MicroRNA-218 enhances gastric cancer cell cisplatin sensitivity by targeting survivin

Abstract

Gastric cancer (GC) is one of the most prevalent types of cancer worldwide. Cisplatin based chemotherapy is the primary strategy implemented for the treatment of G; however, chemoresistance is a major problem. Previous studies have indicated that microRNAs (miRs) are associated with chemoresistance in various types of cancer and that miR-218 specifically, serves important roles in the growth of GC cells. The present study assessed the potential biological roles of miR-218 in GC cell cisplatin (DDP) resistance. The results obtained from a polymerase chain reaction assay indicated that the expression of miR-218 was decreased in cisplatin resistant SGC7901/DDP cells compared with SGC7901 cells. Furthermore, MTT results indicated that the upregulation of miR-218 expression significantly enhanced SGC7901/DDP cell sensitivity to DDP. The results of a dual-luciferase assay indicated that survivin was a direct target gene of miR-218. Results also demonstrated that miR-218 was overexpressed in SGC7901/DDP cells and that the downregulation of survivin expression enhanced SGC7901/DDP cell sensitivity to DDP. Further study demonstrated that the upregulation of miR-218 decreased the expression of survivin in SGC7901/DDP cells and induced apoptosis. The findings of the present study indicated that the induction of miR-218 enhanced GC cell DDP resistance via the regulation of survivin, which may potentially benefit the clinical treatment of GC in the future.

Keywords: SCG7901/DDP; SGC7901; cisplatin sensitivity; microRNA-218; survivin.

Figure 1.

Expression of miR-128 in human GC cell lines. Relative miR-128 levels were measured using a reverse transcription quantitative polymerase chain reaction assay. Data are expressed as the mean + standard deviation. *P<0.05 vs. SGC7901 cells. miR, microRNA; GC, gastric cancer; DDP, cisplatin.

Figure 2.

miR-218 regulated GC cell sensitivity to DDP. In SGC7901/DDP cells, an MTT assay revealed that the upregulation of miR-128 significantly decreased resistance to DDP; while in SGC7901 cells, the downregulation of miR-128 significantly enhanced resistance to DDP. Data are expressed as the mean + standard deviation. *P<0.05 vs. respective controls. miR, microRNA; DDP, cisplatin; GC, gastric cancer; IC₅₀, half maximal inhibitor concentration.

Figure 3.

Survivin was a direct target of Hsa-miR-218. (A) Prediction of miR-218 binding sites in the 3′UTRs of the human survivin gene. (B) Survivin was confirmed to be a direct target of Hsa-miR-218 by performing a dual-luciferase assay. Data were expressed as the mean + standard deviation. *P<0.05. miR, microRNA; UTR, untranslated region; WT, wild type; Mut, mutant; CMV, cytomegalovirus.

Figure 4.

Expression of survivin in resistant GC cell lines and the effect of survivin in GC cell DDP resistance. (A) Survivin levels were measured using western blotting and a reverse transcription-quantitative polymerase chain reaction assay. *P<0.05 vs. SGC-7901. (B) In human GC cells, an MTT assay revealed that the knock out of survivin significantly decreased resistance to DDP. Data were expressed as the mean + standard deviation. *P<0.05 vs. control. GC, gastric cancer; DDP, cisplatin; IC₅₀, half maximal inhibitor concentration; siRNA, small interfering RNA.

Figure 5.

Expression of survivin in human GC cells transfected with an miR-218 mimic or inhibitor. (A) The expression of survivin was measured using western blotting. (B) The expression of survivin was measured using a reverse transcription quantitative polymerase chain reaction assay. Data were expressed as the mean + standard deviation. *P<0.05. GC, gastric cancer; miR, microRNA; DDP, cisplatin.

Figure 6.

SGC7901/DDP cells treated with miR-218 were sensitized to DDP-induced apoptosis. (A) In SGC7901/DDP cells, apoptosis was assessed using flow cytometry. (B) Representative results of flow cytometry. Data were expressed as the mean + standard deviation. *P<0.05 vs. the miRNA mimic control. DDP, cisplatin; miR, microRNA; PI, propidium iodide; FITC, fluorescein isothiocyanate.