米非司酮对人宫颈癌Hela细胞增殖及细胞周期的影响

目的探讨米非司酮对人子宫颈癌Hela细胞增殖及细胞周期分布的影响。方法采用MTT测定，观察不同浓度米非司酮(10、5、2.5、1μmol/L)对Hela细胞增殖的抑制作用；通过ABC免疫组化染色及流式细胞仪分析，检测用药后Ki-67抗原、细胞周期分布及增殖指数的变化。结果4个浓度的米非司酮对Hela细胞增殖均有抑制作用，并呈剂量依赖性，以10μmol/L浓度抑制作用最强，抑制率达54%；2.5μmol/L米非司酮可使Ki-67抗原表达明显减少，米非司酮(5μmol/L)使Hela细胞阻滞于G0/G1期，不能进入S期及G2/M期，抑制DNA的合成，使细胞增殖指数明显下降。结论米非司酮体外对PR阳性的人宫颈癌细胞有明显的抑制作用，使细胞周期分布阻滞于G0/G1期。     

塞来昔布对宫颈癌细胞的化疗增敏作用

目的探讨特异性环氧化酶-2（COX-2）抑制剂塞来昔布对顺铂诱导宫颈癌Hela细胞增殖与凋亡的作用及机制。方法采用四甲基偶氮唑蓝比色法（MTT）,测定塞来昔布对顺铂诱导Hela细胞增殖活性的作用;应用流式细胞仪检测细胞凋亡率;Western blot检测Hela细胞中Bcl-2、Bax蛋白的表达情况。结果 5、10μmol/L的塞来昔布分别与顺铂联合应用,可增强顺铂对Hela细胞增殖抑制作用。塞来昔布（5μmol/L）能促进顺铂诱导Hela细胞的凋亡。塞来昔布作用于Hela细胞后,Bcl-2蛋白表达水平下调、Bax蛋白表达水平上调呈浓度依赖关系。结论塞来昔布能促进顺铂对Hela细胞增殖抑制和诱导凋亡作用,起化疗增敏作用,可能与其下调Bcl-2蛋白表达水平、上调Bax蛋白表达水平有关。     

芹菜素通过 PI3K/Akt 信号通路诱导 Hela 细胞凋亡

目的：初探芹菜素（Apigenin）对人宫颈癌细胞 Hela 的抑制机制。方法：MTT 法检测 Apigenin 对 Hela细胞的增殖抑制作用,实时无标记细胞分析技术测量 Apigenin 对 Hela 细胞生长曲线的影响。Western blot 检测 Apigenin 对 Hela 细胞中 PI3K/ Akt 信号通路的影响。结果：与阴性对照组相比,Apigenin 能显著抑制 Hela细胞的增殖（P <0.01）,当药物浓度为20μmol/ L 时抑制率达到（80.5±5.3）%,IC50值为（6.8±0.8）μmol/ L。细胞生长曲线反映,Apigenin 减缓了 Hela 细胞的增殖,对数期细胞经20μmol/ L Apigenin 处理后,细胞数量迅速下降。Western blot 结果显示,Apigenin 能显著抵抗 IGF -1引起的 Akt 激活但并不能降低 PI3K 的磷酸化水平。同时 Apigenin 还能降低 Bcl -2/ Bax 比例,提高 Caspase -3活性,启动细胞线粒体凋亡。结论：Apigenin可以通过 PI3K/ Akt 信号通路促进 Hela 细胞的凋亡。     

顺铂联合土贝母皂苷甲对宫颈癌Hela细胞的增殖抑制作用研究

目的:探讨土贝母皂苷甲与顺铂单独及联合应用对人宫颈癌Hela细胞的抑制作用,以期对临床上药物治疗宫颈癌提供新的思路和理论依据.方法:采用MTT法检测单用土贝母皂苷甲、DDP及两药联合时对HeLa细胞的生长抑制率.用流式细胞仪测定细胞周期变化.结果:土贝母皂苷甲组(20μg/ml、40μg/ml、80μg/ml)、顺铂组(10μmol/L)及联合组(40μg/ml土贝母皂苷甲+10μmol/L顺铂)宫颈癌Hela细胞株均有不同程度的生长抑制作用;土贝母皂苷甲组随着药物浓度增加,作用时间延长,对Hela细胞的生长抑制率逐渐升高;土贝母皂苷甲与顺铂联合用药较单一用药对Hela细胞的生长抑制率增高,具有浓度―时间依赖性.流式细胞仪分析结果显示:土贝母皂苷甲组、顺铂组及联合组作用于宫颈癌Hela细胞株24小时,可阻滞细胞周期于G2/M期.结论:土贝母皂苷甲对宫颈癌HeLa细胞株具有生长抑制作用,且呈剂量和时间依赖性,其与顺铂联合应用具有协同作用,联合应用可减少顺铂用药剂量;土贝母皂苷甲与顺铂单独及联合作用于宫颈癌Hela细胞株24h可阻滞细胞周期于G2/M期.     

