MicroRNA miR-145 inhibits proliferation, invasiveness, and stem cell phenotype of an in vitro endometriosis model by targeting multiple cytoskeletal elements and pluripotency factors

miRNAsong: a web-based tool for generation and testing of miRNA sponge constructs in silico

MicroRNA (miRNA) sponges are RNA transcripts containing multiple high-affinity binding sites that associate with and sequester specific miRNAs to prevent them from interacting with their target messenger (m)RNAs. Due to the high specificity of miRNA sponges and strong inhibition of target miRNAs, these molecules have become increasingly applied in miRNA loss-of-function studies. However, improperly designed sponge constructs may sequester off-target miRNAs; thus, it has become increasingly important to develop a tool for miRNA sponge construct design and testing. In this study, we introduce microRNA sponge generator and tester (miRNAsong), a freely available web-based tool for generation and in silico testing of miRNA sponges. This tool generates miRNA sponge constructs for specific miRNAs and miRNA families/clusters and tests them for potential binding to miRNAs in selected organisms. Currently, miRNAsong allows for testing of sponge constructs in 219 species covering 35,828 miRNA sequences. Furthermore, we also provide an example, supplemented with experimental data, of how to use this tool. Using miRNAsong, we designed and tested a sponge for miR-145 inhibition, and cloned the sequence into an inducible lentiviral vector. We found that established cell lines expressing miR-145 sponge strongly inhibited miR-145, thus demonstrating the usability of miRNAsong tool for sponge generation. URL: http://www.med.muni.cz/histology/miRNAsong/.

A plausible role for actin gamma smooth muscle 2 (ACTG2) in small intestinal neuroendocrine tumorigenesis

BACKGROUND

Small intestinal neuroendocrine tumors (SI-NETs) originate from the enterochromaffin cells in the ileum and jejunum. The knowledge about genetic and epigenetic abnormalities is limited. Low mRNA expression levels of actin gamma smooth muscle 2 (ACTG2) have been demonstrated in metastases relative to primary SI-NETs. ACTG2 and microRNA-145 (miR-145) are aberrantly expressed in other cancers and ACTG2 can be induced by miR-145. The aim of this study was to investigate the role of ACTG2 in small intestinal neuroendocrine tumorigenesis.

METHODS

Protein expression was analyzed in SI-NETs (n = 24) and in enterochromaffin cells by immunohistochemistry. The cell line CNDT2.5 was treated with the histone methyltransferase inhibitor 3-deazaneplanocin A (DZNep), the selective EZH2 inhibitor EPZ-6438, or 5-aza-2'-deoxycytidine, a DNA hypomethylating agent. Cells were transfected with ACTG2 expression plasmid or miR-145. Western blotting analysis, quantitative RT-PCR, colony formation- and viability assays were performed. miR-145 expression levels were measured in tumors.

RESULTS

Eight primary tumors and two lymph node metastases displayed variable levels of positive staining. Fourteen SI-NETs and normal enterochromaffin cells stained negatively. Overexpression of ACTG2 significantly inhibited CNDT2.5 cell growth. Treatment with DZNep or transfection with miR-145 induced ACTG2 expression (>10-fold), but no effects were detected after treatment with EPZ-6438 or 5-aza-2'-deoxycytidine. DZNep also induced miR-145 expression. SI-NETs expressed relatively low levels of miR-145, with reduced expression in metastases compared to primary tumors.

CONCLUSIONS

ACTG2 is expressed in a fraction of SI-NETs, can inhibit cell growth in vitro, and is positively regulated by miR-145. Theoretical therapeutic strategies based on these results are discussed.

Syndecan-4 expression is upregulated in endometriosis and contributes to an invasive phenotype

OBJECTIVE

To study the expression and function of syndecan-4 in endometriosis.

DESIGN

Histopathological investigation of eutopic endometrium and experimental laboratory study on a cell line derived from epithelial endometriotic cells (12Z).

SETTING

University hospital laboratory.

PATIENT(S)

One hundred six women (62 controls/44 endometriosis) from the IVF center of Münster University Hospital aged 23-44 undergoing Pipelle biopsy and diagnostic exploratory laparoscopy.

INTERVENTION(S)

Eutopic endometrial tissue was investigated by immunohistochemistry for the expression of syndecan-4. The human endometriotic cell line 12Z was transiently transfected with syndecan-4 small interfering RNA and investigated for changes in cell behavior.

MAIN OUTCOME MEASURE(S)

Syndecan-4 expression in eutopic endometrium was evaluated immunohistochemically in endometrial glands and stroma. Scoring results were correlated with the stages of the menstrual cycle and presence or absence of endometriosis. Quantitative polymerase chain reaction was used to measure syndecan-4-dependent expression changes of MMP2, MMP3, MMP9, Rac1, and ATF2. Altered cell behavior was monitored by matrigel invasion assays and cell viability assays.

RESULT(S)

Syndecan-4 expression was significantly higher in the glands and stroma of patients with endometriosis compared with controls, whereas no menstrual cycle-dependent expression was observed. In 12Z cells, syndecan-4 depletion did not affect cell viability but resulted in a significantly reduced matrigel invasiveness and reduced expression of the small GTPase Rac1, the transcription factor ATF-2, and MMP3.

CONCLUSION(S)

The upregulation of syndecan-4 in the eutopic endometrium of endometriosis patients may facilitate the pathogenetic process by promoting invasive cell growth via Rac1, MMP3, and ATF-2.

Optimization of a cationic liposome-based gene delivery system for the application of miR-145 in anticancer therapeutics

In order to improve the delivery efficiency of microRNA (miRNA or miR)-145, the present study examined several factors which may affect cationic liposome (CL)-based transfection, including the hydration medium used for the preparation of liposomes, the quantity of the plasmid, the molar ratio of N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP)/cholesterol (chol), or DOTAP/chol, and the weight ratio of DOTAP/DNA. In order to enhance the transfection efficiency, protamine was selected as a DNA-condensing agent to form liposome‑protamine‑DNA (LPD) ternary complexes. An agarose gel retardation assay was used to examine the DNA binding affinity of the CLs. Following transfection, GFP fluorescence images were captured and flow cytometry was performed to determine the transfection efficiency. Furthermore, an MTT assay was performed to determine the cytotoxicity of the liposome complexes. The final optimal conditions were as follows: 5% glucose as the hydration medium, a molar ratio of DOTAP/chol at 3:1 for the preparation of CLs, a weight ratio of DOTAP/protamine/DNA of 3:0.5:1, with 8 µg plasmid added for the preparation of the LPD complexes. In vitro, the LPD complexes exhibited an enhanced transfection efficiency and low cytotoxicity, which indicated that the presented LPD vector enhanced the transfection efficiency of the CLs. The HepG2 cells were found to have the lowest expression levels of miR‑145 out of the cell lines tested (A549, BGC-823, HepG2, HeLa, LoVo and MCF-7). Following the transient transfection of the HepG2 cells with miR‑145, the results revealed that the overexpression of miR‑145 inhibited the proliferation of the HepG2 cells and downregulated the expression of cyclin-dependent kinase 6 (CDK6), cyclinD1, c-myc, and Sp1 transcription factor (Sp1). In conclusion, in this study, we optimized a liposome‑based delivery system for the efficient delivery of miR‑145 into cancer cells. This may provide a foundation for further research into the use of miR‑145 in anticancer therapeutics.

miRNAs as new molecular insights into inflammatory bowel disease: Crucial regulators in autoimmunity and inflammation

Inflammatory bowel disease (IBD) is characterized by chronic relapsing inflammatory disorders of the gastrointestinal tract, and includes two major phenotypes: ulcerative colitis and Crohn’s disease. The pathogenesis of IBD is not fully understood as of yet. It is believed that IBD results from complicated interactions between environmental factors, genetic predisposition, and immune disorders. miRNAs are a class of small non-coding RNAs that can regulate gene expression by targeting the 3′-untranslated region of specific mRNAs for degradation or translational inhibition. miRNAs are considered to play crucial regulatory roles in many biologic processes, such as immune cellular differentiation, proliferation, and apoptosis, and maintenance of immune homeostasis. Recently, aberrant expression of miRNAs was revealed to play an important role in autoimmune diseases, including IBD. In this review, we discuss the current understanding of how miRNAs regulate autoimmunity and inflammation by affecting the differentiation, maturation, and function of various immune cells. In particular, we focus on describing specific miRNA expression profiles in tissues and peripheral blood that may be associated with the pathogenesis of IBD. In addition, we summarize the opportunities for utilizing miRNAs as new biomarkers and as potential therapeutic targets in IBD.

microRNA miR-200b affects proliferation, invasiveness and stemness of endometriotic cells by targeting ZEB1, ZEB2 and KLF4

Endometriosis is characterized by growth of endometrial tissue at ectopic locations. Down-regulation of microRNA miR-200b is observed in endometriosis and malignant disease, driving tumour cells towards an invasive state by enhancing epithelial-to-mesenchymal transition (EMT). miR-200b up-regulation may inhibit EMT and invasive growth in endometriosis. To study its functional impact on the immortalized endometriotic cell line 12Z, the stromal cell line ST-T1b, and primary endometriotic stroma cells, a transient transfection approach with microRNA precursors was employed. Expression of bioinformatically predicted targets of miR-200b was analysed by qPCR. The cellular phenotype was monitored by Matrigel invasion assays, digital-holographic video microscopy and flow cytometry. qPCR revealed significant down-regulation of ZEB1 (P < 0.05) and ZEB2 (P < 0.01) and an increase in E-cadherin (P < 0.01). miR-200b overexpression decreased invasiveness (P < 0.0001) and cell motility (P < 0.05). In contrast, cell proliferation (P < 0.0001) and the stemness-associated side population phenotype (P < 0.01) were enhanced following miR-200b transfection. These properties were possibly due to up-regulation of the pluripotency-associated transcription factor KLF4 (P < 0.05) and require attention when considering therapeutic strategies. In conclusion, up-regulation of miR-200b reverts EMT, emerging as a potential therapeutic approach to inhibit endometriotic cell motility and invasiveness.

Non-coding RNAs in Uterine Development, Function and Disease

The major function of the uterus is to accept and provide a suitable environment for an embryo, ultimately leading the birth of offspring and successful propagation of the species. For this occur, there must be precise coordination of hormonal signalling within both the endometrial and myometrial components of this organ. Non-coding RNAs, specifically, microRNAs (miRNAs) have been shown to be essential for normal uterine development and function. Within this organ, miRNAs are proposed to fine-tune the actions of the female steroid hormones estradiol and progesterone. Not surprising, mis-expression of miRNAs has been documented in diseases of the endometrium and myometrium such as endometriosis and leiomyomas, respectively. In this chapter, I will review the current understanding on the role, regulation and function of non-coding RNAs focusing on miRNAs in both the normal physiology of the endometrium and myometrium as well as in pathologies of these tissues, namely endometriosis and leiomyomas.

SYBR Gold Fluorescence Quenching is a Sensitive Probe of Chitosan-microRNA Interactions

Competitive dye displacement titration has previously been used to characterize chitosan-DNA interactions using ethidium bromide. In this work, we aim to develop a fast and reliable method using SYBR Gold as a fluorescent probe to evaluate the binding affinity between ssRNA and chitosan. The interaction of chitosan with ssRNA was investigated as a function of temperature, molecular weight and degree of acetylation of chitosan, using competitive dye displacement titrations with fluorescence quenching. Affinity constants are reported, showing the high sensitivity of the interaction to the degree of acetylation of chitosan and barely dependent on the molecular weight. We propose that the mechanism of SYBR Gold fluorescence quenching is governed by both static and dynamic quenching.

Physicochemical and biological characterization of chitosan-microRNA nanocomplexes for gene delivery to MCF-7 breast cancer cells

Cancer gene therapy requires the design of non-viral vectors that carry genetic material and selectively deliver it with minimal toxicity. Non-viral vectors based on cationic natural polymers can form electrostatic complexes with negatively-charged polynucleotides such as microRNAs (miRNAs). Here we investigated the physicochemical/biophysical properties of chitosan-hsa-miRNA-145 (CS-miRNA) nanocomplexes and the biological responses of MCF-7 breast cancer cells cultured in vitro. Self-assembled CS-miRNA nanocomplexes were produced with a range of (+/-) charge ratios (from 0.6 to 8) using chitosans with various degrees of acetylation and molecular weight. The Z-average particle diameter of the complexes was <200 nm. The surface charge increased with increasing amount of chitosan. We observed that chitosan induces the base-stacking of miRNA in a concentration dependent manner. Surface plasmon resonance spectroscopy shows that complexes formed by low degree of acetylation chitosans are highly stable, regardless of the molecular weight. We found no evidence that these complexes were cytotoxic towards MCF-7 cells. Furthermore, CS-miRNA nanocomplexes with degree of acetylation 12% and 29% were biologically active, showing successful downregulation of target mRNA expression in MCF-7 cells. Our data, therefore, shows that CS-miRNA complexes offer a promising non-viral platform for breast cancer gene therapy.

MiR-183 Regulates ITGB1P Expression and Promotes Invasion of Endometrial Stromal Cells

We applied in the previous study miRNA microarray screening analysis to identify several differentially expressed miRNAs, including miR-183 in normal, eutopic, and ectopic endometrium. Knockdown of miR-183 expression induced the invasiveness and inhibition of apoptosis in endometrial stromal cells. The current study aims to identify the miR-183 targets with relevance to cell functions in endometrial stromal cells, to verify the interaction of miR-183 with its target genes, and to confirm the role of miR-183 in the process of endometriosis. Using microarray analysis, we identified 27 differentially expressed genes (19 were upregulated and 8 downregulated), from which we selected 4 downregulated genes (ITGB1, AMIGO2, VAV3, and PSEN2) based on GO databases for functional analysis and significant pathway analysis. Western blotting analyses showed that integrin β1 (ITGB1), but not AMIGO2, was affected by miR-183 overexpression, whereas no protein expression of VAV3 and PSEN2 was detected. Luciferase reporter assay verified that ITGB1 is a target gene of miR-183. Moreover, we found that ITGB1 is overexpressed in the endometrium of endometriosis patients. Furthermore, overexpression of ITGB1 rescued the repressive effects of miR-183 on the invasiveness of endometrial stromal cells. These findings, together with the fact that ITGB1 is a critical factor for cell adhesion and invasiveness, suggest that miR-183 may be involved in the development of endometriosis by regulating ITGB1 in endometrial stromal cells.

The Krüppel-like factors in female reproductive system pathologies

Female reproductive tract pathologies arise largely from dysregulation of estrogen and progesterone receptor signaling, leading to aberrant cell proliferation, survival, and differentiation. The signaling pathways orchestrated by these nuclear receptors are complex, require the participation of many nuclear proteins serving as key binding partners or targets, and involve a range of paracrine and autocrine regulatory circuits. The members of the Krüppel-like factor (KLF) family of transcription factors are ubiquitously expressed in reproductive tissues and have been increasingly implicated as critical co-regulators and integrators of steroid hormone actions. Herein, we explore the involvement of KLF family members in uterine pathology, describe their currently known molecular mechanisms, and discuss their potential as targets for therapeutic intervention.

MicroRNA-133a inhibits proliferation and invasion, and induces apoptosis in gastric carcinoma cells via targeting fascin actin-bundling protein 1

Fascin actin-bundling protein 1 (FSCN1) is associated with tumor progression. In addition, deregulation of the expression of FSCN1 has been observed in certain types of cancer. However, the detailed role of FSCN1 in gastric cancer remains to be elucidated. In the present study, downregulation of microRNA (miR)-133a and upregulation of FSCN1 were both observed in gastric cancer tissues and cell lines. Functional studies have revealed that miR-133a is able to bind to the 3'-untranslated region of FSCN1 mRNA, and overexpression of miR-133a causes downregulation of FSCN1 expression, while downregulation of miR-133a leads to an increased FSCN1 expression in gastric cancer cells. Furthermore, overexpression of miR-133a inhibited proliferation and invasion, but promoted apoptosis of gastric cancer cells, which may be reversed by upregulation of FSCN1. By contrast, downregulation of miR-133a enhanced proliferation and invasion, but suppressed apoptosis in gastric cancer cells. In conclusion, the anti-oncogenic activity of miR-133a may involve the inhibition of the target gene FSCN1. The present study suggested that miR-133a may be a potential therapeutic target in the treatment of gastric cancer.

MiR-145 suppresses embryo-epithelial juxtacrine communication at implantation by modulating maternal IGF1R

Successful implantation requires the synchronization of viable embryonic development with endometrial receptivity. The mechanisms allowing for the initiation of crosstalk between the embryo and the endometrium remain elusive; however, recent studies have revealed that there are alterations in endometrial microRNAs (miRs) in women suffering repeated implantation failure and that one of the altered miRs is miR-145. We assessed the role of miR-145 and its target IGF1R, in early implantation. miR-145 overexpression and IGF1R knockdown were achieved in Ishikawa endometrial cells. Quantitative PCR, western blotting and 3'UTR luciferase reporter assays confirmed that IGF1R is a direct target of miR-145 in the endometrium. Attachment of mouse embryos or IGF1-coated beads to endometrial epithelial cells was used to study the effects of altered miR-145 and/or IGF1R expression on early implantation events. miR-145 overexpression or specific reduction of IGF1R impaired attachment in both cases. An IGF1R target protector prevented the miR-145-mediated reduction in IGF1R and reversed the effect of miR-145 overexpression on attachment. The data demonstrate that miR-145 influences embryo attachment by reducing the level of IGF1R in endometrium.

Enhanced miR-210 expression promotes the pathogenesis of endometriosis through activation of signal transducer and activator of transcription 3

STUDY QUESTION

What are the roles of the microRNA miR-210-an miRNA that is up-regulated in endometriotic cyst stromal cells (ECSCs)-in the pathogenesis of endometriosis?

SUMMARY ANSWER

Up-regulated miR-210 expression in ECSCs is involved in their proliferation, resistance to apoptosis and angiogenesis through signal transducer and activator of transcription (STAT) 3.

WHAT IS KNOWN ALREADY

In the pathogenesis of endometriosis, a number of roles for microRNAs (miRNAs) are becoming apparent.

STUDY DESIGN, SIZE, DURATION

ECSCs and normal endometrial stromal cells (NESCs) were isolated from ovarian endometriotic tissues (patients aged 24-40 years undergoing salpingo-oophorectomy or evisceration for the treatment of ovarian endometriotic cysts, n = 10) and the eutopic endometrial tissues without endometriosis (premenopausal patients aged 35-45 years undergoing hysterectomies for subserousal leiomyoma, n = 13), respectively.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We used a global gene expression microarray technique to identify downstream targets of miR-210, and we assessed the functions of miR-210 in the pathogenesis of endometriosis by using the miR-210-transfected NESCs.

MAIN RESULTS AND THE ROLE OF CHANCE

Gene expression microarray analysis revealed that one of the key target molecules of miR-210 is STAT3. In the NESCs, in comparison to the control, miR-210 transfection resulted in the induction of cell proliferation (P < 0.0005), the production of vascular endothelial cell growth factor (VEGF) (P < 0.0005) and the inhibition of apoptosis (P < 0.05) through STAT3 activation [increased levels of mRNA (P < 0.0005), and protein (P < 0.005)]. In the ECSCs, inhibitors of STAT3 inhibited the cell proliferation and VEGF production (P < 0.05), and induced the apoptosis of these cells (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

The roles of aberrant miR-210 expression were investigated only in the stromal component of ectopic and eutopic endometrium. Control endometrial tissues were obtained from premenopausal patients who had subserosal leiomyoma and NESC gene expression patterns may be altered in these women. Furthermore, the effects of STAT3 inhibitors were evaluated only in ECSCs and not in NESCs.

WIDER IMPLICATIONS OF THE FINDINGS

The present findings indicate that miR-210 induces NESCs to differentiate into the endometriotic phenotype and we speculate that up-regulated miR-210 expression in ECSCs is involved in the creation of the endometriosis-specific cellular dysfunctions through epigenetic mechanisms. The data indicate that STAT3 inhibitors may be promising candidates for the treatment of endometriosis.

STUDY FUNDING/COMPETING INTERESTS

This work was supported in part by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (no. 13237327 to K.N., no. 25861500 to Y.K. and no. 23592407 to H.N.). There are no conflicts of interest to declare.

Double-negative feedback loop between ZEB2 and miR-145 regulates epithelial-mesenchymal transition and stem cell properties in prostate cancer cells

