Publications by authors named "Paola Circosta"

27 Publications

  • Page 1 of 1

Targeting Acute Myelogenous Leukemia Using Potent Human Dihydroorotate Dehydrogenase Inhibitors Based on the 2-Hydroxypyrazolo[1,5-]pyridine Scaffold: SAR of the Biphenyl Moiety.

J Med Chem 2021 Apr 12. Epub 2021 Apr 12.

Department of Drug Science and Technology, University of Turin, Via P. Giuria 9, Turin 10125, Italy.

The connection with acute myelogenous leukemia (AML) of dihydroorotate dehydrogenase (DHODH), a key enzyme in pyrimidine biosynthesis, has attracted significant interest from pharma as a possible AML therapeutic target. We recently discovered compound , a potent DHODH inhibitor (IC = 1.2 nM), able to induce myeloid differentiation in AML cell lines (THP1) in the low nM range (EC = 32.8 nM) superior to brequinar's phase I/II clinical trial (EC = 265 nM). Herein, we investigate the drug-like properties observing good metabolic stability and no toxic profile when administered at doses of 10 and 25 mg/kg every 3 days for 5 weeks (Balb/c mice). Moreover, in order to identify a backup compound, we investigate the SAR of this class of compounds. Inside the series, is characterized by higher potency in inducing myeloid differentiation (EC = 17.3 nM), strong proapoptotic properties (EC = 20.2 nM), and low cytotoxicity toward non-AML cells (EC(Jurkat) > 100 μM).
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http://dx.doi.org/10.1021/acs.jmedchem.0c01549DOI Listing
April 2021

Targeting Chronic Myeloid Leukemia Stem/Progenitor Cells Using Venetoclax-Loaded Immunoliposome.

Cancers (Basel) 2021 Mar 15;13(6). Epub 2021 Mar 15.

Department of Clinical and Biological Sciences, University of Turin, 10043 Turin, Italy.

CML is a hematopoietic stem-cell disorder emanating from breakpoint cluster region/Abelson murine leukemia 1 (BCR/ABL) translocation. Introduction of different TKIs revolutionized treatment outcome in CML patients, but CML LSCs seem insensitive to TKIs and are detectable in newly diagnosed and resistant CML patients and in patients who discontinued therapy. It has been reported that CML LSCs aberrantly express some CD markers such as CD26 that can be used for the diagnosis and for targeting. In this study, we confirmed the presence of CD26+ CML LSCs in newly diagnosed and resistant CML patients. To selectively target CML LSCs/progenitor cells that express CD26 and to spare normal HSCs/progenitor cells, we designed a venetoclax-loaded immunoliposome (IL-VX). Our results showed that by using this system we could selectively target CD26+ cells while sparing CD26- cells. The efficiency of venetoclax in targeting CML LSCs has been reported and our system demonstrated a higher potency in cell death induction in comparison to free venetoclax. Meanwhile, treatment of patient samples with IL-VX significantly reduced CD26+ cells in both stem cells and progenitor cells population. In conclusion, this approach showed that selective elimination of CD26+ CML LSCs/progenitor cells can be obtained in vitro, which might allow in vivo reduction of side effects and attainment of treatment-free, long-lasting remission in CML patients.
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http://dx.doi.org/10.3390/cancers13061311DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8000981PMC
March 2021

The Synergism between DHODH Inhibitors and Dipyridamole Leads to Metabolic Lethality in Acute Myeloid Leukemia.

Cancers (Basel) 2021 Feb 28;13(5). Epub 2021 Feb 28.

Department of Clinical and Biological Sciences, University of Turin, Orbassano, 10043 Turin, Italy.

Dihydroorotate Dehydrogenase (DHODH) is a key enzyme of the pyrimidine biosynthesis, whose inhibition can induce differentiation and apoptosis in acute myeloid leukemia (AML). DHODH inhibitors had shown promising in vitro and in vivo activity on solid tumors, but their effectiveness was not confirmed in clinical trials, probably because cancer cells exploited the pyrimidine salvage pathway to survive. Here, we investigated the antileukemic activity of MEDS433, the DHODH inhibitor developed by our group, against AML. Learning from previous failures, we mimicked human conditions (performing experiments in the presence of physiological uridine plasma levels) and looked for synergic combinations to boost apoptosis, including classical antileukemic drugs and dipyridamole, a blocker of the pyrimidine salvage pathway. MEDS433 induced apoptosis in multiple AML cell lines, not only as a consequence of differentiation, but also directly. Its combination with antileukemic agents further increased the apoptotic rate, but when experiments were performed in the presence of physiological uridine concentrations, results were less impressive. Conversely, the combination of MEDS433 with dipyridamole induced metabolic lethality and differentiation in all AML cell lines; this extraordinary synergism was confirmed on AML primary cells with different genetic backgrounds and was unaffected by physiological uridine concentrations, predicting activity.
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http://dx.doi.org/10.3390/cancers13051003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7957697PMC
February 2021

Nanocarriers as Magic Bullets in the Treatment of Leukemia.

Nanomaterials (Basel) 2020 Feb 6;10(2). Epub 2020 Feb 6.

Department of Clinical and Biological Sciences, University of Torino, 10043 Torino, Italy.

