A metabolic function of FGFR3-TACC3 gene fusions in cancer.

Chromosomal translocations that generate in-frame oncogenic gene fusions are notable examples of the success of targeted cancer therapies. We have previously described gene fusions of FGFR3-TACC3 (F3-T3) in 3% of human glioblastoma cases. Subsequent studies have reported similar frequencies of F3-T3 in many other cancers, indicating that F3-T3 is a commonly occuring fusion across all tumour types. F3-T3 fusions are potent oncogenes that confer sensitivity to FGFR inhibitors, but the downstream oncogenic signalling pathways remain unknown. Here we show that human tumours with F3-T3 fusions cluster within transcriptional subgroups that are characterized by the activation of mitochondrial functions. F3-T3 activates oxidative phosphorylation and mitochondrial biogenesis and induces sensitivity to inhibitors of oxidative metabolism. Phosphorylation of the phosphopeptide PIN4 is an intermediate step in the signalling pathway of the activation of mitochondrial metabolism. The F3-T3-PIN4 axis triggers the biogenesis of peroxisomes and the synthesis of new proteins. The anabolic response converges on the PGC1α coactivator through the production of intracellular reactive oxygen species, which enables mitochondrial respiration and tumour growth. These data illustrate the oncogenic circuit engaged by F3-T3 and show that F3-T3-positive tumours rely on mitochondrial respiration, highlighting this pathway as a therapeutic opportunity for the treatment of tumours with F3-T3 fusions. We also provide insights into the genetic alterations that initiate the chain of metabolic responses that drive mitochondrial metabolism in cancer.

Laboratory diagnosis of heparin-induced thrombocytopenia: A retrospective experience.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a severe complication of heparin therapy associated with thrombosis that requires a quick diagnosis. Therefore, laboratory assays must provide an accurate and swift answer. This work aims to evaluate the performances of an ELISA assay, especially when combined with 4T risk score, and a functional assay. METHODS: Data were collected for 894 patients treated by heparin who underwent anticoagulant switch because of HIT suspicion and were examined by a multidisciplinary expert team who confirmed or ruled out HIT diagnosis. All patients were tested for anti-PF4 IgG with Asserachrom HPIA IgG (ELISA), and 307 were tested with a platelet aggregation test done on platelet-rich plasma (PRP-PAT). The 4T risk score was available for 607 of them. RESULTS: HIT was diagnosed in 232 patients. 4T risk score had a 94.2% negative predictive value (NPV) for risk scores ≤3 and 77.3% for risk scores ≤5. The sensitivity of ELISA was 90.9%, its specificity 79.0%, and its NPV 96.1%. When combined with 4T risk score, its NPV reached 100% and 97% for risk scores ≤3 and ≤5, respectively. PRP-PAT sensitivity was 70.4%, and its specificity was 92.3%. Combination of ELISA and PRP-PAT had a 0.7% false-negative rate. CONCLUSION: This study shows that ELISA can rule out HIT with an excellent NPV, especially when combined with the 4T risk score. Nonetheless, it has low specificity; hence, it needs to be associated with a functional assay.

Functional proteogenomics reveals biomarkers and therapeutic targets in lymphomas.

Identification of biomarkers and therapeutic targets is a critical goal of precision medicine. N-glycoproteins are a particularly attractive class of proteins that constitute potential cancer biomarkers and therapeutic targets for small molecules, antibodies, and cellular therapies. Using mass spectrometry (MS), we generated a compendium of 1,091 N-glycoproteins (from 40 human primary lymphomas and cell lines). Hierarchical clustering revealed distinct subtype signatures that included several subtype-specific biomarkers. Orthogonal immunological studies in 671 primary lymphoma tissue biopsies and 32 lymphoma-derived cell lines corroborated MS data. In anaplastic lymphoma kinase-positive (ALK+) anaplastic large cell lymphoma (ALCL), integration of N-glycoproteomics and transcriptome sequencing revealed an ALK-regulated cytokine/receptor signaling network, including vulnerabilities corroborated by a genome-wide clustered regularly interspaced short palindromic screen. Functional targeting of IL-31 receptor ß, an ALCL-enriched and ALK-regulated N-glycoprotein in this network, abrogated ALK+ALCL growth in vitro and in vivo. Our results highlight the utility of functional proteogenomic approaches for discovery of cancer biomarkers and therapeutic targets.

