Inhibition of checkpoint kinase 1 sensitizes lung cancer brain metastases to radiotherapy

The most important therapeutic tool in brain metastasis is radiation therapy. However, resistance to radiation is a possible cause of recurrence or treatment failure. Recently, signal pathways about DNA damage checkpoints after irradiation have been noticed. We investigated the radiosensitivity can be enhanced with treatment of Chk1 inhibitor, AZD7762 in lung cancer cell lines and xenograft models of lung cancer brain metastasis. Clonogenic survival assays showed enhancement of radiosensitivity with AZD7762 after irradiation of various doses. AZD7762 increased ATR/ATM-mediated Chk1 phosphorylation and stabilized Cdc25A, suppressed cyclin A expression in lung cancer cell lines. In xenograft models of lung cancer (PC14PE6) brain metastasis, AZD7762 significantly prolonged the median survival time in response to radiation. Depletion of Chk1 using shRNA also showed an enhancement of sensitivity to radiation in PC14PE6 cells. The results of this study support that Chk1 can be a good target for enhancement of radiosensitivity.     

纳米金在肿瘤成像和放射治疗领域的应用进展

纳米金颗粒以其优越的理化性质在医学领域发挥独特的作用.近年来越来越多的研究证实了纳米金在肿瘤早期诊断和治疗方面方面有重要作用,尤其是纳米金正被逐步应用肿瘤成像和治疗领域.本文从纳米金的性质,在肿瘤成像和放射治疗方面的应用进展等方面作一综述.     

青蒿琥酯对肺癌细胞裸鼠皮下移植瘤生长和放射敏感性的影响研究

目的:探讨青蒿琥酯对肺癌细胞裸鼠皮下移植瘤生长和放射敏感性的影响。方法:将肺癌细胞接种至裸鼠皮下,腹腔注射青蒿琥酯,同时给予放射处理记为联合组,设置青蒿琥酯组(不照射处理)、放射组(腹腔注射生理盐水)和对照组(腹腔注射生理盐水,不放射处理),测量肿瘤体积,取瘤体并称取瘤体重量,脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(TUNEL)法检测组织中细胞凋亡水平,Western blot检测组织中活化的含半胱氨酸的天冬氨酸蛋白水解酶3(Cleaved Caspase-3)、信号转导与转录因子3(STAT3)、磷酸化的STAT3(p-STAT3)、p38丝裂原活化蛋白激酶(p38MAPK)、磷酸化的p38MAPK(p-p38MAPK)水平。结果:青蒿琥酯组、放射组、联合组皮下移植瘤体积和重量均明显低于对照组,联合组肿瘤重量和体积明显低于青蒿琥酯和放射组,差异均具有统计学意义(P0.05)。青蒿琥酯、放射组、联合组肿瘤组织中细胞凋亡率、Cleaved Caspase-3水平和p-p38MAPK/p38MAPK均明显高于对照组,联合组肿瘤组织中细胞凋亡率、Cleaved Caspase-3水平和p-p38MAPK/p38MAPK高于青蒿琥酯和放射组,差异均具有统计学意义(P0.05)。青蒿琥酯、放射组、联合组肿瘤组织中p-STAT3/STAT3水平明显低于对照组,联合组肿瘤组织中p-STAT3/STAT3水平低于蒿琥酯组和放射组,差异均具有统计学意义(P0.05)。结论:青蒿琥酯能够抑制肺癌细胞裸鼠皮下移植瘤生长,促进癌细胞凋亡,增加放疗敏感性,作用机制可能与p38MAPK、STAT3信号通路有关。     

应用蛋白质组学方法初步筛选与鼻咽癌放射敏感相关的蛋白

目的:通过筛选放射敏感性不同的鼻咽癌细胞中差异表达蛋白,以发现与鼻咽癌放射敏感相关的蛋白。方法:放射处理并结合流式细胞术检测及比较5-8F和6-10B细胞的放射敏感性。提取细胞总蛋白,进行双向凝胶电泳、MALDI-TOF肽质指纹图分析、质谱数据的蛋白质库搜寻鉴定。应用Western Blot检测细胞中蛋白质表达。应用免疫组织化学方法检测鼻咽癌组织中相关蛋白的表达。结果:双向凝胶电泳后对胶上的部分分辨较好的差异蛋白质点进行肽质谱指纹图分析和鉴定,在两种细胞中差异表达最为显著的蛋白质有9个。Western Blot证实CK19和P73在5-8F和6-10B表达与蛋白质组结果一致。P73在鼻咽癌放射敏感组和不敏感组中的表达阳性率分别为90%、57.5%,存在显著性差异。结论:放射敏感性不同的鼻咽癌细胞中存在一些差异表达蛋白,这些蛋白可能与鼻咽癌放射敏感性有关,其中P73可能成为放射敏感性预测的侯选标志物。     

血卟啉衍生物对X线照射的HeLa细胞增敏效应

血卟啉衍生物(HpD)作为光敏剂与激光技术相结合应用于临床治疗浅表肿瘤已取得显著的疗效。但是,HpD能否作为辐射增敏剂治疗深部肿瘤亦已引起人们的重视。本文报告了离体培养的HeLa细胞经HpD(30微克/毫升)处理后接受X线(5 Gy)照射,观察其某些生物学特性的改变,并以此作为判断HpD的辐射增敏效应的指标。实验结果表明,HeLa细胞经HpD处理后可提高辐射敏感性(SER)10—67.7%。     

