TRAIL和ACNU对实验性大鼠脑胶质瘤的治疗作用

[目的]观察TRAIL和嘧啶亚硝脲（ACNU）对实验性大鼠脑胶质瘤的治疗作用,并探讨TRAIL和ACNU联合在诱导细胞凋亡中的作用机制。[方法]制备Wistar大鼠C6细胞胶质瘤动物模型,并随机分成4组：TRAIL＋ACNU治疗组（A组）、ACNU治疗组（B组）、TRAIL治疗组（C组）、生理盐水对照组（D组）。观察动物的生存状况及肿瘤大体情况,测量肿瘤的体积、计算肿瘤的抑制率;观察TRAILR2/DR5免疫组织化学表达变化情况;电镜观察肿瘤细胞变化;流式细胞仪检测肿瘤细胞凋亡情况。[结果]A组与B组的大鼠生存较好,而C组与D组的大鼠生存差。肿瘤体积分别为A组（19.00±2.59）mm3、B组（68.76±5.56）mm3、C组（230.31±13.94）mm3、D组（238.84±10.64）mm3。除C组和D组相比无显著差异外,4组间两两比较均有显著差异（P〈0.05）。电子显微镜观察,A组和B组可见明显凋亡小体,C组与D组少见。肿瘤细胞凋亡率A组（20.38%±1.62%）大于B组（14.85%±2.41%）,差异有显著性（P〈0.05）;C组（0.44%±0.21%）与D组（0.35%±0.24%）相比较差异无显著性（P〉0.05）。[结论]ACNU引起肿瘤细胞凋亡,并可诱导大鼠脑胶质瘤细胞表达DR5,使其对TRAIL诱导的凋亡敏感,TRAIL和ACNU体内联合应用具有协同作用。     

树突细胞／肿瘤细胞融合疫苗对食管癌移植瘤生长的抑制作用

背景与目的：我们前期的研究表明树突细胞／肿瘤细胞融合疫苗能有效诱导体外抗食管癌细胞的特异性免疫应答。在此基础上,本研究进一步探讨树突细胞／肿瘤细胞融合疫苗诱导抗原特异性细胞毒性T淋巴细胞（cytotoxic T lymphocytes．CTLs）对食管癌细胞株EC-109裸鼠皮下移植瘤的体内抑瘤作用及对肿瘤细胞增殖和凋亡的影响。方法：①采用聚乙二醇法制备树突细胞／肿瘤细胞融合疫苗并诱导抗原特异性CTLs产生。②建立食管癌EC-109细胞裸鼠皮下移植瘤模型,将成功荷瘤的裸鼠随机分为3组,分别以融合细胞激活的CTLs（A组．n=11）、未激活的T淋巴细胞（B组,n=11）以及RMPI-1640培养液（C组,n=11）作为效应细胞进行瘤内注射,每周一次。③4周后处死动物剥离肿瘤组织．测量并比较各组肿瘤组织的平均体积及平均湿重,计算抑瘤率。④免疫组化SP法检测3组裸鼠移植瘤增殖细胞核抗原（proliferating cell nuclear antigen,PCNA）的表达。⑤流式细胞仪检测3组肿瘤细胞周期及细胞凋亡率,比较各组肿瘤细胞的S期细胞平均百分比（S-phase fraction,SPF）以及细胞平均凋亡率。结果：①A组肿瘤组织的平均体积显著小于B组和C组,差异有统计学意义[（881．45±31．14）mm^3 vs．（1493．37±51．67）mm^3,（2065．77±87．55）mm^3,F=950．67．P=0．00],其平均湿重亦显著小于B组和C组,差异有统计学意义[（0．88±0．04）gvs．（1．38±0．07）g,（2．04±0．11）g,F=1335．90,P=0．00];A组抑瘤率明显高于B组,差异有统计学意义（56．86％ vs．32．35％,F=1218．08,P=0．001）。②A组肿瘤的平均PCNA—LI明显低于B组和C组,差异有统计学意义[（26．83±0．95）％ vs．（51．82±1．51）％,（68．93±2．40）％,F=1528．39,P=0．000]。③A组肿瘤细胞平均SPF值明显低于B、C两组,差异有统计学意义[（12．     