Integrated genomic sequencing reveals mutational landscape of T-cell prolymphocytic leukemia.

The comprehensive genetic alterations underlying the pathogenesis of T-cell prolymphocytic leukemia (T-PLL) are unknown. To address this, we performed whole-genome sequencing (WGS), whole-exome sequencing (WES), high-resolution copy-number analysis, and Sanger resequencing of a large cohort of T-PLL. WGS and WES identified novel mutations in recurrently altered genes not previously implicated in T-PLL including EZH2, FBXW10, and CHEK2. Strikingly, WGS and/or WES showed largely mutually exclusive mutations affecting IL2RG, JAK1, JAK3, or STAT5B in 38 of 50 T-PLL genomes (76.0%). Notably, gain-of-function IL2RG mutations are novel and have not been reported in any form of cancer. Further, high-frequency mutations in STAT5B have not been previously reported in T-PLL. Functionally, IL2RG-JAK1-JAK3-STAT5B mutations led to signal transducer and activator of transcription 5 (STAT5) hyperactivation, transformed Ba/F3 cells resulting in cytokine-independent growth, and/or enhanced colony formation in Jurkat T cells. Importantly, primary T-PLL cells exhibited constitutive activation of STAT5, and targeted pharmacologic inhibition of STAT5 with pimozide induced apoptosis in primary T-PLL cells. These results for the first time provide a portrait of the mutational landscape of T-PLL and implicate deregulation of DNA repair and epigenetic modulators as well as high-frequency mutational activation of the IL2RG-JAK1-JAK3-STAT5B axis in the pathogenesis of T-PLL. These findings offer opportunities for novel targeted therapies in this aggressive leukemia.

A novel recurrent NPM1-TYK2 gene fusion in cutaneous CD30-positive lymphoproliferative disorders.

The spectrum of cutaneous CD30-positive lymphoproliferative disorders (LPDs) includes lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Chromosomal translocations targeting tyrosine kinases in CD30-positive LPDs have not been described. Using whole-transcriptome sequencing, we identified a chimeric fusion involving NPM1 (5q35) and TYK2 (19p13) that encodes an NPM1-TYK2 protein containing the oligomerization domain of NPM1 and an intact catalytic domain in TYK2. Fluorescence in situ hybridization revealed NPM1-TYK2 fusions in 2 of 47 (4%) primary cases of CD30-positive LPDs and was absent in other mature T-cell neoplasms (n = 151). Functionally, NPM1-TYK2 induced constitutive TYK2, signal transducer and activator of transcription 1 (STAT1), STAT3, and STAT5 activation. Conversely, a kinase-defective NPM1-TYK2 mutant abrogated STAT1/3/5 signaling. Finally, short hairpin RNA-mediated silencing of TYK2 abrogated lymphoma cell growth. This is the first report of recurrent translocations involving TYK2, and it highlights the novel therapeutic opportunities in the treatment of CD30-positive LPDs with TYK2 translocations.

Global phosphoproteomic profiling reveals distinct signatures in B-cell non-Hodgkin lymphomas.

