Frequent amplification of ORAOV1 gene in esophageal squamous cell cancer promotes an aggressive phenotype via proline metabolism and ROS production
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Yosuke Togashi1, Tokuzo Arao1, Hiroaki Kato2, Kazuko Matsumoto1, Masato Terashima1, Hidetoshi Hayashi1, Marco A de Velasco1, Yoshihiko Fujita1, Hideharu Kimura1, Takushi Yasuda2, Hitoshi Shiozaki2, and Kazuto Nishio1
1 Department of Genome Biology, Kinki University Faculty of Medicine, Osaka-Sayama, Osaka, Japan
2 Department of Surgery, Kinki University Faculty of Medicine, Osaka-Sayama, Osaka, Japan
Kazuto Nishio, email:
Keywords: oral cancer overexpressed 1, esophageal squamous cell cancer, pyrroline-5-carboxylate reductase, proline metabolism, reactive oxygen species.
Received: October 31, 2013 Accepted: December 30, 2013 Published: December 30, 2013
Chromosomal band 11q13 seems to be one of the most frequently amplified lesions in human cancer, including esophageal squamous cell cancer (ESCC). The oral cancer overexpressed 1 (ORAOV1) gene has been identified within this region, but its detailed biological function in human ESCC remains largely unclear. In our clinical samples of stage III ESCC, ORAOV1 amplification was observed in 49 of 94 cases (53%). ORAOV1 amplification was significantly associated with a poorly differentiated histology and tumors located in the upper or middle esophagus. Patients with ORAOV1 amplification tended to have a shorter survival period, although the difference was not significant. To investigate the function of ORAOV1, we created ORAOV1-overexpressed ESCC cell lines that exhibited increased cellular proliferation and colony formation, compared with in vitro controls. In vivo, ORAOV1-overexpressed cells exhibited a significantly increased tumorigenicity and a significantly larger tumor volume and poorer differentiation than controls. The peptide mass fingerprinting technique demonstrated that ORAOV1 bound to pyrroline-5-carboxylate reductase (PYCR), which is associated with proline metabolism and reactive oxygen species (ROS) production. Then, ORAOV1-overexpressed cell lines were resistant to stress treatment, which was cancelled by PYCR-knockdown. In addition, the ORAOV1-overexpressed cell line had a higher intracellular proline concentration and a lower ROS level. Our findings indicate that the ORAOV1 gene is frequently amplified in ESCC, enhances tumorigenicity and tumor growth, and is associated with a poorly differentiated tumor histology via proline metabolism and ROS production. ORAOV1 could be a novel target for the treatment of ESCC.
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