基于核酸适配子的循环肿瘤细胞检测研究进展

循环肿瘤细胞（circulating tumor cell,CTC）是从肿瘤病灶脱落后进入血液循环的肿瘤细胞,在肿瘤的微转移检测、病情评估、疗效及预后评判等方面具有重要价值,但因其在血液中数量极少,难以检测,临床应用进展缓慢。近年来,随着生物学技术的不断发展,CTC的富集及检测新方法不断进步,其中基于核酸适配子的富集及检测方法不但能快速高效捕获和无损释放CTC,还能定性、定量分析CTC,甚至能检测出血液中的单个CTC和不同亚群的肿瘤细胞,具有良好的应用前景。      

适配子的临床应用前景展望

适配子(aptamer)是通过指数富集配体的系统进化(SELEX)技术得到的与靶分子特异结合的小分子核苷酸,它具备很多优点,在医疗界备受关注.适配子可以替代传统抗体,并显示出更多的优越性.与目前应用于临床研究或制药的几种核苷酸比较,适配子的应用前景更乐观.     

适配子的临床应用前景展望

适配子(aptamer)是通过指数富集配体的系统进化(SELEX)技术得到的与靶分子特异结合的小分子核苷酸,它具备很多优点,在医疗界备受关注.适配子可以替代传统抗体,并显示出更多的优越性.与目前应用于临床研究或制药的几种核苷酸比较,适配子的应用前景更乐观.     

核酸适配子及其在肿瘤标志物研究中的应用

适配子是应用指数富集的配体系统进化（SELEX）技术从单链随机寡核苷酸文库中筛选得到的能与靶标高特异性和高亲和力结合的单链寡核苷酸配体。以肿瘤标志物为靶标的核酸适配子不仅可以用于建立敏感而特异的肿瘤标志物检测新方法,也可用于捕获血液中的肿瘤细胞继而进行相关分析,还可携带药物对肿瘤进行靶向治疗,以及用于阻断靶分子的功能而实现肿瘤的生物治疗。肿瘤标志物的适配子筛选和应用是肿瘤研究的一个新领域。      

转移性大肠癌LoVo细胞特异性核酸适配子W14的生物活性和血浆稳定性

目的：分析转移性大肠癌LoVo细胞特异性核酸适配子W14的生物活性和血浆稳定性。方法: 采用荧光显微镜流式细胞术分析W14在25 ℃和37 ℃下与靶细胞LoVo的特异结合活性;流式细胞术检测W14在血浆环境下对LoVo细胞的特异识别能力;37 ℃ 下W14分别在完全培养基和人血浆中孵育0.5、1、1.5、2、3、4、6 h, 琼脂糖凝胶电泳检测W14的生物稳定性;用2、4、8、10 μmol/L 的W14处理LoVo细胞24、48、72 h,MTS实验测定W14的细胞毒性。结果: W14在不同温度和血浆环境中以及不同温度条件下都能特异性地识别和结合靶细胞LoVo,能稳定地存在于血浆中6 h不发生降解,且对细胞没有明显的毒性作用。结论: 转移性大肠癌特异性核酸适配子W14具有良好的适应能力和特异性结合能力,有较好的生物稳定性和低毒性,适应于人体内应用。     

肿瘤细胞疫苗及其研究进展

癌症复发与转移是恶性肿瘤治疗失败的主要原因之一。立足于整体,用肿瘤细胞疫苗（简称瘤苗）特异性主动免疫来调节和提高机体内固有抗肿瘤能力是目前正在积极探索的生物反应调节疗法（ＢｉｏｌｏｇｉｃａｌＲｅｓｐｏｎｓｅＭｏｄｉｆｉｅｒＴｈｅｒａｐｙ,ＢＲＭＴ）的...     

药物诱导的肿瘤细胞凋亡研究进展

细胞调亡又称为程序化细胞死亡，是在生理或某些病理条件下细胞主动参与的“自杀”过程。近年来的研究表明，许多抗癌药物均能诱导肿瘤细胞发生程序化死亡，可能是这些药物抑制肿瘤生长的机理之一。药物诱导的肿瘤细胞调亡过程包含一系列有条理的形态和生化事件，包括基因表达和ＤＮＡ损伤等等。细胞凋亡现象为肿瘤化疗提供了新思路和靶点，对此过程机理的深入研究将更好地指导肿瘤化疗实践。     

核酸适配子在肿瘤诊治中的新进展

0 引言 1990年Tuerk[1]和Ellington[2]报道了一种在体外应用随机单链寡核苷酸文库筛选、扩增特定配体的技术,这种技术可得到与靶分子具有高亲和力、高特异性结合的寡核苷酸序列,此技术称为指数富集的配体系统进化(SELEX)技术.此后该技术不断得到改良和发展,筛选出多种靶标的特异性适配子,在基础研究、临床诊断、药物研发等方面得以广泛应用,尤其在肿瘤的诊断[3]、靶向药物输送和靶向治疗_]方面表现出巨大的潜力,本文就核酸适配子在肿瘤诊治中的近期进展综述如下.     

