945 resultados para Tumor Cells


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Recentemente, nosso grupo demonstrou que a matriz extracelular de astrocitomas promove a seleçãode células endoteliais altamente proliferativas, porém com reduzida capacidade tubulogênica, além de determinar a morte de uma segunda sub-população endotelial, por desaderência ou anoikis. Estratégias de simulação dos teores de tenascina-C (TN-C) e fibronectina (FN) nas matrizes de astrocitomas, realizados com ambas as proteínas purificadas na forma de substratos definidos, sugeriram que o balanço TN-C:FN estava relacionado com os fenótipos endoteliais observados. No entanto, este procedimento não permitia abordar a participação de outros componentes da matriz tumoral nativa neste processo. Com objetivo de estudar a modulação do fenótipo angiogênico das células endoteliais por matrizes de astrocitoma, realizamos o silenciamento da expressão de TN-C na linhagem de astrocitoma U-373 MG. O silenciamento foi confirmado por western blotting, PCR em tempo real e ELISA, que permitiram concluir que, no período pós-transfecção (120h) necessário para se obter matrizes tumorais nativas para ensaios funcionais com células endoteliais, as células U-373 MG mantiveram-se silenciadas em índices superiores a 90%. A diminuição de TN-C nas matrizes tumorais resultou em um pequeno (≅18%, em média), porém significativo aumento na taxa de adesão endotelial. HUVECs incubadas com a matriz secretadas por células silenciadas apresentaram uma redução de ≅35% do número de núcleos picnóticos, quando comparadas a HUVECs incubadas com a matriz de células U-373 MG (selvagens ou transfectadas com siRNA controle). O silenciamento da expressão da TN-C na matriz nas células U-373 MG restaurou ainda o defeito tubulogênico das células endoteliais, que passaram a apresentar formação de tubos comparável à obtida quando HUVECs foram incubadas com sua matriz autóloga, rica em FN. Tais resultados apoiam observações anteriores do grupo, que já sugeriam que a maior proporção de FN na matriz autóloga, comparada a matriz do astrocitoma, seria o fator principal para a seleção dos fenótipos angiogênicos observados, demonstrando mais uma vez a importância do balanço FN:TN-C na regulação de processos angiogênicos. Dados anteriores sugeriam ainda que a sub-população endotelial que morre por anoikisapós contato prolongado (24 horas) com matrizes de astrocitomas corresponde a células que já haviam entrado na fase S do ciclo celular, no início da incubação. A fim de nos aprofundarmos sobre a participação do ciclo celular neste processo, a expressão da proteína p27, um inibidor de quinases dependentes de ciclinas (CKI), também foi analisada. HUVECs incubadas com a matriz de astrocitoma apresentaram um aumento de 2 a 3 vezes na expressão de p27, quando comparada com HUVECs provenientes de sua matriz autóloga. No entanto, células endoteliais incubadas com matriz secretada por células U-373 MG silenciadas apresentaram um nível de expressão de p27 comparável ao das HUVECs incubadas com matriz secretada por células selvagens, indicando que a expressão de TN-C não modula, ou não está diretamente correlacionada à expressão da proteína p27. Este resultado sugere que outros componentes da matriz tumoral devam estar envolvidos na modulação do ciclo celular endotelial.

