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International audience; Translocation t(4;12)(q11-13;p13) is a recurrent but very rare chromosomal aberration in acute myeloid leukaemia (AML) resulting in the non-constant expression of a CHIC2/ETV6 fusion transcript. We report clinico-biological features, molecular characteristics and outcomes of 21 cases of t(4;12) including 19 AML and two myelodysplastic syndromes (MDS). Median age at the time of t(4;12) was 78 years (range, 56–88). Multilineage dysplasia was described in 10 of 19 (53%) AML cases and CD7 and/or CD56 expression in 90%. FISH analyses identified ETV6 and CHIC2 region rearrangements in respectively 18 of 18 and 15 of 17 studied cases. The t(4;12) was the sole cytogenetic abnormality in 48% of cases. The most frequent associated mutated genes were ASXL1 (n = 8/16, 50%), IDH1/2 (n = 7/16, 44%), SRSF2 (n = 5/16, 31%) and RUNX1 (n = 4/16, 25%). Interestingly, concurrent FISH and molecular analyses showed that t(4;12) can be, but not always, a founding oncogenic event. Median OS was 7.8 months for the entire cohort. In the 16 of 21 patients (76%) who received antitumoral treatment, overall response and first complete remission rates were 37% and 31%, respectively. Median progression-free survival in responders was 13.7 months. Finally, t(4;12) cases harboured many characteristics of AML with myelodysplasia-related changes (multilineage dysplasia, MDS-related cytogenetic abnormalities, frequent ASXL1 mutations) and a poor prognosis.

The chromosomal translocation t(4;11)(q21;q23), a hallmark of an aggressive form of acute lymphoblastic leukemia (ALL), encodes mixed-lineage leukemia (MLL)-AF4 oncogenic chimera that triggers aberrant transcription of genes involved in lymphocyte differentiation, including HOXA9 and MEIS1. The scaffold protein 14-3-3θ, which promotes the binding of MLL-AF4 to the HOXA9 promoter, is a target of MiR-27a, a tumor suppressor in different human leukemia cell types. We herein study the role of MiR-27a in the pathogenesis of t(4;11) ALL. Reverse transcription quantitative PCR (qPCR) reveals that MiR-27a and 14-3-3θ expression is inversely correlated in t(4;11) ALL cell lines; interestingly, MiR-27a relative expression is significantly lower in patients affected by t(4;11) ALL than in patients affected by the less severe t(12;21) leukemia. In t(4;11) leukemia cells, ectopic expression of MiR-27a decreases protein level of 14-3-3θ and of the key transcription factor RUNX1. We show for the first time that MiR-27a also targets AF4 and MLL-AF4; in agreement, MiR-27a overexpression strongly reduces AF4 and MLL-AF4 protein levels in RS4;11 cells. Consequent to AF4 and MLL-AF4 downregulation, MiR-27a overexpression negatively affects transcription of HOXA9 and MEIS1 in different t(4;11) leukemia cell lines. In agreement, we show through chromatin immunoprecipitation experiments that MiR-27a overexpression impairs the binding of MLL-AF4 to the HOXA9 promoter. Lastly, we found that MiR-27a overexpression decreases viability, proliferation, and clonogenicity of t(4;11) cells, whereas it enhances their apoptotic rate. Overall, our study identifies the first microRNAthat strikes in one hit four crucial drivers of blast transformation in t(4;11) leukemia. Therefore, MiR-27a emerges as a new promising therapeutic target for this aggressive and poorly curable form of leukemia.

Improved therapies in multiple myeloma (MM) have forced a constant risk stratification update, first Durie-Salmon, then international scoring systems (ISS), next revised-ISS (RISS) including high-risk cytogenetic abnormalities (HRCAs) such as del(17p) and t(4;14), and now R2-ISS including 1q21 gain has been proposed. Predictive value of 1q21 gain by itself or in concurrence with other cytogenetic abnormalities is evaluated in 737 real-world plasma cell neoplasm (PCN) patients under current therapies. Ten-year progression-free survival (10y-PFS) rates for patients with 2, 3 and 3 copies of 1q21 were 72.2%, 42.5% and 43.4% (P

Background Chronic myeloid leukemia is a hematologic malignancy associated with the fusion of two genes: BCR and ABL1. This fusion results from a translocation between chromosomes 9 and 22, which is called the Philadelphia chromosome. Although the Philadelphia chromosome is present in more than 90% of patients with chronic myeloid leukemia, 5–8% of patients with chronic myeloid leukemia show complex variant translocations. Herein, we report a unique case of a three-way translocation variant in chronic phase chronic myeloid leukemia. Case presentation A 40-year-old Asian male who presented with leukocytosis was diagnosed with chronic phase chronic myeloid leukemia. Cytogenetic karyotyping analysis showed 46,XY,t(4;9;22)(q21;q34;q11.2). He was treated with bosutinib and then changed to dasatinib because of intolerance, and MR4.5 (BCR-ABL/ABL ≦ 0.0032%, international scale) was achieved after 17 months of continuous treatment. Conclusion This was the 14th case of t(4;9;22), in particular, a new variant Ph translocation involved in chromosome 4q21 and the first successful case treated with tyrosine kinase inhibitors in the world. We summarize previous case reports regarding three-way variant chromosome translocation, t(4;9;22) and discuss how this rare translocation is linked to prognosis.

