Background and Aims:Long non-coding RNAs(lncRNAs)can indirectly regulate the transcription and degradation of downstream mRNAs by binding to microRNAs(miRNAs),thereby regulating the occurrence and development of tumors.LncRNA FOXP4-AS1 is a recently discovered tumor-related biomarker,playing different regulatory roles in different tumors.Our previous study found that FOXP4-AS1 is downregulated in papillary thyroid carcinoma(PTC)and is a tumor suppressor.In addition,bioinformatics analysis predicted that miR-507 could complementarily bind to FOXP4-AS1.Therefore,this study was conducted to explore the role and mechanism of FOXP4-AS1 in inhibiting the growth of PTC cells by regulating miR-507 and its downstream target mRNA.Methods:The expression levels of miR-507 in thyroid cancer(TC)and its clinical significance were analyzed using the TCGA database.The expression levels of miR-507 in PTC cell lines(TPC-1,K1)and normal thyroid follicular epithelial cells(Nthy-ori3-1)were detected by qRT-PCR and the changes in miR-507 expression levels after overexpression and knockdown of FOXP4-AS1 were measured.The dual-luciferase reporter gene assay was used to verify the targeting relationship between FOXP4-AS1 and miR-507.miR-507 mimic and inhibitor were transfected into stable cell lines overexpressing or knockdown of FOXP4-AS1,and changes in cell function were detected by CCK-8 assay,colony formation assay,Transwell assay,scratch healing assay,and flow cytometry.Bioinformatics analysis was used to predict the downstream targets of miR-507,and qRT-PCR was used for validation.Results:Analysis of the TCGA database showed that miR-507 was highly expressed in TC,and its expression level was associated with clinical pathological features such as clinical stage,T stage,and extrathyroidal infiltration(all P＜0.05).qRT-PCR results showed that compared with Nthy-ori3-1 cells,miR-507 was highly expressed in both PTC cell lines,and the expression levels of miR-507 in both PTC cells changed inversely after overexpression and knockdown of FOXP4-AS1(all P＜0.05).The results of the dual-luciferase reporter gene assay showed that FOXP4-AS1 targeted and inhibited the expression of miR-507.Cell function experiments and functional recovery experiments showed that after overexpression of FOXP4-AS1,the proliferation,migration,and anti-apoptotic ability of PTC cells were significantly weakened,and these functions were restored after the addition of miR-507 mimic(all P＜0.05);knockdown of FOXP4-AS1 in PTC cells resulted in a significant increase in proliferation,migration,and anti-apoptotic ability,and these functions were restored after the addition of the miR-507 inhibitor(all P＜0.05).Bioinformatics prediction and GO,KEGG enrichment analysis results showed that miR-507 downstream may involve CAMK4.qRT-PCR validation results showed that the expression level of CAMK4 changed in the same direction as the expression level of FOXP4-AS1,and its expression level changed inversely with the addition of miR-507 mimic and inhibitor(all P＜0.05).Conclusion:FOXP4-AS1 can target miR-507,and may regulate the proliferation,migration,and apoptosis of PTC cells by inhibiting the expression level of miR-507 through a sponge mechanism.CAMK4 may be one of the downstream targets of the FOXP4-AS1/miR-507 pathway in exerting its anticancer effects.
国家科技期刊平台
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