EGFR抑制剂对肿瘤的抑制和放疗增敏作用研究进展

放射治疗是治疗肿瘤的重要手段,提高放疗疗效仍是目前肿瘤放射治疗学领域亟待解决的难题。表皮生长因子受体（epidermal growth factor receptor ,EGFR）是ErbB家族成员之一,具有酪氨酸激酶活性,是一种重要的跨膜受体。EGFR 可介导细胞迁移、黏附、增殖、分化、凋亡,且与肿瘤的形成和恶化密切相关。EGFR 抑制剂具有放射增敏性,EGFR 抑制剂可通过影响细胞周期进展、DNA 损伤修复及抗血管形成等多种途径发挥放疗增敏作用。合理应用EGFR 抑制剂,将有效地提高恶性肿瘤放射敏感性,从而改善患者生活质量,减少肿瘤局部复发,延长患者的生存时间。      

上皮-间充质转化影响肿瘤放疗敏感性研究进展北大核心CSCD

放射治疗是目前治疗恶性肿瘤的重要手段之一,然而肿瘤细胞放射敏感性的下降是影响放疗疗效的主要原因。上皮-间充质转化(EMT)是一个复杂的生物学过程,能够赋予恶性肿瘤进展所必需的特征,如肿瘤起始特性、侵袭性、传播能力和对化疗及放疗的耐受,且EMT也可以由放射本身诱导,从而赋予肿瘤细胞辐射抗性。已有证据表明,抑制EMT可以增强肿瘤细胞的放射敏感性,但对涉及的分子机制及关键靶点、通路还缺乏整体的认识。本文回顾了近年来关于EMT在肿瘤放射治疗中作用的研究,重点关注了其中的信号通路、EMT诱导转录因子,有助于加深对EMT影响放疗敏感性的理解,为提高放射疗法的临床治疗效果提供思路。     

上皮-间充质转化影响肿瘤放疗敏感性研究进展

放射治疗是目前治疗恶性肿瘤的重要手段之一, 然而肿瘤细胞放射敏感性的下降是影响放疗疗效的主要原因。上皮-间充质转化(EMT)是一个复杂的生物学过程, 能够赋予恶性肿瘤进展所必需的特征, 如肿瘤起始特性、侵袭性、传播能力和对化疗及放疗的耐受, 且EMT也可以由放射本身诱导, 从而赋予肿瘤细胞辐射抗性。已有证据表明, 抑制EMT可以增强肿瘤细胞的放射敏感性, 但对涉及的分子机制及关键靶点、通路还缺乏整体的认识。本文回顾了近年来关于EMT在肿瘤放射治疗中作用的研究, 重点关注了其中的信号通路、EMT诱导转录因子, 有助于加深对EMT影响放疗敏感性的理解, 为提高放射疗法的临床治疗效果提供思路。     

食管癌放射敏感性相关基因及分子标志物研究进展

放疗是食管癌最主要的治疗手段之一,而放疗抵抗是食管癌放疗面临的最大困扰和障碍。放射敏感性是当今肿瘤放射生物学研究的重点和难点。多种基因可影响食管癌的放射敏感性,如果能筛选出放射敏感性的决定性基因,对于研究放射增敏、靶向治疗和预测放疗效果指导个体化治疗等具有重要意义。本文将从不同的信号转导通路入手就以往研究中食管癌放射敏感性相关的主要基因及重要分子标志物作一综述。     

表皮生长因子受体抑制剂与放疗联合应用的研究进展

为进一步提高肿瘤放射治疗的疗效,人们在不断寻找新方法。表皮生长因子受体（epidermal growth factor receptor,EGFR）抑制剂等新一代生物靶向治疗有很多研究进展。目前的研究结果显示EGFR抑制剂可以增加放疗的敏感性：EGFR活化后具有广泛的作用,能促进细胞的转录、增殖,影响细胞周期进程,诱导血管生成,在促进细胞的放射损伤修复方面起着重要作用。EGFR抑制剂能阻断细胞DNA损伤的修复,增加肿瘤细胞放射后的死亡。     

表皮生长因子受体抑制剂与放疗联合应用的研究进展

为进一步提高肿瘤放射治疗的疗效,人们在不断寻找新方法.表皮生长因子受体(epidermal growth factor receptor,EGFR)抑制剂等新一代生物靶向治疗有很多研究进展.目前的研究结果显示EGFR抑制剂可以增加放疗的敏感性:EGFR活化后具有广泛的作用,能促进细胞的转录、增殖,影响细胞周期进程,诱导血管生成,在促进细胞的放射损伤修复方面起着重要作用.EGFR抑制剂能阻断细胞DNA损伤的修复,增加肿瘤细胞放射后的死亡.     

