We have previously reported that AD5-10, a novel agonistic monoclonal antibody against DRS, possessed a strong cytotoxic activity in various tumor cells, via induction of caspase-dependent and -independent signaling p...We have previously reported that AD5-10, a novel agonistic monoclonal antibody against DRS, possessed a strong cytotoxic activity in various tumor cells, via induction of caspase-dependent and -independent signaling pathways. The present study further demonstrates that reactive oxygen species （ROS） were generated in abundance in Jurkat leukemia cells upon AD5-10 stimulation and that ROS accumulation subsequently evoked sustained activation of c-Jun N-terminal kinase （JNK）, loss of mitochondrial membrane potential, and release of endonuclease G （Endo G） from mitochondria into the cytosol. The reducing agent, N-acetylcysteine （NAC）, effectively inhibited the sustained activation of JNK, release of Endo G, and cell death in Jurkat cells treated by AD5-10. Moreover, a dominant-negative form of JNK （but not of p38） enhanced NF-κB activation, suppressed caspase-8 recruitment in death-inducing signaling complexes （DISCs）, and reduced adverse effects on mitochondria, thereby inhibiting AD5-10-induced cell death in Jnrkat leukemia cells. These data provide novel information on the DR5-mediated ceil death-signaling path- way and may shed new light on effective strategies for leukemia and solid tumor therapies.展开更多
Interleukin-2 （IL）-2 signaling plays a pivotal role in the activation of immune responses, and drugs that block this pathway have been shown to be effective for the immunosuppression in patients with organ transplan...Interleukin-2 （IL）-2 signaling plays a pivotal role in the activation of immune responses, and drugs that block this pathway have been shown to be effective for the immunosuppression in patients with organ transplantation to alleviate/eliminate allograft rejection. The first humanized monoclonal antibody （mAb） daclizumab falls into this category and shows high specificity and affinity against a key component of the IL-2 receptor complex, namely IL-2Ra. To reveal the molecular mechanism of the inhibition of the IL-2 signaling pathway by dacllzumab, we determined the crystal structures of the daclizumab Fab in free form and in complex with the IL-2Ra ectodomain at 2.6 and 2.8 A resolution, respectively. The daclizumab Fab adopts a similar conformation in the presence or absence of the IL- 2Ra ectodomain. The antigen-binding site of daclizumab is mainly composed of live complementarity determining regions （CDRs） that form a large positively charged surface depression and two flanking patches that are generally hydrophobic. The conformational epitope consists of several discontinuous segments of the IL-2Ru ectodomain, a large portion of which overlaps with the regions that interact with IL-2, suggesting that the binding of daclizumab to IL-2Ra would prevent the IL-2 binding to IL-2Ra and the subsequent formation of the IL-2fIL-2Ra[~/c complex, and therefore block the IL-2 signaling pathway. These results also have implications for the design and development of improved mAb drugs targeting IL-2Ra.展开更多
Objective：To investigate the expression of CXCR4 on HL-60 cell line and the proliferation, apoptosis of HL-60 cell line cocultured with bone marrow stromal cells, so as to assess the possibility of 12G5, an anti-CXCR...Objective：To investigate the expression of CXCR4 on HL-60 cell line and the proliferation, apoptosis of HL-60 cell line cocultured with bone marrow stromal cells, so as to assess the possibility of 12G5, an anti-CXCR4 monoclonal antibody, in eradicating the minimal residual disease. Methods：The activity of SDF-1 was inhibited by 10 μg/ml 12G5. After treatment with 12G5, the status of adhesion was observed, and the adhesion rates, apoptosis and cell cycles were detected after 24 h of treatment. Cell growth rates were measured by trypan blue exclusion. Cell growth curve was plotted, and the expression of PCNA and apoptosis related protein including PCNA, Bcl-2 and Fas were detected with immunohistochemical technique. Results：（1） There was middling degree expression of CXCR4 on HL-B0 membrane. From 0 h to 6 h, as the time of 12G5 incubation along, the expression of CXCR4 decreased gradually. （2） After treatment for 24 h, the adhesion rates in the experiment group and the control were （39.4±7.9）% and （51.4±5.9）%, respectively. （3）After treatment for 24 h, the percentage of HL-60 cells in G0/G1 phase were （55.21±4.9）%, and that in S phase and G2/M phase were （30.40±4.1）% and （14.39± 5.2）%, respectively, with the corresponding proportions being （44. 67±2.2）%, （45.30±3.7）%, and （10. 03±2.6）% in the control. （4） The percentage of apoptotic HL-60 cells was （8.95±1.7）% in the experiment group, compared to （3. 97±2. 4）% in the control. （5）The survival rates of HL-60 cells decreased markedly at 48 h to 96 h, and the proliferation slowed down at this time duration. （6）The expression of PCNA and Bcl-2 down-regulated significantly, but the Fas protein expression was up-regulated. Conclusion：12G5 could inhibit the capability of adhesion and proliferation of HL-60 cells and it can induce more cells to enter G0/G1 phase and promote apoptosis. It may be helpful by inhibiting the bioactivity of SDF-1 with 12G5 in the therapy of marrow residual disease.展开更多
基金Acknowledgments We thank Dr Shimin Hu for his generous gifts of constructs. This work was partially supported by National Natural Science Foundation of China （Grant Nos. 30571687 and 30721063） and by State Key Basic Research Program of China （Grant No. 2007CB507404）.
