金纳米簇放射治疗增敏作用的研究进展

目前恶性肿瘤的放射治疗疗效仍欠满意,放疗增敏剂是提高放疗疗效的有效手段。金纳米材料因其高原子序数可有效增加肿瘤细胞的放疗敏感性。金纳米簇因其更小的尺寸有更加优良的放射生物学、放射物理学特性。本文综述了金纳米簇特殊的放射生物学、放射物理学特性,并详细地介绍了其对外照射放疗、放射性核素治疗、X射线诱导的光动力治疗的增敏作用。     

放射性核素标记的金纳米颗粒在肿瘤诊疗中的研究进展

金纳米颗粒（GNPs）由于具有独特的物理化学性质,近年来被广泛应用于生物医学领域的研究。放射性核素标记的GNPs可用于疾病的单模态和多模态分子成像,同时,利用所标记放射性核素自身的特点、GNPs自身的光热效应和放射增敏作用,或进一步负载治疗剂后,还可用于疾病的诊疗一体化。笔者对放射性核素标记的GNPs的制备及其在肿瘤诊疗中的研究进展进行综述。     

金纳米粒子在肿瘤放疗中的研究进展

放疗在肿瘤的治疗中起着不可替代的作用，但由放疗引起的不良反应以及放疗过程中的肿瘤耐受问题仍未得到根本解决，因此放疗增敏显得尤为重要。金纳米粒子（GNPs）作为新型的纳米类放疗增敏制剂，因其较高的生物相容性受到了专家学者的广泛关注和研究。作为新型的纳米制剂，GNPs的理化性质，包括粒径、表面电荷和组装形态等能够影响体内代谢行为和肿瘤蓄积，因此导致放疗增敏率不同。笔者对近几年GNPs作为放疗增敏制剂的研究进展做进一步的总结和进展性汇报。     

Wort mannin对细胞的辐射增敏作用

目的　研究磷脂酰肌醇３激酶的特异性抑制剂Ｗｏｒｔｍａｎｎｉｎ（ ＷＴ） 对细胞的放射增敏效应,以探索放射增敏信号传导途径。方法　采用体外细胞克隆培养法观察不同浓度ＷＴ 在不同时间对３ 种细胞的放射增敏效应。结果　５０ μｍｏｌ／Ｌ以上浓度的ＷＴ 在照射后６ 小时内对ＬＰ３ 细胞呈较明显的增敏效应,剂量存活曲线Ｄ０ 增敏比在２ 左右;５０ μｍｏｌ／Ｌ ＷＴ 对ＨｅＬａ 细胞和ＳＰ／２０细胞均呈明确增敏效应。结论　ＷＴ是一种新型放射增敏剂。     

放射增敏机制的研究进展

目前约有70％的肿瘤需要进行放射治疗,但大多数肿瘤都存在一定的放射抗拒性,即便在精确放疗占主导地位的今天,临床上放疗野内复发的情况依旧存在。因此放射增敏剂成为了近年来的研究热点,而放射增敏机制的研究因其能为增敏剂的临床应用和新药的研制和开发提供理论依据而备受关注。现将放射增敏机制的相关研究进展综述如下。     

放射增敏剂在肿瘤治疗中的应用

放射治疗是治疗恶性肿瘤的重要手段之一。临床上常因正常组织耐受剂量的限制而不能给予肿瘤足够的照射剂量,而造成治疗失败,因此,如何提高肿瘤对射线的敏感性是临床肿瘤放疗面临的突出问题。放射增敏剂作为一种增强肿瘤放疗敏感性、提高放疗疗效的药物,通过增加辐射诱导的氧自由基及DNA损伤、调控放疗关键分子靶点以达到放射增敏目的。本文结合放射增敏剂在放射治疗中的应用,概述了放射增敏剂的发展现状及相关领域的研究进展,并对多种放射增敏剂的作用机制进行了简要综述,以期为进一步研究放射增敏调控的分子机制、促进放射增敏剂的研发,以及设计新的策略改善放射治疗结果提供帮助。     

