Identification and Effects of Novel Promoter Region Haplotypes in the Human Equilibrative Nucleoside Transporter, hENT1.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2083-2083
Author(s):  
Scott N. Myers ◽  
Rakesh K. Goyal ◽  
Jennifer D. Roy ◽  
Robert E. Ferrell
Keyword(s):  
De Novo ◽  
Remission Rate ◽  
Leukemic Cells ◽  
Luciferase Reporter ◽  
Luciferase Expression ◽  
Nucleoside Transporter ◽  
Nucleotide Polymorphisms ◽  
Flanking Sequence ◽  
Equilibrative Nucleoside Transporter

Abstract Front-line induction chemotherapy regimens containing cytosine arabinoside (Ara-C) and anthracyclines result in 80% complete remission rate in childhood acute myeloid leukemia (AML) but their cure rate is about 35 – 50%, one of the lowest of all childhood cancers. Understanding the factors that contribute to emergence of chemoresistant leukemic cells is crucial to improving treatment outcome in children with AML. We are interested in studying the role of variation in Ara-C transport and biotransformation pathway genes in the efficacy and toxicity of treatment of childhood AML. To permeate the cell membrane, Ara-C is mainly dependent on human equilibrative nucleoside transporter 1 (hENT1; SLC29A1; gene localized to 6p21.1). Several studies have suggested an important role for altered levels of hENT1 in the chemosensitivity of AML blasts to Ara-C (Galmarini et al. Leukemia2001; 15(6):87; Gati et al. Leuk Lymphoma1998; 32(1–2):45). Osato and colleagues identified two single nucleotide polymorphisms (SNPs) in the hENT1 coding sequence that led to missense changes, but their in vitro analysis did not detect differences in the activity of variant alleles in a yeast transfection system (Osato et al. Pharmacogenetics2003;13(5):297). To identify variation in hENT1 that might influence its expression, we sequenced 1.6Kb of the proximal 5′-flanking sequence of the gene in 42 unrelated individuals and identified three SNPs at positions C-1345G, G-1050A, and G-706C. TRANSFAC analysis (www.genomatix.de) predicted that two of these (C-1345G & G-706C) would alter consensus transcription factor binding site sequences. We cloned four naturally occurring haplotypes (CGG, CAG, CGC, and GAG) using the TOPO-TA cloning kit, then transfected Cos-1 cells using the Lipofectamine 2000 protocol. Gene expression was assayed using the Promega Dual-Luciferase Reporter Assay System and read on a Molecular Devices HT Analyzer. Luciferase activity was measured at 24 and 48 hours after transfection for six replicates of every condition during three separate transfections. To correct for differences in transfection efficiencies, experimental (Photinus pyralis) luciferase activities were normalized by co-transfection with control (Renilla reniformis) luciferase plasmid. Compared to the wild type CGG haplotype, variant haplotypes CAG, CGC, and GAG drive luciferase expression at approximately 2x (p <0.0001), 1.4x (p <0.001) and 1.2x (p =0.08), respectively. This leads to the hypothesis that individuals carrying CAG or CGC haplotypes (17% of the population) exhibit higher levels of hENT1 expression and are more sensitive to Ara-C exposure. Experiments are underway to quantify gene transcripts in people of known hENT1 haplotypes. We also plan to genotype a large cohort of children with de novo AML for these three SNPs in hENT1 and correlate clinical outcomes in individuals carrying the low- versus the high-expressing haplotypes.

Identification and Effects of Novel Promoter Region Haplotypes in the Human Cytidine Deaminase Gene.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2080-2080
Author(s):  
Sara M. Fitzgerald ◽  
Rakesh K. Goyal ◽  
Jennifer D. Roy ◽  
John Wilson ◽  
Robert E. Ferrell
Keyword(s):  
De Novo ◽  
Remission Rate ◽  
Cytidine Deaminase ◽  
Leukemic Cells ◽  
European Ancestry ◽  
Expression Vectors ◽  
Luciferase Reporter ◽  
Upstream Region ◽  
Luciferase Expression ◽  
Nucleotide Polymorphisms

Abstract Front-line induction chemotherapy regimens containing cytosine arabinoside (Ara-C) and anthracyclines result in 80% complete remission rate in childhood acute myeloid leukemia (AML) but their cure rate is about 35 – 50%, one of the lowest of all childhood cancers. Understanding the factors that contribute to emergence of chemoresistant leukemic cells are crucial to improving treatment outcomes. We are interested in studying the role of genetic variation in Ara-C transport and biotransformation pathway genes in the efficacy and toxicity of treatment of childhood AML. Human cytidine deaminase (CDA; EC 3.5.4.5; gene localized to 1p35– 36.2) is a salvage pathway enzyme that irreversibly catalyzes the hydrolytic deamination of Ara-C and Ara-CMP to inactive uracil nucleosides. Several studies have suggested an important role for increased levels of CDA in the development of resistance to Ara-C. Yue and colleagues identified three single nucleotide polymorphisms (SNP) in the CDA gene, one of which (G208A) leads to an alanine to threonine change at codon 70 (A70T) (Yue et al, Pharmacogenetics2003; 13(1):29–38). They showed that the 70T allele had 40% activity with cytidine as substrate and only 32% activity toward Ara-C as the 70A allele. These results suggest that variation in the CDA gene might contribute to Ara-C sensitivity. This variant, while common in Japanese, was not observed by us in a panel of primarily Caucasians of mixed-European ancestry. We sequenced 1.6 Kb of the 5′-upstream region of CDA in 24 laboratory control samples and identified six SNPs (A-92G, C-205G , C-451T, C-897A, A-1138G, G-1172A). TRANSFAC matrix (www.genomatix.de) predicted that three of these, (A-92G, C-451T, and C-897A) would alter consensus transcription factor binding site sequences. We cloned the five naturally occurring haplotypes (ACC, GTC, ATC, ACA and GCC) using the TOPO-TA cloning kit, subcloned into luciferase expression vectors and then transfected Cos-1 cells using the Lipofectamine 2000 protocol. Gene expression was assayed using the Promega Dual-Luciferase Reporter Assay System and read on a Molecular Devices HT Analyzer. Luciferase activity was measured 24 and 48 hours after transfection for six replicates of every condition during two separate transfections. To correct for differences in transfection efficiencies, experimental (Photinus pyralis) luciferase activities were normalized by co-transfection with control (Renilla reniformis) luciferase plasmid. We observed that haplotype combinations ACC, GTC, ACA and GCC drive luciferase expression at approximately 3x that of ATC haplotype (p <0.0001) at 24 hours (2.5x) and this difference persists at 48 hours (3.3x). When reanalyzed as single SNP genotypes, most of the differences in expression were significant, but the magnitude of difference was reduced, suggesting that no single SNP accounts for the expression differences observed at the haplotype level. This leads to the hypothesis that individuals carrying the ATC haplotype (13% of the population; derived from the testing of 94 alleles) would exhibit lower levels of CDA expression and are more sensitive to Ara-C exposure. Experiments are underway to quantify CDA transcription in people of known CDA haplotypes. We also plan to genotype a large cohort of children with de novo AML for these three SNPs and correlate clinical outcomes in individuals carrying the low- versus the high-expressing haplotypes.

Implications On Drug Resistance and Survival of ABCB1 Single Nucleotide Polymorphisms in Normal Karyotype De Novo AML.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2648-2648
Author(s):  
Christer Paul ◽  
Henrik Green ◽  
Ingrid Jakobsen Falk ◽  
Kourosh Lotfi ◽  
Esbjorn Paul ◽  
...  
Keyword(s):  
Drug Sensitivity ◽  
De Novo ◽  
Normal Karyotype ◽  
University Hospital ◽  
Leukemic Cells ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
The Mean ◽  
De Novo Aml

Abstract Abstract 2648 Poster Board II-624 Background: Multidrug resistance and expression of the ATP-dependent drug transporting protein ABCB1 is a clinically relevant problem in the treatment of acute myeloid leukaemia. Several single nucleotide polymorphisms (SNPs) in the ABCB1 have been associated with altered P-glycoprotein expression and phenotype. These SNPs might influence the clinical outcome in AML and predict individual differences in response to therapy with ABCB1 substrates. Aims: To investigate the impact of the ABCB1 SNPs in exon 11, 12, 21 and 26 on treatment response, survival and in vitro drug sensitivity in AML patients. Methods: PCR and Pyrosequencing were used to determine the genotype of the SNPs G1199T/A, C1236T, A1308G, G2677T/A and C3435T in 100 de novo AML patients with normal karyotype treated at Linköping University Hospital or Karolinska University Hospital. Almost all patients were treated with one anthracycline and Ara-C during the induction regime. The affect of the genetic variants in ABCB1 on survival were analysed by Kaplan-Meier Log-rank tests and multivariant analysis by Cox regression. Patients receiving transplantation were censored at that point in the analysis. A Nordic reference material of 400 healthy volunteers of equal age and sex distribution was also included. NPM1 and FLT3-ITD mutations were determined by PCR. Leukemic cells were isolated and drug sensitivity was measured after 4 days culturing by a bioluminescence ATP-assay. Results: The survival of the AML patients was significantly correlated to the ABCB1 genotypes C1236T (P=0.02) and G2677T (P=0.02), with a borderline significance for G1199A (p=0.06). For the C1236T SNP the mean survival was 0.7, 1.3 and 1.8 years for the wild type, heterozygous and homozygous variants, respectively. The mean survival for patients with G/G, G/T and T/T genotype of SNP G2677T/A was 0.7, 1.2 and 1.7 years, respectively. Only the wild type of A1308T was found in the material and C3435T did not correlate to survival. Multivariate analysis showed that 1236T/T and 2677T/T were independent factors for survival (hazard ratio 0.24 and 0.22). Comparison of allele frequencies between AML patients and healthy volunteers showed no significant difference. In vitro testing showed that leukemic cells from patients carrying 1236T/T or 2677T/T were significantly more susceptible for mitoxantrone and borderline susceptible to daunorubicine and etoposide, substrates for Pgp but not to Ara-C. Conclusions: Our findings suggest that ABCB1 SNPs do not affect the development of the disease but the survival after chemotherapy possibly by impact on drug sensitivity. The correlation between ABCB1 genotype and the overall survival of AML patients might provide useful information for treatment strategies and individualized chemotherapy. Disclosures: Paul: Aprea AB: Consultancy, Research Funding.

scholarly journals MicroRNA-98 reduces nerve growth factor expression in nicotine-induced airway remodeling

2020 ◽  
Vol 295 (52) ◽  
pp. 18051-18064
Author(s):  
Cherry Wongtrakool ◽  
Junsuk Ko ◽  
Andrew J. Jang ◽  
Kora Grooms ◽  
Sarah Chang ◽  
...  
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Airway Remodeling ◽  
Luciferase Reporter ◽  
Mouse Lung ◽  
Luciferase Expression ◽  
Nerve Growth ◽  
Pparγ Agonist

