Expression of the imprinted H19 oncofetal RNA in epithelial ovarian cancer

Long noncoding RNA H19 in ovarian biology and placenta development

As the first long noncoding RNA to be discovered, H19 has gained substantial attention as a key regulator of several biological processes and its roles in female reproductive biology are gradually getting revealed. Herein, we have summarized the current evidence regarding H19 expression pattern and involvement in the developmental and pathological processes associated with the ovary and the placenta. The findings indicate that within the ovaries, H19 is expressed in the antral and cystic atretic follicles as well as in the corpora lutea but absent in the primordial, primary, and secondary follicles. Its normal expression promotes the maturation of antral follicles and prevents their premature selection for the ovulatory journey while its aberrant induction promotes polycystic ovary syndrome development and ovarian cancer metastasis. In the placenta, H19 is highly expressed in the cytotrophoblasts and extravillous trophoblasts but weakly expressed in the syncytiotrophoblast layer and potentially controls trophoblast cell fate decisions during placenta development. Abnormal expression of H19 is observed in the placental villi of pregnancies affected by pre-eclampsia and fetal growth restriction. Therefore, dysregulated H19 is a candidate biomarker and therapeutic target for the mitigation of ovarian and placenta-associated diseases.

Suicide gene strategies applied in ovarian cancer studies

Ovarian cancer represents the most lethal gynecological malignancy among women in developed countries. Despite the recent innovations, the improvements in the 5-year survival rate have been insufficient and the management of this disease still remains a challenge. The fact that the majority of patients experience recurrent or resistant disease have substantiated the necessity of an innovative treatment. Among various strategies investigated, the recent strides made in gene delivery techniques have made gene therapy, including suicide gene strategies, a potential alternative for treating ovarian cancer. Various suicide gene candidates, which are capable of promoting cancer cell apoptosis directly after its entry or indirectly by prodrug administration, can be separated into three systems using enzyme-coding, toxin or pro-apoptotic genes. With this review, we aim to provide an overview of different suicide genes depending on therapeutic strategies, the vectors used to deliver these transgenes specifically to malignant cells, and the combined treatments of these genes with various therapeutic regimens.

The role of lncRNA H19 in tumorigenesis and drug resistance of human Cancers

Systemic therapy is one of the most significant cancer treatments. However, drug resistance often appears and has become the primary cause of cancer therapy failure. Regulation of drug target, drug metabolism and drug efflux, cell death escape (apoptosis, autophagy, et al.), epigenetic changes, and many other variables are complicatedly involved in the mechanisms of drug resistance. In various types of cancers, long non-coding RNA H19 (lncRNA H19) has been shown to play critical roles in tumor development, proliferation, metastasis, and multiple drug resistance as well. The efficacy of chemotherapy, endocrine therapy, and targeted therapy are all influenced by the expression of H19, especially in breast cancer, liver cancer, lung cancer and colorectal cancer. Here, we summarize the relationship between lncRNA H19 and tumorigenesis, and illustrate the drug resistance mechanisms caused by lncRNA H19 as well. This review may provide more therapeutic potential targets for future cancer treatments.

The Effect of Metformin on Expression of Long Non-coding RNA H19 in Endometrial Cancer

Background: Endometrial cancer is the fourth most widespread cancer among females, with a growing prevalence in recent years. Management by combined therapies along with surgery, radiotherapy, and chemotherapy have improved patients' prognoses. Besides, the development of new therapies helps preserve fertility and prognosis in aggressive tumors. The purpose of this research was to identify the efficacy of metformin on the H19 long non-coding RNA expression in endometrial cancer to provide further insight into the pathogenesis and treatment of the disease. Methods: A total of 23 patients with endometrial cancer, diagnosed by biopsy or diagnostic curettage, were recruited and divided into three groups, before and after metformin treatment and placebo. Real-time PCR was used to evaluate the H19 expression in cancer tissue in all patients. Results: : It has been observed that in endometrial tissue of the "after-metformin" treatment group, the H19 expression level was significantly reduced, compared with the "before-metformin" treatment group, but not in comparison with the placebo. These findings indicate that metformin reduced the H19 expression in endometrial cancer. Conclusion: Anti-diabetic drugs, such as metformin, may be beneficial by reducing the H19 expression in endometrial cancer due to the H19 relation to cancer progression.

Long Non-Coding RNA-Based Functional Prediction Reveals Novel Targets in Notch-Upregulated Ovarian Cancer

Notch signaling is a druggable target in high-grade serous ovarian cancers; however, its complexity is not clearly understood. Recent revelations of the biological roles of lncRNAs have led to an increased interest in the oncogenic action of lncRNAs in various cancers. In this study, we performed in silico analyses using The Cancer Genome Atlas data to discover novel Notch-related lncRNAs and validated our transcriptome data via NOTCH1/3 silencing in serous ovarian cancer cells. The expression of novel Notch-related lncRNAs was down-regulated by a Notch inhibitor and was upregulated in high-grade serous ovarian cancers, compared to benign or borderline ovarian tumors. Functionally, Notch-related lncRNAs were tightly linked to Notch-related changes in diverse gene expressions. Notably, genes related to DNA repair and spermatogenesis showed specific correlations with Notch-related lncRNAs. Master transcription factors, including EGR1, CTCF, GABPα, and E2F4 might orchestrate the upregulation of Notch-related lncRNAs, along with the associated genes. The discovery of Notch-related lncRNAs significantly contributes to our understanding of the complex crosstalk of Notch signaling with other oncogenic pathways at the transcriptional level.

The Genetic Changes of Hepatoblastoma

Hepatoblastoma is the most common malignant liver cancer in childhood. The etiology of hepatoblastoma remains obscure. Hepatoblastoma is closely related to genetic syndromes, hinting that hepatoblastoma is a genetic predisposition disease. However, no precise exposures or genetic events are reported to hepatoblastoma occurrence. During the past decade, significant advances have been made in the understanding of etiology leading to hepatoblastoma, and several important genetic events that appear to be important for the development and progression of this tumor have been identified. Advances in our understanding of the genetic changes that underlie hepatoblastoma may translate into better patient outcomes. Single nucleotide polymorphisms (SNPs) have been generally applied in the research of etiology's exploration, disease treatment, and prognosis assessment. Here, we reviewed and discussed the molecular epidemiology, especially SNPs progresses in hepatoblastoma, to provide references for future studies and promote the study of hepatoblastoma's etiology.

