MicroRNA145 targets BNIP3 and suppresses prostate cancer progression

MicroRNA Expression Profile on Solid Subtype of Invasive Lung Adenocarcinoma Reveals a Panel of Four miRNAs to Be Associated with Poor Prognosis in Chinese Patients

According to the reclassification of lung adenocarcinoma (LAC) proposed in 2011, solid predominant lung adenocarcinoma (SPA) has been associated with poor outcomes for LAC patients. However, the prognostic value of the presence of solid subtype remains unclear. Besides, there is little data about the roles of microRNA (miRNA) in solid subtype of LAC. In this study, 243 LAC patients were classified into solid subtype positive and negative groups (S+ LAC, n=134 and S- LAC, n=109) according to whether the solid subtype was more than 5% of the tumor component or not. We analyzed the relationship between solid subtype and patients' outcome by univariate and multivariate analyses. Solid subtype was proved to be significantly associated with the 5-year overall survival and played as an independent prognostic factor for stage I-III invasive LAC patients. Then miRNA microarray was used to identify differentially expressed miRNAs in solid subtype, resulting in 31 differential miRNAs. Quantitative reverse transcription-PCR (QRT-PCR) was used to validate 4 key miRNAs (miR-133b, miR-155-5p, miR-124-3p, miR-145-5p). Further, CCK-8 and transwell assays were performed to validate the impact of one dysregulated miRNA (miR-133b) on LAC cell function. Interestingly, while miR-133b could significantly inhibit the proliferation of A549 and SPC-A1, it showed no effect on the migration or invasion of LAC cell lines. These results suggest that solid subtype can exert independent prognostic impact on LAC patients, and 4 important dysregulated miRNAs in solid subtype of LAC may be involved in the malignancy of S+LAC, thus may further have clinical perspective for S+ LAC in the future.

Screening of Differently Expressed miRNA and mRNA in Prostate Cancer by Integrated Analysis of Transcription Data

OBJECTIVE

The purpose of this study was to screen aberrantly expressed miRNAs and genes in prostate cancer (PCA), and further uncover the underlying mechanisms for the development of PCA.

MATERIALS AND METHODS

We searched the Gene Expression Omnibus database for miRNA and gene expression datasets of PCA, and then separately integrated miRNA and gene expression datasets to identify miRNA and gene expression profiles in PCA. Target genes of differentially expressed miRNAs were predicted through miRWalk database. We matched these target genes with the list of differentially expressed genes to identify miRNA-target gene pairs whose expression was inversely correlated. The function of these target genes was annotated.

RESULTS

Twenty-nine differentially expressed miRNAs and 946 differentially expressed genes were identified between PCA and normal control. Seven hundred fifty-one miRNA-target gene pairs that showed inverse expression in PCA were obtained to establish a regulatory network. In this regulatory network, 10 genes (BCL2, BNC2, CCND2, EPM2A, MRAS, NAV2, RASL12, STK33, TCEAL1, WWC2) were co-regulated by 5 miRNAs (hsa-miR-106b, hsa-miR-130b, hsa-miR-93, hsa-miR-153, hsa-miR-182). The expression of hsa-miR-182 was significantly associated with PCA survival through the online validation tool of SurvMicro, suggesting the potential use as a diagnostic or prognostic biomarker in PCA.

CONCLUSION

This integrated analysis was performed to infer new miRNA regulation activities, which provides insights into the understanding of underlying molecular mechanisms of PCA, and guides for exploration of novel therapeutic targets.

MiRNA Expression Analysis of Pretreatment Biopsies Predicts the Pathological Response of Esophageal Squamous Cell Carcinomas to Neoadjuvant Chemoradiotherapy

OBJECTIVE

To identify miRNA markers useful for esophageal squamous cell carcinoma (ESCC) neoadjuvant chemoradiotherapy (neo-CRT) response prediction.

SUMMARY

Neo-CRT followed by surgery improves ESCC patients' survival compared with surgery alone. However, CRT outcomes are heterogeneous, and no current methods can predict CRT responses.

METHODS

Differentially expressed miRNAs between ESCC pathological responders and nonresponders after neo-CRT were identified by miRNA profiling and verified by real-time quantitative polymerase chain reaction (qPCR) of 27 ESCCs in the training set. Several class prediction algorithms were used to build the response-classifying models with the qPCR data. Predictive powers of the models were further assessed with a second set of 79 ESCCs.

RESULTS

Ten miRNAs with greater than a 1.5-fold change between pathological responders and nonresponders were identified and verified, respectively. A support vector machine (SVM) prediction model, composed of 4 miRNAs (miR-145-5p, miR-152, miR-193b-3p, and miR-376a-3p), were developed. It provided overall accuracies of 100% and 87.3% for discriminating pathological responders and nonresponders in the training and external validation sets, respectively. In multivariate analysis, the subgroup determined by the SVM model was the only independent factor significantly associated with neo-CRT response in the external validation sets.

CONCLUSIONS

Combined qPCR of the 4 miRNAs provides the possibility of ESCC neo-CRT response prediction, which may facilitate individualized ESCC treatment. Further prospective validation in larger independent cohorts is necessary to fully assess its predictive power.

Small molecule-mediated up-regulation of microRNA targeting a key cell death modulator BNIP3 improves cardiac function following ischemic injury

Genetic ablation of BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), an essential regulator of cardiac cell death, is an effective way to prevent cardiac cell death triggered by pathologic conditions. However, currently there exists no known means, such as inhibitors, to down-regulate BNIP3 in mature heart. Here, we report that a small molecule inducer of microRNA-182 (miR-182) suppressed ischemia/reperfusion (I/R)-induced cardiac cell death by down-regulating BNIP3. We first selected miR-182 as a potent BNIP3-targeting miRNA based on miRNA-target prediction databases and empirical data. The subsequent screening of small molecules for inducing miR-182 expression identified Kenpaullone as a hit compound. Both exogenous miR-182 and Kenpaullone significantly suppressed hypoxia-induced cardiomyocyte death in vitro. To investigate the effect of changing substituents of Kenpaullone on miR-182 expression, we synthesized 9 derivatives of Kenpaullone. Among these derivatives, compound 5 showed significantly improved ability to induce miR-182 expression. The results of the in vivo study showed that compound 5 significantly improved heart function following I/R-injury in rats. Our study provides strong evidence that the small molecule-mediated up-regulation of miRNAs is a viable strategy to down-regulate target proteins with no known chemical inhibitor and that compound 5 may have potential to prevent I/R-inflicted cardiac cell death.

