Reduced miR-31 and let-7 maintain the balance between differentiation and quiescence in lung cancer stem-like side population cells

Recent studies have indicated that side population (SP) cells, which are an enriched source of cancer stem cells (CSCs), drive and maintain many types of human malignancies. SP cells have distinguishing biological characteristics and are thought to contribute to metastasis, therapy resistance, and tumor recurrence. In the present study, the miRNA expression profiles of SP cells and non-SP cells were compared using miRNA array analysis. Both let-7 and miR-31 were significantly down-regulated in SP cells compared to non-SP cells. The results were confirmed by real-time PCR. Engineered repression of miR-31 caused marked repression of both lung cancer SP cell and non-SP cell growth in vitro. In contrast, engineered repression of let-7 caused marked promotion of both lung cancer SP and non-SP cells growth in vitro. Cell cycle studies further revealed that reduced miR-31 could inhibit SP cell proliferation by a cell cycle arrest in the G0/G1 phase, whereas reduced let-7 induced SP cell proliferation by accelerating G1/S phase transition. Notably, reduced miR-31 prevented SP cell differentiation, whereas reduced let-7 promoted SP cell differentiation under differentiation conditions. These findings indicate that reduced miR-31 and let-7 are involved in maintaining the balance between differentiation and quiescence in SP cells.     

直肠腺瘤和直肠癌中 microRNA 表达谱差异

目的对直肠癌miRNA表达谱进行初步研究,以期发现在直肠癌发生过程中与直肠腺瘤miRNA的差异表达谱,并预测可能受其调控的靶基因。方法选择2011年1～3月于解放军第306医院肠镜检查的直肠癌及直肠腺瘤进行检测,筛选直肠癌、直肠腺瘤组织差异表达的miRNA,并运用生物信息软件分析其靶基因。结果通过miRNAs芯片检测,发现直肠腺癌与直肠腺瘤相比,上调的miRNA 34种,下调8种。预测ZFHX4可能为miR-375的靶基因,预测SMAD2等可能为miR-18a的靶基因。结论与直肠腺瘤相比,直肠腺癌有其特异的miRNA表达谱,miRNA在直肠癌的发生中可能起到重要作用。     

Intratumoral heterogeneity of microRNA expression in breast cancer

Profiling studies have identified specific microRNA (miRNA) signatures in malignant tumors including breast cancer. Our aim was to assess intratumoral heterogeneity in miRNA expression levels within primary breast cancers and between axillary lymph node metastases from the same patient. Specimens of 16 primary breast cancers were sampled in 8-10 distinct locations including the peripheral, intermediate, and central tumor zones, as well as two to five axillary lymph node metastases (n = 9). Total RNA was extracted from 132 paraffin-embedded samples, and the expression of miR-10b, miR-210, miR-31, and miR-335 was assessed as well as the reproducibility of RNA extraction and miRNA analysis by quantitative RT-PCR. Considerable intratumoral heterogeneity existed for all four miRNAs within primary breast cancers (CV 40%). No significant differences within (CV 34%) or between different tumor zones (CV 33%) were found. A similar variation in miRNA expression was observed between corresponding lymph node metastases (mean CV 40%). In comparison, the variation among different patients showed a CV of 80% for primary tumors and 103% for lymph node metastases. Both miRNA extraction procedures and quantitative RT-PCR showed high reproducibility (CV ≤ 2%). Thus, the intratumoral heterogeneity of miRNA expression in breast cancers can lead to significant sampling bias. Assessment of breast cancer miRNA profiles may require sampling at several different tumor locations and of several tumor-involved lymph nodes when deriving miRNA expression profiles of metastases.     

MicroRNA-31 initiates lung tumorigenesis and promotes mutant KRAS-driven lung cancer

MicroRNA (miR) are important regulators of gene expression, and aberrant miR expression has been linked to oncogenesis; however, little is understood about their contribution to lung tumorigenesis. Here, we determined that miR-31 is overexpressed in human lung adenocarcinoma and this overexpression independently correlates with decreased patient survival. We developed a transgenic mouse model that allows for lung-specific expression of miR-31 to test the oncogenic potential of miR-31 in the lung. Using this model, we observed that miR-31 induction results in lung hyperplasia, followed by adenoma formation and later adenocarcinoma development. Moreover, induced expression of miR-31 in mice cooperated with mutant KRAS to accelerate lung tumorigenesis. We determined that miR-31 regulates lung epithelial cell growth and identified 6 negative regulators of RAS/MAPK signaling as direct targets of miR-31. Our study distinguishes miR-31 as a driver of lung tumorigenesis that promotes mutant KRAS-mediated oncogenesis and reveals that miR-31 directly targets and reduces expression of negative regulators of RAS/MAPK signaling.     

Targeting miR-21 for the Therapy of Pancreatic Cancer

Despite tremendous efforts worldwide from clinicians and cancer scientists, pancreatic ductal adenocarcinoma (PDA) remains a deadly disease for which no cure is available. Recently, microRNAs (miRNAs) have emerged as key actors in carcinogenesis and we demonstrated that microRNA-21 (miR-21), oncomiR is expressed early during PDA. In the present study, we asked whether targeting miR-21 in human PDA-derived cell lines using lentiviral vectors (LVs) may impede tumor growth. We demonstrated that LVs-transduced human PDA efficiently downregulated miR-21 expression, both in vitro and in vivo. Consequently, cell proliferation was strongly inhibited and PDA-derived cell lines died by apoptosis through the mitochondrial pathway. In vivo, miR-21 depletion stopped the progression of a very aggressive model of PDA, to induce cell death by apoptosis; furthermore, combining miR-21 targeting and chemotherapeutic treatment provoked tumor regression. We demonstrate herein for the first time that targeting oncogenic miRNA strongly inhibit pancreatic cancer tumor growth both in vitro and in vivo. Because miR-21 is overexpressed in most human tumors; therapeutic delivery of miR-21 antagonists may still be beneficial for a large number of cancers for which no cure is available.     

MicroRNA-182 drives metastasis of primary sarcomas by targeting multiple genes

Metastasis causes most cancer deaths, but is incompletely understood. MicroRNAs can regulate metastasis, but it is not known whether a single miRNA can regulate metastasis in primary cancer models in vivo. We compared the expression of miRNAs in metastatic and nonmetastatic primary mouse sarcomas and found that microRNA-182 (miR-182) was markedly overexpressed in some tumors that metastasized to the lungs. By utilizing genetically engineered mice with either deletion of or overexpression of miR-182 in primary sarcomas, we discovered that deletion of miR-182 substantially decreased, while overexpression of miR-182 considerably increased, the rate of lung metastasis after amputation of the tumor-bearing limb. Additionally, deletion of miR-182 decreased circulating tumor cells (CTCs), while overexpression of miR-182 increased CTCs, suggesting that miR-182 regulates intravasation of cancer cells into the circulation. We identified 4 miR-182 targets that inhibit either the migration of tumor cells or the degradation of the extracellular matrix. Notably, restoration of any of these targets in isolation did not alter the metastatic potential of sarcoma cells injected orthotopically, but the simultaneous restoration of all 4 targets together substantially decreased the number of metastases. These results demonstrate that a single miRNA can regulate metastasis of primary tumors in vivo by coordinated regulation of multiple genes.     

Cigarette smoke mediates epigenetic repression of miR-487b during pulmonary carcinogenesis

MicroRNAs are critical mediators of stem cell pluripotency, differentiation, and malignancy. Limited information exists regarding microRNA alterations that facilitate initiation and progression of human lung cancers. In this study, array techniques were used to evaluate microRNA expression in normal human respiratory epithelia and lung cancer cells cultured in the presence or absence of cigarette smoke condensate (CSC). Under relevant exposure conditions, CSC significantly repressed miR-487b. Subsequent experiments demonstrated that miR-487b directly targeted SUZ12, BMI1, WNT5A, MYC, and KRAS. Repression of miR-487b correlated with overexpression of these targets in primary lung cancers and coincided with DNA methylation, de novo nucleosome occupancy, and decreased H2AZ and TCF1 levels within the miR-487b genomic locus. Deoxy-azacytidine derepressed miR-487b and attenuated CSC-mediated silencing of miR-487b. Constitutive expression of miR-487b abrogated Wnt signaling, inhibited in vitro proliferation and invasion of lung cancer cells mediated by CSC or overexpression of miR-487b targets, and decreased growth and metastatic potential of lung cancer cells in vivo. Collectively, these findings indicate that miR-487b is a tumor suppressor microRNA silenced by epigenetic mechanisms during tobacco-induced pulmonary carcinogenesis and suggest that DNA demethylating agents may be useful for activating miR-487b for lung cancer therapy.     

