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At least 847 records · Page 47Linked to original sources
PubMed2026

Dual Mechanisms Underlie the Repression of Repressor Element 1-Silencing Transcription Factor Expression in Lung Neuroendocrine Carcinoma Cells.

Recent advances in genetic analysis have led to further subtyping of small-cell lung carcinoma (SCLC). The major subtypes of SCLC are the achaete-scute family bHLH transcription factor 1 (ASCL1)-predominant (SCLC-A), neuronal differentiation 1 (NEUROD1)-predominant (SCLC-N), and POU class 2 homeobox 3 (POU2F3) (SCLC-P) subtypes. SCLC-A and SCLC-N tumors express chromogranin A (CHGA) and synaptophysin (SYP), but SCLC-P tumors do not. Large-cell neuroendocrine carcinoma, another type of neuroendocrine carcinoma (NEC), also frequently expresses CHGA and SYP. Because CHGA and SYP expression is controlled by a transrepressor, repressor element 1-silencing transcription factor (REST), the mechanisms underlying REST suppression in NEC were investigated, with a focus on miRNAs and epigenetics, to determine the causes of the differences in the expression of CHGA and SYP between SCLC-A/N and SCLC-P cells. The results showed that miR-375-3p, which was induced by ASCL1 and NEUROD1, repressed REST expression by binding to the 3'-untranslated region of REST mRNA. Bisulfite sequencing and experiments using a DNA methyltransferase inhibitor, a histone deacetylase inhibitor, and chromatin immunoprecipitation-based quantitative PCR revealed that promoter/enhancer hypermethylation and histone deacetylation causes REST gene inactivation in SCLC-A/N. These phenomena were also observed in a large-cell neuroendocrine carcinoma cell line that expressed high levels of ASCL1 and NEUROD1. Taken together, these findings suggest that NEC has dual repressive effects on REST expression, resulting in strict regulation of the expression of CHGA, SYP, and other REST-controlled neuronal/neuroendocrine-specific genes.

Humans↗
PubMed2026

Comparative transcriptome analysis reveals ncRNA-mediated regulatory networks associated with muscle crispiness in grass carp.

Non-coding RNAs (ncRNAs) have been demonstrated to be involved in muscle development and to function as key regulators. However, the molecular mechanism underlying muscle crispiness in grass carp (GC) remains poorly understood, and whether these ncRNAs are involved in its regulation is still unknown. In the current investigation, differentially expressed (DE) RNAs (including lncRNAs, circRNAs, miRNAs, and mRNAs) were identified; concomitantly, target genes prediction was conducted, and functional and signaling pathway enrichment analyses were performed. Pathways related to muscle crispiness were identified, and the competitive endogenous RNA (ceRNA) (lncRNA/circRNA-miRNA-mRNA) regulatory network was further constructed. The results showed that a total of 126 DE-lncRNAs, 17 DE-circRNAs, 329 DE-miRNAs, and 442 DE-mRNAs were identified in muscle tissues of both the GC and crisp grass carp (CGC). GO and KEGG enrichment analyses revealed that target genes of DE-ncRNAs were significantly enriched in signaling pathways, including structural constituents of muscle, apoptosis, oxidative phosphorylation, and regulation of actin cytoskeleton, suggesting that these pathways may be involved in muscle texture remodeling. Subsequently, DE-RNAs enriched in related pathways were identified, and a core ceRNA regulation network comprising 3 lncRNAs, 4 circRNAs, 3 miRNAs, and 17 mRNAs was constructed. Additionally, 10 DE-RNAs from randomly selected groups were validated by qRT-PCR. Our findings not only provide scientific evidence elucidating the molecular mechanisms underlying muscle crispiness in GC but also establish a foundation for studying changes in muscle textural qualities across other fish species.

Animals↗
PubMed2021

ERBB3 overexpression due to miR-205 inactivation confers sensitivity to FGF, metabolic activation, and liability to ERBB3 targeting in glioblastoma.

In glioblastoma (GBM), the most frequent and lethal brain tumor, therapies suppressing recurrently altered signaling pathways failed to extend survival. However, in patient subsets, specific genetic lesions can confer sensitivity to targeted agents. By exploiting an integrated model based on patient-derived stem-like cells, faithfully recapitulating the original GBMs in vitro and in vivo, here, we identify a human GBM subset (∼9% of all GBMs) characterized by ERBB3 overexpression and nuclear accumulation. ERBB3 overexpression is driven by inheritable promoter methylation or post-transcriptional silencing of the oncosuppressor miR-205 and sustains the malignant phenotype. Overexpressed ERBB3 behaves as a specific signaling platform for fibroblast growth factor receptor (FGFR), driving PI3K/AKT/mTOR pathway hyperactivation, and overall metabolic upregulation. As a result, ERBB3 inhibition by specific antibodies is lethal for GBM stem-like cells and xenotransplants. These findings highlight a subset of patients eligible for ERBB3-targeted therapy.

Antibodies↗
PubMed2006

Involvement of human micro-RNA in growth and response to chemotherapy in human cholangiocarcinoma cell lines.

BACKGROUND & AIMS: Micro-RNA (miRNA) are endogenous regulatory RNA molecules that modulate gene expression. Alterations in miRNA expression can contribute to tumor growth by modulating the functional expression of critical genes involved in tumor cell proliferation or survival. Our aims were to identify specific miRNA involved in the regulation of cholangiocarcinoma growth and response to chemotherapy. METHODS: miRNA expression in malignant and nonmalignant human cholangiocytes was assessed using a microarray. Expression of selected miRNA and their precursors was evaluated by Northern blots and real-time polymerase chain reaction, respectively. The effect of selected miRNA on cell growth and response to chemotherapy was assessed using miRNA-specific antisense oligonucleotides to decrease miRNA expression or with precursor miRNA to increase cellular expression. RESULTS: miRNA expression was markedly different in malignant cholangiocytes, with decreased expression of many miRNA compared with nonmalignant cells. A cluster of miRNA, including miR-320, miR-200b, miR-21, miR-23a, miR-141, miR-27a, and miR-34a, were expressed in all cell lines. MiR-21, miR-141, and miR-200b were highly over-expressed in malignant cholangiocytes. Inhibition of miR-21 and miR-200b increased sensitivity to gemcitabine, whereas inhibition of miR-141 decreased cell growth. Treatment of tumor cell xenografts with systemic gemcitabine altered the expression of a significant number of miRNA. miR-21 modulates gemcitabine-induced apoptosis by phosphatase and tensin homolog deleted on chromosome 10 (PTEN)-dependent activation of PI 3-kinase signaling. Potential target genes that were modulated by selected miRNA were identified. CONCLUSIONS: Alterations in miRNA expression contribute to tumor growth and response to chemotherapy. Aberrantly expressed miRNA or their targets will provide mechanistic insight and therapeutic targets for cholangiocarcinoma.

Animals↗
PubMed2006

Dicer function is essential for lung epithelium morphogenesis.

DICER is a key enzyme that processes microRNA and small interfering RNA precursors into their short mature forms, enabling them to regulate gene expression. Only a single Dicer gene exists in the mouse genome, and it is broadly expressed in developing tissues. Dicer-null mutants die before gastrulation. Therefore, to study Dicer function in the later event of lung formation, we inactivated it in the mouse lung epithelium using a Dicer conditional allele and the Sonic Hedgehogcre (Shhcre) allele. Branching arrests in these mutant lungs, although epithelial growth continues in distal domains that are expanded compared with normal samples. These defects result in a few large epithelial pouches in the mutant lung instead of numerous fine branches present in a normal lung. Significantly, the initial phenotypes are apparent before an increase in epithelial cell death is observed, leading us to propose that Dicer plays a specific role in regulating lung epithelial morphogenesis independent of its requirement in cell survival. In addition, we found that the expression of Fgf10, a key gene involved in lung development, is up-regulated and expanded in the mesenchyme of Dicer mutant lungs. Previous studies support the hypothesis that precise localization of FGF10 in discrete sites of the lung mesenchyme serves as a chemoattractant for the outgrowth of epithelial branches. The aberrant Fgf10 expression may contribute to the Dicer morphological defects. However, the mechanism by which DICER functions in the epithelium to influence Fgf10 expression in the mesenchyme remains unknown.

Animals↗
PubMed2005

Potential roles for short RNAs in lymphocytes.

