Abstract
Papillary thyroid carcinoma (PTC) is the most common malignant tumor of the endocrine system globally. Formononetin (FMNT), an isoflavonoid, exerts anti-tumorigenic effects and chromobox homolog 4 (CBX4) exerts tumor-promoting effect in specific types of tumors. Nevertheless, the predictive values and biological functions of FMNT and CBX4 in the pathological progress of PTC have not been fully understood till now. In the present study, the human PTC cell line TPC-1 was exposed to 0, 10, 30 and 100 µM FMNT for 24 h to elucidate the precise effects of FMNT on the biological behaviors of PTC cells. Moreover, FMNT-treated TPC-1 cells were transfected with oe-CBX4 to evaluate whether CBX4 was implicated in the anticarcinogenic effects of FMNT against PTC. It was demonstrated that FMNT treatment suppressed the proliferation, clone formation, migration, invasion, EMT, angiogenesis and stemness of PTC cells in a dose-dependent manner. Furthermore, it was verified that FMNT targeted CBX4 to downregulate its expression in a dose dependent manner. The suppressive effects of FMNT on the proliferation, clone formation, migration, invasion, EMT, angiogenesis and stemness of PTC cells were partially reversed by CBX4 overexpression. Upregulation of CBX4 abolished the tumor suppression effects of FMNT in the malignant progression of PTC. In conclusion, FMNT might act as a promising anti-tumorigenic agent in PTC, which depends on the downregulation of CBX4.