Role of HMGB1 in regulation of STAT3 expression in CD4(+) T cells from patients with aGVHD after allogeneic hematopoietic stem cell transplantation.

Treg/Th17 balance plays a critical role in maintaining immune homeostasis of acute graft-versus-host disease (aGVHD) patients. STAT3 is an important factor involved in the instability of Treg and the promotion of Th17. HMGB1 is a cytokine mediator of inflammation and an important chromatin protein regulating gene transcription. In this study, we found that the expressions of HMGB1 and STAT3 were higher in CD4(+) T cells of patients with aGVHD compared with those without aGVHD, and the HMGB1 expression was positively correlated with the STAT3 expression. Simultaneously, their expressions were positively correlated with the severity of the aGVHD. We also demonstrated that HMGB1 could regulate the expression of STAT3 by modulation of its DNA methylation in CD4(+) T cells, moreover downregulated HMGB1 in aGVHD CD4(+) T cells could change the ratio of Treg/Th17. These data strongly suggest that HMGB1 plays a crucial role in the regulation of Treg/Th17 and progression of aGVHD.

SUMOylation of insulin-like growth factor 1 receptor, promotes proliferation in acute myeloid leukemia.

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.

PTEN regulates BCRP/ABCG2 and the side population through the PI3K/Akt pathway in chronic myeloid leukemia.

A small population of cancer stem cells named the "side population" (SP) has been demonstrated to be responsible for the persistence of many solid tumors. However, the role of the SP in leukemic pathogenesis remains controversial. The resistance of leukemic stem cells to targeted therapies, such as tyrosine kinase inhibitors (TKIs), results in therapeutic failure or refractory/relapsed disease in chronic myeloid leukemia (CML). The drug pump, ATP-binding cassette sub-family G member 2 (ABCG2), is well known as a specific marker of the SP and could be controlled by several pathways, including the PI3K/Akt pathway. Our data demonstrated that compared with wild-type K562 cells, the higher percentage of ABCG2+ cells corresponded to the higher SP fraction in K562/ABCG2 (ABCG2 overexpressing) and K562/IMR (resistance to imatinib) cells, which exhibited enhanced drug resistance along with downregulated phosphatase and tensin homologue deleted on chromosome -10 (PTEN) and activated phosphorylated-Akt (p-Akt). PTEN and p-Akt downregulation could be abrogated by both the PI3K inhibitor LY294002 and the mTOR inhibitor rapamycin. Moreover, in CML patients in the accelerated phase/blastic phase (AP/BP), increased SP phenotype rather than ABCG2 expression was accompanied by the loss of PTEN protein and the up-regulation of p-Akt expression. These results suggested that the expression of ABCG2 and the SP may be regulated by PTEN through the PI3K/Akt pathway, which would be a potentially effective strategy for targeting CML stem cells.

MiR-223 regulates human embryonic stem cell differentiation by targeting the IGF-1R/Akt signaling pathway.

Currently, there are difficulties associated with the culturing of pluripotent human embryonic stem cells (hESCs), and knowledge regarding their regulatory mechanisms is limited. MicroRNAs (miRNAs) regulate gene expression and have critical functions in stem cell self-renewal and differentiation. Moreover, fibroblast growth factor (FGF) and the insulin-like growth factor receptor (IGF-1R) are key activators of signaling in hESCs. Based on the identification of complementary binding sites in miR-223 and IGF-1R mRNA, it is proposed that miR-223 acts as a local regulator of IGF-1R. Therefore, levels of miR-223 were detected in differentiated versus undifferentiated hESCs. In addition, proliferation, apoptosis, and differentiation were assayed in these two hESC populations and were compared in the presence of exogenous miR-223 and miR-223 inhibitor. Inhibition of miR-223 was found to maintain the undifferentiated state of hESCs, while addition of miR-223 induced differentiation. Furthermore, these effects were found to be likely dependent on IGF-1R/Akt signaling.

Inactivation of PTEN increases ABCG2 expression and the side population through the PI3K/Akt pathway in adult acute leukemia.

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.

MicroRNA-20b and ERK1/2 pathway independently regulate the expression of tissue factor in hematopoietic and trophoblastic differentiation of human embryonic stem cells.

INTRODUCTION: Tissue factor (TF) is expressed in various types of cells. TF expression is essential for many biological processes, such as blood coagulation and embryonic development, while its high expression in stem cells often leads to failure of transplantation. In this study, we used the human embryonic stem cell (hESC) culture system to understand the molecular mechanisms by which TF expression is regulated in hESC-derived hematopoietic and trophoblastic cells. METHODS: hESCs were induced in vitro to differentiate into hematopoietic and trophoblastic cells. TF expression in various types of cells during these differentiation processes was examined by quantitative real-time polymerase chain reaction analysis and western blot analysis. The regulatory mechanisms of TF expression were investigated by miRNA expression analysis, luciferase report assay, TF mRNA and protein analysis, and pathway phosphorylation analysis. RESULTS: We first found that TF was expressed only in trophoblasts and granulocyte-monocyte (G-M) cells differentiated from hESCs; and then demonstrated that miR-20b downregulated and Erk1/2 signaling pathway upregulated the TF expression in trophoblasts and G-M cells. Finally, we found that miR-20b downregulated the TF expression independently of the Erk1/2 signaling pathway. CONCLUSIONS: The miR-20b and Erk1/2 pathway independently regulate expression of TF in trophoblasts and G-M cells differentiated from hESCs. These findings will open an avenue to further illustrate the functions of TF in various biological processes.

[Therapeutic effect of priming induction regimen of CAG for newly diagnosed acute myeloid leukemia in elderly patients].

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.

[Relation between the expression of sIL-2R and the relapse in patients with acute lymphoblastic leukemia].

OBJECTIVE: To explore the relation of the serum level of sIL-2R in relapse patients with acute lymphoblastic leukemia (ALL). METHODS: With ELISA, we determined the levels of sIL-2R of 48 patients with ALL after their first diagnoses, complete remission 1 and relapse. The levels of sIL-2R of 30 patients from complete remission 1 to relapse were monitored. RESULTS: The levels of sIL-2R were higher in the relapse group and first diagnosed group than in the control. The levels of sIL-2R were higher in the relapse group and first diagnosed group than in the complete remission 1 group. However, the difference between the complete remission 1 and the control had no statistical significance. When we determined the levels of sIL-2R dynamically, we found that after complete remission, the levels of sIL-2R decreased, however, before one month of hematological relapse, the levels of sIL-2R increased. CONCLUSION: Monitor of the level of sIL-2R can predict impending relapse of patients with ALL and is helpful to early diagnosis of relapse.

[Clinical analysis of 282 patients with non-Hodgkin's lymphoma].

OBJECTIVE: To analyze the classification, stage and prognosis of non-Hodgkin's lymphoma (NHL). METHODS: Two hundred eighty two patients with NHL were retrospectively reviewed. RESULTS: The complete remission (CR) rate and 5-year survival rate of B-cell NHL were higher than those of T-cell NHL(P < 0.05). There were significant differences in CR rate and 5-year survival rate among the low-grade, the intermediate-grade and the high-grade NHL(P < 0.05). The CR rate and 5-year survival rate of patients who were treated by the scheme of doxorubicin, cyclophosphamide, vincristine and prednisone (CHOP) were higher than those treated by the scheme of cyclophosphamide, vincristine, prednisone and etoposide (COP + VP16) (P < 0.05). CONCLUSION: Rational classification and staging play an important role in the prognosis of NHL. CHOP-based scheme may be regarded as the first choice and the standard scheme of treatment.