Akt2 regulates all Akt isoforms and promotes resistance to hypoxia through induction of miR-21 upon oxygen deprivation.

ABSTRACT: The growth and survival of tumor cells in an unfavorable hypoxic environment depend upon their adaptability. Here, we show that both normal and tumor cells expressing the protein kinase Akt2 are more resistant to hypoxia than cells expressing Akt1 or Akt3. This is due to the differential regulation of microRNA (miR) 21, which is upregulated by hypoxia only in Akt2-expressing cells. By upregulating miR-21 upon oxygen deprivation, Akt2 downregulates PTEN and activates all three Akt isoforms. miR-21 also targets PDCD4 and Sprouty 1 (Spry1), and the combined downregulation of these proteins with PTEN is sufficient to confer resistance to hypoxia. Furthermore, the miR-21 induction by Akt2 during hypoxia depends upon the binding of NF-κB, cAMP responsive element-binding protein (CREB), and CBP/p

SUBMITTER: Polytarchou C 

PROVIDER: S-EPMC3129420 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature