Resveratrol decreases the levels of miR-155 by upregulating miR-663, a microRNA targeting JunB and JunD

MiR-663, a microRNA targeting p21(WAF1/CIP1), promotes the proliferation and tumorigenesis of nasopharyngeal carcinoma

MicroRNAs (miRNAs) may function as either oncogenes or tumor suppressors in the malignant progression of different tumor types. MiR-663 was recently reported to be decreased and identified as a tumor suppressor in gastric cancer. We also verified its role in repressing cell proliferation of a gastric cancer cell line. In this study, however, miR-663 was found to be upregulated in nasopharyngeal carcinoma (NPC) cells compared with human immortalized nasopharyngeal epithelium cells, using a miRNA microarray, and this higher expression was confirmed in NPC tissue samples. Indeed, inhibition of miR-663 impaired the proliferation of NPC cells in vitro and the NPC tumor growth of xenografts in nude mice. Mechanistically, miR-663 directly targeted p21(WAF1/CIP1) to promote the cellular G1/S transition, as the inhibitory effects of miR-663 on the G1/S transition could be rescued by p21(WAF1/CIP1) silencing. Our results imply that miR-663 may act as an oncogene in NPC. The newly identified miR-663/p21(WAF1/CIP1) axis clarifies the molecular mechanism of NPC cell proliferation and represents a novel strategy for the diagnosis and treatment of patients with NPC.

PDCD4 expression inversely correlated with miR-21 levels in gastric cancers

PURPOSE

The specific aim of this study was to investigate whether the PDCD4 gene is involved in the development and progression of gastric cancer.

METHODS

We examined the genetic and epigenetic alterations of the PDCD4 gene as well as the expression of PDCD4 protein in gastric cancers. The mRNA expression of PDCD4 and miRNA-21 expression were also analyzed using quantitative real-time RT-PCR.

RESULTS

Loss or reduced PDCD4 expression was observed in 79 (36.7%) of 215 gastric cancer specimens. Statistically, altered PDCD4 expression was not associated with the clinicopathological parameters, including tumor differentiation, location, lymph node metastasis and overall survival (P > 0.05). miRNA-21 overexpression was frequently detected in gastric cancers (31 of 46, 67.4%), and there was a significant inverse correlation between miRNA-21 and PDCD4 protein expression (P = 0.029), but not between miRNA-21 and PDCD4 mRNA expression. In genetic analysis, no mutation was detected in the coding region of the PDCD4 gene, and promoter hypermethylation was found in 24 (36.4%) of the 66 gastric cancer samples.

CONCLUSIONS

Our data suggest that overexpression of miRNA-21 and reduced or loss of PDCD4 expression may play a role in the development and progression of gastric cancers.

MicroRNA, nutrition, and cancer prevention

MicroRNA (miRNA) are small noncoding RNA molecules that are involved in post-transcriptional gene silencing. Alterations in miRNA expression are observed in and may underlie many different human diseases, including cancer. In fact, miRNA have been shown to affect the hallmarks of cancer, including sustaining proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis. Genetic and epigenetic alterations may explain aberrant miRNA expression in cancer cells and may also contribute to cancer risk. It is now thought that by circulating through the bloodstream, miRNA can exert their effects at distant sites as well as within the cells of origin. Recent evidence suggests that nutrients and other bioactive food components protect against cancer through modulation of miRNA expression. Moreover, dietary factors have been shown to modify miRNA expression and their mRNA targets in various cancer processes, including apoptosis, cell cycle regulation, differentiation, inflammation, angiogenesis, and metastasis as well as pathways in stress response. Herein, we provide a brief overview of dietary modulation of miRNA expression and its potential role in cancer prevention. Understanding the affect of dietary factors on miRNA expression and function may provide insight on prevention strategies to reduce the burden of cancer.

