This study investigated the effect of
etoposide, an anticancer
chemotherapy drug, on B7-H1 expression in
retinoblastoma (Rb) cells and the role of miR-513a-5p in the process. Rb cells were divided into control and
etoposide groups. In the
etoposide group, cells were treated with
etoposide at different concentrations (2.5, 5, 10, 20 and 40 μg/mL) for 24 h. Those given no treatment of etopside served as controls. Reverse transcription polymerase chain reaction (RT-PCR), fluorescence quantitative PCR and flow cytometry were performed to measure the
mRNA and
protein expression of B7-H1 in Rb cells. The
mRNA expression of miR-513a-5p in Rb cells before and after
etoposide treatment was also detected by fluorescence quantitative PCR. The miR-513a-5p mimics and the miR-513a-5p inhibitor were transfected into Rb cells separately, and fluorescence quantitative PCR and flow cytometry were used to detect the effect of the miR-513a-5p mimics or inhibitor on B7-H1 expression. TargetScan5.2 was employed to predict the miR-513a-5p binding sites in the 3'-untranslated region of B7-H1
mRNA.
Luciferase reporter plasmids carrying this site were prepared and transfected into Rb cells and
luciferase activity analyzed. The results showed that
etoposide stimulated the
mRNA and
protein expression of B7-H1 in Rb cells, which reached a maximal level
after treatment with 5 μg/mL
etoposide (P<0.05). However, miR-513a-5p expression was decreased in Rb cells after
etoposide treatment. When the miR-513a-5p inhibitor was added, B7-H1 expression was increased with the concentration of the miR-513a-5p inhibitor (P<0.05). Moreover, B7-H1 expression was decreased gradually with the concentration of the miR-513a-5p mimics increased (P<0.01). Additionally, the miR-513a-5p mimics were found to inhibit the
luciferase activity. It was concluded that
etoposide can promote B7-H1 expression in Rb cells, which may be associated with chemoresistance. The promoting effect of
etoposide on B7-H1 expression can be reversed by miR-513a-5p mimics. MiR-513a-5p inhibits the
mRNA and
protein expression of B7-H1 via binding to the 3'-UTR of B7-H1
mRNA.