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No presente trabalho é descrita a obtenção de hidrazonas derivadas de isoniazida e de seus complexos de cobre(II) e gálio(III) candidatos a protótipos de fármacos antituberculose e antitumoral. Para investigar o efeito da modificação química sobre as bioatividades do fármaco isoniazida, foram preparados cinco derivados hidrazônicos: 2-piridinocarboxaldeído isonicotinoil hidrazona (HPCIH, 1), 2-acetilpiridina isonicotinoil hidrazona (HAPIH, 2), 2-benzoilpiridina isonicotinoil hidrazona (HBPIH, 3), 2-piridinoformamida isonicotinoil hidrazona (HPAmIH, 4) e 2-pirazinoformamida isonicotinoil hidrazona (HPzAmIH, 5), sendo o composto HPAmIH (4) inédito. Análises de ponto de fusão, espectroscopia de infravermelho (IV), espectrometria de massas, ressonância magnética nuclear (RMN), análise elementar e termogravimetria confirmaram a obtenção e pureza das hidrazonas. Foi determinada ainda a estrutura de HPCIH (1) por difração de raios X de monocristal. Essas moléculas foram efetivas em inibir o crescimento de cepas de micobactérias Mycobacterium tuberculosis H37Rv (ATCC 27294) nas concentrações testadas, com exceção de HPzAmIH (5). As hidrazonas HAPIH (2) e HBPIH (3) foram os compostos orgânicos mais ativos (concentração inibitória mínima, CIM = 0,625 g/mL), apresentando atividade antimicobacteriana apenas duas vezes inferior à do fármaco isoniazida.Quanto à ação contra células tumorais, as hidrazonas HAPIH (2) e HBPIH (3) foram as mais potentes contra as linhagens OVCAR-8 (tumor de ovário - humano), HCT-116 (tumor de cólon - humano) e SF-295 (glioblastoma humano), com inibições de 34,98 a 98,63% do crescimento celular, na concentração de 5 g/mL, enquanto que a isoniazida não foi efetiva contra as linhagens estudadas. Para avaliar o efeito da coordenação a metais sobre a atividade farmacológica das hidrazonas, foram sintetizados os complexos de cobre(II) e gálio(III), sendo todos inéditos: [Cu(HPCIH)Cl2]∙H2O (6), [Cu(HAPIH)Cl2]∙H2O (7), [Cu2(HBPIH)2Cl2]Cl2∙4H2O(8), [Cu(HPAmIH)Cl2]∙H2O (9), [Cu(HPzAmIH)Cl2]∙H2O (10), [Ga(HPCIH)2](NO3)32H2O (11), [Ga(HAPIH)(APIH)](NO3)22H2O (12), [Ga(HPAmIH)(PAmIH)](NO3)22H2O(13) e [Ga(HPzAmIH)(PzAmIH)](NO3)2H2O (14). Os complexos foram caracterizados por espectroscopia de IV, análise elementar, condutivimetria, RMN e espectroscopia eletrônica. Em geral, os complexos também demonstraram ação contra M. tuberculosis, sendo que apenas para 6, 9, 10 e 14 foi verificada melhor atividade em relação às hidrazonas livres. Os complexos metálicos foram tanto quanto ou mais ativos contra as células tumorais OVCAR-8, HCT-116 e SF-295 do que as hidrazonas livres. Merecem destaque os complexos 79 e 12, que apresentaram inibição de crescimento celular de 72,2100%, na concentração de 5 g/mL. Os resultados demonstram portanto que em geral os compostos 114 são menos ativos do que a isoniazida contra M. tuberculosis, enquanto que a modificação química do fármaco, formando-se hidrazonas com posterior complexação cobre(II) e gálio(III) constituíram uma estratégia interessante na obtenção de compostos mais potentes contra células tumorais

