TIP30基因腺病毒载体的构建及体内外抑癌作用

目的 利用缺陷型腺病毒载体表达TIP30基因,观察其体内外抑瘤作用。方法 用Ad-Easy^TM系统,在大肠杆菌同源重组,构建Ad-TIP30腺病毒载体,经在293细胞内成功包装并鉴定后,感染p53基因型不同的肝癌细胞株HepG2(p53-wt)、PLC／PRL／5(p53-mut)和骨肉瘤细胞株Saos-2(p53-null)。用台盼蓝拒染法检测存活细胞,观察TIP30的体外抑瘤作用;用RT-PCR方法检测HepG2细胞p53基因的表达水平;通过裸鼠皮下肝癌移植瘤模型观察Ad-TIP30的体内抑瘤效果。结果 Ad-TIP30对3种肿瘤细胞的增殖均有抑制作用,但对p53基因野生型的肝癌细胞株HepG2抑制作用最明显。经Ad-TIP30感染后,HepG2细胞p53基因表达水平显著升高。Ad-TIP30可显著抑制裸鼠皮下肿瘤的生长,其抑瘤率达62．8％。结论 腺病毒载体表达TIP30基因可通过p53基因依赖性或非依赖性途径抑制肿瘤细胞的增殖,是一种潜在的肿瘤生物治疗手段。     

腺病毒介导p53基因联合胸腺肽治疗腹腔转移癌的实验研究

 目的 评价p53腺病毒注射液与胸腺肽α1（Tα1）联合腹腔给药对腹膜转移癌模型的协同抑制作用。方法 建立H22腹水瘤的昆明小鼠模型，48 h后以p53腺病毒注射液、Tα1等腹腔注射，治疗周期为1周，治疗后测量腹围、体重，计量腹水，计数瘤细胞数，以流式细胞分析检测瘤细胞凋亡、死亡比例及细胞周期。结果 p53腺病毒注射液腹腔局部给药1周，出现瘤细胞G0／G1期阻滞；其和Tα1联用后，未生成腹水的小鼠增多，生成腹水的小鼠的腹水量和瘤细胞数均较单用时明显减少，死亡细胞数明显增高。结论 p53腺病毒注射液可阻滞腹水瘤细胞增生，联合Tα1腹腔给药，对瘤细胞具有协同杀伤作用，抑制腹膜转移癌的发生。     

重组人p53腺病毒逆转非小细胞肺癌顺铂耐药的体外研究

目的 为重组人p53腺病毒应用于临床非小细胞肺癌顺铂耐药患者提供实验依据.方法 采用CCK-8试剂检测半数抑制浓度(IC50);应用流式细胞仪检测细胞周期分布及凋亡发生率;采用功能分类基因芯片检测药物作用前后的基因变化.结果 顺铂联合重组人p53腺病毒后,H1299细胞顺铂的半数抑制浓度下降至5 μg/mL(P<0.05),细胞的凋亡率上升为10.73%(P<0.05).重组人p53腺病毒单药作用后,H1299细胞内p53基因大量表达.在两药联合作用下,导入的p53基因激活了由Fas/Apo-1/CD95系统、TNFR超家族、Bcl-2/Bax等所介导的凋亡通路,同时也上调了部分细胞周期调控基凶.结论 重组人p53腺病毒介导的基因治疗有希望成为治疗临床非小细胞肺癌顺铂耐药患者的一种有效的辅助手段.     

重组人p53腺病毒注射液(rAd/p53)治疗小鼠乳腺癌的实验研究

目的 探讨重组人p53腺病毒注射液(rAd/p53)不同用药方式对荷瘤小鼠乳腺癌的治疗效果.方法 细胞毒性实验,流式细胞术观察rAd/p53对乳腺癌细胞的体外抑制作用及促凋亡作用.建立乳腺癌小鼠模型,不同方式瘤内注射rAd/p53,观察对肿瘤的生长情况的影响,并对肿瘤组织进行免疫组化检查微血管密度(MVD).结果 rAd/p53体内外均可显著抑制乳腺癌细胞Ca761的生长,且早期连续瘤内给药效果好于隔天给药.结论 实验研究提示重组人p53腺病毒注射液治疗乳腺癌是有效的,早期连续用药疗效可能会更佳.     

