STAT1-induced upregulation of lncRNA LINP1 promotes cell proliferation and inhibits apoptosis via AMPK signaling pathway in papillary thyroid cancer.

Abstract

The purpose of this study was to detect the relative expression of long non-coding ribonucleic acid (lncRNA) in non-homologous end joining pathway 1 (LINP1) in papillary thyroid cancer (PTC) tissues and cells, and to investigate the molecular mechanisms of abnormal expression and biological function of LINP1. The relative expression of LINP1 in PTC tissues and cells was detected via quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR), and the impact of small interfering (si)-LINP1 on the proliferative capacity of PTC cells was studied using Cell Counting Kit-8 (CCK-8) and colony formation assays. After the expression of LINP1 in PTC cells was interfered, flow cytometry was applied to determine the changes in cell cycle distribution and apoptosis rate. The transcription factors binding to the promoter region of LINP1 were predicted by bioinformatics. Next, qRT-PCR assay was adopted to measure the changes in LINP1 expression after interference in the expression of signal transducer and activator of transcription 1 (STAT1). Finally, the changes in the expressions of molecular markers of the adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway were examined via Western blotting assay after the expressions of STAT1 and LINP1 were interfered. It was shown in qRT-PCR results that LINP1 expression was upregulated in 42 out of 53 cases of PTC tissues and in all PTC cells. After interference in the expression of LINP1 in PTC cells, the results of CCK-8 and colony formation assays indicated that the proliferative capacity of the cells was repressed. According to the results of flow cytometry, the cell cycle was arrested at the G1/G0 phase, and the apoptosis rate was increased. In addition, the bioinformatics predicted that STAT1 could bind to the promoter region of LINP1, and the results of qRT-PCR indicated that the expression of LINP1 declined after STAT1 expression was interfered. Moreover, it was indicated in the Western blotting assay after interference in the expressions of STAT1 and LINP1 that the expression of molecular marker (Phosphorylation AMPK, p-AMPK) of the AMPK signaling pathway was altered but the expression of total AMPK did not change. The transcription factor STAT1 promotes the expression of LINP1 in PTC, and highly expressed LINP1 facilitates the proliferation and inhibits the apoptosis of PTC by suppressing the AMPK signaling pathway.