Downregulation of lncRNA IGF2-AS-encoded peptide induces trophoblast - cycle arrest.

Research Question: lncRNA IGF2-AS may be related to early pregnancy loss. Does lncRNA IGF2-AS affect trophoblast cell growth? The aim of the present study was to verify that lncRNA IGF2-AS encodes a polypeptide, IGF2-AS-168aa, and to study its role in the pathogenesis of trophoblasts.

Design: A small interfering RNA targeted to the IGF2-AS gene (si-IGF2-AS) was designed and transfected into JEG-3 and JAR cells for in-vitro gene silencing. Quantitative polymerase chain reaction and western blotting were used to determine lncRNA IGF2-AS levels in experimental cells. After IGF2-AS suppression, MTT assay was used to assess cell proliferation and apoptosis was determined by flow cytometry. Target gRNA IGF2-AS-gRNA was designed for knockout conducted the corresponding mRNA. HEK293T cells were transfected with the identified positive clone vectors. Finally, IGF2-AS-168aa was analysed by western blotting after the protein-coding region of the IGF2-AS gene was knocked out by CRISPR/Cas9 gene-editing technology.

Results: lncRNA IGF2-AS and IGF2-AS-168aa were significantly downregulated in JEG-3 and JAR cells transfected with si-IGF2-AS (lncRNA IGF2-AS: JAR: NC versus small interfering RNA (siRNA)-1: P = 0.019 NC versus siRNA-2: P = 0.013; JEG-3: NC versus siRNA-1: P = 0.001 NC versus siRNA-2: P = 0.004) (IGF2-AS-168aa: JAR: NC versus siRNA-1: P = 0.030 NC versus siRNA-2: P = 0.018; JEG-3: NC versus siRNA-1: P = 0.004 NC versus siRNA-2: P = 0.001). IGF2-AS gene was incapable of encoding IGF2-AS-168aa after the coding region was successfully knocked out in HEK293T cells. Flow cytometry and the MTT assay revealed that IGF2-AS gene silencing led to cell cycle block in the G1 phase, markedly decreasing cell proliferation and increasing apoptosis.

Conclusion: The IGF2-AS gene encoded a peptide with a potential function in trophoblast cell cycle arrest.