小干扰RNA抑制bcl-xL表达对食管癌细胞化疗敏感性的影响

目的探讨凋亡抑制分子bcl-xL表达下调对食管癌细胞化疗敏感性的影响。方法根据人bcl-xL基因序列设计和合成3对小干扰RNA,将其转染于体外培养的人食管癌细胞株Eca-109,通过RT-PCR和Western-blotting检测bcl-xL的表达情况,筛选出对bcl-xL表达抑制作用最强的小干扰RNA,通过MTT法检测小干扰RNA转染细胞和对照细胞在不同浓度顺铂和紫杉醇作用下的细胞增殖抑制率,计算出半数抑制浓度IC50值并进行对比分析。结果食管癌细胞转染靶向bcl-xL的3种小干扰RNA后,bcl-xL mRNA和蛋白表达均显示出不同程度下调,其中siRNA1对癌细胞bcl-xL表达的抑制作用最强。siRNA1转染食管癌细胞后可使顺铂和紫杉醇对癌细胞的IC50值由转染前的（31.4±4.3）μmol/L和（35.3±6.1）μmol/L下降至转染后的（8.4±3.3）μmol/L和（15.1±4.7）μmol/L（P〈0.01）。结论小干扰RNA抑制bcl-xL表达可增强食管癌细胞对顺铂和紫杉醇化疗的敏感性。     

小干扰RNA抑制bcl-xL表达对食管癌细胞化疗敏感性的影响

目的 探讨凋亡抑制分子bcl-xL表达下调对食管癌细胞化疗敏感性的影响.方法 根据人bcl-xL基因序列设计和合成3对小干扰RNA,将其转染于体外培养的人食管癌细胞株Eca-109,通过RT-PCR和Western-blotting检测bcl-xL的表达情况,筛选出对bcl-xL表达抑制作用最强的小干扰RNA,通过MTT法检测小干扰RNA转染细胞和对照细胞在不同浓度顺铂和紫杉醇作用下的细胞增殖抑制率,计算出半数抑制浓度IC50值并进行对比分析.结果 食管癌细胞转染靶向bcl-xL的3种小干扰RNA后,bcl-xL mRNA和蛋白表达均显示出不同程度下调,其中siRNA1对癌细胞bcl-xL表达的抑制作用最强.siRNA1转染食管癌细胞后可使顺铂和紫杉醇对癌细胞的IC5o值由转染前的(31.4±4.3)μmol/L和(35.3±6.1)μmol/L下降至转染后的(8.4±3.3)μmol/L和(15.1±4.7)μmol/L(P＜0.01).结论 小干扰RNA抑制bcl-xL表达可增强食管癌细胞对顺铂和紫杉醇化疗的敏感性.     

ZD6474对鼻咽癌细胞株CNE2抑制作用及其机制的探讨

目的:研究ZD6474对鼻咽癌细胞株CNE2的抑制作用.方法: 采用MTT 法测定ZD6474的抑制浓度(IC50) ,流式细胞仪检测ZD6474的凋亡率及细胞周期分布.结果: MTT数据显示,CNE2细胞的抑制率与ZD6474浓度成正相关,随ZD6474浓度升高,抑制作用越明显,IC50=2.531 μmol/L;流式细胞术分析显示,ZD6474处理48 h使CNE2细胞凋亡率明显升高[(24.02±5.90)%],且随浓度升高凋亡率升高越明显,P<0.001.细胞周期结果显示,ZD6474使细胞周期S期[(34.96±5.37)%]比例下降,G0/G1期[(56.25±1.45)%]和G2/M期[(17.36±5.73)%]比例升高.结论: ZD6474能明显抑制CNE2细胞的增殖,促进其凋亡并改变其细胞周期的分布.     

