MEASURING C-ERBB-2 ONCOGENE AMPLIFICATION IN FRESH AND PARAFFIN-EMBEDDED TUMORS BY COMPETITIVE POLYMERASE CHAIN-REACTION

We present an original application of competitive polymerase chain rea ction (PCR) for measuring oncogene amplification in DNA from human tum ors by simultaneous PCR amplification of genomic DNA with fixed amount s of an internal standard (competitor DNA). Competitors share the same sequence as the target genes but contain an additional 15- to 20-base -pair insert, which allows resolution of the amplified products after polyacrylamide gel electrophoresis and ethidium bromide staining. The gene copy number is derived from the ratio between the intensities of the bands corresponding to the amplified products. Using this procedur e, we measured c-erbB-2 amplification in breast and bladder carcinomas in both fresh tumor tissues and paraffin-embedded tissue samples and assessed the precision, sensitivity, and accuracy of the assay. Compet itive PCR is a simple, reliable, and accurate method for the evaluatio n of c-erbB-2 amplification and is potentially suitable for use in the clinical laboratory.