Regulation of deoxyribonucleic acid synthesis in proliferating and differentiating trophoblast cells: Involvement of transferrin, transforming growth factor-β, and tyrosine kinases

Gary P. Hamlin, Michael J. Soares*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

34 Citations (Scopus)


This report investigates the regulation of DNA synthesis in trophoblast stem cells and differentiating trophoblast cells. Experiments in this study were performed on the Rcho-1 trophoblast cell line, which was established from a transplantable rat choriocarcinoma. Rcho-1 trophoblast cells can be manipulated to proliferate or differentiate along the trophoblast giant cell pathway. DNA synthesis in quiescent trophoblast stem cells (maintained in serum-free medium) was stimulated by fetal bovine serum and donor horse serum or transferrin to a level approximately 30- and 10-fold above the basal level, respectively. Transferrin and horse serum were ineffective at maintaining trophoblast cell proliferation. In contrast, serum-starved differentiating trophoblast cells synthesize DNA at maximal levels and could not be further stimulated by the addition of exogenous factors. Fetal bovine serum-stimulated proliferation was effectively inhibited by transforming growth factor-β1. Experiments with the tyrosine kinase inhibitor genistein implicate tyrosine kinase involvement in the regulation of DNA synthesis and proliferation in trophoblast stem cells and DNA synthesis in differentiating trophoblast cells. Proliferating and differentiating trophoblast cells differ in their levels of tyrosine kinase activities and express unique tyrosine-phosphorylated proteins. In summary, DNA synthesis and proliferation in trophoblast stem cells are under extrinsic control, whereas DNA synthesis in differentiating trophoblast cells is under intrinsic control. Both mechanisms require tyrosine kinase activity, but the nature of the tyrosine kinase pathways in each process appears to be distinct.

Original languageEnglish
Pages (from-to)322-331
Number of pages10
Issue number1
Publication statusPublished - 1 Jan 1995
Externally publishedYes


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