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
Boanmycin (bleomycin A6 . BM) . an antitumor antibiotic, was conjugated to monoclonal antibodies including R19, H 111 and CCT2. The immunoconjugates exhibited selective cytotoxicity to related target cells including c...Boanmycin (bleomycin A6 . BM) . an antitumor antibiotic, was conjugated to monoclonal antibodies including R19, H 111 and CCT2. The immunoconjugates exhibited selective cytotoxicity to related target cells including cecum cancer Hce-8693 cells, liver cancer BEL-7402 cells and leukemia CEM cells. They were highly effective against related human tumor xenografts in nude mice, and the inhibition rates by the conjugates were much higher than those by free BM. The inhibition rate by R19-BM conjugate against human cecum cancer xenografts reached 90%. BY immunoelectron microscopy, CCT2-BM conjugate showed specific binding and internalization in leukemia CEM cells. The results indicate that boanmycin-monoclonal antibody immunoconjugates are highly active both in vitro and in vivo.展开更多
This study characterized the activation of platelet integrin α bβ3 induced by two anti human platelet tetraspanin monoclonal antibodies(mAbs),HI117 and SJ9A4. Methods.Using 125 I labeled human fibrinogen(Fg),specifi...This study characterized the activation of platelet integrin α bβ3 induced by two anti human platelet tetraspanin monoclonal antibodies(mAbs),HI117 and SJ9A4. Methods.Using 125 I labeled human fibrinogen(Fg),specific Fg binding to human platelets induced by HI117 and SJ9A4 was measured as indication of activation of platelet integrin αbβ3 by the two mAbs. Results.HI117 and SJ9A4(10μg/ml and 20μg/ml) induced evident specific Fg binding to human platelets,suggesting that the two mAbs evoked activation of platelet integrin αbβ3.Further study indicated that HI117 and SJ9A4 induced integrin αⅡbβ3 activation independent of platelet Fc receptors, and that HI117 and SJ9A4 induced integrin αbβ3 activation was inhibited by sphingosing, aspirin, apyrase, and/or PGI2. Conclusion.The anti platelet tetraspanin(CD9)mAbs,HI117 and SJ9A4, can induce platelet integrin αⅡbβ3 activation independent of Fc receptors.Three signaling pathways,i.e.thromboxane,secreted ADP, and cAMP pathways may be involved in the process,with protein kinase C activation presumably being the common step of the three pathways.展开更多
Recent studies have demonstrated that the membrane-proximal external region （MPER） of human immunodeficiency virus 1 （HIV-1） glycoprotein 41 contains a series of epitopes for human monoclonal antibodies, including...Recent studies have demonstrated that the membrane-proximal external region （MPER） of human immunodeficiency virus 1 （HIV-1） glycoprotein 41 contains a series of epitopes for human monoclonal antibodies, including 2F5, Zl3el, 4El0, and 10E8, which were isolated from HIV-l-infected individuals and show broad neutralizing activities. This suggests that MPER is a good target for the development of effective HIV-1 vaccines. However, many studies have shown that it is difficult to induce antibodies with similar broad neutralizing activities using MPER-based peptide antigens. Here, we report that 10E8-1ike neu- tralizing antibodies with effective anti-HIV-1 activity were readily induced using a precisely designed conformational immu- nogenic peptide containing the 10E8-specific epitope. This immunogenic peptide （designated T10HE） contains a 15-mer MPER-derived 10E8-specific epitope fused to T-helper-cell epitopes from tetanus toxin （tt）, which showed a significantly sta- bilized a-helix structure after a series of modifications, including substitution with an （S）-c^-（2＇-pentenyl） alanine containing an olefin-bearing tether and ruthenium-catalyzed olefin metathesis, compared with the unmodified T10E peptide. The stabilized （x-helix structure of T10HE did not affect its capacity to bind the 10E8 antibody, as evaluated with an enzyme linked immuno- sorbent assay （ELISA） and surface plasmon resonance binding assay （SPR assay）. The efficacies of the T10HE and T10E epitope vaccines were evaluated after a standard vaccination procedure in which the experimental mice were primed with ei- ther the T10HE or T10E immunogen and boosted with HIV-1 JRFL pseudoviruses. Higher titers of 10E8-1ike antibodies were induced by T10HE than that by T10E. More importantly, the antibodies induced by T10HE showed enhanced antiviral potency against HIV-1 strains with both X4 and R5 tropism and a greater degree of broad neutralizing activity than the antibodies in- duced by T10E. These results indicate that a 10E8-epitope-based structure-specific peptide immunogen can elicit neutralizing antibodies when used as a vaccine prime.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.