Leukemia is a type of hematopoietic stem/progenitor cell malignancy characterized by the accumulation of immature cells in the blood and bone marrow. Treatment strategies mainly rely on the administration of chemotherapeutic agents, which, unfortunately, are known for their high toxicity and side effects. The concept of targeted therapy as magic bullet was introduced by Paul Erlich about 100 years ago, to inspire new therapies able to tackle the disadvantages of chemotherapeutic agents. Currently, nanoparticles are considered viable options in the treatment of different types of cancer, including leukemia. The main advantages associated with the use of these nanocarriers summarized as follows: i) they may be designed to target leukemic cells selectively; ii) they invariably enhance bioavailability and blood circulation half-life; iii) their mode of action is expected to reduce side effects. FDA approval of many nanocarriers for treatment of relapsed or refractory leukemia and the desired results extend their application in clinics. In the present review, different types of nanocarriers, their capability in targeting leukemic cells, and the latest preclinical and clinical data are discussed.
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http://dx.doi.org/10.3390/nano10020276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075174PMC
February 2020

Inhibition of bromodomain and extra-terminal proteins increases sensitivity to venetoclax in chronic lymphocytic leukaemia.

J Cell Mol Med 2020 01 10;24(2):1650-1657. Epub 2019 Dec 10.

Dept. of Clinical and Biological Sciences, University of Turin, Orbassano, Italy.

The development of drugs able to target BTK, PI3k-delta and BCL2 has dramatically improved chronic lymphocytic leukaemia (CLL) therapies. However, drug resistance to these therapies has already been reported due to non-recurrent changes in oncogenic pathways and genes expression signatures. In this study, we investigated the cooperative role of the BCL2 inhibitor venetoclax and the BRD4 inhibitor JQ1. In particular, we found that JQ1 shows additional activity with venetoclax, in CLL cell lines and in ex vivo isolated primary CD19 lymphocytes, arguing in favour of combination strategies. Lastly, JQ1 is also effective in venetoclax-resistant CLL cell lines. Together, our findings indicated that the BET inhibitor JQ1 could be a promising therapy in CLL, both as first-line therapy in combination with venetoclax and as second-line therapy, after the emergence of venetoclax-resistant clones.
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http://dx.doi.org/10.1111/jcmm.14857DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6991693PMC
January 2020

Bone marrow microenvironment: The guardian of leukemia stem cells.

World J Stem Cells 2019 Aug;11(8):476-490

Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran 146651157, Iran.

Bone marrow microenvironment (BMM) is the main sanctuary of leukemic stem cells (LSCs) and protects these cells against conventional therapies. However, it may open up an opportunity to target LSCs by breaking the close connection between LSCs and the BMM. The elimination of LSCs is of high importance, since they follow cancer stem cell theory as a part of this population. Based on cancer stem cell theory, a cell with stem cell-like features stands at the apex of the hierarchy and produces a heterogeneous population and governs the disease. Secretion of cytokines, chemokines, and extracellular vesicles, whether through autocrine or paracrine mechanisms by activation of downstream signaling pathways in LSCs, favors their persistence and makes the BMM less hospitable for normal stem cells. While all details about the interactions of the BMM and LSCs remain to be elucidated, some clinical trials have been designed to limit these reciprocal interactions to cure leukemia more effectively. In this review, we focus on chronic myeloid leukemia and acute myeloid leukemia LSCs and their milieu in the bone marrow, how to segregate them from the normal compartment, and finally the possible ways to eliminate these cells.
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http://dx.doi.org/10.4252/wjsc.v11.i8.476DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6716085PMC
August 2019

Chronic myeloid leukemia stem cells.

Leukemia 2019 07 24;33(7):1543-1556. Epub 2019 May 24.

Imperial College London, London, UK.

Chronic myeloid leukemia (CML) is caused by BCRABL1 in a cell with the biological potential, intrinsic or acquired, to cause leukemia. This cell is commonly termed the CML leukemia stem cell (LSC). In humans a CML LSC is operationally-defined by ≥1 in vitro or in vivo assays of human leukemia cells transferred to immune-deficient mice. Results of these assays are sometimes discordant. There is also the unproved assumption that biological features of a CML LSC are stable. These considerations make accurate and precise identification of a CML LSC difficult or impossible. In this review, we consider biological features of CML LSCs defined by these assays. We also consider whether CML LSCs are susceptible to targeting by tyrosine kinase inhibitors (TKIs) and other drugs, and whether elimination of CML LSCs is needed to achieve therapy-free remission or cure CML.
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http://dx.doi.org/10.1038/s41375-019-0490-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6755964PMC
July 2019

An Ig Transmembrane Domain Motif Improves the Function of TCRs Transduced in Human T Cells: Implications for Immunotherapy.

J Immunother 2019 05;42(4):97-109

Institute of Protein Biochemistry, National Research Council.

