title: Limited importance of the dominant-negative effect of TP53 missense mutations.
abstract: BACKGROUND
  Heterozygosity of TP53 missense mutations is related to the phenomenon of the dominant-negative effect (DNE). To estimate the importance of the DNE of TP53 mutations, we analysed the percentage of cancer cases showing a single heterozygous mutation of TP53 and searched for a cell line with a single heterozygous mutation of this gene. This approach was based on the knowledge that genes with evident DNE, such as EGFR and IDH1, represent nearly 100% of single heterozygous mutations in tumour specimens and cell lines.
  
  
  METHODS
  Genetic analyses (LOH and sequencing) performed for early and late passages of several cell lines originally described as showing single heterozygous TP53 mutations (H-318, G-16, PF-382, MOLT-13, ST-486 and LS-123). Statistical analysis of IARC TP53 and SANGER databases. Genetic analyses of N-RAS, FBXW7, PTEN and STR markers to test cross-contamination and cell line identity. Cell cloning, fluorescence-activated cell sorting and SSCP performed for the PF-382 cell line.
  
  
  RESULTS
  A database study revealed TP53 single heterozygous mutations in 35% of in vivo (surgical and biopsy) samples and only 10% of cultured cells (in vitro), although those numbers appeared to be overestimated. We deem that published in vivo TP53 mutation analyses are not as rigorous as studies in vitro, and we did not find any cell line showing a stable, single heterozygous mutation. G16, PF-382 and MOLT-13 cells harboured single heterozygous mutations temporarily. ST-486, H-318 and LS-123 cell lines were misclassified. Specific mutations, such as R175H, R273H, R273L or R273P, which are reported in the literature to exert a DNE, showed the lowest percentage of single heterozygous mutations in vitro (about 5%).
  
  
  CONCLUSIONS
  We suggest that the currently reported percentage of TP53 single heterozygous mutations in tumour samples and cancer cell lines is overestimated. Thus, the magnitude of the DNE of TP53 mutations is questionable. This scepticism is supported by database investigations showing that retention of the wild-type allele occurs with the same frequency as either nonsense or missense TP53 mutations.
authors.affiliation: Department of Molecular Pathology and Neuropathology, Chair of Oncology, Medical University of Lodz, Czechoslowacka 8/10, 92-216 Lodz, Poland.
authors.forename: Ewelina
authors.initials: E
authors.lastname: Stoczynska-Fidelus
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Szybka
authors.forename: Sylwester
authors.initials: S
authors.lastname: Piaskowski
authors.forename: Michal
authors.initials: M
authors.lastname: Bienkowski
authors.forename: Krystyna
authors.initials: K
authors.lastname: Hulas-Bigoszewska
authors.forename: Mateusz
authors.initials: M
authors.lastname: Banaszczyk
authors.forename: Izabela
authors.initials: I
authors.lastname: Zawlik
authors.forename: Dorota
authors.initials: D
authors.lastname: Jesionek-Kupnicka
authors.forename: Radzislaw
authors.initials: R
authors.lastname: Kordek
authors.forename: Pawel P
authors.initials: PP
authors.lastname: Liberski
authors.forename: Piotr
authors.initials: P
authors.lastname: Rieske
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004252:DNA Mutational Analysis; D030541:Databases, Genetic; D006801:Humans; D019656:Loss of Heterozygosity / Q000235:genetics*; D051379:Mice; D020125:Mutation, Missense / Q000235:genetics*; D009369:Neoplasms / Q000235:genetics* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
chemical_list: D016159:Tumor Suppressor Protein p53