GNA对人宫颈癌细胞增殖抑制、凋亡、迁移及细胞周期分布的影响

目的:研究新藤黄酸（gambogic acid,GNA）对人宫颈癌细胞的增殖抑制、凋亡、迁移以及细胞周期分布的影响。方法:将人宫颈癌Hela细胞分为空白对照组、25 μmol/L浓度组、50 μmol/L浓度组和100 μmol/L浓度组,进行细胞培养后采用MTT法和流式细胞术检测细胞24 h、48 h和72 h时间段的增殖抑制和凋亡情况,Transwell实验检测细胞迁移情况,流式细胞仪检测细胞周期分布,Western blot检测Bcl-2、Bax、E-cadherin和NF-κB蛋白相对表达量。结果:25 μmol/L浓度组、50 μmol/L浓度组和100 μmol/L浓度组对宫颈癌细胞的抑制增殖率在不同时间段均显著高于空白对照组,增殖抑制率随着浓度和时间的增加而升高（P＜0.05）;25 μmol/L浓度组、50 μmol/L浓度组和100 μmol/L浓度组宫颈癌细胞凋亡率在各时间段均显著高于空白对照组,凋亡率随着浓度和时间的增加而升高（P＜0.05）;25 μmol/L浓度组、50 μmol/L浓度组和100 μmol/L浓度组宫颈癌细胞的细胞迁移数量相比对照组均显著减少,细胞迁移数量随着浓度的增加而减少（P＜0.05）;GNA浓度越高,处于G0/G1期的细胞比例越高,处于G2/M和S期的细胞比例越低;25 μmol/L浓度组、50 μmol/L浓度组和100 μmol/L浓度组Bcl-2、NF-κB均低于空白对照组（P＜0.05）;25 μmol/L浓度组、50 μmol/L浓度组和100 μmol/L浓度组Bax、E-cadherin表达均高于空白对照组。结论:GNA能够促进宫颈癌细胞的凋亡,抑制细胞的增殖和迁移能力,通过改变癌细胞的周期分布降低癌细胞的增长,其能力呈现浓度依赖性。     

MTBD抗肿瘤细胞活性及作用机制研究

目的:对新发现的Aurora-B激酶抑制剂4-[2-(3-甲基噻吩-2-基)噻唑-4-基]-苯-1,2-二醇(MTBD)进行肿瘤细胞增殖抑制活性和作用机制的研究。方法:MTT法检测MTBD对肿瘤细胞的增殖抑制活性;流式细胞术检测MTBD对Hela细胞的周期阻滞和组蛋白3的磷酸化;ELISA方法检测MTBD对Aurora-B激酶的抑制活性;RT-PCR技术检测MTBD对S期检查点的相关蛋白转录水平的影响。结果:MTBD能够抑制Hela细胞、HepG2细胞和A549细胞的增殖,其IC50分别为(1.03±2.23)、(1.72±3.78)和(2.01±1.23)μmol/L;MTBD能够诱导Hela细胞发生G2/M期和S期阻滞,并诱导细胞发生凋亡;MTBD能够抑制Aurora-B激酶活性,其IC50为(1.70±2.02)μmol/L,但未能检测到Hela细胞内组蛋白3(Ser10)磷酸化水平下降;S期检查点相关基因p21和p53转录上调,CDK2、Cyclin A1和pCNA转录不同程度下调。结论:MTBD能抑制肿瘤细胞增殖,诱导细胞周期阻滞和凋亡;MTBD抗肿瘤活性的发挥可能不是主要通过Aurora-B激酶抑制,而是与多个细胞周期因子相关,并且对于不同肿瘤细胞株有不同的作用机制。     