The chromosomal translocation t(4, 11) marks an infant acute lymphoblastic leukemia associated with dismal prognosis. This rearrangement leads to the synthesis of the MLL-AF4 chimera, which exerts its oncogenic activity by upregulating transcription of genes involved in hematopoietic differentiation. Crucial for chimera’s aberrant activity is the recruitment of the AF4/ENL/P-TEFb protein complex. Interestingly, a molecular interactor of AF4 is fibroblast growth factor receptor 2 (FGFR2). We herein analyze the role of FGFR2 in the context of leukemia using t(4, 11) leukemia cell lines. We revealed the interaction between MLL-AF4 and FGFR2 by immunoprecipitation, western blot, and immunofluorescence experiments, we also tested the effects of FGFR2 knockdown, FGFR2 inhibition, and FGFR2 stimulation on the expression of the main MLL-AF4 target genes, i.e., HOXA9 and MEIS1. Our results show that FGFR2 and MLL-AF4 interact in the nucleus of leukemia cells and that FGFR2 knockdown, which is associated with decreased expression of HOXA9 and MEIS1, impairs the binding of MLL-AF4 to the HOXA9 promoter. We also show that stimulation of leukemia cells with FGF2 increases nuclear level of FGFR2 in its phosphorylated form, as well as HOXA9 and MEIS1 expression. In contrast, preincubation with the ATP-mimetic inhibitor PD173074, before FGF2 stimulation, reduced FGFR2 nuclear amount and HOXA9 and MEIS1 transcript level, thereby indicating that MLL-AF4 aberrant activity depends on the nuclear availability of FGFR2. Overall, our study identifies FGFR2 as a new and promising therapeutic target in t(4, 11) leukemia.

The chromosomal translocation t(4;11) marks an infant acute lymphoblastic leukemia associated with dismal prognosis. This rearrangement leads to the synthesis of the MLL-AF4 chimera, which exerts its oncogenic activity by upregulating transcription of genes involved in hematopoietic differentiation. Crucial for chimera’s aberrant activity is the recruitment of the AF4/ENL/P-TEFb protein complex. Interestingly, a molecular interactor of AF4 is fibroblast growth factor receptor 2 (FGFR2). We herein analyze the role of FGFR2 in the context of leukemia using t(4;11) leukemia cell lines. We revealed the interaction between MLL-AF4 and FGFR2 by immunoprecipitation, western blot, and immunofluorescence experiments; we also tested the effects of FGFR2 knockdown, FGFR2 inhibition, and FGFR2 stimulation on the expression of the main MLL-AF4 target genes, i.e., HOXA9 and MEIS1. Our results show that FGFR2 and MLL-AF4 interact in the nucleus of leukemia cells and that FGFR2 knockdown, which is associated with decreased expression of HOXA9 and MEIS1, impairs the binding of MLL-AF4 to the HOXA9 promoter. We also show that stimulation of leukemia cells with FGF2 increases nuclear level of FGFR2 in its phosphorylated form, as well as HOXA9 and MEIS1 expression. In contrast, preincubation with the ATP-mimetic inhibitor PD173074, before FGF2 stimulation, reduced FGFR2 nuclear amount and HOXA9 and MEIS1 transcript level, thereby indicating that MLL-AF4 aberrant activity depends on the nuclear availability of FGFR2. Overall, our study identifies FGFR2 as a new and promising therapeutic target in t(4;11) leukemia.

The Revised International Staging System (R-ISS) was developed for a more accurate risk stratification of patients with symptomatic multiple myeloma (MM). However, original and subsequent validation studies of the R-ISS included relatively younger patients, many of whom were treated without bortezomib. Hence, we investigated the real-world prognostic performance of the R-ISS in 400 patients with MM treated with novel agents in Japan, an aging society. The patients had a median age of 72 years, and 96.0% were treated with bortezomib. Patients in R-ISS stage II were significantly older and failed to show significantly longer overall survival (OS) compared to patients in R-ISS stages III (median age; 74 and 70 years, respectively; P = 0.001, and median OS; 63.4 vs. 54.7 months, respectively; P = 0.32). However, OS differed significantly among patients with all conventional ISS stages. ISS stage III patients recategorized to R-ISS stage III were significantly younger than those recategorized to R-ISS stage II and had a relatively longer OS. As a reason for these findings, patients with the high-risk cytogenetic abnormality t(4;14) were significantly younger and had an improved OS compared to others, which can be attributed to a young age and bortezomib therapy, as previously suggested. In conclusion, the R-ISS was less successful than the ISS in discriminating between stages II and III among bortezomib-treated patients with MM in an aging society, which might be attributable to the inclusion of t(4;14) in the R-ISS categorization strategy.

