Clinicopathological Characteristics and Prognosis Analysis of the Patients with Plasmablastic Lymphoma / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To evaluate the clinicopathological characteristics, treatment and prognosis of the patients with plasmablastic lymphoma(PBL).</p><p><b>METHODS</b>The clinical and pathological data of 21 patients with PBL diagnosed and treated in our center between January 2009 and September 2017 were retrospectively analyzed. The clinical and pathological features, treatment and therapentic outcome were summarized and the high risk factors affecting the prognosis of patients were investigated.</p><p><b>RESULTS</b>The 21 PBL patients included 12 males and 9 females, and their median age was 52 years old. The human immunodeficiency virus (HIV) was negative in all patients. The primary involved sites of 16 patients were extranodal, and the patients staged in III-IV accounted for 81%; 18 patients receved first-line chemotherapy with standard CHOP(E) (cyclophosphamide +epirubicin +vincristine +prednisone±etoposide). After treatment, only 1 patient achieved complete response (CR), and 8 patients achieved partial response (PR). The median overall survival time was 6.3 months. Multivariate analysis showed the America Eastern Cooperative Oncology Group (ECOG) physical score and bone marrow infiltration were significant prognostic factors (P<0.01).</p><p><b>CONCLUSION</b>Plasmablastic lymphoma frequently occurrs in the middle-old aged persons with all HIV negative. Primary extranodal lesions are frequent. Most patients were in advanced stage with poor treatment response. ECOG score≥2 and bone marrow infiltration are independent prognostic factors related with worse prognosis.</p>

Valproic Acid Represses Autophagy and Enhances the Anti-myeloma Activity of DNA-damaging Drugs / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To explore the effect of valproic acid(VPA) on anti-myeloma activity of Doxorubicin(DOX) or Melphalan(MEL) and its related mechanism.</p><p><b>METHODS</b>Human multiple myeloma(MM) cells were treated with VPA of non-toxic dose in absence and presence of DOX or MEL at different concentrations (ie. IC10, IC20, IC40). The cell proliferation was detected by MTT method. Western blot was used to detect the expression levels of autophagy-related proteins (LC3, ATG5, ATG7) and acetylated histone H4K16ac.</p><p><b>RESULTS</b>Cell proliferation inhibition markedly increased in VPA plus DOX or MEL as compared with DOX or MEL alone (P<0.05). Both LC3 and H4K16ac expression levels in co-treatment were between VPA and DOX or MEL treated alone. Importantly, VPA of non-toxic dose not only augmented the anti-myeloma activity of DOX or MEL, but also down-regulated the autophagy-related protein expression and increases H4K16ac protein levels.</p><p><b>CONCLUSION</b>H4K16ac can inhibit the transcription of autophagy-related genes, The VPA enhance the anti-myeloma activity of DNA-damaging drugs, at least in part, via H4K16ac-mediated suppression of cytoprotective autophagy.</p>

Influence of CD117 Expression on Response of Multiple Myeloma Patients to Chemotherapy / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the influence of CD117 expression on response of multiple myeloma patients to chemo-therapy.</p><p><b>METHODS</b>A total of 65 cases of newly diagnosed multiple myeloma in our hospital from 2011 to 2013 were enrolled in this study. Cytogenetic abnormalities and immunophenotype were detected by using fluorescence in situ hybridization and flow cytometry before chemotherapy. The therapeutic efficacy of patients was evaluated after 4 cycles of PAD or TAD regimen.</p><p><b>RESULTS</b>The positive rates of 1q21 amplification, RB1: 13q14 deletion, D13S319: 13q14.3 deletion, IgH: 14q32 rearrangement and p53: 17p13 deletion were 32.2%, 40%, 40%, 20% and 3.1% respectively; the positive rates of CD38, CD138, CD56, CD117, CD20 were respectively 100%, 100%, 60%, 20%, 10.8%; the positive rates of CD19 and CD10 were 4.6% and 4.6% respectively; the positive CD22, CD7, CD5, CD103 did not found in any patients. The therapeutic efficacy of CD117⁻ patients was better than that of CD117⁺ patients (P < 0.05), there was no correlation of the remaining indicators with efficacy; the proportion of CD117⁺ patients with β2-microglobulin ≥ 5.5 mg/L was significantly higher than that of CD117⁻ patients (P < 0.05); the rest of baseline data had no significant difference (P > 0.05).</p><p><b>CONCLUSION</b>CD117 can be used as an indicator for evaluating efficacy of patients with newly diagnosed multiple myeloma.</p>

