卵巢癌细胞多药耐药中miR-193a-3p的表达及作用

目的探讨在卵巢癌细胞多药耐药中miR-193a-3p的表达及其作用。方法采用MTT法分析卵巢癌细胞系A2780、SKOV-3、HO8910和ES-2对5种化疗药物的敏感性,确定其半数抑制浓度(IC_(50))值;用定量实时PCR(qRT-PCR)方法检测miR-193a-3p;转染miR-193a-3p mimic于最低表达miR-193a-3p的相对多药最敏感的卵巢癌细胞系ES-2中,用qRT-PCR方法检测转染效率;用MTT方法在转染后相对多药最敏感的卵巢癌细胞系ES-2中检测其对上述化疗药物敏感性的差异。结果在相对多药最敏感的卵巢癌细胞系ES-2中miR-193a-3p的表达最低,而在相对多药最耐药的卵巢癌细胞系SKOV-3中miR-193a-3p的表达最高(P0.01);转染miR-193a-3p mimic于相对多药最敏感的卵巢癌细胞系ES-2中后,使其增加对(紫杉醇,卡铂,多西他赛)化疗药物的耐受性(P0.01)。结论卵巢癌细胞多药耐药的调控中可能有miR-193a-3p的参与。     

用基因芯片筛选乳腺癌细胞耐药相关基因

摘要：目的：通过挖掘基因芯片数据,识别可能与乳腺癌细胞耐药相关的基因。 方法：从基因表达数据库（Gene Expression Omnibus,GEO）中下载编号为GSE28784基因芯片数据,分析乳腺癌敏感细胞系MDA-MB-231/S和多西紫杉醇耐药细胞系MDA-MB-231/Doc中基因表达差异,获得差异表达基因,并对这些基因进行生物信息学分析。 结果：得到639个表达差异的基因,与敏感细胞系相比,分别有220和419个基因在耐药细胞系中表达下调或上调;这些基因主要参与调控细胞死亡、凋亡、迁移和免疫效应等过程;表皮生长因子受体（EGFR）、JUN、白介素6（IL-6）、蛋白酪氨酸激酶2（PTK2）和多药耐药蛋白1（ABCB1）等已知与耐药相关的基因可能参与了乳腺癌细胞对多西紫杉醇的耐药。 结论：基因芯片数据的挖掘为进一步研究乳腺癌细胞的耐药机制提供了方向。     

葡萄糖神经酰胺合酶与白血病细胞耐药的关系

本研究旨在观察葡萄糖神经酰胺合酶（glucosylceramide synthase，GCS）基因及其蛋白在人白血病细胞的表达及其与肿瘤多药耐药的关系。首先以β—actin基因为内参照物，采用RT—PCR方法分析了53例耐药／非耐药白血病患者外周血标本，并对药物敏感的HL-60细胞株和对阿霉素耐药的HL-60／ADR细胞株中GCS基因的表达水平进行检测，同时与多药耐药基因（mdr1）的表达进行比较。继而采用Western blot法分析HL-60细胞株及HL-60／ADR细胞株中GCS蛋白及P-gP蛋白的表达情况。结果表明：白血病患者耐药组临床标本中的GCS基因扩增条带光密度相对比值明显高于非耐药组（P〈0．05），且GCS基因扩增条带光密度值显著增强时往往伴有mdr1基因的高表达，两者呈正相关（P〈0．01、r=0．6）。HL-60／ADR细胞株GCSmRNA及蛋白均过度表达，且明显高于HL-60细胞株，与此同时，HL-60／ADR细胞株的mdr1mRNA和P-gP的表达亦显著增高。结论：GCS可能在白血病多药耐药中起着重要作用。     