Evolving evidence suggests that nicotine may contribute to impaired asthma control by stimulating expression of nerve growth factor (NGF), a neurotrophin associated with airway remodeling and airway hyperresponsiveness. We explored the hypothesis that nicotine increases NGF by reducing lung fibroblast (LF) microRNA-98 (miR-98) and PPARγ levels, thus promoting airway remodeling. Levels of NGF, miR-98, PPARγ, fibronectin 1 (FN1), endothelin-1 (EDN1, herein referred to as ET-1), and collagen (COL1A1 and COL3A1) were measured in human LFs isolated from smoking donors, in mouse primary LFs exposed to nicotine (50 μg/ml), and in whole lung homogenates from mice chronically exposed to nicotine (100 μg/ml) in the drinking water. In selected studies, these pathways were manipulated in LFs with miR-98 inhibitor (anti-miR-98), miR-98 overexpression (miR-98 mimic), or the PPARγ agonist rosiglitazone. Compared with unexposed controls, nicotine increased NGF, FN1, ET-1, COL1A1, and COL3A1 expression in human and mouse LFs and mouse lung homogenates. In contrast, nicotine reduced miR-98 levels in LFs in vitro and in lung homogenates in vivo. Treatment with anti-miR-98 alone was sufficient to recapitulate increases in NGF, FN1, and ET-1, whereas treatment with a miR-98 mimic significantly suppressed luciferase expression in cells transfected with a luciferase reporter linked to the putative seed sequence in the NGF 3′UTR and also abrogated nicotine-induced increases in NGF, FN1, and ET-1 in LFs. Similarly, rosiglitazone increased miR-98 and reversed nicotine-induced increases in NGF, FN1, and ET-1. Taken together, these findings demonstrate that nicotine-induced increases in NGF and other markers of airway remodeling are negatively regulated by miR-98.

scholarly journals HIF-1–dependent repression of equilibrative nucleoside transporter (ENT) in hypoxia

2005 ◽  
Vol 202 (11) ◽  
pp. 1493-1505 ◽  
Author(s):  
Holger K. Eltzschig ◽  
Parween Abdulla ◽  
Edgar Hoffman ◽  
Kathryn E. Hamilton ◽  
Dionne Daniels ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Molecular Mechanisms ◽  
Hypoxia Inducible Factor ◽  
Nucleoside Transporter ◽  
In Vivo Models ◽  
Equilibrative Nucleoside Transporter ◽  
Hypoxia Inducible Factor 1 ◽  
And Function

Extracellular adenosine (Ado) has been implicated as central signaling molecule during conditions of limited oxygen availability (hypoxia), regulating physiologic outcomes as diverse as vascular leak, leukocyte activation, and accumulation. Presently, the molecular mechanisms that elevate extracellular Ado during hypoxia are unclear. In the present study, we pursued the hypothesis that diminished uptake of Ado effectively enhances extracellular Ado signaling. Initial studies indicated that the half-life of Ado was increased by as much as fivefold after exposure of endothelia to hypoxia. Examination of expressional levels of the equilibrative nucleoside transporter (ENT)1 and ENT2 revealed a transcriptionally dependent decrease in mRNA, protein, and function in endothelia and epithelia. Examination of the ENT1 promoter identified a hypoxia inducible factor 1 (HIF-1)–dependent repression of ENT1 during hypoxia. Using in vitro and in vivo models of Ado signaling, we revealed that decreased Ado uptake promotes vascular barrier and dampens neutrophil tissue accumulation during hypoxia. Moreover, epithelial Hif1α mutant animals displayed increased epithelial ENT1 expression. Together, these results identify transcriptional repression of ENT as an innate mechanism to elevate extracellular Ado during hypoxia.

scholarly journals Somatic Mutations in Oncogenes Are in Chronic Myeloid Leukemia Acquired De Novo via Deregulated Base-Excision Repair and Alternative Non-Homologous End Joining

2021 ◽  
Vol 11 ◽  
Author(s):  
Nikola Curik ◽  
Vaclava Polivkova ◽  
Pavel Burda ◽  
Jitka Koblihova ◽  
Adam Laznicka ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Base Excision Repair ◽  
Myeloid Leukemia ◽  
Somatic Mutations ◽  
De Novo ◽  
Excision Repair ◽  
Leukemic Cells ◽  
End Joining ◽  
Base Excision

