Abstract:

Objective To explore the effects of heat treatment and ultraviolet B （UVB） radiation alone or in combination on the expression of heat shock protein （HSP） 72 in human epidermal melanocytes. Methods Melanocytes were obtained from human foreskin, and subjected to primary culture. After 3 to 5 passages, the melanocytes were classified into 4 groups: control group （receiving no treatment）, heat treatment group （treated with heat at 42 ℃ for 1 hour every day for 3 days）, UVB group （irradiated with UVB at 50 mJ/cm2 daily for 3 days）, combination group （treated with heat at 42 ℃ for 1 hour followed by irradiation with UVB at 50 mJ/cm2 daily for 3 days）. After another 2- to 6-hour culture following the last treatment, melanocytes were collected and subjected to real time PCR and Western blot for the detection of HSP72 mRNA and protein expression, respectively. Results The mRNA and protein expressions of HSP72 were significantly higher in the heat treatment group and combination group than in the control group （mRNA: 6.584 ± 0.871 and 7.269 ± 0.454 vs. 0.975 ± 0.089, both P < 0.001; protein: 2.022 ± 0.058 and 2.080 ± 0.045 vs. 0.532 ± 0.033，both P < 0.001）, but was similar between the UVB group and control group （mRNA: 0.832 ± 0.084 vs. 0.975 ± 0.089, P > 0.05; protein: 0.546 ± 0.021 vs. 0.532 ± 0.033, P > 0.05）. The ANOVA of factorial design showed that neither heat treatment nor UVB irradiation had interaction effect on the mRNA or protein expression of HSP72（F = 2.106, 1.399 respectively, both P < 0.05）. Conclusions Heat treatment can cause an increase in the expression of HSP72, which may enhance the function of melanocytes and protect melanocytes from UVB induced damage.

Key words: Heat shock protein 72