RNA interference (RNAi) is an ancient and evolutionarily conserved process. In some eukaryotes, RNAi silences parasitic genetic elements. In plants, RNAi serves as an immune system against RNA viruses and transgenes and in worms, RNAi silences transposons. In mammals, RNAi has yet unknown functions. However, emerging roles for short RNAs and the factors that interact with them in other eukaryotes include chromatin modification, DNA deletion and DNA methylation, which may provide clues to the roles for short RNA function in mammals. For example, antigen receptor expression in lymphocytes is a highly regulated process and although much is known about chromatin modification and DNA deletion in the immune system, several molecular details of chromatin regulation remain elusive. This review compares emerging roles for short RNA function to processes required for antigen receptor expression in mammalian lymphocytes and predicts that short RNAs direct events required for successful lymphocyte-restricted gene expression.

Animals↗
PubMed2001

An abundant class of tiny RNAs with probable regulatory roles in Caenorhabditis elegans.

Two small temporal RNAs (stRNAs), lin-4 and let-7, control developmental timing in Caenorhabditis elegans. We find that these two regulatory RNAs are members of a large class of 21- to 24-nucleotide noncoding RNAs, called microRNAs (miRNAs). We report on 55 previously unknown miRNAs in C. elegans. The miRNAs have diverse expression patterns during development: a let-7 paralog is temporally coexpressed with let-7; miRNAs encoded in a single genomic cluster are coexpressed during embryogenesis; and still other miRNAs are expressed constitutively throughout development. Potential orthologs of several of these miRNA genes were identified in Drosophila and human genomes. The abundance of these tiny RNAs, their expression patterns, and their evolutionary conservation imply that, as a class, miRNAs have broad regulatory functions in animals.

Animals↗
PubMed2004

Argonaute2 is the catalytic engine of mammalian RNAi.

Gene silencing through RNA interference (RNAi) is carried out by RISC, the RNA-induced silencing complex. RISC contains two signature components, small interfering RNAs (siRNAs) and Argonaute family proteins. Here, we show that the multiple Argonaute proteins present in mammals are both biologically and biochemically distinct, with a single mammalian family member, Argonaute2, being responsible for messenger RNA cleavage activity. This protein is essential for mouse development, and cells lacking Argonaute2 are unable to mount an experimental response to siRNAs. Mutations within a cryptic ribonuclease H domain within Argonaute2, as identified by comparison with the structure of an archeal Argonaute protein, inactivate RISC. Thus, our evidence supports a model in which Argonaute contributes "Slicer" activity to RISC, providing the catalytic engine for RNAi.

Amino Acid Sequence↗
PubMed2006

A method for similarity search of genomic positional expression using CAGE.

With the advancement of genome research, it is becoming clear that genes are not distributed on the genome in random order. Clusters of genes distributed at localized genome positions have been reported in several eukaryotes. Various correlations have been observed between the expressions of genes in adjacent or nearby positions along the chromosomes depending on tissue type and developmental stage. Moreover, in several cases, their transcripts, which control epigenetic transcription via processes such as transcriptional interference and genomic imprinting, occur in clusters. It is reasonable that genomic regions that have similar mechanisms show similar expression patterns and that the characteristics of expression in the same genomic regions differ depending on tissue type and developmental stage. In this study, we analyzed gene expression patterns using the cap analysis gene expression (CAGE) method for exploring systematic views of the mouse transcriptome. Counting the number of mapped CAGE tags for fixed-length regions allowed us to determine genomic expression levels. These expression levels were normalized, quantified, and converted into four types of descriptors, allowing the expression patterns along the genome to be represented by character strings. We analyzed them using dynamic programming in the same manner as for sequence analysis. We have developed a novel algorithm that provides a novel view of the genome from the perspective of genomic positional expression. In a similarity search of expression patterns across chromosomes and tissues, we found regions that had clusters of genes that showed expression patterns similar to each other depending on tissue type. Our results suggest the possibility that the regions that have sense-antisense transcription show similar expression patterns between forward and reverse strands.

Algorithms↗
PubMed2004

The Microprocessor complex mediates the genesis of microRNAs.

MicroRNAs (miRNAs) are a growing family of small non-protein-coding regulatory genes that regulate the expression of homologous target-gene transcripts. They have been implicated in the control of cell death and proliferation in flies, haematopoietic lineage differentiation in mammals, neuronal patterning in nematodes and leaf and flower development in plants. miRNAs are processed by the RNA-mediated interference machinery. Drosha is an RNase III enzyme that was recently implicated in miRNA processing. Here we show that human Drosha is a component of two multi-protein complexes. The larger complex contains multiple classes of RNA-associated proteins including RNA helicases, proteins that bind double-stranded RNA, novel heterogeneous nuclear ribonucleoproteins and the Ewing's sarcoma family of proteins. The smaller complex is composed of Drosha and the double-stranded-RNA-binding protein, DGCR8, the product of a gene deleted in DiGeorge syndrome. In vivo knock-down and in vitro reconstitution studies revealed that both components of this smaller complex, termed Microprocessor, are necessary and sufficient in mediating the genesis of miRNAs from the primary miRNA transcript.

Cell Line↗
PubMed2006

Genomic evolution of Hox gene clusters.

The family of Hox genes, which number 4 to 48 per genome depending on the animal, control morphologies on the main body axis of nearly all metazoans. The conventional wisdom is that Hox genes are arranged in chromosomal clusters in colinear order with their expression patterns on the body axis. However, recent evidence has shown that Hox gene clusters are fragmented, reduced, or expanded in many animals-findings that correlate with interesting morphological changes in evolution. Hox gene clusters also contain many noncoding RNAs, such as intergenic regulatory transcripts and evolutionarily conserved microRNAs, some of whose developmental functions have recently been explored.

Animals↗
PubMed2006

Epigenetic activation of tumor suppressor microRNAs in human cancer cells.

MicroRNAs (miRNAs) are small noncoding RNAs that function as endogenous post-transcriptional silencers of target genes. miRNAs are expressed in a tissue specific manner and play important roles in cell proliferation, apoptosis and differentiation during animal development. Recent studies have shown a distinct connection between aberrant expression of miRNAs and the development of cancer, suggesting that miRNAs can be potential therapeutic targets. Our recent study has shown that some miRNAs are controlled by epigenetic alterations such as DNA methylation and histone modification in human cancer cells. Activation of tumor suppressor miRNAs by chromatin modifying drugs may cause downregulation of target oncogenes and could be a novel strategy for the prevention and treatment of human cancer.

Epigenesis, Genetic↗
PubMed2026

Tumor Suppressive Role of Hsa-miR-328-3p in Colon Cancer by Regulating EN2.

BACKGROUND/AIM: Colon cancer is a prevalent and life-threatening malignancy worldwide. Recent studies have focused on how microRNAs (miRNAs) act as post-transcriptional modulators in colon cancer progression. Herein, this study aimed to identify the impact of miRNAs that are decreased in colon cancer and to investigate their regulatory mechanisms. MATERIALS AND METHODS: Differentially expressed miRNAs (DEmiRNAs) and genes (DEGs) were identified through analysis of miRNA sequencing and RNA sequencing data from normal and tumor tissues in The Cancer Genome Atlas (TCGA). Expression levels were validated by quantitative polymerase chain reaction (qPCR) in both tissues and cell lines. Functional effects of miRNAs were evaluated by assessing cell viability, proliferation, migration, and invasion following transfection with miRNA mimics. RESULTS: Analysis of miRNA-seq data from the TCGA database identified hsa-miR-328-3p as a miRNA consistently downregulated across all stages of colon cancer. This downregulation was independently validated in colon cancer patient tissues by qPCR. Functional assays demonstrated that enforced expression of hsa-miR-328-3p significantly reduced cell viability, proliferation, migration, and invasion in colon cancer cell lines, supporting its tumor-suppressive role. To elucidate the molecular mechanism underlying these inhibitory effects, target gene analysis was performed. Engrailed homeobox 2 (EN2) was identified as a potential target of hsa-miR-328-3p, and a dual-luciferase assay confirmed that EN2 is directly regulated by hsa-miR-328-3p. CONCLUSION: Collectively, these findings indicate that hsa-miR-328-3p is frequently downregulated in colon cancer and functions as a tumor suppressor by negatively regulating its target gene, EN2, thereby contributing to colon cancer malignancy. EN2 may serve as a potential diagnostic biomarker for colon cancer, while restoration of hsa-miR-328-3p expression represents a promising therapeutic strategy. Further studies are needed to clarify the precise molecular mechanisms linking the hsa-miR-328-3p/EN2 axis to colon cancer progression.

Humans↗