RESUMO
The tumor suppressor PTEN controls cell proliferation by regulating phosphatidylinositol-3-kinase (PI3K) activity, but the participation of PTEN in host defense against bacterial infection is less well understood. Anti-inflammatory PI3K-Akt signaling is suppressed in patients with cystic fibrosis (CF), a disease characterized by hyper-inflammatory responses to airway infection. We found that Ptenl-/- mice, which lack the NH2-amino terminal splice variant of PTEN, were unable to eradicate Pseudomonas aeruginosa from the airways and could not generate sufficient anti-inflammatory PI3K activity, similar to what is observed in CF. PTEN and the CF transmembrane conductance regulator (CFTR) interacted directly and this interaction was necessary to position PTEN at the membrane. CF patients under corrector-potentiator therapy, which enhances CFTR transport to the membrane, have increased PTEN amounts. These findings suggest that improved CFTR trafficking could enhance P. aeruginosa clearance from the CF airway by activating PTEN-mediated anti-bacterial responses and might represent a therapeutic strategy.
Assuntos
Membrana Celular/imunologia , Regulador de Condutância Transmembrana em Fibrose Cística/imunologia , Fibrose Cística/imunologia , PTEN Fosfo-Hidrolase/imunologia , Infecções por Pseudomonas/imunologia , Aminofenóis/farmacologia , Aminopiridinas/farmacologia , Animais , Benzodioxóis/farmacologia , Membrana Celular/efeitos dos fármacos , Fibrose Cística/tratamento farmacológico , Fibrose Cística/genética , Fibrose Cística/microbiologia , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Regulação da Expressão Gênica , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Moleculares , Monócitos/efeitos dos fármacos , Monócitos/imunologia , Monócitos/microbiologia , PTEN Fosfo-Hidrolase/deficiência , PTEN Fosfo-Hidrolase/genética , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/imunologia , Ligação Proteica , Conformação Proteica , Transporte Proteico , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/imunologia , Infecções por Pseudomonas/genética , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/imunologia , Quinolonas/farmacologia , Transdução de SinaisRESUMO
Insights into cancer genetics can lead to therapeutic opportunities. By cross-referencing chromosomal changes with an unbiased genetic screen we identify the ephrin receptor A7 (EPHA7) as a tumor suppressor in follicular lymphoma (FL). EPHA7 is a target of 6q deletions and inactivated in 72% of FLs. Knockdown of EPHA7 drives lymphoma development in a murine FL model. In analogy to its physiological function in brain development, a soluble splice variant of EPHA7 (EPHA7(TR)) interferes with another Eph-receptor and blocks oncogenic signals in lymphoma cells. Consistent with this drug-like activity, administration of the purified EPHA7(TR) protein produces antitumor effects against xenografted human lymphomas. Further, by fusing EPHA7(TR) to the anti-CD20 antibody (rituximab) we can directly target this tumor suppressor to lymphomas in vivo. Our study attests to the power of combining descriptive tumor genomics with functional screens and reveals EPHA7(TR) as tumor suppressor with immediate therapeutic potential.
Assuntos
Genes Supressores de Tumor , Linfoma Folicular/metabolismo , Receptor EphA7/metabolismo , Animais , Anticorpos Monoclonais Murinos/uso terapêutico , Linhagem Celular Tumoral , Cromossomos Humanos Par 6 , Genômica , Humanos , Linfoma Folicular/tratamento farmacológico , Linfoma Folicular/genética , Masculino , Camundongos , Transplante de Neoplasias , Interferência de RNA , Rituximab , Transplante HeterólogoRESUMO
PURPOSE: Cadherin-17 (CDH17) is a calcium-dependent cell adhesion protein that is overexpressed in several adenocarcinomas, including gastric, colorectal, and pancreatic adenocarcinoma. High levels of CDH17 have been linked to metastatic disease and poor prognoses in patients with these malignancies, fueling interest in the protein as a target for diagnostics and therapeutics. Herein, we report the synthesis, in vitro validation, and in vivo evaluation of a CDH17-targeted 89Zr-labeled immunoPET probe. METHODS: The CDH17-targeting mAb D2101 was modified with an isothiocyanate-bearing derivative of desferrioxamine (DFO) to produce a chelator-bearing immunoconjugate - DFO-D2101 - and flow cytometry and surface plasmon resonance (SPR) were used to interrogate its antigen-binding properties. The immunoconjugate was then radiolabeled with zirconium-89 (t1/2 ~ 3.3 days), and the serum stability and immunoreactive fraction of [89Zr]Zr-DFO-D2101 were determined. Finally, [89Zr]Zr-DFO-D2101's performance was evaluated in a trio of