title: Retinol induces morphological alterations and proliferative focus formation through free radical-mediated activation of multiple signaling pathways.
abstract: OBJECTIVE
  Toxicity of retinol (vitamin A) has been previously associated with apoptosis and/or cell malignant transformation. Thus, we investigated the pathways involved in the induction of proliferation, deformation and proliferative focus formation by retinol in cultured Sertoli cells of rats.
  
  
  METHODS
  Sertoli cells were isolated from immature rats and cultured. The cells were subjected to a 24-h treatment with different concentrations of retinol. Parameters of oxidative stress and cytotoxicity were analyzed. The effects of the p38 inhibitor SB203580 (10 μmol/L), the JNK inhibitor SP600125 (10 μmol/L), the Akt inhibitor LY294002 (10 μmol/L), the ERK inhibitor U0126 (10 μmol/L) the pan-PKC inhibitor Gö6983 (10 μmol/L) and the PKA inhibitor H89 (1 μmol/L) on morphological and proliferative/transformation-associated modifications were studied.
  
  
  RESULTS
  Retinol (7 and 14 μmol/L) significantly increases the reactive species production in Sertoli cells. Inhibition of p38, JNK, ERK1/2, Akt, and PKA suppressed retinol-induced [(3)H]dT incorporation into the cells, while PKC inhibition had no effect. ERK1/2 and p38 inhibition also blocked retinol-induced proliferative focus formation in the cells, while Akt and JNK inhibition partially decreased focus formation. ERK1/2 and p38 inhibition hindered transformation-associated deformation in retinol-treated cells, while other treatments had no effect.
  
  
  CONCLUSIONS
  Our results suggest that activation of multiple kinases is responsible for morphological and proliferative changes associated to malignancy development in Sertoli cells by retinol at the concentrations higher than physiological level.
authors.affiliation: Center for Oxidative Stress Research, Department of Biochemistry, Federal University of Rio Grande do Sul - Porto Alegre, RS, Brazil. dgelain@yahoo.com.br
authors.forename: Daniel Pens
authors.initials: DP
authors.lastname: Gelain
authors.forename: Matheus Augusto de Bittencourt
authors.initials: MA
authors.lastname: Pasquali
authors.forename: Fernanda Freitas
authors.initials: FF
authors.lastname: Caregnato
authors.forename: Mauro Antonio Alves
authors.initials: MA
authors.lastname: Castro
authors.forename: José Claudio Fonseca
authors.initials: JC
authors.lastname: Moreira
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D005609:Free Radicals / Q000378:metabolism*; D008297:Male; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D012708:Sertoli Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects*; D014801:Vitamin A / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology*
chemical_list: D005609:Free Radicals; D014815:Vitamins; D014801:Vitamin A; D011494:Protein Kinases