Cholinesterase-Targeting microRNAs Identified in silico Affect Specific Biological Processes

MicroRNAs (miRs) have emerged as important gene silencers affecting many target mRNAs. Here, we report the identification of 244 miRs that target the 3′-untranslated regions of different cholinesterase transcripts: 116 for butyrylcholinesterase (BChE), 47 for the synaptic acetylcholinesterase (AChE-S) splice variant, and 81 for the normally rare splice variant AChE-R. Of these, 11 and 6 miRs target both AChE-S and AChE-R, and AChE-R and BChE transcripts, respectively. BChE and AChE-S showed no overlapping miRs, attesting to their distinct modes of miR regulation. Generally, miRs can suppress a number of targets; thereby controlling an entire battery of functions. To evaluate the importance of the cholinesterase-targeted miRs in other specific biological processes we searched for their other experimentally validated target transcripts and analyzed the gene ontology enriched biological processes these transcripts are involved in. Interestingly, a number of the resulting categories are also related to cholinesterases. They include, for BChE, response to glucocorticoid stimulus, and for AChE, response to wounding and two child terms of neuron development: regulation of axonogenesis and regulation of dendrite morphogenesis. Importantly, all of the AChE-targeting miRs found to be related to these selected processes were directed against the normally rare AChE-R splice variant, with three of them, including the neurogenesis regulator miR-132, also directed against AChE-S. Our findings point at the AChE-R splice variant as particularly susceptible to miR regulation, highlight those biological functions of cholinesterases that are likely to be subject to miR post-transcriptional control, demonstrate the selectivity of miRs in regulating specific biological processes, and open new venues for targeted interference with these specific processes.

Resveratrol, MicroRNAs, Inflammation, and Cancer

MicroRNAs are short noncoding RNAs that regulate the expression of many target genes posttranscriptionally and are thus implicated in a wide array of cellular and developmental processes. The expression of miR-155 or miR-21 is upregulated during the course of the inflammatory response, but these microRNAs are also considered oncogenes due to their upregulation of expression in several types of tumors. Furthermore, it is now well established that inflammation is associated with the induction or the aggravation of nearly 25% of cancers. Therefore, the above microRNAs are thought to link inflammation and cancer. Recently, resveratrol (trans-3,4′,5-trihydroxystilbene), a natural polyphenol with antioxidant, anti-inflammatory, and anticancer properties, currently at the stage of preclinical studies for human cancer prevention, has been shown to induce the expression of miR-663, a tumor-suppressor and anti-inflammatory microRNA, while downregulating miR-155 and miR-21. In this paper we will discuss how the use of resveratrol in therapeutics may benefit from the preanalyses on the status of expression of miR-155 or miR-21 as well as of TGFβ1. In addition, we will discuss how resveratrol activity might possibly be enhanced by simultaneously manipulating the levels of its key target microRNAs, such as miR-663.

Comparative effects of retinoic acid, vitamin D and resveratrol alone and in combination with adenosine analogues on methylation and expression of phosphatase and tensin homologue tumour suppressor gene in breast cancer cells

Aberrations in DNA methylation patterns have been reported to be involved in driving changes in the expression of numerous genes during carcinogenesis and have become promising targets for chemopreventive action of natural compounds. In the present study, we investigated the effects of all-trans retinoic acid (ATRA), vitamin D₃ and resveratrol alone and in combination with adenosine analogues, 2-chloro-2'-deoxyadenosine (2CdA) and 9-β-d-arabinosyl-2-fluoroadenine (F-ara-A), on the methylation and expression of phosphatase and tensin homologue (PTEN) tumour suppressor gene in MCF-7 and MDA-MB-231 breast cancer cells. The present results showed that in non-invasive MCF-7 cells, ATRA, vitamin D₃ and resveratrol possess high efficacy in the reduction of PTEN promoter methylation. It was associated with PTEN induction as well as DNA methyltransferase down-regulation and p21 up-regulation after treatments with vitamin D₃ and resveratrol, suggesting a complex regulation of the DNA methylation machinery. Vitamin D₃ and resveratrol improved the inhibitory effects of 2CdA and F-ara-A on PTEN methylation in MCF-7 cells; however, only the combined action of vitamin D₃ and 2CdA boosted the induction of PTEN expression, suggesting a cooperation of these compounds in additional processes driving changes in PTEN expression. In contrast, in highly invasive MDA-MB-231 cells, only vitamin D₃ reduced PTEN methylation and induced its expression without notable effects in combined treatments. The present results suggest that natural compounds can find application in epigenetic anticancer therapy aimed at inhibition of promoter methylation of tumour suppressor genes and induction of their expression at early stages of carcinogenesis.

MicroRNAs, diet, and cancer: new mechanistic insights on the epigenetic actions of phytochemicals

There is growing interest in the epigenetic mechanisms that impact human health and disease, including the role of microRNAs (miRNAs). These small (18-25 nucleotide), evolutionarily conserved, non-coding RNA molecules regulate gene expression in a post-transcriptional manner. Several well-orchestered regulatory mechanisms involving miRNAs have been identified, with the potential to target multiple signaling pathways dysregulated in cancer. Since the initial discovery of miRNAs, there has been progress towards therapeutic applications, and several natural and synthetic chemopreventive agents also have been evaluated as modulators of miRNA expression in different cancer types. This review summarizes the most up-to-date information related to miRNA biogenesis, and critically evaluates proposed miRNA regulatory mechanisms in relation to cancer signaling pathways, as well as other epigenetic modifications (DNA methylation patterns, histone marks) and their involvement in drug resistance. We also discuss the mechanisms by which dietary factors regulate miRNA expression, in the context of chemoprevention versus therapy.

Pro-apoptotic versus anti-apoptotic properties of dietary resveratrol on tumoral and normal cardiac cells

Resveratrol is a natural dietary polyphenol found in grape skin, red wine, and various other food products. Resveratrol has proved to be an effective chemopreventive agent for different malignant tumors. It has also been shown to prevent vascular alterations such as atherosclerosis and inflammatory-associated events. In view of these observations, we investigated the anti-proliferative and pro-apoptotic activities of resveratrol on a tumoral cardiac cell line (HL-1 NB) derived from mouse tumoral atrial cardiac myocytes. These effects were compared with those found on normal neonatal mouse cardiomyocytes. HL-1 NB cells and neonatal cardiomyocytes were treated with resveratrol (5, 30, and/or 100 μM) for different times of culture (24, 48, and/or 72 h). Resveratrol effects were determined by various microscopical and flow cytometric methods. After resveratrol treatment, a strong inhibition of tumoral cardiac HL1-NB cell growth associated with a loss of cell adhesion was observed. This cell proliferation arrest was associated with an apoptotic process revealed by an increased percentage of cells with fragmented and/or condensed nuclei (characteristic of apoptotic cells) identified after staining with Hoechst 33342 and by the presence of cells in subG1. At the opposite, on normal cardiomyocytes, no cytotoxic effects of resveratrol were observed, and a protective effect of resveratrol against norepinephrine-induced apoptosis was found on normal cardiomyocytes. Altogether, the present data demonstrate that resveratrol (1) induces apoptosis of tumoral cardiac HL1-NB cells, (2) does not induce cell death on normal cardiomyocytes, and (3) prevents norepinephrine-induced apoptosis on normal cardiomyocytes.

Epigenetic changes induced by curcumin and other natural compounds

Epigenetic regulation, which includes changes in DNA methylation, histone modifications, and alteration in microRNA (miRNA) expression without any change in the DNA sequence, constitutes an important mechanism by which dietary components can selectively activate or inactivate gene expression. Curcumin (diferuloylmethane), a component of the golden spice Curcuma longa, commonly known as turmeric, has recently been determined to induce epigenetic changes. This review summarizes current knowledge about the effect of curcumin on the regulation of histone deacetylases, histone acetyltransferases, DNA methyltransferase I, and miRNAs. How these changes lead to modulation of gene expression is also discussed. We also discuss other nutraceuticals which exhibit similar properties. The development of curcumin for clinical use as a regulator of epigenetic changes, however, needs further investigation to determine novel and effective chemopreventive strategies, either alone or in combination with other anticancer agents, for improving cancer treatment.

MicroRNA Dysregulation in Colon Cancer Microenvironment Interactions: The Importance of Small Things in Metastases

The influence of the microenvironment through the various steps of cancer progression is signed by different cytokines and growth factors, that could directly affect cell proliferation and survival, either in cancer and stromal cells. In colon cancer progression, the cooperation between hypoxia, IL-6 and VEGF-A165 could regulate the DNA repair capacity of the cell, whose impairment is the first step of colon cancer development. This cooperation redirects the activity of proteins involved in the metabolic shift and cell death, affecting the cell fate. The pathways triggered by micro environmental factors could modulate cancer-related gene transcription, affecting also small non coding mRNA, microRNAs. MicroRNAs have emerged as key post-transcriptional regulators of gene expression, directly involved in human cancers. The present review will focus first on the intertwined connection between cancer microenvironment and aberrant expression of microRNAs which contribute to carcinogenesis. In particular, the epigenetic mechanisms triggered by tissue microenvironment will be discussed, in view of the recent identification of miRNAs able to directly or indirectly modulate the epigenetic machinery (epi-miRNAs) and that are involved in the epithelial to mesenchimal transition and metastases development.