顺铂诱导铁死亡促进肿瘤相关巨噬细胞极化抑制宫颈癌细胞耐药性北大核心

目的:探究顺铂通过引起宫颈癌细胞铁死亡进而诱导肿瘤相关巨噬细胞极化从而抑制宫颈癌细胞耐药性的机制。方法:使用5μmol/L顺铂处理顺铂耐药宫颈癌细胞Hela/R一定时间后,采用qRT-PCR法检测铁死亡相关基因的mRNA表达变化情况;使用ELISA试剂盒和荧光染色法测定铁死亡后的Hela/R细胞释放高迁移率族蛋白1(high mobility group box 1,HMGB1)的情况。将顺铂处理过的Hela/R细胞和M2型小鼠骨髓来源巨噬细胞共培养一定时间后,采用流式细胞术检测巨噬细胞激活情况。将共培养后的巨噬细胞和Hela/R细胞共孵育,采用CCK8法和流式细胞术分别检测肿瘤细胞的存活率和凋亡情况。结果:实验数据显示,顺铂可引起Hela/R细胞的铁死亡,抑制其铁死亡抑制基因Slc40a1、Slc7a11、Slc3a2、Gpx4、Fth1、Blvrb的mRNA表达(P<0.05),上调铁死亡诱发基因Slc5a1、Tfrc的mRNA表达(P<0.01)。铁死亡Hela/R细胞释放损伤相关模式分子HMGB1,诱导M2型肿瘤相关巨噬细胞的CD80、CD86和CD40平均荧光强度提升,增强了肿瘤相关巨噬细胞对Hela/R细胞的杀伤能力。结论:顺铂通过引起宫颈癌细胞的铁死亡激活肿瘤相关巨噬细胞进而达到有效杀伤肿瘤细胞的效果。     

表皮生长因子受体酪氨酸激酶抑制剂ZD1839对鼻咽癌细胞系的作用

ZDl839是一种喹唑啉类化合物,它是一种口服的选择性的表皮生长因子受体酪氨酸激酶抑制剂,已被美国食品药品管理局批准用于治疗晚期非小细胞肺癌。鼻咽癌是一种存在表皮生长因子受体表达的上皮源性的恶性肿瘤,ZDl839对其作用如何还未见有报道。本实验通过体外研究初步探讨ZDl839在鼻咽癌治疗中的可能价值。     

ZD1839 ('Iressa'), a specific oral epidermal growth factor receptor-tyrosine kinase inhibitor, potentiates radiotherapy in a human colorectal cancer xenograft model

The effect of ZD1839 ('Iressa'), a specific inhibitor of the tyrosine kinase activity of the epidermal growth factor receptor, on the radiation response of human tumour cells (LoVo colorectal carcinoma) was evaluated in vitro and in vivo. ZD1839 (0.5 microM, incubated days 1-5) significantly increased the anti-proliferative effect of fractionated radiation treatment (2 Gy day(-1), days 1-3) on LoVo cells grown in vitro (P=0.002). ZD1839 combined with either single or fractionated radiotherapy in mice bearing LoVo tumour xenografts, also produced a highly significant increase in tumour growth inhibition (P< or = 0.001) when compared to treatment with either modality alone. The radio-potentiating effect of ZD1839 was more apparent when radiation was administered in a fractionated protocol. This phenomenon may be attributed to an anti proliferative effect of ZD1839 on tumour cell re-population between radiotherapy fractions. These data suggest radiotherapy with adjuvant ZD1839 could enhance treatment response. Clinical investigation of ZD1839 in combination with radiotherapy is therefore warranted.     

表皮生长因子受体酪氨酸激酶抑制剂ZD1839与奥沙利铂联合对人肺癌A549细胞的作用

背景与目的:ZD1839是一种表皮生长因子受体酪氨酸激酶的小分子抑制剂,是目前肺癌分子靶向治疗中较为成熟的药物,因其单药临床有效率低,如何与化疗联合提高抗癌效应受到关注.本实验通过研究ZD1839联合奥沙利铂的不同给药方案对人肺腺癌细胞A549的杀伤作用,探讨两药联合的最佳模式.方法:以药物联合效应测定方法,评价ZD1839和奥沙利铂不同给药顺序对A549细胞的抑制作用,以流式细胞仪测定不同联合方案对A549细胞周期分布及凋亡率的影响.观察ZD1839、奥沙利铂不同给药方案作用时,裸鼠A549细胞移植瘤生长情况,测定肿瘤生长抑制率.结果:先奥沙利铂后ZD1839的序贯给药方案表现出明显的协同作用,药物联合指数为0.51±0.01;而先ZD1839后给予奥沙利铂时,药物联合指数为1.56±0.03,两药间为拮抗作用.先奥沙利铂后ZD1839组G2/M期细胞比例与其他组相比明显增加,达到37.9%(P＜0.05),细胞凋亡率达到22.3%.体内实验表明,先奥沙利铂后ZD1839组抑瘤率最高,达到58.9%;而先奥沙利铂 ZD1839 24 h后ZD1839 48 h组的抑瘤率为52.4%,ZD1839后奥沙利铂组的抑瘤率为30.6%.结论:先奥沙利铂后ZD1839序贯给药对A549细胞增殖的抑制作用更强.     

