Fig. 6

DNMT1 methylated KLF4 to inhibit its expression. a Expression of KLF4 in LAD tissues (n = 42) and paracancerous tissues (n = 42) by RT-qPCR, normalized to GAPDH. b Immunohistochemical detection of KLF4 in LAD tissues (n = 42) and paracancerous tissues (n = 42) (200 ×). c KLF4 mRNA expression in HBE cells and 5 LAD cell lines by RT-qPCR, normalized to GAPDH. d KLF4 protein expression in HBE cells and 5 LAD cell lines by Western blot analysis, normalized to GAPDH. e Silencing efficiency of DNMT1 by Western blot analysis, normalized to GAPDH. f ChIP test to detect the binding of DNMT1 to the KLF4 promoter region. g Dual luciferase reporter gene assay to detect the binding relation between DNMT1 and KLF4. h MSP to detect the effect of the methylation level of the KLF4 promoter region. i Western blot analysis of DNMT1 and KLF4 protein expression, normalized to GAPDH. * p < 0.05 vs. the paracancerous tissues (panels a and b), HBE cells (panels c and d), cells transfected with sh-NC (panels e, i), DNA-protein complex fragments incubated with IgG (panel f), or cells transfected with sh-NC and KLF4-WT (panel g). All experiments were done in triplicate