Long non-coding RNA CCAT1 promotes metastasis and poor prognosis in epithelial ovarian cancer

The roles of long non-coding RNAs in ovarian cancer: from functions to therapeutic implications

Long non-coding RNAs (lncRNAs) are multifunctional and participate in a variety of biological processes and gene regulatory networks. The deregulation of lncRNAs has been extensively implicated in diverse human diseases, especially in cancers. Overwhelming evidence demonstrates that lncRNAs are essential to the pathophysiological processes of ovarian cancer (OC), acting as regulators involved in metastasis, cell death, chemoresistance, and tumor immunity. In this review, we illustrate the expanded functions of lncRNAs in the initiation and progression of OC and elaborate on the signaling pathways in which they pitch. Additionally, the potential clinical applications of lncRNAs as biomarkers in the diagnosis and treatment of OC were emphasized, cementing the bridge of communication between clinical practice and basic research.

MicroRNAs, long non-coding RNAs, and circular RNAs and gynecological cancers: focus on metastasis

Gynecologic cancer is a significant cause of death in women worldwide, with cervical cancer, ovarian cancer, and endometrial cancer being among the most well-known types. The initiation and progression of gynecologic cancers involve a variety of biological functions, including angiogenesis and metastasis-given that death mostly occurs from metastatic tumors that have invaded the surrounding tissues. Therefore, understanding the molecular pathways underlying gynecologic cancer metastasis is critical for enhancing patient survival and outcomes. Recent research has revealed the contribution of numerous non-coding RNAs (ncRNAs) to metastasis and invasion of gynecologic cancer by affecting specific cellular pathways. This review focuses on three types of gynecologic cancer (ovarian, endometrial, and cervical) and three kinds of ncRNAs (long non-coding RNAs, microRNAs, and circular RNAs). We summarize the detailed role of non-coding RNAs in the different pathways and molecular interactions involved in the invasion and metastasis of these cancers.

The Role of EMT-Related lncRNAs in Ovarian Cancer

Ovarian cancer (OC) is one of the deadliest cancers worldwide; late diagnosis and drug resistance are two major factors often responsible for high morbidity and treatment failure. Epithelial-to-mesenchymal transition (EMT) is a dynamic process that has been closely linked with cancer. Long non-coding RNAs (lncRNAs) have been also associated with several cancer-related mechanisms, including EMT. We conducted a literature search in the PubMed database in order to sum up and discuss the role of lncRNAs in regulating OC-related EMT and their underlying mechanisms. Seventy (70) original research articles were identified, as of 23 April 2023. Our review concluded that the dysregulation of lncRNAs is highly associated with EMT-mediated OC progression. A comprehensive understanding of lncRNAs' mechanisms in OC will help in identifying novel and sensitive biomarkers and therapeutic targets for this malignancy.

Emerging role of oncogenic long noncoding RNA as cancer biomarkers

The view of long noncoding RNAs as nonfunctional "garbage" has been definitely outdated by the large body of evidence indicating this class of ncRNAs as "golden junk", especially in precision oncology. Indeed, in light of their oncogenic role and the higher expression in multiple cancer types compared with paired adjacent tissues, the clinical interest for lncRNAs as diagnostic and/or prognostic biomarkers has been rapidly increasing. The emergence of large-scale sequencing technologies, their subsequent diffusion even in small research and clinical centers, the technological advances for the detection of low-copy lncRNAs in body fluids, coupled to the huge reduction of operating costs, have nowadays made possible to rapidly and comprehensively profile them in multiple tumors and large cohorts. In this review, we first summarize some relevant data about the oncogenic role of well-studied lncRNAs having a clinical relevance. Then, we focus on the description of their potential use as diagnostic/prognostic biomarkers, including an updated overview about licensed patents or clinical trials on lncRNAs in oncology.

Long non-coding RNA MYU promotes ovarian cancer cell proliferation by sponging miR-6827-5p and upregulating HMGA1

Background: Long non-coding RNAs (lncRNAs) have been confirmed to play vital roles in tumorigenesis. LncRNA MYU has recently been reported as an oncogene in several kinds of tumors. However, MYU's expression status and potential involvement in ovarian cancer (OC) remain unclear. In this study, we explored the underlying role of MYU in OC. Methods and results: The expression of MYU was upregulated in OC tissues, and MYU's overexpression was significantly correlated with the FIGO stage and lymphatic metastasis. Knockdown of MYU inhibited cell proliferation in SKOV3 and A2780 cells. Mechanistically, MYU directly interacted with miR-6827-5p in OC cells; HMGA1 is a downstream target gene of miR-6827-5p. Furthermore, MYU knockdown increased the expression of miR-6827-5p and decreased the expression of HMGA1. Restoration of HMGA1 expression reversed the influence on cell proliferation caused by MYU knockdown. Conclusion: MYU functions as a ceRNA that positively regulates HMGA1 expression by sponging miR-6827-5p in OC cells, which may provide a potential target and biomarker for the diagnosis or prognosis of OC.

Development of a Novel KCNN4-Related ceRNA Network and Prognostic Model for Renal Clear Cell Carcinoma

Background. Clear cell renal cell carcinoma (ccRCC) accounts for more than 80% of renal cell carcinomas. Yet, it has not been fully understood about the derivation and progression of the tumor, as well as the long-term benefits from multimodality therapy. Therefore, reliable and applicable molecular markers are urgently needed for the prediction of diagnosis and prognosis of ccRCC patients. Methods. Genetic and clinical information of 533 ccRCC patients from The Cancer Genome Atlas database was collected for comprehensive bioinformatic analyses. UALCAN was used to detect gene expression in paired tumor samples. Two data sets from Gene Expression Omnibus database were analyzed to identify differentially expressed genes (DEGs), and Gene Set Enrichment Analysis was applied for the functional enrichment of DEGs. Tumor Immune Single Cell Hub and Tumor IMmune Estimation Resource databases were separately used for analyses of single-immune cell and immune cell infiltration. Encyclopedia of RNA Interactomes database was explored to predict targeted microRNAs (miRNAs) and corresponding long non-coding RNAs (lncRNAs). Cox regression analysis was performed for the construction of risk signature and prognosis model. Finally, quantitative real-time polymerase chain reaction and western blot were conducted for KCNN4 expression detection in cell lines and clinical samples. Small interfering RNA was employed to knock down KCNN4, and corresponding functional experiments were conducted on ccRCC cells as well. Results. KCNN4 showed elevated expression in tumors and prominent clinical correlation in ccRCC. In total, 41 KCNN4-related genes were enriched, and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed they were intimately related to immune-related signaling pathways. Spearman’s analysis revealed the significantly positive correlation of KCNN4 with immune cell infiltration. By integrating hub miRNA-let-7e-5p and four critical lncRNA, a competitive endogenous RNA network-based risk signature was constructed. The prognosis model derived from it showed considerable predictive value for survival of ccRCC patients. Finally, in vitro experiments confirmed the remarkable tumor-promoting role of KCNN4 in ccRCC cells. Conclusion. KCNN4 significantly affected the immune status of tumor microenvironment and immunotherapy elements, through which it promoted tumor progression in ccRCC, and it could be a potential biomarker for prognosis and immunotherapy effects of ccRCC patients.

Upregulation of the c-MYC oncogene and adjacent long noncoding RNAs PVT1 and CCAT1 in esophageal squamous cell carcinoma

BACKGROUND

All cell types express long non-coding RNAs (lncRNAs), which have the potential to play a role in carcinogenesis by altering the levels of their expression. Squamous cell carcinoma of the esophagus (ESCC) is a deadly disease with a poor prognosis and a high frequency of lymphatic metastases. Understanding the functional role and signaling pathways of two neighboring lncRNAs, CCAT1 and PVT1, in this oncogene's pathogenesis may help us determine ESCC. Furthermore, it is still unclear whether these lncRNAs are linked to the clinicopathological characteristics of patients with ESCC.