EGFR blockade with ZD1839 ("Iressa") potentiates the antitumor effects of single and multiple fractions of ionizing radiation in human A431 squamous cell carcinoma. Epidermal growth factor receptor

PURPOSE: Signaling pathways initiated by the epidermal growth factor receptor (EGFR) play important roles in the response to ionizing radiation. In this study the consequences of inhibiting the EGFR on the response of A431 cells (human vulvar squamous cell carcinoma cells that overexpress EGFR) to radiation, were investigated in vitro and in vivo, using the selective EGFR-tyrosine kinase inhibitor, ZD1839 ("Iressa"). METHODS AND MATERIALS: The effect of ZD1839 on proliferation, apoptosis, and clonogenic survival after radiation was determined in vitro. For in vivo studies, athymic nude mice with established subcutaneous A431 xenografts (approximately 100 mm(3)) were treated with either a single 10 Gy fraction or 4 daily 2.5 Gy fractions of radiation with or without ZD1839 (75 mg/kg/day intraperitoneally for 10 days) to determine effects on tumor growth delay. RESULTS: Treatment of A431 cells with ZD1839 in vitro reduced proliferation, increased apoptosis, and reduced clonogenic survival after radiation. Strikingly greater than additive effects of ZD1839 in combination with radiation on tumor growth delay were observed in vivo after either a single 10 Gy fraction (enhancement ratio: 1.5) or multiple 4 x 2.5 Gy fractions (enhancement ratio: 4). ZD1839 reduced tumor vascularity, as well as levels of vascular endothelial growth factor (VEGF) protein and mRNA induced by stimulation with epidermal growth factor (EGF), suggesting a possible role of inhibition of angiogenesis in the effect. CONCLUSIONS: Inhibiting EGFR-mediated signal transduction cascades with ZD1839 potentiates the antitumor effect of single and multiple fractions of radiation. These data provide preclinical rationale for clinical trials of EGFR inhibitors including ZD1839 in combination with radiation.     

The effects of ZD1839 (Iressa), a highly selective EGFR tyrosine kinase inhibitor, as a radiosensitiser in bile duct carcinoma cell lines

The signaling pathway that is initiated by binding of epidermal growth factor receptor (EGFR) and results in sustained signaling through PI3K plays an important role in a tumor's response to ionizing radiation. The current in vitro study explored both the effects of ZD1839 (Iressa), a highly selective EGFR tyrosine kinase inhibitor, as a radiosensitiser for bile duct carcinoma cell lines and ZD1839's general effects on cell growth in the same two lines. Secondly, we ensured suppression of radiation-induced phosphorylation of EGFR by ZD1839 using an immunoprecipitation technique. Furthermore, we examined radiation-induced phosphorylation of ERK, p38, JNK, and AKT with or without inhibitor with use of Western blot techniques and performed clonogenic assays to confirm radiosensitivity in the presence of a drug. ZD1839 inhibited cell growth of both cell lines and suppressed radiation-induced phosphorylation of EGFR. After exposure to radiation, there was an increase in phosphorylation of AKT as shown by Western blot. Treatment with either ZD1839 or LY294002 (the latter, a PI3K inhibitor) suppressed phosphorylation of AKT by Western blot. Both ZD1839 and LY294002 significantly suppressed colony formation by clonogenic assay; however, U0126 (a MEK1/2 inhibitor), SB203580 (a p38 inhibitor), and SP600125 (a JNK inhibitor) had no effect on colony formation. These results suggest that AKT may be a useful target molecule for enhancement of radiotherapy effect and that ZD1839 may have an important role in combination with radiotherapy for patients with bile duct carcinoma.     

