LAUSR

ABSTRACT Deficiency in trophoblast invasion is causally linked to the pathogenesis of preeclampsia. Tumor necrosis factor‐alpha (TNF‐&agr;) shows the ability to suppress the invasiveness of trophoblasts, while cysteine‐rich 61 (Cyr61) exerts an opposite function in trophoblast invasion. This study was designed to check the hypothesis that cysteine‐rich 61 (Cyr61) may be involved in the anti‐invasive activity of TNF‐&agr; in trophoblasts. To this end, we examined the effect of TNF‐&agr; treatment on Cyr61 expression in HTR‐8/SVneo trophoblast cells and investigated the mechanism for the regulation of Cyr61 by TNF‐&agr;. Gain‐of‐function experiments were performed to clarify the role of Cyr61 in TNF‐&agr;‐dependent suppression of trophoblast invasion. It was found that TNF‐&agr; at 1 and 10 ng/mL reduced Cyr61 protein levels by 30 and 80%, respectively, in HTR‐8/SVneo cells, but did not affect the mRNA expression of Cyr61. Mechanistically, microRNA (miR)‐145‐5p was stimulated by TNF‐&agr; and negatively regulated the expression of Cyr61 via interaction with its 3′‐untranslated region. Functionally, overexpression of miR‐145‐5p significantly impaired the migration and invasion of HTR‐8/SVneo cells. Depletion of miR‐145‐5p rescued HTR‐8/SVneo cells from TNF‐&agr;‐mediated invasion suppression, which coincided with prevention of Cyr61 downregulation by TNF‐&agr;. In addition, overexpression of Cyr61 partially restored the invasion of HTR8/SVneo cells co‐transfected with miR‐145‐5p mimic or exposed to TNF‐&agr;. Taken together, miR‐145‐5p‐mediated downregulation of Cyr61 is required for the anti‐invasive effect of TNF‐&agr; on trophoblasts.