Lowly-expressed lncRNA GAS5 facilitates progression of ovarian cancer through targeting miR-196-5p and thereby regulating HOXA5

LncRNA FAM225B Regulates PDIA4-Mediated Ovarian Cancer Cell Invasion and Migration via Modulating Transcription Factor DDX17

Objective

This study aimed to explore the roles and mechanisms of lncRNA FAM225B and PDIA4 in ovarian cancer.

Methods

RT-qPCR and Western blot assays were performed to detect the expression levels of the lncRNAs FAM225B, DDX17, and PDIA4 in the serum of patients with ovarian cancer and cell lines. Cells were transfected with lncRNA FAM225B- and PDIA4-related vectors to determine the malignant phenotypes using functional experiments. The mutual binding of lncRNA FAM225B and DDX17 was verified using RNA pull-down and RIP assays.

Results

The expression of lncRNAs FAM225B and PDIA4 was decreased in the serum of patients with ovarian cancer and cell lines. Restoration of lncRNA FAM225B or PDIA4 reduced cell proliferation, migration, and invasion abilities and elevated the apoptosis rate, whereas suppression of lncRNA FAM225B or PDIA4 exhibited an inverse trend. RNA pull-down and RIP assays revealed a direct interaction between lncRNA FAM225B and DDX17. ChIP assay revealed a relationship between DDX17 and the PDIA4 promoter. LncRNA FAM225B and DDX17 positively regulate PDIA4 expression. Downregulation of PDIA4 expression counteracts the suppressive effect of lncRNA FAM225B overexpression in ovarian cancer cells.

Conclusion

This research study supports the fact that lncRNA FAM225B in ovarian cancer can upregulate PDIA4 by directly binding to DDX17, inhibiting the activities of ovarian cancer cells.

RBM38 Reverses Sorafenib Resistance in Hepatocellular Carcinoma Cells by Combining and Promoting lncRNA-GAS5

BACKGROUND

Hepatocellular carcinoma (HCC) is a life-threatening human malignancy and the fourth leading cause of cancer-related deaths worldwide. Patients with HCC are often diagnosed at an advanced stage with a poor prognosis. Sorafenib is a multikinase inhibitor used as the first-line treatment for patients with advanced HCC. However, acquired resistance to sorafenib in HCC leads to tumor aggression and limits the drug's survival benefits; the underlying molecular mechanisms for this resistance remain unclear.

METHODS

This study aimed to examine the role of the tumor suppressor RBM38 in HCC, and its potential to reverse sorafenib resistance. In addition, the molecular mechanisms underlying the binding of RBM38 and the lncRNA GAS5 were examined. The potential involvement of RBM38 in sorafenib resistance was examined using both in vitro and in vivo models. Functional assays were performed to assess whether RBM38: binds to and promotes the stability of the lncRNA GAS5; reverses the resistance of HCC to sorafenib in vitro; and suppresses the tumorigenicity of sorafenib-resistant HCC cells in vivo.

RESULTS

RBM38 expression was lower in HCC cells. The IC₅₀ value of sorafenib was significantly lower in cells with RBM38 overexpression than in control cells. RBM38 overexpression improved sorafenib sensitivity in ectopic transplanted tumors and suppressed the growth rate of tumor cells. RBM38 could bind to and stabilize GAS5 in sorafenib-resistant HCC cells. In addition, functional assays revealed that RBM38 reversed sorafenib resistance both in vivo and in vitro in a GAS5-dependent manner.

CONCLUSIONS

RBM38 is a novel therapeutic target that can reverse sorafenib resistance in HCC by combining and promoting the lncRNA GAS5.

Long Non-Coding RNA GAS5 Promotes BAX Expression by Competing with microRNA-128-3p in Response to 5-Fluorouracil

The acquisition of drug resistance is a major hurdle for effective cancer treatment. Although several efforts have been made to overcome drug resistance, the underlying mechanisms have not been fully elucidated. This study investigated the role of long non-coding RNA (lncRNA) growth arrest-specific 5 (GAS5) in drug resistance. GAS5 was found to be downregulated in colon cancer cell lines that are resistant to 5-fluorouracil (5-FU). Downregulation of GAS5 decreased the viability of HCT116 cells and the level of the pro-apoptotic BAX protein, while GAS5 overexpression promoted cell death in response to 5-FU. The interaction between GAS5 and BAX mRNA was investigated using MS2-tagged RNA affinity purification (MS2-trap) followed by RT-qPCR, and the results showed that GAS5 bound to the 3'-untranslated region of BAX mRNA and enhanced its expression by interfering with the inhibitory effect of microRNA-128-3p, a negative regulator of BAX. In addition, ectopic expression of GAS5 increased the sensitivity of resistant cells in response to anti-cancer drugs. These results suggest that GAS5 promoted cell death by interfering with miR-128-3p-mediated BAX downregulation. Therefore, GAS5 overexpression in chemo-resistant cancer cells may be a potential strategy to improve the anti-cancer efficacy of drugs.