文摘Boanmycin (bleomycin A6 . BM) . an antitumor antibiotic, was conjugated to monoclonal antibodies including R19, H 111 and CCT2. The immunoconjugates exhibited selective cytotoxicity to related target cells including cecum cancer Hce-8693 cells, liver cancer BEL-7402 cells and leukemia CEM cells. They were highly effective against related human tumor xenografts in nude mice, and the inhibition rates by the conjugates were much higher than those by free BM. The inhibition rate by R19-BM conjugate against human cecum cancer xenografts reached 90%. BY immunoelectron microscopy, CCT2-BM conjugate showed specific binding and internalization in leukemia CEM cells. The results indicate that boanmycin-monoclonal antibody immunoconjugates are highly active both in vitro and in vivo.
文摘This study characterized the activation of platelet integrin α bβ3 induced by two anti human platelet tetraspanin monoclonal antibodies(mAbs),HI117 and SJ9A4. Methods.Using 125 I labeled human fibrinogen(Fg),specific Fg binding to human platelets induced by HI117 and SJ9A4 was measured as indication of activation of platelet integrin αbβ3 by the two mAbs. Results.HI117 and SJ9A4(10μg/ml and 20μg/ml) induced evident specific Fg binding to human platelets,suggesting that the two mAbs evoked activation of platelet integrin αbβ3.Further study indicated that HI117 and SJ9A4 induced integrin αⅡbβ3 activation independent of platelet Fc receptors, and that HI117 and SJ9A4 induced integrin αbβ3 activation was inhibited by sphingosing, aspirin, apyrase, and/or PGI2. Conclusion.The anti platelet tetraspanin(CD9)mAbs,HI117 and SJ9A4, can induce platelet integrin αⅡbβ3 activation independent of Fc receptors.Three signaling pathways,i.e.thromboxane,secreted ADP, and cAMP pathways may be involved in the process,with protein kinase C activation presumably being the common step of the three pathways.
基金supported by Ministry of Science and Technology of China(2012ZX10001-009)
文摘Recent studies have demonstrated that the membrane-proximal external region （MPER） of human immunodeficiency virus 1 （HIV-1） glycoprotein 41 contains a series of epitopes for human monoclonal antibodies, including 2F5, Zl3el, 4El0, and 10E8, which were isolated from HIV-l-infected individuals and show broad neutralizing activities. This suggests that MPER is a good target for the development of effective HIV-1 vaccines. However, many studies have shown that it is difficult to induce antibodies with similar broad neutralizing activities using MPER-based peptide antigens. Here, we report that 10E8-1ike neu- tralizing antibodies with effective anti-HIV-1 activity were readily induced using a precisely designed conformational immu- nogenic peptide containing the 10E8-specific epitope. This immunogenic peptide （designated T10HE） contains a 15-mer MPER-derived 10E8-specific epitope fused to T-helper-cell epitopes from tetanus toxin （tt）, which showed a significantly sta- bilized a-helix structure after a series of modifications, including substitution with an （S）-c^-（2＇-pentenyl） alanine containing an olefin-bearing tether and ruthenium-catalyzed olefin metathesis, compared with the unmodified T10E peptide. The stabilized （x-helix structure of T10HE did not affect its capacity to bind the 10E8 antibody, as evaluated with an enzyme linked immuno- sorbent assay （ELISA） and surface plasmon resonance binding assay （SPR assay）. The efficacies of the T10HE and T10E epitope vaccines were evaluated after a standard vaccination procedure in which the experimental mice were primed with ei- ther the T10HE or T10E immunogen and boosted with HIV-1 JRFL pseudoviruses. Higher titers of 10E8-1ike antibodies were induced by T10HE than that by T10E. More importantly, the antibodies induced by T10HE showed enhanced antiviral potency against HIV-1 strains with both X4 and R5 tropism and a greater degree of broad neutralizing activity than the antibodies in- duced by T10E. These results indicate that a 10E8-epitope-based structure-specific peptide immunogen can elicit neutralizing antibodies when used as a vaccine prime.