METHODS

For this study, we used biopsy from the Imam Khomeini Cancer Institute's tumor bank in Tehran, Iran to obtain 40 ESCC tumor samples and their normal margin counterparts. The expression levels of the CCAT1, PVT1, and c-MYC genes were assessed using quantitative Real-Time RT-PCR. Additionally, demographic data and clinical-pathologic characteristics, such as tumor grade, tumor stage, lymph node, and metastasis, were taken into consideration. Graphpad prism version 8 was used for bioinformatics analyses.

RESULTS

Comparing ESCC tissues to non-tumor tissues, we found significant upregulation of PVT1, CCAT1, and c-MYC. Patients with ESCC who had increased PVT1 expression also had higher rates of advanced stage and lymph node metastasis, whereas increased CCAT1 expression was only linked to advanced stage and wasn't associated with lymph node metastasis. In predicting ESCC, CCAT1 (p < 0.05) was found to be an important factor. Overall survival was reduced by c-MYC and PVT1 overexpression (p < 0.001), according to Kaplan-Meier analysis. PVT1, CCAT1, and c-MYC were found to interact with 23 miRNAs with high and medium score classes, as shown in a bioinformatics study. We summarized the experimentally proven interactions between c-MYC, PVT1, and CCAT1 and other miRNAs, lncRNAs, and proteins.

CONCLUSION

This is the first report that CCAT1, PVT1 and c-MYC have been found to be up-regulated simultaneously in ESCC. It is possible that these genes may be involved in ESCC as a result of these findings. Therefore, as consequence, more research is needed to determine whether or not these lncRNAs play an oncogenic role in ESCC development and progression, as well as the regulatory mechanisms that control them.

CCAT 1- A Pivotal Oncogenic Long Non-Coding RNA in Colorectal Cancer

Colorectal cancer (CRC) is ranked as the third most common cancer and second deadliest cancer in both men and women in the world. Currently, the cure rate and 5-year survival rate of CRC patients remain relatively low. Therefore, discovering a novel molecular biomarker that can be used to improve CRC screening, diagnosis, prognosis, and treatment would be beneficial. Long non-coding RNA colon cancer-associated transcript 1 (CCAT 1) has been found overexpressed in CRC and is associated with CRC tumorigenesis and treatment outcome. CCAT 1 has a high degree of specificity and sensitivity, it is readily detected in CRC tissues and is significantly overexpressed in both premalignant and malignant CRC tissues. Besides, CCAT 1 is associated with clinical manifestation and advanced features of CRC, such as lymph node metastasis, high tumor node metastasis stage, differentiation, invasion, and distant metastasis. In addition, they can upregulate oncogenic c-MYC and negatively modulate microRNAs via different mechanisms of action. Furthermore, dysregulated CCAT 1 also enhances the chemoresistance in CRC cells while downregulation of them reverses the malignant phenotypes of cancer cells. In brief, CCAT 1 serves as a potential screening, diagnostic and prognostic biomarker in CRC, it also serves as a potential therapeutic marker to treat CRC patients.

Analysis of A Disintegrin and Metalloprotease 17 (ADAM17) Expression as a Prognostic Marker in Ovarian Cancer Patients Undergoing First-Line Treatment Plus Bevacizumab

To find prognostic factors for advanced ovarian cancer patients undergoing first-line therapy with carboplatin, paclitaxel and bevacizumab, we investigated the expression of a disintegrin and metalloprotease 17 (ADAM17) in cancer tissues. ADAM17 has been involved in ovarian cancer development, progression and cell resistance to cisplatin. Tissue microarrays from 309 ovarian cancer patients enrolled in the MITO16A/MANGO-OV2 clinical trial were analyzed by immunohistochemistry for ADAM17 protein expression. Intensity and extent of staining were combined into a semi-quantitative visual grading system (H score) which was related to clinicopathological characteristics of cases and the clinical outcome of patients by univariate and multivariate Cox regression models. ADAM17 immunostaining was detected in most samples, mainly localized in the tumor cells, with variable intensity across the cohort. Kaplan–Meier survival curves, generated according to the best cut-off value for the ADAM17 H score, showed that high ADAM17 expression was associated with worse prognosis for PFS and OS. However, after the application of a shrinkage procedure to adjust for overfitting hazard ratio estimates, the ADAM17 value as prognostic factor was lost. As subgroup analysis suggested that ADAM17 expression could be prognostically relevant in cases with no residual disease at baseline, further studies in this patient category may be worth planning.

STAT3-EMT axis in tumors: modulation of cancer metastasis, stemness and therapy response

Epithelial-to-mesenchymal transition (EMT) mechanism is responsible for metastasis of tumor cells and their spread to various organs and tissues of body, providing undesirable prognosis. In addition to migration, EMT increases stemness and mediates therapy resistance. Hence, pathways involved in EMT regulation should be highlighted. STAT3 is an oncogenic pathway that can elevate growth rate and migratory ability of cancer cells and induce drug resistance. The inhibition of STAT3 signaling impairs cancer progression and promotes chemotherapy-mediated cell death. Present review focuses on STAT3 and EMT interaction in modulating cancer migration. First of all, STAT3 is an upstream mediator of EMT and is able to induce EMT-mediated metastasis in brain tumors, thoracic cancers and gastrointestinal cancers. Therefore, STAT3 inhibition significantly suppresses cancer metastasis and improves prognosis of patients. EMT regulators such as ZEB1/2 proteins, TGF-β, Twist, Snail and Slug are affected by STAT3 signaling to stimulate cancer migration and invasion. Different molecular pathways such as miRNAs, lncRNAs and circRNAs modulate STAT3/EMT axis. Furthermore, we discuss how STAT3 and EMT interaction affects therapy response of cancer cells. Finally, we demonstrate targeting STAT3/EMT axis by anti-tumor agents and clinical application of this axis for improving patient prognosis.

The Role of Long Non-Coding RNA CCAT1 and SNHG14 in Activation of Some Protein-Coding Genes Associated with the Development of Ovarian Cancer

Late diagnosis of ovarian cancer is one of the most important problems in its treatment. Long non-coding RNA (lncRNA) are a poorly studied, but promising type of diagnostic biomarkers. We studied the lncRNA interactome to identify biomarkers with potential significance for molecular diagnostics of ovarian cancer. By screening the TCGA database, we identified differentially expressed lncRNA CCAT1 and SNHG14. Based on the indices of complementarity of CCAT1 and SNHG14 to the mRNA sequences, we selected 5 protein-coding genes MAPK1, c-MET, TGFB2, SNAIL1, and WNT4 associated with the epithelial-mesenchymal transition. Real-time PCR on 54 ovarian cancer samples confirmed the high expression levels of CCAT1 and SNHG14 (logFC>1.5, p<0.05). A positive correlation between the expression levels of two lncRNA and mRNA of 5 genes in 6 pairs was established. The activating effect of CCAT1 and SNHG14 on the expression of these genes can be mediated by miR-203 and miR-124.

What is beyond LncRNAs in breast cancer: A special focus on colon cancer-associated Transcript-1 (CCAT-1)

Long non-coding RNAs (LncRNAs) play a vital role in the process of malignant transformation. In breast cancer (BC), lncRNAs field is currently under intensive investigations. Yet, the role of lncRNAs as promising diagnostic and/or prognostic biomarkers and as therapeutic target/tool among BC patients still needs a special focus from the biomedical scientists. In BC, triple negative breast cancer patients (TNBC) are the unlucky group as they are always represented with the worst prognosis and the highest mortality rates. For that reason, a special focus on TNBC and associated lncRNAs was addressed in this review. Colon cancer-associated transcript 1 (CCAT-1) is a newly discovered oncogenic lncRNA that has been emerged as a vital biomarker for diagnosis, prognosis and therapeutic interventions in multiple malignancies and showed differential expression among TNBC patients. In this review, the authors shed the light onto the general role of lncRNAs in BC and the specific functional activities, molecular mechanisms, competing endogenous ncRNA role of CCAT-1 in TNBC.

