株A549、H358、H1299、H1650和H1975中miR-7的相对表达水平均降低(P<0.05)。结论在非小细胞肺癌中,耐药细胞中miR-7的相对表达水平均较敏感细胞系降低,提示miR-7的低表达可能与非小细胞肺癌耐药性相关,其可能是潜在的肺癌药物敏感性预测分子标志物。     

大黄素逆转非小细胞肺癌EGFR-TKI耐药的机制研究

目的 探讨大黄素逆转非小细胞肺癌（NSCLC）表皮生长因子受体酪氨酸激酶抑制剂（EGFR TKI）耐药的作用机制。方法 应用持续诱导的方法构建NSCLC EGFR-TKI耐药细胞株HCC827／GR;应用MTS法检测大黄素（30μmol／L）、吉非替尼（1μmol／L）及两药联合处理HCC827和HCC827／GR细胞48h后细胞增殖能力的变化;应用Western blotting法检测HCC827和 HCC827／GR细胞中p EGFR、p-AKT、p-ERK1／2及p-MET蛋白表达水平的变化。结果 MTS法检测结果显示,经单药吉非替尼或大黄素处理后,HCC827／GR细胞增殖能力未减弱,而两药联合处理组的细胞增殖能力明显下降,差异有统计学意义（P＜0.05）。Western blotting检测结果显示,HCC827、HCC827／GR细胞中p-EGFR、p-ERK1/2明显表达,而p-AKT表达微弱;HCC827／GR 中p-MET表达水平较HCC827明显上调。经单药吉非替尼处理后,HCC827细胞株p-EGFR、p-ERK1/2表达水平下调,HCC827／GR细胞株p-EGFR表达明显下调;大黄素可显著下调HCC827／GR细胞株p-MET表达,但对p-EGFR、p-ERK1/2的表达无影响;而大黄素与吉非替尼两药联用可明显抑制HCC827／GR细胞株p-EGFR、p-ERK1/2以及p-MET的表达。结论 大黄素可以逆转NSCLC EGFR-TKI耐药,可能是通过抑制c-Met的活化来实现。     

人非小细胞肺癌细胞EGFR基因启动子甲基化与吉非替尼敏感性之间的相关性研究

目的 探讨EGFR基因启动子甲基化水平与人非小细胞肺癌（NSCLC）细胞株对吉非替尼敏感性之间的相关性。方法 用不同浓度吉非替尼分别作用于NSCLC细胞株HCC827、H1650、H1975、H358、H1299、A549后,CCK-8法检测细胞增殖抑制率,DNA直接测序法、实时荧光定量PCR法、免疫印迹法和甲基化特异性PCR法分别检测上述NSCLC细胞株EGFR基因突变、EGFR mRNA、EGFR蛋白表达和启动子区甲基化状态。结果 CCK-8法检测结果显示,19外显子缺失突变的HCC827细胞对吉非替尼最敏感,而同为19外显子缺失突变的H1650细胞对吉非替尼不敏感;野生型的H358细胞对吉非替尼中度敏感,其敏感性甚至超过19外显子突变的H1650细胞,而同为EGFR野生型的H1299、A549细胞对吉非替尼敏感性较差。吉非替尼处理72h后,HCC827细胞与H358细胞相比、HCC827细胞和H358细胞与其他4株细胞相比,IC50值均有显著性差异（P＜0.05）。HCC827细胞EGFR启动子为未甲基化状态,其EGFR蛋白和mRNA表达最高;H358细胞为部分甲基化,其EGFR蛋白和mRNA为中等表达;其他4个细胞株均为高甲基化状态,EGFR蛋白和mRNA呈低表达;HCC827细胞的EGFR表达水平较H358细胞高,HCC827和H358细胞的EGFR表达较其他4个细胞株高,差异均有统计学意义（P＜0.05）。结论 EGFR基因启动子区高甲基化可能下调EGFR基因的表达水平,从而降低NSCLC对吉非替尼的敏感性;对该基因的甲基化检测可能对预测吉非替尼治疗NSCLC疗效有一定的临床指导意义。     

