两个改造后的肿瘤抑素抗肿瘤活性肽活性研究

为了研究改造后的肿瘤抑素2个抗肿瘤活性肽的作用机制,明确其不同的抗肿瘤活性,采用基因工程技术原理,人工合成肿瘤抑素中185～203位氨基酸所对应的19肽和T7肽(74～98位氨基酸)基础上改造的21肽碱基序列,将其与融合蛋白表达载体pTYB2重组后转化到大肠杆菌BL21(DE3)中进行诱导表达,用几丁质亲和层析柱一步纯化,直接获得19肽和21肽,利用MTT法、细胞生长曲线、TUNEL法、流式细胞仪早期细胞凋亡检测和细胞周期检测,小鼠H22腹水型转移型肝癌实体瘤抑瘤实验并结合组织病理学切片,来研究19肽和21肽单独应用或联合应用对肿瘤细胞和内皮细胞生长和凋亡的影响以及对体内肿瘤的抑制情况.体内外实验表明:获得的19肽抗肿瘤活性以直接作用肿瘤细胞为主,也有抑制新生血管生成的作用.基因重组21肽抗肿瘤作用是通过抑制肿瘤组织新生血管生成实现的.19肽、21肽联合应用对肿瘤细胞、内皮细胞生长抑制和促凋亡作用明显增强,抗肿瘤活性大大提高.联合用药弥补了单独用药不足,产生协同抗肿瘤作用,可能会成为今后肿瘤治疗的一个主要方向.     

姜黄素抗肿瘤的机制

姜黄素具有很显著的抗肿瘤作用。本文通过对几年来国内外对姜黄素抗肿瘤的研究进行总结,介绍了姜黄素的抗肿瘤机制。在分子水平上,肿瘤细胞摄取姜黄素,增加药物作用的靶位点,调节肿瘤细胞的信号传递,从而调节肿瘤细胞中某些酶活性及蛋白质、基因的表达。在细胞水平上,姜黄素能抑制肿瘤细胞的增殖、促进肿瘤细胞凋亡、逆转肿瘤细胞的多药耐药性、增强NK细胞杀伤力。在组织水平上抑制肿瘤血管生成等方面来发挥抗肿瘤作用。     

人mda-7／IL-24的抗肿瘤作用机制

mda-7／IL-24是20世纪90年代中期发现的一个新基因。由于mda-7／IL-24与人IL-10家族具有相当的同源性,后来HUGO基因命名委员会将之重新命名为IL-24,并将其归类到IL-10家族。近年研究表明,采用复制缺陷的腺病毒表达载体Ad．mda-7使其在肿瘤细胞异位表达,引起多种肿瘤细胞的生长抑制。尽管mda．7／IL-24肿瘤靶向性的作用机制还不是很清楚,但大量的实验结果表明该基因作为一个有效的肿瘤治疗基因,能够区分正常细胞和肿瘤细胞、诱导各种不同肿瘤细胞凋亡、启动抗肿瘤“旁观者效应”、增强肿瘤细胞对射线敏感性、抑制动物模型体内移植瘤的生长和血管新生以及具有调节免疫应答能力。     

苦参活性成分的抗肿瘤作用机制研究进展

苦参是中国传统的植物药,具有清热燥湿等多种作用,广泛地应用于抗肿瘤研究,其活性成分能够通过细胞周期阻滞抑制肿瘤细胞的增殖、诱导肿瘤细胞分化、通过细胞周期阻滞、Fas/Fasl和线粒体途径诱导肿瘤细胞凋亡,通过降低VEGF等的表达抑制肿瘤血管生成和内皮细胞增殖,抑制肿瘤侵袭和转移,通过抑制端粒酶活性、逆转多药耐药、调节免疫耐受等辅助治疗肿瘤。通过收集、分析和整理最近几年涉及苦参活性成分抗肿瘤作用的文献,综述其抗肿瘤作用机制,为临床应用苦参治疗肿瘤提供参考。     

靶向Survivin基因与肿瘤

Survivin基因不仅表达于绝大多数的肿瘤细胞中,也存在于人体正常的细胞中,它具有抑制凋亡和调节有丝分裂的双重作用．临床研究表明：下调Survivin基因的表达或者抑制Survivin蛋白的功能,可以降低肿瘤细胞的生长潜力、增加凋亡的比例,而且可以增强肿瘤细胞对抗肿瘤药物和放射线的敏感性．许多抗肿瘤药物通过诱导细胞凋亡而发挥功能．但某些肿瘤表现出对它们的耐药性。导致肿瘤耐药性的一个最重要的因素就是Survivin的表达．有关细胞凋亡途径和Survivin基因表达等方面的研究可为发现和发展新型抗肿瘤药物提供新的途径．     

