• Open Access

Essential contribution of Ets-1 to constitutive Pim-3 expression in human pancreatic cancer cells

Authors

  • Ying-Yi Li,

    1. Division of Molecular Bioregulation, Cancer Research Institute, Kanazawa University, 13-1 Takaramahi, Kanazawa 920-0934, Japan and
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  • Yu Wu,

    1. Division of Molecular Bioregulation, Cancer Research Institute, Kanazawa University, 13-1 Takaramahi, Kanazawa 920-0934, Japan and
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  • Koichi Tsuneyama,

    1. Department of Pathology and 21st Century Center of Excellence Program, Toyama University Faculty of Medicine, 2630 Sugitani, Toyama 930-0194, Japan
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  • Tomohisa Baba,

    1. Division of Molecular Bioregulation, Cancer Research Institute, Kanazawa University, 13-1 Takaramahi, Kanazawa 920-0934, Japan and
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  • Naofumi Mukaida

    Corresponding author
    1. Division of Molecular Bioregulation, Cancer Research Institute, Kanazawa University, 13-1 Takaramahi, Kanazawa 920-0934, Japan and
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To whom correspondence should be addressed. E-mail: naofumim@kenroku.kanazawa-u.ac.jp.

Abstract

We previously demonstrated that the proto-oncogene Pim-3 with serine/threonine kinase activity was aberrantly expressed in cancer cells but not in the normal cells of the pancreas. In order to elucidate the molecular mechanism underlying aberrant Pim-3 expression in pancreatic cancer cells, we constructed luciferase expression vectors linked to 5′-flanking deletion mutants of the human Pim-3 gene and transfected human pancreatic cancer cells with the resultant vectors. The region up to –264 bp was essential for constitutive Pim-3 gene expression, and the mutation in the Ets-1 binding site (between –216 and –211 bp) reduced luciferase activities. Moreover, Ets-1 mRNA and protein were constitutively expressed together with Pim-3 in human pancreatic cancer cell lines. Chromatin immunoprecipitation assay demonstrated constitutive binding of Ets-1 to the 5′-flanking region of human Pim-3 gene between –249 and –183 bp. Pim-3 promoter activity and its protein expression were induced by transfection with wild type-Ets-1 and were reduced by transfection with dominant negative-Ets-1 or Ets-1 small-interfering RNA (siRNA). Furthermore, dominant negative-Ets-1 and Ets-1 siRNA reduced the amount of Bad phosphorylated at its Ser112 and induced apoptosis, when they were transfected into human pancreatic cancer cells. Finally, Pim-3 cDNA transfection reversed Ets-1 siRNA-induced increase in apoptosis and decrease in Bad phosphorylation at its Ser112. These observations would indicate that the transcription factor Ets-1 can induce aberrant Pim-3 expression and subsequently prevent apoptosis in human pancreatic cancer cells. (Cancer Sci 2009; 100: 396–404)

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