miRNA-34c对肺腺癌A549细胞的辐射增敏效应

目的研究肺腺癌A549细胞中miRNA-34e的辐射增敏效应。方法单独转染miRNA．34e序列或单独照射或转染和照射联合处理细胞后,采用MTT比色法检测细胞生长抑制率,流式细胞术检测细胞周期,藻红B染色法观察细胞凋亡率,Westernblot检测p53蛋白的表达。结果转染联合照射处理组的抑制率及凋亡率都较单独转染或单独照射组明显增高（均P〈0．05）,且随miR-34e转染浓度的增加而增高（均P〈0．05）。细胞周期检测结果显示,细胞明显阻滞于G1／G0期（P〈0．05）。联合处理的细胞p53蛋白表达量较单独照射组增加,且呈miRNA．34c浓度依赖性增加（P〈0．05）。结论miRNA-34c对肺腺癌细胞A549有辐射增敏效应,可强化p53蛋白的表达,诱导细胞G1／G0期阻滞和凋亡。     

Attenuation of chronic thermotolerance by KNK437, a benzylidene lactam compound,enhances thermal radiosensitization in mild temperature hyperthermia combined with low dose-rate irradiation

Purpose: We investigated whether the attenuation of chronic thermotolerance by KNK437, a heat shock protein inhibitor, can modify the effect of thermal radiosensitization in mild temperature hyperthermia (MTH) combined with low dose-rate irradiation (LDRI).

Materials and methods: The human lung adenocarcinoma cell line A549 was simultaneously exposed to LDRI with MTH at 41°C and KNK437 at a dose of 100 μM. Cell survival was estimated by a clonogenic assay. Cell cycle change during treatment was analyzed by flow cytometry. Expression levels of the heat shock proteins hsp72, hsp27 and heat shock factor 1 (HSF-1) were measured by Western blotting.

Results: KNK437 inhibited the expression of inducible hsp72 and hsp27, but produced no change in the mobility shift of HSF-1. The cytotoxicity of LDRI was enhanced by MTH. The survival curve for LDRI + MTH revealed no development of chronic thermotolerance up to 48 h. Simultaneous LDRI and KNK437 treatment also resulted in enhanced cell killing. The radiosensitizing effect of KNK437 was enhanced by simultaneous exposure of the cells to MTH. Flow cytometry analysis of cell cycle progression demonstrated marked G2 arrest and mild G1 arrest with LDRI alone, but mild G1 arrest with MTH alone, and mild G2-M, S-phase accumulation with KNK437 alone. The marked G2 arrest caused by LDRI was partially suppressed by the addition of MTH, and was also suppressed by KNK437 treatment.

Conclusions: Exposure of A549 cells to KNK437 caused inhibition of hsp72 and hsp27 expression. The addition of KNK437 increased not only thermosensitivity to MTH, but also radiosensitivity to LDRI. KNK437 also enhanced the MTH-induced radiosensitization under these experimental conditions.     

p27kip1基因转染增强放射抗拒人食管癌细胞的放射敏感性

目的研究腺病毒介导的p27kip1基因转染对人放射抗拒食管癌细胞放射敏感性的影响。方法以重组腺病毒介导的p27kip1基因转染人放射抗拒食管癌细胞EC9706R,免疫细胞化学法检测p27kip1表达;流式细胞仪检测转染前后肿瘤细胞周期,克隆形成实验检测p27kip1基因转染前后两种EC9706R细胞的放射敏感性。结果腺病毒转染后放射抗拒食管癌EC9706R细胞p27kip1表达明显升高,细胞周期结果显示G0/G1期阻滞;转染p27kip1前后放射敏感性参数检测结果比较:转染前EC9706R细胞SF2=67.4%,Dq=1.66 Gy,转染后SF2=49.7%,Dq=1.03 Gy,放射增敏比SERSF2、SERDq分别为1.36,1.61,两者比较差异有统计学意义(P<0.05)。结论 p27kip1基因转染能增强人放射抗拒食管癌细胞的放射敏感性。     

Induction of autophagy promotes differentiation of glioma-initiating cells and their radiosensitivity

Glioblastoma (GBM) is a highly aggressive brain tumor characterized by increased proliferation and resistance to chemotherapy and radiotherapy. Recently, the identification of tumor-initiating cells with stem-like properties in diverse human cancers including GBM represents an important conceptual advance in cancer biology with therapeutic implications. However, the factors determining the differential development and radiosensitization of glioma-initiating cells (GICs) remain poorly defined. Here, we report that rapamycin induced differentiation of GICs and increased their sensitivity to radiation by activating autophagy. Transient in vitro exposure to rapamycin and radiation abolished the capacity of transplanted GICs to establish intracerebral GBMs. Most importantly, in vivo combination of rapamycin and radiation effectively blocked the tumor growth and associated mortality that occurs in mice after intracerebral grafting of human GICs. We demonstrate that rapamycin activated their autophagy and triggers the differentiation cascade in GICs isolated from human GBMs. This was followed by a reduction in proliferation, cell viability, clonogenic ability and increased expression of neural differentiation markers after radiation. Our results suggest that autophagy plays an essential role in the regulation of self-renewal, differentiation, tumorigenic potential and radiosensitization of GICs, suggesting autophagy could be a promising therapeutic target in a subset of GBMs. We propose that autophagy defect in GICs contributes to radioresistance of GICs by desensitizing GICs to normal differentiation cues. Activating autophagy may abrogate the resistance of GICs to radiation and could lead to the development of novel therapeutic approaches for the treatment of GBMs.     

