Original Paper

Histochemistry and Cell Biology

, Volume 111, Issue 6, pp 453-459

Subcellular distribution of S100 proteins in tumor cells and their relocation in response to calcium activation

  • Andrea MuellerAffiliated withDepartment of Pediatrics, Division of Clinical Chemistry and Biochemistry, University of Zurich, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland e-mail: heizmann@kispi.unizh.ch Tel.: +411-2667541, Fax: +411-2667169
  • , Thomas BächiAffiliated withCentral Electron Microscopy Laboratory, University of Zurich, Gloriastrasse 30, CH-8028 Zurich, Switzerland
  • , Matthias HöchliAffiliated withCentral Electron Microscopy Laboratory, University of Zurich, Gloriastrasse 30, CH-8028 Zurich, Switzerland
  • , Beat W. SchäferAffiliated withDepartment of Pediatrics, Division of Clinical Chemistry and Biochemistry, University of Zurich, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland e-mail: heizmann@kispi.unizh.ch Tel.: +411-2667541, Fax: +411-2667169
  • , C. W. HeizmannAffiliated withDepartment of Pediatrics, Division of Clinical Chemistry and Biochemistry, University of Zurich, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland e-mail: heizmann@kispi.unizh.ch Tel.: +411-2667541, Fax: +411-2667169

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Abstract

 S100 proteins, a subgroup of the EF-hand Ca2+-binding protein family, regulate a variety of cellular processes via interaction with different target proteins. Several pathological disorders, including cancer, are linked to altered Ca2+ homeostasis and might involve the multifunctional S100 proteins, which are expressed in a cell- and tissue-specific manner. The present work demonstrates a distinct intracellular localization of S100A6, S100A4, and S100A2 in two tumor cell lines derived from metastatic epithelial breast adenocarcinoma (MDA-MB231) and cervical carcinoma (HeLa). Treatment of the cells by thapsigargin, the ionophore A23187, or cyclic ADP-ribose, to increase [Ca2+]i via different pathways, led to relocation of S100A6 and S100A4 but only partially of the nuclear S100A2, as demonstrated by confocal laser scanning microscopy. These findings support the hypothesis that S100 proteins could play a crucial role in the regulation of Ca2+ homeostasis in cancer cells.