The Role of Mitochondrial VDAC2 in the Survival and Proliferation of T-Cell Acute Lymphoblastic Leukemia Cells

Background: T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy with aberrant T-cell developmental arrest. Individuals with relapsed T-ALL have limited therapeutic alternatives and poor prognosis. The mitochondrial function is critical for the T-cell viability. The voltage-dependent anion channel 2 (VDAC2) in the mitochondrial outer membrane, interacts with pro-apoptotic BCL-2 proteins and mediates the apoptosis of several cancer cell lines. Objective: The aim of the current study is to explore the role of VDAC2 in T-ALL cell survival and proliferation. Methods: Publicly available datasets of RNA-seq results were analyzed for expression of VDAC isoforms and T-ALL cell lines were treated with a VDAC2 small molecular inhibitor erastin. A VDAC2 RNA interference (siRNA) was delivered to T-ALL cell lines using a retroviral vector. Functional assays were performed to investigate the VDAC2 siRNA impacts on cell proliferation, apoptosis and survival of T-ALL cells. Results: Our analysis found a high expression of VDAC2 mRNA in various T-ALL cell lines. Public datasets of T-ALL RNA-seq also showed that VDAC2 is highly expressed in T-ALL (116.2 ± 36.7), compared to control groups. Only two T-ALL cell lines showed sensitivity to erastin (20 μM) after 48 hours of incubation, including Jurkat (IC50 = 3.943 μM) and Molt4 (IC50 = 3.286 μM), while another two T-ALL cells (CUTLL1 and RPMI 8402) had unstable IC50. However, five T-ALL cell lines (LOUCY, CCRF-CEM, P12-ICHI, HPB-ALL, and PEER cells) showed resistance to erastin. On the contrary, all T-ALL cell lines genetically inhibited with VDAC2 siRNA led to more than 80% decrease in VDAC2 mRNA levels, and a Conclusion: VDAC2 is highly expressed in T-ALL cells. The inhibition of VDAC2 significantly decreased cell viability, increased apoptosis, reduced cell proliferation and caused cell cycle sub-G1 arrest of T-ALL cells.

Resveratrol Induces Apoptosis and Autophagy in T-cell Acute Lymphoblastic Leukemia Cells by Inhibiting Akt/mTOR and Activating p38-MAPK

Objective To explore the effects of resveratrol-induced apoptosis and autophagy in T-cell acute lymphoblastic leukemia （T-ALL） cells and potential molecular mechanisms. Methods The anti-proliferation effect of resveratrol-induced, apoptosis and autophagy on T-ALL cells were detected by using MTI- test, immunofluorescence, electronic microscope, and flow cytometry, respectively. Western blotting was performed for detecting changes of apoptosis-associated proteins, cell cycle regulatory proteins and state of activation of Akt, mTOR, p70S6K, 4E-BP1, and p38-MAPK. Results Resveratrol inhibited the proliferation and dose and time-dependent manner. It also induced cyclin-dependent kinase （CDK） inhibitors p21 and induced apoptosis and autophagy in T-ALL cells in a cell cycle arrest at G0/G1 phase via up regulating p27 and down regulating cyclin A and cyclin D1. Western blotting revealed that resveratrol significantly decreased the expression of antiapoptotic proteins （Mcl-1 and Bcl-2） and increased the expression of proapoptotic proteins （Bax, Bim, and Bad）, and induced cleaved-caspase-3 in a time-dependent manner. Significant increase in ratio of LC3-11/LC3-1 and Beclin 1 was also detected. Furthermore, resveratrol induced significant dephosphorylation of Akt, mTOR, p70S6K, and 4E-BP1, but enhanced specific phosphorylation of p38-MAPK which could be blocked by SB203580. When autophagy was suppressed by 3-MA, apoptosis in T-ALL cells induced by resveratrol was enhanced. Conclusion Our findings have suggested that resveratrol induces cell cycle arrest, apoptosis, and autophagy in T-ALL cells through inhibiting Akt/mTOR/p7OS6K/4E-BP1 and activating p38-MAPK signaling pathways. Autophagy might play a role as a self-defense mechanism in T-ALL cells treated by resveratrol. Therefore, the reasonable inhibition of autophagy in T-ALL cells may serve as a promising strategy for resveratrol induced apoptosis and can be used as adjuvant chemotherapy for T-ALL.

