Cancer cells frequently express genes normally active in male germ cells. ATAD2 is one of them encoding a conserved factor harbouring an AAA type ATPase domain and a bromodomain. We show here that ATAD2 is highly expressed in testis as well as in many cancers of different origins and that its high expression is a strong predictor of rapid mortality in lung and breast cancers. These observations suggest that ATAD2 acts on upstream and basic cellular processes to enhance oncogenesis in a variety of unrelated cell types. Accordingly, our functional studies show that ATAD2 controls chromatin dynamics, genome transcriptional activities and apoptotic cell response. We could also highlight some of the important intrinsic properties of its two regulatory domains, including a functional cross-talk between the AAA ATPase domain and the bromodomain. Altogether, these data indicate that ATAD2 overexpression in somatic cells, by acting on basic properties of chromatin, may contribute to malignant transformation.