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

EIF4A3 is stabilized by the long noncoding RNA BC200 to regulate gene expression during Epstein-Barr virus infection

Epstein‒Barr virus (EBV) regulates the expression of host genes involved in functional pathways for viral infection and pathogenicity. Long noncoding RNAs (lncRNAs) have been found to be important regulators of cellular biology. However, how EBV affects host biological processes via lncRNAs remains elusive. Eukaryotic initiation factor 4A3 (EIF4A3) was recently identified as an essential controller of cell fate with an unknown role in EBV infection. Here, the expression of lncRNA brain cytoplasmic 200 (BC200) was shown to be significantly upregulated in EBV-infected cell lines. RNA immunoprecipitation and RNA pulldown assays confirmed that BC200 bound to EIF4A3. Moreover, BC200 promoted EIF4A3 expression at the protein level but not at the mRNA level. Mechanistically, BC200 stabilized the EIF4A3 protein by impeding the K48-linked polyubiquitination of the K195 and K198 residues of EIF4A3. In addition, RNA-seq analysis of EBV-positive cells with knockdown of either BC200 or EIF4A3 revealed that a broad range of cellular genes were differentially regulated, particularly those related to virus infection and immune response pathways. This study is the first to reveal the key residues involved in EIF4A3 polyubiquitination and elucidate the novel regulatory role of EBV in host gene expression via the BC200/EIF4A3 axis. These results have implications for the pathogenesis and treatment of EBV-related diseases.

Long Noncoding RNA CTD-2589M5.4 Inhibits Ovarian Cancer Cell Proliferation, Migration, and Invasion Via Downregulation of the Extracellular Matrix-Receptor Interaction Pathway

Background: The authors' previous study showed that the long noncoding RNA CTD-2589M5.4 was significantly upregulated in multidrug-resistant ovarian cancer cells. However, the role of CTD-2589M5.4 in the progression of ovarian cancer remains unclear. The purpose of this current study was to illuminate the biological function and possible mechanism of CTD-2589M5.4 in ovarian cancer development. Materials and Methods: The expression of CTD-2589M5.4 was examined via real-time quantitative PCR in primary ovarian cancer tissues (POCTs) and ovarian cancer cell lines. The biological function of CTD-2589M5.4 was analyzed via CCK-8 proliferation, wound healing, transwell, and flow cytometry assays in CTD-2589M5.4-overexpressed/silenced and control ovarian cancer cells. The mechanism of CTD-2589M5.4 function in ovarian cancer progression was analyzed utilizing high-throughput RNA-sequencing, Kyoto Encyclopedia of Genes and Genomes analysis, qRT-PCR, Western blot, and rescue experiments. Results: CTD-2589M5.4 expression was decreased in the POCTs and ovarian cancer cells compared with the normal ovarian tissues (p < 0.05) and normal ovarian epithelial cells (p < 0.05). Overexpression of CTD-2589M5.4 inhibited the proliferation, invasion, and migration of ovarian cancer cells, while knockdown of CTD-2589M5.4 had the opposite effect. Furthermore, a total of 750 and 233 genes were notably upregulated and downregulated, respectively, in the CTD-2589M5.4-overexpressed A2780 cells, while the extracellular matrix (ECM)-receptor interaction pathway was significantly downregulated. In addition, overexpression of fibronectin 1 significantly abrogated the tumor suppressive function of CTD-2589M5.4. Conclusions: This study demonstrated that CTD-2589M5.4 could inhibit ovarian cancer cell proliferation, invasion, and migration, at least partially by way of downregulating the ECM-receptor interaction pathway, therefore providing a potential therapeutic target for the prevention and/or treatment of ovarian cancer.

Clinicopathological Significance and Prognostic Values of Long Noncoding RNA BCYRN1 in Cancer Patients: A Meta-Analysis and Bioinformatics Analysis

Background

Although combination therapies have substantially improved the clinical outcomes of cancer patients, the prognosis and early diagnosis remain unsatisfactory. As a result, it is critical to look for novel indicators linked to cancer. Despite a number of recent studies indicating that the lncRNA brain cytoplasmic RNA1(BCYRN1) may be a potential predictive biomarker in cancer patients, BCYRN1's prognostic value is still being debated.

Methods

We utilized PubMed, Embase, Web of Science, and the Cochrane Library to search for studies related to BCYRN1 until October 2021. Valid data were extracted after determining the articles according to the inclusion and exclusion criteria, and forest plots were made using Stata software. We used hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals to evaluate the relationship between abnormal BCYRN1 expression and patient prognosis and clinicopathological characteristics.

Results

Meta-analysis revealed that increased BCYRN1 expression was associated with both overall tumor survival (OS; HR = 1.84, 95% CI 1.51–2.25, p < 0.0001) and disease-free survival (DFS; HR = 1.65, 95% CI 1.20–2.26, p=0.002). Furthermore, a strong association was discovered between increased BCYRN1 expression and tumor invasion depth (OR = 2.11, 95% CI 1.49–2.99, p=0.000), clinical stage (OR = 2.52, 95% CI 1.18–5.37, p=0.017), and distant tumor metastasis (OR = 4.19, 95% CI 1.45–12.05, p=0.008).

Conclusions

We found that high BCYRN1 expression was associated with poor survival prognosis and aggressive clinicopathological characteristics in various cancers, indicating that it is a potential prognostic indicator as well as a therapeutic target. Further research is needed on pan-cancer cohorts to determine the clinical relevance of BCYRN1 in distinct cancer types.

Long Noncoding RNA LIFR-AS1: A New Player in Human Cancers

Emerging evidence has indicated that aberrantly expressed long noncoding RNAs (lncRNAs) play a vital role in various biological processes associated with tumorigenesis. Leukemia inhibitory factor receptor antisense RNA1 (LIFR-AS1) is a recently identified lncRNA transcribed in an antisense manner from the LIFR gene located on human chromosome 5p13.1. LIFR-AS1 regulates tumor proliferation, migration, invasion, apoptosis, and drug resistance through different mechanisms. Its expression level is related to the clinicopathological characteristics of tumors and plays a key role in tumor occurrence and development. In this review, we summarize the role of LIFR-AS1 in the development and progression of different cancers and highlight the potential for LIFR-AS1 to serve as a biomarker and therapeutic target for a variety of human cancers.

The Emerging Roles and Therapeutic Implications of Epigenetic Modifications in Ovarian Cancer

Ovarian cancer (OC) is one of the most lethal gynecologic malignancies globally. In spite of positive responses to initial therapy, the overall survival rates of OC patients remain poor due to the development of drug resistance and consequent cancer recurrence. Indeed, intensive studies have been conducted to unravel the molecular mechanisms underlying OC therapeutic resistance. Besides, emerging evidence suggests a crucial role for epigenetic modifications, namely, DNA methylation, histone modifications, and non-coding RNA regulation, in the drug resistance of OC. These epigenetic modifications contribute to chemoresistance through various mechanisms, namely, upregulating the expression of multidrug resistance proteins (MRPs), remodeling of the tumor microenvironment, and deregulated immune response. Therefore, an in-depth understanding of the role of epigenetic mechanisms in clinical therapeutic resistance may improve the outcome of OC patients. In this review, we will discuss the epigenetic regulation of OC drug resistance and propose the potential clinical implications of epigenetic therapies to prevent or reverse OC drug resistance, which may inspire novel treatment options by targeting resistance mechanisms for drug-resistant OC patients.

GATA1-induced upregulation of LINC01503 promotes carboplatin resistance in ovarian carcinoma by upregulating PD-L1 via sponging miR-766-5p

Background

Ovarian Carcinoma (OCa) is a high-mortality malignancy derived from female reproductive system. Increasing evidence has identified long non-coding RNAs (lncRNAs) as important regulators in OCa chemoresistance. In this study, we intended to explore the role of LINC01503 in OCa resistance to carboplatin (CBP).

Methods

Gene expression was measured by reverse transcription-quantitative PCR (RT-qPCR) in OCa cells. Western blot was adopted to detect protein levels of GATA1, PD-L1, E-cadherin, N-cadherin, Vimentin, Bcl-2, Bax, cleaved caspase-3. To assess the effects of LINC01503 on the resistance of OCa cells to CBP, Cell Counting Kit-8 (CCK-8), colony formation, Transwell, and flow cytometry experiments were performed to evaluate half-maximal inhibitory concentration (IC₅₀), cell viability, migrative and invasive ability, as well as cell apoptosis. Dual-luciferase reporter assay was employed to assess the associations between the genes.

Results

LINC01503 was upregulated in CBP-resistant OCa cells. LINC01503 knockdown reduced CBP resistance in OCa cells. Besides, GATA-binding protein 1 (GATA1) activated LINC01503 transcription in CBP-resistant OCa cells. MiR-766-5p was lowly expressed in CBP-resistant cells and confirmed as a target for LINC01503. In addition, miR-766-5p overexpression increased CBP sensitivity in OCa cells. PD-L1 was verified as the target of miR-766-5p. Besides, LINC01503 upregulated PD-L1 level by regulating miR-766-5p. Furthermore, rescue experiments showed that PD-L1 overexpression abrogated the inhibited impacts of blocking LINC01503 on CBP resistance in OCa cells.

Conclusion

GATA1-induced LINC01503 expedited CBP resistance in OCa cells via the miR-766-5p/PD-L1 axis, providing a new target for improving the efficacy of OCa chemotherapy.

Graphical Abstract

Ovarian cancer: epigenetics, drug resistance, and progression

Ovarian cancer (OC) is one of the most common malignant tumors in women. OC is associated with the activation of oncogenes, the inactivation of tumor suppressor genes, and the activation of abnormal cell signaling pathways. Moreover, epigenetic processes have been found to play an important role in OC tumorigenesis. Epigenetic processes do not change DNA sequences but regulate gene expression through DNA methylation, histone modification, and non-coding RNA. This review comprehensively considers the importance of epigenetics in OC, with a focus on microRNA and long non-coding RNA. These types of RNA are promising molecular markers and therapeutic targets that may support precision medicine in OC. DNA methylation inhibitors and histone deacetylase inhibitors may be useful for such targeting, with a possible novel approach combining these two therapies. Currently, the clinical application of such epigenetic approaches is limited by multiple obstacles, including the heterogeneity of OC, insufficient sample sizes in reported studies, and non-optimized methods for detecting potential tumor markers. Nonetheless, the application of epigenetic approaches to OC patient diagnosis, treatment, and prognosis is a promising area for future clinical investigation.

BCYRN1: An oncogenic lncRNA in diverse cancers

Brain cytoplasmic 200 (BC200) or alternatively named as brain cytoplasmic RNA 1 (BCYRN1) is a long non-coding RNA (lncRNA) primarily identified in the neurons. In addition to its participation in the pathogenesis of neurodegenerative disorders, it partake in the carcinogenesis process. Numerous in vitro studies have reported elevation of expression of BCYRN1 in cancer cell lines. Short hairpin-RNA-mediated silencing of BCYRN1 has attenuated growth of tumors in the animal models. Independent studies in esophageal squamous cell cancer, gastric cancer, colorectal cancer, hepatocellular carcinoma and non-small cell lung cancer have demonstrated association between elevated BCYRN1 levels and poor survival of patients. Taken together, BCYRN1 is an appropriate candidate for targeted therapies in the field of cancer.

RNA polymerase III transcription as a disease factor

In this review, Yeganeh et al. summarize different human diseases that have been linked to defects in the Pol III transcription apparatus or to Pol III products imbalance and discuss the possible underlying mechanisms.

