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Evaluation of oestrogen receptor expression in breast cancer by quantification of mRNA
Author(s) -
Potemski P,
Pluciennik E,
Bednarek A K,
Kusinska R,
Kubiak R,
Kordek R
Publication year - 2007
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/j.1365-2559.2007.02886.x
Subject(s) - immunohistochemistry , breast cancer , subtyping , biology , keratin , messenger rna , real time polymerase chain reaction , gene expression , pathology , tissue microarray , estrogen receptor , cancer research , cancer , gene , medicine , biochemistry , computer science , programming language
Aims: cDNA microarrays have subclassified breast carcinomas into molecular subtypes with oestrogen receptor‐α ( ER ) gene expression as a main marker. The aim was to compare ER expression in 97 patients with operable breast cancer estimated by real‐time reverse transcriptase‐polymerase chain reaction (real‐time RT‐PCR) and by routine immunohistochemistry, and to determine which method was reliable for molecular subtyping in relation to basal‐type keratins and HER2 gene expression. Methods and results: Frozen tumour samples were analysed by real‐time RT‐PCR for the expression of ER , HER2 , keratin 5 and keratin 17 genes. In a group of 27 tumours with a low level of ER mRNA (<1.00), there were eight ER+ cases as assessed by immunohistochemistry, and of 70 cases with a high level of ER mRNA (≥1.00), 26 were ER− by immunohistochemistry ( P = 0.003). Lack of prognostic relevance of ER mRNA level was demonstrated, whereas assessment by immunohistochemistry was related to clinical outcome. Expression of basal keratins and HER2 genes differed significantly between ER+ and ER− tumours based on immunohistochemistry, but not on mRNA level. Conclusions: These results throw doubt on the assessment of ER mRNA as a key factor in the molecular distinction between breast tumours.