野生型p53基因转染对卵巢癌细胞生长及药物敏感性影响

目的:探讨野生型p53基因转染对人卵巢癌细胞株SKOV-3的体外生长及裸鼠体内致瘤性抑制作用,并了解p53基因与SKOV-3细胞对顺铂敏感性之间的关系.方法:利用脂质体介导,将含有人野生型p53cDNA的真核表达质粒pCB6-p53导入SKOV-3细胞中,观察该细胞体外生长和裸鼠体内致瘤性改变;应用流式细胞仪检测细胞周期及凋亡情况,MTT法检测细胞药物敏感性改变.结果:免疫组化法证实外源性p53基因在阳性细胞克隆稳定存在;转染野生型p53基因的SKOV-3细胞体外生长速率下降,裸鼠体内致瘤性丧失;G1/G0期细胞百分比(81.5%)和凋亡细胞百分比(11%)增高;p53表达阳性的SKOV-3细胞对顺铂的敏感性明显增强.结论:野生型p53基因转染能使SKOV-3细胞出现生长抑制和对顺铂的化疗敏感性增强.     

腺病毒介导的野生型p53基因对肺腺癌细胞株生长的抑制作用

为研究野生型p53基因对肺腺癌细胞株GLC-82细胞生长的作用,确立腺病毒介导的野生型p53基因在肿瘤治疗中的意义,应用分子克隆技术首先构建了野生型p53复制缺陷型腺病毒重组体,应用生化染色方法确定了重组体的转染效率,以免疫组化法及PCR技术分别确定了腺病毒载体介导的p53基因转染GLC-82细胞后p53蛋白和p53 cDNA的表达情况;最后应用细胞生物学方法检测了p53对GLC-82细胞扩增及细胞周期的影响.结果表明所构建的重组体可以高效、快速转染GLC82细胞,抑制GLC-82细胞扩增,使细胞合成期和分裂后期的量减少,出现细胞凋亡现象:提示野生型p53基因导入可作为治疗肺腺癌的途径之一     

p53反义RNA对人肺癌细胞表型和顺铂敏感性的影响

目的 研究外源p53反义RNA对有p53基因248密码点突变的人肺癌细胞系恶性表型和顺铂敏感性的影响。方法 构建p53反义RNA真核细胞表达载体PEGFP－p53（AS),经酶切图证明反向联结质粒。Lipofectin介导转染有p53基因248密码点突变的人肺癌细胞系801D，经G418筛选获耐受克隆。稀释法建立单细胞克隆系，应用PCR检测外源基因，荧光显微镜检测细胞绿色荧光蛋白表达，p53单抗免疫组化染色检测p53突变蛋白表达，体外集落形成实验检测细胞生长，流式细胞仪检测细胞周期，MTT法检测细胞对顺铂药物敏感性。结果 酶切图证明了p53-cDNA反向联结于质粒，构建了PEGFP－p53(AS),并建立了转染单细胞克隆系PEGFP－p53(AS)-801D及空载细胞系PEGFP－801D。PCR检测外源p53基因和neo基因存在于转染细胞系，而荧光显微镜下发现其胞浆有绿荧光蛋白表达。免疫组化染色p53突变蛋白在801D细胞系为阳性，而PEGFP－p53(AS)-801D为阴性，证明外源反义p53在转染细胞稳定表达并封闭内源突变蛋白表达。与母系相比，PEGFP－p53(AS)-801D集落形成抑制率为61％（P＜0．01），流式细胞检测该细胞系G1期细胞数明显增中，出现G1期阻滞的表现。MTT检测PEGFP－p53(AS）－801D对顺铂比母系更为敏感。结论 有p53基因248密码点突变的801D细胞恶性增殖明显，对顺铂耐药，外源p53反义RNA可封闭突变蛋白表达，抑制细胞体外恶性增殖，增加对顺铂的药物敏感性。转染p53反义RNA可抑制p53突变的恶性表型或恢复野生型p53基因功能。     

