ECRG2基因在食管癌等常见恶性肿瘤中的突变、功能分析及临床意义评价

ECRG2 is a novel esophageal cancer related gene which was cloned from primary squamous cell carcinomas tissues from high incidence families in Lin-Xian County. Reverse transcription-PCR and Northern blot results showed that the ECRG2 gene was expressed in normal esophagus, liver, colon, and lung tissues but was downregulated in the adjacent and cancerous tissues, especially with low frequency in esophageal cancer. ECRG2 is involved in the regulation of migration/invasion through uPA/uPAR/β1 integrins/Src/MAP kinase pathway. Moreover, ECRG2 is important for ensuring centrosome duplication, spindle assembly checkpoint, and accurate chromosome segregation in a p53/BubR1-dependent manner. It has been identified that a short tandem repeat (STR) polymorphism in the non-coding region of the exon 4 of the ECRG2 gene. Furthermore, bioinformatics predicts more single-nucleotide polymorphism (SNP) within ECRG2 genomic sequence. However, the ECRG2 cancer susceptibility mutations in esophageal cancer and other tumors and their contributing to early diagnosis, prevention, and treatment are unrevealing. This proposal aims to identify the cancer susceptibility mutations within ECRG2 genomic sequence through the target region sequencing, elucidate the molecular mechanism through which the identified variants play roles during the carcinogenesis of esophageal cancer, and facilitate early diagnosis, prevention, and treatment of esophageal cancer.

ECRG2基因是从我国食管鳞癌高癌家系克隆的新候选抑癌基因，属于丝氨酸蛋白酶抑制剂家族，通过uPA/uPAR/β1 integrin/Src/MAPK信号通路抑制肿瘤细胞侵袭迁移；通过p53、BubR1参与中心体复制及纺锤体检测点功能，与染色体稳定性密切相关。已经发现ECRG2基因第四外显子非编码区存在TCA短串联重复序列多态性，生物信息学预测ECRG2基因组序列中存在多个SNP位点。但是，这些SNP是否在肿瘤组织中确实存在及其功能、临床意义评价尚不清楚。本项目拟采用目标区域测序法分析ECRG2基因在食管癌及其他常见恶性肿瘤中的突变情况，并利用突变体候选基因研究法、转录组测序法等探讨ECRG2基因突变体的功能及其分子机制，结合随访资料筛查ECRG2基因相关的食管癌预警分子标志物，为研究我国食管鳞癌发生发展的分子机制、筛选早期诊断标记物及候选治疗靶点提供理论依据。

ECRG2 基因是从我国食管鳞癌高癌家系克隆的新候选抑癌基因，属于丝氨酸蛋白酶抑制剂家族，通过uPA/uPAR/β1 integrin/Src/MAPK信号通路抑制肿瘤细胞侵袭迁移。本项目采用目标区域测序法鉴定了ECRG2基因在食管癌中T88C遗传变异，并利用突变体候选基因研究法、转录组测序法等探讨ECRG2-T88C突变体的功能及其分子机制，发现了食管癌中特异的突变体T88C，发现了ECRG2-T88C在食管癌中发挥类似癌基因样作用，其高表达促进食管癌细胞增殖、侵袭迁移。进一步分子机制研究发现，ECRG2-T88C突变体与uPA/uPAR复合物的结合力降低，丧失了ECRG2对uPA/uPAR/β1 integrins (FPRL1)/Src/ MAPK信号转导通路的抑制作用，从而促进了食管鳞癌细胞的侵袭迁移。另外，ECRG2-T88C突变体与uPA/uPAR复合物的结合力降低干扰了uPA对MMPs活性的抑制，从而促进了ECM的降解，加速了食管鳞癌细胞的侵袭迁移。另外，本项目还采用转录组测序，综合分析了ECRG2-T88C影响的细胞内信号通路，并在细胞水平及动物水平验证了ECRG2-T88C通过影响MAPK、Wnt、Notch信号通路以及ECM而在食管癌发生发展中发挥作用。本项目研究成果为研究我国食管鳞癌发生发展的分子机制、筛选早期诊断标记物及候选治疗靶点提供理论依据。