The suppression of Aurora-A/STK15/BTAK expression enhances chemosensitivity to docetaxel in human esophageal squamous cell carcinoma

Abstract

Purpose: We previously reported that the expression of Aurora-A was frequently up-regulated in human esophageal squamous cell carcinoma (ESCC) tissues as well as cell lines and the up-regulation contributed to a poor prognosis. In this study, we assessed the possibility of Aurora-A suppression as a therapeutic target for ESCC using ESCC cell lines. Experimental Design: We established subclones using vector-based short hairpin RNA (shRNA). Then, we investigated the effect of Aurora-A suppression on proliferation and cell cycle changes in vitro. Next, chemosensitivity against docetaxel was investigated by tetrazolium salt - based proliferation assay (WSTassay) and cell number determinations, and furthermore, the type of cell death induced by docetaxel was analyzed by flow cytometry. Finally, to examine the effect of Aurora-A shRNA on proliferation and chemosensitivity against docetaxel in vivo, a s.c. tumor formation assay in nude mice was done. Results: We established two genetically different stable cell lines (510 A and 1440 A) in which levels of Aurora-A were reduced. Cell growth was inhibited by 38.7% in 510 A and by 24.3% in 1440 A in vitro compared with empty vector-transfected controls (510 m and 1440 m), and this growth inhibition was mediated through G2-M arrest as confirmed by flow cytometry. Next, in a WST assay, the IC50 for Aurora-A shRNA-transfected cells was lower than that of empty vector-transfected cells (510 A, 2.7 × 10-7 mol/L; 510 m, 4.8 × 10-7 mol/L; 1440 A, 2.6 × 10-7 mol/L; 1440 m, 4.9 × 10 -7 mol/L). In addition, 0.3 nmol/L docetaxel induced a notable level of apoptosis in Aurora-A shRNA-transfected cells compared with empty vector-transfected cells. In the assay of s.c. tumors in nude mice, tumor growth in 510 A was inhibited by 36.1% compared with that in 510 m, and in tumors treated with docetaxel, the suppression of Aurora-A resulted in 44.0% tumor growth suppression in vivo. Conclusions: These results indicated that Aurora-A might play an important role in chemosensitivity to docetaxel, and the suppression of its expression might be a potential therapeutic target for ESCC. © 2007 American Association for Cancer Research.