野生型p53基因转染对卵巢癌细胞生长及药物敏感性影响

目的：探讨野生型p53基因转染对人卵巢癌细胞株SKOV-3的体外生长及裸鼠体内致瘤性抑制作用。并了解p53基因与SKOV-3细胞对顺铂敏感性之间的关系。方法：利用脂质体介导,将含有人野生型p53cDNA的真核表达质粒pCB6-p53导入SKOV-3细胞中,观察该细胞体外生长和裸鼠体内致瘤性改变;应用流式细胞仪检测细胞周期及凋亡情况,MTT法检测细胞药物敏感性改变。结果：免疫组化法证实外源性p53基因在阳性细胞克隆稳定存在;转染野生型p53基因的SKOV-3细胞体外生长速率下降,裸鼠体内致瘤性丧失;G1/G0期细胞百分比（81.5%)和凋亡细胞百分比（11%）增高;p53表达阳性的SKOV-3细胞对顺铂的敏感性明显增强。结论：野生型p53基因转染能使SKOV-3细胞出现生长抑制和对顺铂的化疗敏感性增强。     

抑癌基因p16INK4a与p53抑制白血病细胞株生长作用的比较

 目的 比较野生型p16INK4a、p53抑癌基因的表达对白血病细胞株K562和HL60的生长抑制。方法 采用脂质体介导野生型p16INK4a、p53抑癌基因转染K562、HL60细胞并进行G418筛选，免疫印渍检测p16INK4a、p53基因的表达，通过细胞生长曲线检测细胞活力，流式细胞仪进行细胞DNA周期分析及细胞凋亡分析，采用联苯胺氧化试验检测K562细胞的分化。结果 转染后p53、p16INK4a在K562及HL60细胞中表达；与对照细胞相比，实验组细胞生长受到明显的抑制，G1期细胞数增加，S期细胞减少。与p16INK4a相比，抑癌基因p53使细胞表达Annexin V增加，显示出更强的致凋亡现象，尤其在HL60细胞株。结论 抑癌基因p16INK4a、p53能有效抑制白血病细胞株的生长，可能更适合复发、难治性白血病的基因治疗。     

经不同途径应用rAdp53对大肠癌裸鼠模型生长抑制差异性的研究

目的:研究经不同途径使用rAdp53对小鼠大肠癌肿瘤模型生长抑制作用的差异性.方法:应用人大肠癌-174细胞株经体外培养传代后,接种到SPF级BALB/c-nu裸鼠皮下,建立大肠癌动物模型;分别经由腹腔、静脉以及瘤内注射rAdp53,动态测量不同使用途径下肿瘤体积及肿瘤重量的变化.结果:经三种不同途径应用rAdp53后,大肠癌动物模型的生长明显较对照组减缓,但腹腔注射组与静脉注射组、瘤内注射组的抑瘤作用有统计学的差异性;同样经三种不同途径给药后,肿瘤模型瘤重抑制率均达50%以上,其中静脉注射组及瘤内注射组高达70%以上,与腹腔注射组有显著统计学差异.结论:经不同途径应用rAdp53均可以抑制大肠癌肿瘤模型的生长,但静脉注射组及瘤内注射组的抑瘤效果较腹腔注射组明显增强.     

