QUANTITATION OF C-ERBB-2 MESSENGER-RNA BY COMPETITIVE REVERSE TRANSCRIPTASE-POLYMERASE CHAIN-REACTION

The overexpression of the c-erbB-2 gene has been reported as an indepe ndent prognostic factor for the progressions of primary human adenocar cinomas such as breast cancer, although there are some controversies a nd overexpression rate are variable (10 similar to 50%). Both the cont roversies on the prognostic value and the varible overexpression rate may result from interpersonal variations in the immunohistochemical qu antitation of the c-erbB-2 gene product or the heterogeneity of the et iology of breast cancers. To clarify this point, we designed an accura te quantitation method of c-erbB-2 mRNA with minimal interpersonal var iations. We set up the competitive reverse transcriptase-polymerase ch ain reaction method for high sensitivity because the clinical samples are small biopsy specimens in many cases. With our method, the overall sensitivity was 50 times or more greater than that of the ribonucleas e protection assay. We expect that our method is helpful in establishi ng the clinical meaning of c-erbB-2 overexpression in primary human ad enocarcinomas, including breast cancers, and also enables-the levels o f c-erbB-2 mRNA in small surgical samples such as biopsy specimens and lymph nodes to be assessed without interpersonal variation.