RESUMEN
Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphomas are tumors that carry translocations involving the ALK gene at the 2p23 locus, leading to the expression of ALK tyrosine kinase fusion oncoproteins. Amongst hematologic malignancies, these lymphomas are particular in that they express very low levels of B-cell lymphoma 2 (BCL2), a recognized inhibitor of apoptosis and autophagy, two processes that share complex interconnections. We have previously shown that treatment of ALK-positive anaplastic large cell lymphoma cells with the ALK tyrosine kinase inhibitor crizotinib induces autophagy as a pro-survival response. Here, we observed that crizotinib-mediated inactivation of ALK caused an increase in BCL2 levels that restrained the cytotoxic effects of the drug. BCL2 downregulation in combination with crizotinib treatment potentiated loss of cell viability through both an increase in autophagic flux and cell death, including apoptosis. More importantly, our data revealed that the blockade of autophagic flux completely reversed impaired cell viability, which demonstrates that excessive autophagy is associated with cell death. We propose that the downregulation of BCL2 protein, which plays a central role in the autophagic and apoptotic machinery, combined with crizotinib treatment may represent a promising therapeutic alternative to current ALK-positive anaplastic large cell lymphoma treatments.
Asunto(s)
Quinasa de Linfoma Anaplásico/metabolismo , Antineoplásicos/farmacología , Autofagia , Crizotinib/farmacología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Linfoma Anaplásico de Células Grandes/patología , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Quinasa de Linfoma Anaplásico/genética , Animales , Muerte Celular , Proliferación Celular/efectos de los fármacos , Humanos , Linfoma Anaplásico de Células Grandes/tratamiento farmacológico , Linfoma Anaplásico de Células Grandes/metabolismo , Ratones , Ratones Endogámicos NOD , Ratones SCID , Pronóstico , Proteínas Proto-Oncogénicas c-bcl-2/genética , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Programmed death ligand-1 (PD-L1) is a key component of tumor immunosuppression. The uneven therapeutic results of PD-L1 therapy have stimulated intensive studies to better understand the mechanisms underlying altered PD-L1 expression in cancer cells, and to determine whether, beyond its immune function, PD-L1 might have intracellular functions promoting tumor progression and resistance to treatments. In this Opinion, we focus on paradigmatic examples highlighting the central role of PD-L1 in post-transcriptional regulation, with PD-L1 being both a target and an effector of molecular mechanisms featured prominently in RNA research, such as RNA methylation, phase separation and RNA G-quadruplex structures, in order to highlight vulnerabilities on which future anti-PD-L1 therapies could be built.
Asunto(s)
Antígeno B7-H1 , Neoplasias , ARN , Humanos , Antígeno B7-H1/metabolismo , ARN/metabolismo , ARN/genética , Animales , Neoplasias/metabolismo , Neoplasias/genética , Neoplasias/inmunología , Tolerancia Inmunológica , Terapia de Inmunosupresión , Procesamiento Postranscripcional del ARN , Regulación Neoplásica de la Expresión Génica , G-CuádruplexRESUMEN
Although deregulated expression of specific microRNAs (miRNAs) has been described in solid cancers and leukemias, little evidence of miRNA deregulation has been reported in ALK-positive (ALK(+)) anaplastic large cell lymphomas (ALCL). These tumors overexpress the major antiapoptotic protein myeloid cell leukemia 1 (MCL-1), a situation that could compensate for the lack of BCL-2. We report that ALK(+) ALCL cell lines and biopsy specimens (n = 20) express a low level of miR-29a and that this down-modulation requires an active NPM-ALK kinase. Murine models (transgenic mice and mouse embryonic fibroblast [MEF] cells), which allow conditional NPM-ALK fusion protein expression, showed an increase of miR-29a expression in the absence of NPM-ALK. Concordant results were observed after the abolition of NPM-ALK kinase activity (siALK or PF-2341066) in NPM-ALK(+) ALCL cell lines. In addition, we showed that low expression of miR-29a, probably through methylation repression, plays an important regulatory role in MCL-1 overexpression that could promote tumor cell survival by inhibiting apoptosis. Enforced miR-29a expression was found to modulate apoptosis through inhibition of MCL-1 expression in ALCL cell lines and in a xenografted model, with a concomitant tumor growth reduction. Thus, synthetic miR-29a represents a potential new tool to affect tumorigenesis in these lymphomas.
