膜联蛋白A1在口腔鳞癌EMT相关转移通路中的作用机制

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancer. The 5-year survival rate of OSCC patients is 50-60%, with the main reason of deaths due to metastasis concomitant with organ failure. Thus, a better understanding of cellular and molecular mechanisms leading to metastatic dissemination of carcinoma cells is of utmost importance. A central process in metastasis is epithelial-to-mesenchymal transition (EMT), i.e. the conversion of sessile, polarized epithelial cells to motile fibroblastoid cells expressing mesenchymal markers. Annexin A1 is an intracellular protein that can bind calcium and phospholipids, which has been suggested to have an important role in the inflammation response, cell proliferation, cell signaling, phagocytosis, and carcinogenesis. Sabine Maschler et al reported that Annexin A1 attenuates EMT and metastatic potential in breast cancer, however, Marjo de Graauw revealed that Annexin A1 regulates TGF-β signaling and promotes metastasis formation of basal-like breast cancer cells. So, there are still some controversies about the connection of Annexin A1 with EMT/metastasis, especially, there is no report which revealed a clear, causal connection of Annexin A1 with EMT/metastasis in oral squamous cell carcinoma until now. Our previous studies have established an in vitro cellular carcinogenesis model from normal oral mucosal epithelia to cancerous squamous cells, and comparative proteomic technique has been used to screen the differential proteomic profiles between the cells at different stages of carcinogenesis. Annexin A1 is one of the proteins, which is expressed in low level accompanying with the carcinogenesis. Significant correlation is also found between the Annexin A1 expression level and pathological differentiation grade of cancerous tissues, a poorer differentiation grade indicating a lower level of Annexin A1 expression. When the Annexin A1 expression is overexpressed in the cancerous cells with transferring with the Annexin A1 gene coding sequence, lower metastasis rate is found with increased expression of E-candherin and decreased expression of N-cadherin and vimentin，additionally the differentiation grade of cancerous tissues becomes better from moderately differentiation grade to well differentiation grade. Based on our previous results, the aim of this project is to explore the potential inhibition role of Annexin A1 in the EMT/metastasis pathway with the molecular intervention, in vitro and in vivo methods in oral squamous cell carcinoma, evaluate the clinical predictive value in oral squamous cell carcinoma metastasis.

本课题组建立了口腔黏膜上皮细胞体外癌变模型，之后应用比较蛋白质组学的方法发现Annexin A1随细胞癌变而表达下降，并且其表达高低与口腔鳞癌的分化程度相关，病理分化程度越差，表达越低；过表达口腔鳞癌细胞系Annexin A1基因后，细胞迁移速率明显减慢，EMT相关标志物E-cadherin表达升高，N-cadherin及Vimentin表达降低；由此，我们推测Annexin A1在口腔鳞癌的EMT相关转移中具有重要的作用。检索大量文献发现，Annexin A1在恶性肿瘤EMT相关转移中的作用存在争议，尤其在口腔鳞癌转移中的作用还未见报道，具有进一步研究的价值。本课题采用分子干预和体内外实验相结合的方案，以EMT信号通路为切入点，探讨Annexin A1在抑制口腔鳞癌EMT相关通路转移中的作用机制，评价Annexin A1在口腔鳞癌转移中的预测价值，为治疗口腔鳞癌转移提供可能的靶点。

本课题通过检测口腔鳞癌细胞系及口腔鳞癌病人临床标本中Annexin A1表达情况，发现Annexin A1与口腔鳞癌患者预后显著相关，并通过体内、外实验，发现低表达Annexin A1促进口腔鳞癌细胞生长、侵袭、以及体内肿瘤的生长，口腔鳞癌细胞出现EMT转化；高表达Annexin A1抑制口腔鳞癌细胞的生长、侵袭及体内肿瘤的生长速率，口腔鳞癌细胞出现逆EMT转化，阐明了Annexin A1在口腔鳞癌EMT相关转移通路中的作用机制，为Annexin A1作为口腔鳞癌临床治疗及预后预测的生物标记提供了理论基础，为口腔鳞癌治疗提供了新的靶点；另外，本课题应用 Agilent表达谱芯片方法，进一步探索Annexin A1新的生物学功能，为进一步研究奠定了基础，指明了方向。