肿瘤放射增敏剂临床应用现状

在恶性肿瘤放疗时试用放射增敏剂以提高肿瘤细胞的放射敏感性，进而改善恶性肿瘤放疗效果，是当前临床放射生物学的重要课题之一。已有若干放射增敏剂在完成临床前试验研究后过度到临床试用。虽然有的药物在临床试验后因毒性过大或未能得到预期效果而被放弃，但是各国学者仍在不懈努力中。增敏剂的应用必将进一步提高恶性肿瘤患者的放疗效果。     

吉非替尼对肺癌细胞株HCC827和H358放射敏感性的影响及其机制研究

背景与目的表皮生长因子受体(epidermal growth factor receptor,EGFR)是决定放疗效应的一个重要因素,其过表达或是下游通路的激活与包括非小细胞肺癌在内的肿瘤的放疗抵抗相关,因而阻断EGFR的信号通路可能会增强放疗敏感性。本研究旨在探讨小分子EGFR酪氨酸激酶抑制剂吉非替尼能否增加肺癌细胞株HCC827和H358的放疗敏感性及其可能的机制。方法选取HCC827和H358这两个非小细胞肺癌细胞株,分为单纯X线组和X线+吉非替尼两组。单纯X线组采用单纯X线照射,X线+吉非替尼组经1μmol/L吉非替尼作用24h后再行X线照射。克隆形成实验比较两株细胞中不同分组细胞放射敏感性,免疫荧光激光共聚焦显微镜观察X线照射后各时间点细胞核中的磷酸化H2AX(γ-H2AX)及EGFR焦点在细胞中的定位情况,Western blot法检测放疗后胞质胞核蛋白中EGFR的表达。结果克隆形成实验中,H358细胞实验组与对照组在各放疗剂量点的SF2值分别为0.355和0.433;HCC827细胞实验组与对照组在各放疗剂量点的SF2值分别为0.223和0.242,差别不明显。激光共聚焦显微镜观察照射4Gy后各时间段实验组H358细胞核中g-H2AX斑点相比对照组要多,且持续时间更长。而对照组和实验组的HCC827细胞g-H2AX斑点在各时间段并无明显差异;激光共聚焦显微镜观察照射4Gy后对照组H358的EGFR蛋白在1h内入核,而经吉非替尼处理后EGFR蛋白几乎不入核;实验组及对照组HCC827细胞的EGFR表达位置均在细胞质中,胞核中很少或者没有,可以认为并无入核现象;Western blot结果显示,H358细胞在经4Gy放射处理后有入核现象,而预先经吉非替尼处理后,EGFR蛋白几乎不在核内表达而仍位于细胞浆内。对于HCC827细胞,实验组及对照组的EGFR蛋白均在细胞质中表达,胞核中很少或没有,且两组并无明显差异。结论吉非替尼可增加肺癌细胞株H358的放射敏感性,这可能与其阻止放疗后EGFR入核、影响放疗后双链断裂(double strand break,DSB)修复有关;而对HCC827细胞无影响,可能与其放疗后EGFR不入核相关。     

EGFR核转位与DNA损伤修复研究进展

表皮生长因子受体(epidermal growth factor receptor, EGFR)在许多人类恶性肿瘤中过表达或突变,参与肿瘤发生和恶性转变过程,是目前分子靶向治疗的热点。多种肿瘤组织细胞核内发现高水平的 EGFR 表达,并且已经证实核EGFR 的高表达与患者总体生存率、无病生存率负相关[1]。核EGFR 在肿瘤的形成、发展、转移及治疗耐受中发挥着重要的生物学功能,特别是核EGFR 能促进细胞生成和 DNA 损伤修复[2]。因此,核EGFR 与DNA 之间的相互关系值得深入研究。本文将综述EGFR 核转位通路及其与DNA 损伤修复的关系,并分析核EGFR 潜在的分子治疗靶点。     

放射性粒子近距离治疗软组织肉瘤研究进展

近距离放疗以其独特的放射生物学及放射物理学特性成为软组织肉瘤治疗的重要手段,根据治疗时机分为术前放疗、术中放疗、术后放疗、单纯放疗,在提高患肢保存率及肉瘤局部控制率方面发挥了重要作用,但对治疗时机、治疗方式、植入剂量的选择仍存在争议.     