Predictive Value of Dynamic Peri-Transplantation MRD Assessed By MFC Either Alone or in Combination with Other Variables for Outcomes of Patients with T-Cell Acute Lymphoblastic Leukemia

We performed a retrospective analysis to investigate dynamic peri-hematopoieticstem cell transplantation(HSCT)minimal/measurable residual disease(MRD)on outcomes inpatients with T-cell acute lymphoblastic leukemia(T-ALL).A total of 271 patients were enrolledand classified into three groups:unchanged ncgative MRD pre-and post-HSCT group(group A),post-MRD non-increase group(group B),and post-MRD increase group(group C).The patientsin group B and group C experienced a higher cumulative incidence of relapse(CIR)(42%vs.71%vs.16%,P<0.001)and lower leukemia-free survival(LFS)(46%vs.21%vs.70%,P<0.001)andoverall survival(OS)(50%vs.28%vs.72%,P<0.001)than in group A,but there was no significantdifference in non-relapse mortality(NRM)among three groups(14%vs.12%vs.8%,P=0.752).Multivariate analysis showed that dynamic peri-HSCT MRD was associated with CIR(HR=2.392,95%CI,1.816-3.151,P<0.001),LFS(HR=1.964,95%CI,1.546-2.496,P<0.001)and os(HR=1.731,95%CI,1.348-2.222,P<0.001).We also established a risk scoring system based ondynamic peri-HSCT MRD combined with remission status pre-HSCT and onsct of chronic graft-versus-host disease(GVHD).This risk scoring system could better distinguish ClR(c=0.730)thanthat for pre-HSCT MRD(c=0.562),post-HSCT MRD(c=0.616)and pre-and post-MRD dynamics(c=0.648).Our results confirm the outcome predictive value of dynamic peri-HSCT MRD eitheralone or in combination with other variables for patients with T-ALL.

MicroRNA-145-3p suppresses the malignant behaviors of T-cell acute lymphoblastic leukemia Jurkat cells via inhibiting the NF-kappaB signaling pathway

T-cell acute lymphoblastic leukemia(T-ALL)is a hematological tumor caused by the malignant transformation of immature T-cell progenitor cells.Emerging studies have stated that microRNAs(miRNAs)may play key roles in T-ALL progression.This study aimed to investigate the roles of miR-145-3p in T-ALL cell proliferation,invasion,and apoptosis with the involvement of the nuclear factor-kappaB(NF-κB)signaling pathway.T-ALL Jurkat cells were harvested,and the expression of miR-145-3p and NF-κB-p65 was measured.Gain-and loss-of-functions of miR-145-3p and NF-κB-p65 were performed to identify their roles in the biological behaviors of Jurkat cells,including proliferation,apoptosis,and invasion.Consequently,the current study demonstrated that miR-145-3p was down-regulated while NF-κB-p65 was up-regulated in Jurkat cells.miR-145-3p directly bound to the 3’untranslated region of NF-κB-p65.Over-expression of miR-145-3p inhibited Jurkat cell proliferation,invasion,and resistance to apoptosis,while over-expression of NF-κB-p65 presented opposite trends.Co-transfection of miR-145-3p and NF-κB-p65 promoted the malignant behaviors of Jurkat cells compared to miR-145-3p transfection alone,while it reduced these behaviors of Jurkat cells compared to NF-κB-p65 transfection alone.Taken together,this study provided evidence that miR-145-3p could suppress proliferation,invasion,and resistance to the death of T-ALL cells via inactivating the NF-κB signaling pathway.

