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Current valid treatments for acute myeloid leukemia (AML) include chemotherapy and hematopoietic stem cell transplantation, which are defective and limited respectively. The insulin-like growth factor 1 receptor (IGF-1R) is up-regulated in many solid tumors; therefore, it may be a target for tumor therapy. Interestingly, IGF-1R is modified by SUMOylation, a type of reversible post-translational modification. In this study, we found that IGF-1R was increased in both cell lines and clinical samples of AML and was modified by SUMO-1. Furthermore, IGF-1, ligand of IGF-1R, induced the up-regulation of IGF-1R and increased the proliferation of leukemia cell line. After mutation of Lys(1025) and Lys(1100) in IGF-1R, the evolutionarily conserved lysine residues were identified as the SUMOylation sites of IGF-1R, because the SUMOylation of IGF-1R in these mutants was significantly inhibited. Furthermore, the cell proliferation mediated by IGF-1 was also reduced. After inhibition of UBC9, the activating enzyme of SUMOylation, co-expression of IGF-1R and SUMO-1 was down-regulated, and cell proliferation was also inhibited. However, cell apoptosis was not significantly affected. These results suggest that IGF-1R and its SUMOylation may be a new therapeutic target for strategy of AML., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Both the occurrence and recurrence of acute leukemia (AL) might suggest the presence of leukemia stem cells. Side population (SP) cells, exhibiting stem cell-like properties, express ABCG2 (breast cancer resistance protein [BCRP]). This study revealed that over-expression of ABCG2 in Jurkat and HL60 cells led to an increased SP fraction, up-regulated levels of phosphorylated-PI3K and phosphorylated-Akt, and enhanced drug resistance, all of which could be attenuated by treatment with either the PI3K inhibitor LY294002 or the mTOR inhibitor rapamycin. ABCG2 expression and SP cell counts were further characterized in 222 adult AL patients at three disease stages: upon diagnosis, at remission and at refractory/relapse (R/R), while 10 healthy donors served as the normal controls. Only a small fraction of the ABCG2+population (0.05-12.3%) and SP cells (0.02-1.60%) were observed in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) patients. In the normal control population, the SP cell fraction represented a statistically higher percentage of total cells compared to the fraction of SP cells upon diagnosis or relapse in both AML and ALL. In addition, we demonstrated that ABCG2 expression and SP cell ratios can be upregulated by the inactivation of phosphatase and tensin homolog (PTEN) protein, achieved in this study by removing inhibition of the PI3K/Akt pathway. Collectively, this study suggests that the PTEN/PI3K/Akt pathway up-regulates ABCG2 expression and the SP cell population and is a potential AL-specific treatment target worth investigating further., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Objective: To evaluate the clinical efficacy and toxicity of priming induction regimen of CAG for newly diagnosed acute myeloid leukemia (AML) in elderly patients., Methods: Seventy-five patients with newly diagnosed AML were divided into 2 groups: 34 were treated with priming induction regimen CAG and the other 41 were treated with 2 classic routine chemotherapy regimens including pirarubicin+cytarabine (TA) and homoharringtonine+cytarabine (HA). All patients had a 14 day interval between the 2 courses of chemotherapy., Results: The complete remission rate after 2 courses of induction therapy in patients with the priming induction regimen CAG and the total efficacy rate was significantly higher than that of the routine chemotherapy patients(67.6% vs. 39%; 82.4% vs. 56.1%). Patients with unfavorable karyotypes had poor chemotherapy efficacy. The 3-year disease-free-survival (DFS) time was longer in patients with AML treated with priming induction regimen CAG than in patients treated with 2 classic routine chemotherapy regimens. Except for the muscular soreness, the hematological and non-hematological side effects in the CAG priming induction group were significantly fewer than those in the routine chemotherapy group., Conclusion: The priming induction regimen of CAG has a significantly higher complete remission rate and an efficacy rate, fewer side effects, milder chemotherapy intensity and is more sensitive to chemotherapeutic drugs than those of the routine chemotherapy. It can shorten the duration of agranulocytosis and decrease infectious complications and increase the sensitivity of leukemia blast cells to chemotherapeutic drugs.