Isolation and characterization of a novel human lung-specific gene homologous to lysosomal membrane glycoproteins 1 and 2: significantly increased expression in cancers of various tissues.

We have isolated and characterized a novel human lung-specific gene and observed its increased expression in cancers arising from various tissues. The cDNA, designated TSC403, contained an open reading frame of 1248 nucleotides encoding 416 amino acids; the deduced amino acid sequence showed significant similarities to lysosomal membrane glycoproteins (lamps) 1 and 2. We localized the gene to chromosomal band 3q27, a genomic region that is often amplified in human cancers of several tissue types. We detected a high level of the TSC403 transcript in primary cancers of the esophagus, colon, fallopian tube, ovary, breast, and liver, although expression of this gene was barely detectable in corresponding normal tissues. These findings indicated that up-regulation of the TSC403 transcript may be related to the development and/or progression of cancer in humans.