Objective:
To investigate the mechanism of action involved in LINC01128 in serum and decidua tissue of recurrent spontaneous abortion (RSA).

Material and methods:
49 RSA patients and 50 pregnant women with normal termination of pregnancy were included in the study. Following curettage, decidual tissues and serum samples were stored at -80 °C. Real-time quantitative PCR (RT-qPCR) was performed to detect the expression of genes as well as vascular endothelial growth factor (VEGF) and matrix metalloprotein 2/9 (MMP2 and MMP9). A dual-luciferase report assay (DLR) was performed to verify the targetting interactions between miR-515-5p and LINC01128 or DNA methyltransferase 1 (DNMT1). Cell Counting Kit-8 (CCK8) detected cell proliferation, Transwell observed migration, and flow cytometry recorded apoptosis.

Results:
RSA patients contained low LINC01128 and high miR-515-5p in serum and metaphase tissue, and the expression of both was negatively correlated. DLR results showed that these two genes have an antagonistic targetting relationship. LINC01128 could inhibit the expression of miR-515-5p, promote the proliferation and migration of trophoblast cells, reduce apoptosis, and increase the expression of vascular endothelial growth factor, MMP2 and MMP9. DNMT1 is a target gene of miR-515-5p, which is lowly expressed in serum and metaphase tissue of RSA patients, and negatively correlates with miR-515-5p. The expression level of DNMT1 was increased in trophoblast cells transfected with LINC01128.

Conclusions:
The LINC01128/miR-515-5p/DNMT1 regulatory axis in trophoblast cells may be associated with the development of RSA.