title: IPH-926 lobular breast cancer cells harbor a p53 mutant with temperature-sensitive functional activity and allow for profiling of p53-responsive genes.
abstract: Profiling of p53-responsive genes has been carried out in different cellular models, most of which involved genetic modifications or cytotoxic stimulation. We report on the utilization of IPH-926 human lobular breast cancer cells for the profiling of p53-responsive genes using a novel approach without such modifications. We discovered that IPH-926 cells harbor a homozygous TP53 missense mutation encoding for a rare p53 mutant (E285K) with temperature-sensitive (ts) loss of function characteristics. This mutation had evolved as a late, secondary genetic event during the natural clonal evolution of the corresponding lobular carcinoma. In vitro temperature shifts reconstituted endogenous wild-type p53 activity in IPH-926, as evidenced by induction of p21(Waf1). Transcriptional alterations associated with restored p53 function were profiled using Affymetrix microarrays and a new strategy to gate out non-specific temperature effects. At the P=0.0005 significance level, 60 genes were differentially expressed following reconstitution of p53 activity. These genes included CDKN1A, MDM2 and PHLDA3, a recently described p53-inducible inhibitor of AKT. Similar transcriptional alterations were observed upon reconstitution of p53 activity in BT-474 cells, which also harbor ts-p53 E285K, and in ASPC1 cells transduced with ts-p53 A138V. Consistent with these models, low PHLDA3 expression was associated with nuclear p53 accumulation, indicative of deleterious TP53 mutations, in primary breast cancers. From a molecular point of view, IPH-926 thus provides a new tool to study transcriptional programs controlled by p53. From a tumor pathology perspective, IPH-926 also provides the first direct evidence of a p53-related clonal evolutionary pathway in lobular breast cancer progression.
authors.affiliation: Institute of Pathology, Hannover Medical School, Hannover, Germany. Christgen.Matthias@MH-Hannover.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Christgen
authors.forename: Monika
authors.initials: M
authors.lastname: Noskowicz
authors.forename: Charlotte
authors.initials: C
authors.lastname: Heil
authors.forename: Elisa
authors.initials: E
authors.lastname: Schipper
authors.forename: Henriette
authors.initials: H
authors.lastname: Christgen
authors.forename: Robert
authors.initials: R
authors.lastname: Geffers
authors.forename: Hans
authors.initials: H
authors.lastname: Kreipe
authors.forename: Ulrich
authors.initials: U
authors.lastname: Lehmann
mesh_terms: D000818:Animals; D017209:Apoptosis; D001943:Breast Neoplasms / Q000235:genetics*; D018275:Carcinoma, Lobular / Q000235:genetics*; D045744:Cell Line, Tumor; D019143:Evolution, Molecular; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D006801:Humans; D051379:Mice; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000378:metabolism; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
chemical_list: D009687:Nuclear Proteins; C495901:TP53 protein, human; C109277:TSSC3 protein; D016159:Tumor Suppressor Protein p53