Asunto(s)
Apoptosis/genética , Linfoma Anaplásico de Células Grandes/genética , MicroARNs/genética , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Tirosina Quinasas Receptoras/genética , Quinasa de Linfoma Anaplásico , Animales , Línea Celular Tumoral , Células Cultivadas , Regulación hacia Abajo/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Linfoma Anaplásico de Células Grandes/metabolismo , Linfoma Anaplásico de Células Grandes/patología , Ratones , Ratones Endogámicos NOD , Ratones SCID , Ratones Transgénicos , MicroARNs/metabolismo , MicroARNs/fisiología , Proteína 1 de la Secuencia de Leucemia de Células Mieloides , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Regulación hacia Arriba/genética , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Autophagy has been described as harboring a dual role in cancer development and therapy. Depending on the context, it can exert either pro-survival or pro-death functions. Here, we review what is known about autophagy in crizotinib-treated ALK+ ALCL. We first present our main findings on the role and regulation of autophagy in these cells. Then, we provide literature-driven hypotheses that could explain mechanistically the pro-survival properties of autophagy in crizotinib-treated bulk and stem-like ALK+ ALCL cells. Finally, we discuss how the potentiation of autophagy, which occurs with combined therapies (ALK and BCL2 or ALK and RAF1 co-inhibition), could convert it from a survival mechanism to a pro-death process.
Asunto(s)
Autofagia/efectos de los fármacos , Crizotinib/farmacología , Resistencia a Antineoplásicos/efectos de los fármacos , Linfoma/tratamiento farmacológico , Quinasa de Linfoma Anaplásico/efectos de los fármacos , Humanos , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Tirosina Quinasas Receptoras/efectos de los fármacosRESUMEN
Anaplastic large cell lymphomas associated with ALK translocation have a good outcome after CHOP treatment; however, the 2-year relapse rate remains at 30%. Microarray gene-expression profiling of 48 samples obtained at diagnosis was used to identify 47 genes that were differentially expressed between patients with early relapse/progression and no relapse. In the relapsing group, the most significant overrepresented genes were related to the regulation of the immune response and T-cell activation while those in the non-relapsing group were involved in the extracellular matrix. Fluidigm technology gave concordant results for 29 genes, of which FN1, FAM179A, and SLC40A1 had the strongest predictive power after logistic regression and two classification algorithms. In parallel with 39 samples, we used a Kallisto/Sleuth pipeline to analyze RNA sequencing data and identified 20 genes common to the 28 genes validated by Fluidigm technology-notably, the FAM179A and FN1 genes. Interestingly, FN1 also belongs to the gene signature predicting longer survival in diffuse large B-cell lymphomas treated with CHOP. Thus, our molecular signatures indicate that the FN1 gene, a matrix key regulator, might also be involved in the prognosis and the therapeutic response in anaplastic lymphomas.
RESUMEN
Anaplastic lymphoma kinase positive anaplastic large cell lymphomas (ALK+ ALCL) are an aggressive pediatric disease. The therapeutic options comprise chemotherapy, which is efficient in approximately 70% of patients, and targeted therapies, such as crizotinib (an ALK tyrosine kinase inhibitor (TKI)), used in refractory/relapsed cases. Research efforts have also converged toward the development of combined therapies to improve treatment. In this context, we studied whether autophagy could be modulated to improve crizotinib therapy. Autophagy is a vesicular recycling pathway, known to be associated with either cell survival or cell death depending on the cancer and therapy. We previously demonstrated that crizotinib induced cytoprotective autophagy in ALK+ lymphoma cells and that its further intensification was associated with cell death. In line with these results, we show here that combined ALK and Rapidly Accelerated Fibrosarcoma 1 (RAF1) inhibition, using pharmacological (vemurafenib) or molecular (small interfering RNA targeting RAF1 (siRAF1) or microRNA-7-5p (miR-7-5p) mimics) strategies, also triggered autophagy and potentiated the toxicity of TKI. Mechanistically, we found that this combined therapy resulted in the decrease of the inhibitory phosphorylation on Unc-51-like kinase-1 (ULK1) (a key protein in autophagy initiation), which may account for the enforced autophagy and cytokilling effect. Altogether, our results support the development of ALK and RAF1 combined inhibition as a new therapeutic approach in ALK+ ALCL.
