诱导染色体不稳定与非整倍性的Ska1蛋白影响前列腺癌发生与发展的机制研究

Chromosome instability (CIN) describes an increased rate of chromosome missegregation in mitosis resulting in a failure to maintain the correct chromosomal complement. CIN leads to the occurrence of alterations in tumor suppressor genes and oncogenes, and is associated with tumorigenesis and tumor progression. Spindle and kinetochore-associated 1 (Ska1), a microtubule-binding subcomplex of the outer kinetochore, is a newly identified protein that is essential for proper chromosome segregation. Recent studies indicate Ska1 facilitates microtubule depolymerization-coupled motility. In pilot studies, we found that Ska1 was highly overexpressed in human prostate cancer tissues compared to adjacent normal tissues. Ska1 was also highly overexpressed in prostate caner cell lines compared to normal prostate epithelial cells. Overexpressed Ska1 promoted multipolar spindle formation, which caused aberrant chromosome segregation and chromosome instability. In this project, we aim to study 1) whether Ska1 can lead to prostate tumorigenesis; 2) whether Ska1 can affect prostate tumor progression by using transgenic mouse models, normal prostate epithelial cells and cancer cell lines. In order to identify drug targets for prostate cancer therapy, we also proposed to find the other components of Ska complex and related genes by the use of microarray analysis and protein chips. By overexpression or knowing down of these gene expression, it could facilitate us to better understand the cellular and molecular mechanisms underlying Ska1 induced CIN. This study could reveal Ska1-induced CIN is a cause or a consequence of prostate tumor initiation; Ska1-induced CIN promote or suppress prostate tumor progression, and find new moleculars that are associated with Ska1-induced CIN.

染色体不稳定是指有丝分裂后细胞发生染色体丢失或获得的概率增强；其能导致抑癌或致癌基因的缺失或多拷贝，并与肿瘤的发生与发展相关。Ska1是新型的微管与着丝粒结合蛋白，能够协助微管牵引着丝粒完成有丝分裂，影响染色体的分离。本项目预实验表明Ska1在前列腺癌细胞与组织中过表达，过表达的Ska1通过促进癌细胞多级纺锤体的形成，引起染色体的不稳定与非整倍性。本项目通过体内外实验，利用转基因小鼠模型、正常前列腺上皮和癌细胞系，研究Ska1能否通过促进染色体的不稳定影响前列腺癌的发生与发展。继而由高通量基因与蛋白芯片分析获得Ska1相关的基因和蛋白；揭示Ska1通过这些分子促进染色体不稳定的分子与细胞学机制。预计本项目的完成可发现Ska1与前列腺癌发生与发展的关系；Ska1及其相关分子影响染色体不稳定的分子与细胞机制。本项目可为前列腺癌的发生发展提供新的理论基础，并为临床前列腺癌的诊断提供新靶点。

纺锤体与着丝粒结合蛋白SKA1具有保持有丝分裂中纺锤体微管与着丝粒稳定结合、确保有丝分裂顺利完成的作用。本项目旨在研究SKA1在前列腺癌发生与发展过程中的作用。项目研究表明：SKA1蛋白的过表达诱导人前列腺上皮细胞中心粒的扩增、多中心体的产生并促进前列腺癌的发生。. 我们的实验显示小鼠前列腺特异性过表达SKA1后，小鼠产生前列腺癌前病变或前列腺肿瘤，证明SKA1为致癌基因，其过表达能够促进前列腺癌的发生。免疫组化与实时活体成像表明SKA1除了在有丝分裂前期至末期位于纺锤丝与着丝粒交界处外，还富集于中心体并有可能是新型的中心粒蛋白。随后实时活体成像、过表达、siRNA抑制其表达的体外实验均表明SKA1 是参与中心粒复制的重要蛋白，其表达水平可调控前列腺上皮细胞中心粒的复制与中心体的数目。 . 尽管果蝇体系中已经证实中心体过度扩繁能够引起肿瘤的发生，然而尚未有足够的证据证实其同样影响哺乳动物的肿瘤发生。并且，迄今为止，鲜有单个基因过表达引起转基因小鼠前列腺癌的报道。我们转基因老鼠的体内证据以及人前列腺上皮细胞裸鼠皮下成瘤的实验表明中心体的过度扩繁能够促进哺乳动物前列腺肿瘤的发生，这是一个重大的发现。. 本研究内容于2014年10月在国际著名病理学杂志《The Journal of Pathology（IF: 7.33），并于2014年7月在Cell子刊《Stem Cell Reports》上发表文章。

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