RESUMO
Merlin, which is encoded by the tumour suppressor gene Nf2, plays a crucial role in tumorigenesis and metastasis. However, little is known about the functional importance of Merlin splicing forms. In this study, we show that Merlin is present at low levels in human hepatocellular carcinoma (HCC), particularly in metastatic tumours, where it is associated with a poor prognosis. Surprisingly, a splicing variant of Merlin that lacks exons 2, 3 and 4 ((Δ2-4)Merlin) is amplified in HCC and portal vein tumour thrombus (PVTT) specimens and in the CSQT2 cell line derived from PVTT. Our studies show that (Δ2-4)Merlin interferes with the capacity of wild-type Merlin to bind ß-catenin and ERM, and it is expressed in the cytoplasm rather than at the cell surface. Furthermore, (Δ2-4)Merlin overexpression increases the expression levels of ß-catenin and stemness-related genes, induces the epithelium-mesenchymal-transition phenotype promoting cell migration in vitro and the formation of lung metastasis in vivo. Our results indicate that the (Δ2-4)Merlin variant disrupts the normal function of Merlin and promotes tumour metastasis.
Assuntos
Processamento Alternativo , Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , Neoplasias Pulmonares/genética , Neurofibromina 2/genética , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/secundário , Linhagem Celular Tumoral , Citoplasma/metabolismo , Proteínas do Citoesqueleto/metabolismo , Transição Epitelial-Mesenquimal/genética , Feminino , Humanos , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/secundário , Masculino , Proteínas de Membrana/metabolismo , Proteínas dos Microfilamentos/metabolismo , Pessoa de Meia-Idade , Metástase Neoplásica , Neurofibromina 2/metabolismo , Veia Porta/patologia , Trombose/patologia , beta Catenina/metabolismoRESUMO
p204, an inteferon-inducible protein, is known to play an important role in modulating cell proliferation, cell cycling, and the differentiation of various tissues, including osteoblasts. In order to determine the role of p204 during development in vivo, the teleost zebrafish (Danio rerio), an established vertebrate model for developmental studies, was employed. p204 cDNA was introduced into zebrafish by microinjection, and p204 was ectopically expressed throughout the whole embryo during the early stages of zebrafish embryogenesis, then its expression gradually decreased, mainly in ventrally located cells and retina capsules. Importantly, overexpression of p204 in zebrafish resulted in striking malformations such as bent spine and expanded belly. Furthermore, the expressions of some genes (vent, runx2b, osn) involved in dorsoventral patterning and osteogenesis were significantly upregulated after p204 injection. This study provides not only the in vivo evidences demonstrating the role of p204 during embryonic development, but also new insights into the molecular mechanism by which p204 mediate osteogenesis.