• X-F Meng, L-Y Zhao, and X-F Chu.
• Department of Endocrine, Shandong Weifang People's Hospital, Weifang, China. cxfcxfcxf19841022@163.com.
• Eur Rev Med Pharmacol Sci. 2019 Mar 1; 23 (5): 2075-2083.

ObjectiveThis study aims to elucidate the regulatory role of long noncoding RNA (lncRNA) LINC00673 in proliferative, invasive and metastatic capacities of papillary thyroid carcinoma (PTC), and to investigate the possible underlying mechanism.Patients And MethodsLINC00673 expression in PTC tissues and cell lines was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The correlation between LINC00673 expression and PTC prognosis was analyzed. By plasmid transfection, we constructed PTC cell lines with stable knockdown of LINC00673. The regulatory effect of LINC00673 on the proliferation of K1 and TPC-1 cells were determined by Cell Counting Kit-8 (CCK-8) assay and colony formation assay. The transwell assay was conducted to evaluate the effect of LINC00673 on the metastatic ability of PTC cells. The binding condition between LINC00673 with enhancer of zeste homolog 2 (EZH2) and DNA Methyltransferase 1 (DNMT1) was verified by RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) and Western blot. The cellular mechanism of p53 in regulating biological behaviors of PTC cells was explored by Western blot. Finally, the gain-of-function experiment was performed to elucidate whether LINC00673 could regulate PTC development by inhibiting p53 expression.ResultsLINC00673 expression in PTC tissues was significantly higher than that of the adjacent normal tissues. Besides, higher expression of LINC00673 indicated worse prognosis of PTC. The knockdown of LINC00673 in K1 and TPC-1 cells markedly reduced the proliferative rate. Meanwhile, LINC00673 down-regulation remarkably inhibited the migratory and invasive capacities of K1 and TPC-1 cells. RIP and ChIP assay demonstrated that LINC00673 could bind to EZH2 and DNMT1. Besides, Western blot analysis showed that LINC00673 negatively regulated p53 expression. In addition, the knockdown of p53 in K1 and TPC-1 cells partially reversed the inhibitory effect of LINC00673 deficiency on the proliferation and metastasis of PTC cells.ConclusionsHigh expression of LINC00673 in PTC predicts a poor prognosis. LINC00673 remarkably promotes the proliferation and invasion of PTC cells by inhibiting p53 expression by binding to EZH2 and DNMT1.

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