Administration of wild-type p53 adenoviral vector synergistically enhances the cytotoxicity of anti-cancer drugs in human lung cancer cells irrespective of the status of p53 gene

Recombinant adenovirus mediated p53 gene transfer combined with anti-cancer drugs has clinical potential for gene therapy of lung cancer. We constructed a recombinant adenoviral vector expressing wild-type p53 cDNA (Ad-p53), and assessed the efficacy of a combined treatment with Ad-p53 and six anti-cancer drugs (cisplatin, 5-fluorouracil, doxorubicin, docetaxel, irinotecan, and etoposide) for human lung cancer cell lines, H1299 (with deleted p53), RERF-LC-OK (with mutant p53), and A549 (with wild-type p53). The infection of the Ad-p53 vector into H1299 cells, RERF-LC-OK cells, or A549 cells increased the sensitivity to all six drugs regardless of the cellular p53 status, and a synergism was observed by the isobolic method in combination studies (D<1). We conclude that our strategy using adenoviral mediated p53 gene transfer to cancer cells can enhance the cytotoxic effect of anti-cancer drugs, which leading to an improvement of lung cancer chemotherapy.     

重组腺病毒p53基因治疗肝癌研究进展

目的：探讨重组腺病毒p53基因（recombinant humanAd—p53,rAd—p53）治疗肝癌的抗肿瘤机制及临床应用。方法：应用PubMed、万方和CNKI数据库,以“肝癌、重组腺病毒p53基因、基因治疗、实验研究和临床应用”为关键词,检索1994—06—01—2013—11—31文献739篇,纳入标准：1）p53基因与肝癌发生的相关性;2）重组腺病毒p53基因抗肿瘤机制;3）重组腺病毒p53治疗肝癌的实验研究;4）重组腺病毒p53治疗肝癌的临床应用研究。根据纳入标准选择符合分析的文献36篇。结果：p53基因是公认的肿瘤抑制基因,具有促使肿瘤细胞自杀和帮助缺陷细胞修复的作用。rAd—p53是复制缺陷型5型腺病毒载体与人p53基因重组的肿瘤基因治疗制品。rAd-p53通过多种途径发挥抗肿瘤作用,包括使肿瘤的细胞周期阻滞和发生程序性死亡,促进放射线对肿瘤细胞引起的细胞周期阻滞和凋亡,刺激机体产生抗肿瘤免疫反应,抑制肿瘤血管内皮生长因子,控制肿瘤的血管生成,使注射部位瘤组织产生局部血供障碍和坏死。此外,还能增加肝癌细胞的放化疗敏感性,间接增强抗肿瘤疗效。rAd-p53基因疗法为肝癌治疗开辟了崭新的途径,多项-l盘床研究疗效良好。结论：rAd—p53基因对肿瘤的作用机制体现了在抗肿瘤治疗方面的有效性,并在基础研究及临床应用中均取得了显著进展,再肝癌的防治中将取得更大的突破。     

The evaluation of gastric cancer sensitivity to 5-FU/CDDP in terms of induction of apoptosis: time- and p53 expression-dependency of anti-cancer drugs

Clinical in vivo and in vitro studies have revealed pronounced gastric cancer activity using the combination of 5-fluorouracil (5-FU) and cisplatin (CDDP). In addition, the combination of 5-fluorouracil plus cisplatin (FP treatment) possesses synergistic cytotoxicity against gastric cancer. Sensitivity of two gastric cancer cell lines to anti-cancer drugs, 5-fluorouracil (5-FU) and/or cisplatinum (CDDP), was evaluated by use of either flow cytometric analysis (FACS) or morphological observation in terms of induction of apoptosis. In morphological observation, a new experimental technique was used in which cancer cells were distributed in thin collagen gel as one or two cell layers, and cultured with anti-cancer drugs. Thereafter, cells were stained with fluorescent Hoechst 33258 (Ho) and photographed, then stained with hematoxylin and eosin (H&E) and photographed again. Cell death patterns were determined by combining observations of Ho- and H&E-stained cells. While combined administration of 5-FU and CDDP did not induce apoptosis of MKN-28 (mutant-type p53), apoptotic cells were markedly observed in the case of MKN45 (wild-type p53). In addition, consecutive administration of CDDP for 3 h and 5-FU for 21 h effectively induced apoptosis of MKN45. These results indicated that the type of p53 expression in cancer cells could be a promising factor in predicting response to FP therapy and the administration of CDDP prior to 5-FU may be more effective in inducing apoptosis of gastric cancer cells with wild-type p53 expression. These data may provide evidence to support the idea that p53 expression is related to multidrug resistance (MDR) in FP therapy of gastric cancer cell lines.     

