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MicroRNAs (miRNAs) regulate gene expression through degradation and/or translational repression of target mRNAs. Dysregulations in the miRNA machinery may be involved in carcinogenesis of colorectal cancer (CRC). The purpose of the current study was to evaluate the DiGeorge syndrome critical region gene 8 (DGCR8) and argonaute 2 (AGO2) mRNA expression in CRC and to evaluate the value of clinical parameters on their expression. We investigated the mRNA expressions of DGCR8 and AGO2 in 60 CRC tissues and adjacent histologically non-neoplastic tissues by using quantitative real-time PCR. Our study revealed that the mRNA expression level of DGCR8 is up-regulated in CRC. However, AGO2 mRNA expression was not significantly altered in CRC tissues. Neither DGCR8 nor AGO2 mRNA expression level was not associated with any clinical parameters, including age, tumor stage, CEA titer, and BMI in CRC cases. However, the mRNA expression levels of DGCR8 and AGO2 were positively correlated to each other. This study demonstrated for the first time that the DGCR8 mRNA expression level was up-regulated in CRC, suggesting its important role in pathobiology of colorectal carcinogenesis. [ABSTRACT FROM AUTHOR]

Highlights: [•] Silibinin induces apoptosis in HT29 colon carcinoma cells. [•] Silibinin up-regulates NAG-1 expression. [•] p53 and ATF3 are not involved in silibinin-induced NAG-1 up-regulation. [•] Silibilin induces NAG-1 expression via up-regulation of EGR-1. [•] Suppression of NAG-1 expression attenuates silibinin-induced apoptosis. [ABSTRACT FROM AUTHOR]

Abstract: Anisomycin is known to inhibit protein synthesis and induce ribotoxic stress. In this study, we investigated whether anisomycin treatment could modulate TRAIL-mediated apoptosis in human renal carcinoma Caki cells. We found that anisomycin treatment (10–15 nM) alone had no effect on the level of apoptosis, but a combination treatment of anisomycin and TRAIL significantly increased the level of apoptosis in human renal carcinoma (Caki, ACHN and A498), human glioma (U251MG), and human breast carcinoma (MDA-MB-361 and MCF7) cells. Anisomycin treatment led to the down-regulation of Bcl-2 expression at the transcriptional level, and the over-expression of Bcl-2 inhibited the apoptosis induced by the combination treatment of anisomycin and TRAIL. Furthermore, anisomycin treatment resulted in the down-regulation of c-FLIP(L) and Mcl-1 at the post-transcriptional level, and the over-expression of c-FLIP(L) and Mcl-1 blocked the induction of apoptosis caused by the combination treatment of anisomycin with TRAIL. In contrast, anisomycin treatment had no effect on the levels of TRAIL-mediated apoptosis in mouse kidney cells (TMCK-1) or normal human skin fibroblasts (HSF). Cumulatively, our study demonstrates that anisomycin treatment enhances TRAIL-mediated apoptosis through the down-regulation of Bcl-2, c-FLIP(L) and Mcl-1 at the transcriptional or post-transcriptional level. [Copyright &y& Elsevier]

Lipocalin-2 (LCN2) is a member of the lipocalin superfamily and plays a critical role in the regulation of various physiological processes, such as inflammation and obesity. In this study, we report that LCN2 negatively modulates the proliferation and differentiation of osteoclast precursors, resulting in impaired osteoclast formation. The overexpression of LCN2 in bone marrow-derived macrophages or the addition of recombinant LCN2 protein inhibits the formation of multinuclear osteoclasts. LCN2 suppresses macrophage colony-stimulating factor (M-CSF)-induced proliferation of osteoclast precursor cells without affecting their apoptotic cell death. Interestingly, LCN2 decreases the expression of the M-CSF receptor, c-Fms, and subsequently blocks its downstream signaling cascades. In addition, LCN2 inhibits RANKL-induced osteoclast differentiation and attenuates the expression of c-Fos and nuclear factor of activated T cells c1 (NFATc1), which are important modulators in osteoclastogenesis. Mechanistically, LCN2 inhibits NF-κB signaling pathways, as demonstrated by the suppression of IκBα phosphorylation, nuclear translocation of p65, and NF-κB transcriptional activity. Thus, LCN2 is an anti-osteoclastogenic molecule that exerts its effects by retarding the proliferation and differentiation of osteoclast lineage cells. [ABSTRACT FROM AUTHOR]

