FAT4基因突变通过干扰细胞极性及接触抑制促进结直肠癌发生、侵袭和转移的分子机制

Gene mutation is the initial factors of cancer, mutant protein has become the ideal target of targeted therapy and immunotherapy for malignant tumours. It is important to screen and identify "driver mutation” of tumor for the implementation of precise treatment for patients with cancer. FAT4 gene is a metastasis-associated candidate “driver mutant” of colorectal cancer from our preliminary study through high-throughput sequencing; however, the role and molecular mechanism of FAT4 mutations are unclear in the progression of colorectal cancer, and whether it can be regarded as "driver mutations" is also debatable. In view of our preliminary study and analysis, we propose that FAT4 mutation disrupts planar cell polarity and contact inhibition, and promotes initiation, invasion, metastasis of colorectal cancer by regulating the activity of planar cell polarity and Hippo signaling pathway. This subject intends to engineer FAT4 mutation model in colorectal cancer cell lines and in mouse using CRISPR/Cas9 gene editing technology, then dynamically observes the change of cell plane polar through morphology experiment; explore the interaction between FAT4 mutation protein and DCHS1/2 along with other protein, and regulation mechanism on PCP and Hippo pathway using variety molecular biology experiment. Finally, this subject aim to elucidate the role and molecular mechanism of FAT4 mutation, and definite FAT4 mutation as "driver mutation” in the initiation and progression of colorectal cancer.

基因突变是肿瘤发生的始动因素，所产生的突变蛋白已成为恶性肿瘤靶向治疗和免疫治疗的理想靶点，筛选、鉴定驱动突变对肿瘤患者的精准治疗具有重要的科学意义。FAT4基因是我们前期筛选出的一个CRC转移相关驱动突变候选分子；然而，FAT4突变在CRC演进过程中的作用及分子机制尚不清楚，其能否作为驱动突变也尚无定论。鉴于前期的分析研究，我们提出“FAT4突变通过调节PCP和Hippo等信号通路的活性，干扰细胞极性和接触抑制，促进CRC发生、侵袭和转移”这一科学假设。本课题拟以CRISPR/Cas9定点突变和突变修复细胞株及肠道特异FAT4基因突变小鼠为研究对象，检测FAT4突变对细胞极性、增殖、侵袭和转移能力的影响，采用CO-IP等技术探讨FAT4突变蛋白与DCHS1/2蛋白的结合情况及对PCP和Hippo等通路的调控；初步阐明FAT4突变在CRC发生和演进中的作用和分子机制，明确其“驱动突变”角色。

基因突变是肿瘤发生的始动因素，所产生的突变蛋白已成为恶性肿瘤靶向治疗和免疫治疗的理想靶点，筛选、鉴定驱动突变对肿瘤患者的精准治疗具有重要的科学意义。FAT4基因是我们前期筛选出的一个CRC转移相关驱动突变候选分子；然而，FAT4突变在CRC演进过程中的作用及分子机制尚不清楚，其能否作为驱动突变也尚无定论。鉴于前期的分析研究，我们提出“FAT4突变通过调节PCP和Hippo等信号通路的活性，破坏细胞平面极性和接触抑制，促进CRC发生、侵袭和转移”这一科学假设。本课题以CRISPR/Cas9定点突变和突变修复细胞株及肠道特异FAT4基因突变小鼠为研究对象，检测了FAT4突变对细胞极性、增殖及侵袭转移的影响，采用CO-IP等探讨了FAT4突变蛋白与DCHS1/2互作蛋白的结合情况及对PCP和Hippo等通路的调控。本课题初步阐明抑癌基因FAT4突变，改变其蛋白胞外段的结构，影响与DCHS1/2蛋白的相互结合，引起胚胎发育过程中的相关信号通路（包括细胞平面极性PCP和Hippo通路）活性异常，进而导致肠粘膜上皮细胞平面极性紊乱及细胞接触抑制废除，促进CRC的发生、侵袭和转移。

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