Interaction of WAVE1 and genes involved in multiple drug resistance in children with acute myeloblastic leukemia / 中华儿科杂志

<p><b>OBJECTIVE</b>Multidrug resistance (MDR) is one of the primary causes of suboptimal outcomes in chemotherapy of children with acute myeloblastic leukemia (AML). The mechanisms of drug transport resistance may chiefly contribute to MDR. Expression and/or activity of P-glycoprotein (P-gp), multiple resistance-associated protein-1 (MRP1), lung-resistance related protein (LRP) and breast cancer resistance protein (BCRP) have been considered to be associated with unfavourable outcomes in pediatric AML patients. In previous studies, we found WASP-family verprolin-homologous protein-1 (WAVE1) was involved in the MDR mechanisms in K562/A02 leukemia cells. To investigate the expression of WAVE1, P-gp, MRP1, LRP/MVP and BCRP; and if WAVE1 is involved in MDR of human leukemia cell.</p><p><b>METHODS</b>WAVE1, P-gp, MRP1, LRP, BCRP mRNA and protein expression in bone marrow mononuclear cells (BMMCs) were measured by real-time fluorescence quantitative PCR (RQ-PCR) and Western blot in a cohort of 52 children with acute myeloblastic leukemia. During follow-up, of the 52 patients, 21 were documented as being relapsing or refractory, and 31 were induced into complete continuous remission. Furthermore, HL60 cells and HL60/ADR cells were transiently transfected with PCDNA3.1-WAVE1 reconstructed plasmid and specifically siRNA to WAVE1 respectively, and the expression of WAVE1, MRP1 and BCRP before and after transfection was assessed by real-time PCR and Western blot analysis.</p><p><b>RESULTS</b>(1) The expression levels of WAVE1, P-gp, MRP, LRP and BCRP in refractory/relapsing group were much higher than that in complete continuous remission (CCR) group. (2) WAVE1 mRNA and protein expression in BMMCs of children were at higher levels when they were newly diagnosed or relapsed, compared with complete continuous remission. (3) The WAVE1 expression at mRNA and protein level in HL60/ADR cells was increased by about 353% and 95% respectively as compared with that in HL60 cells. (4) Overexpression of WAVE1 in HL60 cell lines upregulated the expression levels of MRP and BCRP (MRP mRNA and protein level were increased by about 16.54 times and 129% respectively, BCRP was increased by 4.93 times and 96%); whereas suppression of WAVE1 expression by RNA interference downregulated the expression levels of MRP1 and BCRP (MRP mRNA and protein level was only 11% and 43% of pre-disturbance respectively, BCRP was 14% and 71%).</p><p><b>CONCLUSIONS</b>Higher levels of WAVE1 in the BM indicate an unfavorable prognosis in children with AML. WAVE1 is related to the development of AML and involved in the MDR mechanisms, and regulates the level of MRP1 and BCRP.</p>

Expression of WAVE1 and p22phox in children with acute lymphocytic leukemia and the relationship of WAVE1 with oxidative stress / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the expression of WAVE1 and p22phox in peripheral blood mononuclear cells (PBMCs) in children with acute lymphocytic leukemia (ALL) and the relationship of WAVE1 with oxidative stress.</p><p><b>METHODS</b>Real-time PCR was used for detecting WAVE1 and p22phox expression in PBMCs in 41 children with ALL and 10 normal controls. Plasma activity of superoxide dismutase (SOD) was measured by the xanthine oxidase method. Plasma activity of GSH-Px was measured by the DTNB reaction test.</p><p><b>RESULTS</b>The expression of WAVE1 and p22phox was significantly higher in the active ALL groups (newly diagnosed and relapse ALL) than that in the normal control and the complete remission (CR) ALL groups (<0.01). The CR ALL group showed increased WAVE1 and p22phox expression than those in the normal control group (<0.05). Plasma activities of SOD (22.62+/-7.39 U/mL) and GSH-Px (91.73+/-28.88 micromol/L) in the active ALL group were significantly lower than those in the normal control (166.35+/-27.93 U/mL and 490.94+/-39.38 micromol/L, respectively) and the CR ALL groups (107.11+/-28.57 U/mL and 267.56+/-82.64 micromol/L, respectively) (<0.01). WAVE1 expression was positively correlated with p22phox expression (r=0.34, <0.05) but negatively correlated with plasma activities of SOD and GSH-Px ( r=-0.336 and-0.408, respectively; <0.05).</p><p><b>CONCLUSIONS</b>WAVE1 and p22phox expression in PBMCs increased and was associated with the disease course in children with ALL. Oxidative stress may be involved in the regulation of WAVE1 expression in ALL children.</p>

