Aim: To investigate the cytotoxic action and its mechanism of a novel anti-human DR5 monoclonal antibody (mAb mDRA-6).
Methods: The cytotoxic action of mAb mDRA-6 on Jurkat cells and the effects of inhibitors of caspase 8 and caspase 9 on apoptosis of Jurkat cells induced with mAb mDRA-6 were detected by flow cytometry. The effects of mAb mDRA-6 on the morpha of Jurkat cells was observed by fluorescence microscope. The apoptosis of Jurkat cells was detected by flow cytometry with Annexin V-FITC/PI staining. The DNA fragmentation in Jurkat cells was analysed by agrose gel electrophoresis.
Results: mAb mDRA-6 exerted cytotoxicity on Jurkat cells in dose-dependent and time-dependent manner. Jurkat cells treated with mDRA-6 exhibited typical apoptostic features in morphology, namely, membrane crenation, bubbling, chromatin condensation, and formation of apoptotic bodies. The flow cytometry analysis showed that phosphatidylserine (PS) was highly expressed in Jurkat cells treated with mDRA-6. Agrose gel electrophoresis indicated that DNA fragmentation occurred in Jurkat cells. Inhibitor of caspase 8 inhibited the apoptosis of Jurkat cells induced with mDRA-6 while Inhibitor of caspase 9 showed less effect.
Conclusion: mDRA-6 may exert cytotoxicity by inducing Jurkat cell apoptosis through signal transduction pathway of death receptors, which may be a useful tool in treating tumors with DR5 as target molecule and exploring the functional domain of DR5.