title: Delta Np63 alpha expression is regulated by the phosphoinositide 3-kinase pathway.
abstract: p63 is a homologue of p53 that functions to maintain progenitor cell populations in stratified epithelia. Delta Np63 alpha is overexpressed in epithelial cancers and has been shown to have oncogenic properties. We have previously reported that inhibition of epidermal growth factor receptor signaling results in a decrease in Delta Np63 alpha expression. Here, we demonstrate Delta Np63 alpha is a target of the phosphoinositide-3-kinase (PI3K) pathway downstream of the epidermal growth factor receptor. Treatment of keratinocytes with epidermal growth factor results in an increase in Delta Np63 alpha expression at the mRNA level, which is abrogated by inhibition of PI3K but not mitogen-activated protein kinase signaling. Small interfering RNA-mediated knockdown of the p110 beta catalytic subunit of PI3K results in a decrease in Delta Np63 alpha protein levels in keratinocytes. The results presented herein suggest that regulation of Delta Np63 alpha expression by the PI3K pathway plays a critical role in the survival and proliferative capacity of squamous epithelia.
authors.affiliation: Department of Biochemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Barbieri
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Barton
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Pietenpol
mesh_terms: D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000473:pathology; D018307:Neoplasms, Squamous Cell / Q000209:etiology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D021122:Protein Subunits / Q000037:antagonists & inhibitors / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000494:pharmacology
chemical_list: D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D004815:Epidermal Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D021122:Protein Subunits; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C077214:L1Hs-encoded protein p40, human