Fig. 6: GADD45α negatively regulates cytoplasmic localization of APE1 in cervical cancer cells.

a Cytoplasmic APE levels were increased, while nuclear APE1 levels were decreased in HeLa-XR cells compared to HeLa cells. Cytoplasmic and nuclear proteins were isolated from indicated cells and the indicated proteins were detected using western blot. b APE1 expression and subcellular localization were detected using immunofluorescence in HeLa-XR and HeLa cells. c Cytoplasmic APE1 level was increased, while nuclear APE1 level was decreased in HeLa cells in response to silencing of GADD45α. Cytoplasmic and nuclear proteins were isolated from indicated cells after 72 h transfection, and the indicated proteins were detected using western blot. d APE1 expression and subcellular localization were detected using immunofluorescence in HeLa cells transfected with shGADD45α plasmid or vector. e Cytoplasmic APE1 levels were decreased, while nuclear APE1 levels were increased in HeLa-XR cells in response to GADD45α overexpression. Cytoplasmic and nuclear proteins were isolated from indicated cells after 72 h transfection, and the indicated proteins were detected using Western blot. f APE1 expression and subcellular localization were detected using immunofluorescence in HeLa-XR cells that overexpressed GADD45α plasmid or vector. g GADD45α expression is negatively correlated with radiation sensitivity and cytoplasmic APE1 expression levels in specimens from cervical cancer patients. Expression of GADD45α and APE1 was measured using immunohistochemistry. Each immunofluorescence experiment was repeated three times. *p < 0.05; **p < 0.01. GR good response, PR poor response