TRAIL抗肿瘤的优化研究进展

肿瘤坏死因子相关凋亡诱导配体(TRAIL)是肿瘤坏死因子(TNF)超家族成员。因其具有选择性杀伤绝大多数肿瘤细胞而对人体正常细胞无明显细胞毒性的特性而被广泛研究,并已有相关制剂进入临床抗肿瘤研究。虽然TRAIL在体内外实验中均展现出良好的抗肿瘤效果,前期临床研究结果也表明了其相对安全性,但其临床抗肿瘤效果却不太理想。总结其临床效果差的主要原因,可能有体内稳定性差、肿瘤靶向性差、肿瘤获得性耐受等。对于TRAIL临床疗效差的问题,许多针对性的研究也相应开展,目前已有不少报道表明通过一些合理的优化方式有可能解决上述问题。我们从TRAIL的基因治疗、重组蛋白及死亡受体抗体治疗、TRAIL联合用药治疗及其他治疗方法等方面,简要综述TRAIL在抗肿瘤方面的应用及其应用中的优化。     

一种溶酶体靶向的原位自组装短肽设计及抗肿瘤活性研究

肿瘤已成为威胁人类生命的一大杀手,目前主要采用手术和放、化疗等手段进行治疗,但由于放、化疗的细胞选择性差、毒副作用明显且易引起肿瘤细胞产生耐受(/药)性,不利于肿瘤的持续治疗,因此亟待研发具有定向定位优势、毒副作用低的新型靶向药物.原位自组装多肽能识别肿瘤部位的特异性高表达物质,在肿瘤部位靶向性聚集形成稳定的纳米结构,实现精准和高效治疗,有望成为一种新型的抗肿瘤药物.本研究基于多肽原位自组装的设计理念,利用溶酶体内组织蛋白酶L的催化活性,设计了靶向溶酶体且能够原位自组装的多肽分子Fmoc-FFRIKFERQ-OH,研究了该分子的自组装特性及抗肿瘤活性.结果显示,在体外酸性条件下,组织蛋白酶L能精准切割Fmoc-FFRIKFERQ-OH分子,其酶切产物FmocFFR-OH自组装形成长纳米纤维结构,对肿瘤细胞A375和SH-SY5Y均具有较好的杀伤作用.该分子通过靶向溶酶体杀伤肿瘤细胞且对正常细胞的毒性较低,有望成为一种新型的抗肿瘤药物.     

多西紫杉醇白蛋白微球的制备及优化实验研究

多西紫杉醇(DT)是唯一应用于临床治疗肿瘤的紫杉醇的衍生物,其水溶性差,制剂中需要加入有机溶剂和助溶剂,而有机溶剂和助溶剂具有刺激性。为减少多西紫杉醇制剂的刺激性,本实验通过去溶剂化—化学交联法制备水溶性多西紫杉醇白蛋白微球。对制备过程中的重要影响因素进行考察,并通过Design-expert软件进行数据优化,最终得优化条件:白蛋白浓度为35 mg.mL-1,DT浓度为1.03 mg.mL-1,乙醇和水的比例为3∶1,乙醇的滴加速度为0.73 mL.min-1,搅拌时间为12 h,0.2%戊二醛与白蛋白的交联比为2∶1。得到的多西紫杉醇白蛋白微球粒径为185 nm,载药量为14.4%,成功的解决了其水溶性,为接下来的动物实验、临床应用提供了良好的基础。     

叶酸受体介导的负载紫杉醇纳米药物输送系统的制备

目的:构建靶向肿瘤组织的药物输送系统,是解决目前临床肿瘤化疗问题的有效途径之一.我们拟开展叶酸受体介导的负载紫杉醇纳米药物输送系统的制备及其表征.方法:以丁二酰化肝素为载体,通过碳二亚胺法将叶酸和丁二酰化肝素连接,制备肝素-叶酸偶联物,然后通过物理方法将紫杉醇包裹在肝素-叶酸偶联物中,在水溶性条件下体系自组装成肝素-叶酸-紫杉醇纳米粒.应用核磁共振氢谱(1H NMR),动态光散射(DLS)和扫描电子显微镜(SEM)对构建的纳米药物结构进行表征,同时观测其在水溶性条件下的自组装行为.结果:成功制备了肝素-叶酸-紫杉醇纳米药物输送系统,检测表明药物系统带有8.5％(w/w)的叶酸并负载9.6％(w/w)的药物,SEM检测表明形成了球状的纳米颗粒,DLS表明粒子的粒径在了86 nm左右.结论:我们成功制备了叶酸受体介导的负载紫杉醇的纳米药物输送系统,在进一步开展的生物活性的检测中,希望通过叶酸受体的靶向作用,引导药物定向分布在肿瘤组织,从而提高化疗药物的治疗效果同时降低其对正常细胞的毒副作用,为开发新型靶向药物输送系统提供基础.     

