Silence mechanism of WT1 gene in leukemic cell line U937 / 中国实验血液学杂志

This study was aimed to investigate the methylation status of WT1 gene in leukemia cell lines and its relation with expression of WT1 gene. The WT1 gene was silenced by DNA methylation or histone deacetylation, and the expression of WT1 gene was induced by using HDAC inhibitor and/or demethylation agent of DNA. Some leukemia cell lines (U937, HL-60, K562, KG1) were detected by RT-PCR, MS-PCR, restriction analysis, and DNA sequencing. U937 leukemic cells without WT1 mRNA expression were incubated with HDAC inhibitor Trichostatin A (TSA) and/or demethylation agent decitabine. The results showed that the U937 cells did not express WT1 gene, but HL-60, K562 and KG1 cells highly expressed WT1 gene; WT1 gene was unmethylated in HL-60 cells, but methylated in K562 and U937 cells. WT1 expression could be reactivated by co-incubation with TSA and decitabine, but not was observed by using single drug. It is concluded that WT1 promoter is methylated in some leukemia cells, however, the methylation can not affect its expression. DNA methylation and deacetylation of histones are synergistic to inhibit the expression of WT1 in leukemic U937 cells, the combination of TSA with decitabine can induce expression of WT1 gene.

Study on the involvement of ZO-1 gene in leukemogenesis / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore ZO-1 gene expression and methylation in leukemia cells and the involvement of ZO-1 gene in leukemogenesis.</p><p><b>METHODS</b>Restriction landmark genomic scanning (RLGS) was used to identify new leukemia related gene, and methylation specific PCR (MSP) for ZO-1 methylation status. ZO-1 specific siRNA was designed and prepared by in vitro transcription and transfected into K562 cells, the transfected cells were cultured for 48 hours before harvesting. The effect of ZO-1 siRNA was monitored by Northern blot. Cellular proliferation capacity was assayed by CCK-8, cell apoptosis by Annexin V-fluorescence in isothiocyanate (FITC) assay, and cell cycle by phosphatidylinositol (PI).</p><p><b>RESULTS</b>The intensified spots in RLGS gel were subjected to bioinformatics analysis and one of the candidate spots was proved to be ZO-1 gene. In fresh leukemia cells, Molt4 cells and HL-60 cells, ZO-1 was hypermethylated, causing it reduced or silenced. ZO-1 gene was highly expressed with no methylation in normal peripheral blood MNC and K562 cells. There was a good correlation between promoter methylation and the gene silence. The silenced gene can be re-activated by demethylation treatment with 5-AZA-dC in most leukemia cell lines. RNA interference for ZO-1 gene in K562 cells did not interfere with cell proliferation, cell cycle and apoptosis.</p><p><b>CONCLUSION</b>ZO-1 gene methylation might be involved in the tumorigenesis of acute leukemia.</p>

Preliminary study on leukemia related gene zo-1 involved in pathogenesis of leukemia / 中国实验血液学杂志

The study was aimed to identify a new leukemia related gene zo-1 from leukemia and to explore its mechanism in leukemia. Methylation specific PCR (MSP) was used for testing gene zo-1 methylation in leukemia cells. The gene zo-1 specific siRNA was designed according to its sequence, and transfected into THP-1 cell, and the cells were cultured for 48 hours before harvesting. The effect of zo-1 siRNA was monitored by RT-PCR. The cellular proliferation activity was assayed by CCK-8, the apoptosis was detected by Annexin-V-fluorescence in isothiocyanate (FITC) assay, and cell cycle was observed by propidium iodide (PI). The results indicated that the gene zo-1 in patients with acute leukemia was hypermethylated, while the gene zo-1 in healthy persons was unmethylated. The THP-1 cells with unmethylation of zo-1 gene promoter overexpressed the gene zo-1, while the Molt4 and HL-60 cells with hypermethylation of gene zo-1 promoter did not express the gene zo-1. The silenced zo-1 gene in Molt4 and HL-60 leukemia cell lines could be reactivated by demethylation treatment with 5-AZA-dC. The oligofectamine-transfected siRNA for zo-1 gene successfully inhibited the expression of gene zo-1 in THP-1 cells, but did not interfere with cell proliferation, cell cycle and apoptosis. It is concluded that gene zo-1 is a leukemia-related gene. Gene zo-1 in acute leukemia was hypermethylated, the methylation status of gene zo-1 regulates the expression of gene zo-1. Lack of gene zo-1 expression in THP-1 cells does not influence the cell proliferation, apoptosis and cell cycle, which suggests that the methylation of gene zo-1 may be involved in the genesis of acute leukemia, its mechanism is worthy to be studied.