亚致死量陡脉冲调节人卵巢癌细胞多药耐药的实验研究

目的研究亚致死量陡脉冲对人卵巢癌多药耐药细胞亚株的杀伤及对多药耐药性的调节，并探讨其可能的作用机制。方法以人卵巢癌细胞亲本株（SKOV3）及多药耐药亚株（SKOV3／ADM）为研究对象，采用60Hz陡脉冲电击处理，甲基噻唑基四唑（MTT）法检测两株细胞的电敏感性及化疗敏感性；逆转录一多聚酶链反应（RT—PCR）法检测耐药亚株中的多药耐药基因（MDR1）mRNA水平，免疫细胞化学法检测其P糖蛋白（P—gP）表达，用透射电镜观察超微结构的改变。结果SKOV3亲本及耐药亚株对陡脉冲电场的电敏感性相近（P=0．642）；亚致死量脉冲处理后的耐药亚株出现：化疗敏感性增强，半效抑制浓度（IC50）值及耐药指数（RI）均减低，MDR1 mRNA水平无显著改变（P=0．947），P—gP蛋白表达强度显著减弱（P=0．001），细胞出现凋亡改变。结论陡脉冲对SKOV3多药耐药亚株亦可有效杀伤；亚致死量陡脉冲可逆转多药耐药，其可能的机制为增加膜渗透性的同时亦可能诱导并持久改变了耐药相关蛋白的正常构象与功能。     

热化疗联合对人肺腺癌耐药细胞株A549／DDP作用及其机制的实验研究

目的 观察热化疗联合对人肺腺癌耐药细胞株A549／DDP的影响及其机制，为临床上应用热化疗联合治疗非小细胞肺癌提供理论依据。方法 CCK-8法检测A549、不同温度下A549／DDP细胞对顺铂的敏感性；流式细胞仪分析热疗对A549／DDP细胞周期分布的影响；RT-PCR检测热疗对A549／DDP细胞ERCC1表达的影响。结果 亲代人肺腺癌细胞株A549对顺铂的敏感性明显高于耐药细胞株ASg9／DDP，不同温度加热后A549／DDP细胞对顺铂的敏感性均有提高；热疗尤其是热化疗后G2／M期细胞明显增多，G0／G1期细胞明显减少（P〈0．01）；热疗后A549／DDP细胞ERCC1mRNA表达未见明显改变。结论 热疗能提高人肺腺癌耐药细胞株A549／DDP对顺铂的敏感性，热化疗具有协同作用。热化疗协同作用机制可能主要是诱导细胞周期阻滞，抑制细胞增殖，和DNA修复基因ERCC无直接相关性。     

紫杉醇耐药人肺腺癌细胞系的建立及生物学活性

目的：体外建立紫杉醇耐药人肺腺癌A549/TAX细胞系,并对其生物学特性进行研究.方法：采用逐步增加紫杉醇浓度结合低剂量持续诱导法,建立紫杉醇耐药人肺腺癌A549/TAX细胞系.MT T法描绘A549和A549/TAX细胞的生长曲线;流式细胞仪检测细胞周期并比较经紫杉醇诱导24 h后A549和A549/TAX细胞平均凋亡率的差异;检测紫杉醇对A549/TAX细胞的半数抑制浓度、耐药系数（RI）及A549/TAX细胞对其他 5种化疗药物（顺铂、长春新碱、表阿霉素、足叶乙甙及吉西他滨）的交叉耐药谱;RT-PCR半定量分析A549/TAX细胞凋亡基因（bcl-2）及耐药基因（MDR1、LRP、GST-π）的mRNA表达.结果：A549/TAX细胞生长较亲本细胞快,S期细胞增多[（51.61±0.48）%],G1 期减少[（37.26±0.23）%],经紫杉醇（150 μmol/L）诱导前后平均凋亡率差异与A549细胞相比差异有显著性.A549/TAX细胞对紫杉醇、长春新碱、表阿霉素及足叶乙甙的RI分别为 21.3、12.91、5.88和4.79,而对顺铂（RI=1.06）和吉西他滨（RI=1.03）则无交叉耐药;A549/TAX细胞bcl-2、 MDR1、LRP mRNA的表达均较亲本细胞显著增高（P＜0.001）,GST-πmRNA未见表达.结论：成功建立了紫杉醇耐药A549/TAX细胞系,该细胞抗药性能明显、稳定,推测其多药耐药性与bcl-2、MDR1和LRP高表达有关.     