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Tem sido descrito que o acúmulo de mutações em proto-oncogenes e genes supressores de tumor contribui para o direcionamento da célula à carcinogênese. Na maioria dos casos de câncer, as células apresentam proliferação descontrolada devido a alterações na expressão e/ou mutações de ciclinas, quinases dependentes de ciclinas e/ou inibidores do ciclo celular. Os tumores sólidos figuram entre o tipo de câncer mais incidente no mundo, sendo a quimioterapia e/ou hormônio-terapia, radioterapia e cirurgia os tratamentos mais indicados para estes tipos de tumores. Entretanto, o tratamento quimioterápico apresenta diversos efeitos colaterais e muitas vezes é ineficaz. Portanto, a busca por novas moléculas capazes de conter a proliferação destas células e com baixa toxicidade para o organismo se faz necessário. Este trabalho teve por objetivo avaliar a ação antitumoral in vitro de um novo composto sintético, a pterocarpanoquinona LQB118, sobre algumas linhagens tumorais humanas de alta prevalência e estudar alguns dos seus mecanismos de ação. As linhagens tumorais estudadas neste trabalho foram os adenocarcinomas de mama (MCF7) e próstata (PC-3), e carcinoma de pulmão (A549). A citotoxicidade foi avaliada pelo ensaio do MTT e a proliferação celular pela contagem de células vivas (exclusão do corante azul de tripan) e análise do ciclo celular (citometria de fluxo). A expressão gênica foi avaliada por RT-PCR e a apoptose foi avaliada por condensação da cromatina (microscopia de fluorescência-DAPI), fragmentação de DNA (eletroforese) e marcação com anexina V (citometria de fluxo). Das linhagens tumorais testadas, a de próstata (PC3) foi a que se mostrou mais sensível ao LQB 118, e em função deste resultado, os demais experimentos foram realizados com esta linhagem tumoral. O efeito citotóxico do LQB 118 se mostrou tempo e concentração dependente. Esta substância inibiu a proliferação celular e prejudicou a progressão do ciclo celular, acumulando células nas fases S e G2/M. Buscando esclarecer os mecanismos desta ação antitumoral, demonstrou-se que o LQB 118 inibe a expressão do mRNA do fator de transcrição c-Myc e das ciclinas D1 e B1, e induz a apoptose de tais células tumorais. Em suma, o LQB 118 é capaz de inibir a proliferação das células tumorais de próstata, alterando a expressão do mRNA de alguns genes reguladores do ciclo celular, resultando em interrupção do ciclo celular e indução de apoptose, indicando este composto como um potencial candidato a futuro medicamento no tratamento do câncer de próstata.

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非晶状体βγ晶状体蛋白与三叶因子蛋白复合物(βγ-CAT)是从大蹼铃蟾(Bombina maxima)皮肤分泌物中分离的分子量为72 kDa的天然蛋白复合物.本研究通过激光共聚焦显微镜和Westem blot分析βγ-CAT在人脐静脉内皮细胞(HUVEC)中的细胞核转运机制,以及βγ-CAT对多株肿瘤细胞(HCT116,HT29,A375,Hela,THP-1等)的细胞毒效应.结果表明:βγ-CAT的α亚基中含有典型的GTP/ATPase的保守结构模体Walker A和Walker B,体外检测到βγ-CAT具有GTP/ATP水解酶和GTP/ATP结合活性.在细胞核转运过程中,βγ-CAT的α亚基和β亚基参与形成约150kDa含有泛素化修饰信号的大分子复合物,且泛素化修饰信号和βγ-CAT的α亚基和β亚基共定位于细胞内和融合于细胞核区域的转运囊泡小体中.βγ-CAT能够选择性的杀伤肿瘤细胞,诱导肿瘤细胞脱落和发生凋亡.上述结果为进一步深入研究阡βγ-CAT的细胞核转运和调节细胞功能的分子作用机制提供思路和线索.

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Two groups of antimicrobial peptides have been isolated from skin secretions of Bombina maxima. Peptides in the first group, named maximins 1, 2, 3, 4 and 5, are structurally related to bombinin-like peptides (BLPs). Unlike BLPs, sequence variations in maximins occurred all through the molecules. In addition to the potent antimicrobial activity, cytotoxicity against tumor cells and spermicidal action of maximins, maximin 3 possessed a significant anti-HIV activity. Maximins 1 and 3 were toxic to mice with LD50 values of 8.2 and 4.3 mg/kg, respectively. Peptides in the second group, termed maximins H1, H2, H3 and H4, are homologous with bombinin H peptides. cDNA sequences revealed that one maximin peptide plus one maximin H peptide derived from a common larger protein. (C) 2002 Elsevier Science Inc. All rights reserved.

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Jerdonitin is a P-II class snake venom metalloproteinase comprising metalloproteinase and disintegrin domains. In this study, we established a high-level expression system in Pichia pastoris and developed a purification strategy for the recombinant Jerdonitin. This recombinant Jerdonitin degraded fibrinogen at a level of activity comparable with its wild type. The effects of recombinant Jerdonitin on inhibiting ADP-induced human platelet aggregation were in a dose-dependent manner with an IC50 of 248 nM. In addition, we reported here that Jerdonitin can significantly inhibit the growth of several cell lines, including human liver cancer cells (Bel7402), human leukemia cells (K562) and human gastric carcinoma cells (BGC823). This study offers recombinant Jerdonitin that will be valuable for further functional and structural studies of Jerdonitin. (C) 2009 Elsevier Ltd. All rights reserved.

