TOX3-WDR5信号轴靶向ABCG2促进结肠癌细胞干性维持及化疗和靶向治疗耐药的功能、分子机制和临床意义

ABCG2异常表达与结肠癌细胞干性维持及耐药产生密切相关，阐明结肠癌特异的ABCG2转录调控机制意义重大。前期研究我们在结肠癌干性样细胞中鉴定出ABCG2启动子结合蛋白TOX3，发现其高表达于干性样细胞，调控ABCG2转录、癌细胞干性及化疗敏感性，并招募甲基转移酶复合体成员WDR5，但其调控ABCG2参与结肠癌进程的具体机制和临床意义，尚不明确。本课题拟在结肠癌细胞和动物模型中敲低或过表达TOX3，研究其对ABCG2表达，干性维持，化疗和靶向治疗敏感性的影响，并在此基础上过表达或敲低ABCG2，研究其对TOX3介导功能的逆转性；同时分析WDR5在TOX3调控ABCG2表达和肿瘤进程中的协同性；分析三者在小鼠结肠癌原位模型和病人癌组织中表达相关性，结合临床资料，评估三者与肿瘤耐药、复发及转移的联系。本课题旨在为确立TOX3/WDR5/ABCG2信号轴为结肠癌预后预测和治疗新靶标提供实验依据。

The aberrant activation of ABCG2 is closely associated with stemness maintenance, chemotherapy and targeting therapy resistance of colon cancer cells. It is of great significance to clarify the specific transcriptional regulatory mechanisms of ABCG2 in colon cancer. In the preliminary studies, we identified TOX3 as a new ABCG2 promoter-binding protein in colon cancer stemness-like cells. We also found it promoted ABCG2 transcription, was highly expressed in colon cancer stem-like cells, affected the stemness and chemotherapeutic sensitivity in colon cancer and recruited the key component of methyltransferase complex,WDR5. However, it is still unclear about the precise molecular mechanisms and clinical significance of TOX3 involved in tumorigenesis, development and therapeutic resistance in colon cancer via regulating ABCG2. This project plans to knock down or overexpress TOX3 in colon cancer cell lines or animal models, and further investigate its effects on ABCG2 transcription, stemness maintenance, sensitivity of chemotherapy and targeting drug therapy and tumor growth and metastasis. We also plan to further knock down or overexpress ABCG2 based on TOX3 overexpression or knockdown to analyze the reversibility of ABCG2 on the above biological function changes mediated by TOX3. Simultaneously, we will analyze the synergy of WDR5 and its mediated methylation of Histone in the regulation of ABCG2 expression and tumor progression mediated by TOX3. Moreover, we will also establish orthotopic colon cancer model in mice and collect tumor tissue samples from mice and patients to investigate the correlation between pairwise among TOX3, WDR5 and ABCG2 expression and their relationship with tumor therapeutic resistance, recurrence, metastasis and prognosis, thereby clarifying its clinical significance. This project aims to provide experimental evidence for developing TOX3/WDR5/ABCG2 axis as the new targets in colon cancer prognosis prediction and treatment.