Low concentration of arsenic-induced aberrant mitosis in keratinocytes through E2F1 transcriptionally regulated Aurora-A

• Published in: Toxicological sciences 2013-03, Vol.132 (1), p.43-52
• Main Authors: Wu, Chin-Han, Tseng, Ya-Shih, Kao, Yu-Ting, Sheu, Hamm-Ming, Liu, Hsiao-Sheng
• Format: Article
• Language: English
• Subjects: Aurora Kinases; Blotting, Western; Cell Line; Chromatin Immunoprecipitation; Dose-Response Relationship, Drug; E2F1 Transcription Factor - physiology; Fluorescent Antibody Technique; Humans; Immunohistochemistry; Keratinocytes - cytology; Keratinocytes - drug effects; Mitosis - drug effects; Promoter Regions, Genetic; Protein-Serine-Threonine Kinases - genetics; Reverse Transcriptase Polymerase Chain Reaction; Skin Neoplasms - metabolism; Transcription, Genetic - physiology; Tumor Suppressor Protein p53 - metabolism
• ISSN: 1096-6080; 1096-0929
• DOI: 10.1093/toxsci/kfs322

Chronic exposure to low-concentration arsenic promotes cell proliferation and carcinogenesis both in vitro and in vivo. Centrosome amplification, the major cause of chromosome instability, occurs frequently in cancers. Aurora-A is a mitotic kinase and causes centrosome amplification and chromosome instability when overexpressed. Our previous study revealed that low-concentration arsenic induces Aurora-A overexpression in immortalized bladder cells. In this study, we hypothesized that low-concentration arsenic induces aberrant mitosis in keratinocytes due to Aurora-A overexpression. The specimen of Bowen's disease (BD) and squamous cell carcinoma obtained from arseniasis-endemic areas in Taiwan showed Aurora-A overexpression. The mRNA/protein levels and kinase activity of Aurora-A were increased in immortalized keratinocyte HaCaT cells after arsenic treatment at low concentration (< 1µM). Aberrant spindles, multiple centrosomes, and multinucleated cells were detected under fluorescent microscopy in HaCaT cells after arsenic treatment. These findings were associated with increased expression of Aurora-A. We further revealed that Aurora-A was regulated by arsenic-induced transcriptional factor E2F1 as demonstrated by chromosome immunoprecipitation, promoter activity, and small interfering RNA assays. Finally, in arsenic-treated HaCaT cells and in BD, a significant increase of dysfunctional p53 was found, and this event correlated with the increase in expression of Aurora-A. Altogether, our data suggest that low concentration of arsenic induces activation of E2F1-Aurora-A axis and results in aberrant mitosis of keratinocytes. Overexpression of Aurora-A and dysfunctional p53 may act synergistically to trigger skin tumor formation. Our findings suggest that Aurora-A may be a potential target for the prevention and treatment of arsenic-related cancers.