title: The GADD45, ZBRK1 and BRCA1 pathway: quantitative analysis of mRNA expression in colon carcinomas.
abstract: GADD45 is a growth arrest-associated gene that is induced in response to DNA damage. This gene is a target for coordinate regulation by both ZBRK1 and BRCA1. A sequence within intron 3 of GADD45 supports specific assembly of the ZBRK1/BRCA1 complex. In this study, the relationships between GADD45, ZBRK1, and BRCA1 expression were investigated in colon carcinomas. mRNA expression of these three genes was analysed in 116 colon carcinomas by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Genetic and epigenetic changes that could alter expression of these genes were studied. Possible relationships between expression levels of GADD45, ZBRK1, and BRCA1, and a series of clinicopathological parameters classically associated with poor prognosis, were also examined. ZBRK1 showed a tendency towards underexpression, while GADD45 and BRCA1 were generally overexpressed. A direct relationship between these three genes was observed, with the exception of BRCA1 expression levels, similar to normal tissues, which showed a tendency to be associated with low levels of GADD45 mRNA. Concomitantly altered expression of ZBRK1 and BRCA1 was associated with GADD45 mRNA expression. Promoter hypermethylation was not observed in GADD45 or BRCA1, and no mutations in GADD45 or ZBRK1 were found in regions involved in the interaction between the GADD45 gene and the ZBRK1 and BRCA1 proteins. No clinicopathological parameter was correlated with altered GADD45 or ZBRK1 expression but there was a statistically significant relationship between BRCA1 levels and the sex of patients. In conclusion, these results suggest that this pathway, involved in the response to DNA damage, is deregulated in colon carcinomas, and concomitantly altered expression of ZBRK1 and BRCA1 has an additive effect on GADD45 regulation. This is the first study in human carcinomas to analyse the relationships between expression of GADD45, ZBRK1, and BRCA1 mRNA.
authors.affiliation: Department of Medical Oncology, Hospital Universitario Puerta de Hierro, Madrid, Spain.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Garcia
authors.forename: José M
authors.initials: JM
authors.lastname: García
authors.forename: Cristina
authors.initials: C
authors.lastname: Peña
authors.forename: Javier
authors.initials: J
authors.lastname: Silva
authors.forename: Gemma
authors.initials: G
authors.lastname: Domínguez
authors.forename: Rufo
authors.initials: R
authors.lastname: Rodríguez
authors.forename: Constanza
authors.initials: C
authors.lastname: Maximiano
authors.forename: Ruth
authors.initials: R
authors.lastname: Espinosa
authors.forename: Pilar
authors.initials: P
authors.lastname: España
authors.forename: Félix
authors.initials: F
authors.lastname: Bonilla
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry / Q000235:genetics*; D000704:Analysis of Variance; D016022:Case-Control Studies; D003110:Colonic Neoplasms / Q000737:chemistry / Q000235:genetics*; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019398:Genes, BRCA1; D005819:Genetic Markers; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D008297:Male; D018807:Polymorphism, Single-Stranded Conformational; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018709:Statistics, Nonparametric; D000097642:GADD45 Proteins
chemical_list: D004268:DNA-Binding Proteins; D005819:Genetic Markers; D047908:Intracellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D000097642:GADD45 Proteins; C422407:ZNF350 protein, human