苯并杂环化合物的放射增敏研究进展

放射增敏指的是通过一些化学物质(化学合成药物、中草药及其有效成分、生物制品等)的作用，能提高射线对肿瘤细胞，尤其是肿瘤组织中乏氧细胞的杀伤力，但对受照射的正常细胞影响不大。随着世界各国对放射增敏研究的不断深入，近年来陆续出现了一些新型的增敏剂。它们都是通过不同的作用机理分别起到了增敏的效果。其中最新和最有代表性的是苯并六元杂环的增敏剂。笔者主要介绍以苯并杂环为母体的衍生物的放射增敏研究进展。     

金纳米棒联合内放疗靶向性肿瘤治疗的研究进展

随着纳米技术的迅速发展,纳米科学与肿瘤医学相结合形成的纳米肿瘤医学是纳米科学中新兴的重要领域。金纳米棒（GNR）,一种棒状的纳米材料,由于其独特光学性质在生物医学领域展现出巨大应用潜力,尤其是GNR的热疗,放射增敏作用以及对肿瘤的靶向性治疗方面。GNR联合内放疗靶向性治疗肿瘤作为一种新兴疗法,对肿瘤的靶向性治疗取得了优异的疗效。本文对GNR联合内放疗靶向性肿瘤治疗的机制及其近年来的研究应用作一综述。     

15nm聚乙二醇保护的Au纳米颗粒对HepG2细胞的放射增敏作用

目的研究Au纳米颗粒对HepG2细胞的放射增敏作用。方法首先制备典型的15nm聚乙二醇（PEG）包裹的Au纳米颗粒,然后使用紫外可见分光光度计实时定量检测纳米颗粒的血浆稳定性,同时使用噻唑蓝法研究给药后24h和48h的细胞活性,最后,通过克隆形成实验研究不同浓度的Au纳米颗粒对HepG2细胞的放射增敏作用。结果PEG包裹的Au纳米颗粒具有较好的血浆稳定性,在24h及以后未见表面等离子共振吸收峰有明显的偏移。细胞活性实验表明,24h后,细胞的活性有所降低,但是48h后细胞的活性迅速恢复到90％。进一步研究克隆形成发现,Au纳米颗粒具有明显的放射增敏作用。结论15nmPEG包裹的Au纳米颗粒具有较高的血浆稳定性、较低的细胞毒性和较好的放射增敏作用。     

放射增敏剂——第四届国际肿瘤治疗中化学增敏防护药物研究会议上大会综述报告

自从在Key Biscayne 召开第三届国际肿瘤治疗中化学增敏防护药物研究会议以来,两年间在增敏剂的研究领域出现了许多新的进展,主要是:1.涌现出一些新的更有效的放射增敏剂和化学增敏剂。2.对放射效应的生化机理等增敏和防护机制有了更深入的理解。3.特别是提出了增敏药物如何更合理地     

甘氨双唑钠修饰纳米金对肺腺癌细胞A549的放射增敏研究

目的 探讨甘氨双唑钠修饰纳米金制备及放射增敏效果。方法 把甘氨双唑钠修饰到已连接聚乙二醇的纳米金上,纳米金粒径18 nm。利用扫描电镜观察肺腺癌(A549)细胞吞噬甘氨双唑钠-纳米金的现象。将培养的肺腺癌细胞分为甘氨双唑钠组、纳米金组、甘氨双唑钠-纳米金组、对照组(不加药组)。用四甲基偶氮唑盐比色法和克隆形成实验对肺腺癌(A549)细胞进行放射增敏的研究。结果 甘氨双唑钠-纳米金能进入细胞质和细胞核;浓度为0.003 mg/ml纳米金和甘氨双唑钠-纳米金没有明显的细胞毒性;甘氨双唑钠-纳米金组相对于甘氨双唑钠组、纳米金组、对照组,D₀、D_q出现了下调;接受2、4、6和8 Gy剂量照射后,甘氨双唑钠-纳米金组肺腺癌细胞的存活率与其他3组相比,均明显下降(F=4.8、14.5、5.7、7.6,P<0.05)。结论 甘氨双唑钠修饰的纳米金能增加肺腺癌细胞的辐射敏感性。     

Enhancement of radiosensitivity of melanoma cells by pegylated gold nanoparticles under irradiation of megavoltage electrons

Purpose: Gold nanoparticles (GNP) have significant potential as radiosensitizer agents due to their distinctive properties. Several studies have shown that the surface modification of nanoparticles with methyl polyethylene glycol (mPEG) can increase their biocompatibility. However, the present study investigated the radiosensitization effects of mPEG-coated GNP (mPEG-GNP) in B16F10 murine melanoma cells under irradiation of 6?MeV Electron beam.

