ONCOGENE AND TUMOR-SUPPRESSOR GENE-PRODUCTS DURING TROPHOBLAST DIFFERENTIATION IN THE FIRST-TRIMESTER

Tumour suppressor genes may have a role in the control of trophoblast cell population expansion as trophoblast invasion occurs. To investiga te this hypothesis, the location of tumour suppressor gene and protoon cogene products were studied at various stages of trophoblast differen tiation and invasion. Trophoblast and decidua were obtained from eight women having a therapeutic termination of pregnancy. Immunohistochemi stry was used to localize the products of c-myc, c-erB-2, RB, BCL-2, P 21, and P53 genes and anticytokeratin was used to identify fetal cells amongst the maternal decidual cells. The most differentiated and furt hest invading trophoblast cell type, the multinucleated trophoblast, e xpressed a combination of genes which may indicate a high apoptotic ra te. The other fully differentiated trophoblast, the syncytiotrophoblas t, expressed BCL-2 suggesting protection from apoptosis. The co-occurr ence of proto-oncogenes and the products of tumour suppressor genes in first trimester trophoblast suggests an important role not only in ne gative regulation of cellular invasion but also in population expansio n through the presence of oncogenes and anti-apoptotic proteins.