HDM2 regulation by AURKA promotes cell survival in gastric cancer.
OBJECTIVE
Suppression of P53 (tumor protein 53) transcriptional function mediates poor therapeutic response in patients with cancer. Aurora kinase A (AURKA) and human double minute 2 (HDM2) are negative regulators of P53. Herein, we examined the role of AURKA in regulating HDM2 and its subsequent effects on P53 apoptotic function in gastric cancer.


METHODS
Primary tumors and in vitro gastric cancer cell models with overexpression or knockdown of AURKA were used. The role of AURKA in regulating HDM2 and cell survival coupled with P53 expression and activity were investigated.


RESULTS
Overexpression of AURKA enhanced the HDM2 protein level; conversely, knockdown of endogenous AURKA decreased expression of HDM2 in AGS and SNU-1 cells. Dual co-immunoprecipitation assay data indicated that AURKA was associated with HDM2 in a protein complex. The in vitro kinase assay using recombinant AURKA and HDM2 proteins followed by co-immunoprecipitation revealed that AURKA directly interacts and phosphorylates HDM2 protein in vitro. The activation of HDM2 by AURKA led to induction of P53 ubiquitination and attenuation of cisplatin-induced activation of P53 in gastric cancer cells. Inhibition of AURKA using an investigational small-molecule specific inhibitor, alisertib, decreased the HDM2 protein level and induced P53 transcriptional activity. These effects markedly decreased cell survival in vitro and xenograft tumor growth in vivo. Notably, analysis of immunohistochemistry on tissue microarrays revealed significant overexpression of AURKA and HDM2 in human gastric cancer samples (P < 0.05).


CONCLUSIONS
Collectively, our novel findings indicate that AURKA promotes tumor growth and cell survival through regulation of HDM2-induced ubiquitination and inhibition of P53. Clin Cancer Res; 20(1); 76-86. ©2013 AACR.
Authors' Affiliations: Departments of Surgery and Cancer Biology, Vanderbilt University Medical Center; Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee; Translational Medicine, Millennium Pharmaceuticals, Inc., Cambridge, Massachusetts; and Department of Pharmacology, Arnold and Marie Schwartz College of Pharmacy and Health Sciences, Long Island University, New York.
Vikas
V
Sehdev
Ahmed
A
Katsha
Janet
J
Arras
Dunfa
D
Peng
Mohammed
M
Soutto
Jeffrey
J
Ecsedy
Alexander
A
Zaika
Abbes
A
Belkhiri
Wael
W
El-Rifai
D000230:Adenocarcinoma / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D064096:Aurora Kinase A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001381:Azepines / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D010766:Phosphorylation; D059748:Proteolysis; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D054875:Ubiquitination; D015854:Up-Regulation; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D001381:Azepines; C550258:MLN 8237; D011743:Pyrimidines; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C576917:AURKA protein, human; D064096:Aurora Kinase A