Materials and methods: The synthesized GNP were characterized by UV-Visible spectroscopy, dynamic light scattering, transmission electron microscopy, and zeta potential. Enhancement of radiosensitization was evaluated by the clonogenic assay at different radiation doses of megavoltage electron beams.

Results: It was observed that mPEG-GNP with a hydrodynamic size of approximately 50?nm are almost spherical and cellular uptake occurred at all concentrations. Both proliferation efficiency and survival fraction decreased with increasing mPEG-GNP concentration. Furthermore, significant GNP sensitization occurred with a maximum dose enhancement factor of 1.22 at a concentration of 30 μM.

Conclusions: Pegylated-GNP are taken up by B16F10 cancer cells and cause radiosensitization in the presence of 6?MeV electrons. The radiosensitization effects of GNP may probably be due to biological processes. Therefore, the underlying biological mechanisms beyond the physical dose enhancement need to be further clarified.     

Improved dynamic response assessment for intra‐articular injected iron oxide nanoparticles

The emerging importance of nanoparticle technology, including iron oxide nanoparticles for monitoring development, progression, and treatment of inflammatory diseases such as arthritis, drives development of imaging techniques. Studies require an imaging protocol that is sensitive and quantifiable for the detection of iron oxide over a wide range of concentrations. Conventional signal loss measurements of iron oxide nanoparticle containing tissues saturate at medium concentrations and show a nonlinear/nonproportional intensity to concentration profile due to the competing effects of T₁ and T₂ relaxation. A concentration calibration phantom and an in vivo study of intra‐articular injection in a rat knee of known concentrations of iron oxide were assessed using the difference‐ultrashort echo time sequence giving a positive, quantifiable, unambiguous iron signal and monotonic, increasing concentration response over a wide concentration range in the phantom with limited susceptibility artifacts and high contrast in vivo to all other tissues. This improved dynamic response to concentration opens possibilities for quantification due to its linear nature at physiologically relevant concentrations. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.     

聚乳酸羟基乙酸载全氟溴辛烷-四氧化三铁包金纳米粒子双模态成像与光热治疗的体外研究

目的制备具有表面金壳以聚乳酸羟基乙酸(PLGA)为载体包载全氟溴辛烷(PFOB)和四氧化三铁(SPIOs)的纳米粒子,用于探究其体外超声显像和磁共振成像能力和光热杀伤肿瘤细胞效果。方法采用单乳化水包油(O/W)溶剂挥发法制备PFOB-SPIOs@PLGA纳米粒子,金种子生长法形成纳米粒子表面金壳制备;对其进行表征;通过CCK-8法评估纳米粒子的细胞毒性情况;采用超声和磁共振成像仪器观察纳米粒子的体外成像效果;近红外激光照射纳米粒子溶液观测升温效果;AM单染在激光共聚焦下观察光热杀伤肿瘤细胞效果。结果成功制备了PFOB-SPIOs@PLGA@Au纳米粒子,纳米粒子平均粒径(347±65.8)nm,粒径均一,分散性好;磁共振测得r2值为(465.23±30.39)mM-1s-1,具有体外磁共振T2成像效果;具有体外超声成像效果;近红外激光照射纳米粒子溶液10min最高温度可达45.2℃;CCK-8法检测纳米粒子对各组细胞存活率无明显影响。结论成功制备了粒径均一的PFOB-SPIOs@PLGA@Au纳米粒子,该纳米粒子具有较好的超声和磁共振T2体外成像效果和体外升温效果,且无明显细胞毒性。     

The use of theranostic gadolinium-based nanoprobes to improve radiotherapy efficacy