Adoptive transfer of T lymphocytes (ACT) engineered with T-cell receptors (TCRs) of known antitumor specificity is an effective therapeutic strategy. However, a major constraint of ACT is the unpredictable interference of the endogenous TCR α and β chains in pairing of the transduced TCR. This effect reduces the efficacy of the genetically modified primary T cells and carries the risk of generating novel TCR reactivities with unintended functional consequences. Here, we show a powerful approach to overcome these limitations. We engineered TCR α and β chains with mutations encompassing a conserved motif (FXXXFXXS) required to stabilize the pairing of immunoglobulin heavy chain transmembrane domains. Molecular modeling supported the preferential pairing of mutated TCR and impaired pairing between mutated and wild-type TCRs. Expression of the mutated TCR was similar to wild type and conferred the expected specificity. Fluorescence resonance energy transfer analysis in mouse splenocytes transduced with mutated or wild-type TCRs showed a higher proximity of the former over the latter. Importantly, we show that mutated TCRs effectively outcompete endogenous TCRs and improve in vitro antitumor cytotoxicity when expressed in ex vivo isolated human T cells. This approach should contribute to improving current protocols of anticancer immunetherapy protocols.
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http://dx.doi.org/10.1097/CJI.0000000000000259DOI Listing
May 2019

Survivin-peptide vaccination elicits immune response after allogeneic nonmyeloablative transplantation: a safe strategy to enhance the graft versus tumor effect.

Immunotherapy 2018 07;10(9):753-767

Molecular Biotechnology Center, University of Torino, 10126 Turin, Italy.

Allogeneic hematopoietic cell transplantation (allo-HCT) is an adoptive immunotherapy strategy whose effectiveness relies on graft-versus-tumor (GVT) effect. We explored the feasibility of enhancing GVT after allo-HCT by peptide vaccination. Two myeloma patients were transplanted with a fludarabine-total body irradiation conditioning regimen and vaccinated with an HLA-A*0201-restricted modified survivin nonapeptide, plus montanide as adjuvant. At time of first vaccination, one patient had just attained serological remission despite documented relapse after transplant, while the other patient was in stable disease. Both patients had an immune response to vaccination: the frequency of survivin-specific CD8 T cells increased between second and sixth vaccination and accounted for 0.5-0.8% of CD8 cells; CD8 cells were functional in ELISPOT assay. The first patient persists in complete remission with a follow-up of >5 years, while the second patient did not have a clinical response and vaccination was halted. We analyzed the T-cell receptor (TCR) repertoire of the first patient by spectratyping and found that vaccination did not affect the diversity of TCR profile, indicating that survivin clonotypes were probably spread in multiple TCR families. We generated a limited number (n = 4) of survivin-specific T cell clones: three were reactive only against the modified peptide, whereas one clone recognized also the naive peptide. Peptide vaccination is safe and applicable after allo-HCT and elicits an efficient antigen-specific T cell response without causing graft-versus-host disease.
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http://dx.doi.org/10.2217/imt-2017-0139DOI Listing
July 2018

Targeting Myeloid Differentiation Using Potent 2-Hydroxypyrazolo[1,5- a]pyridine Scaffold-Based Human Dihydroorotate Dehydrogenase Inhibitors.

J Med Chem 2018 Jul 9;61(14):6034-6055. Epub 2018 Jul 9.

Department of Clinical and Biological Sciences , University of Turin , Turin 10043 , Italy.

Human dihydroorotate dehydrogenase ( hDHODH) catalyzes the rate-limiting step in de novo pyrimidine biosynthesis, the conversion of dihydroorotate to orotate. hDHODH has recently been found to be associated with acute myelogenous leukemia, a disease for which the standard of intensive care has not changed over decades. This work presents a novel class of hDHODH inhibitors, which are based on an unusual carboxylic group bioisostere 2-hydroxypyrazolo[1,5- a]pyridine, that has been designed starting from brequinar, one of the most potent hDHODH inhibitors. A combination of structure-based and ligand-based strategies produced compound 4, which shows brequinar-like hDHODH potency in vitro and is superior in terms of cytotoxicity and immunosuppression. Compound 4 also restores myeloid differentiation in leukemia cell lines at concentrations that are one log digit lower than those achieved in experiments with brequinar. This Article reports the design, synthesis, SAR, X-ray crystallography, biological assays, and physicochemical characterization of the new class of hDHODH inhibitors.
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http://dx.doi.org/10.1021/acs.jmedchem.8b00373DOI Listing
July 2018

Tailoring CD19xCD3-DART exposure enhances T-cells to eradication of B-cell neoplasms.

Oncoimmunology 2018;7(4):e1341032. Epub 2018 Feb 8.

Department of Molecular Biotechnology and Health Science and Center for Experimental Research and Medical Studies (CeRMS), University of Torino, Torino, Italy.

Many patients with B-cell malignancies can be successfully treated, although tumor eradication is rarely achieved. T-cell-directed killing of tumor cells using engineered T-cells or bispecific antibodies is a promising approach for the treatment of hematologic malignancies. We investigated the efficacy of CD19xCD3 DART bispecific antibody in a broad panel of human primary B-cell malignancies. The CD19xCD3 DART identified 2 distinct subsets of patients, in which the neoplastic lymphocytes were eliminated with rapid or slow kinetics. Delayed responses were always overcome by a prolonged or repeated DART exposure. Both CD4 and CD8 effector cytotoxic cells were generated, and DART-mediated killing of CD4 cells into cytotoxic effectors required the presence of CD8 cells. Serial exposures to DART led to the exponential expansion of CD4 and CD8 cells and to the sequential ablation of neoplastic cells in absence of a PD-L1-mediated exhaustion. Lastly, patient-derived neoplastic B-cells (B-Acute Lymphoblast Leukemia and Diffuse Large B Cell Lymphoma) could be proficiently eradicated in a xenograft mouse model by DART-armed cytokine induced killer (CIK) cells. Collectively, patient tailored DART exposures can result in the effective elimination of CD19 positive leukemia and B-cell lymphoma and the association of bispecific antibodies with unmatched CIK cells represents an effective modality for the treatment of CD19 positive leukemia/lymphoma.
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http://dx.doi.org/10.1080/2162402X.2017.1341032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5889202PMC
February 2018

Identification of a new subclass of ALK-negative ALCL expressing aberrant levels of ERBB4 transcripts.

