Expression of E-cadherin and its repressor snail in placental tissue of normal, preeclamptic and HELLP pregnancies

Abstract

Incomplete invasion of extravillous trophoblasts (EVT) is thought to be associated with complications of pregnancy. Snail, a zinc-finger transcription factor represses the transcription of the cell adhesion molecule E-cadherin. The aim of this study was to investigate the expression of E-cadherin and Snail in placental tissue with preeclampsia or HELLP. Placental tissues were obtained from five patients with HELLP syndrome, seven patients with preeclampsia and seven patients after a normal term birth and analysed for Snail and E-cadherin immunoreactivity with specific monoclonal antibodies. Immunohistochemical staining of the placental tissue was analysed using an immunoreactivity score for the evaluation of staining intensity. In preeclamptic EVT, Snail immunoreactivity showed a significant 1.7-fold increase, accompanied by a significant 1.9-fold reduction of E-cadherin immunoreactivity. A 1.7-fold increase of Snail and in parallel a 1.3-fold reduction of E-cadherin was observed in EVT of HELLP placentas although without statistical significance. Loss of E-cadherin can be observed during epithelial-mesenchymal transition (EMT), a key process in normal development and trophoblast differentiation. Snail represses the transcription of E-cadherin triggering a complete EMT. Results obtained in this study showed changes of Snail and E-cadherin immunoreactivity in preeclamptic placentas that could be accompanied with an altered EMT in trophoblasts.