The significance of homeodomain transcription factor 2 in colon cancer cells

Background

Colon cancer is a serious malignant tumor. It has been reported that paired-like homeodomain transcription factor 2 (PITX2) can promote the progression of several types of cancer via regulating the Wnt/β-catenin pathway. It has also been demonstrated that high levels of long non-coding RNA (lncRNA) gastric carcinoma high expressed transcript 1 (GHET1) can also promote the development of cervical cancer via activating the Wnt/β-catenin pathway. However, whether PITX2 can affect the development of colon cancer via regulating the expression of lncRNA GHET1 remains unclear.

Results

The results demonstrated that PITX2 knockdown attenuated the proliferation, migration and invasion abilities of colon cancer cells. Additionally, PITX2 promoted the expression of lncRNA GHET1 via binding to its promoter. Overexpression of lncRNA GHET1 induced the expression of Wnt/β-catenin signaling-related proteins, cyclin D1, c-Myc and MMP-7. Furthermore, lncRNA GHET1 overexpression abrogated the PITX2 silencing-mediated decreased proliferation, migration and invasion abilities of colon cancer cells.

Conclusion

The findings of the present study suggested that PITX2 could enhance the proliferation, migration and invasion abilities of colon cancer cells via upregulating lncRNA GHET1 and activating the Wnt/β-catenin pathway.

Research Progress in Prognostic Factors and Biomarkers of Ovarian Cancer

Ovarian cancer is a serious threat to women's health; its early diagnosis rate is low and prone to metastasis and recurrence. The current conventional treatment for ovarian cancer is a combination of platinum and paclitaxel chemotherapy based on surgery. The recurrence and progression of ovarian cancer with poor prognosis is a major challenge in treatment. With rapid advances in technology, understanding of the molecular pathways involved in ovarian cancer recurrence and progression has increased, biomarker-guided treatment options can greatly improve the prognosis of patients. This review systematically discusses and summarizes existing and new information on prognostic factors and biomarkers of ovarian cancer, which is expected to improve the clinical management of patients and lead to effective personalized treatment.

Non-Coding RNAs as Biomarkers of Tumor Progression and Metastatic Spread in Epithelial Ovarian Cancer

Simple Summary

Despite advances in cancer research in recent years, efficient predictive biomarkers of tumor progression and metastatic spread for ovarian cancer are still missing. Therefore, we critically address recent findings in the field of non-coding RNAs (microRNAs and long non-coding RNAs) and DNA methylation in ovarian cancer patients as promising novel biomarkers of ovarian cancer progression.

Abstract

Ovarian cancer is one of the most common causes of death among gynecological malignancies. Molecular changes occurring in the primary tumor lead to metastatic spread into the peritoneum and the formation of distant metastases. Identification of these changes helps to reveal the nature of metastases development and decipher early biomarkers of prognosis and disease progression. Comparing differences in gene expression profiles between primary tumors and metastases, together with disclosing their epigenetic regulation, provides interesting associations with progression and metastasizing. Regulatory elements from the non-coding RNA families such as microRNAs and long non-coding RNAs seem to participate in these processes and represent potential molecular biomarkers of patient prognosis. Progress in therapy individualization and its proper targeting also rely upon a better understanding of interactions among the above-listed factors. This review aims to summarize currently available findings of microRNAs and long non-coding RNAs linked with tumor progression and metastatic process in ovarian cancer. These biomolecules provide promising tools for monitoring the patient’s response to treatment, and further they serve as potential therapeutic targets of this deadly disease.

The role of altered long noncoding RNAs in overall survival of ovarian cancer: A systematic review and meta-analysis

In recent years, tremendous research efforts have been focused on investigating the effect of dysregulation of lncRNAs on cancer progression, most of which confirm a positive link. This inspired us to conduct the present meta-analysis to explore whether aberrant expression of multiple lncRNAs has a role in patients' outcome in ovarian cancer. This comprehensive meta-analysis pertains to the evaluation of association between dysregulated lncRNAs expression level with eventual outcome and clinicopathological characteristics of ovarian cancer patients. We systematically searched PubMed, Web of Science, and Scopus to find all eligible articles. Pooled hazard ratios (HRs) and 95% confidence intervals (95% CIs) for overall survival, disease-free survival and progression-free survival were measured with a fixed or random effects model. A total of 34 studies were included in the meta-analysis. Dysregulation of lncRNAs were contributed to shorter overall survival (34 studies, 1180 patients HR = 2.12, 95% CI: 1.73 ± 2.60, random-effects) in ovarian cancer. Furthermore, altered lncRNAs were also related to decreased progression-free survival (8 studies, 1180 patients HR: 1.88, 95% CI: (1.35-2.62) and disease-free survival (2 studies, 285 patients, HR: 6.07, 95% CI: 1.28-28.78) in this disease. Our analyses supported the robust prognostic significance of altered lncRNAs in ovarian cancer. However, more extended studies are encouraged to evaluate the clinical application potential of these lncRNAs in the prognosis evaluation of ovarian cancer.

8q24.21 Locus: A Paradigm to Link Non-Coding RNAs, Genome Polymorphisms and Cancer

The majority of the human genome is comprised of non-protein-coding genes, but the relevance of non-coding RNAs in complex diseases has yet to be fully elucidated. One class of non-coding RNAs is long non-coding RNAs or lncRNAs, many of which have been identified to play a range of roles in transcription and translation. While the clinical importance of the majority of lncRNAs have yet to be identified, it is puzzling that a large number of disease-associated genetic variations are seen in lncRNA genes. The 8q24.21 locus is rich in lncRNAs and very few protein-coding genes are located in this region. Interestingly, the 8q24.21 region is also a hot spot for genetic variants associated with an increased risk of cancer. Research focusing on the lncRNAs in this area of the genome has indicated clinical relevance of lncRNAs in different cancers. In this review, we summarise the lncRNAs in the 8q24.21 region with respect to their role in cancer and discuss the potential impact of cancer-associated genetic polymorphisms on the function of lncRNAs in initiation and progression of cancer.

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.

Interplay between p53 and non-coding RNAs in the regulation of EMT in breast cancer

The epithelial-mesenchymal transition (EMT) plays a pivotal role in the differentiation of vertebrates and is critically important in tumorigenesis. Using this evolutionarily conserved mechanism, cancer cells become drug-resistant and acquire the ability to escape the cytotoxic effect of anti-cancer drugs. In addition, these cells gain invasive features and increased mobility thereby promoting metastases. In this respect, the process of EMT is critical for dissemination of solid tumors including breast cancer. It has been shown that miRNAs are instrumental for the regulation of EMT, where they play both positive and negative roles often as a part of a feed-back loop. Recent studies have highlighted a novel association of p53 and EMT where the mutation status of p53 is critically important for the outcome of this process. Interestingly, p53 has been shown to mediate its effects via the miRNA-dependent mechanism that targets master-regulators of EMT, such as Zeb1/2, Snail, Slug, and Twist1. This regulation often involves interactions of miRNAs with lncRNAs. In this review, we present a detailed overview of miRNA/lncRNA-dependent mechanisms that control interplay between p53 and master-regulators of EMT and their importance for breast cancer.

