Long Noncoding RNA FER1L4 Promotes Papillary Thyroid Cancer Progression by Targeting miR-612/CDH4 Axis

Abstract Background: Long noncoding RNAs (lncRNAs) have emerged as crucial regulators in various cancers. However, the functional roles of most lncRNA in papillary thyroid cancer (PTC) are not detailly understood. This study aims to investigate the biological functions and the molecular mechanism of lncRNA FER1L4 in PTC.Methods: The expression of FER1L4 in PTC was determined via operating RT-PCR assays. Meanwhile, the clinical significance of FER1L4 in PTC patients was described. The biological functions of FER1L4 on PTC cells were evaluated by gain and loss of function experiments. Moreover, animal experiments were performed to reveal the effect on tumor growth. Subcellular distribution of FER1L4 was determined by fluorescence in situ hybridization and subcellular localization assays. Luciferase reporter assay and RNA immunoprecipitation assay were applied to define the relationship between FER1L4, miR-612, and CDH4. Results: Upregulated expression of FER1L4 in PTC tissues was correlated with higher lymph node metastasis rate (p=0.020), extrathyroidal extension (p=0.013), and advanced TNM stage (p=0.013). In addition, knockdown of FER1L4 suppressed PTC cell proliferation, migration and invasion, whereas ectopic expression of FER1L4 inversely promoted these processes. Mechanistically, FER1L4 could competitively bind with miR-612 to prevent the degradation of its target gene Cadherin 4 (CDH4). This condition was further confirmed in the rescue assays.Conclusions: This study firstly demonstrates FER1L4 plays an oncogenic role in PTC via FER1L4-miR-612-CDH4 axis and may provide a new therapeutic and diagnostic target for PTC.