新相关基因Bmi-1在大肠癌肝转移中的作用及机制研究

Liver is the most common metastatic site for colorectal cancer (CRC).Though studies show that the epithelial-mesenchymal transition (EMT) is one of the main mechanisms underlying development of CRC metastasis, the exact molecular mechanisms remain unclear. Clinically, we found that the polycomb-group protein Bmi-1 was higher expressed in a cohort of human hepatic metastasis than in their primary colorectal tumors, suggesting that it might play an important role in mediating CRC liver metastasis. Our preliminary results also showed that Bmi-1 promoted mitigation and invasion abilities in CRC cells. In this study,we aim to investigate the role of Bmi-1 in regulating metastasis ability in CRC cells and stemness in cancer stem cells under hypoxia or inflammatory cytokine IL-1β treatment. Then the genes and proteins that are functionally critical under Bmi-1 regulation will be identified using EMT PCR array, Western-blot assay, spheroids formation assay, immunofluorescence analysis ect. Furthermore, 3D Organotypic "raft" culture and nude mice models of experimental CRC liver metastasis will be used to confirm what we find above. In addition,we will collect samples from CRC patients with/without liver metastasis for primary culture of tumor cells and tissue immunohistochemistry to confirm the molecular mechanisms. These findings will shed a new light on understanding molecular mechanisms underlying colorectal cancer liver metastasis and provide a potent molecular target for treatment.

肝脏是大肠癌最常见的转移器官，目前认为上皮间质转化（EMT）与大肠癌转移有关，但是分子作用机制仍不清楚。我们前期研究发现表观遗传调控因子Bmi-1在大肠癌患者肝转移灶组织中的表达较原发灶组织显著增高，并参与调控大肠癌细胞迁移与侵润，是大肠癌肝转移的新促进因子。本研究拟在前期工作的基础上，观察在肿瘤微环境（低氧、促炎症因子IL-1β刺激）作用下Bmi-1对大肠癌细胞侵袭转移能力及肿瘤细胞干性的影响，并运用EMT PCR Array、western-blot、免疫荧光、特异信号通路阻断等方法研究Bmi-1调控的关键信号通路分子变化，进而通过建立3D培养大肠癌组织模型和大肠癌肝转移裸鼠模型，明确 Bmi-1对大肠癌肝转移的促进作用并探讨其具体作用机制，最后用临床组织标本验证关键分子表达变化，从而为探索大肠癌肝转移的发病机制和找到新的治疗靶点奠定基础。

肝脏是大肠癌最常见的转移器官，目前认为上皮间质转化（EMT）与大肠癌转移有关，但是分子作用机制仍不清楚。我们研究发现表观遗传调控因子Bmi-1在大肠癌患者肝转移灶组织中的表达较原发灶组织显著增高，并参与调控EMT相关分子表达促进大肠癌细胞迁移与侵润，其作用与调节大肠癌细胞AKT/GSK-3β/Snail通路有关，大肠癌肝转移裸鼠体内实验证实是Bmi-1是大肠癌肝转移的关键促进因子。.短链脂肪酸丁酸钠(NaB)是结肠细菌厌氧发酵膳食纤维的产物，已被证明在大肠癌中有抗肿瘤的效果，然而其作用机制并不清楚。我们进行体内外实验研究发现丁酸钠能有效抑制大肠癌细胞增殖，并能通过调控EMT相关蛋白表达抑制细胞迁移与侵袭。丁酸钠抑制大肠癌细胞迁移的作用与其上调miR-200c的表达并抑制其下游靶基因Bmi-1的表达有关。这些研究为探索大肠癌肝转移的发病机制和找到新的治疗靶点奠定基础。.放射性口腔黏膜炎是放疗过程中常见副作用之一，严重影响患者治疗和生活质量，目前仍没有理想的防治手段。我们成功建立放射性口腔黏膜炎小鼠模型，研究发现Bmi-1上游调控miR-200c调节放射性口腔黏膜炎的病理过程，抑制miR-200c表达能效降低电离辐射引起的细胞衰老死亡、活性氧产生、炎症因子产生，促进DNA修复和角化细胞迁移，其作用与调节TGF-β/Smad/NF-κB通路及EMT相关蛋白表达有关。本研究为开发防治放射性口腔黏膜炎的新型药物提供全新的靶点。