Loss of let-7 up-regulates EZH2 in prostate cancer consistent with the acquisition of cancer stem cell signatures that are attenuated by BR-DIM

Five microRNAs in serum as potential biomarkers for prostate cancer risk assessment and therapeutic intervention

Background

Prostate cancer (PCa) is a common malignant human tumor and one of the main causes of cancer-related deaths in men. At present, prostate-specific antigen levels are widely used to diagnose PCa in the clinic, but they are not sufficient for an accurate early diagnosis or prognosis.

Methods

To identify potential molecular markers for PCa, we used real-time PCR to measure the expression levels of various microRNAs, including miR-1825, miR-484, miR-205, miR-141, and let-7b, in the serum of 72 PCa patients and 34 healthy controls.

Results

miR-1825, miR-484, miR-205, miR-141, and let-7b were shown to be highly specific for PCa, suggesting that they could be used as PCa tumor screening biomarkers. miR-205 may also be used as a biomarker for indicating bone metastasis in PCa patients, miR-1825 levels may help indicate tumor–node–metastasis classification, the evaluation of treatment effects, and determining prognosis, while let-7b levels may indicate potential tumor malignancy and the hormone resistance status and could be used as a basis to adjust individual treatments for the high-risk, early diagnosis of refractory PCa.

Conclusion

This study identified possible PCa tumor markers to more accurately predict the occurrence, progression, and prognosis of PCa, and which could be used in the development of tumor drug therapy.

Electronic supplementary material

The online version of this article (10.1007/s11255-018-2009-4) contains supplementary material, which is available to authorized users.

Inferring microRNA-Environmental Factor Interactions Based on Multiple Biological Information Fusion

Accumulated studies have shown that environmental factors (EFs) can regulate the expression of microRNA (miRNA) which is closely associated with several diseases. Therefore, identifying miRNA-EF associations can facilitate the study of diseases. Recently, several computational methods have been proposed to explore miRNA-EF interactions. In this paper, a novel computational method, MEI-BRWMLL, is proposed to uncover the relationship between miRNA and EF. The similarities of miRNA-miRNA are calculated by using miRNA sequence, miRNA-EF interaction, and the similarities of EF-EF are calculated based on the anatomical therapeutic chemical information, chemical structure and miRNA-EF interaction. The similarity network fusion is used to fuse the similarity between miRNA and the similarity between EF, respectively. Further, the multiple-label learning and bi-random walk are employed to identify the association between miRNA and EF. The experimental results show that our method outperforms the state-of-the-art algorithms.

Let-7b attenuates cisplatin resistance and tumor growth in gastric cancer by targeting AURKB

Platinum-based chemotherapy is currently a standard treatment strategy for patients with gastric cancer. Eventhough it has been widely shown that microRNAs (miRNAs) are involved in tumor development, whether miRNAs have a role in chemosensitivity of gastric cancer cells to platinum-based treatment remain largely undefined. In this study, a cisplatin-resistant gastric cancer cell line (SGC7901/DDP) with stable enhanced expression or knockdown of let-7b was generated. MTT and TUNEL assays were carried out to assess whether miR-let-7 is crucial for cell viability and apoptosis, respectively. In vitro luciferase reporter assay was performed to explore target genes of let-7b. Further, a subcutaneously transplanted tumor model in BALB/c nude mice was used to determine the impacts of let-7b on tumor growth in vivo. We observed that the let-7b-expression level of SGC7901/DDP cells was significantly lower than for its parental SGC7901 cells. Transfection of let-7b mimics was found to increase the cytotoxicity of DDP to SGC7901/DDP cells by inducing apoptosis. However, reversed cytotoxicity of DDP was observed in SGC7901/DDP cells with knockdown of let-7b. Luciferase reporter assay indicated that let-7b targeted AURKB in SGC7901/DDP cells. Knockdown of AURKB imitated the effect of let-7b overexpression on the sensitivity of SGC7901/DDP cells to DDP. Further investigation demonstrated that the SGC7901/DDP primary tumor growth was significantly reduced by let-7b mimic transfection. These findings indicate that overexpression of let-7b might provide a potential strategic approach for attenuating DDP resistance in SGC7901/DDP human gastric cancer cells.

Modulation in the microRNA repertoire is responsible for the stage-specific effects of Akt suppression on murine neuroendocrine prostate cancer

Recent studies indicate a stage-specific, differential role for the oncogene Akt on various cancers. In prostate cancer (PCa), suppression of Akt activity in the advanced stages promoted transforming growth factor-β (TGFβ) pathway-mediated epithelial-to-mesenchymal transition (EMT) and metastasis to the lungs. In the current study, we performed Affymetrix analysis to compare the expression profile of microRNAs in the mouse prostate tissues collected at the prostatic inter-epithelial neoplasia (PIN) stage from Transgenic adenocarcinoma of the mouse (TRAMP)/Akt1^+/+ versus TRAMP/Akt1^–/– mice, and at the advanced stage from TRAMP/Akt1^+/+ mice treated with triciribine (Akt inhibitor) versus DMSO-treated control. Our analysis demonstrates that in the early stage, Akt1 in the TRAMP prostate tumors express a set of miRNAs responsible for regulating cancer cell survival, proliferation, and tumor growth, whereas, in the advanced stages, a different set of miRNAs that promote EMT and cancer metastasis is expressed. Our study has identified novel Akt-regulated signature microRNAs in the early and advanced PCa and demonstrates their differential effects on PCa growth and metastasis.

EZH2 induces the expression of miR-1301 as a negative feedback control mechanism in triple negative breast cancer

Breast cancer is one of the most common malignancies in women. ERα, PR, and HER2 triple negative breast cancer (TNBC) is the current research focus because of the lack of effective targeted therapies. In our study, lentivirus systems were used to overexpress EZH2 and miR-1301 in TNBC cell lines. Western blot analysis and RT-qPCR were used to detect the protein and microRNA levels. The TCGA and Kaplan Meier plotter databases were used to analyze the EZH2 and miR-1301 expression levels in breast cancer. The effect of miR-1301 overexpression on cell proliferation, migration and colony formation were determined by using the sulforhodamine B (SRB) assay, wound healing assay and colony formation assay, respectively. Furthermore, an xenograft mouse model was used to investigate the function of miR-1301 overexpression in vivo. Finally, dual luciferase reporter assay was used to verify the binding site of EZH2 and miR-1301. We found that EZH2 induced the expression of miR-1301 in two TNBC cell lines, HCC1937 and HCC1806. Overexpression of miR-1301 suppressed TNBC cell proliferation, migration and colony formation, as well as the xenograft tumor growth in immunodeficient mice. Interestingly, miR-1301 inhibited the expression of EZH2 by binding to the 3'-UTR of EZH2 gene. These data suggest that EZH2 induces the expression of miR-1301 as a negative feedback control mechanism in TNBC.

