Evaluation of cervical cone biopsies for coexpression of p16INK4a and Ki-67 in epithelial cells

Authors

  • Miriam Reuschenbach,

    Corresponding author
    1. Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany and Clinical Cooperation Unit Applied Tumor Biology, German Cancer Research Center, Heidelberg, Germany
    • Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany
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    • Tel.: +49-6221-565210, Fax: +49-6221-565981

    • M.R. and M.S. contributed equally to this work

  • Mirjam Seiz,

    1. Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany and Clinical Cooperation Unit Applied Tumor Biology, German Cancer Research Center, Heidelberg, Germany
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    • M.R. and M.S. contributed equally to this work

  • Christina von Knebel Doeberitz,

    1. Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany and Clinical Cooperation Unit Applied Tumor Biology, German Cancer Research Center, Heidelberg, Germany
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  • Svetlana Vinokurova,

    1. Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany and Clinical Cooperation Unit Applied Tumor Biology, German Cancer Research Center, Heidelberg, Germany
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  • Alexander Duwe,

    1. mtm Laboratories, Heidelberg, Germany
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  • Ruediger Ridder,

    1. mtm Laboratories, Heidelberg, Germany
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  • Heike Sartor,

    1. Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany and Clinical Cooperation Unit Applied Tumor Biology, German Cancer Research Center, Heidelberg, Germany
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  • Friedrich Kommoss,

    1. Institute of Pathology, Mannheim, Germany
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  • Dietmar Schmidt,

    1. Institute of Pathology, Mannheim, Germany
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  • Magnus von Knebel Doeberitz

    1. Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany and Clinical Cooperation Unit Applied Tumor Biology, German Cancer Research Center, Heidelberg, Germany
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  • Conflict of interest: AD and RR are employees of mtm Laboratories that develops and markets products related to this study. DS has been a temporary clinical advisor and speaker for mtm Laboratories, and MvKD is a member of the supervisory board of mtm Laboratories. RR, CvKD and MvKD declare a financial interest in mtm Laboratories. All other authors disclose no potential conflict of interest.

Abstract

Diffuse overexpression of p16INK4a in basal and parabasal cells of cervical epithelium is a hallmark of human papillomavirus-mediated transformation. Focal p16INK4a expression is occasionally observed in nondysplastic epithelium. In normal cells, expression of p16INK4a triggers cell cycle arrest. However, cells undergoing transformation in intraepithelial lesions actively proliferate. To prove that the different expression patterns of p16INK4a, i.e., focal versus diffuse, reflect biologically different entities, we hypothesized that p16INK4a-positive cells in epithelia displaying focal p16INK4a expression pattern do not coexpress proliferation-associated Ki-67 protein, while p16INK4a-positive cells in lesions with diffuse p16INK4a expression may do. A total of 138 cervical cone biopsies were stained for the expression of p16INK4a and Ki-67 using a primary antibody cocktail. All metaplastic lesions (n = 21) displayed focal staining for p16INK4a, and in all of these lesions p16INK4a-positive cells were found to be negative for Ki-67 expression. Diffuse expression of p16INK4a was observed in 12/21 (57.1%) cervical intraepithelial neoplasia (CIN) 1 lesions, all of them simultaneously showed Ki-67 immunoreactivity in a large proportion of p16INK4a-positive cells. Seventeen of 23 (73.9%) CIN2 lesions and all 27 (100%) CIN3/carcinoma in situ (CIS) as well as all 46 (100%) carcinoma cases displayed diffuse and combined expression of p16INK4a and Ki-67. Coexpression of Ki-67 and p16INK4a in the same cell is entirely restricted to cervical lesions displaying diffuse p16INK4a expression, whereas in lesions with focal p16INK4a expression, p16INK4a-expressing cells are negative for Ki-67. Thus, diffuse expression of p16INK4a reflects lesions with proliferation-competent cells, while p16INK4a-expressing cells associated with focal expression patterns are cell cycle arrested.

Ancillary