Fig. 5

Exogenous expression of DNMT1 2 reversed the effect of UA on EZH protein expression and cell growth. a-b, H1299 and A549 cells were transfected with the control (pCMV6) or expression constructs of DNMT1 for 24 h before exposing the cells to UA for an additional 24 h. Afterwards, EZH2 and DNMT1 protein expression (a) and cell viability (b) were determined using Western blot and MTT assays. c, H1299 and A549 cells were transfected with the control (pCMV6) or expression constructs of EZH2 for 24 h before exposing the cells to UA for an additional 24 h. Afterwards, EZH2 and DNMT1 protein were determined using Western blot. d, H1299 and A549 cells were transfected with the control (pCMV6) or expression constructs of DNMT1 for 24 h before exposing the cells to UA for an additional 24 h. Afterwards, DNMT1, phosphor-SAPK/JNK were determined using Western blot. Values in bar graphs were given as the mean ± SD from three independent experiments performed in triplicate. *Indicates significant difference as compared to the untreated control group (P < 0.05). **Indicates significant difference from UA treated alone (P < 0.01). e, The diagram shows that UA inhibits NSCLC growth through SAPK/JNK-mediated inhibition of SP1; this in turn results in inhibition of DNMT1 and EZH2. Overexpression of DNMT1 diminishes UA-reduced EZH2 protein expression. The negative feedback regulation of SAPK/JNK signaling by SP1 and DNMT1 attenuates, while the reciprocal interaction of EZH2 and DNMT1 contributes the overall effect of UA in inhibition of lung cancer cell growth