Micrornas in prostate cancer: an overview

Prostate cancer is the second highest cause of cancer mortality after lung tumours. In USA it affects about 2.8 million men and the incidence increases with age in many countries. Therefore, early diagnosis is a very important step for patient clinical evaluation and for a selective and efficient therapy. The study of miRNAs' functions and molecular mechanisms has brought new knowledge in biological processes of cancer. In prostate cancer there is a deregulation of several miRNAs that may function as tumour suppressors or oncogenes. The aim of this review is to analyze the progress made to our understanding of the role of miRNA dysregulation in prostate cancer tumourigenesis.

Let-7e inhibits TNF-α expression by targeting the methyl transferase EZH2 in DENV2-infected THP-1 cells

Tumor necrosis factor α (TNFα), an important inflammatory cytokine, is associated with dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), a severe pathological manifestation of dengue virus (DENV) infection. However, the regulatory mechanism of microRNA on TNFα is currently unknown. Our study showed that the TNFα expression increased immediately and then later decreased, while a marked increase for the miRNA let-7e was detected in dengue virus type 2 (DENV2)-infected peripheral blood mononuclear cells (PBMCs). From this study, we found that let-7e was able to inhibit TNFα expression, but bioinformatics analysis showed that the enhancer of zeste homolog 2 (EZH2) was the potential direct target of let-7e instead of TNFα. EZH2 methyl transferase can produce H3K27me3 and has a negative regulatory role. Using a dual-luciferase reporter assay and Western blotting, we confirmed that EZH2 was a direct target of let-7e and found that siEZH2 could inhibit TNFα expression. In the further study of the regulatory mechanism of EZH2 on TNFα expression, we showed that siEZH2 promoted EZH1 and H3K4me3 expression and inhibited H3K27me3 expression. More importantly, we revealed that siEZH2 down-regulated NF-κB p65 within the nucleus. These findings indicate that the let-7e/EZH2/H3K27me3/NF-κB p65 pathway is a novel regulatory axis of TNFα expression. In addition, we determined the protein differences between siEZH2 and siEZH2-NC by iTRAQ and found a number of proteins that might be associated with TNFα.

Emerging biomarkers in the diagnosis of prostate cancer

Prostate cancer (PCa) is the second most common cancer in men worldwide. A large proportion of PCa are latent, never destined to progress or affect the patients’ life. It is of utmost importance to identify which PCa are destined to progress and which would benefit from an early radical treatment. Prostate-specific antigen (PSA) remains the most used test to detect PCa. Its limited specificity and an elevated rate of overdiagnosis are the main problems associated with PSA testing. New PCa biomarkers have been proposed to improve the accuracy of PSA in the management of early PCa. Commercially available biomarkers such as PCA3 score, Prostate Health Index (PHI), and the four-kallikrein panel are used with the purpose of reducing the number of unnecessary biopsies and providing information related to the aggressiveness of the tumor. The relationship with PCa aggressiveness seems to be confirmed by PHI and the four-kallikrein panel, but not by the PCA3 score. In this review, we also summarize new promising biomarkers, such as PSA glycoforms, TMPRSS2:ERG fusion gene, microRNAs, circulating tumor cells, androgen receptor variants, and PTEN gene. All these emerging biomarkers could change the management of early PCa, offering more accurate results than PSA. Nonetheless, large prospective studies comparing these new biomarkers among them are required to know their real value in PCa detection and prognosis.

Food as Pharma? The Case of Glucosinolates

BACKGROUND

Glucosinolates (GLSs) are dietary plant secondary metabolites occurring in the order Brassicales with potential health effects, in particular as anti-carcinogenic compounds. GLSs are converted into a variety of breakdown products (BPs) upon plant tissue damage and by the gut microbiota. GLS biological activity is related to BPs rather than to GLSs themselves.

METHODS

we have reviewed the most recent scientific literature on the metabolic fate and the biological effect of GLSs with particular emphasis on the epidemiological evidence for health effect and evidence from clinical trials. An overview of potential molecular mechanisms underlying GLS biological effect is provided. The potential toxic or anti-nutritional effect has also been discussed.

RESULTS

Epidemiological and human in vivo evidence point towards a potential anti-cancer effect for sulforaphane, indole-3-carbinol and 3,3-diindolylmethane. A number of new human clinical trials are on-going and will likely shed further light on GLS protective effect towards cancer as well as other diseases. BPs biological effect is the results of a plurality of molecular mechanisms acting simultaneously which include modulation of xenobiotic metabolism, modulation of inflammation, regulation of apoptosis, cell cycle arrest, angiogenesis and metastasis and regulation of epigenetic events. BPs have been extensively investigated for their protective effect towards cancer but in recent years the interest also includes other diseases.

CONCLUSION

It appears that certain BPs may protect against and may even represent a therapeutic strategy against several forms of cancer. Whether this latter effect can be achieved through diet or supplements should be investigated more thoroughly.

Epigenetic Contribution of High-Mobility Group A Proteins to Stem Cell Properties

High-mobility group A (HMGA) proteins have been examined to understand their participation as structural epigenetic chromatin factors that confer stem-like properties to embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and cancer stem cells (CSCs). The function of HMGA was evaluated in conjunction with that of other epigenetic factors such as histones and microRNAs (miRs), taking into consideration the posttranscriptional modifications (PTMs) of histones (acetylation and methylation) and DNA methylation. HMGA proteins were coordinated or associated with histone and DNA modification and the expression of the factors related to pluripotency. CSCs showed remarkable differences compared with ESCs and iPSCs.

