Role of β-TrCP ubiquitin ligase receptor in UVB mediated responses in skin.

Skin cancers are the most common cancers in the United States. Exposure to UVB radiation is a major risk factor for skin cancer induction. SCF(β-TrCP) E3 ubiquitin ligase has been found to be involved in cell cycle, cell proliferation and transformation. Aberrant up-regulation of beta-transducin repeats-containing proteins (β-TrCP) is often found in cancer cell lines and primary tumors. We have previously demonstrated that β-TrCP2 is over-expressed in chemically induced mouse skin tumors. Various cellular stress stimuli, including UVB, induce an increase in β-TrCP1 mRNA and protein levels in human cells. We have previously shown that inhibition of β-TrCP function, by induction of dominant negative β-TrCP2 (β-TrCP2(ΔF)), in vitro in hTERT immortalized normal keratinocytes, results in increase in UVB induced apoptosis. We have generated transgenic mice with inducible, selective expression of dominant negative β-TrCP2 in epidermis with the Keratin 5 promoter (K5-rTA x TRE-HA-β-TrCP(ΔF)). Here we report that inhibition of β-TrCP function in mouse epidermis results in decrease in UVB-induced edema, hyperplasia, and inflammatory response and increment in UVB-induced apoptosis in skin. Our results suggest that β-TrCP may be an essential player in UVB induced responses in skin and can be a potential therapeutic target for skin cancer.