miR-214通过PTEN调控AKT信号通路抑制鼻咽癌细胞凋亡CSCD

目的探讨miR-214通过PTEN调控下游AKT信号通路激活对鼻咽癌细胞凋亡的影响。方法miR-214抑制剂转染鼻咽癌5-8F和6-10B细胞。MTT法评估细胞增殖情况。Annexin-V/PI染色法检测两种鼻咽癌细胞凋亡情况。Western blot和real-time PCR检测miR-214抑制剂对PTEN基因转录和蛋白表达以及对AKT信号通路和凋亡相关蛋白表达水平的影响。检测shRNA沉默PTEN基因转录和蛋白表达后,miR-214抑制剂对鼻咽癌细胞凋亡影响。结果miR-214抑制剂可抑制鼻咽癌细胞生长,诱导5-8F和6-10B细胞凋亡。miR-214通过靶向3'-UTR区域调控PTEN基因转录和蛋白表达。抑制miR-214可促进PTEN的表达,抑制AKT信号通路激活,进而调控下游细胞周期和凋亡相关蛋白表达。沉默PTEN基因转录和蛋白表达可逆转miR-214抑制剂对鼻咽癌细胞AKT信号通路活性和凋亡的影响。结论miR-214可通过直接靶向PTEN基因转录促进AKT信号通路激活抑制鼻咽癌细胞凋亡。     

Heregulin通过Her2激活SKBR3细胞内IKK／NF－κB信号通路

目的：初探Her2激动剂Heregulin（HRG）对人乳腺癌SKBR3细胞内IKK／NF－κB信号通路的激活机制。方法：Western blotting法检测 HRG对 SKBR3细胞中 PI3K／Akt／IKK信号通路的影响。以 TNF －α／RIP1／IKK这条经典信号通路为对照,引入各通路中关键蛋白（PI3K、RIP1及IKK）的抑制剂,对比各抑制剂对两条通路的影响。实时无标记细胞分析技术监测HRG对SKBR3细胞增殖的促进作用及IKK抑制剂TPCA1对HRG的拮抗作用。结果：HRG与TNF－α均能激活IKK引起 NF－κB入核,RIP1的抑制剂Necrostatin－1能阻断由TNF－α引起的IKK活化,但不能阻断由HRG引起的IKK活化,表明HRG并非通过传统的途径激活IKK。PI3K抑制剂LY294002能阻断由HRG引起的IKK激活,PI3K是Her2信号通路的关键蛋白之一,因此推测HRG是经由PI3K／Akt信号通路,完成对IKK／NF－κB通路的激活。细胞生长曲线反映,HRG能促进SKBR3细胞的增殖,TPCA1对HRG具有拮抗作用,对数期细胞经100nmol／L的TPCA1处理后,细胞增殖受到抑制,数量迅速下降。结论：HRG可以通过Her2／PI3K／Akt途径激活SKBR3细胞内IKK／NF－κB信号通路。     

鼻咽癌细胞PI3K/AKT和ERK/MAPK信号通路活性表达及其临床意义的探讨

目的:探讨鼻咽癌细胞中PK3K/AKT和ERK/MAPK信号传导通路异常激活与鼻咽癌细胞发生发展的关系.方法:蛋白质印迹法检测3例鼻咽低分化鳞癌组织及其细胞株(CNE2)和鼻咽炎性组织中IGF-1R、AKT和ERKl/2蛋白的表达情况;相同实验方法检测鼻咽癌细胞株CNE2中磷酸化的PAKT和pERK1/2蛋白的表达和给予胰岛素样生长因子-1(IGF-1)刺激癌细胞后磷酸化的pAKT和pERK的表达水平,再分别用PKB/AKT和ERK/MAPK通路抑制剂对CNE2细胞信号传导通路磷酸化的调节作用进行抑制试验.结果:3例鼻咽低分化鳞癌组织和cNE2细胞株中IGF-1R、AKT和ERK1/2蛋白表达水平明显高于鼻咽炎性组织;IGF-1可刺激CNE2细胞中PAKT和pERK1/2的表达增加,与空白对照组相比,其pAKT和pERK表达量明显增高;给予wortrnannin和PD98059治疗24和48 h后,CNE2细胞株生长明显受到抑制.结论:IGF-lR的过度表达及其PK3K/AKT、ERK/MAPK信号传导通路的异常激活在鼻咽癌的发生、发展过程中可能起着非常重要的作用,IGF-1R系统有可能作为复发或转移性鼻咽癌治疗中一个潜在的靶分子.中华肿瘤防治杂志.2009,16(1):44-47     