murine models of pancreatic ductal adenocarcinoma (PDAC): subcutaneous, orthotopic, and patient-derived xenografts (PDX). PET images were acquired over the course of 5 days, and terminal biodistribution data were collected after the final imaging time point. RESULTS: DFO-D2101 was produced with a degree of labeling of ~ 1.1 DFO/mAb. Flow cytometry with CDH17-expressing AsPC-1 cells demonstrated that the immunoconjugate binds to its target in a manner similar to its parent mAb, while SPR with recombinant CDH17 revealed that D2101 and DFO-D2101 exhibit nearly identical KD values: 8.2 × 10-9 and 6.7 × 10-9 M, respectively. [89Zr]Zr-DFO-D2101 was produced with a specific activity of 185 MBq/mg (5.0 mCi/mg), remained >80% stable in human serum over the course of 5 days, and boasted an immunoreactive fraction of >0.85. In all three murine models of PDAC, the radioimmunoconjugate yielded high contrast images, with high activity concentrations in tumor tissue and low uptake in non-target organs. Tumoral activity concentrations reached as high as >60 %ID/g in two of the cohorts bearing PDXs. CONCLUSION: Taken together, these data underscore that [89Zr]Zr-DFO-D2101 is a highly promising probe for the non-invasive visualization of CDH17 expression in PDAC. We contend that this radioimmunoconjugate could have a significant impact on the clinical management of patients with both PDAC and gastrointestinal adenocarcinoma, most likely as a theranostic imaging tool in support of CDH17-targeted therapies.
Assuntos
Caderinas , Radioisótopos , Zircônio , Animais , Humanos , Camundongos , Caderinas/metabolismo , Linhagem Celular Tumoral , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/metabolismo , Desferroxamina/química , Adenocarcinoma/diagnóstico por imagem , Imunoconjugados/farmacocinética , Anticorpos Monoclonais/farmacocinética , Distribuição Tecidual , Tomografia por Emissão de PósitronsRESUMO
UDP-glucose pyrophosphorylase 2 (UGP2), the enzyme that synthesizes uridine diphosphate (UDP)-glucose, rests at the convergence of multiple metabolic pathways, however, the role of UGP2 in tumor maintenance and cancer metabolism remains unclear. Here, we identify an important role for UGP2 in the maintenance of pancreatic ductal adenocarcinoma (PDAC) growth in both in vitro and in vivo tumor models. We found that transcription of UGP2 is directly regulated by the Yes-associated protein 1 (YAP)-TEA domain transcription factor (TEAD) complex, identifying UGP2 as a bona fide YAP target gene. Loss of UGP2 leads to decreased intracellular glycogen levels and defects in N-glycosylation targets that are important for the survival of PDACs, including the epidermal growth factor receptor (EGFR). These critical roles of UGP2 in cancer maintenance, metabolism, and protein glycosylation may offer insights into therapeutic options for otherwise intractable PDACs.
Assuntos
Carcinoma Ductal Pancreático/enzimologia , Regulação Enzimológica da Expressão Gênica/fisiologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Glicogênio/biossíntese , Neoplasias Pancreáticas/enzimologia , UTP-Glucose-1-Fosfato Uridililtransferase/metabolismo , Animais , Carcinoma Ductal Pancreático/patologia , Linhagem Celular Tumoral , Técnicas de Silenciamento de Genes , Glicosilação , Humanos , Camundongos , Camundongos Nus , Neoplasias Experimentais , Neoplasias Pancreáticas/patologia , Fatores de Transcrição de Domínio TEA/genética , Fatores de Transcrição de Domínio TEA/metabolismo , UTP-Glucose-1-Fosfato Uridililtransferase/genética , Proteínas de Sinalização YAP/genética , Proteínas de Sinalização YAP/metabolismoRESUMO
The translational control of oncoprotein expression is implicated in many cancers. Here we report an eIF4A RNA helicase-dependent mechanism of translational control that contributes to oncogenesis and underlies the anticancer effects of silvestrol and related compounds. For example, eIF4A promotes T-cell acute lymphoblastic leukaemia development in vivo and is required for leukaemia maintenance. Accordingly, inhibition of eIF4A with silvestrol has powerful therapeutic effects against murine and human leukaemic cells in vitro and in vivo. We use transcriptome-scale ribosome footprinting to identify the hallmarks of eIF4A-dependent transcripts. These include 5' untranslated region (UTR) sequences such as the 12-nucleotide guanine quartet (CGG)4 motif that can form RNA G-quadruplex structures. Notably, among the most eIF4A-dependent and silvestrol-sensitive transcripts are a number of oncogenes, superenhancer-associated transcription factors, and epigenetic regulators. Hence, the 5' UTRs of select cancer genes harbour a targetable requirement for the eIF4A RNA helicase.
