Pigment epithelium-derived factor plays an inhibitory role in proliferation and migration of HaCaT cells

The normal vasculature is maintained by a balance between angiogenic factors and anti-angiogenic factors. Recent studies have shown that pigment epithelium-derived factor (PEDF) can induce differentiation and inhibit angiogenesis of tumors. This study was designed to investigate the expression of PEDF and its roles in proliferation, adhesion and migration of HaCaT cells, a human keratinocyte cell line. Our results have shown that PEDF is expressed in HaCaT cells at both mRNA and protein levels determined by RT-PCR and Western blot, separately. PEDF signal mainly localizes in the cytoplasm of HaCaT cell, as determined by immunofluorescence. Furthermore, expression of PEDF is decreased by 50 ng/ml of VEGF₁₆₅. Proliferation and migration of HaCaT cells are decreased by PEDF, while adhesion of HaCaT cells is upregulated approximately by 29%. PEDF also induce the S phase accumulation of HaCaT cells. In addition, phosphorylation of ERK1/2, not JNK and p38, is decreased by PEDF. These results indicate that PEDF may play an inhibitory role on growth and migration of HaCaT cells through dephosphorylation of ERK1/2.