VALIDATION OF A DIFFERENTIAL PCR AND AN ELISA PROCEDURE IN STUDYING HER-2 NEU STATUS IN BREAST-CANCER/

HER-2/neu oncogene status and total cellular p185(HER-2) content were simultaneously analyzed in 415 invasive breast-cancer specimens by dif ferential PCR and ELISA respectively. Mathematical analysis of the dat a led us to establish a cut-off value of 1.7 for the ratio between the intensity of the HER-2/neu gene band and the reference gene band, to consider the HER-2/neu gene amplified, and of 260 fmol/mg protein, to consider p 185(HER-2) over-expressed. Of the 415 tumors studied, 15% s howed a diverse degree of HER-2/neu gene amplification. Of these tumor s, 87% showed over-expression of the p185(HER-2). Of the remaining 352 specimens that did not display HER-2/neu gene amplification, 97% show ed no p185(HER-2) over-expression (P < 0.0001). In 40 selected samples with a p185(HER-2) level lower than 260 fmol/mg protein, the degree o f p185(HER-2) phosphorylation was very low or undetectable. Conversely , 38 of 46 selected tumors with a p185(HER-2) level higher than 260 fm ol/mg protein exhibited a considerable degree of p185(HER-2) phosphory lation (P < 0.0001). Our data suggest that: (i) differential PCR and E LISA, which are relatively simple procedures, give similar information on HER-2/neu status in breast cancer; and (ii) given the large series analyzed, the cutoff values established can be considered as safe val ues for determining whether, in a given tumor, the HER-2/neu oncogene is amplified or p185(HER-2) is over-expressed. (C) 1996 Wiley-Liss, In c.