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目的 研究由减式杂交方法获得的人大肠癌相关基因SNC73的结构和功能。方法 对SNC73的cDNA进行了核苷酸序列测定 ,分析得到全长序列 ,并对其编码的蛋白进行了分析及预测 ;采用Insitu Max荧光原位杂交方法结合荧光R带技术对SNC73在人染色体上的定位作了研究 ;利用Northern杂交、逆转录聚合酶链反应 (RT PCR)方法检测了SNC73在多种肿瘤细胞系中的表达 ,及在大肠癌组织与正常粘膜中的表达情况 ;应用原位杂交 /原位PCR技术检测SNC73mRNA在肠上皮中的表达情况。结果 对SNC73序列及开放阅读框 (ORF)进行分析 ,发现其与免疫球蛋白IgA高度同源 ,为一免疫球蛋白样基因。该基因定位于人染色体 14q32。SNC73在大肠癌组织与正常肠粘膜的表达有差异 (P <0 .0 5 )。SNC73在肠上皮表达阳性。结论 SNC73在大肠癌中低表达 ,可能为一新的肿瘤标记物 ,并提示上皮细胞、非淋巴细胞存在IgA类的蛋白。
Objective To study the structure and function of human colon cancer-related gene SNC73 obtained by subtractive hybridization. Methods The nucleotide sequence of SNC73 cDNA was determined, the full-length sequence was analyzed, and the encoded protein was analyzed and predicted. The Insitu Max fluorescence in-situ hybridization method was used in combination with the fluorescent R-band technique to detect SNC73 on the human chromosome. The location was studied; Northern blotting, reverse transcription polymerase chain reaction (RT PCR) method was used to detect the expression of SNC73 in various tumor cell lines, and its expression in colorectal cancer tissues and normal mucosa; Hybridization/in situ PCR was used to detect the expression of SNC73 mRNA in intestinal epithelium. Results The SNC73 sequence and open reading frame (ORF) were analyzed and found to be highly homologous to immunoglobulin IgA, which is an immunoglobulin-like gene. This gene is located on human chromosome 14q32. The expression of SNC73 in colorectal cancer tissue and normal intestinal mucosa was different (P < 0.05). SNC73 is positive in intestinal epithelium. Conclusion SNC73 is lowly expressed in colorectal cancer and may be a new tumor marker. It suggests that IgA proteins are present in epithelial cells and non-lymphocytes.