MiR-376c-3p Affects The Proliferation And Invasion Of Medullary Thyroid Cancer Cells By Inhibiting The Expression Of HBEGF

Background: Medullary Thyroid carcinoma(Medullary Thyroid Carcinomas,MTC)is poorly differentiated thyroid malignant tumor that is characterized by lymph nodes and distant metastasis.The therapeutic effect in patients with advanced MTC is not satisfactory and the fatality rate of the patients is more higher.However,the metastasizing mechanism of MTC has not been fully elucidated.Micro RNA(mi RNA)regulate the translation and expression of related proteins of target genes at the post-transcriptional level through complete or incomplete binding of messenger RNA(m RNA)of the target genes,which further regulate cell growth,differentiation,proliferation,cycle and apoptosis.HBEGFF(heparin-binding epidermal growth factor-like growth factor)is a member of the epidermal growth factor family,and is involved in the occurrence and development of tumors.Previous studies have found that the expressions of mi R-376c-3p and HBEGF in MTC were down-regulated and up-regulated,respectively.Therefore,we hypothesize that mi R-376c-3p post-transcriptional negative regulation of HBEGF expression is involved in the growth and metastasis of MTC cells.Objectives: The main purpose of this study was to detect the effect of mi R-376c-3p on the proliferation,migration and invasion of MTC cells,and to elucidate the mechanism of the interaction between mi R-376c-3p and its downstream target gene,HBEGF,on the proliferation,migration and invasion of MTC cells.Methods: Mi R-376c-3p mimic,mi R-376c-3p inhibitor and corresponding negative controls(NC-mimic or NC-inhibitor)were designed and synthesized using the Gene Pharma.The Cell Counting Kit-8(CCK-8)and soft agar colony formation assay were applied to evaluate the proliferation of transfected MZ-CRC-1 cells.Wound healing and Transwell assay were employed to evaluate MTC cell migration and invasion,respectively.Luciferase assay was performed to validate the downstream target of mi R-376c-3p in MZ-CRC-1 cells.Quantitative RT-PCR(q RT-PCR)was used to detect mi RNA abundance of key genes.Western blot technique was used to analyze protein levels of HBEGF,E-cadherin,ZO-1,N-cadherin and vimentin.Results:(1)The viability,migration and invasion of MZ-CRC-1 cells were inhibited by mi R-376c-3p mimic;(2)The expression of N-cadherin and Vimentin was downregulated and the expression of E-cadherin and ZO-1 was upregulated by mi R-376c-3p mimic in MZ-CRC-1 cells;(3)Luciferase reporter assay revealed that mi R-376c-3p could bind 3’ untranslated region of HBEGF,of which overexpression nearly nullified the inhibitory effects of proliferation induced by mi R-376c-3p mimic in MTC cells.Conclusions: mi R-376c-3p suppreses the proliferation,migration and invasion of MTC cells via targeting and downregulating HBEGF,suggesting that mi R-376c-3p may play an important role in the treatment of MTC.The present study may help to elucidate the mechanism of migration and invasion in MTC,and provide new insights and methods to treat MTC patients.