Abstract:

Objective To discuss the effect of downregulating the proline-rich protein 11 （PRR11） expression on drug resistance of the esophageal cancer drug resistant cells， and to clarify the related mechanism. Methods The drug resistant cells EC9706/cisplatin（DDP） were established by incrementally stimulating the human esophageal cancer EC9706 cells with the increasing concentrations of DDP. The drug sensitivity of the EC9706/DDP cells was detected by MTT assay； the expression levels of PRR11 mRNA and protein in the EC9706/DDP cells and their parent EC9706 cells were detected by real-time fluorescence quantitative PCR （RT-qPCR） and Western blotting methods. The EC9706/DDP cells were divided into control group，sh-NC group （infected with sh-NC），sh-PRR11 group（infected with sh-PRR11）， sh-NC+DDP group （infected with sh-NC and treated with 4 mg·L^－1 DDP）， and sh-PRR11+DDP group （infected with sh-PRR11 and treated with 4 mg·L^－1 DDP）. The expression levels of PRR11 mRNA in the cells in various groups were detected by RT-qPCR method； the expression levels of PRR11， phosphoinositide 3-kinase （PI3K） p110α， protein kinase B （AKT）， phosphorylated AKT （p-AKT）， P-glycoprotein （P-gp）， and multidrug resistance-associated protein 1 （MRP1） proteins in the cells in various groups were detected by Western blotting method；the apoptotic rates of the cells in various groups were detected by flow cytometry. Results The DDP-resistant cell line EC9706/DDP was successfully obtained，and the drug resistance index was 7.23±0.86. Compared with the EC9706 cells， the expression levels of PRR11 mRNA and protein in the EC9706/DDP cells were increased （P<0.05）. Compared with control and sh-NC groups， the expression levels of PRR11 mRNA and protein in the cells in sh-PRR11 group were decreased （P<0.05），and the 50% inhibitory concentration （IC₅₀） of DDP was decreased （P<0.05）.Compared with sh-NC group，the expression levels of PI3K p110α， p-AKT， P-gp， and MRP1 proteins in the cells in sh-NC+DDP and sh-PRR11 groups were decreased （P<0.05），and the apoptotic rate of the cells was increased （P<0.05）. Compared with sh-NC+DDP group and sh-PRR11 group，the expression levels of PI3K p110α， p-AKT， P-gp， and MRP1 proteins in the cells in sh-PRR11+DDP group were increased（P<0.05），and the apoptotic rate of the cells was increased（P<0.05）. Conclusion Downregulating the expression of PRR11 gene in the drug resistant EC9706/DDP cells can inhibit the expressions of drug resistance-related proteins， reverse the resistance to DDP， and induce the apoptosis； its mechanism may be related to the inhibition of activation of the PI3K/AKT signaling pathway.

Key words: Proline-rich protein 11, Esophageal neoplasm, Cisplatin, Drug resistance, Phosphoinositide 3-kinase/protein kinase B signaling pathway