Blood 2016 Jan 13;127(2):221-32. Epub 2015 Oct 13.

Department of Molecular Biotechnology and Health Sciences, Center for Experimental Research and Medical Studies, University of Turin, Turin, Italy; Department of Pathology, New York University Cancer Center, New York University School of Medicine, New York, NY.

Anaplastic large-cell lymphoma (ALCL) is a clinical and biological heterogeneous disease that includes systemic anaplastic lymphoma kinase (ALK)-positive and ALK-negative entities. To discover biomarkers and/or genes involved in ALK-negative ALCL pathogenesis, we applied the cancer outlier profile analysis algorithm to a gene expression profiling data set including 249 cases of T-cell non-Hodgkin lymphoma and normal T cells. Ectopic coexpression of ERBB4 and COL29A1 genes was detected in 24% of ALK-negative ALCL patients. RNA sequencing and 5' RNA ligase-mediated rapid amplification of complementary DNA ends identified 2 novel ERBB4-truncated transcripts displaying intronic transcription start sites. By luciferase assays, we defined that the expression of ERBB4-aberrant transcripts is promoted by endogenous intronic long terminal repeats. ERBB4 expression was confirmed at the protein level by western blot analysis and immunohistochemistry. Lastly, we demonstrated that ERBB4-truncated forms show oncogenic potentials and that ERBB4 pharmacologic inhibition partially controls ALCL cell growth and disease progression in an ERBB4-positive patient-derived tumorgraft model. In conclusion, we identified a new subclass of ALK-negative ALCL characterized by aberrant expression of ERBB4-truncated transcripts carrying intronic 5' untranslated regions.
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http://dx.doi.org/10.1182/blood-2014-12-614503DOI Listing
January 2016

Cytokine-induced killer cells engineered with exogenous T-cell receptors directed against melanoma antigens: enhanced efficacy of effector cells endowed with a double mechanism of tumor recognition.

Hum Gene Ther 2015 Apr 13;26(4):220-31. Epub 2015 Apr 13.

1 Molecular Biotechnology Center, University of Torino , 10126 Turin, Italy .

Cytokine-induced killer (CIK) cells consist of a heterogeneous population of polyclonal T lymphocytes displaying NK phenotype and HLA-unrestricted cytotoxic activity against a broad range of tumors. We sought to determine whether transduction of CIK cells with T cell receptor (TCR) genes specific for tumor-associated antigens could generate effector cells endowed with a double mechanism of tumor recognition. HLA-A2-restricted TCR-transduced (TD) CIK directed against the melanoma antigens Mart1 and NY-ESO1 were generated by lentiviral transduction and successfully expanded over a 3-4-week period. TD-CIK cells were both CD3(+)/CD56(-) and CD3(+)/CD56(+) (31±8% and 59±9%, respectively), indicating that both major histocompatibility complex (MHC)-restricted T cells and MHC-unrestricted CIK could be targeted by lentiviral transduction. At the end of the culture, the majority of both unmodified and TD-CIK displayed an effector memory phenotype, without considerable expression of replicative senescence and exhaustion markers. Functionally, TD-CIK specifically recognized tumor cells expressing the relevant antigen as well as maintained their MHC-unrestricted tumor activity. The cytotoxic activity of TD-CIK against HLA-A2(+) melanoma cell lines was significantly higher than the untransduced counterparts at a low effector:target ratio (cytotoxic activity of TD-CIK was from 1.9- to 4.3-fold higher than untransduced counterparts). TD-CIK were highly proficient in releasing high amount of IFN-γ upon antigen-specific stimulation and were able to recognize primary melanoma targets. In conclusion, we showed that (1) the reproducibility and simplicity of CIK transduction and expansion might solve the problem of obtaining adequate numbers of potent antitumor effector cells for adoptive immunotherapy; (2) the presence of both terminal effectors as well as of less differentiated progenitors might confer them long survival in vivo; and (3) the addition of an MHC-restricted antigen recognition allows not only targeting tumor surface antigens but also a wider range of cytoplasmic or nuclear antigens, involved in tumor proliferation and survival. TD-CIK cells with a double mechanism of tumor recognition are an attractive and alternative tool for the development of efficient cell therapeutic strategies.
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http://dx.doi.org/10.1089/hum.2014.112DOI Listing
April 2015

The molecular and functional characterization of clonally expanded CD8+ TCR BV T cells in eosinophilic granulomatosis with polyangiitis (EGPA).

Clin Immunol 2014 May-Jun;152(1-2):152-63. Epub 2014 Mar 13.

