title: Over expression of the selectable marker blasticidin S deaminase gene is toxic to human keratinocytes and murine BALB/MK cells.
abstract: BACKGROUND
  The blasticidin S resistance gene (bsr) is a selectable marker used for gene transfer experiments. The bsr gene encodes for blasticidin S (BS) deaminase, which has a specific activity upon BS. Therefore, its expression is supposed to be harmless in cells. The work reported on herein consisted of experiments to verify a possible toxicity of bsr on mammalian cells, which include several cell lines and primary cultures.
  
  
  RESULTS
  Murine keratinocyte BALB/MK and human primary keratinocyte cells transduced with the retroviral vector LBmSN, which has an improved expression system of bsr, namely bsrm, died in five days after the transduction. Meanwhile the control vector LBSN, which expresses bsr, did not provoke cell death. The lethal activity of bsrm was observed only in human keratinocytes and BALB/MK cells among the cell types tested here. Death appears to be mediated by a factor, which is secreted by the BALB/MK transduced cells.
  
  
  CONCLUSIONS
  By our study we demonstrated that the expression of bsrm gene is toxic to human keratinocytes and BALB/MK cells. It is likely over expression of BS deaminase gene is responsible for the death.
authors.affiliation: Department of Biophysics & Center for Gene Therapy, UNIFESP - EPM, São Paulo, SP, Brazil. fmbento@hotmail.com <fmbento@hotmail.com>
authors.forename: Fernanda Mara
authors.initials: FM
authors.lastname: Bento
authors.forename: Daniela
authors.initials: D
authors.lastname: Takeshita
authors.forename: Chester Bittencourt
authors.initials: CB
authors.lastname: Sacramento
authors.forename: Tamara Rocha
authors.initials: TR
authors.lastname: Machado
authors.forename: Monica Beatriz
authors.initials: MB
authors.lastname: Mathor
authors.forename: Adriana Karaoglanovic
authors.initials: AK
authors.lastname: Carmona
authors.forename: Sang Won
authors.initials: SW
authors.lastname: Han
mesh_terms: D000619:Aminohydrolases / Q000235:genetics* / Q000633:toxicity*; D000818:Animals; D002452:Cell Count; D016923:Cell Death / Q000235:genetics; D002460:Cell Line; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D005804:Genes, Lethal / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics*; D005822:Genetic Vectors / Q000235:genetics / Q000633:toxicity; D006801:Humans; D015603:Keratinocytes / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D041681:NIH 3T3 Cells / Q000737:chemistry / Q000378:metabolism; D009705:Nucleosides / Q000235:genetics / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics / Q000378:metabolism; D014161:Transduction, Genetic / Q000379:methods
chemical_list: D005819:Genetic Markers; D009705:Nucleosides; C004500:blasticidin S; D000619:Aminohydrolases; C019795:blasticidin S deaminase