GAS5 alleviates cisplatin drug resistance in oral squamous cell carcinoma by sponging miR-196a

Objective

The long non-coding RNA Growth-arrest-specific transcript 5 (GAS5) has been extensively linked with the ability of cancer cells to resist chemotherapeutic interventions. This prospective study aimed to investigate the role of GAS5 in oral squamous cell carcinoma (OSCC), which has been poorly characterized to date.

Methods

GAS5 and miR-196a expression levels were detected by quantitative real-time PCR analysis. Cisplatin (DDP) sensitivity and apoptosis levels were determined using Cell Counting Kit 8 and flow cytometry, respectively. Luciferase reporter and RNA immunoprecipitation assays were performed to confirm target miRNAs of GAS5.

Results

We found that GAS5 was expressed at low levels in DDP-resistant OSCC cell lines and tissues, and that GAS5 levels were intricately linked to the survival rates of OSCC patients. GAS5 overexpression led to the recovery of DDP sensitivity in CAL27/DDP cells. Additionally, in both DDP-resistant and -sensitive lines, GAS5 showed a cytoplasmic distribution and downregulated miR-196a in OSCC tissues. Exogenous transfection of miR-196a alleviated the effects of GAS5 on DDP sensitivity, confirming this as the mechanism of chemoresistance.

Conclusions

These findings may provide new targets for the treatment of chemotherapy-resistant OSCC.

Long non-coding RNAs affecting cell metabolism in cancer

Metabolic reprogramming is commonly recognized as one important hallmark of cancers. Cancer cells present significant alteration of glucose metabolism, oxidative phosphorylation, and lipid metabolism. Recent findings demonstrated that long non-coding RNAs control cancer development and progression by modulating cell metabolism. Here, we give an overview of breast cancer metabolic reprogramming and the role of long non-coding RNAs in driving cancer-specific metabolic alteration.

Potential Role of miR-196a and miR-196b as Prognostic Biomarkers of Survival in Head and Neck Squamous Cell Carcinoma: A Systematic Review, Meta-Analysis and Trial Sequential Analysis

The etiopathogenetic mechanisms involving tumor genesis, including alteration of cell proliferation, apoptosis, invasion, migration, and death, may lead to alterations in microRNAs (miR) expression. The hypothesis is that with the presence in the literature of recent studies conducted on miR-196a and miR-196b, it is possible to clearly determine, by aggregating the results, whether miR-196 upregulation in head and neck squamous cell carcinoma (HNSCC) tissues can represent a prognostic biomarker of survival through hazard ratio (HR) analysis. The systematic review was conducted following the indications of the PRISMA, and four electronic databases were used (Science Direct, SCOPUS, PubMed, and Cochrane Central), with the addition of gray literature. Combinations of keywords were used, such as miR-196, miR-196 AND HNSCC, microRNA AND HNSCC, LSCC AND miR-196, OSCC AND miR-196, OPSCC AND miR-196, HSCC AND miR-196. The meta-analysis and trial sequential analysis (TSA) were performed using RevMan 5.41 software and Stata 13 (StataCorp, College Station, TX, USA) with the implementation of the R 4.2 software. This search identified 1593 reports and, at the end of the selection, five articles were inserted. The results of the meta-analysis report an aggregate HR for overall survival (OS), between the highest and lowest miR-196 expression of 1.67, 95% CI: [1.16, 2.49]. In this meta-analysis, we found that the forest plot is in favor of higher OS in HNSCC patients, compared with the control, with low miR-196 expression, correlating this data with a favorable prognosis, which indicated the potential role of this miRNA in strengthening the therapy sensitiveness of the HNSCC patients. Consequently, the present systematic review places itself, together with other systematic reviews on this topic, in a key role to the finding of Phase 3 clinical trials studies, in search for a prognostic model of miR-196 for HNSCC. In conclusion, with the limitations of the meta-analysis, it can be argued that miRs of the miR-196 family could be independent prognostic biomarkers of survival for HNSCC.

Long noncoding RNAs (lncRNAs) in HIV-mediated carcinogenesis: Role in cell homeostasis, cell survival processes and drug resistance

There is accruing data implicating long non-coding RNAs (lncRNAs) in the development and progression of non-communicable diseases such as cancer. These lncRNAs have been implicated in many diverse HIV-host interactions, some of which are beneficial to HIV propagation. The virus-host interactions induce the expression of HIV-regulated long non-coding RNAs, which are implicated in the carcinogenesis process, therefore, it is critical to understand the molecular mechanisms that underpin these HIV-regulated lncRNAs, especially in cancer formation. Herein, we summarize the role of HIV-regulated lncRNAs targeting cancer development-related processes including apoptosis, cell cycle, cell survival signalling, angiogenesis and drug resistance. It is unclear how lncRNAs regulate cancer development, this review also discuss recent discoveries regarding the functions of lncRNAs in cancer biology. Innovative research in this field will be beneficial for the future development of therapeutic strategies targeting long non-coding RNAs that are regulated by HIV, especially in HIV associated cancers.