Inducing effect of chidamide on apoptosis of multiple myeloma cells and its relerance to DNA damage response / 中国实验血液学杂志

<p><b>OBJECTIVE</b>This study was aimed to explore the effect of a novel histone deacetylase inhibitor Chidamide on apoptosis of human multiple myeloma(MM) cells and its relevance to DNA damage response(DDR).</p><p><b>METHODS</b>The cell proliferation was detected by MTT method, apoptosis and cell cycle distribution were analyzed by flow cytometry, the expression levels of targeted proteins were detected by Western blot, the DNA damage response was blocked by ATM kinase inhibitor KU-55933.</p><p><b>RESULTS</b>Chidamide inhibited RPMI 8226 cell proliferation in dose- and time-dependent manner and its IC50 values of 24,48,72 h were 9.6, 6 and 2.8 µmol/L respectively. Chidamide induced cell cycle arrest of RPMI 8226 cells in G0/G1 phase by upregulating the expression of P21. Chidamide triggered caspase-3 dependent apoptosis and upregulated expression of DDR-related proteins including γH2AX, pATM in RPMI 8226 cells. Pretreatment with ATM kinase inhibitor KU-55933 down-regulated expression of DDR related proteins induced by chidamide, thereby inhibiting DNA damage response and finally resulting in suppression of apoptotic cell death.</p><p><b>CONCLUSION</b>Proliferative inhibtion, cell cycle arrest and apoptosis of multiple myeloma cells induced by chidamide involve DDR.</p>

Efficacy comparison between standard and reduced doses of bortezomib combined with adriamycin and dexamethasone in the treatment of patients with multiple myeloma / 中华血液学杂志

<p><b>OBJECTIVE</b>To compare the efficacy and safety of standard or reduced doses of bortezomib combined with adriamycin and dexamethasone (PAD) in patients with multiple myeloma (MM).</p><p><b>METHODS</b>Eighty-two newly diagnosed or refractory/relapsed patients received bortezomib [either 1.2-1.3 mg/m(2) (standard dose) or 1.0-1.1 mg/m(2) (reduced dose) on day 1, 4, 8 and 11], and adriamycin (10 mg/m(2)) plus dexamethasone (40 mg/m(2)) on day 1-4 at 3-week intervals for 1 to 6 courses. The International Myeloma Working Group Criteria were used to evaluate the response. Adverse events were graded according to the National Cancer Institute Common Toxicity Criteria (Version 3.0).</p><p><b>RESULTS</b>Two courses of standard dose of PAD resulted in a similar response rate of partial and very good partial complete remissions (PR) compared with reduced dose (80.0% vs 80.8%, P=0.728). Grade III- Ⅳ neutropenia and thrombocytopenia were higher with standard dose than that with reduced doses of PAD (21.1% vs11.1%, P=0.270; 10.5% vs 6.3%, P=0.619, respectively). Grade III-Ⅳ bortezomib-induced peripheral neuropathy, herpes zoster, fatigue or abdominal distention were significantly higher with standard dose than that with reduced dose of PAD (15.8% vs 1.6%, P=0.037; 26.3% vs 6.3%, P=0.028; 36.8% vs 14.3%, P=0.046; 15.8% vs 1.6%, P=0.037, respectively).</p><p><b>CONCLUSION</b>Reduced dose of PAD appears to result in a similar overall response rate, but a better tolerance and safety compared with standard dose.</p>

Inhibitory effect of 14-3-3ζ on the proliferation of HL-60 cells and HL-60/VCR cells / 中国实验血液学杂志

