Abstract：Objective: To investigate the effect of the EZH2 inhibitor DZNep on the proliferation of uveal melanoma cells. Methods: In this experimental study, the expression of EZH2 in uveal melanocytes (UM95, UM96) and uveal melanoma cells (M23, SP6.5) was detected by Western blot analysis. The effect of DZNep on cell viability and clonal growth was evaluated by MTS and colony formation assay. Furthermore, cell proliferation was detected by EdU assay, whereas cell cycle was determined by flow cytometry. Then, Western blotting was carried out to test the protein levels of EZH2, H3K27me3, and cell cycle-related proteins as well as p-ERK. Data were analyzed by an independent t test. Results: Compared with UM95, the expression of EZH2 increasedsignificantly in M23 and SP6.5 cells (t=25.050, P=0.002; t=14.220, P=0.005). MTS assay showed that the viability of M23 and SP6.5 cells was inhibited by DZNep ina doseor time-dependent manner. When compared with the DMSO-treated group, the clone numbers of M23 and SP6.5 cells in the DZNep group were obviously decreased (t=3.364, P=0.015; t=6.997, P<0.001), and the ratio ofthe proliferative marker EdU labelling cells was lower (t=5.117, P=0.002; t=3.399, P=0.015). Also, flow cytometry revealed that the percentage of cells in the G1 phase in the DZNep group was markedly higher than that in the DMSO group (t=6.199, P=0.003; t=3.729, P=0.020). Furthermore, Western blot analysis showed that compared with the DMSO-treated group, some proteins were reduced after exposureto DZNep, including EZH2 (t=5.214, P=0.035; t=13.530, P=0.005), p-Rb (t=4.551, P=0.045; t=4.655, P=0.043), E2F1 (t=8.090, P=0.015; t=9.313, P=0.011), p-ERK (t=4.819, P=0.040; t=8.951, P=0.012). as well as the level of H3K27me3 (t=5.257, P=0.034; t=5.697, P=0.030). Conclusions: DZNep can inhibit the proliferation of uveal melanoma cells, and is a promising epigenetic drug for the treatment of this malignancy.
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