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。     

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。     

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。     

电离辐射克服NSCLC细胞株H1975吉非替尼耐药的体外研究

目的 探讨电离辐射联合吉非替尼对NSCLC耐药株H1975耐药突变、细胞凋亡及相关蛋白表达的影响及其可能机制。方法 实时荧光定量PCR对不同处理组H1975细胞的T790M突变进行相对定量分析;流式细胞仪检测不同处理组H1975细胞的凋亡率;免疫印迹检测不同处理组凋亡相关蛋白的表达水平。结果 2.5 Gy电离辐射组相较于0 Gy对照组,H1975细胞株T790M突变量降为原来的0.67倍,随电离辐射剂量的增高,T790M突变量降低（P＜0.05）;电离辐射联合吉非替尼组的细胞凋亡率为（44.35±8.49）%,相较于单独电离辐射组（21.84±5.62）%或吉非替尼组（17.38±6.78）%明显升高（P＜0.05）;电离辐射联合吉非替尼可诱导H1975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）蛋白表达水平明显下调。结论 在吉非替尼耐药的NSCLC细胞株H1975中,电离辐射可以克服吉非替尼耐药,与吉非替尼有良好的协同作用。     

抗EGFR单抗联合EGFR酪氨酸激酶抑制剂对人肺腺癌细胞凋亡的影响及其机制

目的:目前抗表皮生长因子受体(epidermal growth factor receptor, EGFR)的小分子酪氨酸激酶抑制剂吉非替尼(gefitinib)和抗EGFR单克隆抗体西妥昔单抗(cetuximab)在肺癌的临床应用中颇为广泛.鉴于这两种药物均针对EGFR分子靶点,因此本研究旨在就上述两种药物联合用药对人肺腺癌细胞凋亡的影响及其分子机制进行探讨.方法:吉非替尼和西妥昔单抗单独或联合用药作用于人肺腺癌细胞株A549和SPC-A-1后,用碘化丙啶标记,采用流式细胞术观察细胞凋亡情况,活细胞计数试剂盒测定各组细胞增殖抑制情况,Western印迹法检测两种药物对EGFR下游信号通路蛋白[磷酸化蛋白激酶B(phosphorylated Akt, p-Akt)、磷酸化EGFR(phosphorylated EGFR,p-EGFR)和磷酸化丝裂原激活蛋白激酶(phosphorylated mitogen-activated protein kinase, p-MAPK)]在蛋白水平表达的影响.结果:吉非替尼或西妥昔单抗单独作用后,A549和SPC-A-1细胞均明显凋亡,同时细胞增殖受到不同程度的抑制.Western印迹法检测p-Akt、p-EGFR和p-MAPK蛋白表达量均较不用药对照组下降.吉非替尼和西妥昔单抗联合作用后,肺腺癌细胞的凋亡、增殖以及在EGFR分子层次表现出较单一用药更为显著的作用.结论:吉非替尼和西妥昔单抗两种药物之间具有良好的协同作用,联合用药可能在临床治疗非小细胞肺癌中具有较大的应用潜力.     

c-Met信号通道参与HGF诱导不同基因型非小细胞肺癌细胞株对吉非替尼耐药

背景与目的肝细胞生长因子(hepatocyte growth factor,HGF)诱导非小细胞肺癌(non-small cell lung cancer,NSCLC)对吉非替尼耐药,可能与其受体c-Met激活有关。本研究旨在探讨c-Met及其下游信号通道是否参与HGF诱导不同基因型NSCLC细胞株对吉非替尼耐药。方法选择人NSCLC细胞株表皮生长因子受体(epidermal growth factor receptor,EGFR)突变型PC-9、PC9/R和EGFR野生型H292、A549,用HGF诱导细胞,通过MTT法检测细胞增殖,Annexin V-FITC法检测细胞凋亡,应用免疫印迹技术检测细胞中c-Met及下游通道的变化。结果吉非替尼对PC9、H292、A549的生长抑制作用呈浓度依赖性,HGF诱导后吉非替尼抑制细胞的生长曲线明显往右移。在PC9、H292、A549细胞中,吉非替尼和HGF处理组的细胞凋亡率比吉非替尼处理组均减少(P<0.05),在PC9/R细胞中无明显减少(P>0.05)。HGF能激活PC9、H292、PC9/R、A549细胞中c-Met及其下游通道蛋白。在PC9、H292、A549细胞中,吉非替尼和HGF处理组的p-Met、p-Akt、p-Stat3、p-Erk1/2蛋白表达比吉非替尼处理组均增高,在PC9/R细胞中无明显增高。结论在体外HGF诱导不同基因型NSCLC细胞株对吉非替尼耐药,c-Met及其下游信号通道参与HGF诱导不同基因型NSCLC细胞株对吉非替尼耐药。     