重组人p53腺病毒注射液联合顺铂治疗肺癌所致胸腔积液的临床研究

背景与目的：肿瘤抑制基因p53是目前研究最为广泛和系统的抑癌基因之一,p53基因突变或缺失导致肿瘤的形成。本研究评价重组人p53腺病毒注射液（rAd-p53）导入野生型p53基因抑癌基因治疗同时联合顺铂治疗肺癌所致胸腔积液的临床疗效和毒副反应。方法：将35例肺癌合并胸腔积液患者随机分为联合组和单药组两组。所有患者应用长春瑞滨25mg/m2静脉点滴,第1、8天,每3周重复一次。前述治疗基础上,联合组胸腔内灌入rAd-p531×10^12VP和顺铂注射液40mg/m2;单药组胸腔内灌入顺铂注射液40mg/m2,每周重复一次,连用4次后观察疗效。结果：联合组和单药组的有效率分别为82.35%和50.00%（P〈0.05）;联合组和单药组的一般状况改善率分别为64.70%和33.33%（P〈0.05）;两组患者主要不良反应为发热、胸痛、消化道反应及白细胞减少,联合组发热的发生率高于单药组（P〈0.05）,主要为自限性发热,36h后自行恢复正常。结论：重组人p53腺病毒注射液联合顺铂治疗肺癌所致胸腔积液疗效确切,且毒副反应较低,值得临床推广应用。     

Expression of p53 protein as a predictor of the response to 5-fluorouracil and cisplatin chemotherapy in human gastrointestinal cancer cell lines evaluated with apoptosis by use of thin layer collagen gel

Apoptosis of the target cells is an important index in the assessment of the efficacy of cancer chemotherapy. We previously established a new experimental technique in which cancer cells are distributed in thin collagen gel as one or two cell layers, and cultured with anti-cancer drugs. The cells are stained with fluorescent Hoechst 33258 (Ho) and photographed, then with hematoxylin and eosin (H&E) and again photographed. The results show that most cell death patterns can be determined by combining observations of Ho and H&E-stained cells without the necessity for judging the apoptosis by electron microscopy. 5-fluorouracil (5-FU) and cisplatin (CDDP) are important anti-cancer drugs in the treatment of a variety of cancers. 5-FU or CDDP alone have shown significant effects in the treatment of gastric and colon cancers, and in addition, it has been shown that the combination of 5-FU plus CDDP (FP) therapy produces synergism greater than 5-FU or CDDP alone in gastrointestinal cancer. In this study, we evaluated the efficacy and toxicity of FP therapy in the gastric cancer cell lines MKN45, MKN28, and KATOIII and the colon cancer cell lines HCT116 and COLO320, and examined the relationship between the response to FP therapy and apoptosis. Additionally, we performed transfection of normal p53 gene into p53 mutant MKN28 cells and analyzed the impact of the p53 gene on a sensitivity test. Wild-type p53 in MKN45, HCT116, and COLO320 cells underwent significantly (p<0.01) more apoptosis than MKN28 and KATOIII cells possessing p53 mutant- and deficient-type, respectively, in FP therapy. Transfection of p53 to MKN28 cells resulted in a significantly (p<0.01) higher apoptotic index. From these results, we conclude that the p53 pathway allows induction of apoptosis in gastrointestinal cancers in FP therapy treatment, and that identification of the p53 type of a patient's cancer can be used to predict the success of FP therapy.     

