Acetylation of K188 and K192 inhibits the DNA-binding ability of NarL to regulate Salmonella virulence.

Salmonella infection significantly increases nitrate levels in the intestine, immune cells, and immune organs of the host, and it can exploit nitrate as an electron acceptor to enhance its growth. In the presence of nitrate or nitrite, NarL, a regulatory protein of the Nar two-component system, is activated and regulates a number of genes involved in nitrate metabolism. However, research on NarL at the post-translational level is limited. In this study, we demonstrate that the DNA-binding sites K188 and 192 of NarL can be acetylated by bacterial metabolite acetyl phosphate and that the degree of acetylation has a considerable influence on the regulatory function of NarL. Specifically, acetylation of NarL negatively regulates the transcription of narG, narK, and napF, which affects the utilization of nitrate in Salmonella. Besides, both cell and mouse models show that acetylated K188 and K192 result in attenuated replication in RAW 264.7 cells, as well as impaired virulence in mouse model. Together, this research identifies a novel NarL acetylation mechanism that regulates Salmonella virulence, providing a new insight and target for salmonellosis treatment.IMPORTANCESalmonella is an important intracellular pathogen that can cause limited gastroenteritis and self-limiting gastroenteritis in immunocompetent humans. Nitrate, the highest oxidation state form of nitrogen, is critical in the formation of systemic infection in Salmonella. It functions as a signaling molecule that influences Salmonella chemotaxis, in addition to acting as a reduced external electron acceptor for Salmonella anaerobic respiration. NarL is an essential regulatory protein involved in nitrate metabolism in Salmonella, and comprehending its regulatory mechanism is necessary. Previous research has linked NarL phosphorylation to the formation of its dimer, which is required for NarL to perform its regulatory functions. Our research demonstrated that acetylation also affects the regulatory function of NarL. We found that acetylation affects Salmonella pathogenicity by weakening the ability of NarL to bind to the target sequence, further refining the mechanism of the anaerobic nitrate respiration pathway.

Efficient biodegradation of di-(2-ethylhexyl) phthalate by a novel strain Nocardia asteroides LMB-7 isolated from electronic waste soil.

The di-2-ethylhexyl phthalate (DEHP) degrading strain LMB-7 was isolated from electronic waste soil. According to its biophysical/biochemical characteristics and 16S rRNA gene analysis, the strain was identified as Nocardia asteroides. Optimal pH and temperature for DEHP degradation were 8.0 and 30 °C, respectively, and DEHP removal reached 97.11% after cultivation for 24 h at an initial concentration of 400 mg/L. As degradation intermediates, di-butyl phthalates, mono-2-ethylhexyl phthalate and 2-ethylhexanol could be identified, and it could be confirmed that DEHP was completely degraded by strain LMB-7. To our knowledge, this is a new report of DEHP degradation by a strain of Nocardia asteroides, at rates higher than those reported to date. This finding provides a new way for DEHP elimination from environment.

Acetylation of NarL K188 and K192 is involved in regulating Escherichia coli anaerobic nitrate respiration.

As a facultative anaerobe, Escherichia coli can activate various respiratory chains during anaerobic growth, among which the mode of anaerobic respiration with nitrate allows good energy conservation. NarL is one of the regulatory proteins in the Nar two-component system that regulates anaerobic respiration in E. coli. Previous studies have shown that NarL activates downstream gene regulation through phosphorylation. However, there are few studies on other protein translational modifications that influence the regulatory function of NarL. Herein, we demonstrate that acetylation modification exists on K188 and K192, the two lysine residues involved in contacting to DNA, and the degree of acetylation has significant effects on DNA-binding abilities, thus affecting the anaerobic growth of E. coli. In addition, NarL is mainly regulated by acetyl phosphate, but not by peptidyl-lysine N-acetyltransferase. These results indicate that non-enzymatic acetylation of NarL by AcP is one of the important mechanisms for the nitrate anaerobic respiratory pathway in response to environmental changes, which extends the idea of the mechanism underlying the response of intestinal flora to changes in the intestinal environment. KEY POINTS: • Acetylation was found in NarL, which was mainly mediated by AcP. • Non-enzymatic acetylation at K188 and K192 affects NarL binding ability. • Acetylation of NarL K188 and K192 regulates anaerobic nitrate growth of E. coli.

