[Effect of Netrin-1 on VEGFA Expression in T-ALL Cells and Its Related Mechanism].

AbstractObjective: To investigate the effect of the axon guidance factor Netrin-1 on the expression of VEGFA in T cell acute lymphoblastic leukemia(T-ALL) and its related mechanism. METHODS: ELISA assays were applied to detect the levels of Netrin-1 and VEGFA in the bone marrow (BM) samples from children in the T-ALL and control group. The level of Netrin-1 and VEGFA were compared between control children and patients, and the liner correlation between Netrin-1 and VEGFA was analyzed. The T-ALL cells Jurkat and Molt-4 were culture in vitro, and the cells were treated with different concentration of Netrin-1 (0, 25, 50, 100 ng/ml) for 24 h, quantitative RT-PCR (qRT-PCR) and Western blot were used to detect the VEGFA expression in Jurkat, Molt-4 cells. The expression of Netrin-1 receptors in T-ALL cells was detected by qRT-PCR and the interaction between Netrin-1 and receptor in each cells was detected by co-IP. Furthermore, Western blot was used to detect the phosphorylation level of key prateins of AKT signal transduction pathway including Akt and mTOR in T-ALL cells treated with Netrin-1 (100 ng/ml). The expression of VEGFA and phosphorylation of AKT pathway transducers were detected by Western blot, after T-ALL cells treated with Netrin-1 (100 ng/ml) combined with inhibitors specific to Akt or mTOR. RESULTS: The expression level of Netrin-1 and VEGFA in T-ALL patients BM samples were both signi-ficantly higher than that of control group. And the expression level of Netrin-1 was positively correlated with that of VEGFA（r2=0974). With the increase of Netrin-1 concentration, the expression level of VEGFA also increased(P<0.05）. Netrin-1 interacted with its receptor, integrin-ß4 at the Netrin-1 concentration of 100 ng/ml. Further, the treatment of Netrin-1 could increase the phosphorylation of Akt and mTOR, which were the key transducers of AKT pathway. After treatment of T-ALL cells with Netrin-1 (100 ng/mL) and Akt inhibitor, the expression of VEGFA and phosphorylation of Akt or mTOR decreased. When the cells were treated with Netrin-1(100 ng/ml) and mTOR inbititor, the phosphorylation level of mTOR and the expression of VEGFA decreased, the phosphorylation level of Akt increased. CONCLUSION: The expression of Netrin-1 and VEGFA in bone marrow of childred with T-ALL were abnormal, and there was a linear relationship between them. Netrin-1 can interact with its receptor, integrin-ß4 and activate AKT transduction pathway to elevate the expression of VEGFA in T-ALL cells.

[Expression of Netrin-1 in Patients with Acute Lymphoblastic Leukemia and Its Clinical Significance].

OBJECTIVE: To investigate the correlation of the Netrin-1 expression level with the clinical characteristics in children with acute lymphoblastic leukemia (ALL) and to explore its possible regulatory mechanism. METHODS: ELISA was used to detect the expression level of Netrin-1 in peripheral blood serum from 48 child ALL patients (newly diagnosed, recurrent), and its relevance with clinical indicators was statistically analyzed. The blood serum samples from 27 children with non malignant hematological diseases were choosen as controls. Leukemia cell lines of Jurkat,Molt-4,SUP-B15 and Raji were cultivated in vitro, after treated with different concentrations of recombinant human Netrin-1 protein， the invasive ability of the cells was detected by Transwell method； the effect of Netrin-1 to the proli feration of cells was detected by CCK-8 method； The expression and phosphorylation level of key molecules, such as FAK,Erk1/2,PI3K and Akt signaling pathway were detected by Western blot. RESULTS: The expression of Netrin-1 in child patients was significantly higher than that of the control group (P<0.05). With the increasing of Netrin-1 level, the level of Plt (r=0.483, P<0.05) increased, while the level of WBC (r=-0.290, P<0.05) decreased, and there were no significant correlation with age, Hb level and the proportion of immature cells in bone marrow. When the concentration of Netrin-1 was 25-50 ng/ml, the level of Netrin-1 positively correlated with WBC (r=0.886, P<0.05) ; the level of Netrin-1 significantly decreased when the patient's WBC was ＞50×109/L and Plt ＞20×109/L(P=0.042，P=0.001); The expression level of Netrin-1 was significantly different in the risk group(P=0.017), and level of Netrin-1 in high-risk group was significantly higher than that in low risk group and middle risk group, but there was no significant difference of Netrin-1 expression in sex, hepatosplenomegaly, MRD, recurrence and chromosome abnormality. Netrin-1 could promote the invasiveness of the four kinds of cells (P<0.05). With the increase of Netrin-1 concentration, the number of cells increased at first and then decreased, and the number of cells in the invading chamber was the highest when the concentration of Netrin-1 was 100 ng/ml; the survival rate of the four kinds of cells significantly increased when the concentration of Netrin-1 was 25 ng/ml(P<0.05), and SUP-B15 cells showed the highest cell survival rate at a concentration of 100 ng/ml; The survival rate of the four kinds of cells showed a tendency : survival of cells increased at low concentration of Netrin-1 and survival of cells decreased at high concentration of Netrin-1. The results of Western blot showed that Netrin-1 activated the phosphorylation level of key molecules such as FAK,Erk1/2,PI3K,Akt signaling pathway (P<0.05). CONCLUSION: There is abnormal expression of Netrin-1 in serum of children with ALL. Netrin-1 may affect the occurrence and development of ALL by increasing the proliferation and invasiveness of leukemia cells, and may become a risk factor of ALL or a potential target in biotherapy.

[E-cadherin Expression in Children with Acute Leukemia and Its Clinical Significance].