RNA polymerase (Pol) III is responsible for transcription of different noncoding genes in eukaryotic cells, whose RNA products have well-defined functions in translation and other biological processes for some, and functions that remain to be defined for others. For all of them, however, new functions are being described. For example, Pol III products have been reported to regulate certain proteins such as protein kinase R (PKR) by direct association, to constitute the source of very short RNAs with regulatory roles in gene expression, or to control microRNA levels by sequestration. Consistent with these many functions, deregulation of Pol III transcribed genes is associated with a large variety of human disorders. Here we review different human diseases that have been linked to defects in the Pol III transcription apparatus or to Pol III products imbalance and discuss the possible underlying mechanisms.

LncRNA BCYRN1 inhibits glioma tumorigenesis by competitively binding with miR-619-5p to regulate CUEDC2 expression and the PTEN/AKT/p21 pathway

Glioma is the most common malignant tumor in the central nervous system. Altered long noncoding RNAs (lncRNAs) are playing regulatory roles in physiological and pathogenic processes in cancer. Here, we uncovered a differentially expressed lncRNA called brain cytoplasmic RNA 1 (BCYRN1), and elucidated its function and molecular mechanism in the progression and development of glioma. Three fresh tumor tissues from glioma patients and three normal brain tissues from craniocerebral trauma patients were prepared for high-throughput RNA sequencing. Differential RNA transcripts and BCYRN1 were identified by RT-qPCR in glioma samples and controls. CCK-8, colony formation assays, flow cytometry, TUNEL assays, cell migration assays, wound-healing assays, and xenograft model were established to investigate the biological function of BCYRN1 both in vitro and in vivo. Various bioinformatics analysis, dual-luciferase reporter assays, biotinylated RNA pulldown assays, and rescue experiments were conducted to reveal the underlying mechanisms of competitive endogenous RNAs (ceRNAs). 183 lncRNAs were identified with significant dysregulation in glioma and randomly selected differential RNAs were further confirmed by RT-qPCR. Among them, BCYRN1 was the most downregulated lncRNA, and its low expression positively correlated with glioma progression. Functionally, BCYRN1 overexpression inhibited cell proliferation, migration in glioma cell lines, whereas BCYRN1 depletion resulted in the opposite way. MiR-619-5p was further confirmed as the direct target of BCYRN1. Mechanistically, miR-619-5p specifically targeted the CUE domain containing protein 2 (CUEDC2), and BCYRN1/miR-619-5p suppressed glioma tumorigenesis by inactivating PTEN/AKT/p21 pathway in a CUEDC2-dependent manner. Overall, our data presented that the reduced expression of BCYRN1 was associated with poor patient outcome in glioma. BCYRN1 functioned as a ceRNA to inhibit glioma progression by sponging miR-619-5p to regulate CUEDC2 expression and PTEN/AKT/p21 pathway. Our results indicated that BCYRN1 exerted tumor suppressor potential and might be a candidate in the diagnosis and treatment of glioma.

BCYRN1 is correlated with progression and prognosis in gastric cancer

Long non-coding RNA brain cytoplasmic RNA 1 (BCYRN1) has been found to play an important role in tumorigenesis of a variety of tumors including gastric cancer (GC). However, the prognostic significance and molecular mechanism of BCYRN1 was still unknown in GC. In the present study, we found BCYRN1 expression was dramatically elevated in GC tissues and cell lines, and positively associated with tumor depth, lymph node metastasis and clinical stage in patients with GC. Moreover, univariate and multivariate Cox regression analyses demonstrated that high BCYRN1 expression was independent prognostic factor for overall survival in GC patients. In lncRNA-microRNA interactome database, we found that there were putative binding sites between BCYRN1 and miR-204-5p. Furthermore, we confirmed that down-regulation of BCYRN1 inhibited GC cell proliferation, migration and invasion through directly up-regulated miR-204-5p expression. In conclusion, BCYRN1 acts as a promising prognostic predictor in GC patients and regulated GC cell proliferation, cell cycle, migration and invasion through targeting miR-204-5p.

Back to the Future: Rethinking the Great Potential of lncRNAS for Optimizing Chemotherapeutic Response in Ovarian Cancer

Ovarian cancer (OC) is one of the most fatal cancers in women worldwide. Currently, platinum- and taxane-based chemotherapy is the mainstay for the treatment of OC. Yet, the emergence of chemoresistance results in therapeutic failure and significant relapse despite a consistent rate of primary response. Emerging evidence substantiates the potential role of lncRNAs in determining the response to standard chemotherapy in OC. The objective of this narrative review is to provide an integrated, synthesized overview of the current state of knowledge regarding the role of lncRNAs in the emergence of resistance to platinum- and taxane-based chemotherapy in OC. In addition, we sought to develop conceptual frameworks for harnessing the therapeutic potential of lncRNAs in strategies aimed at enhancing the chemotherapy response of OC. Furthermore, we offered significant new perspectives and insights on the interplay between lncRNAs and the molecular circuitries implicated in chemoresistance to determine their impacts on therapeutic response. Although this review summarizes robust data concerning the involvement of lncRNAs in the emergence of acquired resistance to platinum- and taxane-based chemotherapy in OC, effective approaches for translating these lncRNAs into clinical practice warrant further investigation.

LncRNA BC200 Promotes Esophageal Squamous Cell Cancer Migration and Invasion and Can Regulate ATF4 Expression

Background: The main reason for esophageal squamous cell carcinoma (ESCC) treatment failure is metastasis. Little is known about the mechanisms involved in the metastasis of ESCC, and there is a lack of effective therapeutic targets. In our previous study, we found that patients with high levels of BC200 tended to have poor prognoses.