A facile,branched DNA assay to quantitatively measure glucocorticoid receptor auto-regulation in T-cell acute lymphoblastic leukemia

Glucocorticoid(GC) steroid hormones are used to treat acute lymphoblastic leukemia(ALL) because of their pro-apoptotic effects in hematopoietic cells.However,not all leukemia cells are sensitive to GC,and no assay to stratify patients is available.In the GC-sensitive T-cell ALL cell line CEM-C7,auto-up-regulation of RNA transcripts for the glucocorticoid receptor(GR) correlates with increased apoptotic response.This study aimed to determine if a facile assay of GR transcript levels might be promising for stratifying ALL patients into hormone-sensitive and hormone-resistant populations.The GR transcript profiles of various lymphoid cell lines and 4 bone marrow samples from patients with T-cell ALL were analyzed using both an optimized branched DNA(bDNA) assay and a real-time quantitative reverse transcription-polymerase chain reaction assay.There were significant correlations between both assay platforms when measuring total GR(exon 5/6) transcripts in various cell lines and patient samples,but not for a probe set that detects a specific,low abundance GR transcript(exon 1A3).Our results suggest that the bDNA platform is reproducible and precise when measuring total GR transcripts and,with further development,may ultimately offer a simple clinical assay to aid in the prediction of GC-sensitivity in ALL patients.

Multi-omics integration reveals potential stage-specific druggable targets in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia(T-ALL),a heterogeneous hematological malignancy,is caused by the developmental arrest of normal T-cell progenitors.The development of targeted therapeutic regimens is impeded by poor knowledge of the stage-specific aberrances in this disease.In this study,we performed multi-omics integration analysis,which included mRNA expression,chromatin accessibility,and gene-dependency database analyses,to identify potential stage-specific druggable targets and repositioned drugs for this disease.This multi-omics integration helped identify 29 potential pathological genes for T-ALL.These genes exhibited tissue-specific expression profiles and were enriched in the cell cycle,hematopoietic stem cell differentiation,and the AMPK signaling pathway.Of these,four known druggable targets(CDK6,TUBA1A,TUBB,and TYMS)showed dysregulated and stage-specific expression in malignant T cells and may serve as stage-specific targets in T-ALL.The TUBA1A expression level was higher in the early T cell precursor(ETP)-ALL cells,while TUBB and TYMS were mainly highly expressed in malignant T cells arrested at the CD4 and CD8 double-positive or single-positive stage.CDK6 exhibited a U-shaped expression pattern in malignant T cells along the naıve to maturation stages.Furthermore,mebendazole and gemcitabine,which target TUBA1A and TYMS,respectively,exerted stage-specific inhibitory effects on T-ALL cell lines,indicating their potential stage-specific antileukemic role in T-ALL.Collectively,our findings might aid in identifying potential stage-specific druggable targets and are promising for achieving more precise therapeutic strategies for T-ALL.

Novel PIKfyve/Tubulin Dual-target Inhibitor as a Promising Therapeutic Strategy for B-cell Acute Lymphoblastic Leukemia

Objective:In B-cell acute lymphoblastic leukemia(B-ALL),current intensive chemotherapies for adult patients fail to achieve durable responses in more than 50%of cases,underscoring the urgent need for new therapeutic regimens for this patient population.The present study aimed to determine whether HZX-02-059,a novel dual-target inhibitor targeting both phosphatidylinositol-3-phosphate 5-kinase(PIKfyve)and tubulin,is lethal to B-ALL cells and is a potential therapeutic for B-ALL patients.Methods:Cell proliferation,vacuolization,apoptosis,cell cycle,and in-vivo tumor growth were evaluated.In addition,Genome-wide RNA-sequencing studies were conducted to elucidate the mechanisms of action underlying the anti-leukemia activity of HZX-02-059 in B-ALL.Results:HZX-02-059 was found to inhibit cell proliferation,induce vacuolization,promote apoptosis,block the cell cycle,and reduce in-vivo tumor growth.Downregulation of the p53 pathway and suppression of the phosphoinositide 3-kinase(PI3K)/AKT pathway and the downstream transcription factors c-Myc and NF-κB were responsible for these observations.Conclusion:Overall,these findings suggest that HZX-02-059 is a promising agent for the treatment of B-ALL patients resistant to conventional therapies.