Notch信号阻断剂抑制鼻咽癌细胞增殖的作用及机制

目的探讨Notch信号阻断剂抑制鼻咽癌细胞增殖的作用及其机制。方法应用Notch信号特异性抑制剂GSI抑制Notch信号的表达,MTT法检测癌细胞的生长增殖变化;流式细胞及Hoechst 33258染色检测癌细胞凋亡;应用Western blot检测Notch信号受抑制后AKT、MEK信号通路的变化。结果应用Notch抑制剂GSI作用后,癌细胞Notch1、2、4表达明显下降,而Notch3无明显变化。GSI作用后癌细胞增殖明显受到抑制,凋亡增加;该作用有浓度及时间双重依赖性（P<0.05）。Notch信号阻断后磷酸化AKT、GSK3β和ERK1/2显著下降,而总AKT、总GSK3β及总ERK1/2无明显变化。结论阻断鼻咽癌细胞Notch信号可以显著抑制鼻咽癌细胞增殖及诱导癌细胞凋亡。该作用可能与下调AKT及MEK信号通路有关。     

小檗碱通过调控IGF-1R信号通路抑制食管癌细胞增殖和诱导细胞凋亡的实验

目的 检测小檗碱对食管癌细胞增殖、周期和凋亡的影响,并探讨其作用机制。 方法 MTT法检测细胞的增殖抑制作用;碘化丙啶（Propidium iodide, PI）染色法检测细胞周期进程;Annexin V-FITC和PI双染法结合流式细胞技术检测小檗碱的凋亡诱导作用;Western blot技术检测小檗碱对胰岛素样生长因子1受体（IGF-1R）的活化及下游主要信号分子AKT和p44/42MAPK（ERK）磷酸化水平的影响。结果 小檗碱在体外可浓度依赖性地抑制四种食管癌细胞系的增殖,且其IC50值与细胞表面IGF-1R的表达水平呈负相关。小檗碱可使细胞阻滞在G₂/M期。细胞凋亡实验结果显示,小檗碱可浓度依赖性地诱导食管癌细胞发生凋亡,并且在相同浓度下KYSE450细胞（IGF-1R高表达）的凋亡率显著高于KYSE150细胞（IGF-1R低表达）。Western blot结果显示,小檗碱处理可显著抑制IGF-1R的磷酸化,并抑制AKT和ERK的活化,且抑制作用随着小檗碱浓度的增加而增强。结论 小檗碱可通过对IGF-1R及其介导的下游信号通路的调控来发挥抑制食管癌细胞增殖、阻断细胞周期进程以及诱导食管癌细胞凋亡的作用。     

IGF －1R 阻断剂抑制人肝癌细胞 MHCC97－H 增殖转移的研究

目的：探讨 IGF －1R 阻断剂在人肝癌细胞 MHCC97－H 增殖转移中的作用。方法：培养人肝癌细胞株 MHCC97－H,预先给予 IGF －1R 阻断剂鬼臼苦素（picropodophyllin,PPP）10μmol／L 干预1h,然后给予 IGF－II 50ng／ml 作用48h,观察各组细胞形态变化,噻唑兰（MTT）法分析细胞生长情况,Brdu 法检测细胞增殖潜能,平板克隆实验观察并计算细胞克隆形成率,Real －time PCR 及 Western blot 法观察细胞增殖核抗原（PC-NA）、基质金属蛋白酶－9、－2（MMP －9、MMP －2）mRNA 及蛋白表达情况,进一步分析细胞增殖转移情况。结果：IGF －1R 阻断剂 PPP 可使 MHCC97－H 细胞形态发生明显改变;IGF －1R 阻断剂 PPP 显著抑制 MH-CC97－H 细胞存活率、细胞增殖及克隆形成（P ＜0．05）;与对照组相比,IGF －II 组 MHCC97－H 细胞中 PC-NA、MMP －9及 MMP －2的 mRNA 和蛋白表达显著升高（P ＜0．05）,而与 IGF －II 组相比,IGF －1R 阻断剂PPP 可明显抑制 MHCC97－H 细胞中 PCNA、MMP －9及 MMP －2的 mRNA 和蛋白表达（P ＜0．05）。结论：IGF －1R 阻断剂通过抑制人肝癌细胞 MHCC97－H 生长增殖,下调 PCNA、MMP －9及 MMP －2的表达,发挥阻碍人肝癌细胞 MHCC97－H 增殖转移的功效。     

