Figure 1.

Enhancer of zeste homolog 2 (EZH2) expression is associated with cisplatin (cDDP) resistance in ovarian cancer cells and tumor tissue specimens. A, Representative images of immunohistochemical analysis of EZH2 (brown, nucleus) and copper transporter 1 (CTR1) (brown, cellular membrane) in ovarian cancer specimens (scale bar = 500 μm in 20× images; scale bar = 50 μm in 200×) and of the semiquantification of EZH2 and CTR1 expression in cDDP‐sensitive/cDDP‐resistant ovarian cancer specimens. Mann‐Whitney test, P = .0005 and P = .0007. B, Colony formation assay and concentration survival curves for A2780, A2780C12, ES2, and ES2C12 cells after treatment with 2, 4, or 8 μmol/L cDDP (C12 cell lines were cDDP‐resistant cells generated after 12 cycles of increasing cDDP exposure). C, Accumulation of EZH2 and H3K27Me3 during 1, 2, 4, 6, 9, and 12 cycles of increasing cDDP exposure in A2780 and ES2 cells as monitored by Western blot analysis. D,E, Western blot and quantitative real‐time PCR analyses of EZH2 expression after transfection with EZH2 shRNA (ShEZH2) in A2780 and ES2 cells and EZH2 overexpressing plasmid in ES2 cells. F, Concentration survival curves for A2780 and ES2 cells incubated with serial doses of cDDP after EZH2 modification. Bars represent mean ± SD (n = 3). *P < .05, **P < .01, ***P < .001, ***P < .0001, Student's t‐test. ShNC, scrambled control