LncRNA MONC Suppresses the Malignant Phenotype of Endometrial Cancer Stem Cells by Regulating the MiR-636/GLCE Axis

Background: Emerging evidence shows that abnormal expression of long non-coding RNA is involved in the occurrence and development of various tumors. LncRNA MONC is abnormally expressed in head and neck squamous cell carcinoma (HNSCC), lung cancer, colorectal cancer, and acute megakaryocytic leukemia, but the biological function and potential regulatory mechanism of MONC in endometrial cancer stem cells (ECSCs) and endometrial cancer cells (ECCs) have not been studied. In this study, we aimed to explore the tumor suppressive effect and mechanism of MONC in regulating ECSCs and ECCs. Methods: The expression of genes was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The expression of proteins was detected by Western blot. The interplay of LncRNA-miRNA-mRNA was verified using the luciferase assay. The growth rate of ECSC spheroids was detected by sphere formation assay. Cell proliferation was detected by CCK-8 assay. The cell invasion was detected by transwell invasion assay. Cell cycle was detected by Cell cycle analysis.Cell apoptosis was detected by the Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double-staining assay. Animal study was conducted to evaluate the effect of MONC combined with miR-636 on tumor growth in vivo. Results: Low MONC expression in endometrial carcinoma (EC), which directly inhibits the malignant biological behavior of ECSCs and ECCs by directly inhibiting miR-636. Simultaneously, miR-636 may indirectly reduce the expression of MONC. Down-regulation of miR-636 may promote GLCE expression by targeting the 3'-untranslated region (UTR) of the downstream gene GLCE, thereby inhibiting the progression of ECSCs. MONC combined with miR-636 inhibited the Notch signaling pathway and tumor epithelial-to-mesenchymal transition (EMT) process. In addition, we verified the tumor suppressive effect of MONC in nude mice, miR-636 can rescue the tumor suppressive effect of overexpressing MONC, and this effect is more obvious in ECSC. Conclusion: MONC inhibits the malignant phenotypes of ECSCs and ECCs by regulating the miR-636/GLCE axis. The MONC/miR-636/GLCE axis may provide novel treatment avenues for human EC.