Deregulation of signaling pathways controlled by protein phosphorylation underlies the pathogenesis of hematological malignancies; however, the extent to which deregulated phosphorylation may be involved in B-cell non-Hodgkin lymphoma (B-NHL) pathogenesis is largely unknown. To identify phosphorylation events important in B-NHLs, we performed mass spectrometry-based, label-free, semiquantitative phosphoproteomic profiling of 11 cell lines derived from three B-NHL categories: Burkitt lymphoma, follicular lymphoma, and mantle-cell lymphoma. In all, 6579 unique phosphopeptides, corresponding to 1701 unique phosphorylated proteins, were identified and quantified. The data are available via ProteomeXchange with identifier PXD000658. Hierarchical clustering highlighted distinct phosphoproteomic signatures associated with each lymphoma subtype. Interestingly, germinal center-derived B-NHL cell lines were characterized by phosphorylation of proteins involved in the B-cell receptor signaling. Of these proteins, phosphoprotein associated with glycosphingolipid-enriched microdomains 1 (PAG1) was identified with the most phosphorylated tyrosine peptides in Burkitt lymphoma and follicular lymphoma. PAG1 knockdown resulted in perturbation of the tyrosine phosphosignature of B-cell receptor signaling components. Significantly, PAG1 knockdown increased cell proliferation and response to antigen stimulation of these germinal center-derived B-NHLs. These data provide a detailed annotation of phosphorylated proteins in human lymphoid cancer. Overall, our study revealed the utility of unbiased phosphoproteome interrogation in characterizing signaling networks that may provide insights into pathogenesis mechanisms in B-cell lymphomas.

Integrated phosphoproteomic and metabolomic profiling reveals NPM-ALK-mediated phosphorylation of PKM2 and metabolic reprogramming in anaplastic large cell lymphoma.

The mechanisms underlying the pathogenesis of the constitutively active tyrosine kinase nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) expressing anaplastic large cell lymphoma are not completely understood. Here we show using an integrated phosphoproteomic and metabolomic strategy that NPM-ALK induces a metabolic shift toward aerobic glycolysis, increased lactate production, and biomass production. The metabolic shift is mediated through the anaplastic lymphoma kinase (ALK) phosphorylation of the tumor-specific isoform of pyruvate kinase (PKM2) at Y105, resulting in decreased enzymatic activity. Small molecule activation of PKM2 or expression of Y105F PKM2 mutant leads to reversal of the metabolic switch with increased oxidative phosphorylation and reduced lactate production coincident with increased cell death, decreased colony formation, and reduced tumor growth in an in vivo xenograft model. This study provides comprehensive profiling of the phosphoproteomic and metabolomic consequences of NPM-ALK expression and reveals a novel role of ALK in the regulation of multiple components of cellular metabolism. Our studies show that PKM2 is a novel substrate of ALK and plays a critical role in mediating the metabolic shift toward biomass production and tumorigenesis.

Fusion peptides from oncogenic chimeric proteins as putative specific biomarkers of cancer.

Chromosomal translocations encoding chimeric fusion proteins constitute one of the most common mechanisms underlying oncogenic transformation in human cancer. Fusion peptides resulting from such oncogenic chimeric fusions, though unique to specific cancer subtypes, are unexplored as cancer biomarkers. Here we show, using an approach termed fusion peptide multiple reaction monitoring mass spectrometry, the direct identification of different cancer-specific fusion peptides arising from protein chimeras that are generated from the juxtaposition of heterologous genes fused by recurrent chromosomal translocations. Using fusion peptide multiple reaction monitoring mass spectrometry in a clinically relevant scenario, we demonstrate the specific, sensitive, and unambiguous detection of a specific diagnostic fusion peptide in clinical samples of anaplastic large cell lymphoma, but not in a diverse array of benign lymph nodes or other forms of primary malignant lymphomas and cancer-derived cell lines. Our studies highlight the utility of fusion peptides as cancer biomarkers and carry broad implications for the use of protein biomarkers in cancer detection and monitoring.

Safety and activity of crizotinib for paediatric patients with refractory solid tumours or anaplastic large-cell lymphoma: a Children's Oncology Group phase 1 consortium study.

