title: Expression of BRCA1, NBR1 and NBR2 genes in human breast cancer cells.
abstract: BRCA1 is a tumour suppressor gene with a caretaker function in the DNA-damage repair and the maintenance of genome integrity. The human BRCA1 and NBR2 genes and the homologous Brcal and Nbr1 mouse genes are situated head-to-head on human chromosome 17q21 and on mouse chromosome 11, respectively. Their transcription start sites, located on opposite DNA strands, are separated by 218 bp in humans, and by 289 bp in mice. Because of this intimate contact and because of our previous observation of a quasi-reciprocal expression pattern of Brca1 and Nbr1 in mouse spermatogenesis, we estimated here the relative mRNA expression of BRCA1, NBR1 (next-to-BRCA1) and NBR2 genes in a panel of permanent cell lines and primary cell cultures derived from human breast cancer or normal mammary tissue. The analysis revealed highly significant downregulation of BRCA1 in 11 out of 12 examined tumour cell lines and primary cell cultures as compared to non-malignant mammary cells. Two isoforms of NBR1(1A) and the classical NBR1(1B) transcripts were found in cells from malignant mammary tissues, all of them downregulated in respect to normal cells. The expression of NBR2 differed, being increased in three permanent tumour cell lines and slightly decreased in all primary breast cancer cell cultures. The in silico analysis revealed two new putative domains of the predicted NBR1 protein, suggesting its role in the ubiquitin pathway. The recent identification of the ubiquitin protein ligase activity of BRCA1 implies a possible functional connection between both genes.
authors.affiliation: Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague.
authors.forename: S D
authors.initials: SD
authors.lastname: Dimitrov
authors.forename: E
authors.initials: E
authors.lastname: Matousková
authors.forename: J
authors.initials: J
authors.lastname: Forejt
mesh_terms: D017398:Alternative Splicing; D019313:BRCA1 Protein / Q000096:biosynthesis*; D001940:Breast / Q000166:cytology / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019398:Genes, BRCA1; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics; D062085:RNA, Long Noncoding; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D019313:BRCA1 Protein; D047908:Intracellular Signaling Peptides and Proteins; C549756:NBR1 protein, human; C107422:NBR2 lncRNA, human; C486326:Nbr1 protein, mouse; D009363:Neoplasm Proteins; D020033:Protein Isoforms; D011506:Proteins; D062085:RNA, Long Noncoding; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D014157:Transcription Factors