凋亡相关基因Bcl—XL、Bax表达与人卵巢癌细胞辐照凋亡效应的相关性研究

目的：探讨60Coγ射线作用下人卵巢癌细胞株A2780及其顺铂耐药株A2780－cp凋亡相关基因Bcl-XL、Bax的表达及在辐照凋亡效应中作用。方法：分别运用流式细胞技术（FCM）及RT－PCR方法，分析A2780－A2780－cp中Bcl-XL、Bax转录的相对表达与辐照诱导的细胞凋亡率的关系。结果：A2780－cp细胞较其亲本株A2780细胞有较高水平的Bcl-XL表达；辐照后2h两者呈现不同程度的Bcl-XL、Bax的转录增加及Bcl-XL/Bax比率变化。结论：不同p53基因状态卵巢癌细胞对辐照诱导的凋亡敏感性与肿瘤细胞的Bcl-XL、Bax表达及二者的比率有关。     

成人急性白血病患者细胞周期蛋白A基因表达与耐药的关系

目的 探讨细胞周期蛋白A（cyclin A)基因在成人急性白血病（AL）患者中的表达以及与耐药的关系。方法 采用半定量RT－PCR技术对32例多药耐药和32例化疗敏感的AL患者和20名正常人进行细胞周期蛋白A、mdr1、TopoⅡα、bcl-2 mRNA水平的测定。结果 耐药组患者细胞周期蛋白A及TopoⅡα mRNA的表达水平均明显低于敏感组患者（P＜0．01），20名正常人在同一实验条件下未检出细胞周期蛋白A mRNA的表达；耐药组患者mdrl及bcl-2 mRNA表达水平均明显高于敏感组（P＜0．01）；64例AL患者中，细胞周期蛋白A与TopoⅡα表达水平呈高度的正相关（r=0.794,P=0.000)；细胞周期蛋白A与TopoⅡα同时阳性低表达的10例AL患者全部耐药；经Binary逻辑回归分析显示细胞周期蛋白A与耐药显著相关。结论 细胞周期蛋白A可能会成为判断AL患者预后的新指标，联合TopoⅡα检测对判断AL耐药有意义。     

K562/A02耐药细胞NF-κB活性测定及葛根素部分逆转耐药效应的初步研究

白血病细胞的多药耐药（MDR）的产生是导致化疗失败的主要原因。目前发现MDR的产生机制是多因素的，且有不同的耐药表型。核转录因子KappaB（NF—κB）在细胞增殖和凋亡中起关键调控作用。为明确NF—κB是否与细胞MDR产生有关及葛根素是否通过抑制NF—κB活性而逆转耐药，我们观察了慢性粒细胞白血病急变细胞株K562及其耐药细胞株K562／A02的NF—κB活性，P糖蛋白（P—gP）、耐药相关蛋白（MRP）表达情况，以及葛根素干预前后NF—κB活性，P—gP、MRP表达的变化，为揭示白血病细胞耐药机制，寻求有效的逆转耐药药物提供实验依据。     

Acquired cisplatin resistance in human ovarian cancer cells is associated with enhanced repair of cisplatin-DNA lesions and reduced drug accumulation.

Studies were undertaken to investigate acquired resistance to cisplatin in human ovarian cancer cells. The cell lines A2780 and A2780/CP70 were studied to assess their respective characteristics of drug accumulation and efflux, cytosolic inactivation of drug, and DNA repair. All experiments were performed using 1-h drug exposures. The A2780/CP70 cell line was 13-fold more resistant to cisplatin than A2780 cells. When studied at their respective IC50 doses, drug accumulation rates were similar for the two cell lines. However, the resistant cell line was twofold more efficient at effluxing drug, which was associated with reduced total drug accumulation for equivalent micromolar drug exposures. At equivalent levels of total cellular drug accumulation, the two cell lines formed the same levels of cisplatin-DNA damage, suggesting that cytosolic inactivation of drug does not contribute to the differential in resistance between these cell lines. Resistant cells were also twofold more efficient at repairing cisplatin-DNA lesions in cellular DNA and in transfected plasmid DNA. We conclude that in these paired cell lines, alterations in drug uptake/efflux and in DNA repair are the major contributing factors to acquired resistance to cisplatin.     

