ANALYSIS OF THE IGF-II RECEPTOR GENE COPY NUMBER IN BREAST-CARCINOMA

Insulin and the insulin-like growth factors (IGFs) may be important re gulators of breast cancer growth. The IGF-II receptor is identical to the mannose 6-phosphate (Man-6-P) receptor, which is involved in lysos omal enzyme pathways. In order to determine whether the Man-6-P/IGF-II receptor gene copy number is altered in breast cancer we analysed spe cimens of invasive breast carcinoma from 51 patients by Southern blott ing. No amplification of the receptor gene was observed whatever the c linical presentation of the tumour and irrespective of a concomitant a mplification of c-erbB2 or int-2 genes in several tumours. As indicate d by Northern blotting, the gene is transcribed in breast tumour tissu es and non-tumour breast tissue. These results suggest that the recept or gene is stable in breast carcinoma and that, if anything, the recep tor involvement in breast cancer progression may be the result of a di sregulation of its expression at a post-transcriptional or post-transl ational level.