Long non-coding RNAs in recurrent ovarian cancer: Theranostic perspectives

Nearly 70% of ovarian cancer (OC) patients experience recurrence within the first 2 years after initial treatment. Emerging evidence indicates that long non-coding RNAs (lncRNAs) play a pivotal role in the pathogenesis of OC progression, resistance to therapy and recurrent OC (ROC). Transcriptome profiling studies have reported differential expression patterns of lncRNAs in OC which are related to increased cell invasion, metastasis and drug resistance. In this review, we highlighted the roles of lncRNAs in OC progression and outlined the potential molecular mechanisms by which lncRNAs impact on ROC. Recent advances using lncRNAs as potential biomarkers for screening, detection, prediction, response to therapy and as therapeutic targets are discussed.

Correlation between polymorphisms in IGF2/H19 gene locus and epithelial ovarian cancer risk in Chinese population

To investigate the association between SNPs in human IGF2/H19 gene locus and epithelial ovarian cancer (EOC) risk, we performed a case-control study in 422 individuals (219 EOC patients and 203 cancer-free controls). Four SNPs (rs2525885, rs2839698, rs3741206, rs3741219) were found to be related with EOC risk. Specifically, the minor allele C of rs2525885 and allele A of rs2839698 was associated with elevated EOC genetic susceptibility under both dominant and recessive models (TC + CC vs TT: adjusted OR: 1.61, P = .031; CC vs TT + TC: adjusted OR: 4.87, P = .014; GA + AA vs GG: adjusted OR: 1.63, P = .023; AA vs GG + GA: adjusted OR: 2.43, P = .007). For rs3741206, the genotype TC + CC was associated with a significant decrease in EOC risk with the TT genotype as reference in a dominant genetic model (adjusted OR: 0.44, P = .003), while for rs3741219, genotype AA was associated with a 59% decrease in EOC risk only in the recessive model (adjusted OR: 0.41, P = .038). In the stratified analysis, an increased risk associated with the variant genotypes was observed in only subjects aged >47 years for rs2525885 (adjusted OR = 2.04, P = .024), rs2839698 (adjusted OR = 2.50, P = .047) and rs3741206 (adjusted OR = 0.37, P = .009), respectively. What's more, the TC + CC genotype of rs2525885 was significantly associated with advanced FIGO stage (III vs II, adjusted OR = 2.73, P = .040).

Targeted Diphtheria Toxin-Based Therapy: A Review Article

Cancer remains one of the leading causes of death worldwide. Conventional therapeutic strategies usually offer limited specificity, resulting in severe side effects and toxicity to normal tissues. Targeted cancer therapy, on the other hand, can improve the therapeutic potential of anti-cancer agents and decrease unwanted side effects. Targeted applications of cytolethal bacterial toxins have been found to be especially useful for the specific eradication of cancer cells. Targeting is either mediated by peptides or by protein-targeting moieties, such as antibodies, antibody fragments, cell-penetrating peptides (CPPs), growth factors, or cytokines. Together with a toxin domain, these molecules are more commonly referred to as immunotoxins. Targeting can also be achieved through gene delivery and cell-specific expression of a toxin. Of the available cytolethal toxins, diphtheria toxin (DT) is one of the most frequently used for these strategies. Of the many DT-based therapeutic strategies investigated to date, two immunotoxins, Ontak^TM and Tagraxofusp^TM, have gained FDA approval for clinical application. Despite some success with immunotoxins, suicide-gene therapy strategies, whereby controlled tumor-specific expression of DT is used for the eradication of malignant cells, are gaining prominence. The first part of this review focuses on DT-based immunotoxins, and it then discusses recent developments in tumor-specific expression of DT.

LncRNAs as Regulators of Autophagy and Drug Resistance in Colorectal Cancer

Colorectal cancer (CRC) is a common malignancy with 1. 8 million cases in 2018. Autophagy helps to maintain an adequate cancer microenvironment in order to provide nutritional supplement under adverse conditions such as starvation and hypoxia. Additionally, most of the cases of CRC are unresponsive to chemotherapy, representing a significant challenge for cancer therapy. Recently, autophagy induced by therapy has been shown as a unique mechanism of resistance to anticancer drugs. In this regard, long non-coding RNAs (lncRNAs) analysis are important for cancer detection, progression, diagnosis, therapy response, and prognostic values. With increasing development of quantitative detection techniques, lncRNAs derived from patients' non-invasive samples (i.e., blood, stools, and urine) has become into a novel approach in precision oncology. Tumorspecific GAS5, HOTAIR, H19, and MALAT are novels CRC related lncRNAs detected in patients. Nonetheless, the effect and mechanism of lncRNAs in cancer autophagy and chemoresistance have not been extensively characterized. Chemoresistance and autophagy are relevant for cancer treatment and lncRNAs play a pivotal role in resistance acquisition for several drugs. LncRNAs such as HAGLROS, KCNQ1OT1, and H19 are examples of lncRNAs related to chemoresistance leaded by autophagy. Finally, clinical implications of lncRNAs in CRC are relevant, since they have been associated with tumor differentiation, tumor size, histological grade, histological types, Dukes staging, degree of differentiation, lymph node metastasis, distant metastasis, recurrent free survival, and overall survival (OS).