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结合作者在纳米磁性液体方面的研究经历,介绍了生物医学应用领域纳米磁性粒子的组成结构及特点,指出高分子改性纳米磁性粒子具有生物相容性好、稳定性强、载药量高的优点,并对目前高分子改性纳米四氧化三铁颗粒的制备方法及特点进行了对比分析。指出进一步研制磁响应性强、载药量高、粒度分布均匀的纳米磁性粒子,使之对癌细胞具有亲和作用,尽量避免对毛细血管网状内皮系统的清除,是未来肿瘤治疗领域纳米磁性粒子的研发目标,并对目前制备方法中存在的不足提出了改进的建议。


The biomedical application of biocompatible magnetic nanoparticles is introduced with respect to its composition and structure. It is indicated that polymer-coated magnetic nanoparticles have combined properties of long stability and higher drug loading capacity. The methods for the preparation of polymer-coated magnetite nanoparticles are discussed and compared. The preparation of magnetic nanoparticles with higher magnetization response, higher drug loading capacity, and narrow size distribution is to be researched in the future. For targeting delivery, the magnetic nanoparticles should also have high affinity to the tumor cells and could escape from human RES system. For this purpose, some suggestions have been given.

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齐墩果酸(OA)是一个分布广泛、含量丰富的天然三萜化合物,常以皂苷元的形式广泛存在于植物中,具有多种重要生物活性。但是OA许多活性较弱,且生物利用度低,限制了其在临床上的应用。一是OA水溶性差;二是抗癌活性仍与临床应用的抗癌药物相差比较大。 真菌在微生物转化中具有种类多、培养条件比较简单等特点,为了寻找到具有转化OA能力的菌株,采取一步发酵的方法,在18株实验室保藏真菌菌株中筛选到5株目的菌株,TLC分析显示有转化效果。 随后采用二步发酵的方法作为复筛,验证5株菌株转化能力,波谱分析结果表明5株菌株对OA确实有转化作用。 选择5株菌种中代号1F-2 2菌株作为放大实验菌株,分离转化产物,得到OA衍生物108(相对分子量414m/z)和1010(相对分子量340 m/z),分离出的产物用于活性检测。寻找到产物108的RP-HPLC分离条件,质谱得出二者相对分子质量。 为验证OA转化产物抗肿瘤活性,首次研究了OA对卵巢癌细胞株IGROV1和人乳腺癌细胞株MDA-MB-231作用,通过细胞增殖抑制实验、用MTT法检测细胞活性,结果表明齐墩果酸可降低卵巢癌细胞株IGROV1和乳腺癌细胞MDA-MB-231细胞增殖能力并呈剂量依赖性,对肿瘤细胞株的半数有效抑制浓度化IC50 分别为36.58μg/mL和38.8μg/mL (P<0.01)。OA能抑制肿瘤细胞活性,并且OA对卵巢癌细胞株IGROV1抑制活性高于乳腺癌细胞MDA-MB-231。 在此基础上,转化产物108和1010对卵巢癌细胞株IGROV1和人乳腺癌细胞株MDA-MB-231的抑制作用也进行研究,MTT实验结果表明,转化产物对两株癌细胞也有抑制活性(P<0.01)。 总之,本文工作为进一步开展齐墩果酸类化合物结构改造和抗肿瘤活性的研究奠定了基础。 Oleanolic acid (OA) is a triterpenoid widely distributed in the nature which possesses various important bioactivities. OA also serves as aglycon of many natural saponins. However, the relatively weak activities and poor bioavailability hinder its clinical use. Firstly, poor water-solubility results in worse bioavailability. Secondly, compared with clinical antitumor drug, the antitumor effect of OA has a great difference, it is worse. Many fungi have ability to transform nature products into a variety of derivatives, and transformation conditions of fungi are simple. Attempt to obtain fungi strains able to biotransform OA, we carried out the following experiments: To investigate the biotransformation 0f OA by strains supplied firstly, we used one-step fermentation method to screen the aimed strains from 18 fungus strains stored in our laboratory. On the basis of the initial screening experiments, we found 5 aimed strains. The TLC results showed that the 5 fungi strains could transform OA into other components derivatives. Then we used two-step fermentation method as secondly screening. We repeated the five strains to do the experiments, analytical data of the results proved the transformation indeed. In the followed experiments work, we chose 1F-2 2 strain as large-scale transformation fungus from the aimed fungi. We got two biotransformation products of OA by 1F-2 2, and named those derivatives 108 and 1010. We found RP-HPLC separation conditions of product 108. The two products were characterized by ESI-MS. To verify the anti-tumor activity of biotransformation products of OA, we studied the inhibition effect of oleanolic acid on the ovarian carcinomas IGROV1 and breast cancer cell line MDA-MB-231 firstly. With an assay based on a tetrazolium dye (MTT), the effects of various concentrations of oleanolic acid on ovarian carcinomas IGROV1 and breast cancer cell line MDA-MB-231 were studied. MTT method was used to measure the tumor cells viability. Compared with the control group, oleanolic acid can significantly inhibit the viability of the ovarian carcinoma cells IGROV1 and MDA-MB-231 breast cancer cell line (P<0.01), IC50 values were 36.58μg/mL or 38.8μg/mL. Oleanolic acid can inhibit the malignant tumor cells viability, and inhibitory activity of OA to ovarian carcinomas IGROV1 was higher than to breast cancer cell line MDA-MB-231. On this basis, we studied the anti-tumor activity of the two derivatives of OA [called 108 (414 m/z) and 1010(340 m/z)]. It came to the conclusion that the two derivatives also showed potent inhibitory effect on the growth of these tumor cells(P<0.01). Therefore, the results of studies will benefit the further investigating on the relationships of structures and antitumor activities of OA.

