Effect of 12-O-tetradecanoylphorbol 13-acetate(TPA) on the Expression of Keratin in HaCaT cells

Abstract

In human skin, specific keratin markers reflect on normal differentiation and pathologic conditions. This experiment focused on the expressional pattern of keratin 10 (K10: normal differentiation marker), and keratin 8 & 13 (K8 & K13:pathologic differentiation marker) together with their cellular localization after treating HaCaT cells with 12-Otetradecanoylphorbol 13-acetate (TPA). The cells were treated with TPA at 0, 0.1, 1 g/ml for 2 hours or 6 hours. Morphologic studies revealed that TPA treatment changed the shape of cells into the fibroblast-like cells with highly folded nuclear membrane and reduced number of the desmosome. The results of indirect immunofluorescent staining and Northern blotting analysis showed that TPA considerably down-regulated the expression of K10, while markedly up-regulating the expression of K8 and K13 both at protein and mRNA levels. Furthermore, by simultaneous staining for keratins and DNA content in flow cytometry, it was found that TPA increased the expression of K8 and K13 dramatically at the S-G2-M phase of the cells. In conclusion, these changes induced by TPA in HaCaT cells may indicate a close relationship between the morphologic change and the altered expression of keratin subfamilies. It also suggests that TPA known as a tumor promotor may directly induce the potentially malignant cells even without the support of tumor initiator.