The Synergistic Effect And Mechanism Of Venetoclax And Arsenic Trioxide In Myelodysplastic Syndrome

BackgroundMyelodysplastic syndrome(Myelodysplastic Syndrome,MDS)is a group of myeloid malignant tumors derived from hematopoietic stem cells,which is characterized by abnormal morphology of bone marrow cells,ineffective hematopoiesis leading to hemocytopenia,clonal instability and the risk of transformation to acute myeloid leukemia.The incidence of MDS in people over 65 years old is as high as 75-162 / 100,000 pop?lation,which is the most common malignant hematological disease in the elderly.Allogeneic hematopoietic stem cell transplantation is the only treatment for longterm remission in patients with MDS,but it is only suitable for a small number of patients.Demethylation drugs can improve the median survival time of 40% to 60% patients,but can not eradicate malignant clones,and the time to maintain the efficacy is limited.If the treatment fails,the median survival time is less than 6 months.The treatment of these patients is still facing challenges.Studies have shown that BCL-2 family proteins play an important role in the disease progression and chemotherapy resistance of MDS,so the selective BCL-2 inhibitor Venetoclax(ABT-199/GDC0199)is expected to benefit MDS patients.The effect of Venetoclax monotherapy on patients with myeloid malignant hematological diseases is limited,and it is easy to produce drug resistance.The combination of Venetoclax and other drugs is more conducive to achieve deep and lasting remission.In view of the m?lti-target anti-tumor characteristics of the traditional drug arsenic trioxide(ATO)and the clinically proven safety,we intend to explore the role of Venetoclax combined with ATO in High-risk MDS,so as to provide theoretical support for its clinical application in the future.PurposeToexplore the effect of selective BCL-2 inhibitor Venetoclax combined with arsenic trioxide(ATO)on High-risk MDS cells,and further clarify the mechanism.MethodsHigh-risk MDS cell lines(MDS-L,SKM-1,MOLM-13)and High-risk MDS primary patient cells were treated with different concentrations of Venetoclax and arsenic trioxide(ATO)alone or in combination.MTS assay was used to detect the inhibitory effect on cell proliferation.The Calcu Syn software was used to calc?late the combined index(CI).Flow cytometry was used to detect the effects of drugs on apoptosis,mitochondrial membrane potential and the level of ROS in mitochondria.The cells treated with single or combined drugs were collected,and the changes of apoptosisrelated proteins and cell proliferation-related signal pathway proteins were verified by Western Blot.Double-tailed t-test or m?ltiple groups of ANOVA were used for statistical analysis of bioassay.P <0.05 was considered statistically significant.Results1.Venetoclax combined with ATO co?ld significantly inhibit the proliferation and induce apoptosis of High-risk MDS cell lines MDS-L,SKM-1,MOLM-13 and High-risk MDS primary patient cells.2.ATO plays a synergistic role in promoting apoptosis by increasing the decrease of mitochondrial membrane potential induced by Venetoclax and the production of ROS.3.ATO exerts synergistic antitumor effect by inhibiting the phosphorylation of AKT and activating GSK-3 ? to promote the degradation of MCL-1..ConclusionIn this study,we found that the combination of BCL-2 inhibitor Venetoclax and ATO co?ld significantly inhibit the proliferation and induce apoptosis of High-risk MDS cell lines MDS-L,SKM-1 and MOLM-13.The combination of the two drugs also showed synergistic inhibitory effect in primary High-risk MDS cells.After further exploring its mechanism,it was found that on the one hand,Venetoclax and ATO cooperated on mitochondria,induced the decrease of mitochondrial membrane potential,decreased the apoptosis threshold,promoted the production of mitochondrial ROS and induced the apoptosis of MDS cells.On the other hand,ATO activates GSK-3 ? by inhibiting the phosphorylation of AKT,and the activated GSK-3 ? phosphorylates the Ser159 site of the anti-apoptotic protein MCL-1,which res?lts in degradation of MCL-1 by proteasome,thus exerting a synergistic anti-tumor effect.