食管鳞癌染色体5p15.31扩增区段中候选预后标志物NSUN2的研究

Radical resection is a conventional treatment for esophageal squamous cell carcinoma (ESCC). Nowadays, it has been gradually replaced by individual treatment according to different clinical stages. Endoscopic mucosal resection is the first choice for ESCC patients diagnosed at stage T1N0 before operation. Therefore identification and application of biomarker of metastasis and prognosis is essential for selecting the best treatment strategy. Our previous study showed that genomic gain of 5p15.31 was frequently detected in ESCC patient samples and correlated with poor prognosis. Over-expression of NSUN2 located at 5p15.31 has been reported in various of cancers. Immunohistochemistry (IHC) and 5-year survival analysis of 96 ESCC patient samples at stage T3 showed that over-expression of NSUN2 was significantly correlated with poor prognosis (P<0.05), but not with lymph node metastasis. This project aims to identify if the gene NSUN2 is the target gene, of which the amplification can predict ESCC metastasis and prognosis. First of all, we will apply Fluorescent in situ Hybridization (FISH) and IHC analysis to investigate the incidence and concordance rate of NSUN2 amplification and over-expression. The correlation of NSUN2 amplification and over-expression with recurrence, metastasis and prognosis will also be analyzed. The gene function of NSUN2 will be studied in ESCC cell lines and nude mice. Eventually we will evaluate the effectiveness of NSUN2 as a prognosis marker for ESCC.

食管鳞癌以根治术为首选方案的传统治疗方式已逐步被依据不同分期实施的"个体化治疗"取代，目前术前确诊为T1N0期病例首选局部粘膜切除术。因此提示预测肿瘤转移、预后相关分子标志物的研究和应用，将成为决策最佳方案和指导治疗的重要依据。本课题组前期研究显示食管鳞癌5p15.31区段扩增与预后有关，位于该区段的基因NSUN2，其蛋白异常高表达与食管鳞癌不良预后相关(P<0.05)。本项研究旨在验证NSUN2是否为位于5p15.31区段的靶标，即其扩增能够作为判断转移、预后和治疗的依据。首先，我们将采用荧光原位杂交(FISH)和免疫组化分析不同分期食管鳞癌中NSUN2基因扩增和蛋白质异常高表达的发生率、符合率，及与复发、转移、预后的相关性。其后，我们将对NSUN2的基因功能在细胞水平和实验动物中进行研究，最终对NSUN2能否作为食管鳞癌有效的预后标志物进行评价。

食管鳞癌由于缺乏有效的早期诊断及治疗方式，导致其成为预后较差的恶性肿瘤。而随着食管鳞癌分子特征的揭示，使得提示预测肿瘤转移、预后的分子标志物的研究和应用，能够为肿瘤患者的有效监测及治疗提供重要依据。本课题组主要研究食管鳞癌基因组水平改变及其与临床病理因素及预后的相关性，从而发现预后标志物及治疗靶标。首先利用Oncoscan SNP基因芯片平台对38例早期食管鳞癌病例进行全基因组拷贝数检测，发现包括FGF4、MRAS、ALK和CHEK1基因等39个基因的拷贝数组合能够有效的预测早期食管鳞癌的转移。同时利用Ion Torrent二代测序平台，针对食管鳞癌中可能起驱动作用的44个基因的热点突变位点，对119例Ⅰ-Ⅱ食管鳞癌进行靶向测序，通过分析发现ZNF750、KEAP1和PIK3CA基因突变与预后相关，利用该三个基因组合可以有效预测食管鳞癌患者预后，并且可作为影响预后的独立影响因素。除此之外，进一步对PI3K/AKT/mTOR通路中PIK3CA基因突变、基因扩增及PI3K/AKT/mTOR信号通路蛋白质表达水平进行研究，发现了PIK3CA基因突变与蛋白高表达可以作为ESCC的预后标志物及治疗靶标。在本研究中发现的基因拷贝数改变，以及基因点突变和小片段的插入和缺失组合，提示可以作为预后标志物及治疗靶标，进而为食管鳞癌患者提供的个体化治疗提供了分子病理学依据。