Cten, a COOH-terminal tensin-like protein with prostate restricted expression, is down-regulated in prostate cancer.

Tensin is a signaling molecule that binds to actin filaments and localizes to focal adhesions. Recently, we have discovered that tensin represents a new gene family with related members that are expressed in a variety of tissues. In this study, we report the identification and characterization of a new COOH-terminal tensin-like molecule, cten. Human cten cDNA encodes a 715 amino acid sequence containing the Src homology 2 and phosphotyrosine-binding domains that are similar to the COOH termini of tensin molecules. Although cten is shorter and does not have the actin-binding domain found in other tensins, analysis of the genomic structure has suggested that cten is related to the tensin gene family. In addition, cten also localizes to focal adhesions. In contrast to other tensin members, cten expression is restricted to prostate and placenta by Northern blot analysis. Furthermore, examination of cten expression in prostate cancer/cell lines has revealed its down-regulation in tumor samples. Our studies have suggested that during evolution, cten has preserved its role in mediating signal transduction at focal adhesions through the Src homology 2 and phosphotyrosine-binding domains but has lost its function in binding to actin filaments. The evolutionary divergence has produced the first focal adhesion protein specifically expressed in the prostate and the placenta, which may be involved in preventing prostate tumor formation.