C19MC microRNAs regulate the migration of human trophoblasts.

Early in pregnancy, trophoblast invasion into the decidua and inner myometrium is essential for establishment of proper implantation, maternal-fetal exchange, and immunological tolerance of the feto-placental allograft. Unlike villous trophoblasts (VTs), extravillous trophoblasts (EVTs) are unique in their capacity to invade the maternal decidua and myometrium. The largest human microRNA (miRNA) gene cluster, the chromosome 19 miRNA cluster (C19MC), is expressed almost exclusively in the placenta and, rarely, in certain tumors and undifferentiated cells. In the work reported here, we found that the expression of C19MC miRNAs is higher in VTs than in EVTs. Using a bacterial artificial chromosome (BAC)-mediated overexpression of C19MC miRNAs in an EVT-derived cell line, which does not naturally express these miRNAs, we found that C19MC miRNAs selectively attenuate cell migration without affecting cell proliferation or apoptosis. A microarray analysis revealed that C19MC miRNAs regulate target transcripts related to cellular movement. Our data also implicated a specific C19MC member, miR-519d, indirectly regulating the EVT invasive phenotype by targeting CXCL6, NR4A2 and FOXL2 transcripts through a 3'UTR miRNA-responsive element. Together, our data suggest a role for C19MC miRNAs in modulating the migration of EVTs.