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。     

洛伐他汀克服非小细胞肺癌PC9细胞株吉非替尼耐药的体外研究

目的:研究联合洛伐他汀(lovastatin)和吉非替尼(gefi tinib)对体外诱导吉非替尼获得性耐药的非小细胞肺癌细胞株PC9细胞凋亡以及相关蛋白表达的影响,并探讨其可能的机制。方法:应用洛伐他汀联合吉非替尼处理耐吉非替尼的非小细胞肺癌PC9细胞株后,采用WST-1法检测不同药物处理对PC9细胞增殖的影响,Hoechst33342荧光染色法观察细胞凋亡形态,FCM法观察细胞凋亡状况,蛋白质印迹法检测凋亡相关蛋白的表达水平。结果:洛伐他汀联合吉非替尼可在体外诱导耐吉非替尼的PC9细胞凋亡,抑制其细胞增殖;洛伐他汀联合吉非替尼可诱导耐吉非替尼的PC9细胞中磷酸化表皮生长因子受体(phosphorylated epidermal growth factor receptor,p-EGFR)、磷酸化蛋白激酶B(phosphorylated protein kinase B,p-AKT)和磷酸化细胞外调节蛋白激酶1/2(phosphorylated extracellular signal-regulated kinase1/2,p-ERK1/2)蛋白表达水平明显下调。结论:在体外诱导吉非替尼获得性耐药的非小细胞肺癌细胞株PC9中,洛伐他汀可以克服吉非替尼耐药,两者具有良好的协同作用,提示两药联合对于出现吉非替尼耐药的非小细胞肺癌的临床治疗可能具有很大的应用潜力。     

上调miR-34b表达可增强HCC827细胞对埃克替尼的敏感性

目的:探讨上调miR-34b的表达对HCC827细胞对埃克替尼敏感性的影响及其机制。方法:应用细胞转染技术获得miR-34b高表达的HCC827细胞，并将HCC827细胞分为空白对照组、转染组、埃克替尼组及埃克替尼与转染联合组，采用MTT法测定各组细胞增殖的情况，运用流式细胞术分析各组细胞凋亡率及生长周期的变化，同时应用Real-time PCR及Western Blot方法检测各组c-MET基因mRNA及蛋白的表达水平。 结果:miR-34b转染后，HCC827细胞的增殖能力下降，凋亡率升高（P<0.05）；miR-34b转染后，埃克替尼对HCC827细胞的抑制率较埃克替尼组明显上升，半数抑制浓度（IC50）明显下降（P<0.05）；转染组及埃克替尼与转染联合组的c-MET水平较对照组有所下降（P<0.05）。结论:上调miR-34b表达可以抑制HCC827细胞增殖，促进其凋亡，并可以增强HCC827细胞对盐酸埃克替尼的敏感性；其机制可能与miR-34b反馈抑制c-MET有关。     

肺腺癌吉非替尼获得性耐药相关microRNAs的筛选鉴定

背景与目的肺腺癌吉非替尼获得性耐药严重影响了肺癌的治疗效果,microRNA在肺腺癌吉非替尼获得性耐药中的作用及其机制尚不清楚。本研究筛选与肺腺癌获得性吉非替尼耐药相关的microRNAs。方法以吉非替尼敏感肺癌细胞PC9与吉非替尼耐药肺癌细胞PC9/AB11为细胞模型,观察二者的形态学差异,流式细胞仪检测二者的细胞周期,计算它们的倍增时间,MTT法检测吉非替尼对两种细胞的IC50,应用microRNA芯片检测和筛选与吉非替尼耐药相关的microRNAs,并进行real-timePCR验证。结果 PC9细胞与PC9/AB11细胞形态差异明显,在细胞周期、倍增时间和吉非替尼对其的IC50上均具有统计学差异。microRNA芯片结果显示,与PC9相比,耐药肺癌细胞株PC9/AB11中有4个microRNAs表达水平明显上调,有9个microRNAs表达水平明显下调。经real-timePCR验证,microRNA-138在PC9/AB11中表达明显下调,与芯片结果一致。结论 PC9和PC9/AB11细胞株microRNA表达谱存在明显差异,初步筛选到了13个与肺腺癌吉非替尼耐药密切相关的microRNAs,为进一步深入研究microRNA在肺腺癌吉非替尼获得性耐药中的作用及其分子机制提供了实验依据和理论基础。     

