目的：通过直肠癌循环肿瘤细胞（circulating tumor cell，CTC）与原发肿瘤组织基因表达谱的差异分析，筛选直肠癌CTC的特异性基因。方法：选取2015年9月至2015年12月福建省肿瘤医院收治的直肠癌患者4例，取肿瘤组织和相应的癌旁组织并采集外周血20 ml。应用流式细胞术检测血液CTC，抽提癌组织和CTC的总RNA，采用人全转录组表达谱芯片检测CTC及相应肿瘤组织mRNA表达谱，经聚类分析筛选CTC特异性基因，并采用生物分子注释系统MAS软件对其进行基因功能及其相关的信号通路分析。结果：4例直肠癌患者检测到CTC数目分别是67、78、53和120个。筛选出肿瘤与癌旁组织差异基因共7 755个、CTC与白细胞差异基因共 567个，肿瘤组织及CTC差异基因交集后共同上调或下调的特异性基因共36个，其中上调 16个、下调20个（P<0.05或P<0.01）。CTC 特异性基因与肿瘤转移和干细胞功能有关，涉及与细胞转移、干细胞功能和免疫功能相关的22条信号通路。结论：CTC与原发肿瘤基因相比，具有独特的表达谱，是肿瘤复发和转移的重要基础。

Objective:To screen specific gene of circulating tumor cells (CTCs) of rectal cancer according to the differentially expressed profile of rectal cancer CTCs and primary tumor tissues. Methods: Four cases of rectal cancer patients treated in Fujian Cancer Hospital from September 2015 to December 2016 were selected to collect tumor tissues and corresponding para-cancerous tissues, in addition, 20 ml of peripheral blood was collected. Moflo XDP cytometry was adopted to identify and sort CTCs; after purification and amplification of sample total RNA, human whole transcriptome microarray chip was used to detect the expression profiles of CTCs and tumor tissue mRNA of corresponding patients, and further to screen the CTCs specific genes. In addition, MAC3.0 bio-informatics software was used for the gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Results: After sorting and testing, CTCs number sorted from each patient were 67，78，53 and 120.There were 7 755 differentially expressed gene between tumor tissues and normal para-cancerous tissues; there were 567 differentially expressed gene between CTCs and white cells; Combining the two dataset, there were 36 differentially co-expressed gene, including 16 up-regulated genes and 20 down-regulated genes (P<0.05 or P<0.01).GO function of CTCs specific genes were correlated with tumor metastasis and stem cell function, and those specific genes also participated in 22 signaling pathways related to cell migration, stem cell function and immune function. Conclusion: Compared with primary tumor gene, CTCs has a unique mRNA profile, which is the foundation of tumor recurrence and metastasis.

福建省医学创新基金资助项目（No.2015-CXB-4）；福建省自然科学基金资助项目（No.2016J01436）；国家临床重点专科建设基金资助项目(No.2015-544)