Trichostatin A up-regulates p73 and induces Bax-dependent apoptosis in cisplatin-resistant ovarian cancer cells

Several studies in the last years evidenced that deregulation of proapoptotic and antiapoptotic pathways are key players in the onset and maintenance of chemoresistance in advanced ovarian cancers. To characterize the signaling events and molecules involved in the acquisition of cisplatin resistance, we used the human ovarian cancer cell line A2780 and its derivative cisplatin-resistant subline A2780 CIS. We found that the mitochondrial intrinsic apoptotic pathway, induced by cis-dichlorodiammineplatinum (CDDP) in A2780 wild-type cells, was compromised in the resistant subline CIS. The analysis of expression of proteins involved in mitochondria-dependent apoptosis revealed a role of Bax and p73 but not p53. Indeed, we found that CDDP treatment induced the up-regulation of p53 in both sensitive and resistant A2780 cell lines. By contrast, p73 and Bax expressions were compromised in resistant cells. Pretreatment of resistant A2780 CIS cells with the histone deacetylase inhibitor trichostatin A overcomes apoptosis resistance to CDDP by restoring both p73 and Bax but not p53 expression. Altogether, these data indicate that p73, but not p53, is involved in the regulation of apoptosis susceptibility to cisplatin in A2780 ovarian cancer cells and evidence a key contribution of histone deacetylase activation in the acquisition of chemotherapy resistance in human ovarian cancer cells.     

Histone deacetylase inhibitors induce G2-checkpoint arrest and apoptosis in cisplatinum-resistant ovarian cancer cells associated with overexpression of the Bcl-2-related protein Bad

Trichostatin A produces predominantly G(1) cell-cycle blockade and differentiation of the cisplatinum-sensitive A2780 ovarian cancer cell line. Given the propensity of ovarian tumors to become resistant to cisplatinum, often leading to cross-resistance to other agents, we have extended these observations by examining how the emergence of resistant phenotypes in A2780 cells affects the actions of histone deacetylase (HDAC) inhibitors. Trichostatin A exposure (100 ng/mL, 24 hours) induced ultrastructural differentiation of the "intrinsically" cisplatinum-resistant A2780-9M subline, with the reappearance of intercellular junctions and lumina containing primitive microvilli. Similar trichostatin A exposure in the acquired resistance A2780CP cells produced minimal differentiation consisting of occasional weak intercellular junctions. Independent of the differences in trichostatin A-induced differentiation, in both resistant sublines trichostatin A produced a similar reduction in cell viability, by >90%, within 5 days of treatment. Diminished viability in both A2780-9M and CP cells was associated with the absence of cell cycle arrest in G1, resulting in predominant G2-checkpoint arrest accompanied by a 10- to 20-fold increase in Annexin V binding and the reemergence of apoptosis. Similar cell cycle arrests and apoptosis were also observed using other HDAC inhibitors and in other resistant ovarian cancer cell lines (OVCAR-3 and SK-OV-3). Trichostatin A-induced apoptosis in resistant cells is in sharp contrast to its effects on the parental cisplatinum-sensitive A2780 and normal MRC-5 fibroblast cell lines (predominant cycle arrest in G1 with no detectable apoptosis). Western immunoblot analysis indicated trichostatin A triggers apoptosis in resistant ovarian cancer cells via p53-independent activation of the intrinsic "mitochondrial" pathway, commensurate with induction of the Bcl-2-related protein Bad. These results suggest cisplatinum resistance alters the effects of HDAC inhibition through a shift in cell cycle arrest from the G1 to the G2 checkpoint and reactivation of the intrinsic mitochondrial apoptotic cascade.     

