Linc-RNA-RoR acts as a "sponge" against mediation of the differentiation of endometrial cancer stem cells by microRNA-145

Abstract

Objectives: Recently, large intergenic non-coding ribonucleic acids-RoR (linc-RoR) was reported to regulate expression of core stem cell transcription factors (TFs), but its role in endometrial tumorsphere is still unknown.

Methods: Fluorescence in situ hybridization (FISH) was used to characterize linc-RoR expression in ETs. After construction of adenovirus vectors carrying green fluorescent protein (GFP), these vectors were transfected into ETs to estimate the effects of overexpression or knocked down expression of miR-145, linc-RoR or Dicer. Flow cytometry was employed to ascertain transfection efficiency, and real-time polymerase chain reaction (RT-PCR) was employed to compare their levels. Colony formation was analyzed using cultured gelatin-coated tissue cultures. miR-145 potential targeting sites in linc-RoR were mutated using a site-directed mutagenesis kit to verify its competing endogenous RNA (ceRNA) effects.

Results: Expression of linc-RoR and core stem cell TFs was associated with the pluripotent state of ETs, whereas miR-145 expression increased after ET differentiation. Greater expression of miR-145 could lead to down-regulation of linc-RoR and core TFs, and decreased colony formation. Converse effects could be achieved after knocked-down miR-145 expression. The effects of miR-145 could be eliminated after increasing the expression of linc-RoR in ETs or mutated targeted sequences in linc-RoR. Knocked-down Dicer expression could improve the expression of linc-RoR and core TFs.

Conclusions: Linc-RoR is a ceRNA and acts as a miR-145 "sponge" to inhibit mediation of the differentiation of ETs by miR-145. These results suggest that linc-RoR has an important role during endometrial carcinogenesis.

Keywords: Endometrial cancer; Tumorsphere; linc-RoR; miR-145.