以整合素αvβ3为靶点的肿瘤靶向制剂

整合素αvβ3在肿瘤细胞及肿瘤血管内皮细胞中高表达,RGD序列作为其配体,可与其进行特异性结合,为肿瘤的诊断和靶向治疗提供了理论基础。RGD诊断试剂的前期研究和临床试验数据表明其具有良好的肿瘤组织靶向性。RGD-纳米抗肿瘤制剂(RGD-脂质体、RGD-胶束和RGD-纳米粒)在体外可提高细胞对药物的吸收率,增强细胞毒性;在动物移植瘤模型中,能更好地抑制肿瘤的生长,延长了动物的生存时间。在肿瘤发病率居高不下,治疗手段和疗效都较为有限的今天,RGD靶向制剂在肿瘤诊断和治疗中所具有的优势值得特别关注。     

纳米递送载体在口服抗肿瘤药物给药系统中的应用

化疗治疗是目前肿瘤治疗的主要手段之一,但大部分化疗药物具有水溶性低、肠道壁通透性差、易受到P-糖蛋白(P-gp)外排的性质,极大限制了其开发为口服制剂。基于纳米技术的药物递送系统在口服抗肿瘤药物的递送中具有独特的优势,表现出良好的应用前景。笔者将深入探讨纳米递送载体在药物口服递送中所面临的生理障碍以及克服生理屏障的方法,并对聚合物胶束、脂质体、纳米粒等纳米体载体在抗肿瘤药物口服递药系统的应用进行了详细的综述。     

叶酸偶联牛血清白蛋白负载卡铂和紫杉醇肿瘤靶向纳米粒制备、表征及体外释放性能评价

紫杉醇（Paclitaxel,商品名Taxol）是一种在红豆杉科(Taxaceae L.)红豆杉属(Taxus L.)生长缓慢的常绿乔木中分离提取的天然化合物。卡铂和紫杉醇均是目前临床上使用率很高的抗肿瘤药物,并在临床上经常配伍使用治疗不同的癌症。本研究以叶酸偶联的牛血清白蛋白作为药物载体,采用去溶剂技术制备了叶酸靶向卡铂—紫杉醇的白蛋白纳米粒,并研究了靶向制剂体外释放性质。研究结果表明：卡铂—紫杉醇白蛋白纳米粒平均粒径为199.4 nm,Zeta电位为-30.90 mV。卡铂包封率为91.4%;紫杉醇包封率为56.1%,药物总载药量为21%。其冻干粉复溶12 h后各项数据未发生较大变化,说明其具有良好的稳定性。体外释放结果表明叶酸—卡铂—紫杉醇白蛋白纳米粒与卡铂和紫杉醇原粉比较具有明显的缓释效果,体外释药时间可达120 h。     

壳聚糖衍生物及其胶束：特性、功能化修饰和在药物传递系统中的应用

壳聚糖是一种天然多糖,具有无毒、可生物降解、生物相容性等诸多优点,但水溶性差的自身特点限制了其在药剂学中的应用,而其经合理的结构设计、修饰和优化,可获得性能良好的两亲性壳聚糖衍生物,这些衍生物在水溶液中能自组装成具有良好药物传输性能（如载药量、稳定性、刺激敏感性、靶向性等）的胶束,并被广泛应用于构建药物传递系统,以改善药物的溶解性、靶向性、生物利用度及耐药性,降低药物的毒副作用。综述壳聚糖衍生物结构对其胶束药物传输性能的影响以及壳聚糖衍生物及其胶束的功能化修饰和在药物传递系统中的应用。     