拓扑替康、顺铂和泰素对宫颈癌HeLa细胞的抑制及放射增敏作用

目的研究拓扑替康（TPT）对宫颈癌HeLa细胞的杀伤作用和放射增敏作用,并与顺铂（DDP）和泰素（TAX）进行对比分析。方法采用MTT法检测TPT、DDP和TAX对宫颈癌HeLa细胞增殖能力的影响,细胞克隆形成法研究三种化疗药物的放射增敏作用,并应用单击多靶模型计算放射增敏比。结果TPT、DDP和TAX作用HeLa细胞24、48和72h半数抑制浓度分别为8．0、2．6和0．8μg／mL,2．4、0．7和0．1μg／mL,0．3、0．1和0．0μg／mL。三种化疗药物的放射增敏组肿瘤细胞凋亡率均明显高于单放射组和单独化疗组（P〈0．05）;放射增敏实验中,TPT作用24h和48h后放射增敏比分别为1．167和1．344,DDP为1．314和1．538。TAX为1．076和1．316。结论TPT、DDP和TAX对宫颈癌HeLa细胞具有明显抑制作用,且呈时间和浓度依赖性。三种化疗药物具有放射增敏作用,DDP的放射增敏作用最强,TAX最弱。     

多西他赛对人肝癌放疗增敏及其作用机制探讨

目的 观察不同浓度多西他赛(Docetaxel)在体外对人肝癌细胞的放射增敏作用及其机制。方法 用0．125、0．25、0．5nmol／L多西他赛作用人SMMC-7721肝癌细胞株24h和0．125、0．25nmol／L多西他赛作用48h后分别给予0、2,4、6、8、10Gy剂量照射，单纯照射组未给予多西他赛处理而接受同等剂量照射，用集落形成实验分析放射增敏效应。另外用流式细胞术检测上述不同浓度多西他赛分别作用不同时间SMMC-7721细胞内活性氧(reactive oxygen species，ROS)和用比色法测定谷胱甘肽(glutathione，GSH)含量的变化。结果 用0．125、0．25、0．5nmol／L多西他赛作用24h和0．125、0．25nmol／L多西他赛作用48h均能观察到各自的放射增敏作用，其放射增敏比(SERDq)分别为1．12、1．19、1．43和1．37、1．48。同时观察到上述剂量多西他赛作用不同时间导致SMMC-7721细胞内ROS产生增多和GSH降低。结论 上述剂量多西他赛在体外对SMMC-7721肝癌细胞具有放射增敏作用，其增敏机制与用药后细胞内ROS产生增多和GSH降低有关。     

Valproic acid promotes radiosensitization in meningioma stem-like cells

Although meningioma stem-like cells have been isolated and characterized, their therapeutic targeting remains a challenge. Meningioma sphere cells (MgSCs) with cancer stem cells properties show chemo- and radioresistance in comparison with meningioma adherent cells (MgACs). We tested the effect of valproic acid (VPA), a commonly used anti-epileptic drug, which passes the blood brain barrier, on cultured MgSCs. VPA reduced the viability of MgSCs and MgACs. In MgSCs, treatment with VPA increased radio-sensitivity, expression of p-cdc2, p-H2AX and cleaved caspase-3 and PARP. Anchorage-independent growth (AIG) was reduced by VPA. AIG was further reduced by combined treatment with irradiation. Expression of a stem cell marker, Oct4, was reduced by VPA. Oct4 was further decreased by combined treatment with irradiation. These results suggest that VPA may be a potential treatment for meningioma through targeting meningioma stem-like cells.     

同期放化疗诱导人结直肠癌细胞发生上皮-间质转化

目的:探讨放化疗抵抗的结直肠癌细胞发生上皮-间质转化(epithelial-mesenchymal transition,EMT)的意义.方法:采用5-FU化疗同期进行放疗对人结直肠癌野生型细胞(HCTll6)进行干预,诱导放化疗共同抵抗的细胞株(HCT1 16CRR)并采用克隆形成实验进行放化疗抵抗性的鉴定.高倍显微镜下观察细胞形态学变化.采用Real-time PCR和Western印迹,检测上皮表型标志物E-cadherin,间质表型标志物N-cadherin、波形蛋白(vimentin)、核转录因子(Snail)mRNA及其蛋白的表达.结果:放化疗抵抗的结直肠癌细胞发生与EMT相符的形态学改变,细胞呈纺锤体状,极性消失,并出现伪足;Real-time PCR和Western印迹结果显示E-cadherin mRNA及蛋白表达下调;N-cadherin,vimentin,Snail mRNA及蛋白表达上调,差异有统计学意义(P＜0.05).结论:放化疗抵抗后的人结直肠癌细胞发生EMT,其与结直肠癌的治疗抵抗相关.     

Complete Response of Esophageal Cancer Achieved by Combination Therapy with 5-Fluorouracil, Low-Dose Cisplatin, and Radiation: Report of a Case

2 per day, from days 1–5 combined with the daily administration of low-dose cisplatin, 10 mg/m² per day before each fraction of radiation, given as 2 Gy each time, throughout the entire treatment period of 3 weeks beginning on day 1. The benefits of our preoperative chemoradiation therapy included no severe side effects, down-staging and resectability of the tumor, as well as a pathological complete response, which could prolong the survival time. Our experience of this case prompts us to recommend the concurrent daily preoperative chemoradiation therapy for patients with locally advanced esophageal cancer. (Received for publication on June 20, 1997; accepted on Jan. 6, 1998)