Apoptosis ; drug effects ; Asparaginase ; pharmacology ; HL-60 Cells ; Humans ; K562 Cells ; U937 Cells

OBJECTIVETo analyze the isoforms of IKAROS in the bone marrow samples from children with acute B-lineage lymphoblastic leukemia (B-ALL) and to investigate the relationship between frequency of dominant-negative (DN) IKAROS isoforms and prognosis of B-ALL, and to preliminarily study the relevant mechanism.

METHODSA total of 137 children with newly diagnosed B-ALL, who sequentially entered the Department of Hematology and Oncology, Shanghai Children's Medical Center between January 2005 and September 2010, were included in the study. Nest-PCR, Sanger sequencing, and TA cloning were used to analyze the expression of IKAROS isoforms in these children. The relationship between frequency of DN IKAROS isoforms and prognosis of B-ALL was investigated.

RESULTSOf the 137 children with newly diagnosed B-ALL, 16 had expression of IK6, 14 had expression of IK4, and 2 had expression of IK7. There was significant difference in 2.5-year event-free survival between the cohorts of DN IKAROS and non-DN IKAROS (P=0.01). Analysis of the 10 paired of diagnosis/relapse samples from 10 patients with recurrence showed that 8 of 10 paired diagnosis and relapse samples had inconsistent expression of IKAROS isoforms. The rate of IK6 expression in relapse samples from 21 relapse ALL patients was significantly higher than in the 137 children with newly diagnosed ALL (62% vs 12%, P<0.01).

CONCLUSIONSExpression of DN IKAROS isoforms can be a poor prognostic factor in B-ALL and is closely associated with recurrence of B-ALL.

Adolescent ; Child ; Child, Preschool ; Female ; Humans ; Ikaros Transcription Factor ; genetics ; Infant ; Male ; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma ; metabolism ; mortality ; Prognosis ; Protein Isoforms ; genetics

OBJECTIVETo investigate the effect of vascular endothelial growth factor (VEGF) on the apoptosis of human acute leukemia HL-60 cell line and to analyze the role of the related apoptosis genes, such as Bcl-2 and Mcl-1, in the process of apoptosis of human acute leukemia cells.

METHODSHL-60 cells were treated with different concentrations of VEGF (2 microg/L, 20 microg/L or 100 microg/L ) or 20 mg/L of etoposide (VP16, an apoptosis inducter) alone or VEGF plus VP16. After 18 hrs of treatment, the apoptosis rate of HL-60 cells was detected by single-cell gel electrophoresis and flow cytometry. The expressions of Bcl-2 and Mcl-1 of HL-60 cells were detected by RT-PCR. The Control group did not receive any treatment. Immunocytochemistry was used to detect the VEGF and Mcl-1 protein in bone marrow cells from 8 patients with newly diagnosed or relapsed leukemia, 14 leukemia patients in complete remission, and from 5 normal children.

RESULTSDifferent concentrations of VEGF markedly inhibited the apoptosis of HL-60 cells and decreased the apoptosis induced by VP16 exposure. The Bcl-2 and Mcl-1 mRNA and protein in HL-60 cells treated with VEGF were significantly higher than those in the Control group. The expressions of VEGF and Mcl-1 protein in bone marrow cells of the newly diagnosed and relapsed patients were significantly higher than in patients in complete remission.

CONCLUSIONVEGF can inhibit the apoptosis of HL-60 cells possibly through increasing the expressions of Bcl-2 and Mcl-1 mRNA and protein, which may represent one of the mechanisms responsible for human acute leukemia. The expressions of VEGF, Bcl-2 and Mcl-1 might be used as the markers for the prognostic evaluation of leukemia.

