title: Reversible dysfunction of wild-type p53 following homeodomain-interacting protein kinase-2 knockdown.
abstract: About half of cancers sustain mutations in the TP53 gene, whereas the other half maintain a wild-type p53 (wtp53) but may compromise the p53 response because of other alterations. Homeodomain-interacting protein kinase-2 (HIPK2) is a positive regulator of p53 oncosuppressor function. Here, we show, by microarray analysis, that wtp53 lost the target gene activation following stable knockdown of HIPK2 (HIPK2i) in colon cancer cell line. Our data show that the stable knockdown of HIPK2 led to wtp53 misfolding, as detected by p53 immunoprecipitation with conformation-specific antibodies, and that p53 protein misfolding impaired p53 DNA binding and transcription of target genes. We present evidence that zinc supplementation to HIPK2i cells increased p53 reactivity to conformation-sensitive PAb1620 (wild-type conformation) antibody and restored p53 sequence-specific DNA binding in vivo and transcription of target genes in response to Adriamycin treatment. Finally, combination of zinc and Adriamycin suppressed tumor growth in vivo and activated misfolded p53 that induced its target genes in nude mice tumor xenografts derived from HIPK2i cells. Bioinformatics analysis of microarray data from colon cancer patients showed significant association of poor survival with low HIPK2 expression only in tumors expressing wtp53. These results show a critical role of HIPK2 in maintaining the transactivation activity of wtp53 and further suggest that low expression of HIPK2 may impair the p53 function in tumors harboring wtp53.
authors.affiliation: Molecular Oncogenesis Laboratory and Preclinical Experimental Laboratory, Regina Elena Cancer Institute, Rome, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Puca
authors.forename: Lavinia
authors.initials: L
authors.lastname: Nardinocchi
authors.forename: Hilah
authors.initials: H
authors.lastname: Gal
authors.forename: Gideon
authors.initials: G
authors.lastname: Rechavi
authors.forename: Ninette
authors.initials: N
authors.lastname: Amariglio
authors.forename: Eytan
authors.initials: E
authors.lastname: Domany
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Notterman
authors.forename: Marco
authors.initials: M
authors.lastname: Scarsella
authors.forename: Carlo
authors.initials: C
authors.lastname: Leonetti
authors.forename: Ada
authors.initials: A
authors.lastname: Sacchi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Blandino
authors.forename: David
authors.initials: D
authors.lastname: Givol
authors.forename: Gabriella
authors.initials: G
authors.lastname: D'Orazi
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000235:genetics*; D004317:Doxorubicin / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D009368:Neoplasm Transplantation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*
chemical_list: D000903:Antibiotics, Antineoplastic; D002352:Carrier Proteins; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin; C115114:HIPK2 protein, human; C492003:Hipk2 protein, mouse; D017346:Protein Serine-Threonine Kinases