竹节参化学成分及其抗肿瘤作用机制

癌症的发病率逐年上升,威胁着人类的生命健康。目前恶性肿瘤的治疗手段如放化疗、靶向治疗、免疫治疗等存在不良反应大、易耐药等问题。传承数千年的中医药在肿瘤的防治中有疗效确切、不良反应小、价格低廉等优势。中药竹节参为五加科人参属植物,主要含有皂苷类、糖类、氨基酸等多种化学成分。药理研究表明,竹节参有良好的抗肿瘤作用,其作用机制与抑制肿瘤细胞增殖、诱导细胞凋亡、抑制细胞迁移和侵袭、化疗增敏、增强机体免疫、改善肿瘤恶病质等有关。本文对竹节参中具备抗肿瘤作用的化学成分及抗肿瘤的作用机制进行系统综述,以期为进一步探索竹节参中不同化学成分的抗肿瘤作用机制及其在临床中的应用提供新的思路和理论依据。     

IAP家族分子与肿瘤靶向治疗

凋亡抑制因子(inhibitor of apoptosis proteins,IAPs)是一类高度保守的内源性抗细胞凋亡因子家族,主要通过抑制Caspase活性和参与调节核因子NF-κB的作用而抑制细胞凋亡。细胞抗凋亡机制在肿瘤发生、发展以及肿瘤耐药性形成中发挥重要作用。肿瘤细胞高表达IAPs是导致肿瘤细胞抵抗凋亡的关键。细胞凋亡调控异常与肿瘤细胞耐药密切相关,增强肿瘤细胞对化疗药物的敏感性成为近年来肿瘤治疗的重要策略之一。该文综述了IAP家族蛋白的结构、生物学特性及其作为肿瘤治疗靶点的研究进展。     

间充质干细胞抑制肿瘤细胞增殖机制的研究进展

间充质干细胞(mesenchymal stem cells,MSCs)是能够从多种组织来源的基质细胞分离出来的一种具有分化潜能的干细胞,能够分化为脂肪、成骨和软骨细胞等多种组织细胞。研究表明,MSCs对肿瘤细胞具有抑制作用,其作用机制体现在两方面:一方面是通过直接分泌蛋白和微泡来调节肿瘤细胞信号通路和生长所需的因子的表达;另一方面是作为肿瘤靶向药物运输载体,向肿瘤组织输送多种能够抑制肿瘤生长、促进肿瘤细胞凋亡的基因或药物。该文针对MSCs对肿瘤细胞的直接和间接抑制机制进行了综述。     

XIAP在胰腺癌化疗耐药及治疗中的研究进展

X连锁的凋亡抑制蛋白(X-linked inhibitor of apoptosis protein,XIAP)是凋亡抑制蛋白家族中的一员,具有抗凋亡作用.研究发现XIAP在胰腺癌中呈高表达,并且能诱导胰腺癌细胞及组织对化疗耐药.通过在基因水平及蛋白水平降低XIAP的表达对胰腺癌的治疗具有重要意义.AEG 35156是针对XIAP的反义寡核苷酸分子,能够抑制胰腺癌细胞及组织生长.RNAi能够稳定下调胰腺癌细胞中XIAP水平,从而加强TRAIL诱导的细胞凋亡,并能提高胰腺癌细胞对化疗的敏感性.针对XIAP的小分化合物能够抑制XIAP的功能,释放被XIAP抑制的凋亡起始和效应分子以及XIAP抑制的其他促凋亡蛋白,提高多种肿瘤细胞的凋亡指数及对放化疗的敏感性.XAFl能抑制XIAP的抗凋亡作用.本文就XIAP在胰腺癌化疗耐药及治疗中的研究进展做一综述.     

