Chromogenic Tissue-Based Methods for Detection of Gene Amplifications (or Rearrangements) Combined with Protein Overexpression in Clinical Samples

Abstract

Immunohistochemistry (IHC) is a well-established, tissue-based assay for the visualization of target proteins. For analysis of DNA targets, chromogenic in situ hybridization (CISH) applications have significant advantages over traditional fluorescence in situ hybridization (FISH). CISH slides can be analyzed using a regular light microscope, while FISH slides require the use of a specialized fluorescence microscope in a dark room. CISH slides allow observers to correlate the gene status (gene amplifications, gene rearrangements, and gene deletions) in the context of tissue morphology better than FISH slides. Recently, a combination of IHC and CISH assays (gene-protein assay, GPA) was developed to study the relationship between gene status and protein expression on the same tissue section. CISH and GPA applications can be optimized using an automated tissue slide processing system to generate reproducible results for a long and complex assay protocol. GPA applications are an ideal approach for tumor status and heterogeneity analyses for research and clinical investigations.