University Division of Hematology and Cell Therapy, AO Mauriziano, Torino, University of Torino, Italy; Molecular Biotechnology Center (MBC), University of Torino, Italy. Electronic address:

In eosinophilic granulomatosis with polyangiitis (EGPA) clonally expanded T cells might concur in granuloma formation and vascular injury. The TCR β-variable (BV) chain repertoire and third complementarity determining region (CDR3) of peripheral CD4+ and CD8+ cells in EGPA patients and age-matched controls and the expression of cytokines and chemokine receptors were investigated. The CD8+ lymphocytes of EGPA patients showed an increased frequency of BV expansions with a skewed profile of BV CDR3 lengths, increased CCR5 and CXCR3 expression and increased INFγ and TNFα production. In two patients, the TCR CDR3 cDNA sequences of the expanded BV family were identified. The CD4+ lymphocytes of EGPA patients revealed a higher expression of CRTH2 and increased production of IL-5. In conclusion, CD4+ T cells display a Th2 profile and CD8+ T cells are clonally expanded in EGPA and have a proinflammatory phenotype, suggesting their pathogenic role in vasculitic damage.
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http://dx.doi.org/10.1016/j.clim.2014.03.001DOI Listing
July 2014

miR-223 is a coordinator of breast cancer progression as revealed by bioinformatics predictions.

PLoS One 2014 6;9(1):e84859. Epub 2014 Jan 6.

Molecular Biotechnology Center (MBC), University of Torino, Torino, Italy ; Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy ; Center for Molecular Systems Biology, University of Torino, Torino, Italy.

MicroRNAs are single-stranded non-coding RNAs that simultaneously down-modulate the expression of multiple genes post-transcriptionally by binding to the 3'UTRs of target mRNAs. Here we used computational methods to predict microRNAs relevant in breast cancer progression. Specifically, we applied different microRNA target prediction algorithms to various groups of differentially expressed protein-coding genes obtained from four breast cancer datasets. Six potential candidates were identified, among them miR-223, previously described to be highly expressed in the tumor microenvironment and known to be actively transferred into breast cancer cells. To investigate the function of miR-223 in tumorigenesis and to define its molecular mechanism, we overexpressed miR-223 in breast cancer cells in a transient or stable manner. Alternatively we overexpressed miR-223 in mouse embryonic fibroblasts or HEK293 cells and used their conditioned medium to treat tumor cells. With both approaches, we obtained elevated levels of miR-223 in tumor cells and observed decreased migration, increased cell death in anoikis conditions and augmented sensitivity to chemotherapy but no effect on adhesion and proliferation. The analysis of miR-223 predicted targets revealed enrichment in cell death and survival-related genes and in pathways frequently altered in breast cancer. Among these genes, we showed that protein levels for STAT5A, ITGA3 and NRAS were modulated by miR-223. In addition, we proved that STAT5A is a direct miR-223 target and highlighted a possible correlation between miR-223 and STAT5A in migration and chemotherapy response. Our investigation revealed that a computational analysis of cancer gene expression datasets can be a relevant tool to identify microRNAs involved in cancer progression and that miR-223 has a prominent role in breast malignancy that could potentially be exploited therapeutically.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084859PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3882278PMC
September 2014

Expression of NKG2D and CD107 in CD8(+) effector memory lymphocytes in Churg-Strauss syndrome.

Clin Exp Rheumatol 2012 Jan-Feb;30(1 Suppl 70):S57-61. Epub 2012 May 14.

Allergology and Clinical Immunology, University of Torino, Italy.

Objectives: Churg-Strauss syndrome (CSS) is a necrotising vasculitis of small vessels in which oligoclonally expanded TCR Vβ CD8+ effector memory T cells populations (TEM) may be involved in vasculitic damage. The aim of this study was to assess the functional role of CD8+ T cells in CSS patients by flow cytometry analysis of membrane expression of cytotoxic markers NKG2D and CD107a.

Methods: Immunostaining of peripheral T cells and effector memory lymphocytes (TEM) from CSS patients and controls was performed by gating CD28 and CD45RA in the CD8+NKG2D+ and CD4+NKG2D+ populations. CD107a expression was evaluated in both whole CD8+ and CD4+ and the TEM cells by gating CD62 and CD45RA following polyclonal stimulation.

Results: NKG2D expression was shifted toward the CD8+CD28- fraction of T cells in CSS patients compared to healthy controls (56.1±25.8% versus 17.2±7.3%, respectively, p=0.002). CD8+Vβ+ expanded T cells showed a significantly increased expression of NKG2D compared to the whole CD8+ T cell population (91.4±1.9% versus 79.7±3.8%, respectively, p=0.015). Moreover the CD8+ population from CSS upregulates CD107a on its surface upon polyclonal stimulation in a significantly higher proportion than healthy subjects (26.2±10.8% versus 8.2±2.9%, p=0.0031) and the majority CD8+ CD107+ cells from CSS patients showed a TEM phenotype compared to controls (64.8±4.9% vs. 19.8±2.9, respectively, p<0.001).

Conclusions: In CSS, CD8+ TEM lymphocytes show markers of cytotoxic activity, which suggests a role for these cells in vasculitic damage.
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August 2012

High basal γH2AX levels sustain self-renewal of mouse embryonic and induced pluripotent stem cells.

Stem Cells 2012 Jul;30(7):1414-23

Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.