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。     

AHR活化介导的ROS诱导NSCLC细胞吉非替尼耐药的作用机制

目的:探讨芳香烃受体（AHR）介导的活性氧簇（ROS）诱导非小细胞肺癌（NSCLC）吉非替尼耐药的作用机制。方法:以正常支气管肺泡上皮细胞BEAS-2B为对照,Western blot检测非小细胞肺癌A549、PC-9、H1299和H1975细胞AHR的蛋白表达。AHR激动剂FICZ、吉非替尼、N-乙酰半胱氨酸（NAC）分别处理A549和PC-9细胞,MTT、激光共聚焦显微镜、流式细胞术及Western blot分别检测吉非替尼敏感性、细胞内ROS及表皮生长因子受体（EGFR）信号。结果:MTT检测显示FICZ通过上调半数最大抑制浓度（IC50）诱导PC-9及A549细胞对吉非替尼耐药,Western blot显示FICZ可导致PC-9及A549细胞EGFR、AKT磷酸化,而NAC可遏制A549细胞中的EGFR磷酸化并逆转吉非替尼耐药。共聚焦显微镜和流式细胞仪显示,FICZ诱导的AHR活化导致PC-9及A549细胞内ROS产生增加,并且可被NAC抑制。结论:活化的AHR可通过促进NSCLC细胞中的ROS产生和EGFR信号转导介导吉非替尼耐药,此过程可被NAC抑制。     

SU11274逆转肝细胞生长因子诱导不同EGFR基因型非小细胞肺癌细胞株对吉非替尼耐药

背景与目的:肝细胞生长因子(hepatocyte growth factor,HGF)诱导敏感非小细胞肺癌(nonsmall cell lung cancer,NSCLC)细胞对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)耐药,其机制与c-Met激活有关。本研究探讨c-Met抑制剂SU11274逆转HGF诱导的不同EGFR基因型NSCLC细胞株对吉非替尼耐药及逆转耐药机制。方法:选择人NSCLC细胞株PC9(EGFR突变型)、H292(EGFR野生型)和A549(EGFR野生型),应用吉非替尼和SU11274单独或联合作用于HGF诱导的细胞株。实验分为6组:C组(不加药对照组)、H组(HGF处理组)、G组(吉非替尼处理组)、S组(SU11274处理组)、HG组(HGF+吉非替尼处理组)和HGS组(HGF+吉非替尼+SU11274处理组)。MTT法检测对细胞增殖的影响,流式细胞术检测细胞凋亡的影响;应用蛋白质印迹法(Western blot)检测细胞中c-Met及其下游通道Stat3、Akt和Erk1/2蛋白表达水平。结果:吉非替尼对3种细胞的生长抑制作用均呈浓度依赖性,HGF处理能够缓解吉非替尼的增殖抑制作用(P<0.05);不同浓度吉非替尼联合SU11274作用于HGF诱导细胞时,3种细胞株存活率比吉非替尼单独作用于HGF诱导细胞时明显降低(P<0.05);HGS组的细胞凋亡比HG组明显增加(P<0.05);HGS组的c-Met、Stat3、Akt和Erk1/2活化蛋白量比HG组明显减少。结论:c-Met抑制剂SU11274可逆转HGF诱导的不同EGFR基因型NSCLC细胞株对吉非替尼耐药,其机制可能与抑制HGF活化的c-Met及其下游通道蛋白表达有关。     

