Bitter Taste Receptor Agonist Denatonium Inhibits Stemness Characteristics in Hematopoietic Stem/Progenitor Cells.

Bone marrow microenvironmental stimuli profoundly impact hematopoietic stem cell fate and biology. As G protein-coupled receptors, the bitter taste receptors (TAS2Rs) are key in transmitting extracellular stimuli into an intracellular response, within the oral cavity but also in extraoral tissues. Their expression in the bone marrow (BM)-derived cells suggests their involvement in sensing the BM microenvironmental fluctuation. In the present study, we demonstrated that umbilical cord blood (UCB)-derived CD34+ cells express fully functional TAS2Rs along with the signal transduction cascade components and their activation by the prototypical agonist, denatonium benzoate, significantly modulated genes involved in stemness maintenance and regulation of cell trafficking. The activation of these specific pathways was confirmed in functional in vitro experiments. Denatonium exposure exerted an antiproliferative effect on UCB-derived CD34+ cells, mainly affecting the most undifferentiated progenitor frequency. It also reduced their clonogenicity and repopulating potential in vitro. In addition, the TAS2R signaling activation impaired the UCB-derived CD34+ cell trafficking, mainly reducing the migration toward the chemoattractant agent CXCL12 and modulating the expression of the adhesion molecules CD62L, CD49d, and CD29. In conclusion, our results in UCB-derived CD34+ cells expand the observation of TAS2R expression in the setting of BM-resident cells and shed light on the role of TAS2Rs in the extrinsic regulation of hematopoietic stem cell functions.

Extracellular vesicle-associated IGF2BP3 tunes Ewing sarcoma cell migration and affects PI3K/Akt pathway in neighboring cells.

Ewing sarcoma (EWS) is a challenging pediatric cancer characterized by vast intra-tumor heterogeneity. We evaluated the RNA-binding protein IGF2BP3, whose high expression correlates with a poor prognosis and an elevated tendency of metastases, as a possible soluble mediator of inter-cellular communication in EWS. Our data demonstrate that (i) IGF2BP3 is detected in cell supernatants, and it is released inside extracellular vesicles (EVs); (ii) EVs from IGF2BP3-positive or IGF2BP3-negative EWS cells reciprocally affect cell migration but not the proliferation of EWS recipient cells; (iii) EVs derived from IGF2BP3-silenced cells have a distinct miRNA cargo profile and inhibit the PI3K/Akt pathway in recipient cells; (iv) the 11 common differentially expressed miRNAs associated with IGF2BP3-positive and IGF2BP3-negative EVs correctly group IGF2BP3-positive and IGF2BP3-negative clinical tissue specimens. Overall, our data suggest that IGF2BP3 can participate in the modulation of phenotypic heterogeneity.

Oncogenic Vav1-Myo1f induces therapeutically targetable macrophage-rich tumor microenvironment in peripheral T cell lymphoma.

Peripheral T cell lymphoma not otherwise specified (PTCL-NOS) comprises heterogeneous lymphoid malignancies characterized by pleomorphic lymphocytes and variable inflammatory cell-rich tumor microenvironment. Genetic drivers in PTCL-NOS include genomic alterations affecting the VAV1 oncogene; however, their specific role and mechanisms in PTCL-NOS remain incompletely understood. Here we show that expression of Vav1-Myo1f, a recurrent PTCL-associated VAV1 fusion, induces oncogenic transformation of CD4+ T cells. Notably, mouse Vav1-Myo1f lymphomas show T helper type 2 features analogous to high-risk GATA3+ human PTCL. Single-cell transcriptome analysis reveals that Vav1-Myo1f alters T cell differentiation and leads to accumulation of tumor-associated macrophages (TAMs) in the tumor microenvironment, a feature linked with aggressiveness in human PTCL. Importantly, therapeutic targeting of TAMs induces strong anti-lymphoma effects, highlighting the lymphoma cells' dependency on the microenvironment. These results demonstrate an oncogenic role for Vav1-Myo1f in the pathogenesis of PTCL, involving deregulation in T cell polarization, and identify the lymphoma-associated macrophage-tumor microenvironment as a therapeutic target in PTCL.