TF-FⅦa复合物影响人卵巢癌细胞尿激酶型纤溶酶原激活物受体mRNA表达的研究

目的克隆人组织因子(TF),研究组织因子-活化凝血因子Ⅶ复合物(TF-FⅦa)对人卵巢癌细胞内尿激酶型纤溶酶原激活物(u-PA)及其受体(u-PAR)mRNA表达的影响,探讨该复合物在肿瘤浸润、转移中的作用机制.方法采用分子克隆技术构建人TF真核表达载体pcDNA3-TFcDNA;以脂质体介导转染人卵巢癌细胞系A2780,筛选稳定表达的转染细胞A2780-TF.以FⅦa分别刺激A2780细胞和A2780-TF细胞,采用RT-PCR方法检测细胞内u-PA及u-PAR mRNA水平变化.结果①构建产物经基因测序证实为pcDNA3-TFcDNA重组体;②转染细胞A2780-TF内TF-mRNA水平显著增高转染细胞为3.91±0.28,未转染细胞为0.97±0.23(P<0.01);转染细胞表面TF表达显著增高转染细胞为(48.56±9.53)%,未转染细胞为(2.73±1.15)%(P<0.01);③FⅦa刺激对A2780细胞内u-PA、u-PAR mRNA水平均无显著影响;④FⅦa呈浓度依赖性诱导A2780-TF细胞内u-PAR mRMA水平增高,而不影响u-PA mRNA水平;FⅦa刺激A2780-TF细胞内u-PAR mRNA水平增高的作用具有一定的时相性;⑤抗TF单抗可阻断FⅦa诱导A2780-TF细胞内u-PAR mRNA转录的作用.结论 TF通过与FⅦa形成复合物而上调人卵巢癌细胞内u-PAR mRNA的表达,可能藉此增强肿瘤侵袭及转移作用.     

Bcl-2 down-regulation and tubulin subtype composition are involved in resistance of ovarian cancer cells to vinflunine

Vinflunine, a new microtubule-targeting drug, has a marked antitumor activity in vitro and in vivo. Here, we studied the mechanisms mediating resistance to vinflunine. We investigated the response to vinflunine of ovarian cancer cells initially selected as paclitaxel-resistant cells (A2780-TC1 cells). By comparison with A2780-wild-type (wt) cells, we showed that A2780-TC1 cells were highly resistant to vinflunine, with resistance factors reaching 800 and 1,830 for IC(50) and IC(70), respectively. We showed that P-glycoprotein minimally participated in this cell resistance. The examination of tubulin composition revealed increased levels of acetylated alpha-tubulin, betaII-tubulin, and betaIII-tubulin in A2780-TC1 cells before vinflunine treatment. As a consequence, vinflunine unequally affected microtubule network organization and function in A2780-wt and A2780-TC1 cells. Whereas the drug depolymerized microtubules and induced a mitotic block in A2780-wt cells, it did not depolymerize microtubules and induced a G(2) block in A2780-TC1 cells. Elsewhere, the mitochondrial protein Bcl-2 was down-regulated in A2780-TC1 cells. This down-regulation was related to resistance, as A2780-TC1 cells stably transfected with a Bcl-2 construct recovered a partial sensitivity to vinflunine. Lastly, we confirmed the role played by Bcl-2 by showing that the mitochondrial membrane potential was only disrupted by vinflunine in cells expressing Bcl-2. Altogether, our results indicate that modifications acquired during treatment (i.e., paclitaxel) have significant consequences on cell response to the following drug (i.e., vinflunine). Especially, this study shows that a specific pool of tubulin subtypes and a down-regulation of Bcl-2 are associated with resistance of ovarian cancer cells to vinflunine.     

Chronic exposure to HPMA copolymer-bound adriamycin does not induce multidrug resistance in a human ovarian carcinoma cell line.

