Gold-facilitated in situ hybridization: a bright-field autometallographic alternative to fluorescence in situ hybridization for detection of Her-2/neu gene amplification.

Fluorescence in situ hybridization (FISH) represents an excellent method for profiling gene amplification in situ, but correlation with tissue morphology is difficult because of dark-field visualization. Validation of a bright-field assay for assessment of HER-2/neu gene amplification was investigated. Streptavidin-Nanogold was used to generate bright-field gene copy signals using GoldEnhance gold-based autometallography, catalyzed reported deposition, and a biotin-labeled probe. One hundred cases of invasive breast carcinoma were evaluated for which FISH gene copy results, and mRNA and oncoprotein gene expression, were known. Autometallographic signals were qualitatively evaluable without the use of oil immersion microscopy. Results correlated well with indirect and direct label FISH. Autometallographic gold-based in situ hybridization represents a promising bright-field assay for the assessment of HER-2/neu gene amplification.