基于纳米技术的肿瘤热放疗增敏的研究进展

放疗是治疗恶性肿瘤的重要手段之一,通过物理技术提高放疗的治疗增益比是现代精确放疗技术的发展方向。由于高能放射线固有的物理特性,通过放射物理技术提高放疗的治疗增益比必然遭遇瓶颈。应用热疗增敏放疗,可提高肿瘤细胞的放射敏感性、降低肿瘤细胞的放射抵抗性,在放疗中具有非常重要的临床实用价值。具有良好的生物相容性和安全性的多功能纳米材料在肿瘤光热疗治疗研究中已经受到广泛的关注并展现出了良好的潜力,将纳米热疗技术作为增敏载体结合放疗,在热放疗增敏的同时,高原子序数纳米材料亦可单独作为放疗增敏载体,使肿瘤热疗和放疗二者协同增效,有可能克服目前制约肿瘤放疗的诸多难题,为推动放疗的进一步发展提供了新的发展机遇。本文对基于纳米技术的肿瘤热放疗增敏的研究进展进行综述。      

拮抗IAP在肿瘤放疗增敏中的应用

凋亡抑制蛋白（inhibitor of apoptosis proteins,IAP）是一类内源性细胞凋亡抑制因子,其过度表达与肿瘤发生密切相关。尽管放疗能够激活肿瘤细胞中一系列复杂的信号转导途径,导致肿瘤细胞死亡,然而,肿瘤细胞中高表达IAP会诱导很多肿瘤耐放射。因此,以IAP为靶点的拮抗剂治疗可能为放疗增敏开辟新的途径。     

西妥昔单抗放疗增敏作用研究进展

0引言表皮生长因子受体(Epidermal growth factorreceptor,EGFR)是erbB酪氨酸受体家族的成员之一。该家族共有4个成员,即EGFR(HER1、HER2、HER3和HER4)。其结构相似,分为三部分:胞外配体结合区、跨膜区及胞内区。当EGFR与其配体结合,启动一系列下游级联反应,从而介导细胞分化、生存、迁徙、侵袭、黏附和转移等一系列过程。针对EGFR靶点的药物主要分为两类:一类是作用于受体胞内区的小分子酪氨酸激酶抑制剂(TKI),如ZD1839(吉非替尼)、OSI-774(埃罗替尼)等;另一类是作用于受体胞外区的单克隆抗体(Mab),如I MG-C225(西妥昔单抗)。EGFR高表达被证实与放疗抗拒有关[1],C225是人鼠嵌合型的IgG1单克隆抗体,可以特异性地与EGFR结合,阻断其与配体的结合,从而阻断整个下游信号途径的传导而发挥抗肿瘤作用。本文就C225在放疗中的作用作一综述,并初步探讨其可能的作用机制。     

金纳米颗粒放射增敏机制研究进展

摘 要：金纳米颗粒（gold nanoparticles,GNPs）以其独特的理化特点而广泛应用于肿瘤诊疗研究。GNPs生物相容性好,原子序数高,对kV级射线的光电效应截面比软组织高,能提高肿瘤组织的局部能量沉积,是一种有良好应用前景的放射增敏剂。MV级射线通过康普顿散射与GNPs相互作用,但其截面远远低于kV级射线与GNPs作用的截面,因此GNPs对其增敏效应不如kV级射线显著。GNP诱导细胞内活性氧簇（reactive oxygen species,ROS）增加,引起DNA损伤,诱导细胞凋亡。GNPs通过调控细胞周期进程,使细胞阻滞在G2/M期,增强细胞的放射敏感性。此外,GNPs还能引起细胞内自噬体增多和溶酶体降解能力减弱并最终引起细胞死亡。GNPs也可以抑制缺氧诱导因子1α（hypoxia inducible factor-1α,HIF-1α）和血管内皮生长因子（vascular endothelial growth factor,VEGF）mRNA表达,使裸鼠肝癌血管形态趋于正常。     