Role of EZH2 in cancer stem cells: from biological insight to a therapeutic target

Epigenetic modifications in cancer stem cells largely result in phenotypic and functional heterogeneity in many solid tumors. Increasing evidence indicates that enhancer of zeste homolog 2 (EZH2), the catalytic subunit of Polycomb repressor complex 2, is highly expressed in cancer stem cells of numerous malignant tumors and has a critical function in cancer stem cell expansion and maintenance. Here, we review up-to-date information regarding EZH2 expression patterns, functions, and molecular mechanisms in cancer stem cells in various malignant tumors and discuss the therapeutic potential of targeting EZH2 in tumors.

Hsa-let-7c controls the committed differentiation of IGF-1-treated mesenchymal stem cells derived from dental pulps by targeting IGF-1R via the MAPK pathways

The putative tumor suppressor microRNA let-7c is extensively associated with the biological properties of cancer cells. However, the potential involvement of let-7c in the differentiation of mesenchymal stem cells has not been fully explored. In this study, we investigated the influence of hsa-let-7c (let-7c) on the proliferation and differentiation of human dental pulp-derived mesenchymal stem cells (DPMSCs) treated with insulin-like growth factor 1 (IGF-1) via flow cytometry, CCK-8 assays, alizarin red staining, real-time RT-PCR, and western blotting. In general, the proliferative capabilities and cell viability of DPMSCs were not significantly affected by the overexpression or deletion of let-7c. However, overexpression of let-7c significantly inhibited the expression of IGF-1 receptor (IGF-1R) and downregulated the osteo/odontogenic differentiation of DPMSCs, as indicated by decreased levels of several osteo/odontogenic markers (osteocalcin, osterix, runt-related transcription factor 2, dentin sialophosphoprotein, dentin sialoprotein, alkaline phosphatase, type 1 collagen, and dentin matrix protein 1) in IGF-1-treated DPMSCs. Inversely, deletion of let-7c resulted in increased IGF-1R levels and enhanced osteo/odontogenic differentiation. Furthermore, the ERK, JNK, and P38 MAPK pathways were significantly inhibited following the overexpression of let-7c in DPMSCs. Deletion of let-7c promoted the activation of the JNK and P38 MAPK pathways. Our cumulative findings indicate that Let-7c can inhibit the osteo/odontogenic differentiation of IGF-1-treated DPMSCs by targeting IGF-1R via the JNK/P38 MAPK signaling pathways.

Cancer Stem Cells, Bone and Tumor Microenvironment: Key Players in Bone Metastases

Tumor mass is constituted by a heterogeneous group of cells, among which a key role is played by the cancer stem cells (CSCs), possessing high regenerative properties. CSCs directly metastasize to bone, since bone microenvironment represents a fertile environment that protects CSCs against the immune system, and maintains their properties and plasticity. CSCs can migrate from the primary tumor to the bone marrow (BM), due to their capacity to perform the epithelial-to-mesenchymal transition. Once in BM, they can also perform the mesenchymal-to-epithelial transition, allowing them to proliferate and initiate bone lesions. Another factor explaining the osteotropism of CSCs is their ability to recognize chemokine gradients toward BM, through the CXCL12–CXCR4 axis, also known to be involved in tumor metastasis to other organs. Moreover, the expression of CXCR4 is associated with the maintenance of CSCs’ stemness, and CXCL12 expression by osteoblasts attracts CSCs to the BM niches. CSCs localize in the pre-metastatic niches, which are anatomically distinct regions within the tumor microenvironment and govern the metastatic progression. According to the stimuli received in the niches, CSCs can remain dormant for long time or outgrow from dormancy and create bone lesions. This review resumes different aspects of the CSCs’ bone metastastic process and discusses available treatments to target CSCs.

MicroRNAs and epithelial-mesenchymal transition in prostate cancer

Prostate cancer (PCa) is a leading cause of male cancer-related deaths. A significant fraction of prostate tumors are very aggressive, often metastasizing to bone, causing significant morbidity and mortality. Also, PCa is associated with high rates of recurrence, often attributed to the existence of cancer stem cells. Epithelial-mesenchymal transition (EMT), a process characterized by decreased expression of epithelial genes and increased expression of mesenchymal genes, plays a critical role in tumor invasion, metastasis and recurrence. In PCa, EMT has been implicated particularly in the context of metastatic disease and microRNAs have emerged as critical post-transcriptional regulators of PCa EMT. In this review, we summarize the role of miRNAs in PCa EMT that play a role in progression, metastasis and recurrence. Studies till date suggest that microRNAs mediate efficient and reversible control of PCa EMT via multiple mechanisms including either by (i) directly repressing single or multiple EMT-TFs or regulating cytoskeletal components (epithelial/mesenchymal genes) or (ii) regulating key signaling pathways involved in EMT. Oncogenic microRNAs often act as EMT promoters by repressing epithelial characteristics and tumor suppressive miRNAs act by inhibiting mesenchymal progression. Further, EMT is mechanistically linked to stem cell signatures in PCa and several miRNAs implicated in EMT have been reported to influence PCa stem cells. Loss of EMT-inhibiting miRNAs and/or gain of EMT promoting miRNAs lead to induction of PCa EMT, leading to tumor progression, metastasis and recurrence. Restoring expression of tumor suppressive miRNAs and inhibiting oncogenic miRNAs represent potential therapeutic opportunities to prevent disease metastasis and recurrence.

The Mechanism of Synchronous Precise Regulation of Two Shrimp White Spot Syndrome Virus Targets by a Viral MicroRNA

MicroRNAs (miRNAs), important factors in animal innate immunity, suppress the expressions of their target genes by binding to target mRNA’s 3′ untranslated regions (3′UTRs). However, the mechanism of synchronous regulation of multiple targets by a single miRNA remains unclear. In this study, the interaction between a white spot syndrome virus (WSSV) miRNA (WSSV-miR-N32) and its two viral targets (wsv459 and wsv322) was characterized in WSSV-infected shrimp. The outcomes indicated that WSSV-encoded miRNA (WSSV-miR-N32) significantly inhibited virus infection by simultaneously targeting wsv459 and wsv322. The silencing of wsv459 or wsv322 by siRNA led to significant decrease of WSSV copies in shrimp, showing that the two viral genes were required for WSSV infection. WSSV-miR-N32 could mediate 5′–3′ exonucleolytic digestion of its target mRNAs, which stopped at the sites of target mRNA 3′UTRs close to the sequence complementary to the miRNA seed sequence. The complementary bases (to the target mRNA sequence) of a miRNA 9th–18th non-seed sequence were essential for the miRNA targeting. Therefore, our findings presented novel insights into the mechanism of miRNA-mediated suppression of target gene expressions, which would be helpful for understanding the roles of miRNAs in innate immunity of invertebrate.

