title: Human endogenous retroviral syncytin exerts inhibitory effect on invasive phenotype of B16F10 melanoma cells.
abstract: OBJECTIVE
  Fusogenic endogenous retroviral syncytin plays an important role in the formation of syncytiotrophoblasts in human placenta. Apart from its expression in placenta, brain and testis, syncytin has also been found in many cancers. Although syncytin has been proposed to serve as a positive prognostic marker in some cancers, the underlying mechanism is unclear. The aim of this study is to evaluate the effects of syncytin expression on the invasive phenotype of melanoma cells.
  
  
  METHODS
  The eukaryotic expression plasmid for syncytin-EGFP was constructed and transfected into B16F10 melanoma cells. The effect of syncytin on the invasion potential of tumor cells was evaluated in B16F10 subline cells that stably expressed syncytin-EGFP fusion protein or EGFP alone.
  
  
  RESULTS
  The B16F10 sublines that stably expressed syncytin-EGFP or EGFP alone were established respectively and confirmed by immunofluorescent and immunoblotting assay. Syncytin expression in B16F10 cells was associated with decreased cell proliferation, migration and invasion. Multinucleated giant cells that contained as many as five nuclei were induced in syncytin-expressing cells. In addition, syncytin expression did not alter the sensitivity of B16F10 cells to trichosanthin, a toxin that damages syncytiotrophoblasts more efficiently than other tissues.
  
  
  CONCLUSIONS
  These results suggest that syncytin expression in some cancers may confine their invasion potential and thus serve as a positive prognostic factor.
authors.affiliation: Institute of Tissue Transplantation and Immunology, Jinan University, Guangzhou 510632, China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Mo
authors.forename: Dongyun
authors.initials: D
authors.lastname: Ouyang
authors.forename: Lihui
authors.initials: L
authors.lastname: Xu
authors.forename: Qi
authors.initials: Q
authors.lastname: Gao
authors.forename: Xianhui
authors.initials: X
authors.lastname: He
keywords: Syncytin; cell fusion; invasiveness; melanoma; multinucleated cells