The chromosomal translocation t(4;11) marks an infant acute lymphoblastic leukemia associated with dismal prognosis. This rearrangement leads to the synthesis of the MLL-AF4 chimera, which exerts its oncogenic activity by upregulating transcription of genes involved in hematopoietic differentiation. Crucial for chimera’s aberrant activity is the recruitment of the AF4/ENL/P-TEFb protein complex. Interestingly, a molecular interactor of AF4 is fibroblast growth factor receptor 2 (FGFR2). We herein analyze the role of FGFR2 in the context of leukemia using t(4;11) leukemia cell lines. We revealed the interaction between MLL-AF4 and FGFR2 by immunoprecipitation, western blot, and immunofluorescence experiments; we also tested the effects of FGFR2 knockdown, FGFR2 inhibition, and FGFR2 stimulation on the expression of the main MLL-AF4 target genes, i.e., HOXA9 and MEIS1. Our results show that FGFR2 and MLL-AF4 interact in the nucleus of leukemia cells and that FGFR2 knockdown, which is associated with decreased expression of HOXA9 and MEIS1, impairs the binding of MLL-AF4 to the HOXA9 promoter. We also show that stimulation of leukemia cells with FGF2 increases nuclear level of FGFR2 in its phosphorylated form, as well as HOXA9 and MEIS1 expression. In contrast, preincubation with the ATP-mimetic inhibitor PD173074, before FGF2 stimulation, reduced FGFR2 nuclear amount and HOXA9 and MEIS1 transcript level, thereby indicating that MLL-AF4 aberrant activity depends on the nuclear availability of FGFR2. Overall, our study identifies FGFR2 as a new and promising therapeutic target in t(4;11) leukemia.

Multiple myeloma (MM) patients considered to be at high cytogenetic risk commonly fail to respond to standard treatment. A thorough understanding of the molecular mechanism of MM development is, therefore, needed. We endeavored to explore the transcriptional signature among different subgroups of newly diagnosed MM using gene chip-based expression microarray. Bone marrow samples of 15 newly diagnosed Thai MM patients were included. The chromosomal translocation t(4;14) was the most frequently identified genetic alteration in the high-risk subgroup. Cluster analysis from expression profiling demonstrated that high-risk MM have a distinctly different expression pattern compared to standard-risk patients. The most significant differentially expressed gene was UCHL1. Functional enrichment analysis by Gene Set Enrichment Analysis, FUNRICH, and Gene Ontology Panther pathway revealed the gene sets involved in cell cycle control to be enriched in the t(4;14) high-risk group. Interestingly, among the well-established downstream targets of UCHL1, only CCND2 was significantly expressed in the t(4;14) high-risk group. Suppression of UCHL1 protein level by LDN-5744 inhibitor could arrest the cell cycle in G1 phase in cell lines. These findings shed light on the molecular mechanism of UCHL1 in t(4;14) high-risk MM and support the evidence that alteration of the UCHL1 pathway may play a role in the pathogenesis of high-risk MM.

We describe the clinical, morphologic, immunophenotypic and molecular genetic features of 15 cases of acute myeloid leukemia (AML) with t(4;12)(q12;p13). There were 9 men and 6 women, with a median age of 50 years (range, 17-76). Most patients had hypercellular bone marrow with a median blast count of 58% and multilineage dysplasia. Flow cytometry analysis showed myeloid lineage with blasts positive for CD13, CD33, CD34, CD38, CD117 and HLA-DR. Interestingly, aberrant CD7 expression was detected in 12/14 cases, and myeloperoxidase was either negative (3/15) or positive in only a small subset of the blasts (12/15). t(4;12)(q12;p13) was detected at time of initial diagnosis in 4 and at relapse or progression in 9 patients. The initial karyotype was unknown in 2 cases. FISH analysis showed PDGFRA-ETV6 rearrangement in all 7 cases assessed. FLT3 ITD was detected in 2/11 cases and IDH2 and JAK2 mutation were each detected in 1/2 cases assessed. There were no mutations of KRAS (0/8), NRAS (0/8), CEBPA (0/3), KIT (0/3), NPM1 (0/3) or IDH1 (0/2). All patients received aggressive multiagent chemotherapy; 7 patients additionally received stem cell transplantation. With a median follow-up of 10 months (range, 6-51), 13 patients died of AML, 1 patient had persistent disease, and 1 patient was lost to follow-up. In summary, AML with t(4;12)(q12;p13) is usually associated with myelodysplasia, aberrant CD7 expression, weak of absent myeloperoxidase expression, frequent PDGFRA-ETV6 fusion, and an aggressive clinical course. The molecular findings suggest that there may be a role for tyrosine kinase inhibitors in patient management.

