Study of Regulatory Mechanism of Various Growth Factors in Human Epidermal Cells and Fibroblasts

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(1) Effects of TGF-beta on growth and differentiation of cultured human keratinocytes : TGF-beta inhibited human keratinocyte growth over 0.25 ng/ml and arrested in G_1/G_0 phase of cell cycle. This growth arrest was reversible unless incubation duration is too long.(2) Roles of TGF-alpha in normal and psoriatic epidermis : The localization of TGF-alpha in normal and psoriatic epidermis was examined immunocytochemically. TGF-alpha was observed mainly in the upper layer of normal epidermis. In contrast, TGF-alpha was present intensely through the whole epidermis except basal layer in psoriatic epidermis. This result indicates the increase of TGF-alpha in psoriatic epidermis compared to normal epidermis. To further confirm the increase of TGF-alpha, the amount of TGF-alpha in extracts of normal and psoriatic epidermis was measured by ELISA. The amount TGF-atpha in the extracts of normal epidermis was 1.45 <plus-minus> 1.06 ng/g of wet tissue, while the amount in psoriatic involved epidermis was 6.71 <plus-minus> 0.75ng/g of wet tis(3) Effects of IL-6 on growth and differentiation of cultured human keratinocytes : IL-6 stimulated human keratinocyte growth. Immuno-cytochemical study showed that I1-6 and IL-6 receptor were present in basal layer of epidermis. This suggests that IL-6 possibly stimulates keratinocyte growth in autocrine manner. IL-6 has no clear effect on differentiation of human keratinocytes.(4) Effects of platelet-derived endothelial cell growth factor (PD-ECGF) on growth and differentiation of cultured human keratinocytes : PD-ECGF stimulated human keratinocyte growth. However, PD-ECGF has no clear effect on differentiation of human keratinocytes.(5) A new method for quantifying keratinocyte differentiation using immuno-fluorescent staining of involucrin and cyto-fluorography was established.