BACKGROUND: Various human cancers have ALK gene translocations, amplifications, or oncogenic mutations, such as anaplastic large-cell lymphoma, inflammatory myofibroblastic tumours, non-small-cell lung cancer (NSCLC), and neuroblastoma. Therefore, ALK inhibition could be a useful therapeutic strategy in children. We aimed to determine the safety, recommended phase 2 dose, and antitumour activity of crizotinib in children with refractory solid tumours and anaplastic large-cell lymphoma. METHODS: In this open-label, phase 1 dose-escalation trial, patients older than 12 months and younger than 22 years with measurable or evaluable solid or CNS tumours, or anaplastic large-cell lymphoma, refractory to therapy and for whom there was no known curative treatment were eligible. Crizotinib was given twice daily without interruption. Six dose levels (100, 130, 165, 215, 280, 365 mg/m(2) per dose) were assessed in the dose-finding phase of the study (part A1), which is now completed. The primary endpoint was to estimate the maximum tolerated dose, to define the toxic effects of crizotinib, and to characterise the pharmacokinetics of crizotinib in children with refractory cancer. Additionally, patients with confirmed ALK translocations, mutations, or amplification (part A2 of the study) or neuroblastoma (part A3) could enrol at one dose level lower than was currently given in part A1. We assessed ALK genomic status in tumour tissue and used quantitative RT-PCR to measure NPM-ALK fusion transcript in bone marrow and blood samples of patients with anaplastic large-cell lymphoma. All patients who received at least one dose of crizotinib were evaluable for response; patients completing at least one cycle of therapy or experiencing dose limiting toxicity before that were considered fully evaluable for toxicity. This study is registered with ClinicalTrials.gov, NCT00939770. FINDINGS: 79 patients were enrolled in the study from Oct 2, 2009, to May 31, 2012. The median age was 10.1 years (range 1.1-21.4); 43 patients were included in the dose escalation phase (A1), 25 patients in part A2, and 11 patients in part A3. Crizotinib was well tolerated with a recommended phase 2 dose of 280 mg/m(2) twice daily. Grade 4 adverse events in cycle 1 were neutropenia (two) and liver enzyme elevation (one). Grade 3 adverse events that occurred in more than one patient in cycle 1 were lymphopenia (two), and neutropenia (eight). The mean steady state peak concentration of crizotinib was 630 ng/mL and the time to reach this peak was 4 h (range 1-6). Objective tumour responses were documented in 14 of 79 patients (nine complete responses, five partial responses); and the anti-tumour activity was enriched in patients with known activating ALK aberrations (eight of nine with anaplastic large-cell lymphoma, one of 11 with neuroblastoma, three of seven with inflammatory myofibroblastic tumour, and one of two with NSCLC). INTERPRETATION: The findings suggest that a targeted inhibitor of ALK has antitumour activity in childhood malignancies harbouring ALK translocations, particularly anaplastic large-cell lymphoma and inflammatory myofibroblastic tumours, and that further investigation in the subset of neuroblastoma harbouring known ALK oncogenic mutations is warranted. FUNDING: Pfizer and National Cancer Institute grant to the Children's Oncology Group.

Evaluation of an integrated activated partial thromboplastin time (Cephen LS/Cephen) for the detection of lupus anticoagulant.

INTRODUCTION: It is recommended to use two chronometric assays of different principles for the diagnosis of lupus anticoagulant (LA), consisting in diluted Russell Viper Venom Time (dRVVT) and activated Partial Thromboplastin Time (aPTT). Yet, there are only a few integrated aPTT assays; this study aims to evaluate one of them: Cephen LS/Cephen (Hyphen Biomed). METHOD: 249 samples of patients were included in this study. Normal reference ranges were determined with platelet-poor plasma (PPP) from healthy blood donors. Performances were then evaluated by comparing Cephen LS/Cephen test results to the results of the laboratory's reference assay for the diagnosis of LA and to clinical data, both on non-anticoagulated and anticoagulated patients' samples (Unfractioned heparin (UFH), Low Molecular Weight Heparin (LMWH), Vitamin K Antagonists (VKA) and apixaban). Interference of UFH, LMWH and VKA were also evaluated thanks to spiking experiment of increasing heparin concentrations or factor deficiency. RESULTS: Cephen LS/Cephen test had 48.6% sensitivity towards LA. Although UFH and VKA seemed to interfere with this assay and were likely to cause false negative, LMWH and apixaban did not. Finally, combination of Cephen LS/ Cephen with dRVVT had 89.0% sensitivity. CONCLUSION: Cephen LS/Cephen seems relevant for LA diagnosis, in combination with dRVVT, and might be used in patients undergoing LMWH or apixaban therapy.

