title: Basal keratin expression in breast cancer by quantification of mRNA and by immunohistochemistry.
abstract: Definitions of basal-like breast cancer phenotype vary, and microarray-based expression profiling analysis remains the gold standard for the identification of these tumors. Immunohistochemical identification of basal-like carcinomas is hindered with a fact, that on microarray level not all of them express basal-type cytokeratin 5/6, 14 and 17. We compared expression of cytokeratin 5, 14 and 17 in 115 patients with operable breast cancer estimated by real-time RT-PCR and immunohistochemistry. Despite the method of dichotomization and statistical analysis, there were cases with discordant results comparing immunohistochemistry and RT-PCR analysis. For dichotomisation based on quartiles and ROC, 14% of cases were negative on immunohistochemical examination for CK5/6, but presented high CK5 mRNA levels. There were also 48-55% cases, which were CK5/6-immunopositive, but were negative by mRNA examination. Similar discordances were observed for CK14 and CK17. Basal keratin mRNAs did not correlate with ER mRNA levels, while immunohistochemistry produced significant relationship with ER status. Our observation suggest that both method may produce different results in a small proportion of cases. Discordance between immunohistochemistry and RT-PCR may confound attempts to establish a simple methods for identification of basal-like tumors.
authors.affiliation: Department of Pathology, Medical University of Lodz, 4 Paderewski St., Lodz, Poland. radzislaw.kordek@umed.lodz.pl
authors.forename: Radzislaw
authors.initials: R
authors.lastname: Kordek
authors.forename: Piotr
authors.initials: P
authors.lastname: Potemski
authors.forename: Renata
authors.initials: R
authors.lastname: Kusinska
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Pluciennik
authors.forename: Andrzej
authors.initials: A
authors.lastname: Bednarek
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism* / Q000628:therapy; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D007633:Keratins / Q000096:biosynthesis* / Q000378:metabolism; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000378:metabolism*; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
chemical_list: D012333:RNA, Messenger; D007633:Keratins