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Human hepatoma (SMMC-7721) and normal liver (L02) cells were irradiated with c-rays, 12C6+ and 36Ar18+ ion beams at the Heavy Ion Research Facility in Lanzhou (HIRFL). By using the Calyculin-A induced premature chromosome condensation technique, chromatid-type breaks and isochromatid-type breaks were scored separately. Tumor cells irradiated with heavy ions produced a majority of isochromatid break, while chromatid breaks were dominant when cells were exposed to c-rays. The relative biological effectiveness (RBE) for irradiation-induced chromatid breaks were 3.6 for L02 and 3.5 for SMMC-7721 cell lines at the LET peak of 96 keVlm 1 12C6+ ions, and 2.9 for both of the two cell lines of 512 keVlm 1 36Ar18+ ions. It suggested that the RBE of isochromatid-type breaks was pretty high when high-LET radiations were induced. Thus we concluded that the high production of isochromatid-type breaks, induced by the densely ionizing track structure, could be regarded as a signature of high-LET radiation exposure.

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Hepatoma and melanoma cells were exposed to C-12(6+) beams generated by HIRFL facility and gamma-rays and the cell response was studied by colony assays as well as the analysis of RBE of carbon ions was evolved. The survival curves of cells irradiated by heavy ions were different from those of cells irradiated by gamma-rays. And two kinds of cell showed the obvious discrepancy in response to the photon and ion irradiation. The results showed that heavy ions have special physical properties and mighty potency to kill cell in both single and fractional irradiation meanwhile it can kill tumor cells with high radioresistance more efficiently. When involved in clinical therapy, heavy ions will enhance the therapy efficiency and decrease the suffering of patients because it can impair the repair for sublethal damage of cells which can lead to fewer irradiation fractions.

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Three human malignancy cell lines were irradiated with Co-60 gamma-rays. Initial chromatid breaks were measured by using the chemically induced premature chromosome condensation technique. Survival curves of cells exposed to gamma rays was linear-quadratic while the efficiency of Calyculin A in inducing PCC of G(2) PCC was about five times more than G(1) PCC. A dose-dependent increase in radiation-induced chromatid/isochromatid breaks was observed in G(1) and G(2) phase PCC and a nearly positive linear correlation was found between cell survival and chromatin breaks. This study implies that low LET radiation-induced chromatid/isochromatid breaks can potentially be used to predict the radiosensitivity of tumor cells either in in vitro experimentation or in in vivo clinical radiotherapy.