Intravesical treatment of advanced urothelial bladder cancers with oncolytic HSV-1 co-regulated by differentially expressed microRNAs

Urothelial bladder cancer is the most common malignancy of the urinary tract. Although most cases are initially diagnosed as non-muscle-invasive, more than 80% of patients will develop recurrent or metastatic tumors. No effective therapy exists currently for late-stage metastatic tumors. By intravesical application, local administration of oncolytic Herpes Simplex virus (oHSV-1) can provide a promising new therapy for this disease. However, its inherent neurotoxicity has been a perceived limitation for such application. In this study, we present a novel microRNA-regulatory approach to reduce HSV-1-induced neurotoxicity by suppressing viral replication in neurons while maintaining oncolytic selectivity toward urothelial tumors. Specifically, we designed a recombinant virus that utilizes differentially expressed endogenous microR143 (non-cancerous, ubiquitous) and microR124 (neural-specific) to regulate expression of ICP-4, a gene essential for HSV-1 replication. We found that expression of ICP-4 must be controlled by a combination of both miR143 and miR124 to achieve the most effective attenuation in HSV-1-induced toxicity while retaining maximal oncolytic capacity. These results suggest that interaction between miR143 and miR124 may be required to successfully regulate HSV-1 replication. Our resent study is the first proof-in-principle that miRNA combination can be exploited to fine-tune the replication of HSV-1 to treat human cancers.

Mitophagy programs: mechanisms and physiological implications of mitochondrial targeting by autophagy

Mitochondria are an essential source of ATP for cellular function, but when damaged, mitochondria generate a plethora of stress signals, which lead to cellular dysfunction and eventually programmed cell death. Thus, a major component of maintaining cellular homeostasis is the recognition and removal of dysfunctional mitochondria through autophagy-mediated degradation, i.e., mitophagy. Mitophagy further constitutes a developmental program, and undergoes a high degree of crosstalk with apoptosis. Reduced mitochondrial quality control is linked to disease pathogenesis, suggesting the importance of process elucidation as a clinical target. Recent work has revealed multiple mitophagy programs that operate independently or undergo crosstalk, and require modulated autophagy receptor activities at outer membranes of mitochondria. Here, we review these mitophagy programs, focusing on pathway mechanisms which recognize and target mitochondria for sequestration by autophagosomes, as well as mechanisms controlling pathway activities. Furthermore, we provide an introduction to the currently available methods for detecting mitophagy.

MicroRNAs mediating CNS inflammation: Small regulators with powerful potential

MicroRNAs (miRNAs) are a family of small non-coding RNAs (~22 nucleotides) that fine-tune protein expression by either silencing mRNA translation or directly targeting gene transcripts for degradation. In the central nervous system (CNS), neuroinflammation plays a critical role in brain injury and neurodegeneration. Increasing evidence supports the involvement of miRNAs as key regulators of neuroinflammation. Altered expression or function of particular miRNAs has been identified in various CNS pathological conditions, including neuroinflammation, neurodegeneration, and autoimmune diseases. Several miRNAs have been shown to play a critical role in the microglia-mediated inflammatory response including miR-155 and miR-146a. In this review, we summarize recent advances in the field of miRNAs associated with CNS inflammation, including our studies of unique inflammatory pathways involving miR-155 and miR-146a. We discuss how specific miRNAs influence microglia activation states in response to inflammatory stimuli, and describe the potential of miRNAs as both biomarkers of inflammation and therapeutic tools for the modulation of microglia behavior.

The role of miR-145 in stem cell characteristics of human laryngeal squamous cell carcinoma Hep-2 cells

The cancer stem-like cells (CSLCs) are tumorigenic cells promoting initiation, progression, and spread of the tumor. Accumulating evidences suggested the presence of CSLCs in distinct tumors including laryngeal squamous cell carcinoma (LSCC). MicroRNAs have been proposed as significant regulators of carcinogenesis, and several of them have been demonstrated to have direct roles in survival of CSLCs. In this study, we aimed to explore the role of miR-145, which is downregulated in LSCC, on cancer stem cell potency of laryngeal cancer cells. We initially showed the downregulation of miR-145 expression in tumor tissue samples and in CD133-enriched CSLCs. Quantitative reverse-transcription PCR (qRT-PCR) analysis of miR-145-transfected Hep-2 cells demonstrated the inhibitory role of miR-145 on stem cell markers like SOX2, OCT4, KLF4, and ABCG2. We, then, investigated the stem cell features of miR-145-overexpressing Hep-2 cells by sphere formation assay, single-cell cloning assay, and aldehyde dehydrogenase (ALDH) assay, which all demonstrated the inhibition of stem cell potency upon miR-145 overexpression. Further qRT-PCR analysis demonstrated altered expression of epithelial to mesenchymal transition markers in miR-145-overexpressing Hep-2 cells. In conclusion, we demonstrated the regulatory role of miR-145 in stem cell characteristics of Hep-2 cells. Based on these results, we propose that miR-145 might carry crucial roles in LSCC tumorigenesis, prognosis, metastasis, chemoresistance, and recurrence through regulating stem cell properties of tumor cells.

Transcriptional regulation of BNIP3 by Sp3 in prostate cancer

BACKGROUND

The transcription factors Sp3/Sp1 are expressed in a various types of cancers and BNIP3 is overexpressed in prostate cancer. Although it has been demonstrated that BNIP3 is transcriptionally regulated by HIF-1α and is post-transcriptionally regulated by miR145, our previous data indicated that there might be some other transcription factors regulating BNIP3 in prostate cancer. This study is conducted to investigate whether BNIP3 expression is directly regulated by Sp3/Sp1 or not.

MATERIALS AND METHODS

Bioinformatics analysis shows that BNIP3 promoter contains several potential Sp3/Sp1 binding sites. And then it is demonstrated that SP3 could regulate the BNIP3 transcriptionally by binding to the predicted sites by dual reporter gene assays, ChIP, and EMSA. The biological effects of SP3 regulating BNIP3 on prostate cancer cells proliferation are measured by MTT, TUNEL, and flow cytometry.

RESULTS

Our data show that Sp3 but not Sp1, is positively related to BNIP3 overexpression in prostate cancer. Sp3 can directly regulate BNIP3 transcription by mainly binding to the Sp3 binding sites (-624~-615 and -350~-343) of BNIP3 promoter. Knockdown of Sp3 by RNA interference could reduce cells growth and lead to cells apoptosis in PC-3 and DU145. Sp3-dependent BNIP3 overexpression might be an important mechanism to promote prostate cancer cells proliferation.

CONCLUSION

This is the first study to provide direct evidence of Sp3-dependent BNIP3 expression. Sp3 might be the major transcriptional regulator of BNIP3 in prostate cancer and it is worthy to further study. The regulation of BNIP3 by Sp3 may be a new cancer-specific therapeutic target in prostate cancer.

The role of miRNAs in bone metastasis and their significance in the detection of bone metastasis: a review of the published data

The preferential metastasis of cancer cells to bone disrupts the process of bone remodeling and results in serious complications. Although bone imaging techniques are well established for bone metastasis diagnosis, they still have limits. Recently, small noncoding RNA molecules, called miRNAs, have become the subject of interest in many molecular pathways in relation to bone metastasis. Furthermore, studies have demonstrated the ability to distinguish normal from cancerous cells and metastatic bone tumor origin based on miRNA profiles. Here, we summarize the data on mechanisms of osteolytic and osteoblastic bone metastases supporting the involvement of miRNA changes in the bone metastatic evolution. We also focus on the available evidence regarding current clinical studies of miRNA expression in the detection of bone metastases.

Low miR-143/miR-145 Cluster Levels Induce Activin A Overexpression in Oral Squamous Cell Carcinomas, Which Contributes to Poor Prognosis

Deregulated expression of activin A is reported in several tumors, but its biological functions in oral squamous cell carcinoma (OSCC) are unknown. Here, we investigate whether activin A can play a causal role in OSCCs. Activin A expression was assessed by qPCR and immunohistochemistry in OSCC tissues. Low activin A-expressing cells were treated with recombinant activin A and assessed for apoptosis, proliferation, adhesion, migration, invasion and epithelial-mesenchymal transition (EMT). Those phenotypes were also evaluated in high activin A-expressing cells treated with follistatin (an activin A antagonist) or stably expressing shRNA targeting activin A. Transfections of microRNA mimics were performed to determine whether the overexpression of activin A is regulated by miR-143/miR-145 cluster. Activin A was overexpressed in OSCCs in comparison with normal oral mucosa, and high activin A levels were significantly associated with lymph node metastasis, tumor differentiation and poor survival. High activin A levels promoted multiple properties associated with malignant transformation, including decreased apoptosis and increased proliferation, migration, invasion and EMT. Both miR-143 and miR-145 were markedly downregulated in OSCC cell lines and in clinical specimens, and inversely correlated to activin A levels. Forced expression of miR-143 and miR-145 in OSCC cells significantly decreased the expression of activin A. Overexpression of activin A in OSCCs, which is controlled by downregulation of miR-143/miR-145 cluster, regulates apoptosis, proliferation and invasiveness, and it is clinically correlated with lymph node metastasis and poor survival.

Identification of apoptosis-related microRNAs and their target genes in myocardial infarction post-transplantation with skeletal myoblasts

Background

Skeletal myoblasts (SkMs) has provided a promising treatment for myocardial infarction (MI). Functioning as posttranscriptional regulators, microRNAs (miRNAs) play important roles in cardiac repairment and stem cell regulation. However, the correlation between miRNAs and their targeted genes in SkM cell therapy for MI was not fully understood.

Methods

We explored the cardioprotection by SkMs in infracted rats and determined cardiac functions at 4 weeks. In addition, we compared the expression profiles of miRNAs and mRNAs in post-MI rats with or without SkM cell therapy using microarray. The concordance between miRNA expression and mRNA levels of potential target genes was confirmed by quantitative real-time PCR.

Results

Quantitative echocardiography and histology showed improved cardiac function, attenuated heart infarcted area and inhibited cardiomyocyte apoptosis in the SkM group, compared with MI group. We identified that 160 miRNAs were differentially expressed in MI group as compared to the control group and 78 miRNAs were differentially expressed in the SkM treated group as compared to the untreated post-MI. We focused on a novel set of apoptosis-associated miRNAs and their target genes, among which 4 miRNAs (miR-30a-5p, miR-30c-5p, miR-145-5p, miR-140-3p), except one (miR-143-3p), were downregulated in the SkM treated group as compared to the untreated group. Furthermore, we found seven genes including Angptl4, Dpep1, Egr1, Eif5a, Tsc22d3, Irs2 and Cebpb that showed a linear correlation with which miRNAs.

Conclusions

The downregulation of apoptosis-regulatory miRNAs and in turn upregulation of target genes may partially account for rescue effect of SKM therapy for MI.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0603-0) contains supplementary material, which is available to authorized users.

Prognostic role of microRNA-145 in prostate cancer: A systems review and meta-analysis

Background

Many studies have shown that microRNAs (miRNAs) exhibit altered expression in various cancers and may play an important role as prognostic biomarkers. The present meta-analysis was undertaken to summarize recent studies of the use of microRNA-145 (miR-145) in the assessment of prostate cancer and to analyze the prognostic role of miR-145 for disease-free survival (DFS) outcome.

Methods

The present meta-analysis was performed by searching PubMed with the use of multiple search strategies. Data were extracted from studies examining DFS in patients with prostate cancer who showed lower expression of miR-145. Pooled hazard ratios of miR-145 and 95% confidence intervals were calculated. Four studies with a total of 211 patients were included in this meta-analysis.

Results

For overall DFS, the pooled hazard ratio of lower miR-145 expression in prostate cancer was 0.74 (95% confidence interval: 0.23–2.34, P = 0.001). Thus, lower miR-145 expression was found to significantly predict poorer outcomes.

Conclusions

The present findings suggest that downregulation of the expression of miR-145 might predict poor prognosis in patients with prostate cancer.

Role of miRNA in cancer diagnosis, prognosis, therapy and regulation of its expression by Epstein-Barr virus and human papillomaviruses: With special reference to oral cancer

MicroRNAs (miRNAs) belong to class of small non-coding RNAs that regulate numerous biological processes by targeting broad set of messenger RNAs. Research on miRNA-based biomarkers has witnessed phenomenal growth, owing to non-invasive nature of miRNA based screening assays and their sensitivity and specificity in detecting cancers. Their discovery in humans in 2000 has led to an explosion in research in terms of their role as biomarker, therapeutic target and trying to elucidate their function. This review aims to summarize the function of microRNAs as well as to examine how dysregulation at any step in their biogenesis or functional pathway can play a role in development of cancer, together with its possible involvement in oral cancer. Overexpression of oncogenic miRNA may reduce protein products of tumor-suppressor genes but loss of tumor-suppressor miRNA expression may cause elevated levels of oncogenic protein. One or both of these alterations could represent new targets for cancer diagnosis and treatment in future. Many researchers have focused on genetic and epigenetic alterations in OSCC cells. The genetic susceptibility, endemic environment factors, and Epstein-Barr virus (EBV) infection are believed to be the major etiologic factors of OSCC. Once metastasis occurs, prognosis is very poor. It is urgently needed to develop biomarkers for early clinical diagnosis/prognosis, and novel effective therapies for oral carcinoma. High-risk HPV infection leads to aberrant expression of cellular oncogenic and tumor suppressive miRNAs. The emergence of miRNA knowledge, and its potential interactive action with such alterations, therefore creates new understanding of cell transformation.

Role of miR-145 in human laryngeal squamous cell carcinoma

BACKGROUND

Laryngeal squamous cell carcinoma (SCC), being an aggressive malignancy, is one of the most commonly diagnosed malignant types of head and neck SCC worldwide. Incidences of laryngeal SCC have been reported to increase recently. In this study, we aimed to explore the biological effects of miR-145 on laryngeal cancer cells.

METHODS

The relative miR-145 level in laryngeal SCC tumor tissues and normal samples was investigated. Then, Hep-2 cells were utilized for functional analysis of miR-145. The proliferation abilities of transfected cells were measured using MTS assay. Scratch assay and single colony migration assay were performed to observe the alterations in migration behavior of transfected cells. Caspase assay and cell cycle analysis were used to investigate the underlying reasons of proliferative inhibition in cells in which miR-145 is overexpressed. Moreover, expression of SOX2 was analyzed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analysis in Hep-2 cells upon miR-145 transfection and its expression was evaluated in tumor and normal tissue sample of the larynx.

RESULTS

The miR-145 expression in laryngeal SCC tumor samples has been shown to be downregulated. The miR-145 overexpression caused inhibition of proliferation and migration in Hep-2 cells through induction of apoptosis and cell cycle arrest. The SOX2 level was demonstrated to be overexpressed in tumor samples and its expression was significantly decreased in miR-145 overexpressed Hep-2 cells.

