P8.110 Estrogen activity on human skin involves interaction with the insulin-like growth factor-I (IGF-I) signalling pathway

E. Makrantonaki, M. Oeff, S. Fimmel, C.E. Orfanos, Ch.C. Zouboulis

Department of Dermatology, Charité University Medicine Berlin, Campus Benjamin Franklin, Berlin, Germany

Estrogens have been suggested to exhibit a profound influence on skin aging. In our experimental series which tested the effects of hormones as single agents, IGF-I, but not 17β-estradiol, amplified neutral and polar lipid production in SZ95 sebocytes (p<0.001) and proliferation of breast area skin fibroblasts from a 60-year-old female (p<0.01). To investigate the hypothesis of IGF-I signalling pathway involvement in estrogen effects on human skin, human skin cells maintained in steroid-free medium were first tested and found to express IGF-I receptor (IGF-IR) and estrogen receptor-α (ER α) using RT-PCR and Western blotting. Treatment of SZ95 sebocytes and fibroblasts with 17 β -estradiol over 48-72 h enhanced IGF-I synthesis (+28% and +41%, respectively). IGF-IR expression was significantly reduced under IGF-I (-41 to -48%) and 17 β -estradiol treatment (-37 to -48%) of SZ95 sebocytes for 48-72 h, while in fibroblasts a reduction of IGF-IR expression under IGF-I treatment (-47%, 48-72 h) was assessed but an initial increase under treatment with 17 β -estradiol (+32% at 48 h, -15% at 72 h) was observed. ER α expression did not change under any regimen tested. In conclusion, although skin cells express ER α making them directly susceptible to estrogens, there is obviously a cross-talk between estrogen and IGF-I signalling pathways. IGF-I is playing a major role in regulating lipid synthesis in sebocytes and proliferation in fibroblasts and may, therefore, mediate the estrogen activity on normal and aged skin cells.