RESUMEN
Majority of anaplastic large-cell lymphomas (ALCLs) are associated with the t(2;5)(p23;q35) translocation, fusing the NPM (nucleophosmin) and ALK (anaplastic lymphoma kinase) genes (NPM-ALK). Recent studies demonstrated that ALK may also be involved in variant translocations, namely, t(1;2)(q25;p23), t(2;3)(p23;q21), t(2;17)(p23;q23) and inv(2)(p23q35), which create the TPM3-ALK, TFG-ALK5, CLTC-ALK, and ATIC-ALK fusion genes, respectively. Although overexpression of NPM-ALK has previously been shown to transform fibroblasts, the transforming potential of variant X-ALK proteins has not been precisely investigated. We stably transfected the cDNAs coding for NPM-ALK, TPM3-ALK, TFG-ALK, CLTC-ALK or ATIC-ALK into nonmalignant NIH3T3 cells. All X-ALK variants are tyrosine phosphorylated and their subcellular distribution was in agreement with that observed in tumors. Moreover, our results show that the in vitro transforming capacity of NIH3T3-transfected cells are in relation to the level of X-ALK fusion proteins excepted for TPM3-ALK for which there is an inverse correlation. The differences between the five X-ALK variants with regard to proliferation rate, colony formation in soft agar, invasion, migration through the endothelial barrier and tumorigenicity seem to be due to differential activation of various signaling pathways such as PI3-kinase/AKT. These findings may have clinical implications in the pathogenesis and prognosis of ALK-positive ALCLs.
Asunto(s)
Transformación Celular Neoplásica , Proteínas Tirosina Quinasas/genética , Quinasa de Linfoma Anaplásico , Animales , División Celular , Línea Celular , Línea Celular Transformada , Movimiento Celular , Humanos , Ratones , Ratones Desnudos , Células 3T3 NIH , Invasividad Neoplásica , Neoplasias Experimentales/patología , Proteínas Tirosina Quinasas Receptoras , Proteínas Recombinantes de Fusión/análisis , Proteínas Recombinantes de Fusión/genética , Transducción de Señal , TransfecciónRESUMEN
Extensive research has been carried out in the past two decades to provide insights into the molecular mechanisms by which the Nucleophosmin-Anaplastic Lymphoma Kinase (NPM-ALK) exerts its oncogenic effects. These studies led to the concept that NPM-ALK acts at the transcriptional level through the activation of several transcription factors downstream of many different signaling pathways including JAK3/STAT3, PI3K/AKT and RAS/ERK. Nevertheless, the discovery of several RNA-binding proteins (RBPs) within ALK interactome suggested an additional and complementary role of this oncogenic kinase at the post-transcriptional level. This review gives emerging views in ALK-mediated post-transcriptional regulation with a focus on RBPs that are associated with ALK. We will summarize the capacity of NPM-ALK in modulating the biological properties of RBPs and then discuss the role of cytoplasmic aggregates, called AGs for "ALK granules", which are observed in anaplastic large cell lymphoma (ALCL) expressing the ALK kinase. AGs contain polyadenylated mRNAs and numerous RBPs but are distinct from processing bodies (PBs) and stress granules (SGs), two well-known discrete cytoplasmic sites involved in mRNA fate.
