title: Bi-directional regulation between tyrosine kinase Etk/BMX and tumor suppressor p53 in response to DNA damage.
abstract: Etk/Bmx, a member of the Tec family of nonreceptor tyrosine kinases, has been implicated in the regulation of various cellular processes including proliferation, differentiation, motility, and apoptosis. Here, we report the identification of Tec family kinases as the potential interacting proteins of the tumor suppressor p53 by an Src homology 3 domain array screening. Etk is physically associated with p53 through its Src homology 3 domain and the proline-rich domain of p53. Induction of p53 expression by DNA damage inhibits Etk activity in several cell types. Down-regulation of Etk expression by a specific small interfering RNA sensitizes prostate cancer cells to doxorubicin-induced apoptosis, suggesting that inhibition of Etk activity is required for apoptosis in response to DNA damage. We also show that Etk primarily interacts with p53 in the cytoplasm and that such interaction leads to bidirectional inhibition of the activities of both proteins. Overexpression of Etk in prostate cancer cells results in inhibition of p53 transcriptional activity and its interaction with the mitochondrial protein BAK and confers the resistance to doxorubicin. Therefore, we propose that the stoichiometry between p53 and the Tec family kinases in a given cell type may determine its sensitivity to chemotherapeutic drugs.
authors.affiliation: Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Tianyun
authors.initials: T
authors.lastname: Jiang
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Guo
authors.forename: Bojie
authors.initials: B
authors.lastname: Dai
authors.forename: Miyoung
authors.initials: M
authors.lastname: Kang
authors.forename: David K
authors.initials: DK
authors.lastname: Ann
authors.forename: Hsing-Jien
authors.initials: HJ
authors.lastname: Kung
authors.forename: Yun
authors.initials: Y
authors.lastname: Qiu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D019556:COS Cells; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D004249:DNA Damage / Q000502:physiology*; D015536:Down-Regulation / Q000502:physiology; D006801:Humans; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53; C492367:BMX protein, human; D011505:Protein-Tyrosine Kinases