成纤维细胞生长因子2激活肾上腺皮质癌H295R细胞的ERK、AKT信号通路

目的成纤维细胞生长因子2(FGF2)刺激肾上腺皮质细胞生长,参与该部位肿瘤的发生,但其涉及的细胞内信号传导通路研究尚少。本文拟探讨FGF2对人肾上腺皮质癌H295R细胞ERK和AKT信号通路的影响。方法培养H295R细胞;FGF2刺激细胞不同时间,用Western blot检测ERK1/2、p90RSK、Bad和AKT的磷酸化水平;FGF2和血管紧张素Ⅱ(AngⅡ)共处理细胞,Western blot检测磷酸化ERK1/2和AKT。结果 FGF2作用5 min时磷酸化ERK1/2和p90RSK明显增加,10～20 min达峰;而10～20 min时磷酸化Bad稍增加;FGF2作用5 min激活AKT(Thr308)和AKT(Ser473),并持续至60 min。AngⅡ刺激5 min磷酸化ERK1/2达高峰,此后作用减弱;FGF2和AngⅡ共处理细胞产生协同激活ERK1/2的作用。结论 FGF2明显激活H295R细胞的ERK及AKT信号通路,并在激活ERK通路上与AngⅡ有协同作用。     

放射抗拒人鼻咽癌细胞系的建立及其抗拒机制的初步探讨

[目的]建立放射抗拒人鼻咽癌细胞系模型并观察人鼻咽癌细胞经X射线反复照射后放射敏感性的变化及初步探讨其放射抗拒的机制.[方法]利用X射线对人鼻咽癌细胞HONE-1、SUNE2细胞系进行照射,采用剂量梯度法确定其亚致死照射剂量后,每次照射1次亚致死剂量,共照射5次或以上(HONE-1:6Gy×5次,SUNE2:4Gy×7次).采用克隆形成实验等测定所得的HONE-1-IR,SUNE2-IR细胞系及其亲代细胞HONE-1、SUNE2的放射敏感性、细胞周期特征及SP细胞比例.[结果]与亲代细胞HONE-1,SUNE2相比,HONE-1-IR、SUNE2-IR细胞的D0、Dq及SF2值均增大,HONE-1-IR细胞的放射抗拒性(D0)是HONE-1细胞的1.336倍,SUNE2-IR的D0值为SUNE2的1.094倍,表现出一定的放射抗拒性;HONE-1-IR、SUNE2-IR的S期细胞比例较其亲代细胞HONE-1、SUNE2明显增高(HONE-1-IR ys HONE-1:43.56％vs 23.08％,P=-0.002;SUNE2-IR vs SUNE2:32.64％vs 19.20％,P=0.029),G2/M期细胞比例明显降低(HONE-1-IRvsHONE-1:13.65％vs29.51％,P=0.002;SUNE2-IR vs SUNE2:10.25％vs22.63％,P=0.026),而G0/G1期细胞比例则无明显差异(P=0.735,P=0.572);HONE-1-IR细胞的SP细胞比例较HONE-1细胞明显增高(3.96％vs 0.02％),而SUNE2-IR细胞与SUNE2细胞的SP细胞比例分别为0.27％、0.06％.[结论]人鼻咽癌细胞株HONE-1、SUNE2经亚致死剂量X射线多次照射后而建立的后代细胞HONE-1-IR、SUNE2-IR具有一定的放射抗拒性;HONE-1-IR、SUNE2-IR细胞显示出与亲代细胞不同的细胞周期特征,放射抗拒性也可能与SP细胞比例增高有关,值得进一步探讨.     

