Down‐regulation in Multiple Human Cancers of a Novel Gene, DMHC, from 17q25.1 That Encodes an Integral Membrane Protein

Frequent observations of allelic loss in chromosomal band 17q25.1 in a variety of human cancers have suggested that one or more tumor suppressor genes are present in that region. Moreover, a genetic locus for hereditary focal non‐epidermolytic palmoplantar keratoderma, a condition associated with cancer of the esophagus (TOC; Tylosis with Oesophageal Cancer), lies in the same region. We screened cell lines derived from a variety of human cancers by reverse transcription‐polymerase chain reaction (RT‐PCR) to detect alterations in expression of genes within the region in question, by examining expressed sequence tags located there. These experiments identified an 1834‐bp full‐length cDNA encoding a novel, 441‐amino acid integral membrane protein with seven putative transmembrane domains. This gene showed loss or extreme decrease of expression in 6 of 10 uterine cancer‐cell lines, 2 of 11 hepatic cell carcinoma‐cell lines, 2 of 7 lung cancer‐cell lines, 1 of 6 gastric cancer‐cell lines, and 1 of 10 breast cancer‐cell lines. (We named it DMHC (“down‐regulated in multiple human cancers”).) Our results suggest that loss of expression of DMHC at 17q25.1 may play an important role in development of variety of human cancers.