减式杂交筛检大肠癌负相关基因的研究

目的在分子水平寻找与人大肠癌的发生发展相关的新的因素。方法采用减式杂交技术筛选大肠癌下调基因。结果共获得４６个在正常肠粘膜中表达、而在大肠癌中低表达或不表达的克隆。其中２个（ＳＮＣ６和ＳＮＣ１９）已被ＮＣＢＩ作为新基因录入，编号分别为Ｕ１７７１４（ＳＮＣ６）和Ｕ２０４２８（ＳＮＣ１９）。其中ＳＮＣ６已完成全序列测定，为２９３２ｂｐ，推测其为编码２７１个氨基酸的蛋白，分子量为３００００。与蛋白数据库比较，最高同源性仅３０％，染色体定位于２２ｑ１３。ＲＮＡｄｏｔｂｌｏｔ显示：ＳＮＣ６的表达在大肠癌中低于在相应的正常肠粘膜中，在乳癌中亦有此现象。ＮｏｒｔｈｅｒｎＢｌｏｔ发现其在肝、肺、前列腺、睾丸、卵巢及Ｋ５６２细胞中的表达高于其它组织。结论ＳＮＣ６可作为新的大肠癌负相关基因加以研究、利用。

Application of subtractive hybridization in screening for colorectal cancer negatively related genes

Objective\ To search previously uncertained factors that corelated with the occurence and develo pment of human colorectal cancer. Method Subtractive hybridization technique was employed to screen down regulated genes of colorectal cancer.Results We obtained46clones which highly were expressed in normal intestinal mucosa but much lower or none in colorectal cancer.Two of the46clones,SCN6 and SCN19,were accepted by the Genbank Database as novel genes with the accession numbers U17714 and U20248.Full length cDNA(2932bp)of SNC6was sequenced,and supposed to encode aprotein comprised 271 amino acids,MW30kd,which shared less than30%homology with the protein database.The gene was localized to human chromosome22q13.RNA dot blot analysis showed that the expression level of SNC6was lower in colorectal cancer than in normal intestinal mucosa,and similar results were found in breast cancer.Northern blot showed higher expression levels of SNC6in liver,lung, prostate,testis,ovary and K562cell line than in other tissues. Coneclusion SNC6 can be further investigated as anovel colorectal cancer negatively related gene.