Damage Mechanism of CK2 and IKAROS in Philadelphia Like Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is characterized by immature and poorly differentiated B lymphocytes in large numbers in the blood. B cells are distinct from the cell types involved in their development (common lymphoid progenitor cells, pro-B cells, pre-B cells, and mature cells). The process of B cell maturation depends on precise communication within the cell: signals activate specific genes that are essential for proper development. Errors in this intricate signaling network can lead to issues with B cell function and contribute to disease. B-lineage acute lymphoid leukemias, malignancies of precursor-stage B lymphoid cells inhibit lymphoid differentiation, leading to abnormal cell proliferation and survival. The process of developing leukemia (leukemogenesis) can be triggered by an overproduction of both hematopoietic stem cells (the cells that form all blood cells) and the immature versions of white blood cells called lymphoblasts. Acute lymphoblastic leukemia (ALL) with the presence of the Philadelphia chromosome (ALL Ph) is classified as a high-risk manifestation of the disease, this chromosome is the product of the reciprocal translocation, whose product is a BCR-ABL fusion protein. It is a highly active tyrosine kinase that can transform hematopoietic cells into cytokine-independent. Hyperphosphorylation cascades inhibit the differentiating function of IKZF1 as a tumor suppressor gene which leads to an abnormal proliferation of B cells due to the presence of the Philadelphia chromosome;it inhibits the differentiating process, leukemogenesis involving immature B cells in the bloodstream can result from the uncontrolled growth and division of hematopoietic stem cells and immature lymphoblasts (the precursors to B cells).

Chidamide inhibits the NOTCH1-MYC signaling axis in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia(T-ALL)is one of the most dangerous hematological malignancies,with high tumor heterogeneity and poor prognosis.More than 60%of T-ALL patients carry NOTCH1 gene mutations,leading to abnormal expression of downstream target genes and aberrant activation of various signaling pathways.We found that chidamide,an HDAC inhibitor,exerts an antitumor effect on T-ALL cell lines and primary cells including an anti-NOTCH1 activity.In particular,chidamide inhibits the NOTCH1-MYC signaling axis by down-regulating the level of the intracellular form of NOTCH1(NICD1)as well as MYC,partly through their ubiquitination and degradation by the proteasome pathway.We also report here the preliminary results of our clinical trial supporting that a treatment by chidamide reduces minimal residual disease(MRD)in patients and is well tolerated.Our results highlight the effectiveness and safety of chidamide in the treatment of T-ALL patients,including those with NOTCH1 mutations and open the way to a new therapeutic strategy for these patients.

Haploidentical hematopoietic stem cell transplantation may improve long-term survival for children with high-risk T-cell acute lymphoblastic leukemia in first complete remission