文摘We have previously reported that AD5-10, a novel agonistic monoclonal antibody against DRS, possessed a strong cytotoxic activity in various tumor cells, via induction of caspase-dependent and -independent signaling pathways. The present study further demonstrates that reactive oxygen species （ROS） were generated in abundance in Jurkat leukemia cells upon AD5-10 stimulation and that ROS accumulation subsequently evoked sustained activation of c-Jun N-terminal kinase （JNK）, loss of mitochondrial membrane potential, and release of endonuclease G （Endo G） from mitochondria into the cytosol. The reducing agent, N-acetylcysteine （NAC）, effectively inhibited the sustained activation of JNK, release of Endo G, and cell death in Jurkat cells treated by AD5-10. Moreover, a dominant-negative form of JNK （but not of p38） enhanced NF-κB activation, suppressed caspase-8 recruitment in death-inducing signaling complexes （DISCs）, and reduced adverse effects on mitochondria, thereby inhibiting AD5-10-induced cell death in Jnrkat leukemia cells. These data provide novel information on the DR5-mediated ceil death-signaling path- way and may shed new light on effective strategies for leukemia and solid tumor therapies.
基金Acknowledgments We are grateful to the staff members at Shanghai Synchrotron Radiation Facility for support in diffraction data collection and other members of our group for helpful discussion. This work was supported by grants from the Ministry of Science and Technology of China （2010CB833601, 2006AA02A313, and 2009ZX09503- 009）, the National Natural Science Foundation of China （30730028 and 90713046）, and the Chinese Academy of Sciences （KSCX2-YW-R- 107 and SIBS2008002）.
文摘Interleukin-2 （IL）-2 signaling plays a pivotal role in the activation of immune responses, and drugs that block this pathway have been shown to be effective for the immunosuppression in patients with organ transplantation to alleviate/eliminate allograft rejection. The first humanized monoclonal antibody （mAb） daclizumab falls into this category and shows high specificity and affinity against a key component of the IL-2 receptor complex, namely IL-2Ra. To reveal the molecular mechanism of the inhibition of the IL-2 signaling pathway by dacllzumab, we determined the crystal structures of the daclizumab Fab in free form and in complex with the IL-2Ra ectodomain at 2.6 and 2.8 A resolution, respectively. The daclizumab Fab adopts a similar conformation in the presence or absence of the IL- 2Ra ectodomain. The antigen-binding site of daclizumab is mainly composed of live complementarity determining regions （CDRs） that form a large positively charged surface depression and two flanking patches that are generally hydrophobic. The conformational epitope consists of several discontinuous segments of the IL-2Ru ectodomain, a large portion of which overlaps with the regions that interact with IL-2, suggesting that the binding of daclizumab to IL-2Ra would prevent the IL-2 binding to IL-2Ra and the subsequent formation of the IL-2fIL-2Ra[~/c complex, and therefore block the IL-2 signaling pathway. These results also have implications for the design and development of improved mAb drugs targeting IL-2Ra.
基金Supported by the National Natural Scientific Foundation of China (No. 30170396)
文摘Objective：To investigate the expression of CXCR4 on HL-60 cell line and the proliferation, apoptosis of HL-60 cell line cocultured with bone marrow stromal cells, so as to assess the possibility of 12G5, an anti-CXCR4 monoclonal antibody, in eradicating the minimal residual disease. Methods：The activity of SDF-1 was inhibited by 10 μg/ml 12G5. After treatment with 12G5, the status of adhesion was observed, and the adhesion rates, apoptosis and cell cycles were detected after 24 h of treatment. Cell growth rates were measured by trypan blue exclusion. Cell growth curve was plotted, and the expression of PCNA and apoptosis related protein including PCNA, Bcl-2 and Fas were detected with immunohistochemical technique. Results：（1） There was middling degree expression of CXCR4 on HL-B0 membrane. From 0 h to 6 h, as the time of 12G5 incubation along, the expression of CXCR4 decreased gradually. （2） After treatment for 24 h, the adhesion rates in the experiment group and the control were （39.4±7.9）% and （51.4±5.9）%, respectively. （3）After treatment for 24 h, the percentage of HL-60 cells in G0/G1 phase were （55.21±4.9）%, and that in S phase and G2/M phase were （30.40±4.1）% and （14.39± 5.2）%, respectively, with the corresponding proportions being （44. 67±2.2）%, （45.30±3.7）%, and （10. 03±2.6）% in the control. （4） The percentage of apoptotic HL-60 cells was （8.95±1.7）% in the experiment group, compared to （3. 97±2. 4）% in the control. （5）The survival rates of HL-60 cells decreased markedly at 48 h to 96 h, and the proliferation slowed down at this time duration. （6）The expression of PCNA and Bcl-2 down-regulated significantly, but the Fas protein expression was up-regulated. Conclusion：12G5 could inhibit the capability of adhesion and proliferation of HL-60 cells and it can induce more cells to enter G0/G1 phase and promote apoptosis. It may be helpful by inhibiting the bioactivity of SDF-1 with 12G5 in the therapy of marrow residual disease.