A systematic analysis of predicted MiR-31-targets identifies a diagnostic and prognostic signature for lung cancer

Introduction

Recent studies have shown that miR-31 could play a potential role as diagnostic and prognostic biomarkers of several cancers including lung cancer. The aim of this study is to globally summarize the predicting targets of miR-31 and their potential function, pathways and networks, which are involved in the biological behavior of lung cancer.

Methods

We have conducted the natural language processing (NLP) analysis to identify lung cancer-related molecules in our previous work. In this study, miR-31 targets predicted by combinational computational methods. All target genes were characterized by gene ontology (GO), pathway and network analysis. In addition, miR-31 targets analysis were integrated with the results from NLP analysis, followed by hub genes interaction analysis.

Result

We identified 27 hub genes by the final integrative analysis and suggested that miR-31 may be involved in the initiation, progression and treatment response of lung cancer through cell cycle, cytochrome P450 pathway, metabolic pathways, apoptosis, chemokine signaling pathway, MAPK signaling pathway, as well as others.

Conclusion

Our data may help researchers to predict the molecular mechanisms of miR-31 in the molecular mechanism of lung cancer comprehensively. Moreover, the present data indicate that the interaction of miR-31 targets may be promising candidates as biomarkers for the diagnosis, prognosis and personalized therapy of lung cancer.     

MicroRNAs 的失调在高转移肝细胞癌中的作用

目的：筛选在高转移肝细胞癌中差异表达的miRNAs图谱。方法利用Agilent miRNA array芯片技术平台分析比较了4对高转移肝细胞患者的癌组织样本与其相对应的正常组织之间的差异miRNAs。通过生物信息学方法分析了这些候选差异 miRNAs。结果与正常组织相比,我们在高转移肝细胞癌中发现了22个失调的miRNAs,其中包括13个上调的miRNAs（miR-200a、miR-425、miR-221和miR-20b等）和9个下调的miRNAs（miR-762、miR-638和miR-1305等）。其中,一些miRNAs已经被报道与肿瘤的发生和转移相关。靶基因预测分析也表明,这些基因在肿瘤的发生和转移过程中扮演着重要的作用。结论我们在高转移肝细胞癌中发现了一些表达失调的 miRNAs,生物信息学分析也发现这些 miRNAs 在肿瘤的发生和转移中发挥着重要的作用,可以作为肝细胞癌在临床治疗上的一个新的肿瘤标志物。     

Therapeutic Effects of MicroRNA-582-5p and -3p on the Inhibition of Bladder Cancer Progression

Many reports have indicated that the abnormal expression of microRNAs (miRNAs) is associated with the progression of disease and have identified miRNAs as attractive targets for therapeutic intervention. However, the bifunctional mechanisms of miRNA guide and passenger strands in RNA interference (RNAi) therapy have not yet been clarified. Here, we show that miRNA (miR)-582-5p and -3p, which are strongly decreased in high-grade bladder cancer clinical samples, regulate tumor progression in vitro and in vivo. Significantly, the overexpression of miR-582-5p or -3p reduced the proliferation and invasion of UM-UC-3 human bladder cancer cells. Furthermore, transurethral injections of synthetic miR-582 molecule suppressed tumor growth and metastasis in an animal model of bladder cancer. Most interestingly, our study revealed that both strands of miR-582-5p and -3p suppressed the expression of the same set of target genes such as protein geranylgeranyltransferase type I beta subunit (PGGT1B), leucine-rich repeat kinase 2 (LRRK2) and DIX domain containing 1 (DIXDC1). Knockdown of these genes using small interfering RNA (siRNA) resulted in the inhibition of cell growth and invasiveness of UM-UC-3. These findings uncover the unique regulatory pathway involving tumor suppression by both strands of a single miRNA that is a potential therapeutic target in the treatment of invasive bladder cancer.     

Systemic Delivery of Tumor Suppressor microRNA Mimics Using a Neutral Lipid Emulsion Inhibits Lung Tumors in Mice

MicroRNAs (miRNAs) are emerging as potential cancer therapeutics, but effective delivery mechanisms to tumor sites are a roadblock to utility. Here we show that systemically delivered, synthetic miRNA mimics in complex with a novel neutral lipid emulsion are preferentially targeted to lung tumors and show therapeutic benefit in mouse models of lung cancer. Therapeutic delivery was demonstrated using mimics of the tumor suppressors, microRNA-34a (miR-34a) and let-7, both of which are often down regulated or lost in lung cancer. Systemic treatment of a Kras-activated autochthonous mouse model of non-small cell lung cancer (NSCLC) led to a significant decrease in tumor burden. Specifically, mice treated with miR-34a displayed a 60% reduction in tumor area compared to mice treated with a miRNA control. Similar results were obtained with the let-7 mimic. These findings provide direct evidence that synthetic miRNA mimics can be systemically delivered to the mammalian lung and support the promise of miRNAs as a future targeted therapy for lung cancer.     

MicroRNA as a novel drug target for cancer therapy

INTRODUCTION: MicroRNAs (miRNAs), a class of small, regulatory and non-coding RNA molecules, display aberrant expression patterns and functional abnormalities in all kinds of human diseases including cancers. As important emerging modulators in cellular pathways, miRNAs play a key role in tumorigenesis. Correcting these miRNA deficiencies by either up-regulating or down-regulating miRNA function may provide a therapeutic benefit. AREAS COVERED: We herein provide a brief review of miRNA in the following aspects: their possible role of miRNA as oncogenes or tumor suppressors in the pathogenesis of cancer, the abnormally expressed miRNAs in various types of human common cancers, novel drug targets and therapeutic tools for diagnosis, prognosis and treatments of human cancers was also discussed. Finally, we comment on the difficulties and challenges of miRNAs in clinical practice, and the bright perspective for future application. EXPERT OPINION: Targeting of these ectopically miRNAs could provide an important diagnostic or therapeutic strategy for human cancer in the future.     

MicroRNAs as New Players in the Genomic Galaxy and Disease Puzzles

MicroRNAs (miRNAs) are a large family of short, single‐stranded, highly conserved noncoding RNAs involved in gene regulation that can regulate gene expression through sequence‐specific base pairing with target messenger RNAs (mRNAs). miRNAs have been implicated in the development of a wide variety of cancers as well as heart disease and other diseases. This review describes the role of miRNAs in human disease, methodology for evaluating miRNA gene expression, and the potential role of miRNAs as therapeutic agents and targets for the treatment of disease.     

MicroRNA as a novel drug target for cancer therapy

Introduction: MicroRNAs (miRNAs), a class of small, regulatory and non-coding RNA molecules, display aberrant expression patterns and functional abnormalities in all kinds of human diseases including cancers. As important emerging modulators in cellular pathways, miRNAs play a key role in tumorigenesis. Correcting these miRNA deficiencies by either up-regulating or down-regulating miRNA function may provide a therapeutic benefit.

Areas covered: We herein provide a brief review of miRNA in the following aspects: their possible role of miRNA as oncogenes or tumor suppressors in the pathogenesis of cancer, the abnormally expressed miRNAs in various types of human common cancers, novel drug targets and therapeutic tools for diagnosis, prognosis and treatments of human cancers was also discussed. Finally, we comment on the difficulties and challenges of miRNAs in clinical practice, and the bright perspective for future application.

Expert opinion: Targeting of these ectopically miRNAs could provide an important diagnostic or therapeutic strategy for human cancer in the future.     

MicroRNAs regulate methionine adenosyltransferase 1A expression in hepatocellular carcinoma

MicroRNAs (miRNAs) and methionine adenosyltransferase 1A (MAT1A) are dysregulated in hepatocellular carcinoma (HCC), and reduced MAT1A expression correlates with worse HCC prognosis. Expression of miR-664, miR-485-3p, and miR-495, potential regulatory miRNAs of MAT1A, is increased in HCC. Knockdown of these miRNAs individually in Hep3B and HepG2 cells induced MAT1A expression, reduced growth, and increased apoptosis, while combined knockdown exerted additional effects on all parameters. Subcutaneous and intraparenchymal injection of Hep3B cells stably overexpressing each of this trio of miRNAs promoted tumorigenesis and metastasis in mice. Treatment with miRNA-664 (miR-664), miR-485-3p, and miR-495 siRNAs reduced tumor growth, invasion, and metastasis in an orthotopic liver cancer model. Blocking MAT1A induction significantly reduced the antitumorigenic effect of miR-495 siRNA, whereas maintaining MAT1A expression prevented miRNA-mediated enhancement of growth and metastasis. Knockdown of these miRNAs increased total and nuclear level of MAT1A protein, global CpG methylation, lin-28 homolog B (Caenorhabditis elegans) (LIN28B) promoter methylation, and reduced LIN28B expression. The opposite occurred with forced expression of these miRNAs. In conclusion, upregulation of miR-664, miR-485-3p, and miR-495 contributes to lower MAT1A expression in HCC, and enhanced tumorigenesis may provide potential targets for HCC therapy.