T Cell Factor 4 Is Involved in Papillary Thyroid Carcinoma via Regulating Long Non-Coding RNA HCP5

The annual incidence of papillary thyroid carcinoma has increased dramatically. T cell factor 4 (TCF4) is an important component of Wnt signaling pathway.However, the role of TCF4 in PTC remains unknown. In this study, TCF4 was observed to overexpress in PTC patients and cells by qRT-PCR assay. The colony formation assay, Edu staining and transwell assay indicated thatoverexpression of TCF4 promoted cell proliferation and invasion of TCP-1 cells, whereas knockdown of TCF4 inhibited cell proliferation and invasion of IHH-4 cells. To investigate the mechanism of TCF4 in PTC cells, the luciferase assay demonstrated that TCF4 could modulate HCP5 expression. Besides, GLuc-ON promoter reporter assayproved that TCF4 could bind to HCP5 promoter. Further, knockdown of HCP5 could significantly up-regulated miR-15a, miR-216a-5p, miR-22-3p, miR-139-5p, miR-203, miR-27a-3p and miR-320, and down-regulated miR-186-5p in IHH-4 cells, which might be potential downstream of TFC4/HCP5 axis. In conclusion, up-regulation TCF4 can promote HCP5 expression via binding to HCP5 promoter. It may be the first time to prove that TCF4 regulates HCP5 in PTC, which provides a novel sight for treatment of PTC.