Toll-like receptor 9 agonists promote cellular invasion by increasing matrix metalloproteinase activity

Mol Cancer Res. 2006 Jul;4(7):437-47. doi: 10.1158/1541-7786.MCR-06-0007.

Abstract

Toll-like receptor 9 (TLR9) recognizes microbial DNA. We show here that TLR9 protein is expressed in human breast cancer cells and clinical breast cancer samples. Stimulation of TLR9-expressing breast cancer cells with the TLR9 agonistic CpG oligonucleotides (1-10 mumol/L) dramatically increased their in vitro invasion in both Matrigel assays and three-dimensional collagen cultures. Similar effects on invasion were seen in TLR9-expressing astrocytoma and glioblastoma cells and in the immortalized human breast epithelial cell line MCF-10A. This effect was not, however, dependent on the CpG content of the TLR9 ligands because the non-CpG oligonucleotides induced invasion of TLR9-expressing cells. CpG or non-CpG oligonucleotide-induced invasion in MDA-MB-231 cells was blunted by chloroquine and they did not induce invasion of TLR9(-) breast cancer cells. Treatment of MDA-MB-231 cells with CpG or non-CpG oligonucleotides induced the formation of approximately 50-kDa gelatinolytic band in zymograms. This band and the increased invasion were abolished by a matrix metalloproteinase (MMP) inhibitor GM6001 but not by a serine proteinase inhibitor aprotinin. Furthermore, CpG oligonucleotide treatment decreased tissue inhibitor of metalloproteinase-3 expression and increased levels of active MMP-13 in TLR9-expressing but not TLR9(-) breast cancer cells without affecting MMP-8. Neutralizing anti-MMP-13 antibodies inhibited the CpG oligonucleotide-induced invasion. These findings suggest that infections may promote cancer progression through a novel TLR9-mediated mechanism. They also propose a new molecular target for cancer therapy, because TLR9 has not been associated with cancer invasiveness previously.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antibodies / pharmacology
  • Astrocytoma / enzymology
  • Astrocytoma / pathology
  • Breast Neoplasms / enzymology*
  • Breast Neoplasms / pathology
  • Cell Line, Tumor
  • Collagenases / immunology
  • Collagenases / metabolism
  • CpG Islands
  • DNA-Binding Proteins / genetics
  • Glioblastoma / enzymology
  • Glioblastoma / pathology
  • Humans
  • Matrix Metalloproteinase 13
  • Matrix Metalloproteinase 8 / metabolism
  • Matrix Metalloproteinase Inhibitors
  • Matrix Metalloproteinases / metabolism*
  • Neoplasm Invasiveness
  • Oligonucleotides / genetics
  • Oligonucleotides / pharmacology
  • Toll-Like Receptor 9 / agonists*
  • Toll-Like Receptor 9 / biosynthesis
  • Toll-Like Receptor 9 / genetics
  • Toll-Like Receptor 9 / metabolism
  • Trans-Activators

Substances

  • Antibodies
  • CXXC1 protein, human
  • DNA-Binding Proteins
  • Matrix Metalloproteinase Inhibitors
  • Oligonucleotides
  • TLR9 protein, human
  • Toll-Like Receptor 9
  • Trans-Activators
  • Collagenases
  • MMP13 protein, human
  • Matrix Metalloproteinase 13
  • Matrix Metalloproteinases
  • Matrix Metalloproteinase 8