[Acute myeloid leukemia with mutated RUNX1 at the university hospitals of Strasbourg]. / Étude rétrospective des leucémies aiguës myéloïdes mutées RUNX1 aux hôpitaux ­universitaires de Strasbourg.

RUNX1 is essential during human hematopoiesis. Numerous RUNX1 deregulations have been described, including translocations and germline or somatic mutations. Recurrent de novo RUNX1 mutations in acute myeloid leukemias (AML) prompted the creation of a provisional entity of AML with mutated RUNX1 in the 2016 WHO. In addition, recent genomic studies underlined rare AML patients with plasmacytoid dendritic cell (pDC) expansion and high RUNX1 mutations frequency. To better characterized AML with RUNX1 mutations, we retrospectively investigated a cohort of 32 patients diagnosed at Strasbourg University Hospital. Detailed clinical and biological features were aggregated. The presence of a pDC contingent was assessed by cytology and flow cytometry. In our cohort, no common features were identified either in term of cytology, stage of leukemia arrest or mutational features. Based on our observations, mutated RUNX1 AMLs do not appear to be a distinct AML entity. The new 2022 WHO classification includes AML with mutated RUNX1 within AML myelodysplasia-related category. We also identified within our cohort a patient whose AML fulfilled AML-pDC criteria, a rare and newly included entity in the last WHO classification.

Vaginal delivery of the second twin: A simulation program for residents in obstetrics and gynecology in a type III university maternity hospital.

OBJECTIVE: To implement a vaginal delivery of the second twin simulation program for obstetric and gynecology residents, to reduce maternal-fetal mortality in the management of twin pregnancies in the delivery room. DESIGN: A prospective education program. The session consisted of a theoretical part, a practical part on a mannequin and an evaluation. The model was designed in a simple and reproducible way. The simulation evaluation was done at several levels according to the validated Kirkpatrick model. SETTING: A tertiary level university maternity hospital. PARTICIPANTS: Ten obstetric and gynecology residents participated. RESULTS: The resident's personal feelings about their ability to perform the maneuvers increased significantly after participation in the simulation session. Their technical skills in performing the maneuvers were assessed in a second step. The majority of the participants considered the model realistic and the session useful. All agreed that the simulation was an essential part of their learning process. CONCLUSION: A simulated vaginal delivery of the second twin session allows residents to be safely trained in these obstetrical maneuvers, which can be difficult to teach and perform.

Assessment of a multiprofessional training programme by in situ simulation in the maternity units of the Pays de Loire regional perinatal network.

INTRODUCTION: Initially dispensed in specialized simulation centers, simulation training has recently begun to take place directly in healthcare facilities, that is, in situ. The objective of this study is to assess the effect of training by in situ simulation in obstetrics. MATERIAL AND METHODS: The training program, dispensed over a 2-day period, took place in maternity units of the members of the Pays de la Loire perinatal network, Réseau Sécurité Naissance (Network Safety Birth). All participants received a learner satisfaction questionnaire to complete (5-point Likert-like scales). Then, at least 6 months later, each maternity ward received a general questionnaire to assess the effect of the training, as well as a second questionnaire specific to each institution, about the areas for improvement proposed by the teaching team after debriefings. RESULTS: The 14 establishments included in our study returned 375 satisfaction questionnaires. In all, 91.1 % were very satisfied and reported that the training met their expectations, and 99.7 % thought the program would have an impact on their professional practice. More than 94 % of the learners wanted more simulation sessions. Among the 14 facilities, 9 (64.3 %) returned their evaluation questionnaires. In 44.4 % of cases, they reported improvement in team cohesion and in team communication, while the others reported these elements remained stable. All maternity units reported that the training had a positive impact on their team, and that they would be interested in new training program with in situ simulation. DISCUSSION: Most participants clearly appreciated this training. In situ simulation training also led to the identification of areas for improvements, many of them accomplished, through the drafting of protocols or material modifications aimed at improving staff practices and therefore global patient care. There are many ways by which these training programs can be made sustainable, including the development of a new training program of in situ simulation or the creation of onsite simulation sessions on demand or by the professionals at each institution. CONCLUSION: This survey demonstrated the enthusiasm of healthcare professionals about in situ simulation. Moreover, overall improvement in team communication and cohesion was reported in the medium term (evaluation at more than 6 months). The interest of continuing these training sessions appears undeniable.

