ANTISENSE INHIBITION OF THE 27 kDa HEAT SHOCK PROTEIN PRODUCTION AFFECTS GROWTH RATE AND CYTOSKELETAL ORGANIZATION IN MCF-7 CELLS

Authors

  • N. MAIRESSE,

    1. Biology Unit, Institute of Interdisciplinary Research, Free University of Brussels, Campus Erasme, Bldg C, 808 Route de Lennik, B-1070, Brussels, Belgium
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  • S. HORMAN,

    1. Biology Unit, Institute of Interdisciplinary Research, Free University of Brussels, Campus Erasme, Bldg C, 808 Route de Lennik, B-1070, Brussels, Belgium
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  • R. MOSSELMANS,

    1. Laboratory of Cytology and Experimental Oncology, School of Medicine, Free University of Brussels, Campus Erasme, Bldg C, 808 Route de Lennik, B-1070, Brussels, Belgium
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  • P. GALAND

    Corresponding author
    1. Biology Unit, Institute of Interdisciplinary Research, Free University of Brussels, Campus Erasme, Bldg C, 808 Route de Lennik, B-1070, Brussels, Belgium
    2. Laboratory of Cytology and Experimental Oncology, School of Medicine, Free University of Brussels, Campus Erasme, Bldg C, 808 Route de Lennik, B-1070, Brussels, Belgium
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To whom correspondence should be addressed.

Abstract

MCF-7 cells were co-transfected with the human HSP27 antisense cDNA and the neomycin resistance gene, included in the constitutive expression vector pSVL, and the phenotypical changes associated with decreased expression of the HSP27 protein were analysed. Three out of 10 neomycin-resistant clones obtained proliferated normally and showed a normal HSP27 content (Western blot). The seven other clones (designated as αHSP27 clones) were characterized by a dramatic growth inhibition associated with alterations in cellular morphology. Cells became progressively hypertrophied, exhibited lamellar protrusions and tended to lose contact with each other. They also acquired characteristics of secretory cells, namely the presence of numerous refractile granules and secretory canaliculi. Among the αHSP27 clones, two were immunocytochemically analysed for HSP27 content. Both clones were immunonegative for HSP27, contrary to parental cells and neo transfectants. Actin immunostaining in one of these HSP27 negative clones revealed that microfilament organization changed from diffuse to punctate distribution. Our data support the current concept of a role for HSP27 in cell growth and differentiation and further suggests that this might occur through a control on actin polymerization-depolymerization.

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