Original paper
Epidermal proliferation and intracellular adhesion impairment as one mode of action of ultraviolet-B radiation

Introduction: Disturbances in cellular proliferation and adhesion are among the mechanisms leading to photocarcinogenesis.
Aim: To assess epidermal expression of Ki-67 and b-catenin in volunteers exposed to UVB.
Material and methods: Nine volunteers were exposed to UVB for 10 consecutive days (10 × 0.7 MED – whole body) – group 1. Nine other subjects were irradiated with UVB for 10 consecutive days (10 × 0.7 MED – whole body), followed by local exposure to 3 MED UVB dose (10 × 10 cm, buttock skin) – group 2. Volunteers from group 3 (n = 4) were exposed to acute local UVB (3 MED; buttock skin). Four unirradiated volunteers served as the control group (group 4). Twenty four hours after final irradiation skin biopsies were taken in order to perform immunohistochemical analysis with assessment of epidermal expression of Ki-67 and b-catenin.
Results: A significantly higher number of epidermal Ki-67(+) cells was observed in the volunteers from groups 1, 2 and 3 than in the control group. The number of Ki-67(+) cells was significantly higher in group 2 than in 1, as well as in group 2 than in 3. b-Catenin expression was significantly lower in irradiated groups compared to the control group.
Conclusions: The obtained results suggest the role of UVB in impairment of cellular proliferation and adhesion. These phenomena are likely to be among the factors involved in photocarcinogenesis.