Targeting CD99 Compromises the Oncogenic Effects of the Chimera EWS-FLI1 by Inducing Reexpression of Zyxin and Inhibition of GLI1 Activity.

Ewing sarcoma, a highly aggressive pediatric tumor, is driven by EWS-FLI1, an oncogenic transcription factor that remodels the tumor genetic landscape. Epigenetic mechanisms play a pivotal role in Ewing sarcoma pathogenesis, and the therapeutic value of compounds targeting epigenetic pathways is being identified in preclinical models. Here, we showed that modulation of CD99, a cell surface molecule highly expressed in Ewing sarcoma cells, may alter transcriptional dysregulation in Ewing sarcoma through control of the zyxin-GLI1 axis. Zyxin is transcriptionally repressed, but GLI1 expression is maintained by EWS-FLI1. We demonstrated that targeting CD99 with antibodies, including the human diabody C7, or genetically inhibiting CD99 is sufficient to increase zyxin expression and induce its dynamic nuclear accumulation. Nuclear zyxin functionally affects GLI1, inhibiting targets such as NKX2-2, cyclin D1, and PTCH1 and upregulating GAS1, a tumor suppressor protein negatively regulated by SHH/GLI1 signaling. We used a battery of functional assays to demonstrate (i) the relationship between CD99/zyxin and tumor cell growth/migration and (ii) how CD99 deprivation from the Ewing sarcoma cell surface is sufficient to specifically affect the expression of some crucial EWS-FLI1 targets, both in vitro and in vivo, even in the presence of EWS-FLI1. This article reveals that the CD99/zyxin/GLI1 axis is promising therapeutic target for reducing Ewing sarcoma malignancy.

Integrated Molecular Characterization of Patient-Derived Models Reveals Therapeutic Strategies for Treating CIC-DUX4 Sarcoma.

Capicua-double homeobox 4 (CIC-DUX4)-rearranged sarcomas (CDS) are extremely rare, highly aggressive primary sarcomas that represent a major therapeutic challenge. Patients are treated according to Ewing sarcoma protocols, but CDS-specific therapies are strongly needed. In this study, RNA sequencing was performed on patient samples to identify a selective signature that differentiates CDS from Ewing sarcoma and other fusion-driven sarcomas. This signature was used to validate the representativeness of newly generated CDS experimental models-patient-derived xenografts (PDX) and PDX-derived cell lines-and to identify specific therapeutic vulnerabilities. Annotation analysis of differentially expressed genes and molecular gene validation highlighted an HMGA2/IGF2BP/IGF2/IGF1R/AKT/mTOR axis that characterizes CDS and renders the tumors particularly sensitive to combined treatments with trabectedin and PI3K/mTOR inhibitors. Trabectedin inhibited IGF2BP/IGF2/IGF1R activity, but dual inhibition of the PI3K and mTOR pathways was required to completely dampen downstream signaling mediators. Proof-of-principle efficacy for the combination of the dual AKT/mTOR inhibitor NVP-BEZ235 (dactolisib) with trabectedin was obtained in vitro and in vivo using CDS PDX-derived cell lines, demonstrating a strong inhibition of local tumor growth and multiorgan metastasis. Overall, the development of representative experimental models (PDXs and PDX-derived cell lines) has helped to identify the unique sensitivity of the CDS to AKT/mTOR inhibitors and trabectedin, revealing a mechanism-based therapeutic strategy to fight this lethal cancer. SIGNIFICANCE: This study identifies altered HMGA2/IGF2BP/IGF2 signaling in CIC-DUX4 sarcomas and provides proof of principle for combination therapy with trabectedin and AKT/mTOR dual inhibitors to specifically combat the disease.

Restriction Factors expression decreases in HIV-1 patients after cART.

