SDF-1/CXCL12 induces directional cell migration and spontaneous metastasis via a CXCR4/Gαi/mTORC1 axis

FASEB J. 2015 Mar;29(3):1056-68. doi: 10.1096/fj.14-260083. Epub 2014 Dec 2.


Multiple human malignancies rely on C-X-C motif chemokine receptor type 4 (CXCR4) and its ligand, SDF-1/CXCL12 (stroma cell-derived factor 1/C-X-C motif chemokine 12), to metastasize. CXCR4 inhibitors promote the mobilization of bone marrow stem cells, limiting their clinical application for metastasis prevention. We investigated the CXCR4-initiated signaling circuitry to identify new potential therapeutic targets. We used HeLa human cancer cells expressing high levels of CXCR4 endogenously. We found that CXCL12 promotes their migration in Boyden chamber assays and single cell tracking. CXCL12 activated mTOR (mechanistic target of rapamycin) potently in a pertussis-sensitive fashion. Inhibition of mTOR complex 1 (mTORC1) by rapamycin [drug concentration causing 50% inhibition (IC50) = 5 nM] and mTORC1/mTORC2 by Torin2 (IC50 = 6 nM), or by knocking down key mTORC1/2 components, Raptor and Rictor, respectively, decreased directional cell migration toward CXCL12. We developed a CXCR4-mediated spontaneous metastasis model by implanting HeLa cells in the tongue of SCID-NOD mice, in which 80% of the animals develop lymph node metastasis. It is surprising that mTORC1 disruption by Raptor knockdown was sufficient to reduce tumor growth by 60% and spontaneous metastasis by 72%, which were nearly abolished by rapamycin. In contrast, disrupting mTORC2 had no effect in tumor growth or metastasis compared with control short hairpin RNAs. These data suggest that mTORC1 may represent a suitable therapeutic target in human malignancies using CXCR4 for their metastatic spread. .

Keywords: cancer; chemotaxis; lymphangiogenesis; mTOR; rapamycin.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Apoptosis
  • Blotting, Western
  • Cell Movement*
  • Cell Proliferation
  • Chemokine CXCL12 / metabolism*
  • Female
  • Fluorescent Antibody Technique
  • GTP-Binding Protein alpha Subunit, Gi2 / metabolism*
  • Humans
  • Immunoenzyme Techniques
  • Lymphatic Metastasis
  • Mechanistic Target of Rapamycin Complex 1
  • Mice
  • Mice, Inbred NOD
  • Mice, SCID
  • Multiprotein Complexes / metabolism*
  • Receptors, CXCR4 / metabolism*
  • Signal Transduction
  • TOR Serine-Threonine Kinases / metabolism*
  • Tumor Cells, Cultured
  • Uterine Cervical Neoplasms / metabolism
  • Uterine Cervical Neoplasms / secondary*


  • CXCL12 protein, human
  • CXCR4 protein, human
  • Chemokine CXCL12
  • Multiprotein Complexes
  • Receptors, CXCR4
  • MTOR protein, human
  • Mechanistic Target of Rapamycin Complex 1
  • TOR Serine-Threonine Kinases
  • GTP-Binding Protein alpha Subunit, Gi2