Long non-coding RNA CCAT1 promotes non-small cell lung cancer progression by regulating the miR-216a-5p/RAP2B axis

The long non-coding RNA colon cancer-associated transcript 1 (CCAT1) has been investigated to involve in the progression of non-small cell lung cancer (NSCLC). Thus, this study aims to explore the detailed molecular mechanisms of CCAT1 in NSCLC. The expression of CCAT1, miR-216a-5p, RAP2B, Bax, Bcl-2, and cleaved caspase 3 was detected by qRT-PCR or Western blot. Cell proliferation, apoptosis, migration, and invasion were analyzed using cell counting kit-8, flow cytometry or Transwell assays, respectively. The interaction between miR-216a-5p and CCAT1 or RAP2B was analyzed by luciferase reporter, RNA immunoprecipitation, and pull-down assays. The expression of CCAT1 was elevated in NSCLC, and CCAT1 deletion could inhibit NSCLC cell proliferation, migration, and invasion but induce apoptosis in vitro as well as imped tumor growth in vivo. MiR-216a-5p was confirmed to be a target of CCAT1, and silencing miR-216a-5p could reverse CCAT1 depletion-mediated inhibitory effects on cell tumorigenesis in NSCLC. Besides that, miR-216a-5p was decreased in NSCLC, and miR-216a-5p restoration inhibited cell tumorigenesis by regulating RAP2B, which was verified to be a target of miR-216a-5p. Additionally, co-expression analysis suggested that CCAT1 indirectly regulated RAP2B level by targeting miR-216a-5p in NSCLC cells. Taken together, CCAT1 deletion could inhibit cell progression in NSCLC through miR-216a-5p/RAP2B axis, indicating a novel pathway underlying NSCLC cell progression and providing new potential targets for NSCLC treatment.

Gynecologic cancers and non-coding RNAs: Epigenetic regulators with emerging roles

Gynecologic cancers involve the female genital organs, such as the vulva, vagina, cervix, endometrium, ovaries, and fallopian tubes. The occurrence and frequency of gynecologic cancer depends on personal lifestyle, history of exposure to viruses or carcinogens, genetics, body shape, and geographical habitat. For a long time, research into the molecular biology of cancer was broadly restricted to protein-coding genes. Recently it has been realized that non-coding RNAs (ncRNA), including long noncoding RNAs (LncRNAs), microRNAs, circular RNAs and piRNAs (PIWI-interacting RNAs), can all play a role in the regulation of cellular function within gynecological cancer. It is now known that ncRNAs are able to play dual roles, i.e. can exert both oncogenic or tumor suppressive functions in gynecological cancer. Moreover, several clinical trials are underway looking at the biomarker and therapeutic roles of ncRNAs. These efforts may provide a new horizon for the diagnosis and treatment of gynecological cancer. Herein, we summarize some of the ncRNAs that have been shown to be important in gynecological cancers.

LncRNAs in Ovarian Cancer Progression, Metastasis, and Main Pathways: ceRNA and Alternative Mechanisms

Ovarian cancer (OvCa) develops asymptomatically until it reaches the advanced stages with metastasis, chemoresistance, and poor prognosis. Our review focuses on the analysis of regulatory long non-coding RNAs (lncRNAs) competing with protein-coding mRNAs for binding to miRNAs according to the model of competitive endogenous RNA (ceRNA) in OvCa. Analysis of publications showed that most lncRNAs acting as ceRNAs participate in OvCa progression: migration, invasion, epithelial-mesenchymal transition (EMT), and metastasis. More than 30 lncRNAs turned out to be predictors of survival and/or response to therapy in patients with OvCa. For a number of oncogenic (CCAT1, HOTAIR, NEAT1, and TUG1 among others) and some suppressive lncRNAs, several lncRNA/miRNA/mRNA axes were identified, which revealed various functions for each of them. Our review also considers examples of alternative mechanisms of actions for lncRNAs besides being ceRNAs, including binding directly to mRNA or protein, and some of them (DANCR, GAS5, MALAT1, and UCA1 among others) act by both mechanisms depending on the target protein. A systematic analysis based on the data from literature and Panther or KEGG (Kyoto Encyclopedia of Genes and Genomes) databases showed that a significant part of lncRNAs affects the key pathways involved in OvCa metastasis, EMT, and chemoresistance.

The Role of microRNAs in Epithelial Ovarian Cancer Metastasis

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and the major cause of death is mainly attributed to metastasis. MicroRNAs (miRNAs) are a group of small non-coding RNAs that exert important regulatory functions in many biological processes through their effects on regulating gene expression. In most cases, miRNAs interact with the 3′ UTRs of target mRNAs to induce their degradation and suppress their translation. Aberrant expression of miRNAs has been detected in EOC tumors and/or the biological fluids of EOC patients. Such dysregulation occurs as the result of alterations in DNA copy numbers, epigenetic regulation, and miRNA biogenesis. Many studies have demonstrated that miRNAs can promote or suppress events related to EOC metastasis, such as cell migration, invasion, epithelial-to-mesenchymal transition, and interaction with the tumor microenvironment. In this review, we provide a brief overview of miRNA biogenesis and highlight some key events and regulations related to EOC metastasis. We summarize current knowledge on how miRNAs are dysregulated, focusing on those that have been reported to regulate metastasis. Furthermore, we discuss the role of miRNAs in promoting and inhibiting EOC metastasis. Finally, we point out some limitations of current findings and suggest future research directions in the field.

MAGI2-AS3 suppresses MYC signaling to inhibit cell proliferation and migration in ovarian cancer through targeting miR-525-5p/MXD1 axis

Ovarian cancer (OV) is one of the most lethal gynecological malignance in females, and usually diagnosed at advanced stages. Long noncoding RNAs (lncRNAs) exhibit their crucial functions in modulatory mechanisms of cancers. Substantive studies have proven the anti-tumor role of MAGI2-AS3 in multiple cancers, but the physiological functions of MAGI2-AS3 in OV need more detailed explanations. The current study corroborated that overexpression of MAGI2-AS3 executed inhibitory activity in OV via hindering cell proliferation, cell cycle, migration as well as invasion while promoted apoptosis. Moreover MAGI2-AS3 bound with miR-525-5p and negatively regulated the expression of miR-525-5p. Further studies testified that MXD1 was a downstream target of miR-525-5p and the competing relationship between MAGI2-AS3 and MXD1 were confirmed by RNA pull down. Based on the combination between MAX and MYC, we analyzed the effects of MAGI2-AS3 on MXD1 and MYC, unveiling the competing relationship between MXD1 and MYC for binding to MAX. Finally, we constructed rescue assays to certify that MAGI2-AS3 suppressed the course of OV via enhancing MXD1 expression. In summary, MAGI2-AS3 repressed the progression of OV by targeting miR-525-5p/MXD1 axis, offering a novel insight into understanding OV at the molecular level.

Identification of lncRNA-associated ceRNA network in high-grade serous ovarian cancer metastasis

Aim: To uncover a novel lncRNA-miRNA-mRNA network associated with high-grade serous ovarian cancer metastasis. Material & methods: The candidate differentially expressed lncRNAs were obtained from RNA-sequencing data and determined by functional experiments. The downstream miRNAs and mRNAs were identified by bioinformatic prediction and subjected to functional enrichment analysis. Results: The expression levels of lncRNA ENTPD1-AS1/PRANCR/NR2F2-AS1 were reduced in omental metastatic tissues. Similar differential expression patterns of these lncRNAs were also found in lnCAR database and we verified their tumor suppressive roles by performing functional experiments. Furthermore, we predicted miRNAs and mRNAs via bioinformatic tools and validated their alteration in expression levels in presence of lncRNA interference. Conclusion: We proposed a potential ceRNA regulatory mechanism in high-grade serous ovarian cancer omental metastasis.

Long non-coding RNA colon cancer-associated transcript-1 regulates tumor cell proliferation and invasion of non-small-cell lung cancer through suppressing miR-152

AIM

Lung cancer serves as one of the most common cancers in the world, and approximately 50% of non-small-cell lung cancer (NSCLC) patients are found to be aged >70 when diagnosed. In this study, we aimed to explore the effect of long non-coding RNAs colon cancer-associated transcript-1 (CCAT1) in NSCLC.

METHODS

A total of 72 clinical samples from older NSCLC patients were collected for analysis. The relative mRNA level of CCAT1 was detected through real-time polymerase chain reaction. Overall survival of NSCLC patients was detected through Kaplan-Meier survival analysis. MTT assays were used to detect cell proliferation. Cell invasion was determined by transwell assay. Protein levels were detected through western blot.