Activation of interferon (IFN) mediated responses and the consequent expression of restriction factors (RFs) represent an early line of defense against HIV-1 infection. The levels of viral replication and the antiviral are among the determinants influencing RFs' expression pattern. A deeper understanding of the molecular mechanisms regulating RFs activity and their relationship with viral replication factors might lead to new therapeutic strategies based on the enhancement of immune response against the virus. The aim of this study is to perform a longitudinal evaluation of the variations in the levels of a group of selected RFs (APOBEC3G, BST2, TRIM5α, MX2, SAMHD1, SERINC3/5, IFI16 and STING) to determine the impact of cART on their expression in HIV-1 positive patients. Together with RFs expression, immunological and virological parameters (plasma HIV1-RNA load and total HIV1-DNA) were longitudinally evaluated in a cohorts fourteen HIV-1 cART na ve patients, who were evaluated at diagnosis (T0) and followed at 4 (T1) and 8 (T2) months after starting cART. Fourteen long-term treated patients who achieved sustained undetectable viremia for at least 2 years were also included in the study as a reference group. We observed a restoration of immunological conditions during cART, together with a progressive decrease of HIV1-RNA load, which became undetectable at 8 months after starting treatment. On the other hand, despite showing a trend towards decrease, total HIV1-DNA remained detectable after reaching viral suppression, similarly to what observed in long term treated patients. The expression of APOBEC3G, SAMHD1, BST2, IFI16, SERINC3, and SERINC5 was higher at the time of diagnosis and decreased significantly during therapy, reaching levels similar to the ones observed in virally suppressed patients. On the other hand, MX2 and TRIM5a high expression values up to T0, reaching lower levels immediately after the initiation of cART treatment. Correlation analysis showed a positive association between the expression levels of APOBEC3G, IFI16, MX2, SAMHD1, SERINC3 and TRIM5α with the HIV-1 viral load. On the contrary, no significant association was observed for BST2, SERINC5 and STING, even BST2 expression showed a tendency to correlate with viral load. We observed a tendency for a positive association of MX2, SAMHD1 and SERINC5 with the size of viral reservoir and a trend for a negative association for STING. STING appeared also as the only one factor whose expression correlates with the CD4 count and the CD4/CD8 ratio. Our data confirm the correlation between viral replication and expression of RFs, with, the levels of cellular defense proteins decreasing in parallel to the reduction of viral replication.

Corrigendum: Denatonium as a Bitter Taste Receptor Agonist Modifies Transcriptomic Profile and Functions of Acute Myeloid Leukemia Cells.

[This corrects the article DOI: 10.3389/fonc.2020.01225.].

Denatonium as a Bitter Taste Receptor Agonist Modifies Transcriptomic Profile and Functions of Acute Myeloid Leukemia Cells.

The contribution of cell-extrinsic factors in Acute Myeloid Leukemia (AML) generation and persistence has gained interest. Bitter taste receptors (TAS2Rs) are G protein-coupled receptors known for their primary role as a central warning signal to induce aversion toward noxious or harmful substances. Nevertheless, the increasing amount of evidence about their extra-oral localization has suggested a wider function in sensing microenvironment, also in cancer settings. In this study, we found that AML cells express functional TAS2Rs. We also highlighted a significant association between the modulation of some TAS2Rs and the poor-prognosis AML groups, i.e., TP53- and TET2-mutated, supporting a potential role of TAS2Rs in AML cell biology. Gene expression profile analysis showed that TAS2R activation with the prototypical agonist, denatonium benzoate, significantly modulated a number of genes involved in relevant AML cellular processes. Functional assay substantiated molecular data and indicated that denatonium reduced AML cell proliferation by inducing cell cycle arrest in G0/G1 phase or induced apoptosis via caspase cascade activation. Moreover, denatonium exposure impaired AML cell motility and migratory capacity, and inhibited cellular respiration by decreasing glucose uptake and oxidative phosphorylation. In conclusion, our results in AML cells expand the observation of cancer TAS2R expression to the setting of hematological neoplasms and shed light on a role of TAS2Rs in the extrinsic regulation of leukemia cell functions.