Background: The role of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children with high-risk (HR) T-cell acute lymphoblastic leukemia (T-ALL) in first complete remission (CR1) is still under evaluation. Moreover, relapse is the main factor affecting survival. This study aimed to explore the effect of allo-HSCT (especially haploidentical HSCT [haplo-HSCT]) on improving survival and reducing relapse for HR childhood T-ALL in CR1 and the prognostic factors of childhood T-ALL in order to identify who could benefit from HSCT.Methods: A total of 74 newly diagnosed pediatric T-ALL patients between January 1, 2012 and June 30, 2018 were enrolled in this retrospective study. Patients were stratified into the low-risk chemotherapy cohort (n = 16), HR chemotherapy cohort (n = 31), and HR transplant cohort (n = 27). Characteristics, survival outcomes, and prognostic factors of all patients were then analyzed.Results: Patient prognosis in the HR chemotherapy cohort was significantly worse than that in the low-risk chemotherapy cohort (5-year overall survival [OS]: 58.5%vs. 100%,P = 0.003;5-year event-free survival [EFS]: 54.1%vs. 83.4%,P = 0.010;5-year cumulative incidence of relapse [CIR]: 45.2%vs. 6.3%,P = 0.011). In HR patients, allo-HSCT improved the 5-year EFS and CIR compared to that of chemotherapy (5-year EFS: 80.1%vs. 54.1%,P = 0.041;5-year CIR: 11.6%vs. 45.2%,P = 0.006). The 5-year OS was higher in the HR transplant cohort than that in the HR chemotherapy cohort (81.0%vs. 58.5%,P = 0.084). Minimal residual disease re-emergence was an independent risk factor for 5-year OS, EFS, and CIR;age ≥10 years was an independent risk factor for OS and EFS;and high white blood cell count was an independent risk factor for EFS and CIR.Conclusion: Allo-HSCT, especially haplo-HSCT, could effectively reduce relapse of children with HR T-ALL in CR1.

Comparison of the Effects of L-asparaginase and Pegaspargase in the Treatment of Adult Acute Lymphoblastic Leukemia

Objective:To compare the effect of L-asparaginase and pegaspargase in the treatment of adult acute lymphoblastic leukemia.Methods:In this study,96 patients who received treatment at the Shaanxi Provincial People’s Hospital from April 2019 to April 2021 were selected.The control group received L-asparaginase treatment,and the observation group received pegaspargase treatment.The curative effect and adverse reaction rate were compared between the two groups.Results:Comparing the experimental statistical results of the observation and the control groups,it can be concluded that the effect of the former group is better than that of the latter group in terms of clinical curative effect and statistics of adverse reactions.Conclusion:In the treatment of adult acute lymphoblastic leukemia,the application of pegaspargase therapy has a significantly better clinical effect and is worthy of further promotion.

Animal models of T-cell acute lymphoblastic leukemia: mimicking the human disease

T-cell acute lymphoblastic leukemia(T-ALL)is a heterogeneous group of hematological tumors composed of distinct subtypes that vary in their genetic abnormalities.In the past decade,large-scale genomic analysis has shed new light on providing potentially important oncogenic or tumor suppressive candidates involved in the disease progression.Following in silico analysis,functional studies are usually performed to vigorously investigate the biological roles of candidate genes.For this purpose,animal models faithfully recapitulating the human disease are widely applied to decipher the mechanism underlying T-cell transformation.Conversely,an increased understanding of T-ALL biology,including identification of oncogene NOTCH1,TAL1 and MYC as well as tumor suppressor phosphatase and tensin homolog(PTEN),has significantly improved the development of T-ALL animal models.These progresses have opened opportunities for development of new therapeutic strategy to benefit T-ALL patients.In this review,we particularly summarize the mouse and zebrafish models used in T-ALL research and also the most recent advances from these in vivo studies.

Targeting lactate dehydrogenase A (LDHA) exerts antileukemic effects on T-cell acute lymphoblastic leukemia