A new efficient type of gadolinium-based theranostic agent (AGuIX®) has recently been developed for MRI-guided radiotherapy (RT). These new particles consist of a polysiloxane network surrounded by a number of gadolinium chelates, usually 10. Owing to their small size (<5 nm), AGuIX typically exhibit biodistributions that are almost ideal for diagnostic and therapeutic purposes. For example, although a significant proportion of these particles accumulate in tumours, the remainder is rapidly eliminated by the renal route. In addition, in the absence of irradiation, the nanoparticles are well tolerated even at very high dose (10 times more than the dose used for mouse treatment). AGuIX particles have been proven to act as efficient radiosensitizers in a large variety of experimental in vitro scenarios, including different radioresistant cell lines, irradiation energies and radiation sources (sensitizing enhancement ratio ranging from 1.1 to 2.5). Pre-clinical studies have also demonstrated the impact of these particles on different heterotopic and orthotopic tumours, with both intratumoural or intravenous injection routes. A significant therapeutical effect has been observed in all contexts. Furthermore, MRI monitoring was proven to efficiently aid in determining a RT protocol and assessing tumour evolution following treatment. The usual theoretical models, based on energy attenuation and macroscopic dose enhancement, cannot account for all the results that have been obtained. Only theoretical models, which take into account the Auger electron cascades that occur between the different atoms constituting the particle and the related high radical concentrations in the vicinity of the particle, provide an explanation for the complex cell damage and death observed.Radiotherapy (RT) is the most commonly used non-surgical cancer therapy, designed to apply ionizing radiation at a sufficiently high cytotoxic dose to kill cells within the tumour tissue.¹ RT is primarily limited in its ability to deliver therapeutic doses to the target tumour volume whilst minimizing damage to the surrounding healthy tissue.² Numerous solutions have been proposed to overcome this issue, broadly falling into two main categories: (i) implementation of advanced RT techniques enabling intensity-modulated radiation fields [intensity-modulated radiation therapy (IMRT)] in order to more precisely adapt the dose to the tumour target; (ii) development of a new generation of therapeutic agents that sensitize cells to ionizing radiation (radiosensitizers) by improving dose efficacy with their high density and high atomic number (Z).³ High atomic number compounds may provide further benefit in the clinical setting by improving contrast properties for radiological imaging. This would allow monitoring of the radiosensitizing agent within the tumour. It would also facilitate precise defining of the tumour target to allow radiosensitization without affecting healthy tissue. These types of agents are known as “theranostic” agents.Classical imaging contrast agents based on iodine for CT and gadolinium complexes for MRI could all potentially prove effective theranostic agents. The use of inorganic nanoparticles for radiosensitization was first demonstrated by Hainfeld et al⁴ using 1.9-nm gold nanoparticles delivered systemically prior to irradiation in mice exhibiting EMT-6 mammary carcinomas. The authors reported 1-year survival in 86% of animals treated under these conditions compared with only 20% in those irradiated without gold particle injection. The interest in researching inorganic nanoparticles for the purposes of radiosensitization stems from the unique properties of these particles. Firstly, their innate high atomic number and density characteristics, lending them higher mass energy absorption coefficients than soft tissues;⁵ secondly, their multimodality offering the potential for theranostic applications, such as obtaining imaging functionality in addition to radiosensitizing properties;⁶ thirdly, their particular morphology that enables tailored biodistribution, with the potential for passive targeting due to the enhanced permeability and retention (EPR) effect.⁷ In recent studies, nanoparticles have been shown to induce a highly heterogeneous energy distribution at the subcellular scale, leading to complex cell damage near the particles.⁸ This could be a key factor in determining overall response.Despite the efficacy of gold particles as radiosensitizers, gold may not be the only suitable high atomic number theranostic candidate, given the lack of sensitivity afforded by CT classically using gold nanoparticles. The combination of MRI and RT technologies for a single image-guided treatment holds clear potential for improved clinical outcome, as emphasized by the development of new fused instruments combining these two modalities. In this context, gadolinium-based particles appear particularly interesting, since their MRI contrast properties are significantly higher than those of molecular complexes in current use, and they also present a strong and promising radiosensitizing effect.     

