Real-time reverse transcription-PCR and fluorescence in-situ hybridization are complementary to understand the mechanisms involved in HER-2/neu overexpression in human breast carcinomas

Aims : To evaluate the HER‐2/neu status at the mRNA and DNA level of breast carcinomas and to compare it with HER‐2/neu receptor overexpression by immunohistochemistry (IHC). Methods and results : In 32 invasive breast carcinomas, frozen tissue was available for real‐time detection of HER‐2/neu mRNA...

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Bibliographic Details
Published in:Histopathology 2005-04, Vol.46 (4), p.431-441
Main Authors: Vanden Bempt, I, Vanhentenrijk, V, Drijkoningen, M, Wlodarska, I, Vandenberghe, P, De Wolf-Peeters, C
Format: Article
Language:English
Subjects:
Biological and medical sciences
breast carcinoma
Breast Neoplasms - genetics
Breast Neoplasms - pathology
DNA ploidy
Female
fluorescence in-situ hybridization
Gene Expression Regulation, Neoplastic
Gynecology. Andrology. Obstetrics
HER-2/neu
Humans
immunohistochemistry
In Situ Hybridization, Fluorescence - methods
Investigative techniques, diagnostic techniques (general aspects)
Mammary gland diseases
Medical sciences
Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques
Reagent Kits, Diagnostic - standards
real-time RT-PCR
Receptor, ErbB-2 - genetics
Reproducibility of Results
Reverse Transcriptase Polymerase Chain Reaction - methods
RNA, Messenger - genetics
RNA, Messenger - metabolism
Tumors
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Summary:Aims : To evaluate the HER‐2/neu status at the mRNA and DNA level of breast carcinomas and to compare it with HER‐2/neu receptor overexpression by immunohistochemistry (IHC). Methods and results : In 32 invasive breast carcinomas, frozen tissue was available for real‐time detection of HER‐2/neu mRNA levels by reverse transcription‐polymerase chain reaction (RT‐PCR). Corresponding paraffin sections were examined by IHC and fluorescence in‐situ hybridization (FISH). Thereby, different IHC and FISH procedures were compared. Using microwave epitope retrieval, all 32 cases scored 3+ on IHC, whereas only 28 out of 32 cases scored IHC 3+ using water bath epitope retrieval. All of these 28 cases showed increased levels of HER‐2/neu mRNA. Dual‐colour FISH analysis showed corresponding gene amplification in all 28 cases, with two cases showing a peculiar amplification pattern. In the remaining four cases, scoring IHC 2+ using water bath epitope retrieval, mRNA levels were not elevated. Three cases did not have gene amplification and one case showed low‐level HER‐2/neu gene amplification. All four carcinomas showed chromosome 17 polysomy. Conclusions : Real‐time RT‐PCR is accurate in selecting breast carcinoma cases scoring 3+ by IHC with high‐level gene amplification. Results obtained by dual‐colour FISH suggest that mechanisms leading to HER‐2/neu receptor overexpression may be different between carcinomas scoring 2+ and 3+ on IHC, with polysomy 17 found in the former and gene amplification in the latter.
ISSN:0309-0167
1365-2559
DOI:10.1111/j.1365-2559.2005.02112.x