CITED1 promotes proliferation of papillary thyroid cancer cells via the regulation of p21 and p27

It has been reported that CBP/p300-Interacting Transactivator with glutamic acid [E]/aspartic acid [D]-rich C-terminal domain 1 (CITED1) is overexpressed in papillary thyroid cancer (PTC). However, the functional significance and underlying mechanisms of CITED1 in PTC are largely unknown. The Cancer Genome Atlas dataset and real-time PCR were used to determine the expression of CITED1 in PTC. The role of CITED1 in PTC cell proliferation was determined conducted using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, 5-ethynyl-2′-deoxyuridine (EdU) incorporation, and flow cytometry assays in vitro, and a subcutaneous xenotransplantation tumor model in nude mice was established to analyze tumor growth in vivo. We studied the potential mechanisms underlying the contribution of CITED1 to PTC proliferation using western blotting and luciferase assays. We found that CITED1 was highly expressed in PTC. In vitro and in vivo experiments demonstrated that CITED1 was involved in PTC cell proliferation and tumorigenesis. Then, gain- and loss-of-function experiments revealed that CITED1 decreased the expression of p21 and p27, and thereby increased the phosphorylation of pRb as well as E2F1 transcriptional activity. Our results suggest that CITED1 is overexpressed in PTC and that CITED1 promotes the proliferation of PTC cells via the regulation of p21 and p27, which indicates that CITED1 might be a potential therapeutic target in the treatment of PTC.