槲皮素联合顺铂对肺腺癌小鼠移植瘤Bcl-2和Bax表达的调控及意义

目的：观察槲皮素联合顺铂对肺腺癌LA795细胞的T739小鼠移植瘤的抑制作用，检测移植瘤中Bcl-2和Bax的表达水平及肿瘤细胞凋亡指数，探讨其作用机制。方法：将32只接种了LA795肺腺癌细胞的T739小鼠随机分成对照组（A组）、顺铂组（B组）、槲皮素组（C组）、槲皮素＋顺铂组（D组）。用药16d后，观察肿瘤生长情况，接种后24d活杀各组小鼠，移植瘤标本称瘤体质量和测量体积，免疫组织化学和图像分析系统定量检测肿瘤组织的Bcl-2和Bax表达，原位凋亡TUNEL法检测肿瘤细胞凋亡指数。结果：B、C、D各用药组肿瘤的生长受到明显抑制，瘤体质量明显低于A组，其抑瘤率分别为38．57％、26．03％和51．58％，联合用药组抗瘤作用进一步增强。Bcl-2表达在A组高于B、C、D组，Bax表达在A组明显低于B、C、D组，各用药组与对照组相比差异均有统计学意义（P〈0．05或P〈0．01）；肿瘤细胞的凋亡指数在各用药组都比对照组明显提高，差异有统计学意义（P〈0．01）。结论：槲皮素联合顺铂可明显抑制肺腺癌细胞在小鼠体内的生长，其作用机制可能是通过调控肿瘤中Bcl-2和Bax的表达，从而抑制细胞增殖和促进细胞凋亡。     

罗勒多糖对卵巢癌肿瘤转移相关基因SEMA4C表达影响实验研究

目的：观察分析罗勒多糖对卵巢癌SKOV3细胞肿瘤转移相关基因SEMA4C表达的影响,揭示罗勒多糖抗卵巢癌转移的作用机制。方法：体外培养卵巢癌SKOV3细胞,实验分为5组,A组为不加罗勒多糖处理的空白对照组,B组（罗勒多糖100mg／L）、C组（罗勒多糖500mg／L）、D组（罗勒多糖1000mg／L）、E组（紫杉醇0．05μmol／L）为紫杉醇组;荧光实时定量PCR检测不同处理组细胞中SEMA4CmRNA的表达变化;免疫细胞化学分析不同处理组细胞中se—ma4C蛋白的表达差异。结果：SKOV3细胞中SEMA4CmRNA相对表达量,B组为（3．60±0．01）×10-4,C组为（3．04±0．34）×10-4,D组为（1I81±0．42）×10-4,E组为（5．56±0．14）×10-4,与A组（9．02±0．41）×10-4比较,差异均有统计学意义,P〈0．01;B、C和D组与E组比较,差异有统计学意义,P〈0．01;SKOV3细胞中Sema4C蛋白表达平均光密度B组为9．64±0．21,C组为8．58±0．16,D组为6．15±0．38,E组为12．16±0．20,与A组的15．19±0．22比较,差异有统计学意义,P〈0．01;B、C和D组与E组比较,差异均有统计学意义,P〈O．01;罗勒多糖可以抑制卵巢癌细胞中SEMA4CmRNA及编码蛋白的表达,且随着药物浓度的增大,抑制作用越明显。结论：罗勒多糖可下调肿瘤转移相关基因SEMA4C的表达,可能是罗勒多糖抗卵巢癌淋巴道转移的新机制。     

