Mechanism of miR-155 Promoting Drug Resistance in Childhood Acute Lymphoblastic Leukemia by Regulating Wnt/β-Catenin Signaling Pathway / 中国实验血液学杂志

OBJECTIVE@#To investigate the mechanism of miR-155 promoting drug resistance of children B-ALL to Ara-C by regulating Wnt/β-Catenin signaling pathway.@*METHODS@#The expression of miR-155 in bone marrow tissue and cell line of B-ALL was detected by PCR. The chemotherapy resistant strain REH/ Ara-C was constructed by using REH cells. REH/ Ara-C cells were transfected with miR-155 inhibitor. The proliferation of REH/Ara-C cells was detected by EdU. The apoptosis of REH/ Ara-C cells was detected by flow cytometry. The drug resistance of REH/Ara-C cells were analyzed by CCK-8 method and colony formation assay. The expression of Wnt/β-Catenin signaling pathway related proteins were determined by Western blot. MiR-155 inhibitor and Wnt activator agonist were used to transfect REH/Ara-C cells, and their effects on cell proliferation, apoptosis and drug resistance were determined.@*RESULTS@#Compared with normal tissues and cells, the expression level of miR-155 in B-ALL bone marrow tissue/cell line was increased (P<0.05); Compared with drug sensitive B-ALL tissues/cell lines, the expression level of miR-155 in drug resistant B-ALL tissues and cell lines was increased (P<0.05); Inhibition of miR-155 expression decreased the proliferation of REH/Ara-C cells (P<0.05), promoted apoptosis (P<0.05), enhanced the cytotoxicity of Ara-C (P<0.05), and inhibited Wnt/β-Catenin signaling pathway related protein and MDR1 gene expression (P<0.05), which could be reversed by activating Wnt expression (P<0.05).@*CONCLUSION@#The expression of miR-155 is up-regulated in bone marrow of children with B-ALL, which may be related to the activation of Wnt/β-Catenin signaling pathway promotes the proliferation of B-ALL cells and inhibits apoptosis, which leads to chemotherapy resistance.

Effect of Hypoxia Inducible Factor-1α on Chemosensitivity of B-ALL Cells to Vincristine and Its Mechanism / 中国实验血液学杂志

OBJECTIVE@#To explore the effect of hypoxia on the chemosensitivity of B-acute lymphoblastic leukemia （B-ALL） cells to Vincristine (VCR) and the mechanisms.@*METHODS@#B-ALL cells SUP-B15, Nalm-6 and RS4;11 were selected as the research objects. The cells were divided into the control group and the hypoxia mimic group (CoCl2 pretreatment). The two groups were treated with VCR at different concentrations for 24 hours, CCK-8 was used to detect cell viability, flow cytometry was used to detect cell apoptosis, and Western bolt method was used to detect hypoxia inducible factor (HIF-1α), BAX, Bcl-2 and β-actin protein expression. Quantitative real-time fluorescent PCR (qRT-PCR) was used to detect BAX and β-actin mRNA levels.@*RESULTS@#CoCl2 could simulate hypoxic environment to induce the expression of HIF-1α. The cells SUP-B15 and RS4;11 of the hypoxia mimic group were lower sensitivity to VCR as compared with the control group; the apoptosis rate of the hypoxia mimic group was lower than that of the control group after 80 nmol/L VCR treatment. The expression levels of BAX protein and mRNA in the hypoxia mimic group were lower than those of the control group, and there was no significant difference in the expression levels of Bcl-2 protein between two groups.@*CONCLUSION@#Under hypoxic conditions, HIF-1α may mediate VCR resistance in B-ALL cells by downregulating the pro-apoptotic protein BAX.

A rare morphological and immunophenotypic presentation of adult B-cell acute lymphoblastic leukemia with blasts in the monocytic zone on CD45 side scatter

We present a case of B-acute lymphoblastic leukemiain an elderly patient who presented with severe weakness and pancytopenia. The patient was a 75 year old Female whose blasts had an unusual morphology in form of coarse azurophilic granules and cytoplasmic blebs and on flow cytometry the blasts were present in the bright CD45 zone with a high side scatter. Bone marrow aspirate sample was subjected to multicolour flow cytometry using Beckman Coulter Navios® which is an 8 colour flow cytometer.Flow cytometricanalysis of the bone marrow aspirate showed blasts in the monocytic zone with a precursor B cell immunophenotype. Complete blood counts showed pancytopenia with peripheral blood film not showingany blasts. Bone marrow aspirate smears showed 20% blasts with coarse azurophilic granules and cytoplasmic blebs.The position of the blasts in this case which were in monocytic zone giving them a bright expression of CD45 and a high side scatter on the CD45 side scatter. This is not the usual positionfor blasts in B-acute lymphoblastic leukemia as these blasts are less complex. A bright expression of CD45 by blasts in B-acute lymphoblastic leukemia is known to be associated with a poor prognosis but the clinical significance of blasts being bright CD45 with a high side scatter is a very rare occurrence and more number of cases with a similar presentation are required to determine a prognostic significance.