Background Carriership of a reciprocal chromosomal translocation (RCT) involving the short arm of chromosome 4 (4p) may result in birth of a child with Wolf-Hirschhorn syndrome (WHS) due to monosomy 4p, a priori modified by the impact of the partner chromosome imbalance. Familial transmission studies of RCT enable obtaining empirical risk figures that are essential for genetic counseling. In this study, pedigree data from carriers of a unique t(4;19)(p15.32;p13.3), ascertained by two children with WHS phenotype, were collected through five generations and empirical risk for different pregnancy outcomes was assessed. In addition, the phenotype-karyotype correlation was studied in two unbalanced children against the phenotypes of children (literature data) with pure monosomy 4p15.32 → pter and pure trisomy 19p13.3 → pter, accordingly. The phenotype analysis was conducted using the catalogue of traits according to the Munich Dysmorphology Database. Pedigree segregation analysis was conducted by the direct method according to Stengel- Rutkowski et al. Results A double segment imbalance, trisomy 19p13.3 → pter with monosomy 4p15.32 → pter, was diagnosed in WHS progeny at birth. No essential modification of WHS phenotype by the additional trisomy 19p was observed, except for a limited survivability (death in infancy). Pedigree segregation analysis covered 39 relatives showed the probability rate for liveborn with unbalanced karyotype of 3.7 ± 3.6% (1/27), for stillbirth/neonatal death at 7.4 ± 5.0% (2/27), for miscarriage at 22.2 ± 8.0% (6/27), for the chance of having a baby without unbalanced karyotype was estimated at 66.7 ± 9.1% (18/27). In addition, the value of 7.4% for genetic counseling for any carrier of RCT at risk for single segment 19p13.3 → pter imbalance at birth was evaluated as such value have not been estimated so far. Conclusion Carriership of a t(4;19)(p15.32;p13.3) is at low risk for an unbalanced child at birth and for stillbirth/neonatal death but high for miscarriages. The chance of having a baby without unbalanced karyotype was estimated to be high. Monosomy 4p15.32 → pter together with trisomy 19p13.3 → pter as a double segment imbalance in children with WHS may be connected with a limited survivability in infancy. Electronic supplementary material The online version of this article (doi:10.1186/s13039-017-0330-8) contains supplementary material, which is available to authorized users.

Multiple myeloma (MM) patients with t(4;14) is a heterogeneous group. Prognostic tools capable of predicting the outcome of patients are currently lacking. The MM SET domain (MMSET) protein is universally overexpressed and has been suggested to have an important tumorigenic role. This study analyzed whether the overexpression of full-length (MB4-1) or truncated forms (MB4-2 and MB4-3) of MMSET influence the prognosis of t(4;14)pos MM patients. A total of 53 symptomatic t(4;14)pos MM patients were retrospectively analyzed. RT-PCR was performed using cDNA from purified CD138+ bone marrow plasma cells to analyze expression and clinical significance of the IGH-MMSET fusion transcripts corresponding to MB4-1, MB4-2 and MB4-3 breakpoints. Among the patients, 25 (47.2%), 12 (22.6%) and 16 (30.2%) had the MB4-1, MB4-2 and MB4-3 breakpoints, respectively. When adjusted to the established prognostic variables including del(17p), ISS stage, serum LDH and serum calcium levels, the pooled MB4-2/MB4-3 subgroup remained a powerful independent adverse factor for PFS (P=0.013) and OS (P=0.029). Bortezomib-based therapy significantly improved the survival of the MB4-1 subgroup but could not overcome the negative effect of the MB4-2/MB4-3 breakpoints. Our results indicate that MB4-2/MB4-3 breakpoints with truncated forms of MMSET define a subset of t(4;14)posMM with poor prognosis.

Aim. The aim was to evaluate the results of the allogeneic hematopoietic stem cells transplantation (allo-HSCT) in children and adults with the most prognostically unfavorable acute lymphoblastic leukemia (ALL) with t(4; 11)(q21; q23)/KMT2A-AFF1 translocation. Methods. We examined 21 patients (12 females, 9 males) aged from 3 months to 48 years (median 18.9 years). The analysis of prognostic factors of overall (OS) and eventfree survival (EFS) after allo-HSCT in patients of different age groups with various clinical, transplantation and cytogenetic characteristics was performed. Allo-HSCT from HLA-compatible related and unrelated donors, as well as haploidentical allo-HSCT were performed in 4, 9 and 8 patients of age groups < 1 year, 1-18 years, and >18 years, respectively. In 10 (48 %) patients, allo-HSCT was performed in the first remission, in 2 (10 %) patients in the second remission, and in 9 (43 %) patients during the disease relapse. Results. In 8 (38 %) patients, the only chromosomal disorder was the translocation t(4; 11)(q21; q23). Additional changes in chromosomes were found in 11 (52 %) patients. In 8 (38 %) of them, 3 or more chromosomal abnormalities in the karyotype were found. According to the results of a univariant analysis, the OS and EFS were significantly different in patients with allo-HSCT performed in the first remission and at other stages of ALL (in the second remission and in relapse: p < 0.001 in both cases), as well as in patients with or without 3 or more cytogenetic disorders in the karyotype (p = 0.04 in both cases). The multivariant analysis showed that the only independent prognostic factor affecting the OS and EFS in ALL patients with t(4; 11) was the allo-HSCT, including the haploidentical procedure, during the first complete hematological and molecular remission (p = 0.002 and p = 0.0004, respectively). Conclusion. ALL with t(4; 11)/KMT2A-AFF1 was as an absolute indication for allo-HSCT in first remission, including children of < 1 year age group. Satisfactory results can be obtained with the use of haploidentical transplantation from the parents. This approach eliminates the search in the registers completely HLA-compatible donor and facilitates the treatment procedure.

