Abstract Recent experiments have showed that it is possible to use pharmacological agents that inactivate oncogenes to treat at least some types of human malignancies. However, the development of molecular targeted therapy in oral squamous cell carcinoma (OSCC) is lagging behind compare to other cancers. In this study, we attempted to identify an appropriate target molecule and to determine whether targeting such a molecule is plausible therapeutic approach for the treatment of patients with OSCC. We determined the gene expression profiles of 9 human OSCC cell lines and non-neoplastic keratinocyte cell line by microarray analysis, and then identified Aurora kinase A (AURKA) as a cancer-related gene. AURKA has been shown to be related to the progression, survival, histological differentiation, and metastasis in various tumors. We revealed the overexpression of AURKA mRNA and protein in human OSCC cell lines and tissues. To clarify the function of AURKA in the cell proliferation of OSCC cells, we investigated the effect of small interfering RNA (siRNA) specific for AURKA (siAURKA) and MLN8237, an AURKA selective inhibitor, on the growth of human OSCC cells in vitro and in vivo. All siAURKAs almost completely suppressed the expression of AURKA protein, and significantly inhibited the growth of these cells compared to non-targeting siRNA. MLN8237 also markedly reduced the growth rate of human OSCC cells. Next, we assessed the growth inhibitory effect of siAURKA and MLN8237 using mouse model. Synthetic siAURKA/atelocollagen complexes (40 μM) were administrated into mouse tail vain every 3 days, and MLN8237 (20 mg/kg) was received orally for 14 consecutive days. We found both siAURKA and MLN8237 significantly reduced the size of subcutaneously xenografted OSCC tumors. To confirm the usefulness of targeting AURKA in OSCC, we attempted to culture the resected tumor tissues from 3 patients with OSCC and obtained primary cultured cells. Knockdown of AURKA expression and MLN8237 induced the growth inhibition of OSCC primary cultured cells. Furthermore, the expression of AURKA mRNA in OSCC tissues resected from patients was examined. In 37 of 50 primary OSCC tissues, the expression levels of AURKA mRNA were more than 2-fold increase compared to normal oral mucosa tissues, and notably we found significant association between AURKA mRNA expression levels and histological differentiation and lymph node metastasis. These results suggest that AURKA plays a critical role in the growth of human OSCC cells, and targeting AURKA appears to be a potentially useful therapeutic approach for patients with OSCC. Citation Format: Hiroshi Tanaka, Koh-ichi Nakashiro, Kazuki Iwamoto, Norihiko Tokuzen, Yohei Fujita, Rikimaru Shirakawa, Ryota Oka, Hiroyuki Goda, Hiroyuki Hamakawa. Aurora kinase A as a novel therapeutic target in oral squamous cell carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3003. doi:10.1158/1538-7445.AM2013-3003