Ihh 4

The normal thyrocytes-derived cell line Nthy-ori 3-1 (SV-40 immortalized normal human thyroid follicular cells) and four human PTC cell lines (K-1, TPC-1, and IHH-4, BCPAP) were obtained from the American Type Culture Collection (ATCC, Manassas, VA, USA). Nthy-ori3-1 and K-1 cells were cultured in RPMI 1640 medium. TPC-1 cells were cultured in DMEM medium. IHH-4 cells were cultured in a mixture (1:1) of RPMI 1640 and DMEM medium. BCPAP cells were cultured in a mixture (1:1) of F12 and DMEM medium. All media were supplemented with 10% fetal bovine serum, 100 U/ml penicillin and 100 mg/ml streptomycin. All cells were maintained at 37°C in a humidified atmosphere with 5% CO 2 . The overexpression was achieved by transfecting K-1 cells with USP18 plasmids (#22572, Addgene, Watertown, MA, USA) or control vector plasmids. The knockdown was conducted by transducing TPC-1 cells with packaged lentiviruses con-

TPC sample. Twenty-five pairs of human PTC and adjacent normal tissues were obtained from the Second Affiliated Hospital of Xi'an Jiaotong University (Shaanxi, China). The tissues were frozen in liquid nitrogen and stored at -80˚C until use. written informed consent for tissue donation (for research purposes) was obtained from the patients, and the protocol was approved by the Institutional Review board of the Second Affiliated Hospital of Xi'an Jiaotong University.
Cell lines. Four human PTC cell lines, including TPC-1, K1, IHH-4 and CGTH-w3, were obtained from the American Type Culture Collection (ATCC; Manassas, VA, USA). The human thyroid epithelial cell lines Nthy-ori3-1 and HTori-3 were purchased from Shanghai Cell Collection (SCC; Shanghai, China). These cell lines were cultured in Dulbecco's modified Eagle's medium (DMEM) plus 10% fetal bovine serum (FBS; Life Technologies, Inc., Grand Island, NY, USA) at 37˚C in a humidified atmosphere containing 5% CO 2 .