Abstract: Objective To study the expression and significance of pigment epithelium derived factor(PEDF) in the tissue of pigmented nevi and malignant melanoma and in human malignant melanoma cell line A375.Methods The expression and distribution of PEDF protein were detected by ixnmunohistochemical method in the tissue of normal skin,pigmented nevi and human malignant melanoma,and by Western blot analysis in normal human melanocytes and A375 cells.The PEDF mRNA expression was measured by reverse transcription polymerase chain reaction〔RT-PCR) in normal human melanocytes and A375 cells.Results The highest expression of PEDF protein was observed in normal skin,followed in decreasing order by pigmented nevi and malignant melanoma tissue,with a significant difference among the three tissues(p < 0.05).PEDF protein was expressed in normal melanocytes but not in A375 cells.The mRNA expression of PEDF was markedly lower in A375 cells than that in normal melanocytes.Conclusion The decrease of PEDF expression may contribute to the pathogenesis of malignant melanoma.

Key words: Melanoma, Nevus,pigmented, Pigment epithelium derived factor