Somatic mutations are a common molecular mechanism through which chronic myeloid leukemia (CML) cells acquire resistance to tyrosine kinase inhibitors (TKIs) therapy. While most of the mutations in the kinase domain of BCR-ABL1 can be successfully managed, the recurrent somatic mutations in other genes may be therapeutically challenging. Despite the major clinical relevance of mutation-associated resistance in CML, the mechanisms underlying mutation acquisition in TKI-treated leukemic cells are not well understood. This work demonstrated de novo acquisition of mutations on isolated single-cell sorted CML clones growing in the presence of imatinib. The acquisition of mutations was associated with the significantly increased expression of the LIG1 and PARP1 genes involved in the error-prone alternative nonhomologous end-joining pathway, leading to genomic instability, and increased expression of the UNG, FEN and POLD3 genes involved in the base-excision repair (long patch) pathway, allowing point mutagenesis. This work showed in vitro and in vivo that de novo acquisition of resistance-associated mutations in oncogenes is the prevalent method of somatic mutation development in CML under TKIs treatment.

scholarly journals Heat Shock Factor 1 (HSF1-pSer326) Predicts Response to Bortezomib-Containing Chemotherapy in Pediatric AML: A COG Study

Blood ◽  
2020 ◽  
Author(s):  
Fieke W Hoff ◽  
Anneke D van Dijk ◽  
Yi Hua Qiu ◽  
Peter P Ruvolo ◽  
Robert B Gerbing ◽  
...  
Keyword(s):  
Heat Shock ◽  
De Novo ◽  
Heat Shock Factor ◽  
Leukemic Cells ◽  
Heat Shock Factor 1 ◽  
Free Survival ◽  
Heat Shock Responses ◽  
Pediatric Aml ◽  
Hsf1 Gene

Bortezomib (BTZ) was recently evaluated in a randomized Phase 3 clinical trial which compared standard chemotherapy (cytarabine, daunorubicin, etoposide; ADE) to standard therapy with BTZ (ADEB) for de novo pediatric acute myeloid leukemia. While the study concluded that BTZ did not improve outcome overall, we examined patient subgroups benefitting from BTZ-containing chemotherapy using proteomic analyses. The proteasome inhibitor BTZ disrupts protein homeostasis and activates cytoprotective heat shock responses. We measured total heat shock factor 1 (HSF1) and phosphorylated HSF1 (HSF1-pSer326) in leukemic cells from 483 pediatric patients using Reverse Phase Protein Arrays. HSF1-pSer326 phosphorylation was significantly lower in pediatric AML compared to CD34+ non-malignant cells. We identified a strong correlation between HSF1-pSer326 expression and BTZ sensitivity. BTZ significantly improved outcome of patients with low-HSF1-pSer326 with a 5-year event-free survival of 44% (ADE) vs. 67% for low-HSF1-pSer326 treated with ADEB (P=0.019). To determine the effect of HSF1 expression on BTZ potency in vitro, cell viability with HSF1 gene variants that mimicked phosphorylated (S326A) and non-phosphorylated (S326E) HSF1-pSer326 were examined. Those with increased HSF1 phosphorylation showed clear resistance to BTZ vs. those with wild type or reduced HSF1-phosphorylation. We hypothesize that HSF1-pSer326 expression could identify patients that benefit from BTZ-containing chemotherapy.

L-arginine depletion by PEG-arginase I, a new potential therapy for acute lymphoblastic leukemia.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 6580-6580
Author(s):  
Ofelia Crombet Ramos ◽  
Claudia Hernandez ◽  
Kevin Morrow ◽  
John T. Cole ◽  
Paulo Rodriguez
Keyword(s):  
Cell Proliferation ◽  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
De Novo ◽  
Remission Rate ◽  
Lymphoblastic Leukemia ◽  
Arginase I