Background:T-cell acute lymphoblastic leukemia(T-ALL)is an uncommon and aggressive subtype of acute lymphoblastic leukemia(ALL).In the serum of T-ALL patients,the activity of lactate dehydrogenase A(LDHA)is increased.We proposed that targeting LDHA may be a potential strategy to improve T-ALL outcomes.The current study was conducted to investigate the antileukemic effect of LDHA gene-targeting treatment on T-ALL and the underlying molecular mechanism.Methods:Primary T-ALL cell lines Jurkat and DU528 were treated with the LDH inhibitor oxamate.MTT,colony formation,apoptosis,and cell cycle assays were performed to investigate the effects of oxamate on T-ALL cells.Quantitative real-time PCR(qPCR)and Western blotting analyses were applied to determine the related signaling pathways.A mitochondrial reactive oxygen species(ROS)assay was performed to evaluate ROS production after T-ALL cells were treated with oxamate.A T-ALL transgenic zebrafish model with LDHA gene knockdown was established using CRISPR/Cas9 gene-editing technology,and then TUNEL,Western blotting,and T-ALL tumor progression analyses were conducted to investigate the effects of LDHA gene knockdown on T-ALL transgenic zebrafish.Results:Oxamate significantly inhibited proliferation and induced apoptosis of Jurkat and DU528 cells.It also arrested Jurkat and DU528 cells in G0/G1 phase and stimulated ROS production(all P<0.001).Blocking LDHA significantly decreased the gene and protein expression of c-Myc,as well as the levels of phosphorylated serine/threonine kinase(AKT)and glycogen synthase kinase 3 beta(GSK-3β)in the phosphatidylinositol 3′-kinase(PI3K)signaling pathway.LDHA gene knockdown delayed disease progression and down-regulated c-Myc mRNA and protein expression in T-ALL transgenic zebrafish.Conclusion:Targeting LDHA exerted an antileukemic effect on T-ALL,representing a potential strategy for T-ALL treatment.

Macrophage Activation Syndrome in a Context of Pre-B Type Lymphoblastic Acute Leucemia: A Case Report

Macrophage activation syndrome (MAS) is linked to inappropriate stimulation of macrophage cells in the bone marrow and lymphoid system, resulting in abnormal phagocytosis of figurative blood elements and the release of pro-inflammatory cytokines. It is a rare and serious hyper-inflammatory condition of diagnostic and therapeutic emergency. MAS is characterized by non-specific clinical and laboratory signs associated with images of hemophagocytosis. MAS is either “primary” (familial or pediatric forms), or “secondary/reactive” to infection, neoplasia, or autoimmune disease. Hemopathies dominate MAS secondary to neoplasia. B-type acute lymphoblastic leukemia (ALL) is a hematological malignancy characterized by the proliferation and accumulation of B lymphoid progenitors, blocked at an early stage of differentiation, leading to suppression of polyclonal hematopoiesis and subsequent development of signs associated with bone marrow failure. In this context, we report the observation of a macrophage activation syndrome (MAS) associated with ALL, diagnosed at Hôpital Principal de Dakar/Senegal, in a 69-year-old patient with a well-controlled type 2 diabetes under oral antidiabetic therapy (OAD) and good general condition.

Donor-Derived CD19-Targeted T Cell Infusion Eliminates B Cell Acute Lymphoblastic Leukemia Minimal Residual Disease with No Response to Donor Lymphocytes after Allogeneic Hematopoietic Stem Cell Transplantation

Leukemia relapse is still the leading cause of treatment failure after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for B cell acute lymphoblastic leukemia (B-ALL). Relapsed patients with BALL after allo-HSCT have a very short median survival. Minimal residual disease (MRD) is predictive of forthcoming hematological relapse after hematopoietic stem cell transplantation (HSCT);furthermore, eliminating MRD effectively prevents relapse. Donor lymphoblastic infusion (DLI) is the main established approach to treat B-ALL with MRD after allo-HSCT. However, about one-third of patients with MRD are non-responsive to DLI and their prognosis worsens. Although donor-derived cluster of differentiation (CD)19-directed chimeric antigen receptor-modified (CAR) T cells (CART19s) can potentially cure leukemia, the efficiency and safety of infusions with these cells have not yet been investigated in patients with MRD after HSCT. Between September 2014 and February 2018, six patients each received one or more infusions of CART19s from HSCT donors. Five (83.33%) achieved MRD-negative remission, and one case was not responsive to the administration of CAR T cells. Three of the six patients are currently alive without leukemia. No patient developed acute graft-versus-host disease (aGVHD), and no patient died of cytokine release syndrome. Donor-derived CAR T cell infusions seem to be an effective and safe intervention for patients with MRD in B-ALL after allo-HSCT and for those who were not responsive to DLI.