RESULTS

CCAT1 expression levels significantly increased in NSCLC tumor tissues and were associated with poor overall survival of NSCLC patients. CCAT1 promotes cell proliferation, cell invasion and epithelial-mesenchymal transition of NSCLC cell lines. CCAT1 binds with miR-152, and the effect of si-CCAT1 in NSCLC cell proliferation, cell invasion and epithelial-mesenchymal transition was partially reversed by anti-miR-152.

CONCLUSIONS

Long non-coding RNA CCAT1 regulates tumor cell proliferation and invasion in NSCLC through suppressing miR-152. Geriatr Gerontol Int 2020; ••: ••-••.

Long non-coding RNA CCAT1 is overexpressed in endometrial cancer and regulates growth and transcriptome of endometrial adenocarcinoma cells

BACKGROUND

Long non-coding RNAs (lncRNAs) play important roles in regulation of gene expression and are involved in pathogenesis of different diseases including cancer. Recent studies suggested the lncRNA Colon cancer associated transcript-1 (CCAT1) to act as putative oncogene. In this study, to elucidate the role of this lncRNA in endometrial cancer, we examined its expression in normal endometrium and type 1 endometrial cancer and knocked down its expression in endometrial cancer cell lines followed by transcriptome and pathway analyses.

METHODS

CCAT1 expression was examined in 100 tissue samples of normal endometrium and type 1 endometrial cancer tissues by means of RT-qPCR. Knockdown of CCAT1 expression in HEC-1B and RL95/2 endometrial cancer cells was performed by siRNA transfection. Affymetrix GeneChip arrays were used to elucidate the effect of both lncRNAs on the transcriptome of these cell lines.

RESULTS

Median CCAT1 expression was found to be 9.3-fold higher in endometrial cancer when compared to normal endometrium (p < 0.05). In contrast to premenopausal endometrium and G1, G2 and G3 graded endometrial cancer, CCAT1 expression was nearly absent in postmenopausal tissue. Knockdown of CCAT1 by transient siRNA transfection significantly reduced proliferation of HEC-1B cancer cells in vitro by 35.5 % 6 days after transfection and notably reduced their colony formation ability. Affymetrix microarray and Ingenuity pathway analyses revealed a set of up- or down-regulated genes in transfected ERα-negative HEC-1B cells forming a network controlled by the key regulators TNF and TP53, including genes known to be involved in growth control, providing putative molecular mechanisms underlying the observed growth inhibition of HEC-1B cells. In contrast, CCAT1 knockdown in ERα-positive RL95/2 cells did not significantly affect proliferation, but resulted in down-regulation of a network of ERα target genes.

CONCLUSIONS

Given that the lncRNA CCAT1 was found to be overexpressed in endometrial cancer, affected the growth of HEC-1B cells and the expression of growth regulatory genes, our data suggest CCAT1 to exert oncogenic functions in endometrial cancer and encourage further studies to examine to what extent this lncRNA might be a potential therapy target in this cancer entity.

A comprehensive review of the role of long non-coding RNAs in organs with an endocrine function

Long non-coding RNAs (lncRNAs) are transcripts with sizes larger than 200 nucleotides and no/ small open reading frame that cannot produce functional proteins. The number of these transcripts surpasses the number of coding genes. LncRNAs regulate many aspects of cell functions such as proliferation, cell cycle transition and differentiation; so their dysregulation has pervasive effects on cell phenotype. Increasing numbers of these transcripts have been shown to participate in the pathogenesis of cancer. In the current review, we summarize recent findings regarding the role of lncRNAs in tumors originated from organs which have an endocrine function. We mostly focused on adrenal, pancreas and pituitary gland as prototypes of these organs. Moreover, we presented the obtained data of the role of lncRNAs in prostate, ovarian and testicular cancers. Recent data highly supports the role of lncRNAs in the pathogenesis of cancers originated from these organs. Moreover, certain genomic loci within lncRNAs have been shown to be associated with risk of these cancers. Diagnostic and prognostic role of some lncRNAs in these cancers have been evaluated recently. Taken together, lncRNAs are putative biomarkers for cancers originated from organs which have an endocrine function.

Wnt/β-catenin signalling in ovarian cancer: Insights into its hyperactivation and function in tumorigenesis

Epithelial ovarian cancer (EOC) is the deadliest female malignancy. The Wnt/β-catenin pathway plays critical roles in regulating embryonic development and physiological processes. This pathway is tightly regulated to ensure its proper activity. In the absence of Wnt ligands, β-catenin is degraded by a destruction complex. When the pathway is stimulated by a Wnt ligand, β-catenin dissociates from the destruction complex and translocates into the nucleus where it interacts with TCF/LEF transcription factors to regulate target gene expression. Aberrant activation of this pathway, which leads to the hyperactivity of β-catenin, has been reported in ovarian cancer. Specifically, mutations of CTNNB1, AXIN, or APC, have been observed in the endometrioid and mucinous subtypes of EOC. In addition, upregulation of the ligands, abnormal activation of the receptors or intracellular mediators, disruption of the β-catenin destruction complex, inhibition of the association of β-catenin/E-cadherin on the cell membrane, and aberrant promotion of the β-catenin/TCF transcriptional activity, have all been reported in EOC, especially in the high grade serous subtype. Furthermore, several non-coding RNAs have been shown to regulate EOC development, in part, through the modulation of Wnt/β-catenin signalling. The Wnt/β-catenin pathway has been reported to promote cancer stem cell self-renewal, metastasis, and chemoresistance in all subtypes of EOC. Emerging evidence also suggests that the pathway induces ovarian tumor angiogenesis and immune evasion. Taken together, these studies demonstrate that the Wnt/β-catenin pathway plays critical roles in EOC development and is a strong candidate for the development of targeted therapies.

Colon Cancer-Associated Transcripts 1 and 2: Roles and functions in human cancers

The long noncoding RNAs (lncRNAs) Colon Cancer-Associated Transcripts 1 and 2 (CCAT1 and CCAT2) are located in a recurrently amplified region in cancers. Their proximity with the Myc oncogene and their interactions with its promoter provided further evidence for their contribution in the tumorigenesis processes. Several cell line and clinical studies have shown upregulation of these lncRNAs in diverse malignancies. Moreover, some single nucleotide variants within these genes have been associated with cancer risk or therapeutic response in different populations. Besides, these two lncRNAs act as sponges for some tumor suppressor microRNAs (miRNAs), thus promoting cancer evolution. In the current study, we review recent literature about their expression level, interaction with cancer-related pathways, their role in determination of cell fate and their contribution in malignant phenotype characteristics. Taken together, the current literature shows that these lncRNAs are putative targets for design of novel treatment strategies. Moreover, their expression levels in biopsied samples, exosomes, and sera of patients might be applied as diagnostic biomarkers or markers for patient follow-up.

Overexpression of long noncoding RNA HOXB-AS3 indicates an unfavorable prognosis and promotes tumorigenesis in epithelial ovarian cancer via Wnt/β-catenin signaling pathway

Long noncoding RNA HOXB cluster antisense RNA 3 (HOXB-AS3) has been reported to be dysregulated in several tumors. The present study mainly aims at the investigation in how HOXB-AS3 works in epithelial ovarian cancer (EOC) and to elucidate the mechanism involved. Initially, 'GEPIA' was mined to examine the differential expression levels and prognostic value of HOXB-AS3 in EOC patients. The expression of HOXB-AS3 in EOC cell lines and patient specimens was examined with quantitative RT-PCR. Simultaneously, the correlation of HOXB-AS3 expression with a variety of clinicopathological factors and patient survival was analyzed. MTT, colony formation and flow cytometry assays were performed to analyze the cell viability of EOC cells. Wound healing and Transwell assays were carried out to determine EOC cells' capability of migrating and invading. The impact of HOXB-AS3 on EMT and Wnt/β-catenin signaling was explored with the approach of Western blot. We found that in both EOC cell lines and tissues, HOXB-AS3 expression was significantly up-regulated, and its high expression was an independent prognostic marker of poor outcome for EOC patients. In vitro loss-of-function assays revealed that HOXB-AS3 knockdown inhibited EOC cells proliferation, migration, invasion and EMT, and induced EOC cells' apoptosis. Furthermore, we validated that down-regulated HOXB-AS3 attenuated the activity of Wnt/β-catenin signaling to suppress the invasion, migration and proliferation of EOC cells. To sum up, the present study came up with the conclusion that HOXB-AS3 acts as an oncogenic gene in EOC progression through HOXB-AS3-Wnt/β-catenin signaling regulation, providing a novel insight into EOC tumorigenesis.

