| Background:Thyroid cancer is a common endocrine malignancy with increasing incidence year by year.The main pathological type is papillary thyroid carcinoma（PTC）.Late-stage PTC has a poor prognosis due to its invasiveness and metastasis.In recent years,great progress has been made in the clinical detection and treatment of PTC,but effective diagnosis and treatment methods still need to be further explored.Several scientific studies have shown that circular RNA（circRNA）plays a key role in a variety of different diseases due to its unique biological characteristics.The role of circRNA in PTC needs to be further explored to clarify its relationship with the pathogenesis of PTC and find new biomarkers.Methods:A total of 68 patients who underwent ultrasound-guided fine needle aspiration（FNAB）in Qilu Hospital of Shandong University from June 2019 to July 2020 were enrolled in this study.According to the results of surgical pathology and FNAB,4 PTC tissue and adjacent tissue were screened for high-throughput sequencing.The significantly differentially expressed circrRNAs were screened by biological analysis,and the expression levels of differentially expressed circRNAs were verified by real-time fluorescent quantitative PCR（qRT-PCR）.Then we confirmed the expression of circMET（hascirc0082002）by fluorescence in situ hybridization and qRT-PCR in the thyroid tissues and cell lines of PTC.Then the role of circMET in PTC cell lines was verified by silencing circMET in cell proliferation and cell cycle assays.Results:The sequencing results of 4 pairs of samples showed that 103 differentially expressed circRNAs were identified in PTC tissues,including 89 up-regulated circRNAs and 14 down-regulated circRNAs（FC>2;P<0.05）,and the corresponding miRNAs were predicted.The potential axes were predicted,such as circMET/hsa-miR-1197/B3GNT3,circMET/hsa-miR-6796-5p/CDH3 and hsacirc0000660/hsa-miR-1200/MMP7.Then it was significantly enriched in regulation of humoral immune response（GO:0002920,GO:0002920,P=1.552E-05）,regulation of complement activation（GO:0030449,）and other related pathways.The results showed that 14 significantly upregulated circRNAs may play an important role in the occurrence and development of PTC.GEPIA analysis showed that MET,the host gene of circMET,was highly expressed in the PTC group compared with the control group.Subsequently,we validated the expression levels of seven candidate circRNAs（hsacirc00315 84,hsacirc0082002,hsacirc0000660,hsacirc0067938,hsacirc0002483,hsacirc0003692,and hsacirc0006509）and verified to be significantly differentially expressed in other samples.circMET was further verified to be highly expressed in PTC tissues and cell lines.Cell function experiments showed that silencing circMET could inhibit the proliferation of TPC-1 cells and interfere with the cell cycle.Conclusions:This study identified differentially expressed circRNAs in PTC tissues.Compared with adjacent tissues,14 circRNAs that were significantly upregulated were screened out,which may be involved in the biological process of PTC and may be used for the diagnosis of PTC.CircMET can promote the proliferation of PTC cells and affect the cell cycle,which may be used as a promising potential biomarker for the diagnosis of PTC. |
