Lnc-HZ05 regulates BPDE-inhibited human trophoblast cell proliferation and affects the occurrence of miscarriage by directly binding with miR-hz05.

Approximately 15-25% pregnant women end with miscarriage in the world. Environmental BaP (benzo(a)pyrene) and its terminal metabolite BPDE (benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide) may result in the dysfunctions of trophoblast cells, which might further lead to RM (recurrent miscarriage). However, potential mechanisms remain unelucidated. In this work, we identified a novel lnc-HZ05 highly expressed and a novel miR-hz05 lowly expressed in both trophoblast cells exposed to BPDE and human RM tissues. MiR-hz05 reduces FOXO3a mRNA level by weakening its mRNA stability. Lnc-HZ05 increases the expression of FOXO3a by acting as a ceRNA for miR-hz05, and then increases P21 level and reduces CDK2 level. Thus, cell cycle is arrested at G0/G1 phase and trophoblast proliferation is inhibited. Lnc-HZ05 harboring wild-type binding site for miR-hz05, but not its mutant site, could upregulate FOXO3a expression. In normal trophoblast cells, relatively less lnc-HZ05 and more miR-hz05 activate FOXO3a/P21/CDK2 pathway and promote trophoblast proliferation, giving normal pregnancy. In RM tissues and BPDE-treated human trophoblast cells, lnc-HZ05 is increased and miR-hz05 is reduced, both of which suppress this pathway and inhibit cell proliferation, and finally lead to miscarriage. Thus, lnc-HZ05 and miR-hz05 simultaneously regulate cell cycle and proliferation of BPDE-exposed trophoblast cells and miscarriage, providing new perspectives and clinical understandings in the occurrence of unexplained miscarriage.