细菌小细胞在癌症治疗中的应用

癌症一直是危害人类健康的主要疾病之一。传统的癌症治疗方法包括放疗、化疗和手术,均具有明显的毒副作用或局限性。脂质体和纳米颗粒作为被广泛研究的药物递送载体,在人体临床试验中也出现了药物渗漏和装载功能不全等问题。目前而言,应用具有肿瘤靶向性的载体递送抗肿瘤药物或小分子,是有希望介导安全、有效的肿瘤治疗的策略之一。近年来,细菌来源的非复制型小细胞已受到越来越多的关注。小细胞是细菌异常分裂时期产生的纳米级无核细胞,其直径为200–400 nm,因而具有较大的药物装载能力。对小细胞的表面进行修饰,例如,装配能与肿瘤细胞表面特异性抗原或受体结合的抗体/配体,可显著提高小细胞的肿瘤靶向性。这种具有靶向性的纳米材料能将抗肿瘤的化疗药物、功能性核酸或编码功能性小分子的质粒靶向递送至肿瘤,而减少药物在正常组织器官的集聚。因此,使用小细胞作为靶向递送载体有助于降低药物对机体的毒性,从而最大限度地发挥药物分子在体内的抗肿瘤活性。文中将对小细胞的产生与纯化、药物装载、肿瘤细胞靶向性、内化过程以及其用于递送抗肿瘤药物的研究进展等方面进行综述,为开发基于小细胞的癌症治疗策略提供一定的参考。     

糖类修饰的纳米递送系统

癌症的高病发率和高死亡率已经引起了人们广泛的重视。传统治疗癌症的药物分子存在水溶性较差、无靶向性、生物安全性低等问题。纳米递送系统如脂质体、聚合物纳米粒子和共聚物胶束解决了传统癌症治疗过程中药物水溶性较差的问题。但大多数纳米递送系统不具备靶向性和生物相容性,且药物包封率不高。糖类作为具有较好的靶向特异性识别能力、安全性和生物相容性的天然有机化合物能够有效修饰纳米递送系统,能包载药物分子并有效靶向到特定器官。本文将对糖类修饰的脂质体、聚合物纳米粒子和共聚物胶束三大纳米递送系统进行综述。     

Nano-biotechnology in tumour and cancerous disease: A perspective review

In recent years, drug manufacturers and researchers have begun to consider the nanobiotechnology approach to improve the drug delivery system for tumour and cancer diseases. In this article, we review current strategies to improve tumour and cancer drug delivery, which mainly focuses on sustaining biocompatibility, biodistribution, and active targeting. The conventional therapy using cornerstone drugs such as fludarabine, cisplatin etoposide, and paclitaxel has its own challenges especially not being able to discriminate between tumour versus normal cells which eventually led to toxicity and side effects in the patients. In contrast to the conventional approach, nanoparticle-based drug delivery provides target-specific delivery and controlled release of the drug, which provides a better therapeutic window for treatment options by focusing on the eradication of diseased cells via active targeting and sparing normal cells via passive targeting. Additionally, treatment of tumours associated with the brain is hampered by the impermeability of the blood–brain barriers to the drugs, which eventually led to poor survival in the patients. Nanoparticle-based therapy offers superior delivery of drugs to the target by breaching the blood–brain barriers. Herein, we provide an overview of the properties of nanoparticles that are crucial for nanotechnology applications. We address the potential future applications of nanobiotechnology targeting specific or desired areas. In particular, the use of nanomaterials, biostructures, and drug delivery methods for the targeted treatment of tumours and cancer are explored.     

Paclitaxel delivery to brain tumors from hydrogels: a computational study

Malignant gliomas are aggressive forms of primary brain tumors characterized by a poor prognosis. The most successful treatment so far is the local implantation of polymer carriers (Gliadel® wafers) for the sustained release of carmustine. To improve the effectiveness of local drug treatment, new polymer carriers and pharmacological agents are currently being investigated. Of particular interest is a set of novel thermo‐gelling polymers for the controlled release of hydrophobic drugs such as paclitaxel (e.g., OncoGel?). Herein, we use computational mass transport simulations to investigate the effectiveness of paclitaxel delivery from hydrogel‐forming polymer carriers. We found similar (within 1–2 mm) therapeutic penetration distances of paclitaxel when released from these hydrogels as compared with carmustine released from Gliadel® wafers. Effective therapeutic concentrations were maintained for >30 days for paclitaxel when released from the hydrogel as compared with 4 days for carmustine released from Gliadel® wafers. Convection in brain tissue prevented the formation of a uniform drug concentration gradient around the implant. In addition, the surface area to volume ratio of the gel is an important factor that should be considered to maintain a controlled release of paclitaxel within the degradation lifetime of the polymer matrix. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