参脉注射液在食管癌放疗增敏中的作用

目的 观察参脉注射液在食管癌放疗过程中的增敏作用。方法 60例食管癌患者随机分两组单纯放疗组（对照组）、放疗＋参脉组（治疗组）,治疗组放疗同时应用参脉注射液60 ml+5%葡萄糖注射液250 ml,静滴,每日一次,连续使用4周。结果 在放疗剂量达60 Gy时,治疗组有效率为96%,单纯放疗组为73.3%,两者比较,差异有统计学意义（P=0.026）;两组的安全性、肿瘤抑制率及生活质量比较差异均无统计学意义。结论 在食管癌放射治疗过程中应用参麦注射液,可以起到放疗增敏,提高疗效的作用。     

金纳米颗粒在肿瘤放射增敏中的研究进展

金纳米颗粒(AuNPs)以其独特的理化性质及良好的生物相容性在生物医药方面广泛应用,其中金纳米颗粒肿瘤放射增敏作用是目前研究热点。大量体、内外研究证实AuNPs具有放射增敏效果,但AuNPs放射增敏相关机制仍有待进一步研究,目前普遍认为增敏主要由AuNPs促进肿瘤细胞由放疗不敏感期(G₀+G₁期)转为放疗敏感期(G₂+M期)所致。影响AuNPs放射增敏效果的因素有很多,其中包括AuNPs粒径大小及其表面修饰和微观分布、放射线能量及剂量大小和肿瘤细胞类别等。此外值得注意的是,AuNPs用于肿瘤放射增敏的同时也要关注它的安全性。目前已开展了AuNPs有关临床试验,尚需继续进行AuNPs放射增敏的研究才能实现真正的临床转化。     

高氧液静脉输注在肿瘤放疗增敏应用中的研究现状

放射治疗是恶性肿瘤的主要有效治疗方法之一,然而多数肿瘤的放射治疗效果并不理想,造成这些肿瘤放射敏感性差的一个重要原因,就是肿瘤组织内存有相当数量的乏氧细胞所致。因此,直接有效地提高恶性肿瘤组织内的氧分压,改善肿瘤组织细胞的氧供状态,对于增加肿瘤组织细胞的放射敏感性有着十分重要的临床意义[1]。高氧液静脉输注,是近年来出现的1种改善肿瘤细胞乏氧状态简便有效而又安全的方法,其在实现放射治疗增敏的同时,还具有减轻放射性损伤的作用,同时还可以治疗放射治疗的并发症,故越来越受到肿瘤临床医学专家们的重视和认可[2]。     

康宁口服液在晚期食道癌放疗中增敏作用之研究

目的　观察康宁口服液与放疗同时进行对中晚期食管癌的放疗增效作用。方法　 1997年 3月至 1998年10月 ,采用随机分组对 46例中晚期食管癌进行放疗与康宁口服液同步治疗 (A组 ) ,并与 46例单纯放射治疗组 (B组 )的结果进行对比。结果　近期疗效 :A组有效率 93 .5 % ,B组有效率 78.3 %。两组比较有显著性差异。 1、2年生存率 ,康宁合并放疗组为 71.7%、60 .9% ,而单放组为 5 4.3 %、3 9.1%。结论　康宁口服液配合放射治疗食管癌可提高疗效并有放疗增敏作用     

细胞色素C在食管癌放疗中增敏的研究

目的　探讨细胞色素C在食管癌放疗中的增敏作用。方法　将 10 2例经病理确诊的食管癌病人随机分为两组 (治疗组 5 2例、对照组 5 0例 ) ,两组采用相同的放射野、放射总量和分割剂量 ,治疗组在放疗同时给与细胞色素C静推 ,对照组采用单纯放疗。采用肿瘤局部控制率 (CR +PR)作为疗效的评价标准。结果　治疗组在放疗 4 0Gy时较对照组明显为优 (6 3 5 %比 2 8 0 % ,P <0 0 1) ,放疗 6 5Gy时的有效率亦较对照组明显提高 (98 1%比 86 0 % ,P <0 0 5 )。结论　细胞色素C对食管癌放疗具有显著的增敏作用 ,且未见副作用。本研究只限于临床近期疗效的比较 ,是否可以提高远期疗效 ,尚有待进一步随访观察。     

金纳米颗粒在肿瘤放射增敏中的相关研究进展

纳米技术被广泛用于肿瘤的诊断和治疗中,逐渐成为研究的热点。在纳米材料中金纳米颗粒由于低毒性、较好的生物相容性及增强的穿透滞留效应等独特优势在肿瘤诊断、成像、治疗等领域受到广泛关注。目前多项研究表明金纳米颗粒可作为理想的放射增敏剂,研究其在体内、外放射增敏作用将对纳米医学的临床转化具有重要意义。     

