Publications (30)335.42 Total impact
-
Article: Activating mutations in the NT5C2 nucleotidase gene drive chemotherapy resistance in relapsed ALL
[show abstract] [hide abstract]
ABSTRACT: 10.1038/nm.3078Nature medicine 02/2013; advance online publication. · 27.14 Impact Factor -
Article: Activating mutations in the NT5C2 nucleotidase gene drive chemotherapy resistance in relapsed ALL.
[show abstract] [hide abstract]
ABSTRACT: Acute lymphoblastic leukemia (ALL) is an aggressive hematological tumor resulting from the malignant transformation of lymphoid progenitors. Despite intensive chemotherapy, 20% of pediatric patients and over 50% of adult patients with ALL do not achieve a complete remission or relapse after intensified chemotherapy, making disease relapse and resistance to therapy the most substantial challenge in the treatment of this disease. Using whole-exome sequencing, we identify mutations in the cytosolic 5'-nucleotidase II gene (NT5C2), which encodes a 5'-nucleotidase enzyme that is responsible for the inactivation of nucleoside-analog chemotherapy drugs, in 20/103 (19%) relapse T cell ALLs and 1/35 (3%) relapse B-precursor ALLs. NT5C2 mutant proteins show increased nucleotidase activity in vitro and conferred resistance to chemotherapy with 6-mercaptopurine and 6-thioguanine when expressed in ALL lymphoblasts. These results support a prominent role for activating mutations in NT5C2 and increased nucleoside-analog metabolism in disease progression and chemotherapy resistance in ALL.Nature medicine 02/2013; · 27.14 Impact Factor -
Article: Targeting nonclassical oncogenes for therapy in T-ALL.
[show abstract] [hide abstract]
ABSTRACT: Constitutive phosphoinositide 3-kinase (PI3K)/Akt activation is common in T cell acute lymphoblastic leukemia (T-ALL). Although four distinct class I PI3K isoforms (α, β, γ, δ) could participate in T-ALL pathogenesis, none has been implicated in this process. We report that in the absence of PTEN phosphatase tumor suppressor function, PI3Kγ or PI3Kδ alone can support leukemogenesis, whereas inactivation of both isoforms suppressed tumor formation. The reliance of PTEN null T-ALL on the combined activities of PI3Kγ/δ was further demonstrated by the ability of a dual inhibitor to reduce disease burden and prolong survival in mice as well as prevent proliferation and promote activation of proapoptotic pathways in human tumors. These results support combined inhibition of PI3Kγ/δ as therapy for T-ALL.Cancer cell 04/2012; 21(4):459-72. · 25.29 Impact Factor -
Article: Targeting Nonclassical Oncogenes for Therapy in T-ALL
Cancer Cell 04/2012; 21(4):459–472. · 26.57 Impact Factor -
Article: ETV6 mutations in early immature human T cell leukemias.
[show abstract] [hide abstract]
ABSTRACT: Early immature T cell acute lymphoblastic leukemias (T-ALLs) account for ~5-10% of pediatric T-ALLs and are associated with poor prognosis. However, the genetic defects that drive the biology of these tumors remain largely unknown. In this study, analysis of microarray gene expression signatures in adult T-ALL demonstrated a high prevalence of early immature leukemias and revealed a close relationship between these tumors and myeloid leukemias. Many adult immature T-ALLs harbored mutations in myeloid-specific oncogenes and tumor suppressors including IDH1, IDH2, DNMT3A, FLT3, and NRAS. Moreover, we identified ETV6 mutations as a novel genetic lesion uniquely present in immature adult T-ALL. Our results demonstrate that early immature adult T-ALL represents a heterogeneous category of leukemias characterized by the presence of overlapping myeloid and T-ALL characteristics, and highlight the potential role of ETV6 mutations in these tumors.Journal of Experimental Medicine 12/2011; 208(13):2571-9. · 13.85 Impact Factor -
Article: The TLX1 oncogene drives aneuploidy in T cell transformation.
