肌动蛋白结合蛋白的核定位及其新的生物学功能是近年来肿瘤研究的新兴科学问题。在前一项目资助下，本课题组发现肌动蛋白结合蛋白Transgelin在胞浆中可诱导肌动蛋白聚合从而促进结肠癌细胞的迁移和侵袭，并在肿瘤细胞中存在核定位现象，可影响一系列与细胞形态、迁移侵袭密切相关的基因表达。然而Transgelin核定位的生物学功能及发生机制尚未明确。我们推测Transgelin在结肠癌细胞中可能通过核、浆双重机制促进肿瘤转移：在胞浆中重塑细胞骨架，在胞核中调控转移相关基因的表达，从而促进肿瘤细胞转移表型的形成。本课题拟在前期研究基础上，分析Transgelin核定位对结肠癌细胞转移表型的影响，进而探讨其核定位的生物学功能及分子机制。本研究对于深入了解Transgelin在结肠癌转移中的作用途径，建立针对Transgelin的精准干预措施具有重要价值。

The nuclear localization of actin-binding protein and its new biological functions attract growing attention in the field of cancer research. Metastatic dissemination, rather than the primary tumor, is responsible for 90% of colorectal cancer (CRC) deaths. Transgelin was the top-ranked biomarker of metastatic potential identified in the comparison of node-positive versus node-negative CRC in our previous quantitative proteomics study. Experimental manipulation of transgelin levels in the CRC cells led to changes in the metastatic potential in vitro and in vivo. Expression microarray analysis revealed that approximately 250 genes were differentially expressed with up-regulation of transgelin. Localization analyses indicated that it localizes both in the cytoplasm and the nucleus of the tumor cells. These suggest that transgelin may play dual roles in the progression of CRC: it may influence metastasis through direct interaction with cytoplasmic actin, and also regulate the transcription of downstream targets in the nucleus, which work together to form the metastatic phenotype. .This study aims to determine whether the nuclear localization of transgelin affects the clinical characteristics of the tumor and the survival. We will identify the nuclear components that are associated with transgelin in order to clarify its biological function. This work will provide insight into the mechanisms that transgelin participates in CRC metastasis, which may also contribute to the precise intervention of the metastatic disease.

在前期探寻结直肠癌转移标志物的过程中，我们发现肌动蛋白结合蛋白Transgelin在结肠癌细胞的侵袭转移中具有重要作用，在肿瘤细胞中存在核定位，并影响下游一系列基因的表达。本研究主要目标是识别结肠癌细胞中与Transgelin相互作用的DNA及蛋白质成分，揭示Transgelin在肿瘤细胞中核定位的生物学功能。本研究通过染色质免疫共沉淀，未发现结肠癌细胞中Transgelin与DNA存在直接相互作用。进一步通过蛋白质免疫共沉淀及蛋白质全谱分析发现，结肠癌细胞Rko中有297个蛋白质与Transgelin存在特异性相互作用，其中包括多种细胞骨架蛋白、代谢相关酶类、运输蛋白、转录因子、信号蛋白、热休克蛋白和参与氧化还原反应的酶。进而通过蛋白质免疫共沉淀及免疫荧光分析验证了Rko细胞中Transgelin与转录因子HMGA2之间存在的蛋白质-蛋白质相互作用，以及两者在细胞核中存在共定位。通过Gene Ontology分析显示，与Transgelin结合的蛋白质主要参与转录调节、翻译调节、细胞转运、酶活性调节、催化反应等细胞生物学过程。