表皮生长因子受体在肿瘤放射治疗中的作用

表皮生长因子受体(EGFR)是调节肿瘤细胞生长的重要因子之一,在肿瘤的恶性生物学行为中发挥重要作用,与肿瘤放疗抗拒密切相关。EGFR过表达的肿瘤放疗效果差,易复发,预后不良。EGFR已成为肿瘤靶向治疗的重要靶标,抗EGFR治疗具有肿瘤放疗增敏作用。     

Inhibition of the EGFR with nanoparticles encapsulating antisense oligonucleotides of the EGFR enhances radiosensitivity in SCCVII cells

The aim of this study is to evaluate the effects of antisense epidermal growth factor receptor (EGFR) nanoparticles on cell survival and radiosensitivity in the head and neck squamous cell carcinoma cell line SCCVII. Experiments were performed using the murine head-and-neck tumor cell line, SCCVII. Nanoparticle encapsulated antisense EGFR oligonucleotides were combined with radiotherapy and the relative radiosensitivity of the cells was assessed in vitro by MTT and standard colony formation. The proportion of apoptotic cells and cell cycle stages were analyzed by flow cytometry. C3H/He mice with SCCVII tumor heterografts were treated with antisense-EGFR-nanoparticles or RT alone, or with combinations of concomitant and sequential therapy. The relative radiosensitivity of the tumors was assessed in vivo by growth delay assays. The SCCVII cells were resistant to anti-EGFR nanoparticles or radiation therapy alone, but a synergic inhibition effect was observed when the therapies were combined. When the SCCVII cells were pre-treated with 2 μg of antisense-EGFR nanoparticles for 24 h and X-irradiated (4 Gy), flow cytometry analysis revealed cell cycle arrest in G₁ phase and an increased proportion of apoptotic cells. Our results show that antisense EGFR nanoparticles enhance radiosensitivity by inhibition of EGFR-mediated mechanisms of radioresistance. Collectively, these findings may have therapeutic implications because EGFR inhibition may improve the therapeutic efficacy of radiation even in the tumor cells that are resistant to anti-EGFR therapy.     

Nuclear expression of epidermal growth factor receptor is a novel prognostic value in patients with ovarian cancer

The epidermal growth factor receptor (EGFR) has previously been detected in the nucleus of cancer cells and primary tumors. We have reported that EGFR translocates from the plasma membrane to the nucleus. Accumulation of nuclear EGFR is linked to increased DNA synthesis and proliferation; however, the pathological significance of nuclear EGFR is not completely understood. Here, we sought to determine the predictive value of EGFR for the survival of ovarian cancer patients, through the examination of 221 cases of ovarian cancer tissues by immunohistochemical analysis to determine nuclear EGFR expression. In addition, we also examined cyclin D1 and Ki‐67 through immunohistochemisty. Furthermore, we examined nuclear EGFR levels in ovarian cancer cell lines treated with EGF, and primary ovarian tumor tissue using immunofluorescence analysis. Nuclear fractions extracted from serum‐starved cells treated with or without EGF were subjected to SDS–PAGE and Western blot analyses. We found that 28.3% of the cohort had high levels of nuclear EGFR, while 22.5% had low levels of nuclear EGFR, and 49.2% were negative for nuclear EGFR. Importantly, there was an inverse correlation between high nuclear EGFR, cyclin D1, and Ki‐67 with overall survival (P < 0.01, P < 0.09, P < 0.041). Additionally, nuclear EGFR correlated positively with increased levels of cyclin D1 and Ki‐67, both indicators for cell proliferation. Our findings indicate a pathological significance of nuclear EGFR that might be important for predicting clinical prognosis of ovarian cancer patients. © 2008 Wiley‐Liss, Inc.     

吉非替尼对肺癌细胞株A549和H1975放射敏感度的影响及其机制

目的 本研究旨在探讨小分子表皮生长因子受体（epidermal growth factor receptor, EGFR）酪氨酸激酶抑制剂吉非替尼是否能增加肺癌细胞株A549和H1975的放疗敏感度及其机制。方法 选取两种非小细胞肺癌细胞株A549和H1975,分为单纯X线组和X线+吉非替尼组。单纯X线组采用单纯X线照射,X线+吉非替尼组经10 μmol/L吉非替尼作用24 h后行X线照射。两株细胞不同分组细胞,采用克隆形成实验检测放射敏感度,免疫荧光激光共聚焦显微镜观察X线照射后不同时间点细胞核中磷酸化H2AX（γ-H2AX）亮点在细胞中的定位情况,Western blot法检测放疗后胞质胞核蛋白中EGFR的表达。结果 克隆形成实验中,A549细胞X线+吉非替尼组在各放疗剂量点的SF2值（0.3475）低于单纯X线组（0.4833）;H1975细胞X线+吉非替尼组与单纯X线组在各放疗剂量点的SF2值分别为0.3094和0.3207,无明显差异。免疫荧光结果显示,照射4 Gy后各时间点X线+吉非替尼组A549细胞核中γ-H2AX亮点相比单纯X线多;单纯X线组和X线+吉非替尼组H1975细胞γ-H2AX亮点在各时间点无明显差异; Western blot结果显示,A549细胞经4Gy照射后EGFR有入核现象,而预先经吉非替尼处理再接受4Gy照射,EGFR蛋白绝大部分位于细胞质内;H1975细胞,单纯X线组和X线+吉非替尼组EGFR蛋白均在细胞质中表达,胞核中几乎没有,且两组无明显差异。结论 吉非替尼能增加肺癌细胞株A549的放射敏感度,可能与阻止放疗后EGFR入核进行双链断裂（double strand break,DSB）修复有关;对H1975细胞无影响,与其放疗后EGFR不入核相关。     

Epidermal growth factor receptor as a genetic therapy target for carcinoma cell radiosensitization.

