Abstract 476: Overexpression and function of CDCA5 in oral squamous cell carcinoma
Authors: Tokuzen Norihiko , Nakashiro Koh-ichi , Tanaka Hiroshi , Fujita Yohei , Iwamoto Kazuki , Hamakawa Hiroyuki 
Published: May 2015

Abstract
Molecular target drugs are used in the treatment of various malignant tumors. However, the development of molecular targeted therapy for oral squamous cell carcinoma (OSCC) is lagging behind other cancers. In this study, we have attempted to identify an appropriate molecular target for treatment of patients with OSCC. We determined the gene expression profiles of human 9 OSCC cell lines and an immortalized non-neoplastic human keratinocyte cell line by microarray analysis, and then found cell division cycle associated 5 (CDCA5) as one of genes which were commonly overexpressed in OSCC cells. CDCA5 was initially identified as substrate of anaphase-promoting complex and as a regulator of sister chromatid cohesion in HeLa. In addition, it has been reported that CDCA5 plays a critical role in human lung carcinogenesis. However, function of CDCA5 in OSCC remains still unknown. First, we confirmed the overexpression of CDCA5 in 5 human OSCC cells by quantitative RT-PCR (qRT-PCR) and Western blotting. The expression levels of CDCA5 mRNA and protein were markedly elevated in all human OSCC cell lines compared to a non-neoplastic human epithelial cell line. Next, we examined the effect of synthetic small interfering RNAs specific for CDCA5 (siCDCA5) on the growth of human OSCC cells. RNAi effect of siCDCA5 was confirmed by Western blotting. Transfection of siCDCA5 suppressed the expression of its target protein in all types of cells. The growth inhibitory effect of siCDCA5 in OSCC cells was evaluated by WST-8 assay. Knockdown of CDCA5 significantly inhibited the growth of OSCC cells in vitro. Subsequently, we analyzed the influence of siCDCA5 on cell cycle by flow cytometry. Suppression of CDCA5 resulted in the decrease in percentage of cells in G0/G1 phase and increase in G2 phase. This indicated that the anti-proliferative effect of siCDCA5 was due to G2 arrest. Furthermore, we investigated the clinical significance of CDCA5 expression in OSCC. The expression of CDCA5 mRNA in tumor and adjacent normal tissues derived from the patient with OSCC was examined by qRT-PCR. Expression levels of CDCA5 mRNA in the OSCC tissues were significantly higher than in normal tissues. We also examined the expression of CDCA5 protein in 80 OSCC cases by immunohistochemistry with anti-CDCA5 antibodies. Tissue expression of CDCA5 was divided into high or low group at 50% stained tumor cells, resulting in 36 cases as high expression and 44 cases as low expression. We then examined the association of CDCA5 expression with various clinicopathological parameters of OSCC patients, and found a significant association between CDCA5 expression levels and pathological staging, metastasis, and recurrence. These results suggest that CDCA5 functions as a critical gene supporting the growth of human OSCC cells and targeting CDCA5 appears a useful therapeutic strategy for the patients with OSCC.
Citation Format: Norihiko Tokuzen, Koh-ichi Nakashiro, Hiroshi Tanaka, Yohei Fujita, Kazuki Iwamoto, Hiroyuki Hamakawa. Overexpression and function of CDCA5 in oral squamous cell carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 476. doi:10.1158/1538-7445.AM2014-476