Roles of long non-coding RNAs in colorectal cancer tumorigenesis: A Review

Long non-coding RNAs (lncRNAs) are newly identified potential biological and gene regulators. Similar to other cell-free circulating cancer-related nucleic acids, lncRNAs are released in the peripheral circulation of cancer patients and allow for non-invasive gene expression assessment. lncRNAs are considered to be promising biomarkers for cancer prognosis and diagnosis. Several lncRNAs have been found to regulate developmental processes in a number of biological disorders. Recent studies indicated that lncRNAs are associated with numerous diseases, most notably cancer, as they were found to be highly expressed or silenced in a number of human cancers, including colorectal cancer (CRC). Despite advances in the current detection methods, over half of cancer patients succumb to the disease, as several CRC cases are diagnosed at an advanced stage. Due to the lack of non-invasive and low-cost prognostic and diagnostic tests for CRC, the identification of novel, potentially effective biomarkers has been attracting increasing attention in recent cancer research. The present review focused on the most widely applied lncRNAs in cancer detection, including CRC, in vitro.

The functions and oncogenic roles of CCAT1 in human cancer

In various human cancers, long non-coding RNAs (lncRNAs), a novel class of RNAs longer than 200 nucleotides without protein-coding potential, are implicated in a variety of biological processes, such as cell proliferation, invasion, metastasis, and apoptosis through regulation of gene expression at various levels including chromatin, splicing, transcriptional and post-transcriptional levels. However, the mechanisms underlying these are still elusive. Colon cancer-associated transcript 1(CCAT1) has received increased attention among those lncRNAs. Studies have shown high expression pattern and oncogenic role of CCAT1 in different types of cancer, and aberrant expression of CCAT1 has been involved in tumor-genesis, progression, metastasis, and patient survival via regulating different target genes and signaling pathways. In this review, we first introduce the concept, identification, and biological function of CCAT1; we then describe the mechanisms by which CCAT1 regulate the cancer proliferation and progression. In the last, we discuss emerging insights into the role of CCAT1 as potential biomarker and therapeutic target for novel treatment paradigms in cancer.

lncRNA CCAT1 promotes bladder cancer cell proliferation, migration and invasion

OBJECTIVE

To study the expression patterns of long noncoding RNA (lncRNA) colon cancer-associated transcript 1 (CCAT1) and the changes in cell proliferation, apoptosis, migration and invasion induced by silencing CCAT1 in bladder cancer cells.

MATERIALS AND METHODS

The expression levels of CCAT1 were determined using realtime quantitative polymerase chain reaction in cancerous tissues and paired normal tissues from 34 patients with bladder cancer. The relationship between clinical characteristics and CCAT1 expression was analyzed. And then we conducted cell experiments. Bladder urothelial carcinoma cell lines T24 and 5637 cells were transfected with CCAT1 small interfering RNA (siRNA) or scramble siRNA. Cell proliferation and apoptosis changes were determined using a Cell Counting Kit-8 (CCK-8) assay and a fl ow cytometry assay. Migration and invasion changes were measured using a wound healing assay and a trans-well assay. microRNAs (miRNAs) were predicted by Starbase 2.0, and their differential expression levels were studied.

RESULTS

CCAT1 was signifi cantly upregulated in bladder cancer (P < 0.05). CCAT1 upregulation was positively related to tumor stage (P = 0.004), tumor grade (P = 0.001) and tumor size (P = 0.042). Cell proliferation, migration and invasion were promoted by abnormally expressed CCAT1. miRNAs miR-181b-5p, miR-152-3p, miR-24-3p, miR-148a-3p and miR-490-3p were potentially related to the aforementioned functions of CCAT1.

CONCLUSION

CCAT1 plays an oncogenic role in urothelial carcinoma of the bladder. In addition, CCAT1 may be a potential therapeutic target in this cancer.

Long noncoding RNA CDKN2B-AS1 interacts with miR-411-3p to regulate ovarian cancer in vitro and in vivo through HIF-1a/VEGF/P38 pathway

Ovarian cancer (OC) is one of the most prevalent cancers with high fatality rate. In the present study, RT-PCR showed that the mRNA level of CDKN2B-AS1 was significantly upregulated while the miR-411-3p was downregulated in OC cell lines. In addition, the Sh-CDKN2B-AS1 resulted in the suppression of cell growth, invasion, migration and promotion of apoptosis, and miR-411-3p showed reversed results. Further studies demonstrated that CDKN2B-AS1 could directly interact with miR-411-3p, and that there was an inverse correlation between miR-411-3p and CDKN2B-AS1. Moreover, the in vivo experiments further demonstrated that Sh-CDKN2B-AS1 could inhibit the tumor growth. In addition, we examined the effect of CDKN2B-AS1 and miR-411-3p on HIF1a/VEGF/P38 axis. Consequently, Sh-CDKN2B-AS1 could suppress this pathway. In summary, our study demonstrated that the CDKN2B-AS1 interacted with miR-411-3p contributing to carcinogenesis in OC. Meanwhile, Sh-CDKN2B-AS1 showed anti-cancer role by promoting apoptosis and inhibiting cell growth, invasion and migration. Collectively, CDKN2B-AS1 modulated these activities possibly though miR-411-3p/HIF1a/VEGF/P38 pathway.

LncRNA CCAT1 negatively regulates miR-181a-5p to promote endometrial carcinoma cell proliferation and migration

Long non-coding RNAs (lncRNAs) are identified as vital modulators in a number of biological processes, including tumorigenesis. However, the role of lncRNAs in endometrial carcinoma (EC) remains unknown. In the current study, the expression patterns, biological roles and functional mechanism of the lncRNA colon cancer associated transcript 1 (CCAT1) was examined in EC. The expression level of CCAT1 was significantly upregulated in EC tissue samples compared with matched adjacent healthy tissue samples from patients with endometrial cancer. Similarly, CCAT1 was significantly upregulated in several EC cell lines (KLE, Ishiwaka and HEC-1-A), compared with the normal human endometrial stromal cell line T-HESC. Cell counting kit-8 and Transwell migration assays demonstrated that CCAT1 knockdown significantly decreased EC cell proliferation and migration. In addition, CCAT1 was confirmed as a target gene of miR-181a-5p in EC. Overexpression of miR-181a-5p significantly decreased CCAT1 expression in EC cells, whilst knockdown of CCAT1 significantly increased miR-181a-5p expression in EC cells. Furthermore, miR-181a-5p expression was significantly downregulated in EC tissue samples compared with matched adjacent healthy tissue samples from patients with endometrial cancer. Similarly, miR-181a-5p expression was significantly downregulated in several EC cell lines (KLE, Ishiwaka and HEC-1-A), compared with normal human endometrial stromal cell line T-HESC. In addition, rescue experiments demonstrated that inhibition of miR-181a-5p significantly reversed the effect of CCAT1 knockdown on EC cell proliferation and migration. The results suggest that CCAT1 promotes EC progression by acting as a molecular sponge of miR-181a-5p.

