[Cloning and expression analysis of lung carcinoma related gene HLCDG1]

High frequent loss of hetero- zygosity (LOH) of 3p, 5q, 6q, 9p, 10q, 11p, 13q, 17p, and 19p in lung carcinoma was detected by comparative genomic hybridization (CGH) and genomic-wide scan for analysis of genetic alteration with microsatellite allelotying. It was indicated that there might be some other unknown tumor susceptible genes or suppressor genes likely to be involved in lung carcinoma development and progression. The aim of this study was to clone the full-length cDNA of LXDD1,an expressed sequence tag(EST) isolated by mRNA differential display, which is significantly down-regulated in lung carcinoma and represents a novel gene.

Differential expression of LXDD1 in lung carcinoma was confirmed by Northern blot analysis, the expression of the LXDD1 in human normal tissues and the size of the transcription of the LXDD1-representative gene were also determined using MTN (Multiple Tissues Northern Blots). The putative full-length cDNA of the EST-representative gene was cloned and analyzed by bioinformatics. In addition, differential reverse transcription polymerase chain reaction (RT-PCR) was used to detect the expression of the novel gene in various cancer cell lines, primary lung carcinomas, and matched normal lung tissues.

The full length cDNA with no homology to any reported genes in the database of GenBank was successfully cloned and named HLCDG1 (Human lung carcinoma deleted gene 1, GenBank accession number AF447582). A transmembrane protein with 166 amino acids was deduced to come from the open reading frame of the 3113 bp full-length cDNA, HLCDG1 gene was confirmed to be located at chromosome band 5q33 by alignment of electric polymerase chain reaction (e-PCR).

HLCDG1 is a novel gene down-regulated in lung carcinoma, which may be involved in the development of lung carcinoma.