AJUBA基因在食管癌中的作用及机制研究

AJUBA is a novel significantly mutated gene in esophageal squamous cell carcinoma (ESCC) which is identified via high-throughput omics sequencing from a large sample of ESCC cases. Bioinformatics analysis predictes inactivation of this gene may be a driver event in the development of ESCC. The encoded protein by AJUBA gene is one of the members of the LIM protein family, as a scaffolding protein involved in various biological processes. Our previous study showed that AJUBA suppressed cell growth, cell migration and invasion, and there is mislocalization of AJUBA from nucleus to cytoplasm in carcinoma tissue compared with paired normal tissues. However, the melocular mechanism of mislocalization and tumor suppressor of AJUBA in esophageal cancer remains unrevealing. This proposal aims to investigate the correlation between mislocalization and mutation of AJUBA by target capture sequencing and elucidate the melocular mechanism of AJUBA mislocalization through co-immunoprecipitation. Meanwhile, we aim to clearify the specific molecular mechanism of AJUBA tumor suppressor function. The results will facilitate early diagnosis, prevention, and treatment of esophageal cancer.

AJUBA基因是申请者前期利用高通量组学测序技术，在全基因组水平从大样本食管鳞癌中鉴定出的新显著突变基因之一，其失活突变可能是食管鳞癌中关键性驱动事件。该基因编码蛋白是LIM 蛋白家族成员之一，作为支架蛋白参与细胞内多种生物学过程。前期研究表明该基因可以显著抑制癌细胞的增殖、侵袭迁移，且在食管鳞癌中存在从胞核到胞浆的异位表达，但对其在食管癌中异位表达及发挥肿瘤抑制作用的具体机制尚不清楚。本项目拟采用目标区域捕获测序、免疫组化、免疫荧光技术探讨AJUBA异位表达与突变类型的相关性；利用免疫共沉淀明确异位表达的分子机制；采用转录组测序、RNA干扰及裸鼠移植瘤模型等方法阐明其在食管鳞癌中抑制癌细胞增殖、侵袭迁移的分子机制，从而为揭示食管癌新的癌变机理，设计新的抗肿瘤治疗方案提供理论基础。

食管鳞癌（ESCC）是我国常见的具有高发病率和高致死率的恶性肿瘤，由于缺乏早期诊断方法，5年生存率仍为10%～25%。因此，为了改善食管鳞癌患者的现状，鉴定食管鳞癌的关键驱动基因非常迫切。我们课题组前期对ESCC肿瘤及邻近正常组织进行全基因组测序，发现AJUBA是显著突变基因。AJUBA参与细胞粘附、细胞有丝分裂、分化增殖、细胞迁移和侵袭。在本研究中，我们发现AJUBA在ESCC肿瘤组织中的表达显著降低。AJUBA基因敲除可加速细胞增殖和克隆形成，促进细胞迁移和侵袭能力增强，而过表达AJUBA基因则表现出相反的趋势。同时，AJUBA基因敲除导致细胞周期调控因子、凋亡和上皮间质转换（EMT）标记物发生明显变化。此外，我们还发现AJUBA的抑癌作用依赖于Hippo信号通路。总之，我们的研究明确了AJUBA在ESCC中的作用及机制。本研究将有助于深入了解食管鳞癌发生发展的机制，为食管鳞癌的治疗提供新的靶点。