Methods: First, we applied qRT-PCR to detect the expression level of BC200 in normal esophageal squamous epithelial cells and ESCC cells with different degrees of differentiation ability. Then, we changed BC200 expression by transfecting constructed lentiviruses that included BC200 shRNA (LV-BC200-shRNA, KD), negative control (CON053, NC), or BC200 gene (LV-BC200, BC200) to create BC200-deficient cell models in KYSE410 and KYSE70 cells and BC200 overexpression cell models in EC9706 cells and verified the transfection effect by qRT-PCR. Then, we examined cell migration by wound healing assay, invasion by Transwell assay, and proliferation by MTT assay and examined the metastasis ability in a xenograft mouse model. Gene expression profiling was performed to screen a panel of mRNAs following inhibition of BC200 expression. We then used ingenuity pathway analysis (IPA) to analyze the functions of the changed molecules and their interactions. The results from the microarray were validated by qRT-PCR and Western blotting.

Results: In this study, we found that the expression of BC200 in poorly differentiated cell lines was significantly higher than that in well-differentiated cell lines. BC200 can significantly promote the migration and invasion but not the proliferation ability of ESCC cells in vitro and BC200 shRNA can significantly suppress tumor metastasis in vivo. Our genome-wide expression profile chip showed 406 differentially expressed genes, with 91 upregulated genes and 315 downregulated genes. The upstream regulator analysis showed that ATF4 was predicted to be strongly inhibited and 21 genes were consistently inhibited by this gene. Our qRT-PCR and Western blotting data also identified the reduced expression of ATF4 and some selected downstream genes, such as SNAIL2, GADD45A, and PSAT1, as a consequence of downregulating BC200 expression in ESCC.

Conclusion: Our data showed that BC200 promoted the metastasis of ESCC cells and could regulate the expression of ATF4 and its downstream genes.

The functional role of long noncoding RNA in resistance to anticancer treatment

Chemotherapy is one of the fundamental methods of cancer treatment. However, drug resistance remains the main cause of clinical treatment failure. We comprehensively review the newly identified roles of long noncoding RNAs (lncRNAs) in oncobiology that are associated with drug resistance. The expression of lncRNAs is tissue-specific and often dysregulated in human cancers. Accumulating evidence suggests that lncRNAs are involved in chemoresistance of cancer cells. The main lncRNA-driven mechanisms of chemoresistance include regulation of drug efflux, DNA damage repair, cell cycle, apoptosis, epithelial-mesenchymal transition (EMT), induction of signaling pathways, and angiogenesis. LncRNA-driven mechanisms of resistance to various antineoplastic agents have been studied extensively. There are unique mechanisms of resistance against different types of drugs, and each mechanism may have more than one contributing factor. We summarize the emerging strategies that can be used to overcome the technical challenges in studying and addressing lncRNA-mediated drug resistance.

Functional Analysis of RNA Motifs Essential for BC200 RNA-mediated Translational Regulation

Brain cytoplasmic 200 RNA (BC200 RNA) is proposed to act as a local translational modulator by inhibiting translation after being targeted to neuronal dendrites. However, the mechanism by which BC200 RNA inhibits translation is not fully understood. Although a detailed functional analysis of RNA motifs is essential for understanding the BC200 RNA-mediated translation-inhibition mechanism, there is little relevant research on the subject. Here, we performed a systematic domain-dissection analysis of BC200 RNA to identify functional RNA motifs responsible for its translational-inhibition activity. Various RNA variants were assayed for their ability to inhibit translation of luciferase mRNA in vitro. We found that the 111–200-nucleotide region consisting of part of the Alu domain as well as the A/C-rich domain (consisting of both the A-rich and C-rich domains) is most effective for translation inhibition. Surprisingly, we also found that individual A-rich, A/C-rich, and Alu domains can enhance translation but at different levels for each domain, and that these enhancing effects manifest as cap-dependent translation.

Long Non-coding RNAs Involved in Resistance to Chemotherapy in Ovarian Cancer

Ovarian cancer (OC) accounts for more than 150,000 deaths worldwide every year. Patients are often diagnosed at an advanced stage with metastatic dissemination. Although platinum- and taxane-based chemotherapies are effective treatment options, they are rarely curative and eventually, the disease will progress due to acquired resistance. Emerging evidence suggests a crucial role of long non-coding RNAs (lncRNAs) in the response to therapy in OC. Transcriptome profiling studies using high throughput approaches have identified differential expression patterns of lncRNAs associated with disease recurrence. Furthermore, several aberrantly expressed lncRNAs in resistant OC cells have been related to increased cell division, improved DNA repair, up-regulation of drug transporters or reduced susceptibility to apoptotic stimuli, supporting their involvement in acquired resistance. In this review, we will discuss the key aspects of lncRNAs associated with the development of resistance to platinum- and taxane-based chemotherapy in OC. The molecular landscape of OC will be introduced, to provide a background for understanding the role of lncRNAs in the acquisition of malignant properties. We will focus on the interplay between lncRNAs and molecular pathways affecting drug response to evaluate their impact on treatment resistance. Additionally, we will discuss the prospects of using lncRNAs as biomarkers or targets for precision medicine in OC. Although there is still plenty to learn about lncRNAs and technical challenges to be solved, the evidence of their involvement in OC and the development of acquired resistance are compelling and warrant further investigation for clinical applications.

BC200 overexpression contributes to luminal and triple negative breast cancer pathogenesis

Background

Long non coding RNAs (lncRNAs) are RNA molecules longer than 200 nucleotides that are not translated into proteins, but regulate the transcription of genes involved in different cellular processes, including cancer. Epidemiological analyses have demonstrated that parous women have a decreased risk of developing breast cancer in postmenopausal years if they went through a full term pregnancy in their early twenties. We here provide evidence of the role of BC200 in breast cancer and, potentially, in pregnancy’s preventive effect in reducing the lifetime risk of developing breast cancer.

