Potential mechanism of specific small interfering RNA against ubiquitin-specific protease 22 gene on proliferation of human gastric carcinoma cells

Abstract

Objective To explore the effects of ubiquitin-specific protease 22 (USP22) on the proliferation of human gastric carcinoma cells and the potential mechanism. Methods The specific small interfering RNA (siRNA) fragments of USP22 were designed, and the highest efficient siRNA was selected by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) and Western blotting. The proliferation of SGC-7901 cells was tested using methyl thiazol tetrazolium (MTT) assay after USP22 silencing, and the cell cycle and apoptosis were tested by flow cytometry. The altered expression of cell cycle and apoptosis related proteins was detected by Western blotting. Results The efficiency of USP22 siRNA was more than 80%. The proliferation of SGC-7901 cells was significantly suppressed after USP22 silencing, and the cell cycle was arrested in G0/G1 phase [(52.87±1.41)% vs. (73.73±1.78)%, t=15.491, P=0.000]. Meanwhile, the apoptosis rate was significantly increased by USP22 silencing [(19.63±0.82)% vs. (4.54±0.46)%, t=58.051, P=0.000]. The results of Western blotting revealed that the expression of B cell lymphoma/leukemia-2 associated X protein (bax) was significantly increased (t=10.630, P=0.000), whereas that of B-cell lymphoma/leukemia-2 (bcl-2) and pro-cysteinyl aspartate-specific protease (Caspase)-3 was significantly reduced (t=6.674, 7.269; P=0.000). Furthermore, the phosphorylation of protein kinase B (Akt) and glycogen synthase kinase 3β (GSK3β) was significantly reduced (t=13.512, 6.846; P=0.003). Conclusion Cell growth of SGC-7901 cells was inhibited by USP22 silencing via reducing the activity of Akt. Key words: Ubiquitin-specific protease 22; Gastric carcinoma; Proliferation; Apoptosis; Protein kinase B