CONCLUSION

We have demonstrated the deregulation of miR-145 and SOX2 in laryngeal SCC. Based on these results, we propose that miR-145, as an important regulator of SOX2, carries crucial roles in laryngeal SCC tumorigenesis.

MiR200c targets IRS1 and suppresses prostate cancer cell growth

BACKGROUND

The downregulation of the tumor suppressor miR200c plays important roles in many malignant tumors. This study aims to show that miR200c is a posttranscriptional regulator of insulin receptor substrate 1 (IRS1) and over-expression of miR200c suppresses prostate cancer cell growth.

METHODS

Bioinformatics analysis was used to show potential post-translational regulation of IRS1 by miR200c. Dual reporter gene assays were chosen to test the binding of miR200c to the potential seed sequences in IRS1 3'UTR. RT-PCR, Q-PCR and western blot were applied to determine the regulation effect of miR200c on IRS1. CCK8 assay, soft agar assay, trypan blue exclusion assay and flow cytometric analysis were used to measure the biological effects of miR200c on prostate cancer cell proliferation and apoptosis.

RESULTS

The 449-455 nt, 3061-3067 nt, and 3096-3102 nt of the IRS1 3'-UTR were identified as three potential seed sequences for miR200c. MiR200c directly binds to IRS1 through the seed sequences in IRS1 3'-UTR. Artificial overexpression of miR200c significantly downregulated the mRNA and protein levels of IRS1, together with decreased cell proliferation and increased cell death of PC3 and DU145 cells.

CONCLUSIONS

Our results suggest that miR200c plays crucial roles in prostate cancer by post-transcriptional regulation of IRS1. The mir200c/IRS1 pathway may be a potential therapeutic target to prevent prostate cancer cell growth.

Overexpression of miR-145-5p inhibits proliferation of prostate cancer cells and reduces SOX2 expression

We aimed to perform functional analysis of miR-145-5p in prostate cancer (PCa) cells and to identify targets of miR-145-5p for understanding its role in PCa pathogenesis. PC3, DU145, LNCaP PCa, and PNT1a nontumorigenic prostate cell lines were utilized for functional analysis of miR-145-5p. Its overexpression caused inhibition of proliferation through apoptosis and reduced migration in PCa cells. SOX2 expression was significantly decreased in both mRNA and protein level in miR-145-5p-overexpressed PCa cells. We proposed that miR-145-5p, being an important regulator of SOX2, carries a crucial role in PCa tumorigenesis.

Noncoding RNAs as regulators of cardiomyocyte proliferation and death

Cardiovascular diseases are currently the main cause of morbidity and mortality worldwide. Ischemic heart disease, in particular, is responsible for the majority of cardiac-related deaths. Given the negligible regenerative potential of the human myocardium, there is a strong need for therapeutic strategies aiming at enhancing cardiomyocyte survival and proliferation following injury or at inhibiting their death. MicroRNAs (miRNAs) are small non-coding RNA molecules regulating gene expression at a post-transcriptional level with important functions in cardiovascular physiology and disease. It has been demonstrated that miRNAs can influence the ability of cardiomyocytes to enter the cell cycle and/or escape from death pathways. Additionally, long non coding-RNAs could be involved in such pathways. This review summarizes recent evidences on noncoding RNAs regulating proliferation and death of cardiomyocytes representing a future therapeutic for the treatment of heart diseases. This article is part of a Special Issue entitled SI: Non-coding RNAs.

The p53 Transcriptional Network Influences Microglia Behavior and Neuroinflammation

The tumor-suppressor protein p53 belongs to a family of proteins that play pivotal roles in multiple cellular functions including cell proliferation, cell death, genome stability, and regulation of inflammation. Neuroinflammation is a common feature of central nervous system (CNS) pathology, and microglia are the specialized resident population of CNS myeloid cells that initiate innate immune responses. Microglia maintain CNS homeostasis through pathogen containment, phagocytosis of debris, and initiation of tissue-repair cascades. However, an unregulated pro-inflammatory response can lead to tissue injury and dysfunction in both acute and chronic inflammatory states. Therefore, regulation of the molecular signals that control the induction, magnitude, and resolution of inflammation are necessary for optimal CNS health. We and others have described a novel mechanism by which p53 transcriptional activity modulates microglia behaviors in vitro and in vivo. Activation of p53 induces expression of microRNAs (miRNAs) that support microglia pro-inflammatory functions and suppress anti-inflammatory and tissue repair behaviors. In this review, we introduce the previously described roles of the p53 signaling network and discuss novel functions of p53 in the microglia-mediated inflammatory response in CNS health and disease. Ultimately, improved understanding of the molecular regulators modulated by p53 transcriptional activity in microglia will enhance the development of rational therapeutic strategies to harness the homeostatic and tissue repair functions of microglia.

Key regulators in prostate cancer identified by co-expression module analysis

Background

Prostate cancer (PrCa) is the most commonly diagnosed cancer in men in the world. Despite the fact that a large number of its genes have been investigated, its etiology remains poorly understood. Furthermore, most PrCa candidate genes have not been rigorously replicated, and the methods by which they biologically function in PrCa remain largely unknown.

Results

Aiming to identify key players in the complex prostate cancer system, we reconstructed PrCa co-expressed modules within functional gene sets defined by the Gene Ontology (GO) annotation (biological process, GO_BP). We primarily identified 118 GO_BP terms that were well-preserved between two independent gene expression datasets and a consequent 55 conserved co-expression modules within them. Five modules were then found to be significantly enriched with PrCa candidate genes collected from expression Quantitative Trait Loci (eQTL), somatic copy number alteration (SCNA), somatic mutation data, or prognostic analyses. Specifically, two transcription factors (TFs) (NFAT and SP1) and three microRNAs (hsa-miR-19a, hsa-miR-15a, and hsa-miR-200b) regulating these five candidate modules were found to be critical to the development of PrCa.

Conclusions

Collectively, our results indicated that genes with similar functions may play important roles in disease through co-expression, and modules with different functions could be regulated by similar genetic components, such as TFs and microRNAs, in a synergistic manner.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-1015) contains supplementary material, which is available to authorized users.

Reciprocal regulation of PCGEM1 and miR-145 promote proliferation of LNCaP prostate cancer cells

Prostate cancer gene expression marker 1 (PCGEM1) is a long non-coding RNA (lncRNA) overexpressed in prostate cancer (PCa) cells that promotes PCa initiation and progression, and protects against chemotherapy-induced apoptosis. The microRNA miR-145 functions as a tumor suppressor in PCa. We speculate that reciprocal regulation of PCGEM1 and miR-145 promote proliferation of LNCaP prostate cancer cells. To test this hypothesis, the interaction between PCGEM1 and miR-145 was examined using a luciferase reporter assay. Expression levels were selectively altered in LNCaP cells and noncancerous RWPE-1 prostate cells by transfection of miR-145 or small interfering RNA sequences against (siRNA) PCGEM1. Relative expression levels were detected by RT-PCR, tumor cell growth and early apoptosis by the MTT assay and flow cytometry, respectively, and tumor cell migration and invasion properties by transwell assays. The effect of siRNA PCGEM1 and miR-145 transfection on prostate cancer growth in vivo was examined in the (nu/nu) mouse model. PCGEM1 and miR-145 exhibited reciprocal regulation; downregulation of PCGEM1 expression in LNCaP cells increased expression of miR-145, while overexpression of miR-145 decreased PCGEM1 expression. Transfection of the miR-145 expression vector and siRNA PCGEM1 inhibited tumor cell proliferation, migration, and invasion, and induced early apoptosis both in vitro. In contrast, there was no effect on RWPE-1 cells. We demonstrate a reciprocal negative control relationship between PCGEM1 and miR-145 that regulates both LNCaP cell proliferation and nu/nu PCa tumor growth. The results also identify PCGEM1 and associated regulators as possible targets for PCa therapy.

Up-regulation of microRNA-145 associates with lymph node metastasis in colorectal cancer

Metastasis is the main cause of mortality in patients with solid tumours. Identifying the exact molecules associated with CRC metastasis may be crucial to understand the process, which might also be translated to the diagnosis and treatment of CRC. In this study, we investigate the association of microRNA expression patterns with the lymph node metastasis of colorectal cancer. Among these candidate miRNAs, the expression of miRNA-145 was significantly related to lymph node metastasis of CRC. Both in vitro and in vivo study demonstrated that up-regulation of miR-145 could improve the ability of migration and invasion of colorectal cancer cell, while no effect on proliferation was observed. The mechanism of this promotion is associated with the stabilization of Hsp-27, a protein which plays an important role in the promotion of metastasis. These results may be crucial to understanding CRC metastasis and may be translated to the diagnosis and treatment of CRC.

MicroRNA-9 expression is a prognostic biomarker in patients with osteosarcoma

BACKGROUND

The purpose of the present study was to examine the expression levels of microRNA-9 (miR-9) in osteosarcoma tissues and normal bone tissues, and investigate the relationships between miR-9 expression, clinicopathological features and the prognosis of patients with osteosarcoma.

METHODS

The expression levels of miR-9 in osteosarcoma tissues and corresponding non-cancerous tissues were detected using a real-time quantitative assay. Differences in patient survival were determined using the Kaplan-Meier method and a log-rank test. A Cox proportional hazards regression analysis was used for univariate and multivariate analyses of prognostic values.

RESULTS

Compared to non-cancerous bone tissues, the expression levels of miR-9 in osteosarcoma tissues were significantly elevated (P < 0.001). We found that the expression level of miR-9 was significantly associated with tumor size (P = 0.011), clinical stage (P = 0.009) and distant metastasis (P < 0.001). The Kaplan-Meier curve showed that patients with low miR-9 expression survived significantly longer than patients with high miR-9 expression (P = 0.0017). Multivariate analysis suggested that miR-9 expression level (P = 0.002) is an independent prognostic factors for overall survival.

CONCLUSIONS

The findings of our study suggest that increased miR-9 expression has a strong correlation with the aggressive progression of osteosarcoma and its overexpression is a statistically significant risk factor affecting overall survival, suggesting that increased miR-9 expression could be a valuable marker of tumor progression and for prognosis of osteosarcoma.

miR-663 induces castration-resistant prostate cancer transformation and predicts clinical recurrence

Castration-resistant prostate cancer (CRPC) and its treatment are challenging issues in prostate cancer management. Here, we report that miR-663 is upregulated in CRPC tissues. Overexpression of miR-663 in prostate LNCaP cells promotes cell proliferation and invasion, neuroendocrine differentiation, and reduction in dihydrotestosterone-induced upregulation of prostate-specific antigen expression. Furthermore, results of in situ hybridization show that miR-663 expression is correlated with Gleason score and TNM stage and is an independent prognostic predictor of clinical recurrence. Together, these findings suggest that miR-663 is a potential oncomiR for CRPC and may serve as a tumor biomarker for the early diagnosis of CRPC.

The role of miRNAs in cancer: from pathogenesis to therapeutic implications

ABSTRACT: 

Cancer is still one of the dominating causes of deaths worldwide, although there have been important enhancements for detection and diagnosis of cancer recently. miRNAs are shown to participate in carcinogenesis of several types of tumors and their aberrant expression of miRNAs has been detected in cell lines, xenografts and clinical samples. miRNAs are thought to target and modulate the expression of more than 60% of human genes, which makes the expressional regulation by miRNAs the most abundant post-transcriptional regulation mode. Here, we have reviewed the most current literature to shed a light on the functions of miRNAs on human carcinogenesis. Possible roles of miRNAs in oncogenesis through both genetic and epigenetic changes occurring during cancer initiation, progression, invasion or metastasis are summarized.

MicroRNA-494-3p targets CXCR4 to suppress the proliferation, invasion, and migration of prostate cancer

BACKGROUND

Although SDF-1/CXCR4 pathway is a potential mechanism of tumor proliferation and progression, the mechanism of controlling CXCR4 expression is not fully understood. This study was to confirm that miR-494-3p might be a potentially post-transcriptional regulator of CXCR4 and over-expression of miR-494 might suppress prostate cancer progression and metastasis.

MATERIALS AND METHODS

We firstly postulated the post-transcriptional regulation of CXCR4 by miR-494-3p through bioinformatics analysis, and then it was demonstrated that miR-494-3p could regulate the CXCR4 mRNA post-transcriptionally by binding to the predicted site by dual reporter gene assays. The biological effect of miR-494-3p on prostate cancer cells proliferation, apoptosis, migration, and invasion was measured by MTT, TUNEL, flow cytometry, migration, and invasion assays.

RESULTS

It was shown that the mRNA and protein expression levels of CXCR4 were significantly up-regulated in PC-3 and DU145, whereas barely detected in LNCaP and RWPE-1. However, the CXCR4 protein levels were inversely related to the mature miR-494-3p expression levels in RWPE-1 and prostate cancer cells. The constitutive over-expression of miR-494-3p could down-regulate the protein level of CXCR4 in PC-3 and DU145. MiR-494-3p also could bind to the seed sequences in the 3'-UTR of the CXCR4 gene. Artificial over-expression of miR-494-3p could inhibit the growth, promote the apoptosis, and inhibit the migration and invasion of PC-3 and DU145 cells in vivo.

CONCLUSIONS

Our results suggested that miR-494-3p might play crucial role in prostate cancer by post-transcriptional regulation to CXCR4 mRNA. MiR-494-3p/CXCR4 pathway may be a potential therapeutic target to prevent prostate cancer progression and metastasis.

MicroRNAs expression and function in cerebral ischemia reperfusion injury

MicroRNAs (miRNAs) are small (18 ~ 25 nt) noncoding single-stranded RNA molecules that act as negative regulators of gene expression and modulating the stability and/or the translational efficiency of target messenger RNAs. Studies have shown that miRNAs control diverse aspects of brain disease. Recently, several studies have suggested that miRNAs alter the response to ischemia reperfusion injury and regulate the expression of various key elements in cell survival and apoptosis. This review article gives a brief overview of some miRNAs (miR-15a/b, miR-21, miR-29b/c, miR-124, miR-145, miR-181, miR-200 family, miR-338, miR-422a, miR-497, and miR let 7 family) in cerebral ischemia reperfusion injury. Although miRNAs could be potential therapeutic targets for the treatment of ischemia reperfusion injury, their safety and other limitations need further confirmation.

Tumor suppressor microRNAs: a novel non-coding alliance against cancer

Tumor initiation and progression are the outcomes of a stepwise accumulation of genetic alterations. Among these, gene amplification and aberrant expression of oncogenic proteins, as well as deletion or inactivation of tumor suppressor genes, represent hallmark steps. Mounting evidence collected over the last few years has identified different populations of non-coding RNAs as major players in tumor suppression in almost all cancer types. Elucidating the diverse molecular mechanisms underlying the roles of non-coding RNAs in tumor progression might provide illuminating insights, potentially able to assist improved diagnosis, better staging and effective treatments of human cancers. Here we focus on several groups of tumor suppressor microRNAs, whose downregulation exerts a profound oncologic impact and might be harnessed for the benefit of cancer patients.

BNIP3 supports melanoma cell migration and vasculogenic mimicry by orchestrating the actin cytoskeleton

BNIP3 is an atypical BH3-only member of the BCL-2 family of proteins with reported pro-death as well as pro-autophagic and cytoprotective functions, depending on the type of stress and cellular context. In line with this, the role of BNIP3 in cancer is highly controversial and increased BNIP3 levels in cancer patients have been linked with both good as well as poor prognosis. In this study, using small hairpin RNA (shRNA) lentiviral transduction to stably knockdown BNIP3 (BNIP3-shRNA) expression levels in melanoma cells, we show that BNIP3 supports cancer cell survival and long-term clonogenic growth. Although BNIP3-shRNA increased mitochondrial mass and baseline levels of reactive oxygen species production, which are features associated with aggressive cancer cell behavior, it also prevented cell migration and completely abolished the ability to form a tubular-like network on matrigel, a hallmark of vasculogenic mimicry (VM). We found that this attenuated aggressive behavior of these melanoma cells was underscored by severe changes in cell morphology and remodeling of the actin cytoskeleton associated with loss of BNIP3. Indeed, BNIP3-silenced melanoma cells displayed enhanced formation of actin stress fibers and membrane ruffles, while lamellopodial protrusions and filopodia, tight junctions and adherens junctions were reduced. Moreover, loss of BNIP3 resulted in re-organization of focal adhesion sites associated with increased levels of phosphorylated focal adhesion kinase. Remarkably, BNIP3 silencing led to a drop of the protein levels of the integrin-associated protein CD47 and its downstream signaling effectors Rac1 and Cdc42. These observations underscore that BNIP3 is required to maintain steady-state levels of intracellular complexes orchestrating the plasticity of the actin cytoskeleton, which is integral to cell migration and other vital processes stimulating cancer progression. All together these results unveil an unprecedented pro-tumorigenic role of BNIP3 driving melanoma cell's aggressive features, like migration and VM.

Genome-wide miRNA-profiling of aflatoxin B1-induced hepatic injury using deep sequencing

Aflatoxin B1 is a potent carcinogen which can induce** hepatocellular carcinoma (HCC) in mammals. Though microRNAs are known to play important roles in tumorigenesis, the functional complexity of microRNAs in AFB1-induced hepatocellular tumorigenesis has not yet been elucidated. Here, we applied Illumina deep sequencing technology for high-throughput profiling of microRNA in rat liver tissue before and after treatment with aflatoxin B1. Analysis of mature miRNAs from different arms of pre-miRNAs allowed us to identify the predominant form of miRNA. We studied the differential expression profile of miRNAs in two libraries, identifying several cancer-related microRNAs which exhibit abnormal expression. KEGG analysis indicated that predicted target genes of differentially expressed miRNAs are involved in cancer-related pathways. Bioinformatic analysis predicted 16 potential novel miRNAs. Our work provides new insights at the miRNA level into AFB1-induced hepatic injury which may lead to HCC.

Mitochondrial dysfunction in cancer

A mechanistic understanding of how mitochondrial dysfunction contributes to cell growth and tumorigenesis is emerging beyond Warburg as an area of research that is under-explored in terms of its significance for clinical management of cancer. Work discussed in this review focuses less on the Warburg effect and more on mitochondria and how dysfunctional mitochondria modulate cell cycle, gene expression, metabolism, cell viability, and other established aspects of cell growth and stress responses. There is increasing evidence that key oncogenes and tumor suppressors modulate mitochondrial dynamics through important signaling pathways and that mitochondrial mass and function vary between tumors and individuals but the significance of these events for cancer are not fully appreciated. We explore the interplay between key molecules involved in mitochondrial fission and fusion and in apoptosis, as well as in mitophagy, biogenesis, and spatial dynamics of mitochondria and consider how these distinct mechanisms are coordinated in response to physiological stresses such as hypoxia and nutrient deprivation. Importantly, we examine how deregulation of these processes in cancer has knock on effects for cell proliferation and growth. We define major forms of mitochondrial dysfunction and address the extent to which the functional consequences of such dysfunction can be determined and exploited for cancer diagnosis and treatment.

Molecular markers for prostate cancer in formalin-fixed paraffin-embedded tissues

Prostate cancer (PCa) is the most frequently diagnosed type of cancer in developed countries. The decisive method of diagnosis is based on the results of biopsies, morphologically evaluated to determine the presence or absence of cancer. Although this approach leads to a confident diagnosis in most cases, it can be improved by using the molecular markers present in the tissue. Both miRNAs and proteins are considered excellent candidates for biomarkers in formalin-fixed paraffin-embedded (FFPE) tissues, due to their stability over long periods of time. In the last few years, a concerted effort has been made to develop the necessary tools for their reliable measurement in these types of samples. Furthermore, the use of these kinds of markers may also help in establishing tumor grade and aggressiveness, as well as predicting the possible outcomes in each particular case for the different treatments available. This would aid clinicians in the decision-making process. In this review, we attempt to summarize and discuss the potential use of microRNA and protein profiles in FFPE tissue samples as markers to better predict PCa diagnosis, progression, and response to therapy.

MicroRNA-145 inhibits the proliferation, migration and invasion of the human TCA8113 oral cancer line

The aim of this study was to investigate the effect of microRNA (miR)-145 on the proliferation, migration and invasion of the human oral cancer line, TCA8113. Expression levels of miR-145 in TCA8113 cells were detected by quantitative PCR. miR-145 was transfected into human TCA8113 oral cancer cells and the proliferation, migration and invasion abilities of treated TCA8113 cells were detected by proliferation, migration and invasion assays, respectively. The expression levels of miR-145 in TCA8113 cells were significantly lower than those in human normal oral keratinocytes (P<0.05). Cellular proliferation, migration and invasion abilities in the miR-145 transfection group were significantly lower than those in the control group (all P<0.05). High miR-145 expression was found to negatively regulate the proliferation, migration and invasion of TCA8113 cells. Results of the present study indicate that the expression of miR-145 may be associated with the genesis and development of human oral cancer.

Downregulation of miR-145 contributes to lung adenocarcinoma cell growth to form brain metastases

The development of metastases involves the dissociation of cells from the primary tumor, penetrating the basement membrane, invasion and exiting from the vasculature to seed, and finally colonizing in distant tissues. The formation of brain metastasis (BM) in lung adenocarcinoma remains poorly understood. We examined the differential microRNA (miRNA) expression profiles of 5 primary and 3 brain metastatic lung adenocarcinoma samples by Agilent miRNA Microarrays. Five upregulated miRNAs (miRs-9*, -1471, 718, 3656, 720) and 3 downregulated miRNAs (miRs-214, -145 and -23a) were detected. The 4 most significantly deregulated miRNAs (miR-145, miR-214, miR-9* and miR-1471) were validated in the additional 43 samples (35 primary and 8 brain metastatic lung adenocarcinoma samples) using TaqMan quantitative PCR. By functional assay, we found that the expression of miR-145 can regulate the ability of proliferation of A549 and SPC-A1 cells in vitro, but is not related to lymph node metastasis, migration and invasion. These results suggest that miR-145 may have a cell type-specific function and play important roles in the process of BM from lung adenocarcinoma.

Downregulation of microRNA-130a contributes to endothelial progenitor cell dysfunction in diabetic patients via its target Runx3

Dysfunction of endothelial progenitor cells (EPCs) contributes to diabetic vascular disease. MicroRNAs (miRs) have emerged as key regulators of diverse cellular processes including angiogenesis. We recently reported that miR-126, miR-130a, miR-21, miR-27a, and miR-27b were downregulated in EPCs from type II diabetes mellitus (DM) patients, and downregulation of miR-126 impairs EPC function. The present study further explored whether dysregulated miR-130a were also related to EPC dysfunction. EPCs were cultured from peripheral blood mononuclear cells of diabetic patients and healthy controls. Assays on EPC function (proliferation, migration, differentiation, apoptosis, and colony and tubule formation) were performed. Bioinformatics analyses were used to identify the potential targets of miR-130a in EPCs. Gene expression of miR-103a and Runx3 was measured by real-time PCR, and protein expression of Runx3, extracellular signal-regulated kinase (ERK), vascular endothelial growth factor (VEGF) and Akt was measured by Western blotting. Runx3 promoter activity was measured by luciferase reporter assay. A miR-130a inhibitor or mimic and lentiviral vectors expressing miR-130a, or Runx3, or a short hairpin RNA targeting Runx3 were transfected into EPCs to manipulate miR-130a and Runx3 levels. MiR-130a was decreased in EPCs from DM patients. Anti-miR-130a inhibited whereas miR-130a overexpression promoted EPC function. miR-130a negatively regulated Runx3 (mRNA, protein and promoter activity) in EPCs. Knockdown of Runx3 expression enhanced EPC function. MiR-130a also upregulated protein expression of ERK/VEGF and Akt in EPCs. In conclusion, miR-130a plays an important role in maintaining normal EPC function, and decreased miR-130a in EPCs from DM contributes to impaired EPC function, likely via its target Runx3 and through ERK/VEGF and Akt pathways.

BNIP3 acts as transcriptional repressor of death receptor-5 expression and prevents TRAIL-induced cell death in gliomas

Glioblastoma multiforme (GBM) is the most common and malignant brain tumor, and current treatment modalities such as surgical resection, adjuvant radiotherapy and temozolomide (TMZ) chemotherapy are ineffective. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a novel cancer therapeutic agent for GBM because of its capability of inducing apoptosis in glioma cells. Unfortunately, the majority of glioma cells are resistant to TRAIL-induced apoptosis. The Bcl-2 nineteen kilodalton interacting protein (BNIP3) is a pro-cell death BH3-only member of the Bcl-2 family that is one of the highest expressed genes in hypoxic regions of GBM tumors. We previously found that BNIP3 is localized to the nucleus in GBM tumors and suppresses cell death in glioma cells. Herein, we have discovered when BNIP3 nuclear expression is knockdown in glioma cell lines and in normal mouse astrocytes, TRAIL and its death receptor, death receptor-5 (DR5) expression is increased. In addition, when nuclear BNIP3 expression is increased, the amount of TRAIL-induced apoptosis is reduced. Using a streptavidin pull-down assay, we found that BNIP3 binds to the DR5 promoter and nuclear BNIP3 binds to the DR5 promoter. Furthermore, nuclear BNIP3 expression in GBM tumors correlates with decreased DR5 expression. Taken together, we have discovered a novel transcriptional repression function for BNIP3 conferring a TRAIL resistance in glioma cells.

The proto-oncogene ERG is a target of microRNA miR-145 in prostate cancer

Prostate cancer is a leading cause of cancer mortality in men. One of the distinct characteristics of prostate cancer is over-expression of the ERG proto-oncogene. The TMPRSS2-ERG gene fusion, the most common gene fusion, is found in approximately 50% of prostate cancer cases. We show that certain microRNAs are extensively deregulated in prostate cancer cell lines and primary clinical cancer samples. MicroRNAs are capable of modulating post-transcriptional gene expression via inhibition of protein synthesis. Independent target prediction methods have indicated that the 3' untranslated region of the ERG mRNA is a potential target of miR-145. miR-145 is consistently down-regulated in prostate cancer. Here we show that the ERG 3' untranslated region is a regulative target of miR-145 in vitro. Ectopic expression of miR-145 led to a reduction in expression of the ERG protein. We analyzed 26 prostate cancer samples and corresponding normal tissue. ERG protein expression was found to be elevated in the tumor samples, together with increased expression of several ERG isoforms. We identified ERG proteins of 35 and 24 kDa, which may represent unknown ERG splice variants. Analyses of miR-145 and ERG mRNA expression revealed a general down-regulation of miR-145 irrespective of the presence or absence of translocations involving ERG. This observation indicates that down-regulation of miR-145 may contribute to the increased expression of most ERG splice variants sharing the miR-145 target sequence in their 3' untranslated region.

Non-Coding RNAs as Potential Neuroprotectants against Ischemic Brain Injury

Over the past decade, scientific discoveries have highlighted new roles for a unique class of non-coding RNAs. Transcribed from the genome, these non-coding RNAs have been implicated in determining the biological complexity seen in mammals by acting as transcriptional and translational regulators. Non-coding RNAs, which can be sub-classified into long non-coding RNAs, microRNAs, PIWI-interacting RNAs and several others, are widely expressed in the nervous system with roles in neurogenesis, development and maintenance of the neuronal phenotype. Perturbations of these non-coding transcripts have been observed in ischemic preconditioning as well as ischemic brain injury with characterization of the mechanisms by which they confer toxicity. Their dysregulation may also confer pathogenic conditions in neurovascular diseases. A better understanding of their expression patterns and functions has uncovered the potential use of these riboregulators as neuroprotectants to antagonize the detrimental molecular events taking place upon ischemic-reperfusion injury. In this review, we discuss the various roles of non-coding RNAs in brain development and their mechanisms of gene regulation in relation to ischemic brain injury. We will also address the future directions and open questions for identifying promising non-coding RNAs that could eventually serve as potential neuroprotectants against ischemic brain injury.

Heme levels are increased in human failing hearts

OBJECTIVES

The goal of this study was to characterize the regulation of heme and non-heme iron in human failing hearts.

BACKGROUND

Iron is an essential molecule for cellular physiology, but in excess it facilitates oxidative stress. Mitochondria are the key regulators of iron homeostasis through heme and iron-sulfur cluster synthesis. Because mitochondrial function is depressed in failing hearts and iron accumulation can lead to oxidative stress, we hypothesized that iron regulation may also be impaired in heart failure (HF).

METHODS

We measured mitochondrial and cytosolic heme and non-heme iron levels in failing human hearts retrieved during cardiac transplantation surgery. In addition, we examined the expression of genes regulating cellular iron homeostasis, the heme biosynthetic pathway, and micro-RNAs that may potentially target iron regulatory networks.

RESULTS

Although cytosolic non-heme iron levels were reduced in HF, mitochondrial iron content was maintained. Moreover, we observed a significant increase in heme levels in failing hearts, with corresponding feedback inhibition of the heme synthetic enzymes and no change in heme degradation. The rate-limiting enzyme in heme synthesis, delta-aminolevulinic acid synthase 2 (ALAS2), was significantly upregulated in HF. Overexpression of ALAS2 in H9c2 cardiac myoblasts resulted in increased heme levels, and hypoxia and erythropoietin treatment increased heme production through upregulation of ALAS2. Finally, increased heme levels in cardiac myoblasts were associated with excess production of reactive oxygen species and cell death, suggesting a maladaptive role for increased heme in HF.

CONCLUSIONS

Despite global mitochondrial dysfunction, heme levels are maintained above baseline in human failing hearts.

Apoptosis and microRNA aberrations in cancer

Carcinogenesis arises from the malfunction of genes that control cell growth and division. Therefore, the most effective method of hindering tumourigenesis is to induce the death of immortalized cancer cells. Apoptosis or programmed cell death has shown the most promises in impairing cancer growth. A variety of proteins is involved in the regulation of apoptosis and the malfunction of any these regulators may cause cell proliferation. The microRNAs have been shown to play a central role in the regulation of the cell cycle, including apoptosis. The microRNAs are involved in post-transcriptional gene suppression and have been implicated in the regulation of cell differentiation and development. Aberrations in the microRNA regulation of apoptosis lead to tumourigenesis. The present review assesses the current knowledge of apoptotic regulation in cancer and the effect of microRNA aberrations in tumourigenesis.

Downregulation of miR-145 associated with cancer progression and VEGF transcriptional activation by targeting N-RAS and IRS1

MicroRNA-145 (miR-145) is downregulated in various tumor types. However, its mechanism in inhibiting tumor growth and angiogenesis remains to be elucidated. In this study, we found that miR-145 was significantly downregulated in the plasma and cancer tumor tissues of colorectal cancer (CRC) patients, and overexpression of miR-145 inhibited cell proliferation, migration and invasion. To understand the potential mechanism of miR-145 in inhibiting tumor growth, we showed that miR-145 blocked the activation of AKT and ERK1/2 pathways, and the expression of HIF-1 and VEGF via directly targeting N-RAS and IRS1, and VEGF is an important effector for tumor growth. Forced expression of N-RAS and IRS1 restored VEGF expression via transcriptional activation. MiR-145 also inhibited N-RAS and IRS1 expression to suppress AKT and ERK1/2 activation, and VEGF expression in mouse xenograft tumors. To test the clinical relevance of these results, we used 60 pairs of colorectal cancer tissues and adjacent normal tissues, analyzed the levels of miR-145, N-RAS and IRS1 expression in these tissues, and found that miR-145 levels were significantly inversely correlated with N-RAS and IRS1 levels in these colorectal cancer tissues, suggesting the important implication of our findings in translational application for colorectal cancer diagnostics and treatment in the future.

MicroRNAs and prostate cancer: from preclinical research to translational oncology

The management of prostate cancer patients is rapidly changing. The extended survival seen in randomized phase III trials with new molecules has significantly enriched the therapeutic armamentarium, and ongoing clinical trials are assessing whether the integration of these active drugs within established therapeutic regimens results in a further benefit for patients. This complex scenario is raising the need for the identification and validation of biomarkers able to drive the decision-making process during the course of the disease. Compelling evidence has documented the role of microRNAs in cancer biology, and their multifaceted biological activity makes them an attractive candidate as diagnostic, prognostic, and predictive biomarkers. This review summarizes the current knowledge about microRNA deregulation in prostate cancer, how these molecules have been investigated in the clinical setting, and strategies investigators should consider for sharpening their potential.

Synergistic silencing by promoter methylation and reduced AP-2α transactivation of the proapoptotic HRK gene confers apoptosis resistance and enhanced tumor growth

The Harakiri (HRK) gene encodes an important proapoptotic mitochondrial protein of the Bcl-2 family. HRK is expressed in normal tissues but is decreased in many cancers such as melanoma, the mechanisms of which have not been fully elucidated. Here, we demonstrate that HRK is silenced by hypermethylation of a major proximal CpG island in the HRK promoter. Furthermore, we show that HRK is a novel target gene regulated by the transcription factor AP-2α, which interacts with an AP-2α binding site in the HRK promoter. Hypermethylation of the major proximal CpG island (which contains the AP-2α binding site within the most densely methylated -218- to -194-bp region) inhibited AP-2α binding and transcriptional activity. Artificial overexpression of AP-2α in melanoma cells up-regulated HRK transcription, which was further restored by treatment with DNA methyltransferase inhibitor 5-azacytidine. Artificial overexpression of HRK by recombinant adenovirus induced caspase-dependent apoptosis, inhibited melanoma cell growth in vitro, and markedly reduced in vivo melanoma growth in a nude mouse xenograft model. RNA interference by siHRK or siAP-2α reversed the above effects. We conclude that the synergistic effects of HRK promoter hypermethylation and loss of AP-2α transactivation lead to HRK gene silencing and confer resistance to apoptosis and enhanced tumor growth. These novel molecular lesions may provide the basis for new therapeutic approaches to treating AP-2α- and HRK-deficient cancers.

MiR-145 regulates epithelial to mesenchymal transition of breast cancer cells by targeting Oct4

MiR-145 could regulate tumor growth, apoptosis, migration, and invasion. In our present study, we investigated its role in epithelial-mesenchymal transition (EMT). Expression of miR-145 was decreased in breast tumor tissues at T3&4 stages in comparison with those at T1&2. Over-expression of miR-145 mimics enhanced protein levels of E-cadherin and dampened those of α-SMA and Fibronectin, indicative of its inhibitory role in EMT occurrence. Mechanistic studies showed that miR-145 mimics inhibited Oct4 expression and miR-145 inhibitor enhanced it. Over-expression of Oct4 reversed miR-145-regulated expression of EMT markers, suggesting that Oct4 mediated the inhibitory effects of miR-145. MiR-145 could inhibite the expression of Snail, ZEB1, and ZEB2, while over-expression of Oct4 rescued the effects. Furthermore, Oct-4 induced over-expression of transcription factor Snail, ZEB1 and ZEB2 was mediated by β-catenin. Expression of Slug and Twist were not altered by miR-145/Oct4. Taken together, our results have revealed a novel role of miR-145 on EMT. It inhibits EMT by blocking the expression of Oct4, and downstream transcriptional factors, Snail, ZEB1 and ZEB2.