Asunto(s)
Modelos Genéticos , Proteínas de Unión al ARN/fisiología , Proteínas Tirosina Quinasas Receptoras/fisiología , Quinasa de Linfoma Anaplásico , Regulación de la Expresión Génica , Procesamiento Postranscripcional del ARN , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Proteínas Tirosina Quinasas Receptoras/genética , Proteínas Tirosina Quinasas Receptoras/metabolismo , Ribonucleoproteínas/metabolismo , Ribonucleoproteínas/fisiologíaRESUMEN
Anaplastic Lymphoma Kinase-positive Anaplastic Large Cell Lymphomas (ALK+ ALCL) occur predominantly in children and young adults. Their treatment, based on aggressive chemotherapy, is not optimal since ALCL patients can still expect a 30% 2-year relapse rate. Tumor relapses are very aggressive and their underlying mechanisms are unknown. Crizotinib is the most advanced ALK tyrosine kinase inhibitor and is already used in clinics to treat ALK-associated cancers. However, crizotinib escape mechanisms have emerged, thus preventing its use in frontline ALCL therapy. The process of autophagy has been proposed as the next target for elimination of the resistance to tyrosine kinase inhibitors. In this study, we investigated whether autophagy is activated in ALCL cells submitted to ALK inactivation (using crizotinib or ALK-targeting siRNA). Classical autophagy read-outs such as autophagosome visualization/quantification by electron microscopy and LC3-B marker turn-over assays were used to demonstrate autophagy induction and flux activation upon ALK inactivation. This was demonstrated to have a cytoprotective role on cell viability and clonogenic assays following combined ALK and autophagy inhibition. Altogether, our results suggest that co-treatment with crizotinib and chloroquine (two drugs already used in clinics) could be beneficial for ALK-positive ALCL patients.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Autofagia/efectos de los fármacos , Cloroquina/farmacología , Linfoma Anaplásico de Células Grandes/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/farmacología , Pirazoles/farmacología , Piridinas/farmacología , Proteínas Tirosina Quinasas Receptoras/antagonistas & inhibidores , Quinasa de Linfoma Anaplásico , Animales , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Crizotinib , Relación Dosis-Respuesta a Droga , Sinergismo Farmacológico , Femenino , Humanos , Linfoma Anaplásico de Células Grandes/enzimología , Linfoma Anaplásico de Células Grandes/genética , Linfoma Anaplásico de Células Grandes/patología , Ratones Endogámicos NOD , Ratones SCID , Proteínas Asociadas a Microtúbulos/metabolismo , Interferencia de ARN , Proteínas Tirosina Quinasas Receptoras/genética , Proteínas Tirosina Quinasas Receptoras/metabolismo , Transducción de Señal/efectos de los fármacos , Factores de Tiempo , Transfección , Ensayos Antitumor por Modelo de XenoinjertoAsunto(s)
ADN de Neoplasias/análisis , Técnicas de Diagnóstico Molecular , Neoplasias/diagnóstico , Metilación de ADN , Sondas de ADN , Dosificación de Gen , Perfilación de la Expresión Génica , Humanos , Espectrometría de Masas/métodos , Nanotecnología , Neoplasias/genética , Neoplasias/patología , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Polimorfismo de Nucleótido Simple , ARN Mensajero/análisis , ARN Mensajero/genética , ARN Neoplásico/análisis , ARN Neoplásico/genética , Análisis de Secuencia de ADN/métodosRESUMEN
Numerous cytoplasmic foci containing mRNA s and their associated proteins have been described in mammalian somatic and germ cells. The best studied examples are given by the processing bodies (PBs) that are present in all cell types, and the stress granules (SGs) that are transiently formed following stress stimuli. Those foci are non-membranous dynamic structures that, through the continuous exchange of their content with the cytoplasm, are believed to control mRNA storage, translation and degradation. However, due in part to the fact that their composition has not been fully characterized, their relevance to mRNA regulation and cell survival remains a matter of debate. In a recent study, we described new cytoplasmic foci that form specifically in transformed cells expressing the constitutively active ALK tyrosine kinase. Those granules, further called AGs for ALK granules, contain polyadenylated mRNAs but are distinct from PBs and SGs. Using a method based on sucrose density gradient fractionation, we further purified AGs and identified their mRNA content. We discuss our findings in relation to other granules containing untranslated mRNAs and speculate on the possible contribution of AGs to the oncogenic properties of ALK-expressing cells.
RESUMEN
The CCAAT/enhancer-binding protein ß (C/EBPß) plays a major role in the pathogenesis of anaplastic large cell lymphomas (ALCL) that express the nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) tyrosine kinase (ALK(+)). Although ALK-mediated C/EBPß transcriptional activation has been reported, C/EBPß mRNA possesses U- and AU-rich domains in its 3'-untranslated region (3'-UTR) that might be privileged targets for posttranscriptional control in ALK(+) ALCLs. The purpose of this study was to explore this possibility. By using human ALCL-derived cells and a murine model of ALK-transformed cells, we show that the AU-binding protein HuR binds to the 3'-UTR of C/EBPß mRNA, as previously reported in adipocytes, and that NPM-ALK enhances this interaction. Interaction between HuR and C/EBPß mRNA impacts on C/EBPß gene expression at both the mRNA and protein levels. Indeed, C/EBPß mRNA stability following HuR silencing is reduced and reaches the value observed in ALK-inactivated cells. Remarkably, HuR expression is not modified by NPM-ALK, but its association with actively translating polysomes is dramatically increased in ALK(+) cells. HuR/polysomes association diminishes when NPM-ALK activity is inhibited and is accompanied by a concomitant decrease of C/EBPß mRNA translation. Finally, we show that HuR and NPM-ALK colocalized in cytoplasmic granules and HuR is phosphroylated on tyrosine residues in ALK(+) ALCL cells. Our study thus demonstrates that C/EBPß is indeed regulated at the posttranscriptional level by HuR in ALK(+) cells, leading us to propose that part of NPM-ALK oncogenic properties relies on its ability to modify HuR properties in the cytoplasm and hence to alter expression of key actors of transformation.
