从大肠癌组织cDNA表达文库筛选肿瘤抗原基因

Search colorectal cancer antigen genes by screening the colorectal tissue cDNA phage expression libraries with SEREX

目的利用肿瘤患者血清筛选大肠癌cDNA噬菌体表达文库,寻找肿瘤特异性抗原基因。方法采用SMART技术构建中国人大肠癌cDNA噬菌体表达文库。用SEREX方法筛选中国人大肠癌组织cDNA噬菌体表达文库。对获得的阳性克隆片段进行测序、鉴定和BLAST同源性比较,并对其生物信息进行分析。结果成功地构建了大肠癌cDNA噬菌体表达文库,原始文库含2.39×106个重组子,重组率达到97.5%,文库扩增后滴度达到4.1×1010pfu/ml。插入外源性cDNA片段的大小为0.5～4.0kb。SEREX筛选共获得16个阳性克隆,代表12个不同抗原基因,其中10个基因片段为已知抗原基因,如IFITM1、CD24、Survivin、KLK6等,2个为未知EST片段。根据序列分析,筛选出的抗原基因有结构基因、调节基因、代谢相关基因等。结论利用SEREX方法筛选出大肠肿瘤相关抗原基因并获得2个肿瘤抗原候选基因。

Objective Identification of colorectal cancer specific antigens from cDNA phage expression library by recombinant expression cloning (SEREX). Methods The cDNA phage expression library derived from colorectal cancer tissue was constructed using the SMART (Switching Mechanism at 5'end of RNA Transcript) techniques. The cDNA phage expression library was screened with SEREX (serological identification of antigen by recombinant cDNA expression libraries), the positive clones encoding antigenic genes were obtained after immunoscreening, and the nucleotide sequences of cDNA inserts were determined and analyzed with BLST software in GenBank, and the antigenic gene function was analyzed by bioinformatics. Results The cDNA phage expression library derived from colorectal cancer tissues was successfully constructed. The primary library consisted of 2.39×10 6 recombinants, and the recombinant rate was more than 97.5%. The titer of the amplified cDNA phage expression library was 4.1×10 10pfu/ml, and the size of inserted cDNA varied from 0.5 to 4.0kb. Sixteen positive clones encoding antigenic genes were obtained after immunoscreening, and results showed that 16 reactive clones were derived from 12 different genes. Ten of 12 genes were highly homologous to the genes known in GenBank, such as IFITM1, CD24, Survivin, KLK6, et al. Two expressed sequence tags (ESTs) were not found in GenBank. The antigenic genes included structural gene, regulation gene and metabolizing gene. Conclusion The tumor-associated antigen genes and the two ESTs were obtained by SEREX were worthy of further study on their structures and functions.