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Aim: To determine whether the number of non-rejoining G2-chromatid breaks can predict the radiosensitivity of human cell lines. Methods: Cell lines of human ovary carcinoma cells (HO8910), human hepatoma cells (HepG2) and liver cells (L02) were irradiated with a range of doses and assessed both of cell survival and non-rejoining G2-chromatid breaks at 24 h after irradiation. Cell survival was documented by a colony assay. Non-rejoining G2-chromatid breaks were measured by counting the number of non-rejoining G2 chromatid breaks at 24 h after irradiation, detected by the prematurely chromosome condensed (PCC) technique. Results: A linear-quadratic survival curve was observed in three cell lines, and HepG2 was the most sensitive to gamma-radiation. A dose-dependent linear increase was observed in radiation-induced non-rejoining G2-PCC breaks measured at 24 h after irradiation in all cell lines, and HepG2 was the most susceptible to induction of non-rejoining G2-PCC breaks. A close correlation was found between the clonogenic radiosensitivity and the radiation-induced non-rejoining G2-PCC breaks (r=0.923). Furthermore, survival-aberration correlations for two or more than two doses lever were also significant. Conclusion: The number of non-rejoining G2 PCC breaks holds considerable promise for predicting the radiosensitivity of normal and tumor cells when two or more than two doses lever is tested.

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Caffeine, which specifically inhibits ATM/ATR kinases, efficiently abrogates the ionizing radiation (IR)-induced G2 arrest and increases the sensitivity of various tumor cells to IR. Mechanisms for the effect of caffeine remain to be elucidated. As a target of ATM/ATR kinases, BRCA1 becomes activated and phosphorylated in response to IR. Thus, in this work, we investigated the possible role of BRCA1 in the effect of caffeine on G2 checkpoint and observed how BRCA1 phosphorylation was regulated in this process. For these purposes, the BRCA1 protein level and the phosphorylation states were analyzed by Western blotting by using an antibody against BRCA1 and phospho-specific antibodies against Ser-1423 and Ser-1524 residues in cells exposed to a combination of IR and caffeine. The results showed that caffeine down-regulated IR-induced BRCA1 expression and specifically abolished BRCA1 phosphorylation of Ser-1524, which was followed by an override of G2 arrest by caffeine. In addition, the ability of BRCA1 to transactivate p21 may be required for MCF-7 but not necessary for Hela response to caffeine. These data suggest that BRCA1 may be a potential target of caffeine. BRCA1 and its phosphorylation are most likely to be involved in the caffeine-inhibitable event upstream of G2 arrest.

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本论文应用X射线和12C6+离子对不同肿瘤细胞:HL-60、K562、SMMC-7721和HepG2进行辐照,用克隆形成率和四唑盐比色法(MTT)测定四种细胞的辐射敏感性;通过流式细胞术测定细胞周期分布、细胞凋亡、ATM和SMC1蛋白的表达变化。应用免疫细胞化学法与流式检测相结合研究了γ-H2AX蛋白表达的时间效应与剂量效应之间的关系。实验结果表明,四种细胞的辐射敏感性由强到弱依次为HL-60>K562>SMMC-7721>HepG2。即ATM表达量越低的细胞对辐射越敏感,周期阻滞水平越低,细胞凋亡越明显,但辐照后ATM蛋白的表达无显著增加,说明ATM的表达量和功能状态与细胞辐射敏感性有关,但其表达水平不能完全反映ATM蛋白激酶的活性。对ATM表达量差异最显著的HepG2和HL-60细胞来说,辐照前SMC1的表达水平与细胞S期的含量没有直接关系,辐照后SMC1蛋白的上调表达在S期阻滞修复中发挥明显的作用。辐照后1h,HL-60和HepG2细胞的H2AX磷酸化水平随吸收剂量的增加呈线性正相关,但曲线斜率与细胞辐射抗性的差异没有直接的联系。γ-H2AX的消失率与存活分数存在良好的相关性,HepG2细胞抗辐射能力强,这一时间短,HL-60细胞抗辐射能力弱,这一时间长。可以用γ-H2AX的消失速率来评估细胞的辐射敏感性。 以SMMC-7721细胞为同步化细胞模型发现,与其它同步化方法相比,步进电机旋转同步化培养法对细胞损伤最小,同步化效率最高,达到M期>90%,GO/G1期>80%,S期>60%,G2/M>50%。同种射线辐照,GO/G1期SMMC-7721细胞的存活相对G2/M期来说较高。12C6+离子辐照明显减小了二者敏感度的差异性

