RYBP在肺癌发生发展中的作用及分子机制研究

RYBP has been identified as the memeber of PcG family recently.In addition to its gene transcriptional regulation due to the component of PRC1 complex, RYBP is involves in apoptosis, cell cycle control and cell invasion. Up to now,there is rare studies on RYBP in carcinogesis and development and the results are inconsistent. Moreover,it is still not clear about the molecular mechanisms and clinical significance of RYBP as a novel tumor suppressor. Our preliminary results show that RYBP expression levels are lower in tumor tissues than those in normal tissues among 94% lung cancer samples, and the patients have longer survival time with higher RYBP expression level,which is the independent prognosis factor.In vitro study found that RYBP expression are decreased in lung cancer cell lines as well. This proposed effort is on the basis of the hypothesis of "RYBP plays a role on carcinogenesis and prognosis in lung cancer as a new tumor suppressor gene". The large scale clinical samples and in vitro and in vivo experiments will be joint usted to illustrated the role of RYBP in tumorgensis and progress in lung cancer, the molecular mechanisms of RYBP down-regulated and inducing cell apoptosis will be explored as well. In order to explain the identity of the tumor suppressor of RYBP, to provide advices for managment of the high-risk patients in clinic, and for the translational values as the potential biomarker or target for lung cancer diagnosis and therapy.

RYBP是新近识别的多梳蛋白(PcG)家族成员，除参与PcG抑制复合物1(PRC1)的组成，抑制转录功能外，与细胞凋亡及侵袭有关。截至目前RYBP在肿瘤领域的研究不多且存在矛盾，作为新的候选抑癌基因，其临床意义及分子机制都亟待阐明。我们前期通过检测50对肺癌手术患者的冻存癌和癌旁组织，发现94%的样本癌组织中RYBP的表达明显降低，且随RYBP的表达水平逐渐升高，患者的生存时间呈明显延长趋势，体外实验亦发现RYBP在肺癌细胞中表达下调。本项目基于"RYBP可能作为新的抑癌基因在肺癌发生发展中起作用"的假设，拟采用大规模临床肺癌样本的关联研究结合体内外实验方法，进一步验证RYBP在肺癌发病和预后中的作用，阐释其基因表达下调的机理并探索RYBP介导细胞凋亡的分子机制。从而为揭示RYBP的抑癌作用奠定基础，为筛选肺癌易感人群和高危亚型患者及临床判断预后提供参考，为寻找肺癌潜在的诊治靶标提供依据。

RYBP是新近识别的多梳蛋白(PcG)家族成员，除参与PcG抑制复合物1(PRC1)的组成，抑制转录功能外，与细胞凋亡及侵袭有关。本项目选取了441例肺癌患者及癌旁临床样本检测，我们的研究发现，与癌旁组织相比，非小细胞肺癌(NSCLC)患者手术组织样本中RYBP的mRNA和蛋白表达水平表达量均显著降低(P<0.001)。采用单变量Cox比例风险回归模型分析提示，RYBP蛋白表达是NSCLC患者总生存的独立预后因素，低表达的RYBP与差的预后相关。以上结果提示，RYBP在肺癌发生发展中可能起到抑癌作用。接下来，我们采用腺病毒载体的过表达体外细胞学实验方法，研究结果发现过表达RYBP降低了细胞的运动活力，抑制了克隆的形成并且诱导了凋亡，提示在NSCLC细胞中，RYBP可能是通过促进细胞凋亡的方式抑制了细胞增殖；体内移植瘤实验也证实，RYBP可显著抑制NSCLC细胞的恶性增殖特性并且提高NSCLC细胞对化疗药物的敏感性。以上结果都阐释了RYBP介导细胞凋亡的分子机制。此外，本研究也发现了RYBP的转录因子YY1在肺肿瘤组织中亦出现低表达，并且对肺癌细胞的增殖、迁移及侵袭存在影响。我们通过生物信息学手段预测发现RYBP是miR-195的靶基因，而miR-195在肺癌患者样本中的表达，以及对细胞增殖、迁移和侵袭都存在影响。而且，本研究也通过检测603例NSCLC患者和661例健康人的外周血的基因多态性(SNPs)情况，试图寻找肺癌发生发展中人群携带RYBP特异基因型对肺癌发病的影响。研究结果发现，rs4676875, rs12631820, rs2118593, rs4677152的特异基因位点与肺癌发生风险相关。总之，RYBP在肺癌的发生发展中可能起到重要的抑癌作用。