吉非替尼联合培美曲塞对EGFR-TKI获得性耐药的非小细胞肺癌细胞的协同效应

目的:探讨培美曲塞联合吉非替尼对体外诱导的表皮生长因子受体-酪氨酸激酶抑制剂(epidermal growth factor receptor-tyrosine kinase inhibitor,EGFR-TKI)获得性耐药的人非小细胞肺癌PC9/吉非替尼耐药(gei tinib resistance,GR)细胞株的效应及其可能的机制。方法:吉非替尼和培美曲塞单药或联合作用于PC9/GR细胞后,MTT法检测各药物处理组细胞的增殖抑制率及药物的联合指数(combination index,CI),FCM法检测各组细胞的凋亡率,蛋白质印迹法检测各组细胞磷酸化AKT和Bcl-2蛋白的表达水平。结果:吉非替尼和培美曲塞联合应用对PC9/GR细胞的增殖抑制作用和促凋亡作用明显强于各单药组(P0.05);吉非替尼和培美曲塞的CI值1,表现出明显的协同效应。与未进行药物处理的对照组比较,培美曲塞联合吉非替尼可明显下调PC9/GR细胞中磷酸化AKT和Bcl-2蛋白的表达水平(P0.01)。结论:培美曲塞联合吉非替尼对PC9/GR细胞具有较好的协同作用,这协同作用可能与诱导细胞凋亡和下调磷酸化AKT蛋白表达有关。     

MicroRNA-145增强非小细胞肺癌细胞对吉非替尼敏感性及其机制探讨

目的:探讨微小RNA-145（microRNA-145，miR-145）对非小细胞肺癌细胞系吉非替尼耐药的作用及其可能的潜在机制。方法:实时荧光定量PCR（Q-PCR）方法检测正常细胞及非小细胞肺癌细胞中miR-145的表达差异；不同时间5 μmol/L吉非替尼干预肺癌细胞SPC-A-1和A549后，Q-PCR检测miR-145表达变化；miR-145 mimics和miR-145 inhibitors分别转染SPC-A-1和A549肺癌细胞后，CCK8检测细胞活力变化;双荧光素酶报告系统检测miR-145与ADAM19的靶向结合；miR-145 mimics转染SPC-A-1和A549肺癌细胞，Western blot检测ADAM19蛋白表达；Western blot检测5 μmol/L吉非替尼干预后，SPC-A-1和A549肺癌细胞中ADAM19蛋白的表达；miR-145 mimics转染SPC-A-1和A549肺癌细胞，再用5 μmol/L吉非替尼干预，Western blot检测ADAM19蛋白的表达；采用siRNA抑制ADAM19表达，再用5 μmol/L吉非替尼干预，CCK8检测细胞活力；采用BALB/C雌性裸鼠皮下接种肿瘤细胞的方法，观察上述效应。结果:Q-PCR结果显示，与正常肺上皮细胞系BEAS-2B相比较，肺癌细胞SPC-A-1和A549中miR-145表达明显降低；5 μmol/L吉非替尼干预SPC-A-1和A549细胞后，miR-145表达显著上调；转染miR-145 mimics后,CCK8结果显示两种细胞细胞活力下降；双荧光素酶报告系统结果显示，miR-145靶向结合ADAM19基因的3'-UTR区；Western blot结果显示，5 μmol/L吉非替尼诱导SPC-A-1和 A549细胞后，两种细胞中ADAM19蛋白表达均降低；miR-145 mimics转染SPC-A-1和A549细胞，之后给予5 μmol/L吉非替尼治疗，ADAM19蛋白表达下调；siRNA抑制SPC-A-1和A549细胞中ADAM19表达，再给予5 μmol/L吉非替尼治疗，CCK8结果显示，两种细胞的细胞活力显著降低；过表达BALB/C雌性裸鼠的miR-145后，显著抑制皮下肿瘤生长，并且增强吉非替尼的抗肿瘤效果。结论:miR-145显著增强肺癌细胞SPC-A-1和A549对吉非替尼的敏感性，其机制可能是通过靶向结合AMDM19基因的3'-UTR区域，从而抑制其表达。miR-145有可能成为治疗非小细胞肺癌吉非替尼耐药的有效靶点。     

