Distinct functions of macrophage-derived and cancer cell-derived cathepsin Z combine to promote tumor malignancy via interactions with the extracellular matrix

  1. Johanna A. Joyce1
  1. 1Cancer Biology and Genetics Program, Memorial Sloan-Kettering Cancer Center, New York, New York,10065, USA;
  2. 2Institute of Molecular Medicine and Cell Research, Albert-Ludwigs University, D-79104 Freiburg, Germany;
  3. 3BIOSS Centre for Biological Signalling Studies, D-79104 Freiburg, Germany;
  4. 4German Cancer Consortium (DKTK), D-79104 Freiburg, Germany;
  5. 5Pathology Department, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA
  1. Corresponding author: joycej{at}mskcc.org

Abstract

During the process of tumor progression, cancer cells can produce the requisite growth- and invasion-promoting factors and can also rely on noncancerous cells in the tumor microenvironment as an alternative, cell-extrinsic source. However, whether the cellular source influences the function of such tumor-promoting factors remains an open question. Here, we examined the roles of the cathepsin Z (CtsZ) protease, which is provided by both cancer cells and macrophages in pancreatic neuroendocrine tumors in humans and mice. We found that tumor proliferation was exclusively regulated by cancer cell-intrinsic functions of CtsZ, whereas tumor invasion required contributions from both macrophages and cancer cells. Interestingly, several of the tumor-promoting functions of CtsZ were not dependent on its described catalytic activity but instead were mediated via the Arg–Gly–Asp (RGD) motif in the enzyme prodomain, which regulated interactions with integrins and the extracellular matrix. Together, these results underscore the complexity of interactions within the tumor microenvironment and indicate that cellular source can indeed impact molecular function.

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Footnotes

  • Received July 26, 2014.
  • Accepted August 29, 2014.

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