Site-specifically traced drug release and biodistribution of a paclitaxel-antibody conjugate toward improvement of the linker structure

Tumor-directed drug delivery is a promising strategy in cancer treatment, and in this field, monoclonal antibodies constitute an important class of targeting vehicles. A critical issue in the design of targeting conjugates is the timing of the release of the cytotoxic payload, with the ideal situation being the release at the maximum tumor uptake of the targeting molecule. A site-specific radiolabeling technique was used to elucidate the biodistribution and in vivo drug release pattern of an antibody conjugate of paclitaxel (PTX, 1, Figure 1) in which the drug and the antibody moieties were connected by a succinate (SX) linker. In this new method, a metabolite of PTX, 3'-(4-hydroxyphenyl)paclitaxel (3'-OH-PTX, 2, Figure 1) was used as a tyrosine mimic for the synthesis of the drug site-labeled conjugate (DSL, [(125)I]-3'-OH-PTXSXC225). This was achieved by iodogen (125)I-labeling of 3'-OH-PTXSX and subsequent conjugation to C225. The antibody site-labeled conjugate (ASL, PTXSX-[(125)I]-C225) was prepared by direct radioiodination of PTXSXC225. Biodistribution of these compounds was studied in Balb/c nude mice bearing DU-145 human prostate carcinoma xenografts. While the 4 and 24 h tumor uptake (in percent injected dose per gram of tissue, %ID/g) for [(125)I]-3'-OH-PTXSXC225 were 3.3 +/- 1.5 and 1.7 +/- 0.6%ID/g, the PTXSX-[(125)I]-C225 showed tumor uptake values of 3.8 +/- 4.2 and 14.8 +/- 4.2%ID/g at these time points. This difference in the tumor uptake over time indicates an early cleavage of the drug with respect to the antibody tumor localization. This was further confirmed by an in vitro drug release kinetics study leading to a half-life of about 2 h for PTXSXC225 under physiological conditions. To increase the stability of the PTX-MAb bond, a new conjugate (PTXGLC225) with glutaric acid (GL) as the linker was synthesized. Under the same conditions, the PTXGLC225 showed a 16-fold increase in the half-life (t(1/2)) of the drug release. The effect of the increased t(1/2) of this compound on the antitumor activity of the conjugate was tested in a DU-145 human prostate tumor-implanted mouse model. In comparison to a previous similar experiment with PTXSXC225, better antitumor activity was observed for the PTXGLC225 conjugate as compared to controls. These results demonstrated the first time use of radioiodinated 3'-OH-PTX for in vivo tracing of a paclitaxel conjugate and application of the resulting information to the design of a therapeutically more useful PTX-MAb linker.     

Synthesis,anticancer activity and cytotoxicity of galactosylated epothilone B

Epothilones are the 16-membered macrolide compounds, exhibit microtubule-promoting activity, have the same anti-tumor mechanism as paclitaxel, and are expected to be the ideal substitutes for paclitaxel. However, natural epothilone compounds have been found to have disadvantages such as high toxicity in vivo, poor selectivity to tumor cells, and susceptibility to drug resistance. Herein, epothilone B was synthesized by fermentation, and it was galactosylated by chemical method. The toxicity in vitro of epothilone B and its galactosylated derivative was investigated by the MTT method. The anticancer activity evaluation in vitro was performed using a method similar to the antibody-directed enzyme-prodrug therapy (ADEPT) method. It indicated that the ratio of cytotoxicity between the free epothilone B and the galactosylated epothilone B was about 150. This would lay the foundation for the targeted treatment of cancer with epothilone glycosides.     

