The myelodysplastic syndromes (MDSs) comprise a group of disorders characterized by multistage progression from cytopenias to acute myeloid leukemia (AML). They display exaggerated apoptosis in early stages, but lose this behavior during evolution to AML. The molecular basis for loss of apoptosis is unknown. To investigate this critical event, we analyzed phosphatidylinositol (PI) 3'kinase signaling, implicated as a critical pathway of cell survival control in epithelial and hematological malignancies. PI 3'kinase activates Akt through its production of 3' phosphoinositides. In turn, the phosphoinositides are dephosphorylated by two lipid phosphatases, PTEN and SHIP-1, in myeloid cells. We studied primary MDS-enriched bone marrow cells and bone marrow sections by western blotting, immunohistochemistry, immunocytochemistry and quantitative PCR for components of the SHIP/PTEN/PI 3'kinase signaling circuit. We reported constitutively activated Akt, variable levels of PTEN and uniformly decreased SHIP-1 expression in MDS progenitor cells. Overexpression of SHIP-1, but not the phosphatase-deficient form, inhibited myeloid leukemic growth. Levels of microRNA (miR)-210 and miR-155 transcripts, which target SHIP-1, were increased in CD34(+) MDS cells compared with their normal counterparts. Direct binding of miR-210 to the 3' untranslated region of SHIP-1 was confirmed by luciferase reporter assay. Transfection of a myeloid cell line with miR-210 resulted in loss of SHIP-1 protein expression. These data suggest that miR-155 and miR-210/SHIP-1/Akt pathways could serve as clinical biomarkers for disease progression, and that miR-155 and miR-210 might serve as novel therapeutic targets in MDS.
"As SHIP-1 is a target of miR-155 [17-19], we focused on the expression of SHIP-1 in gouty SFMCs. The expression of SHIP-1 mRNA was markedly down-regulated in SFMCs of gouty arthritis patients compared with that in PBMCs of gouty arthritis patients and normal controls (Figure 2A). "
[Show abstract][Hide abstract] ABSTRACT: Gout is characterized by episodes of intense joint inflammation in response to intra-articular monosodium urate monohydrate (MSU) crystals. miR-155 is crucial for the proinflammatory activation of human myeloid cells and antigen-driven inflammatory arthritis. The functional role of miR-155 in acute gouty arthritis has not been defined. Therefore, the aim of this study was to examine the role of miR-155 in pathogenesis of acute gouty arthritis.
Samples from 14 patients with acute gouty arthritis and 10 healthy controls (HCs) were obtained. Peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) were cultured in vitro with MSU crystals, and gene expression (human miR-155 and SHIP-1) were assessed by real-time PCR. THP-1 cells were stimulated by MSU crystals and/or miR-155 transfection and then subjected to Western blot analysis. Levels of human tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta in cell culture supernatants were measured by Luminex. Immunohistochemistry was performed on formalin-fixed gout tissues with anti-SHIP-1 antibody. A C57BL/6J male mouse model of gout was used to analyze the expressions of miR-155, SHIP-1, and inflammatory cytokines.
The samples from gouty arthritis were highly enriched in miR-155, with levels of expression being higher than those found in PBMC from HC. Treatment of the cells with MSU crystals strongly induced miR-155. In addition, overexpression of miR-155 in the cells decreased levels of SHIP-1 and promoted production of MSU-induced proinflammatory cytokines, such as TNF-alpha and IL-1beta. Consistent with in vitro observations, miR-155 expression was elevated in the mouse model of gout. The production of inflammatory cytokines was markedly increased in MSU crystal induced peritonitis mice.
Overexpression of miR-155 in the gouty SFMC leads to suppress SHIP-1 levels and enhance proinflammatory cytokines.
