title: Sox2: a possible driver of the basal-like phenotype in sporadic breast cancer.
abstract: Tumours arising in BRCA1 mutation carriers and sporadic basal-like breast carcinomas have similar phenotypic, immunohistochemical and clinical characteristics. SOX2 is an embryonic transcription factor located at chromosome 3q, a region frequently gained in sporadic basal-like and BRCA1 germline mutated tumours. The aim of the study was to establish whether sox2 expression was related to basal-like sporadic breast tumours. Two hundred and twenty-six sporadic node-negative invasive breast carcinomas were immunohistochemically analysed for oestrogen receptor (ER), progesterone receptor (PR), CK5/6, EGFR, vimentin, HER2, ki67, p53 and sox2 using tissue microarrays. Tumours were considered to have basal-like phenotype if they were ER/HER2-negative and CK5/6 and/or EGFR-positive. Thirty cases of this series (13.7%) displayed a basal-like phenotype. Sox2 expression was observed in 16.7% of cases and was significantly more frequently expressed in basal-like breast carcinomas (43.3% in basal-like, 10.6% in luminal and 13.3% in HER2+ tumours, P<0.001). Moreover, Sox2 showed a statistically significant inverse association with ER and PR (P=0.001 and 0.017, respectively) and direct association with CK5/6, EGFR and vimentin (P=0.022, 0.005 and <0.001, respectively). Sox2 is preferentially expressed in tumours with basal-like phenotype and may play a role in defining their less differentiated/'stem cell' phenotypic characteristics.
authors.affiliation: Laboratory of Breast and Gynaecological Cancer, Molecular Pathology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain. smrodriguez@yahoo.es
authors.forename: Socorro M
authors.initials: SM
authors.lastname: Rodriguez-Pinilla
authors.forename: David
authors.initials: D
authors.lastname: Sarrio
authors.forename: Gema
authors.initials: G
authors.lastname: Moreno-Bueno
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Rodriguez-Gil
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Martinez
authors.forename: Lucia
authors.initials: L
authors.lastname: Hernandez
authors.forename: David
authors.initials: D
authors.lastname: Hardisson
authors.forename: Jorge S
authors.initials: JS
authors.lastname: Reis-Filho
authors.forename: Jose
authors.initials: J
authors.lastname: Palacios
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D005260:Female; D024002:HMGB Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D018295:Neoplasms, Basal Cell / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D055748:SOXB1 Transcription Factors; D051876:Sex-Determining Region Y Protein / Q000378:metabolism*; D046888:Tissue Array Analysis; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D024002:HMGB Proteins; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; D051876:Sex-Determining Region Y Protein; D014157:Transcription Factors