Modulation of MicroRNAs by Chemical Carcinogens and Anticancer Drugs in Human Cancer: Potential Inkling to Therapeutic Advantage

The disorder of microRNAs (miRNAs) often referred as 'micromanagers of gene expression' has been implicated with a vast array of neoplasmthe discovery establishes an important connection with the etiology, diagnosis and potential therapy of human cancer. Indeed, the wide range of profiling studies enabled to create miRNA signatures of solid tumors as well as cancers of blood origin. MiRNAs have been observed to play a significant role in the regulation of gene expression-a critical aspect of many biological processes, including cell development, differentiation, apoptosis and proliferation. The differential expression levels of miRNAs in tumors and their normal counterpart have enabled scientists to designate their roles as oncomir or tumor suppressor. Interestingly, the diminishment of oncogenic or enhanced levels of tumor suppressor miRNAs (antagomirs) have been reported to modulate the sensitivity of cancer cells to anticancer agents. To the other end, carcinogenic chemicals either possess the ability of silencing beneficial tumor suppressive miRNAs or maintain the augmented levels of their oncogenic counterpart. In this article we provide a comprehensive overview on the modulation of these "micromanaging oligos" by cancer causing as well as cancer preventing agents.

Restoration of altered microRNA expression in the ischemic heart with resveratrol

BACKGROUND

Resveratrol, a constituent of red wine, is important for cardioprotection. MicroRNAs are known regulators for genes involved in resveratrol-mediated cardiac remodeling and the regulatory pathway involving microRNA has not been studied so far.

METHODS

We explored the cardioprotection by resveratrol in ischemia/reperfusion model of rat and determined cardiac functions. miRNA profile was determined from isolated RNA using quantitative Real-time PCR based array. Systemic analyses of miRNA array and theirs targets were determined using a number of computational approaches.

RESULTS

Cardioprotection by resveratrol and its derivative in ischemia/reperfusion [I/R] rat model was examined with miRNA expression profile. Unique expression pattern were found for each sample, particularly with resveratrol [pure compound] and longevinex [commercial resveratrol formulation] pretreated hearts. Longevinex and resveratrol pretreatment modulates the expression pattern of miRNAs close to the control level based on PCA analyses. Differential expression was observed in over 25 miRNAs, some of them, such as miR-21 were previously implicated in cardiac remodeling. The target genes for the differentially expressed miRNA include genes of various molecular function such as metal ion binding, sodium-potassium ion, transcription factors, which may play key role in reducing I/R injury.

CONCLUSION

Rats pretreated with resveratrol for 3 weeks leads to significant cardioprotection against ischemia/reperfusion injury. A unique signature of miRNA profile is observed in control heart pretreated with resveratrol or longevinex. We have determined specific group of miRNA in heart that have altered during IR injuries. Most of those altered microRNA expressions modulated close to their basal level in resveratrol or longevinex treated I/R mice.

Potential of the dietary antioxidants resveratrol and curcumin in prevention and treatment of hematologic malignancies

Despite considerable improvements in the tolerance and efficacy of novel chemotherapeutic agents, the mortality of hematological malignancies is still high due to therapy relapse, which is associated with bad prognosis. Dietary polyphenolic compounds are of growing interest as an alternative approach, especially in cancer treatment, as they have been proven to be safe and display strong antioxidant properties. Here, we provide evidence that both resveratrol and curcumin possess huge potential for application as both chemopreventive agents and anticancer drugs and might represent promising candidates for future treatment of leukemia. Both polyphenols are currently being tested in clinical trials. We describe the underlying mechanisms, but also focus on possible limitations and how they might be overcome in future clinical use – either by chemically synthesized derivatives or special formulations that improve bioavailability and pharmacokinetics.