[Bioavailability Characteristics of Chromophoric Dissolved Organic Matter in Lake Gaoyou, Lake Nansi, and Lake Dongping Under Different Hydrological Scenarios].

The bio-lability of chromophoric dissolved organic matter (CDOM) directly reflects its biodegradability potential, and also affects the migration and conversion of pollutants and impacts water quality. This study combines excitation-emission matrices and parallel factor analysis (EEMs-PARAFAC) with laboratory 28 days of bio-incubation experiments, and analyzed the bioavailability characteristics of CDOM samples collected from Lake Gaoyou, Lake Nansi and Lake Dongping in flood season and dry season. Our results showed that:① four fluorescent components were obtained using EEMs-PARAFAC, including a microbial humic-like C1, a terrestrial humic-like C4, a tryptophan-like C2, and a tyrosine-like C3. ② The differences of CDOM absorption pre-and post-incubation, i.e. Δa(254) of the three lakes were positive in the three lakes in the flood season, while partially negative in the dry season, indicating a quite different response of CDOM bioavailability to hydrological seasons. ③ Under different hydrological scenarios, the two humic-like components C1 and C4 increased post-bio-incubation compared with that pre-incubation for the samples collected from Lake Nansi and Lake Dongping, and the two protein-like components in Lake Nansi in both the flood and dry seasons and in Lake Dongping in the flood season (t-test, P<0.001, P=0.005) were lower in the post-than those pre-incubation. In Lake Gaoyou, C1-C3 post-incubation were significantly lower than pre-incubation (t-test, P=0.008, P=0.005). In the dry season, in comparison, C1-C4 except for C2 increased post-incubation than pre-incubation for Lake Gaoyou. This indicated that the protein-like components are unstable and more easily uptaken by microorganisms and may be potentially converted into more stable humic-like components. HIX and IC:IT of the three lakes increased post-incubation while the spectral slope S275-295 decreased, which further confirmed the aforementioned conclusion. ④ During both the flood and dry seasons, the bioavailability of the protein-like components C2-C3 and the fluorescence intensity of C1 and C4 in the inflowing river mouths of the three lakes were higher than in the remaining lake regions. It is therefore necessary to strengthen the water quality management in the inflowing river mouths of the three lakes to maintain the water quality of the lakes.

[Response of Chromophoric Dissolved Organic Matter Dynamics to Different Hydrological Scenarios in the Two Largest Freshwater Lakes Connected to the Yangtze River].

Poyang Lake and Dongting Lake are the two largest freshwater lakes in China connected to the Yangtze River. Changes in the water quality of the two lakes are critical to the water security of the residents surrounding the lakes. Analyses of the optical properties, including chromophoric dissolved organic matter (CDOM) absorption and fluorescence spectroscopy coupled by parallel factor analysis (PARAFAC), were carried out to investigate the dynamics of CDOM in the two lakes in different hydrological scenarios. Our results indicated that different hydrological scenarios have more notable effects on the CDOM dynamics in Poyang Lake compared to those in Dongting Lake. In Poyang Lake, the mean CDOM absorption a(254) and dissolved organic carbon (DOC) were higher in the wet season than in the dry-to-wet transition season, and higher still than in the dry season (t-test, P<0.01), and the mean of the CDOM absorption spectral slope S275-295 was higher in the dry season than in the dry-to-wet transition season and higher still than in the wet season (t-test, P<0.01). In Dongting Lake, the mean of a(254) was not significantly different between different hydrological periods, and SUVA254 reached its maximum in the dry-to-wet transition season. Four fluorescent components were identified using parallel factor analysis. The contribution percentage of CDOM protein-like components in the two lakes was higher during the dry season, and the protein-like components and humic-like components contributed roughly the same amount in the dry-to-wet season, whereas the humic-like components accounted for the main proportion in both lakes during the wet season. From the perspective of spatial distribution, the fluorescence intensity of the four components of Poyang Lake was lower in the southern upstream than in the northern downstream lake regions during the dry season, whereas in the wet season a contrast pattern was found, i.e., with high values found in the upstream lake regions. The spatial difference of fluorescence intensity of the four components in the east of Dongting Lake during the dry season was greater than that in the wet season. We found that DOC increased with increasing water level (r2=0.99, P<0.01) in Poyang Lake and tryptophan-like C2 decreased with increasing water level (r2=0.99, P<0.05) in Dongting Lake. Therefore, the water quality of the two lakes should be managed in a targeted manner according to the response characteristics of CDOM in the two lakes under different hydrological scenarios.