Dose-rate dependence of heat radiosensitization

The dose rate dependence of heat radiosensitization was studied using rat astrocytoma cells in culture and a clinically relevant protocol of heat dose and heat radiation sequence. Cells were treated with a minimally toxic heat dose of 43°C for 30 minutes, after which they were irradiated with varying doses of radiation at dose rates ranging from 0.567 to 300 cGy/min. This heat dose substantially reduced the extrapolation number ($\text{n}\text{?}$), but had little effect on D_o of the radiation survival curve at dose rates of 50 cGy/min or greater. At dose rates less than 10 cGy/min, 43°C for 30 min had little a on $\text{n}\text{?}$ and only for the lowest dose rate studied (0.567 cGy/min) was there a significant reduction in D_o (60%). The thermal enhancement ratio did not vary inversely with radiation dose rate over the dose rate range studied but, instead, was maximal at the two dose rate extremes (0.567 and 300 cGy/min). These data demonstrate that a clinically relevant heat dose enhances very low dose rate, as well as high dose rate, ionizing radiation, but suggest that little benefit is to be gained from using dose rates intermediate between conventional radiotherapeutic high dose rates or dose rates representative of interstitial implants.     

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.     

The heat shock proteins as targets for radiosensitization and chemosensitization in cancer

The heat shock proteins (HSPs) represent a class of proteins which are induced under physiologic stress to promote cell survival in the face of endogenous or exogenous injury. HSPs function predominantly as molecular chaperones, maintaining their "client" proteins in the correct conformational state in order to withstand a biologic stressor. Elevated HSP expression is also found in a range of pathologic conditions, notably malignancy. Cancer cells exploit the pro-survival phenotype endowed by HSPs to bolster their proliferative potential. Consequently, developing means of abrogating HSP expression may provide a way to render cancer cells more susceptible to radiation or chemotherapy. Here, we review the members of the HSP class and their roles in malignancy. We focus on attempts to target these proteins, particularly the small HSPs, in developing potent radiation and chemotherapy sensitizers, as well as proposed mechanisms for this sensitization effect.     

Implantable biodegradable polymers for IUdR radiosensitization of experimental human malignant glioma

Purpose: The potential of halogenated pyrimidines for the radiosensitization of human malignant gliomas remains unrealized. To assess the role of local delivery for radiosensitization, we tested a synthetic, implantablebiodegradable polymer for the controlled release of 5-iodo-2-deoxyuridine (IUdR) both in vitro and in vivo and the resultant radiosensitizationof human malignant glioma xenografts in vivo.Materials and methods: In vitro: To measure release, increasing (10%, 30%, 50%) proportions (weight/weight) of IUdR in the polyanhydride [(poly(bis(p-carboxyphenoxy)-propane) (PCPP) :sebacic acid (SA) (PCPP : SA ratio 20 : 80)] polymer discs were incubated (1 ml phosphate-buffered saline, 37° C). The supernatant fractions were serially assayed using high performance liquid chromatography. To measure modulation of release,polymer discs were co-loaded with 20 Ci 5-125-iodo-2-deoxyuridine (125-IUdR) and increasing (10%, 30%, or 50%) proportions of D-glucose. To test radiosensitization, cells (U251 human malignant glioma) were sequentially exposed to increasing (0 or 10 M) concentrations of IUdR and increasing (0, 2.5, 5.0, or 10 Gy) doses of acute radiation. In vivo: To measure release, PCPP : SA polymerdiscs having 200 Ci 125-IUdR were surgically placed in U251 xenografts (0.1—0.2 cc) growing in the flanksof nude mice. The flanks were reproducibly positioned over a collimated scintillation detector and counted. To measure radiosensitization, PCPP : SApolymer discs having 0% (empty) or 50% IUdR wereplaced in the tumor or contralateral flank. After five days, the tumors were acutely irradiated (500 cGy × 2 daily fractions).Results: In vitro: Intact IUdR was released from the PCPP : SA polymer discs in proportion to the percentage loading. After 4 days the cumulative percentages of loaded IUdR that were released were 43.7 $plusmn; 0.1, 70.0 ± 0.2, and 90.2 ± 0.2 (p < 0.001 ANOVA) for the 10, 30, and 50% loadings. With 0, 10, 30,or 50% D-glucose co-loading, the cumulative release of 125-IUdR from PCPP : SA polymers was 21, 70, 92, or 97%(p < 0.001), respectively, measured 26 days after incubation.IUdR radiosensitized U251 cells in vitro. Cell survival (log₁₀) was – 2.02 ± 0.02 and – 3.68± 0.11 (p < 0.001) after the 10 Gy treatment and no (control) or 10 M IUdR exposures, respectively. In vivo: 125-IUdR Release: The average counts (log₁₀ cpm ± SEM) (hours after implant) were 5.2 ± 0.05 (0.5), 4.3 ± 0.07 (17), 3.9 ± 0.08 (64), and 2.8 ± 0.06 (284). Radiosensitization: Afterintratumoral implantation of empty polymer or intratumoral 50%IUdR polymer, or implantation of 50% IUdR polymers contralateral to tumors, the average growth delays of tumors to4 times the initial volumes were 15.4 ± 1.8, 20.1 + 0.1,and 20.3 + 3.6 (mean + SEM) days, respectively (p = 0.488one-way ANOVA). After empty polymer and radiation treatments,no tumors regressed and the growth delay was 31.1 + 2.1 (p = 0.046 vs. empty polymer alone) days. After implantation of50% IUdR polymers either contralateral to the tumors orinside the tumors, followed by radiation, tumors regressed; growth delays to return to the initial average volumes of 14.0+ 3.6 or 24.2 + 0.2 (p < 0.01) days, respectively.Conclusions: Synthetic, implantable biodegradable polymers hold promise for the controlled release and local delivery ofIUdR for radiosensitization of gliomas.     