The Effect of the MDM2-p53 Loop on the Sensitivity of Ovarian Cancer Cells to Cisplatin

OBJECTIVE To explore whether MDM2 transfection can alter the MDM2-p53 autoregulatory feedback loop so as to change the sensitivity of ovarian cancer cell lines to cisplatin. METHODS The ovarian cancer cell line A2780 expressing wild-type P53 and the ovarian cancer cell line SKOV-3 with the p53 null type were stably transfected with pCMV-MDM2 or pCMV as a control. The blocked expression of P53 was determined by Western blots. Cytotoxicity was assessed using the MTT assay and the trypan blue exclusion assay. Flow cytometry was used to detect changes in the cell cycle and removal of platinum -DNA adducts was measured by atomic absorption spec-troscopy. RESULTS (1) Parental A2780 and A2780-V cells (IC50= 15.14±1.39 μmol) have similar cisplatin sensitivities, whereas sensitivity to cisplatin in A2780-M cells (IC50=7.98±1.32 μmol) was 2 to 3 fold greater (P=0.001). The trypan blue exclusion assay demonstrated that cisplatin killed a higher percentage of A2780-M cells compared to A2780-V cells. There was no significant change following MDM2 transfection in SKOV-3 cells. (2) After cisplatin treatment, A2780-M cells showed a pronounced S-phase arrest, however, A2780 cells with the intact wild-type P53, arrested primarily at the G2/M transition. (3) Platinum uptake was similar for all of the A2780 cell lines after ciaplatin treatment, but the removal of plat-inum-DNA adducts was reduced in the A2780-M cells compared with A2780-V cells. CONCLUSION MDM2 increases cisplatin cytotoxicity in ovarian cancer cells by blocking the expression of p53 through the MDM2-p53 autoregulatory feedback loop.     

应用ATP生物荧光肿瘤体外药敏检测技术研究大肠癌药敏的异质性

目的探讨用ATP生物荧光肿瘤体外药敏检测技术(ATP-TCA)研究大肠癌药敏的异质性和个体化疗的可行性.方法用ATP-TCA检测58例大肠癌标本对16种单药或联合用药的敏感性.结果个体之间的药物敏感性存在着明显的异质性.单药中最有效的药物为长春瑞滨、羟基喜树碱、氟尿嘧啶和紫杉醇.联合用药最有效的是氟尿嘧啶 丝裂霉素 阿糖胞苷,91.6%(11/12)的标本对其敏感,其次是氟尿嘧啶 顺铂 阿霉素,健择 顺铂和5-FU氟尿嘧啶 长春新碱 卡氮芥.结论大肠癌对抗癌药物的敏感程度存在着异质性.ATP生物荧光肿瘤药敏检测技术可用于为大肠癌选择合适的化疗药物.     

重组人类p53腺病毒联合同步放化疗治疗中晚期子宫颈鳞状细胞癌的临床观察

 目的　探讨重组人类p53腺病毒（rAd-p53）瘤内注射联合同步放化疗治疗中晚期子宫颈癌患者的近期疗效及安全性。方法　将21例确诊中晚期子宫颈鳞状细胞癌的患者,随机分为两组,治疗组（10例）行rAd-p53瘤内注射+同步放化疗,对照组（11例）仅行同步放化疗,比较两组治疗结束时患者的近期疗效及主要不良反应。结果　治疗组 完全缓解（CR）2例,部分缓解（PR）6例,稳定（SD）2例,总有效率 80 %;对照组 PR 3 例,SD 6例,进展（PD）2例,总有效率 27.3 %,治疗组和对照组疗效差异有统计学意义（t＝76.00,P＜0.05）,rAd-p53的药物毒副作用主要是自限性发热,两组骨髓抑制反应的发生率差异无统计学意义（t＝119.50,P＞0.05）。结论　rAd-p53瘤内注射在中晚期子宫颈癌的同步放化疗中具有增效作用,rAd-p53瘤内注射是安全有效并方便的治疗手段。     