Inhibition of Methyltransferase DOT1L Sensitizes to Sorafenib Treatment AML Cells Irrespective of MLL-Rearrangements: A Novel Therapeutic Strategy for Pediatric AML.

Pediatric acute myeloid leukemia (AML) is an aggressive malignancy with poor prognosis for which there are few effective targeted approaches, despite the numerous genetic alterations, including MLL gene rearrangements (MLL-r). The histone methyltransferase DOT1L is involved in supporting the proliferation of MLL-r cells, for which a target inhibitor, Pinometostat, has been evaluated in a clinical trial recruiting pediatric MLL-r leukemic patients. However, modest clinical effects have been observed. Recent studies have reported that additional leukemia subtypes lacking MLL-r are sensitive to DOT1L inhibition. Here, we report that targeting DOT1L with Pinometostat sensitizes pediatric AML cells to further treatment with the multi-kinase inhibitor Sorafenib, irrespectively of MLL-r. DOT1L pharmacologic inhibition induces AML cell differentiation and modulates the expression of genes with relevant roles in cancer development. Such modifications in the transcriptional program increase the apoptosis and growth suppression of both AML cell lines and primary pediatric AML cells with diverse genotypes. Through ChIP-seq analysis, we identified the genes regulated by DOT1L irrespective of MLL-r, including the Sorafenib target BRAF, providing mechanistic insights into the drug combination activity. Our results highlight a novel therapeutic strategy for pediatric AML patients.

Deregulation of miRNAs-cMYC circuits is a key event in refractory celiac disease type-2 lymphomagenesis.

A percentage of celiac disease (CD) patients develop refractory type-2 disease (RCD2), a condition associated with increased risk of enteropathy-associated T-cell-lymphoma (EATL) and without therapeutic option. Therefore, we profiled the miRNome in series of peripheral T-cell lymphomas (PTCLs), CD, RCD1 or 2 and in the murine interleukin-15 (IL15)-transgenic (TG) model of RCD. The transcriptome was analyzed in 18 intestinal T-cell lymphomas (ITLs). Bioinformatics pipelines provided significant microRNA (miRNA) lists and predicted targets that were confirmed in a second set of patients. Our data show that ITLs have a unique miRNA profile with respect to other PTCLs. The c-MYC regulated miR-17/92 cluster distinguishes monomorphic epitheliotropic ITL (MEITL) from EATL and prognosticates EATL outcome. These miRNAs are decreased in IL15-TG mice upon Janus kinase (JAK) inhibition. The random forest algorithm identified a signature of 38 classifier miRNAs, among which, the miR-200 and miR-192/215 families were progressively lost in RCD2 and ITL-CD, whereas miR-17/92 and C19MC miRNAs were up-regulated. Accordingly, SMAD3, MDM2, c-Myc and activated-STAT3 were increased in RCD2 and EATL tissues while JAK inhibition in IL15-TG mice restored their levels to baseline. Our data suggest that miRNAs circuit supports activation of STAT3 and c-Myc oncogenic signaling in RCD2, thus contributing to lymphomagenesis. This novel understanding might pave the way to personalized medicine approaches for RCD and EATL.

Whole exome sequencing reveals mutations in FAT1 tumor suppressor gene clinically impacting on peripheral T-cell lymphoma not otherwise specified.

