Syncytin is involved in breast cancer-endothelial cell fusions

Cell Mol Life Sci. 2006 Aug;63(16):1906-11. doi: 10.1007/s00018-006-6201-9.


Cancer cells can fuse spontaneously with normal host cells, including endothelial cells, and such fusions may strongly modulate the biological behaviour of tumors. However, the underlying mechanisms are unknown. We now show that human breast cancer cell lines and 63 out of 165 (38%) breast cancer specimens express syncytin, an endogenous retroviral envelope protein, previously implicated in fusions between placental trophoblast cells. Additionally, endothelial and cancer cells are shown to express ASCT-2, a receptor for syncytin. Syncytin antisense treatment decreases syncytin expression and inhibits fusions between breast cancer cells and endothelial cells. Moreover, a syncytin inhibitory peptide also inhibits fusions between cancer and endothelial cells. These results are the first to show that syncytin is expressed by human cancer cells and is involved in cancer-endothelial cell fusions.

MeSH terms

  • Amino Acid Transport System ASC / genetics
  • Amino Acid Transport System ASC / physiology*
  • Base Sequence
  • Breast Neoplasms / pathology
  • Breast Neoplasms / physiopathology*
  • Cell Fusion
  • Cell Line, Tumor
  • DNA Primers
  • Endothelium, Vascular / pathology
  • Endothelium, Vascular / physiopathology*
  • Female
  • Gene Products, env / genetics
  • Gene Products, env / physiology*
  • Humans
  • Immunohistochemistry
  • Minor Histocompatibility Antigens
  • Pregnancy Proteins / genetics
  • Pregnancy Proteins / physiology*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Umbilical Veins


  • Amino Acid Transport System ASC
  • DNA Primers
  • Gene Products, env
  • Minor Histocompatibility Antigens
  • Pregnancy Proteins
  • SLC1A5 protein, human
  • syncytin