MiR-20a Enhances Cisplatin Resistance Of Human Gastric Cancercell Line By Targeting NFKBIB

Objetives:Drug resistance of cancer cells can be regulated by the dysregulated miRNAs, and sustained NFκB activation also plays an important role in tumor resistance to chemotherapy. Here, we sought to investigate whether there was a correlation between miR-20a and the NFκB pathway to clarify the effects that miR-20a exerted on gastric cancer (GC).Methods:miR-20a expression levels in gastric cancer samples and cell lines were determined using real-time polymerase chain reaction (RT-PCR). Cell sensitivity was assessed by MTT assay. Cell apoptosis was evaluated using flow cytometry. NFKBIB expression in GC tissues was assessed by IHC. The direct target gene of miR-20a was also identified by luciferase reporter assays. Proteins of NFKBIB, p65, Livin and Survivin were represented by western blot assay.Results:We found that miR-20a was significantly upregulated in GC plasma and tissue samples. In addition, it was upregulated in GC plasma and tissues from patients with cisplatin-resistant gastric cancer cell line SGC7901/cisplatin (DDP). In transfection experiments, miR-20a inhibitor enhanced the sensitivity of cells to DDP and DDP-induced apoptosis in SGC7901/DDP. While miR-20a mimic attenuated the sensitivity of cells to DDP and DDP-induced apoptosis in SGC7901. And the upregulation of miR-20a was concurrent with the downregulation of NFKBIB (also known as IkBP) as well as upregulation of p65, Livin, and Survivin. The luciferase activity suggested that NFKBIB was the direct target gene of miR-20a. Transfection of miR-20a inhibitor could increase NFKBIB level; downregulate the expression of p65, Livin and Survivin; and lead to a higher proportion of apoptotic cells in SGC7901/DDP cells. Conversely, ectopic expression of miR-20a dramatically decreased the expression of NFKBIB; increased the expression of p65, Livin, and Survivin; and resulted in a decrease in the apoptosis induced by DDP in SGC7901 cells.Conclusions:Our findings suggested that miR-20a could promote activation of the NFκB pathway and downstream targets p65, Livin and Survivin by targeting NFKBIB, which potentially contributed to GC chemoresistance.