AKt／mTOR 信号通路中 p70S6K1、4E －BPs 在促进肿瘤发生作用中的研究进展

当受细胞外生长因子等刺激作用后,可激活 PI3K／AKt／mTOR 信号通路,参与控制细胞的生长、增殖、生存、凋亡。AKt／mTOR 信号通路在肿瘤的发生发展过程中起着很重要的促进作用。AKt／mTOR 信号通路在肿瘤细胞中能够通过 p70S6K1和4E －BPs 的作用抑制细胞的凋亡,促进核糖体以及蛋白质的合成、促进肿瘤细胞的侵袭和转移、促进细胞周期进展、促进肿瘤血管的生成,进而促进肿瘤的发生发展。本文就AKt／mTOR 信号通路通过 p70S6K1和4E －BPs 促进肿瘤发生的机制进行综述。     

CDO1通过PI3K/AKT信号通路调控胃癌细胞增殖及细胞周期

目的:探讨半胱氨酸双加氧酶1(CDO1)对胃癌细胞增殖、细胞周期的调控机制。方法:用脂质体法将si-NC组（转染si-NC）、si-CDO1组（转染si-CDO1）、pcDNA组（转染pcDNA）、pcDNA-CDO1组（转染pcDNA-CDO1）、pcDNA-CDO1+DMSO组（转染pcDNA-CDO1并用DMSO处理）、pcDNA-CDO1+IGF-1组（转染pcDNA-CDO1并用IGF-1处理）转染至AKG细胞。用实时荧光定量逆转录聚合酶链反应（qRT-PCR）、免疫印迹（Western blot）、细胞计数试剂盒（CCK-8）、流式细胞术检测细胞CDO1、PI3K、Akt、p-Akt蛋白的表达、细胞增殖、细胞周期。结果:与人胃黏膜上皮细胞GES-1相比，胃腺癌细胞AKG中CDO1的表达明显降低（P<0.05）；与si-NC组相比，si-CDO1组AKG细胞的增殖明显上调，细胞发生明显的S期、G2/M期阻滞，过表达CDO1则具有相反的作用。重要的是，敲减CDO1可上调PI3K/AKT信号通路关键基因PI3K、p-Akt的表达，而过表达CDO1具有相反的作用。激活PI3K/AKT信号通路后，过表达CDO1对胃癌细胞的增殖、细胞周期的调控作用可被部分逆转。结论:CDO1可抑制胃癌细胞的增殖，调控细胞周期，其机制与抑制PI3K/AKT信号通路的活性有关，将为胃癌的治疗提供参考。     

Insulin‐like growth factor‐1 signaling is responsible for cathepsin G‐induced aggregation of breast cancer MCF‐7 cells

Cathepsin G (CG), a neutrophil serine protease, induces cell migration and multicellular aggregation of human breast cancer MCF‐7 cells in a process that is dependent on E‐cadherin and CG enzymatic activity. While these tumor cell aggregates can cause tumor emboli that could represent intravascular growth and extravasation into the surrounding tissues, resulting in metastasis, the molecular mechanism underlying this process remains poorly characterized. In this study, we aimed to identify the signaling pathway that is triggered during CG‐mediated stimulation of cell aggregation. Screening of a library of compounds containing approximately 90 molecular‐targeting drugs revealed that this process was suppressed by the insulin‐like growth factor‐1 (IGF‐1) receptor (IGF‐1R)‐specific kinase inhibitor OSI‐906, as well as the multikinase inhibitors axitinib and sunitinib. Antibody array analysis, which is capable of detecting tyrosine phosphorylation of 49 distinct receptor tyrosine kinases, and the results of immunoprecipitation studies indicated that IGF‐1R is phosphorylated in response to CG treatment. Notably, IGF‐1R neutralization via treatment with a specific antibody or silencing of IGF‐1R expression through siRNA transfection suppressed cell aggregation. Furthermore, CG treatment of MCF‐7 cells resulted in increased release of IGF‐1 into the medium for 24 h, while antibody‐mediated IGF‐1 neutralization partially prevented CG‐induced cell aggregation. These results demonstrate that autocrine IGF‐1 signaling is partly responsible for the cell aggregation induced by CG.     