Apoptosis ; drug effects ; Flow Cytometry ; HL-60 Cells ; Humans ; Immunohistochemistry ; Leukemia ; metabolism ; pathology ; Myeloid Cell Leukemia Sequence 1 Protein ; Neoplasm Proteins ; analysis ; genetics ; Proto-Oncogene Proteins c-bcl-2 ; analysis ; genetics ; RNA, Messenger ; analysis ; Reverse Transcriptase Polymerase Chain Reaction ; Vascular Endothelial Growth Factor A ; pharmacology

OBJECTIVEIt has been reported that high-dose cytarabine (HD-AraC) was very effective for childhood hematological malignancies, especially for improving the long-term survival of high-risk acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and T-cell lymphoid malignancies (T-ALL, T-cell non-Hodgkin's lymphoma). This study aimed to evaluate the pharmacokinetics of HD-AraC for childhood hematological malignancies, and the relationship between the expression of the genes coding the key enzymes for Ara-C metabolism with the outcome of the patients.

METHODSThe drug levels of Ara-C in plasma and cerebrospinal fluid were detected with HPLC while HD-AraC was used, the expression of deoxycytidine kinase (dCK) and cytidine deaminase (CDA) mRNA in human leukemia cell lines and the bone marrow cells were investigated in 48 cases of childhood hematological malignancies with RT-PCR methods, and the relationship between the expression of these enzymes mRNA and the outcome of the patients was analyzed.

RESULTS(1) When HD-AraC was used, the plasma levels of Ara-C and Ara-U could be respectively about 50 times and 25 times higher than those obtained when the patients were treated with regular dose of Ara-C treatment, and the level of Ara-C in cerebrospinal fluid could reach about 10% of plasma level of Ara-C. (2) There were significantly different expressions of dCK mRNA in different childhood acute leukemia (AL) patients, which were markedly related to the chemotherapy results. The expression of dCK in ALL was much higher than that in AML and relapsed AL cases. There were no significant differences in expressions of dCK in T-ALL and B lineage ALL. (3) In vitro study found that the expressions of dCK and CDA mRNA did not change in leukemia cell lines incubated at different doses and times of Ara-C.

CONCLUSIONSHD-AraC was a very effective protocol for childhood hematological malignancies for it could significantly elevate the plasma and cerebrospinal fluid drug levels. The expression of dCK may be an important factor in predicting the long-term outcomes of children with hematological malignancies. Good long-term outcomes of the childhood T-ALL could be achieved as the B lineage ALL had been treated with HD-AraC regimen. As the expression levels of dCK were much lower, it may be necessary for the treatment of AML with HD-AraC for consecutive three days.

Antimetabolites, Antineoplastic ; pharmacokinetics ; Child ; Cytarabine ; administration & dosage ; pharmacokinetics ; therapeutic use ; Cytidine Deaminase ; genetics ; Deoxycytidine Kinase ; genetics ; Gene Expression ; Humans ; Leukemia ; drug therapy ; genetics ; metabolism ; Leukemia, Myeloid, Acute ; drug therapy ; genetics ; metabolism ; Lymphoma, Non-Hodgkin ; drug therapy ; genetics ; metabolism ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; drug therapy ; genetics ; metabolism

High expression of cellular asparagine synthetase (AS) is a causative factor for the resistance of leukemic cell to L-asparaginase therapy. This study was aimed to find single nucleotide polymorphism (SNPs) in the promotor region of asparagine synthetase (AS) gene and to determine if these SNPs have influence on the transcriptional activity of AS promotor. The DNA sequences of AS promoter (pAS) from 82 leukemic children and 45 controls were determined to screen for SNPs in this region and the AS mRNA level in these samples was quantified using real-time PCR assay. The results indicated that three SNPs were found in the sequenced pAS fragment. They were -239C/T, -92G/A and -62A/T respectively. The frequency of -92A allele was higher in leukemic samples than that in nonleukemic control (P<0.05). The gene expression level differed among the individuals with genotype of the -92G/A SNP, and the descending order was as follows: GA heterozygote > AA homozygote > GG homozygote. It is concluded that some features in leukemia might associate with SNP on -92A locus, and this SNP in pAS can be one of the factors influencing transcriptional activity of AS gene. The existence of the -92A allele variant contributes to a high expression of AS gene.
Aspartate-Ammonia Ligase ; genetics ; Child ; Female ; Humans ; Leukemia, Myeloid, Acute ; enzymology ; genetics ; Male ; Polymorphism, Single Nucleotide ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; enzymology ; genetics ; Promoter Regions, Genetic ; genetics

OBJECTIVETo study the antileukemic activity of L-asparaginase through determining the changes of 4 kinds of amino acids (Asn, Aspa, Glu and Gln) in cell culture medium.

