Novel human esophagus-specific gene C1orf10: cDNA cloning, gene structure,and frequent loss of expression in esophageal cancer

We have identified a novel human gene, designated C1orf10, using modified d ifferential display PCR. The C1orf10 gene, which spans 5 kb in length, is c omposed of three exons. The deduced protein contains 495 amino acids with o ne transmembrane domain. The amino acid sequence of C1orf10 is characterize d by the presence of a calcium-binding motif of about 90 amino acids at its N-terminal and a conserved consecutive repeat sequence of 60 amino acids t hat was identified previously only in bacterial ice nucleation proteins. In normal adult tissues, C1orf10 is highly expressed only in the esophagus an d was undetectable in a total of 15 other tissues examined, suggesting its important role in esophageal cells. The expression of C1orf10 is either dra matically reduced or absent in esophageal cancer cell lines (3/3) as well a s primary esophageal cancer tissues (35/37) compared with the corresponding normal esophageal mucose. Using a radiation hybrid panel, C1orf10 was foun d to be located on chromosome 1q21. These findings suggest that expression of C1orf10 is unique to esophageal cells and that loss of its expression ma y play a role in the development of esophageal cancer. (C) 2000 Academic Pr ess.