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. 2021 Feb 18;40(11):1974–1987. doi: 10.1038/s41388-021-01682-z

Fig. 5. Metformin downregulates CHRNA7 by enhancing its promoter DNA hypermethylation to repress ESCC CIC properties.

Fig. 5

a Cell survival curves of NE2, adherent- or sphere-cultured TE1 cells treated with metformin at the indicated concentrations. b, c The mRNA and protein levels of CHRNA7 in KYSE270 and TE1 cells treated with vehicle, metformin (Met) for 48 h, Met for 72 h, nicotine (Nic) for 24 h, Met for 48 h followed by the combination of Met and Nic for 24 h. GAPDH was used as an internal control. d Representative images of spheres formed by TE1 cells transfected with CHRNA7 or vector treated with or without metformin. e The methylation level of CHRNA7 in TE1 cells treated with vehicle, Nic, Nic, and Met. f The methylation status on ten CpG islands in TE1 cells treated with vehicle, Nic, Nic, and Met. Data are shown as the means of three independent experiments or representative data. Error bars indicate SD. *P < 0.05, **P < 0.01, ***P < 0.001 by Student’s t-test or one-way ANOVA with post hoc intergroup comparisons.