The Effects Of MiR-124on The Malignant Phenotype Of Endometrial Carcinoma And Relative Machanisms By Targeting STAT3

Objective: To explore the expression of miR-124in the EC tissues and its effects onthe malignant phenotypes of EC cells, providing new avenues for EC diagnostic andtreatment regiments in the future.Methods: Firstly, we explored the expression of miR-124in35paired EC tissuescompared with the adjacent normal tissues using the stem-loop RT-PCR assays.Secondly, we explored the effects of miR-124on the cell proliferation, cell cycleprogression, apoptosis, migration and invasion of HEC-1B cells through the CCK-8assays, flow cytometry technology, wound healing assays and transwell assays,respectively. To further identify the mechanisms involved in miR-124-mediatedbiological behavior, miR-124putative targets were searched using target predictionprograms, and then verified using dual-luciferase reporter and western-blotting assays;Finally, to explore the role of putative target gene in miR-124-mediated tumorsuppression, we treated HEC-1B cells transfected with miR-124before with IL-6cytokine and explored the effects on the malignant phenotype.Results: The expression level of miR-124in EC tissues is significantlydown-regulated in EC tissues comparing with the normal control, suggesting thatmiR-124functions as a tumor suppressor in EC; Restored expression of miR-124significantly suppressed proliferation, migration and invasion, arrested cell cycleprogression, and induced early apoptosis of HEC-1B cells; Target predictionprograms identified signal transducer and transcription activator3(STAT3) to be aputative target gene. Dual-luciferase reporter and western-blotting assays demonstratethat miR-124significantly suppressed that transcription of STAT3. The mRNA andprotein levels of STAT3in HEC-1B cells transfected with miR-124were significantlyreduced; Moreover, knocking down the expression of STAT3in HEC-1B cellsinduced cell growth retardation, apoptosis and suppressed cell migration as well asinvasion, which paralleled the tumor suppressive effects induced by miR-124restoration, suggesting that miR-124functions as a tumor suppressor in EC through,at least partially targeting STAT3; To test this suspect, we treated HEC-1B cells transfected with miR-124before with IL-6cytokine and explored the effects on themalignant phenotype. In accord with this hypothesis, treatment with IL-6cytokinerescued p-STAT3expression and suppression of malignancy phenotype in HEC-1Bcells transfected with miR-124mimics, albeit less effectively than achieved bymiR-124overexpression. These results demonstrate that miR-124functions as atumor suppressor partially through suppressing activity of the STAT3signalingpathway.Conclution: This finding not only helps us understand the molecular mechanism ofendometrial carcinogenesis, but also gives us a strong rationale to further investigatemiR-124as a potential biomarker and therapeutic target for EC.