OBJECTIVE: To investigate the correlation of E-cadherin expression level with the clinical characterastics in children with acute leukemia (AL), and to explore the possible regulatory mechanism. METHODS: Real-time quantitative RT-PCR was applied to detect the expression level of E-cadherin in bone marrow samples from 135 child patients diagnosed as AL, and its relevance with clinical indicators was statistically analyzed. The expression levels of E-cadherin, ß-catenin, and Akt/p-Akt were detected by using Western blot. The bone marrow samples from 22 children with non-malignant hematological diseases were used as controls. RESULTS: The expression level of E-cadherin significantly decreased in newly diagnosed patients with all 3 types of AL as compared with bone marrow samples from control group (P<0.01). In B-ALL group, compared with standard risk group, E-cadherin expression level significantly decreased in intermediate risk group (P<0.05). Moreover,the expression level of E-cadherin mRNA was also reduced in splenomegaly group (P<0.01). However, the correlation of E-cadherin level with clinical characteristics was not found in T-ALL and AML (P>0.05). The expression level of E-cadherin in the patients from Common-B-ALL group was higher than B-ALL patients with other immunophenotypes (P<0.01), while no significant difference was found among patients grouped by FAB classification. By the correlation analysis of measured data, lower E-cadherin expression level was found to be related with high WBC count and serum lactic dehydrogenase level (LDH) (r=-0.419, r=-0.269), but with low blood platelet count in B-ALL (r=0.335). In T-ALL, expression of E-cadherin was found to be negatively correlated with LDH and percentage of immature cells in the bone marrow (r=-0.567, r=-0.557). In addition, the lower expression of E-cadherin was also found to be related with WBC count and percentage of immature cells in the bone marrow in newly diagnosed AML patients (r=-0.368, r=-0.391). Compared with control group, the expression of E-cadherin was down-regulated significantly (P<0.01), while ß-catenin, Akt significantly was up-regulated in 3 types of AL patients (P<0.01). The expression of p-Akt and p-Akt/Akt was up-regulated significantly in T-ALL (P<0.01). CONCLUSION: Lower expression of E-cadherin is related factor of unfavourable prognosis in children with acute leukemia. The expression deficiency or down-regulation of E-cadherin may activate Wnt/ß-catenin and PI3K/ Akt signaling pathways to promote the genesis and progress of haematological malignancies, thus resulting in a series of malignant biological behaviors in cells. E-cadherin may be a new prognostic indicator for pediatric acute leukemia, thus to guide individualized hemotherapy.

[Expression of ß-integrin family members in children with T-cell acute lymphoblastic leukemia].

OBJECTIVE: To study the expression of ß-integrin family members in children with T-cell acute lymphoblastic leukemia (T-ALL) and their significance. METHODS: Quantitative real-time PCR analyses were performed to assess the expression levels of ß-integrin family members in bone marrow samples from 22 children with newly-diagnosed T-ALL and 21 controls (16 children with non-malignant hematologic disease and 5 healthy donors with bone marrow transplantation). Jurkat cells were treated with integrin inhibitor arginine-glycine-aspartate (Arg-Gly-Asp, RGD) peptide. The cell viability and apoptosis rate were determined by CCK8 assay and flow cytometry respectively. RESULTS: The mRNA levels of integrins ß2, ß3, and ß5 were significantly lower in children with T-ALL than in controls (P<0.05). In T-ALL patients, high integrin ß3 expression was associated with lower white blood cell counts (<100×109/L), minimal residual disease (MRD) positivity, and day 33 bone marrow negative remission (P<0.05). In T-ALL patients, higher integrin ß5 expression was associated with relapse of T-ALL (P<0.05). Based on survival curve analysis, higher integrin ß3 expression was related to lower event-free survival and overall survival rates. RGD peptide treatment inhibited the proliferation of Jurkat cells and increased their apoptosis rate (P<0.05). CONCLUSIONS: ß-Integrin may play a role in the occurrence and development of T-ALL by affecting cell proliferation and apoptosis. The expression of integrin ß5 is closely related to the risk of relapse of T-ALL. The expression of integrin ß3 is closely related the treatment response and prognosis of T-ALL.

[PRPS1 Expression in Children with Acute Leukemia and Its Clinical Significance].

OBJECTIVE: To investigate the correlation between the expression level of PRPS1 and the clinical characteristics in children with acute leukemia(AL). METHODS: Real-time quantitative RT-PCR and Western blot were used to detect the level of PRPS1 mRNA and protein expression in bone marrow samples from 176 patients diagnosed as AL (126 cases were newly diagnosed and 50 cases in complete remission), and its relevance with clinical indicators was statistically analyzed. The bone marrow samples from 21 children with non-malignant hematological disease were used as controls. RESULTS: (1)In B-ALL group, the level of PRPS1 mRNA in newly diagnosed patients were significantly higher than that in control and than that in complete remission patients (both P<0.0001). In T-ALL and AML group, differences was only observed between newly diagnosed patients and complete remission patients(both P<0.0001); (2)In B-ALL group, the expression level of PRPS1 increase with along risk enhancement (P<0.01), while no significant difference was observed in T-ALL (P>0.05). In AML patients, expression difference was shown between low risk group and high risk group(P<0.05); (3)High PRPS1 mRNA expression level were associated with high WBC counts and MRD positive in B-ALL patients (P=0.020, P=0.026, respectively); (4)Expression of NT5C2, an essential gene for relapse and drug resistance, was found to be positively correlated with PRPS1 expression in AL samples(P<0.05). CONCLUSION: High expression of PRPS1 is relevant factor of unfavourable prognosis in B-ALL children, which suggest PRPS1 may be a new indicator for prognosis of pediatric B-ALL and an index to guide individualized chemotherapy.