[Characterizing Chromophoric Dissolved Organic Matter in Key Lakes in the Middle Reaches of the East Route of the South-North Water Diversion Project].

Lake Hongze and Lake Luoma are two key lakes located in the middle reaches of the east line of the South-to-North Water Diversion Project. We attempted to unravel the sources and optical composition of CDOM for samples collected from these lakes using excitation-emission matrices (EEMs) and parallel factor analysis (PARAFAC). ① Three fluorescent components were obtained using PARAFAC, including a terrestrial humic-like C1, a tryptophan-like C2, and a tyrosine-like C3. The sources and optical composition of CDOM in the two lakes were, to a large extent, affected by upstream inflow. ② Specifically, fluorescence intensity (Fmax) of the three components C1-C3 in the inflowing river mouths of the two lakes was notably higher than in the other lake regions, and Fmax of the three components during the flood season was significantly higher than during the dry season (t-test, P<0.01). During the flood season, the fluorescence intensity of the terrestrial humic-like component was the highest. This indicates that the source and composition of CDOM in the two lakes are greatly affected by the inflow from the upstream water system, and that the hydrological processes control the abundance and sources of CDOM, especially the terrestrial humic-like C1.③ Significant positive relationships were found between the terrestrial humic-like C1 and the DOC concentrations and CDOM absorption a(254) (r2=0.60, P<0.01; r2=0.88, P<0.01), and the correlation was higher than the other two components. This indicated that the terrestrial humic-like component was the main source of CDOM. In addition, the terrestrial humic-like C1 had a significant positive correlation with SUVA, S275-295, and the integration ratio of the fluorescence peak C to peak T (IC:IT) (r2=0.49, P<0.01; r2=0.61, P<0.01; r2=0.93, P<0.01). It is further revealed that the source and composition of CDOM in the two lakes are greatly affected by land sources. This study reveals the response of CDOM source and composition in Lake Hongze and Lake Luoma to different hydrological scenarios and water transfer processes. Based on these results, the water quality management of the rivers entering the lake should be strengthened during the flood season.

A Retrospective Analysis of Intracranial Hemorrhage in Children with Hemophilia A.

To investigate the incidence, risk factors, clinical manifestations and prognosis of intracranial hemorrhage (ICH) in children with hemophilia A in a center of China, we conducted a retrospective analysis of 126 children with hemophilia A at our hospital in recent 4 years. Thirty-six children with hemophilia A (including 19 severe cases, and 17 moderate cases complicated with joint diseases) received low dose factor VIII (FVIII) prophylaxis, and none of them had ICH. However, 13 cases of hemophilia A not given prophylaxis were complicated with ICH (12 severe cases, and 1 moderate case) and demonstrated an incidence of 10.3% (13/126) in all patients, and 28.6% (12/42) in severe cases. Of the 13 cases, 9 severe ICH cases had a definite history of head injury, accounting for 69.2%. Headache was common in children >3 years, but somnolence, irritability, gaze or convulsions in children <3 years. The most common findings of cranial CT scan included intracranial hematoma (9/13), and less commonly observed were subependymal hemorrhage and intraventricular hemorrhage. After administration of FVIII, all patients survived. Hematoma of 6 cases was observed during CT reexamination after 1-3 months. During the follow-up period, only one case had slight activity limitation on one side of the limb, but steadily recovered. Besides the decreased concentration of FVIII, trauma is the most common risk factor of ICH in children with hemophilia A. The active treatment can improve the prognosis of ICH in children with hemophilia A.

Comparison of diagnosing and staging accuracy of PET (CT) and MIBG on patients with neuroblastoma: Systemic review and meta-analysis.