Decitabine for Relapsed Acute Lymphoblastic Leukemia after Allogeneic Hematopoietic Stem Cell Transplantation

Relapse after allogeneic hematopoietic stem cell transplantation（allo-HSCT） remains a main question on treatment failure. Current strategies for management that usually include salvage chemotherapy, donor lymphocytic infusion and second transplantation. Our study assessed the efficacy of decitabine（DAC） for treating patients with acute lymphoblastic leukemia（ALL） who relapsed after allogeneic hematopoietic stem cell transplantation（allo-HSCT）. We retrospectively analyzed the outcomes of 12 patients with relapsed ALL after allo-HSCT who received DAC therapy. Nine patients received DAC combined with chemotherapy and donor stem cell infusion, and 3 patients received single-agent DAC. Ten of the 12 patients achieved complete remission（CR）, 1 achieved a partial remission（PR）, and 1 had no response（NR） after treatment at the latest follow-up（LFU）, the median survival was 11.2 months（range, 3.8–34, 7 months）. The 1-and 2-year overall survival（OS） rates were 50%（6/12） and 25%（3/12）, respectively. Five patients were still alive; 4 had maintained CR and 1 was alive with disease. Patients with Philadelphia chromosome-positive ALL had higher survival rate than patients with Philadelphia chromosome-negative ALL（57.1% vs. 20%）. No aggravated flares of graft-versus-host disease（GVHD） were observed during DAC treatment. Therefore, DAC may be a promising therapeutic agent for ALL recurrence after allo-HSCT.

Philadelphia chromosome-positive leukemia stem cells in acute lymphoblastic leukemia and tyrosine kinase inhibitor therapy

Leukemia stem cells(LSCs),which constitute a minority of the tumor bulk,are functionally defined on the basis of their ability to transfer leukemia into an immunodeficient recipient animal.The presence of LSCs has been demonstrated in acute lymphoblastic leukemia(ALL),of which ALL with Philadelphia chromosome-positive(Ph+).The use of imatinib,a tyrosine kinase inhibitor(TKI),as part of front-line treatment and in combination with cytotoxic agents,has greatly improved the proportions of complete response and molecular remission and the overall outcome in adults with newly diagnosed Ph+ ALL.New challenges have emerged with respect to induction of resistance to imatinib via Abelson tyrosine kinase mutations.An important recent addition to the arsenal against Ph+ leukemias in general was the development of novel TKIs,such as nilotinib and dasatinib.However,in vitro experiments have suggested that TKIs have an antiproliferative but not an antiapoptotic or cytotoxic effect on the most primitive ALL stem cells.None of the TKIs in clinical use target the LSC.Second generation TKI dasatinib has been shown to have a more profound effect on the stem cell compartment but the drug was still unable to kill the most primitive LSCs.Allogeneic stem cell transplantation(SCT) remains the only curative treatment available for these patients.Several mechanisms were proposed to explain the resistance of LSCs to TKIs in addition to mutations.Hence,TKIs may be used as a bridge to SCT rather than monotherapy or combination with standard chemotherapy.Better understanding the biology of Ph+ ALL will open new avenues for effective management.In this review,we highlight recent findings relating to the question of LSCs in Ph+ ALL.

Rapamycin Sensitizes Glucocorticoid Resistant Acute Lymphoblastic Leukemia CEM-C1 Cells to Dexamethasone Induced Apoptosis through both mTOR Suppression and Up-Regulation and Activation of Glucocorticoid Receptor