SU11274逆转肝细胞生长因子诱导不同EGFR基因型非小细胞肺癌细胞株对吉非替尼耐药

背景与目的：肝细胞生长因子(hepatocyte growth factor,HGF)诱导敏感非小细胞肺癌(nonsmall cell lung cancer,NSCLC)细胞对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)耐药,其机制与c-Met激活有关。本研究探讨c-Met抑制剂SU11274逆转HGF诱导的不同EGFR基因型NSCLC细胞株对吉非替尼耐药及逆转耐药机制。方法：选择人NSCLC细胞株PC9(EGFR突变型)、H292(EGFR野生型)和A549(EGFR野生型),应用吉非替尼和SU11274单独或联合作用于HGF诱导的细胞株。实验分为6组：C组(不加药对照组)、H组(HGF处理组)、G组(吉非替尼处理组)、S(SU11274处理组)、HG组(HGF+吉非替尼处理组)和HGS组(HGF+吉非替尼+SU11274处理组)。MTT法检测对细胞增殖的影响,流式细胞术检测细胞凋亡的影响;应用蛋白质印迹法(Western blot)检测细胞中c-Met及其下游通道Stat3、Akt和Erk1/2蛋白表达水平。结果：吉非替尼对3种细胞的生长抑制作用均呈浓度依赖性,HGF处理能够缓解吉非替尼的增殖抑制作用(P<0.05);不同浓度吉非替尼联合SU11274作用于HGF诱导细胞时,3种细胞株存活率比吉非替尼单独作用于HGF诱导细胞时明显降低(P<0.05);HGS组的细胞凋亡比HG组明显增加(P<0.05);HGS组的c-Met、Stat3、Akt和Erk1/2活化蛋白量比HG组明显减少。结论：c-Met抑制剂SU11274可逆转HGF诱导的不同EGFR基因型NSCLC细胞株对吉非替尼耐药,其机制可能与抑制HGF活化的c-Met及其下游通道蛋白表达有关。     

TIP30逆转人非小细胞肺癌吉非替尼耐药的实验研究

  目的  本实验旨在研究TIP30能否逆转非小细胞肺癌（non-small cell lung cancer,NSCLC）的吉非替尼耐药,并探讨其可能的机制。  方法  慢病毒LV-TIP30转染NSCLC吉非替尼耐药株PC9/GR上调TIP30,以PC9/GR、PC9/GR-LVTIP30和PC9/GR-LVNC为研究对象,分别加或不加5 μmol/L吉非替尼处理共6组细胞。CCK8检测细胞增殖抑制率,划痕修复实验、Transwell实验检测细胞迁移侵袭能力,免疫印迹实验检测p-AKT、p-ERK、p-MEK以及核内EGFR蛋白表达水平。  结果  非吉非替尼处理组中,PC9/GR-LVTIP30细胞的增殖、迁移和侵袭能力与PC9/GR细胞相比均受到明显的抑制（P < 0.05）,吉非替尼处理组中PC9/GR-LVTIP30细胞较PC9/GR细胞抑制作用更明显（P < 0.05）;过表达TIP30后,蛋白p-MEK、p-ERK、p-AKT表达水平降低,核内EGFR表达水平较PC9/GR降低,差异均具有统计学意义（P < 0.05）。  结论  上调TIP30能够逆转人非小细胞肺癌PC9/GR细胞对吉非替尼的耐药性,其发挥作用的机制可能是通过抑制EGFR核内化,进而抑制下游信号通路相关蛋白p-AKT、p-ERK、p-MEK激活发挥作用。      