ZD1839, a specific epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, induces the formation of inactive EGFR/HER2 and EGFR/HER3 heterodimers and prevents heregulin signaling in HER2-overexpressing breast cancer cells.

PURPOSE: ZD1839 is a tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR) that has shown clinical activity against EGFR-expressing tumors. Our aim was to explore the effects of ZD1839 in breast cancer cell lines expressing different levels of EGFR and the closely related HER2 receptor. EXPERIMENTAL DESIGN: We studied the growth-inhibitory effects of ZD1839 in a series of breast carcinoma cell lines. In HER2-overexpressing BT-474 breast cancer cells, we studied the effects of ZD1839 on cell growth and heterodimerization of receptors under basal and ligand-stimulated conditions. RESULTS: ZD1839 was an equally potent inhibitor of growth in breast cancer cells expressing high levels of EGFR and HER2. In BT-474 breast cancer cells, ZD1839 abolished EGF- and heregulin-induced activation of ErbB receptors and downstream signaling molecules. Because ZD1839 does not inhibit the HER2 tyrosine kinase in vitro, and because heregulin is a ligand that activates HER2 by binding to HER3 and HER4 but does not bind to the EGFR, our findings suggested that ZD1839 interfered with HER2 function in intact cells. Searching for mechanisms, we report that ZD1839 induces the formation of inactive unphosphorylated EGFR/HER2 and EGFR/HER3 heterodimers. Furthermore, ZD1839 completely abolishes basal and heregulin-induced formation of active phosphorylated HER2/HER3 heterodimers. CONCLUSIONS: ZD1839 inhibits the growth of HER2-overexpressing breast cancer cells, possibly by sequestration of HER2 and HER3 receptors in an inactive heterodimer configuration with the EGFR. Our findings suggest that there is a strong rationale to conduct clinical trials of ZD1839 in patients with HER2-overexpressing breast tumors.     

Differential radiosensitisation by ZD1839 (Iressa), a highly selective epidermal growth factor receptor tyrosine kinase inhibitor in two related bladder cancer cell lines

The epidermal growth factor receptor (EGFR) is expressed in a wide variety of epithelial tumours including carcinoma of the bladder. Stimulation of the EGFR pathway is blocked by ZD1839 (Iressa), a highly selective EGFR tyrosine kinase inhibitor. Radical radiotherapy is an established organ sparing treatment option for muscle invasive bladder cancer and this study has explored the possibility for the use of ZD1839 as a radiosensitiser in this scenario. The effect of combination treatment with ZD1839 (0.01 microM) and ionising radiation in the established bladder cancer cell lines MGH-U1 and its radiosensitive mutant clone S40b was measured by clonogenic assays. A highly significant radiosensitising effect was seen in both cell lines (P < 0.001 for MGH-U1 and S40b cell lines). This effect was independent of the concentration of the drug and the duration of exposure prior to treatment with ionising radiation. Cell cycle kinetics of both cell lines was not significantly altered with ZD1839 (0.01 microM) as a single agent. A modest induction of apoptosis was observed with ZD1839 (0.01 microM) as a single agent, but a marked induction was observed with the combination treatment of ZD1839 and ionising radiation. These results suggest a potentially important role for ZD1839 in combination with radiotherapy in the treatment of muscle invasive bladder cancer.     

Preclinical evaluation of ZD1839 alone or in combination with oxaliplatin in a panel of human tumor cell lines -- implications for clinical use