Methods

Transcriptome analysis of normal breast of parous and nulliparous postmenopausal women revealed that several lncRNAs are differentially expressed in the parous breast. RNA sequencing of healthy postmenopausal breast tissue biopsies from eight parous and eight nulliparous women showed that there are 42 novel lncRNAs differentially expressed between these two groups. Screening of several of these 42 lncRNAs by RT-qPCR in different breast cancer cell lines, provided evidence that one in particular, lncEPCAM (more commonly known as BC200), was a strong candidate involved in cancer progression. Proliferation, migration, invasion and xerograph studies confirmed this hypothesis.

Results

The poorly studied oncogenic BC200 was selected to be tested in vitro and in vivo to determine its relevance in breast cancer and also to provide us with an understanding of its role in the increased susceptibility of the nulliparous women to cancer. Our results show that BC200 is upregulated in nulliparous women, and breast cancer cells and tissue. The role of BC200 is not completely understood in any of the breast cancer subtypes. We here provide evidence that BC200 has a role in luminal breast cancer as well as in the triple negative breast cancer subtype.

Conclusion

When overexpressed in luminal and triple negative breast cancer cell lines, BC200 shows increased proliferation, migration, and invasion in vitro. In vivo, overexpression of BC200 increased tumor size. Although treatment for cancer using lncRNAs as targets is in its infancy, the advancement in knowledge and technology to study their relevance in disease could lead to the development of novel treatment and preventive strategies for breast cancer.

Role of BCYRN1 in hepatocellular carcinoma pathogenesis by lncRNA-miRNA-mRNA network analysis and its diagnostic and prognostic value

Aim: This study aimed to excavate the roles of BCYRN1 in hepatocellular carcinoma (HCC). Methods: A comprehensive strategy of microarray data mining, computational biology and experimental verification were adopted to assess the clinical significance of BCYRN1 and identify related pathways. Results: BCYRN1 was upregulated in HCC and its expression was positively associated with both tumor, node, metastasis and worse survival rate in patients with HCC. Through combing plasma BCYRN1 with alpha fetoprotein, the diagnosis of HCC was remarkably improved. BCYRN1 may regulate some cancer-related pathways to promote HCC initiation via an lncRNA-miRNA-mRNA network. Conclusion: Our results propose BCYRN1 as a potential diagnostic and prognostic biomarker and offer a novel perspective to explore the etiopathogenesis of HCC.

MEG3: an Oncogenic Long Non-coding RNA in Different Cancers

Long noncoding RNAs (lncRNAs) have recently considered as central regulators in diverse biological processes and emerged as vital players controlling tumorigenesis. Several lncRNAs can be classified into oncogenes and tumor suppressor genes depending on their function in cancer. A maternally expressed gene 3 (MEG3) gene transcripts a 1.6 kb lncRNA whose act as an antitumor component in different cancer cells, such as breast, liver, glioma, colorectal, cervical, gastric, lung, ovarian and osteosarcoma cancer cells. The present review highlights biological function of MEG3 to repress tumor through regulating the major tumor suppressor genes p53 and Rb, inhibiting angiogenesis-related factor, or controlling miRNAs. On the other hand, previous studies have also suggested that MEG3 mediates epithelial-mesenchymal transition (EMT). However, deregulation of MEG3 is associated with the  development and progression of cancer, suggesting that MEG3 may function as a potential biomarker and therapeutic target for human cancers.

BC200 RNA: An Emerging Therapeutic Target and Diagnostic Marker for Human Cancer

One of the most interesting findings from genome-wide expression analysis is that a considerable amount of noncoding RNA (ncRNA) is present in the cell. Recent studies have identified diverse biological functions of ncRNAs, which are expressed in a much wider array of forms than proteins. Certain ncRNAs associated with diseases, in particular, have attracted research attention as novel therapeutic targets and diagnostic markers. BC200 RNA, a 200-nucleotide ncRNA originally identified as a neuron-specific transcript, is abnormally over-expressed in several types of cancer tissue. A number of recent studies have suggested mechanisms by which abnormal expression of BC200 RNA contributes to the development of cancer. In this article, we first provide a brief review of a recent progress in identifying functions of BC200 RNA in cancer cells, and then offer examples of other ncRNAs as new therapeutic targets and diagnostic markers for human cancer. Finally, we discuss future directions of studies on BC200 RNA for new cancer treatments.

Long noncoding RNA SNHG15 serves as an oncogene and predicts poor prognosis in epithelial ovarian cancer

Objective

This study aims to investigate the functional role of long noncoding RNA SNHG15 in epithelial ovarian cancer (EOC).

Materials and methods

The expression of SNHG15 was measured in EOC cells and tissues using qRT-PCR. The correlation of SNHG15 expression and the clinicopathological characters was statistically analyzed. The prognosis of patients with different clinical features in the high/low SNHG15 expression groups were calculated. Moreover, univariate and multivariate Cox regression analyses were performed to identify the risk factors for poor overall survival (OS) and progression-free survival (PFS). The effect of SNHG15 on the migration and invasion was evaluated using Transwell and Matrigel, respectively. The proliferation ability of EOC cells was tested using colony formation and MTT assay. The influence of SNHG15 on the cisplatin resistance was detected by measuring cell inhibition rate and cell viability.

Results

SNHG15 was upegulated in EOC cells and tissues. High SNHG15 expression was correlated with EOC progression and predicted poor OS and PFS in different subgroups of EOC patients. Moreover, multivariate Cox regression analysis defined high SNHG15 expression as an independent risk factor for poor OS and PFS. Furthermore, functional assays showed that the overexpression of SNHG15 promoted migration and invasion, while the loss of SNHG15 suppressed migration and invasion. Furthermore, the proliferation of EOC cells was improved after the ectopic expression of SNHG15, which was suppressed with SNHG15 deficiency. In addition, cisplatin-resistant EOC cells were established for detecting the effect of SNHG15 on EOC chemoresistance. The results showed that cisplatin-resistant EOC cells exhibited much higher levels of SNHG15 expression than controls, and SNHG15 contributed to the chemoresistance of EOC cells.

