Forkhead Box M1 positively regulates UBE2C and protects glioma cells from autophagic death

<p>Ubiquitin-conjugating enzyme E2C (UBE2C) is characterized as a crucial molecule in cancer cell growth that plays an essential role in the development of gliomas, but the detailed mechanisms have not been fully elucidated. In this study, we found that Forkhead box transcription factor M1 (FoxM1) overexpression increased UBE2C expression, whereas FoxM1 suppression inhibited UBE2C expression in glioma cells. In addition, high FoxM1/UBE2C expression was significantly correlated with poor prognosis in glioma. We subsequently demonstrated that UBE2C was a direct transcriptional target of FoxM1, and site-directed mutations markedly down-regulated UBE2C promoter activity. Moreover, UBE2C siRNA (si-UBE2C) significantly induced glioma cell autophagy and increased both mCherry-LC3 punctate fluorescence and LC3B-II/LC3-I expression. Notably, the si-UBE2C-induced decrease in cell viability was markedly inhibited by the autophagy inhibitor bafilomycin A1. The silencing of UBE2C resulted in a distinct inhibition of the PI3K-Akt-mTOR pathway, which functions in the negative modulation of autophagy. Collectively, our findings provide clinical and molecular evidence that FoxM1 promotes glioma progression by enhancing UBE2C transcription and that the inhibition of UBE2C partially induces autophagic glioma cell death. Thus, targeting the FoxM1-UBE2C axis has therapeutic potential in the treatment of gliomas.</p

miR-181a Regulates Inflammation Responses in Monocytes and Macrophages

<div><p>miR-181a has been presumed to target the 3′-untranslated regions (3′-UTR) of IL1a based on software predictions. miR-181a and IL1a have opposite expression levels in monocytes and macrophages in the inflammatory state. This led us to suspect that mir-181a has an important function in regulating inflammatory response by targeting IL1a. Fluorescence reporter assays showed that miR-181a effectively binds to the 3′-UTR of IL1a. The anti-inflammatory functions of miR-181a were investigated in lipopolysaccharides (LPS)-induced Raw264.7 and phorbol 12-myristate 13-acetate (PMA)/LPS-induced THP-1 cells. We found that miR-181a mimics significantly lowered IL1a expression levels in these cells and, interestingly, miR-181a inhibitors reversed this decrease. In addition, miR-181a mimics significantly inhibited increase in the levels of inflammatory factors (IL1b, IL6, and TNFa) in these cells. Furthermore, miR-181a mimics and inhibitors decreased and increased, respectively, production of reactive oxygen species in PMA/LPS-induced THP-1 cells. These results indicate that miR-181a regulates inflammatory responses by directly targeting the 3′-UTR of IL1a and down-regulating IL1a levels. Interestingly, we found that miR-181a inhibited production of inflammatory factors even in IL1a-induced THP-1 cells, suggesting that the anti-inflammatory effects of miR-181a possibly involves other targets in addition to IL1a. Thus, we provide the first evidence for anti-inflammatory effects of miR-181a mediated at least in part by down-regulating IL1a.</p> </div

Effects of miR-181a mimics and inhibitors on the levels of IL1a, IL1b, IL6, and TNFa in IL1a-induced THP-1 cell lysis solution (A) and culture medium (B).

<p>Data are expressed as mean ± SD (n = 3), *<i>P</i><0.05, **<i>P</i><0.01 vs. negative control (NC), ^#<i>P</i><0.05 vs. miRNA inhibitor negative control (NC-i). ‘NC-i’ is a single-stranded nucleic acid used as a negative control for miR-181a inhibitors (181a–i). IL1a + and IL1a- indicate that the cells were treated with (at a final concentration of 0.1 ng/ml) and without exogenous IL1a, respectively.</p

Potential effects and mechanisms of the regulation of inflammation by miR-181a.

<p>Potential effects and mechanisms of the regulation of inflammation by miR-181a.</p

Effects of miR-181a mimics and inhibitors on the productions of reactive oxygen species (ROS) in PMA/LPS-induced TPH-1 cells.

<p>Data are expressed as mean ± SD (n = 3), **<i>P</i><0.01 vs. negative control (NC), ^##<i>P</i><0.01 vs. miRNA inhibitor negative control (NC-i). ‘NC-i’ is a single-stranded nucleic acid used as negative control for miR-181a inhibitors (181a–i). LPS+ and LPS− indicate cells treated with and without PMA/LPS, respectively.</p

(A and B) Effects of transient transfection with miR-181a expression vector on the levels of ILa, IL1b, IL6, and TNFa in PMA/LPS-induced THP-1 cell lysis solution and culture media.

<p>Data are expressed as mean ± SD (n = 3), *<i>P</i><0.05, **<i>P</i><0.01 vs. CMV controls. ‘SC’, pCMV-pre-miR-181a recombinant THP-1 cells; ‘CMV’, pCMV recombinant THP-1 cells (negative controls). (C and D) Effects of si-IL1a on the mRNA levels of IL1a and IL1b in LPS-induced Raw264.7 and PMA/LPS-induced THP-1 cells. (E and F) Effects of si-IL1a on the levels of IL1a, IL1b, IL6, and TNFa in LPS-induced Raw264.7 and PMA/LPS-induced THP-1 cells. Data are expressed as mean ± SD (n = 3), *<i>P</i><0.05, **<i>P</i><0.01 vs. negative control (NC). ‘siNC’ is a single-stranded nucleic acid used as negative control for siIL1a.</p

Primers of mouse IL1a 3′-UTR and its mutated fragments.

<p>Primers of mouse IL1a 3′-UTR and its mutated fragments.</p

Effects of stable expression of miR-181a on production of inflammatory factors in LPS-induced Raw264.7 cells.

<p>(A) pCMV recombinant Raw264.7 cells (CMV, negative controls); (B) pCMV-pre-miR-181a recombinant Raw264.7 cells (SC); (C) endogenous miR-181a expression in SC (containing miR-181a expression vector) and CMV (containing negative control vector) cells; (D) Expression of IL1a in pCMV and pCMV-pre-miR-181a recombinant Raw264.7 cells assayed by Western blotting; (E and F) Levels of IL1a, IL1b, IL6, and TNFa in cell lysis solution and culture media of recombinant Raw264.7 cells transfected with pCMV and pCMV-pre-miR-181a. Data are expressed as mean ± SD (n = 3), *<i>P</i><0.05, **<i>P</i><0.01 vs. pCMV recombinant controls induced by LPS (CMV LPS+), ^##<i>P</i><0.01 vs. miRNA inhibitor negative control (NC-i). LPS+ and LPS− indicate that cells were treated with and without LPS, respectively.</p

Presumed binding sites for miR-181a in the 3′-UTR of mouse and human IL1a.

<p>The binding sites are highly conserved.</p