[show abstract] [hide abstract]
ABSTRACT: The TLX1 oncogene (encoding the transcription factor T cell leukemia homeobox protein-1) has a major role in the pathogenesis of T cell acute lymphoblastic leukemia (T-ALL). However, the specific mechanisms of T cell transformation downstream of TLX1 remain to be elucidated. Here we show that transgenic expression of human TLX1 in mice induces T-ALL with frequent deletions and mutations in Bcl11b (encoding B cell leukemia/lymphoma-11B) and identify the presence of recurrent mutations and deletions in BCL11B in 16% of human T-ALLs. Most notably, mouse TLX1 tumors were typically aneuploid and showed a marked defect in the activation of the mitotic checkpoint. Mechanistically, TLX1 directly downregulates the expression of CHEK1 (encoding CHK1 checkpoint homolog) and additional mitotic control genes and induces loss of the mitotic checkpoint in nontransformed preleukemic thymocytes. These results identify a previously unrecognized mechanism contributing to chromosomal missegregation and aneuploidy active at the earliest stages of tumor development in the pathogenesis of cancer.Nature medicine 10/2010; 16(11):1321-7. · 27.14 Impact Factor -
Article: Absence of biallelic TCRgamma deletion predicts early treatment failure in pediatric T-cell acute lymphoblastic leukemia.
[show abstract] [hide abstract]
ABSTRACT: To identify children with T-cell acute lymphoblastic leukemia (T-ALL) at high risk of induction chemotherapy failure by using DNA copy number analysis of leukemic cells collected at diagnosis. Array comparative genomic hybridization (CGH) was performed on genomic DNA extracted from diagnostic lymphoblasts from 47 children with T-ALL treated on Children's Oncology Group Study P9404 or Dana-Farber Cancer Institute Protocol 00-01. These samples represented nine patients who did not achieve an initial complete remission, 13 who relapsed, and 25 who became long-term, event-free survivors. The findings were confirmed in an independent cohort of patients by quantitative DNA polymerase chain reaction (DNA-PCR), an assay that is well suited for clinical application. Analysis of the CGH findings in patients in whom induction chemotherapy failed compared with those in whom induction chemotherapy was successful identified the absence of biallelic TCRgamma locus deletion (ABD), a characteristic of early thymocyte precursors before V(D)J recombination, as the most robust predictor of induction failure (P < .001). This feature was also associated with markedly inferior event-free (P = .002) and overall survival (P < .001) rates: 25% versus 58% and 25% versus 72%, respectively. Using a rapid and inexpensive quantitative DNA-PCR assay, we validated ABD as a predictor of a poor response to induction chemotherapy in an independent series of patients. Lymphoblasts from children with T-ALL should be evaluated at diagnosis for deletion within the TCRgamma locus. Patients lacking biallelic deletion, which confers a high probability of induction failure with contemporary therapy, should be assigned to alternative therapy in the context of a prospective clinical trial.Journal of Clinical Oncology 08/2010; 28(24):3816-23. · 18.37 Impact Factor -
Article: WT1 mutations in T-ALL.
[show abstract] [hide abstract]
ABSTRACT: The molecular mechanisms involved in disease progression and relapse in T-cell acute lymphoblastic leukemia (T-ALL) are poorly understood. We used single nucleotide polymorphism array analysis to analyze paired diagnostic and relapsed T-ALL samples to identify recurrent genetic alterations in T-ALL. This analysis showed that diagnosis and relapsed cases have common genetic alterations, but also that relapsed samples frequently lose chromosomal markers present at diagnosis, suggesting that relapsed T-ALL emerges from an ancestral clone different from the major leukemic population at diagnosis. In addition, we identified deletions and associated mutations in the WT1 tumor suppressor gene in 2 of 9 samples. Subsequent analysis showed WT1 mutations in 28 of 211 (13.2%) of pediatric and 10 of 85 (11.7%) of adult T-ALL cases. WT1 mutations present in T-ALL are predominantly heterozygous frameshift mutations resulting in truncation of the C-terminal zinc finger domains of this transcription factor. WT1 mutations are most prominently found in T-ALL cases with aberrant rearrangements of the oncogenic TLX1, TLX3, and HOXA transcription factor oncogenes. Survival analysis demonstrated that WT1 mutations do not confer adverse prognosis in pediatric and adult T-ALL. Overall, these results identify the presence of WT1 mutations as a recurrent genetic alteration in T-ALL.Blood 07/2009; 114(5):1038-45. · 9.90 Impact Factor -
Article: Gamma-secretase inhibitors reverse glucocorticoid resistance in T cell acute lymphoblastic leukemia.
