The cytoplasmic domain of C-CAM1 tumor suppressor is necessary and sufficient for suppressing the tumorigenicity of prostate cancer cells

We have previously shown that C-CAM1 cell adhesion molecule can suppress th e growth of prostate cancer cells in vivo. In this study, we determined the minimal domain of C-CAM1 that is required for its tumor-suppressive activi ty. DU145 prostate cancer cells were infected with recombinant adenoviruses containing various C-CAM1 mutant genes, and the effects of the mutant C-CA M1 proteins on the growth of DU145 cells were assessed in a nude-mice xenog raft model, Deletion of C-CAM1's cytoplasmic domain, which is not required for its adhesion activity, abolished the growth-suppressive activity, where as deletion of the adhesion domain did not. This observation suggests that C-CAM1's extracellular domain may be not essential for its tumor suppressiv e activity, Indeed, we found that expression of the C-CAM1 cytoplasmic doma in alone led to growth suppression of DU145 cells, These results suggest th at the cytoplasmic domain of C-CAM1 is necessary and sufficient for its gro wth-suppressive function, (C) 1999 Academic Press.