Expression of pigment epithelium-derived factor in human melanocytes and malignant melanoma cells and tissues: Is loss of pigment epithelium-derived factor associated with melanoma?

BACKGROUND: Pigment epithelium-derived factor (PEDF) was first isolated from the medium conditioned by human fetal retinal pigment epithelial cells and has been detected in a broad range of human fetal and adult tissues. Recent studies have indicated that PEDF activity is inhibitory to angiogenesis. OBJECTIVE: To study the expression and distribution of pigment epithelium-derived factor (PEDF) in human melanocytes, malignant melanoma cells and tissues. RESULTS: PEDF was expressed in human melanocytes. The expression of PEDF protein diminished in the following orders healthy skin, pigmented nevus and human malignant melanoma (p < 0.001). Both the expression of PEDF mRNA and protein was much lower or almost absent in the malignant melanoma cell line A375 than that in human melanocytes (p < 0.001). METHODS: The expression and distribution of PEDF in human healthy skin, pigmented nevus and malignant melanoma were studied. The expression of PEDF mRNA in human melanocytes and malignant melanoma cell line A375 was measured by reverse transcription polymerase chain reaction (RT-PCR) and PEDF protein was detected by immunohistochemical method and Western blotting analysis. CONCLUSION: The lack of PEDF expression may contribute to the pathogenesis of malignant melanoma.