Assuntos
Regiões 5' não Traduzidas/genética , Fator de Iniciação 4A em Eucariotos/metabolismo , Quadruplex G , Proteínas Oncogênicas/biossíntese , Proteínas Oncogênicas/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Biossíntese de Proteínas , Animais , Antineoplásicos Fitogênicos/farmacologia , Antineoplásicos Fitogênicos/uso terapêutico , Sequência de Bases , Linhagem Celular Tumoral , Epigênese Genética , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Motivos de Nucleotídeos , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Biossíntese de Proteínas/efeitos dos fármacos , Ribossomos/metabolismo , Fatores de Transcrição/metabolismo , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/genética , Triterpenos/farmacologiaRESUMO
Epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase that is frequently modified by glycosylation post-translationally. In cancer, EGFR amplifications and hotspot mutations such as L858R that promote proliferation have been detected in a significant fraction of non-small cell lung carcinomas and breast adenocarcinomas. Molecular dynamic simulations suggested that glycosylation at asparagine residue 361 (N361) promotes dimerization and ligand binding. We stably expressed glycosylation-deficient mutant EGFR N361A, with or without the oncogenic mutation L858R. Immunofluorescence and flow cytometry demonstrated that the mutants were each well expressed at the cell membrane. N361A decreased proliferation relative to wild-type EGFR as well as decreased sensitivity to ligands. Proximity ligation assays measuring co-localization of EGFR with its binding partner HER2 in cells revealed that N361A mutations increased co-localization. N361A, located near the binding interface for the EGFR inhibitor necitumumab, desensitized cells expressing the oncogenic EGFR L858R to antibody-based inhibition. These findings underline the critical relevance of post-translational modifications on oncogene function.
RESUMO
KRAS is a small GTPase that is among the most commonly mutated oncogenes in cancer. Here, we discuss KRAS biology, therapeutic avenues to target it, and mechanisms of resistance that tumors employ in response to KRAS inhibition. Several strategies are under investigation for inhibiting oncogenic KRAS, including small molecule compounds targeting specific KRAS mutations, pan-KRAS inhibitors, PROTACs, siRNAs, PNAs, and mutant KRAS-specific immunostimulatory strategies. A central challenge to therapeutic effectiveness is the frequent development of resistance to these treatments. Direct resistance mechanisms can involve KRAS mutations that reduce drug efficacy or copy number alterations that increase the expression of mutant KRAS. Indirect resistance mechanisms arise from mutations that can rescue mutant KRAS-dependent cells either by reactivating the same signaling or via alternative pathways. Further, non-mutational forms of resistance can take the form of epigenetic marks, transcriptional reprogramming, or alterations within the tumor microenvironment. As the possible strategies to inhibit KRAS expand, understanding the nuances of resistance mechanisms is paramount to the development of both enhanced therapeutics and innovative drug combinations.
Assuntos
Resistencia a Medicamentos Antineoplásicos , Neoplasias , Proteínas Proto-Oncogênicas p21(ras) , Humanos , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/antagonistas & inibidores , Neoplasias/tratamento farmacológico , Antineoplásicos/uso terapêutico , Antineoplásicos/farmacologia , MutaçãoRESUMO
Downregulation of the PTEN tumor suppressor transcript is frequent in breast cancer and associates with poor prognosis and triple-negative breast cancer (TNBC) when comparing breast cancers to one another. Here we show that in almost all cases, when comparing breast tumors to adjacent normal ducts, PTEN expression is decreased and the PRC2-associated methyltransferase EZH2 is increased. We further find that when comparing breast cancer cases in large cohorts, EZH2 inversely correlates with PTEN expression. Within the highest EZH2 expressing group, NOTCH alterations are frequent, and also associate with decreased PTEN expression. We show that repression of PTEN occurs through the combined action of NOTCH (NOTCH1 or NOTCH2) and EZH2 alterations in a subset of breast cancers. In fact, in cases harboring NOTCH1 mutation or a NOTCH2 fusion gene, NOTCH drives EZH2, HES-1, and HEY-1 expression to repress PTEN transcription at the promoter, which may contribute to poor prognosis in this subgroup. Restoration of PTEN expression can be achieved with an EZH2 inhibitor (UNC1999), a γ-secretase inhibitor (Compound E), or knockdown of EZH2 or NOTCH. These findings elucidate a mechanism of transcriptional repression of PTEN induced by NOTCH1 or NOTCH2 alterations, and identifies actionable signaling pathways responsible for driving a large subset of poor-prognosis breast cancers.