Peripheral T-cell lymphoma not otherwise specified represents a diagnostic category comprising clinically, histologically, and molecularly heterogeneous neoplasms that are poorly understood. The genetic landscape of peripheral T-cell lymphoma not otherwise specified remains largely undefined, only a few sequencing studies having been conducted so far. In order to improve our understanding of the genetics of this neoplasm, we performed whole exome sequencing along with RNA-sequencing in a discovery set of 21 cases. According to whole exome sequencing results and mutations previously reported in other peripheral T-cell lymphomas, 137 genes were sequenced by a targeted deep approach in 71 tumor samples. In addition to epigenetic modifiers implicated in all subtypes of T-cell neoplasm (TET2, DNMT3A, KMT2D, KMT2C, SETD2), recurrent mutations of the FAT1 tumor suppressor gene were for the first time recorded in 39% of cases. Mutations of the tumor suppressor genes LATS1, STK3, ATM, TP53, and TP63 were also observed, although at a lower frequency. Patients with FAT1 mutations showed inferior overall survival compared to those with wild-type FAT1. Although peripheral T-cell lymphoma not otherwise specified remains a broad category also on molecular grounds, the present study highlights that FAT1 mutations occur in a significant proportion of cases, being provided with both pathogenetic and prognostic impact.

Correction: Whole exome sequencing reveals mutations in FAT1 tumor suppressor gene clinically impacting on peripheral T-cell lymphoma not otherwise specified.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Prospective assessment of NGS-detectable mutations in CML patients with nonoptimal response: the NEXT-in-CML study.

In chronic myeloid leukemia (CML) patients, tyrosine kinase inhibitors (TKIs) may select for drug-resistant BCR-ABL1 kinase domain (KD) mutants. Although Sanger sequencing (SS) is considered the gold standard for BCR-ABL1 KD mutation screening, next-generation sequencing (NGS) has recently been assessed in retrospective studies. We conducted a prospective, multicenter study (NEXT-in-CML) to assess the frequency and clinical relevance of low-level mutations and the feasibility, cost, and turnaround times of NGS-based BCR-ABL1 mutation screening in a routine setting. A series of 236 consecutive CML patients with failure (n = 124) or warning (n = 112) response to TKI therapy were analyzed in parallel by SS and NGS in 1 of 4 reference laboratories. Fifty-one patients (22 failure, 29 warning) who were negative for mutations by SS had low-level mutations detectable by NGS. Moreover, 29 (27 failure, 2 warning) of 60 patients who were positive for mutations by SS showed additional low-level mutations. Thus, mutations undetectable by SS were identified in 80 out of 236 patients (34%), of whom 42 (18% of the total) had low-level mutations somehow relevant for clinical decision making. Prospective monitoring of mutation kinetics demonstrated that TKI-resistant low-level mutations are invariably selected if the patients are not switched to another TKI or if they are switched to a inappropriate TKI or TKI dose. The NEXT-in-CML study provides for the first time robust demonstration of the clinical relevance of low-level mutations, supporting the incorporation of NGS-based BCR-ABL1 KD mutation screening results in the clinical decision algorithms.

Genetic drivers of oncogenic pathways in molecular subgroups of peripheral T-cell lymphoma.

Peripheral T-cell lymphoma (PTCL) is a group of complex clinicopathological entities, often associated with an aggressive clinical course. Angioimmunoblastic T-cell lymphoma (AITL) and PTCL-not otherwise specified (PTCL-NOS) are the 2 most frequent categories, accounting for >50% of PTCLs. Gene expression profiling (GEP) defined molecular signatures for AITL and delineated biological and prognostic subgroups within PTCL-NOS (PTCL-GATA3 and PTCL-TBX21). Genomic copy number (CN) analysis and targeted sequencing of these molecular subgroups revealed unique CN abnormalities (CNAs) and oncogenic pathways, indicating distinct oncogenic evolution. PTCL-GATA3 exhibited greater genomic complexity that was characterized by frequent loss or mutation of tumor suppressor genes targeting the CDKN2A /B-TP53 axis and PTEN-PI3K pathways. Co-occurring gains/amplifications of STAT3 and MYC occurred in PTCL-GATA3. Several CNAs, in particular loss of CDKN2A, exhibited prognostic significance in PTCL-NOS as a single entity and in the PTCL-GATA3 subgroup. The PTCL-TBX21 subgroup had fewer CNAs, primarily targeting cytotoxic effector genes, and was enriched in mutations of genes regulating DNA methylation. CNAs affecting metabolic processes regulating RNA/protein degradation and T-cell receptor signaling were common in both subgroups. AITL showed lower genomic complexity compared with other PTCL entities, with frequent co-occurring gains of chromosome 5 (chr5) and chr21 that were significantly associated with IDH2 R172 mutation. CN losses were enriched in genes regulating PI3K-AKT-mTOR signaling in cases without IDH2 mutation. Overall, we demonstrated that novel GEP-defined PTCL subgroups likely evolve by distinct genetic pathways and provided biological rationale for therapies that may be investigated in future clinical trials.

