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Inhibition of GGTase-I and FTase disrupts cytoskeletal organization of human PC-3 prostate cancer cells

Authors

  • Sanna S. Virtanen,

    Corresponding author
    1. Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FI20520 Turku, Finland
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  • Jouko Sandholm,

    1. Cell Imaging Core, Turku Centre for Biotechnology, University of Turku and bo Akademi University, Tykistkatu 6B, 5th floor, FI20521 Turku, Finland
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  • Gennady Yegutkin,

    1. MediCity Research Laboratory, University of Turku, Tykistkatu 6A, 4th floor, FI20520 Turku, Finland
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  • Kalervo H. Väänänen,

    1. Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FI20520 Turku, Finland
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  • Pirkko L. Härkönen

    1. Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FI20520 Turku, Finland
    2. Department of Laboratory Medicine, MAS University Hospital, Lund University, CRC, Entrance 72, Plan 10 20502 Malm, Sweden
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email sasovi@utu.fi

Abstract

The mevalonate synthesis pathway produces intermediates for isoprenylation of small GTPases, which are involved in the regulation of actin cytoskeleton and cell motility. Here, we investigated the role of the prenylation transferases in the regulation of the cytoskeletal organization and motility of PC-3 prostate cancer cells. This was done by using FTI-277, GGTI-298 or NE-10790, the specific inhibitors of FTase (farnesyltransferase), GGTase (geranylgeranyltransferase)-I and -II, respectively. Treatment of PC-3 cells with GGTI-298 and FTI-277 inhibited migration and invasion in a time- and dose-dependent manner. This was associated with disruption of F-actin organization and decreased recovery of GFP–actin. Immunoblot analysis of various cytoskeleton-associated proteins showed that the most striking change in GGTI-298- and FTI-277-treated cells was a markedly decreased level of total and phosphorylated cofilin, whereas the level of cofilin mRNA was not decreased. The treatment of PC-3 cells with GGTI-298 also affected the dynamics of GFP–paxillin and decreased the levels of total and phosphorylated paxillin. The levels of phosphorylated FAK (focal adhesion kinase) and PAK (p-21-associated kinase)-2 were also lowered by GGTI-298, but levels of paxillin or FAK mRNAs were not affected. In addition, GGTI-298 had a minor effect on the activity of MMP-9. RNAi knockdown of GGTase-Iβ inhibited invasion, disrupted F-actin organization and decreased the level of cofilin in PC-3 cells. NE-10790 did not have any effect on PC-3 prostate cancer cell motility or on the organization of the cytoskeleton. In conclusion, our results demonstrate the involvement of GGTase-I- and FTase-catalysed prenylation reactions in the regulation of cytoskeletal integrity and motility of prostate cancer cells and suggest them as interesting drug targets for development of inhibitors of prostate cancer metastasis.

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