Conclusion

This study confirms that SNHG15 contributes to the migration, invasion, proliferation, and chemoresistance of EOC. SNHG15 may serve as a potential therapeutic target and prognostic biomarker of EOC patients.

Prediction of secondary and tertiary structures of human BC200 RNA (BCYRN1) based on experimental and bioinformatic cross-validation

Based on experimental and bioinformatic approaches, we present the first empirically established complete secondary structure of human BC200 RNA. BC200 RNA is a brain-specific non-messenger RNA with a confirmed regulatory role in dendritic translation in neurons. Although the involvement of human BC200 RNA in various types of tumour and Alzheimer's disease has been repeatedly confirmed, the exact secondary structure remains not fully elucidated. To determine the secondary structure of BC200 RNA in vitro, we performed partial hydrolysis with sequence-specific nucleases and lead-induced cleavage. We also examined the availabilities of putative single-stranded regions and base-pairing interactions via specific DNAzymes and RNase H assay. To determine the complete spatial folding of BC200 RNA, we used experimental data as constraints in structure prediction programs and performed a comparison of results obtained by several algorithms using different criteria. Based on the experimental-derived secondary structure of BC200 RNA, we also predicted the tertiary structure of BC200 RNA. The presented combination of experimental and bioinformatic approaches not only enabled the determination of the most reliable secondary and tertiary structures of human BC200 RNA (largely in agreement with the previous phylogenetic model), but also verified the compatibility and potential disadvantages of utilizing in silico structure prediction programs.

BC200 (BCYRN1) - The shortest, long, non-coding RNA associated with cancer

With the discovery that the level of RNA synthesis in human cells far exceeds what is required to express protein-coding genes, there has been a concerted scientific effort to identify, catalogue and uncover the biological functions of the non-coding transcriptome. Long, non-coding RNAs (lncRNAs) are a diverse group of RNAs with equally wide-ranging biological roles in the cell. An increasing number of studies have reported alterations in the expression of lncRNAs in various cancers, although unravelling how they contribute specifically to the disease is a bigger challenge. Originally described as a brain-specific, non-coding RNA, BC200 (BCYRN1) is a 200-nucleotide, predominantly cytoplasmic lncRNA that has been linked to neurodegenerative disease and several types of cancer. Here we summarise what is known about BC200, primarily from studies in neuronal systems, before turning to a review of recent work that aims to understand how this lncRNA contributes to cancer initiation, progression and metastasis, along with its possible clinical utility as a biomarker or therapeutic target.

The Network of Non-coding RNAs in Cancer Drug Resistance

Non-coding RNAs (ncRNAs) have been implicated in most cellular functions. The disruption of their function through somatic mutations, genomic imprinting, transcriptional and post-transcriptional regulation, plays an ever-increasing role in cancer development. ncRNAs, including notorious microRNAs, have been thus proposed to function as tumor suppressors or oncogenes, often in a context-dependent fashion. In parallel, ncRNAs with altered expression in cancer have been reported to exert a key role in determining drug sensitivity or restoring drug responsiveness in resistant cells. Acquisition of resistance to anti-cancer drugs is a major hindrance to effective chemotherapy and is one of the most important causes of relapse and mortality in cancer patients. For these reasons, non-coding RNAs have become recent focuses as prognostic agents and modifiers of chemo-sensitivity. This review starts with a brief outline of the role of most studied non-coding RNAs in cancer and then highlights the modulation of cancer drug resistance via known ncRNAs based mechanisms. We identified from literature 388 ncRNA-drugs interactions and analyzed them using an unsupervised approach. Essentially, we performed a network analysis of the non-coding RNAs with direct relations with cancer drugs. Within such a machine-learning framework we detected the most representative ncRNAs-drug associations and groups. We finally discussed the higher integration of the drug-ncRNA clusters with the goal of disentangling effectors from downstream effects and further clarify the involvement of ncRNAs in the cellular mechanisms underlying resistance to cancer treatments.

miR-211 sponges lncRNA MALAT1 to suppress tumor growth and progression through inhibiting PHF19 in ovarian carcinoma

Accumulating evidence has indicated that microRNAs (miRNAs) play an important role in the occurrence and progression of ovarian cancer (OC). However, the function of miRNAs implicated in OC remains unclear. This study investigated the potential role of miR-211 in OC. Gene Expression Omnibus database analysis indicated that miR-211 expression was significantly down-regulated in OC tissues compared with normal specimens. In addition, miR-211 overexpression apparently inhibited proliferation, migration, xenograft growth, and induced apoptosis in HEY-T30 and SKOV3 cells. Moreover, PHF19, a component of the polycomb group of proteins, was found to be a direct target of miR-211 based on the luciferase reporter assay and Western blot analysis. Consistently, survival analysis indicated that high PHF19 expression was associated with shorter survival time in patients with OC. Importantly, silence of PHF19 reduced proliferation, induced cell cycle arrest, promoted apoptosis, suppressed migration, and inhibited xenograft growth in SKOV3 cells. Restoration of PHF19 expression markedly reversed the inhibitory effect of miR-211 on OC. Moreover, our results indicate that the long noncoding RNA MALAT1 could sponge miR-211 as a competing endogenous RNA and potentially up-regulate PHF19 expression, thus facilitating the OC progression. These findings suggest that the MALAT1/miR-211/PHF19 axis may act as a key mediator in OC and provide new insight into the prevention of this disease.-Tao, F., Tian, X., Ruan, S., Shen, M., Zhang, Z. miR-211 sponges lncRNA MALAT1 to suppress tumor growth and progression through inhibiting PHF19 in ovarian carcinoma.