Promotive effect of LRP16 gene on proliferation of K562 cells / 中国实验血液学杂志

The study was aimed to investigate the promotive effect of LRP16 gene on K562 cell proliferation. Open reading frame of LRP16 gene was amplified using reverse transcription-polymerase chain reaction (RT-PCR) and ligated to pGEM-T plasmid to construct LRP16 ORF-pGEM-T recombinant vector. Then, LRP16 ORF identified by sequencing was inserted into pcDNA3.1+ plasmid to construct LRP16 ORF-pcDNA3.1+ recombinant expression plasmid which was transfected into K562 cell lines to make overexpression of LRP16 gene in K562 cells. Survival of cells was determined by MTT assay and growth curve of cells was drawn, the cell cycle was detected by flow cytometry. The results showed that LRP16 ORF was successfully amplified, then the LRP16 ORF-pcDNA3.1+ recombinant plasmid was constructed. The K562 cell line with overexpression of LRP16 gene was established. The promotive effect of LRP16 gene overexpression on proliferation of K562 cells was observed and the effect partially related to the enhancement of cells from G0 to S phase induced by LRP16 gene. It is concluded that LRP16 gene overexpression shows a promotive effect on proliferation of K562 cells.

Lrp16 gene expression in leukemia cell lines and bone marrow cells of leukemia patients and its clinical implication / 中国实验血液学杂志

This study was purposed to investigate lrp16 gene expression in leukemia cell lines and bone marrow cells of leukemia patients and explore the relationship between lrp16 gene expression and development of leukemia. Reverse transcriptase-polymerase chain reaction (RT-PCR) was employed to test the lrp16 mRNA expression in 4 leukemia cell lines, including K562 (CML), HL-60 (APL), MOLT4 (ALL) and U937 cell lines, as well as in bone marrow-derived cells from 115 patients with leukemia. The effect of lrp16 gene expression on genesis and progression of leukemia was analyzed according to clinicopathological features. The results indicated that positive expression of lrp16 mRNA was found in all 4 leukemia cell lines. For leukemia patients, the positive expression rate of lrp16 mRNA in all AML patients was 38% (16/42), in which the positive rates in AML patients with complete remission (CR) and AML patients without remission were 13% (4/30) and 100% (12/12) respectively. The positive expression rate of lrp16 mRNA in ALL patients was 38% (10/26), in which the positive rate in ALL patients with CR and ALL patients without remission were 16% (3/18) and 87% (7/8) respectively. The positive expression rate of lrp16 mRNA in CML patients was 36% (9/25), in which the positive rates in CML patients with CR and CML patients without remission were 20% (4/20) and 100% (5/5) respectively. The positive rate of lrp16 mRNA in CLL patients was 31% (7/22), in which the positive rate in CLL patients with CR and CLL patients without remission were 11% (2/17) and 100% (5/5) respectively. There was no difference of lrp16 gene expression between leukemia subtypes, but there was statistical significant difference in lrp16 gene expression between CR patients and non CR patients (p < 0.001). It is concluded that the lrp16 gene is a leukemic oncogene and closely relates to genesis and progression of leukemia, which may be an indicator for evaluating clinical efficacy of leukemia therapy.

GFP used as a reporter system for optimization of K562 cell transfection / 中国实验血液学杂志

This study was aimed to obtain higher efficiency in gene transfection into K562 cells and to study the role of green fluorescence protein (GFP) as a reporter system. Transfection efficiencies with different methods including electroporation and lipofectamine 2000 transfection, were observed and calculated under fluorescent microscopy by using GFP as a reporter system. The results showed that the transfection efficiency with electroporation (10%) was higher than that with lipofectamine 2000 (1%). In conclusion, the electroporation is a more ideal method for introduction of foreign gene into K562 cells. GFP can be used as a reporter system for optimizing transfection of K562 cells.

