Enhancing effect of electric stimulation on cytotoxicity of anticancer agents against rat and human glioma cells

Electropermeabilization, or electroporation, has been used to deliver genes or drugs into the cytoplasm through micropores in the cell membrane caused by electric stimulation. The cytotoxic effect of a combination of anticancer agents with electric stimulation on rat C6 and human T98G glioma cells was examined in vitro. Electric pulses of 100 microsec square waves (eight cycles at 1 Hz) at various electric fields were delivered to C6 or T98G glioma cell suspensions in combination with several anticancer agents. Cell growth was evaluated 48-72 h after treatment. Measurement of cell lysis by electric stimulation was used to assess the optimum field strength for electroporation. Electric stimulation enhanced significantly the cytotoxicity of bleomycin to both C6 and T98G cells by more than 1000-fold using an electric field of 1750 V/cm for C6 cells and 1000 V/cm for T98G cells. The enhancement disappeared when bleomycin concentration was reduced to 100 pg/ml. The cytotoxicity of carboplatin was weakly but significantly enhanced by electric stimulation when a high dose of carboplatin was used. However, there was no enhancement of the cytotoxicity of nimustine hydrochloride (ACNU), etoposide, and vincristine. These results indicate that the combination of bleomycin and electroporation is the most potent candidate for electrochemotherapy in vivo.     

IL-4基因修饰增强脑胶质瘤细胞毒性T淋巴细胞杀伤活性机制的探讨

目的 进一步探讨白细胞介素4（IL－4）基因修饰瘤苗增强细胞毒性T淋巴细胞（CTL）杀伤活性的机制。方法 通过逆转录病毒载体PL－IL－4－SN将人IL－4基因导入神经胶质瘤系SHG44细胞，以IL－4基因修饰瘤苗和野生型瘤细胞作刺激细胞诱导CTL反应，通过流式细胞仪检查瘤细胞表面分子的表达。结果 （1）IL－4基因修饰诱导瘤细胞表达MHC－Ⅱ类抗原、B7－1及ICAM－1等免疫刺激分子，对MHC－I类抗原表达无影响，其瘤苗诱导的CTL杀伤活性为野生型瘤细胞的7倍（P＜0．01）。（2）加入抗IL－4单抗可完全阻断IL－4诱导的细胞表面分子的表达，IL－4基因修饰瘤苗诱导CTL反应时培养上清可检测到大量IL－2的产生。抗IL－4或抗细胞表面分子单抗可降低IL－2产生及抑制CTL反应。结论 IL－4基因修饰可能是通过诱导MHC－Ⅱ类抗原等表面分子表达，促进IL－2的产生从而增强CTL杀伤活性。     

ANGPTL4基因对大鼠胶质瘤细胞系C6血管通道形成的影响

目的　研究ANGPTL4基因对C6细胞形成血管通道的影响。方法　将ANGPTL4蛋白进行原核表达 ,用MTT试验观察ANGPTL4对C6细胞增殖的影响 ,用体外迁移试验 ,体外侵袭试验和体外管状形成试验等体外血管新生研究模型观察ANGPTL4基因对C6细胞形成血管通道的影响。结果　ANGPTL4对C6细胞的增殖没有显著性作用 ;ANGPTL4基因可促进C6细胞的体外迁移 ,侵袭和管状形成。结论　ANGPTL4能够促进C6细胞形成血管通道。     

升高血压联合化疗治疗脑胶质瘤的实验研究

目的:观察利用血管紧张素Ⅱ(AgⅡ)升高血压状态下,钙离子拮抗剂尼莫地平(NMD)和化疗药物联合使用对移植性鼠脑胶质瘤的治疗效果,为临床上脑胶质瘤的化疗提供更合理的方法和理论依据。方法:通过立体定向技术制备移植性鼠脑胶质瘤模型,利用氢清除法测定变压条件下肿瘤和正常脑组织血流量,比较NMD对照组,BCNU、Vm-26、DDP联合化疗组,联合化疗加升压组对肿瘤鼠存活期,肿瘤抑制率及肿瘤病理学影响。结果:AgⅡ诱导高血压状态下,肿瘤组织内血流量明显增加,而其它部位脑组织血流量无明显变化。联合化疗加升压组的存活时间为44.8±11.3天,与联合化疗组的存活时间26.8±5.9天相比,差异显著(P<0.01),而且联合化疗加升压组抑瘤率高于联合化疗组。结论:在AgⅡ诱导高血压状态,通过钙离子拮抗剂与化疗药物的联合应用,可以提高脑胶质瘤的化疗效果。     

Chemotherapy for malignant brain tumors of astrocytic and oligodendroglial lineage

To date, surgery and irradiation remain the standard therapies for anaplastic astrocytoma (AA, WHO grade III) and glioblastoma multiforme (GBM, WHO grade IV). Due to infiltrative tumor growth a complete surgical resection is never achieved and more than 90% of the tumors will recur within 2 cm of the primary tumor location. Postoperative radiotherapy prolongs survival but is not curative and prognosis remains poor with only a few patients being alive 2 years after diagnosis. Over the past decades multiple trials dealt with the question of whether chemotherapy (CT) may influence the outcome of malignant brain tumor patients. In general, the results have been disappointing with one exception: chemosensitivity and prolonged survival after CT have been demonstrated for tumors of oligodendrogial lineage. Drugs showing some activity in malignant brain tumors and therapeutic concepts will be discussed. Received: 2 May 2000 / Accepted: 28 May 2000     