Asunto(s)
Antígenos de Superficie/metabolismo , Proteínas Potenciadoras de Unión a CCAAT/genética , Regulación Neoplásica de la Expresión Génica , Linfoma Anaplásico de Células Grandes/genética , Estabilidad del ARN , Proteínas de Unión al ARN/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Regiones no Traducidas 3'/genética , Quinasa de Linfoma Anaplásico , Animales , Antígenos de Superficie/genética , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Línea Celular Tumoral , Transformación Celular Neoplásica/genética , Proteínas ELAV , Proteína 1 Similar a ELAV , Humanos , Linfoma Anaplásico de Células Grandes/metabolismo , Ratones , Células 3T3 NIH , Biosíntesis de Proteínas/genética , Proteínas Tirosina Quinasas/genética , Proteínas Tirosina Quinasas/metabolismo , Proteínas de Unión al ARN/genética , Proteínas Tirosina Quinasas Receptoras/genéticaRESUMEN
With the use of microarray gene-expression profiling, we analyzed a homogeneous series of 32 patients with systemic anaplastic large-cell lymphoma (ALCL) and 5 ALCL cell lines. Unsupervised analysis classified ALCL in 2 clusters, corresponding essentially to morphologic subgroups (ie, common type vs small cell and "mixed" variants) and clinical variables. Patients with a morphologic variant of ALCL had advanced-stage disease. This group included a significant number of patients who experienced early relapse. Supervised analysis showed that ALK+ALCL and ALK- ALCL have different gene-expression profiles, further confirming that they are different entities. Among the most significantly differentially expressed genes between ALK+ and ALK- samples, we found BCL6, PTPN12, CEBPB, and SERPINA1 genes to be overexpressed in ALK+ ALCL. This result was confirmed at the protein level for BCL-6, C/EBPbeta and serpinA1 through tissue microarrays. The molecular signature of ALK- ALCL included overexpression of CCR7, CNTFR, IL22, and IL21 genes but did not provide any obvious clues to the molecular mechanism underlying this tumor subtype. Once confirmed on a larger number of patients, the results of the present study could be used for clinical and therapeutic management of patients at the time of diagnosis.
Asunto(s)
Forma de la Célula , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Linfoma Anaplásico de Células Grandes/genética , Linfoma Anaplásico de Células Grandes/patología , Proteínas Tirosina Quinasas/genética , Quinasa de Linfoma Anaplásico , Línea Celular Tumoral , Humanos , Inmunohistoquímica , Linfoma Anaplásico de Células Grandes/clasificación , Linfoma Anaplásico de Células Grandes/enzimología , Proteínas Tirosina Quinasas/metabolismo , ARN Mensajero/genética , Proteínas Tirosina Quinasas Receptoras , Análisis de Matrices TisularesRESUMEN
Anaplastic large-cell lymphomas (ALCL) are high grade lymphomas of T or null phenotype often associated with the t(2;5) translocation leading to the expression of a chimeric protein consisting of the N-terminal portion of nucleophosmin (NPM) and the intracellular domain of the anaplastic lymphoma kinase (ALK). Although ALCL are recognized as distinct clinical, biological and cytogenetic entities, heterogeneities persist in this group of tumours, which exhibit a broad spectrum of morphological features. Particularly, the common type tumour consisting in large cells contrast with the small cell variant that is sometimes associated with a leukemic phase. The ALK-negative ALCL is often associated with a poor prognosis. Here, we investigated the proteome of these subtypes of tumours using patient-derived cell lines. We compared the proteome of the cytosolic fraction of NPM-ALK-positive versus NPM-ALK-negative cells on one hand, and the proteome of common cell type versus small cell variant on the other hand. The identification of a set of proteins differentially expressed in the subtypes of ALCL points to new diagnosis/prognosis markers. This study also provides interesting information on the molecular mechanisms responsible for the different subtypes of ALCL.
