Identification by subtractive hybridization of a spectrum of novel and unexpected genes associated with in vitro differentiation of human cytotrophoblast cells.

We have previously demonstrated that epidermal growth factor (EGF), colony stimulating factor-1 (CSF-I), and granulocyte-monocyte colony stimulating factor (GMCSF) stimulate, while transforming growth factor beta 1 (TGF beta 1) inhibits, cytotrophoblast differentiation. To identify genes mediating EGF induced differentiation, we constructed a subtracted cDNA library between undifferentiated cytotrophoblast and differentiating cytotrophoblast. We identified six novel genes and four known syncytial products alpha-human chorionic gonadotrophin (alpha hCG) pregnancy-specific beta 1-glycoprotein, 3 beta-hydroxysteroid dehydrogenase, and plasminogen activator inhibitor type 1 whose mRNAs increased during differentiation. Ten other genes were identified whose mRNAs increased during differentiation. Five of these (keratin 19, calcreticulin, heat shock protein 27, serum and glucocorticoid-regulated kinase and adrenomedullin) were not previously reported to be expressed in placenta. Five other genes known to be expressed in placenta were identified. keratin 8, fibronectin, mitochondrial ATP synthase, 1119, and cytosolic copper-zinc superoxide dismutase (SOD-1). Several of these genes may have regulatory functions in trophoblast differentiation.