The influence of free and N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-bound adriamycin (ADR) on the induction of multidrug resistance in the A2780 human ovarian carcinoma cell line was studied in vitro. It was found that chronic exposure to free ADR led to an increase in resistance to ADR and Taxol and overexpression of the MDR1 gene. No significant changes in the expression of the MRP gene were found during adaptation to free ADR. In addition to MDR1 gene-encoded multidrug resistance, a significant increase in the resistance against ADR was found before the overexpression of the MDR1 gene was measurable. This non-P-glycoprotein resistance does not appear to be connected with MRP gene-encoded resistance. During adaptation to free ADR, changes in cellular metabolism such as increased rate of glucose uptake, oxidation and glycolysis were detected. Adapted sensitive A2780 cells expressed the MDR1 gene and possessed almost the same decreased sensitivity toward ADR as the ADR-resistant human ovarian carcinoma A2780/AD cells. However, they significantly differed in proliferation rate, cellular metabolism and MRP gene expression. On the contrary, multidrug resistance was not induced after repeated exposure of sensitive A2780 cells to HPMA copolymer-bound adriamycin. The cells did not express the MDR1 gene, the expression of the MRP gene was partially inhibited, and the resistance against Taxol was decreased. Differences were also observed in metabolic changes. In summary, the data indicate that, contrary to free ADR, HPMA copolymer-bound ADR does not induce multidrug resistance in A2780 cell culture after repeated exposure.     

Smoothened antagonists reverse taxane resistance in ovarian cancer

The hedgehog pathway has been implicated in the formation and maintenance of a variety of malignancies, including ovarian cancer; however, it is unknown whether hedgehog signaling is involved in ovarian cancer chemoresistance. The goal of this study was to determine the effects of antagonizing the hedgehog receptor, Smoothened (Smo), on chemotherapy response in ovarian cancer. Expression of hedgehog pathway members was assessed in three pairs of parental and chemotherapy-resistant ovarian cancer cell lines (A2780ip2/A2780cp20, SKOV3ip1/SKOV3TRip2, HeyA8/HeyA8MDR) using quantitative PCR and Western blot analysis. Cell lines were exposed to increasing concentrations of two different Smo antagonists (cyclopamine, LDE225) alone and in combination with carboplatin or paclitaxel. Selective knockdown of Smo, Gli1, or Gli2 was achieved using siRNA constructs. Cell viability was assessed by MTT assay. A2780cp20 and SKOV3TRip2 orthotopic xenografts were treated with vehicle, LDE225, paclitaxel, or combination therapy. Chemoresistant cell lines showed higher expression (>2-fold, P < 0.05) of hedgehog signaling components compared with their respective parental lines. Smo antagonists sensitized chemotherapy-resistant cell lines to paclitaxel, but not to carboplatin. LDE225 treatment also increased sensitivity of ALDH-positive cells to paclitaxel. A2780cp20 and SKOV3TRip2 xenografts treated with combined LDE225 and paclitaxel had significantly less tumor burden than those treated with vehicle or either agent alone. Increased taxane sensitivity seems to be mediated by a decrease in P-glycoprotein (MDR1) expression. Selective knockdown of Smo, Gli1, or Gli2 all increased taxane sensitivity. Smo antagonists reverse taxane resistance in chemoresistant ovarian cancer models, suggesting combined anti-hedgehog and chemotherapies could provide a useful therapeutic strategy for ovarian cancer.     

