Abstract: Xu Qingfang*, Hou Wei, Lai Wei, Zheng Yue, Liu Chen, Lu Chun. *Department of Dermatology, Third Affiliated Hospital, Sun Yat-sen University, Guangzhou 510630, China Corresponding author: Lai Wei, Email: drlaiwei@163.com 【Abstract】 Objective To investigate the effect of ultraviolet A（UVA） radiation on the expression and secretion of cathepsin G （CatG） by human dermal fibroblasts. Methods Dermal fibroblasts were isolated from the foreskins of boys, and subjected to primary culture and subculture. After 10 or less passages, the fibroblasts were collected and divided into several groups to be irradiated with 10 J/cm2 UVA followed by 24, 48 and 72 hours of additional culture, or be irradiated with 10, 20 and 30 J/cm2 UVA followed by 24 hours of additional culture, with those receiving no treatment serving as the control group. Subsequently, cells and culture supernatant were collected, real time PCR and Western blot were performed to detect the expressions of CatG mRNA and protein respectively in these cells, and enzyme-linked immunosorbent assay （ELISA） was conducted to measure the expression of CatG protein in the culture supernatant of these cells. Results Compared with the control group, the fibroblasts irradiated with 10 J/cm2 UVA showed a significant increase at 24, 48 and 72 hours in the expressions of CatG mRNA （0.376 ± 0.014 vs. 0.183 ± 0.003, 0.308 ± 0.022 vs. 0.185 ± 0.005, 0.296 ± 0.032 vs. 0.182 ± 0.004, respectively, all P < 0.05） and protein （1.80 ± 0.12 vs. 0.96 ± 0.06, 1.41 ± 0.17 vs. 0.95 ± 0.22, 1.27 ± 0.09 vs. 1.00 ± 0.14, respectively, all P < 0.05）, as well as in the supernatant level of CatG protein （（161.35 ± 7.55） vs. （122.45 ± 6.46） ng/L, （141.76 ± 2.95） vs. （124.17 ± 6.15） ng/L, （139.63 ± 3.04） vs. （121.72 ± 3.17） ng/L, respectively, all P < 0.05）, with the strongest increase observed at 24 hours. At 24 hours after 10, 20 and 30 J/cm2 of UVA radiation, the expression of CatG mRNA in irradiated fibroblasts was 1.90, 2.51 and 3.04 times respectively （all P < 0.05）, the expression of CatG protein was 1.88, 3.97 and 4.72 times respectively （P < 0.05）, and the supernatant level of CatG protein was 1.36, 1.50 and 1.66 times respectively （P < 0.05）, that in the control group, and there was an increasing trend in all the above three parameters with increasing dose of UVA. Conclusion Acute UVA radiation can promote the expression and secretion of CatG by human dermal fibroblasts.

Key words: Fibroblasts, Cathepsins, Ultraviolet rays, Cell aging