Research Progress of Long Non-Coding RNA GAS5 in Malignant Tumors

With completing the whole genome sequencing project, awareness of lncRNA further deepened. The growth arrest-specific transcript 5 (GAS5) was initially identified in growth-inhibiting cells. GAS5 is a lncRNA (long non-coding RNA), and it plays a crucial role in various human cancers. There are small ORFs (open reading frames) in the exons of the GAS5 gene sequence, but they do not encode functional proteins. In addition, GAS5 is also the host gene of several small nucleolar RNAs (snoRNA). These snoRNAs are believed to play a suppressive role during tumor progression by methylating ribosomal RNA (rRNA). As a result, GAS5 expression levels in tumor tissues are significantly reduced, leading to increased malignancy, poor prognosis, and drug resistance. Recent studies have demonstrated that GAS5 can interact with miRNAs by base-pairing and other functional proteins to inhibit their biological functions, impacting signaling pathways and changing the level of intracellular autophagy, oxidative stress, and immune cell function in vivo. In addition, GAS5 participates in regulating proliferation, invasion, and apoptosis through the above molecular mechanisms. This article reviews the recent discoveries on GAS5, including its expression levels in different tumors, its biological behavior, and its molecular regulation mechanism in human cancers. The value of GAS5 as a molecular marker in the prevention and treatment of cancers is also discussed.

SNHG1-miR-186-5p-YY1 feedback loop alleviates hepatic ischemia/reperfusion injury

As a common cause of liver injury, hepatic ischemia/reperfusion injury (HIRI) happens in various clinical conditions including trauma, hepatectomy and liver transplantation. Since transcription factor Yin Yang 1 (YY1) was reported to be downregulated after ischemia/reperfusion (I/R) injury, we focused on YY1 to explore its function in HIRI by functional assays like Cell Counting Kit-8 (CCK-8) assays and flow cytometry assays. The RT-qPCR assay revealed that YY1 was downregulated in hepatocytes after I/R injury. The function assays disclosed that YY1 facilitated cell viability and proliferation, but hindered cell apoptosis in hepatocytes after I/R injury. Through mechanism assays including luciferase reporter assay, RIP and RNA pulldown assay, miR-186-5p was found to bind with YY1 and promote hepatocyte apoptosis by targeting YY1. Subsequently, we verified that small nucleolar RNA host gene 1 (SNHG1) could sponge miR-186-5p to upregulate YY1. Importantly, we figured out that YY1 had a positive regulation on SNHG1. Along the way, YY1 was identified as the upstream transcription factor for SNHG1. In conclusion, our study unveiled a novel competing endogenous RNA (ceRNA) pattern of SNHG1/miR-186-5p/YY1 positive feedback loop in hepatic I/R injury, which might provide new insight into prevention of HIRI during liver transplantation or hepatic surgery.

LncRNA PART1 Stimulates the Development of Ovarian Cancer by Up-regulating RACGAP1 and RRM2

Ovarian cancer (OC) is a kind of gynecologic malignancy with a high mortality rate. Long non-coding RNAs (lncRNAs) have been reported to exert regulatory roles in multiple diseases. However, the role of lncRNA prostate androgen-regulated transcript 1 (PART1) has not been investigated in the development of OC. In this study, from RT-qPCR analysis, we discovered that PART1 demonstrated high expression in OC cells. Moreover, data from functional assays manifested that PART1 reduction hindered the proliferative, migratory, and invasive capabilities of OC cells. In vivo uncovered that PART1 knockdown impeded OC tumor growth. Furthermore, from the experimental results of RNA pull down, RIP, and luciferase reporter assays, we discovered that PART1 served as a sponge for microRNA-6884-5p (miR-6884-5p) to modulate the expression of Rac GTPase activating protein 1 (RACGAP1) and ribonucleotide reductase regulatory subunit M2 (RRM2). Finally, rescue assays proved that overexpression of RACGAP1 or RRM2 abrogated the suppressive role of PART1 knockdown on OC cell malignant behaviors. RACGAP1 and RRM2 were also revealed to act as oncogenes in OC cells. In summary, our research verified the PART1/miR-6884-5p/RACGAP1/RRM2 axis in OC cells, which signified that PART1 might act as a novel biomarker in OC.

Long Noncoding RNA GAS5: A New Factor Involved in Bone Diseases

Long noncoding RNAs (lncRNAs), as an important type of RNA encoded in the human transcriptome, have shown to regulate different genomic processes in human cells, altering cell type and function. These factors are associated with carcinogenesis, cancer metastasis, bone diseases, and immune system diseases, among other pathologies. Although many lncRNAs are involved in various diseases, the molecular mechanisms through which lncRNAs contribute to regulation of disease are still unclear. The lncRNA growth arrest-specific 5 (GAS5) is a key player that we initially found to be associated with regulating cell growth, differentiation, and development. Further work has shown that GAS5 is involved in the occurrence and prognosis of bone diseases, such as osteoporosis, osteosarcoma, and postosteoporotic fracture. In this review, we discuss recent progress on the roles of GAS5 in bone diseases to establish novel targets for the treatment of bone diseases.

