P2 DICKKOPF 1 INDUCTION BY ANDROGEN
Sung YK, Kwack MH, Kim JC Kim MK
Department of Immunology, Kyungpook National University School of Medicine, Daegu, Korea

Androgens are the main regulator of changes in human hair growth, and dihydrotestosterone (DHT) is the most potent natural androgen. Circulating androgens enter the hair follicle via the capillaries of the dermal papilla (DP) situated at the base of the follicles. Once bound by the androgen receptors present within the DP cells, androgens cause an alternation in the production of paracrine regulatory factors. These paracrine factors are thought to influence the activity of the follicular cells. DP in frontal and vertex scalp hair is involved in mediating responses to androgen, but DP in occipital scalp follicle is known to androgen-insensitive. In this study, we detected androgen receptor (AR) expression in occipital scalp DP and in cultured DP cells. RT-PCR analysis showed that DKK-1 mRNA is up-regulated in 6 h after 10-7M DHT treatment. Also, ELISA data showed that DKK-1 is secreted to conditioned media upon DHT exposure. Moreover, coculture experiments showed that neutralizing antibody against DKK-1 attenuated DHT-induced growth inhibition of ORS cells. Altogether, this study showed that expression of DKK-1 is up-regulated in occipital DP cells by DHT and suggests that secreted DKK-1 may suppress the growth of neighboring keratinocytes.