Super-Enhancer-Associated LncRNA UCA1 Interacts Directly with AMOT to Activate YAP Target Genes in Epithelial Ovarian Cancer

Long noncoding RNAs (lncRNAs) have emerged as critical regulators of tumorigenesis, and yet their mechanistic roles remain challenging to characterize. Here, we integrate functional proteomics with lncRNA-interactome profiling to characterize Urothelial Cancer Associated 1 (UCA1), a candidate driver of ovarian cancer development. Reverse phase protein array (RPPA) analysis indicates that UCA1 activates transcription coactivator YAP and its target genes. In vivo RNA antisense purification (iRAP) of UCA1 interacting proteins identified angiomotin (AMOT), a known YAP regulator, as a direct binding partner. Loss-of-function experiments show that AMOT mediates YAP activation by UCA1, as UCA1 enhances the AMOT-YAP interaction to promote YAP dephosphorylation and nuclear translocation. Together, we characterize UCA1 as a lncRNA regulator of Hippo-YAP signaling and highlight the UCA1-AMOT-YAP signaling axis in ovarian cancer development.

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A super-enhancer drives the expression of lncRNA UCA1 in EOC

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Inactivation of UCA1 impairs tumor growth in vivo

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UCA1 activates transcription coactivator YAP and its target genes

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UCA1 promotes YAP dephosphorylation and nuclear translocation via AMOTp130

Long noncoding RNAs as biotargets in cisplatin-based drug resistance

Since its discovery, cisplatin has become the key drug in chemotherapy for cancers. Nevertheless, chemoresistance in cancers has become an impediment in using cisplatin for cancer treatment. The resistance toward cisplatin is multifaceted as it involves multiple cellular pathways. Ever since the knowledge of long noncoding RNAs as modulators of various molecular pathways came to light, the interest in the biological function of lncRNAs as biomarkers has increased dramatically. Numerous studies have reported the link between the dysregulation of lncRNAs and drug resistance in cancers. More importantly, several lncRNAs were found to be vital in regulating cisplatin resistance. Therefore, this review summarizes the recent efforts in linking between cisplatin resistance and different types of lncRNAs.

Non-Coding RNAs in Endometrial Physiopathology

The Human Genome Project led to the discovery that about 80% of our DNA is transcribed in RNA molecules. Only 2% of the human genome is translated into proteins, the rest mostly produces molecules called non-coding RNAs, which are a heterogeneous class of RNAs involved in different steps of gene regulation. They have been classified, according to their length, into small non-coding RNAs and long non-coding RNAs, or to their function, into housekeeping non-coding RNAs and regulatory non-coding RNAs. Their involvement has been widely demonstrated in all cellular processes, as well as their dysregulation in human pathologies. In this review, we discuss the function of non-coding RNAs in endometrial physiology, analysing their involvement in embryo implantation. Moreover, we explore their role in endometrial pathologies such as endometrial cancer, endometriosis and chronic endometritis.

Long non-coding RNAs in ovarian cancer

Long non-coding RNAs (lncRNAs) refer to functional cellular RNAs molecules longer than 200 nucleotides in length. Unlike microRNAs, which have been widely studied, little is known about the enigmatic role of lncRNAs. However, lncRNAs have motivated extensively attention in the past few years and are emerging as potentially important regulators in pathological processes, including in cancer. We now understand that lncRNAs play role in cancer through their interactions with DNA, protein, and RNA in many instances. Moreover, accumulating evidence has recognized that large classes of lncRNAs are functional for ovarian cancer. Nevertheless, the biological phenomena and molecular mechanisms of lncRNAs in ovarian cancer remain to be better identified. In this review, we outline the dysregulated expression of lncRNAs and their potential clinical implications in ovarian cancer, with a particular emphasis on discussing the well characterized mechanisms underlying lncRNAs in ovarian cancer.

Telomerase regulation by the long non-coding RNA H19 in human acute promyelocytic leukemia cells

Background

Since tumor growth requires reactivation of telomerase (hTERT), this enzyme is a challenging target for drug development. Therefore, it is of great interest to identify telomerase expression and activity regulators. Retinoids are well-known inducers of granulocytic maturation associated with hTERT repression in acute promyelocytic leukemia (APL) blasts. In a maturation-resistant APL cell line, we have previously identified a new pathway of retinoid-induced hTERT transcriptional repression independent of differentiation. Furthermore, we reported the isolation of a cell variant resistant to this repression. Those cell lines could serve as unique tools to identify new telomerase regulators.

Methods

Using a microarray approach we identified the long non-coding RNA, H19 as a potential candidate playing a role in telomerase regulation. Expression of H19, hTERT, and hTR were examined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Telomerase activity was quantified by quantitative telomeric repeats amplification protocol (qTRAP). In vitro and in vivo assays were performed to investigate H19 function on telomerase expression and activity.

Results

We showed both in retinoid-treated cell lines and in APL patient cells an inverse relationship between the expression of H19 and the expression and activity of hTERT. Exploring the mechanistic link between H19 and hTERT regulation, we showed that H19 is able to impede telomerase function by disruption of the hTERT-hTR interaction.

Conclusions

This study identifies a new way of telomerase regulation through H19’s involvement and thereby reveals a new function for this long non-coding RNA that can be targeted for therapeutic purpose.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0835-8) contains supplementary material, which is available to authorized users.

Expression and clinical role of long non-coding RNA in high-grade serous carcinoma

OBJECTIVE

To profile long non-coding RNA (lncRNA) expression at the various anatomic sites of high-grades serous carcinoma (HGSC) and in effusion-derived exosomes.

METHODS

LncRNA profiling was performed on 60 HGSC specimens, including 10 ovarian tumors, 10 solid metastases and 10 malignant effusions, as well as exosomes from 30 effusion supernatants. Anatomic site-related expression of ESRG, Link-A, GAS5, MEG3, GATS, PVT1 H19, Linc-RoR, HOTAIR and MALAT1 was validated by quantitative PCR and assessed for clinical relevance in a series of 77 HGSC effusions, 40 ovarian carcinomas, 21 solid metastases and 42 supernatant exosomes.

RESULTS

Significantly different (p<0.05) expression of 241, 406 and 3634 lncRNAs was found in comparative analysis of the ovarian tumors to solid metastases, effusions and exosomes, respectively. Cut-off at two-fold change in lncRNA expression identified 54 lncRNAs present at the 3 anatomic sites and in exosomes. Validation analysis showed significantly different expression of 5 of 10 lncRNAs in the 4 specimen groups (ESRG, Link-A, MEG3, GATS and PVT1, all p<0.001). Higher ESRG levels in HGSC effusions were associated with longer overall survival in the entire effusion cohort (p=0.023) and in patients with pre-chemotherapy effusions tapped at diagnosis (p=0.048). Higher Link-A levels were associated with better overall (p=0.015) and progression-free (p=0.023) survival for patients with post-chemotherapy effusions. Link-A was an independent prognostic marker in Cox multivariate analysis in the latter group (p=0.045).

CONCLUSIONS

We present the first evidence of differential LncRNA expression as function of anatomic site in HGSC. LncRNA levels in HGSC effusions are candidate prognostic markers.

Long noncoding RNA H19 indicates a poor prognosis of colorectal cancer and promotes tumor growth by recruiting and binding to eIF4A3

The overall biological role and clinical significance of long non-coding RNA H19 in colorectal cancer (CRC) remain largely unknown. Here, we firstly report that the lncRNA H19 recruits eIF4A3 and promotes the CRC cell proliferation. We observed higher expression of H19 was significantly correlated with tumor differentiation and advanced TNM stage in a cohort of 83 CRC patients. Multivariate analyses revealed that expression of H19 served as an independent predictor for overall survival and disease-free survival. Further experiments revealed that overexpression of H19 promoted the proliferation of CRC cells, while depletion of H19 inhibited cell viability and induced growth arrest. Moreover, expression profile data showed that H19 upregulated a series of cell-cycle genes. Using bioinformatics prediction and RNA immunoprecipitation assays, we identified eIF4A3 as an RNA-binding protein that binds to H19. We confirmed that combining eIF4A3 with H19 obstructed the recruitment of eIF4A3 to the cell-cycle gene mRNA. Our results suggest that H19, as a growth regulator, could serve as a candidate prognostic biomarker and target for new therapies in human CRC.

Functional prediction of long non-coding RNAs in ovarian cancer-associated fibroblasts indicate a potential role in metastasis

Cancer-associated fibroblasts (CAFs) contribute to the poor prognosis of ovarian cancer. Unlike in tumour cells, DNA mutations are rare in CAFs, raising the likelihood of other mechanisms that regulate gene expression such as long non-coding RNAs (lncRNAs). We aimed to identify lncRNAs that contribute to the tumour-promoting phenotype of CAFs. RNA expression from 67 ovarian CAF samples and 10 normal ovarian fibroblast (NOF) samples were analysed to identify differentially expressed lncRNAs and a functional network was constructed to predict those CAF-specific lncRNAs involved in metastasis. Of the 1,970 lncRNAs available for analysis on the gene expression array used, 39 unique lncRNAs were identified as differentially expressed in CAFs versus NOFs. The predictive power of differentially expressed lncRNAs in distinguishing CAFs from NOFs were assessed using multiple multivariate models. Interrogation of known transcription factor-lncRNA interactions, transcription factor-gene interactions and construction of a context-specific interaction network identified multiple lncRNAs predicted to play a role in metastasis. We have identified novel lncRNAs in ovarian cancer that are differentially expressed in CAFs compared to NOFs and are predicted to contribute to the metastasis-promoting phenotype of CAFs.

Dysregulated expression of long noncoding RNAs in gynecologic cancers

Cancers of the female reproductive system include ovarian, uterine, vaginal, cervical and vulvar cancers, which are termed gynecologic cancer. The emergence of long noncoding RNAs (lncRNAs), which are believed to play a crucial role in several different biological processes, has made the regulation of gene expression more complex. Although the function of lncRNAs is still rather elusive, their broad involvement in the initiation and progression of various cancers is clear. They are also involved in the pathogenesis of cancers of the female reproductive system. LncRNAs play a critical physiological role in apoptosis, metastasis, invasion, migration and cell proliferation in these cancers. Different expression profiles of lncRNAs have been observed in various types of tumors compared with normal tissues and between malignant and benign tumors. These differential expression patterns may lead to the promotion or suppression of cancer development and tumorigenesis. In the current review, we present the lncRNAs that show a differential expression between cancerous and normal tissues in ovarian, cervical and endometrial cancers, and highlight the associations between lncRNAs and some of the molecular pathways involved in these cancers.

Integration of Population-Level Genotype Data with Functional Annotation Reveals Over-Representation of Long Noncoding RNAs at Ovarian Cancer Susceptibility Loci

BACKGROUND

Genome-wide association studies (GWAS) have identified multiple loci associated with epithelial ovarian cancer (EOC) susceptibility, but further progress requires integration of epidemiology and biology to illuminate true risk loci below genome-wide significance levels (P < 5 × 10-8). Most risk SNPs lie within non-protein-encoding regions, and we hypothesize that long noncoding RNA (lncRNA) genes are enriched at EOC risk regions and represent biologically relevant functional targets.

METHODS

Using imputed GWAS data from about 18,000 invasive EOC cases and 34,000 controls of European ancestry, the GENCODE (v19) lncRNA database was used to annotate SNPs from 13,442 lncRNAs for permutation-based enrichment analysis. Tumor expression quantitative trait locus (eQTL) analysis was performed for sub-genome-wide regions (1 × 10-5 > P > 5 × 10-8) overlapping lncRNAs.

RESULTS

Of 5,294 EOC-associated SNPs (P < 1.0 × 10-5), 1,464 (28%) mapped within 53 unique lncRNAs and an additional 3,484 (66%) SNPs were correlated (r2 > 0.2) with SNPs within 115 lncRNAs. EOC-associated SNPs comprised 130 independent regions, of which 72 (55%) overlapped with lncRNAs, representing a significant enrichment (P = 5.0 × 10-4) that was more pronounced among a subset of 5,401 lncRNAs with active epigenetic regulation in normal ovarian tissue. EOC-associated lncRNAs and their putative promoters and transcription factors were enriched for biologically relevant pathways and eQTL analysis identified five novel putative risk regions with allele-specific effects on lncRNA gene expression.

