MESSENGER-RNA EXPRESSION OF COMPONENTS OF THE INSULIN-LIKE-GROWTH-FACTOR SYSTEM IN BREAST-CANCER CELL-LINES, TISSUES, AND METASTATIC BREAST-CANCER CELLS

IGF-1 and 2 are thortgltt to be important growth factors for. breast c ancer: However, gene expression of IGFs ol IGF receptors in breast can cer tissues, and especially in metastatic breast cancer cells, is not well known. Expression of mRNA encoding for IGF-1, IGF-2 IGF-receptor 1 and 2, IGF binding proteins-1 to -6, insulin receptor and insulin wa s determined in the NIH MCF-7 breast cancer-cell line, in specimens fr om breast cancer tissues, and in 6 primary breast cancer cell cultures obtained from metastatic breast cancel; using rT-PCR technique. Speci fic mRNA sequences encoding for IGF-receptor 1 and 2, IGFBP-2, -4 and insulin receptor were identified in all cell cultures and most of the tissue specimens. Though in most of the tissues additional expression of IGF-1 and IGF-2 was detected, there was no mRNA encoding for these proteins in MCF-7 cell cultures as well as in the primary cell culture s of metastatic breast cancers. In none of our specimens mRNA encoding for IGFBP-1, -3, -5, -6 and insulin? was detectable. IGF-receptor exp ression in cancer tissues and metastatic breast cancer cells supports the hypothesis that IGFs increase tumor cell proliferation in vive. Ex pression of IGF-1 and IGF-2 in tumor, tissues but not in cancer cell c ultures indicates an IGF expression located predominantly in stromal p arts of cancer tissues.