RESUMO
Several studies have shown that microRNA-targeting is an effective strategy for the selective control of tissue-tropism and pathogenesis of both DNA and RNA viruses. However, the exploitation of microRNA-targeting for the inhibition of transformation by oncogenic viruses has not been studied. The v-rel oncoprotein encoded by reticuloendotheliosis virus T strain (Rev-T) is a member of the rel/NF-κB family of transcription factors capable of transforming primary chicken spleen and bone marrow cells. Here, by engineering the target sequence of endogenous microRNA miR-142 downstream of the v-rel gene in a Replication-Competent ALV (avian leukosis virus) long terminal repeat (LTR) with a splice acceptor (RCAS) vector and using a v-rel-induced transformation model of chicken embryonic splenocyte cultures, we show that hematopoietic-specific miR-142 can inhibit the v-rel-induced transformation, and that this inhibition effect is due to the silencing of v-rel expression. The data supports the idea that microRNA-targeting can be used to inhibit viral oncogene-induced oncogenesis.
Assuntos
Carcinogênese/genética , Transformação Celular Viral , MicroRNAs/genética , Proteínas Oncogênicas v-rel/genética , Animais , Vírus da Leucose Aviária/genética , Células da Medula Óssea/virologia , Células Cultivadas , Galinhas , Inativação Gênica , NF-kappa B/metabolismo , Proteínas Oncogênicas v-rel/antagonistas & inibidores , Vírus da Reticuloendoteliose/genética , Baço/citologia , Baço/virologia , Fatores de Transcrição/genéticaRESUMO
Expression of inducible nitric oxide synthase (iNOS) protein by lipopolysaccharide (LPS) in BV2 microglia cells increased in a biphasic manner. Glucosamine (GlcN) selectively suppressed the late- but not early-stage iNOS response to LPS. Prolonged induction of iNOS expression by LPS was inhibited by cycloheximide, suggesting that de novo protein synthesis was required. Late-phase activation of nuclear factor-kappaB (NF-κB) activity required for sustained iNOS induction. Nuclear translocation and DNA binding of NF-κB, and Rel proteins expressions were inhibited by GlcN at later time points but not upon immediate early-stage activation by LPS. We show that GlcN selectively inhibits sustained iNOS induction by inhibiting Rel protein expression at both the mRNA and protein levels; such expression is required for prolonged iNOS induction by LPS. Our results provide mechanistic evidence that GlcN regulates inflammation, represented by iNOS. The implication of these results is that GlcN may be a potent transcriptional regulator of iNOS and other genes involved in the general inflammation process.
Assuntos
Glucosamina/farmacologia , Lipopolissacarídeos/antagonistas & inibidores , NF-kappa B/antagonistas & inibidores , Óxido Nítrico Sintase Tipo II/biossíntese , Proteínas Oncogênicas v-rel/antagonistas & inibidores , Animais , Western Blotting , Linhagem Celular , Indução Enzimática/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Camundongos , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/biossíntese , NF-kappa B/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Proteínas Oncogênicas v-rel/biossíntese , Proteínas Oncogênicas v-rel/genética , RNA Mensageiro/antagonistas & inibidores , RNA Mensageiro/genética , Transdução de Sinais/efeitos dos fármacosRESUMO
The Rel/NF-kappa B family is a group of structurally-related, tightly-regulated transcription factors that control the expression of a multitude of genes involved in key cellular and organismal processes. The Rel/NF-kappa B signal transduction pathway is misregulated in a variety of human cancers, especially ones of lymphoid cell origin, due either to genetic changes (such as chromosomal rearrangements, amplifications, and mutations) or to chronic activation of the pathway by epigenetic mechanisms. Constitutive activation of the Rel/NF-kappa B pathway can contribute to the oncogenic state in several ways, for example, by driving proliferation, by enhancing cell survival, or by promoting angiogenesis or metastasis. In many cases, inhibition of Rel/NF-kappa B activity reverses all or part of the malignant state. Thus, the Rel/NF-kappa B pathway has received much attention as a focal point for clinical intervention.
Assuntos
Proteínas I-kappa B/metabolismo , NF-kappa B/metabolismo , Neoplasias/metabolismo , Proteínas Oncogênicas v-rel/metabolismo , Antineoplásicos/farmacologia , Aberrações Cromossômicas , Humanos , Proteínas I-kappa B/antagonistas & inibidores , Proteínas I-kappa B/genética , NF-kappa B/genética , Proteínas Oncogênicas v-rel/antagonistas & inibidores , Proteínas Oncogênicas v-rel/fisiologia , Transdução de SinaisRESUMO
The levels of tumour necrosis factor receptor (TNF-R) superfamily members can be altered in lymphoid leukemias, indicating a possible role of such molecules in the biology of these neoplasias. In B chronic lymphocytic leukemia cells, the CD40/CD40L system has been shown to be effective in inhibiting the apoptotic response to fludarabine. The modulation of apoptosis relied on the CD40-induced activity of NF-kappaB/Rel transcription factors. The anti-apoptotic effect of CD40 was abolished using a phosphorothioate kappaB decoy oligodeoxynucleotide. These findings illustrate an example of the biological activity of TNF-R-like molecules in leukemias. They also show the influence of NF-kappaB/Rel activity on leukemic cell response to apoptogenic agents.