Molecular cloning and characterization of NAG-7: a novel gene downregulated in human nasopharyngeal carcinoma

Objective To identify novel tumor suppressor genes at chromosome 3p24-26 in human nasopharyngeal carcinoma (NPC). Methods Twenty epithelial-derived expressed sequence tags (EST) were select ed from chromosome 3p24-26. RT-PCR and Northern blot were used to detect th e expression of the ESTs in NPC cell line, HNE-1, and primary cultures of n ormal nasopharyngeal epithelial cells. One EST, which was substantially dow nregulated in the HNE-1 cell line, was detected in 19 NPC biopsy samples. c DNA library screening was used to get its full sequence and the sequence of this novel gene was analyzed. Results A novel gene located at chromosome 3p25.3 was obtained and named NA G-7. It was downregulated in 26.3% (5/19) of NPC biopsy samples. Its 1677 b p full length cDNA had a potential open reading frame predicting a 94 amino acid protein with a molecular weight of 11023.87 Dalton. Analysis of the N AG-7 gene showed that it was a transmembrane protein containing a protein k inase C phosphorylation site and a myristyl site. It has no significant hom ology to any reported genes in the database of GenBank. Conclusion NAG-7 is a novel gene downregulated in NPC, suggesting that it m ay be involved in the development of NPC.