Luteolin inhibits insulin-like growth factor 1 receptor signaling in prostate cancer cells

Insulin-like growth factor 1 receptor (IGF-1R) activation is required for prostate cell proliferation. Prostate cancer is one of the most commonly diagnosed malignant tumors in Western countries. Overexpression of IGF-1R in prostate cancer is associated with tumor growth. These suggest that IGF-1R inhibitory agents may be of preventive and/or therapeutic value. With evidence accumulating for a chemopreventive role of flavonoids, the effects of luteolin, a bioactive flavonoid, on IGF-1R signaling in prostate cancer cells were examined. Luteolin inhibited insulin-like growth factor 1 (IGF-1) induced activation of IGF-1R and AKT in prostate cancer PC-3 and DU145 cells. Inhibition of AKT by luteolin resulted in decreased phosphorylation of its downstream targets, including p70S6K1, GSK-3beta and FKHR/FKHRL1. Luteolin also inhibited the IGF-1-induced activation of EGFR and MAPK/ERK signaling. Luteolin inhibited expression of cyclin D1 and increased expression of p21. As a result, luteolin suppressed proliferation and induced apoptosis of prostate cancer cells. Knockdown of IGF-1R by siRNA led to inhibition of proliferation of prostate cancer cells. Results of in vivo tumor growth assay indicated that luteolin inhibited PC-3 tumor growth. Immunoblotting of the extracts of tumor tissues showed that luteolin inhibited IGF-1R/AKT signaling. Our results provide a new insight into the mechanisms that luteolin is against cancer cells.     

IGF-1R表达下调抑制肾癌786-0细胞的增殖、迁移、侵袭和细胞周期G1/S期转变

目的:观察小干扰RNA (siRNA)介导的胰岛素样生长因子1受体(IGF-1R)基因沉默对肾癌细胞786-0增殖、迁移、侵袭和细胞周期的影响.方法:采用实时定量PCR(real-time PCR)和蛋白印迹法(West-ern blot)测定转染后肾癌细胞IGF-lR及下游相关产物的表达;采用Cell counting kit-8(CCK-8)检测细胞增殖能力;Transwell实验及划痕实验检测细胞迁移及侵袭能力;流式细胞仪检测细胞凋亡及周期改变.结果:IGF-1R基因的siRNA可有效抑制IGF-1R mRNA及蛋白的表达(P＜0.01);细胞增殖实验结果显示IGF-1R-siRNA转染组增殖能力显著减弱(P＜0.01);Transwell实验及划痕实验结果显示IGF-1R-siRNA转染组侵袭及迁移能力明显降低(P＜0.01);流式细胞术检测到转染后细胞G1期细胞数明显升高,发生G1/S期阻滞(P＜0.05);IGF-1R下游蛋白p-IRS1、p-IRS2、p-SHC水平显著降低.结论:IGF-1R表达下调可以抑制肾癌786-0细胞的生长、增殖、迁移和侵袭的能力,并可以使肾癌786-0细胞G1/S期细胞周期停滞.     

