title: p300 and p53 levels determine activation of HIF-1 downstream targets in invasive breast cancer.
abstract: In previous studies, we noted that overexpression of hypoxia-inducible factor (HIF)-1alpha in breast cancer, especially the diffuse form, does not always lead to functional activation of its downstream genes. Transcriptional activity of HIF-1 may be repressed by p53 through competition for transcriptional coactivators such as p300. The aim of this study was therefore to explore the role of p53 and p300 in relation to overexpression of HIF-1alpha and activation of HIF-1 downstream genes in invasive breast cancer. p300 immunohistochemistry was performed in a group of 183 early-stage invasive breast cancers, and related to p53 accumulation, overexpression of HIF-1alpha, and several HIF-1 downstream genes. p300 was expressed in varying degrees in 84% of invasive breast cancers. p300 staining intensity correlated positively with HIF-1alpha expression (P = .04), p53 accumulation (P = .001), and overexpression of glucose transporter 1 (GLUT-1) (P < .001), a glucose transporter downstream target gene of HIF-1. GLUT-1 levels were significantly associated with p300 in HIF-1alpha positive patients (P = .02). p53 accumulation significantly positively correlated with carbonic anhydrase IX (CAIX)/GLUT-1 coexpression in HIF-1alpha-positive patients (P = .007). p53 accumulation/high p300 levels, the most favorable situation for HIF-1 downstream activation, were significantly associated with GLUT-1 overexpression (P = .01) and coexpression of CAIX/GLUT-1 (P = .03), compared with low p53/low p300 levels, the most unfavorable situation for HIF-1 downstream activation. p300 is a cofactor highly associated with p53 accumulation and HIF-1alpha levels in invasive breast cancer. Furthermore, low levels of p300 may explain absence of downstream effects in HIF-1alpha-overexpressing cancers, an effect that seems to be enhanced by wild-type levels of p53. This underlines the importance of p300 levels and p53 accumulation in the HIF-1-regulated response toward hypoxia.
authors.affiliation: Department of Pathology, University Medical Center Utrecht, 3508 GA Utrecht, The Netherlands.
authors.forename: Marije M
authors.initials: MM
authors.lastname: Vleugel
authors.forename: David
authors.initials: D
authors.lastname: Shvarts
authors.forename: Elsken
authors.initials: E
authors.lastname: van der Wall
authors.forename: Paul J
authors.initials: PJ
authors.lastname: van Diest
mesh_terms: D000951:Antigens, Neoplasm / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000378:metabolism; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000473:pathology; D002467:Cell Nucleus / Q000187:drug effects / Q000473:pathology; D050881:E1A-Associated p300 Protein / Q000378:metabolism*; D005260:Female; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis*; D007150:Immunohistochemistry; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D051272:Glucose Transporter Type 1; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016159:Tumor Suppressor Protein p53; D050881:E1A-Associated p300 Protein; C494360:EP300 protein, human; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases