ABSTRACT
Collaboration of c-KIT mutations with AML1-ETO (AE) has been demonstrated to induce t(8; 21) acute myeloid leukemia (AML). Targeted therapies designed to eliminate AE and c-KIT oncoproteins may facilitate effective treatment of t(8; 21) AML. Homoharringtonine (HHT) features activity against tumor cells harboring c-KIT mutations, whereas oridonin can induce t(8; 21) AML cell apoptosis and AE cleavage. Therefore, studies should explore the efficacy of combination therapy with oridonin and HHT in t(8; 21) AML. In this study, we investigated the synergistic effects and mechanism of oridonin combined with HHT in t(8; 21) AML cell line and mouse model. The two drugs synergistically inhibited cell viability and induced significant mitochondrial membrane potential loss and apoptosis. Oridonin and HHT induced significant downregulation of c-KIT and its downstream signaling pathways and promoted AE cleavage. HHT increased intracellular oridonin concentration by modulating the expressions of MRP1 and MDR1, thus enhancing the effects of oridonin. The combination of oridonin and HHT prolonged t(8; 21) leukemia mouse survival. In conclusion, oridonin and HHTexert synergistic effects against t(8; 21) leukemia in vivo and in vitro, thereby indicating that their combination may be an effective therapy for t(8; 21) leukemia.
ABSTRACT
Objective@#To investigate the characteristic and prognostic significance of leukemia stem cells associated antigens expressions including CD34, CD38, CD123, CD96 and TIM-3 in t (8;21) AML.@*Methods@#Bone marrow samples of 47 t (8;21) AML patients were collected at diagnosis from October 2015 to April 2018 in Peking University Peoples’ Hospital, then flow cytometry method was performed to detect the expression frequencies of CD34, CD38, CD123, CD96 and TIM-3 to analyze the relationship between leukemia stem cells associated antigens expressions and relapse.@*Results@#Of 47 t (8;21) AML patients tested, the median percentages of CD34+CD38-, CD34+ CD38-CD123+, CD34+CD38- CD96+ and CD34+ CD38- TIM-3+ cells among nucleated cells were 2.37%, 0.24%, 0.27% and 0.06%, respectively. All the frequencies of CD34+CD38-, CD34+CD38-CD123+, CD34+CD38-CD96+ and CD34+ CD38-TIM-3+ cells had no impact on the achievement of CR after the first course of induction. All higher frequencies of CD34+CD38-, CD34+CD38-CD123+, CD34+CD38-CD96+ cells were related to higher 2-year CIR rate. Whereas, the frequency of CD34+ CD38- TIM-3+ cells had no impact on CIR rate. Both high frequency of CD34+ CD38- cells and the high level of minimal residual diseases (patients with <3-log reduction in the RUNX1-RUNX1T1 transcript level after the second consolidation therapy) were independent poor prognostic factors of CIR[P=0.025, HR=6.9 (95%CI 1.3-37.4) ; P=0.031, HR=11.1 (95%CI 1.2-99.2) ].@*Conclusion@#Different leukemia stem cells associated antigens had distinct prognostic significance in t (8;21) AML. High frequencies of CD34+ CD38-, CD34+ CD38- CD123+ and CD34+CD38-CD96+ cells at diagnosis predicted relapse in patients with t (8;21) AML.