This study was aimed to investigate the expression and role of 14-3-3ζ in the AML cell lines: sensitive HL-60 and drug-resistant HL-60/VCR cells. Semi-quantitative RT-PCR and Western blot were respectively used to examine the expression of mdr1 mRNA and Pgp in AML cell lines to validate the results of microarray. Western blot was performed to investigate the expression of Pgp, 14-3-3ζ, and anti-apoptosis protein BCL-2, MCL-1 proteins. Immunofluorescence assay was used to detect the subcellular location of 14-3-3ζ protein in HL-60 and HL-60/VCR cells by laser scanning confocal microscopy. Transduction with siRNA was used to silence 14-3-3ζ in AML cell lines. Cell count method and flow cytometry of cell cycle were used to analyze the changes of growth of AML cells. The results found that mdr1 mRNA and Pgp did not expressed in HL-60 cells, but significantly overexpressed in HL-60/VCR cells. Except 14-3-3σ, the expression of other subtypes of 14-3-3 was higher in HL-60/VCR cells than that in HL-60 cells, especially 14-3-3ζ. The higher expression of 14-3-3ζ, BCL-2, MCL-1 protein was observed in HL-60/VCR cells than that in HL-60 cells. These results were same results from gene chip. It was also noticed that 14-3-3ζ was located in the cytoplasma and nuclei of AML cell lines, especially over-expressed in HL-60/VCR cells. Furthermore, suppression of 14-3-3ζ by RNA interference resulted in inhibition of the proliferation of AML cells with decreased protein expression of BCL-2 and MCL-1, especially in HL-60/VCR cells. It is concluded that 14-3-3ζ plays an important role in proliferation of AML cells and associates with BCL-2 and MCL-1 expression. These results suggested that development of therapy targeting 14-3-3ζ may provide novel, effective strategies for refractory and relapsed AML.

Effects of triptolide on bortezomib-induced apoptosis in multiple myeloma cells / 中国实验血液学杂志

This study was purposed to investigate the effect of triptolide on bortezomib-induced apoptosis in multiple myeloma cell line NCI-H929(H929). MTT assay was applied to detect the inhibitory effects of triptolide and bortezomib alone or combined at different concentrations on H929 cells, the cell apoptosis was assayed by flow cytometry with Annexin V-FITC/PI staining. The results showed that both triptolide (10 - 100 ng/ml) and bortezomib (10 - 100 nmol/L) alone or combination inhibited the proliferation of MM cell line H929 in a concentration-dependent manner. The apoptotic rate of H929 cells in group of triptolide combined with bortezomib was much higher than that in groups of single drug or control; moreover, the apoptotic rate of H929 cells treated by non-inhibitory concentration of triptolide (10 ng/ml) combined with bortezomib (40 nmol/L) for 24 h was significantly higher than that by bortezomib alone (P < 0.05). It is concluded that triptolide can significantly enhance the pro-apoptotic activity of bortezomib in MM cells.

PI3-kinase mediates thrombin-induced platelet aggregation through mDia1 pathway / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the expression of mDia1 (mammalian diaphanous 1)in platelet and the role of mDia1 or phosphatidylinositol 3-kinase (PI3K) in the process of thrombin-induced platelet aggregation.</p><p><b>METHODS</b>The extent of platelet aggregation was measured by a platelet aggregation system and the expression of mDia1 and its relation with F-actin in quiescent, spreading or aggregated platelets by Western blot.</p><p><b>RESULTS</b>There was no significant difference in mDia1 expression level between quiescent and activated platelets. mDia1 moved from a Triton-X100-soluble cytosolic fraction to insoluble cytoskeleton fraction after thrombin induced platelets aggregation. Anti-mDia1 antibody could inhibit this aggregation. PI3K inhibitor Wortmannin or Ly294002 inhibited the thrombin induced platelet aggregation and the above mentioned mDia1 translocation.</p><p><b>CONCLUSION</b>PI3-kinase mediates the thrombin-induced platelet aggregation through mDia1 pathway.</p>

Clinical analysis on 28 patients with hemophagocytic lymphohistiocytosis syndrome / 中国实验血液学杂志

In order to profoundly understand the clinical and laboratorial characteristics and inducing factors of hemophagocytic lymphohistiocytosis syndrome (HLH), 28 HLH patients received from 2004 to 2009 years in our hospital were analyzed retrospectively. The results indicated that all of the patients had a history with prolonged fever (more than 1 week), pancytopenia, hepatosplenomegaly, elevated ferritin level, hypofibrinogen, and hemophagocytosis in bone marrow. HLH was the first characteristic sign of malignant lymphoma in 9 patients; 1 patient had a clinical manifestation similar to fulminant hepatic failure; severe psycho-abnormality occurred in 1 HLH patient and pronounced hemophagocytosis were detected in his cerebrospinal fluid; 1 patient was eventually diagnosed as having HLH by the findings in a lymph node biopsy showing obvious hemophagocytosis. Additionally, the analysis of underlying factors in 28 patients with HLH indicated 11 patients with EB virus-associated HLH, 11 with lymphoma-associated HLH, 2 with Leishmania-associated HLH, and 3 with autoimmune disease-associated HLH. It is concluded that HLH disease is characterised with high heterogenicity in both clinical features and inducing factors; in addition, the patients from a pasturing area should be paid attention to parasite infection such as leishmania.