Long noncoding RNA GAS5 in age-related diseases

Aging refers to a natural process and a universal phenomenon in all cells, tissues, organs and the whole organism. Long non-coding RNAs (lncRNAs) are non-coding RNAs with the length of 200 nucleotides. LncRNA growth arrest-specific 5 (lncRNA GAS5) is often down-regulated in cancer. The accumulation of lncRNA GAS5 has been found to be able to inhibit cancer growth, invasion and metastasis, while enhancing the sensitivity of cells to chemotherapy drugs. LncRNA GAS5 can be a signaling protein, which is specifically transcribed under different triggering conditions. Subsequently, it is involved in signal transmission in numerous pathways as a signal node. LncRNA GAS5, with a close relationship to multiple miRNAs, was suggested to be involved in the signaling pathway under three action modes (i.e., signal, bait and guidance). LncRNA GAS5 was found to be involved in different age-related diseases (e.g., rheumatoid arthritis, type 2 diabetes, atherosclerosis, osteoarthritis, osteoporosis, multiple sclerosis, cancer etc.). This study mainly summarized the regulatory effect exerted by lncRNA GAS5 on age-related diseases.

Hepatitis B virus x gene-downregulated growth-arrest specific 5 inhibits the cell viability and invasion of hepatocellular carcinoma cell lines by activating Y-box-binding protein 1/p21 signaling

The long noncoding RNA growth-arrest specific 5 (GAS5) is a suppressor of many cancers. However, the role and mechanism of action of GAS5 in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) remain unclear. Here, the expression of hepatitis B virus x gene (HBx) mRNA and GAS5 was assessed by qRT-PCR, and western blot analysis was performed to determine the protein expression levels. In addition, the cell viability and invasion of cells were confirmed using  MTT assay and Transwell assay, respectively. The DNA methylation level of GAS5 was measured by methylation-specific PCR. Moreover, RIP assay and RNA pull down assay were carried out to examine the combination of Y-box-binding protein 1 (YBX1) and GAS5. First, our data proved that HBx is increased, while GAS5 is decreased in HCC cell lines. Subsequently, we found that HBx facilitates HCC cell viability and invasion by inhibiting GAS5 expression. Then, we further clarified that HBx induces the DNA methylation of GAS5 by promoting methyltransferase expression, thereby suppressing GAS5 expression. Furthermore, GAS5 binds YBX1 and promotes YBX1 and p21 expression. Finally, the functional analysis revealed that the upregulation of GAS5 could attenuate cell viability and invasion by boosting p21 expression via binding YBX1. Overall, our results demonstrated that HBx promotes HCC progression by inducing GAS5 methylation to reduce its expression. The upregulation of GAS5 suppressed HBV-related HCC by activating YBX1/p21 signaling. Our data provide novel evidence supporting the potential of GAS5 as a treatment target in HBV-related HCC.

Long Non-Coding RNAs as Potential Diagnostic and Prognostic Biomarkers in Breast Cancer: Progress and Prospects

Breast cancer is the most common malignancy among women worldwide, excluding non-melanoma skin cancer. It is now well understood that breast cancer is a heterogeneous entity that exhibits distinctive histological and biological features, treatment responses and prognostic patterns. Therefore, the identification of novel ideal diagnostic and prognostic biomarkers is of utmost importance. Long non-coding RNAs (lncRNAs) are commonly defined as transcripts longer than 200 nucleotides that lack coding potential. Extensive research has shown that lncRNAs are involved in multiple human cancers, including breast cancer. LncRNAs with dysregulated expression can act as oncogenes or tumor-suppressor genes to regulate malignant transformation processes, such as proliferation, invasion, migration and drug resistance. Intriguingly, the expression profiles of lncRNAs tend to be highly cell-type-specific, tissue-specific, disease-specific or developmental stage-specific, which makes them suitable biomarkers for breast cancer diagnosis and prognosis.

The Modulating Mechanisms of miRNA-196 in Malignancies and Its Prognostic Value: A Systematic Review and Meta-Analysis

Accumulating studies have revealed that up- or downregulated miRNA-196 expression correlates with the prognostic value in various malignancies; however, existing single studies lack robust evidence to elucidate the role of miRNA-196 in malignancy. The pooled results showed that the upregulation of miRNA-196 expression was significantly correlated with unfavorable OS [HR 2.14; 95% confidence interval (CI), 1.78-2.57; p < 0.001)] and worse PFS (HR 2.84; 95% CI, 1.29-6.23, P = 0.01) in various malignancies. According to the regulatory mechanisms, studies shown that multiple tumors associated with transcription processes could be modulated by the miRNA-196 family; correspondingly, the miRNA-196 family exerted biological functions that could be regulated by various molecules. The upregulation of miRNA-196a, miRNA-196b and miRNA-196 expression is correlated with significantly unfavorable OS in multiple malignancies; similarly, miRNA-196 overexpression predicts poor PFS in multiple malignancies. Taken together, these findings indicate that miRNA-196a and miRNA-196b may serve as oncogenic molecules and may be potential prognostic biomarkers in multiple malignancies.

