Effect of proteasome subunit beta type 4 on the proliferation and viability of human liver cancer SMMC7721 cells

Objective To investigate the effect of proteasome subunit beta type 4( PSMB4) on the proliferation and viability of human liver cancer SMMC7721 cells and its possible mechanisms. Methods The specific short-hairpin RNA( shRNA) technique was used to construct SMMC7721 cells with knockdown expression of PSMB4,and these cells were selected as experimental group. MTT assay and colony-forming assay were used to observe the change in cell proliferation,flow cytometry was used to measure the change in cell apoptosis rate,and Western blot was used to measure the change in the expression of related proteins. The independent samples t-test was used for comparison of continuous data between two groups. Results SMMC7721 cells with knockdown expression of PSMB4 were successfully constructed( shRNA1: t = 22. 67,P < 0. 0001; shRNA2: t = 30. 88,P < 0. 0001; shRNA3: t = 67. 82,P < 0. 0001). The MTT assay showed that the experimental group had a significantly lower OD490 value than the control group on day 4( 0. 4770 ± 0. 0135 vs 0. 3237 ± 0. 0127,t =8. 286,P = 0. 0012) and day 5( 0. 5893 ± 0. 0088 vs 0. 3847 ± 0. 0090,t = 16. 220,P < 0. 0001). The colony-forming assay showed a significant reduction in the number of cell colonies in the experimental group. Flow cytometry showed that compared with the control group,the experimental group had significantly higher early apoptosis rate( 5. 5570% ± 0. 2589% vs 3. 8870% ± 0. 3324%,t = 3. 964,P = 0. 0166),late apoptosis rate( 12. 6300% ± 0. 4198% vs 5. 3100% ± 0. 3062%,t = 14. 080,P = 0. 0001),and total apoptosis rate( 18. 1800% ± 0. 6785%vs 9. 1970% ± 0. 6313%,t = 9. 967,P = 0. 0006),as well as a significant reduction in the protein expression of nuclear factor-kappa B p65( 0. 8015 ±0. 0120 vs 0. 2841 ±0. 0110,t =31. 830,P <0. 0001) and a significant increase in the protein expression of nuclear factor-kappa B inhibitory protein α( 0. 4816 ± 0. 0112 vs 0. 6583 ± 0. 0142,t = 9. 774,P = 0. 0006). Conclusion Knockdown of PSMB4 expression may reduce the proliferation and viability of liver cancer SMMC7721 cells by inhibiting the NF-κB signaling pathway.