6580 Background: Advances in therapies have resulted in an overall complete remission rate of approximately 85% for childhood acute lymphoblastic leukemia (ALL). In contrast, the overall remission rate of adults with leukemia continues to be poor, only about 40% in cases of T cell-ALL (T-ALL). Therefore, it is imperative to generate new therapies that alone or in combination with other treatments could potentially increase the percentages of complete responders or be used to treat the refractory ALL population. Our published results show that a pegylated form of human arginase I (peg-Arg I) prevented T-ALL cell proliferation in vitro and in vivo through the induction of tumor cell apoptosis. Interestingly, the anti-leukemic effects induced by peg-Arg I did not affect the anti-tumor activity of normal T cells, suggesting an anti-tumor specific effect. Our hypothesis states that peg-Arg I has an anti-tumoral effect on B-ALL and T-ALL cells in vitro and that the sensitivity of ALL cells to peg-Arg I depends on their expression of argininosuccinate synthase (ASS) and their ability to produce L-arginine de novo from citrulline. Methods: Malignant T cell proliferation was tested using nonradioactive cell proliferation yellow tretrazolium salt kit. Apoptosis studies were based on the expression of annexin V. Western blot assays were conducted to determine enzymatic expression in different cell lines. Results: The results of our in vitro experiments showed that peg-Arg I had a pro-apoptotic and anti-proliferattive effect on B-ALL cells similar to the one previously seen on T-ALL cells. These effects can be overcome in cell lines able that express ASS and therefore to produce L-arginine de novo. Conclusions: Our results suggest the role of ASS in the ALL-apoptosis induced by peg-Arg-I. Our next steps include: _Understand why ASS-expressing ALL cells do not undergo apoptosis when cultured with peg-Arg-I_Determine the role of ASS in the anti-leukemic effect induced by peg-Arg-I in vivo. Completion of this research is expected to lead to a better understanding of how peg-Arg-I kills ALL cells and could provide the foundation for a novel therapy for ALL patients.

Relationship among ETV1 genetic polymorphisms, PFS, and microRNA in gastrointestinal stromal tumors.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e22513-e22513
Author(s):  
Haibo Qiu ◽  
Wei Zhuang ◽  
Xiaojun Zhou ◽  
Xueding Wang ◽  
Zhiwei Zhou ◽  
...  
Keyword(s):  
Genetic Polymorphisms ◽  
Germline Mutation ◽  
Tumor Size ◽  
Cox Regression ◽  
Luciferase Reporter ◽  
Cancer Center ◽  
Nucleotide Polymorphisms ◽  
Reporter System ◽  
Therapy Strategy

e22513 Background: In order to evaluate the pharmacokinetic and pharmacogenomic determinants for prognosis of gastrointestinal stromal tumor (GIST). It is necessary to explore a biological predictors to predict and optimal therapeutic strategy. But there were few studied conducted to explore the germline mutation and its mechanisms. Methods: A total of 75 GIST patients treated with Imatinib were enrolled. 35 SNPs (single nucleotide polymorphisms) in KIT/ PDGFRA/ PDGFRB/ ETV1/ FLT1/ MAPK1 et. al were detected using Agena Massarray matrix-assisted laser desorption / ionization-time of flight (MALDI-TOF) platform. COX regression analyses were performed to evaluate the key factors of PFS. The luciferase reporter system of rs3735343 wild type and mutation were established. The GIST-T1 cell line was used to evaluate the biology effect of rs3735343. This study was approved by the ethical committee of Sun Yat-Sen University Cancer Center. Results: Several factors influence the PFS, including KIT somatic mutation, tumor size and germline mutation ABCC4 rs4148551, ETV1 rs3735343, FLT1 rs3751397, KIT rs3822214. And COX regression showed that rs3735343 and tumor size are associated with PFS (P = 0.009 and 0.032, Risk Ratio = 8.995 and 4.173). And we found that rs3735343 mutation type can regulate ETV1 3’UTR and protein expression level through miR-4311 in vitro. Conclusions: The primary determinants of PFS in this somatic and germline mutation model suggested new biomarkers and different mechanisms involved in prognosis. This is the first report showed that ETV1 genetic polymorphisms may influence the prognosis through miRNA-4311. Targeting ETV1, miRNA-4311 or their relative pathway might be a new therapy strategy.