The invasion and metastasis of tumors are triggered by an epithelial to mesenchymal transition (EMT), which is regulated by microRNAs (miRNAs). EMT also promotes malignant tumor progression and the maintenance of the stem cell property, which endows cancer cells with the capabilities of self-renewal and immortalized proliferation. The transcriptional repressor zinc-finger E-box binding homeobox 2 (ZEB2), as an EMT activator, might be an important promoter of metastasis in some tumors. Here, we report that ZEB2 directly represses the transcription of miR-145, which is a strong repressor of EMT. In turn, ZEB2 is also a direct target of miR-145. Further, our findings show that the downregulation of ZEB2 not only represses invasion, migration, EMT, and the stemness of prostate cancer (PCa) cells, but also suppresses the capability of PC-3 cells to invade bone in vivo. Importantly, the expression level of ZEB2 as revealed by immunohistochemical analysis is positively correlated to bone metastasis, the serum free PSA level, the total PSA level, and the Gleason score in PCa patients and is negatively correlated with miR-145 expression in primary PCa specimens. Thus, our findings demonstrate a double-negative feedback loop between ZEB2 and miR-145 and indicate that the ZEB2/miR-145 double-negative feedback loop plays a significant role in the control of EMT and stem cell properties during the bone metastasis of PCa cells. These results suggest that the double-negative feedback loop between ZEB2 and miR-145 contributes to PCa progression and metastasis and might have therapeutic relevance for the bone metastasis of PCa.

Noncoding RNAs in cancer and cancer stem cells

In recent years, it has become increasingly apparent that noncoding RNAs (ncRNA) are of crucial importance for human cancer. The functional relevance of ncRNAs is particularly evident for microRNAs (miRNAs) and long noncoding RNAs (lncRNAs). miRNAs are endogenously expressed small RNA sequences that act as post-transcriptional regulators of gene expression and have been extensively studied for their roles in cancers, whereas lncRNAs are emerging as important players in the cancer paradigm in recent years. These noncoding genes are often aberrantly expressed in a variety of human cancers. However, the biological functions of most ncRNAs remain largely unknown. Recently, evidence has begun to accumulate describing how ncRNAs are dysregulated in cancer and cancer stem cells, a subset of cancer cells harboring self-renewal and differentiation capacities. These studies provide insight into the functional roles that ncRNAs play in tumor initiation, progression, and resistance to therapies, and they suggest ncRNAs as attractive therapeutic targets and potentially useful diagnostic tools.

TAGLN expression is upregulated in NF1-associated malignant peripheral nerve sheath tumors by hypomethylation in its promoter and subpromoter regions

Neurofibromatosis type 1 (NF1) caused by NF1 gene mutation is a commonly inherited autosomal dominant disorder. Malignant peripheral nerve sheath tumors (MPNSTs), a type of aggressive sarcoma, are a major cause of mortality in NF1 patients. The malignant transformation of benign plexiform neurofibromas (PNs) to MPNSTs is a marked peculiarity in NF1 patients, yet the pathogenesis remains poorly understood. We found that an actin-associated protein transgelin (SM22) was highly expressed in NF1-deficient MPNST tissues compared to NF1-deficient PN tissues using immunohistological staining and primary cultured MPNST cells in western blot analysis. We further found that this transgelin upregulation was caused by increased transcriptional expression of the TAGLN gene encoding transgelin. Comparison of DNA methylation values in the promoter and subpromoter regions of the TAGLN gene in three types of NF1-deficient primary-cultured cells, derived from an NF1 patient's normal phenotype, a benign PN and MPNST tissues, revealed that the TAGLN gene was hypomethylated in the MPNST cells. Next, to determine the functional role of transgelin in MPNST pathogenesis, we manipulated the TAGLN gene expression and investigated the alteration of the RAS-mitogen-activated protein kinase (MAPK) signaling pathway in the normal-phenotypic and malignant tumor cells. The downregulation of TAGLN expression in NF1-deficient MPNST tumor cells through the treatment of the small interfering RNA resulted in a decrease in the RAS activation (GTP-RAS) and the downstream ERK1/2 activation (phosphorylated ERK1/2), while the overexpression of TAGLN in normal-phenotypic NF1-deficient cells caused an increase in RAS and ERK1/2 activation. These results indicate that upregulation of transgelin caused by hypomethylation of the TAGLN gene is closely involved in tumor progression in NF1.

Small but sturdy: small RNAs in cellular memory and epigenetics

Cell identities can be stable over a long time due to a “cellular memory” of expression profiles achieved through epigenetic mechanisms. In this review, Stuwe et al. describe recent studies demonstrating that short noncoding RNAs can also provide molecular signals that define epigenetic states of cells, leading to transgenerational epigenetic inheritance.

Cells in multicellular organisms have distinct identities characterized by their profiles of expressed genes. Cell identities can be stable over a long time and through multiple cellular divisions but are also responsive to extracellular signals. Since the DNA sequence is identical in all cells, a “cellular memory” of expression profiles is achieved by what are defined as epigenetic mechanisms. Two major molecular principles—networks of transcription factors and maintenance of cis-chromatin modifications—have been implicated in maintaining cellular memory. Here we describe recent studies demonstrating that short noncoding RNAs can also provide molecular signals that define epigenetic states of cells. Small RNAs can act independently or cooperate with chromatin modifications to achieve long-lasting effects necessary for cellular memory and transgenerational inheritance.

Posttranscriptional Regulation of Intestinal Epithelial Tight Junction Barrier by RNA-binding Proteins and microRNAs

Intestinal epithelial tight junctions (TJs) are a specialized structure that determines the cell polarity and prevents the diffusion of toxins, allergens, and pathogens from the lumen into the tissue. TJs are highly dynamic and its constituent protein complexes undergo continuously remodeling and turnover under tight regulation by numerous extracellular and intracellular factors. RNA-binding proteins (RBPs) and microRNAs (miRNAs) regulate gene expression at the posttranscriptional level and are involved in many aspects of cellular physiology. An increasing body of evidence indicates that RBPs including HuR and CUG-binding protein 1 and miRNAs such as miR-192 modulate the stability and translation of mRNAs encoding TJ proteins and play an important role in the control of intestinal epithelial TJ barrier function. In this mini-review article, we highlight the changes in TJ expression and intestinal epithelial TJ barrier function after activation or inactivation of RBPs and miRNAs and further analyze in some detail the mechanisms through which the stability and translation of TJ mRNAs are regulated by RBPs and miRNAs.

MicroRNA-dependent targeting of the extracellular matrix as a mechanism of regulating cell behavior

BACKGROUND

MicroRNAs are small noncoding RNAs which regulate gene expression at the posttranscriptional level by inducing mRNA degradation or translational repression. MicroRNA-dependent modulation of the extracellular matrix and its cellular receptors has emerged as a novel mechanism of regulating numerous matrix-dependent processes, including cell proliferation and apoptosis, cell adhesion and migration, cell differentiation and stem cell properties.

SCOPE OF REVIEW

In this review, we will present different mechanisms by which microRNAs and extracellular matrix constituents mutually regulate their expression, and we will demonstrate how these expression changes affect cell behavior. We will also highlight the importance of dysregulated matrix-related microRNA expression for the pathogenesis of inflammatory and malignant disease, and discuss the potential for diagnostic and therapeutic applications.

MAJOR CONCLUSIONS

MicroRNAs and matrix-dependent signal transduction processes form novel regulatory circuits, which profoundly affect cell behavior. As misexpression of microRNAs targeting extracellular matrix constituents is observed in a variety of diseases, a pharmacological intervention with these processes has therapeutic potential, as successfully demonstrated in vitro and in advanced animal models. However, a deeper mechanistic understanding is required to address potential side effects prior to clinical applications in humans.

GENERAL SIGNIFICANCE

A full understanding of the role and function of microRNA-dependent regulation of the extracellular matrix may lead to new targeted therapies and new diagnostics for malignant and inflammatory diseases in humans. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Overexpression of lysine-specific demethylase 1 in ovarian endometriomas and its inhibition reduces cellular proliferation, cell cycle progression, and invasiveness

OBJECTIVE

To investigate whether lysine-specific demethylase 1 (LSD1) is aberrantly expressed in endometriomas and whether treatment with tranylcypromine, an LSD1 inhibitor, has any effect on cell viability, cell cycle, and invasiveness.

DESIGN

Laboratory study using human tissues.

SETTING

Academic hospital.

PATIENT(S)

Forty-two ectopic endometrial tissue samples, their homologue eutopic endometrial tissue samples, and 70 control endometrial tissue samples.

INTERVENTION(S)

Immunohistochemistry analysis of LSD1 of all human tissue samples, and Western blot analysis, quantitative real-time reverse-transcription polymerase chain reaction analysis, cell viability assay, cell cycle analysis, and invasion assay of eutopic and ectopic endometriotic stromal cells and normal endometrial stromal cells.

MAIN OUTCOME MEASURE(S)

Immunostaining levels of LSD1, gene and protein expression levels, cell viability, cell cycles, and invasiveness.

RESULT(S)

The expression of the LSD1 gene and protein in endometriosis was elevated. Treatment of endometriotic stromal cells with tranylcypromine statistically significantly reduced the cellular proliferation, cell cycle progression, and invasiveness.

CONCLUSION(S)

Because DNA and histones are intimately intertwined and work in concert in transcription regulation, conceivably histone demethylation activity of LSD1 could be wide ranging. The inhibition of LSD1 activity by tranylcypromine and the resultant inhibition of proliferation, cell cycle progression, and invasiveness suggest that LSD1 may be a candidate therapeutic target for endometriosis.

Overexpression of miR-145 increases the sensitivity of vemurafenib in drug-resistant colo205 cell line

Vemurafenib is a selective and potent small molecule inhibitor of the V600 mutant form of the BRAF protein used in the treatment of melanoma and colorectal cancer. However, vemurafenib has less effect in BRAF mutant colorectal cancer due to the resistance of tumor cell to vemurafenib. To verify whether or not miR-145, a short RNA molecule of microRNA which has been supposed to be a tumor suppressor, is involved in this process, we established vemurafenib-resistant cell line colo205/V and found that the miR-145 expression was significantly downregulated in colo205/V cells compared to normal colo205 cells. Moreover, the overexpression of miR-145 could increase the sensitivity of colo205/V cells to vemurafenib both in vitro and in vivo. In conclusion, miR-145 might be used as a therapeutic target in the treatment of colorectal cancer patients with BRAF V600E mutation.

Protumorigenic effects of mir-145 loss in malignant pleural mesothelioma

We identified a discrete number of microRNAs differentially expressed in benign or malignant mesothelial tissues. We focused on mir-145 whose levels were significantly downregulated in malignant mesothelial tissues and malignant pleural mesothelioma (MPM) cell lines as compared to benign tissues (pleura, peritoneum or cysts). We show that promoter hyper-methylation caused very low levels in MPM cell lines and specimens. Treatment of MPM cell lines with mir-145 agonists negatively modulated some protumorigenic properties of MPM cells, such as clonogenicity, cell migration and resistance to pemetrexed treatment. The main effector mechanism of the clonogenic death induced by mir-145 was that of accelerated senescence. We found that mir-145 targeted OCT4 via specific binding to its 3'-UTR. Increased intracellular levels of mir-145 decreased the levels of OCT4 and its target gene ZEB1, thereby counteracting the increase of OCT4 induced by pemetrexed treatment which is known to favor the development of chemoresistant cells. In line with this, reintroduction of OCT4 into mimic-145 treated cells counteracted the effects on clonogenicity and replicative senescence. This further supports the relevance of the mir-145-OCT4 interaction for the survival of MPM cells. The potential use of mir-145 expression levels to classify benign vs malignant mesothelial tissues and the differences between pemetrexed-induced senescence and that induced by the re-expression of mir-145 are discussed.

Genetic, epigenetic and stem cell alterations in endometriosis: new insights and potential therapeutic perspectives

Human endometrium is a highly dynamic tissue, undergoing periodic growth and regression at each menstrual cycle. Endometriosis is a frequent chronic pathological status characterized by endometrial tissue with an ectopic localization, causing pelvic pain and infertility and a variable clinical presentation. In addition, there is well-established evidence that, although endometriosis is considered benign, it is associated with an increased risk of malignant transformation in approximately 1.0% of affected women, with the involvement of multiple pathways of development. Increasing evidence supports a key contribution of different stem/progenitor cell populations not only in the cyclic regeneration of eutopic endometrium, but also in the pathogenesis of at least some types of endometriosis. Evidence has arisen from experiments in animal models of disease through different kinds of assays (including clonogenicity, the label-retaining cell approach, the analysis of undifferentiation markers), as well as from descriptive studies on ectopic and eutopic tissue samples harvested from affected women. Changes in stem cell populations in endometriotic lesions are associated with genetic and epigenetic alterations, including imbalance of miRNA expression, histone and DNA modifications and chromosomal aberrations. The present short review mainly summarizes the latest observations contributing to the current knowledge regarding the presence and the potential contribution of stem/progenitor cells in eutopic endometrium and the aetiology of endometriosis, together with a report of the most recently identified genetic and epigenetic alterations in endometriosis. We also describe the potential advantages of single cell molecular profiling in endometrium and in endometriotic lesions. All these data can have clinical implications and provide a basis for new potential therapeutic applications.