Drug resistance in tumors is a major issue, limiting the curative efficacy of currently available cancer chemotherapeutics. 5-Fluorouracil (5-FU) is a commonly applied therapeutic drug in colon cancer patient regimens; however, the majority of patients develop resistance to 5-FU in the later stages of the disease, rendering this chemotherapy ineffective. Drug resistance is the main factor underlying the poor prognosis of patients with colon cancer. In recent years, a number of studies have confirmed that long non-coding (lnc)RNAs may play vital roles in tumor resistance. In the present study, the Gene Expression Omnibus (GEO) and lncRNADisease2 databases were screened for colon cancer-associated expression patterns of lncRNA plasmacytoma variant translocation 1 (PVT1). Subsequently, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect changes in PVT1 expression in resistant cell lines, and a Cell Counting Kit-8 (CCK-8) assay kit was used to assess the effects of PVT1 knockdown on the half maximal inhibitory concentrations of parental and 5-FU-resistant HCT116 cells. Subsequently, CCK-8, clone formation, and flow cytometric assays were performed to investigate the effects of PVT1 knockdown on the sensitivity of HCT116-5FU-resistant cells to 5-FU. Dual-luciferase assay, RNA pull-down and RNA immunoprecipitation assays verified the interactive regulation of PVT1, miR-486-5p and cyclin dependent kinase 4 (CDK4). PVT1 was highly expressed in HCT116-5FU-resistant cells, as compared to its expression in HCT116 parental cells. PVT1 knockdown significantly reduced the resistance of HCT116-5FU-resistant cells to 5-FU. In addition, PVT1 upregulated CDK4 expression by adsorbing miR-486-5p; however, CDK4 overexpression restored the effects of miR-486-5p inhibition on HCT116-5-FU-resistant cells. Additionally, PVT1 knockdown partially rescued CDK4 overexpression in HCT116-5-FU-resistant cells. On the whole, the findings of the present study suggest that PVT1 promotes the resistance of colon cancer cells to 5-FU by regulating the miR-486-5p/CDK4 axis. Therefore, PVT1 may prove to be a potential target for counteracting resistance to 5-FU in colon cancer therapy.
Keywords: 5-FU resistance; CDK4; PVT1; colon cancer; miR-486-5p.
Copyright: © Luo et al.