Bioinformatics scan analysis for predicting drug targeted modulation on ID4 gene expression / 中国实验血液学杂志

Low expression of ID4 gene is tightly related with carcinogenesis and high expression shows a definite anti-leukemia effect, though little expression in some leukemia cells. The main purpose of this preliminary work was to analyze the construction of ID4 gene promoter and to predict the cis elements in the ID4 promoter region by scanning the drug candidate with bioinformatics method. All these work are the primary part for finding effective drugs in the treatment of leukemia via the way of ID4 expression regulation. According to the data in GenBank and Internet platform, the 5'-untranslated sequence just upstream of ID4 ORF was virtually cloned. TESS, Genomatix and GenBank databank were used to analyze the cis elements in this area. RSA was used to find the distribution patterns for all these possible elements. SAGE and GEO datasets were used to find active substances which have the effect on the ID4 expression. The rsults indicated that ID4 had a type II promoter with a typical TATA box-45 bp upstream the transcriptional original site. There were a lot of various cis elements in the 5'-untranslated region upstream, including both positive element candidates such as Sp1, c-Myb, abaA, GR, ER, Zeste and C/EBPalpha and negative element candidates such as CCAAT-binding factor, GCF, WT1-KTS, HiNF-C and EGR2. It is concluded that estrogen, dexamethasone, thyroid hormone and follicle stimulating hormone may participate in the regulation of ID4 gene expression in both positive and negative manners.

LRP15 gene promoter region methylation and its expression in acute leukemia / 中国实验血液学杂志

To investigate the relationship between LRP15 gene promoter region methylation and its gene expression in acute leukemia patients, the status of LRP15 gene promoter region methylation was detected by MS-PCR and the gene expression was detected by RT-PCR in bone marrow samples from leukemia patients. The results indicated that the LRP15 gene expression was 47.6% in complete remission (CR) patients and 16.7% in non-CR patients respectively, while LRP15 gene promoter region methylation was 38.1% in CR group and 72.2% in non-CR group respectively. No relationship was found between LRP15 gene promoter region methylation and its expression (P = 0.0087). It is concluded that the methylation in LRP15 gene promoter region may not be the only reason for LRP15 gene silence.

Methylation pattern of LRP15 gene in leukemia / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the methylation status of LRP15 gene in acute leukemia (AL) patients and its role in the tumorigenesis.</p><p><b>METHODS</b>The methylation of LRP15 promoter and first exon of bone marrow mononuclear cells in 73 patients with AL, 10 with chronic leukemia (CL), 9 with hematological benign diseases, and 20 healthy transplantation donors was analyzed by using methylation specific polymerase chain reaction. The methylation of LRP15 gene promoter and first exon in COS7, K562, and HL60 cell lines was also assayed.</p><p><b>RESULTS</b>No LRP15 gene promoter methylation was detected in COS7 cell line. LRP15 gene promoter was methylated in K562 and HL60 cell lines. No deletion of LRP15 gene was detected in all samples. In nearly all French-American-British leukemia subtypes, we found that frequency of LRP15 methylation in adult patients with AL was 71.23% (52/73). There was no detectable methylation in any of the 20 healthy donors and 8 chronic myeloid leukemia patients. The difference in frequency of LRP15 methylation between AL patients and healthy donors or CL patients (10.00%, 1/10) was significant (P < 0.01). Hypermethylation of LRP15 gene was found in 57.14% (16/28) of newly diagnosed AL patients, 83.33% of relapsed AL patients respectively, which was significantly different (P < 0.05). We also demonstrated LRP15 methylation in 55.56% (5/9) adults with benign hematological diseases.</p><p><b>CONCLUSIONS</b>LRP15 methylation changes are common abnormalities in leukemia. LRP15 is postulated to be a tumor suppressor gene.</p>

Analysis of LRP16 gene promoter activity / 中国实验血液学杂志

The study was aimed to analyze the characteristics of LRP16 gene promoter and its activity in order to explore the possible regulation mechanism of LRP16 gene expression. A 2.6 kb genomic DNA sequence of LRP16 5'-end was obtained from NCBI by BLAST software. The 7 target sequences between 0.2 - 2.6 kb from a healthy blood donor DNA sample were amplified by PCR, then identified by DNA sequencing and semi-nest PCR. The verified sequences were analyzed on-line. The results showed that the 7 target sequences were about 400 bp different from each other. All 7 sequences were the same to these GenBank described. At last, all 7 promoter sequences were ligated with luciferase vector, and then the luciferase activity was analyzed in HeLa cells. A known gene promoter sequence can be freely obtained from NCBI database. It is concluded that LRP16 promoter is a standard type II promoter and its activity is strongest in the region from -200 to -600 bp.