A 63-year-old man was diagnosed with a rare variant of acute promyelocytic leukemia (APL) with t(4;17)(q12; q21) that showed atypical morphological features and two different clinical symptoms. He was started on standard induction chemotherapy for acute myeloid leukemia, which decreased myeloblast numbers; however, APL-like blasts remained. He then received a salvage therapy that added all-trans retinoic acid (ATRA). After ATRA commenced, APL-like blasts disappeared and cytogenetic analysis became normal. However, myeloblasts subsequently increased, and he became resistant. In summary, this patient exhibited two different clinical courses of acute myeloid leukemia and APL.

Background Haematological malignancies harbouring rearrangements of the KMT2A gene represent a unique subtype of leukaemia, with biphenotypic clinical manifestations, a rapid and aggressive onset, and a generally poor prognosis. Chromosomal translocations involving KMT2A often cause the formation of oncogenic fusion genes, such as the most common translocation t(4;11)(q21;q23) producing the KMT2A‐AFF1 chimera. Aim The aim of this study was to confirm and review the cytogenetic and molecular features of the KMT2A‐rearranged RS4;11 cell line and put those in context with other reports of cell lines also harbouring a t(4;11) rearrangement. Methods and Results The main chromosomal rearrangements t(4;11)(q21;q23) and i(7q), described when the cell line was first established, were confirmed by fluorescence in situ hybridisation (FISH) and 24‐colour karyotyping by M‐FISH. Additional cytogenetic abnormalities were investigated by further FISH experiments, including the presence of trisomy 18 as a clonal abnormality and the discovery of one chromosome 8 being an i(8q), which indicates a duplication of the oncogene MYC. A homozygous deletion of 9p21 containing the tumour‐suppressor genes CDKN2A and CDKN2B was also revealed by FISH. The production of the fusion transcript KMT2A‐AFF1 arising from the der(11)t(4;11) was confirmed by RT‐PCR, but sequencing of the amplified fragment revealed the presence of multiple isoforms. Two transcript variants, resulting from alternative splicing, were identified differing in one glutamine residue in the translated protein. Conclusion As karyotype evolution is a common issue in cell lines, we highlight the need to monitor cell lines in order to re‐confirm their characteristics over time. We also reviewed the literature to provide a comparison of key features of several cell lines harbouring a t(4;11). This would guide scientists in selecting the most suitable research model for this particular type of KMT2A‐leukaemia.

The t(4;11)(q21;q23) translocation characterizes a form of acute lymphoblastic leukemia with a poor prognosis. It results in a fusion gene encoding a chimeric transcription factor, MLL-AF4, that deregulates gene expression through a variety of still controversial mechanisms. To provide new insights into these mechanisms, we examined the interaction between AF4, the most common MLL fusion partner, and the scaffold protein 14-3-3θ, in the context of t(4;11)-positive leukemia. Protein-protein interactions were analyzed using immunoprecipitation and in vitro binding assays, and by fluorescence microscopy in t(4;11)-positive RS4;11 and MV4–11 leukemia cells and in HEK293 cells. Protein and mRNA expression levels were determined by Western blotting and RT-qPCR, respectively. A 5-bromo-2′-deoxyuridine assay and an annexin V/propidium iodide assay were used to assess proliferation and apoptosis rates, respectively, in t(4;11)-positive and control cells. Chromatin immunoprecipitation was performed to assess binding of 14-3-3θ and AF4 to a specific promoter element. We found that AF4 and 14-3-3θ are nuclear interactors, that 14-3-3θ binds Ser588 of AF4 and that 14-3-3θ forms a complex with MLL-AF4. In addition, we found that in t(4;11)-positive cells, 14-3-3θ knockdown decreased the expression of MLL-AF4 target genes, induced apoptosis and hampered cell proliferation. Moreover, we found that 14-3-3θ knockdown impaired the recruitment of AF4, but not of MLL-AF4, to target chromatin. Overall, our data indicate that the activity of the chimeric transcription factor MLL-AF4 depends on the cellular availability of 14-3-3θ, which triggers the transactivating function and subsequent degradation of AF4. From our data we conclude that the scaffold protein 14-3-3θ enhances the aberrant activity of the chimeric transcription factor MLL-AF4 and, therefore, represents a new player in the molecular pathogenesis of t(4;11)-positive leukemia and a new promising therapeutic target.

Cytogenetics has a pivotal role in risk stratification of acute myeloid leukemia (AML). We report a case of AML with a t(4;12)(q12;p13). To the best of our knowledge, there are about 24 cases of t(4;12) reported in AML which are usually misdiagnosed as lymphoproliferative disorders on morphological assessment. This case showed specific clinical, morphological, and immunophenotypic features such as (1) pseudo lymphoid morphology, (2) dysplasia in granulocytic series, (3) an immature immunophenotype with positivity for CD34 and CD117, and (4) poor treatment response.