In Vivo Eradication of Human Clonigenic Acute Lymphoblastic Leukemic Cells Expressing the Wilms Tumor Protein, WT-1, by HLA Restricted WT-1 Specific T-Cells in NOD/SCID Mice Monitored by Bioluminescent Imaging.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 581-581
Author(s):  
Ekaterina Doubrovina ◽  
Mikhail Doubrovin ◽  
Elena Kanaeva ◽  
Richard J. O’Reilly
Keyword(s):  
T Cells ◽  
Wilms Tumor ◽  
Scid Mice ◽  
Leukemic Cells ◽  
Luciferase Reporter ◽  
Bioluminescent Imaging ◽  
Acute Leukemias ◽  
Post Infusion

Abstract WT-1 is expressed in 60–80% of acute leukemias, CML and high risk forms of MDS. Its expression has been hypothesized to be critical to the growth or survival of leukemic stem cells. Previously, alloreactive HLAA0201− T-cells recognizing a complex of WT-1 peptide and HLA A0201 were reported to prevent growth of leukemic HLA A0201+ CD34+ Ph+CML progenitor cells in NOD/ SCID mice (Transplantation, vol 75, No9, 2003). In this study, we have assessed the capacity of HLA-restricted, WT-1 peptide specific CTL (WT1-CTL) lacking alloreactivity to prevent the outgrowth of a human acute preB-lymphocytic leukemia (B-ALL)in NOD/SCID mice. This leukemia contained 65% of the blasts expressed WT-1 as determined by FACS analysis. For these studies the leukemic cells were transduced to express a luciferase reporter gene, permitting sequential monitoring of growth in vivo by bioluminescent imaging. WT-1 specific T-cells were generated from normal HLA A0201+ donor PBMC by in vitro sensitization with autologous dendritic cells loaded with the immunogenic HLA A0201 binding WT-1 peptide, RMFPNAPYL, and shown to be selectively cytotoxic against HLA A0201+WT-1+ leukemias and peptide loaded PHA blasts. T-cells from the same donor sensitized with autologous EBV BLCL and exhibiting HLA A0201 restricted EBV-specific cytotoxic activity served as controls. WT-1-CTL or EBV CTL were co-incubated in vitro with the WT-1+ HLA A0201+ BALL-LUC at a 4:1 effector target ratio for 7 hours at 37°C. Thereafter, separate groups of 5 NOD/SCID mice received intravenous infusions of cells from each of the co-cultures, at doses providing 12 × 106 WT1 CTL or EBVCTL and 3 × 106 BALL-LUC cells/mouse. A third group received 3×106 BALL-LUC alone. Leukemia growth was monitored at 2–3 day intervals from day 1–45 post infusion. In all 3 groups, BALL-LUC could be detected in the thorax by imaging at day 1. In mice treated with BALL-LUC alone or together with EBV-CTL, signal accumulation in the thorax increased steadily through 45 days of observation. By day 17, BALL-LUC were also detected throughout the head, abdomen and pelvis, and thereafter also increased until sacrifice at day 45. Autopsy confirmed presence of leukemic nodules in the lung and leukemic cells in blood, spleen and marrow as well as other organs. In contrast, in mice treated with WT1-CTL+ BALL LUC, signal intensity in lung decreased by day 4. In 4/5 of these mice, BALL-LUC could not be detected thereafter. In one mouse from this group, BALL-LUC were first detected in the head 31 days post infusion. At autopsy on day 45, this mouse had detectable BALL in the skull but in no other sites. WT-1 expression of residual leukemic cells is being analyzed. The other mice treated with WT-1 CTL had no detectable residual disease. These results suggest that clonogenic BALL cells express WT-1 and are susceptible to eradication in vivo by WT-1 peptide specific cytotoxic T-cells. The elimination of such clonogenic leukemic cells is sufficient to prevent subsequent development of leukemia.

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