4－硒（代）硫酸酯多糖的抗肿瘤免疫调节作用及其机制研究

本实验系统地研究了４－硒（代）硫酸酯多糖的抗肿瘤免疫调节作用及其机制。发现该药在体内外均有抑制肿瘤生长的作用,并认为其抑瘤机制与促进巨噬细胞活性,间接促进淋巴细胞活性,释放具有杀伤肿瘤细胞的效应分子以及选择性抑制肿瘤细胞大分子合成有关。结果表明,４－硒（代）硫酸酯多糖是一种兼具杀伤肿瘤细胞和增强免疫功能双重作用的新型免疫型抗肿瘤药。     

熊果酸衍生物的合成及其对肺癌细胞活性抑制的研究

目的：探讨合成的熊果酸衍生物对肺癌LTEP-α-2肿瘤细胞增殖的抑制作用。方法：熊果酸经氧化、肟化和腙化合成为3-氧代熊果酸、3-肟基熊果酸和3-（2＇,4＇-二硝基）-苯腙熊果酸。采用MTT法检测熊果酸及其衍生物对肺癌LTEP-α-2细胞的体外抗肿瘤活性。结果：熊果酸及其衍生物对肺癌LTEP-α-2细胞有抑制作用,且3-肟基熊果酸对肺癌LTEP-α-2细胞抑制作用高于其他化合物,其抑制率为90.0%,IC50为7.4μg/m L。结论：熊果酸衍生物3-肟基熊果酸抗肺癌LTEP-α-2肿瘤细胞活性高于熊果酸的活性。     

Ursolic acid of Origanum majorana L. reduces Abeta-induced oxidative injury

Amyloid beta protein (Abeta) increases free radical production and lipid peroxidation in PC12 nerve cells, leading to apoptosis and cell death. The effect of ursolic acid from Origanum majorana L. on Abeta-induced neurotoxicity was investigated using PC12 cells. Pretreatment with isolated ursolic acid and vitamin E prevented the PC12 cell from reactive oxygen species (ROS) toxicity that is mediated by Abeta. The ursolic acid resulted in decreased Abeta toxicity assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH), and trypan blue assay. Thus, treatment with these antioxidants inhibited the Abeta-induced neurotoxic effect. Therefore, these results indicate that micromolar Abeta-induced oxidative cell death is reduced by ursolic acid from Origanum majorana L.     

Apoptotic action of ursolic acid isolated from Corni fructus in RC-58T/h/SA#4 primary human prostate cancer cells

Ursolic acid (3β-hydroxy-urs-12-en-28-oic acid) is a major biological active component of Corni fructus that is known to induce apoptosis. However, the apoptotic mechanism of ursolic acid using primary malignant tumor (RC-58T/h/SA#4)-derived human prostate cells is not known. In the present study, ursolic acid significantly inhibited the growth of RC-58T/h/SA#4 cells in dose- and time-dependent manners. Ursolic acid induced cell death as evidenced by an increased proportion of cells in sub-G1 phase, the formation of apoptotic bodies, nuclear condensation, and DNA fragmentation. After ursolic acid treatment at concentrations above 40 μM, the activities of caspase-3, -8, and -9 were significantly increased compared that of control. Ursolic acid modulated the upregulation of Bax (pro-apoptotic) as well as the downregulation of Bcl-2 (anti-apoptotic). Ursolic acid also stimulated Bid cleavage, which indicates that the apoptotic action of caspase-8-mediated Bid cleavage leads to the activation of caspase-9. Thus, the apoptotic effect of ursolic acid was involved in extrinsic and intrinsic signaling pathways. In addition, ursolic acid increased the expression of the caspase-independent mitochondrial apoptosis factor (AIF) in RC-58T/h/SA#4 cells. The present results suggest that ursolic acid from Corni fructus activated apoptosis in RC-58T/h/SA#4 cells via both caspase-dependent and -independent pathways.     

血红素氧合酶-1对肝癌作用的研究进展

血红素氧合酶-1(heme oxygenase,HO-1)是细胞内的一种可诱导的保护性酶,具有抗氧化、抗炎、抗凋亡等作用。它在肿瘤细胞(如肝癌细胞)中的表达一般会增强,能影响肿瘤细胞的增殖等生物学行为。一方面,HO-1能促进肝癌细胞的生长和扩散,并通过减少氧化应激产生的氧自由基而对肝癌细胞发挥保护作用,使肝癌细胞对治疗产生抵抗性。另一方面,HO-1使肝移植治疗晚期肝癌中的免疫排斥降低,提高肝移植的成功率。本文简要概括了HO-1对肝癌发生进展的影响,并阐述了HO-1在肝移植方面的重要作用,这可能对抗肝癌药物的研发及肝癌的治疗具有一定的指导意义。     