抑制骨保护素表达对乳腺癌细胞增殖及TRAIL致其凋亡的影响

目的观察抑制肿瘤细胞骨保护素（OPG）表达对乳腺癌细胞株MDA-MB-231增殖和肿瘤坏死因子相关凋亡诱导配体（tumor necrosis factor-related apoptosis inducing ligand,TRAIL）致其凋亡的影响。方法采用M1Tr法检测对照MDA-MB-231和MDA-MB-231i细胞（OPG表达抑制）增殖;流式细胞术分析对照MDA-MB-231细胞和TRAIL作用24h后MDA-MB-231、MDA-MB-231i细胞凋亡率。结果前2组细胞倍增时间分别为43．5±2．9小时和45．8±3．6小时,差异无统计学意义;后3组细胞凋亡率分别为6．4％±1．3％、16．1％±1．7％和24．4％±3．3％,每2组之间差异均有统计学意义（P值分别为0．001、0．01和0．018）。结论抑制乳腺癌细胞OPG表达不影响其增殖能力。TRAIL可以诱导乳腺癌细胞凋亡,抑制乳腺癌细胞OPG表达可显著增强TRAIL诱导其凋亡的能力。     

塞来昔布联合放射对人鼻咽癌细胞生物效应的研究

目的 探讨COX-2选择性抑制剂塞来昔布联合放射对CNE-1细胞存活和凋亡的影响，并初步探讨其与药物浓度之间的相关性。方法 选择鼻咽癌CNE-1细胞系作为实验对象，以药物浓度0、1．25、2．50、5．00μmol／L设A、B、C、D实验组。4个组分别予6MVX线照射0、2、4、6Gy后分别行成克隆实验、流式细胞仪检测细胞存活分数（SF）及细胞早、晚期凋亡率。结果B、C、D组与A组之间SF值及晚期凋亡率差异有统计学意义（P〈0．05）；B组与C、D组之间差异有统计学意义（P〈0．05）；C组与D组间SF值、晚期凋亡率差异无统计学意义（P〉0．05）；各组间早期凋亡率差异无统计学意义（P〉0．05）。结论塞来昔布联合放射对CNE-1细胞存活下降和晚期凋亡增加有影响，并随药物浓度增加而增加，且在2．50μmol／L达最高值，但对早期凋亡无影响。     

槲皮素联合川芎嗪对小鼠Lewis 肺癌生长的抑制作用

 目的 探讨槲皮素联合川芎嗪对小鼠Lewis肺癌生长的抑制作用及其机制。方法 复制C57BL小鼠Lewis肺癌模型，将40只接种Lewis肺癌的C57BL小鼠随机分成4组：对照组（A组）、槲皮素组（B组）、川芎嗪组（C组）、槲皮素＋川芎嗪组（D组），每组10只。连续用药20日，观察移植瘤生长情况，于接种后第22天处死各组小鼠，采用免疫组化半定量检测肿瘤组织微血管密度（MVD）、血管内皮生长因子（VEGF）及增殖核抗原（PCNA）的表达水平，用原位凋亡TUNEL法检测肿瘤细胞凋亡指数（AI）。结果 （1）B、C、D组肿瘤的生长明显受到抑制，瘤重明显低于A组，其抑瘤率分剐为39．87％、35．45％、54．58％，D组抑瘤率明显高于B、C组，差异有显著性（P〈0．05）。（2）B、C、D组MVD、VEGF及PCNA表达水平明显低于A组（P〈0．05或0．01），尤其是D组表达最低。B、C、D组AI较A组增高（P〈0．05或0．01），D组最高。结论 槲皮素与川芎嗪联合用药可明显抑制Lewis肺癌移植瘤的生长，其作用机制与抑制微血管生成、抑制细胞增殖和促进细胞凋亡有关。     

抑制肿瘤细胞骨保护素表达对乳腺癌细胞致骨转移能力的影响

目的观察抑制肿瘤细胞骨保护素（0steoprotegerin,OPG）表达对乳腺癌MDA～MB-231细胞株致骨转移的影响。方法32只4～6周龄雌性裸鼠被随机分为A、B、C、D4组,每组8只,A、C组的每只裸鼠按分组分别以5×10。个MDA—MB-231细胞注射入左心室（A组）或左胫骨骨髓腔（C组）。B、D组的每只裸鼠按分组分别以5×10。个MDA—MB-231i细胞（OPG表达抑制）注射人左心室（B组）或左胫骨骨髓腔（D组）,42d后行病理检查,比较A、B组骨转移发生率和骨转移灶数量,以及C、D组的骨肿瘤体积。定量资料的比较采用t检验或秩和检验,定性资料比较采用Fisher确切概率检验。结果A组有6只发生骨转移,全组共检出不连续性骨转移灶23处;B组有3只发生骨转移,全组共检出不连续性骨转移灶8处。A组的骨转移发生率和转移灶数量虽高于B组,但两者差异并无统计学意义（P〉0．05）。C组肿瘤平均体积为（66．29±41．01）mm3,D组肿瘤平均体积为（23．70±16．14）mm3,C组骨肿瘤体积大于D组,两组间差异有统计学意义（P=0．02）。结论乳腺癌细胞致骨转移能力与其OPG表达水平密切相关,抑制OPG表达可以降低乳腺癌细胞致骨转移的能力。     