Relationship of P-glycoprotein and p53 protein to chemosensitivity in colorectal cancer

Background Resistance of tumors to chemotherapeutic agents is a major problem in cancer treatment. Recent advances in molecular biology have shown a role for oncogenes in this resistance. Methods We determined the positive or negative expression of P-glycoprotein and mutant p53 protein by immunohistochemistry on 101 human colorectal cancer and correlated the expression of these proteins with the chemosensitivity of the tumors to various anticancer agents using the succinate dehydrogenase inhibition (SDI) test. Results Fifty-five (54.5%) of 101 tumors expressed P-glycoprotein and 53 (52.5%) expressed a mutant p53 protein. Thirty-seven of 55 tumors positive for P-glycoprotein also expressed a mutant p53 protein. The association between the coexpression of P-glycoprotein and p53 protein was statistically significant (P=0.001). Neither the expression of P-glycoprotein nor p53 protein affected the chemosensitivity of the tumor to doxorubicin hydrochloride, aclarubicin hydrochloride, pirarubicin, epirubicin hydrochloride, mitomycin C, 5-fluorouracil, cisplatin, carboplatin, or etoposide. However, a positive correlation was found between the control optical density and chemosensitivity in the P-glycoprotein or mutant p53 protein negative tumors. Oppositely, some P-glycoprotein or mutant p53 protein positive tumors showed low chemosensitivity in spite of their high control optical density. Conclusions A highly statistically significant coexpression of P-glycoprotein and mutant p53 protein was found in colorectal cancer. Furthermore, differences in cell growth between the tumor samples indicate the possibility that the expression of P-glycoprotein and mutant p53 protein in colorectal cancer tumors could be associated with chemoresistance.     

Cisplatin sensitivity/resistance in UV repair-deficient Chinese hamster ovary cells of complementation groups 1 and 3

We assessed the possible role of the human repair genes, ERCC1and ERCC3, in resistance to cisplatin-induced cytotoxicity.The UV repair-deficient Chinese hamster ovary (CHO) 43:3B [designatedERCC1(–)] cell line and its paired subline 83-J5, whichis stably transfected with the human DNA excision repair geneERCC1 [designated ERCC1(+)], were used in this study. UV repair-deficientCHO 27-1 cells [designated ERCC3(–)] and its paired sublinedesignated ‘ERCC3(+)’, which is stably transfectedwith the human DNA excislon repair gene ERCC3, were also used.In each pair of cell lines, we assessed cisplatin cytotoxicity,cellular drug accumulation and platinum-DNA adduct repair after1h drug exposures. Drug accumulation and DNA repair were assessedby atomic absorption spectrometry with Zeeman background correction.ERCC1(+) cells (IC₅₀ = 4.0 µM) were 5-fold more resistantto cisplatin than ERCC1(–) cells (IC₅₀ = 0.75 µM).ERCC1(+) cells repaired 25% of DNA lesions in cellular DNA withina 6 h time period following an IC₅₀ drug exposure and repaired48% over 24 h. No DNA repair was observed in ERCC1(–)cells during the same time periods. Both cell lines showed similarpatterns of drug accumulation. For ERCC3(–) cells (IC₅₀= 54 µM) and ERCC3(+) cells (IC₅₀ = 49 µM), theprofiles of cisplatin sensitivity and cellular drug accumulationwere similar. When treated with 50 µM cisplatin, thesecells showed similar patterns of drug accumulation, and wereequally efficient at forming and repairing lesions in cellularDNA. These data show that in UV repair-deficient CHO cells,ERCC1 confers resistance to cisplatin and confers the abilityto remove platinum from cellular DNA. In contrast, ERCC3 doesnot influence cisplatin drug sensitivity or adduct repair capability.This suggests that ERCC1 may be a determinant of cisplatin resistance,whereas ERCC3 is probably not.