METHODSFollowing L-Asp treatment with designed concentrations and duration, the IC50 (inhibitory concentration 50%) of 8 kinds of common leukemia cell lines (U937, HL-60, Jurkat, NB4, THP-1, Namalwa, Karpass299, K562) were determined by CCK-8 assay. The changes of the 4 kinds of amino acids mentioned above were detected by high performance liquid chromatography (HPLC).

RESULTSThe asparagines in cell culture medium were rapidly exhausted when treated with 0.01 U/mL L-Asp for 4 hrs or 1 U/mL L-Asp for 5 minutes. There were significant differences in the sensitivities to L-Asp of different leukemia cell lines. The sensitivities to L-Asp of various cell lines were dose-dependent. Low concentration of L-Asp resulted in a low IC50 and the IC50 increased following the L-Asp concentration increased.

CONCLUSIONSDifferent leukemia cell lines have different sensitivities to L-Asp, suggesting that exhaustion of asparagines around leukemia cells could not reflect the treatment efficacy of L-Asp. L-Asp antileukemic activity is dose-dependent, which suggests the importance of high-dose L-Asp on childhood acute lymphoblastic leukemia.

Asparaginase ; pharmacology ; Asparagine ; analysis ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Chromatography, High Pressure Liquid ; Humans ; Leukemia ; drug therapy ; metabolism ; pathology ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; drug therapy

OBJECTIVETo determine whether the high level of asparagine synthetase (AS) expression in childhood acute lymphocytic leukemia (ALL) is associated with an inferior prognosis.

METHODSAS mRNA level in leukemic cells from 53 newly diagnosed ALL children was measured by real time fluorescent quantitative PCR method. Patients were divided into groups according to their relapse risk and outcome, and the AS expression levels in each group were compared. The survival rates in different AS expressing level groups were estimated and compared.

RESULTSThe highest level of AS [median 17.25 (2.48-46. 82)] was observed in children failed remission, intermediate level [14.28 (3.20-54.47)] in relapsed children and the lowest level [5.08 (0.84-54.92)] in children with continuous complete remission (CCR) (P<0.05). The AS mRNA level [14.93 (2.48-54.47)] in children with poor outcome (un-remission and relapsed) was significantly higher than that in children in CCR (P<0.01). The two-year estimated disease free survival was much lower in children with high AS expression (53.8%) than in those with low AS expression (84.6%) (P<0.05).

CONCLUSIONHigh expression of AS is associated with a poor outcome in ALL children.

Adolescent ; Aspartate-Ammonia Ligase ; metabolism ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Male ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; enzymology ; Prognosis

This study was purposed to explore the relationship between asparagine synthetase (AsnS) mRNA expression level and the sensitivity of leukemic cell lines to L-asparaginase. The AsnS mRNA expression level in 8 cell lines (Jurkat, HL-60, U937, NB4, THP-1, Namalwa, Karpas299 and K562) was determined by real-time quantitative PCR (RQ-PCR) based on fluorescence dye Eva Green before and after treatment with L-Asp, and the cell proliferation rates were analyzed by CCK-8 assay. The results showed that there was a significant disparity of AsnS expression level in 8 cell lines, and there were significant increases of AsnS expression level in cells co-cultured with L-Asp (p < 0.05). Of all these eight cell lines, cells sensitive to L-asparaginase had lower AsnS expression level and cells resistant to L-asparaginase had higher AsnS expression. U937 which was the most sensitive to L-asparaginase had the lowest AsnS expression level, while K562 was natural resistant to L-asparaginase and possessed of the highest AsnS level. It is concluded that the AsnS plays a critical role in regulating cellular biological behavior after depletion of asparagine, the AsnS mRNA expression level in cells reflects the sensitivity of cells to L-Asp. The results may imply the possibility for the use of L-asparaginase in leukemia with lower AsnS expression level.
Asparaginase ; metabolism ; pharmacology ; Aspartate-Ammonia Ligase ; metabolism ; Cell Line, Tumor ; Humans ; Leukemia ; enzymology

OBJECTIVETo study the expression of zinc finger protein X-linked (ZFX) in bone marrow mononuclear cells (BMMCs) of children with B lineage acute lymphoblastic leukemia (B-ALL) and its relationship with prognosis.