Linc00483 as ceRNA regulates proliferation and apoptosis through activating MAPKs in gastric cancer

Long non‐coding RNAs (lncRNAs) are important regulators of many cellular processes, and their aberrant expression and/or function is associated with many different diseases, including cancer. However, the identification of functional lncRNAs in gastric cancer is still a challenge. In this study, we describe a novel functional lncRNA, linc00483, that is upregulated and associated with tumorigenesis, tumour size, metastasis and poor prognosis in gastric cancer. In our study, linc00483 promoted gastric cancer cell proliferation, invasiveness and metastasis in vitro and in vivo. Mechanistically, upregulated expression of linc00483 in gastric cancer acts as a sponge to absorb endogenous tumour suppressor miR‐30a‐3p. Furthermore, it restores SPAG9 expression, which is negatively regulated by miR‐30a‐3p, and actives MAPK signaling pathway in gastric cancer cells. Thus, linc00483 is an oncogenic lncRNA in gastric cancer and targeting linc00483 or its pathway can potentially be useful in development of targeted therapies for patients with gastric cancer. Our results show that linc00483 is an important regulator in carcinogenesis and may be a useful biomarker to predict prognosis of gastric cancer patients. We believe our findings are novel and will be of interest to scientists working in many areas related to biomarkers in cancer.

Involvement of non-coding RNAs in chemotherapy resistance of ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological malignancy, with a low 5-year survival rate. Most patients with ovarian cancer are diagnosed in late-stages. A rising number of non-coding RNAs (ncRNAs) have been found to act as key regulators of gene expression by applying novel high-thought methods, such as next generation sequencing (NGS). Non-coding RNAs not only play important roles in carcinogenesis, but also affect the clinical treatment strategies. One of the biggest challenge in OC treatment was chemoresistance, which causes poor prognosis and high recurrence rate after applying traditional remedies. Of note, it has been proved that ncRNAs were deeply correlated with chemoresistance in several cancers, which made ncRNAs considered to be potential therapeutic targets in ovarian cancer. Among of all ncRNAs, the studies of miRNAs and lncRNAs in ovarian cancer chemoresistance were much clearer. In this study, we reviewed the most relevant researches in this field, and described the relationships between ncRNAs and chemoresistance in ovarian cancer.

Role of lncRNAs in ovarian cancer: defining new biomarkers for therapeutic purposes

Long noncoding RNAs (lncRNAs) are a class of noncoding RNA, involved in regulation of diverse physiological and pathological processes. Ovarian cancer is the leading cause of death among all gynecological malignancies in the world and its underlying mechanism is still unclear. LncRNAs exhibit multiple biological functions in various stages of ovarian cancer development. We will discuss and summarize the new and important lncRNAs and their involvement in disease, which might represent promising therapeutic targets. Therapeutic intervention based on silencing or functional inhibition of target lncRNAs will be beneficial for ovarian cancer patients.

Identifying the cellular location of brain cytoplasmic 200 RNA using an RNA-recognizing antibody

Brain cytoplasmic 200 RNA (BC200 RNA) is a neuron-specific non-coding RNA, implicated in the inhibition of local synaptodendritic protein synthesis, and is highly expressed in some cancer cells. Although BC200 RNA has been shown to inhibit translation in vitro, the cellular location of this inhibition is unknown. In this study, we used a BC200 RNA-recognizing antibody to identify the cellular locations of BC200 RNA in HeLa cervical carcinoma cells. We observed punctate signals in both the cytoplasm and nucleus, and further discovered that BC200 RNA co-localized with the p-body decapping enzyme, DCP1A, and the heterogeneous nuclear ribonucleoprotein E2 (hnRNP E2). The latter is a known BC200 RNA-binding partner protein and a constituent of p-bodies. This suggests that BC200 RNA is localized to p-bodies via hnRNP E2. [BMB Reports 2017; 50(6): 318-322].

Dysregulated Expression of Long Noncoding RNAs in Ovarian Cancer

Ovarian cancer is the leading cause of death among women with gynecologic malignancies. The development and progression of ovarian cancer are complex and a multiple-step process. New biomarker molecules for diagnostic and prognostic are essential for novel therapeutic targets and to extend the survival time of patients with ovarian cancer. Long noncoding RNAs (lncRNAs) are non–protein-coding transcripts longer than 200 nucleotides that have recently been found as key regulators of various biological processes and to be involved in the development and progression of many diseases including cancers. In this review, we summarized the expression pattern of several dysregulated lncRNAs (HOTAIR, H19, XIST, and HOST2) and the functional molecular mechanism of these lncRNAs on the initiation and progression of ovarian cancer. The lncRNAs as biomarkers may be used for current and future clinical diagnosis, therapeutics, and prognosis.

The long non-coding RNA BC200 (BCYRN1) is critical for cancer cell survival and proliferation

BACKGROUND

BC200 is a long non-coding RNA expressed at high levels in the brain and elevated in a variety of tumour types. BC200 has a hypothesized role in translational regulation; however, to date the functional role of BC200 in both normal and diseased states remains poorly characterized.