To perform a systemic review and meta-analysis of the diagnostic accuracy of PET (CT) and metaiodobenzylguanidine (MIBG) for diagnosing neuroblastoma (NB), electronic databases were searched as well as relevant references and conference proceedings. The diagnostic accuracy of MIBG and PET (CT) was calculated for NB, primary NB, and relapse/metastasis of NB based on their sensitivity, specificity, and area under the summary receiver operating characteristic curve (AUSROC) in terms of per-lesion and per-patient data. A total of 40 eligible studies comprising 1134 patients with 939 NB lesions were considered for the meta-analysis. For the staging of NB, the per-lesion AUSROC value of MIBG was lower than that of PET (CT) [0.8064±0.0414 vs. 0.9366±0.0166 (P<0.05)]. The per-patient AUSROC value of MIBG and PET (CT) for the diagnosis of NB was 0.8771±0.0230 and 0.6851±0.2111, respectively. The summary sensitivity for MIBG and PET (CT) was 0.79 and 0.89, respectively. The summary specificity for MIBG and PET (CT) was 0.84 and 0.71, respectively. PET (CT) showed higher per-lesion accuracy than MIBG and might be the preferred modality for the staging of NB. On the other hand, MIBG has a comparable diagnosing performance with PET (CT) in per-patient analysis but shows a better specificity.

Comparison of Diagnosing and Staging Accuracy of PET (CT) and MIBG on Patients with Neuroblastoma: Systemic Review and Meta-analysis / 华中科技大学学报（医学）（英德文版）

To perform a systemic review and meta-analysis of the diagnostic accuracy of PET (CT) and metaiodobenzylguanidine (MIBG) for diagnosing neuroblastoma (NB),electronic databases were searched as well as relevant references and conference proceedings.The diagnostic accuracy of MIBG and PET (CT) was calculated for NB,primary NB,and relapse/metastasis of NB based on their sensitivity,specificity,and area under the summary receiver operating characteristic curve (AUSROC) in terms of per-lesion and per-patient data.A total of 40 eligible studies comprising 1134 patients with 939 NB lesions were considered for the meta-analysis.For the staging of NB,the per-lesion AUSROC value of MIBG was lower than that of PET (CT) [0.8064±0.0414 vs.0.9366±0.0166 (P＜0.05)].The per-patient AUSROC value of MIBG and PET (CT) for the diagnosis of NB was 0.8771±0.0230 and 0.6851±0.2111,respectively.The summary sensitivity for MIBG and PET (CT) was 0.79 and 0.89,respectively.The summary specificity for MIBG and PET (CT) was 0.84 and 0.71,respectively.PET (CT) showed higher per-lesion accuracy than MIBG and might be the preferred modality for the staging of NB.On the other hand,MIBG has a comparable diagnosing performance with PET (CT) in per-patient analysis but shows a better specificity.

[Biological characteristics of T-lineage acute lymphoblastic leukemia in 23 children].

OBJECTIVE: To investigate the biological characteristics of childhood T-lineage acute lymphoblastic leukemia (T-ALL) and their clinical significance. METHODS: Immunophenotyping was performed by three-color flow cytometry analysis using CD45 /SSC gating in 23 children with newly diagnosed T-ALL. Meanwhile cytogenetic analysis was performed. RESULTS: CD3(+) expression of T-lineage antigens was apparently higher than CD7(+) and CD5(+) expression. CD19(+) expression of B-lineage antigens was apparently higher than CD22(+), CD10(+) and CD20(+) expression. Myeloid antigen was expressed in 4 cases (17%). CD34(+) and HLA-DR(+) were observed in 4 cases (17%) and 5 cases (22%), respectively. cCD3(+) and cCD79(+) were expressed in 23 cases (100%) and 22 cases (96%), respectively. The chromosome detection in 8 cases with T-ALL showed hyperdiploid or Ph(+) chromosome (one case each). The fusion gene detection in 5 cases showed MLL rearrangements in two cases and positive SIL/TAL1 fusion gene in one case. CD3 expression was related with the complete remission rate. CONCLUSIONS: Immunophenotyping is an important tool for diagnosis of T-ALL. However, the immunophenotype of T-ALL is heterogeneous. So, immunophenotyping along with cytogenetic and molecular genetic analysis is needed in the treatment and prognosis evaluation of T-ALL.

[Expression of CD147 and matrix metalloproteinase-9 in children with non-Hodgkin's lymphoma and its correlation with prognosis].

