Overexpression of the cellular DEK protein promotes epithelial transformation in vitro and in vivo

High levels of expression of the human DEK gene have been correlated with numerous human malignancies. Intracellular DEK functions have been described in vitro and include DNA supercoiling, DNA replication, RNA splicing, and transcription. We have demonstrated DEK also suppresses cellular senescence, apoptosis and differentiation, thus promoting cell growth and survival in monolayer and organotypic epithelial raft models. Such functions are likely to contribute to cancer, but direct evidence to implicate DEK as an oncogene has remained elusive. Here we show that in line with an early role in tumorigenesis, murine papilloma formation in a classical chemical carcinogenesis model was reduced in DEK knockout mice. Additionally, HPV E6/E7, hRas and DEK cooperated in the transformation of keratinocytes in soft agar and xenograft establishment, thus also implicating DEK in tumor promotion at later stages. Finally, adenoviral DEK depletion via shRNA expression resulted in cell death in human tumor cells in vitro and in vivo, but did not significantly affect differentiated epithelial cells. Taken together, our data uncover oncogenic DEK activities as postulated from its frequent upregulation in human malignancies, and suggest that the targeted suppression of DEK may become a strategic approach to the treatment of cancer.