MicroRNA-214 regulates the acquired resistance to gefitinib via the PTEN/AKT pathway in EGFR-mutant cell lines

Patients with non-small cell lung cancer (NSCLC) who have activating epidermal growth factor receptor (EGFR) mutations derive clinical benefit from treatment with EGFR-tyrosine kinase inhibitors ((EGFR-TKIs)- namely gefitinib and erlotinib. However, these patients eventually develop resistance to EGFR-TKIs. Despite the fact that this acquired resistance may be the result of a secondary mutation in the EGFR gene, such as T790M or amplification of the MET proto-oncogene, there are other mechanisms which need to be explored. MicroRNAs (miRs) are a class of small non-coding RNAs that play pivotal roles in tumorigenesis, tumor progression and chemo-resistance. In this study, we firstly successfully established a gefitinib resistant cell line-HCC827/GR, by exposing normal HCC827 cells (an NSCLC cell line with a 746E-750A in-frame deletion of EGFR gene) to increasing concentrations of gefitinib. Then, we found that miR-214 was significantly up-regulated in HCC827/ GR. We also showed that miR-214 and PTEN were inversely expressed in HCC827/GR. Knockdown of miR-214 altered the expression of PTEN and p-AKT and re-sensitized HCC827/GR to gefitinib. Taken together, miR-214 may regulate the acquired resistance to gefitinib in HCC827 via PTEN/AKT signaling pathway. Suppression of miR-214 may thus reverse the acquired resistance to EGFR-TKIs therapy.     

MicroRNA-34a overcomes HGF-mediated gefitinib resistance in EGFR mutant lung cancer cells partly by targeting MET

In non-small-cell lung cancer (NSCLC) that harbours an activating epidermal growth factor receptor (EGFR) mutation, over-expression of hepatocyte growth factor (HGF) is an important mechanism involved in the acquired resistance to EGFR-tyrosine kinase inhibitors (TKIs) by restoring activity of the PI3K/Akt pathway via phosphorylation of MET. In our study, we found that the forced expression of miR-34a inhibited cell growth and induced apoptosis partly by targeting MET in HGF-induced gefitinib-resistant HCC827 and PC-9 cells. Furthermore, dramatic tumour regression was observed in the miR-34a plus gefitinib group in HGF-induced gefitinib resistant mouse xenograft models. This study demonstrates for the first time that miR-34a rescues HGF-induced gefitinib resistance in EGFR mutant NSCLC cells.     

Effects of Src inhibitors on cell growth and epidermal growth factor receptor and MET signaling in gefitinib-resistant non-small cell lung cancer cells with acquired MET amplification

The efficacy of epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitors such as gefitinib and erlotinib in non-small cell lung cancer (NSCLC) is often limited by the emergence of drug resistance conferred either by a secondary T790M mutation of EGFR or by acquired amplification of the MET gene. We now show that the extent of activation of the tyrosine kinase Src is markedly increased in gefitinib-resistant NSCLC (HCC827 GR) cells with MET amplification compared with that in the gefitinib-sensitive parental (HCC827) cells. In contrast, the extent of Src activation did not differ between gefitinib-resistant NSCLC (PC9/ZD) cells harboring the T790M mutation of EGFR and the corresponding gefitinib-sensitive parental (PC9) cells. This activation of Src in HCC827 GR cells was largely abolished by the MET-TKI PHA-665752 but was only partially inhibited by gefitinib, suggesting that Src activation is more dependent on MET signaling than on EGFR signaling in gefitinib-resistant NSCLC cells with MET amplification. Src inhibitors blocked Akt and Erk signaling pathways, resulting in both suppression of cell growth and induction of apoptosis, in HCC827 GR cells as effectively as did the combination of gefitinib and PHA-665752. Furthermore, Src inhibitor dasatinib inhibited tumor growth in HCC827 GR xenografts to a significantly greater extent than did treatment with gefitinib alone. These results provide a rationale for clinical targeting of Src in gefitinib-resistant NSCLC with MET amplification. ( Cancer Sci 2009)     