LncRNA GAS5 inhibits the proliferation and invasion of ovarian clear cell carcinoma via the miR-31-5p/ARID1A axis

To investigate the role of the lncRNA growth arrest special 5 (GAS5) in ovarian clear cell carcinoma (OCCC), we measured the expression of GAS5 and miR-31-5p in OCCC tissue samples and OCCC cell lines using RT-qPCR. MTT and colony formation assays were used to measure cell viability and colony formation ability. Cell invasion was determined by Transwell assays. The binding between GAS5 and miR-31-5p as well as miR-31-5p and ARID1A was determined by dual-luciferase reporter assays. The ARID1A protein levels were detected using western blotting. Kaplan-Meier curves were used for the analysis of the 5-year survival rate of patients with OCCC. GAS5 and ARID1A levels were significantly decreased, while miR-31-5p levels were strongly elevated in the OCCC tissues and cell lines. Patients with lower GAS5/ARID1A levels had shorter overall survival times. Overexpression of GAS5 or inhibition of miR-31-5p suppressed cell viability and invasion of OCCC cells and upregulated the protein levels of ARID1A. Moreover, overexpression of miR-31-5p reversed the effects of overexpression of GAS5. Cotransfection with pcDNA3.1-GAS5 and miR-31-5p inhibitor led to the lowest cell viability and cell invasion rates. A dual-luciferase reporter assay was performed to confirm the target relationship between GAS5 and miR-31-5p, as well as between miR-31-5p and ARID1A. LncRNA GAS5 inhibited cell viability and invasion of OCCC through activation of ARID1A by sponging miR-31-5p.

Metastatic colorectal cancer: Perspectives on long non-coding RNAs and promising therapeutics

Metastatic colorectal cancer (mCRC) has long been lethal despite the continuous efforts of researchers worldwide to discover and improve therapeutic regimens. Thanks to the emergence of long non-coding RNAs (lncRNAs), which has strongly reshaped our inherent perspectives on the pathophysiological patterns of disease, research in the field has been reinvigorated. Here, we focus on current understanding of the modes of action of lncRNAs, and review their regulatory roles in metastatic colorectal cancer, and discuss correlated potential lncRNA-based therapeutics. All of the discussed studies share clear and promising perspectives on future diagnostic and therapeutic remedies for metastatic colorectal cancer.

Long non-coding RNAs: A view to kill ovarian cancer

An emerging role of long non-coding RNAs (lncRNAs) in tumor progression has been revealed in the last decade. Through interactions with nucleic acids and proteins, lncRNAs could act as enhancers, scaffolds or decoys for a number of oncoproteins and tumor suppressors. The aberrant lncRNA expression or mutations are often associated with changes in a variety of cellular processes, including proliferation, stress response and cell death. Here, we will focus on the tumor-associated lncRNAs in ovarian cancer according to their contribution to cancer hallmarks, such as intense proliferation, cell death resistance, altered energy metabolism, invasion and metastasis, and immune evasion. Moreover, the potential clinical implications of lncRNAs and their significance for the diagnosis, prognosis and therapy of ovarian cancer will be discussed.

Long Noncoding RNA GAS5 Targeting miR-221-3p/Cyclin-Dependent Kinase Inhibitor 2B Axis Regulates Follicular Thyroid Carcinoma Cell Cycle and Proliferation

INTRODUCTION

Follicular thyroid carcinoma (FTC) is more aggressive than the most common papillary thyroid carcinoma (PTC). However, the current research on FTC is less than PTC. Here, we investigated the effects of long noncoding RNA (lncRNA) GAS5 and miR-221-3p in FTC.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to detect GAS5 and miR-221-3p expression in the FTC tissues and cells. Cell proliferation was assessed by CCK8 and EdU assays. Flow cytometry was performed to determine the cell cycle. The dual-luciferase reporter assay was employed to validate the binding relationship of GAS5/miR-221-3p and miR-221-3p/cyclin-dependent kinase inhibitor 2B (CDKN2B). Western blot was conducted to measure the protein level of CDKN2B.

RESULTS

Our results displayed that GAS5 was downregulated, while miR-221-3p was upregulated in FTC tissues and cells. What's more, overexpression of GAS5 or miR-221-3p inhibition induced G0/G1 phase arrest and inhibited cell proliferation of FTC cells. GAS5 acted as a sponge of miR-221-3p, and CDKN2B was a target gene of miR-221-3p. Additionally, GAS5 inhibited cell cycle and proliferation of FTC cells via reducing miR-221-3p expression to enhance CDKN2B expression.

CONCLUSION

GAS5 induced G0/G1 phase arrest and inhibited cell proliferation via targeting miR-221-3p/CDKN2B axis in FTC. Thus, GAS5 may be a potential therapeutic target for the treatment of FTC.