多西他赛与吉非替尼不同时序应用对人肺腺癌细胞的作用

目的 探讨多西他赛与吉非替尼不同时序应用对人肺腺癌细胞A549和PC-9的生长影响及其细胞学机制。方法 qPCR-HRM法检测人肺腺癌细胞EGFR和K Ras基因突变,MTT法检测细胞增殖, Western blotting检测细胞信号蛋白及磷酸化表达,FCM法检测细胞周期变化。结果 人肺腺癌A549细胞为EGFR基因野生型,PC-9细胞为EGFR第19外显子突变型。多西他赛和吉非替尼单药或联合用药均能抑制A549和PC-9细胞生长,呈浓度依赖性。多西他赛对A549和PC-9细胞生长的半数抑制浓度（IC₅₀）分别为5.24×10^-7和2.13×10^-8mol／L,吉非替尼分别为1.28×10^-5和4.58×10^-8mol／L。在IC₅₀浓度时,多西他赛序贯吉非替尼对A549和PC-9细胞的生长抑制率分别为60.00%和57.45%,均较单药组明显增高（P＜0.05）;而同时用药只对PC-9细胞有增效作用,抑制率为53.46％,较单药组明显增高（P＜0.05）。多西他赛表现为增强A549、PC-9细胞EGFR和ERK磷酸化,吉非替尼表现为抑制,两药均抑制PC-9细胞IGF-1R磷酸化。多西他赛序贯应用吉非替尼显著抑制EGFR和ERK磷酸化,两药同时应用对抑制PC-9细胞的IGF-1R磷酸化具有增强作用。多西他赛将A549及PC-9细胞阻滞在G₂期,吉非替尼将PC-9细胞明显阻滞在G₁期。结论 多西他赛序贯吉非替尼能够抑制EGFR野生型和突变型的A549及PC-9细胞生长,且呈增效作用,可能与影响细胞EGFR和ERK磷酸化有关;两药同时应用仅对PC-9细胞具有增效作用,可能与IGF-1R磷酸化抑制有关;不同时序应用的效果均可能与细胞周期相关。     

吉非替尼获得性耐药细胞株对不同化疗药物的敏感性分析

目的 探讨吉非替尼获得性耐药细胞株对不同化疗药物的敏感性,为分子靶向治疗失败的患者选择化疗方案提供临床前的依据.方法 体外培养人肺腺癌细胞株PC9和吉非替尼获得性耐药株PC9/G,采用二苯基溴化四氮唑蓝(MTT)法测定PC9和PCg/G细胞对不同药物的敏感性以及细胞的增殖抑制率;采用流式细胞仪检测药物对PC9和PCg/G细胞凋亡的影响及P-170蛋白的表达;采用基因芯片技术分析PC9和PC9/G细胞的表达基因谱差异;采用Western blot法检测PC9和PC9/G细胞中总Akt、磷酸化Akt和整合素β1的表达.结果 MTT和凋亡检测的结果 表明,与PC9细胞相比,吉非替尼获得性耐药细胞株PC9/G对顺铂的耐药指数为5.4,细胞凋亡减少,联合LY294002后对顺铂的敏感性显著增加(P＜0.05).PC9/G细胞对多西紫杉醇较PC9细胞更为敏感,培美曲塞对两株细胞的IC50及凋亡影响的差异无统计学意义(P＞0.05).PC9/G细胞中P-170蛋白的表达水平为5.32,与PC9细胞(7.18)比较,差异无统计学意义(P＞0.05).基因芯片分析显示,PC9/G细胞中,整合素β1及DNA修复基因的表达上调,有丝分裂期基因表达下调.PC9/G细胞中总Akt、磷酸化Akt及整合素β1的蛋白表达水平分别为1.32、1.82和1.59,PC9细胞巾总Akt、磷酸化Akt及整合素β1的蛋白表达水平分别为0.83、0.87和0.57.结论 在吉非替尼获得件耐药细胞株中存在P13K的表达上调及激活、整合素β1及DNA修复基因的表达上调,其表达土调与顺铂耐药相关;表皮生长因子受体-酪氨酸激酶抑制剂(EGFR-TKI)治疗失败的患者在选择化疗方案时应避免使用铂类药物,可选择给予多西紫杉醇或培美曲塞治疗.     

安罗替尼联合吉非替尼对吉非替尼耐药非小细胞肺癌PC9/GR细胞增殖的影响及其可能的作用机制

目的 探讨安罗替尼联合吉非替尼对吉非替尼耐药的人非小细胞肺癌PC9/GR（gefitinib resistance）细胞增殖的影响及其可能的作用机制。 方法 依据不同给药情况将PC9/GR细胞分为安罗替尼单药组、吉非替尼单药组、安罗替尼和吉非替尼联合用药组及阴性对照组,用MTT法检测各组细胞的增殖情况,流式细胞仪检测细胞的周期分布,Western blot检测p-ERK1/2和p-AKT蛋白的表达水平。 结果 安罗替尼和吉非替尼作用于PC9/GR细胞72 h的半数抑制浓度（half inhibitory concentration,IC₅₀）分别为（1.91±0.18） μmol/L和（4.83±0.15） μmol/L,两药均呈剂量依赖性的抗增殖作用,且两药联合时表现出明显的协同效应,联合指数（combination index,CI）小于1。安罗替尼和吉非替尼单药均可将PC9/GR细胞阻滞于G0/G1期（均P<0.05）。与各单药组比较,联合用药组表现出更明显的G0/G1期阻滞（均P<0.05）,且下调p-ERK1/2和p-AKT蛋白的表达水平（均P<0.05）。 结论 安罗替尼联合吉非替尼对非小细胞肺癌 PC9/GR细胞具有协同抗增殖作用,且可增强吉非替尼敏感性,其协同抗肿瘤机制可能与诱导细胞周期阻滞和下调p-ERK1/2和p-AKT蛋白的表达相关。     

