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目的 探讨人结肠癌组织中是否存在环加氧酶 2 (COX 2 )选择性剪接异构体的表达及其可能意义。方法针对人COX 2DNA第 7、 8外显子序列 ,设计一对全新引物 ,并采用RT PCR技术 ,从结肠癌组织中分离COX 2mRNA ,然后对电泳条带进行克隆、测序和分析。结果 正常结肠组织和结肠癌组织均发现COX 2目的条带 ( 2 5 2bp) ,但结肠癌组织则出现了一条新的电泳带 ( 5 34bp) ,经克隆和测序证实 ,该条带除目的条带的COX 2DNA的第7、 8外显子序列外 ,还包含第 7、 8外显子间的内含子序列 ,即保留的内含子 ( 2 82bp)。根据阅读框推测 ,在保留的内含子第 4 8～ 5 0碱基出现终止密码。结论 首次发现结肠癌组织中存在COX 2基因的选择性剪接异构体 (Genbankaccessionnumber:BU4 936 0 2 ,AY15 12 980 ) ,其所编码蛋白可能较已报道的COX 2酶蛋白小 ,且蛋白质的C末端缺少阿斯匹林作用位点。
Objective To investigate the expression of cyclooxygenase 2 (COX 2) alternative splicing isoform in human colon cancer and its possible significance. Methods A pair of new primers were designed according to the exons 7 and 8 of human COX 2 DNA. COX 2 mRNA was isolated from colon cancer tissues by RT - PCR. The electrophoresis bands were cloned, sequenced and analyzed. RESULTS: In normal colon and colon cancer tissues, a 2 × 2 bp band of COX 2 was found. However, a new band (5 34 bp) of COX 2 was found in colon cancer tissues. Cloned and sequenced, In addition to the seventh and eighth exon sequences of COX 2 DNA, the intron sequence between exons 7 and 8, ie, the intron retained (282bp), was also included. According to the speculation in the reading frame, the stop codon appears at the 48th to 50th bases of the intron reserved. Conclusions For the first time, it is found that the alternative splicing isoform of COX 2 gene in colon cancer tissues (GenBank accession number: BU4 936 0 2, AY15 12 980) may be smaller than the reported COX 2 enzyme protein, and the protein C The lack of aspirin effect site.