Effects of xbp-1 gene silencing on bortezomib-induced apoptosis in human multiple myeloma cells / 中国实验血液学杂志

This study was purposed to investigate the effect of xbp-1 gene silencing on bortezomib-induced apoptosis in multiple myeloma cell line NCI-H929 (H929). After xbp-1 gene expression was interfered by small hairpin RNA, the cell apoptosis was assayed by flow cytometry with Annexin V-FITC/PI staining, and the expression level of XBP-1 protein was detected by Western blot. The results showed that XBP-1 protein level of H929 cells was inhibited effectively by the PLL3.7 lentiviral vector mediated expression xbp-1 shRNA. The apoptosis rate was significantly higher in xbp-1 shRNA-expressing cells than in untreated control group [(10.13±0.61)% vs (2.5±0.2)%, p<0.05]. After treatment with bortezomib, the apoptosis rate of XBP-1 protein functionally deficient H929 cells was significantly higher than those in vector control group [(45.07±1)% vs (19.53±0.8)%, p<0.05]. It is concluded that xbp-1 gene silencing can significantly enhance the pro-apoptotic activity of bortezomib in multiple myeloma cells.

Bortezomib-induced BiP expression and apoptosis in multiple myeloma cells / 中国实验血液学杂志

This study was aimed to explore the effect of bortezomib on the apoptosis and expression of the molecular chaperone BiP in human multiple myeloma cell line NCI-H929 (H929). After treatment of H929 cells with different concentrations of bortezomib for 24 hours, cell apoptosis was assayed by flow cytometry with Annexin V-FITC/PI staining, and the expression levels of BiP mRNA and protein were detected by RT-PCR and Western blotting analysis. The results showed that bortezomib of different concentrations (20, 40 and 80 nmol/L) induced apoptosis of H929 cells in dose-dependent manner, with apoptotic rates (15.73 +/- 0.67)%, (27.83 +/- 1.26)% and (44.17 +/- 2.25)% respectively, which were significantly higher than that in control (1.21 +/- 0.07%) (p < 0.05). Bortezomib-induced up-regulation of BiP mRNA levels was almost on a parallel with BiP protein when compared with control. Under the similar apoptosis-stimulating conditions with apoptotic rates varying from 40% to 50%, expression levels of BiP mRNA and BiP protein induced by the classical endoplasmic reticulum stressor Brefeldin A (500 ng/ml, 24 h) were almost consistent with those by bortezomib (80 nmol/L, 24 h). It is concluded that bortezomib-induced apoptosis in H929 cells correlates closely with endoplasmic reticulum stress.

PI3-kinase mediates activity of RhoA and interaction of RhoA with mDia1 in thrombin-induced platelet aggregation / 中国实验血液学杂志

The aim of this study was to investigate the role of RhoA/mDia1 pathway in the process of thrombin-induced platelet aggregation and regulatory effect of PI3K inhibitor on this process. The human platelets were isolated from peripheral blood, the activation of RhoA, Rac1 and Cdc42 in the platelet aggregation was detected by GST pull-down assay and immune co-precipitation, the interaction of RhoA, Rac1 and Cdc42 with mDia1 and the formation of complex in the process of platelet aggregation were determined by immune coprecipitation, and the effect of PI3K inhibitor (wortmannin) on above-mentioned process was assayed. The results showed that thrombin elevated the activity of RhoA and the binding capability of RhoA with mDia1 during thrombin-induced platelet aggregation and spreading on Fg coated coverslips. Wortmannin inhibited the rising of RhoA activity and the binding level of RhoA with mDia1 induced by thrombin. Thrombin elevated the activity of Rac1 and Cdc42 during thrombin-induced platelet aggregation, but could not induce binding of Rac1 or Cdc42 with mDia1. Wortmannin could not inhibit the rising of Rac1 and Cdc42 activity induced by thrombin. It is concluded that the PI3-kinase regulates the thrombin-induced actin cytoskeleton reconstitution in platelets by RhoA-mDia1 pathway.

