蛋白酶体抑制剂在肿瘤坏死因子相对凋亡诱导配体诱导恶性淋巴瘤细胞凋亡抵抗中的作用及其分子机制

Effect and molecular mechanism of proteasome inhibitor in TRAIL-induced apoptosis resistance on malignant lymphoma cells

目的探讨体外蛋白酶体抑制剂在肿瘤坏死因子相对凋亡诱导配体（TRAIL）诱导恶性淋巴瘤细胞凋亡抵抗中的作用及其分子机制。方法TRAIL与蛋白酶体抑制剂硼替唑咪（PS-341）处理恶性淋巴瘤Raji细胞后，采用MTF法检测药物不同作用时问对细胞的增生影响；流式细胞术检测细胞周期；Western blotting法检测Bax蛋白质水平变化；实时荧光定量RT—PCR法检测BaxmRNA的表达情况。结果TRAIL在质量浓度500μg／L时可减少Raji细胞的增生，但低于正常淋巴细胞Hmy2．ciR；TRAIL阻滞细胞周期于G0／G1期，Western blotting法检测Raji细胞Bax蛋白表达水平下降，实时荧光定量RT—PCR法检测BaxmRNA的表达水平却未见差异性改变，联合使用浓度为10nmol／LPS-341后可明显提高TRAIL的诱导凋亡作用，阻滞于G0／G1期的细胞数增加，Bax蛋白表达水平也逐渐增加。结论TRAIL在诱导恶性淋巴瘤细胞凋亡过程中出现抵抗，可能与促凋亡蛋白Bax表达水平下降有关，而Bax蛋白表达水平的下降与mRNA表达水平无关，可能与泛素-蛋白酶体途径的降解有关。

Objective To explore the effect and molecular mechanism of proteasome inhibitor in TNF-related apoptosis-inducing ligand （TRAIL）-induced apoptosis resistance on malignant lymphoma cells. Methods Raji cells were treated with TRAIL and proteasome inhibitor （PS-341） in vitro and the cell growth index was evaluated by MTT assay; cell cycle was analysed by flow cytometry; the protein and mRNA level of Bax were measured by Western blotting and real time RT-PCR. Results TRAIL inhibited proliferation of Raji cells at the concentration of 500μg/L, but the inhibition rate was lower than that of the control cell： Hmy2.ciR.TRAIL arrested cell in G0/G1 phase. The Bax protein in Raji is degraded, but the Bax mRNA expression level does not change significantly.The effects of TRAIL was enhanced significantly 10 nmol/L PS- 341 was added. Conclusion Raji cells are resistant in TRAIL-induced apoptosis. This effect may be related to the decrease of Bax protein. The Ubiquitin-proteasome pathway is involved in the degradation of Bax in TRAIL-treated Raji cells.