Abstract: Objective To investigate the pathological significance of DEK-AP-2α interaction in HER2 overexpression and breast tumorigenesis. Methods The protein level of DEK，AP-2α and HER-2 in breast tumor tissues was detected by Western blot. The interaction of DEK and AP-2α in MDA-MB-453 mammary cancer cells was detected by immuno-coprecipitation. Furthermore the impact of DEK and AP-2α on HER2 expression was investigated by siRNA in MDA-MB-453 mammary cancer cells followed by semi-quantitive RT-PCR and Western blot. Resluts A correlation between DEK, AP-2α and HER2 levels in breast cancer tissues were observed. The interaction between DEK and AP-2α in MDA-MB-453 cells was verified by co-immunoprecipitation assay. Depletion of DEK and AP-2α in MDA-MB-453 cell by siRNA cooperatively repressed HER2 expression at both the mRNA and protein levels. Conclution This study provides oncogene DEK cooperates with AP-2α transcriptional factor to promote HER2 overexpression in breast cancer.

Key words: DEK, AP-2α, HER2, breast cancer