Asunto(s)
Biomarcadores de Tumor/biosíntesis , Linfoma de Células B Grandes Difuso/metabolismo , Proteoma/biosíntesis , Quinasa de Linfoma Anaplásico , Línea Celular Tumoral , Citosol/metabolismo , Electroforesis en Gel Bidimensional , Humanos , Inmunohistoquímica , Linfoma de Células B Grandes Difuso/diagnóstico , Linfoma de Células B Grandes Difuso/patología , Proteínas Nucleares/biosíntesis , Nucleofosmina , Fenotipo , Pronóstico , Proteínas Tirosina Quinasas/biosíntesis , Proteínas Tirosina Quinasas Receptoras , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
In anaplastic large cell lymphoma, the ALK gene at 2p23 is known to be fused to NPM, TPM3, TPM4, TFG, ATIC, CLTC, MSN, and ALO17. All of these translocations result in the expression of chimeric ALK transcripts that are translated into fusion proteins with tyrosine kinase activity and oncogenic properties. We report a case showing a restricted cytoplasmic staining pattern of ALK and a novel chromosomal abnormality, t(2;22)(p23;q11.2), demonstrated by fluorescence in situ hybridization analysis. The result of 5' RACE analysis showed that the ALK gene was fused in-frame to a portion of the non-muscle myosin heavy chain gene, MYH9. Nucleotide sequence of the MYH9-ALK chimeric cDNA revealed that the ALK breakpoint was different from all those previously reported. It is localized in the same exonic sequence as MSN-ALK, but 6 bp downstream, resulting in an in-frame fusion of the two partner proteins. In contrast to the previously reported ALK fusion proteins, MYH9-ALK may lack a functional oligomerization domain. However, biochemical analysis showed that the new fusion protein is tyrosine phosphorylated in vivo but seems to lack tyrosine kinase activity in vitro. If further investigations confirm this latter result, the in vivo tyrosine phosphorylation of MYH9-ALK protein could involve mechanisms different from those described in the other ALK hybrid proteins.
Asunto(s)
Linfoma Anaplásico de Células Grandes/genética , Linfoma de Células T/genética , Proteínas Motoras Moleculares , Cadenas Pesadas de Miosina/genética , Proteínas de Fusión Oncogénica/genética , Proteínas Tirosina Quinasas/genética , Proteínas Tirosina Quinasas Receptoras/genética , Secuencia de Aminoácidos , Quinasa de Linfoma Anaplásico , Secuencia de Bases , Niño , Femenino , Humanos , Datos de Secuencia Molecular , Translocación Genética/genética , Células Tumorales CultivadasRESUMEN
Expression of ALK protein by lymphoid cells and the description of variant anaplastic lymphoma kinase (ALK) translocations have typically been restricted to cases of T-cell and null anaplastic large-cell lymphoma (ALCL). All such cases result from a novel fusion created by the ALK gene on chromosome 2p23 and NPM on 5q35 or other variant translocation partners. A rare variant of diffuse large B-cell lymphoma (DLBCL), originally described in 1997, was thought to overexpress full-length ALK in contrast to a chimeric protein characteristic of ALCL. However, full-length ALK protein lacks tyrosine kinase activity and thus the mechanism of oncogenesis has remained elusive. We describe 6 cases of ALK+ DLBCL characterized by a simple or complex t(2;17)(p23;q23) involving the clathrin gene (CLTC) at chromosome band 17q23 and the ALK gene at chromosome band 2p23. All cases were studied using fluorescence in situ hybridization (FISH), complemented in one case with standard cytogenetic analysis, multicolor karyotyping (M-FISH), and reverse transcriptase-polymerase chain reaction. These results clearly demonstrate that most cases of ALK+ DLBCL share the same mechanism of deregulated ALK expression. Moreover, these results demonstrate the presence of CLTC-ALK fusions in these tumors and extend the list of diseases associated with this genetic abnormality to include classical T-cell or null ALCL, ALK+ DLBCL, and inflammatory myofibroblastic tumors.