In vitro and in vivo radiosensitization induced by hydroxyapatite nanoparticles

Background

Previous study showed that hydroxyapatite nanoparticles (nano-HAPs) inhibited glioma growth in vitro and in vivo; and in a drug combination, they could reduce adverse reactions. We investigated the possible enhancement of radiosensitivity induced by nano-HAPs.

Methods

In vitro radiosensitization of nano-HAPs was measured using a clonogenic survival assay in human glioblastoma U251 and breast tumor brain metastatic tumor MDA-MB-231BR cells. DNA damage and repair were measured using γH2AX foci, and mitotic catastrophe was determined by immunostaining. The effect of nano-HAPs on in vivo tumor radiosensitivity was investigated in a subcutaneous and an orthotopic model.

Results

Nano-HAPs enhanced each cell line''s radiosensitivity when the exposure was 1 h before irradiation, and they had no significant effect on irradiation-induced apoptosis or on the activation of the G₂ cell cycle checkpoint. The number of γH2AX foci per cell was significantly large at 24 h after the combination modality of nano-HAPs + irradiation compared with single treatments. Mitotic catastrophe was also significantly increased at an interval of 72 h in tumor cells receiving the combined modality compared with the individual treatments. In a subcutaneous model, nano-HAPs caused a larger than additive increase in tumor growth delay. In an orthotopic model, nano-HAPs significantly reduced tumor growth and extended the prolongation of survival induced by irradiation.

Conclusions

These results show that nano-HAPs can enhance the radiosensitivity of tumor cells in vitro and in vivo through the inhibition of DNA repair, resulting in an increase in mitotic catastrophe.     

Role of nuclear protein denaturation and aggregation in thermal radiosensitization

Hyperthermia at temperatures above 41°C denatures a set of thermolabile cellular proteins located in all parts of the cell. Non-histone nuclear proteins, including those comprising the nuclear matrix, appear to be particularly thermolabile. Heating isolated nuclear matrices of Chinese hamster lung (CHL) V79 cells to 46°C at 1°C/min results in approximately 15% denaturation. Protein unfolding during denaturation exposes buried hydrophobic residues, which increases protein–protein interactions and results in the co-aggregation of denatured thermolabile proteins and native, aggregative-sensitive nuclear proteins. This aggregated protein, the majority of which is native, is insoluble and resistant to extraction during isolation of nuclei and is responsible for the increased protein content, usually expressed as an increased protein:DNA ratio, of nuclei isolated from heated cells. A large fraction of the aggregated protein is found to be associated with the nuclear matrix, distributed throughout the fibre network and nucleolus. Three general consequences of nuclear protein denaturation and aggregation of relevance to cellular damage are: (1) protein (enzyme) inactivation, both direct inactivation of thermolabile proteins and indirect inactivation due to co-aggregation; (2) reduced accessibility and altered physical properties of DNA due to masking by aggregated protein; and (3) protein redistribution into and out of the nucleus. Functional impairment of the nucleus appears to be due to one or a combination of these basic mechanisms.     