Phosphorylation of histone H2AX (γH2AX) is known to be the earliest indicator of DNA double-strand breaks. Recently, it has been shown that mouse embryonic stem cells (mESCs) have very high basal levels of γH2AX, even when they have not been exposed to genotoxic agents. As the specialized role of high basal γH2AX levels in pluripotent stem cells is still debated, we investigated whether H2AX phosphorylation is important in maintaining self-renewal of these cells. Here, we report that not only mESCs but also mouse-induced pluripotent stem cells (miPSCs), have high basal levels of γH2AX. We show that basal γH2AX levels decrease upon ESC and iPSC differentiation and increase when the cells are treated with self-renewal-enhancing small molecules. We observe that self-renewal activity is highly compromised in H2AX-/- cells and that it can be restored in these cells through reconstitution with a wild-type, but not a phospho-mutated, H2AX construct. Taken together, our findings suggest a novel function of H2AX that expands the knowledge of this histone variant beyond its role in DNA damage and into a new specialized biological function in mouse pluripotent stem cells.
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http://dx.doi.org/10.1002/stem.1133DOI Listing
July 2012

Transient proteasome inhibition as a strategy to enhance lentiviral transduction of hematopoietic CD34(+) cells and T lymphocytes: implications for the use of low viral doses and large-size vectors.

J Biotechnol 2011 Dec 10;156(3):218-26. Epub 2011 Sep 10.

Laboratory of Cell Therapy of Cancer, Department of Oncological Sciences, University of Torino Medical School, Institute for Cancer Research and Treatment, Provinciale 142, 10060 Candiolo, Torino, Italy.

The proteasome system restricts lentiviral transduction of stem cells. We exploited proteasome inhibition as a strategy to enhance transduction of both hematopoietic stem cells (HSC) and T lymphocytes with low dose or large-size lentiviral vectors (LV). HSC showed higher transduction efficiency if transiently exposed to proteasome inhibitor MG132 (41.8% vs 10.7%, p<0.0001). Treatment with MG132 (0.5 μM) retained its beneficial effect with 3 different LV of increasing size up to 10.9 Kb (p<0.01). We extended, for the first time, the application of proteasome inhibition to the transduction of T lymphocytes. A transient exposure to MG132 significantly improved lentiviral T-cell transduction. The mean percentage of transduced T cells progressively increased from 13.5% of untreated cells, to 21% (p=0.3), 30% (p=0.03) and 37% (p=0.01) of T lymphocytes that were pre-treated with MG132 at 0.1, 0.5 and 1 μM, respectively. MG132 did not affect viability or functionality of HSC or T cells, nor significantly increased the number of integrated vector copies. Transient proteasome inhibition appears as a new procedure to safely enhance lentiviral transduction of HSC and T lymphocytes with low viral doses. This approach could be useful in settings where the use of large size vectors may impair optimal viral production.
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http://dx.doi.org/10.1016/j.jbiotec.2011.09.001DOI Listing
December 2011

TCR transfer induces TCR-mediated tonic inhibition of RAG genes in human T cells.

Mol Immunol 2011 Jul 8;48(12-13):1369-76. Epub 2011 Apr 8.

Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy.

Induction of the TCR signaling pathway terminates the expression of RAG genes, and a link between this pathway and their transcriptional control is evident from the recent demonstration of their re-expression if the TCR is subsequently lost or down-regulated. Since unstimulated T cells display a steady-state level of "tonic" TCR signaling, i.e. in the absence of any antigenic stimulus, it was uncertain whether this control was exerted through ligand-dependent or ligand-independent TCR signaling. Here we demonstrate for the first time that exogenous TCR α and β chains transferred into the human immature RAG(+) T cell line Sup-T1 by lentiviral transduction inhibit RAG expression through tonic signaling, and that this inhibition could itself be reverted by pharmacological tonic pathway inhibitors. We also suggest that mature T cells already expressing an endogenous TCR on their surface maintain some levels of plasticity at the RAG locus when their basal TCR signaling is interfered with. Lastly, we show that the TCR constructs employed in TCR gene therapy do not possess the same basal signaling transduction capability, a feature that may have therapeutic implications.
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http://dx.doi.org/10.1016/j.molimm.2011.02.015DOI Listing
July 2011

T cell receptor (TCR) gene transfer with lentiviral vectors allows efficient redirection of tumor specificity in naive and memory T cells without prior stimulation of endogenous TCR.

Hum Gene Ther 2009 Dec;20(12):1576-88

Laboratory of Cancer Immunology, Institute for Cancer Research and Treatment (IRCC), Candiolo, 10060, Turin, Italy.

We investigated the possibility of introducing exogenous T cell receptor (TCR) genes into T cells by lentiviral transduction, without prior stimulation of endogenous TCR with anti-CD3. TCR transfer is used to impose tumor antigen specificity on recipient T cells, but sustained activation required for retroviral transduction may affect the clinical efficacy of engineered T cells. Cytokine stimulation makes T cells susceptible to lentiviral transduction in the absence of TCR triggering, but this advantage has never been exploited for TCR transfer. Autoimmune diseases are a source of high-affinity TCRs specific for self/tumor antigens. We selected, from a patient with vitiligo, a Mart1-specific TCR based on intrinsic interchain pairing properties and functional avidity. After lentiviral transduction of human peripheral blood mononuclear cells, preferential pairing of exogenous alpha and beta chains was observed, together with effective recognition of Mart1(+) melanoma cells. We tested transduction efficiency on various T cell subsets prestimulated with interleukin (IL)-2, IL-7, IL-15, and IL-21 (alone or in combination). Both naive and unfractionated CD8(+) T cells could be transduced without requiring endogenous TCR triggering. IL-7 plus IL-15 was the most powerful combination, allowing high levels of transgene expression without inducing T cell differentiation (34 +/- 5% Mart1-TCR(+) cells in naive CD8(+) and 16 +/- 6% in unfractionated CD8(+)). Cytokine-prestimulated, Mart1-redirected naive and unfractionated CD8(+) cells expanded better than CD3-CD28-prestimulated counterparts in response to both peptide-pulsed antigen-presenting cells and Mart1(+) melanoma cells. This strategy allows the generation of tumor-specific T cells encompassing truly naive T cells, endowed with an intact proliferative potential and a preserved differentiation stage.
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http://dx.doi.org/10.1089/hum.2009.117DOI Listing
December 2009