非小细胞肺癌吉非替尼耐药相关miRNAs的筛选鉴定

  目的  miRNA是一类通过结合mRNA调节基因表达的非编码单链小分子RNA,本研究目的是探讨非小细胞肺癌（NSCLC）中miRNA与吉非替尼耐药的关系。  方法  CCK8法检测NSCLC吉非替尼耐药细胞PC9/GR相对于亲本细胞PC9的耐药倍数;miRNA芯片检测PC9/GR与PC9中miRNA的表达差异;RT-PCR验证miRNA芯片结果。将差异表达的miRNA模拟物/抑制剂转染至PC9/GR中,观察其对吉非替尼敏感性的影响。  结果  吉非替尼对PC9和PC9/GR的IC₅₀值分别为42.89 nmoL/L和3.87 μ moL/L,耐药倍数为90.23倍。miRNA芯片结果显示,PC9/GR与PC9比较55条有差异表达miRNAs（P < 0.01）,其中在PC9/GR上调的miRNAs有21条,包括miRNA-1 246、miRNA-125b等;下调的miRNAs有34条,包括miRNA-224、miRNA-125a~5p等。RT-PCR进一步验证其中9条miRNAs,有8条与芯片结果趋势一致。将上述8条miRNAs的模拟物/抑制剂转染至PC9/GR中,发现miRNA-125a~5p模拟物可降低吉非替尼敏感性。  结论  PC9/GR与PC9的miRNA表达存在差异,miRNA可能与NSCLC吉非替尼耐药相关,miRNA-125a~5p可促进PC9/GR对吉非替尼产生耐药。      

Hypoxia induces gefitinib resistance in non‐small‐cell lung cancer with both mutant and wild‐type epidermal growth factor receptors

Somatic mutations in the epidermal growth factor receptor (EGFR) gene, such as exon 19 deletion mutations, are important factors in determining therapeutic responses to gefitinib in non‐small‐cell lung cancer (NSCLC). However, some patients have activating mutations in EGFR and show poor responses to gefitinib. In this study, we examined three NSCLC cell lines, HCC827, PC9, and HCC2935, that expressed an EGFR exon 19 deletion mutation. All cells expressed mutant EGFR, but the PC9 and HCC2935 cells also expressed wild‐type EGFR. The HCC827 cells were highly sensitive to gefitinib under both normoxia and hypoxia. However, the PC9 and HCC2935 cells were more resistant to gefitinib under hypoxic conditions compared to normoxia. Phosphorylation of EGFR and ERK was suppressed with gefitinib treatment to a lesser extent under hypoxia. The expression of transforming growth factor‐α (TGFα) was dramatically upregulated under hypoxia, and the knockdown of TGFα or hypoxia‐inducible factor‐1α (HIF1α) reversed the resistance to gefitinib in hypoxic PC9 and HCC2935 cells. Finally, introduction of the wild‐type EGFR gene into the HCC827 cells caused resistance to gefitinib under hypoxia. This phenomenon was also reversed by the knockdown of TGFα or HIF1α. Our results indicate that hypoxia causes gefitinib resistance in EGFR‐mutant NSCLC through the activation of wild‐type EGFR mediated by the upregulation of TGFα. The presence of wild‐type and mutant EGFR along with tumor hypoxia are important factors that should be considered when treating NSCLC patients with gefitinib.     

