Comparison of automated silver enhanced in situ hybridization and fluorescence in situ hybridization for evaluation of epidermal growth factor receptor status in human glioblastomas

Abstract

The epidermal growth factor receptor (EGFR) is amplified in approximately 40% of glioblastomas making it a compelling molecular target for therapy. Before starting a therapy targeting the EGFR pathway, accurate determining of EGFR status is a prerequisite. We evaluated the reliability of the novel automated silver enhanced in situ hybridization for the detection of EGFR gene amplification in human glioblastomas. EGFRamplification status was assessed in 93 cases of glioblastoma by silver enhanced in situ hybridization and compared with results of fluorescence in situ hybridization and immunohistochemistry. In a second cohort, silver enhanced in situ hybridization status was correlated with EGFR gene expression data. The EGFR gene was amplified in 25/90 tumours (28%) by silver enhanced in situ hybridization, and in 28/93 tumours (30%) by fluorescence in situ hybridization. The concordance rate for silver enhanced in situ hybridization and fluorescence in situ hybridization was 98%. Two glioblastomas were scored as being amplified by fluorescence in situ hybridization but not by silver enhanced in situ hybridization. Polymerase chain reaction-based EGFRamplification data were highly correlated with EGFR silver enhanced in situ hybridization. Altogether, 81 of 91 cases (89%) showed positivity for EGFR expression by immunohistochemistry. Although EGFR protein over expression was associated with gene amplification (r ¼ 0.40, Po0.001), there were 29 of 91 cases that showed a high EGFR protein level and no EGFR amplification by fluorescence in situ hybridization. The high concordance rate of silver enhanced in situ hybridization and fluorescence in situ hybridization for the detection of EGFR amplification in paraffin-embedded glioblastomas samples demonstrates that silver enhanced in situ hybridization is a valid and attractive alternative to fluorescence in situ hybridization. Silver enhanced in situ hybridization combines the advantages of bright field microscopy with fully automated analysis in a costeffective way thereby emphasizing its use for routine application in surgical pathology.

Differential expression of Yes-associated protein is correlated with expression of cell cycle markers and pathologic TNM staging in non–small-cell lung carcinoma☆

“…SISH staining can be analyzed by standard light microscopy and allows permanent storage of slides. Recently, a high concordance rate between SISH and FISH (98%) for the detection of EGFR gene amplification in paraffin-embedded glioblastoma samples has been reported [23].…”

“…However, limitations of FISH include rapid signal loss at room temperature and difficulty in distinguishing between tumor cells and surrounding normal cells. SISH has been reported to represent an attractive alternative to FISH and was used for EGFR copy number analysis in this study [23]. SISH staining can be analyzed by standard light microscopy and allows permanent storage of slides.…”

Hybridization for human epidermal growth factor receptor 2 testing in gastric carcinoma: a comparison of fluorescence in-situ hybridization with a novel fully automated dual-colour silver in-situ hybridization method

“…were studied, both methods showed very low failure rates (data not shown). These results are consistent with previous reports on failure rates for epidermal growth factor receptor (EGFR) SISH versus FISH 23 …”

Out of the darkness and into the light: bright field in situ hybridisation for delineation ofERBB2(HER2) status in breast carcinoma

“…Recently, published studies have used chromogenic in situ hybridisation as a means of assessing platelet-derived growth factor receptor A in gliomas,35 determining amplification of the epidermal growth factor receptor ( EGFR ) gene in anal squamous lesions,36 and correlating the EGFR gene copy number with therapy response in colorectal cancers 37. Furthermore, the use of silver-enhanced in situ hybridisation to evaluate EGFR status in human glioblastomas has demonstrated strong concordance with FISH and gene expression data 38. The principles of various bright field technologies in use today, along with their benefits and limitations, are described below.…”