To explore the effect and possible mechanism of circSERPINE2 on the proliferation, migration and invasion of trophoblast cells HTR8/SVneo.

The placental tissues of 37 patients with preeclampsia and 37 normal pregnant women were collected. Trophoblast cells HTR8/Svneo were cultured in vitro and transfected with circSERPINE2 small interfering RNA (si-circSERPINE2) or miR-34a-5p mimic or co-transfected with si-circSERPINE2 and miR-34a-5p inhibitor into HTR8/Svneo cells. The expression of circSERPINE2 and miR-34a-5p was defected by qRT-PCR. Cell proliferation was detected by CCK-8 assay and colony formation assay. Cell migration, invasion and expression of E-cadherin and N-cadherin were detected by scratch assay, Transwell assay and Western blot, respectively. Dual-luciferase reporter gene experiment confirmed the targeting relationship between circSERPINE2 and miR-34a-5p. A paired sample t-test or independent sample t-test was used to compare between two groups.One-way analysis of variance was used for multi-group comparison, and the LSD-t test was used for pairwise comparison between groups.

Compared with normal placental tissues, the expression of circSERPINE2 was decreased in the placental tissue of patients with preeclampsia (0.37 ± 0.04 vs 1.00 ± 0.11) ;the expression of miR-34a-5p was increased (3.50 ± 0.28 vs 1.00 ± 0.08) , and the differences were statistically significant (all P < 0.05) . Compared with the si-NC, the circSERPINE2 expression level (0.31 ± 0.03 vs 1.01 ± 0.06) , cell viability, number of clones, number of invasions, scratch healing rate and N-cadherin expression were decreased in the HTR8/Svneo cells transfected with si-circSERPINE2, but the expression of E-cadherin was increased (P < 0.05) . Compared with miR-NC, cell viability, number of clones formed, number of invasions, scratch healing rate and N-cadherin expression were decreased in HTR8/Svneo cells transfected with miR-34a-5p mimic, the expression of miR-34a-5p (3.48 ± 0.32 vs 1.00 ± 0.00) and E-cadherin were increased (all P < 0.05) . circSERPINE2 targeted and negatively regulated miR-34a-5p. Down-regulating miR-34a-5p reversed the inhibitory effect of circSERPINE2 knockdown on HTR8/Svneo cells proliferation, migration and invasion.

circSERPINE2 is down-regulated in placental tissue of preeclampsia patients, and knockdown of circSERPINE2 may inhibit the proliferation, migration and invasion of trophoblast cells by targeting and negatively regulating miR-34a-5p expression.