Objective: To investigate the effects of proteasome beta 5 subunit (PSMB5) on proliferation and bortezomib (BTZ) chemo-sensitivity of multiple myeloma (MM) and its related molecular mechanisms. Methods: We used two MM cell lines, RPMI 8226 and BTZ drug-resistant cell line RPMI 8226/BTZ100 (hereinafter referred to as BTZ100) , as the research object. PSMB5 was overexpressed or knocked down in two myeloma cell lines via lentivirus transfection. CCK8 assay was used to detect the impact of PSMB5 on cell viability and bortezomib sensitivity in human myeloma cells; Using flow cytometry to test the effects of PSMB5 on apoptosis rate of human myeloma cells under the treatment of bortezomib; Apoptosis-related gene expression of Bax, Bcl-2, p-Akt and cleaved caspase-3 were detected by Western blot. Results: ①PSMB5 overexpression and knockdown were successfully constructed in RPMI 8226 and BTZ100 cells. ②PSMB5 expression was positively correlated with cell proliferation of RPMI 8226 and BTZ100 cells (P<0.05) . ③The cell viability was lower after PSMB5 knockdown in RPMI 8226 cells than control cells under the same concentration of BTZ[IC(50) at 24 h: (7.01±0.47) and (9.64±0.55) nmol/L respectively, t=6.289, P=0.003]. The cell viability was higher after PSMB5 overexpression in RPMI 8226 cells than control cells under the same concentration of BTZ[IC(50) at 24 h: (10.99±0.58) and (9.51±0.37) nmol/L respectively, t=3.724, P=0.020) . PSMB5 expression was negatively correlated with the sensitivity of RPMI 8226 cells to BTZ. The results of BTZ100 cells were similar. ④The expression of PSMB5 was negatively correlated with the apoptosis of RPMI 8226 and BTZ100 under the treatment of BTZ. ⑤Meanwhile, PSMB5 knockdown could increase the expression of pro-apoptosis gene Bax and cleaved caspase-3 and decrease the expression of anti-apoptotic gene Bcl-2 and p-Akt. PSMB5 over-expression has the opposite results. Conclusion: PSMB5 knockdown could improve the bortezomib sensitivity of MM cells via activation of apoptosis signaling. PSMB5 may be a potential therapeutic target for MM.
目的： 探讨蛋白酶体β5亚单位（PSMB5）基因对多发性骨髓瘤（MM）细胞增殖和硼替佐米（BTZ）耐药的影响及其机制。 方法： 以MM细胞株RPMI 8226细胞和BTZ耐药细胞株RPMI 8226/BTZ100（简称BTZ100）细胞为研究对象，采用慢病毒转染的方法建立过表达和下调PSMB5表达的MM稳转细胞系；CCK8法检测PSMB5对MM细胞增殖和BTZ耐药性的影响；流式细胞术检测PSMB5对细胞凋亡的影响；Western blot法检测PSMB5对凋亡相关基因Bax、Bcl-2、p-Akt和Cleaved caspase-3表达的影响。 结果： ①成功构建稳定过表达和下调PSMB5表达的RPMI 8226和BTZ100细胞系。②PSMB5表达与RPMI 8226和BTZ100细胞增殖呈正相关（P值均<0.05）。③下调PSMB5表达后，在相同浓度的BTZ作用下RPMI 8226细胞活力较对照组降低[作用24 h时IC(50)分别为（7.01±0.47）、（9.64±0.55）nmol/L，t=6.289，P=0.003]，过表达后的细胞活力较对照组升高[IC(50)分别为（10.99±0.58）、（9.51±0.37）nmol/L，t=3.724，P=0.020]。④PSMB5表达可促进BTZ诱导的RPMI 8226、BTZ100细胞凋亡，与对照组比较，差异均有统计学意义（P值均<0.05）。⑤下调PSMB5表达可上调Bax和Cleaved caspase-3表达，降低Bcl-2和p-Akt表达，而过表达则相反。 结论： 下调PSMB5表达可通过激活凋亡信号通路促进MM细胞凋亡，增强MM细胞对BTZ的敏感性。提示PSMB5可能是治疗MM的潜在靶点。.
Keywords: Bortezomib; Cell proliferation; Drug resistance, neoplasm; Multiple myeloma; Proteasome beta 5 subunits.