Clonal CD8+ TCR-Vbeta expanded populations with effector memory phenotype in Churg Strauss syndrome.

Clin Immunol 2008 Jul 23;128(1):94-102. Epub 2008 May 23.

Allergologia e Immunologia Clinica, University of Torino Medical School, Italy.

Churg Strauss Syndrome (CSS) is a systemic vasculitis in which oligoclonal T cell expansions might be involved in the pathogenesis. Combined analysis of TCR-Vbeta expression profile by flow cytometry and of TCR gene rearrangement by heteroduplex PCR was used to detect and characterize T cell expansions in 8 CSS patients, 10 asthmatics and 42 healthy subjects. In all CSS patients one or two Vbeta families were expanded among CD8+ cells, with an effector memory phenotype apt to populate tissues and inflammatory sites. Heteroduplex PCR showed the presence of one or more clonal TCR rearrangements, which reveals monoclonal or oligoclonal T cells subpopulations. After purification with a Vbeta specific monoclonal antibody, each CD8+/Vbeta+ expanded family showed a single TCR rearrangement, clearly suggestive of monoclonality. All CD8+ expansions were detectable throughout the disease course. TCR-Vbeta expanded or deleted populations were not observed in asthmatic patients. Clonal CD8+/Vbeta+ T cell expansions might be useful as a disease marker.
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http://dx.doi.org/10.1016/j.clim.2008.03.505DOI Listing
July 2008

Ab-induced ectodomain shedding mediates hepatocyte growth factor receptor down-regulation and hampers biological activity.

Proc Natl Acad Sci U S A 2006 Mar 17;103(13):5090-5. Epub 2006 Mar 17.

Division of Molecular Oncology, Institute for Cancer Research and Treatment (IRCC), University of Turin Medical School, 10060 Candiolo, Italy.

Targeting tyrosine kinase receptors (RTKs) with specific Abs is a promising therapeutic approach for cancer treatment, although the molecular mechanism(s) responsible for the Abs' biological activity are not completely known. We targeted the transmembrane RTK for hepatocyte growth factor (HGF) with a monoclonal Ab (DN30). In vitro, chronic treatment of carcinoma cell lines resulted in impairment of HGF-induced signal transduction, anchorage-independent growth, and invasiveness. In vivo, administration of DN30 inhibited growth and metastatic spread to the lung of neoplastic cells s.c. transplanted into immunodeficient nu/nu mice. This Ab efficiently down-regulates HGF receptor through a molecular mechanism involving a double proteolytic cleavage: (i) cleavage of the extracellular portion, resulting in "shedding" of the ectodomain, and (ii) cleavage of the intracellular domain, which is rapidly degraded by the proteasome. Interestingly, the "decoy effect" generated by the shed ectodomain, acting as a dominant negative molecule, enhanced the inhibitory effect of the Ab.
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http://dx.doi.org/10.1073/pnas.0508156103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1458799PMC
March 2006

Lentiviral transduction of primary myeloma cells with CD80 and CD154 generates antimyeloma effector T cells.

Hum Gene Ther 2005 Apr;16(4):445-56

Laboratory of Cancer Immunology, Institute for Cancer ReEsearch and Treatment, University of Turin-School of Medicine, Torino, Italy.

The development of immunotherapy approaches designed to obtain tumor-specific T cells might help eradicate residual malignant cells in multiple myeloma (MM) patients. To this end, we used autologous primary MM cells as antigen-presenting cells (APC). Gene transfer of both CD80 and CD154 by lentiviral vectors was necessary to significantly improve the APC function of human MM cells. Simultaneous CD80/CD154 expression on MM cells allowed the generation of CD8+ T cells that recognized unmodified MM cells in 11 of 16 cases, specifically in six of six patients with low-stage disease, but only in five of ten patients with advanced disease. The activity of CD8+ T cells was MHC restricted and MM specific. In seven of seven cases, CD8+ T cell activity was inhibited by monoclonal antibodies against HLA class I, and in four of four cases, CD8+ T cells recognized autologous MM cells but not autologous normal B and T lymphocytes nor bone marrow stromal cells. In addition, the activity of CD8+ T cells was directed against allogeneic MM cells that shared at least one MHC allele with the autologous counterpart, but not against MHC mismatched MM cells. These data lay the ground for the isolation of new MM antigens and for the design of vaccination protocols with primary MM cells genetically engineered to express immunostimulatory molecules.
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http://dx.doi.org/10.1089/hum.2005.16.445DOI Listing
April 2005

Leukemia-derived immature dendritic cells differentiate into functionally competent mature dendritic cells that efficiently stimulate T cell responses.