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)     

Identification of genes linked to gefitinib treatment in prostate cancer cell lines with or without resistance to androgen: a clue to application of gefitinib to hormone-resistant prostate cancer

Understanding the molecular action of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, might allow us to perform more effective therapies for hormone-independent advanced prostate cancer. A DNA microarray study was undertaken to comprehensively analyze the alteration of levels of 1,081 genes after gefitinib treatment in androgen-independent PC3 and DU145 cells and androgen-dependent LNCaP cells. The proliferation of PC3, DU145 and LNCaP cells was significantly inhibited by 50.2%, 83.8% and 55.2%, respectively, 6 days after 10 microM gefitinib administration. Of the above 1,081 genes, we identified 23, 13 and 33 genes with significantly different expression in PC3, DU145 and LNCaP cells, respectively, 24 h after 10 microM-gefitinib exposure. Among the identified genes, only Quiescin Q6, a negative cell cycle regulator, was increased after gefitinib treatment in all three cell lines regardless of gefitinib sensitivity. Except for Quiescin Q6, there were no overlapping genes between PC3 and DU145 cells. However, levels of several oncogenes or proliferation-related genes were changed after gefitinib treatment in the 2 androgen-independent cell lines. We also identified 7 unique genes [glycyl-tRNA synthetase, interferon, alpha-inducible protein, stratifin, nuclear factor of kappa light polypeptide gene enhancer in B-cells 1, dual specificity phosphatase 9, guanine nucleotide binding protein (G protein) beta polypeptide 2, neural retina leucine zipper] whose levels were altered exclusively after gefitinib administration in gefitinib-resistant PC3 and LNCaP cells, but not in DU145 cells, suggesting that these 7 genes could be targets for overcoming gefitinib resistance. Collectively, our molecular profiling data will serve as a framework for understanding the molecular action of gefitinib for prostate cancer.     

Establishment of a human non-small cell lung cancer cell line resistant to gefitinib

The epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitor gefitinib (Iressa, ZD1839) has shown promising activity preclinically and clinically. Because comparative investigations of drug-resistant sublines with their parental cells are useful approaches to identifying the mechanism of gefitinib resistance and select factors that determine sensitivity to gefitinib, we established a human non-small cell lung carcinoma subline (PC-9/ZD) that is resistant to gefitinib. PC-9/ZD cells are approximately 180-fold more resistant to gefitinib than their parental PC-9 cells and PC-9/ZD cells do not exhibit cross-resistance to conventional anticancer agents or other tyrosine kinase inhibitors, except AG-1478, a specific inhibitor of EGFR. PC-9/ZD cells also display significant resistance to gefitinib in a tumor-bearing animal model. To elucidate the mechanism of resistance, we characterized PC-9/ZD cells. The basal level of EGFR in PC-9 and PC-9/ZD cells was comparable. A deletion mutation was identified within the kinase domain of EGFR in both PC-9 and PC-9/ZD, but no difference in the sequence of EGFR cDNA was detected in either cell line. Increased EGFR/HER2 (and EGFR/HER3) heterodimer formations were demonstrated in PC-9/ZD cells by chemical cross-linking and immunoprecipitation analysis in cells unexposed to gefitinib. Exposure to gefitinib increased heterodimer formation in PC-9 cells, but not in PC-9/ZD cells. Gefitinib inhibits EGFR autophosphorylation in a dose-dependent manner in PC-9 cells but not in PC-9/ZD cells. A marked difference in inhibition of site-specific phosphorylation of EGFR was observed at Tyr1068 compared to other tyrosine residues (Tyr845, 992 and 1045). To elucidate the downstream signaling in the PC9/ZD cellular machinery, complex formation between EGFR and its adaptor proteins GRB2, SOS, and Shc was examined. A marked reduction in the GRB2-EGFR complex and absence of SOS-EGFR were observed in PC-9/ZD cells, even though the protein levels of GRB2 and SOS in PC-9 and PC-9/ZD cells were comparable. Expression of phosphorylated AKT was increased in PC-9 cells and inhibited by 0.02 microM gefitinib. But the inhibition was not significant in PC-9/ZD cells. These results suggest that alterations of adaptor-protein-mediated signal transduction from EGFR to AKT is a possible mechanism of the resistance to gefitinib in PC-9/ZD cells. These phenotypes including EGFR-SOS complex and heterodimer formation of HER family members are potential biomarkers for predicting resistance to gefitinib.