title: Low concentration of arsenic-induced aberrant mitosis in keratinocytes through E2F1 transcriptionally regulated Aurora-A.
abstract: 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.
authors.affiliation: The Institute of Basic Medical Science, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chin-Han
authors.initials: CH
authors.lastname: Wu
authors.forename: Ya-Shih
authors.initials: YS
authors.lastname: Tseng
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Kao
authors.forename: Hamm-Ming
authors.initials: HM
authors.lastname: Sheu
authors.forename: Hsiao-Sheng
authors.initials: HS
authors.lastname: Liu
mesh_terms: D064127:Aurora Kinases; D015153:Blotting, Western; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D004305:Dose-Response Relationship, Drug; D050687:E2F1 Transcription Factor / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects*; D008938:Mitosis / Q000187:drug effects*; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012878:Skin Neoplasms / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D016159:Tumor Suppressor Protein p53; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases