Pterostilbene Acts through Metastasis-Associated Protein 1 to Inhibit Tumor Growth, Progression and Metastasis in Prostate Cancer

<div><p>The development of natural product agents with targeted strategies holds promise for enhanced anticancer therapy with reduced drug-associated side effects. Resveratrol found in red wine, has anticancer activity in various tumor types. We reported earlier on a new molecular target of resveratrol, the metastasis-associated protein 1 (MTA1), which is a part of nucleosome remodeling and deacetylation (NuRD) co-repressor complex that mediates gene silencing. We identified resveratrol as a regulator of MTA1/NuRD complex and re-activator of p53 acetylation in prostate cancer (PCa). In the current study, we addressed whether resveratrol analogues also possess the ability to inhibit MTA1 and to reverse p53 deacetylation. We demonstrated that pterostilbene (PTER), found in blueberries, had greater increase in MTA1-mediated p53 acetylation, confirming superior potency over resveratrol as dietary epigenetic agent. In orthotopic PCa xenografts, resveratrol and PTER significantly inhibited tumor growth, progression, local invasion and spontaneous metastasis. Furthermore, MTA1-knockdown sensitized cells to these agents resulting in additional reduction of tumor progression and metastasis. The reduction was dependent on MTA1 signaling showing increased p53 acetylation, higher apoptotic index and less angiogenesis <i>in vivo</i> in all xenografts treated with the compounds, and particularly with PTER. Altogether, our results indicate MTA1 as a major contributor in prostate tumor malignant progression, and support the use of strategies targeting MTA1. Our strong pre-clinical data indicate PTER as a potent, selective and pharmacologically safe natural product that may be tested in advanced PCa.</p> </div

Effects of resveratrol and pterostilbene on spontaneous metastasis: involvement of MTA1.

<p>A. BL images of metastasis are shown. Signals detected after prostate removal consisted of metastatic and non-specific signals. Removal of skin and muscles eliminated non-specificity. B. <i>Top, ex vivo</i> images of metastatic organs. <i>Bottom,</i> Validation of metastatic lesions (T) in kidneys (K), liver (Li) and lung/heart (L/H) by H&E staining. C, quantitative analysis of total metastatic Luc signals in Total Flux (photons/sec/cm2/sr). Open circles represent outliers. *p<0.05; **p<0.01; ***p<0.001 are pairwise comparisons vs. EV-Ctrl. D, quantitative analysis of organ-specific metastasis calculated by luciferase signals as Total Flux (photons/sec/cm²/sr). Color-coded histograms of signals for each group are shown. PTER was more effective in inhibiting metastasis in all organs compared to Res in EV-group. In MTA1-knockdown group, Res exhibited more effects by eliminating kidney metastasis.</p

MTA1-mediated therapeutic activity of resveratrol and pterostilbene in orthotopic PCa xenografts.

<p>Male nude mice were injected orthotopically with Du145-EV-Luc (EV) or Du145-MTA1shRNA-Luc (MTA1shRNA) cells and treated with vehicle (Ctrl), Res or PTER, 50 mg/kg/day, every day, i.p. A. Normalized representative BL images of mice from each group are shown. B, <i>left</i>, Quantitative analysis of tumor light emission in Total Flux (photons/sec/cm2/sr) is plotted against time. The means ± SE are shown (n = 6 at the start), *p = 0.05. <i>Right</i>, log trends for each group are shown. Significant growth inhibition was detected in EV- vs. MTA1shRNA-tumors as groups, **p<0.01 and between EV-Ctrl vs. MTA1shRNA-Res and MTA1shRNA-PTER, ***p<0.001.</p

Chemical structures of stilbenes.

<p>Resveratrol (Res), <i>trans</i>-3,5,4′-trihydroxystilbene; Pterostilbene (PTER), <i>trans</i>-3,5-dimethoxystilbene; Trimethoxy-Resveratrol (3M-Res), <i>trans</i>-3,5,4′-trimethoxystilbene; Piceatannol (PIC), <i>trans</i>-3,5,3′4′-tetrahydroxystilbene; Dimethoxystyrylaniline (DMSA), <i>trans</i>-4-(3,5-dimethoxystyryl)aniline; Diacetyl-Resveratrol (2Ac-Res), <i>trans</i>-3,5-diacetylstilbene; Triacetyl-Resveratrol (3Ac-Res), <i>trans</i>-3,5,4′-triacetylstilbene.</p

Pterostilbene increases MTA1-mediated p53 acetylation in Du145 cells.

<p>Du145-EV and Du145-MTA1shRNA cells (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057542#pone.0057542.s001" target="_blank">Fig. S1</a>) were treated with 50 µM of Res or PTER for 24 hr and analyzed for MTA1, p53, Ac-p53 by Western blot as described in “<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057542#s2" target="_blank">Materials and methods</a>”. A representative blot is shown. Quantitation of Ac-p53/p53 ratio was conducted by Image J software and data shown as mean±SEM from three independent experiments.</p

Enrichment for functional annotations and cell-type groups using stratified LD score regression.

<p><b>A.</b> Enrichment estimates of 24 main annotations for each of four BP traits. Annotations are ordered by size. Error bars represent jackknife standard errors around the estimates of enrichment, and stars indicate significance at P < 0.05 after Bonferroni correction for 24 hypotheses tested and four BP traits. <b>B.</b> Significance of enrichment of 10 cell-type groups for four BP traits. Dotted line and stars indicate significance at P < 0.05 after Bonferroni correction for 10 hypotheses tested and four BP traits.</p

Intelligent Forecasting of Electricity Demand

In this paper, a number of approaches to the modelling of electricity demand, on a variety of time-scales, are considered. These approaches fall under the category of 'intelligent' systems engineering, where techniques such as neural networks, fuzzy logic and genetic algorithms are employed. The paper attempts to give some motivation for the employment of such techniques, while also making some effort to be realistic about the limitations of such methods, in particular a number of important caveats that should be borne in mind when utilising these techniques within the current application domain. In general, the electricity demand data is modelled as a time series, but one application considered involves application of linguistic modelling to capture operator expertise