MGP参与调控锯齿状路径来源结肠癌进展的机制研究

Sessile Serrated Adenoma (SSA) is one of the main precancerous lesions of right-sided colon cancer, which accounts for 20-30% of colon cancer cases. Its cancerous mechanism, which is quite different from "adenoma-carcinoma" sequence, called "Serrated Pathway", has not been well studied. In our previous studies, Matrix Gla Protein (MGP) was found overexpressed in SSA and colon cancer, and higher MGP level in colon cancer patients indicated a worse prognosis. Interference of MGP resulted in inhibition of colon cancer cell growth and motility, as well as an increase in apoptosis. Additionally, JAK-STAT pathway was identified as a potential target of MGP in colon cancer in co-expression analysis. In this project, firstly the effect of MGP in cell phenotype will be revealed in normal colon epithelial cells, colon cancer cells, and colonoids models derived from SSA patients' colon mucosa. Secondly, the protein-protein interaction will be investigated and the direct interacting target of MGP will be identified. Furthermore, the mechanism of STAT activation by MGP will be explained by further investigation such as rescue assays. Together, this study will shed light on accurate subtyping of colorectal cancer and their precancerous lesions, exploring of SSA-related cancerous mechanism, and detection of novel therapeutic targets for colorectal cancer.

广基锯齿状腺瘤（SSA）是右半结肠癌的主要癌前病变，其发病机制是不同于传统腺瘤的锯齿状路径，该路径占结肠癌总发病率的20-30%，但其调控机制尚不清楚。我们前期研究发现基质Gla蛋白（MGP）在结肠癌与SSA中有过表达现象，而高表达MGP的患者预后较差；并且干扰MGP能抑制结肠癌细胞的生长与运动能力，促进凋亡；后续共表达分析发现JAK-STAT通路可能是其潜在靶点。本研究拟在这些工作的基础上，系统的探索MGP在结肠肿瘤及其癌前病变中的生物学效应与作用机制，具体包括：①在正常结肠上皮细胞、结肠癌细胞及SSA来源的结肠类器官（Colonoids）中检测MGP对表型的影响；②蛋白相互作用研究寻找MGP影响JAK-STAT通路的直接作用蛋白，明确靶结构域等具体机制；③挽救实验进一步明确MGP及其靶分子的作用。本研究将对锯齿状路径来源结肠癌的发病机制及相关治疗靶点提供新的实验证据与研究思路。

广基锯齿状腺瘤是右半结肠癌的主要癌前病变，其发病机制不同于传统腺瘤路径。我们前期研究发现基质Gla蛋白（MGP）在结肠癌与广基锯齿状腺瘤中有过表达现象，进一步研究中我们发现MGP在胃肠道肿瘤中存在普遍性的过表达现象，且MGP高表达在胃癌及结肠癌两类不同的消化道肿瘤患者中均与预后不良显著相关，提示其作为相关肿瘤标记物的潜在可能性。通过系列细胞表型研究我们明确了MGP在胃肠道肿瘤中的促癌生物学机能，包括促进增殖、抑制凋亡、促进细胞运动等；在分子机制层面，我们探索了原假说中MGP蛋白通过激活JAK-STAT通路的具体机制，通过荧光共定位、免疫共沉淀的实验明确了MGP通过与STAT5相互作用，促进其与靶基因CCND2、SOCS2、BCL-2启动子的结合，从而促进肿瘤进展的分子生物学过程。此外，我们还进一步探索了MGP蛋白通过自身钙离子结合能力对肿瘤进展的影响，明确了MGP蛋白通过结合胞内Ca2+，从而激活CREB、NFkB、NFAT等Ca2+下游相关通路，促进肿瘤增殖的分子机制，在原计划的基础上进一步丰富了MGP的胞内促癌功能及其相关分子机制。综上所述，本项目的科学发现提示MGP可能作为一种潜在的肿瘤早期标记物及治疗靶点，而我们对MGP胞内定位、功能的揭示，丰富了我们对这类蛋白功能的认知，也对传统分泌蛋白提供了一种全新的审视角度，对未来相关领域的研究也具有一定借鉴意义。