RESUMO
RNA-binding proteins (RBPs) have important roles in tumorigenesis. Although IGF2BP3, an evolutionally conserved RBP, has been reported as a useful diagnostic marker for various cancers and has been considered a regulator of tumorigenesis, little is known of the function of IGF2BP3 because of lack of information regarding IGF2BP3 target mRNAs. Here, we report the identification of IGF2BP3 target mRNAs and IGF2BP3 function in cancer proliferation. We identified mRNAs with altered expression in IGF2BP3-depleted cells by massive sequencing analysis and IGF2BP3-binding RNAs by immunoprecipitation of IGF2BP3 followed by massive sequencing analysis, resulting in the identification of 110 candidates that are negatively regulated by IGF2BP3. We found that IGF2BP3 destabilized EIF4E-BP2 and MEIS3 mRNAs. Co-immunoprecipitation analysis revealed the interaction between IGF2BP3 and ribonucleases such as XRN2 and exosome component. The retarded proliferation of IGF2BP3-depleted cells was partially rescued by the depletion of EIF4E-BP2, which negatively regulates eukaryotic translation initiation factor 4E (eIF4E), an activator of translation and a well-known proto-oncogene. Consistent with this observation, IGF2BP3 depletion reduced phosphorylated eIF4E, the active form, and translational efficiency of eIF4E target transcripts. Reduction of phosphorylated eIF4E by IGF2BP3 depletion was rescued by EIF4E-BP2 depletion. At last, we found an inverse correlation between the expression level of IGF2BP3 and EIF4E-BP2 in human lung adenocarcinoma tissues. Together, these results suggest that IGF2BP3 promotes eIF4E-mediated translational activation through the reduction of EIF4E-BP2 via mRNA degradation, leading to enhanced cell proliferation. This is the first report demonstrating that IGF2BP3 is an RNA-destabilizing factor. Notably, here we provide the first evidence for the functional linkage between two previously well-known cancer biomarkers, IGF2BP3 and eIF4E.
Assuntos
Fator de Iniciação 4E em Eucariotos/metabolismo , Fatores de Iniciação em Eucariotos/metabolismo , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/metabolismo , Células A549 , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Western Blotting , Proliferação de Células/genética , Fator de Iniciação 4E em Eucariotos/genética , Fatores de Iniciação em Eucariotos/genética , Exorribonucleases/metabolismo , Expressão Gênica , Células HeLa , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Ligação Proteica , Proto-Oncogene Mas , Interferência de RNA , Estabilidade de RNA/genética , RNA Mensageiro/genética , Proteínas de Ligação a RNA/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
BACKGROUND: Angiomatoid fibrous histiocytoma (AFH) is a rare soft-tissue tumour of uncertain differentiation and low metastatic potential. Cytogenetics and/or molecular genetics have revealed that most have a rearrangement of the EWSR1 gene, whereas a FUS gene rearrangement is present in a minority of cases. Although some cases of AFH display striking pleomorphism and mitotic activity, there are no known clinical, morphological or genetic factors that predict metastasis. The authors present clinicopathological features of AFH, including cases showing a pleomorphic histological appearance, and results of fluorescence in situ hybridisation analysis of EWSR1 and FUS rearrangements. METHODS: Tumour samples from 10 patients were subjected to clinicopathological and immunohistochemical analysis and dual-colour fluorescence in situ hybridisation for EWSR1 and FUS with split-signal probes. RESULTS: All cases showed clinical features (sites: extremities followed by trunk; age: adolescent to young adult), morphology (multinodular proliferation of spindle cells, lymphoid cuffs and pseudovascular spaces) and immunohistochemical results (more than half were positive for CD68, CD99, desmin and epithelial membrane antigen) typical of AFH. There were two local recurrences in each of two patients. Two patients developed distant metastases and died from the disease; tumours of these two patients showed focal proliferation of large pleomorphic cells with hyperchromatic nuclei and high proliferative activity (>10/10 high-power field and Ki-67 labelling index >10%). There were no clinical, histological or immunohistochemical differences between the nine cases with EWSR1 rearrangement and one case with FUS rearrangement. CONCLUSIONS: Wide surgical excision and careful follow-up are necessary for patients with AFH in view of its risk of local recurrence and metastasis leading to a fatal outcome.
Assuntos
Histiocitoma Fibroso Benigno/genética , Neoplasias de Tecidos Moles/genética , Adulto , Proteínas de Ligação a Calmodulina/genética , Criança , Pré-Escolar , Feminino , Seguimentos , Rearranjo Gênico , Histiocitoma Fibroso Benigno/patologia , Histiocitoma Fibroso Benigno/secundário , Histiocitoma Fibroso Benigno/terapia , Humanos , Hibridização in Situ Fluorescente/métodos , Neoplasias Pulmonares/secundário , Masculino , Pessoa de Meia-Idade , Proteínas de Neoplasias/genética , Recidiva Local de Neoplasia/genética , Proteína EWS de Ligação a RNA , Proteína FUS de Ligação a RNA/genética , Proteínas de Ligação a RNA/genética , Neoplasias de Tecidos Moles/patologia , Neoplasias de Tecidos Moles/terapia , Adulto JovemRESUMO
A patient had triple extramammary Paget's disease of both axillary and genital regions. Right inguinal lymphadenopathy was found 1 year after excision of all the skin lesions. Excisional biopsy of the lymph node demonstrated a mixture of Paget cells and atypical squamoid cells with horn pearls suggestive of keratinization. The squamoid cells were positive for cytokeratin 10, a marker of suprabasal epidermis, and also positive for laminin gamma2 which is often expressed in invasive squamous cell carcinoma. The coexistence of these different cells within the same tumour island suggested that the squamoid cells derived from metaplasia of Paget cells.
Assuntos
Neoplasias dos Genitais Masculinos/patologia , Doença de Paget Extramamária/patologia , Escroto/patologia , Idoso , Axila , Carcinoma de Células Escamosas/patologia , Diagnóstico Diferencial , Humanos , Metástase Linfática/patologia , Masculino , Metaplasia/patologiaRESUMO
A remarkable increase in the permeability of erythrocyte ghosts and liposomal membranes composed of erythrocyte lipids from aged diabetics was revealed by measuring [14C]glucose leakage. There were no significant differences in the contents of free cholesterol or phospholipids, or in the cholesterol/phospholipid ratio between diabetic and normal erythrocyte membranes, but significantly higher amounts of unsaturated fatty acids, arachidonic acid and docosahexaenoic acid were observed in the erythrocyte membranes of diabetics. Reconstituted liposomes prepared from aged diabetic erythrocyte lipids were highly susceptible to superoxide-induced oxidative stress. Vitamin E was highly effective in suppressing the peroxidative lysis of liposomes composed of diabetic erythrocyte lipids. The effect of superoxide dismutase (SOD) on the inhibition of peroxidation of unsaturated lipids within liposomal membranes was less than that of vitamin E.