FBXW7 Triggers Degradation of KMT2D to Favor Growth of Diffuse Large B-cell Lymphoma Cells.

Mature B-cell neoplasms are the fifth most common neoplasm. Due to significant heterogeneity at the clinical and genetic levels, current therapies for these cancers fail to provide long-term cures. The clinical success of proteasome inhibition for the treatment of multiple myeloma and B-cell lymphomas has made the ubiquitin pathway an important emerging therapeutic target. In this study, we assessed the role of the E3 ligase FBXW7 in mature B-cell neoplasms. FBXW7 targeted the frequently inactivated tumor suppressor KMT2D for protein degradation, subsequently regulating gene expression signatures related to oxidative phosphorylation (OxPhos). Loss of FBXW7 inhibited diffuse large B-cell lymphoma cell growth and further sensitized cells to OxPhos inhibition. These data elucidate a novel mechanism of regulation of KMT2D levels by the ubiquitin pathway and uncover a role of FBXW7 in regulating oxidative phosphorylation in B-cell malignancies. SIGNIFICANCE: These findings characterize FBXW7 as a prosurvival factor in B-cell lymphoma via degradation of the chromatin modifier KMT2D.

Colony-Stimulating Factor 1 Receptor (CSF1R) Activates AKT/mTOR Signaling and Promotes T-Cell Lymphoma Viability.

PURPOSE: Peripheral T-cell lymphomas are clinically aggressive and usually fatal, as few complete or durable remissions are achieved with currently available therapies. Recent evidence supports a critical role for lymphoma-associated macrophages during T-cell lymphoma progression, but the specific signals involved in the cross-talk between malignant T cells and their microenvironment are poorly understood. Colony-stimulator factor 1 receptor (CSF1R, CD115) is required for the homeostatic survival of tissue-resident macrophages. Interestingly, its aberrant expression has been reported in a subset of tumors. In this article, we evaluated its expression and oncogenic role in T-cell lymphomas. EXPERIMENTAL DESIGN: Loss-of-function studies, including pharmacologic inhibition with a clinically available tyrosine kinase inhibitor, pexidartinib, were performed in multiple in vitro and in vivo models. In addition, proteomic and genomic screenings were performed to discover signaling pathways that are activated downstream of CSF1R signaling. RESULTS: We observed that CSF1R is aberrantly expressed in many T-cell lymphomas, including a significant number of peripheral and cutaneous T-cell lymphomas. Colony-stimulating factor 1 (CSF1), in an autocrine or paracrine-dependent manner, leads to CSF1R autophosphorylation and activation in malignant T cells. Furthermore, CSF1R signaling was associated with significant changes in gene expression and in the phosphoproteome, implicating PI3K/AKT/mTOR in CSF1R-mediated T-cell lymphoma growth. We also demonstrated that inhibition of CSF1R in vivo and in vitro models is associated with decreased T-cell lymphoma growth. CONCLUSIONS: Collectively, these findings implicate CSF1R in T-cell lymphomagenesis and have significant therapeutic implications.

The mechanism of cancer drug addiction in ALK-positive T-Cell lymphoma.