METHODSThe expression of ZFX in human leukemia cell lines (REH, HL-60, NB(4) and K562) was measured by Western blot. ZFX gene was cloned by PCR from one patient and DNA sequencing technology was used to confirm it. Real-time PCR was used for detecting ZFX mRNA expression in the BMMCs of 82 children with newly-diagnosed B-ALL, 24 children with complete remission (CR) after induction therapy and 64 control children (fracture or congenital heart disease patients). According to the presence of bone marrow or central nervous system relapse during a follow-up of 3 years, the patients were identified as having a good or poor prognosis. Their ZFX mRNA levels in BMMCs at diagnosis were compared.

RESULTSZFX protein was expressed in human leukemia cell lines REH, HL-60, NB(4) and K562. ZFX mRNA expression was significantly higher in the newly-diagnosed ALL group than in the control group (P < 0.01). ZFX mRNA expression in the ALL CR group was significantly reduced compared with the newly-diagnosed ALL group (P < 0.01). Children with a poor prognosis had significantly higher ZFX mRNA levels at diagnosis than those with a good prognosis (P < 0.05).

CONCLUSIONSZFX is over-expressed in children with B-ALL and its levels are higher in those with a poor prognosis than those with a good prognosis, which suggests that ZFX is important in the prognosis evaluation of B-ALL.

Adolescent ; Cell Line, Tumor ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Kruppel-Like Transcription Factors ; analysis ; genetics ; physiology ; Male ; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma ; metabolism ; pathology ; Prognosis ; Real-Time Polymerase Chain Reaction

BACKGROUNDMultidrug resistance to chemotherapeutic agents is an important clinical problem during the treatment of leukemia. The resistance process is multifactorial. To realize the total factors involved in multidrug resistance, we analyzed the differentially expressed proteins of K562 and K562/ADM cells and we investigated one of the up-regulated proteins (CRKL) using siRNA to determine its role in K562/ADM cells.

METHODSAltered protein expressions between K562/S (K562 ADM-sensitive cell line) and K562/ADM (K562 multidrug resistant cell line induced by adriamycin) were identified by 2D-DIGE coupled with mass spectrometry. Meanwhile, we confirmed the differential expression of CRKL and Stathmin in both K562 and K562/ADM cells by Western blot analysis. Furthermore, we used RNA interference to silence the CRKL gene expression.

RESULTSAmong the 9 differentially expressed proteins, 3 were up-regulated in K562/ADM cells, while 6 were down-regulated in the K562/ADM cells compared with its parent cell line. The expression of CRKL was up-regulated significantly in K562/ADM cells, and it can be decreased by recombinant lentivirus. Moreover, the multidrug resistance of K562/ADM cells was efficiently reversed by silence of CRKL gene expression.

CONCLUSIONSThe data provided the differentially expressed proteins in K562 and its resistant cell line and highlights the power of 2D-DIGE for the discovery of resistance markers in cancer. We found CRKL may be a new protein involved in the multidrug resistance of leukaemia cells.

Adaptor Proteins, Signal Transducing ; analysis ; antagonists & inhibitors ; genetics ; Amino Acid Sequence ; Doxorubicin ; pharmacology ; Drug Resistance, Multiple ; Humans ; K562 Cells ; chemistry ; drug effects ; Molecular Sequence Data ; Neoplasm Proteins ; analysis ; Nuclear Proteins ; analysis ; antagonists & inhibitors ; genetics ; Proteomics ; Stathmin ; analysis