Abstract:

Objective To measure the expression of granulocyte colony-stimulating factor receptor （G-CSFR） in human melanocytes and to evaluate the biologic effect of recombinant human granulocyte colony-stimulating factor （rhG-CSF） on human melanocytes. Methods Melanocytes were obtained from circumcision specimens of healthy males, and neutrophils were isolated from heparin-anticoagulated peripheral blood of healthy human followed by a primary culture. Then, the melanocytes in third passage were cultured with or without the presence of various concentrations （200, 400, 600, 800 μg/L） of rhG-CSF for 72 hours. The growth and morphology of melanocytes were observed. Flow cytometry was performed to detect the expression of G-CSFR in untreated human melanocytes, neutrophils and erythroleukemia cells （HEL 92.1.7）. Western blot and reverse transcription PCR （RT-PCR） were carried out to measure the expression of G-CSFR protein and mRNA respectively in the neutrophils, HEL 92.1.7 cells, treated or untreated human melanocytes. Methyl thiazolyl tetrazolium （MTT） assay was performed to evaluate the proliferation, and dopa-oxidation assay to estimate the tyrosinase activity, of treated melanocytes. Results The expression rate of G-CSFR was 76.81% ± 10.70% in human melanocytes, significantly higher than that in the HEL 92.1.7 cells （2.53% ± 1.54%, P < 0.01）, but lower than that in the neutrophils（85.76% ± 15.71%, P < 0.05）. Both G-CSFR protein and mRNA were expressed in melanocytes, and there was no significant differences in the expression level of G-CSFR protein and mRNA among melanocytes treated with different concentrations of rhG-CSF（both P﹥0.05）. The expression levels of G-CSFR protein and mRNA in the melanocytes were significantly higher than those in the HEL 92.1.7 cells （both P < 0.01）, but lower than those in the neutrophils （P < 0.05 or < 0.01）. rhG-CSF at 200－800 μg/L displayed a significantly promotive effect on the proliferation of melanocytes （P < 0.01 or < 0.05 ）, and the effect was in a dose-dependent manner when rhG-CSF ranged from 200 to 600 μg/L （P < 0.01）. The rhG-CSF at 600 μg/L and 12-O-tetradecanoyl-phorbol-13-acetate （TPA） at 20 μg/L showed an equivalent effect on the proliferation of melanocytes （164.04% ± 13.0% vs. 165.62% ± 10.6%, P > 0.05）. However, rhG-CSF from 200 to 800 μg/L had no significant impact on the tyrosinase activity of melanocytes （all P > 0.05）. Conclusions G-CSFR is expressed in human melanocytes. rhG-CSF can promote the proliferation of cultured human melanocytes, but has no obvious influence on the tyrosinase activity of melanocytes.

Key words: Biologic effect