纳米二氧化钛和纳米氧化锌的Ames试验

目的：研究纳米二氧化钛、纳米氧化锌两种纳米光催化材料的潜在致突变性。方法：采用Ames试验平板掺入法,计数TA97,TA98,TA100,TA102四种菌株分别在纳米二氧化钛及纳米氧化锌5个不同浓度下的回变菌落数。结果：纳米二氧化钛、纳米氧化锌材料各剂量组均未引起测试菌株回变菌落数的明显增加。Ames试验结果均为阴性。结论：纳米二氧化钛、纳米氧化锌在实验剂量范围内未见致突变性。     

Transfection of human tumour cells with Mre11 siRNA and the increase in radiation sensitivity and the reduction in heat-induced radiosensitization

Double-strand DNA breaks (DSBs) are potentially lethal DNA lesions induced by ionizing radiation. In eukaryotes, DSBs can be repaired by homologous recombination (HR) or non-homologous end-joining (NHEJ). DNA repair protein Mre11 participates in both the NHEJ and HR DNA repair pathways. Hyperthermia has been used clinically as a radiosensitizer. However, the mechanisms by which radiosensitization is induced by hyperthermia, especially moderate hyperthermia (41°C) are not fully understood. Previous studies suggest that 41°C reduces the nuclear Mre11 protein level in a manner that correlates with heat-induced changes in radiation sensitivity. Therefore, siRNA technology was used in the present study to reduce Mre11 gene expression to determine if reduced Mre11 protein levels induced radiosensitization and if such radiosensitization is similar to that induced by moderate hyperthermia. The results show that (1) the cellular level of the Mre11 protein was reduced about 60 ± 18% by a 24-h treatment with siRNA. Results from the Mre11 protein turnover assay showed a half-life of 11.6 ± 0.5?h for the Mre11 protein, which is consistent with reduction in protein level in 24?h after Mre11 siRNA treatment assuming a delay of 4–8?h to reduce RNA levels. After 48?h in siRNA, cellular Mre11 protein levels increased to approximately pretreatment levels. NSY cells were sensitized to ionizing radiation after 24?h of treatment with Mre11 siRNA. Two hours at 41°C did not increase the radiation sensitivity of cells with a reduced Mre11 protein level following a 24-h siRNA treatment. These data support the conclusion that the DSB repair protein, Mre11, appears to be a target for radiosensitization by moderate hyperthermia.     

盐霉素增加鼻咽癌CNE-2细胞放疗敏感性的实验研究

目的:探讨盐霉素（Sal）对鼻咽癌CNE-2细胞的放疗增敏作用及其可能的机制。方法:CCK8测定不同浓度盐霉素、不同剂量放疗及联合应用对CNE-2细胞增殖的抑制作用;平板克隆实验观察盐霉素联合放疗后细胞的克隆形成率;Hoechst33258染色观察细胞凋亡;流式细胞术检测细胞凋亡率及细胞周期的变化情况。结果:CCK8结果显示,盐霉素和放疗对鼻咽癌CNE-2细胞的生长有显著的抑制作用,呈浓度和剂量依赖性,且联合组抑制作用强于单纯药物组或放疗组。平板克隆实验显示盐霉素联合放疗后能显著降低细胞的克隆形成率;Hoechst33258染色显示盐霉素联合放疗治疗后细胞凋亡现象更明显;细胞流式术检测显示联合组较单纯药物组或放疗组凋亡率增加,盐霉素对放疗具有增敏作用。药物组和放疗组均能使G2/M期细胞比例增加,两者联合效果更明显。结论:盐霉素能增加人鼻咽癌CNE-2细胞的放疗敏感性,其作用机制可能与周期阻滞及其凋亡诱导相关。