BACKGROUND: Preclinical studies have suggested antitumor activity of an epidermal growth factor (EGF)-receptor targeted therapy with selective tyrosine kinase inhibitors alone or in combination with conventional cytostatic drugs. However, in non-small cell lung cancer (NSCLC), addition of ZD1839 (Iressa) to combination chemotherapy did not improve the therapeutic outcome. Thus, further work is necessary to define factors predicting outcome of combination therapy. MATERIALS AND METHODS: In the present study, the activity of ZD1839 alone or in combination with oxaliplatin (Eloxatin) was evaluated in 12 human cancer cell lines including colon, testicular, anaplastic thyroid and epidermoid carcinoma cells. RESULTS: The EGF-receptor protein was overexpressed in line A431 (epidermoid carcinoma) and near the minimum detection limit in all other cell lines. The single agent activity of ZD1839 was highest in cell line A431. In the other cell lines, it was lower and appeared to be independent of EGF-receptor expression levels. The relative antitumor activity (RAA) was low (RAA = 1). Combined exposure to oxaliplatin and ZD1839 (IC30) resulted in significant synergy in 4 out of 6 colorectal cancer (CRC) cell lines and significant antagonism in 4 out of 6 non-colorectal cancer cell lines. Continuous exposure to ZD1839 (IC30) induced a marked G1-phase arrest and dephosphorylation of EGF-receptor in A431, whereas no significant cell cycle perturbation could be detected in the low-expression cell lines. Other factors than cell cycle perturbation seem to determine the mode of drug interaction between oxaliplatin and ZD1839. CONCLUSION: Based on RAA, the single agent activity of ZD1839 in the investigated cell line panel appeared to be low. Combined exposure to ZD1839 and oxaliplatin exerted synergy in colorectal cancer cell lines, warranting further evaluation in this type of cancer. However, based on the observed antagonism in non-colorectal cancer cell lines, combined treatment with ZD1839 and oxaliplatin is not recommended for other types of cancer. Further research is necessary to identify factors which determine the nature of drug interaction in different tumor types including CRC and lung cancer.     

Cooperative inhibitory effect of ZD1839 (Iressa) in combination with trastuzumab (Herceptin) on human breast cancer cell growth.

BACKGROUND: Co-expression of the epidermal growth factor receptor (EGFR) and of ErbB-2 is found in a subset of primary human breast cancer. MATERIALS AND METHODS: The antiproliferative effects of anti-EGFR and anti-ErbB-2 agents were evaluated using a monolayer assay. The effects of these agents on the activation of EGFR, ErbB-2, AKT and p42/p44 MAP kinases (MAPK) were investigated by western blot analysis. RESULTS: We found that both ZD1839 (Iressa), a specific EGFR tyrosine kinase inhibitor, and trastuzumab (Herceptin) (TRA), a humanized anti-ErbB-2 monoclonal antibody, were able to inhibit the growth of SK-Br-3 and BT-474 breast carcinoma cells, which express both EGFR and ErbB-2. Treatment of breast carcinoma cells with a combination of ZD1839 and TRA resulted in a synergistic inhibitory effect. Treatment of SK-Br-3 cells with ZD1839 produced a significant, dose-dependent reduction of the tyrosine phosphorylation of both EGFR and ErbB-2. Phosphorylation of MAPK and AKT were significantly reduced in SK-Br-3 cells following treatment with ZD1839, whereas treatment with TRA produced a reduction of AKT but not MAPK phosphorylation. Finally, treatment with ZD1839, but not with TRA, produced a significant increase in fragmented DNA in breast carcinoma cells. However, a more pronounced increase in the levels of fragmented DNA was observed following combined treatment with ZD1839 and TRA. CONCLUSIONS: These data suggest that combined treatment with drugs that target EGFR and ErbB-2 might result in an efficient inhibition of tumor growth in those breast carcinoma patients whose tumors co-express both receptors.     

ZD1839 and Cisplatin Alone or in Combination for Treatmentof a Nasopharyngeal Carcinoma Cell Line and Xenografts

This study evaluated the effects of ZD1839, an orally active, selective epidermal growth factor receptor (EGFR)tyrosine kinase inhibitor, on nasopharyngeal carcinoma (NPC) both in vitro and in vivo. Influence of ZD1839alone or combined with cisplatin on the NPC cell line CNE2 was detected by MTT assay with flow cytometryassessment of cell cycle distribution and apoptosis rates. Nude mice NPC xenografts were also used to evaluatethe effects of ZD1839 alone or combined with cisplatin. The Student’s t test evaluated statistical significance.ZD1839 alone or combined with cisplatin inhibited CNE2 cell line proliferation. ZD1839 induced CNE2 cellcycle arrest in the G1 phase, and higher concentrations induced apoptosis. Xenograft tumors were significantlysmaller when treated with 200 mg/kg ZD1839, cisplatin, or cisplatin combined with 100 mg/kg ZD1839 thanuntreated controls. ZD1839 (200 mg/kg) alone showed good tumor inhibition effects, reduction of tumor weights,and smaller tumor volume without loss of body weight. ZD1839 (200 mg/kg) might provide a good and effectivetherapeutic reagent for NPC.