Long non-coding RNA LOC541471: A novel prognostic biomarker for head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an aggressive cancer. Early detection and management of HNSCC may prevent progression of the disease. Long non-coding RNAs (lncRNAs) may serve as prognostic biomarkers for various cancer types. The current study downloaded an RNA-Seq dataset containing 43 tumor-normal pairs. An independent t-test identified that the expression level of lncRNA LOC541471 was significantly increased in tumor tissues compared with healthy tissues. Additionally, the current study demonstrated that high lncRNA LOC541471 expression was significantly associated with increasing lymph node metastasis classification and perineural invasion. A multivariate Cox regression analysis revealed that high lncRNA LOC541471 expression levels were an independent predictor for reduced overall survival (n=487) and relapse-free survival (n=355). According to the anatomic neoplasm subdivision, HNSCC samples were classified as oropharyngeal carcinoma (n=297), oral carcinoma (n=80), laryngeal carcinoma and hypopharyngeal carcinoma (n=123). A negative association was revealed between lncRNA LOC541471 expression and overall survival in all subtypes of HNSCC. Therefore, lncRNA LOC541471 is significantly negatively associated with overall survival and relapse-free survival of patients with HNSCC and may be considered a potential prognostic factor for HNSCC.

LncRNAs in ovarian cancer

Ovarian cancer is one of the most common gynecologic malignancies and has a poor prognosis. Recently, long noncoding RNAs (lncRNAs) have been identified as key regulators of cancer development. Studies have shown that the dysregulation of lncRNAs is frequently observed in ovarian cancer and greatly contributes to malignant phenotypical changes. In this review, we provide perspectives on the involvement of lncRNAs in the proliferation, apoptosis, cell cycle, migration, invasion, metastasis and drug resistance of ovarian cancer based on recent discoveries. Then, we discuss the role of lncRNAs in predicting the prognosis of ovarian cancer. Finally, we provide insight into the potential of lncRNAs for evaluating the diagnosis and prognosis of ovarian cancer.

The emerging role of lncRNAs in inflammatory bowel disease

Dysregulation of long noncoding RNA (lncRNA) expression is linked to the development of various diseases. Recently, an emerging body of evidence has indicated that lncRNAs play important roles in the pathogenesis of inflammatory bowel diseases (IBDs), including Crohn’s disease (CD) and ulcerative Colitis (UC). In IBD, lncRNAs have been shown to be involved in diverse processes, including the regulation of intestinal epithelial cell apoptosis, association with lipid metabolism, and cell–cell interactions, thereby enhancing inflammation and the functional regulation of regulatory T cells. In this review, we aim to summarize the current knowledge regarding the role of lncRNAs in IBD and highlight potential avenues for future investigation. We also collate potentially immune-relevant, IBD-associated lncRNAs identified through a built-by association analysis with respect to their neighboring protein-coding genes within IBD-susceptible loci. We further underscore their importance by highlighting their enrichment for various aspects of immune system regulation, including antigen processing/presentation, immune cell proliferation and differentiation, and chronic inflammatory responses. Finally, we summarize the potential of lncRNAs as diagnostic biomarkers in IBD.

Studying long noncoding RNAs (lncRNAs) may improve diagnosis and treatment of inflammatory bowel disease (IBD). These RNAs are found between genes in DNA regions previously thought to be “junk,” and have recently been shown to be important in development of various diseases. IBD, which includes both Crohn’s disease and ulcerative colitis, damages the digestive tract lining, causing pain and chronic diarrhea. A better understanding of IBD’s complex causes is needed to identify more effective treatments. Flemming Pociot at the Steno Diabetes Center in Gentofte, Denmark, and co-workers reviewed recent research linking lncRNAs and IBD. They discuss how lncRNAs’ roles in immunity and inflammation influence IBD development, describing how particular lncRNAs are related to IBD. Promising avenues for further research are highlighted, including the use of lncRNAs as biomarkers of IBD, which can be difficult to diagnose.

Pivotal prognostic and diagnostic role of the long non‑coding RNA colon cancer‑associated transcript 1 expression in human cancer (Review)

Long non‑coding RNAs (lncRNAs) have been classically defined as regulatory RNA members >200 nucleotides in length, without detectable open‑reading frames to encode proteins. Previous studies have demonstrated that lncRNAs serve critical roles in multiple cancer types. Colon cancer‑associated transcript 1 (CCAT1), a novel cancer‑associated lncRNA, is significantly overexpressed in a number of malignancies. Functionally, as an oncogenic lncRNA, CCAT1 is involved in proliferation, migration, cell cycle progression, apoptosis, chemoresistance and other biological processes of cancer cells through complex regulation mechanisms in the cytoplasm or nucleus. In clinical applications, CCAT1 is additionally positively associated with histological differentiation, tumour node metastasis stage, vascular invasion, overall survival and recurrence‑free survival, which demonstrates its important role as a diagnostic and prognostic marker in cancer. The present review summarises the current research progress of the oncogenic potential and clinical uses of CCAT1 in various human cancer types.

CRISPR/Cas9 Knockout Strategies to Ablate CCAT1 lncRNA Gene in Cancer Cells

Background

With the increasing discovery of long noncoding RNAs (lncRNAs), the application of functional techniques that could have very specific, efficient, and robust effects and readouts is necessary. Here, we have applied and analyzed three gene knockout (KO) strategies to ablate the CCAT1 gene in different colorectal adenocarcinoma cell lines. We refer to these strategies as “CRISPR excision”, “CRISPR HDR”, and “CRISPR du-HITI”.

Results

In order to obstruct the transcription of lncRNA or to alter its structure, in these strategies either a significant segment of the gene is removed, or a transcription termination signal is inserted in the target gene. We use RT-qPCR, RNA-seq, MTT, and colony formation assay to confirm the functional effects of CCAT1 gene ablation in knockout colorectal adenocarcinoma cell lines. We applied three different CRISPR/Cas9 mediated knockout strategies to abolish the transcription of CCAT1 lncRNA. CCAT1 knockout cells displayed dysregulation of genes involved in several biological processes, and a significant reduction for anchorage-independent growth. The du-HITI strategy introduced in this study removes a gene segment and inserts a reporter and a transcription termination signal in each of the two target alleles. The preparation of donor vector for this strategy is much easier than that in “CRISPR HDR”, and the selection of cells in this strategy is also much more practical than that in “CRISPR excision”. In addition, use of this technique in the first attempt of transfection, generates single cell knockouts for both alleles.

Conclusions

The strategies applied and introduced in this study can be used for the generation of CCAT1 knockout cell lines and in principle can be applied to the deletion of other lncRNAs for the study of their function.

Electronic supplementary material

The online version of this article (10.1186/s12575-018-0086-5) contains supplementary material, which is available to authorized users.

Interaction of long-chain non-coding RNAs and important signaling pathways on human cancers (Review)

Long non-coding RNAs (lncRNAs) usually refer to non-coding RNA transcripts >200 nucleotides in length. In terms of the full genomic transcript, the proportion of lncRNAs far exceeds that of coding RNA. Initially, lncRNAs were considered to be the transcriptional noise of genes, but it has since been demonstrated that lncRNAs serve an important role in the regulation of cellular activities through interaction with DNA, RNA and protein. Numerous studies have demonstrated that various intricate signaling pathways are closely related to lncRNAs. Here, we focus on a large number of studies regarding the interaction of lncRNAs with important signaling pathways. It is comprehensively illustrated that lncRNAs regulate key metabolic components and regulatory factors of signaling pathways to affect the biological activities of tumor cells. Evidence suggests that the abnormal expression or mutation of lncRNAs in human tumor cells, and their interaction with signaling pathways, may provide a basis and potential target for the diagnosis and treatment of human cancers.

The lncRNA CCAT1 upregulates TGFβR1 via sponging miR-490-3p to promote TGFβ1-induced EMT of ovarian cancer cells

Background

Ovarian cancer is the fifth leading cause of cancer deaths in women worldwide. LncRNACCAT1 was reported to play a critical role in cell metastasis of ovarian cancer. However, little is known about the detailed mechanism of how CCAT1 enhances TGFβ1-induced EMT of ovarian cancer cells.