Id4 gene methylation for detection of minimal residual disease in acute leukemia / 中华血液学杂志

<p><b>OBJECTIVE</b>To evaluate the possibility of Id4 gene promoter methylation as a biomarker for minimal residual disease (MRD) detection in acute leukemia.</p><p><b>METHODS</b>Methylation specific-PCR technique was used to detect Id4 gene methylation in samples with different percentages of leukemia cells from leukemia cell line and bone marrows from leukemia patients in complete remission (CR).</p><p><b>RESULTS</b>Id4 gene methylation could be detected in samples containing 1% or lower leukemia cells. Frequency of Id4 gene methylation in acute lymphoblastic leukemia (ALL) patients in CR was 64.3% being higher than that in acute myeloid leukemia (AML) patients in CR. In 14 ALL patients with Id4 gene methylation, 8 relapsed in 12 months, while only one relapsed in 9 patients without Id4 gene methylation. In 8 AML patients with Id4 gene methylation, 5 relapsed in 12 months, while two relapsed in 20 AML patients with Id4 gene methylation.</p><p><b>CONCLUSION</b>Id4 gene promoter methylation is a candidate of biomarker for MRD detection in acute leukemias.</p>

Analysis of the methylation in the promoter of LRP15 gene and its expression / 中国实验血液学杂志

To study the methylation in the promoter of LRP15 gene and its relationship with gene expression and to explore the possible mechanism of regulating LRP15 gene methylation, the methylation in the promoter of LRP15 gene in K562 cell line was detected by MS-PCR. Then K562 was exposed to 5-aza-2'-deoxycytidine (CdR) and trichostatin (TSA), to determine whether the silencing of LRP15 gene by de novo methylation could be reversed. As a result, it was confirmed by MS-PCR that the promoter of LRP15 was hypermathylated in K562 cell line, and lost its transcription activity. After CdR, with or without TSA, the silencing of LRP15 gene by de novo methylation can be reversed. Observation demonstrated that the expression of LRP15 was controlled by methylation in its promoter in K562. It is suggested that methyltransferase inhibitor and deacetylase inhibitor may be effective agents in leukemia therapy.

Effect of inhibitors for demethylation and histone deacetylase on proliferation of cell line K562 and expression of tumor related genes / 中国实验血液学杂志

In order to observe the effect of inhibitors for demethylation and histone deacetylase on the growth of leukemia cell line K562 and the expressin of tumor related genes, the K562 cells were treated with 5-aza-2' deoxycytidine (DAC) and trichostatin A (TSA) in co-culture; the growth curves were observed; the cell cycle was detected by flow cytometry (FCM); the gene expression pattern before and after drug treatment was measured with Atlas7742-1 microarray. The results showed that the combination treatment of DAC and TSA inhibited the proliferation of K562 cells, the growth of most cells were stopped in G(1)/S phases after drug treatment, the gene expression after treatment was more than before, and a few gene expression were down-regulated. In conclusion, combination treatment of DAC and TSA had an inhibitive effect on the leukemia cell line K562, combination of DAC and TSA with microarray could be used for screening candidate genes inhibiting leukemia cells.

The study on methylation of gene IGSF4 promoter in acute leukemia cells / 中国实验血液学杂志

To study whether gene IGSF4 was inactived by methylation in leukocytic cells, expression of IGSF4 was examined before and after treatment with demethylating agent in U937, Molt4 and HL-60 leukemia cell lines by means of RT-PCR. The methylation of promoter in U937, Molt4 and HL-60 cells as well as 21 acute leukemia patients was analyzed by MS-PCR. The results showed that methylation of IGSF4 promoter was inactived and could be reversed by treatment with a demethylating agent in U937, Molt4 and HL-60 cell. IGSF4 promoter methylation was detected in 57.1% of acute leukemia patients. There is no difference in incidence of IGSF4 promoter methylation between acute myelocytic leukemia and acute lymphocytic leukemia. In conclusion, IGSF4 is frequently inactived in acute leukemia and is a good candidate for the leukemia suppressor gene. As a normal suppressor gene, it may play an important role in inhibiting the development of leukemia, and the methylation of gene IGSF4 may be a good index in monitoring relapse of leukemia.