CONCLUSIONS

lncRNAs are significantly enriched at EOC risk regions, suggesting a mechanistic role for lncRNAs in driving predisposition to EOC.

IMPACT

lncRNAs represent key candidates for integrative epidemiologic and functional studies. Further research on their biologic role in ovarian cancer is indicated. Cancer Epidemiol Biomarkers Prev; 26(1); 116-25. ©2016 AACR.

Long non-coding RNA H19 enhances cell proliferation and anchorage-independent growth of cervical cancer cell lines

Long non-coding RNA H19 is aberrantly expressed in multiple malignancies and its expression levels correlate with recurrence, metastasis, and patient survival. Despite numerous reports documenting the role of H19 in carcinogenesis, its contribution to cervical cancer development is still largely unknown. In this study, I observed that H19 expression was elevated in cervical cancer cell lines and could be detected in extracellular vesicles in the culture medium. In addition, I demonstrated, by overexpression and knockdown experiments, that H19 promoted cell proliferation and multicellular tumor spheroid formation without significantly affecting apoptosis and cell migration. Finally, treatment with transforming growth factor beta and hypoxia-mimetic CoCl₂ could modulate H19 levels in a cell line-specific manner. These findings indicate that H19 promotes both anchorage-specific and -independent growth of cervical cancer cell lines and may serve as a potential target for cancer diagnosis and therapy.

MicroRNA and Long Non-Coding RNA in Ovarian Carcinoma: Translational Insights and Potential Clinical Applications

Reliable biomarkers for the detection of early ovarian carcinoma are currently unavailable. MicroRNA and long non-coding RNA may be important in cancer initiation and progression by regulating gene expression through post-transcriptional mechanisms. MicroRNAs, such as miR-26a and miR-132, have been investigated as novel biomarkers for diagnosis, prognosis, monitoring of therapeutic response, and therapeutic targets in ovarian carcinomas. Some long non-coding RNAs, such as H19 and UCA1, may be involved in the pathogenesis of ovarian carcinomas. MicroRNA and long non-coding RNA have potential clinical utility in the diagnosis of ovarian cancer and predicting prognosis, metastasis, recurrence, and response to therapy.

The Role of Long Non-Coding RNAs in Ovarian Cancer

Background:

Mesenchymal stem cells (MSCs) are important candidates for MSC-based cellular therapy. Current paradigm states that MSCs support local progenitor cells in damaged tissue through paracrine signaling. Therefore, the study of paracrine effects and secretome of MSCs could lead to the appreciation of mechanisms and molecules associated with the therapeutic effects of these cells. This study analyzed anti-inflammatory and immune-modulatory effects of MSC secretomes derived from embryonic stem cells (ESCs) and bone marrow cells after hypoxia and normoxia preconditioning.

Methods:

ESCs differentiated into MSCs and characterized by flow cytometry as well as by differentiation into adipocytes and osteoblasts. The experimental groups were consisted of individual groups of ESC-MSCs and BM-MSCs (bone marrow-derived mesenchymal stromal cells), which were preconditioned with either hypoxia or normoxia for 24, 48 and 72 h. After collecting the cell-free medium from each treatment, secretomes were concentrated by centrifugal filters. Using a peripheral blood mononuclear cell (PBMC) assay and ELISA, IL-10 concentration in PBMCs was evaluated after their incubation with different secretomes from preconditioned and non-preconditioned MSCs.

Results:

A significant difference was observed between ESC-MSC normoxia and ESC-MSC hypoxia in IL-10 concentration, and normoxia secretomes increased IL-10 secretion from PBMCs. Moreover, the strongest IL-10 secretion from PBMCs could be detected after the stimulation by ESC-MSC conditioned secretomes, but not BM-MSC conditioned medium.

Conclusions:

Human hypoxia preconditioned ESC-MSC secretome indicated stronger immune-modulatory effects compared to BM-MSC conditioned medium. It could be suggested that induced MSCs confer less immune-modulatory effects but produce more inflammatory molecules such as tumor necrosis factor α, which needs further investigation.

The emerging role of long non-coding RNAs in endometrial cancer

The human genome is pervasively transcribed and approximately 98% of the genome is non-coding. Long non-coding RNAs (lncRNAs) are a heterogeneous group of RNA transcripts that are >200 nucleotides in length with minimal to no protein-coding potential. Similar to proteins, lncRNAs have important biological functions in both normal cells and disease states including many types of cancer. This review summarizes recent advances in our understanding of lncRNAs in cancer biology and highlights the potential for lncRNA as diagnostic biomarkers and therapeutics. Herein we focus on the poorly understood role of lncRNAs in endometrial cancer, the most common gynecologic malignancy in the developed world.

An overview of long non-coding RNAs in ovarian cancers

As with miRNAs a decade ago, the scientific community recently understood that lncRNAs represent a new layer of complexity in the regulation of gene expression. Although only a subset of lncRNAs has been functionally characterized, it is clear that they are deeply involved in the most critical physiological and pathological biological processes. This review shows that in ovarian carcinoma, data already available testify to the importance of lncRNAs and that the demonstration of an ever-growing role of lncRNAs in the biology of this malignancy can be expected from future studies. We also underline the importance of their relationship with associated protein partners and miRNAs. Together, the available information suggests that the emerging field of lncRNAs will pave the way for a better understanding of ovarian cancer biology and might lead to the development of innovative therapeutic approaches. Moreover, lncRNAs expression signatures either alone or in combination with other types of markers (miRNAs, mRNAs, proteins) could prove useful to predict outcome or treatment follow-up in order to improve the therapeutic care of ovarian carcinoma patients.

Functions and Mechanisms of Long Noncoding RNAs in Ovarian Cancer

Long noncoding RNAs (lncRNAs) are longer than 200-nucleotide, noncoding transcripts in length, have a variety of biological functions, and are closely associated with tumor development. Ovarian cancer, as 1 of the 3 common gynecological malignancies, is the leading cause of death in women with gynecological malignant tumor. In this study, a review of the literature found that lncRNAs H19, LSINCT5, and XIST have a close relationship to the development of ovarian cancer occurrence, growth, invasion, and metastasis, and they can promote ovarian cancer cell proliferation. Hence, in this article, the progress of above-mentioned 3 kinds of lncRNAs in ovarian cancer was reviewed and designed to help in the diagnosis, treatment, and prognosis of ovarian cancer.

Downregulation of BC200 in ovarian cancer contributes to cancer cell proliferation and chemoresistance to carboplatin

Previous studies have demonstrated that long non-coding RNAs (lncRNAs) serve an important role in carcinogenesis. BC200 is a lncRNA that is reportedly associated with ovarian cancer. The aim of the present study was to investigate this potential association between BC200 and ovarian cancer, and to subsequently analyze the biological function of BC200 in the disease. BC200 expression was compared in ovarian cancer tissue and normal ovarian tissue samples through the use of quantitative polymerase chain reaction. To allow the biological function of BC200 in ovarian cancer to be analyzed, small interfering RNA was used to knock down the expression of BC200 in SKOV3 and A2780 ovarian cancer cells. The proliferative, invasive and migratory abilities of the cells were identified by means of cell counting kits and Transwell assays. Carboplatin was also used to treat the ovarian cancer cells, and a luminescent cell viability assay was subsequently used to detect the sensitivity of the cells to the carboplatin. The results demonstrated that BC200 expression was reduced in ovarian cancer compared with normal ovarian tissue samples. In the SKOV3 and A2780 cells, BC200 exerted no effect on invasive or migratory ability, however, the inhibition of BC200 was demonstrated to promote cell proliferation. Additionally, it was observed that carboplatin induced BC200 expression in the cell lines, and that the inhibition of BC200 decreased the sensitivity of the cells to the drug. BC200 is therefore likely to have a tumor suppressive function in ovarian cancer by affecting cell proliferation. Furthermore, BC200 appears to serve a role in the mediation of carboplatin-induced ovarian cancer cell death.

Molecular Analysis of Mixed Endometrioid and Serous Adenocarcinoma of the Endometrium

Background

The molecular biology and cellular origins of mixed type endometrial carcinomas (MT-ECs) are poorly understood, and a Type II component of 10 percent or less may confer poorer prognoses.

Methodology/Principal Findings

We studied 10 cases of MT-EC (containing endometrioid and serous differentiation), 5 pure low-grade endometrioid adenocarcinoma (EAC) and 5 pure uterine serous carcinoma (USC). Endometrioid and serous components of the MT-ECs were macrodissected and the expression of 60 candidate genes compared between MT-EC, pure USC and pure EAC. We found that four genes were differentially expressed when MT-ECs were compared to pure low-grade EAC: CDKN2A (P = 0.006), H19 (P = 0.010), HOMER2 (P = 0.009) and TNNT1 (P = 0.006). Also while we found that even though MT-ECs closely resembled the molecular profiles of pure USCs, they also exhibit lower expression of PAX8 compared to all pure cases combined (P = 0.035).

Conclusion

Our data suggest that MT-EC exhibits the closest molecular and epidemiological similarities to pure USC and supports clinical observations that suggest patients with MT-EC should receive the same treatment as patients with pure serous carcinoma. Novel specific markers of MT-EC could be of diagnostic utility and could represent novel therapeutic targets in the future.

Histone h1.3 suppresses h19 noncoding RNA expression and cell growth of ovarian cancer cells

Ovarian cancer is a deadly gynecologic malignancy for which novel biomarkers and therapeutic targets are imperative for improving survival. Previous studies have suggested the expression pattern of linker histone variants as potential biomarkers for ovarian cancer. To investigate the role of histone H1 in ovarian cancer cells, we characterize individual H1 variants and overexpress one of the major somatic H1 variants, H1.3, in the OVCAR-3 epithelial ovarian cancer cell line. We find that overexpression of H1.3 decreases the growth rate and colony formation of OVCAR-3 cells. We identify histone H1.3 as a specific repressor for the noncoding oncogene H19. Overexpression of H1.3 suppresses H19 expression, and knockdown of H1.3 increases its expression in multiple ovarian epithelial cancer cell lines. Furthermore, we demonstrate that histone H1.3 overexpression leads to increased occupancy of H1.3 at the H19 regulator region encompassing the imprinting control region (ICR), concomitant with increased DNA methylation and reduced occupancy of the insulator protein CTCF at the ICR. Finally, we demonstrate that H1.3 overexpression and H19 knockdown synergistically decrease the growth rate of ovarian cancer cells. Our findings suggest that H1.3 dramatically inhibits H19 expression, which contributes to the suppression of epithelial ovarian carcinogenesis.

Regulation of tumor cell migration and invasion by the H19/let-7 axis is antagonized by metformin-induced DNA methylation

The imprinted, developmentally regulated H19 long noncoding RNA has been implicated in the pathogenesis of diverse human cancers, but the underlying mechanisms have remained poorly understood. Here, we report that H19 promotes tumor cell migration and invasion by inhibiting let-7, a potent tumor suppressor microRNA that functions to posttranscriptionally suppress the expression of oncogenes that regulate cell growth and motility. We show that H19 depletion impairs, whereas its overexpression enhances the motility and invasiveness of tumor cells. These phenomena occur, at least in part through affecting let-7-mediated regulation of metastasis-promoting genes, including Hmga2, c-Myc and Igf2bp3. This H19/let-7-dependent regulation is recapitulated in vivo where co-expressions of oncogenes and H19 exist in both primary human ovarian and endometrial cancers. Furthermore, we provide evidence that the anti-diabetic drug metformin inhibits tumor cell migration and invasion, partly by downregulating H19 via DNA methylation. Our results reveal a novel mechanism underpinning H19-mediated regulation in metastasis and may explain why in some cases increased let-7 expression unexpectedly correlates with poor prognosis, given the widely accepted role for let-7 as a tumor suppressor. Targeting this newly identified pathway might offer therapeutic opportunities.

