【作者】 曹磊；

【导师】 章翔； 曹卫东；

【作者基本信息】 第四军医大学 ， 外科学， 2008， 硕士

【摘要】 星形细胞瘤是指以星形胶质细胞来源的瘤细胞所组成的肿瘤,约占神经上皮源性肿瘤的75%。按肿瘤的生物学特性星形细胞瘤可分两大类:一类边界清楚,较少向周围脑组织浸润,包括毛细胞星形细胞瘤、室管膜下巨细胞性星形细胞瘤与多形性黄色星形细胞瘤,其临床表现与病情发展均有各自的典型特征,预后较好;另一类星形细胞瘤则无明显边界,向周围脑组织广泛浸润,肿瘤细胞呈间变特性,包括星形细胞瘤、间变性星形细胞瘤及多形性胶质母细胞瘤等。此类肿瘤病程为进展性,该肿瘤患者中的大部分即使手术后接受放疗、化疗等综合治疗,疗效依然欠佳。其中,恶性程度最高的多形性胶质母细胞瘤患者经综合治疗后,其中位生存期也仅为1年。在肿瘤的发生、发展中有多种基因的连锁改变,这些改变最终使肿瘤细胞获得无限增殖的生长优势,从而促进肿瘤的发生和发展。肿瘤细胞获得对抗细胞凋亡的能力是其中的关键环节。因此,发现和阐明瘤细胞逃避细胞凋亡的机制有助于研究肿瘤治疗的新方法。14-3-3蛋白是一类高度保守的小分子多功能酸性二聚体蛋白。它们是在1967年一项有关脑蛋白的研究中被发现的,并根据其在随后的蛋白电泳中的位置而命名的。最初只发现这类蛋白在神经元中有大量的表达,但随后的研究发现它们存在于所有的真核生物中。目前,已发现这类蛋白在哺乳类有机体中有由不同基因编码的7个亚型及200多个能与其相互结合的配体分子。研究还发现14-3-3蛋白在多种细胞生理过程中起重要作用。近年的研究还提示,14-3-3蛋白有可能通过抑制细胞凋亡而参与肿瘤的发生和发展。曹卫东博士曾经研究并证实了14-3-3蛋白在胶质瘤中有表达,但是具体哪一个亚型有表达还需要进一步的研究。基于此,本科题从以下方面进行探讨。14-3-3蛋白各亚型在人脑星形细胞瘤中的表达及意义:采用免疫组化ABC法检测了10例正常脑组织、80例人脑星形细胞瘤石蜡标本中14-3-3蛋白各亚型的表达情况。结果显示,在正常脑组织中,14-3-3蛋白7个亚型主要表达于神经元胞体和突起,但是ε、ζ和θ亚型在胶质细胞的胞浆中有弱表达。在大部分星形细胞瘤组织中,β、ε、ζ、η和θ亚型都有表达,且它们的免疫反应评分随着肿瘤的级别增高而升高。结果提示,这5个亚型在人脑星形细胞瘤的发生中可能起着重要的作用,尤其是β和η亚型。综上所述,本课题在国内外首次研究了14-3-3蛋白各亚型在人脑星形细胞瘤中的表达情况,结果表明,β和η亚型可能是人脑星形细胞瘤形成和发展过程中的两个关键亚型,其作用机制可能是它们通过抑制肿瘤细胞凋亡来促进星形细胞瘤的发生和发展,而ε、ζ和θ亚型或许对正常脑的功能有关,并且参与肿瘤的恶性进展,但作用相对较弱。以14-3-3β和η亚型为靶点来设计新的脑星形细胞瘤治疗方法是很有前景的。更多还原

【Abstract】 Astrocyte tumors are the most frequent brain tumors and are among the most aggressive of all human malignancies. It accounts for about 50%~60% of human brain tumor in adults. Even with best conventional therapy, the prognosis is dismal. The mean survival time after surgical intervention is within one year in glioblastoma multiformes which is the most malignany in astrocytoma. Astrocyte tumors development occurs by means of a series of dynamic changes in the genome that confer growth advantages to transformed cells. Among them, suppression of apoptosis is a common phenomenon. By extending the lifespan of abnormal cells, accumulation of transforming mutations can occur, thereby promoting development of the malignant phenotype and resistance to conventional cytotixic agents. Therefore, futher understanding the mechanism of how astrocytoma cells evading apoptosis is crucial for designing new ways restoration of apoptotic pathways in astrocytomas.The term14-3-3 refers to family fo highly conserved, small, acidic dimeric proteins of 28-33 kDa. They received their name in 1967 during a systematic classification of brain proteins that was based on their fraction number on anion-exchange chromatography and migration position in gel electrophoresis. Proteins of this family have been found in all eukaryotic organisms studied so far. However, the highest tissue concertration of 14-3-3 proteins is found in the brain,comprising about 1% of its total soluble protein. There are seven known mammalian 14-3-3 proteins encoded by separate genes. Up to now, over 200 14-3-3-binding ligands are identified, and the number of 14-3-3 binding partners is still increasing. Considering the number of binding partners, it is not surprising that 14-3-3 proteins play crucial roles in regulating multiple cellular processes-they include the maintenance of cell cycle checkpoints and DNA repair, the prevention of aoptosis, the onset of cell differentiation and senescence, and the coordination of cell adhesion and motility. In addition to their important roles in many mormal physiology processes, 14-3-3 proteins have attracted much recent interest in the etiopathogenesis of human cancers owing to their involvement in the prevention of apoptosis. At present, there is no research concerning the expression and role of 14-3-3 isoforms in astrocytoma. In this study, we addressed this issue from the following aspect.The expression and its significance of 14-3-3 isoforms in astrocyte tumors: The expression of 14-3-3 isoforms was detected in 80 cases of formalin-fixed, paraffin embedded archival tumor tissue from patients with astrocyte tumors, and 10 normal human brain tissues by immunohistochemical ABC method. The results showed that, in the normal control brains, 14-3-3 isoforms immunoreactivity was localized mainly in the neuronal somata and processes, while only weak expression ofε,ζandθwas found in some glial cells. Howeverβ,ε,ζ,ηandθisoforms’immunoreactivity was seen in the majority of astrocyte tumor samples and its immunoreactivity score was increased markedly with an increase in the pathologic grade of human astrocyte tumors. These results indicate that the five isoforms ,especiallyβandηisoforms,may play an important role in tumorigenesis of human astrocyte tumors.In summary, in the first time, this research suggested thatβandηisoforms may be key proteins in initiation and progress of human astrocyte tumors, its mechanism may involve the anti-apoptotic effect of 14-3-3 isoforms in the tumorogenesis and development of astrocyte tumors. 14-3-3 isoforms may be considered as a potential and promising target for gene therapy of astrocyte tumors.更多还原