Middle-high dose of cyclophosphamide or conventional routine chemotherapy with increased dose of cyclophosphamide combined with G-CSF for mobilizing peripheral blood progenitor cells in patients with tumor / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the clinical value of glycosylated G-CSF combined with middle-high dose cyclophosphamide (Cy) or conventional chemotherapy with increased dose of Cy for mobilizing peripheral blood progenitor cells in patients with tumor.</p><p><b>METHODS</b>Thirty patients from four hospitals in Beijing region were enrolled in this clinical study. Diagnoses of the patients were non-Hodgkin' lymphoma (n = 21), Hodgkin disease (n = 1), breast cancer (n = 7) and ovary cancer (n = 1). Autologous peripheral blood progenitor cells (APBPC) were mobilized by middle-high dose Cy or conventional chemotherapy with increased dose of Cy combined with G-CSF. G-CSF was given subcutaneously from the nadir of the white blood cell (WBC) count to the end of PBPC collection. The dosage of G-CSF was 250 microg/d in 29 patients and 500 microg/d in 1 patient. When WBC count was > 5 x 10(9)/L, APBPC were harvested with CS 3000 plus/COBE Spectra.</p><p><b>RESULTS</b>The average dosage of Cy was 3.95 g (2.3 g/m(2)). The doses of G-CSF were 3.1 approximately 6.4 microg x kg(-1) x d(-1). Thirteen patients (43%) were collected twice, 14 patients (47%) three times and 3 patients (10%) four times. All of the patients could tolerate the treatment regimens. Seven patients had bone pain after G-CSF injection and one was severe, one patient had headache and one had nausea and vomiting.</p><p><b>CONCLUSION</b>250 microg glycosylated G-CSF combined with middle-high Cy or conventional chemotherapy with increased dose of Cy combined G-CSF is an optimal method for APBPC mobilization in tumor patients.</p>

Analysis of LRP15 Gene Expression Pattern and Its Expression in Leukemia Cells / 中国实验血液学杂志

To explore the possible function of LRP15 gene in carcinogenesis and its significance in the classification and prognosis of leukemia, the expression pattern of LRP15 in normal tissues, tumor tissues and cell lines was detected with SAGE and gene expression database provided by NCBI and NCI respectively. RT-PCR was used to detect the expression of LRP15 in leukemia patients. The results showed that LRP15 was expressed in different tissues and tumor cell lines, the positive rate of LRP15 in immature blood cells was higher than that of mature blood cells and the positive rate of M(1), M(2) and M(3) was higher than that of other AML subtypes (P < 0.01), the expression of LRP15 in refractory leukemia was higher than that of de novo leukemia. The results suggest that LRP15 may play an important role in carcinogenesis, AML classification and acute leukemia prognosis.

Comparison of curative effect of autologous peripheral blood stem cell transplantation versus bone marrow transplantation for acute leukemia / 中国实验血液学杂志

To compare the clinical outcome of autologous peripheral blood stem cell transplantation (APBSCT) and autologous bone marrow transplantation (ABMT) in treatment of patients with acute leukemia in first remission, 41 patients received APBSCT, 17 patients received unpurged ABMT and 30 patients received purged ABMT. The results showed that hematopoietic recovery was significantly earlier after APBSCT than that after purged or unpurged ABMT. The 3-year disease-free survival (DFS), relapse rate (RR) and transplant-related mortality (TRM) for all patients of 3 groups were 51.7%, 41.7% and 6.8%, respectively. DFS and RR were significantly influenced by disease types (ALL or AML) and intervals between diagnosis and CR(1) or CR(1) and transplant. The main causes of transplant-related death were infection and hemorrhage. After APBSCT, DFS, RR and TRM were 48.4%, 43.9% and 4.9%, respectively, and did not differ significantly from those found in unpurged ABMT (47.1%, 45.6% and 11.8%) or purged ABMT (66.5%, 29.6% and 6.7%). It is concluded that the clinical outcome of APBSCT is similar to unpurged or purged ABMT but APBSCT allows faster recovery of hematopoiesis and needs less transfusion support.