Assuntos
Neoplasias da Mama/enzimologia , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Receptor Notch1/metabolismo , Receptor Notch2/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Proliferação de Células , Regulação para Baixo , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Fusão Gênica , Humanos , Mutação , PTEN Fosfo-Hidrolase/genética , Receptor Notch1/genética , Receptor Notch2/genética , Transcrição GênicaRESUMO
Inhibition of the eIF4A RNA helicase with silvestrol and related compounds is emerging as a powerful anti-cancer strategy. We find that a synthetic silvestrol analogue (CR-1-31 B) has nanomolar activity across many cancer cell lines. It is especially active against aggressive MYC+/BCL2+ B cell lymphomas and this likely reflects the eIF4A-dependent translation of both MYC and BCL2. We performed a genome-wide CRISPR/Cas9 screen and identified mechanisms of resistance to this new class of therapeutics. We identify three negative NRF2 regulators (KEAP1, CUL3, CAND1) whose inactivation is sufficient to cause CR1-31-B resistance. NRF2 is known to alter the oxidation state of translation factors and cause a broad increase in protein production. We find that NRF2 activation particularly increases the translation of some eIF4A-dependent mRNAs and restores MYC and BCL2 production. We know that NRF2 functions depend on removal of sugar adducts by the frutosamine-3-kinase (FN3K). Accordingly, loss of FN3K results in NRF2 hyper-glycation and inactivation and resensitizes cancer cells to eIF4A inhibition. Together, our findings implicate NRF2 in the translation of eIF4A-dependent mRNAs and point to FN3K inhibition as a new strategy to block NRF2 functions in cancer.
RESUMO
The posttranscriptional control of gene expression by microRNAs (miRNAs) is highly redundant, and compensatory effects limit the consequences of the inactivation of individual miRNAs. This implies that only a few miRNAs can function as effective tumor suppressors. It is also the basis of our strategy to define functionally relevant miRNA target genes that are not under redundant control by other miRNAs. We identified a functionally interconnected group of miRNAs that exhibited a reduced abundance in leukemia cells from patients with T cell acute lymphoblastic leukemia (T-ALL). To pinpoint relevant target genes, we applied a machine learning approach to eliminate genes that were subject to redundant miRNA-mediated control and to identify those genes that were exclusively targeted by tumor-suppressive miRNAs. This strategy revealed the convergence of a small group of tumor suppressor miRNAs on the Myb oncogene, as well as their effects on HBP1, which encodes a transcription factor. The expression of both genes was increased in T-ALL patient samples, and each gene promoted the progression of T-ALL in mice. Hence, our systematic analysis of tumor suppressor miRNA action identified a widespread mechanism of oncogene activation in T-ALL.
Assuntos
Regulação Neoplásica da Expressão Gênica/genética , Genes Supressores de Tumor , Genes myb/genética , MicroRNAs/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Transferência Adotiva , Animais , Inteligência Artificial , Transplante de Células-Tronco Hematopoéticas , Proteínas de Grupo de Alta Mobilidade/genética , Proteínas de Grupo de Alta Mobilidade/metabolismo , Humanos , Camundongos , MicroRNAs/metabolismo , Modelos Genéticos , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Subpopulações de Linfócitos T/metabolismoRESUMO
The importance of individual microRNAs (miRNAs) has been established in specific cancers. However, a comprehensive analysis of the contribution of miRNAs to the pathogenesis of any specific cancer is lacking. Here we show that in T-cell acute lymphoblastic leukemia (T-ALL), a small set of miRNAs is responsible for the cooperative suppression of several tumor suppressor genes. Cross-comparison of miRNA expression profiles in human T-ALL with the results of an unbiased miRNA library screen allowed us to identify five miRNAs (miR-19b, miR-20a, miR-26a, miR-92 and miR-223) that are capable of promoting T-ALL development in a mouse model and which account for the majority of miRNA expression in human T-ALL. Moreover, these miRNAs produce overlapping and cooperative effects on tumor suppressor genes implicated in the pathogenesis of T-ALL, including IKAROS (also known as IKZF1), PTEN, BIM, PHF6, NF1 and FBXW7. Thus, a comprehensive and unbiased analysis of miRNA action in T-ALL reveals a striking pattern of miRNA-tumor suppressor gene interactions in this cancer.