Neoadjuvant cisplatin for head and neck cancer: Simulation of a novel schedule for improved therapeutic ratio

Current clinical studies support the role of neoadjuvant cisplatin administration prior to curative radiotherapy or radio-chemotherapy for advanced head and neck cancer. Nevertheless, based on locoregional control rates the studies indicate that there is need to redesign cisplatin-based schedules for induction chemotherapy, thus the ideal treatment regimen is yet to be established. While the pharmacokinetics/dynamics of daily cisplatin regimens correspond better with the cell cycle properties of head and neck cancers, weekly regimens are more commonly employed in clinics due to lower complications. Yet, the high rates of adverse events induced by current cisplatin schedules often represent a limiting factor in the overall success of the treatment.The aim of the present paper was to model the pharmacodynamic properties of cisplatin and to simulate and compare various neoadjuvant treatment regimens in regards to their effect on tumour control. Treatment simulation was undertaken on a virtual squamous cell carcinoma of the head and neck, previously grown by computer-based probabilistic methods.The model suggests that a novel cisplatin treatment, given every three days is comparable, in regards to tumour control, with the daily administration and more effective than the weekly regimen in neoadjuvant settings. Endpoints were assessed in terms of cell population regrowth after treatment cessation followed by two weeks of unperturbed growth. Simulation of two weeks low-dose daily cisplatin followed by two weeks ‘free growth’ lead to 15% population regrowth, while weekly high-dose cisplatin over three weeks, followed by two weeks unperturbed growth resulted in 52% tumour cell regrowth. The proposed novel schedule of low-dose third-daily cisplatin gives closer tumour regrowth to daily administration (27% versus 15%) than to the weekly regimen (52%) and also similar cell distribution along the cell cycle as the daily one, suggesting therefore comparable response to subsequent treatment.The advantage of using a third-daily drug regimen would be a decrease in normal tissue complication rates compared to daily administration and possibly an increase in tumour control when compared to the ‘conventional’ weekly cisplatin delivery.     

Apoptosis as the basic mechanism of cytotoxic action of ursolic and pomolic acids in glioma cells

Pentacyclic triterpene acids are of great interest as compounds that exhibit selective cytotoxicity against malignant tumor cells. If earlier studies were carried out mainly in cancer cells of epithelial origin, in the present work the cytotoxic effect of ursolic and pomolic acids on the primary and permanent glioma cell lines was analyzed. Both compounds are toxic to oncotransformed cells and induce apoptosis in U-87 MG line. Using molecular docking, it has been shown that Akt1 and MDM2 may be potential targets of the studied triterpene acids. It has been suggested that ursolic and pomolic acids induce apoptosis in glioma cells through inhibition of the PI3K/Akt signaling pathway, and they can be considered as potentially promising agents for the treatment of glioblastoma.     

Ursolic acid synergistically enhances the therapeutic effects of oxaliplatin in colorectal cancer

Oxaliplatin is a key drug in chemotherapy of colorectal cancer (CRC). However, its efficacy is unsatisfied due to drug resistance of cancer cells. In this study, we tested whether a natural agent, ursolic acid, was able to enhance the efficacy of oxaliplatin for CRC. Four CRC cell lines including SW480, SW620, LoVo, and RKO were used as in vitro models, and a SW620 xenograft mouse model was used in further in vivo study. We found that ursolic acid inhibited proliferation and induced apoptosis of all four cells and enhanced the cytotoxicity of oxaliplatin. This effect was associated with down-regulation of Bcl-xL, Bcl-2, survivin, activation of caspase-3, 8, 9, and inhibition of KRAS expression and BRAF, MEK1/2, ERK1/2, p-38, JNK, AKT, IKKα, IκBα, and p65 phosphorylation of the MAPK, PI3K/AKT, and NF-κB signaling pathways. The two agents also showed synergistic effects against tumor growth in vivo. In addition, ursolic acid restored liver function and body weight of the mice treated with oxaliplatin. Thus, we concluded that ursolic acid could enhance the therapeutic effects of oxaliplatin against CRC both in vitro and in vivo, which offers an effective strategy to minimize the burden of oxaliplatin-induced adverse events and provides the groundwork for a new clinical strategy to treat CRC.     

