title: Molecular characterization of spontaneous mesenchymal stem cell transformation.
abstract: BACKGROUND
  We previously reported the in vitro spontaneous transformation of human mesenchymal stem cells (MSC) generating a population with tumorigenic potential, that we termed transformed mesenchymal cells (TMC).
  
  
  RESULTS
  Here we have characterized the molecular changes associated with TMC generation. Using microarrays techniques we identified a set of altered pathways and a greater number of downregulated than upregulated genes during MSC transformation, in part due to the expression of many untranslated RNAs in MSC. Microarray results were validated by qRT-PCR and protein detection.
  
  
  CONCLUSIONS
  In our model, the transformation process takes place through two sequential steps; first MSC bypass senescence by upregulating c-myc and repressing p16 levels. The cells then bypass cell crisis with acquisition of telomerase activity, Ink4a/Arf locus deletion and Rb hyperphosphorylation. Other transformation-associated changes include modulation of mitochondrial metabolism, DNA damage-repair proteins and cell cycle regulators. In this work we have characterized the molecular mechanisms implicated in TMC generation and we propose a two-stage model by which a human MSC becomes a tumor cell.
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rubio
authors.forename: Silvia
authors.initials: S
authors.lastname: Garcia
authors.forename: Maria F
authors.initials: MF
authors.lastname: Paz
authors.forename: Teresa
authors.initials: T
authors.lastname: De la Cueva
authors.forename: Luis A
authors.initials: LA
authors.lastname: Lopez-Fernandez
authors.forename: Alison C
authors.initials: AC
authors.lastname: Lloyd
authors.forename: Javier
authors.initials: J
authors.lastname: Garcia-Castro
authors.forename: Antonio
authors.initials: A
authors.lastname: Bernad
mesh_terms: D002471:Cell Transformation, Neoplastic; D004260:DNA Repair; D015870:Gene Expression; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction