LINC00891 Promotes Tumorigenesis and Metastasis of Thyroid Cancer by Regulating SMAD2/3 via EZH2

Background: Thyroid cancer (TC), the most common endocrine malignant tumor, is increasingly causing a huge threat to our health nowadays. Methods: To explore the tumorigenesis mechanism of thyroid cancer, we identified that long intergenic non-coding RNA-00891 (LINC00891) was upregulated in TC using the Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and local databases. LINC00891 expression was correlated with histological type and lymph node metastasis (LNM). The high expression of LINC00891 could serve as a diagnostic marker for TC and its LNM. In vitro experiments demonstrated that LINC00891 knockdown could inhibit cell proliferation, migration, invasion and prompt apoptosis and G1 arrest of TC cells. We also investigated the related mechanisms of LINC00891 promoting TC progression using RNA sequencing, Gene Set Enrichment Analysis, and Western blotting. Results: Our experiments demonstrated that LINC00891 promoted TC progression via the EZH2-SMAD2/3 signaling axis. In addition, overexpression of EZH2 could reverse the suppressive epithelial-to-mesenchymal transition (EMT) caused by LINC00891 knockdown. Conclusion: In conclusion, the LINC00891/EZH2/SMAD2/3 regulatory axis participated in tumorigenesis and metastasis of thyroid cancer, which may provide a novel target for treatment.