Oncogene and tumour suppressor gene products during trophoblast differentiation in the first trimester

Tumour suppressor genes may have a role in the control of trophoblast cellpopulation expansion as trophoblast invasion occurs. To investigate thishypothesis, the location of tumour suppressor gene and proto-oncogeneproducts were studied at various stages of trophoblast differentiation andinvasion. Trophoblast and decidua were obtained from eight women having atherapeutic termination of pregnancy. Immunohistochemistry was used tolocalize the products of c-myc, c-erB- 2, RB, BCL-2, P21, and P53 genes andanti-cytokeratin was used to identify fetal cells amongst the maternaldecidual cells. The most differentiated and furthest invading trophoblastcell type, the multinucleated trophoblast, expressed a combination of geneswhich may indicate a high apoptotic rate. The other fully differentiatedtrophoblast, the syncytiotrophoblast, expressed BCL-2 suggesting protectionfrom apoptosis. The co-occurrence of proto-oncogenes and the products oftumour suppressor genes in first trimester trophoblast suggests animportant role not only in negative regulation of cellular invasion butalso in population expansion through the presence of oncogenes andanti-apoptotic proteins.