IL-13Rα2、VEGF和PTEN在人脑胶质瘤中的研究进展

胶质瘤是中枢神经系统发生率最高的恶性肿瘤,其治疗仍然是一大难题。近年来,对脑胶质瘤发病的相关分子机制和凋亡机制已进行了广泛而深入的研究,为进一步探讨胶质瘤的分子病因、分子分型、恶性进展、基因治疗及预后评估奠定了基础,尤其是对白细胞介素13受体α2(IL-13Rα2)、血管内皮生长因子(VEGF)及人10号染色体上缺失的磷酸酶和张力蛋白类似物(PTEN)的深入研究。本文总结了IL-13Rα2、VEGF和PTEN的研究进展及其临床意义。     

Efficient Retrovirus-mediated Cytokine-gene Transduction of Primary-cultured Human Glioma Cells for Tumor Vaccination Therapy

In order to realize a novel vaccination treatment for malignant gliomas using tumor cells genetically modified to express certain cytokines, it is essential to achieve an efficient gene transduction into primary cultured cells. We investigated the feasibility of preparing a glioma vaccine through retro-virus-mediated gene transduction. Glioma cells were cultured primarily from surgically resected tumor tissues of six patients. We obtained more than 1000-fold proliferation of cultures within eight weeks in all six cases. In vitro infection with a recombinant retrovirns GKlacZ carrying an Escherichia coli β -galsictosidase marker gene resulted in over 65% gene transfer to the primary cultured glioma cells. Further enrichment (∼90%) of transduced cells was possible by employing repeated infections or using vectors with neo marker gene. Two cytokine genes, granulocyte-macrophage colony-stimulating factor and interleukin-4, were introduced into glioma cells by sequential transduction with two single-expression GK vectors. The transduced glioma cells produced high levels of both cytokines. We also evaluated simultaneous introduction of two genes with double-expression GK vectors containing internal ribosomal entry site (IRES) or internal promoter (PGK). Although the cells transduced with double-expression vectors secreted both cytokines, the level of the gene product following IRES or PGK was 10 times lower than that of the upstream gene product. The transduced cells retained cytokine secretion in vitro for 14 days after 100 Gy irradiation. Our data indicate the feasibility of retrovirus-mediated preparation of gene-modified tumor vaccines from clinical glioma materials, which could be useful for potentiating antitumor immunity in glioma patients.     

对术中超声在神经胶质瘤分级中的诊断价值的探讨

通过分析不同等级胶质瘤的超声声像图表现,探讨术中超声在胶质增生和胶质瘤鉴别诊断以及胶质瘤分级中的临床应用价值.材料和方法:对21例胶质增生及胶质瘤患者的术中超声声像图进行回顾性分析,比较胶质增生及不同等级胶质瘤的超声声像图特征.结果:2例胶质增生,6例低级别胶质瘤,4例间变性胶质瘤和9例胶质母细胞瘤的声像图各具特征.尤其是高级别胶质瘤内的坏死液化发生率达到了53.8%(7/13),而胶质增生和低级别胶质瘤中均未见坏死液化灶,两者差异存在显著性(P＜0.05).结论:术中超声在诊断胶质增生及对胶质瘤分级中具有一定的应用价值.     

局部热化疗对鼠胶质瘤PCNA和VEGF蛋白表达的影响

目的研究局部热化疗对鼠胶质瘤PCNA和VEGF蛋白表达的影响,探讨其作为胶质瘤辅助治疗的可行性。方法将传代培养的C6细胞接种于大鼠背部皮下,肿瘤生长至1.5～2cm直径时,分组进行局部热疗、化疗、热化疗。测量肿瘤体积和重量;用免疫组化S-P法检测PCNA、VEGF蛋白表达,光镜观察肿瘤增殖状况。结果热疗、化疗、热化疗与对照组比较:瘤体缩小、瘤重减轻,PCNA和VEGF蛋白表达减低(P<0.01),且热化疗较单纯热疗和化疗减低更明显(P<0.01)。结论①热疗、化疗、热化疗能抑制肿瘤生长,且热化疗有协同作用;②热化疗一方面抑制PCNA合成与表达,抑制肿瘤增殖;另一方面抑制VEGF合成与分泌,抑制肿瘤血管再生,达到抗瘤作用。     

脑胶质瘤P^53蛋白表达的初步研究

作者随机选取２２例星形细胞瘤的新鲜标本作冰冻切片，然后采用抗Ｐ＾５３单克隆抗体ｐＡｂ２４０，按ＡＢＣ法作免疫组化检测。结果发现星形细胞瘤Ｉ级Ｐ＾５３蛋白表达阳性率为０，Ⅱ级阳性率为２５％，Ⅲ－Ⅳ级阳性率为５０％，三组间的阳性率有极显著差异。本文还讨论了Ｐ＾５３基因的生物学特性及其与临床的关系。