Downregulation of miR-132 by promoter methylation contributes to pancreatic cancer development

DNA methylation landscape of fat deposits and fatty acid composition in obese and lean pigs

Obese and lean type pig breeds exhibit differences in their fat deposits and fatty acid composition. Here, we compared the effect of genome-wide DNA methylation on fatty acid metabolism between Landrace pigs (LP, leaner) and Rongchang pigs (RP, fatty). We found that LP backfat (LBF) had a higher polyunsaturated fatty acid content but a lower adipocyte volume than RP backfat (RBF). LBF exhibited higher global DNA methylation levels at the genome level than RBF. A total of 483 differentially methylated regions (DMRs) were located in promoter regions, mainly affecting olfactory and sensory activity and lipid metabolism. In LBF, the promoters of genes related to ATPase activity had significantly stronger methylation. This fact may suggest lower energy metabolism levels, which may result in less efficient lipid synthesis in LBF. Furthermore, we identified a DMR in the miR-4335 and miR-378 promoters and validated their methylation status by bisulfite sequencing PCR. The hypermethylation of the promoters of miR-4335 and miR-378 in LBF and the resulting silencing of the target genes may result in LBF's low content in saturated fatty acids and fat deposition capacity. This study provides a solid basis for exploring the epigenetic mechanisms affecting fat deposition and fatty acid composition.

microRNAs involved in Parkinson's disease: A systematic review

The aim of the present study was to determine the expression of blood microRNAs (miRNAs) involved in PD in humans. For this purpose the following electronic databases were selected: MEDLINE by Pubmed, Scopus and Web of Science. The search strategy included the proposed descriptors in the Medical Subject Headings. There were no restrictions with respect to the language of the publication. In the study selection two independent reviewers initially evaluated studies that were identified by the search strategy according to titles and abstracts. The reviewers evaluated (also unassisted) the complete articles and selected studies according to the eligibility criteria specified above. Studies that were not in accordance with the adopted criteria were excluded according to the boundaries imposed by the search strategy. The following data were extracted from the selected studies: Publication identification, location where the study was conducted, study design, the sample size, the participants' characteristics, the miRNAs involved in PD, the miRNA detection and analysis method, and the type of miRNA dysregulation in PD. Through this systematic review of the literature published over the last 10 years, the expression of 91 different miRNAs were analyzed in the context of PD, with the expression of 39 of these miRNAs differing significantly between individuals with PD and healthy controls and/or between treated and untreated patients with PD. The miRNAs were extracted from mononuclear cells, leukocytes, plasma, serum and peripheral blood, and the majority of the studies used reverse transcription‑quantitative polymerase chain reaction (RT-qPCR), which is considered to be the gold standard for miRNA analysis.

Downregulation of microRNA-132 indicates progression in hepatocellular carcinoma

Although miR-132 has been studied in various human tumors, few studies have investigated the role of miR-132 in hepatocellular carcinoma (HCC). The present study aimed to evaluate the associations between miR-132 and clinicopathological parameters, including recurrence, in patients with HCC. Reverse transcription-quantitative polymerase chain reaction analysis was used to detect the expression levels of miR-132 in 95 cases of HCC and their corresponding non-cancerous liver tissues. Th e associations between miR-132 expression levels and clinicopathological characteristics, including recurrence, were investigated in patients with HCC. miR-132 expression levels were significantly reduced in HCC tissues, as compared with adjacent non-cancerous tissues (1.9245±0.7564 vs. 2.7326±1.1475; P<0.001). The area under curve (AUC) of receiver operating characteristic (ROC) used to distinguish cancerous and non-cancerous tissues was 0.711 for miR-132 expression (95% confidence interval, 0.637-0.785; P<0.001) and the optimal cut-off value was 2.25. Expression levels of miR-132 were significantly reduced in the distant metastasis (P=0.031), advanced clinical TNM stage (P=0.022), hepatitis B virus-positive (P<0.001), NM23-expressed (P=0.034), high Ki-67 labeling index (LI; P=0.005) and tumor infiltration or no capsule groups (P=0.026). Spearman correlation analysis demonstrated that miR-132 was significantly correlated with hepatitis B virus infection (r=-0.351; P<0.001), NM23 (r=-0.220; P=0.032), Ki-67 LI (r=-0.264; P=0.010) and tumor capsule (r=-0.207; P=0.044). Kaplan-Meier analysis with the log-rank test indicated an approximate difference of 8 months, although miR-132 may exhibit inferior values for the prediction of recurrence in HCC patients (50.95 vs. 58.68 months; P=0.512). Therefore, the findings of the present study indicated that miR-132 is downregulated in HCC and may serve as a tumor suppressor in its progression.

miRNA regulation of Sirtuin-1 expression in human astrocytoma

Sirtuins are a family of 7 histone deacetylases largely involved in the regulation of cell proliferation, survival and death. The role of sirtuins in tumorigenesis and cancer progression has been previously studied in certain cancer types. Few studies have investigated sirtuin expression in gliomas, with controversial results. The aim of the present study was to investigate the expression of sirtuin-1 (Sirt-1) in diffuse astrocytoma [low grade astrocytoma (LGA)], anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM) and in primary glioma cell lines: PLGAC (primary LGA cells); PAAC (primary AA cells); and PGBMC (primary GBM cells). Tumor samples were obtained from patients who underwent craniotomy for microsurgical tumor resection at the Neurosurgery Unit of the University of Messina between 2011 and 2014. Sirt-1 expression was qualitatively analyzed in 30 human glial tumor samples and 5 non-neoplastic brain tissue (NBT) specimens using immunohistochemistry and western blotting techniques. Sirt-1 expression was quantitatively analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, Sirt-1 expression in primary cell lines was investigated by immunoblotting and RT-qPCR. Sirt-1 expression was downregulated in gliomas compared to NBTs. Sirt-1 levels also varied among different tumor grades, with more evident downregulation in high-grade (P<0.001) than low-grade tumors (P<0.01). These data were confirmed in cell lines, with the exception of upregulation of protein level in the highest malignancy grade cell lines. The present results suggest a role for miRNA-34a, miRNA-132 and miRNA-217 in the epigenetic control of Sirt-1 during gliomagenesis and progression, and demonstrate the different implications of Sirt-1 in human tissues and cell lines. Furthermore, the present results reveal that Sirt-1 may be an intrinsic regulator of tumor progression and the regulation of Sirt-1 involves complex molecular pathways. However, the biological functions of Sirt-1 in gliomagenesis require additional investigation.

Aberrant Expression of Breast Development-Related MicroRNAs, miR-22, miR-132, and miR-212, in Breast Tumor Tissues

PURPOSE

MicroRNAs (miRNAs) are a major class of small endogenous RNA molecules that posttranscriptionally regulate the expression of most genes in the human genome. miRNAs are often located in chromosomal fragile sites, which are suscept-ible to amplification or deletion. Chromosomal deletions are frequent events in breast cancer cells. Deletion and loss of heterozygosity at 17p13.3 have been reported in 49% of breast cancers. The aim of the current study was to evaluate potential expression alterations of miR-22, miR-132, and miR-212, which are located on the 17p13.3 locus and are required for mammary gland development.

METHODS

A matched case-control study was conducted, which included 36 pairs of tumor and matched nontumor surgical specimens from patients diagnosed with breast invasive ductal carcinoma. Formalin-fixed paraffin-embedded samples from archival collections at the pathology department of Shariati Hospital were prepared for RNA extraction using the xylene-ethanol method before total RNA was isolated with TRIzol Reagent. Specific primers were designed for cDNA synthesis and miRNA amplification. The expression of miRNAs was then evaluated by real-time polymerase chain reaction (RT-PCR).

RESULTS

According to our RT-PCR data, the miR-212/miR-132 family was downregulated in breast cancer (0.328-fold, p<0.001), and this reduced expression was the most prominent in high-grade tumors. In contrast, miR-22 exhibited a significant upregulation in breast tumor samples (2.183-fold, p=0.040).

CONCLUSION

Consistent with the frequent deletion of the 17p13.3 locus in breast tumor cells, our gene expression data demonstrated a significant downregulation of miR-212 and miR-132 in breast cancer tissues. In contrast, we observed a significant upregulation of miR-22 in breast tumor samples. The latter conflicting result may have been due to the upregulation of miR-22 in stromal/cancer-associated fibroblasts, rather than in the tumor cells.

Methylation of miR-145a-5p promoter mediates adipocytes differentiation

MicroRNAs (miRNAs, miR) play important roles in adipocyte development. Recent studies showed that the expression of several miRNAs is closely related with promoter methylation. However, it is not known whether miRNA mediates adipocytes differentiation by means of DNA methylation. Here, we showed that miR-145a-5p was poorly expressed in adipose tissue from mice fed a high fat diet (HFD). Overexpression or inhibition of miR-145a-5p was unfavorable or beneficial, respectively, for adipogenesis, and these effects were achieved by regulating adipocyte-specific genes involved in lipogenic transcription, fatty acid synthesis, and fatty acid transportation. Particularly, we first suggested that miR-145a-5p mimics or inhibitors promoted or repressed adipocytes proliferation by regulating p53 and p21, which act as cell cycle regulating factors. Surprisingly, the miR-145a-5p-repressed adipocyte differentiation was enhanced or rescued when cells treated with 5-Aza-dC were transfected with miR-145a-5p mimics or inhibitors, respectively. These data indicated that, as a new mean to positively regulate adipocyte proliferation, the process of miR-145a-5p-inhibited adipogenesis may be regulated by DNA methylation.

Wnt Pathway Stabilizes MeCP2 Protein to Repress PPAR-γ in Activation of Hepatic Stellate Cells

PPAR-γ is essential for differentiation of hepatic stellate cells (HSC), and its loss due to epigenetic repression by methyl-CpG binding protein 2 (MeCP2) causes HSC myofibroblastic activation mediated in part via Wnt pathway, the key cellular event in liver fibrosis. Decreased miR-132 was previously proposed to promote MeCP2 protein translation for Ppar-γ repression in activated HSC (aHSC). The present study aimed to test this notion and to better understand the mechanisms of MeCP2 upregulation in aHSC. MeCP2 protein is increased on day 3 to 7 as HSC become activated in primary culture on plastic, but this is accompanied by increased but not reduced miR-132 or miR-212 which is also expected to target MeCP2 due to its similar sequence with miR-132. The levels of these mRNAs are decreased 40~50% in aHSCs isolated from experimental cholestatic liver fibrosis but increased 6–8 fold in aHSC from hepatotoxic liver fibrosis in rats. Suppression of either or both of miR132 and miR212 with specific anti-miRNA oligonucleotides (anti-oligo), does not affect MeCP2 protein levels in aHSCs. The Wnt antagonist FJ9 which inhibits HSC activation, increases miR-132/miR-212, reduces MeCP2 and its enrichment at 5’ Ppar-γ promoter, and restores Ppar-γ expression but the anti-oligo do not prevent Ppar-γ upregulation. The pan-NADPH oxidase (NOX) inhibitor diphenyleneiodonium (DPI) also reduces both MeCP2 and stabilized non-(S33/S37/Thr41)-phospho β-catenin and reverts aHSC to quiescent cells but do not affect miR-132/miR-212 levels. Wnt antagonism with FJ9 increases MeCP2 protein degradation in cultured HSC, and FJ9-mediated loss of MeCP2 is rescued by leupeptin but not by proteasome and lysozome inhibitors. In conclusion, canonical Wnt pathway increases MeCP2 protein due to protein stability which in turn represses Ppar-γ and activates HSC.

Methylation-induced silencing of maspin contributes to the proliferation of human glioma cells

Maspin, a member of the serpin superfamily of serine protease inhibitors, has been reported to be involved in cancer initiation and progression. However, the expression of maspin and its expression regulation in glioma remain unknown. In the present study, we aimed to investigate the function of maspin in glioma cells and its regulatory mechanism. We found that the expression of maspin was silenced in glioma cells and tissues. Although maspin had no effect on the migration and invasion of human glioma cells in vitro, overexpression of maspin inhibited cell growth in U87 cells. We showed that the methylase inhibitor 5-Aza-2′-deoxycytidine induced the expression of maspin in glioma cell lines. Furthermore, both U87 and U251 cells showed hypermethylation in the maspin promoter. In addition, bisulphite sequencing analysis indicated that 16 CpG sites in the promoter were completely methylated in glioma cells and cancerous tissues, while CpG dinucleotides in the maspin promoter were unmethylated in normal brain tissues. Our data suggest that methylation-induced silencing of maspin contributes to the proliferation of human glioma cells, and maspin may be a potential therapeutic target in glioma.

Downregulated miR-506 expression facilitates pancreatic cancer progression and chemoresistance via SPHK1/Akt/NF-κB signaling

The aberrant expression of microRNAs (miRNAs) has emerged as an important hallmark of cancer. However, the molecular mechanisms underlying the changes in miRNA expression remain unclear. In this study, we discovered a novel epigenetic mechanism of miR-506 regulation and investigated its functional significance in pancreatic cancer. Sequencing analysis revealed that the miR-506 promoter is highly methylated in pancreatic cancer tissues compared with non-cancerous tissues. Reduced miR-506 expression was significantly associated with clinical stage, pathologic tumor status, distant metastasis and decreased survival of pancreatic cancer patients. miR-506 inhibited cell proliferation, induced cell cycle arrest at the G1/S transition and enhanced apoptosis and chemosensitivity of pancreatic cancer cells. Furthermore, we identified sphingosine kinase 1 (SPHK1) as a novel target of miR-506, the expression of which inhibited the SPHK1/Akt/NF-κB signaling pathway, which is activated in pancreatic cancer. High SPHK1 expression was significantly associated with poor survival in a large cohort of pancreatic cancer specimens. Our data suggest that miR-506 acts as a tumor suppressor miRNA and is epigenetically silenced in pancreatic cancer. The newly identified miR-506/SPHK1 axis represents a novel therapeutic strategy for future pancreatic cancer treatment.

Developments in miRNA gene signaling pathways in pancreatic cancer

Pancreatic cancer is a devastating malignancy that ranks as the fourth leading cause of cancer-related deaths worldwide. Dismal prognosis is mainly attributable to limited knowledge of the molecular pathogenesis of the disease. miRNAs have been found to be deregulated in pancreatic cancer, affecting several steps of initiation and aggressiveness of the disease by regulating important signaling pathways, such as the KRAS and Notch pathways. Moreover, the effect of miRNAs on regulating cell cycle events and expression of transcription factors has gained a lot of attention. Recent studies have highlighted the application of miRNAs as biomarkers and therapeutic tools. The current review focuses on latest advances with respect to the roles of miRNAs in pancreatic ductal adenocarcinoma associated signaling pathways and miRNA-based therapeutics.

The loop structure and the RNA helicase p72/DDX17 influence the processing efficiency of the mice miR-132

miRNAs are small RNAs that are key regulators of gene expression in eukaryotic organisms. The processing of miRNAs is regulated by structural characteristics of the RNA and is also tightly controlled by auxiliary protein factors. Among them, RNA binding proteins play crucial roles to facilitate or inhibit miRNA maturation and can be controlled in a cell, tissue and species-specific manners or in response to environmental stimuli. In this study we dissect the molecular mechanism that promotes the overexpression of miR-132 in mice over its related, co-transcribed and co-regulated miRNA, miR-212. We have shown that the loop structure of miR-132 is a key determinant for its efficient processing in cells. We have also identified a range of RNA binding proteins that recognize the loop of miR-132 and influence both miR-132 and miR-212 processing. The DEAD box helicase p72/DDX17 was identified as a factor that facilitates the specific processing of miR-132.

Radiation-induced miR-208a increases the proliferation and radioresistance by targeting p21 in human lung cancer cells

BACKGROUND

Lung cancer has long been the most dangerous malignant tumor among males in both well developed and poorly developed countries. Radiotherapy plays a critical role in the curative management of inoperable non-small cell lung cancer (NSCLC) and is also used as a post-surgical treatment in lung cancer patients. Radioresistance is an important factor that limits the efficacy of radiotherapy for NSCLC patients. Increasing evidence suggests that microRNAs (miRNAs) possess diverse cellular regulatory roles in radiation responses.

METHODS

In this study, we used miRNA microarray technology to identify serum miRNAs that were differentially expressed before and after radiotherapy in lung cancer patients. We further examined the biological function of miR-208a on cell viability, apoptotic death and cell cycle distribution in human lung cancer cells and explored the probable mechanism.

RESULTS

Nine miRNAs, including miR-29b-3p, miR-200a-3p, and miR-126-3p were significantly down-regulated, whereas miR-208a was the only miRNA that was up-regulated in the serum of the patients after radiation treatment (P < 0.05). The expression of miR-208a could be induced by X-ray irradiation in lung cancer cells. Forced expression of miR-208a promoted cell proliferation and induced radioresistance via targeting p21 with a corresponding activation of the AKT/mTOR pathway in lung cancer cells, whereas down-regulation of miR-208a resulted in the opposite effects. In addition, down-regulation of miR-208a increased the percentage of cells undergoing apoptosis and inhibited the G1 phase arrest in NSCLC cells. Moreover, miR-208a from the serum exosome fraction of lung cancer patients could shuttle to A549 cells in a time-dependent manner, which was likely to contribute to the subsequent biological effects.

CONCLUSIONS

The present study provides evidence that miR-208a can affect the proliferation and radiosensitivity of human lung cancer cells by targeting p21 and can be transported by exosomes. Thus, miR-208a may serve as a potential therapeutic target for lung cancer patients.

Genetic and epigenetic alterations of microRNAs and implications for human cancers and other diseases

MicroRNAs (miRNAs) are a well-studied group of noncoding RNAs that control gene expression by interacting mainly with messenger RNA. It is known that miRNAs and their biogenesis regulatory machineries have crucial roles in multiple cell processes; thus, alterations in these genes often lead to disease, such as cancer. Disruption of these genes can occur through epigenetic and genetic alterations, resulting in aberrant expression of miRNAs and subsequently of their target genes. This review focuses on the disruption of miRNAs and their key regulatory machineries by genetic alterations, with emphasis on mutations and epigenetic changes in cancer and other diseases.

Downregulation of microRNA-132 by DNA hypermethylation is associated with cell invasion in colorectal cancer

microRNAs (miRNAs) are small, noncoding RNAs that are involved in many biological processes, and aberrant regulation of miRNAs is always associated with cancer progression and development. Abnormal expression of miRNA-132 (miR-132) has been found in some types of cancer, but the effects and potential mechanisms of miR-132 in colorectal cancer (CRC) have not been explored to date. In this study, quantitative real-time polymerase chain reaction was used to investigate the level of miR-132 in CRC tissues and their paired adjacent normal tissues. Bioinformatics analysis indicated that the mechanism underlying the tumor suppressor role of miR-132 in CRC cells may play a role in tumor suppression by targeting paxillin. Furthermore, methylation-specific polymerase chain reaction was performed to evaluate the methylation status of the miR-132 regulatory region. A DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine, was used to activate the expression of miR-132 in CRC cells in vitro. Downregulation of miR-132 may occur as a result of hypermethylation and implies a poor prognosis in CRC; therefore, triggering miR-132 reexpression by using DNA methyltransferase inhibitors may be a potential molecular therapeutic target for CRC.

Regulatory RNAs and control of epigenetic mechanisms: expectations for cognition and cognitive dysfunction

The diverse functions of noncoding RNAs (ncRNAs) can influence virtually every aspect of the transcriptional process including epigenetic regulation of genes. In the CNS, regulatory RNA networks and epigenetic mechanisms have broad relevance to gene transcription changes involved in long-term memory formation and cognition. Thus, it is becoming increasingly clear that multiple classes of ncRNAs impact neuronal development, neuroplasticity, and cognition. Currently, a large gap exists in our knowledge of how ncRNAs facilitate epigenetic processes, and how this phenomenon affects cognitive function. In this review, we discuss recent findings highlighting a provocative role for ncRNAs including lncRNAs and piRNAs in the control of epigenetic mechanisms involved in cognitive function. Furthermore, we discuss the putative roles for these ncRNAs in cognitive disorders such as schizophrenia and Alzheimer's disease.

MicroRNA-132 enhances transition from inflammation to proliferation during wound healing

Wound healing is a complex process that is characterized by an initial inflammatory phase followed by a proliferative phase. This transition is a critical regulatory point; however, the factors that mediate this process are not fully understood. Here, we evaluated microRNAs (miRs) in skin wound healing and characterized the dynamic change of the miRNome in human skin wounds. miR-132 was highly upregulated during the inflammatory phase of wound repair, predominantly expressed in epidermal keratinocytes, and peaked in the subsequent proliferative phase. TGF-β1 and TGF-β2 induced miR-132 expression in keratinocytes, and transcriptome analysis of these cells revealed that miR-132 regulates a large number of immune response- and cell cycle-related genes. In keratinocytes, miR-132 decreased the production of chemokines and the capability to attract leukocytes by suppressing the NF-κB pathway. Conversely, miR-132 increased activity of the STAT3 and ERK pathways, thereby promoting keratinocyte growth. Silencing of the miR-132 target heparin-binding EGF-like growth factor (HB-EGF) phenocopied miR-132 overexpression in keratinocytes. Using mouse and human ex vivo wound models, we found that miR-132 blockade delayed healing, which was accompanied by severe inflammation and deficient keratinocyte proliferation. Together, our results indicate that miR-132 is a critical regulator of skin wound healing that facilitates the transition from the inflammatory to the proliferative phase.

Hsa-miR-132 inhibits proliferation of hepatic carcinoma cells by targeting YAP

MicroRNAs and Yes-associated protein (YAP) play an important role in the occurrence and development of hepatic carcinomas. However, the interaction between microRNAs and YAP was seldom elucidated. In this study, we showed that miR-132 could target YAP gene by using dual-luciferase reporter system. Further quantitative polymerase chain reaction analysis and western blotting showed that miR-132 could significantly reduce the expression of YAP at mRNA and protein levels. Results of annexin V-fluorescein isothiocyanate, 5-ethynyl-2'-deoxyuridine staining and transwell assays showed that miR-132 significantly promoted the cell apoptosis and effectively inhibited the proliferation and invasion of hepatoma cells. These results indicated that miR-132 could inhibit the growth of hepatoma cells by targeting YAP gene and reducing its expression level. Taken together, results from this study would help us to understand the mechanisms for occurrence and development of hepatic carcinoma and provide new targets for diagnosis and treatment of liver cancer.

Ormeloxifene suppresses desmoplasia and enhances sensitivity of gemcitabine in pancreatic cancer

The management of pancreatic ductal adenocarcinoma (PDAC) is extremely poor due to lack of an efficient therapy and development of chemoresistance to the current standard therapy, gemcitabine. Recent studies implicate the intimate reciprocal interactions between epithelia and underlying stroma due to paracrine Sonic hedgehog (SHH) signaling in producing desmoplasia and chemoresistance in PDAC. Herein, we report for the first time that a nonsteroidal drug, ormeloxifene, has potent anticancer properties and depletes tumor-associated stromal tissue by inhibiting the SHH signaling pathway in PDAC. We found that ormeloxifene inhibited cell proliferation and induced death in PDAC cells, which provoked us to investigate the combinatorial effects of ormeloxifene with gemcitabine at the molecular level. Ormeloxifene caused potent inhibition of the SHH signaling pathway via downregulation of SHH and its related important downstream targets such as Gli-1, SMO, PTCH1/2, NF-κB, p-AKT, and cyclin D1. Ormeloxifene potentiated the antitumorigenic effect of gemcitabine by 75% in PDAC xenograft mice. Furthermore, ormeloxifene depleted tumor-associated stroma in xenograft tumor tissues by inhibiting the SHH cellular signaling pathway and mouse/human collagen I expression. Xenograft tumors treated with ormeloxifene in combination with gemcitabine restored the tumor-suppressor miR-132 and inhibited stromal cell infiltration into the tumor tissues. In addition, invasiveness of tumor cells cocultivated with TGFβ-stimulated human pancreatic stromal cells was effectively inhibited by ormeloxifene treatment alone or in combination with gemcitabine. We propose that ormeloxifene has high therapeutic index and in a combination therapy with gemcitabine, it possesses great promise as a treatment of choice for PDAC/pancreatic cancer.

The Interplay Between miR-148a and DNMT1 Might be Exploited for Pancreatic Cancer Therapy

We discovered the expression level of miR-148a significantly decreased in pancreatic cancer tissues whereas that of DNMT1 increased. In ASPC-1 cancer cells, the overexpression of miR-148a led to a decreased level of DNMT1 and reduced the proliferation and metastasis of ASPC-1 cells. Moreover, the increased expression of miR-148a arrested the UTR methylation of p27, giving rise to an increased level of p27. Interestingly, it was shown that the DNMT1 inhibition enhanced the expression of miR-148a. In vivo studies demonstrated that the tumorigenesis of ASPC-1 was significantly arrested by either the overexpression of miR-148a or the inhibition of DNMT1.

MicroRNAs in Pancreatic Cancer: Involvement in Carcinogenesis and Potential Use for Diagnosis and Prognosis

Pancreatic cancer is one of the most fatal malignancies with increasing incidence and high mortality. Possibilities for early diagnosis are limited and there is currently no efficient therapy. Molecular markers that have been introduced into diagnosis and treatment of other solid tumors remain unreciprocated in this disease. Recent discoveries have shown that certain microRNAs (miRNAs) take part in fundamental molecular processes associated with pancreatic cancer initiation and progression including cell cycle, DNA repair, apoptosis, invasivity, and metastasis. The mechanism involves both positive and negative regulation of expression of protooncogenes and tumor suppressor genes. Various miRNAs are expressed at different levels among normal pancreatic tissue, chronic pancreatitis, and pancreatic cancer and may therefore serve as a tool to differentiate chronic pancreatitis from early stages of cancer. Other miRNAs can indicate the probable course of the disease or determine the survival prognosis. In addition, there is a growing interest directed at the understanding of miRNA-induced molecular mechanisms. The possibility of intervention in the molecular mechanisms of miRNAs regulation could begin a new generation of pancreatic cancer therapies. This review summarizes the recent reports describing functions of miRNAs in cellular processes underlying pancreatic cancerogenesis and their utility in diagnosis, survival prognosis, and therapy.

Vps4A functions as a tumor suppressor by regulating the secretion and uptake of exosomal microRNAs in human hepatoma cells

The deregulation of microRNAs (miRNAs) plays an important role in human hepatocarcinogenesis. In this study, we highlight exosomes as mediators involved in modulating miRNA profiles in hepatocellular carcinoma (HCC) cells. First, we examined the different miRNA expression profiles in HCC cells and HCC cell-derived exosomes. Next, coculture experiments indicated that HCC cell-derived exosomes promoted the cell growth, migration, and invasion of HCC cells and had the ability to shuttle miRNAs to recipient cells. Further, our data showed that Vps4A, a key regulator of exosome biogenesis, was frequently down-regulated in HCC tissues. The reduction of Vps4A in HCC tissues was associated with tumor progression and metastasis. In vitro studies revealed that Vps4A repressed the growth, colony formation, migration, and invasion of HCC cells. We further investigated the role and involvement of Vps4A in suppressing the bioactivity of exosomes and characterized its ability to weaken the cell response to exosomes. By small RNA sequencing, we demonstrated that Vps4A facilitated the secretion of oncogenic miRNAs in exosomes as well as accumulation and uptake of tumor suppressor miRNAs in cells. A subset of Vps4A-associated miRNAs was identified. Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that the phosphatidylinositol-3-kinase/Akt signaling pathway was the most likely candidate pathway for modulation by these miRNAs. Indeed, we proved that the phosphatidylinositol-3-kinase/Akt pathway was inactivated by Vps4A overexpression.

CONCLUSION

Exosome-mediated miRNA transfer is an important mechanism of self-modulation of the miRNA expression profiles in HCC cells, and Vps4A may function as a tumor suppressor, which utilizes exosomes as mediators to regulate the secretion and uptake of miRNAs in hepatoma cells; these observations provide new insights into the development of HCC.

Identification of subgroup-specific miRNA patterns by epigenetic profiling of sporadic and Lynch syndrome-associated colorectal and endometrial carcinoma

Background

Altered expression of microRNAs (miRNAs) commonly accompanies colorectal (CRC) and endometrial carcinoma (EC) development, but the underlying mechanisms and clinicopathological correlations remain to be clarified. We focused on epigenetic mechanisms and aimed to explore if DNA methylation patterns in tumors depend on DNA mismatch repair (MMR) status, sporadic vs. Lynch-associated disease, and geographic origin (Finland vs. Australia). Treatment of cancer cell lines with demethylating agents revealed 109 significantly upregulated miRNAs. Seven met our stringent criteria for possible methylation-sensitive miRNAs and were used to screen patient specimens (205 CRCs and 36 ECs) by methylation-specific multiplex ligation-dependent probe amplification.

Results

Three miRNAs (129-2, 345, and 132) with low methylation levels in normal tissue and frequent hypermethylation in tumors were of particular interest. Hypermethylation of miR-345 and miR-132 associated with MMR deficiency in CRC regardless of geographic origin, and hypermethylation of miR-132 distinguished sporadic MMR-deficient CRC from Lynch-CRC. Finally, hypermethylation of miRNAs stratified 49 endometrial hyperplasias into low-methylator (simple hyperplasia) and high-methylator groups (complex hyperplasia with or without atypia) and suggested that miR-129-2 methylation in particular could serve as a marker of progression in early endometrial tumorigenesis.

Conclusions

Our study identifies miR-345 and miR-132 as novel differentially methylated miRNAs in CRC, thereby facilitating sub-classification of CRC and links miR-129-2 methylation to early endometrial tumorigenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0059-3) contains supplementary material, which is available to authorized users.

Clinical implications of miRNAs in the pathogenesis, diagnosis and therapy of pancreatic cancer

Despite considerable progress being made in understanding pancreatic cancer (PC) pathogenesis, it still remains the 10th most often diagnosed malignancy in the world and 4th leading cause of cancer related deaths in the United States with a five year survival rate of only 6%. The aggressive nature, lack of early diagnostic and prognostic markers, late clinical presentation, and limited efficacy of existing treatment regimens make PC a lethal cancer with high mortality and poor prognosis. Therefore, novel reliable biomarkers and molecular targets are urgently needed to combat this deadly disease. MicroRNAs (miRNAs) are short (19-24 nucleotides) non-coding RNA molecules implicated in the regulation of gene expression at post-transcriptional level and play significant roles in various physiological and pathological conditions. Aberrant expression of miRNAs has been reported in several cancers including PC and is implicated in PC pathogenesis and progression, suggesting their utility in diagnosis, prognosis and therapy. In this review, we summarize the role of several miRNAs that regulate various oncogenes (KRAS) and tumor suppressor genes (p53, p16, SMAD4, etc.) involved in PC development, their prospective roles as diagnostic and prognostic markers and as a therapeutic targets.

MiR-467a is upregulated in radiation-induced mouse thymic lymphomas and regulates apoptosis by targeting Fas and Bax

It has been reported dysregulation of certain microRNAs (miRNAs / miRs) is involved in tumorigenesis. However, the miRNAs associated with radiocarcinogenesis remain undefined. In this study, we validated the upregulation of miR-467a in radiation-induced mouse thymic lymphoma tissues. Then, we investigated whether miR-467a functions as an oncogenic miRNA in thymic lymphoma cells. For this purpose, we assessed the biological effect of miR-467a on thymic lymphoma cells. Using miRNA microarray, we found four miRNAs (miR-467a, miR-762, miR-455 and miR-714) were among the most upregulated (>4-fold) miRNAs in tumor tissues. Bioinformatics prediction suggests miR-467a may potentially regulate apoptosis pathway via targeting Fas and Bax. Consistently, in miR-467a-transfected cells, both proliferation and colony formation ability were significantly increased with decrease of apoptosis rate, while, in miR-467a-knockdown cells, proliferation was suppressed with increase of apoptosis rate, indicating that miR-467a may be involved in the regulation of apoptosis. Furthermore, miR-467a-knockdown resulted in smaller tumors and better prognosis in an in vivo tumor-transplanted model. To explain the mechanism of apoptosis suppression by miR-467a, we explore the expression of candidate target genes (Fas and Bax) in miR-467a-transfected relative to negative control transfected cells using flow cytometry and immunoblotting. Fas and Bax were commonly downregulated in miR-467a-transfected EL4 and NIH3T3 cells, and all of the genes harbored miR-467a target sequences in the 3'UTR of their mRNA. Fas and Bax were actually downregulated in radiation-induced thymic lymphoma tissues, and therefore both were identified as possible targets of miR-467a in thymic lymphoma. To ascertain whether downregulation of Fas and / or Bax is involved in apoptosis suppression by miR-467a, we transfected vectors expressing Fas and Bax into miR-467a-upregulated EL4 cells. Then we found that both Fas- and Bax-overexpression decreased cell viability with increase of apoptosis rate, indicating that downregulation of Fas and Bax may be at least partly responsible for apoptosis suppression by miR-467a. These data suggest that miR-467a may have oncogenic functions in radiation-induced thymic lymphoma cells and that its increased expression may confer a growth advantage on tumor cells via aberrant expression of Fas and Bax.

Upregulation of the miR-212/132 cluster suppresses proliferation of human lung cancer cells

Lung cancer is the leading cause of cancer-related mortality worldwide. microRNAs (miRNAs) are small post-transcriptional regulatory non-coding RNAs that function as oncogenes or tumor suppressors in human cancers. Emerging evidence reveals that deregulation of miRNAs contributes to the progression of human lung cancer, which is the leading cause of cancer-related deaths worldwide. In the present study, we found that upregulation of the miR-212/132 cluster significantly suppressed the growth and focus formation of A549 and H1299 cells. Moreover, forced expression of this cluster conferred radiosensitivity and inhibited the migration of lung cancer cells, whereas downregulation of miR-212/132 reversed the above effects. Furthermore, miR-212/132 overexpression induced cell cycle arrest at the G1/S phase transition of the lung cancer cells, and inhibition of miR-132 and miR-212 abrogated this arrest. In addition, miR-212/132 overexpression increased the percentage of cells undergoing apoptosis. Cells transfected with the miR-212/132 cluster exhibited upregulated p21 expression and reduced cyclin D1 expression. Conversely, cells transfected with the miR-212/132 inhibitor showed reduced expression of p21 and upregulated expression of cyclin D1, suggesting that miR-212/132 may mediate proliferation and cell cycle arrest through p21 and cyclin D1. Our study provides insight into the biological function of the miR-212/132 cluster in lung cancer. The present study may provide a potential therapeutic target for the treatment of lung cancer.

Pathogenetic and diagnostic significance of microRNA deregulation in peripheral T-cell lymphoma not otherwise specified

Peripheral T-cell lymphomas not otherwise specified (PTCLs/NOS) are rare and aggressive tumours whose molecular pathogenesis and diagnosis are still challenging. The microRNA (miRNA) profile of 23 PTCLs/NOS was generated and compared with that of normal T-lymphocytes (CD4+, CD8+, naive, activated). The differentially expressed miRNA signature was compared with the gene expression profile (GEP) of the same neoplasms. The obtained gene patterns were tested in an independent cohort of PTCLs/NOS. The miRNA profile of PTCLs/NOS then was compared with that of 10 angioimmunoblastic T-cell lymphomas (AITLs), 6 anaplastic large-cell lymphomas (ALCLs)/ALK+ and 6 ALCLs/ALK−. Differentially expressed miRNAs were validated in an independent set of 20 PTCLs/NOS, 20 AITLs, 19 ALCLs/ALK− and 15 ALCLs/ALK+. Two hundred and thirty-six miRNAs were found to differentiate PTCLs/NOS from activated T-lymphocytes. To assess which miRNAs impacted on GEP, a multistep analysis was performed, which identified all miRNAs inversely correlated to different potential target genes. One of the most discriminant miRNAs was selected and its expression was found to affect the global GEP of the tumours. Moreover, two sets of miRNAs were identified distinguishing PTCL/NOS from AITL and ALCL/ALK−, respectively. The diagnostic accuracy of this tool was very high (83.54%) and its prognostic value validated.

N-methylnicotinamide and nicotinamide N-methyltransferase are associated with microRNA-1291-altered pancreatic carcinoma cell metabolome and suppressed tumorigenesis

The cell metabolome comprises abundant information that may be predictive of cell functions in response to epigenetic or genetic changes at different stages of cell proliferation and metastasis. An unbiased ultra-performance liquid chromatography-mass spectrometry-based metabolomics study revealed a significantly altered metabolome for human pancreatic carcinoma PANC-1 cells with gain-of-function non-coding microRNA-1291 (miR-1291), which led to a lower migration and invasion capacity as well as suppressed tumorigenesis in a xenograft tumor mouse model. A number of metabolites, including N-methylnicotinamide, involved in nicotinamide metabolism, and l-carnitine, isobutyryl-carnitine and isovaleryl-carnitine, involved in fatty acid metabolism, were elevated in miR-1291-expressing PANC-1. Notably, N-methylnicotinamide was elevated to the greatest extent, and this was associated with a sharp increase in nicotinamide N-methyltransferase (NNMT) mRNA level in miR-1291-expressing PANC-1 cells. In addition, expression of NNMT mRNA was inversely correlated with pancreatic tumor size in the xenograft mouse model. These results indicate that miR-1291-altered PANC-1 cell function is associated with the increase in N-methylnicotinamide level and NNMT expression, and in turn NNMT may be indicative of the extent of pancreatic carcinogenesis.

Upregulation of miR-132 expression in glioma and its clinical significance

miR-132 was found to be overexpressed in glioma; however, its clinical significance has not been investigated. In the present study, we evaluated the association between miR-132 and clinicopathological parameters and prognosis. Quantitative real-time PCR was used to analyze the expression of miR-132 in 113 cases of glioma and 36 cases of normal brain tissues. The association of miR-132 expression with clinicopathological factors and prognosis of glioma patients were analyzed. The expression levels of miR-132 were significantly higher in glioma tissues than that in normal brain tissues (mean ± SD, 4.448 ± 1.857 vs. 1.936 ± 0.543; P < 0.001). The miR-132 expression level was classified as high or low in relation to the median value. High expression of miR-132 was found to significantly correlate with KPS score (P = 0.001); extent of resection (P = 0.009), and WHO grade (P < 0.001). Kaplan-Meier analysis with the log-rank test indicated that high miR-132 expression had a significant impact on overall survival (17.3 vs. 56.2 %; P = 0.04) and progression-free survival (11.7 vs. 50.5 %; P = 0.012). In conclusion, this study identified high miR-132 expression as a biomarker of poor prognosis in patients diagnosed with glioma.

Targeting Btk/Etk of prostate cancer cells by a novel dual inhibitor

Btk and Etk/BMX are Tec-family non-receptor tyrosine kinases. Btk has previously been reported to be expressed primarily in B cells and has an important role in immune responses and B-cell malignancies. Etk has been shown previously to provide a strong survival and metastasis signal in human prostate cancer cells, and to confer androgen independence and drug resistance. While the role of Etk in prostate carcinogenesis is well established, the functions of Btk in prostate cancer have never been investigated, likely due to the perception that Btk is a hematopoietic, but not epithelial, kinase. Herein, we found that Btk is overexpressed in prostate cancer tissues and prostate cancer cells. The level of Btk in prostate cancer tissues correlates with cancer grades. Knockdown of Btk expression selectively inhibits the growth of prostate cancer cells, but not that of the normal prostate epithelial cells, which express very little Btk. Dual inhibition of Btk and Etk has an additive inhibitory effect on prostate cancer cell growth. To explore Btk and Etk as targets for prostate cancer, we developed a small molecule dual inhibitor of Btk and Etk, CTN06. Treatment of PC3 and other prostate cancer cells, but not immortalized prostate epithelial cells with CTN06 resulted in effective cell killing, accompanied by the attenuation of Btk/Etk signals. The killing effect of CTN06 is more potent than that of commonly used inhibitors against Src, Raf/VEGFR and EGFR. CTN06 induces apoptosis as well as autophagy in human prostate cancer cells, and is a chemo-sensitizer for docetaxel (DTX), a standard of care for metastatic prostate cancer patients. CTN06 also impeded the migration of human prostate cancer cells based on a ‘wound healing' assay. The anti-cancer effect of CTN06 was further validated in vivo in a PC3 xenograft mouse model.

MicroRNAs as emerging biomarkers and therapeutic targets for pancreatic cancer

Despite tremendous efforts from scientists and clinicians worldwide, pancreatic adenocarcinoma (PDAC) remains a deadly disease due to the lack of early diagnostic tools and reliable therapeutic approaches. Consequently, a majority of patients (80%) display an advanced disease that results in a low resection rate leading to an overall median survival of less than 6 months. Accordingly, robust markers for the early diagnosis and prognosis of pancreatic cancer, or markers indicative of survival and/or metastatic disease are desperately needed to help alleviate the dismal prognosis of this cancer. In addition, the discovery of new therapeutic targets is mandatory to design effective treatments. In this review, we will highlight the translational studies demonstrating that microRNAs may soon translate into clinical applications as long-awaited screening tools and therapeutic targets for PDAC.

Epithelial and stromal microRNA signatures of columnar cell hyperplasia linking Let-7c to precancerous and cancerous breast cancer cell proliferation

Columnar cell hyperplasia (CCH) is the earliest histologically identifiable breast lesion linked to cancer progression and is characterized by increased proliferation, decreased apoptosis and elevated oestrogen receptor α (ERα) expression. The mechanisms underlying the initiation of these lesions have not been clarified but might involve early and fundamental changes in cancer progression. MiRNAs are key regulators of several biological processes, acting by influencing the post-transcriptional regulation of numerous targets, thus making miRNAs potential candidates in cancer initiation. Here we have defined novel epithelial as well as stromal miRNA signatures from columnar cell hyperplasia lesions compared to normal terminal duct lobular units by using microdissection and miRNA microarrays. Let-7c were among the identified downregulated epithelial miRNAs and its functions were delineated in unique CCH derived cells and breast cancer cell line MCF-7 suggesting anti-proliferative traits potentially due to effects on Myb and ERα. MiR-132 was upregulated in the stroma surrounding CCH compared to stoma surrounding normal terminal duct lobular units (TDLUs), and overexpression of miR-132 in immortalized fibroblasts and in fibroblasts co-cultured with epithelial CCH cells caused substantial expression changes of genes involved in metabolism, DNA damage and cell motility. The miRNA signatures identified in CCH indicate early changes in the epithelial and stromal compartment of CCH and could represent early key alterations in breast cancer progression that potentially could be targeted in novel prevention or treatment schedules.

Role of non-coding RNAs in pancreatic cancer: The bane of the microworld

Our understanding of the mechanisms underlying the development of pancreatic cancer has been greatly advanced. However, the molecular events involved in the initiation and development of pancreatic cancer remain inscrutable. None of the present medical technologies have been proven to be effective in significantly improving early detection or reducing the mortality/morbidity of this disease. Thus, a better understanding of the molecular basis of pancreatic cancer is required for the identification of more effective diagnostic markers and therapeutic targets. Non-coding RNAs (ncRNAs), generally including microRNAs and long non-coding RNAs, have recently been found to be deregulated in many human cancers, which provides new opportunities for identifying both functional drivers and specific biomarkers of pancreatic cancer. In this article, we review the existing literature in the field documenting the significance of aberrantly expressed and functional ncRNAs in human pancreatic cancer, and discuss how oncogenic ncRNAs may be involved in the genetic and epigenetic networks regulating functional pathways that are deregulated in this malignancy, particularly of the ncRNAs’ role in drug resistance and epithelial-mesenchymal transition biological phenotype, with the aim of analyzing the feasibility of clinical application of ncRNAs in the diagnosis and treatment of pancreatic cancer.

DNA methylation, microRNAs, and their crosstalk as potential biomarkers in hepatocellular carcinoma

Epigenetic alterations have been identified as a major characteristic in human cancers. Advances in the field of epigenetics have contributed significantly in refining our knowledge of molecular mechanisms underlying malignant transformation. DNA methylation and microRNA expression are epigenetic mechanisms that are widely altered in human cancers including hepatocellular carcinoma (HCC), the third leading cause of cancer related mortality worldwide. Both DNA methylation and microRNA expression patterns are regulated in developmental stage specific-, cell type specific- and tissue-specific manner. The aberrations are inferred in the maintenance of cancer stem cells and in clonal cell evolution during carcinogenesis. The availability of genome-wide technologies for DNA methylation and microRNA profiling has revolutionized the field of epigenetics and led to the discovery of a number of epigenetically silenced microRNAs in cancerous cells and primary tissues. Dysregulation of these microRNAs affects several key signalling pathways in hepatocarcinogenesis suggesting that modulation of DNA methylation and/or microRNA expression can serve as new therapeutic targets for HCC. Accumulative evidence shows that aberrant DNA methylation of certain microRNA genes is an event specifically found in HCC which correlates with unfavorable outcomes. Therefore, it can potentially serve as a biomarker for detection as well as for prognosis, monitoring and predicting therapeutic responses in HCC.

Epigenetics and pancreatic cancer: Pathophysiology and novel treatment aspects

An improvement in pancreatic cancer treatment represents an urgent medical goal. Late diagnosis and high intrinsic resistance to conventional chemotherapy has led to a dismal overall prognosis that has remained unchanged during the past decades. Increasing knowledge about the molecular pathogenesis of the disease has shown that genetic alterations, such as mutations of K-ras, and especially epigenetic dysregulation of tumor-associated genes, such as silencing of the tumor suppressor p16^ink4a, are hallmarks of pancreatic cancer. Here, we describe genes that are commonly affected by epigenetic dysregulation in pancreatic cancer via DNA methylation, histone acetylation or miRNA (microRNA) expression, and review the implications on pancreatic cancer biology such as epithelial-mesenchymal transition, morphological pattern formation, or cancer stem cell regulation during carcinogenesis from PanIN (pancreatic intraepithelial lesions) to invasive cancer and resistance development. Epigenetic drugs, such as DNA methyltransferases or histone deactylase inhibitors, have shown promising preclinical results in pancreatic cancer and are currently in early phases of clinical development. Combinations of epigenetic drugs with established cytotoxic drugs or targeted therapies are promising approaches to improve the poor response and survival rate of pancreatic cancer patients.

miR-132 inhibits colorectal cancer invasion and metastasis via directly targeting ZEB2

AIM: To investigate the biological role and underlying mechanism of miR-132 in colorectal cancer (CRC) progression and invasion.

METHODS: Quantitative RT-PCR analysis was used to examine the expression levels of miR-132 in five CRC cell lines (SW480, SW620, HCT116, HT29 and LoVo) and a normal colonic cell line NCM460, as well as in tumor tissues with or without metastases. The Kaplan-Meier method was used to analyze the prognostic significance of miR-132 in CRC patients. The biological effects of miR-132 were assessed in CRC cell lines using the transwell assay. Quantitative RT-PCR and western blot analyses were employed to evaluate the expression of miR-132 targets. The regulation of ZEB2 by miR-132 was confirmed using the luciferase activity assay.

RESULTS: miR-132 was significantly down-regulated in the CRC cell lines compared with the normal colonic cell line (P < 0.05), as well as in the CRC tissues with distant metastases compared with the tissues without metastases (10.52 ± 4.69 vs 23.11 ± 7.84) (P < 0.001). Down-regulation of miR-132 was associated with tumor size (P = 0.016), distant metastasis (P = 0.002), and TNM stage (P = 0.020) in CRC patients. Kaplan-Meier survival curve analysis indicated that patients with low expression of miR-132 tended to have worse disease-free survival than patients with high expression of miR-132 (P < 0.001). Moreover, ectopic expression of miR-132 markedly inhibited cell invasion (P < 0.05) and the epithelial-mesenchymal transition (EMT) in CRC cell lines. Further investigation revealed ZEB2, an EMT regulator, was a downstream target of miR-132.

CONCLUSION: Our study indicated that miR-132 plays an important role in the invasion and metastasis of CRC.

USF-1 inhibition protects against oxygen-and-glucose-deprivation-induced apoptosis via the downregulation of miR-132 in HepG2 cells

Upstream stimulatory factor 1 (USF-1) is an important transcription factor that participates in glucose metabolism and tumorigenesis. The aim of the current study was to explore the regulatory mechanism of USF-1 in HepG2 cells exposed to oxygen and glucose deprivation (OGD). After the establishment of the OGD model in HepG2 cells, we determined that the cells treated with OGD exhibited a high apoptotic rate and that the introduction of siRNA against USF-1 protected the cells from OGD-induced apoptosis. The miRNA microarray results demonstrated that a set of miRNAs were deregulated in the cells transfected with USF-1 siRNA, and the set of downregulated miRNAs included a novel miRNA, miR-132. Further analyses indicated that miR-132 overexpression inhibits the protective roles of USF-1 siRNA in OGD-induced apoptosis. We also identified several binding sites for USF-1 in the miR-132 promoter. The silencing of USF-1 resulted in a reduction in miR-132 expression, and USF-1 overexpression increased the expression of this miRNA. Our study indicated that the silencing of USF-1 plays protective roles in OGD-induced apoptosis through the downregulation of miR-132, which indicates that the silencing of USF-1 may be a therapeutic strategy for the promotion of cancer cell survival under OGD conditions.

MiR-132 suppresses the migration and invasion of lung cancer cells via targeting the EMT regulator ZEB2

MicroRNAs (miRNAs) are small, non-coding RNAs which can function as oncogenes or tumor suppressor genes in human cancers. Emerging evidence reveals that deregulation of miRNAs contributes to the human non-small cell lung cancer (NSCLC). In the present study, we demonstrated that the expression levels of miR-132 were dramatically decreased in examined NSCLC cell lines and clinical NSCLC tissue samples. Then, we found that introduction of miR-132 significantly suppressed the migration and invasion of lung cancer cells in vitro, suggesting that miR-132 may be a novel tumor suppressor. Further studies indicated that the EMT-related transcription factor ZEB2 was one direct target genes of miR-132, evidenced by the direct binding of miR-132 with the 3' untranslated region (3' UTR) of ZEB2. Further, miR-132 could decrease the expression of ZEB2 at the levels of mRNA and protein. Notably, the EMT marker E-cadherin or vimentin, a downstream of ZEB2, was also down-regulated or up-regulated upon miR-132 treatment. Additionally, over-expressing or silencing ZEB2 was able to elevate or inhibit the migration and invasion of lung cancer cells, parallel to the effect of miR-132 on the lung cancer cells. Meanwhile, knockdown of ZEB2 reversed the enhanced migration and invasion mediated by anti-miR-132. These results indicate that miR-132 suppresses the migration and invasion of NSCLC cells through targeting ZEB2 involving the EMT process. Thus, our finding provides new insight into the mechanism of NSCLC progression. Therapeutically, miR-132 may serve as a potential target in the treatment of human lung cancer.

The expression and clinical significance of miR-132 in gastric cancer patients

Background and objective

miR-132 plays a role in regulating neuronal morphology and cellular excitability. Little is known about the effects of miR-132 in cancer. The aim of this study is to evaluate the expression of miR-132 and its clinical significance in gastric cancer.

Methods

Cancerous tissues and corresponding normal tissues from 79 patients with gastric cancer were examined for the expression of miR-132 using quantitative PCR and the association between miR-132 expression levels and clinicopathological factors and prognosis was analyzed.

Results

In 79 clinical samples of gastric cancer patients, miR-132 expression levels in cancer tissues were significantly higher than those in the corresponding normal tissues (P = 0.001). Higher expression levels of miR-132 were associated with more frequent lymph node metastasis (P = 0.033), more lymphatic tumor emboli (P = 0.007), and more advanced stage (P = 0.016). Additionally, expression of miR-132 was an independent prognostic factor for overall survival (P = 0.020).

Conclusion

miR-132 could serve as an efficient prognostic factor for gastric cancer patients.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/8168577241196050

Sp1-mediated microRNA-182 expression regulates lung cancer progression

Our recent study indicated that overexpression of Sp1 enhances the proliferation of lung cancer cells, while represses metastasis. In this study, we found that the transcriptional activity of FOXO3 was increased, but its protein levels decreased following Sp1 expression. Sp1 increased expression of miR-182, which was then recruited to the 3'-untranslated region of FOXO3 mRNA to silence its translational activity. Knockdown of miR-182 inhibited lung cancer cells growth, but enhanced the invasive and migratory abilities of these cells through increased N-cadherin expression. Repression of FOXO3 expression in the miR-182 knockdown cells partially reversed this effect, suggesting that miR-182 promotes cancer cell growth and inhibits cancer metastatic activity by regulating the expression of FOXO3. The expression of several cancer metastasis-related genes such as ADAM9, CDH9 and CD44 was increased following miR-182 knockdown. In conclusion, in the early stages of lung cancer progression, Sp1 stimulates miR-182 expression, which in turn decreases FOXO3 expression. This stimulates proliferation and tumor growth. In the late stages, Sp1 and miR-182 decline, thus increasing FOXO3 expression, which leads to lung metastasis.

Therapeutic potential of histone deacetylase inhibitors in pancreatic cancer

Pancreatic cancer is a devastating disease with a dismal prognosis. Surgical resection is the only curative option but is heavily hampered by delayed diagnosis. Due to few therapeutic treatments available, novel and efficacious therapy is urgently needed. Histone deacetylase inhibitors (HDACIs) are emerging as a prominent class of therapeutic agents for pancreatic cancer and have exhibited significant anticancer potential with negligible toxicity in preclinical studies. Clinical evaluations of HDACIs are currently underway. HDACIs as monotherapy in solid tumors have proven less effective than hematological malignancies, the combination of HDACIs with other anticancer agents have been assessed for advanced pancreatic cancer. In this review, we describe the molecular mechanism underpin the anticancer effect of HDACIs in pancreatic cancer and summarize the recent advances in the rationale for the combination strategies incorporating HDACIs. In addition, we discuss the importance of identifying predictors of response to HDACI-based therapy.

MicroRNAs (miRNAs) as biomarker(s) for prognosis and diagnosis of gastrointestinal (GI) cancers

Gastrointestinal (GI) cancers remain one of the most common malignancies and are the second common cause of cancer deaths worldwide. The limited effectiveness of therapy for patients with advanced stage and recurrent disease is a reflection of an incomplete understanding of the molecular basis of GI carcinogenesis. Major advancements have improved our understanding of pathology and pathogenesis of GI cancers, but high mortality rates, unfavorable prognosis and lack of clinical predictive biomarkers provide an impetus to investigate new sensitive and specific diagnostic and prognostic markers for GI cancers. MicroRNAs (miRNAs) are short (19-24 nucleotides) noncoding RNA molecules that regulate gene expression at the posttranscriptional level thus playing an important role in modulating various biological processes including, but not limited to developmental processes, proliferation, apoptosis, metabolism, differentiation, epithelial-mechenchymal transition and are involved in the initiation and progression of various human cancers. Unique miRNA expression profiles have been observed in various cancer types at different stages, suggesting their potential as diagnostic and prognostic biomarkers. Due to their tumor-specific and tissue-specific expression profiles, stability, robust clinical assays for detection in serum as well as in formalin-fixed tissue samples, miRNAs have emerged as attractive candidates for diagnostic and prognostic applications. This review summarizes recent research supporting the utility of miRNAs as novel diagnostic and prognostic tools for GI cancers.

miR-132 targeting cyclin E1 suppresses cell proliferation in osteosarcoma cells

In this study, we investigated the roles of miR-132 in tumor growth of osteosarcoma. We found that overexpression of miR-132 significantly suppressed in vitro cell proliferation and in vivo tumor growth. In addition, miR-132 overexpression induced G1/S cell cycle arrest of osteosarcoma cells. Further study showed that miR-132 could interact with the 3'-untranslated region of cyclin E1 (CCNE1) gene and repress its expression. Re-expression of CCNE1 (without the 3'UTR) could partially abrogate the miR-132-induced cell proliferation inhibition. Of significance, contrary to CCNE1, expression level of miR-132 was significantly lower in osteosarcoma tissues than in the adjacent normal tissues. Taken together, these results indicate that miR-132 functions as a tumor suppressor in osteosarcoma and that its suppressive effects are mediated chiefly by repressing CCNE1 expression.