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>

Allelic loss of 6q16.3 microsatellite DNA in childhood acute lymphoblastic leukemia and bioinformatics analysis / 中华血液学杂志

<p><b>OBJECTIVE</b>To locate the cluster region of loss of heterozygosity (LOH) in children with acute lymphoblastic leukemia (ALL), and explore the new tumor suppressor gene.</p><p><b>METHODS</b>Allelic loss was analyzed by PCR with 15 microsatellite markers mapping on 6q16.3. The LOH was analyzed by bioinformatics. The relationship between LOH and clinical factors was further analyzed.</p><p><b>RESULTS</b>The frequency of LOH at least at one loci on 6q16.3 was 32.7%. The LOH in relapsed patients was higher than those in not relapsed. The higher frequency of LOH was observed in two regions of D6S1709-D6S1028 and D6S2160-D6S1580 at 6q16.3. GRIK2 may be a candidate of tumor suppressor gene. There are 12 ESTs may carry out new anti-oncogene. Patients with 6q LOH had higher WBC counts (P < 0.01), blast cells percentage (P < 0.01), relapse rate (P < 0.05) and chromosomal aberration (P < 0.05).</p><p><b>CONCLUSION</b>D6S1709-D6S1028 and D6S2160-D6S1580 are two regions of minimus deletion on 6q16.3 in which tumor suppressor gene may exist. The LOH on 6q16.3 may be a prognostic index of children with ALL.</p>