J Immunol 2004 Aug;173(4):2855-65

Laboratory of Cancer Immunology, Institute for Cancer Research and Treatment, Candiolo, Italy.

Primary acute myeloid leukemia cells can be induced to differentiate into dendritic cells (DC). In the presence of GM-CSF, TNF-alpha, and/or IL-4, leukemia-derived DC are obtained that display features of immature DC (i-DC). The aim of this study was to determine whether i-DC of leukemic origin could be further differentiated into mature DC (m-DC) and to evaluate the possibility that leukemic m-DC could be effective in vivo as a tumor vaccine. Using CD40L as maturating agent, we show that leukemic i-DC can differentiate into cells that fulfill the phenotypic criteria of m-DC and, compared with normal counterparts, are functionally competent in vitro in terms of: 1) production of cytokines that support T cell activation and proliferation and drive Th1 polarization; 2) generation of autologous CD8(+) CTLs and CD4(+) T cells that are MHC-restricted and leukemia-specific; 3) migration from tissues to lymph nodes; 4) amplification of Ag presentation by monocyte attraction; 5) attraction of naive/resting and activated T cells. Irradiation of leukemic i-DC after CD40L stimulation did not affect their differentiating and functional capacity. Our data indicate that acute myeloid leukemia cells can fully differentiate into functionally competent m-DC and lay the ground for testing their efficacy as a tumor vaccine.
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http://dx.doi.org/10.4049/jimmunol.173.4.2855DOI Listing
August 2004

The characterization of chemokine production and chemokine receptor expression reveals possible functional cross-talks in AML blasts with monocytic differentiation.

Exp Hematol 2003 Jun;31(6):495-503

University Division of Clinical Immunology and Hematology, Ospedale Mauriziano Umberto I, Turin, Italy.

Objective: The mechanisms regulating the trafficking of leukemic myeloid blasts are poorly understood. A differential expression of chemokines and chemokine receptors might account for some aspects of the pattern of invasion and accumulation of leukemic cells. We aimed at defining the pattern of chemokine and chemokine receptor expression of acute myeloid leukemia (AML) blasts in comparison with their putative normal cell counterparts.

Patients And Methods: Twenty-five cases of AML were analyzed by flow cytometry for the expression of several chemokine receptors and by RT-PCR for the expression of relevant chemokines. For selected chemokines, the production was confirmed by ELISA. AML blasts were also assessed for their migration capacity in response to autologous supernatants and recombinant chemokines.

Results: Undifferentiated AML (MO-M1 and some M2) express only CXCR4 on their surface and produce mainly inflammatory chemokines, resembling normal CD34+ progenitors. More differentiated AML (M4-M5 and some M2) have a more diversified receptor repertoire and, besides CXCR4, express the receptors for inflammatory chemokines and produce both constitutive and inflammatory chemokines, resembling resting and activated monocytes. In particular, M4-M5 blasts produce MCP-1 and MIP-3alpha and also express their specific receptors (CCR2 and, to a lesser extent, CCR6) and migrate in vitro in response to MCP-1 and MIP-3alpha and to their own supernatant. A significant correlation between extramedullary involvement and coexpression of MCP-1/CCR2 was found.

Conclusions: These data suggest that chemokines and their receptors segregate within the different FAB subtypes and, by allowing cross-talk among members of the malignant clone, might help to explain some aspects of the pattern of invasion in AML with monocytic differentiation.
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http://dx.doi.org/10.1016/s0301-472x(03)00066-3DOI Listing
June 2003

CD100/Plexin-B1 interactions sustain proliferation and survival of normal and leukemic CD5+ B lymphocytes.

Blood 2003 Mar 24;101(5):1962-9. Epub 2002 Oct 24.

Department of Oncological Sciences, University of Torino, Institute for Cancer Research and Treatment (IRCC), Candiolo (TO) and Division of Clinical Immunology and Hematology, Ospedale Mauriziano Umberto I, Torino, Italy.

Growth and survival of chronic B-cell tumors are favored by the malignant cell's capacity to respond to selected microenvironmental stimuli provided by nontumoral bystander cells. To investigate which mechanisms operate in these crosstalks and whether they are malignancy-related or reproduce the mechanisms used by normal B cells we have studied the expression and functional role of semaphorin CD100 (now called Sema4D) in chronic lymphocytic leukemia (CLL) cells and normal CD5+ B cells. We demonstrate here that (1) leukemic and normal CD5+ B lymphocytes uniformly express CD100; (2) the CD100 high-affinity receptor Plexin-B1 is expressed by bone marrow stromal cells, follicular dendritic cells, and activated T lymphocytes, and is thus available to CD100+ lymphocytes in different specific microenvironments; and (3) upon interaction between CD100 and Plexin-B1 both CLL and normal CD5+ B cells increase their proliferative activity and extend their life span. These findings establish that Plexin-B1 is an easily accessible receptor for CD100 within the immune system. The encounter of CD100+ leukemic cells with Plexin-B1 may promote the proliferation and survival of malignant cells. The crosstalk operated by the CD100/Plexin-B1 interaction is not malignancy related but reproduces a mechanism used by normal CD5+ B cells.
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http://dx.doi.org/10.1182/blood-2002-05-1339DOI Listing
March 2003