Targeting aldehyde dehydrogenase cancer stem cells in ovarian cancer

Aldehyde dehydrogenase-1A1 (ALDH1A1) expression characterizes a subpopulation of cells with tumor-initiating or cancer stem cell properties in several malignancies. Our goal was to characterize the phenotype of ALDH1A1-positive ovarian cancer cells and examine the biological effects of ALDH1A1 gene silencing. In our analysis of multiple ovarian cancer cell lines, we found that ALDH1A1 expression and activity was significantly higher in taxane- and platinum-resistant cell lines. In patient samples, 72.9% of ovarian cancers had ALDH1A1 expression in which the percentage of ALDH1A1-positive cells correlated negatively with progression-free survival (6.05 vs. 13.81 months; P < 0.035). Subpopulations of A2780cp20 cells with ALDH1A1 activity were isolated for orthotopic tumor-initiating studies, where tumorigenicity was approximately 50-fold higher with ALDH1A1-positive cells. Interestingly, tumors derived from ALDH1A1-positive cells gave rise to both ALDH1A1-positive and ALDH1A1-negative populations, but ALDH1A1-negative cells could not generate ALDH1A1-positive cells. In an in vivo orthotopic mouse model of ovarian cancer, ALDH1A1 silencing using nanoliposomal siRNA sensitized both taxane- and platinum-resistant cell lines to chemotherapy, significantly reducing tumor growth in mice compared with chemotherapy alone (a 74%-90% reduction; P < 0.015). These data show that the ALDH1A1 subpopulation is associated with chemoresistance and outcome in ovarian cancer patients, and targeting ALDH1A1 sensitizes resistant cells to chemotherapy. ALDH1A1-positive cells have enhanced, but not absolute, tumorigenicity but do have differentiation capacity lacking in ALDH1A1-negative cells. This enzyme may be important for identification and targeting of chemoresistant cell populations in ovarian cancer.     

Replication and cytolysis of an E1B-attenuated adenovirus in drug-resistant ovarian tumour cells is associated with reduced apoptosis

Therapeutic approaches which are effective in tumour cells resistant to conventional chemotherapy would be of value. An E1B 55 kDa-deleted adenovirus (ONYX-015) induces lysis in cells with mutant p53, although the specificity of these observations for different cell types is unclear. We have used a matched set of drug-resistant human ovarian tumour cell lines to examine the potential of ONYX-015 for preferential replication and lysis of drug-resistant ovarian tumour cells with documented alterations in p53 function. Marked preferential replication of ONYX-015 is observed after infection of mutant p53 transfectant and cisplatin-resistant derivatives, compared to the wild-type p53 expressing parental A2780 line. Infection causes increased cytopathic effects in vitro and inhibition of tumour growth in vivo of the drug-resistant derivatives, but not the parental line. In apparent contrast, increased apoptosis and reduced clonogenic survival is induced by ONYX-015 infection of the chemosensitive parental cell line. ONYX-015 induces increased pro-apoptotic BAX and reduced anti-apoptotic BCLX(L) in parental cells, but not in the resistant derivative A2780/cp70. We propose that induction of apoptosis is one factor which prevents ONYX-015 spread and cytolysis after infection of chemosensitive cells, while it is the failure to engage apoptosis in drug-resistant cells that allows preferential viral replication, spread and cytolysis.     

白血病和卵巢癌亲代及耐药细胞系细胞外调节蛋白激酶与端粒酶活性的变化

本研究观察白血病和卵巢癌亲代及耐药细胞系中端粒酶活性及细胞外调节蛋白激酶(extracelluar regulated protein kinases ERK)磷酸化蛋白表达水平的变化，探讨端粒酶与ERK在白血病及卵巢癌耐药中的作用。采用MTT法评价白血病和卵巢癌亲代和耐药细胞系对HRT或DDP的敏感性，用流式细胞术分析这两种细胞系间细胞周期分布的差别，用端粒酶重复扩增技术(TRAP)、生物发光分析法定量和定性检测端粒酶活性及用Western blot检测法检测磷酸化ERK1和ERK2蛋白的表达水平。结果表明：白血病和卵巢癌耐药细胞系处于G0／G1期的细胞比例增加，端粒酶活性和磷酸化ERK1/2蛋白表达水平耐药细胞系较亲代细胞系高。结论：耐药细胞系G0／G1期细胞比例增加可能是细胞产生耐药的一种标志。白血病和卵巢癌细胞系耐药的产生可能与端粒酶活性和磷酸化ERK1/2蛋白表达水平的增高有关。