Abstract: Dysregulation of transforming growth factor-β (TGF-β) signaling has been implicated in the pathogenesis of a variety of diseases including cancer; therefore, pharmacological inhibitors that target the TGF-β signaling pathway might be promising drugs for disease therapy. In this study, we investigated the mechanism of inhibition of TGF-β signaling by the Hsp90 inhibitor geldanamycin (GA). Treatment with GA suppressed TGF-β signaling, as evidenced by inhibition of TGF-β-induced phosphorylation and transcriptional activity of Smad3 and decreased induction of target genes. Western blot analysis revealed that GA induced degradation of TGF-β type I and type II receptors through a proteasome-dependent pathway. Notably, induction of Hsp70 by GA correlated with inhibition of TGF-β signaling. Suppression of Hsp70 expression by Hsp70 siRNA or KNK437, an inhibitor of Hsp70 synthesis, blocked the inhibition of TGF-β signaling by GA. Furthermore, Hsp70 interacted directly with TGF-β receptors following GA treatment. Our results suggest that GA-mediated induction of Hsp70 and its subsequent interaction with TGF-β receptors plays a crucial role in inhibition of TGF-β signaling. [Copyright &y& Elsevier]

Summary: GATA factors establish transcriptional networks that control fundamental developmental processes. Whereas the regulator of hematopoiesis GATA-1 is subject to multiple posttranslational modifications, how these modifications influence GATA-1 function at endogenous loci is unknown. We demonstrate that sumoylation of GATA-1 K137 promotes transcriptional activation only at target genes requiring the coregulator Friend of GATA-1 (FOG-1). A mutation of GATA-1 V205G that disrupts FOG-1 binding and K137 mutations yielded similar phenotypes, although sumoylation was FOG-1 independent, and FOG-1 binding did not require sumoylation. Both mutations dysregulated GATA-1 chromatin occupancy at select sites, FOG-1-dependent gene expression, and were rescued by tethering SUMO-1. While FOG-1- and SUMO-1-dependent genes migrated away from the nuclear periphery upon erythroid maturation, FOG-1- and SUMO-1-independent genes persisted at the periphery. These results illustrate a mechanism that controls trans-acting factor function in a locus-specific manner, and differentially regulated members of the target gene ensemble reside in distinct subnuclear compartments. [Copyright &y& Elsevier]

Abstract: In activated macrophage, large amounts of nitric oxide (NO) are generated by inducible nitric oxide synthase (iNOS), resulting in acute or chronic inflammatory disorders. In Raw 264.7 cells stimulated with lipopolysaccharide (LPS) to mimic inflammation, 8-hydroxyquinoline (8HQ) inhibited the LPS-induced expression of both iNOS protein and mRNA in a parallel dose-dependent manner. 8HQ did not enhance the degradation of iNOS mRNA. To investigate the mechanism by which 8HQ inhibits iNOS gene expression, we examined the activation of MAP kinases in Raw 264.7 cells. We did not observe any significant change in the phosphorylation of MAPKs between LPS alone and LPS plus 8HQ-treated cells. Moreover, 8HQ significantly inhibited the DNA-binding activity of nuclear factor-κB (NF-κB) and CCAAT/enhancer-binding protein β (C/EBPβ), but not activator protein-1 and cAMP response element-binding protein. Taken together, these results suggest that 8HQ acts to inhibit inflammation through inhibition of NO production and iNOS expression through blockade of C/EBPβ DNA-binding activity and NF-κB activation. [Copyright &y& Elsevier]