A novel chromosomal abnormality t (9;14)(p24;q13) in B-acute lymphoblastic leukemia.

Acute lymphoblastic leukemia is a malignant disease of the bone marrow in which early lymphoid precursors proliferate and replace the normal hematopoietic cells of the marrow. We describe the clinical, morphologic, immunophenotypic and cytogenetic findings in the case of a 26‑year‑old man with B‑lymphoblastic leukemia. Surface marker analysis revealed that they are positive for CD markers CD10, CD19, CD13, CD34, CD45 and HLA‑DR, but negative for CD20, CD33, CD117 and CD11C markers. Cytogenetic analysis established a novel translocation, t (9;14)(p24;q13). Apart from this, spectral karyotyping revealed an additional translocation, t (6p; 14q). This is the first documented case of B‑lymphoblastic leukemia with concurrent occurrence of both abnormalities. Further studies are needed to understand the role of this abnormality in carcinogenesis.

Pattern of chromosome involvement in childhood hyperdiploid pre-B-cell acute lymhoblastic leukemia cases from India.

BACKGROUND: Hyperdiploid pre‑B‑cell acute lymhoblastic leukemia (pre‑B‑ALL) is a common form of childhood leukemia with very good prognosis with present day chemotherapy. However, the chromosomal composition of the hyperdiploidy has not been extensively studied and possible mechanism for this pathology remains so far conjectural. OBJECTIVE: To analyze the pattern of chromosome involvement in a cohort of childhood hyperdiploid pre‑B‑ALL from India and from this pattern to develop an understanding on the causation of such pathology. Whether such patients also carry translocations and FLT3 mutations in addition to their hyperdiploid karyotype. MATERIALS AND METHODS: One hundred and twenty‑six childhood pre‑B‑ALL patients were studied. Bone marrow aspirate of these patients were evacuated for morphology, FAB classification, immunophenotyping and both conventional and molecular cytogenetics. RESULTS: Of 126 patients with pre‑B‑ALL (age 2-15 years), 90 patients with abnormal karyotype showed 50 with hyperdiploid karyotype (50/90 i.e. 55.5%). Chromosomes 9, 10, 14, 17, 18, 20 and 21 were more often involved in hyperdiploidy. Chromosome 21 duplication was present in 92% of the cases. Chromosomes 5, 15, 16, 17 and Y were less often involved (18-20%) in hyperdiploidy. About 44% of patients with hyperdiploidy had additional karyotypic abnormality of which TEL‑AML1 was predominant (24%). Chromosome loss was rare and accounted for 20% of the cases only. We did not find any FLT3 mutation in our patients. CONCLUSION: In this study, the pattern of chromosome involvement in hyperdiploid karyotype of ALL patients is same as other studies except some chromosomes like 1, 6, 11, 12, 19 and 22 have some more frequent involvement than other studies. This study also showed the occurrence of TEL/AML1 fusion is more (19.8%) than other reports from India.

Prognostic significance of bone marrow examination during induction chemotherapy for B acute lymphoblastic leukemia / 中华实用儿科临床杂志

Objective To explore the prognostic significance of bone marrow examination at different time points by using different methods during induction therapy.Methods From Feb.2004 to Jan.2013,268 newly diagnosed (B acute lymphoblastic leukemia,B-ALL) pediatric patients in Peking University People's Hospital,were enrolled for the study.In this study,the overall survival (OS) ratio and event-free survival(EFS) ratio of patients with different bone marrow morphology on day 8 and day 15 were analyzed.Based on different cut off value of minimal residual disease (MRD) on day 15 and end-of-induction,the OS ratio and EFS ratio of the higher patients and the lower patients were compared.Results Patients with M1,M2 or M3 marrows on day 8 had no significant difference in OS ratio (P =0.372) or EFS ratio (P =0.393).When it came to day 15,patients with M1,M2 or M3 marrows had no significant difference in OS ratio (P =0.050) or EFS ratio (P =0.324).Patients with MRD ＞ 10.00％ on day 15 had lower OS ratio than those with MRD ≤ 10.00％,and it had significant difference(P =0.022).But there was no significant difference in EFS ratio (P =0.191).As for MRD on the end-of-induction,when using the MRD level of 0.0l ％,0.10％,1.00％ as cut-off values,the lower group of end-of-induction MRD was significantly associated with a higher probability of OS ratio and it had significant differences(P =0.018,0.006,0.002),and it showed the same results at EFS ratio (P =0.002,0.000,0.000).Conclusions The bone marrow morphology on day 8 and day 15 during induction therapy had no prognostic significance.The MRD of day 15 had prognostic significance when using 10.00％ as the cut off value.The critical value of MRD on the end-of-induction MRD should be 0.01％ for the prognosis.