Multiple myeloma (MM) is a hematological malignancy characterized by the proliferationof plasma cells in the bone marrow usually secreting a monoclonal immunoglobulin. Despite recenttherapeutic advances, the disease remains incurable, with a median survival of approximately 6years. However, there is considerable clinical heterogeneity between patients, with differentoutcome primarily associated with discrete genetic abnormalities. Among these, the t (4;14) (p16;q32), which is found in 15% of MM, defines one of the most serious subgroups of MM. Despite thepotential role of two deregulated oncogenes (FGFR3 and MMSET), the molecular mechanisms thatexplain the severity of MM with t (4;14) have not been clearly elucidated. By implementing theapproaches of molecular biology, high throughput sequencing and functional tests on a wide rangeof MM t (4;14), my project sought to identify genetic events associated with the poor prognosis ofthis subgroup of patients. The results showed that the site of the translocation breakpoints withinthe MMSET gene affect patient outcome. They also profiled the landscape of specific geneticmutations affecting t (4;14) MM, and revealed a relatively high frequency of alterations in the ATM/ ATR genes and PRKD2. Finally, this project has identified PKD2 as a therapeutic target anddemonstrated that an inhibitor of PKDs (kb NB 142-70) blocks the proliferation of MM cells in vitro.All these results throw new light on the pathophysiology of MM t (4;14) and opens the way to newtherapeutic approaches., Le myélome multiple (MM) est une hémopathie maligne, caractérisée par la prolifération au niveau de la moelle osseuse de plasmocytes tumoraux sécrétant le plus souvent une immunoglobuline monoclonale. Malgré de récents progrès thérapeutiques, cette maladie reste aujourd’hui incurable avec une survie médiane d’environ 6 ans. Cependant, il existe une grande hétérogénéité pronostique parmi les patients qui est associée à différentes anomalies génétiques. Parmi celles-ci, la translocation t(4;14) (p16;q32), retrouvée dans 15% des MM, définit l’une des formes de MM actuellement la plus grave. Malgré le rôle potentiel des deux oncogènes FGFR3 et MMSET qu’elle dérégule, les mécanismes moléculaires permettant d’expliquer la gravité des MM avec t(4;14) ne sont pas clairement élucidés. En mettant en œuvre des approches de biologie moléculaire, de séquençage à haut débit et de tests fonctionnels sur une très large série de MM t(4;14), mes travaux ont cherché à identifier les événements génétiques associés au mauvais pronostic de ce sous-groupe de malades. Les résultats montrent l’implication du point de cassure au sein du gène MMSET dans le pronostic des patients. Ils ont également permis de définir le paysage particulier des mutations génétiques affectant les MM t(4;14) en mettent en évidence les fréquences relativement élevées des altérations dans les gènes ATM/ATR et PRKD2. Enfin, ils ont identifiés PKD2 comme une cible thérapeutique et démontré qu’un inhibiteur des PKDs, kb NB 142-70, bloquait la prolifération des cellules de MM in vitro. L’ensemble de ces résultats jette un éclairage nouveau sur la physiopathologie des MM t(4;14) et ouvre la voie vers de nouvelles approches thérapeutiques.

The most frequent rearrangement of the human MLL gene fuses MLL to AF4 resulting in high-risk infant B-cell acute lymphoblastic leukemia (B-ALL). MLL fusions are also hallmark oncogenic events in secondary acute myeloid leukemia. They are a direct consequence of mis-repaired DNA double strand breaks (DNA-DSBs) due to defects in the DNA damage response associated with exposure to topoisomerase- II poisons such as etoposide. It has been suggested that MLL fusions render cells susceptible to additional chromosomal damage upon exposure to etoposide. Conversely, the genome-wide mutational landscape in MLL-rearranged infant B-ALL has been reported silent. Thus, whether MLL fusions compromise the recognition and/or repair of DNA damage remains unanswered. Here, the fusion proteins MLL-AF4 (MA4) and AF4-MLL (A4M) were CRISPR/Cas9-genome edited in the AAVS1 locus of HEK293 cells as a model to study MLL fusion-mediated DNA-DSB formation/repair. Repair kinetics of etoposide- and ionizing radiation-induced DSBs was identical in WT, MA4- and A4M-expressing cells, as revealed by flow cytometry, by immunoblot for γH2AX and by comet assay. Accordingly, no differences were observed between WT, MA4- and A4M-expressing cells in the presence of master proteins involved in non-homologous end-joining (NHEJ; i.e.KU86, KU70), alternative-NHEJ (Alt-NHEJ; i.e.LigIIIa, WRN and PARP1), and homologous recombination (HR, i.e.RAD51). Moreover, functional assays revealed identical NHEJ and HR efficiency irrespective of the genotype. Treatment with etoposide consistently induced cell cycle arrest in S/G2/M independent of MA4/A4M expression, revealing a proper activation of the DNA damage checkpoints. Collectively, expression of MA4 or A4M does neither influence DNA signaling nor DNA-DSB repair., This work was supported by the European Research Council to P.M (ERC-2014-CoG-646903), MINECO (SAF2013-43065 to P.M), The Foundation Inocente Inocente and the Spanish Association of Cancer Research (AECC) to P.M and the Deutsche José Carreras Leukämie Stiftung to R.M/P.M. P.M also acknowledges the financial support from The Obra Social La Caixa-Fundaciò Josep Carreras and The Generalitat de Catalunya (SGR330). F.G. is supported by a Ramón y Cajal Grant (RYC-2014-16751) from the Ministry of Economy and Competitiveness (MINECO), Spain. N.C.G and A.B.H acknowledge financial support from The Cooperative Research Thematic Networks (RTICC) (RD12/0036/0058) and the INNOCAMPUS Program (CEI10-1-0010).

