RESUMO
Malignant mesothelioma (MpM) is an aggressive, invariably fatal tumour that is causally linked with asbestos exposure. The disease primarily results from loss of tumour suppressor gene function and there are no 'druggable' driver oncogenes associated with MpM. To identify opportunities for management of this disease we have carried out polysome profiling to define the MpM translatome. We show that in MpM there is a selective increase in the translation of mRNAs encoding proteins required for ribosome assembly and mitochondrial biogenesis. This results in an enhanced rate of mRNA translation, abnormal mitochondrial morphology and oxygen consumption, and a reprogramming of metabolic outputs. These alterations delimit the cellular capacity for protein biosynthesis, accelerate growth and drive disease progression. Importantly, we show that inhibition of mRNA translation, particularly through combined pharmacological targeting of mTORC1 and 2, reverses these changes and inhibits malignant cell growth in vitro and in ex-vivo tumour tissue from patients with end-stage disease. Critically, we show that these pharmacological interventions prolong survival in animal models of asbestos-induced mesothelioma, providing the basis for a targeted, viable therapeutic option for patients with this incurable disease.
Assuntos
Mesotelioma Maligno/genética , Oncogenes/genética , Biossíntese de Proteínas/genética , RNA Mensageiro/genética , Animais , Amianto , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/antagonistas & inibidores , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Mesotelioma Maligno/induzido quimicamente , Mesotelioma Maligno/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/genética , Mitocôndrias/metabolismo , Naftiridinas/farmacologia , Polirribossomos/efeitos dos fármacos , Polirribossomos/metabolismo , Biossíntese de Proteínas/efeitos dos fármacos , RNA Mensageiro/metabolismo , Células Tumorais CultivadasAssuntos
Adenocarcinoma/genética , Biomarcadores Tumorais/genética , Carcinoma de Células Escamosas/genética , Neoplasias Pulmonares/genética , Carcinoma de Pequenas Células do Pulmão/genética , Adenocarcinoma/diagnóstico , Adenocarcinoma/patologia , Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/patologia , Rearranjo Gênico , Humanos , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/patologia , Mutação , Patologia Molecular , Carcinoma de Pequenas Células do Pulmão/diagnóstico , Carcinoma de Pequenas Células do Pulmão/patologiaRESUMO
In situ hybridization is used to visualize nucleic acids in microscopic tissue sections and has in recent years been used successfully to detect microRNAs. We have further optimized a technique to detect and semiquantitatively assay microRNA expression in tissue microarrays derived from formalin-fixed paraffin-embedded archival tumor tissue.
Assuntos
Hibridização In Situ/métodos , MicroRNAs/análise , Neoplasias/genética , Análise Serial de Tecidos/métodos , Formaldeído/química , Regulação Neoplásica da Expressão Gênica , Humanos , MicroRNAs/genética , Inclusão em Parafina/métodos , Fixação de Tecidos/métodosRESUMO
The regulation of protein synthesis plays as important a role as transcriptional control in the control of gene expression. Once thought solely to act globally, translational control has now been shown to be able to control the expression of most genes specifically. Dysregulation of this process is associated with a range of pathological conditions, notably cancer and several neurological disorders, and can occur in many ways. These include alterations in the expression of canonical initiation factors, mutations in regulatory mRNA sequence elements in 5' and 3' untranslated regions (UTRs), such as upstream open reading frames (uORFs), internal ribosome entry segments (IRESs) and micro-RNA (miR) target sites, and the altered expression of trans-acting protein factors that bind to and regulate these elements. Translational control is increasingly open for study in both fresh and fixed tissue, and this rapidly developing field is yielding useful diagnostic and prognostic tools that will hopefully provide new targets for effective treatments.
Assuntos
Neoplasias/genética , Biossíntese de Proteínas/genética , Regulação da Expressão Gênica/genética , Transtornos Heredodegenerativos do Sistema Nervoso/genética , Humanos , MicroRNAs/genética , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genética , RNA Mensageiro/genéticaRESUMO
We have identified a novel motif which consists of the sequence (CCU)(n) as part of a polypyrimidine-rich tract and permits internal ribosome entry. A number of constructs containing variations of this motif were generated and these were found to function as artificial internal ribosome entry segments (AIRESs) in vivo and in vitro in the presence of polypyrimidine tract-binding protein (PTB). The data show that for these sequences to function as IRESs the RNA must be present as a double-stranded stem and, in agreement with this, rather surprisingly, we show that PTB binds strongly to double-stranded RNA. All the cellular 5' untranslated regions (UTRs) tested that harbor this sequence were shown to contain internal ribosome entry segments that are dependent upon PTB for function in vivo and in vitro. This therefore raises the possibility that PTB or its interacting protein partners could provide a bridge between the IRES-RNA and the ribosome. Given the number of putative cellular IRESs that could be dependent on PTB for function, these data strongly suggest that PTB-1 is a universal IRES-trans-acting factor.