Role of WAVE1 in K562 leukemia cells invasion and its mechanism / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate role of WASP family verprolin homologous protein 1 (WAVE1) in K562 leukemia cell invasion and its mechanism.</p><p><b>METHODS</b>Immunofluorescence method was used to detect the distribution of WAVE1 and MMP-2 in the cells. K562 cells were transfected with pcDNA3. 1-WAVE1 reconstructed plasmid or with specific siRNA to WAVE1 gene. The invasion ability of K562 cells was examined by Transwell assay. The expression level of WAVE1 and MMP-2 in K562 cells was assayed by real-time PCR and Western blot.</p><p><b>RESULTS</b>(1) WAVE1 and MMP-2 mainly expressed and co-localized in the cell membrane; (2) 24 h and 48 h after transfected with pcDNA3. 1-WAVE1, the MMP-2 mRNA level in K562 cells increased by 295% and 198% while its protein increased by 80% and 23% respectively as compared with control K562 cells. At the same time point after transfected with specific siRNA, the MMP-2 mRNA level decreased by 81% and 28%, and its protein decreased by 36% and 53% respectively as compared with control. (3) The invasion ability of K562 cells was enhanced after transfected with pcDNA3. 1-WAVE1 and depressed after transfected with the specific siRNA.</p><p><b>CONCLUSION</b>The co-localization of WAVE1 and MMP-2 in K562 cells suggests they coordinate in functions; WAVE1 may involve in the migration and invasion of K562 cells through regulating the expression level of MMP-2.</p>

Efficacy and prognosis analysis in 188 children with acute lymphoblastic leukemia of China / 中华儿科杂志

<p><b>OBJECTIVE</b>To analyze the therapeutic effect and the influencing factors of event-free survival (EFS) of childhood acute lymphoblastic leukemia (ALL) in Xiangya Hospital of Central South University and the First Affiliated Hospital of Guangxi Medical University.</p><p><b>METHODS</b>All the patients adopted chemotherapy according to therapeutic guideline revised by the Subspecialty Group of Hematology, The Society of Pediatrics, Chinese Medical Association for the second-time in 1998 (the Rongcheng ALL-98 Protocol). Kaplan-Meier method was used to estimate the survival rates of 188 patients who received therapy with good compliance. The differences of EFS between groups were assessed by Log-rank test. The independent influencing factors on EFS were analyzed by the Cox proportional hazards regression model.</p><p><b>RESULTS</b>After receiving inductive treatment, 354 of 374 (93.6%) patients demonstrated a complete remission; 188 patients who received complete courses of treatment with good compliance showed (68.1 +/- 5.6)% five-year EFS. Meanwhile, the five-year EFS in standard-risk (SR) group and high-risk (HR) group were (75.2 +/- 6.0)% and (47.6 +/- 11.6)%, respectively. The total relapse rate was 10.6% and the median time to relapse was 13 months. Twenty-nine of 188 patients (15.4%) were dead, and 13 patients (7.0%) died from treatment-related complications. Independent adverse prognostic factors included risk grouping, t (9; 22)/bcr-abl gene and leukocyte count.</p><p><b>CONCLUSIONS</b>The total EFS of childhood ALL patients treated with Rongcheng ALL-98 Protocol in two hospitals was close to 70%. Therefore, it is necessary to evaluate risk factors and consider the grouping in more detail to reduce the treatment-related mortality and to increase the compliance of treatment which can ultimately improve the EFS.</p>

Enhancive effect of HMGB1 gene silence on adriamycin-induced apoptosis in K562/A02 drug resistance leukemia cells / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the effect of high mobility group boxl (HMGBI) gene silence on adriamycin (ADM)-induced apoptosis in K562/A02 drug resistance leukemia cells.</p><p><b>METHODS</b>K562/ A02 cells were transient transfected with HMGB1- small interference RNA(siRNA) vector, and the levels of HMGB1 gene differential expression pre-and post-transfection were measured by RT-PCR and Western blotting. 50% inhibition concentration (IC50) of ADM on K562/A02 was determined by WST-8 assay. Cell apoptosis was assessed by flow cytometry. The release of Smac/DIABLO from the mitochondria to the cytoplasm was assayed by Western blotting. Activity of Caspase-3 was assayed with a Caspase Colorimetric Assay Kit.</p><p><b>RESULTS</b>(1) The HMGB1 expression at mRNA and protein levels in HMGB1 siRNA transfected K562/A02 cells were decreased by 86% and 71% respectively compared with control. (2) Suppression of HMGB1 by siRNA in K562/A02 cells resulted in a reversal of the resistance to ADM, and decreased IC50 from (4.83 +/- 0.08) microg/ml to (1.33 +/- 0.10) microg/ml. 1 microg/ml and 5 microg/ml of ADM treatment increased cell apoptotic rate by 27% and 32% respectively. (3) HMGB1 suppression in K562/A02 cells significantly promoted ADM- induced Smac/DIABLO release from the mitochondria to the cytoplasm, and increased the activities of Caspase-3.</p><p><b>CONCLUSION</b>HMGB1 gene silence can enhance sensitivity of K562/A02 cells to ADM and reverse cell resistant to ADM.</p>