Gold nanoparticles as novel agents for cancer therapy

Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. This review introduces the field of nanotechnology with a focus on recent gold nanoparticle research which has led to early-phase clinical trials. In particular, the pre-clinical evidence for gold nanoparticles as sensitisers with ionising radiation in vitro and in vivo at kilovoltage and megavoltage energies is discussed.     

Gold nanoparticles in combination with megavoltage radiation energy increased radiosensitization and apoptosis in colon cancer HT-29 cells

Purpose: Gold nanoparticles (GNP) act as a radiosensitizer in radiation therapy. However, recent studies have shown contradictory evidence in terms of radiosensitization in the presence of GNP combined with X-ray megavoltage energy (MV) on different cell types. In this study, the effect of GNP on radiosensitization enhancement of HT-29 human colorectal cancer cells at MV X-ray energy was evaluated.

Materials and methods: The cytotoxicity and radiosensitization of GNP were evaluated in HT-29 human colorectal cancer cells by MTS-assay and multiple MTS-assay, respectively. Cellular uptake was assayed using graphite furnace atomic absorption spectrometry (GFAAS). Apoptosis and cell cycle progression were determined by an Annexin V-FITC/propidium iodide (PI) kit and PI/RNase solution with flow cytometry, respectively.

Results: Results showed that the cell viability of the HT-29 cells was not influenced by exposure to different concentrations of GNP (10–100 μM). GNP alone did not affect the cell cycle progression and apoptosis. In contrast, GNP, in combination with radiation (9?MV), induced more apoptosis. The interaction of GNP with MV energy resulted in a significant radiosensitization enhancement compared with irradiation alone.

Conclusion: It was concluded that GNP may work as bio-inert material on HT-29 cancer cells and their enhancement of radiosensitization may be due to increase in the absorbed irradiation dose.     

Biodegradable,polymer encapsulated,metal oxide particles for MRI‐based cell tracking

Metallic particles have shaped the use of magnetic resonance imaging (MRI) for molecular and cellular imaging. Although these particles have generally been developed for extracellular residence, either as blood pool contrast agents or targeted contrast agents, the coopted use of these particles for intracellular labeling has grown over the last 20 years. Coincident with this growth has been the development of metal oxide particles specifically intended for intracellular residence, and innovations in the nature of the metallic core. One promising nanoparticle construct for MRI‐based cell tracking is polymer encapsulated metal oxide nanoparticles. Rather than a polymer coated metal oxide nanocrystal of the core: shell type, polymer encapsulated metal oxide nanoparticles cluster many nanocrystals within a polymer matrix. This nanoparticle composite more efficiently packages inorganic nanocrystals, affording the ability to label cells with more inorganic material. Further, for magnetic nanocrystals, the clustering of multiple magnetic nanocrystals within a single nanoparticle enhances r₂ and ${\mathit{r}}_2^{*}$ relaxivity. Methods for fabricating polymer encapsulated metal oxide nanoparticles are facile, yielding both varied compositions and synthetic approaches. This review presents a brief history into the use of metal oxide particles for MRI‐based cell tracking and details the development and use of biodegradable, polymer encapsulated, metal oxide nanoparticles and microparticles for MRI‐based cell tracking. Magn Reson Med 73:376–389, 2015. © 2014 Wiley Periodicals, Inc.     