Deciphering the Long Non-Coding RNAs and MicroRNAs Coregulation Networks in Ovarian Cancer Development: An Overview

Non-coding RNAs are emergent elements from the genome, which do not encode for proteins but have relevant cellular functions impacting almost all the physiological processes occurring in eukaryotic cells. In particular, microRNAs and long non-coding RNAs (lncRNAs) are a new class of small RNAs transcribed from the genome, which modulate the expression of specific genes at transcriptional and posttranscriptional levels, thus adding a new regulatory layer in the flux of genetic information. In cancer cells, the miRNAs and lncRNAs interactions with its target genes and functional pathways are deregulated as a consequence of epigenetic and genetic alterations occurring during tumorigenesis. In this review, we summarize the actual knowledge on the interplay of lncRNAs with its cognate miRNAs and mRNAs pairs, which interact in coregulatory networks with a particular emphasis on the mechanisms underlying its oncogenic behavior in ovarian cancer. Specifically, we reviewed here the evidences unraveling the relevant roles of lncRNAs/miRNAs pairs in altered regulation of cell migration, angiogenesis, therapy resistance, and Warburg effect. Finally, we also discussed its potential clinical implications in ovarian cancer and related endocrine disease therapies.

Mechanisms of Apoptosis-Related Long Non-coding RNAs in Ovarian Cancer

Ovarian cancer is a health-threatening malignancy of ovary in female reproductive systems and one of the most common gynecological malignancies worldwide. Due to rare early symptoms, ovarian cancers are often diagnosed at advanced stages and exhibit poor prognosis. Thus, efforts have been paid to develop alternative diagnostic and therapeutic strategies for the disease. Recent studies have presented that some long non-coding RNAs (lncRNAs) play roles in apoptosis of ovarian cancer cells through various mechanisms involved in the regulation of transcription factors, histone modification complexes, miRNAs, and protein stability. Because evasion of apoptosis in cancer cells facilitates to promote tumor progression and therapy resistance, apoptosis regulatory mechanisms of lncRNAs may be promising new targets in ovarian cancer. In this review, we introduce the recent findings in regard to the molecular mechanisms of apoptosis-related lncRNAs in ovarian cancer cells.

LncRNA ARAP1-AS1 aggravates the malignant phenotypes of ovarian cancer cells through sponging miR-4735-3p to enhance PLAGL2 expression

Ovarian cancer is one of the leading lethal gynecological cancers, causing serious harm to the health of female populations. Growing studies emphasize that lncRNAs serve as significant regulators in the tumorigenesis and evolution of numerous malignancies, including ovarian cancer. Recently, the oncogenic activity of lncRNA ARAP1-AS1 has been justified in a variety of cancers. However, the potential function of ARAP1-AS1 in ovarian cancer development is still unclear. Herein, we firstly revealed the expression profile of ARAP1-AS1 in ovarian cancer. Compared to normal samples and cells, upregulation of ARAP1-AS1 was observed in tissues and cells of ovarian cancer. Therewith, it was disclosed that knockdown of ARAP1-AS1 alleviated the carcinogenicity of ovarian cancer cells. Besides, our findings delineated that ARAP1-AS1 silence inhibited the expression of oncogene PLAGL2. Considering that ARAP1-AS1 was principally expressed in the the cytoplasm of ovarian cancer cells, we speculated that ARAP1-AS1 facilitated ovarian cancer progression via functioning as a ceRNA. Further investigations indicated that ARAP1-AS1 promoted PLAGL2 expression by competitively binding with miR-4735-3p. Of note, ARAP1-AS1 contributed to the malignant phenotypes of ovarian cancer cells through modulation of miR-4735-3p/PLAGL2 axis, revealing ARAP1-AS1 as a promising therapeutic target for ovarian cancer patients.

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.

The LINC00477/miR-128 axis promotes the progression of polycystic ovary syndrome by regulating ovarian granulosa cell proliferation and apoptosis

BACKGROUND

Long noncoding RNAs (lncRNAs) participate in the pathogenesis of various human diseases. This study aims to investigate the roles of lncRNA LINC00477 in polycystic ovary syndrome (PCOS), especially the impacts of LINC00477 on the proliferation and migration of human granulosa cells and the related mechanisms.

METHODS

qRT-PCR analysis was performed to examine the expression pattern of LINC00477 in serum samples of PCOS patients as well as PCOS animal models. The effect of LINC00477 on the viability and apoptosis of ovarian granulosa cells was detected by MTT and flow cytometry assays. The correlation between LINC00477 and miR-128 was verified by bioinformatics analysis and dual-luciferase reporter and RNA pull-down assays. Finally, rescue assays were performed to analyze the effects of the LINC00477-miR-128 axis on the biological behaviors of granulosa cells.

RESULTS

LINC00477 was significantly upregulated in the serum of PCOS patients as well as PCOS mouse models. LINC00477 overexpression inhibited the proliferation and promoted the apoptosis of granulosa cells, whereas knockdown of LINC00477 yielded the opposite effects. Moreover, miR-128 mimics partially abrogated the effect of LINC00477 on granulosa cells.