Blastic plasmacytoid dendritic cell neoplasm: genomics mark epigenetic dysregulation as a primary therapeutic target.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy for which there is still no effective therapy. In order to identify genetic alterations useful for a new treatment design, we used whole-exome sequencing to analyze 14 BPDCN patients and the patient-derived CAL-1 cell line. The functional enrichment analysis of mutational data reported the epigenetic regulatory program to be the most significantly undermined (P<0.0001). In particular, twenty-five epigenetic modifiers were found mutated (e.g. ASXL1, TET2, SUZ12, ARID1A, PHF2, CHD8); ASXL1 was the most frequently affected (28.6% of cases). To evaluate the impact of the identified epigenetic mutations at the gene-expression and Histone H3 lysine 27 trimethylation/acetylation levels, we performed additional RNA and pathology tissue-chromatin immunoprecipitation sequencing experiments. The patients displayed enrichment in gene signatures regulated by methylation and modifiable by decitabine administration, shared common H3K27-acetylated regions, and had a set of cell-cycle genes aberrantly up-regulated and marked by promoter acetylation. Collectively, the integration of sequencing data showed the potential of a therapy based on epigenetic agents. Through the adoption of a preclinical BPDCN mouse model, established by CAL-1 cell line xenografting, we demonstrated the efficacy of the combination of the epigenetic drugs 5'-azacytidine and decitabine in controlling disease progression in vivo.

Aneuploid acute myeloid leukemia exhibits a signature of genomic alterations in the cell cycle and protein degradation machinery.

BACKGROUND: Aneuploidy occurs in more than 20% of acute myeloid leukemia (AML) cases and correlates with an adverse prognosis. METHODS: To understand the molecular bases of aneuploid acute myeloid leukemia (A-AML), this study examined the genomic profile in 42 A-AML cases and 35 euploid acute myeloid leukemia (E-AML) cases. RESULTS: A-AML was characterized by increased genomic complexity based on exonic variants (an average of 26 somatic mutations per sample vs 15 for E-AML). The integration of exome, copy number, and gene expression data revealed alterations in genes involved in DNA repair (eg, SLX4IP, RINT1, HINT1, and ATR) and the cell cycle (eg, MCM2, MCM4, MCM5, MCM7, MCM8, MCM10, UBE2C, USP37, CK2, CK3, CK4, BUB1B, NUSAP1, and E2F) in A-AML, which was associated with a 3-gene signature defined by PLK1 and CDC20 upregulation and RAD50 downregulation and with structural or functional silencing of the p53 transcriptional program. Moreover, A-AML was enriched for alterations in the protein ubiquitination and degradation pathway (eg, increased levels of UHRF1 and UBE2C and decreased UBA3 expression), response to reactive oxygen species, energy metabolism, and biosynthetic processes, which may help in facing the unbalanced protein load. E-AML was associated with BCOR/BCORL1 mutations and HOX gene overexpression. CONCLUSIONS: These findings indicate that aneuploidy-related and leukemia-specific alterations cooperate to tolerate an abnormal chromosome number in AML, and they point to the mitotic and protein degradation machineries as potential therapeutic targets.

LncRNAs as novel players in hepatocellular carcinoma recurrence.