TRAIL与卡铂联合诱导卵巢癌细胞凋亡的研究

目的探讨肿瘤坏死因子相关凋亡诱导配体（TRAIL）与卡铂（CBP）联合应用对体外培养的卵巢A2780细胞的生物学效应及其作用机制。方法采用MTT法、流式细胞术，检测体外培养的A2780细胞在卡铂和TRAIL共同作用下的细胞增殖抑制效应以及细胞凋亡程度，应用半定量逆转录多聚酶链反应（RT-PCR）法检测TRAIL受体的mRNA表达水平。结果A2780细胞对TRAIL敏感，TRAIL与卡铂联合用药对细胞的增殖抑制呈现高效协同作用，与单独用药组比较有显著性差异（P〈0．05）；流式细胞术分析协同性杀伤作用主要由于TRAIL和CBP联合诱导细胞凋亡引起；RT—PCR法检测结果显示A2780细胞在TRAIL与卡铂联合用药后均表现死亡受体DR4、DR5表达水平上调和诱骗受体DcR1、DcR2表达水平下调。结论在体外TRAIL与化疗药物联用能明显抑制肿瘤细胞增殖，诱导肿瘤细胞凋亡，卡铂能明显增强TRAIL对肿瘤细胞的敏感性，其诱导机制可能与死亡受体DR4、DR5表达水平上调和诱骗受体DcR1、DcR2表达水平下调相关。     

胶质瘤egr-1基因表达水平与其细胞增殖和凋亡关系的研究

目的：探讨胶质瘤细胞egr-1基因表达水平与肿瘤恶性程度、细胞增殖活性及凋亡程度的关系。方法：用原位杂交、原位细胞凋亡检测和免疫组化染色方法观察了73例不同级别的胶质瘤。结果：73例胶质瘤egr-1mRNA和EGR-1蛋白阳性表达率均为100％．这两种阳性肿瘤细胞密度均随肿瘤恶性程度升高而相应增加，不同级别组间比较差异均有显著性（P〈0．01）。73例胶质瘤增殖细胞核抗原（PCNA）阳性肿瘤细胞和凋亡肿瘤细胞检出率均为100％。随肿瘤恶性程度升高，PCNA阳性肿瘤细胞密度增加而凋亡肿瘤细胞密度减少，不同级别组间比较差异均有显著性（心0．05～0．01）。经直线相关分析证实，egr-1mRNA、EGR-1蛋白和PCNA阳性肿瘤细胞密度彼此间均呈显著性正相关（r=0．685～0．999，P〈0．01），前三种阳性肿瘤细胞密度均与凋亡肿瘤细胞密度呈显著性负相关（r=-0．758—0．775，P〈0．01）。结论：egr-1基因表达水平对评价胶质瘤生物学行为有重要参考价值。胶质瘤细胞egr-1基因表达异常增加可能是促进肿瘤细胞增殖和抑制其凋亡的重要因素，并在胶质瘤发生及恶性进展过程中均起重要作用。     

