凝缩蛋白家族成员NCAPH影响结直肠癌发生发展的功能与机制研究

Colorectal cancer is one of the major malignancies worldwide, whose pathogenesis is complex and requires the accumulated alteration of multiple genes and signaling pathways. Condensins are multi-protein complexes which play pivotal roles in chromosome assembly and segregation during mitosis, meiosis and even tumorigenesis. Using tissue microarrays by immunohistochemistry and hematoxylin-eosin staining, we found that non-SMC condensin I complex subunit H (NCAPH) in colon cancerous tissues was higher than that in all corresponding adjacent non-cancerous tissues. We then characterized the exact function of the NCAPH in colon cancer. We provided evidences showing that NCAPH is highly expressed in colorectal cancer cell lines comparing with normal human colonic epithelial cells (HCoEpiC), and identified many NCAPH mutations in colon cancer patients. We found that depletion of NCAPH inhibits colon cancer cell proliferation, migration in vitro and xenograft tumor formation in vivo. Furthermore, NCAPH knockdown promotes cell apoptosis and cell cycle arrest at G2/M phase. Interestingly, the NCAPH high expression in tumor tissues of colon patients had a significantly better prognosis and survival rate than low expression patients, suggesting that NCAPH high expression promotes colonic cancerous cell proliferation, on the other hand, may also sensitize these cells responding to chemo- or radio-therapies. Collectively, these findings reveal an important role of NCAPH in colorectal cancer, indicating that NCAPH could be used as a new therapeutic target in future. Thus, we decided to use molecular, cellular, biochemical and xenograft tumor formation in vivo models to further characterize the mechanistic roles of NCAPH in colorectal cancer including cancer stem cells, which will definitely benefit our studies and clinical applications in colorectal cancer field in future.

结直肠癌是国内外最主要的消化系统恶性肿瘤之一，其发病机制尚不清楚。申请人前期通过亲和纯化和蛋白质谱分析，筛选得到Hedgehog(Hh)信号通路Smoothened(Smo)的新互作蛋白：凝缩蛋白家族成员NCAPH (non-SMC condensin I complex subunit H)。研究发现，NCAPH在结肠癌肿瘤细胞和组织中高表达，敲低NCAPH的表达可以抑制结直肠癌细胞的增殖、迁移和裸鼠移植瘤形成能力。同时发现肿瘤组织NCAPH高表达，且接受过放化疗的结直肠癌患者预后更好，提示其可增强肿瘤细胞对放化疗的敏感性。申请人拟：1）研究NCAPH对肿瘤细胞增殖、凋亡、迁移和放化疗敏感性等的影响；2）利用裸鼠荷瘤实验研究其体内功能；3）结合临床关联性分析和多种组学方法，解析其利用Hh通路依赖或非依赖的方式影响结直肠癌发生发展的分子机制。该项目将为结直肠癌的研究及临床治疗提供新的靶点。

NCAPH作为condensin I蛋白家族的一员，其在肿瘤特别是结直肠癌中的功能与分子调控机理并不清楚。申请人通过本项目研究发现，NCAPH在结肠癌患者的肿瘤组织中,相比癌旁的正常组织表达水平更高。在结直肠癌肿瘤细胞中抑制NCAPH的表达，可以显著抑制肿瘤细胞的增殖、迁移和裸鼠移植瘤形成等能力。深入研究发现靶向调控NCAPH表达水平的非编码RNA：miR-133b在肿瘤组织和肿瘤患者外周血中都低表达，导致NCAPH持续稳定高表达。高水平表达的NCAPH蛋白，通过与蛋白激酶Akt1竞争结合Wnt信号通路下游转录因子β-catenin，抑制Akt1磷酸化修饰β-catenin蛋白，阻止了β-catenin被泛素化修饰及蛋白酶体降解，从而使得β-catenin蛋白稳定持续表达并激活Wnt信号通路和肿瘤干细胞活性，进一步促进了肿瘤的发生和发展。运用以上实验方法和策略，申请人同步解析新分子：PAQR4、YTHDF1、GLT8D1、RETSAT等，在肿瘤中与NCAPH协同或单独影响肿瘤发生发展的功能和分子机制。以上研究成果发表标注文章13篇，其中包含1篇Molecular Cancer、1篇Cell Research、2篇Signal Transduction and Targeted Therapy、2篇Nature Communications、1篇Theranostics、1篇Cancer Letters、2篇Frontiers in Cell and Developmental Biology、1篇Cell Death & Disease、1篇Aging和1篇四川大学学报。申请国家发明专利7项，获得授权4项。共培养博士毕业生4人，硕士毕业生9人。为肿瘤临床诊断和治疗提供了新的科学数据和靶点。