CONCLUSION

LINC00477 may function as a ceRNA to inhibit proliferation and apoptosis of granulosa cells by modulating miR-128 expression.

Expression of long-chain noncoding RNA GAS5 in osteoarthritis and its effect on apoptosis and autophagy of osteoarthritis chondrocytes

OBJECTIVE

To investigate the expression of long-chain noncoding RNA GAS5 in osteoarthritis (OA) and the effect of silencing GAS5 on autophagy of osteoarthritis chondrocytes (OACs).

METHODS

OA rat models were constructed by cutting the anterior cruciate ligament, and the expressions of GAS5 in rat cartilage tissues at 4 weeks (early OA) and 12 weeks (late OA) after modeling were detected. The rat chondrocytes were isolated, cultured and transfected with si-GAS5 to silencing GAS5. Then, the changes of apoptosis and autophagy levels of OA chondrocytes were detected by transfection of GFP-LC3 and flow cytometry. Bioinformatic tools were used to analyze the miRNA binding to GAS5 and the downstream target genes, then luciferase reporter assay and GDC-0349 (inhibitor of mTOR) were used to verify their relationships.

RESULTS

The expression of GAS5 in cartilage tissue of OA rats was higher than control, which was higher in late OA than that in early OA. After silencing the GAS5, the autophagy ability of OACs was increased and the apoptosis rate was decreased. GAS5 was able to bind to miR-144 and regulate the expressin of mTOR. mTOR inhibitor GDC-0349 could reverse the inhibition of GAS5 on autophagy but could not reverse its effect on apoptosis.

CONCLUSION

GAS5 expresses highly in OA cartilage tissues and increases with the progression of OA. GAS5 inhibits autophagy and promotes the apoptosis of OACs, and the inhibition of autophagy may be related to its regulation of mTOR.

LncRNA GAS5 Suppressed Proliferation and Promoted Apoptosis in Laryngeal Squamous Cell Carcinoma by Targeting MiR-26a-5p and Modifying ULK2

Purpose

Long noncoding RNAs growth arrest-specific 5 (GAS5) exerts important functions in modulating various tumor behaviors. However, the role of lncRNA GAS5 in laryngeal squamous cell carcinoma (LSCC) remains unknown.

Materials and Methods

Cell viability and apoptosis were, respectively, detected by cell counting kit-8 and flow cytometry, DIANA-LncBase V, Starbase, TargetScan and a dual-luciferase reporter gene assay were employed to assess the relationship among GAS5, miR-26a-5p and uncoordinated 51-like kinase 1 (ULK2), and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot were performed to detect the expression of autophagy-relative factors.

Results

The expression level of GAS5 was frequently decreased in LSCC cell lines, and up-regulated GAS5 inhibited AMC-HN-8 cells viability and induced apoptosis. More importantly, we found that GAS5 activated autophagy, with enhanced autophagy-related proteins after GAS5 overexpression. While down-regulated GAS5 had opposite results in Tu 177 cells, GAS5 was found to act as a microRNA sponge in a pathway to regulate miR-26a-5p and its target gene ULK2. MiR-26a-5p mimics inhibited apoptosis and autophagy, which were reversed by GAS5 and siGAS5 in AMC-HN-8 cells and Tu 177 cells, as well as ULK2 in AMC-HN-8 cells. Meanwhile, the concomitant downregulation of ULK2 and miRNA-26a-5p inhibitor decreased the miRNA-26a-5p inhibitor-induced apoptosis and autophagy.

Conclusion

This is the first report of LncRNA GAS5 acting as a tumor suppressor in LSCC by regulating the miR-26a-5p/ULK2 axis, and it could be a new target for gene therapy in LSCC.

The essential role of long non-coding RNA GAS5 in glioma: interaction with microRNAs, chemosensitivity and potential as a biomarker

Glioma is a malignant brain tumor with a generally poor prognosis. Dysregulation of a long non-coding RNA, GAS5, has been detected in numerous cancers, including glioma. Previous studies have suggested that GAS5 plays a significant functional role in glioma, affecting proliferation, metastasis, invasion, and apoptosis. In this review, we describe the roles and mechanisms of GAS5 in glioma. GAS5 may be a biomarker for diagnosis and prognosis, and even a potential target for glioma treatment, and therefore warrants further investigation.

Mitochondrial long non-coding RNA GAS5 tunes TCA metabolism in response to nutrient stress

Organelles use specialized molecules to regulate their essential cellular processes. However, systematically elucidating the subcellular distribution and function of molecules such as long non-coding RNAs (lncRNAs) in cellular homeostasis and diseases has not been fully achieved. Here, we reveal the diverse and abundant subcellular distribution of organelle-associated lncRNAs from mitochondria, lysosomes and endoplasmic reticulum. Among them, we identify the mitochondrially localized lncRNA growth-arrest-specific 5 (GAS5) as a tumour suppressor in maintaining cellular energy homeostasis. Mechanistically, energy-stress-induced GAS5 modulates mitochondrial tricarboxylic acid flux by disrupting metabolic enzyme tandem association of fumarate hydratase, malate dehydrogenase and citrate synthase, the canonical members of the tricarboxylic acid cycle. GAS5 negatively correlates with levels of its associated mitochondrial metabolic enzymes in tumours and benefits overall survival in individuals with breast cancer. Together, our detailed annotation of subcellular lncRNA distribution identifies a functional role for lncRNAs in regulating cellular metabolic homeostasis, highlighting organelle-associated lncRNAs as potential clinical targets to manipulate cellular metabolism and diseases.

