Abstract:

Objective To explore the changes in β-catenin expression and their significance in ultraviolet ray （UV）-induced development of skin tumor in mice. Methods The back of 60 mice was irradiated for various durations to establish tumor models. Ten mice receiving no irradiation served as the control. Fifteen mice were sacrificed respectively on week 2, 4, 6 and 8 after the beginning of irradiation and skin tissue specimens were resected from the back of these mice. Hematoxylin and eosin staining was conducted to observe the histopathological changes of skin, and immunohistochemistry and real time fluorescence PCR were carried out to detect the expression of β-catenin. Results Along with the UV irradiation, the exposed skin experienced a series of histological changes. The β-catenin expression was located in cell membrane in unirradiated mice and those irradiated for 2 weeks. There was an attenuation in the expression of β-catenin in cell membrane but an increment in the ectopic expression of β-catenin in 7, 9 and 9 of the 15 mice receiving 4-, 6- and 8-week irradiation respectively. Compared with the control mice, a significant increase was observed in the ectopic expression rate of β-catenin in mice receiving 4, 6 and 8 weeks of irradiation （all P < 0.045）. The relative expression level of β-catenin mRNA was 4.893, 7.857, 10.452, 12.481 and 14.702 in unirradiated mice, mice receiving 2, 4, 6 and 8 weeks of irradiation, respectively, with statistical differences between the 5 groups （all P < 0.05）. Conclusions There is an ectopic nuclear expression of β-catenin in cells of UV-irradiated mouse skin, which may be involved in the initiation and progression of skin tumors.