β-catenin/LEF-1 Transcription Complex is Responsible for the Transcriptional Activation of LINC01278
Abstract Background: Our previous study shows that LINC01278 inhibits the development of papillary thyroid carcinoma (PTC) by regulating miR-376c-3p/DNM3 axis. However, the regulation mechanism of LINC01278 expression in PTC cells is still unclear. Methods: The luciferase reporter and ChIP assays were used to confirme the binding of LEF-1 to the putative promoter site of LINC01278. The RNA immunoprecipitation was used the enrichment of LINC01278 in β-catenin protein. Western blot was used to detected the expression of target proteins. Results: Firstly, the online PROMO algorithm determined a putative LEF-1 binding site on LINC01278 promoter. Then, the luciferase reporter and ChIP assays confirmed the binding of LEF-1 to the putative promoter site of LINC01278. Furthermore, the overexpression of β-catenin increased the binding of LEF-1 to the LINC01278 promoter, and the knockdown or overexpression of LEF-1 or β-catenin can affect the expression level of LINC01278. In addition, RNA immunoprecipitation showed that LINC01278 was enriched in β-catenin protein. RNA pulldown and western blot also confirmed that LINC01278 precipitated β-catenin in TPC-1 and BCPAP cells. Furthermore, the knockdown or overexpression of LINC01278 significantly affected the expression of β-catenin and targets of Wnt/β-catenin signaling pathway (CCND2, CyclinD1, MYC, and SOX4). Conclusion: In summary, we found the transcriptional activation of LINC01278 by the β-catenin/LEF-1 transcription factor, and the negative feedback regulation of LINC01278 on Wnt/β-catenin signaling pathway activation.