结直肠癌细胞的快速增殖是造成患者死亡的重要原因之一，但其机制尚不甚明晰。申请者在前期工作中发现MLF1IP能促进结直肠癌细胞增殖；干扰MLF1IP可导致结直肠癌细胞G1/S期阻滞，并上调BRCA1和p27蛋白的表达，而下调p-AKT蛋白的表达；MLF1IP与BRCA1的转录调控密切相关。故推测：MLF1IP通过调控BRCA1/AKT/p27信号轴促进结直肠癌细胞增殖。本项目拟用多种分子生物学手段观察MLF1IP对BRCA1/AKT/p27信号轴的调控作用，并在结直肠癌临床样本及动物模型中检测MLF1IP与BRCA1的表达并探讨其与结直肠癌细胞增殖的相关性。最后，通过RT-PCR、荧光素酶报告实验、ChIP和结合位点突变载体等方法解析MLF1IP与BRCA1启动子的结合效应与作用位点，从而阐明MLF1IP调控BRCA1转录的具体机制。本课题为临床防治结直肠癌提供新的靶点和策略。

The rapid proliferation of colorectal cancer cells is a leading cause of death in colorectal cancer patients, however, the mechanism remains unclear. In the preliminary work, we found that MLF1IP could promote the proliferation of colorectal cancer cells. Furthermore, we found that knockdown of MLF1IP caused G1/S phase arrest in colorectal cancer cells. In MLF1IP-shRNA expressing cells, the expression of BRCA1 and p27 proteins were upregulated, and the expression of p-AKT protein was downregulated. Moreover, MLF1IP was closely associated with transcriptional regulation of BRCA1 gene. Therefore, it is speculated that MLF1IP affects colorectal cancer proliferation through mediating BRCA1/AKT/p27 signaling pathway. On this basis, we intend to observe the effect of MLF1IP on the BRCA1/AKT/p27 signaling pathway by molecular biology methods, and analyze the expression of the MLF1IP and BRCA1 in colorectal cancer clinical samples and animal models and their correlation with the proliferation of colorectal cancer. Finally, binding site of MLF1IP on BRCA1 promoter is verified using RT-PCR, luciferase reporting experiment, ChIP and binding site mutation vectors to illuminate the the specific regulatory mechanism of MLF1IP on BRCA1 gene transcription. This project will provide novel targets and strategies for treatment of colorectal cancer patients.