LINC00649通过miR-424-5p/IGF1R轴调控内质网应激介导的宫颈癌细胞凋亡

目的探讨LINC00649/miR-424-5p/IGF1R对内质网应激(ERs)介导的宫颈癌(CC)细胞凋亡的影响。方法从GEO数据库中获取CC相关的数据,并分析差异表达的miRNAs。利用生物信息学数据库预测miR-424-5p的上、下游靶点,将LINC00649和IGF1R纳入研究,随后双荧光素酶实验进一步验证靶向关系。qRT-PCR检测LINC00649、miR-424-5p和IGF1R在CC组织和细胞中的表达水平。CCK-8和流式细胞术分别评估CC细胞增殖和凋亡变化。Western blot检测ERs相关蛋白GRP78、CHOP和Caspase-12的表达。结果与癌旁组织和H8细胞相比,LINC00649和IGF1R在CC组织和细胞中表达上调,而miR-424-5p下调(均P<0.05)。LINC00649的异常高表达与CC患者的预后不良有关,敲减LINC00649可通过促进ERs来抑制CC细胞活力,诱导细胞凋亡(均P<0.05)。LINC00649吸附miR-424-5p上调IGF1R的表达。miR-424-5p抑制剂或过表达IGF1R均可部分逆转敲减LINC00649对CC细胞的影响(均P<0.05)。结论 LINC00649能够通过miR-424-5p/IGF1R抑制CC细胞的ERs过程进而减少细胞凋亡,提高细胞活力。     

LINC00649通过miR-424-5p/IGF1R轴调控内质网应激介导的宫颈癌细胞凋亡

目的探讨LINC00649/miR-424-5p/IGF1R对内质网应激(ERs)介导的宫颈癌(CC)细胞凋亡的影响。方法从GEO数据库中获取CC相关的数据,并分析差异表达的miRNAs。利用生物信息学数据库预测miR-424-5p的上、下游靶点,将LINC00649和IGF1R纳入研究,随后双荧光素酶实验进一步验证靶向关系。qRT-PCR检测LINC00649、miR-424-5p和IGF1R在CC组织和细胞中的表达水平。CCK-8和流式细胞术分别评估CC细胞增殖和凋亡变化。Western blot检测ERs相关蛋白GRP78、CHOP和Caspase-12的表达。结果与癌旁组织和H8细胞相比,LINC00649和IGF1R在CC组织和细胞中表达上调,而miR-424-5p下调(均P<0.05)。LINC00649的异常高表达与CC患者的预后不良有关,敲减LINC00649可通过促进ERs来抑制CC细胞活力,诱导细胞凋亡(均P<0.05)。LINC00649吸附miR-424-5p上调IGF1R的表达。miR-424-5p抑制剂或过表达IGF1R均可部分逆转敲减LINC00649对CC细胞的影响(均P<0.05)。结论 LINC00649能够通过miR-424-5p/IGF1R抑制CC细胞的ERs过程进而减少细胞凋亡,提高细胞活力。     

UVA-induced cell cycle progression is mediated by a disintegrin and metalloprotease/epidermal growth factor receptor/AKT/Cyclin D1 pathways in keratinocytes

UVA (315-400 nm), which constitutes approximately 95% of the UV irradiation in natural sunlight, represents a major environmental challenge to the skin and is clearly associated with human skin cancer. Here, we show that a low, nonlethal dose of UVA induces dose-dependent cell cycle progression in human HaCaT keratinocytes. We found that UVA induced cyclin D1 accumulation, whereas siRNA knockdown of cyclin D1 blocked the UVA-induced cell cycle progression, indicating that this process is mediated by cyclin D1. UVA irradiation also induced AKT activation; when cells were incubated with phosphatidylinositol-3-OH kinase/AKT inhibitor or infected with dominant-negative AKT, cyclin D1 up-regulation, cell cycle progression, and proliferation were inhibited, suggesting that AKT activation is required for UVA-induced cell cycle progression. In contrast, extracellular signal-regulated kinase (ERK) was not activated by UVA exposure; incubation with ERK/mitogen-activated protein kinase inhibitor had no effect on UVA-induced cyclin D1 up-regulation and cell cycle progression. Activation of epidermal growth factor receptor (EGFR) was observed after UVA exposure. EGFR kinase inhibitor AG attenuated the UVA-induced AKT/cyclin D1 pathway and cell cycle progression, indicating that EGFR is upstream of AKT/cyclin D1 pathway activation. Furthermore, metalloprotease inhibitor GM6001 blocked UVA-induced cell cycle progression, and siRNA knockdown of a disintegrin and metalloprotease (ADAM)17 had a similar inhibitory effect, demonstrating that ADAM17 mediates the EGFR/AKT/cyclin D1 pathway and cell cycle progression to the S phase induced by UVA radiation. Identification of these signaling pathways in UVA-induced cell proliferation will facilitate the development of efficient and safe chemopreventive and therapeutic strategies for skin cancer.     

