Rituximab对紫杉醇诱导人B淋巴瘤细胞株凋亡的增敏作用

Rituximab-mediated Sensitiziation of B-NHL Cell Lines to Apoptosis Induced by Paclitaxel

目的基于对CHOP(环磷酰胺、阿霉素、长春新碱和强的松)联合化疗方案治疗侵袭性淋巴瘤疗效的不尽人意,本文研究利妥昔单抗(Rituximab)对新一代化疗药物Paclitaxel的化疗增敏作用,并探讨其可能的作用机制。方法(1)体外培养Daudi、Ramos、Namalwa和Raji细胞,采用XTT法测定细胞增殖抑制率:以药物浓度为横坐标,抑制率为纵坐标绘出细胞增殖抑制曲线,比较单药和两药协同作用曲线,若联合作用曲线左移表示有协同作用,右移表示有拮抗作用。(2)Western blot测定:Daudi、Ramos、Raji和Na-malwa细胞经Rituximab20μg/ml作用24小时后检测抗凋亡蛋白Bcl-2的表达情况。结果(1)XTT法测定Paclitaxel单药及与Rituximab联合作用对各细胞株增殖抑制率:对Daudi、Namalwa、Ramos和Raji细胞株,Rituximab对Paclitaxel的细胞毒作用有明显的增敏作用;(2)Western blot测定:在Namalwa和Raji细胞株中,经Rituximab作用24小时后,可见Bcl-2蛋白表达下调。结论(1)单药Rituximab对Paclitaxel有明显的化疗增敏作用。(2)在Namalwa和Raji细胞株,经Rituximab作用24小时后可见Bcl-2表达下调,可能是Rituximab增敏的机制之一。

Objective It is unsatisfied to the efficacy for patients with aggressive Non-Hodgkin＇s lymphoma （NHL） were treated by CHOP regimen （cyclophosphamide, doxorubicin, vincristine, and predisone）. In this research, we studied the Rituximab-mediated sensitization of B-NHL cell lines to apoptosis induced by Paclitaxel and discussed their mechanism. Methods （1）Detection of inhibitive rate of cell proliferation by XTT assay： the cytotoxic effect of each treatment was calculated as the percentage of viability as compared to the untreated cells. The curves of cell inhibiting are draw by the concentration of drugs set as abscissa and the rates of inhibition as ordinate. There are two curves of inhibition： one for cytotoxic drug and another one for combination in rituximab with Paclitaxel. Shifting left of curve imply the synergistic effect, while shifting right of curve means the agonistic effect. （2）Western blot analysis of protein expression： The human burkitt＇ s lymphoma cell lines Daudi, Namalwa, Raji and Ramos cells were cultured in complete medium supplemented with either rituximab（20μg/ml） or normal serum for ninety-six hours. At different times, the cells were harvested and the expression of anti-apoptosis protein Bcl-2 was analyzed by westblotting. Results （1） Inhibition of cell proliferation by either Paclitaxel alone or combination with rituximab was detected by XTT assay： rituxiamb could sensitize significantly the cytotoxicity of Paclitaxel in Daudi, Namalwa and Raji cell lines. （2）Analysis of Westblotting： Expression of Bcl-2 protein was down-regulated after treated by rituximab for 24 hours in Raji and Namalwa cell lines. Conclusion （ 1 ） Rituximah as a monomer could sensitize the cytotoxicity of Paclitaxel to the human lymphoma cell lines. （2）Expression of Bcl-2 in Raji and Namalwa cell lines was down-regulated after the cells were treated by rituximab for 24 hours. Down-regulation of Bcl- 2 expression might be the one of mechanisms which the rituximab sensitized the cytotoxicity of cytotoxic drugs.