The Role Of SUMOylation And OPN In AML

Objective:Post-translational modification(PTM)is an essential mechanism for regulating protein function.Targeting PTM,which is expected to reduce off-target effect caused by tumor cells heterogeneity,is one of the main strategies to solve the bottleneck problem of molecular therapy.SUMOylation,as a core mechanism of PTM,is closely correlated to tumorigenesis.Targeting SUMOyaltion has shown a favorable application potential in hematological malignancies.However,we know few about the role of SUMOylation key genes in the generation and maintenance of AML.UBC9 is the only E2 of SUMOylation,thus it is a key regulator of Sumoylation.Here,we generated Ubc9fl/+;Vav-cre mice to investigate the effect of Ubc9 haploinsufficiency on normal hematopoiesis,leukemogenesis and leukemia maintenanceMethod:Ubc9fl/+;Vav-cre mice were backcrossed to U9fl/fl mice to generate Ubc9 spontaneous knockout mice,experimental mice were age matched littermates.However,we found Ubc9fl/fl;Vav-cre mice died before birth.So we turned to compare the differences between Ubc9fl/+;Vav-cre mice and Ubc9fl/+ mice.Both groups of mice were sacrificed at 6-8 weeks,the proportion and numbers of mature cells in BM,PB,SP,thymus and HSPC were calculated.Then we employed a retrovirus system to overexpress human MLL-AF9 fusion gene in mouse c-Kit+ cells.And we characterized the immunophenotype and biological signature of the leukemia cells and LSCs by FACS.Results:Except for the declined proportion and reduced number of DN cells in thymus and CLP cells in BM,the normal hematopoiesis was not affected by Ubc9 haploinsufficiency.CFC with whole bonw marrow cells and LSK+ cells had no difference between these two groups.Ubc9 haploinsufficiency accelerated the progression of AML by increasing sternness and enhancing cell cycle progression.Conclusion:In summary we have shown that Ubc9 haploinsufficiency mildly affected the normal hematopoiesis and could accelerated the progression of MLL-AF9.Ubc9 might act like a tumor suppressor gene in AML.Objective:Acute myeloid leukemia(AML)is the most common acute leukemia in adults.AML is now cured in 35 to 40%of adult patients who are 60 years of age or younger and in 5 to 15%of patients who are older than 60 years of age.The outcome in older patients who are unable to receive intensive chemotherapy without unacceptable side effects remains dismal,with a median survival of only 5 to 10 months.Leukemia stem cell(LSC)is closely associated with the generation of AML and is the main cause of the recurrence after remission.OPN is an extracellular matrix protein which plays an important role in the migration,invasion and proliferation of tumor cells.However,whether OPN could affect the biological signature of LSC remains unclear.Thus we established a Opn Knock-down MLL-AF9 mouse model and OPN knock-down human Leukemia cell-lines to investigated the role of OPN in AML.Method:We used RNA interference system to knock down Opn in MLL-AF9 mouse models and human leukemia cell-lines.Then we characterized the immunophenotype and biological signature by FACS and CFC.Results:By analyzing the gene expression level,we found that Opn was significantly and highly expressed in LSCs.Opn knock down significantly prolonged the survival of leukemic mice and decreased the leukemia burden by decreasing the capacity of LSC and promote LSC apoptosis.The human leukemia cell-line shows the same phenotype as the leukemic mice.Conclusion:In summary,we found that OPN might be a good therapeutic target for eradicating LSCs in AML.