尼莫司汀联合顺铂治疗C6脑胶质瘤的实验研究

目的:观察尼莫司汀(nimustine,ACNU)和顺铂(cisplatin,CDDP)联合应用治疗脑胶质瘤的增效作用,探讨临床联合使用化疗药物治疗脑胶质瘤的理论依据.方法:ACNU和CDDP联合处理C6胶质瘤细胞24 h后,采用FCM法检测细胞周期及细胞凋亡;建立Wistar大鼠颅内C6胶质瘤模型,ACNU和CDDP联合给药3 d后处死部分大鼠,HE染色肿瘤组织,进行形态学观察,免疫组织化学法检测增殖相关蛋白--增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)及凋亡相关蛋白bd-2的表达情况;观察剩余大鼠的生存情况.结果:FCM检测发现,联合用药组与CDDP组和ACNU组比较,细胞周期无明显变化;细胞凋亡率增加,联合用药组细胞凋亡率为(2.10±0.14)%,与CDDP组(1.72±0.21)%、ACNU组(0.57±0.01)%比较差异有统计学意义(P＜0.01).组织学观察发现,瘤灶边缘浸润灶数目减少;免疫组织化学结果显示,联合用药组PCNA、bcl-2蛋白表达下降,与单药应用组比较,差异有统计学意义(P＜0.01).联合用药组与单药应用组相比动物生存期延长,差异有统计学意义(P＜0.01).结论:ACNU与CDDP联合治疗脑胶质瘤比单药应用具有明显的增效作用.     

TRAIL在脑胶质瘤治疗中的研究进展

肿瘤坏死因子相关凋亡诱导配体(TRAIL)能选择性杀伤肿瘤细胞而对正常细胞无损伤。TRAIL死亡受体在脑胶质瘤组织广泛表达,但不同胶质瘤细胞对TRAIL诱导的凋亡敏感性存在差异,针对耐药机制来选择相应药物干预可以恢复其敏感性。研究发现某些化疗药物、放射线及基因疗法可增强TRAIL对肿瘤细胞的杀伤作用。     

Neuro-Oncology Working Group 01 trial of nimustine plus teniposide versus nimustine plus cytarabine chemotherapy in addition to involved-field radiotherapy in the first-line treatment of malignant glioma.

PURPOSE: The role of chemotherapy in the primary treatment of malignant glioma remains controversial. The results from the German-Austrian Glioma trial (GAG, 1983 to 1988) demonstrated a survival benefit for chemotherapy using carmustine (BCNU) plus teniposide (VM26) over BCNU alone in addition to radiotherapy in patients with a Karnofsky performance score (KPS) more than 60. The Neuro-Oncology Working Group (NOA) of the German Cancer Society therefore compared the efficacy of nimustine (ACNU) plus VM26 and ACNU plus cytarabine (Ara-C) chemotherapy in addition to standard radiotherapy in patients with newly diagnosed malignant glioma. PATIENTS AND METHODS: From 1994 to 2000, 375 patients were randomly assigned to receive radiotherapy and cycles of ACNU 90 mg/m2 intravenously (IV) on day 1 and VM26 60 mg/m2 IV on days 1 to 3 (n = 183), or ACNU 90 mg/m2 IV on day 1 and Ara-C 120 mg/m2 IV on days 1 to 3 (n = 179), in 6-week intervals. Thirteen patients were not eligible after central neuropathology review. The remaining 362 patients had glioblastoma (n = 301) or anaplastic glioma (n = 61). RESULTS: Median survival and 2-year survival rates were 17.3 months and 25% for ACNU plus VM26, and 15.7 months and 29% for ACNU plus Ara-C in glioblastoma, and 60 months and 88% for ACNU plus VM26 and 62.5 months and 72% for ACNU plus Ara-C in anaplastic glioma. Multivariate analysis revealed no survival advantage for either arm or for subpopulations defined by histology, age, or KPS. Hematologic toxicity was more prominent in the ACNU plus Ara-C arm. CONCLUSION: The median survival times and 2-year survival rates for patients with anaplastic glioma and glioblastoma achieved in the NOA-01 trial compare favorably with historical trials and with the Radiation Therapy Oncology Group database. The toxicity profile favors ACNU plus VM26 for further evaluation.     