Rational new strategies are needed to treat tumors resistant to kinase inhibitors. Mechanistic studies of resistance provide fertile ground for development of new approaches. Cancer drug addiction is a paradoxical resistance phenomenon, well-described in MEK-ERK-driven solid tumors, in which drug-target overexpression promotes resistance but a toxic overdose of signaling if the inhibitor is withdrawn. This can permit prolonged control of tumors through intermittent dosing. We and others showed previously that cancer drug addiction arises also in the hematologic malignancy ALK-positive anaplastic large-cell lymphoma (ALCL) resistant to ALK-specific tyrosine kinase inhibitors (TKIs). This is driven by the overexpression of the fusion kinase NPM1-ALK, but the mechanism by which ALK overactivity drives toxicity upon TKI withdrawal remained obscure. Here we reveal the mechanism of ALK-TKI addiction in ALCL. We interrogated the well-described mechanism of MEK/ERK pathway inhibitor addiction in solid tumors and found it does not apply to ALCL. Instead, phosphoproteomics and confirmatory functional studies revealed that the STAT1 overactivation is the key mechanism of ALK-TKI addiction in ALCL. The withdrawal of TKI from addicted tumors in vitro and in vivo leads to overwhelming phospho-STAT1 activation, turning on its tumor-suppressive gene-expression program and turning off STAT3's oncogenic program. Moreover, a novel NPM1-ALK-positive ALCL PDX model showed a significant survival benefit from intermittent compared with continuous TKI dosing. In sum, we reveal for the first time the mechanism of cancer drug addiction in ALK-positive ALCL and the benefit of scheduled intermittent dosing in high-risk patient-derived tumors in vivo.

Mass spectrometry and proteomics in hematology.

Mass spectrometry-based techniques now enable the unbiased identification of proteins in complex mixtures including proteins isolated from cells and tissues. These powerful tools permit near-complete annotation of proteins expressed in cells, tissues or organs. Further, these techniques permit the interrogation of the numerous posttranslational modifications that govern cell-specific responses to signaling cues and underlie the functional heterogeneity of cellular composition and contribute to biological complexity. Parallel developments in technologies such as mass cytometry and multicolor ion-beam imaging which permit multi-parameter detection of numerous proteins at the single-cell and in situ level respectively, are poised to radically impact our understanding of the functional and translational importance of proteins in hematologic conditions. Importantly, the field of proteomics is poised to realize the immensely powerful opportunities in integration with genomic information that is being discovered at an unprecedented pace for many hematologic conditions.

Farnesyltransferase inhibitor R115777 inhibits cell growth and induces apoptosis in mantle cell lymphoma.

INTRODUCTION: The cytotoxic activity of the farnesyltranseferase inhibitor R115777 was evaluated in cell lines representative of mantle cell lymphoma (MCL). METHODS: Cell growth, proliferation, and apoptosis were analyzed in four human MCL cell lines (Granta, NCEB, REC, and UPN1) in presence of R115777, alone or in combination with vincristin, doxorubicin, bortezomib, cisplatin and cytarabine. Inhibition of farnesylation was determined by the appearance of prelamin A. The antitumor activity of R115777, administered p.o. at 100, 250 and 500 mg/kg, was determined in vivo in nude mice xenografted with UPN1 cells. RESULTS: R115777 inhibited the growth of MCL cell lines in vitro with inhibitory concentrations ranging between 2 and 15 nM. A fifty percent decrease of cell viability was observed at concentrations comprised between 0.08 and 17 microM. Apoptosis, evaluated by annexin V and activated caspase 3 staining, was induced in all cell lines, in 40 to 71% of the cells depending on the cell lines. In addition, R115777 significantly increased the cytotoxic effect of vincristine, doxorubicin, bortezomib, cisplatin and cytarabine (p=0.001, p=0.016, p=0.006, p=0.014 and p=0.007 respectively). Exposure of MCL cell lines to R115777 during 72 hours resulted in inhibition of protein farnesylation. R115777 administered p.o. twice daily for 8 consecutive days to mice bearing established s.c. UPN1 xenograft displayed cytostatic activity at the 500 mg/kg dosage. CONCLUSION: We have demonstrated that inhibition of farnesyltransferase by R115777 was associated with growth inhibition and apoptosis of MCL cell lines in vitro and tumor xenograft stability in vivo.