Paclitaxel-loaded poly(gamma-glutamic acid)-poly(lactide) nanoparticles as a targeted drug delivery system against cultured HepG2 cells

The study was to develop paclitaxel-loaded formulations using a novel type of self-assembled nanoparticles that was composed of block copolymers synthesized from poly(gamma-glutamic acid) and poly(lactide) via a simple coupling reaction. The nanoparticles (the NPs) were prepared with various feed weight ratios of paclitaxel to block copolymer (the P/BC ratio). The morphology of all prepared nanoparticles was spherical and the surfaces were smooth. Increasing the P/BC ratio significantly increased the drug loading content of the prepared nanoparticles, but remarkably reduced the drug loading efficiency. The release rate of paclitaxel from the NPs decreased significantly as the P/BC ratio increased. For the potential of targeting liver cancer cells, galactosamine was further conjugated on the prepared nanoparticles (the Gal-NPs) as a targeting moiety. It was found that the activity in inhibiting the growth of HepG2 cells (a liver cancer cell line) by the Gal-NPs was comparable to that of a clinically available paclitaxel formulation, while the NPs displayed a significantly less activity. This may be attributed to the fact that the Gal-NPs had a specific interaction with HepG2 cells via ligand-receptor recognition. Cells treated with distinct paclitaxel formulations resulted in arrest in the G2/M phase. The arrest of cells in the G2/M phase was highly suggestive of interference by paclitaxel with spindle formation and was consistent with the morphological findings presented herein. In conclusion, the active targeting nature of the Gal-NPs prepared in the study may be used as a potential drug delivery system for the targeted delivery to liver cancers.     

Clinical and Preclinical Pharmacology of Liposomal Vincristine

Abstract

Vincristine is one of the most commonly administered anticancer drugs and is active in a wide range of indications including non-Hodgkin's lymphomas, acute lymphocytic leukemias and lung cancer. Administration of vincristine in long-circulating liposomes may be expected to result in increased accumulation of drug at tumor sites due to “passive targeting” or “disease-site targeting” effects arising from the more permeable vasculature in these regions. Further, for liposomes with appropriate drug release characteristics, extended exposure of tumor cells to vincristine would result from liposomal delivery. The combination of increased drug delivery and extended duration of drug exposure may be expected to result in increased efficacy, particularly because vincristine is a cell-cycle specific drug. It is shown that vincristine can be encapsulated in large unilamellar vesicles (diameter β 100 nm) using a pH gradient (interior acidic) approach. Further, the efficacy of liposomal formulations of vincristine in animal models is highly sensitive to the drug release rate in vivo. A liposomal formulation with drug retention characteristics such that more than 50% of the vincristine is retained in the carrier 24 h following i.v. injection exhibits significantly improved antitumor efficacy in A431 xenograft and P388 murine tumor models in comparison to either free drug or leakier liposomal formulations. The clinical activity of liposomal vincristine has been investigated in relapsed or refractory non-Hodgkin's lymphoma patients at a dose level of 2 mg/m² every two weeks. Of 83 registered patients, there were 24 responses in 68 evaluable patients. The responses according to histology are: Indolent-13%; Transformed-42%; Aggressive-45%. There were no serious cases of myelosuppression or any toxic deaths. It is concluded that liposomal vincristine can be given at high doses, is active and well tolerated and is rarely neurotoxic or myelosuppressive in these heavily pretreated patients. It appears that the benefits of low toxicity and enhanced efficacy noted in the tumor models are also observed in the clinical setting. A multicenter pivotal Phase II trial of liposomal vincristine in relapsed and refractory non-Hodgkin's lymphoma has been approved by the US FDA and is ongoing.     

Synthesis and biological evaluation of PSMA-targeting paclitaxel conjugates

Prostate cancer (PC) is the second most commonly occurring cancer in men. Conventional chemotherapy has wide variety of disadvantages such as high systemic toxicity and low selectivity. Targeted drug delivery is a promising approach to decrease side effects of therapy. Prostate specific membrane antigen (PSMA) is overexpressed in prostate cancer cells while low level of expression is observed in normal cells. In this study we describe the development of Glu-urea-Lys based PSMA-targeting conjugates with paclitaxel. A series of new PSMA targeting conjugates with paclitaxel was designed and synthesized. The cytotoxicity of conjugates was evaluated against prostate (LNCaP, 22Rv1 and PC-3) and non-prostate (Hek293T, VA13, A549 and MCF-7) cell lines. The most promising conjugate 21 was examined in vivo using 22Rv1 xenograft mice model. It demonstrated good efficiency comparable with paclitaxel, while reduced toxicity. 3D molecular docking study was also performed to understand underlying mechanism of binding and further optimization of the linker substructure and conjugates structure for improving the target affinity. These conjugates may be useful for further design of novel PSMA targeting delivery systems for PC.     