[show abstract] [hide abstract]
ABSTRACT: Gamma-secretase inhibitors (GSIs) block the activation of the oncogenic protein Notch homolog-1 (NOTCH1) in T cell acute lymphoblastic leukemia (T-ALL). However, limited antileukemic cytotoxicity and severe gastrointestinal toxicity have restricted the clinical application of these targeted drugs. Here we show that combination therapy with GSIs plus glucocorticoids can improve the antileukemic effects of GSIs and reduce their gut toxicity in vivo. Inhibition of NOTCH1 signaling in glucocorticoid-resistant T-ALL restored glucocorticoid receptor autoupregulation and induced apoptotic cell death through induction of the gene encoding BCL-2-like apoptosis initiator-11 (BCL2L11). GSI treatment resulted in cell cycle arrest and accumulation of goblet cells in the gut mediated by upregulation of the gene encoding the transcription factor Krüppel-like factor-4 (Klf4), a negative regulator of the cell cycle required for goblet cell differentiation. In contrast, glucocorticoid treatment induced transcriptional upregulation of cyclin D2 (Ccnd2) and protected mice from developing the intestinal goblet cell metaplasia typically induced by inhibition of NOTCH signaling with GSIs. These results support a role for glucocorticoids plus GSIs in the treatment of glucocorticoid-resistant T-ALL.Nature medicine 01/2009; 15(1):50-8. · 27.14 Impact Factor -
Article: Differential expression of constitutive and inducible proteasome subunits in human monocyte-derived DC differentiated in the presence of IFN-alpha or IL-4.
[show abstract] [hide abstract]
ABSTRACT: Several studies strongly suggest that DC differentiated in vitro in the presence of type I IFN acquire more potent immune stimulatory properties, compared with DC differentiated in vitro with IL-4. However, little is known about the molecular mechanisms underlying this phenomenon. To address this question, we compared the Ag-processing machinery (APM) profile in human DC grown in the presence of IFN-alpha ((IFN)DC) or IL-4 ((IL-4)DC). Using a panel of APM component-specific mAb in Western blot experiments, we found that (IFN)DC preferentially express inducible proteasome subunits (LMP2, LMP7, and MECL1) both at immature and mature stages. In contrast, immature (IL-4)DC co-express both constitutive (beta1, beta2, and beta5) and inducible subunits, as shown by Western blotting analysis. In addition, immature (IFN)DC express higher levels of TAP1, TAP2, calnexin, calreticulin, tapasin, and HLA class I molecules than (IL-4)DC. The different proteasome profiles of (IFN)DC and (IL-4)DC were associated with a greater ability of (IFN)DC to present an immunodominant epitope that requires LMP7 expression for its processing. In general, these data show the impact of cytokines on APM component expression and hence the Ag-processing ability of DC.European Journal of Immunology 01/2009; 39(1):56-66. · 5.10 Impact Factor -
Article: Differential expression of constitutive and inducible proteasome subunits in human monocyte‐derived DC differentiated in the presence of IFN‐α or IL‐4
[show abstract] [hide abstract]
ABSTRACT: Several studies strongly suggest that DC differentiated in vitro in the presence of type I IFN acquire more potent immune stimulatory properties, compared with DC differentiated in vitro with IL-4. However, little is known about the molecular mechanisms underlying this phenomenon. To address this question, we compared the Ag-processing machinery (APM) profile in human DC grown in the presence of IFN- (IFNDC) or IL-4 (IL-4DC). Using a panel of APM component-specific mAb in Western blot experiments, we found that IFNDC preferentially express inducible proteasome subunits (LMP2, LMP7, and MECL1) both at immature and mature stages. In contrast, immature IL-4DC co-express both constitutive (β1, β2, and β5) and inducible subunits, as shown by Western blotting analysis. In addition, immature IFNDC express higher levels of TAP1, TAP2, calnexin, calreticulin, tapasin, and HLA class I molecules than IL-4DC. The different proteasome profiles of IFNDC and IL-4DC were associated with a greater ability of IFNDC to present an immunodominant epitope that requires LMP7 expression for its processing. In general, these data show the impact of cytokines on APM component expression and hence the Ag-processing ability of DC.European Journal of Immunology 12/2008; 39(1):56 - 66. · 5.10 Impact Factor -
Article: The side population of ovarian cancer cells is a primary target of IFN-alpha antitumor effects.