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目的: 探讨不同LET辐射对健康人外周血淋巴细胞的遗传损伤效应;了解重离子辐射诱导人血淋巴细胞染色体畸变的特点;研究用G2期染色体畸变预测肿瘤细胞辐射敏感性的可行性。材料与方法:采用兰州近代物理研究所重离子研究装置产生的12C离子和兰州大学第一附属医院放疗科提供的X射线照射健康人外周血,用常规染色体分析技术和姊妹染色体差别染色法研究不同LET辐射对健康人血淋巴细胞中期染色体的损伤效应、高LET辐射的剂量率效应、时程效应和染色体畸变的特点;用Calyculin A诱导间期染色体凝集技术研究12C 离子对淋巴细胞G2期染色体的损伤效应。用60Coγ射线照射人卵巢癌细胞和肝癌细胞,以细胞克隆存活率和G2期染色体畸变为生物学终点,探讨用G2期染色体畸变预测肿瘤细胞辐射敏感性的可行性。 结果与结论 1. 不同LET辐射诱导‘双+环’畸变与剂量之间存在良好的线性平方关系, 12C 离子诱导的畸变在细胞间的分布不符合泊松分布; 12C离子的相对生物学效应随着LET的增大而增大;12C离子诱导染色体畸变在1-5 Gy/min的范围内不存在剂量率效应;在0-4 Gy的剂量范围内不存在时程效应,说明培养48小时后中期‘双+环’畸变能很好的反应12C离子对淋巴细胞的损伤效应。本研究可以帮助人们了解重离子的相对生物学效应,为病人健康组织的保护以及放射医师的防护提供重要的理论数据。 2. LET为34.6 keV/μm的12C离子诱导淋巴细胞G2-期染色体数目畸变与剂量之间存在良好的线性关系(r=0.99);最长G2-PCC与最短G2-PCC的长度之比与剂量之间存在良好的线性平方关系(r2=0.96)。表明有希望用G2-期染色体畸变评估重离子的相对生物学效应和估计重离子的辐射剂量,也为合理评估空间混合辐射场中重离子辐射所占比例提供了两个潜在的指标。 3. LET为34.6 keV/μm12C 离子诱导的畸变,除大部分染色体型畸变外,还出现少量的染色单体畸变,这一现象在理论上突破了传统的认识,对重离子辐射损伤机理的认识有重要意义。这可能是由于重离子特殊的离子径迹结构诱导染色单体畸变。重离子相对生物学效应是相对于常规射线而言的,而常规射线辐照G0期淋巴细胞只产生染色体型畸变,因此这一现象的存在对重离子相对生物学效应的确定提出了新的问题。 4. γ射线诱导肿瘤细胞G2期染色体初始断裂畸变和修复24小时后残余断裂畸变都与辐射剂量有良好的相关性;肿瘤细胞克隆存活率与G2染色单体初始断裂(r=0.96)和修复24小时后残余断裂(r=0.91)都有一定的相关性,比较而言,G2染色单体初始断裂畸变能更好的反映肿瘤细胞的辐射敏感性,预示G2染色单体初始断裂畸变有希望成为肿瘤细胞辐射敏感性的预测指标。 5. 2 Gyγ射线诱导的G2-染色单体断裂畸变,有近65% 的断裂在辐射后24小时内得以修复;对G2等点染色单体断裂畸变,在辐射后24小时内只有20%左右得以修复;两类畸变的修复主要发生在辐射后2小时内。 6. 在用G2-assay法测定染色体畸变的实验中,给予较高剂量时,很难获得足够的中期细胞以供观察。用G2-assay和G2-PCC技术获得的数据都与细胞克隆存活率有一定的相关性,比较而言,后者的相关性要好一些。表明G2-PCC技术可以作为细胞存活实验和用常规染色体畸变分析放射敏感性的替代方法