Cellular studies reveal mechanistic differences between taccalonolide A and paclitaxel

Taccalonolide A is a microtubule stabilizer that has cellular effects almost identical to paclitaxel. However, biochemical studies show that, unlike paclitaxel, taccalonolide A does not enhance purified tubulin polymerization or bind tubulin/microtubules. Mechanistic studies aimed at understanding the nature of the differences between taccalonolide A and paclitaxel were conducted. Our results show that taccalonolide A causes bundling of interphase microtubules at concentrations that cause antiproliferative effects. In contrast, the concentration of paclitaxel that initiates microtubule bundling is 31-fold higher than its IC₅₀. Taccalonolide A''s effects are further differentiated from paclitaxel in that it is unable to enhance the polymerization of tubulin in cellular extracts. This finding extends previous biochemical results with purified brain tubulin to demonstrate that taccalonolide A requires more than tubulin and a full complement of cytosolic proteins to cause microtubule stabilization. Reversibility studies were conducted and show that the cellular effects of taccalonolide A persist after drug washout. In contrast, other microtubule stabilizers, including paclitaxel and laulimalide, demonstrate a much higher degree of cellular reversibility in both short-term proliferation and long-term clonogenic assays. The propensity of taccalonolide A to alter interphase microtubules at antiproliferative concentrations as well as its high degree of cellular persistence may explain why taccalonolide A is more potent in vivo than would be expected from cellular studies. The close linkage between the microtubule bundling and antiproliferative effects of taccalonolide A is of interest given the recent hypothesis that the effects of microtubule targeting agents on interphase microtubules might play a prominent role in their clinical anticancer efficacy.Key words: taccalonolide, paclitaxel, microtubule stabilizer, microtubule targeted agent, tubulin, microtubule, laulimalide, antimitotic agent, drug persistence     

EIF2A promotes cell survival during paclitaxel treatment in vitro and in vivo

The integrated stress response (ISR) is critical for cancer cell survival during stress stimuli and has been implicated in the resistance to cancer therapeutics, in which the mechanism, however, is poorly understood. Here, we showed that paclitaxel, the major chemotherapy drug for breast cancer, induced ISR and phosphorylated ser51 residue of EIF2S1 by EIF2AK3 and EIF2AK4. When exposed to paclitaxel, cancer cells activated the EIF2AK3/EIF2AK4‐pEIF2S1‐ATF4 axis and maintained redox homoeostasis by inducing expression of the major antioxidant enzymes HMOX1, SHMT2 and SLC7A11. Paclitaxel‐mediated cell death was significantly increased following loss of ISR or ATF4 expression. This sensitizing effect could be partially rescued by Trolox, a ROS scavenger. We demonstrated that the alternative initiation factor EIF2A was essential for cancer cell survival after paclitaxel‐mediated ISR both in vitro and in vivo. Moreover, patients with breast cancer exhibited higher ISR after chemotherapy, and the elevated mRNA levels of HMOX1, SHMT2 and EIF2A were correlated with poor prognosis. Collectively, our findings reveal a novel mechanism for paclitaxel resistance and suggest that targeting EIF2A combined with ISR agonist may be a potential treatment regimen to overcome drug resistance for breast cancer.     

Psychiatry-epitomes of progress: stimulants and hyperkinesis

Although used around the world since 1949, lithium has come into extensive use in psychiatry in the United States only within the past decade. Before initiating treatment with this drug, physicians must be familiar with the diagnostic scheme of the major affective disorders, the indications and contraindications to lithium''s use, and its principles of treatment, including evaluation before lithium therapy, criteria for monitoring blood levels and signs of impending toxicity.Despite earlier reports about the toxicity of lithium when it was promoted as a salt substitute, lithium is a safe drug. Its use not only has revolutionized the treatment of the major affective disorders, but has opened up new and broad avenues of research into the regulation of man''s emotions.