[show abstract] [hide abstract]
ABSTRACT: The side population (SP), recently identified in several normal tissues and in a variety of tumors based on its ability to extrude some fluorescent dyes, may comprise cells endowed with stem cell features. In this study, we investigated the presence of SP in epithelial ovarian cancer and found it in 9 of 27 primary tumor samples analyzed, as well as in 4 of 6 cultures from xenotransplants. SP cells from one xenograft bearing a large SP fraction were characterized in detail. SP cells had higher proliferation rates, were much less apoptotic compared with non-SP cells, and generated tumors more rapidly than non-SP cells. We also investigated the effects of IFN-alpha, a cytokine that has widely been used to treat solid tumors, on epithelial ovarian cancer cells and observed that IFN-alpha exerted marked antiproliferative and proapoptotic effects on primary cultures containing high numbers of SP cells. In vitro, IFN-alpha treatment invariably caused a dramatic reduction in SP size in tumor cell lines of different origins; moreover, IFN-alpha treatment of purified SP cells was associated with a distinctive change in their transcriptional profile. Gene therapy with human IFN-alpha resulted in regression of established tumors bearing a large SP fraction, which was not observed when tumors bearing low SP levels were treated. These findings could have relevant clinical implications because they imply that tumors bearing large SP numbers, albeit rare, could be sensitive to IFN-alpha treatment.Cancer Research 07/2008; 68(14):5658-68. · 7.86 Impact Factor -
Article: NOTCH1 extracellular juxtamembrane expansion mutations in T-ALL.
[show abstract] [hide abstract]
ABSTRACT: Heterodimerization domain (HD) mutations in NOTCH1 induce ligand-independent activation of the receptor and contribute to the pathogenesis of one-third of human T-cell lymphoblastic leukemias (T-ALLs). Here we report a novel class of activating mutations in NOTCH1 leading to aberrant activation of NOTCH1 signaling in T-cell lymphoblasts. These so-called juxtamembrane expansion (JME) alleles consist of internal duplication insertions in the vicinity of exon 28 of the NOTCH1 gene encoding the extracellular juxtamembrane region of the receptor. Notably, structure-function analysis of leukemia-derived and synthetic JME mutants demonstrated that the aberrant activation of NOTCH1 signaling is dependent on the number of residues introduced in the extracellular juxtamembrane region of the receptor and not on the specific amino acid sequence of these insertions. JME NOTCH1 mutants are effectively blocked by gamma-secretase inhibitors and require an intact metalloprotease cleavage site for activation. Overall, these results show a novel mechanism of NOTCH1 activation in T-ALL and provide further insight on the mechanisms that control the activation of NOTCH1 signaling.Blood 05/2008; 112(3):733-40. · 9.90 Impact Factor -
Article: Differential expression of CCR7 defines two distinct subsets of human memory CD4+CD25+ Tregs.
[show abstract] [hide abstract]
ABSTRACT: Natural Tregs play an essential role in controlling self-tolerance but the in vivo sites of Treg-mediated suppression remain controversial. We have previously reported the identification of distinct naïve and memory Treg populations in human circulating lymphocytes. Here we show that memory Tregs contain high proportions of inflammatory chemokine-expressing cells and comprise two populations that differ in the expression of the lymphoid chemokine receptor CCR7 and represent the counterparts of conventional CCR7(+) central memory (CM) and CCR7(-) effector memory (EM) T cells. CM and EM Tregs exert comparable ex vivo suppressor functions but the EM population is more prominent among Tregs as compared to conventional CD4(+) T cells, and is the main Treg subset found in ovarian tumors. Our data suggest that a division of labor between CM and EM Tregs ensures tolerance at lymphoid and peripheral locations including tumor sites.Clinical Immunology 04/2008; 126(3):291-302. · 4.05 Impact Factor -
Article: Differential regulation of hypoxia-induced CXCR4 triggering during B-cell development and lymphomagenesis.
