Reduced Susceptibility to Two-Stage Skin Carcinogenesis in Mice with Epidermis-Specific Deletion of Cd151

Altered expression of the tetraspanin CD151 is associated with skin tumorigenesis; however, whether CD151 is causally involved in the tumorigenic process is not known. To evaluate its role in tumor formation, we subjected epidermis-specific Cd151 knockout mice to chemical skin carcinogenesis. Mice lacking epidermal Cd151 developed fewer and smaller tumors than wild-type mice after treatment with 7,12-dimethylbenzanthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA). Furthermore, Cd151-null epidermis showed a reduced hyperproliferative response to short-term treatment with TPA as compared with wild-type skin, whereas epidermal turnover was increased. Tumors were formed in equal numbers after DMBA-only treatment. We suggest that DMBA-initiated keratinocytes lacking Cd151 leave their niches in the epidermis and hair follicles in response to TPA treatment and subsequently are lost by differentiation. Because genetic ablation of Itga3 also reduced skin tumor formation, we tested whether reduced expression of alpha 3 could further suppress tumor formation in epidermis-specific Cd151 knockout mice. Although DMBA/TPA-induced formation of skin tumors was similar in compound heterozygotes for Cd151 and Itga3 to that in wild-type mice, heterozygosity for Itga3 on a Cd151-null background diminished tumorigenesis, suggesting genetic interaction between the two genes. We thus identify CD151 as a critical factor in TPA-dependent skin carcinogenesis.