OSBP-related Protein 4L Abrogation By OSW-1 Results In T-ALL Cell Death

T-cell acute lymphoblastic leukemia?T-ALL?is one of the deadliest and most aggressive hematological malignancies.T-ALL cells preferentially use oxidative phosphorylation as a source of ATP to sustain cells survival.According to our previous research,ORP4L interactes with both G?_q/11/11 and PLC?3 and support T-ALL cell survival via mediating ORP4L/G?_q/11/PLC?3 signal pathway Thus,ORP4L might be a key therapeutic target for T-ALL treatment.However,the related chemical compound targeting ORP4L against T-ALL remains unclear.Oxysterol binding protein-related protein-4L?ORP4L?is a member of the Oxysterol binding protein?OSBP?family,which plays an important role in cellular lipid metabolism,proliferation,differentiation and apoptosis.Our previous study reported that ORP4L modulates the movement and phosphorylation of PLC?3 through intracellular mediation of G protein-dependent cellular signals,which in turn affects calcium homeostasis and energy supply in T-ALL cells,ultimately affecting cell survival.In this study,we further confirmed that ORP4L interacts directly with the ITPR1,which in turn regulates the release of Ca²⁺in T-ALL cells.Recently,it has been found that natural compound OSW-1 has a highly cytotoxic effect on tumor cell lines and targets OSBP/ORP4L,but its mechanism is unknown.This study found that OSW-1 treatment results in T-ALL cell death,while overexpression of ORP4L can attenuate the above cytotoxicity for T-ALL cells.We found that OSW-1 treatment results in the translocation of ORP4L in T-ALL cells,weakening the interaction between ORP4L and ITPR1,inhibiting the Ca²⁺oscillation and eventually reducing the production of ATP.However,overexpression of ORP4L can counteract the inhibition of OSW-1 on Ca²⁺release and ATP production in T-ALL cells,thereby maintaining cell survival.Finally,we injected OSW-1 pretreated Jurkat T cells into NOD/SCID mice and found that OSW-1 can significantly inhibit the survival of T-ALL cells in vivo.In conclusion,this study found that ORP4L interacts with ITPR1 in T-ALL cells and maintains calcium homeostasis and cell survival.Meanwhile,by targeting ORP4L,OSW-1blocks the interaction between ORP4L and ITPR1,which inhibits the Ca²⁺oscillation and ATP production in T-ALL cells,eventually causing cell death.These results reveal that OSW-1 is a natural small molecule compound targeting ORP4L for the treatment of acute T-lymphocytic leukemia,which is worth for the further research.