Epidermal growth factor receptor and K-Ras mutations and resistance of lung cancer to insulin-like growth factor 1 receptor tyrosine kinase inhibitors

BACKGROUND:

Most patients with nonsmall cell lung cancer (NSCLC) have responded poorly to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). The authors investigated the involvement of insulinlike growth factor 1 receptor (IGF‐1R) signaling in primary resistance to EGFR TKIs and the molecular determinants of resistance to IGF‐1R TKIs.

METHODS:

Phosphorylated IGF‐1R/insulin receptor (pIGF‐1R/IR) was immunohistochemically evaluated in an NSCLC tissue microarray. The authors analyzed the antitumor effects of an IGF‐1R TKI (PQIP or OSI‐906), either alone or in combination with a small‐molecular inhibitor (PD98059 or U0126) or with siRNA targeting K‐Ras or mitogen‐activated protein kinase/extracellular signal‐regulated kinase kinase (MEK), in vitro and in vivo in NSCLC cells with variable histologic features and EGFR or K‐Ras mutations.

RESULTS:

pIGF‐1R/IR expression in NSCLC specimens was associated with a history of tobacco smoking, squamous cell carcinoma histology, mutant K‐Ras, and wild‐type (WT) EGFR, all of which have been strongly associated with poor response to EGFR TKIs. IGF‐1R TKIs exhibited significant antitumor activity in NSCLC cells with WT EGFR and WT K‐Ras but not in those with mutations in these genes. Introduction of mutant K‐Ras attenuated the effects of IGF‐1R TKIs on NSCLC cells expressing WT K‐Ras. Conversely, inactivation of MEK restored sensitivity to IGF‐TKIs in cells carrying mutant K‐Ras.

CONCLUSIONS:

The mutation status of both EGFR and K‐Ras could be a predictive marker of response to IGF‐1R TKIs. Also, MEK antagonism can abrogate primary resistance of NSCLC cells to IGF‐1R TKIs. Cancer 2012. © 2012 American Cancer Society.     

Enhancement of doxorubicin cytotoxicity of human cancer cells by tyrosine kinase inhibition of insulin receptor and type I IGF receptor

The type I insulin-like growth factor receptor (IGF1R) contributes to cancer cell biology. Disruption of IGF1R signaling alone or in combination with cytotoxic agents has emerged as a new therapeutic strategy. Our laboratory has shown that sequential treatment with doxorubicin (DOX) and anti-IGF1R antibodies significantly enhanced the response to chemotherapy. In this study, we examined whether inhibition of the tyrosine kinase activity of this receptor family would also enhance chemotherapy response. Cis-3-[3-(4-methyl-piperazin-l-yl)-cyclobutyl]-1-(2-phenyl-quinolin-7-yl)-imidazo[1,5-a]pyrazin-8-ylamine (PQIP) inhibited IGF1R and insulin receptor (InsR) kinase activity and downstream activation of ERK1/2 and Akt in MCF-7 and LCC6 cancer cells. PQIP inhibited both monolayer growth and anchorage-independent growth in a dose-dependent manner. PQIP did not induce apoptosis, but rather, PQIP treatment was associated with an increase in autophagy. We examined whether sequential or combination therapy of PQIP with DOX could enhance growth inhibition. PQIP treatment together with DOX or DOX followed by PQIP significantly inhibited anchorage-independent growth in MCF-7 and LCC6 cells compared to single agent alone. In contrast, pre-treatment with PQIP followed by DOX did not enhance the cytotoxicity of DOX in vitro. Furthermore, OSI-906, a PQIP derivative, inhibited IGF-I signaling in LCC6 xenograft tumors in vivo. When given once a week, simultaneous administration of OSI-906 and DOX significantly enhanced the anti-tumor effect of DOX. In summary, these results suggest that timing and duration of the IGF1R/InsR tyrosine kinase inhibitors with chemotherapeutic agents should be evaluated in clinical trials. Long-term disruption of IGF1R/InsR may not be necessary when combined with cytotoxic chemotherapy.