姜黄素诱导肿瘤细胞凋亡机制的研究进展

姜黄素是从姜科姜黄素属植物中提取的一种多酚类化合物,具有抗肿瘤、 抗炎、 抗氧化等作用,姜黄素能够在多方面起到抗肿瘤作用, 而且不良反应小。姜黄素诱导肿瘤细胞凋亡,是其发挥抗肿瘤作用的重要机制之一。本文主要针对姜黄素诱导肿瘤细胞凋亡的作用靶点、作用途径及分子机制的研究进展作一综述。     

有机酸诱导肿瘤细胞凋亡研究进展

与传统的杀伤肿瘤细胞的方式相比，通过诱导肿瘤细胞凋亡进行肿瘤治疗的方法具有明显的优越性。有机酸类化合物是能够通过各种途径诱导肿瘤细胞凋亡的重要药物之一，对于寻找高效低毒的诱导肿瘤细胞凋亡的药物的研究具有重要的意义。本文就饱和脂肪酸、不饱和脂肪酸、含苯环的脂肪酸、维生素类酸、稠环类酸等五类有机酸诱导肿瘤细胞的凋亡以及其诱导机制的国内外研究现状进行简要综述。     

SELEX技术及其在肿瘤研究中的应用

配体指数级富集系统进化技术(SELEX)是一种很有发展前途的组合化学技术,它可筛选出针对靶分子的高特异性和高结合力的适配子.适配子可识别、结合特定靶分子或作为功能阻断物质或直接阻断疾病进程,所以适配子可应用于临床疾病的诊断和治疗.现综述SELEX技术及其在肿瘤研究中的应用前景.     

Metastasis‐focused cell‐based SELEX generates aptamers inhibiting cell migration and invasion

Metastasis, the capacity of tumour cells to disseminate and grow at distant sites, is the main factor in cancer mortality. Compounds inhibiting migration and invasion of cancer cells are promising candidates for anticancer therapy strategies. We have generated nuclease‐resistant RNA ligands (aptamers) recognizing highly metastatic cells with high affinity and specificity, and inhibiting their migratory and invasive potentials. Aptamers were generated by a cell‐based subtractive SELEX technology using isogenic cell lines with similar tumorigenic potentials but opposite metastatic aggressiveness. Two aptamers, E37 and E10, bound specifically to the metastatically aggressive cell line and altered the phosphorylation of several tyrosine kinases. Fluorescent microscopy showed intracellular uptake of E37, in contrast to membrane binding of E10. Both aptamers inhibited migration of tumour cells in culture (50 and 85% inhibition with respect to control pool for E10 and E37, respectively) while only E10 inhibited cell invasion (?75% with respect to control pool). This proof‐of‐concept study demonstrates the potential of cell‐based SELEX to yield ligands that selectively recognize aggressive metastatic cells and inhibit phenotypes linked to metastatic potential.     

肿瘤特异性抗原研究与肿瘤特异性免疫治疗

近一个世纪以来 ,肿瘤抗原的研究一直处于肿瘤免疫学的核心地位 ,而肿瘤免疫治疗也随着肿瘤抗原研究的深入不断发展 ,并形成肿瘤生物治疗的主流。肿瘤免疫学的历史发展过程 ,说明只有坚持肿瘤抗原研究才能更好的发展肿瘤免疫治疗。1　肿瘤特异性抗原研究肿瘤细胞是正常细胞的“非己”化。肿瘤细胞在“非己”化过程中 ,必然会产生一些“非己”的成分。在这里 ,我们把肿瘤的这种“非己”成分限定为只存在于肿瘤细胞 ,而正常组织细胞不具有的细胞膜成分 ,通常称为肿瘤抗原。机体免疫系统可以识别任何“非己”的成份 ,并通过免疫应答将其排除。…     

Surface-immobilized aptamers for cancer cell isolation and microscopic cytology

Exposing rare but highly malignant tumor cells that migrate from the primary tumor mass into adjacent tissue(s) or circulate in the bloodstream is critical for early detection and effective intervention(s). Here, we report on an aptamer-based strategy directed against epidermal growth factor receptor (EGFR), the most common oncogene in glioblastoma (GBM), to detect these deadly tumor cells. GBMs are characterized by diffuse infiltration into normal brain regions, and the inability to detect GBM cells renders the disease surgically incurable with a median survival of just 14.2 months. To test the sensitivity and specificity of our platform, anti-EGFR RNA aptamers were immobilized on chemically modified glass surfaces. Cells tested included primary human GBM cells expressing high levels of the wild-type EGFR, as well as genetically engineered murine glioma cells overexpressing the most common EGFR mutant (EGFRvIII lacking exons 2-7) in Ink4a/Arf-deficient astrocytes. We found that surfaces functionalized with anti-EGFR aptamers could capture both the human and murine GBM cells with high sensitivity and specificity. Our findings show how novel aptamer substrates could be used to determine whether surgical resection margins are free of tumor cells, or more widely for detecting tumor cells circulating in peripheral blood to improve early detection and/or monitoring residual disease after treatment.     

