Osteoblast-secreted factors enhance the expression of dysadherin and CCL2-dependent migration of renal carcinoma cells

Authors

  • Yvonne Schüler,

    1. Section for Transplantation Immunology and Immunohematology, Center for Medical Research, University of Tübingen, Germany
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    • The authors declare no competing financial interests.

  • Cornelia Lee-Thedieck,

    1. Department of New Materials and Biosystems, Max Planck Institute for Metals Research, Stuttgart, Germany
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    • The authors declare no competing financial interests.

  • Konstanze Geiger,

    1. Section for Transplantation Immunology and Immunohematology, Center for Medical Research, University of Tübingen, Germany
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  • Tatjana Kaiser,

    1. Department of Gynecology and Obstetrics, University of Tübingen, Germany
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  • Yoshinori Ino,

    1. Division of Pathology, National Cancer Center Research Institute, Tokyo, Japan
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  • Wilhelm K. Aicher,

    1. Center for Regenerative Biology and Medicine, University of Tübingen, Germany
    2. Department of Orthopedic Surgery, Center for Medical Research, University of Tübingen, Germany
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  • Gerd Klein

    Corresponding author
    1. Section for Transplantation Immunology and Immunohematology, Center for Medical Research, University of Tübingen, Germany
    • Center for Medical Research, Section for Transplantation Immunology and Immunohematology, Waldhörnlestrasse 22, 72072 Tübingen, Germany
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    • Tel: +49-7071-29-84465, Fax: +49-7071-29-5567


Abstract

Renal cell carcinoma (RCC) frequently metastasizes to the bone marrow. These metastases are characterized by extensive osteolytic lesions. The mechanism, however, by which RCC cells metastasize to bone marrow remains poorly understood. To unravel the role of bone marrow cells in this context, we performed cell adhesion and migration assays using human RCC cell lines to analyze the influence of resident bone marrow cells on renal tumor cells. The strongest adhesion of RCC cells was observed to osteoblasts. Moreover, conditioned medium of osteoblasts (OB-CM) significantly increased RCC cell migration. By gene expression analysis dysadherin was identified as a transcript whose expression could be elevated more than twofold in RCC cells when exposed to OB-CM. Suppression of dysadherin expression in RCC cells by siRNA reduced their ability to migrate in the presence of OB-CM. Furthermore, the RCC cells secreted high amounts of the chemokine CCL2 when tumor cells migrated under the influence of osteoblast-secreted factors. CCL2 neutralization strongly reduced the migratory ability of the RCC cells. Silencing the expression of dysadherin in RCC cells resulted in a twofold reduction of CCL2 protein expression indicating a dysadherin-dependent expression of the chemokine. Taken together, our data show that osteoblasts are the major cell type of the bone marrow that affect RCC cells by secreting factors that increase the expression of dysadherin and CCL2 in the tumor cells leading to enhanced cell migration. These data suggest an osteoblast-induced autocrine mechanism for a facilitated homing of RCC cells to the bone marrow.

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