[show abstract] [hide abstract]
ABSTRACT: The chemokine receptor CXCR4 plays a central role in organ-specific homing and tumor spreading and is induced by hypoxia. B lymphocytes are exposed to low oxygen tensions during their development, but the influence of hypoxia on their physiology is poorly understood. Here, we show that hypoxia is associated with up-regulation of CXCR4 expression in human normal and malignant B cells, through both transcriptional and posttranslational mechanisms. However, a dichotomic functional response to CXCR4 triggering was observed: both peripheral B cells and lymphomas arising from mature B cells displayed increased responses to CXCR4 triggering under hypoxia, whereas germinal center (GC) B cells as well as GC-derived lymphomas showed CXCR4 receptor desensitization. This phenomenon was associated with differential modulation of key signal-transducing molecules, including mitogen-activated protein kinase phosphatase-1 and regulator of G protein signaling molecule-1. The unresponsiveness of GC-derived lymphomatous B cells to CXCR4 triggering under hypoxia may have implications for the development and pathogenesis of GC-derived lymphoid tumors.Cancer Research 10/2007; 67(18):8605-14. · 7.86 Impact Factor -
Article: Vaccination with NY-ESO-1 protein and CpG in Montanide induces integrated antibody/Th1 responses and CD8 T cells through cross-priming.
[show abstract] [hide abstract]
ABSTRACT: The use of recombinant tumor antigen proteins is a realistic approach for the development of generic cancer vaccines, but the potential of this type of vaccines to induce specific CD8(+) T cell responses, through in vivo cross-priming, has remained unclear. In this article, we report that repeated vaccination of cancer patients with recombinant NY-ESO-1 protein, Montanide ISA-51, and CpG ODN 7909, a potent stimulator of B cells and T helper type 1 (Th1)-type immunity, resulted in the early induction of specific integrated CD4(+) Th cells and antibody responses in most vaccinated patients, followed by the development of later CD8(+) T cell responses in a fraction of them. The correlation between antibody and T cell responses, together with the ability of vaccine-induced antibodies to promote in vitro cross-presentation of NY-ESO-1 by dendritic cells to vaccine-induced CD8(+) T cells, indicated that elicitation of NY-ESO-1-specific CD8(+) T cell responses by cross-priming in vivo was associated with the induction of adequate levels of specific antibodies. Together, our data provide clear evidence of in vivo cross-priming of specific cytotoxic T lymphocytes by a recombinant tumor antigen vaccine, underline the importance of specific antibody induction for the cross-priming to occur, and support the use of this type of formulation for the further development of efficient cancer vaccines.Proceedings of the National Academy of Sciences 06/2007; 104(21):8947-52. · 9.68 Impact Factor -
Article: Epitope clustering in regions undergoing efficient proteasomal processing defines immunodominant CTL regions of a tumor antigen.
[show abstract] [hide abstract]
ABSTRACT: Identification of immunodominant CD8(+) T cell responses to frequently expressed tumor antigens across MHC class I polymorphism is essential for the implementation of cancer immunotherapy. However, the key factors that determine immunodominance are not fully understood. Because of its frequent expression in tumors and its spontaneous immunogenicity, NY-ESO-1 is a prime target of cancer vaccines and an ideal model antigen for elucidating the molecular basis of immunodominant tumor-specific CD8(+) T cell responses. Here, we have assessed CD8(+)T cell responses to full-length NY-ESO-1 in cancer patients. We identified 3 immunodominant regions of the protein located within 3 distinct clusters of MHC class I binding sequences that co-localize with previously defined clusters of MHC class II binding sequences, are predicted to be hydrophobic and undergo efficient proteasomal processing. Our results support the concept that epitope clustering within defined protein regions identifies tumor antigen immunodominant regions and suggest a general strategy for their identification.Clinical Immunology 03/2007; 122(2):163-72. · 4.05 Impact Factor -
Article: Rapamycin-mediated enrichment of T cells with regulatory activity in stimulated CD4+ T cell cultures is not due to the selective expansion of naturally occurring regulatory T cells but to the induction of regulatory functions in conventional CD4+ T cells.