Lomustine and nimustine exert efficient antitumor effects against glioblastoma models with acquired temozolomide resistance

Glioblastomas (GBM) often acquire resistance against temozolomide (TMZ) after continuous treatment and recur as TMZ-resistant GBM (TMZ-R-GBM). Lomustine (CCNU) and nimustine (ACNU), which were previously used as standard therapeutic agents against GBM before TMZ, have occasionally been used for the salvage therapy of TMZ-R-GBM; however, their efficacy has not yet been thoroughly examined. Therefore, we investigated the antitumor effects of CCNU and ACNU against TMZ-R-GBM. As a model of TMZ-R-GBM, TMZ resistant clones of human GBM cell lines (U87, U251MG, and U343MG) were established (TMZ-R-cells) by the culture of each GBM cells under continuous TMZ treatment, and the antitumor effects of TMZ, CCNU, or ACNU against these cells were analyzed in vitro and in vivo. As a result, although growth arrest and apoptosis were triggered in all TMZ-R-cells after the administration of each drug, the antitumor effects of TMZ against TMZ-R-cells were significantly reduced compared to those of parental cells, whereas CCNU and ACNU demonstrated efficient antitumor effects on TMZ-R-cells as well as parental cells. It was also demonstrated that TMZ resistance of TMZ-R-cells was regulated at the initiation of DNA damage response. Furthermore, survival in mice was significantly prolonged by systemic treatment with CCNU or ACNU but not TMZ after implantation of TMZ-R-cells. These findings suggest that CCNU or ACNU may serve as a therapeutic agent in salvage treatment against TMZ-R-GBM.     

Enhanced effect of reserpine upon growth-inhibitory action of ACNU on ACNU-resistant C6 glioma

Reserpine was found to enhance the cytotoxicity of ACNU on ACNU-resistant C6 glioma (C6/ACNU) cells in vitro. When reserpine was added along with ACNU to the C6/ACNU cells in vitro. When reserpine was added along with ACNU to the C6/ACNU culture in vitro at a concentration of 10 microM, the IC50 of ACNU for C6/ACNU cells decreased to the level of that for C6 cells and ACNU resistance was completely overcome in vitro. Furthermore, intracellular uptake of ACNU increased in both sensitive (C6) and resistant (C6/ACNU) glioma cells when 20 microM reserpine was added to the culture medium. Reserpine (20 microM) enhanced the cellular level of ACNU in C6 cells 1.5-fold and enhanced the level of ACNU in C6/ACNU cells 4-fold. The amount of ACNU incorporated into C6/ACNU cells reached the same level as that incorporated into C6 cells. The enhanced cytotoxicity of ACNU in vitro could be explained by the effective intracellular accumulation of ACNU resulting from the increase of intracellular uptake of ACNU in C6/ACNU cells by reserpine.     

Therapeutic effect of neural stem cells expressing TRAIL and bortezomib in mice with glioma xenografts

Treatment of glioblastoma remains a challenge in neuro-oncology. We investigated if treatment with neural stem cells engineered to express membrane-bound TRAIL (NSCs-mTRAIL) alone or in combination with proteasome inhibitors is a feasible therapeutic approach for experimental glioma. Glioma cells showed resistance to soluble TRAIL and proteasome inhibitors alone, but responded well to their combined treatment. In co-culture with NSCs-mTRAIL, glioma cells appeared to be more prone to apoptosis than to treatment with soluble TRAIL, which was enhanced by proteasome inhibitor bortezomib. In vivo, the survival of animals bearing intracranial glial xenografts was significantly improved by NSCs-mTRAIL. The addition of bortezomib further enhanced the efficacy of NSCs-TRAIL treated group in one of examined tumor models. These data demonstrate that therapy with NSCs-mTRAIL is a potent cell based approach for treatment of glioma. Such an approach warrants further search for therapeutics capable of increasing sensitivity of glioma cells to mTRAIL in vivo.     