Clinical and molecular evidences of epithelial to mesenchymal transition in acquired resistance to EGFR-TKIs

Background

Epithelial-to-mesenchymal transition (EMT), which was related with an acquired resistance to gefitinib, was found in the A549 lung cancer cell line. However, the clinical feasibility of this finding is still questionable. Here, we investigated whether EMT could be detected in a more clinically suitable situation using patient's tumor and cells with deletion mutation on exon 19 of EGFR gene.

Methods

HCC827 cell line was used to establish the subline resistant to EGFR-TKIs. The induction of EMT was analyzed by immunostainings and Western blots in resistant cells and biopsied tissue from a patient with acquired resistance to erlotinib. Migration and invasion assay was performed to characterize the resistant cells. EMT-related genes expression was evaluated by cDNA microarray. Phospho-receptor tyrosine kinase array analysis was carried out to find bypass activating signals such as MET.

Results

We found that EMT developed in a lung cancer patient who had an acquired resistance to erlotinib while there were no known resistant mechanisms such as T790M and MET amplification. CL-387,785-resistant cells (HCC827/CLR) were obtained by long-term exposure to increasing concentrations of CL-387,785 (an irreversible EGFR-TKI). The morphological and molecular maker changes compatible with EMT were also found in HCC827/CLR cells. However, there were also no secondary T790M mutation and MET amplification. Furthermore, the activity of most of tested RTKs including receptor HER family was decreased suggesting that there was no bypass activating signal leading to resistance. These cells showed an enhanced capability for migration (∼1.6-fold) and invasion (∼2.8-fold).

Conclusion

EMT should be considered as one of possible mechanisms for the acquired resistance to EGFR-TKIs in lung cancer cells.     

Acquired resistance to cetuximab is mediated by increased PTEN instability and leads cross-resistance to gefitinib in HCC827 NSCLC cells

EGFR inhibitors, including the small-molecule tyrosine kinase inhibitors such as gefitinib, and the monoclonal antibodies directed at the receptor such as cetuximab, have demonstrated promising effects in non-small cell lung cancer (NSCLC). In this study, we generated cetuximab-resistant cell lines (HCC827-CR) from HCC827 NSCLC cells to investigate acquired resistance mechanisms to cetuximab. In HCC827-CR cells, Akt was hyperactivated and its activity was persistent upon cetuximab treatment. Blockade of PI3K/Akt activity restored cetuximab sensitivity in HCC827-CR cells. Further investigation revealed that increased PTEN instability mediates constitutive Akt activation. By 1 μM proteosomal inhibitor, MG-132, PTEN protein levels were restored and Akt activity was dramatically reduced. Overexpression of PTEN by transfection could not restore cetuximab sensitivity in HCC827-CR because overexpressed PTEN was degraded rapidly (∼72 h). The increased PTEN instability was confirmed by the treatment of HCC827-CR with a protein synthesis inhibitor, cycloheximide. In the presence of cycloheximide, overexpressed PTEN was degraded more rapidly (∼12 h) in HCC827-CR cells. Interestingly, HCC827-CR cells also revealed de novo resistance to gefitinib. Inhibition of PI3K/Akt signaling pathway restored sensitivity to gefitinib in HCC827-CR cells. Taken together, these data show that PTEN instability-mediated constitutive Akt activation is involved in acquired resistance mechanisms to cetuximab and also induces de novo resistance to gefitinib. Importantly, these findings suggest emergence of cross-resistance between two agents as a potential serious problem in the clinical setting.