METHODS

Detailed BC200 expression analyses were performed in tumor cell lines, primary and non-tumorigenic cultured breast and lung cells, and a panel of normal human tissues by quantitative real-time PCR and confirmed by northern blot. Subcellular fractionation was performed to assess BC200 distribution and efficient knock-down of BC200 was established using both locked nucleic acid (LNA) GapmeRs and conventional siRNAs. Cell viability following BC200 knockdown and overexpression was assessed by MTT assay and induction of apoptosis was monitored by Annexin V/PI staining and flow cytometry. Cell cycle arrest and synchronization were performed using serum withdrawal as well as the specific inhibitors Lovastatin, Thymidine, RO3306 and Nocodazole. Synchronization was monitored by fluorescent analysis of cellular DNA content by flow cytometry RESULTS: BC200 expression was substantially upregulated in brain and elevated expression was also observed in testes, small intestine and ovary. Expression in cultured tumour cells was dramatically higher than corresponding normal tissue; however, expression in cultured primary cells was similar to that in immortalized and cancer cell lines. BC200 knockdown resulted in a dramatic loss of viability through growth arrest and induction of apoptosis that could be partially rescued by overexpression of wild-type BC200 but not an siRNA-resistant sequence mutant. A substantial decrease in BC200 expression was observed upon cell confluence or serum deprivation, as well as drug induced cell cycle arrest in G1 or G2 but not S- or M-phases. Upon release from cell cycle arrest, BC200 expression was recovered as cells entered S-phase, but did not follow a periodic expression pattern during synchronized progression through the cell cycle. This elevated expression was critical for the survival of proliferating cancerous and non-cancerous cells, but is dispensable upon senescence or cell cycle arrest.

CONCLUSIONS

BC200 expression is elevated in proliferating cultured cells regardless of origin. In primary cells, expression is dramatically reduced upon cell cycle arrest by confluence, serum deprivation or chemical inhibition. The lethality of BC200 knockdown is restricted to actively proliferating cells, making it a promising therapeutic target for a broad spectrum of cancers.

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.

Influence of microRNAs and Long Non-Coding RNAs in Cancer Chemoresistance

Innate and acquired chemoresistance exhibited by most tumours exposed to conventional chemotherapeutic agents account for the majority of relapse cases in cancer patients. Such chemoresistance phenotypes are of a multi-factorial nature from multiple key molecular players. The discovery of the RNA interference pathway in 1998 and the widespread gene regulatory influences exerted by microRNAs (miRNAs) and other non-coding RNAs have certainly expanded the level of intricacy present for the development of any single physiological phenotype, including cancer chemoresistance. This review article focuses on the latest research efforts in identifying and validating specific key molecular players from the two main families of non-coding RNAs, namely miRNAs and long non-coding RNAs (lncRNAs), having direct or indirect influences in the development of cancer drug resistance properties and how such knowledge can be utilised for novel theranostics in oncology.

Long noncoding RNA expression signature to predict platinum-based chemotherapeutic sensitivity of ovarian cancer patients

Dysregulated long noncoding RNAs (lncRNAs) are potential markers of several tumor prognoses. This study aimed to develop a lncRNA expression signature that can predict chemotherapeutic sensitivity for patients with advanced stage and high-grade serous ovarian cancer (HGS-OvCa) treated with platinum-based chemotherapy. The lncRNA expression profiles of 258 HGS-OvCa patients from The Cancer Genome Atlas were analyzed. Results revealed that an eight-lncRNA signature was significantly associated with chemosensitivity in the multivariate logistic regression model, which can accurately predict the chemosensitivity of patients [Area under curve (AUC) = 0.83]. The association of a chemosensitivity predictor with molecular subtypes indicated the excellent prognosis performance of this marker in differentiated, mesenchymal, and immunoreactive subtypes (AUC > 0.8). The significant correlation between ZFAS1 expression and chemosensitivity was confirmed in 233 HGS-OvCa patients from the Gene Expression Omnibus datasets (GSE9891, GSE63885, and GSE51373). In vitro experiments demonstrated that the ZFAS1 expression was upregulated by cisplatin in A2008, HeyA8, and HeyC2 cell lines. This finding suggested that ZFAS1 may participate in platinum resistance. Therefore, the evaluation of the eight-lncRNA signature may be clinically implicated in the selection of platinum-resistant HGS-OvCa patients. The role of ZFAS1 in platinum resistance should be further investigated.

Regulation of BC200 RNA-mediated translation inhibition by hnRNP E1 and E2

The long noncoding RNA BC200 (brain cytoplasmic RNA, 200 nucleotides) acts as a translational modulator of local protein synthesis at dendrites. BC200 RNA has been shown to inhibit translation in vitro, but it remains unknown how this translation inhibition might be controlled in a cell. Here, we performed yeast three-hybrid screening and identified hnRNP E1 and hnRNP E2 as BC200 RNA-interacting proteins. We found that: these hnRNA proteins could restore BC200 RNA-inhibited translation; BC200 RNA interacts with hnRNP E1 and E2 mainly through its unique 3' C-rich domain; and the RNA binding specificities and modes of the two proteins differed somewhat. Our results offer new insights into the regulation of BC200 RNA-mediated translation inhibition.

Novel mechanisms and approaches to overcome multidrug resistance in the treatment of ovarian cancer

Ovarian cancer remains the leading cause of gynecological cancer-related mortality despite the advances in surgical techniques and chemotherapy drugs over the past three decades. Multidrug resistance (MDR) to chemotherapy is the major cause of treatment failure. Previous research has focused mainly on strategies to reverse MDR by targeting the MDR1 gene encoded P-glycoprotein (Pgp) with small molecular compound inhibitors. However, prior Pgp inhibitors have shown very limited clinical success because these agents have relatively low potency and high toxicity. Therefore, identification of more specific and potent new inhibitors would be useful. In addition, emerging evidence suggests that cancer stem cells (CSCs), deregulated non-coding RNA (ncRNA), autophagy, and tumor heterogeneity also contribute significantly to drug sensitivity/resistance in ovarian cancer. This review summarizes these novel mechanisms of MDR and evaluates several new concepts to overcome MDR in the treatment of ovarian cancer. These new strategies include overcoming MDR with more potent and specific Pgp inhibitors, targeting CSCs and ncRNA, modulating autophagy signaling pathway, and targeting tumor heterogeneity.