[show abstract] [hide abstract]
ABSTRACT: Rapamycin is an immunosuppressive drug currently used in different clinical settings. Although the capacity of rapamycin to inhibit the mammalian target of rapamycin serine/threonine protein kinase and therefore T cell cycle progression is well known, its effects are complex and not completely understood. It has been reported recently that TCR-mediated stimulation of murine CD4+ T cells in the presence of rapamycin results in increased proportions of CD4+ T cells with suppressive functions, suggesting that the drug may also exert its immunosuppressive activity by promoting the selective expansion of naturally occurring CD4+ regulatory T cells (Treg). In this study, we show that stimulation of human circulating CD4+ T cells in the presence of rapamycin results indeed in highly increased suppressor activity. By assessing the effect of rapamycin on the growth of nonregulatory and Treg populations of defined differentiation stages purified ex vivo from circulating CD4+ T cells, we could demonstrate that this phenomenon is not due to a selective expansion of naturally occurring Tregs, but to the capacity of rapamycin to induce, upon TCR-mediated stimulation, suppressor functions in conventional CD4+ T cells. This condition, however, is temporary and reversible as it is dependent upon the continuous presence of rapamycin.The Journal of Immunology 08/2006; 177(2):944-9. · 5.79 Impact Factor -
Article: Interruption of tumor dormancy by a transient angiogenic burst within the tumor microenvironment.
[show abstract] [hide abstract]
ABSTRACT: Tumor growth is currently viewed as a phenomenon associated with neovascularization and sustained production of angiogenic factors, but whether a transient angiogenic switch may trigger tumor growth remains unclear. Here, we report that leukemia cells (MOLT-3) were poorly angiogenic and remained dormant when injected s.c. into immunodeficient mice. However, progressive growth of lymphoid tumors was invariably recorded when irradiated angiogenic cells from Kaposi's sarcoma (KS-IMM) were locally coinjected with MOLT-3 cells or administered later. The persistence of KS-IMM cells in vivo was tracked by flow cytometry and real-time PCR analysis, and it was limited to a few days, during which angiogenesis was induced and preceded tumor growth. The engraftment of other types of poorly tumorigenic cancer cells was also greatly improved by irradiated KS-IMM cells. Moreover, short-term treatment with angiogenic factors, including basic FGF or VEGF, either given as recombinant factors or delivered by retroviral vectors, also accelerated tumor growth. These findings may emphasize that tumor angiogenesis is a process requiring a higher amount of angiogenic factors for its induction than maintenance.Proceedings of the National Academy of Sciences 04/2006; 103(11):4216-21. · 9.68 Impact Factor -
Article: Heterogeneous intracellular expression of B-cell receptor components in B-cell chronic lymphocytic leukaemia (B-CLL) cells and effects of CD79b gene transfer on surface immunoglobulin levels in a B-CLL-derived cell line.
[show abstract] [hide abstract]
ABSTRACT: B-cell chronic lymphocytic leukaemia (B-CLL) cells display low amounts of surface immunoglobulins (sIg). To investigate the mechanisms underlying this phenomenon, we performed a thorough study of surface and intracellular expression of the B-cell receptor (BCR) components in B-CLL cells using flow cytometry. There was an heterogeneous pattern of expression. Overall, 20 of 22 samples showed reduced sIgM levels, compared with normal B cells. Among them, three (15%) had very low to undetectable intracellular IgM levels and variable amounts of CD79a and CD79b; nine (45%) had low intracellular CD79b levels but appreciable levels of IgM and CD79a; and eight (40%) had relatively normal intracellular levels of all BCR components. To investigate whether surface BCR levels could be controlled by the rate of CD79b synthesis, adenoviral vectors encoding CD79b were generated and used for gene transfer experiments. Delivery of CD79b to non-B cells transfected with IgM and CD79a lead to high-level expression of a functional BCR. Moreover, CD79b gene transfer in a B cell line derived from a B-CLL patient and characterised by low intracellular levels of endogenous CD79b consistently increased sIgM levels. These findings indicate that the phenotype of B-CLL cells in a subset of patients may depend primarily on poor CD79b expression, and suggest that upregulation of CD79b expression may correct the phenotype of these cells.British Journal of Haematology 10/2005; 130(6):878-89. · 4.94 Impact Factor
Top Journals
Institutions
-
2006–2013
-
Columbia University
- • Institute for Cancer Genetics
- • Department of Pediatrics
- • Department of Medicine
New York City, NY, USA
-
-
2002–2009
-
University-Hospital of Padova
Padova, Veneto, Italy
-
-
2008
-
The Clinical Trial Center, LLC
Jenkintown, PA, USA -
University of Pittsburgh
- Department of Surgery
Pittsburgh, PA, USA
-
-
2002–2005
-
University of Padua
Padova, Veneto, Italy
-