Detection of circulating miRNAs: comparative analysis of extracellular vesicle-incorporated miRNAs and cell-free miRNAs in whole plasma of prostate cancer patients

Background

Circulating cell-free miRNAs have emerged as promising minimally-invasive biomarkers for early detection, prognosis and monitoring of cancer. They can exist in the bloodstream incorporated into extracellular vesicles (EVs) and ribonucleoprotein complexes. However, it is still debated if EVs contain biologically meaningful amounts of miRNAs and may provide a better source of miRNA biomarkers than whole plasma. The aim of this study was to systematically compare the diagnostic potential of prostate cancer-associated miRNAs in whole plasma and in plasma EVs.

Methods

RNA was isolated from whole plasma and plasma EV samples from a well characterised cohort of 50 patient with prostate cancer (PC) and 22 patients with benign prostatic hyperplasia (BPH). Nine miRNAs known to have a diagnostic potential for PC in cell-free blood were quantified by RT-qPCR and the relative quantities were compared between patients with PC and BPH and between PC patients with Gleason score ≥ 8 and ≤6.

Results

Only a small fraction of the total cell-free miRNA was recovered from the plasma EVs, however the EV-incorporated and whole plasma cell-free miRNA profiles were clearly different. Four of the miRNAs analysed showed a diagnostic potential in our patient cohort. MiR-375 could differentiate between PC and BPH patients when analysed in the whole plasma, while miR-200c-3p and miR-21-5p performed better when analysed in plasma EVs. EV-incorporated but not whole plasma Let-7a-5p level could distinguish PC patients with Gleason score ≥ 8 vs ≤6.

Conclusions

This study demonstrates that for some miRNA biomarkers EVs provide a more consistent source of RNA than whole plasma, while other miRNAs show better diagnostic performance when tested in the whole plasma.

Brassica-Derived Plant Bioactives as Modulators of Chemopreventive and Inflammatory Signaling Pathways

A high consumption of vegetables belonging to the Brassicaceae family has been related to a lower incidence of chronic diseases including different kinds of cancer. These beneficial effects of, e.g., broccoli, cabbage or rocket (arugula) intake have been mainly dedicated to the sulfur-containing glucosinolates (GLSs)-secondary plant compounds nearly exclusively present in Brassicaceae-and in particular to their bioactive breakdown products including isothiocyanates (ITCs). Overall, the current literature indicate that selected Brassica-derived ITCs exhibit health-promoting effects in vitro, as well as in laboratory mice in vivo. Some studies suggest anti-carcinogenic and anti-inflammatory properties for ITCs which may be communicated through an activation of the redox-sensitive transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) that controls the expression of antioxidant and phase II enzymes. Furthermore, it has been shown that ITCs are able to significantly ameliorate a severe inflammatory phenotype in colitic mice in vivo. As there are studies available suggesting an epigenetic mode of action for Brassica-derived phytochemicals, the conduction of further studies would be recommendable to investigate if the beneficial effects of these compounds also persist during an irregular consumption pattern.

Resveratrol and pterostilbene as a microRNA-mediated chemopreventive and therapeutic strategy in prostate cancer

Growing evidence indicates that deregulation of the epigenetic machinery comprising the microRNA (miRNA) network is a critical factor in the progression of various diseases, including cancer. Concurrently, dietary phytochemicals are being intensively studied for their miRNA-mediated health-beneficial properties, such as anti-inflammatory, cardioprotective, antioxidative, and anticancer properties. Available experimental data have suggested that dietary polyphenols may be effective miRNA-modulating chemopreventive and therapeutic agents. Moreover, noninvasive detection of changes in miRNA expression in liquid biopsies opens enormous possibilities for their clinical utilization as novel prognostic and predictive biomarkers. In our published studies, we identified resveratrol-regulated miRNA profiles in prostate cancer. Resveratrol downregulated the phosphatase and tensin homolog (PTEN)-targeting members of the oncogenic miR-17 family of miRNAs, which are overexpressed in prostate cancer. We have functionally validated the miRNA-mediated ability of resveratrol and its potent analog pterostilbene to rescue the tumor suppressor activity of PTEN in vitro and in vivo. Taken together, our findings implicate the use of resveratrol and its analogs as an attractive miRNA-mediated chemopreventive and therapeutic strategy in prostate cancer and the use of circulating miRNAs as potential predictive biomarkers for clinical development.

Prostate Cancer Stem Cell Markers Drive Progression, Therapeutic Resistance, and Bone Metastasis

Metastatic or recurrent tumors are the primary cause of cancer-related death. For prostate cancer, patients diagnosed with local disease have a 99% 5-year survival rate; however, this 5-year survival rate drops to 28% in patients with metastatic disease. This dramatic decline in survival has driven interest in discovering new markers able to identify tumors likely to recur and in developing new methods to prevent metastases from occurring. Biomarker discovery for aggressive tumor cells includes attempts to identify cancer stem cells (CSCs). CSCs are defined as tumor cells capable of self-renewal and regenerating the entire tumor heterogeneity. Thus, it is hypothesized that CSCs may drive primary tumor aggressiveness, metastatic colonization, and therapeutic relapse. The ability to identify these cells in the primary tumor or circulation would provide prognostic information capable of driving prostate cancer treatment decisions. Further, the ability to target these CSCs could prevent tumor metastasis and relapse after therapy allowing for prostate cancer to finally be cured. Here, we will review potential CSC markers and highlight evidence that describes how cells expressing each marker may drive prostate cancer progression, metastatic colonization and growth, tumor recurrence, and resistance to treatment.

Anticancer Natural Compounds as Epigenetic Modulators of Gene Expression

Accumulating evidence shows that hallmarks of cancer include: "genetic and epigenetic alterations leading to inactivation of cancer suppressors, overexpression of oncogenes, deregulation of intracellular signaling cascades, alterations of cancer cell metabolism, failure to undergo cancer cell death, induction of epithelial to mesenchymal transition, invasiveness, metastasis, deregulation of immune response and changes in cancer microenvironment, which underpin cancer development". Natural compounds as bioactive ingredients isolated from natural sources (plants, fungi, marine life forms) have revolutionized the field of anticancer therapeutics and rapid developments in preclinical studies are encouraging. Natural compounds could affect the epigenetic molecular mechanisms that modulate gene expression, as well as DNA damage and repair mechanisms. The current review will describe the latest achievements in using naturally produced compounds targeting epigenetic regulators and modulators of gene transcription in vitro and in vivo to generate novel anticancer therapeutics.

Integrated genomic analyses of de novo pathways underlying atypical meningiomas

Meningiomas are mostly benign brain tumours, with a potential for becoming atypical or malignant. On the basis of comprehensive genomic, transcriptomic and epigenomic analyses, we compared benign meningiomas to atypical ones. Here, we show that the majority of primary (de novo) atypical meningiomas display loss of NF2, which co-occurs either with genomic instability or recurrent SMARCB1 mutations. These tumours harbour increased H3K27me3 signal and a hypermethylated phenotype, mainly occupying the polycomb repressive complex 2 (PRC2) binding sites in human embryonic stem cells, thereby phenocopying a more primitive cellular state. Consistent with this observation, atypical meningiomas exhibit upregulation of EZH2, the catalytic subunit of the PRC2 complex, as well as the E2F2 and FOXM1 transcriptional networks. Importantly, these primary atypical meningiomas do not harbour TERT promoter mutations, which have been reported in atypical tumours that progressed from benign ones. Our results establish the genomic landscape of primary atypical meningiomas and potential therapeutic targets.

Meningiomas are mostly benign brain tumours with the potential for becoming atypical or malignant. Here, the authors show that primary atypical meningiomas are epigenetically and genetically distinct from benign and progressed tumours, highlighting possible therapeutic targets such as PRC2.

miRNAs as novel biomarkers in the management of prostate cancer

microRNAs (miRNAs) are small non-coding RNAs that control gene expression posttranscriptionally and are part of the giant non codifying genoma. Cumulating data suggest that miRNAs are promising potential biomarkers for many diseases, including cancer. Prostate cancer (PCa) detection is currently based in the serum prostate-specific antigen biomarker and digital rectal examination. However, these methods are limited by a low predictive value and the adverse consequences associated with overdiagnosis and overtreatment. New biomarkers that could be used for PCa detection and prognosis are still needed. Recent studies have demonstrated that aberrant expressions of microRNAs are associated with the underlying mechanisms of PCa. This review attempts to extensively summarize the current knowledge of miRNA expression patterns, as well as their targets and involvement in PCa pathogenesis. We focused our review in the value of circulating and urine miRNAs as biomarkers in PCa patients, highlighting the existing discrepancies between different studies, probably associated with the important methodological issues related to their quantitation and normalization. The majority of studies have been performed in serum or plasma, but urine obtained after prostate massage appears as a new way to explore the usefulness of miRNAs. Large screening studies to select a miRNA profile have been completed, but bioinformatics tools appear as a new approach to select miRNAs that are relevant in PCa development. Promising preliminary results were published concerning miR-141, miR-375 and miR-21, but larger and prospective studies using standardized methodology are necessary to define the value of miRNAs in the detection and prognosis of PCa.

Circulating Plasma MicroRNAs As Diagnostic Markers for NSCLC

Lung cancer is the most common cause of cancer deaths all over the world, in which non-small cell lung cancer (NSCLC) accounts for ~85% of cases. It is well known that microRNAs (miRNAs) play a critical role in various cellular processes, mediating post-transcriptional silencing either by mRNA degradation through binding the 3' UTR of target mRNA or by translational inhibition of the protein. In the past decade, miRNAs have also been increasingly identified in biological fluids such as human serum or plasma known as circulating or cell-free miRNAs, and may function as non-invasive diagnostic markers for various cancer types including NSCLC. Circulating tumor cells (CTCs) are those cells that are shed from solid tumors and then migrate into the circulation. However, reports concerning the roles of CTCs are quite rare, which may be attributed to the difficulties in the enrichment and detection of CTCs in the circulation. Although, there have been reassuring advances in identifying circulating miRNA-panels, which are assumed to be of diagnostic value in NSCLC early stage, some issues remain concerning the reliability of using miRNA panels as a diagnostic tool for NSCLC. In the current review, we are aiming at providing insights into the miRNAs biology, the mechanisms of miRNAs release into the bloodstream, cell-free miRNAs as the diagnostic markers for NSCLC and the current limitations of CTCs as diagnostic markers in NSCLC.

Let‑7a suppresses cell proliferation via the TGF‑β/SMAD signaling pathway in cervical cancer

Cervical cancer is the second most commonly diagnosed type of cancer among women after breast cancer. Recent research has addressed the role of microRNAs in cervical cancer. In the present study, we aimed to determine the effect of let‑7a on the regulation of the cell proliferation of cervical cancer and the related signaling pathway. Real‑time RT‑PCR was used to detect the expression of let‑7a in the blood of cervical cancer patients and normal controls. The expression of let‑7a was also assessed in cervical cancer cell lines: HeLa, SiHa and normal human immortalized keratinocyes HaCaT. Cell proliferation was tested by MTT assay, and cell apoptosis and cell cycle were examined by flow cytometric analysis in HeLa cells. Moreover, bioinformatic analysis, dual‑luciferase reporter assay and western blotting were used to confirm the target gene for let‑7a. In addition, the expression of TGF‑β1, SMAD4 and p53 were assessed by western blotting and real‑time PCR. Our studies showed that the expression of let‑7a in cervical cancer was significantly reduced in cervical cancer patients compared with the expression in the normal control group. Cell proliferation of HeLa cells was inhibited by overexpression of let‑7a. The cell cycle analysis showed that an increased population was arrested in the G2 phase in the let‑7a mimic group when compared with that in the mimic control and untreated groups. In addition, the cell cycle‑related factor p53 was increased in the let‑7a overexpression group compared with that in the control and untreated groups. Furthermore, TGFBR1 was confirmed to be a target of let‑7a. Moreover, the expression of TGF‑β1 and SMAD4 proteins was elevated in cervical squamous carcinoma and cervical adenocarcinoma tissues. However, the expression of TGF‑β1 and SMAD4 was decreased in the let‑7a‑overexpressing cervical cancer cell lines (HeLa, SiHa and CaSki). Our data suggest that let‑7a may play a role in the cell proliferation of cervical cancer by regulating the TGF‑β/SMAD pathway, and may participate in the regulation of the occurrence and development of cervical cancer.

Non-coding RNA/microRNA-modulatory dietary factors and natural products for improved cancer therapy and prevention: Alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins

Non-coding small RNA molecules, the microRNAs (miRNAs), contribute decisively to the epigenetic regulation processes in cancer cells. Problematic pathogenic properties of cancer cells and the response of cancers towards anticancer drugs are highly influenced by miRNAs. Both increased drug activity and formation of tumor resistance are regulated by miRNAs. Further to this, the survival and proliferation of cancer cells and the formation of metastases is based on the modulated expression of certain miRNAs. In particular, drug-resistant cancer stem-like cells (CSCs) depend on the presence and absence of specific miRNAs. Fortunately, several small molecule natural compounds were discovered that target miRNAs involved in the modulation of tumor aggressiveness and drug resistance. This review gives an overview of the effects of a selection of naturally occurring small molecules (alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins) on miRNAs that are closely tangled with cancer diseases.

The evolving landscape of prostate cancer stem cell: Therapeutic implications and future challenges

Prostate cancer (PCa) is the most common cause of malignancy in males and the second leading cause of cancer mortality in United States. Current treatments for PCa include surgery, radiotherapy, and androgen-deprivation therapy. Eventually, PCa relapses to an advanced castration-resistant PCa (CRPC) that becomes a systematic disease and incurable. Therefore, identifying cellular components and molecular mechanisms that drive aggressive PCa at early stage is critical for disease prognosis and therapeutic intervention. One potential strategy for aggressive PCa is to target cancer stem cells (CSCs) that are identified by several unique characteristics such as immortal, self-renewal, and pluripotency. Also, CSC is believed to be a major factor contributing to resistance to radiotherapy and conventional chemotherapies. Moreover, CSCs are thought to be the critical cause of metastasis, tumor recurrence and cancer-related death of multiple cancer types, including PCa. In this review, we discuss recent progress made in understanding prostate cancer stem cells (PCSCs). We focus on the therapeutic strategies aimed at targeting specific surface markers of CSCs, the key signaling pathways in the maintenance of self-renewal capacity of CSCs, ATP-binding cassette (ABC) transporters that mediate the drug-resistance of CSCs, dysregulated microRNAs expression profiles in CSCs, and immunotherapeutic strategies developed against PCSCs surface markers.

miR-34C Disrupts the Stemness of Purified CD133+ Prostatic Cancer Stem Cells

OBJECTIVE

To find the potential micro-RNA (miRNA) that could determine the fate of prostate cancer stem cells.

MATERIALS AND METHODS

We compared miRNA expression between our purified CD133⁺ prostatic cancer stem cells (PCSCs) and CD133^- cells. Sphere formation assay and matrigel-based cell invasion assay were applied to determine the stemness of CD133⁺ PCSCs after our manipulation of miRNA using miRNA mimic or miRNA inhibitor.

RESULTS

In this study, we identified that miR-34C was under-expressed in the purified CD133⁺ PCSCs and enforced introduction of miR-34C attenuated the stemness of CD133⁺ PCSCs. Clinically, we also observed a negative correlation between miR-34C and CD133.

CONCLUSION

Our data strongly suggest that miR-34C may play essential role in conferring castration resistance by equilibrating PSCS population.

An overview of long non-coding RNAs in ovarian cancers

As with miRNAs a decade ago, the scientific community recently understood that lncRNAs represent a new layer of complexity in the regulation of gene expression. Although only a subset of lncRNAs has been functionally characterized, it is clear that they are deeply involved in the most critical physiological and pathological biological processes. This review shows that in ovarian carcinoma, data already available testify to the importance of lncRNAs and that the demonstration of an ever-growing role of lncRNAs in the biology of this malignancy can be expected from future studies. We also underline the importance of their relationship with associated protein partners and miRNAs. Together, the available information suggests that the emerging field of lncRNAs will pave the way for a better understanding of ovarian cancer biology and might lead to the development of innovative therapeutic approaches. Moreover, lncRNAs expression signatures either alone or in combination with other types of markers (miRNAs, mRNAs, proteins) could prove useful to predict outcome or treatment follow-up in order to improve the therapeutic care of ovarian carcinoma patients.

H3K27 Methylation: A Focal Point of Epigenetic Deregulation in Cancer

Epigenetics, the modification of chromatin without changing the DNA sequence itself, determines whether a gene is expressed, and how much of a gene is expressed. Methylation of lysine 27 on histone 3 (H3K27me), a modification usually associated with gene repression, has established roles in regulating the expression of genes involved in lineage commitment and differentiation. Not surprisingly, alterations in the homeostasis of this critical mark have emerged as a recurrent theme in the pathogenesis of many cancers. Perturbations in the distribution or levels of H3K27me occur due to deregulation at all levels of the process, either by mutation in the histone itself, or changes in the activity of the writers, erasers, or readers of this mark. Additionally, as no single histone mark alone determines the overall transcriptional readiness of a chromatin region, deregulation of other chromatin marks can also have dramatic consequences. Finally, the significance of mutations altering H3K27me is highlighted by the poor clinical outcome of patients whose tumors harbor such lesions. Current therapeutic approaches targeting aberrant H3K27 methylation remain to be proven useful in the clinic. Understanding the biological consequences and gene expression pathways affected by aberrant H3K27 methylation may lead to identification of new therapeutic targets and strategies.

The roles of microRNAs in the progression of castration-resistant prostate cancer

Prostate cancer (PCa) is one of the leading causes of cancer-related death in men. PCa is androgen-dependent, and androgen-deprivation therapy is effective for first-line hormonal treatment, but the androgen-independent phenotype of PCa eventually develops, which is difficult to treat and has no effective cure. Recently, microRNAs have been discovered to have important roles in the initiation and progression of PCa, suggesting their use in diagnosis, predicting prognosis and development of treatment for castration-resistant PCa (CRPC). Understanding the networks of microRNAs and their target genes is necessary to ascertain their roles and importance in the development and progression of PCa. This review summarizes the current knowledge about microRNAs regulating PCa progression and elucidates the mechanism of progression to CRPC.

Roles of Dietary Phytoestrogens on the Regulation of Epithelial-Mesenchymal Transition in Diverse Cancer Metastasis

Epithelial-mesenchymal transition (EMT) plays a key role in tumor progression. The cells undergoing EMT upregulate the expression of cell motility-related proteins and show enhanced migration and invasion. The hallmarks of EMT in cancer cells include changed cell morphology and increased metastatic capabilities in cell migration and invasion. Therefore, prevention of EMT is an important tool for the inhibition of tumor metastasis. A novel preventive therapy is needed, such as treatment of natural dietary substances that are nontoxic to normal human cells, but effective in inhibiting cancer cells. Phytoestrogens, such as genistein, resveratrol, kaempferol and 3,3′-diindolylmethane (DIM), can be raised as possible candidates. They are plant-derived dietary estrogens, which are found in tea, vegetables and fruits, and are known to have various biological efficacies, including chemopreventive activity against cancers. Specifically, these phytoestrogens may induce not only anti-proliferation, apoptosis and cell cycle arrest, but also anti-metastasis by inhibiting the EMT process in various cancer cells. There have been several signaling pathways found to be associated with the induction of the EMT process in cancer cells. Phytoestrogens were demonstrated to have chemopreventive effects on cancer metastasis by inhibiting EMT-associated pathways, such as Notch-1 and TGF-beta signaling. As a result, phytoestrogens can inhibit or reverse the EMT process by upregulating the expression of epithelial phenotypes, including E-cadherin, and downregulating the expression of mesenchymal phenotypes, including N-cadherin, Snail, Slug, and vimentin. In this review, we focused on the important roles of phytoestrogens in inhibiting EMT in many types of cancer and suggested phytoestrogens as prominent alternative compounds to chemotherapy.

Cross Talk between Cancer and Mesenchymal Stem Cells through Extracellular Vesicles Carrying Nucleic Acids

Extracellular vesicles (EVs) are considered to be a novel complex mechanism of cell communication within the tumor microenvironment. EVs may act as vehicles for transcription factors and nucleic acids inducing epigenetic changes in recipient cells. Since tumor EVs may be present in patient biological fluids, it is important to investigate their function and molecular mechanisms of action. It has been shown that tumor cells release EVs, which are capable of regulating cell apoptosis, proliferation, invasion, and epithelial-mesenchymal transition, as well as to suppress activity of immune cells, to enhance angiogenesis, and to prepare a favorable microenvironment for metastasis. On the other hand, EVs derived from stromal cells, such as mesenchymal stem cells (MSCs), may influence the phenotype of tumor cells through reciprocal cross talk greatly influenced by the transcription factors and nucleic acids they carry. In particular, non-coding RNAs (ncRNAs), including microRNAs and long ncRNAs, have recently been identified as the main candidates for the phenotypic changes induced in the recipient cells by EVs. ncRNAs, which are important regulators of mRNA and protein expression, can function either as tumor suppressors or as oncogenes, depending on their targets. Herein, we have attempted to revise actual evidence reported in the literature on the role of EVs in tumor biology with particular regard to the cross talk of ncRNAs between cancer cells and MSCs.

Targeting EZH2 for cancer therapy: progress and perspective

Enhancer of Zeste Homolog 2 (EZH2) is the core component of the polycomb repressive complex 2 (PRC2), possessing the enzymatic activity in generating di/tri-methylated lysine 27 in histone H3. EZH2 has important roles during early development, and its dysregulation is heavily linked to oncogenesis in various tissue types. Accumulating evidences suggest a remarkable therapeutic potential by targeting EZH2 in cancer cells. The first part reviews current strategies to target EZH2 in cancers, and evaluates the available compounds and agents used to disrupt EZH2 functions. Then we provide insight to the future direction of the research on targeting EZH2 in different cancer types. We comprehensively discuss the current understandings of the 1) structure and biological activity of EZH2, 2) its role during the assembling of PRC2 and recruitment of other protein components, 3) the molecular events directing EZH2 to target genomic regions, and 4) post-translational modification at EZH2 protein. The discussion provides the basis to inspire the development of novel strategies to abolish EZH2-related effects in cancer cells.

Mutations and deletions of PRC2 in prostate cancer

The Polycomb group of proteins (PcGs) are transcriptional repressor complexes that regulate important biological processes and play critical roles in cancer. Mutating or deleting EZH2 can have both oncogenic and tumor suppressive functions by increasing or decreasing H3K27me3. In contrast, mutations of SUZ12 and EED are reported to have tumor suppressive functions. EZH2 is overexpressed in many cancers, including prostate cancer, which can lead to silencing of tumor suppressors, genes regulating epithelial to mesenchymal transition (EMT), and interferon signaling. In some cases, EZH2 overexpression also leads to its use of non-histone substrates. Lastly, PRC2 associated factors can influence the progression of cancer through progressive mutations or by specific binding to certain target genes. Here, we discuss which mutations and deletions of the PRC2 complex have been detected in different cancers, with a specific focus on the overexpression of EZH2 in prostate cancer.

Higher EZH2 expression is associated with extramedullary infiltration in acute myeloid leukemia

Accumulating evidence indicates that enhancer of zeste homolog 2 (EZH2) promotes the metastatic ability of solid tumors, but the role of EZH2 in extramedullary infiltration (EMI) in acute myeloid leukemia (AML) has not been thoroughly explored. In the present study, we investigated the possible association between EZH2 and EMI. We found that the messenger RNA (mRNA) and protein expression levels of EZH2 in AML patients were both significantly higher than in idiopathic thrombocytopenic purpura (ITP) patients. Furthermore, a positive correlation between EZH2 mRNA expression and percentage of peripheral blood blasts wa s found in AML patients (r = 0.404, p = 0.009). The migratory capacities of Kasumi-1 and HL-60, which both show a high level of EZH2 expression, were markedly higher than those of U937 and KG-1α. In contrast, silencing of EZH2 resulted in reduction in proliferation and migration ability and an increase in apoptosis. The latter observation was accompanied by reduced expression of associated proteins p-ERK, p-cmyc, and matrix metalloproteinase 2 (MMP-2) and an increase in epithelial cadherin (E-cadherin). These data suggest that higher expression of EZH2 may be associated with extramedullary infiltration in acute myeloid leukemia and affect pathogenesis via activation of the p-ERK/p-cmyc/MMP-2 and E-cadherin signaling pathways.

Epigenetic regulators: Polycomb-miRNA circuits in cancer

Polycomb group (PcG) proteins belong to a family of epigenetic modifiers and play a key role in dynamic control of their target genes. Several reports have found that aberrations in PcG-microRNA (miRNA) interplay in various cancer types often associated with poor clinical prognosis. This review discusses important PcG-miRNA molecular networks which act as critical interfaces between chromatin remodeling, and transcriptional and post-transcriptional regulation of their target genes in cancer. Moreover, here are discussed several compounds influencing the activity of PcG proteins entered in clinical arena for the treatment of solid tumors, multiple myeloma and B lymphomas, thus highlighting the therapeutic potential of targeting this protein family.

JMJD1A promotes tumorigenesis and forms a feedback loop with EZH2/let-7c in NSCLC cells

Lung cancer is the most common cause of cancer-related deaths worldwide, and non-small cell lung cancer (NSCLC) accounts for 80 to 85 % of all lung cancer. Although the standard treatment regimen has been established, long-term survival for NSCLC patients is still generally poor. The histone demethylase Jumonji domain containing 1A (JMJD1A) has been proposed as an oncogene in several types of human cancer, but its clinical significance and functional roles in NSCLC remain largely unclear. In the present study, JMJD1A was frequently upregulated in NSCLC compared with para-carcinoma tissues. JMJD1A knockdown significantly inhibited NSCLC cell growth, migration, and invasion in vitro and tumorigenesis in vivo. Further experiments demonstrated that JMJD1A knockdown could decrease the expression of EZH2, which has been shown to play a crucial role in the carcinogenesis of NSCLC and, in turn, increase the expression of anti-tumor microRNA let-7c. Also, let-7c directly targeted the 3'-untranslated regions of JMJD1A and EZH2. Taken together, JMJD1A could promote NSCLC tumorigenesis. JMJD1A/EZH2/let-7c constituted a feedback loop and might represent a promising therapeutic target for NSCLC.

The bounty of nature for changing the cancer landscape

The landscape of cancer has changed considerably in past several years, due mainly to aggressive screening, accumulation of data from basic and epidemiological studies, and the advances in translational research. Natural anticancer agents have always been a part and parcel of cancer research. The initial focus on natural anticancer agents was in context of their cancer chemopreventive properties but their ability to selectively target oncogenic signaling pathways has also been recognized. In light of the rapid advancements in our understanding of the role of microRNAs, cancer stem cells, and epigenetic events in cancer initiation and progression, a number of natural anticancer agents are showing promise in vitro, in vivo as well as in preclinical studies. Moreover, parent structures of natural agents are being extensively modified with the hope of improving efficacy, specificity, and bioavailability. In this article, we focus on two natural agents, 3,3'-diindolylmethane and garcinol, along with 3,4-difluorobenzo curcumin, a synthetic analog of natural agent curcumin. We showcase how these anticancer agents are changing cancer landscape by modulating novel microRNAs, epigenetic factors, and cancer stem cell markers. These activities are relevant and being appreciated for overcoming drug resistance and inhibition of metastases, the two overarching clinical challenges in modern medicine.

The role of microRNAs in prostate cancer progression

Prostate cancer (PCa) is the most common male malignancy and the second highest cause of cancer-related mortality in United States. MicroRNAs (miRNAs) are small non-coding RNAs that represent a new mechanism to regulate mRNA post-transcriptionally. It is involved in diverse physiological and pathophysiological process. Dysregulation of miRNAs has been associated with the multistep progression of PCa from prostatic intraepithelial neoplasia (PIN), localized adenocarcinoma to metastatic castration-resistance PCa (CRPC). Identification of unique miRNA could provide new biomarkers for PCa and develop into therapeutic strategies. In this review, we will summarize a broad spectrum of both tumor suppressive and oncogenic miRNAs, and their mechanisms contribute to prostate carcinogenesis.

Epigenetics in Personalized Management of Lung Cancer

In last several years, the focus on the origin and progression of human cancers has shifted from genetic to epigenetic regulation, with particular attention to methylation and acetylation events that have profound effect on the eventual expression of oncogenes and the suppression of tumor suppressors. A few drugs targeting these epigenetic changes have already been approved for treatment, albeit not for lung cancer. With the recent advances in the push towards personalized therapy, questions have been asked about the possible targeting of epigenetic events for personalized lung cancer therapy. Some progress has been made but a lot needs to be done. In this chapter, a succinct review of these topics is provided.

Epigenetic and miRNAs Dysregulation in Prostate Cancer: The role of Nutraceuticals

The control of cancer onset and progression is recognized to benefit from specific molecular targeting. MiRNAs are increasingly being implicated in prostate cancer, and the evidence suggests they are possible targets for molecular therapy and diagnosis. In cancer cells, growing attention has been dedicated to novel molecular mechanisms linking the epigenetic scenario to miRNA dysregulation. Currently, the rising evidence shows that nutritional and natural agents, the so-called nutraceuticals, could modulate miRNAs expression, and, as a consequence, might influence cellular responses in health or diseases conditions, including cancer. Among dietary components, plant-derived polyphenols are receiving wide interest, either for their anti-aging and anti-oxidant properties, or for their more general "cell-protective" effects. Above all, their role in preventing the occurrence/recurrence of cancer and, in particular, their potentiality in nutritional intervention for modulating the functions of miRNAs and the epigenetic mechanisms, is still under active debate. This review is focused on the more recent highlights of the impact of miRNAs dysregulation on the onset and progression of prostate cancer, their interplay with epigenetic control and their modulation by natural agents.

Indole-3-Carbinol and Its Role in Chronic Diseases

Indole-3-carbinol (I3C), a common phytochemical in cruciferous vegetables, and its condensation product, 3,3'-diindolylmethane (DIM) exert several biological activities on cellular and molecular levels, which contribute to their well-recognized chemoprevention potential. Initially, these compounds were classified as blocking agents that increase drug-metabolizing enzyme activity. Now it is widely accepted that I3C and DIM affect multiple signaling pathways and target molecules controlling cell division, apoptosis, or angiogenesis deregulated in cancer cells. Although most of the current data support the role of I3C and DIM in prevention of hormone-dependent cancers, it seems that their application in prevention of the other cancer as well as cardiovascular disease, obesity, and diabetes reduction is also possible. This chapter summarizes the current experimental data on the I3C and DIM activity and the results of clinical studies indicating their role in prevention of chronic diseases.