"Among the most highly expressed miRNAs, seven miRNAs were shown modified in hypoxia: miR-93, miR-205, miR-224, miR-335, miR- 424, miR-451, and miR-491. Other miRNAs induced by hypoxia were identified by targeted approaches, as they were shown to be modified in preeclamptic placentas (considered as hypoxic) or pregnancies associated with abnormal placental Doppler waveforms , indicative of a blood circulation defect; this was the case for miR-21 (Cindrova-Davies et al., 2013), miR-210 (Ishibashi et al., 2012; Lee et al., 2012; Muralimanoharan et al., 2012), and miR- 518c (Ishibashi et al., 2012). These hypoxia-induced modifications in miRNA content are probably not linked to miRNAs biogenesis , since the responsible enzymes are apparently not modified by hypoxia (Donker et al., 2007). "
[Show abstract][Hide abstract] ABSTRACT: MicroRNAs (miRNAs) have recently become essential actors in various fields of physiology and medicine, especially as easily accessible circulating biomarkers, or as modulators of cell differentiation. To this respect, terminal differentiation of trophoblasts (the characteristic cells of the placenta in Therian mammals) into syncytiotrophoblast, villous trophoblast, or extravillous trophoblast constitutes a good example of such a choice, where miRNAs have recently been shown to play an important role. The aim of this review is to provide a snapshot of what is known today in placentation mechanisms that are mediated by miRNA, under the angles of materno-fetal immune dialog regulation, trophoblast differentiation, and angiogenesis at the materno-fetal interface. Also, two aspects of regulation of these issues will be highlighted: the part played by oxygen concentration and the specific function of imprinted genes in the developing placenta.
Frontiers in Genetics 11/2013; 4:248. DOI:10.3389/fgene.2013.00248
"MicroRNAs are short, non-coding RNA that disrupt translation of mRNA targets, thereby resulting in down regulation of the mRNA corresponding encoded proteins. miR-155 has a known oncogenic activity in hematologic malignancies [27,28]. Sustained expression of this miR in hematopoietic stem cells causes a myeloproliferative disorder . "
[Show abstract][Hide abstract] ABSTRACT: Activating mutations [internal tandem duplication (ITD)] or overexpression of the FMS-like tyrosine kinase receptor-3 (FLT3) gene are associated with poor outcome in acute myeloid leukemia (AML) patients, underscoring the need for novel therapeutic approaches. The natural product silvestrol has potent antitumor activity in several malignancies, but its therapeutic impact on distinct molecular high-risk AML subsets remains to be fully investigated. We examined here the preclinical activity of silvestrol in FLT3-ITD and FLT3 wild-type (wt) AML.
Silvestrol in vitro anti-leukemic activity was examined by colorimetric cell viability assay, colony-forming and flow cytometry assays assessing growth inhibition and apoptosis, respectively. Pharmacological activity of silvestrol on FLT3 mRNA translation, mRNA and protein expression was determined by RNA-immunoprecipitation, qRT-PCR and immunoblot analyses, respectively. Silvestrol in vivo efficacy was investigated using MV4-11 leukemia-engrafted mice.
Silvestrol shows antileukemia activity at nanomolar concentrations both in FLT3-wt overexpressing (THP-1) and FLT3-ITD (MV4-11) expressing AML cell lines (IC50 = 3.8 and 2.7 nM, respectively) and patients’ primary blasts [IC50 = ~12 nM (FLT3-wt) and ~5 nM (FLT3-ITD)]. Silvestrol increased apoptosis (~4fold, P = 0.0001), and inhibited colony-formation (100%, P < 0.0001) in primary blasts. Silvestrol efficiently inhibited FLT3 translation reducing FLT3 protein expression by 80–90% and decreased miR-155 levels (~60%), a frequently co-regulated onco-miR in FLT3-ITD-positive AML. The median survival of silvestrol-treated vs vehicle-treated mice was 63 vs 29 days post-engraftment, respectively (P < 0.0001).
Silvestrol exhibits significant in vivo and in vitro antileukemic activities in AML through a novel mechanism resulting in inhibition of FLT3 and miR-155 expression. These encouraging results warrant a rapid translation of silvestrol for clinical testing in AML.
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