DNMT1-MUC1 mediated epigenetic modification contributes to STON2 regulation in ovarian cancer cells. a 3AO and Caov3 cells were treated with 0 μM, 10 μM, and 15 μM Aza (S1782, Selleck, USA) for 48 h, and MUC1 expression was detected using qPCR analysis. b 3AO and Caov3 cells were transfected with a STON2-specific siRNA or siNC for 24 h, followed by treatment with Aza (15 μM for 48 h). MUC1 expression was detected using qPCR analysis. c Schematic illustration of the MUC1 promoter embedded in one CpG-rich region (− 2366 to − 2327 bp). d 3AO and Caov3 cells were transfected with a STON2-specific siRNA or control for 24 h, followed by pyrosequencing to assess the DNA methylation status of MUC1 (three coupled independent samples). Each column represents the relative average DNA methylation level at one CpG site compared to the control group (see also raw pyrograms of representative experiments in Additional file 5: Figure S2). e-g 3AO and Caov3 cells were transfected with a STON2-specific siRNA for 72 h. DNMT1 and MUC1 expression were detected by immunoblot analysis (e). DNMT1 expression was determined by qPCR analysis (f). DNMT1 and MUC1 expression was assayed by immunoblotting in the presence of MG132 (10 μM for 0 h, 6 h, 12 h) g. (h-i) 3AO and Caov3 cells were transfected with a DNMT1-specific siRNA for 72 h. MUC1 expression was detected using qPCR analysis (h). MUC1 expression was detected using immunoblot analysis (i). Data represents the mean ± S.E. of three independent experiments. The level of significance is indicated by *P < 0.05, **P < 0.01, ***P < 0.001, NS indicates P > 0.05