Assuntos
Redes Reguladoras de Genes , Genes Supressores de Tumor , MicroRNAs/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Adolescente , Adulto , Animais , Apoptose , Biomarcadores Tumorais/genética , Western Blotting , Linhagem Celular Tumoral , Proliferação de Células , Criança , Pré-Escolar , Feminino , Imunofluorescência , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Técnicas Imunoenzimáticas , Lactente , Luciferases/metabolismo , Masculino , Camundongos , MicroRNAs/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Taxa de Sobrevida , Adulto JovemRESUMO
New anticancer drugs that target oncogenic signaling molecules have greatly improved the treatment of certain cancers. However, resistance to targeted therapeutics is a major clinical problem and the redundancy of oncogenic signaling pathways provides back-up mechanisms that allow cancer cells to escape. For example, the AKT and PIM kinases produce parallel oncogenic signals and share many molecular targets, including activators of cap-dependent translation. Here, we show that PIM kinase expression can affect the clinical outcome of lymphoma chemotherapy. We observe the same in animal lymphoma models. Whereas chemoresistance caused by AKT is readily reversed with rapamycin, PIM-mediated resistance is refractory to mTORC1 inhibition. However, both PIM- and AKT-expressing lymphomas depend on cap-dependent translation, and genetic or pharmacological blockade of the translation initiation complex is highly effective against these tumors. The therapeutic effect of blocking cap-dependent translation is mediated, at least in part, by decreased production of short-lived oncoproteins including c-MYC, Cyclin D1, MCL1, and the PIM1/2 kinases themselves. Hence, targeting the convergence of oncogenic survival signals on translation initiation is an effective alternative to combinations of kinase inhibitors.
Assuntos
Linfoma/metabolismo , Biossíntese de Proteínas , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Capuzes de RNA/metabolismo , Transdução de Sinais , Animais , Antibióticos Antineoplásicos/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Linfoma/tratamento farmacológico , Linfoma/genética , Alvo Mecanístico do Complexo 1 de Rapamicina , Camundongos , Complexos Multiproteicos , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Proteínas/genética , Proteínas/metabolismo , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-pim-1/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-pim-1/genética , Capuzes de RNA/genética , Sirolimo/farmacologia , Serina-Treonina Quinases TOR , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Células Tumorais CultivadasRESUMO
Genetically and pathologically accurate mouse models of leukemia and lymphoma have been developed in recent years. Adoptive transfer of genetically modified hematopoietic progenitor cells enables rapid and highly controlled gain- and loss-of-function studies for these types of cancer. In this Commentary, we discuss how these highly versatile experimental approaches can be used as biological filters to pinpoint transformation-relevant activities from complex cancer genome data. We anticipate that the functional identification of genetic 'drivers' using mouse models of leukemia and lymphoma will facilitate the development of molecular diagnostics and mechanism-based therapies for patients that suffer from these diseases.
Assuntos
Bases de Dados Genéticas , Modelos Animais de Doenças , Genoma/genética , Neoplasias Hematológicas/genética , Pesquisa Translacional Biomédica , Animais , Humanos , CamundongosRESUMO
MicroRNAs (miRNAs) have emerged as novel cancer genes. In particular, the miR-17-92 cluster, containing six individual miRNAs, is highly expressed in haematopoietic cancers and promotes lymphomagenesis in vivo. Clinical use of these findings hinges on isolating the oncogenic activity within the 17-92 cluster and defining its relevant target genes. Here we show that miR-19 is sufficient to promote leukaemogenesis in Notch1-induced T-cell acute lymphoblastic leukaemia (T-ALL) in vivo. In concord with the pathogenic importance of this interaction in T-ALL, we report a novel translocation that targets the 17-92 cluster and coincides with a second rearrangement that activates Notch1. To identify the miR-19 targets responsible for its oncogenic action, we conducted a large-scale short hairpin RNA screen for genes whose knockdown can phenocopy miR-19. Strikingly, the results of this screen were enriched for miR-19 target genes, and include Bim (Bcl2L11), AMP-activated kinase (Prkaa1) and the phosphatases Pten and PP2A (Ppp2r5e). Hence, an unbiased, functional genomics approach reveals a coordinate clampdown on several regulators of phosphatidylinositol-3-OH kinase-related survival signals by the leukaemogenic miR-19.