// Enrica Calura 1,* , Andrea Bisognin 2,* , Martina Manzoni 3 , Katia Todoerti 4 , Elisa Taiana 3 , Gabriele Sales 1 , Gareth J. Morgan 5 , Giovanni Tonon 6 , Nicola Amodio 7 , Pierfrancesco Tassone 7 , Antonino Neri 3 , Luca Agnelli 3,** , Chiara Romualdi 1,** and Stefania Bortoluzzi 2,** 1 Department of Biology, University of Padua, Padua, Italy 2 Department of Molecular Medicine, University of Padua, Padua, Italy 3 Department of Clinical Sciences and Community Health, University of Milan, and Hematology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy 4 Laboratory of Pre-Clinical and Translational Research, IRCCS-CROB, Referral Cancer Center of Basilicata, Rionero in Vulture, Italy 5 Myeloma Institute, University of Arkansas for Medical Sciences, Little Rock, AR, USA 6 Functional Genomics of Cancer Unit, Division of Experimental Oncology, San Raffaele Scientific Institute, Milan, Italy 7 Department of Experimental and Clinical Medicine, University of Study Magna Graecia, Catanzaro, Italy * The first two authors equally contributed to this work ** A substantial contribution to the conception, design, execution and writing of this work was equally provided by these three groups. LA, CR, SB have therefore to be considered co-last authors Correspondence to: Luca Agnelli, email: // Keywords : multiple myeloma, transciptional regulatory network, t(4;14) translocation, microRNA, expression profiling Received : August 05, 2015 Accepted : September 30, 2015 Published : October 19, 2015 Abstract The identification of overexpressed miRNAs in multiple myeloma (MM) has progressively added a further level of complexity to MM biology. miRNA and gene expression profiles of two large representative MM datasets, available from retrospective and prospective series and encompassing a total of 249 patients at diagnosis, were analyzed by means of i n silico integrative genomics methods, based on MAGIA 2 and Micrographite computational procedures. We first identified relevant miRNA/transcription factors/target gene regulation circuits in the disease and linked them to biological processes. Members of the miR-99b/let-7e/miR-125a cluster, or of its paralog, upregulated in t(4;14), were connected with the specific transcription factors PBX1 and CEBPA and several target genes. These results were validated in two additional independent plasma cell tumor datasets. Then, we reconstructed a non-redundant miRNA-gene regulatory network in MM, linking miRNAs, such as let-7g , miR-19a , mirR-20a , mir-21 , miR-29 family, miR-34 family, miR-125b , miR-155 , miR-221 to pathways associated with MM subtypes, in particular the ErbB, the Hippo, and the Acute myeloid leukemia associated pathways.

The pathogenesis of infant acute lymphoblastic leukemia (ALL) is still not well defined. Short latency to leukemia and very high concordance rate for ALL in Mixed-Lineage Leukemia (MLL)-positive infant twins suggest that the MLL rearrangement itself could be sufficient for overt leukemia. Attempts to generate a suitable mouse model for MLL-AF4-positive ALL did not thoroughly resolve the issue of whether cooperating mutations are required to reduce latency and to generate overt leukemia in vivo. In this study, we applied single-nucleotide polymorphism array technology to perform genomic profiling of 28 infant ALL cases carrying t(4;11) to detect MLL-cooperating aberrations hidden to conventional techniques and to gain new insights into infant ALL pathogenesis. In contrast to pediatric, adolescent and adult ALL cases, the MLL rearrangement in infant ALL is associated with an exceptionally low frequency of copy-number abnormalities, thus confirming the unique nature of this disease. By contrast, additional genetic aberrations are acquired at disease relapse. Small-segmental uniparental disomy traits were frequently detected, mostly constitutional, and widely distributed throughout the genome. It can be argued that the MLL rearrangement as a first hit, rather than inducing the acquisition of additional genetic lesions, has a major role to drive and hasten the onset of leukemia. Leukemia (2010) 24, 169-176; doi:10.1038/leu.2009.203; published online 12 November 2009