Objective To explore the role of glucocorticoid （GC） receptor （GR） in rapamycin＇s reversion of GC resistance in humanGC-resistant T-acute lymphoblastic leukemia （ALL） CEM-C1 cells. Methods CEM-C1 cells were cultured in vitro and treated with rapamycin at different concentrations with or without 1 μmol/L dexamethasone （Dex）. 3-（4, 5-dimethylthiazol-2-yl）-2, 5-diphenyltetrazolium bromide （MTT） test was performed to assess cell proliferation. The cell cycle and cell apoptosis were analyzed by flow cytometry. The expression of GRα mRNA was determined by real-time quantitative RT-PCR. The expression of GR, p-70S6K, Mcl-1, and Bim proteins was detected by Western blot. Results When incubated with rapamycin at different concentrations, CEM-C1 cells showed significant growth inhibition in a time- and concentration-dependent manner. The growth inhibition was synergistically increased when CEM-C1 cells were treated with rapamycin plus 1 μmol/L Dex. CEM-C1 cells treated with rapamycin alone showed no apparent apoptosis, and were arrested at G0/G1 phase. After the treatment with Dex plus rapamycin, CEM-C1 cells demonstrated apparent apoptosis and increased the cell cycle arrested at G0/G1 phase. Rapamycin combined with Dex up-regulated GRα, phosphorylated GR（p-GR）, and pro-apoptotic protein Bim-EL in CEM-C1 cells, but inhibited the expression of p-p70S6K, a downstream target protein ofmTOR （mammalian target of rapamycin）. Conclusion After the treatment with rapamycin plus Dex, Dex resistant CEM-C1 cells induce growth inhibition and apoptosis. The underlying mechanism may involve inhibition of the mTOR signaling pathway and also be associated with up-regulation of GR expression and activation of GC-GR signaling pathway.

Individualized leukemia cell-population profiles in common B-cell acute lymphoblastic leukemia patients

Immunophenotype is critical for diagnosing common B-cell acute lymphoblastic leukemia (common ALL) and detecting minimal residual disease. We developed a protocol to explore the immunophenotypic profiles of common ALL based on the expression levels of the antigens associated with B lymphoid development, including IL-7Rα (CD127), cytoplasmic CD79a (cCD79a), CD19, VpreB (CD179a), and sIgM, which are successive and essential for progression of B cells along their developmental pathway. Analysis of the immunophenotypes of 48 common ALL cases showed that the immunophenotypic patterns were highly heterogeneous, with the leukemic cell population differing from case to case. Through the comprehensive analysis of immunophenotypic patterns, the profiles of patient-specific composite leukemia cell populations could provide detailed information helpful for the diagnosis, therapeutic monitoring, and individualized therapies for common ALL.

DNA repair gene XRCC1 polymorphisms and susceptibility to childhood acute lymphoblastic leukemia: a meta-analysis

Objective： To estimate the relationship between genetic polymorphisms of X-ray repair cross- complementing group 1 （XRCC1） and the susceptibility to childhood acute lymphoblastic leukemia （ALL）. Methods： Relevant case-control studies were enrolled in the meta-analysis. We applied Rev Man 4.2 software to pool raw data and test studies＇ heterogeneity and to calculate the incorporated odds ratio （OR） and 95% confidence interval （95% CI）. Results： Our data showed that the OR for the Gln allele of the Arg399Gln polymorphism, compared with the Arg allele, was 1.35 （95% CI, 1.16-1.57; P〈0.0001） for childhood ALL patients. Similarly, the homozygous genotype Gln/Gln and heterozygous genotype Arg/Gln both significantly increased the risk of childhood ALL compared with the wild genotype Arg/Arg （OR =1.58; 95% CI, 1.13-2.21; P=0.008; OR =1.51; 95% CI, 1.21-1.87; P=0.0002）. The dominant model of Arg399Gln was associated with childhood ALL risk （OR =1.54; 95% CI, 1.25-1.89; P〈0.0001）. The ethnic subgroup analysis demonstrated that the Gln allele in all five ethnic groups was prone to be a risk factor for childhood ALL just with different degrees of correlation while Arg194Trp SNP showed a protective or risk factor or irrelevant thing in different races. Conclusions： XRCC1 399 polymorphism may increase the risk of childhood ALL. Different ethnic groups with some gene polymorphism have different disease risks.