Epidermal growth factor and 1 alpha,25-dihydroxyvitamin D-3 suppress lipogenesis in hamster sebaceous gland cells in vitro

We have previously reported the establishment of a culture system of hamste r auricular sebocytes. Although their morphologic and biochemical propertie s are very similar to those of human sebocytes, the regulation of lipogenes is is not clear. Therefore, we investigated the effect of epidermal growth factor, all-trans retinoic acid, 1 alpha ,25-dihydroxyvitamin D-3, and andr ogens such as testosterone and 5 alpha -dihydrotestosterone on lipogenesis in cultured hamster sebocytes. Intracellular lipid droplets detected with O il-Red-O staining were observed in 5 d cultures and increased in a time-dep endent manner; 40.7% +/- 1.11% of 2 wk cultured cells tested lipid-positive by flow cytometric analysis. When the hamster sebocytes were cultured in t he presence of epidermal growth factor, all-trans retinoic acid, or 1 alpha ,25-dihydroxyvitamin D3, the intracellular lipid droplets were diminished by all-trans retinoic acid and epidermal growth factor, and slightly by 1 a lpha ,25-dilrydroxyvitatnin D3. The intracellular lipid droplets consisted mainly of triglycerides (71.8%) and, as minor components, cholesterol (18.0 %), wax esters (3.6%), and free fatty acids (6.6%). Epidermal growth factor and all-trans retinoic acid decreased the intracellular accumulation of tr iglycerides (92.6% and 96.1% inhibition, respectively) and free fatty acids (54.3% and 62.6% inhibition, respectively) in the sebocytes. In addition, 1 alpha ,25-dihydroxyvitamin D-3 decreased the triglyceride level (34.3% in hibition), but augmented the accumulation of wax esters (30% increase). The re was no difference in the level of cholesterol as a result of these treat ments, however. In contrast, 5 alpha -dihydrotestosterone augmented the for mation of intracellular lipid droplets along with an increase in the accumu lation of triglycerides in hamster sebocytes. Our findings that regulation of lipogenesis by all-trans retinoic acid and androgen in hamster sebocytes is identical to regulation in humans suggest that hamster sebocytes are us eful for the elucidation of sebaceous function at the cellular level. Furth ermore, this is the first evidence that epidermal growth factor and 1 alpha ,25-dihydroxyvitamin D-3 may act as suppressors in the regulation of lipog enesis in hamster sebocytes in vitro.