C-MYC-induced upregulation of LINC01503 promotes progression of non-small cell lung cancer.

OBJECTIVE The purpose of this study was to detect the expression of long intergenic non-protein-coding RNA 1503 (LINC01503) in non-small cell lung cancer (NSCLC), and to further study its biological function, as well as the regulatory relationships of c-MYC with LINC01503 and the extracellular signal regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling pathway in NSCLC. PATIENTS AND METHODS Tissue specimens were collected from 36 NSCLC patients, and the relative expression level of LINC01503 in the 36 cases of NSCLC tissue specimens and NSCLC cells was then determined using quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR). Then, the effects of LINC01503 on the proliferation and apoptosis of NSCLC cells were detected in vitro via Cell-Counting Kit (CCK)-8 assay, colony-forming assay and flow cytometry. Besides, the possible LINC01503 promoter-binding transcription factor was predicted using bioinformatics. After interference with c-MYC expression, the changes in the expression of LINC01503 were examined through qRT-PCR. Finally, the changes in the expressions of the molecular markers in the ERK/MAPK signaling pathway after interference with LINC01503 and c-MYC expressions were evaluated using Western blotting. RESULTS According to qRT-PCR results, the expression of LINC01503 was upregulated in 30 out of 36 cases of NSCLC tissues. Compared with that in human normal bronchial epithelial cells, the expression of LINC01503 was elevated in NSCLC cells. As shown by the CCK-8 assay and colony-forming assay, the proliferation ability of NSCLC cells was weakened after interference with LINC01503 expression, and the flow cytometry results revealed the apoptosis rate of NSCLC cells was raised after interference with LINC01503 expression. Moreover, the bioinformatics prediction showed that c-MYC might be the LINC01503 promoter-binding transcription factor. Additionally, it was found through the qRT-PCR that the expression of LINC01503 declined after interference with c-MYC expression. Finally, based on Western blotting results, the expressions of phosphorylated ERK1/2 (p-ERK1/2) and p-MAPK/ERK kinase (MEK), the molecular markers in the ERK/MAPK signaling pathway, were inhibited after interference with c-MYC and LINC01503 expressions. CONCLUSIONS The transcription factor c-MYC promotes the expression of LINC01503 in NSCLC and activates the ERK/MAPK signaling pathway to drive the development and progression of NSCLC.