title: Morphologic conversion of a neuroblastoma-derived cell line by E6-mediated p53 degradation.
abstract: Neuroblastoma-derived tumor cells, unlike cells from other tumor types, characteristically express a wildtype but cytoplasmically sequestered p53 protein. To ascertain whether the p53 in these cells retained any physiological activity, we inactivated it in SK-N-SH cells, a neuroblastoma-derived cell line, by introducing the human papilloma virus type 16 E6 expression plasmid. Parent SK-N-SH cell cultures are composed of two cell types exhibiting characteristic morphologies designated neuroblastic (N-type) or substrate-adherent fibroblastic (S-type) cells, both of which have been shown to spontaneously transdifferentiate or interconvert. We report here that down-regulation of p53 resulted in conversion of SK-N-SH cells to the substrate-adherent fibroblast-like S-type cells. The morphologic conversion was accompanied by a loss of neurofilament expression, a marker for the neuronal N-type cells, an increase in the expression of vimentin, and a lack of responsiveness to retinoic acid-induced neuronal differentiation. Importantly, we did not observe N-type cells in the E6-transfected cell population, suggesting that they were incapable of transdifferentiating to the N-type morphology. We also tested the ability of these E6-transfected S-type cells to form colonies in soft agar and observed a markedly reduced capacity of these cells to do so when compared with the parent and mutant E6-transfected cells. These results suggest that p53 is required for the maintenance of the neuroblastic tumorigenic phenotype.
authors.affiliation: Cancer Biology Interdisciplinary Program, and Arizona Cancer Center, Department of Radiation Oncology, University of Arizona, Tucson 85724, USA.
authors.forename: S V
authors.initials: SV
authors.lastname: Gaitonde
authors.forename: W
authors.initials: W
authors.lastname: Qi
authors.forename: R R
authors.initials: RR
authors.lastname: Falsey
authors.forename: N
authors.initials: N
authors.lastname: Sidell
authors.forename: J D
authors.initials: JD
authors.lastname: Martinez
mesh_terms: D000362:Agar / Q000737:chemistry; D017209:Apoptosis; D015153:Blotting, Western; D002448:Cell Adhesion; D002454:Cell Differentiation; D002455:Cell Division; D004247:DNA / Q000187:drug effects / Q000528:radiation effects; D015536:Down-Regulation; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism*; D016900:Neurofilament Proteins / Q000378:metabolism; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011839:Radiation, Ionizing; D012097:Repressor Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology; D014404:Tubulin / Q000096:biosynthesis; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014746:Vimentin / Q000096:biosynthesis
chemical_list: C068651:E6 protein, Human papillomavirus type 16; D016900:Neurofilament Proteins; D009856:Oncogene Proteins, Viral; D012097:Repressor Proteins; D014404:Tubulin; D016159:Tumor Suppressor Protein p53; D014746:Vimentin; D014212:Tretinoin; D000362:Agar; D004247:DNA