Localization of human TACC3 to mitotic spindles is mediated by phosphorylation on Ser558 by Aurora A: a novel pharmacodynamic method for measuring Aurora A activity.
Aurora A is a serine/threonine protein kinase essential for normal mitotic progression. Aberrant increased expression of Aurora A, which occurs frequently in human cancers, results in abnormal mitoses leading to chromosome instability and possibly tumorigenesis. Consequently, Aurora A has received considerable attention as a potential target for anticancer therapeutic intervention. Aurora A coordinates several essential mitotic activities through phosphorylation of a variety of proteins, including TACC3, which modulates microtubule stabilization of the mitotic spindle. Recent studies identified a conserved serine in Xenopus (Ser(626)) and Drosophila (Ser(863)) TACC3 orthologues that is phosphorylated by Aurora A. We show that this conserved serine on human TACC3 (Ser(558)) is also phosphorylated by Aurora A. Moreover, phosphorylation of TACC3 by Aurora A in human cells is essential for its proper localization to centrosomes and proximal mitotic spindles. Inhibition of Aurora A with the selective small molecule inhibitor MLN8054 in cultured human tumor cells resulted in mislocalization of TACC3 away from mitotic spindles in a concentration-dependent manner. Furthermore, oral administration of MLN8054 to nude mice bearing HCT-116 human tumor xenografts caused a dose-dependent mislocalization of TACC3 away from spindle poles that correlated with tumor growth inhibition. As TACC3 localization to mitotic spindles depends on Aurora A-mediated phosphorylation, quantifying TACC3 mislocalization represents a novel pharmacodynamic approach for measuring Aurora A activity in cancer patients treated with inhibitors of Aurora A kinase.
LeRoy
Patrick J
PJ
Department of Molecular, Millennium Pharmaceuticals, Cambridge, Massachusetts 02139, USA.
Hunter
John J
JJ
Hoar
Kara M
KM
Burke
Krissy E
KE
Shinde
Vaishali
V
Ruan
Jason
J
Bowman
Douglas
D
Galvin
Katherine
K
Ecsedy
Jeffrey A
JA
D000595:Amino Acid Sequence; D000818:Animals; D064096:Aurora Kinase A; D064127:Aurora Kinases; D001552:Benzazepines / Q000494:pharmacology*; D018385:Centrosome / Q000378:metabolism; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
D001552:Benzazepines; C518940:MLN8054; D008869:Microtubule-Associated Proteins; C120551:TACC3 protein, human; D012694:Serine; C576918:Aurka protein, mouse; D064096:Aurora Kinase A; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases