Abstract:Objective To study the structure and function of a novel serine protease gene associated with human colorectal cancer SNC19.Methods The cDNA sequence was determined by both manual and automatic sequencing techniques. The full length cDNA sequence was obtained by the 5'-Rapid Amplification of cDNA Ends technique and web-based analysis. Open reading frame analysis and protein function prediction were also performed. Northern blot was used to detect the expression of SNC19 in various human normal tissues and tumor cell lines. Fluorescent in situ hybridization combined with fluorescent R-banding technique was employed to map the SNC19 gene on human chromosome.Results Full length SNC19 cDNA, size 3152 bp, encodes a protein highly homologous to a mouse serine protease epithin. In normal human tissues, high SNC19 expression levels were observed in the kidney, pancreas, prostate, small intestine and colon; moderate SNC19 expression levels were observed in the placenta, lung, liver, spleen thymus, testis and peripheral blood lymphocytes; and extremely low expression levels were observed in the heart, brain, skeletal muscle and ovary. In tumor cell lines, colorectal cancer cells SW480, SW620, SW1116 and Colo205, breast cancer cell Bcap37 and gastric cancer cells MKN28 and SGC7901 showed high levels of SNC19 expression; cervical cancer cell HeLa-S3, lung cancer PAA, oral epithelial cancer cell KB and lymphoma cell Raji showed moderate levels of SNC19 expression; and tongue squamous cancer cell Tca8113, leukemia cells HL-60, K562, MOLT-4, lung cancer cell A549 and melanoma cell G361 showed very low levels of SNC19 expression. SNC19 was mapped to human chromosome 11q24-25. Conclusion SNC19 encodes a novel human serine protease with 855 amino acid residues. As a novel serine protease associated with human colorectal cancer, the expression of SNC19 in various tissues and cell lines may have very important impact on their phenotypes and biological behaviors.%目的研究一个通过减式杂交方法获得的新的人大肠癌相关基因SNC19的结构和功能.方法对SNC19的cDNA进行了核苷酸序列测定,并通过5'-RACE及联网分析得到了全长cDNA序列,并对其编码的蛋白进行了分析及功能预测.利用Northern杂交方法检测了SNC19在各种人正常组织及多种肿瘤细胞系中的表达;采用In Situ-Max荧光原位杂交方法结合荧光R带技术对SNC19在人染色体上的定位做了研究.结果对包含全长开放阅读框(ORF)的3152?bp的SNC19 cDNA序列进行的分析以及预测的编码蛋白序列显示,SNC19编码一个与小鼠丝氨酸蛋白酶epithin有极高的同源性的蛋白,该基因在正常人肾脏、胰腺、前列腺、小肠、结肠组织中高表达,在胎盘、肺、肝脏、脾脏、胸腺、睾丸组织及外周血中中度表达,而在心脏、脑、骨骼肌及卵巢组织中低表达.该基因在肠癌细胞SW480、SW620、SW1116、Colo205、乳癌细胞Bcap37及胃癌细胞MKN28、SGC7901中高表达,在宫颈癌细胞HeLa-S3、肺癌细胞PAA 、口腔上皮癌细胞KB及淋巴瘤细胞Raji中中度表达,而在舌鳞癌细胞Tca8113、白血病细胞 HL-60、K562、MOLT-4、肺癌细胞A549和黑色素瘤细胞G361中低表达.SNC19定位于人染色体11q24-25.结论 SNC19编码一个由855个氨基酸残基组成的新发现的人类丝氨酸蛋白酶.由于丝氨酸蛋白酶是一类与细胞生长分化密切相关的蛋白,作为新的人丝氨酸蛋白酶的大肠癌相关基因SNC19在各种组织及细胞中的表达对这些细胞的表型及生物学行为可能具有十分重要的作用.
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