Lentivirus-mediated RNA interference targeting the H19 gene inhibits cell proliferation and apoptosis in human choriocarcinoma cell line JAR

Background

H19 is a paternally imprinted gene that has been shown to be highly expressed in the trophoblast tissue. Results from previous studies have initiated a debate as to whether noncoding RNA H19 acts as a tumor suppressor or as a tumor promotor in trophoblast tissue. In the present study, we developed lentiviral vectors expressing H19-specific small interfering RNA (siRNA) to specifically block the expression of H19 in the human choriocarcinoma cell line JAR. Using this approach, we investigated the impact of the H19 gene on the proliferation, invasion and apoptosis of JAR cells. Moreover, we examined the effect of H19 knockdown on the expression of insulin-like growth factor 2 (IGF2), hairy and enhancer of split homologue-1 (HES-1) and dual-specific phosphatase 5 (DUSP5) genes.

Results

H19 knockdown inhibited apoptosis and proliferation of JAR cells, but had no significant impact on cell invasion. In addition, H19 knockdown resulted in significant upregulation of HES-1 and DUSP5 expression, but not IGF2 expression in JAR cells.

Conclusions

The finding that H19 downregulation could simultaneously inhibit proliferation and apoptosis of JAR cells highlights a putative dual function for H19 in choriocarcinoma and may explain the debate on whether H19 acts as a tumor suppressor or a tumor promotor in trophoblast tissue. Furthermore, upregulation of HES-1 and DUSP5 may mediate H19 downregulation-induced suppression of proliferation and apoptosis of JAR cells.

Detection of a long non-coding RNA (CCAT1) in living cells and human adenocarcinoma of colon tissues using FIT-PNA molecular beacons

Although the function and mechanism of action of long non-coding RNAs (lncRNA) is still not completely known, studies have shown their potential role in the control of gene expression and regulation, in cellular proliferation and invasiveness at the transcriptional level via multiple mechanisms. Recently, colon cancer associated transcript 1 (CCAT1) lncRNA was found to be expressed in colorectal cancer (CRC) tumors but not in normal tissue. This study aimed to study the ability of a CCAT1-specific peptide nucleic acid (PNA) based molecular beacons (TO-PNA-MB) to serve as a diagnostic probe for in vitro, ex vivo, and in situ (human colon biopsies) detection of CRC. The data showed enhanced fluorescence upon in vitro hybridization to RNA extracted from CCAT1 expressing cells (HT-29, SW-480) compared to control cells (SK-Mel-2). Uptake of TO-PNA-MBs into cells was achieved by covalently attaching cell penetrating peptides (CPPs) to the TO-PNA-MB probes. In situ hybridization of selected TO-PNA-MB in human CRC specimens was shown to detect CCAT1 expression in all (4/4) subjects with pre-cancerous adenomas, and in all (8/8) patients with invasive adenocarcinoma (penetrating the bowel wall) tumors. The results showed that CCAT1 TO-PNA-MB is a powerful diagnostic tool for the specific identification of CRC, suggesting that with the aid of an appropriate pharmaceutical vehicle, real time in vivo imaging is feasible. TO-PNA-MB may enable identifying occult metastatic disease during surgery, or differentiating in real time in vivo imaging, between benign and malignant lesions.

Regulation of H19 and its encoded microRNA-675 in osteoarthritis and under anabolic and catabolic in vitro conditions

Cartilage degeneration in the course of osteoarthritis (OA) is associated with an alteration in chondrocyte metabolism. In order to identify molecules representing putative key regulators for diagnosis and therapeutic intervention, we analyzed gene expression and microRNA (miR) levels in OA and normal knee cartilage using a customized cartilage cDNA array and quantitative RT-PCR. Among newly identified candidate molecules, H19, IGF2, and ITM2A were significantly elevated in OA compared to normal cartilage. H19 is an imprinted maternally expressed gene influencing IGF2 expression, whose transcript is a long noncoding (lnc) RNA of unknown biological function harboring the miR-675. H19 and IGF2 mRNA levels did not correlate significantly within cartilage samples suggesting that deregulation by imprinting effects are unlikely. A significant correlation was, however, observed for H19, COL2A1, and miR-675 expression levels in OA tissue, and functional regulation of these candidate molecules was assessed under anabolic and catabolic conditions. Culture of chondrocytes under hypoxic signaling showed co-upregulation of H19, COL2A1, and miRNA-675 levels in close correlation. Proinflammatory cytokines IL-1β and TNF-α downregulated COL2A1, H19, and miR-675 significantly without close statistical correlation. In conclusion, this is the first report demonstrating deregulation of an lncRNA and its encoded miR in the context of OA-affected cartilage. Stress-induced regulation of H19 expression by hypoxic signaling and inflammation suggests that lncRNA H19 acts as a metabolic correlate in cartilage and cultured chondrocytes, while the miR-675 may indirectly influence COL2A1 levels. H19 may not only be an attractive marker for cell anabolism but also a potential target to stimulate cartilage recovery.

microRNA expression profiling of endometrial endometrioid adenocarcinomas and serous adenocarcinomas reveals profiles containing shared, unique and differentiating groups of microRNAs

microRNAs (miRNAs) control a multitude of pathways in human cancers. Differential expression of miRNAs among different histological types of tumors within the same type of tissue offers insight into the mechanism of pathogenesis and may help to direct treatment to improve prognosis. We assessed expression of 667 miRNAs in endometrial endometrioid and serous adenocarcinomas using RNA extracted from benign endometrium as well as from primary endometrial tumors. Quantitative miRNA profiling of endometrial adenocarcinomas revealed four overlapping groups of significantly overexpressed and underexpressed miRNAs. The first group was composed of 20 miRNAs significantly dysregulated in both adenocarcinoma types compared with benign endometrium, two groups were composed of miRNAs significantly dysregulated in either endometrioid adenocarcinomas or in serous adenocarcinomas compared with benign endometrium, and the fourth group was composed of 17 miRNAs that significantly distinguished between endometrioid adenocarcinomas and serous adenocarcinomas themselves. Validation of the expression levels of the selected miRNAs was carried out in a second panel composed of ten endometrioid and five serous tumors. Experimentally validated mRNA targets of these dysregulated miRNAs were identified using published sources, whereas TargetScan was used to predict targets of miRNAs in the first and fourth profile groups. These validated and potential miRNA target lists were filtered using published lists of genes displaying significant overexpression or underexpression in endometrial cancers compared to benign endometrium. Our results revealed a number of dysregulated miRNAs that are commonly found in endometrial (and other) cancers as well as several dysregulated miRNAs not previously identified in endometrial cancers. Understanding these differences may permit the development of both prognostic and diagnostic biomarkers.

The functional role of long non-coding RNA in human carcinomas

Long non-coding RNAs (lncRNAs) are emerging as new players in the cancer paradigm demonstrating potential roles in both oncogenic and tumor suppressive pathways. These novel genes are frequently aberrantly expressed in a variety of human cancers, however the biological functions of the vast majority remain unknown. Recently, evidence has begun to accumulate describing the molecular mechanisms by which these RNA species function, providing insight into the functional roles they may play in tumorigenesis. In this review, we highlight the emerging functional role of lncRNAs in human cancer.

Toxin-based therapeutic approaches

Protein toxins confer a defense against predation/grazing or a superior pathogenic competence upon the producing organism. Such toxins have been perfected through evolution in poisonous animals/plants and pathogenic bacteria. Over the past five decades, a lot of effort has been invested in studying their mechanism of action, the way they contribute to pathogenicity and in the development of antidotes that neutralize their action. In parallel, many research groups turned to explore the pharmaceutical potential of such toxins when they are used to efficiently impair essential cellular processes and/or damage the integrity of their target cells. The following review summarizes major advances in the field of toxin based therapeutics and offers a comprehensive description of the mode of action of each applied toxin.

Oncofetal H19-derived miR-675 regulates tumor suppressor RB in human colorectal cancer

H19 is an imprinted oncofetal non-coding RNA recently shown to be the precursor of miR-675. The pathophysiological roles of H19 and its mature product miR-675 to carcinogenesis have, however, not been defined. By quantitative reverse transcription-polymerase chain reaction, both H19 and miR-675 were found to be upregulated in human colon cancer cell lines and primary human colorectal cancer (CRC) tissues compared with adjacent non-cancerous tissues. Subsequently, the tumor suppressor retinoblastoma (RB) was confirmed to be a direct target of miR-675 as the microRNA suppressed the activity of the luciferase reporter carrying the 3'-untranslated region of RB messenger RNA that contains the miR-675-binding site. Suppression of miR-675 by transfection with anti-miR-675 increased RB expression and at the same time, decreased cell growth and soft agar colony formation in human colon cancer cells. Reciprocally, enhanced miR-675 expression by transfection with miR-675 precursor decreased RB expression, increased tumor cell growth and soft agar colony formation. Moreover, the inverse relationship between the expressions of RB and H19/miR-675 was also revealed in human CRC tissues and colon cancer cell lines. Our findings demonstrate that H19-derived miR-675, through downregulation of its target RB, regulates the CRC development and thus may serve as a potential target for CRC therapy.

Development of targeted therapy for ovarian cancer mediated by a plasmid expressing diphtheria toxin under the control of H19 regulatory sequences

Background

Ovarian cancer ascites fluid (OCAF), contains malignant cells, is usually present in women with an advanced stage disease and currently has no effective therapy. Hence, we developed a new therapy strategy to target the expression of diphtheria toxin gene under the control of H19 regulatory sequences in ovarian tumor cells. H19 RNA is present at high levels in human cancer tissues (including ovarian cancer), while existing at a nearly undetectable level in the surrounding normal tissue.

Methods

H19 gene expression was tested in cells from OCAF by the in-situ hybridization technique (ISH) using an H19 RNA probe. The therapeutic potential of the toxin vector DTA-H19 was tested in ovarian carcinoma cell lines and in a heterotopic animal model for ovarian cancer.

Results

H19 RNA was detected in 90% of patients with OCAF as determined by ISH. Intratumoral injection of DTA-H19 into ectopically developed tumors caused 40% inhibition of tumor growth.

Conclusion

These observations may be the first step towards a major breakthrough in the treatment of human OCAF, while the effect in solid tumors required further investigation. It should enable us to identify likely non-responders in advance, and to treat patients who are resistant to all known therapies, thereby avoiding treatment failure.

H19 expression in hepatic metastases from a range of human carcinomas

AIMS

To investigate the expression of the imprinted oncofetal H19 gene in hepatic metastases derived from a range of human carcinomas and assess its prognostic value with the view of developing a DNA based treatment for such metastases.

METHODS

Non-radioactive in situ hybridisation for H19 RNA was performed on paraffin wax embedded sections of liver biopsies or partial hepatectomy specimens, taken from 80 patients with hepatic metastases derived from carcinomas from several medical centres in Israel. The degree of expression was graded qualitatively according to the number of cells expressing H19 and the intensity of staining. The medical files were searched for demographic data and survival times before and after diagnosis of hepatic metastases.

RESULTS

H19 expression was found in the hepatic metastases of 64 of 80 patients. High expression (higher staining grades) of H19 in the metastases was found in 43 of 80 patients. However, H19 expression status in the hepatic metastases did not correlate with either the length of time to development of metastasis or overall survival.

CONCLUSIONS

H19 is highly expressed in more than half of hepatic metastases derived from a range of carcinomas. Thus, these metastases may be suitable candidates for H19 DNA based treatment. Further studies are needed to determine whether H19 expression has prognostic value in metastatic liver disease using larger numbers of specific subtypes of primary carcinomas.

The non-coding RNAs as riboregulators

The non-coding RNAs database (http://biobases.ibch.poznan.pl/ncRNA/) contains currently available data on RNAs, which do not have long open reading frames and act as riboregulators. Non-coding RNAs are involved in the specific recognition of cellular nucleic acid targets through complementary base pairing to control cell growth and differentiation. Some of them are connected with several well known developmental and neuro-behavioral disorders. We have divided them into four groups. This paper is a short introduction to the database and presents its latest, updated edition.