OBJECTIVE: To investigate the expression of CD147 and matrix metalloproteinase-9 (MMP-9) in children with non-Hodgkin's lymphoma (NHL) and its correlation with clinical stage, tumor size, bone marrow invasion, immunological typing, serum lactate dehydrogenase (LDH) concentration, and prognosis. METHODS: Specimens excised from NHL patients were prepared. Expression of CD147 and MMP-9 were tested by streptavidin-biotin complex (SABC) immunohistochemistry and its correlation with clinical results were analyzed. RESULTS: The positive rate of CD147 expression was 73% (45/62), 17 cases were (-), 11 cases (+), 34 cases (++) and 21 cases (+++). The positive rate of MMP-9 expression was 81% (50/62), 12 cases were (-), 13 cases (+), 18 cases (++) and 19 cases (+++). The Spearman rank correlation analysis indicated that there was a positive correlation between CD147 and MMP-9 expressions in NHL (r(S) = 0.763, P = 0.034). Expression of CD147 was determined in relation to factors that included clinical bone marrow invasion, tumor size, LDH level as well as the clinical stage; expression of MMP-9 had a positive correlation with bone marrow invasion, tumor size and clinical phases. The 5-year survival rates (5YSR) were 78% (22/28) and 45% (15/34) in the cases whose CD147 expression was (-)-(+) and (++)-(+++), respectively, and 5YSR were 84% (21/25) and 43% (16/37) in the cases whose MMP-9 expression was (-)-(+) and (++)-(+++) respectively, the difference was significant. Cox multivariate analysis showed that both CD147 and MMP-9 were important prognostic factors. CONCLUSION: The increased expression of CD147 and/or MMP-9 correlates with a poor clinical outcome in patients with NHL.

[Effects of SODD and survivin on leukemia cell apoptosis induced by chemotherapeutic drugs].

This study was aimed to investigate the changes of silencer of death domains (SODD), survivin, caspase 3, caspase 8 and caspase 9 in the apoptotic process of human leukemia cells induced by chemotherapeutic drugs in order to explore the molecular mechanism of apoptotic modulatory genes and to search for the new target of chemotherapeutic drugs. After Jurkat cells were induced by chemotherapeutic drugs, the translocated phosphatidylserine was labeled with annexin V/PI, and the apoptosis incidence was measured by FCM; The expression changes of SODD, caspase 3, caspase 8 and caspase 9 were determined by Western blot; the changes of survivin mRNA and protein were determined by RT-PCR and immunohistochemistry SABC method respectively. The results indicated that high expressions of SODD and survivin could inhibit apoptotic signaling pathway; VCR down-regulated the function of SODD protein and effectively induced the apoptosis of Jurkat cells in a time-dependent manner and activates caspase 3 through the death receptor-mediated activation of caspase 8, in which caspase 9 and survivin were not degraded. It is concluded that SODD participates in the apoptotic process induced by VCR which induces the Jurkat cell apoptosis by downregulating expression of SODD protein and priming death receptor pathway. In the apoptotic process, the mitochondrion apoptotic pathway is not trigged.

[Expression of Daxx in children with acute leukemia].

OBJECTIVE: To investigate Daxx expression and its clinical significance in children with acute leukemia. METHODS: The expression of Daxx protein was detected by immunohistochemical assay in 50 children with newly diagnosed acute leukemia (34 cases of acute lymphocytic leukemia and 16 cases of acute non-lymphocytic leukemia). Twenty children with normal bone marrow were used as the control group. RESULTS: Daxx protein was expressed in 38.0% of 50 children with acute leukemia, which was significantly higher than that of the control group (5.0%) (P < 0.05). The children with acute non-lymphocytic leukemia had significantly higher Daxx expression levels (62.5%) than those with acute lymphocytic leukemia (26.5%; P < 0.05) as well as the control group (P < 0.05). There were no significant differences in the Daxx expression between acute lymphocytic leukemia children and the control group. Daxx protein was expressed in 55.6% of high risk group of acute lymphocytic leukemia but it was not expressed in standard risk group of acute lymphocytic leukemia (P < 0.05). CONCLUSIONS: Daxx expression is abnormal in children with acute leukemia and associated with some clinical features of acute leukemia, suggesting that it may play an important role in the genesis and development of acute leukemia.

[Expression of survivin and its location in bone marrow cells of childhood acute leukemia: relationship to therapeutic efficacy].

