Circular RNAs (circRNAs) play an extremely important regulatory role in the occurrence and development of various malignant tumors including papillary thyroid cancer (PTC). circFAT1(e2) is a new type of circRNA derived from exon 2 of the FAT1 gene, which is distributed in the cytoplasm and nucleus of PTC cells. However, so far, the role of circFAT1(e2) in PTC is still unclear. In this study, circFAT1(e2) was found to be highly expressed in PTC cell lines and tissues. circFAT1(e2) knockdown suppressed PTC cell growth, migration, and invasion. Also, circFAT1(e2) acted as a sponge for potential microRNAs (miRNAs) to modulate cancer progression. A potential miRNA target was discovered to be miR-873 which was targeted by circFAT1(e2) in PTC. The dual-luciferase assay conducted later also confirmed that there was indeed a direct interaction between circFAT1(e2) and miR-873. This study also confirmed that circFAT1(e2) inhibited the miR-873 expression and thus promoted the ZEB1 expression, thus affecting the proliferation, metastasis, and invasion of PTC cells. In conclusion, the results of this study indicated that circFAT1(e2) played a carcinogenic role by targeting the miR-873/ZEB1 axis to promote PTC invasion and metastasis, which might become a potential novel target for therapy of PTC.

中文翻译：

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circFAT1(e2) 通过 miRNA-873/ZEB1 轴促进甲状腺乳头状癌增殖、迁移和侵袭

环状RNA（circRNA）在包括甲状腺乳头状癌（PTC）在内的多种恶性肿瘤的发生、发展中发挥着极其重要的调节作用。circFAT1(e2)是源自FAT1基因外显子2的新型circRNA，分布于PTC细胞的细胞质和细胞核中。然而，迄今为止，circFAT1(e2)在PTC中的作用仍不清楚。在这项研究中，发现circFAT1(e2)在PTC细胞系和组织中高表达。circFAT1(e2) 敲除抑制 PTC 细胞生长、迁移和侵袭。此外，circFAT1(e2) 还充当潜在 microRNA (miRNA) 的海绵，调节癌症进展。一个潜在的 miRNA 靶标被发现是 miR-873，它是 PTC 中 circFAT1(e2) 的靶标。随后进行的双荧光素酶测定也证实了circFAT1(e2)和miR-873之间确实存在直接相互作用。本研究还证实circFAT1(e2)抑制miR-873表达进而促进ZEB1表达,从而影响PTC细胞的增殖、转移和侵袭。总之，本研究结果表明，circFAT1(e2)通过靶向miR-873/ZEB1轴而发挥致癌作用，促进PTC侵袭和转移，可能成为PTC治疗的潜在新靶点。