Measurement of serum free light chains and its clinical significance in 20 newly diagnosed patients of multiple myeloma / 中国实验血液学杂志

The objective of this study was to explore the clinical significance of measuring serum free light chains (sFLC) and to compare with serum total light chains (free and binded) in multiple myeloma (MM). sFLC in 20 newly diagnosed MM patients and 20 cases of healthy people as control were measured by immuno-nephelometric assays; the serum light chains and kappa/lambda ratio were measured in all patients, while immunofixation electrophoresis (IFE) tests were carried out at the same time in 18 out of 20 patients. The results showed that the abnormality of serum free light chains and kappa/lambda ratio were found in all of the 20 newly diagnosed MM patients (p < 0.01). The measurement of sFLC showed higher sensitivity than the total serum chains (p < 0.01). It is concluded that the method testing sFLC by immuno-nephelometric assay combined with kappa/lambda ratio is valuable for MM diagnosis, and the measurement of sFLC can be used as one of indicators for MM diagnosis.

CMV pp65 gene modified dendritic cells activate autologous T cells / 中国实验血液学杂志

Cytomegalovirus (CMV) infection is a dangerous complication in patients with chronic graft versus host disease (cGVHD). CMV-specific immunity depends on the activity of T cells. This study was aimed to investigate the effect of CMV pp65 gene modified dendritic cells (DCs) on activation of autologous T cells. Lentivirus system was utilized to introduce the CMV full-length pp65 gene into mouse DCs; CpG-DNA was used to induce mature DCs; flow cytometry and immunofluorescence were used to determine the expression of antigen and IFNgamma in T lymphocytes. The results showed that the DCs were infected with lentivirus at a multiplicity of infection (MOI) of 50 with optimal infectious efficiency of 30%-40%; mature DCs expressing pp65 gene could stimulate autologous naive T cells to express CD69 specifically; mature DCs expressing PP65 could stimulate autologous CD4+ or CD8+ T cells to produce IFNgamma. It is concluded that CMV pp65-modified and CpG-DNA-induced mature DCs can activate CMV-specific T lymphocytes in vitro.

Effect of curcumin on expression of survivin, Bcl-2 and Bax in human multiple myeloma cell line / 中国实验血液学杂志

To explore the mechanisms of suppression growth and induction apoptosis of curcumin on human multiple myeloma cell line RPMI8226, the suppressive effect of curcumin on RPMI8226 was examined by MTT assay; the induction apoptosis and cell cycle arrest of curcumin on RPMI8226 were determined by flow cytometry (FCM); the changes of survivin, Bcl-2, Bax mRNA levels were detected by RT-PCR. The results showed that curcumin obviously suppressed the proliferation of RPMI8226 in both time- and dose-dependent manners, and the IC(50) were 12.15 micromol/L, 4.9 micromol/L for 24 and 48 hours respectively. FCM indicated that the apoptosis ratio rose from 10.6% of untreated cells up to 36.9% of treated cells (p < 0.05), and curcumin arrested cell cycle of RPMI8226 at G(2)/M phase. RT-PCR showed that RPMI8226 cells expressed survivin, Bcl-2 strongly and Bax slightly; while RPMI8226 cells were treated with curcumin 10 micromol/L for 24 hours, the expressions of survivin, Bcl-2 mRNA were apparently down-regulated, and the expression of Bax mRNA was markedly up-regulated. It is concluded that curcumin can suppress the proliferation of human multiple myeloma cell line RPMI8226, and induce their apoptosis. The mechanism of antitumous effect of curcumin may be related to down-regulation of survivin, Bcl-2 mRNA and up-regulation of Bax mRNA.

Rac1 expression and its effects on the cell cycle progression and apoptosis in human acute leukemic cell line HL-60 / 中国实验血液学杂志