BACKGROUND: Exposure of human cancer cells to ionizing radiation activates the epidermal growth factor receptor (EGFR), which, in turn, mediates a cytoprotective response that reduces the cells' sensitivity to ionizing radiation. Overexpression of a dominant-negative EGFR mutant, EGFR-CD533, disrupts the cytoprotective response by preventing radiation-induced activation of the receptor and its downstream effectors. To investigate whether gene therapy with EGFR-CD533 has the potential to increase tumor cell radiosensitivity, we introduced an adenoviral vector containing EGFR-CD533 into xenograft tumors in nude mice and evaluated the tumor response to ionizing radiation. METHODS: Xenograft tumors established from the human mammary carcinoma cell line MDA-MB-231 were transduced via infusion with the adenoviral vector Ad-EGFR-CD533 or a control vector containing the beta-galactosidase gene, Ad-LacZ. The transduced tumors were then exposed to radiation in the therapeutic dose range, and radiation-induced EGFR activation was assessed by examining the tyrosine phosphorylation of immunoprecipitated EGFR. Radiosensitization was determined in vitro by colony-formation assays. All statistical tests were two-sided. RESULTS: The transduction efficiency of MDA-MB-231 tumors by Ad-LacZ was 44%. Expression of EGFR-CD533 in tumors reduced radiation-induced EGFR activation by 2.94-fold (95% confidence interval [CI] = 2.23 to 4.14). The radiosensitivity of Ad-EGFR-CD533-transduced tumors was statistically significantly higher (46%; P<.001) than that of Ad-LacZ-transduced tumors, yielding a dose-enhancement ratio of 1.85 (95% CI = 1.54 to 2.51). CONCLUSIONS: Transduction of MDA-MB-231 xenograft tumors with Ad-EGFR-CD533 conferred a dominant-negative EGFR phenotype and induced tumor radiosensitization. Therefore, disruption of EGFR function through overexpression of EGFR-CD533 may hold promise as a gene therapeutic approach to enhance the sensitivity of tumor cells to ionizing radiation.     

EGFR抑制剂与肿瘤细胞放射敏感性

表皮生长因子受体(EGFR)在多种上皮来源的恶性肿瘤中存在过表达,其表达水平与肿瘤的放射敏感性呈负相关.大量研究表明,阻断EGFR表达的靶向抑制剂能够增加肿瘤细胞的放射敏感性,提高放射治疗的疗效,其机制可能与抑制细胞增殖、诱导细胞凋亡、干扰细胞周期分布、延长DNA的损伤修复有关.因此,运用EGFR抑制剂可以增强肿瘤细胞对放射的敏感性.     

NONO phase separation enhances DNA damage repair by accelerating nuclear EGFR-induced DNA-PK activation

Radioresistance is one of the main causes of cancer treatment failure, which leads to relapse and inferior survival outcome of cancer patients. Liquid-liquid phase separation (LLPS) of proteins is known to be involved in various biological processes, whereas its role in the regulation of radiosensitivity remains largely unknown. In this study, we characterized NONO, an RNA/DNA binding protein with LLPS capacity, as an essential regulator of tumor radioresistance. In vitro assay showed that NONO involved in DNA repair via non-homologous end joining (NHEJ) manner. NONO knockout significantly reduced DNA damage repair and sensitized tumor cells to irradiation in vitro and in vivo. NONO overexpression was correlated with an inferior survival outcome in cancer patients. Mechanically, NONO was associated with nuclear EGFR (nEGFR). Both irradiation and EGF treatment induced nEGFR accumulation, thereby increased the association between NONO and nEGFR. However, NONO was not a substrate of EGFR kinase. Furthermore, NONO promoted DNA damage-induced DNA-PK phosphorylation at T2609 by enhancing the interaction between EGFR and DNA-PK. Importantly, NONO protein formed high concentration LLPS droplets in vitro, and recruited EGFR and DNA-PK. Disruption of NONO droplets with LLPS inhibitor significantly reduced the interaction between EGFR and DNA-PK, and suppressed DNA damage-induced phosphorylation of T2609-DNA-PK. Taken together, LLPS of NONO recruits nuclear EGFR and DNA-PK and enhances their interaction, further increases DNA damage-activated pT2609-DNA-PK and promotes NHEJ-mediated DNA repair, finally leads to tumor radioresistance. NONO phase separation-mediated radioresistance may serve as a novel molecular target to sensitize tumor cell to radiotherapy.