Methods

We used RT-qPCR to examine the level of miR-490-3p and CCAT1 and western blot to detect the protein level of TGFβR1 and EMT-associated markers. We utilized luciferase reporter assay to confirm the direct interaction of CCAT1 or TGFβ1 with miR-490-3p. Wound healing and invasion assay were employed to investigate the role of CCAT1 and miR-490-3p in the TGFβ1-induced migration and cell invasion of ovarian cancer cells, respectively.

Results

TGFβ1 stimulated the expression of CCAT1. And CCAT1 knockdown decreased cell migration, invasion and EMT-associated markers expression of ovarian cancer cells treated with TGFβ1. CCAT1 directly targeted and downregulated miR-490-3p, then increasing TGFβR1 level. miR-490-3p was shown to regulate cell invasion, migration and EMT markers expression via TGFβR1. In addition, we also observed that miR-490-3p was essential for TGFβ1-induced tumor cell invasion and migration influenced by CCAT1. CCAT1 level was significantly higher in tumors than adjacent normal tissue, in contrast, miR-490-3p level was lower in ovarian tumors.

Conclusion

Here, we reveal that CCAT1 contributes to TGFβ1-induced EMT of ovarian tumor cells through miR-490-3p/TGFR1 axis. These findings will provide deep insights into the mechanism by which CCAT1 exerts its oncogenic role in ovarian cancer progression and facilitate developing novel therapeutical therapies for treating ovarian cancer.

The downregulated long noncoding RNA DHRS4-AS1 is protumoral and associated with the prognosis of clear cell renal cell carcinoma

BACKGROUND

Long noncoding RNAs (lncRNAs) have been identified as important factors in cancer biology and are deregulated in many cancers. The present study aimed to determine the expression and roles of lncRNA DHRS4-AS1 in the progression of clear cell renal cell carcinoma (ccRCC).

METHODS AND RESULTS

Using high-throughput RNA-sequencing data of ccRCC tumors from the Cancer Genome Atlas project, we identified lncRNA DHRS4-AS1 as significantly associated with ccRCC patients' overall survival. We confirmed the downregulation of DHRS4-AS1 in ccRCC by assessing its expression levels in a cohort of 52 tumor and paired non-tumor samples. In addition, we found that low DHRS4-AS1 expression was significantly associated with a high tumor node metastasis stage, lymph node metastasis, advanced pathological grade and poor prognosis. Furthermore, DHRS4-AS1 overexpression inhibited the progression of cell cycles of ccRCC in vitro. These data indicate that DHRS4-AS1 functions by preventing the proliferation and invasion, inhibiting the cell cycle progression and promoting the apoptosis of ccRCC cells.

CONCLUSION

Taken together, our findings identify the role of DHRS4-AS1 as a tumor inhibitor in ccRCC for the first time, demonstrating that DHRS4-AS1 is a potential prognostic biomarker that could potentially be applied in ccRCC therapy.

Long non-coding RNAs as emerging regulators of epithelial to mesenchymal transition in gynecologic cancers

Gynecologic cancer is a vital global healthcare issue with high rates of mortality and morbidity. Tumor metastasis attributes to most of the death suffering from solid tumors. The epithelial-mesenchymal transition (EMT) plays a pivotal role in initiating metastasis. Long non-coding RNAs (lncRNAs), a well-known group of non-coding RNAs, and a prominent topic in life science research, are misregulated in many malignancies and some are EMT-associated. In the case of gynecologic cancers, several EMT-associated lncRNAs have been identified and found to be implicated in cancer aggressiveness and progression. Mechanically, these lncRNAs participate in the EMT-related metastatic process in multiple ways including interaction with polycomb repressive complex 2 (PRC2), regulation of EMT signaling networks, mediation of EMT-transcription factors (EMT-TFs) and EMT markers, and cooperation with microRNAs (miRNAs). Further studies on these EMT-associated lncRNAs and identification of more relevant lncRNAs are imperative for the lncRNAs-based clinical management of high rate of metastasis in patients with gynecologic cancers.

miR-152 inhibits proliferation of human endometrial cancer cells via inducing G2/M phase arrest by suppressing CDC25B expression

microRNA-152 (miR-152) is a tumor suppressor that is down-regulated in many cancers including endometrial cancer (EC). However, the underlying mechanism of action of miR-152 in EC is unclear. The aim of the present study was to evaluate the role of miR-152 on proliferation of human endometrial cancer cells. Herein, we found that miR-152 overexpression and CDC25B knockdown inhibited proliferative ability and induced G2/M phase arrest in KLE and HEC-1B cells. CDC25B was a target of miR-152. In addition, CDC25B overexpression rescued miR-152-induced proliferation inhibition and G2/M phase arrest in human endometrial cancer cells. The results indicated that miR-152 was a tumor suppressor in EC that inhibited proliferation of human endometrial cancer cells via inducing G2/M phase arrest by suppressing CDC25B expression.

LncRNA CASC15 promotes colon cancer cell proliferation and metastasis by regulating the miR‑4310/LGR5/Wnt/β‑catenin signaling pathway

Previous studies have indicated that overexpression of long noncoding RNA cancer susceptibility 15 (CASC15) may promote tumor development and progression in gastric cancer and hepatocellular carcinoma. However, the function of CASC15 in colon cancer remains unknown. In the present study, the expression of CASC15 was upregulated in colon cancer tissues and its expression was correlated with clinical Tumor‑Node‑Metastasis stage and tumor metastasis. In addition, knockdown of CASC15 significantly inhibited the proliferation, migration and invasion of colon cancer cells in vitro and in vivo. Following mechanistic experiments, CASC15 was observed to act as a sponge to suppress microRNA (miR)‑4310 that targeted LGR5. Through the inhibition of miR‑4310, CASC15 promoted leucine‑rich repeat‑containing G‑protein coupled receptor 5 (LGR5) expression and consequently activated the Wnt/β‑catenin signaling pathway. The results revealed that the inhibition of the Wnt/β‑catenin signaling pathway in CASC15‑overexpressing colon cancer cells suppressed cellular proliferation, migration and invasion. Collectively, these results demonstrated that CASC15 promoted colon cancer growth and metastasis through the activation of the Wnt/β‑catenin signaling pathway in a miR‑4310/LGR5 dependent manner. Thus, the present study suggested that CASC15 may be a therapeutic target for colon cancer treatment.

Functional Role of Non-Coding RNAs during Epithelial-To-Mesenchymal Transition

Epithelial-to-mesenchymal transition (EMT) is a key biological process involved in a multitude of developmental and pathological events. It is characterized by the progressive loss of cell-to-cell contacts and actin cytoskeletal rearrangements, leading to filopodia formation and the progressive up-regulation of a mesenchymal gene expression pattern enabling cell migration. Epithelial-to-mesenchymal transition is already observed in early embryonic stages such as gastrulation, when the epiblast undergoes an EMT process and therefore leads to the formation of the third embryonic layer, the mesoderm. Epithelial-to-mesenchymal transition is pivotal in multiple embryonic processes, such as for example during cardiovascular system development, as valve primordia are formed and the cardiac jelly is progressively invaded by endocardium-derived mesenchyme or as the external cardiac cell layer is established, i.e., the epicardium and cells detached migrate into the embryonic myocardial to form the cardiac fibrous skeleton and the coronary vasculature. Strikingly, the most important biological event in which EMT is pivotal is cancer development and metastasis. Over the last years, understanding of the transcriptional regulatory networks involved in EMT has greatly advanced. Several transcriptional factors such as Snail, Slug, Twist, Zeb1 and Zeb2 have been reported to play fundamental roles in EMT, leading in most cases to transcriptional repression of cell⁻cell interacting proteins such as ZO-1 and cadherins and activation of cytoskeletal markers such as vimentin. In recent years, a fundamental role for non-coding RNAs, particularly microRNAs and more recently long non-coding RNAs, has been identified in normal tissue development and homeostasis as well as in several oncogenic processes. In this study, we will provide a state-of-the-art review of the functional roles of non-coding RNAs, particularly microRNAs, in epithelial-to-mesenchymal transition in both developmental and pathological EMT.