Abstract: ZHANG Ping, PANG Xiao-wen, LI You, LI Dong-guang, LIU Wei. Department of Dermatology, General Hospital of Air Force, Beijing 100142, China Corresponding author: LIU Wei, Email: weiliuair@gmail.com 【Abstract】 Objective To estimate the effect of glycoprotein （transmembrane） nonmetastatic melanoma protein B （GPNMB） on the proliferation and migration of as well as melanogenesis in melanoma cells. Methods The expression of GPNMB was detected by immunofluorescence assay in two melanoma cell lines M14 and G-361, as well as in primary human melanocytes. Then, the three kinds of cells each were classified into three groups: experimental group treated with small interfering RNA targeting GPNMB （GPNMB-siRNA）, negative control group treated with the negative control siRNA, blank control group remaining untreated. Methyl thiazolyl tetrazolium （MTT） assay, transwell invasion assay and spectrophotometry were performed to evaluate cell proliferation activity, invasion potential and melanin levels, respectively. Statistical analysis was done using Student′s t test. Results GPNMB was expressed in both melanoma cells and melanocytes. The transfection with GPNMB-siRNA down-regulated the mRNA and protein expressions of GPNMB in, and markedly suppressed the proliferation and migration of, melanoma cells. In detail, the proliferative activity （expressed as the absorbence value at 570 nm） of M14 and G361 cells was reduced by 35% and 40% respectively, the migration activity of M14 and G361 cells by 49% and 51% respectively, and the melanin levels in melanocytes, M14 cells and G361 cells by 73%, 82% and 69% respectively, in the experiment group compared with those in the blank control group. Conclusions The siRNA-mediated silencing of GPNMB could effectively inhibit the proliferation of, invasion of and melanogenesis in melanoma cells, which suggests that GPNMB plays critical roles in the initiation and progression of melanoma. 【Key words】 GPNMB; RNA, small interfering; Melanins; Cell proliferation; Cell movement