MYC promotes the development of papillary thyroid carcinoma by inhibiting the expression of lncRNA PAX8‑AS1:28.

As a common malignancy of the endocrine system, papillary thyroid carcinoma (PTC) seriously affects the quality of life of patients. lncRNA PAX8‑AS1:28, or lnc‑PSD4‑1:14 has been reported to be abnormally expressed in PTC. However, the function of PAX8‑AS1:28 in PTC is still unknown. Therefore, the present study aimed to investigate the functions of PAX8‑AS1:28 in PTC, and to explore the possible mechanisms of action. A total of 38 patients with PTC were included and the normal thyroid follicular epithelial cell line Nthy‑ori 3‑1 and PTC cell line IHH‑4 were also used. MYC and PAX8‑AS1:28 overexpression and siRNA silencing in the cell lines were carried out. Expression of PAX8‑AS1:28, PAX8 and MYC in tumor tissue, adjacent healthy tissue and different cell lines were detected by qRT‑PCR and western blot analysis. Cell proliferation was measured by CCK‑8 assay. Expression levels of PAX8‑AS1:28 and PAX8 were lower in PTC tumor tissue and PTC cells than those in healthy tissue and normal cells. In contrast, the expression level of MYC was higher in PTC cells than that in normal cells. PAX8‑AS1:28 silencing reduced the expression level of PAX8 and promoted tumor cell growth, while PAX8‑AS1:28 overexpression increased the expression level of PAX8 and inhibited tumor cell growth. MYC silencing increased expression levels of PAX8‑AS1:28 and PAX8 and inhibited tumor cell growth, while MYC overexpression decreased expression levels of PAX8‑AS1:28 and PAX8 and promoted tumor cell growth. MYC can promote PTC by inhibiting the expression of lncRNA PAX8‑AS1:28.