Aim: t(4,11) is a chromosomal abnormality formed by the translocation MLL-AF4, which is the result of the fusion of the AF4 gene, localized on 4q21 chromosomal band, to the MLL gene, localized on 11q23 chromosomal band. The aim of this study is to examine the results of the analysis of t (4;11) MLL-AF4 translocation in acute lymphoblastic leukemia (ALL) patients retrospectively. Materials and Methods: Peripheral blood or bone marrow samples of 176 children (70 girls, 106 boys) and 144 adults (60 women, 84 men) with a preliminary diagnosis of acute leukemia between 2009-2013 were analyzed in the Medical Biology Department of Ege University Faculty of Medicine. The translocation RNA results of 71 peripheral blood and 473 bone marrow samples of these patients were evaluated quantitatively for t(4;11) with real-time RT-PCR. t(4;11) quantitation was performed by real-time qRT-PCR instrument after the synthesis of complementary DNA with conventional PCR from total RNA or mRNA isolated from blood and bone marrow. Quantitative analysis of the patients was performed by comparing positive and negative controls and samples classified as positive or negative (the ratio of the number of positive copies to the number of reference copies). Results: A total of 320 patients, with 98 having also follow-ups, were evaluated for t(4;11) translocation. Totally 34 patients (24 children and 10 adults) were found positive and the other samples were negative. Conclusion: The assessment of these results supports that, quantitative determination of t(4;11) with RT-PCR method among newly diagnosed ALL patients and ALL patients undergoing treatment, is a valuable method for both confirming the diagnosis and guiding the treatment intended to achieve molecular remission., Amaç: t(4;11), MLL-AF4 translokasyonu sonucu oluşan, 4q21 kromozomal bandına yerleşim gösteren AF4 geninin 11q23 kromozomal bandına yerleşim gösteren MLL genine füzyonu sonucu gelişen kromozomal bir anomalidir. Bu çalışmada, retrospektif olarak 2009-2013 yılları arasındaki akut lenfoblastik lösemi (ALL) hastalarındaki t(4;11) MLL-AF4 translokasyonunun analiz sonuçlarının incelenmesi amaçlandı. Gereç ve Yöntem: Ege Üniversitesi Tıp Fakültesi Tıbbi Biyoloji Anabilim Dalı'na 2009-2013 yılları arasında akut lösemi ön tanısıyla 176 çocuk (70 kız, 106 erkek) ve 144 yetişkin (60 kadın, 84 erkek) olgunun kan veya kemik iliği örnekleri incelendi. Bu olgulara ait 71 kan ve 473 kemik iliği örneğinin t(4;11) translokasyon RNA sonuçları, gerçek zamanlı RT-PCR yöntemi ile kantitatif olarak değerlendirildi. İlk aşamada, kan ve kemik iliği örneklerinden izole edilen total RNA veya mRNA'dan konvansiyonel bir PCR cihazı ile komplementer DNA sentezlendi. İkinci aşamada, gerçek zamanlı PCR cihazı ile t(4;11) kantitasyonu gerçekleştirildi. Olguların kantitatif olarak değerlendirilmesi, pozitif kontrol ve negatif kontrolün karşılaştırılması ile örneklerin negatif yada pozitif (pozitif olgu kopya sayısının referans kopya sayısına oranı) olması şeklinde yapıldı. Bulgular: Çalışmamızda 98'i takip hastası olmak üzere toplam 320 hasta t(4;11) MLL-AF4 translokasyonu için değerlendirildi. Çalışmaların sonucunda toplam 34 olgu (24 çocuk, 10 yetişkin) pozitif ve diğer örnekler negatif olarak bulundu. Sonuç: Bu değerlendirmenin sonuçları, RT-PCR yöntemi ile ALL hastalarında yeni tanı döneminde ve tedavi sürecinde t(4;11) MLL-AF4 translokasyonunun kantitatif tayini, hem tanının kesinleştirilmesinde hem de moleküler remisyon sağlanmasına yönelik tedaviyi yönlendirmesinde değerli bir yöntem olduğunu desteklemektedir.

We have recently demonstrated that Taspase1-mediated cleavage of the AF4–MLL oncoprotein results in the formation of a stable multiprotein complex which forms the key event for the onset of acute proB leukemia in mice. Therefore, Taspase1 represents a conditional oncoprotein in the context of t(4;11) leukemia. In this report, we used site-directed mutagenesis to unravel the molecular events by which Taspase1 becomes sequentially activated. Monomeric pro-enzymes form dimers which are autocatalytically processed into the enzymatically active form of Taspase1 (αββα). The active enzyme cleaves only very few target proteins, e.g., MLL, MLL4 and TFIIA at their corresponding consensus cleavage sites (CSTasp1) as well as AF4–MLL in the case of leukemogenic translocation. This knowledge was translated into the design of a dominant-negative mutant of Taspase1 (dnTASP1). As expected, simultaneous expression of the leukemogenic AF4–MLL and dnTASP1 causes the disappearance of the leukemogenic oncoprotein, because the uncleaved AF4–MLL protein (328 kDa) is subject to proteasomal degradation, while the cleaved AF4–MLL forms a stable oncogenic multi-protein complex with a very long half-life. Moreover, coexpression of dnTASP1 with a BFP-CSTasp1-GFP FRET biosensor effectively inhibits cleavage. The impact of our findings on future drug development and potential treatment options for t(4;11) leukemia will be discussed., eBioMedicine, 2 (5), ISSN:2352-3964