Chemokine axes in breast cancer: factors of the tumor microenvironment reshape the CCR7-driven metastatic spread of luminal-A breast tumors

J Leukoc Biol. 2016 Jun;99(6):1009-25. doi: 10.1189/jlb.3MA0815-373R. Epub 2016 Mar 2.

Abstract

Chemokine axes have been shown to mediate site-specific metastasis in breast cancer, but their relevance to different subtypes has been hardly addressed. Here, with the focus on the CCR7-CCL21 axis, patient datasets demonstrated that luminal-A tumors express relatively low CCR7 levels compared with more aggressive disease subtypes. Furthermore, lymph node metastasis was not associated with high CCR7 levels in luminal-A patients. The metastatic pattern of luminal-A breast tumors may be influenced by the way luminal-A tumor cells interpret signals provided by factors of the primary tumor microenvironment. Thus, CCR7-expressing human luminal-A cells were stimulated simultaneously by factors representing 3 tumor microenvironment arms typical of luminal-A tumors, hormonal, inflammatory, and growth stimulating: estrogen + TNF-α + epidermal growth factor. Such tumor microenvironment stimulation down-regulated the migration of CCR7-expressing tumor cells toward CCL21 and inhibited the formation of directional protrusions toward CCL21 in a novel 3-dimensional hydrogel system. CCL21-induced migration of CCR7-expressing tumor cells depended on PI3K and MAPK activation; however, when CCR7-expressing cancer cells were prestimulated by tumor microenvironment factors, CCL21 could not effectively activate these signaling pathways. In vivo, pre-exposure of the tumor cells to tumor microenvironment factors has put restraints on CCL21-mediated lymph node-homing cues and shifted the metastatic pattern of CCR7-expressing cells to the aggressive phenotype of dissemination to bones. Several of the aspects were also studied in the CXCR4-CXCL12 system, demonstrating similar patient and in vitro findings. Thus, we provide novel evidence to subtype-specific regulation of the CCR7-CCL21 axis, with more general implications to chemokine-dependent patterns of metastatic spread, revealing differential regulation in the luminal-A subtype.

Keywords: CCL21; CXCR4-CXCL12 axis; bone metastasis; lymph node metastasis; migration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology*
  • Cell Line, Tumor
  • Cell Movement
  • Cell Surface Extensions / metabolism
  • Chemokine CCL21 / metabolism*
  • Down-Regulation
  • Endocytosis
  • Enzyme Activation
  • Female
  • Humans
  • Lymphatic Metastasis / pathology*
  • Mice, Nude
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, CCR7 / metabolism*
  • Tumor Microenvironment*

Substances

  • CCL21 protein, human
  • Chemokine CCL21
  • Receptors, CCR7
  • Proto-Oncogene Proteins c-akt