Applications of nanoparticles for diagnosis and therapy of cancer

During the last decades, a plethora of nanoparticles have been developed and evaluated and a real hype has been created around their potential application as diagnostic and therapeutic agents. Despite their suggestion as potential diagnostic agents, only a single diagnostic nanoparticle formulation, namely iron oxide nanoparticles, has found its way into clinical routine so far. This fact is primarily due to difficulties in achieving appropriate pharmacokinetic properties and a reproducible synthesis of monodispersed nanoparticles. Furthermore, concerns exist about their biodegradation, elimination and toxicity. The majority of nanoparticle formulations that are currently routinely used in the clinic are used for therapeutic purposes. These therapeutic nanoparticles aim to more efficiently deliver a (chemo-) therapeutic drug to the pathological site, while avoiding its accumulation in healthy organs and tissues, and are predominantly based on the “enhanced permeability and retention” (EPR) effect. Furthermore, based on their ability to integrate diagnostic and therapeutic entities within a single nanoparticle formulation, nanoparticles hold great promise for theranostic purposes and are considered to be highly useful for personalizing nanomedicine-based treatments. In this review article, we present applications of diagnostic and therapeutic nanoparticles, summarize frequently used non-invasive imaging techniques and describe the role of EPR in the accumulation of nanotheranostic formulations. In this context, the clinical potential of nanotheranostics and image-guided drug delivery for individualized and improved (chemo-) therapeutic interventions is addressed.Currently, in vivo molecular imaging comprises an important focus area of medical research. The rapidly evolving field of molecular imaging improves early disease detection and disease staging and enables image-guided therapy and treatment personalization. Furthermore, it provides essential information on the therapy efficacy. However, molecular imaging requires the use of molecular imaging probes to visualize and characterize biological processes at the cellular and molecular level.^1–5Recent advances in nanotechnology have led to the development of various nanoparticle formulations for diagnostic and therapeutic applications. Diagnostic nanoparticles aim to visualize pathologies and to improve the understanding of important (patho-) physiological principles of various diseases and disease treatments. Clinically, however, nanodiagnostics are only useful in a limited number of situations, due to the complex demands on their pharmacokinetic properties and elimination. Therefore, the majority of nanoparticle formulations currently used in the clinics is applied for therapeutic purposes. Therapeutic nanoparticles aim to improve the accumulation and release of pharmacologically active agents at the pathological site, increase therapeutic efficacy and reduce the incidence and intensity of side effects by reducing their localization in healthy tissues.^6–9 The intrinsic characteristics of nanoparticles hold great promise for integrating diagnostic and therapeutic agents into a single nanoparticle formulation, enabling their application for theranostic purposes, such as monitoring the biodistribution and target site accumulation, visualizing and quantifying drug release and longitudinally assessing the therapeutic efficacy. Such theranostic nanoparticles may be used for personalizing nanomedicine-based therapies by enabling patient preselection and by controlling therapeutic efficacy.^7–15In this review article, indications of current nanoparticle formulations for diagnostic and therapeutic applications and a brief overview of non-invasive imaging modalities will be given. In addition, the suitability of nanoparticles as molecular imaging probes and contrast agents to enhance disease diagnosis and treatment and their potential clinical application to facilitate personalized therapy interventions will be addressed and discussed.     

Pharmacological inhibition of EGFR tyrosine kinase affects ILK-mediated cellular radiosensitization in vitro

Purpose: Integrin-linked kinase (ILK) mediates signals from β integrins and links integrins to epidermal growth factor receptor (EGFR). Previous studies have identified an antisurvival effect of ILK in irradiated cells. The aim of this study was to evaluate the role of EGFR tyrosine kinase (tk) activity for ILK-mediated radiosensitization.

Materials and methods: Human FaDu squamous cell carcinoma (SCC) cells stably transfected with hyperactive ILK (ILK-hk) and ILK^fl/fl and ILK^?/? mouse fibroblasts were treated with the pharmacological EGFR-tk inhibitor BIBX1382BS without or in combination with single doses of X-rays. Clonogenic radiation survival, protein expression and phosphorylation (EGFR, v-akt murine thymoma viral oncogene homolog 1 (Akt), p42/44 mitogen-activated protein kinase), DNA-double strand break (DSB) repair measured by γH2AX foci, cell morphology and cell cycle distribution were examined.

Results: Expression of ILK-hk or ILK^fl/fl status resulted in significant radiosensitization relative to vector controls or ILK^?/?. Following BIBX1382BS, clonogenic survival of normal fibroblasts and vector controls remained unaffected while ILK-hk-related radiosensitization was significantly diminished. In contrast to BIBX1382BS, which did not affect DNA-DSB repair, ILK-hk-mediated radiosensitization was associated with reduced DNA-DSB repair. At 10 days after BIBX1382BS treatment, FaDu transfectants, in contrast to fibroblasts, showed reduced cell size, accumulation of G1 phase cells and reduced Akt-serine(S)473 phosphorylation.

Conclusions: Our findings confirm ILK as a cell type-independent antisurvival factor in irradiated cells, which actions in terms of radiosensitization critically depend on proper EGFR-tk activity.