Long non-coding RNAs (lncRNAs) are ncRNAs more than 200 nucleotides long that participate to a wide range of biological functions. However, their role in cancer is poorly known. By using an NGS-based approach we analyzed the intragenic and poliA-lncRNAs in hepatocellular carcinoma (HCC) and we assayed the relationships between their deregulated expression and clinical-pathological characteristics. The expression profile of lncRNAs was studied in a discovery series of 28 HCC and matched cirrhosis and was validated in an independent cohort of 32 HCC patients both in tissue and serum. The correlation between lncRNA expression and clinical-pathological variables, EMT markers and putative sponged microRNAs level were investigated. Functional experiments were performed in HCC-derived cell lines to clarify the role of selected lncRNAs in HCC. A panel of deregulated lncRNAs differentiated HCC from cirrhotic tissue. CASC9 and LUCAT1 were up-regulated in a subset of HCC-derived cell lines and in half of HCCs which displayed a lower recurrence after surgery. LUCAT1 and CASC9 silencing increased cell motility and invasion capability in HCC cells and influenced the EMT phenotype. LUCAT1 was demonstrated to directly sponge the onco-miR-181d-5p. Both LUCAT1 and CASC9 were secreted in exosomes, and higher circulating CASC9 levels were associated with tumor size and HCC recurrence after surgery, suggesting its potential usage as putative non-invasive prognostic biomarker of recurrence.

The emerging role of GSK-3ß in the pathobiology of classical Hodgkin lymphoma.

AIMS: Glycogen synthase kinase-3 beta (GSK-3ß) is a serine/threonine kinase involved in glycogen metabolism, cell cycle progression, differentiation, embryogenesis, migration, metabolism, survival and cellular senescence. Its main biological function is to inhibit ß-catenin by sequestration and promotion of its proteasomal degradation in the Wnt canonical pathway; however, GSK-3ß interacts with multiple signalling pathways, and aberrant expression of the enzyme was reported in many solid neoplasms. This study aimed to investigate the biological relevance of GSK-3ß in classical Hodgkin lymphomas (cHL). METHODS AND RESULTS: We analysed the functional status of GSK-3ß enzyme in cHL by using antibodies raised against fixation-resistant epitopes of phospho Y216 GSK-3ß (active form), phospho S9 GSK-3ß (inactive form) and ß-catenin protein. We first detected the pY216 GSK-3ß active form of the enzyme in 100 of 100 (100%) of the cases, and in line with the latter expression profile, the ß-catenin protein was found in only 12 of 100 (12%) of the samples. As reported previously in bladder cancer, pancreatic adenocarcinoma and chronic lymphocytic leukaemia, we showed an aberrant nuclear localization in the neoplastic clone of active pY216 GSK-3ß in 78 of 100 (78%) of cHL cases. CONCLUSIONS: We demonstrated the activation of GSK-3ß in cHL resulting in inhibition of the Wnt/ß-catenin signal cascade and the aberrant accumulation of its activated form in nuclei of Hodgkin Reed-Sternberg and Hodgkin cells. These findings may be relevant for future clinical studies, identifying GSK-3ß as a potential therapeutic target for cHL.

Activating mutations and translocations in the guanine exchange factor VAV1 in peripheral T-cell lymphomas.

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of non-Hodgkin lymphomas frequently associated with poor prognosis and for which genetic mechanisms of transformation remain incompletely understood. Using RNA sequencing and targeted sequencing, here we identify a recurrent in-frame deletion (VAV1 Δ778-786) generated by a focal deletion-driven alternative splicing mechanism as well as novel VAV1 gene fusions (VAV1-THAP4, VAV1-MYO1F, and VAV1-S100A7) in PTCL. Mechanistically these genetic lesions result in increased activation of VAV1 catalytic-dependent (MAPK, JNK) and non-catalytic-dependent (nuclear factor of activated T cells, NFAT) VAV1 effector pathways. These results support a driver oncogenic role for VAV1 signaling in the pathogenesis of PTCL.