The track structures of ionizing particles and their application to radiation biophysics

Using knowledge of the track structure generated by ionizing particles together with details of the organisms being irradiated, the application of a new analytical method to two biophysical models to explain the inactivation of cells by radiation has been developed. It is shown that both models are equally successful in predicting experimental results and that good agreement is found with the data for single-strand phage, Bacillus subtilis spores, various strains of Escherichia coli, haploid and diploid yeast, and human diploid fibroblasts. The only significant discrepancy arose with T1-phage, for which a tentative explanation is offered. The differences in inherent radiosensitivity between organisms, after allowance is made for differences in target size, are attributed to differences in enzymatic repair systems and in the packing of the DNA. Received: 5 August 1998 / Accepted in revised form: 3 May 1999     

荧光晕法在细胞染色质结构状态检测中的应用

荧光晕法是近年来发展起来的定量检测细胞染色质结构状态的方法,由于其简易、直观、灵敏、快速,已被广泛用于放射生物学及肿瘤细胞生物学研究中。我们依据文献报道建立了此法,并对其进行了改良,进一步优化了操作步骤。并用该法检测了两种相同来源(具有相似遗传背景)、具不同辐射敏感性的细胞株的染色质结构状态,发现辐射敏感株SX-9具有更松散的染色质结构,可能与两者的辐射敏感性差异有关,为研究染色质结构状态与辐射敏感性的关系提供了佐证。     

Telomeres: hallmarks of radiosensitivity

Telomeres are the very ends of the chromosomes. They can be seen as natural double-strand breaks (DSB), specialized structures which prevent DSB repair and activation of DNA damage checkpoints. In somatic cells, attrition of telomeres occurs after each cell division until replicative senescence. In the absence of telomerase, telomeres shorten due to incomplete replication of the lagging strand at the very end of chromosome termini. Moreover, oxidative stress and accumulating reactive oxygen species (ROS) lead to an increased telomere shortening due to a less efficient repair of SSB in telomeres. The specialized structures at telomeres include proteins involved in both telomere maintenance and DNA repair. However when a telomere is damaged and has to be repaired, those proteins might fail to perform an accurate repair of the damage. This is the starting point of this article in which we first summarize the well-established relationships between DNA repair processes and maintenance of functional telomeres. We then examine how damaged telomeres would be processed, and show that irradiation alters telomere maintenance leading to possibly dramatic consequences. Our point is to suggest that those consequences are not restricted to the short term effects such as increased radiation-induced cell death. On the contrary, we postulate that the major impact of the loss of telomere integrity might occur in the long term, during multistep carcinogenesis. Its major role would be to act as an amplificator event unmasking in one single step recessive radiation-induced mutations among thousands of genes and providing cellular proliferative advantage. Moreover, the chromosomal instability generated by damaged telomeres will favour each step of the transformation from normal to fully transformed cells.     

甜柿巨大花粉萌发特征及辐射敏感性研究

以‘禅寺丸’（Diospyros kakiL.f)为试材,对巨大花粉萌发率,花粉管伸长,亲和性及辐射敏感性进行了研究。结果表明：（1）巨大花粉在培养基和柱头上正常萌发,不存在萌发及亲和性障碍;（2）巨大花粉萌发迟缓及低萌发率造成其与普通花粉受精竞争中处于劣势;（3）巨大花粉和普通花粉对^60Coγ-射线辐射敏感性有差异。巨大花粉的敏感性低于普通花粉,1200Gy为刺激巨大花粉萌发的适合剂量,同时可抑制普通花粉萌发,从而可相对提高巨大花粉的受精竞争力;（4）辐射延迟效应造成巨大花粉的萌发率在一定期间内有下降趋势。但自身的修复机制可部分恢复其生活力。     

Egr-1基因沉默对A549细胞放射敏感性的影响

目的:探讨Egr-1基因沉默对人肺腺癌A549细胞放射敏感性的影响。方法:选用A549细胞株作为研究对象,将其分成A、B、C三组,即空白对照组(只加入RPMI-1640培养)、阴性对照组(加入LV3-NC-sh RNA)、实验组(加入EGR1-homo-2294-sh RNA),采用慢病毒介导的sh RNA干扰技术使实验组细胞Egr-1基因沉默表达。利用荧光显微镜、自动化荧光定量细胞成像分析系统分析sh RNA转染,利用FQ-PCR分析Egr-1表达,再利用细胞克隆形成实验检测细胞放射敏感性参数的差异。结果:慢病毒介导的sh RNA成功转染阴性对照组、实验组细胞;空白对照组与阴性对照组Egr-1表达无差异(P0.05),实验组与空白对照组、阴性对照组比较Egr-1均受到明显抑制(P0.05);克隆形成实验中细胞放射敏感性参数D0、SF2实验组细胞与空白对照组、阴性对照组比较均存在明显差异(P0.05)。结论:Egr-1基因沉默使A549细胞放射敏感性降低,Egr-1表达可能与肿瘤细胞对放射的敏感性有关。