Complete remission of cancer in late-stage disease by radiation and transfer of allogeneic MHC-matched immune T cells: lessons from GvL studies in animals

Most immunotherapy studies in animal tumor models are performed in early stages of the disease. Reports on the studies of treatment in late stages of tumor growth and metastasis are much rarer. To guide future efforts for treatment in late-stage disease, a model of effective immune rejection of advanced metastasized cancer is reviewed and lessons therefrom are summarized. Already cachectic DBA/2 mice with a subcutaneously transplanted syngeneic tumor (ESb-MP lymphoma) of 1.5 cm diameter and with macroscopic liver and kidney metastases at 4 weeks could be successfully treated by a combination of sublethal (5 Gy) irradiation followed by a single transfer of 20 million anti-tumor immune spleen cells from tumor-resistant allogeneic MHC-B10.D2 mice. Following intravenous cell transfer, the primary tumors became encapsulated and were eventually rejected from the skin while visceral metastases gradually disappeared leaving behind only scar tissue. There was wound-healing at the site of the rejected primary tumor, and the animals survived long term without any tumor recurrence. The complete eradication of late-stage disease by adoptive cellular immunotherapy could be corroborated noninvasively by ³¹P-NMR spectroscopy of primary tumors and by ¹H-NMR microimaging of liver metastases. Conclusions from functional mechanistic studies in this model are summarized and clinical implications discussed.     

Hepatic tissue engineering: from transplantation to customized cell-based liver directed therapies from the laboratory

Today, liver transplantation is still the only curative treatment for liver failure due to end-stages liver diseases. Donor organ shortage, high cost and the need of immunosuppressive medications are still the major limitations in the field of liver transplantation. Thus, alternative innovative cell-based liver directed therapies, e.g. liver tissue engineering, are under investigation with the aim, that in future an artificial liver tissue could be created and be used for the replacement of the liver function in patients. Using cells instead of organs in this setting should permit (i) expansion of cells in an in vitro phase, (ii) genetic or immunological manipulation of cells for transplantation, (iii) tissue typing and cryopreservation in a cell bank, and (iv) the ex vivo genetic modification of patient's own cells prior re-implantation. Function and differentiation of liver cells are influenced by the three-dimensional organ architecture. The use of polymeric matrices permits the three dimensional formation of a neo-tissue and specific stimulation by adequate modification of the matrix-surface which might be essential for appropriate differentiation of transplanted cells. Additionally, culturing hepatocytes on three dimensional matrices permits culture in a flow bioreactor system with increased function and survival of the cultured cells. Based on bioreactor technology, bioartificial liver devices (BAL) are developed for extracorporeal liver support. Although BALs improved clinical and metabolic conditions, increased patient survival rates have not been proven yet. For intra-corporeal liver replacement, a concept which combines Tissue Engineering using three-dimensional, highly porous matrices with cell transplantation could be useful. In such a concept, whole liver mass transplantation, long term engraftment and function as well as correction of a metabolic defect in animal models could be achieved with a principally reversible procedure. Future studies have to investigate, which environmental conditions and transplantation system would be most suitable for the development of artificial functional liver tissue including blood supply for a potential use in a clinical setting.     

Arachidonic acid causes cell death through the mitochondrial permeability transition. Implications for tumor necrosis factor-alpha aopototic signaling

We have investigated the effects of arachidonic and palmitic acids in isolated rat liver mitochondria and in rat hepatoma MH1C1 cells. We show that both compounds induce the mitochondrial permeability transition (PT). At variance from palmitic acid, however, arachidonic acid causes a PT at concentrations that do not cause PT-independent depolarization or respiratory inhibition, suggesting a specific effect on the PT pore. When added to intact MH1C1 cells, arachidonic acid but not palmitic acid caused a mitochondrial PT in situ that was accompanied by cytochrome c release and rapidly followed by cell death. All these effects of arachidonic acid could be prevented by cyclosporin A but not by the phospholipase A(2) inhibitor aristolochic acid. In contrast, tumor necrosis factor alpha caused phospholipid hydrolysis, induction of the PT, cytochrome c release, and cell death that could be inhibited by both cyclosporin A and aristolochic acid. These findings suggest that arachidonic acid produced by cytosolic phospholipase A(2) may be a mediator of tumor necrosis factor alpha cytotoxicity in situ through induction of the mitochondrial PT.