NUMERICAL ABERRATIONS OF CHROMOSOME-17 IN INTERPHASE CELL-NUCLEI OF BREAST-CARCINOMA CELLS - LACK OF CORRELATION WITH ABNORMAL EXPRESSION OF P53, NEU AND NM23 PROTEIN

The genes for p53, neu (c-erbB-2) and nm23 are all located on chromoso me 17. Abnormal expression of their protein products is an important p rognostic parameter. The aim of this study was to investigate if numer ical aberrations of chromosome 17 are reflected in the expression of t hese markers. The immunohistochemical expression was analysed on histo logical specimens from 33 breast carcinomas. In situ hybridization (IS H) was performed on interphase cell nuclei in air-dried fine-needle as pirates from the same cases using a digoxigenin-labelled a-satellite p robe for chromosome 17. ISH for chromosome 6, 7 and 12 was used additi onally to give an estimate of ploidy. Of the carcinomas 76% were aneup loid, and numerical abnormalities of chromosome 17 were found in 34%. Abnormal p53 protein was expressed in 15% (five cases). All of these w ere aneuploid, but only one of them revealed aneusomy of chromosome 17 . Neu overexpression was found in 18% of the tumours (six cases). Five of these were aneuploid, whereas two were aneusome for chromosome 17. Four cancers showed full (normal) expression of nm23 protein, whereas 29 had reduced expression. Reduced expression was found in 23 of 25 a neuploid tumours. Numerical aberrations of chromosome 17 were found eq ually in carcinomas with reduced and full nm23 protein expression. Abn ormal numbers of chromosome 17 seem only to have a minor impact on the se markers and are not reflected significantly in their expression.