核酸适配子及其在肿瘤诊断与治疗中的应用

核酸适配子是采用指数富集配体的系统进化(SELEX)技术从随机单链寡核苷酸库中筛选出的能与靶物质高特异性、高亲和力结合的配体,其特性在很多方面优于抗体,在分子识别研究中具有重要价值,可用于靶物质的测定、阻断靶物质的生物活性,在肿瘤的诊断和治疗中有着广阔的应用前景。     

核酸适配子及其在肿瘤诊断与治疗中的应用

核酸适配子是采用指数富集配体的系统进化（SELEX）技术从随机单链寡核苷酸库中筛选出的能与靶物质高特异性、高亲和力结合的配体,其特性在很多方面优于抗体,在分子识别研究中具有重要价值,可用于靶物质的测定、阻断靶物质的生物活性,在肿瘤的诊断和治疗中有着广阔的应用前景。     

Tumor cell differentiation by butyrate and environmental stress

The present study shows that stress signaling plays a role in differentiation of K562, PANC1, HT29 and HL60 tumor cells: (1) Butyrate induced differentiation in K562, PANC1, and HT29 cells can be inhibited by SB203580, a specific inhibitor of p38 stress activated protein kinase. (2) Heat shock and hyperosmolarity increase expression of differentiation markers in K562, HT29, HL60 and in K562, PANC1, and HT29 cells, respectively. (3) Conversely, environmental stress induced differentiation in K562, HT29, and PANC1 cells can be inhibited by SB203580 and quercetin, a compound with heat shock pathway inhibiting activity. (4) Butyrate and environmental stress enhance either additively or synergistically differentiation of K562, HT29, PANC1 or HL60 cells, respectively. Stress signaling pathways might be an interesting pharmacologic target for differentiation therapy of malignant disease.     

Tumor progression in nude mice and its representation in cell culture

Varying dilutions containing from 10(6) to 10(3) spontaneously transformed Balb/3T3 cells were inoculated into nude mice [N:NIH(S)II]. Less than half the mice inoculated with 10(3) cells developed tumors. The higher concentrations of cells produced visible tumors in all mice within 2-3 weeks, and these tumors grew rapidly to large sizes. Some tumors initiated by the lower concentrations of cells arose quickly, but others were greatly delayed in onset, then grew slowly, if at all, for several weeks before a rapid acceleration. The delayed acceleration can be considered a form of tumor progression. When first explanted into culture, cells from the early tumors multiplied somewhat more slowly than the parental cells that initiated the tumors, but narrowed the gap in a few weekly passages. By contrast, only a small fraction (less than or equal to 0.001) of cells from the longest delayed tumors could sustain multiplication in culture, although flow cytometry revealed them to have been a rapidly multiplying population when explanted. A relatively large fraction of these explanted tumor cells incorporated a 1-hour pulse of [3H]thymidine into DNA, although at a low rate. The shift to culture apparently slowed progress through the S-period of the cell cycle. The multiplication rate of cell populations from the delayed tumors increased in successive passages in culture. There was great heterogeneity in growth capacity among clones of the tumor cells. The growth rates of some clones declined to the point of extinction, those of others remained constant for several weeks, while those of still others steadily increased in growth rate. The low initial cloning efficiency of cells from the delayed tumors and the heterogeneity of growth rates among the clonable cells indicate that selection plays a major role in the increase of the growth capacity of the cell population. The steady increase in growth rates within clones suggests that physiological adaptation also contributes to the progressive growth of the tumor populations in culture. The results constitute a rationale for using the progressive growth of cells in culture as a model system for discriminating the types of cellular changes that underlie tumor progression.     

Tumor cell recognition by natural killer cells

Natural killer (NK) cells contribute to the immune defense against cancer and viruses. Tumor cells and infected cells that downregulate the HLA class I antigen expression are targets for NK cell responses because NK cell activation is controlled by a repertoire of inhibitory receptors with different HLA class I specificities. The clonal distribution of these inhibitory receptors permits NK cell recognition of target cells that have lost expression of a single HLA-B or HLA-C allotype. Several activation receptors on NK cells have been identified that contribute to tumor cell recognition. One such receptor, NKG2D, is expressed by all NK cells and binds to inducible ligands on tumor cells.