• Asian Pacific Journal of Cancer Prevention
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• v.16 no.6
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• pp.2397-2402
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• 2015

Previous studies have shown that miR-454 plays an important role in a variety of biological processes in various human cancer cells. However, the underlying mechanisms of this microRNA in colorectal cancer (CRC) cells remain largely unknown. In the present study, we investigated the miR-454 role in CRC cell proliferation. We found that miR-454 expression is markedly upregulated in CRC tissues and CRC cells compared with the matched tumor adjacent tissues and the FHC normal colonic cell line. Ectopic expression of miR-454 promoted the proliferation and anchorage-independent growth of CRC cells, whereas inhibition of miR-454 reduced this effect. Bioinformatics analysis further revealed cylindromatosis (CYLD), a putative tumor suppressor as a potential target of miR-454. Data from luciferase reporter assays showed that miR-454 directly binds to the 3'-untranslated region (3'-UTR) of CYLD mRNA and repressed expression at both transcriptional and translational levels. In functional assays, CYLD-silenced in miR-454-in-transfected SW480 cells have positive effect to promote cell proliferation, suggesting that direct CYLD downregulation is required for miR-454-induced CRC cell proliferation. In sum, our data provide compelling evidence that miR-454 functions as an onco-miRNA, playing a crucial role in the promoting cell proliferation in CRC, and its oncogenic effect is mediated chiefly through direct suppression of CYLD expression.

• BMB Reports
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• v.51 no.11
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• pp.602-607
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• 2018

Aberrant expression of microRNAs (miRNAs) plays important roles in carcinogenesis and tumor progression. However, the expression and biological role of miR-301b in triple-negative breast cancer (TNBC) remains unclear. Here we aimed to evaluate the roles and mechanisms of miR-301b in TNBC cells. miR-301b expression was assessed in TNBC specimens and cell lines by quantitative Real-Time PCR (qRT-PCR). TNBC cells were transfected with miR-301b mimics, inhibitors or Cylindromatosis (CYLD) small interfering RNA (siRNA) using Lipofectamine 2000. The functional roles of miR-301b were determined by cell proliferation, colony formation, and apoptosis assays. Western blots and qRT-PCR were used to measure the expression of mRNAs and proteins in the cells. We found that miR-301b was upregulated in TNBC specimens and cell lines. Overexpression of miR-301b promoted cell proliferation in TNBC cells, while inhibited the apoptosis induced by 5-FU. CYLD was downregulated by miR-301b at both mRNA and protein levels in TNBC cells. Dual-luciferase report assay confirmed that miR-301b downregulated CYLD by direct interaction with the 3'-untranslated region(3'-UTR) of CYLD mRNA. $NF-{\kappa}B$ activation was mechanistically associated with miR-301b-mediated downregulation of CYLD. However, inhibition of miR-301b reversed all the effects of miR-301b. In conclusion, miR-301b plays an oncogenic role in TNBC possibly by downregulating CYLD and subsequently activating $NF-{\kappa}B$ p65, and this may provide a novel therapeutic approach for TNBC.

• Journal of Life Science
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• v.32 no.6
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• pp.476-481
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• 2022

Ubiquitin signaling regulates virtually all aspects of eukaryotic biology and dynamic processes in which protein substrates are modified by ubiquitin. To regulate these processes, deubiquitinating enzymes (DUBs) cleave ubiquitin or ubiquitin-like proteins from these substrates. DUBs have been implicated in the pathogenesis of cancer, leading to the development of increasing numbers of small-molecule DUB inhibitors. On the other hand, recent studies have focused on the function of DUBs in metabolic diseases such as obesity, diabetes, and fatty liver diseases. DUBs play a positive or negative role in the progression and development of metabolic diseases. Their involvement in cell pathology and regulation of major transcription factors in metabolic syndrome has been examined in vitro and in animal and human biopsies. UCH, USP7, and USP19 were linked to adipocyte differentiation, body weight gain, and insulin resistance in genetic or diet-induced obesity. CYLD, USP4, and USP18 were found to be closely associated with fatty liver diseases. In addition, these liver diseases were accompanied by body weight change in certain cases. Collectively, in this review, we discuss the current understanding of DUBs in metabolic diseases with a particular focus on obesity. We also provide basic knowledge and regulatory mechanisms of DUBs and suggest these enzymes as therapeutic targets for metabolic diseases.

• BMB Reports
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• v.40 no.3
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• pp.341-348
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• 2007

Herpesvirus saimiri (HVS), a member of the $\delta$-herpesvirus family, encodes an oncoprotein called Saimiri Transforming Protein (STP) which is required for lymphoma induction in non-human primates. Previous study has shown that STP-C, an oncoprotein of HVS, activates NF-$\kappa$B signaling pathway. However, the detailed mechanism of STP-Cmediated NF-$\kappa$B activation has not been reported yet. We first report that STP-C interacts with TRAF6 protein in vivo and in vitro and further investigation shows that $Glu_{12}$ residue of STP-C is critical for binding to TRAF6. Introduction of ubiquitin together with STP-C augments NF-$\kappa$B activity compared to that of STP-C expression alone. STP-C expression further induces ubiquitination of endogenous TRAF6. In addition, either a deubiquitination enzyme, CYLD or a dominant negative E2-conjugation enzyme reduced NF-$\kappa$B activity in spite of the presence of STP-C, supporting that the interaction between STP-C and TRAF6 induces ubiquitination of TRAF6. NF-$\kappa$B activation by STP-C through the ubiquitinated TRAF6 causes the increased production of IL-8, an inflammatory chemokine and the enhanced expression of costimulatory molecule ICAM, which might ultimately contribute cellular transformation by the exposure of HVS-infected cells with inflammatory microenvironment and chronic activation.