Abstract: Objective The objective of this study was to investigate the effect of salinomycin on proliferation and autophagic flux of human melanoma M21 cells.Methods The cell survival rate was determined by MTS assay and IC₅₀ values(half inhibitory concentration)were calculated.The morphological changes of cells after salinomycin administration were observed under optical microscope.Flow cytometry was used to examine the apoptosis rate of M21 cells.Western blot was used to detect the expression of autophagic-related protein LC3B and p62 in M21 cells.The presence of autophagosomes in M21 cells after salinomycin administration was observed under transmission electron microscope.Western blot and immunofluorescence were used to detect the level of p62 protein and localizing changes in M21 cells.Results Salinomycin significantly inhibited proliferation of M21 cells,and the IC₅₀ values were(1.38±0.18)μM.After salinomycin administration,the proliferation rate of M21 cells was slowed down,and obvious vacuoles appeared in the cells.Salinomycin could not only induce cell apoptosis,but it also increased the ratio of LC3B-Ⅱ/LC3B-Ⅰ in M21 cells.The increase and accumulation of autophagosomes were directly observed under transmission electron microscope.The level of p62 protein was slightly elevated after salinomycin treatment and gradually aggregated into the cytoplasm,indicating that autophagic flux was inhibited.Conclusion Salinomycin can inhibit the proliferation of human malignant melanoma M21 cells,and its mechanism may be related to the accumulation autophagosomes granules and inhibition of autophagic flux.

Key words: Malignant melanoma, M21 cell line, Salinomycin, Autophagy