肿瘤坏死因子相关的凋亡诱导配体对胰腺癌细胞抗肿瘤作用的研究

Objective To investigate the antitumor effect of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)gene transfection mediated by adenovirus into human pancreatic carcinoma cell line Panc-1, and the mechanisms involved in this effect. Methods TRAIL gene was transfected into pancreatic cancer cell line Panc-1 by an adenovirus vector (Ad-TRAIL).Level of TRAIL mRNA expression was determined using RT-PCR, and TRAIL protein synthesis was evaluated with Western blot. Cell-growth activities were determined by MTT assay. The bystander effect was observed by co-culturing the Panc-1cells with the transfected TRAIL gene at different ratios. Apoptosis in pancreatic cancer cells was detected by flow cytometry.Procaspase-8 and procaspase-3 were determined by Western blot. Results The stable overexpression of TRAIL was detected in Panc-1 cells transfected by Ad-TRAIL. Ad-TRAIL significantly inhibited of cell viability of Panc-1 cells. Furthermore,co-culture of cancer cells transfected with TRAIL with that nontransfected resulted in the cell death of both cells by bystander effect. Moreover, the percentage of apoptotic cells was significantly higher in the Ad-TRAIL-treatment group compared to the control groups (P ＜ 0.01). And there was a diminished amount of procaspase-8 and procaspase-3 after infection with Ad-TRAIL. Conclusion The overexpression of TRAIL gene in Panc-1 cells by Ad-TRAIL exerts its antitumor effects, and themechanisms involved in this effect may be proapoptosis and bystander effect.     

The mechanism and overcoming of resistance in ACNU-resistant sublines of C6 and 9L rat glioma

In order to study the mechanism of the resistance to chemotherapeutic agents, especially ACNU [1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride], two variant cell lines (C6/ACNU and 9L/ACNU) resistant to ACNU were selected in vivo from rat C6 and 9L glioma, respectively. Uptake and efflux of ACNU in these resistant cells were studied with Ethylene[¹⁴C]ACNU. The result indicated that the resistance exhibited by both sublines were due to both the reduced uptake of the drug and the increased efflux. The study of the effects of oxidative phosphorylation inhibitor, DNP (2,4-dinitrophenol), on the uptake and retention of ACNU suggested that there is an active outward transport mechanism for ACNU in both glioma sublines and that enhanced activity of this efflux mechanism renders cells highly resistant to the cytotoxic action of ACNU. In an attempt to clarify the more detailed biochemical mechanisms of this active efflux system, we surveyed various membrane-modifying agents which potentiate the sensitivity of these resistant cells to ACNU. Among a number of membrane-modifying agents, reserpine was found to retain ACNU in the resistant cells and to enhance the action of ACNU on these resistant cell lines. It may be concluded that drugs such as reserpine may overcome a mechanism of ACNU resistance.Abbreviations PBS phosphate-buffered saline consisting of 0.02 M sodium phosphate, 0.15 M NaCl pH 7.4 - IC₅₀ concentration of drug required for 50% inhibition of cell growth - C6/ACNU C6 glioma cells resistant to ACNU - 9L/ACNU 9L glioma cells resistant to ACNU - CAP-2 2-(gamma-chloropropyl)2-chloromethylpyrimidine hydrochloride - BCNU 1,3-bis(2-chloroethyl)-1-nitrosourea     

Pharmacokinetics of intrathecal 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride in rats

Summary The pharmacokinetics of intrathecal 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) were studied in female Wistar rats by macroscopical autoradiography using¹⁴C labeled ACNU. In normal rats, ACNU rapidly distributed in the subarachnoid space and ventricles after intracisternal administration. Diffusional transport into the brain tissue was limited to a depth of 1 or 2 mm from the cerebrospinal fluid (CSF) surface of the brain. Clearance of ACNU from the CSF space and brain was relatively fast and the half time of ACNU concentration at the cortical or ventricular surface was 10 min. In rats with leptomeningeal tumor induced by intracisternal inoculation of Walker 256 carcinosarcoma cells, the distribution pattern of ACNU after intracisternal administration was essentially the same as in normal rats until the tumor had grown in the subarachnoid space to form more than 10 or 20 layers of tumor cells. ACNU was distributed in the tumor as well. When the tumor had grown to form masses in the subarach-noid space, ACNU failed to penetrate to more than a depth of 1 or 2 mm from the tumor surface.Our results suggest that intrathecal ACNU administration may have no, or minor side effects on the brain and that it can eliminate floating or thin layered tumor cells in the subarachnoid space but not bulky tumors.