OBJECTIVE: Survivin, a unique member of the inhibitor of apoptosis protein (IAP) family, plays an important role in regulating both apoptosis and cell division. Overexpression of survivin is associated with increased risk of recurrence and poor outcome in cancer patients. This study aimed to investigate the expression of survivin and its location as well as the relationship between cellular location and expression of survivin and the therapeutic efficacy at the cellular level. METHODS: The expression of survivin protein was detected by immunohistochemical assay in bone marrow cells from 62 children with acute leukemia and 40 hospitalized children who did not have leukemia (Control group), and in a human acute T lymphocytic leukemia cell line (Molt-4 cells) treated in vitro with daunorubicin (DNR). Cell apoptosis was detected using flow cytometry. RESULTS: Survivin protein was expressed in 41.9% of the 62 children with acute leukemia but in only 5.0% of the Control group (chi(2)=16.66; P < 0.01). The expression rate of survivin was 46.2% in cytoplasm and 53.9% in nucleus in the children with acute leukemia (chi(2)0.3077; P> 0.05). However, the remission rate of patients in whom survivin expression was seen in the nucleus was significantly higher than that in patients in whom survivin was expressed in cytoplasm after chemotherapy. The survivin expression in Molt-4 cells decreased remarkably by DNR treatment in a time and dosage-dependent manner. DNR treatment also induced survivin transllocation from cytoplasm to nucleus and cell apoptosis in a time and dosage-dependent manner. CONCLUSIONS: Survivin may play an important role in the development and prognosis of childhood acute leukemia. The different expression pattern of survivin in the cytoplasm and the nucleus may be associated with therapeutic efficacy and prognosis in acute leukemia. DNR may reduce the survivin expression in leukemic cells and induce cell apoptosis.

[FANCA gene mutation analysis in Fanconi anemia patients].

OBJECTIVE: To screen the FANCA gene mutation and explore the FANCA protein function in Fanconi anemia (FA) patients. METHODS: FANCA protein expression and its interaction with FANCF were analyzed using Western blot and immunoprecipitation in 3 cases of FA-A. Genomic DNA was used for MLPA analysis followed by sequencing. RESULTS: FANCA protein was undetectable and FANCA and FANCF protein interaction was impaired in these 3 cases of FA-A. Each case of FA-A contained biallelic pathogenic mutations in FANCA gene. CONCLUSIONS: No functional FANCA protein was found in these 3 cases of FA-A, and intragenic deletion, frame shift and splice site mutation were the major pathogenic mutations found in FANCA gene.

[Regulation of NF-kappaB/P65 by MDM2 in acute lymphoblastic leukemia in childhood].

OBJECTIVE: MDM2 is considered a proto-oncogene due to its ability to inhibit P53 tumor-suppressor function. But, evidence showed that MDM2 might have a P53-independent role in tumorigenesis. MDM2 is over-expressed in human sarcoma and carcinoma. Recent studies showed that MDM2 might act as a transcriptional factor to modulate expressions of other genes involved in cell cycle regulation and transformation. In the present study, the investigators hypothesized that MDM2 directly affected NF-kappaB expression and function in a P53-independent manner. METHODS: MDM2 was transfected to acute lymphoblastic leukemia (ALL) line EU-4 cells lacking P53 expression and expressing very low levels of MDM2. MDM2 and P65 expression in mRNA level and protein level were detected by Western blot and Northern blot after transfection. Since the expression of E-selectin is P65 dependent, E-selectin promoter-CAT construct and P65 and MDM2 expression plasmids were co-transfected to EU-4 cells. CAT activation was determined with ELISA. The effect of adriamycin (ADM) at the concentrations of 15 micro g/ml, 7.5 micro g/ml, 5 micro g/ml and 1 micro g/ml on MDM2-transfected EU-4 cells and the parent cells was detected by MTT assay. RESULTS: The results showed that MDM2 up-regulated P65 expression at both mRNA and protein levels, and MDM2 increased P65-mediated transactivation of E-selectin promoter. Without P65, MDM2 had no effect on the transactivation of E-selectin. Moreover, MDM2 antisense could not change the transactivation of E-selectin. MTT results showed that the survival rate of MDM2 transfected EU-4 cells was higher than that of parental cells. The results suggested that MDM2 transfection increase drug resistance of EU-4 cells to ADM compared with parent cells. CONCLUSION: (1) MDM2 up-regulated transcriptionally P65 expression. (2) MDM2 increased drug resistance of leukemia cells to ADM. (3) MDM2 elevated NF-kappaB activity in a P53-independent manner in childhood lymphoblastic leukemia cell line.