Study on DNA methylation status of WT1 gene promoter in leukemia cell / 中华血液学杂志

<p><b>OBJECTIVE</b>To analyse the WT1 expression and its DNA methylation status of its promoter domain.</p><p><b>METHOD</b>The expression of WT1 gene and its DNA methylation status were assayed in leukemia cell lines and normal peripheral blood mononuclear cells (PBMNC) by RT-PCR and MS-PCR.</p><p><b>RESULTS</b>WT1 was overexpressed in HL60, K562 and KG1 leukemia cell lines, but not in U937 and PBMNC. Methylation of WT1 promoter was not observed in HL60 cells.</p><p><b>CONCLUSION</b>DNA methylation of WT1 gene promotor did not inhibit its expression. Other mechanisms may appear to regulate the WT1 expression.</p>

The effect of separating red blood cells from bone marrow graft in vitro by methylcellulose / 中国实验血液学杂志

It has need to separate red blood cells (RBC) from marrow graft in ABO group unmatched BMT and auto-BMT with purging tumor cells, the separating effect of methylcellulose was observed. The mixture of 0.5% methylcellulose and bone marrow was laid up in an open transfusion system, and then sedimentation of RBC was performed in the transfusion tube. The separating results of 18 marrow grafts showed that the recovery rates of mononuclear cells and CD34(+) cells were (83.8 +/- 55.2)% and (90.3 +/- 7.2)%, respectively. RBC residual rate was (4.3 +/- 1.5)%. The yield of CFU-GM was (60.8 +/- 22.4)/2 x 10(5) MNC, and there was no difference to [(69.8 +/- 23.4)/2 x 10(5) MNC] yielded from same marrow samples, separated by Ficoll-Hypaque separation. It is concluded that this method could be used for bone marrow transplantation.

The expression of Fas, FasL and Bcl-2 on RMA cells during the process of apoptosis induced by chemotherapeutic drugs / 中国实验血液学杂志

The objective of the study is to explore the effect of Fas, FasL and Bcl-2 on the process of apoptosis induced by chemotherapeutic drugs through detecting the expression of Fas, FasL and Bcl-2 on murine lymphoma cell line RMA. Dexamethasone(DEX), etoposide (VP-16), arsenic trioxide As(2)O(3) and all trans-retinoic-acid (ATRA) were added to the RMA cells as well as to the cells preincubated with interleukin-2 (IL-2), interleukin-6 (IL-6) or granulocyte-macrophage colony-stimulating factor (GM-CSF), respectively. The effect on apoptosis was observed and the expression of Fas and FasL mRNA as well as the expression of Fas and Bcl-2 antigen were measured. DEX and VP-16 could promote apoptosis of RMA cells while upregulating the expression of Fas and FasL without affecting the expression of Bcl-2. ATRA downregulated the expression of Bcl-2 without any change of Fas and FasL, and no apoptosis of RMA cells induced by ATRA was observed. Although As(2)O(3) induced apoptosis of RMA cells, it did not affect the expression of Fas, FasL and Bcl-2, which suggested that different drugs induce apoptosis of the same kind of cells by different signal transduction system and apoptosis induced by Fas system needed the coexistence of Fas and FasL. Although IL-2, IL-6 and GM-CSF upregulated the expression of Fas protein when adding to RMA cells separately, none of them induced apoptosis. Apoptosis could be induced by combination of IL-2 and IL-6 along with the upregulation of Fas and FasL. The cytokines facilitated the apoptotic action of chemotherapeutic drugs, the drug concentration for inducing apoptosis decreased and the time period of starting apoptosis shortened. Apoptosis could be observed without the expression of FasL when anti-Fas-antibody was added to RMA cells. The results demonstrated that there was synergistic effect of chemotherapeutic drugs and some cytokines for induction of apoptosis. Fas-FasL system participated in the apoptosis induced by DEX and VP-16; different drugs induce apoptosis by different pathway of signal transduction.