The study was aimed to investigate the expression of Rac1 in human acute leukemic cell line HL-60 and effect of Rac1 on cell cycle progression and apoptosis. The mRNA expression of Rac1 in HL-60 cell line and normal human peripheral blood mononuclear cells (PBMNC) were examined by semi-quantitative RT-PCR. After transfection of HL-60 cells with different concentrations of Rac1 antisense oligodeoxynucleotide (ASODN) by means of FuGENE6, the survival, cell cycle, apoptosis of HL-60 cells were observed through MTT assay, FCM test, Wright-Giemsa, acridine orange/ethidium bromide (AO/EB) and Annexin V-FITC/PI staining test respectively. The results showed that Rac1 relative amount in HL-60 was 0.84 +/- 0.13, while it in the normal PBMNC was 0.26 +/- 0.1 (P < 0.01); the expression of Rac1 in HL-60 cells was significantly upregulated. Compared with sense oligodeoxynucleotide (SODN), HL-60 cell viability, after exposure to ASODN at a concentration of 2.0 g/L decreased, (73.7 +/- 5.0)% vs (93.2 +/- 3.0)% (P < 0.01), while the proportion of G(1) cells increased as (52.1 +/- 6.8)% vs (31.6 +/- 4.7)% (P < 0.05), the percentage of Annexin V positive cells increased, (19.2 +/- 2.1)% vs (4.1 +/- 1.7)% (P < 0.01), and HL-60 cells were observed to have formation of apoptotic bodies. The data presented indicate that Rac1 may be involved in regulation of HL-60 cell cycle and apoptosis, promote overproliferation of HL-60 cells and inhibit their apoptosis.

Tyrosine kinase inhibitor reverses adriamycin resistance mediated by cell adhesion in RPMI8226 cells / 中国实验血液学杂志

To study the effects of tyrosine-kinase inhibitor STI571 on the adhesion of RPMI8226 cells to fibronectin (FN), cell adhesion mediated adriamycin-resistance and the Rac1 mRNA expression, the adhesion of RPMI8226 cells to fibronectin and drug resistance mediated by cell adhesion were determined by means of crystal violet staining and MTT assays respectively, Rac1 mRNA levels in RPMI8226 cells were examined by semi-quantitative RT-PCR. The results showed that STI571 could inhibit the adhesion of RPMI8226 cells to fibronectin. When RPMI8226 cells had been adhered to FN or BSA-coated wells for 1, 6 and 12 hours, the adhesion rates were (43.71 +/- 2.18)%, (55.63 +/- 1.56)%, and (63.42 +/- 2.46)% respectively. After treatment with STI571 20 micromol/L, the adhesion rates decreased to (15.12 +/- 1.04)%, (17.58 +/- 1.32)% and (17.24 +/- 1.59)% respectively (P < 0.05). The experiment revealed that growth of RPMI8226 cells adhered to FN-coated plates had a significant advantage over growth on BSA-coated plates when exposed to adriamycin (Adr) for 1 hour followed by a 24-hour culture period, and the mean IC(50) value for FN-adhered cells was (1.46 +/- 0.04) micromol/L while mean IC(50) value for BSA control was (0.78 +/- 0.03) micromol/L (P < 0.05). Following treatment with 20 micromol/L STI571, the mean IC50 values for FN and BSA adhered cells were (0.81 +/- 0.05) micromol/L, (0.74 +/- 0.02) micromol/L respectively, there was no significant difference between them (P > 0.05). RT-PCR demonstrated that the relative Rac1 mRNA level (Rac1/GAPDH) in RPMI8226 cells was downregulated following being treated with 20 micromol/L STI571. It is concluded that STI571 can inhibit the adhesion of RPMI8226 cells to fibronectin, reverse cell adhesion mediated adriamycin-resistance, and downregulate Rac1 mRNA level.

Difference of gene expression profiles between HL-60/VCR and HL-60 cells detected by human genome genechip / 中国实验血液学杂志

This study was aimed to detect the gene expression profile changes between human acute leukemia cell line HL-60 and VCR-resistance HL-60, and to investigate the underlying mechanisms of MDR by using genechip technology. In experiments, mRNA were harvested using TrizoL reagent from these two cell lines, through RT-PCR, the biotinylated nucleotide were incorporated into the cRNA during the in vitro transcription reaction. The high quality RNA was hybridized to the gene expression array--human genome U133A developed by Affymetrix. It was scanned by G2500A GeneArray Scanner and the acquired image was analysed by a series of softwares. The results showed that 5,507 genes were differentially expressed between human acute leukemia cell line HL-60 and VCR-resistant HL-60. Compared with HL-60, 3,100 genes were up-regulated and 2,407 genes were down-regulated in VCR-resistant cell line. These genes were involved in different cell activities such as growth regulation and signal transduction. Among the genes with remarkable differential expression between the two cell lines, 435 were up-regulated and 605 were down-regulated. It is concluded that many different kinds of genes are involved in the mechanism of MDR and there is an intricate molecular network that controls the sensitivity of leukemia cells to the chemotherapeutic agents. Genechip is an efficient tool for parallel gene expression analysis.