Cloning, expression, and mutation analysis of NOR1, a novel human gene down-regulated in HNE1 nasopharyngeal carcinoma cell line

Purpose: To investigate cloning, expression, and mutation analysis of the putative candidate tumor suppressor gene related with nasopharyngeal carcinoma (NPC). Methods: We studied the expression profiles in the NPC cell line HNE1 with the normal nasopharyngeal epithelial cell as control by using cDNA array representing 11,000 cDNA clusters. EST W95442 was found down-regulated in HNE1. Subsequently, the corresponding gene sequence including this EST was established by cDNA cloning and the RACE (rapid amplification of cDNA end) procedure. The expression pattern of this gene was examined by using Northern blot analysis in various human tissues. Furthermore, we screened the mutations of the coding sequence of the gene using reverse transcription-polymerase chain reaction and single-strand conformation polymorphisms (RT-PCR-SSCP) as well as direct sequencing analysis. Results: A novel gene (GenBank accession No. AF462348) was cloned and named NOR1 standing for oxidored-nitro domain-containing protein 1 (Human Gene Nomenclature Committee-approved symbol). Northern blot analysis revealed that the NOR1 gene had two transcripts (1.2 kb, 1.6 kb), and expressed ubiquitously in human tissues. Moreover, a Glu58Gly mutation in the exon 1 of NOR1 was detected in two of 25 NPC biopsies. Conclusions: We cloned a novel gene NOR1, and the Glu58Gly polymorphism of NOR1 may be involved in the development and/or progression of NPC suggesting that NOR1 could be a candidate tumor repressor gene related with NPC.