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We investigated the roles of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptor death receptor 5 (DR5) in the onset of acute leukemia and changes in their expression during chemotherapy. Bone marrow samples from 16 patients newly diagnosed with acute leukemia were collected before chemotherapy. Bone marrow samples from patients with non-hematologic malignancies served as the control group. Peripheral blood samples of patients with acute leukemia were also collected before chemotherapy and at 1 and 3 days after chemotherapy. Mononuclear cells in the bone marrow and peripheral blood were isolated and used to detect the expression of TRAIL and DR5 by flow cytometry. Compared with mononuclear cells from the control group, mononuclear cells from newly diagnosed patients with acute leukemia showed no significant difference in the expression of TRAIL (P > 0.05) but showed significantly increased expression of DR5 (P < 0.05). TRAIL and DR5 expression in peripheral blood mononuclear cells after chemotherapy was significantly increased compared to expression before chemotherapy (P < 0.05). Patients showing high expression of DR5 had a higher remission rate. One of the mechanisms underlying the treatment of leukemia with chemotherapy drugs may be the induction of TRAIL and DR5, which may promote apoptosis in leukemia cells. TRAIL-mediated apoptosis is regulated by DR5 expression.

Objective: To explore the expression of PD-L1 in acute leukemia patients, and to analyze the relationship of PD-L1 expression with the patients' clinical characteristics and prognosis., Methods: The expression of PD-L1 in leukemia cells of 75 patients including 59 de novo patients and 16 relapse/refractory patients with acute leukemia was detected by the flow cytometry, the clinical information was collected, and the therapeutic efficacy of de novo patients was analyzed., Results: The PD-L1 was expressed in human acute leukemia cells with total expression rate 32% (24/75), and its expression level in AML-M5 was higher than that in other leukemias [56.3% (9/16) vs 25.4% (15/59)], there was statistical significance (P = 0.019). The PD-L1 possitive rate in relapse/refractory group was higher than that in de novo patient group [(56.3% (9/16) vs 25.4% (15/59)], and there was statistical significance (P = 0.019). In 59 de novo patients, the CR rate of PD-L1 positive group after 1 course of chemotherapy was lower than that in PD-L1 negative group (66.7% vs 71.4%), the CR rate of PD-L1 positive group after 2 courses of chemotherapy was also lower than that in PD-L1 negative group (70% vs 88.6%). The relapse rate and the proportion of refractory patients in PD-L1 possitive group were higher than those in PD-L1 negative group. The expression of PD-L1 did not correlated with the clinical parameters, such as sex, age, extramedullary infiltration, percentage of blast cells in bone marrow, counts of WBC, RBC and platelet, as well as molecular biological features and cytogenetical characteristics., Conclusion: PD-L1 is expressed in human acute leukemia cells, and may be involved in the immune escape and primary resistant mechanisms, PD-L1 may be used as an indicator for evaluation of the the patients' prognosis and reocurrence.

The aim of this study was to explore the expression of beta-catenin in acute leukemia bone marrow cells and its role in the development of acute leukemia. The expression of beta-catenin of bone marrow cells was detected by immunocytochemistry and flow cytometry in 20 cases of newly diagnosed acute leukemia. Meanwhile the expression of the proliferating index Ki-67 was detected by immunocytochemistry. The results showed that the expression of beta-catenin and Ki-67 in acute leukemia bone marrow cells was significantly higher than those in control group (P < 0.05). The migration of beta-catenin from cytoplasm to nuclear was observed in acute leukemia bone marrow cells. There was a positive correlation between the expressions of beta-catenin and Ki-67 in all the cases and the Pearson correlation coefficient was 0.845. In conclusion, the expression of beta-catenin was significantly high in acute leukemia bone marrow cells and showed a positive correlation with the cell proliferation. It suggests that beta-catenin may be involved in the development of acute leukemia through promoting the excessive proliferation of cells.

In order to explore the expression of TRAIL in primary acute leukemic cells and the effect of chemotherapeutic drug on TRAIL expression in acute leukemic cells, the expression of TRAIL was assessed by flow cytometry on day 0, day 1, day 3 and day 5 in 16 patients with acute leukemia received chemotherapy. Meanwhile, the bone marrow mononuclear cells of acute leukemia patients were cultured in vitro with VP-16 and INFalpha-2a. Expression of TRAIL was analyszed by flow cytometry at 24, 48 and 72 hours after treatment. The results showed that the expression of TRAIL in the peripheral blood mononuclear cells was upregulated significantly from day 1 after chemotherapy (P < 0.05). In in vitro culture test, VP-16 upregulated the expression of TRAIL on acute leukemia bone marrow mononuclear cells (P < 0.05). Compared with VP-16 alone, the combination of VP-16 with IFNalpha-2a showed no synergic effects on the expression of TRAIL. It is concluded that the expression of TRAIL increases after chemotherapy in vivo and after treatment with VP-16 and IFN in vitro, which suggests that the apoptosis induced by TRAIL may play an important role in chemotherapy of leukemia.