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.

Silencing of lncRNA DLEU1 inhibits tumorigenesis of ovarian cancer via regulating miR-429/TFAP2A axis

Long non-coding RNAs (lncRNAs) are known as crucial regulators in the development of OC. In the current study, we aim to explore the function and molecular mechanism of lncRNA DLEU1 in OC. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to determine the expression of DLEU1, miR-429, and TFAP2A in OC cells and tissues. The relationship among DLEU1, miR-429, and TFAP2A was tested by dual-luciferase reporter (DLR) assay. Besides, the proliferative, migratory and invasive abilities of OC cells were analyzed by MTT, wound healing, and transwell assays, respectively. Western blot was performed to determine the protein expression of TFAP2A. The expression of lncRNA DLEU1 and TFAP2A were upregulated, and miR-429 was downregulated in OC tissues. Silencing of DLEU1 inhibited the proliferation, migration, and invasion of OC cells. Bioinformation and DLR assay showed that DLEU1 acted as the sponge for miR-429. Moreover, miR-429 could directly target TFAP2A and inhibit the proliferation, migration, and invasion of OC cells. Moreover, we observed a negative correlation between miR-429 and DLEU1, and between miR-429 and TFAP2A in OC tissues. The transfection of miR-429 inhibitor or pcDNA-TFAP2A reversed the inhibitory effects of si-DLEU1 on the proliferation, migration, and invasion of OC cells. Silencing of DLEU1 inhibited the proliferation, migration, and invasion of OC cells by regulating miR-429/TFAP2A axis, indicating a potential therapeutic target for OC.

MiR-196: emerging of a new potential therapeutic target and biomarker in colorectal cancer

Deregulation of microRNAs, as key elements in colorectal cancer (CRC) pathogenesis, is correlated with various stages of this cancer. miR-196 is involved in the initiation and progression of a verity of malignances, especially CRC. miR-196 in CRC cells could target different types of genes with oncogenic and/or tumor suppressor function such as HOX genes, GATA6, SOCS1, SOCS3, ANXA1, DFFA, PDCD4, ZG16 and ING5. Therefore, these genes could be up or down-regulated in cells and subsequently change the capacity of CRC cells in terms of tumor development, progression and, response to therapy. Comprehension of miR-196-associated aberrations underlying the CRC pathogenesis might introduce promising targets for therapy. Additionally, it seems that miR-196 expression profiling, especially circulatory exosomal miR-196, might be useful for diagnosis and prognosis determination of the CRC patients. In this review, at first, we summarize the roles of miR-196 in different types of cancers. After that, a detailed discussion about this miRNA and also their targets in CRC pathogenesis, progression, and response to treatment are represented. Moreover, we highlight the potential utilization of miR-196 and its targets as therapeutic targets and novel biomarkers in early detection and prediction of prognosis in CRC patients.

Long non-coding RNAs in ovarian cancer: expression profile and functional spectrum

Long non-coding RNAs (lncRNAs), initially recognized as byproducts of the transcription process, have been proven to play crucial modulatory roles in preserving overall homoeostasis of cells and tissues. Furthermore, aberrant levels of these transcripts have been shown to contribute many diseases, including cancer. Among these, many aspects of ovarian cancer biology have been found to be regulated by lncRNAs, including cancer initiation, progression and dissemination. In this review, we summarize recent studies to highlight the various roles of lncRNAs in ovary in normal and pathological conditions, immune system, diagnosis, prognosis, and therapy. We address lncRNAs that have been extensively studied in ovarian cancer and their contribution to cellular dynamics.

Long non‑coding RNA PCAT6 promotes the development of osteosarcoma by increasing MDM2 expression

Osteosarcoma is a severe malignant tumor. Several studies indicated that lncRNA prostate cancer-associated transcript 6 (PCAT6) promoted the development of multiple types of cancers. Studies have also revealed that MDM2 could aggravate tumor symptoms inhibiting P53 expression. However, whether lncRNA PCAT6 could affect the proliferation and metastasis of osteosarcoma cells by regulating P53 expression is unclear. The present study established lncRNA PCAT6-overexpressing osteosarcoma cells. Cell Counting Kit-8, wound healing and Transwell assays were performed to detect the change in proliferation, migration and invasion of these cells, respectively. Subsequently, E3 ubiquitin-protein ligase Mdm2 (MDM2), P53 and P21 expression were determined using western blotting. Finally, MDM2 expression was inhibited and the proliferation, migration and invasion of these cells was determined again. The present study found that the proliferation, migration and invasion of osteosarcoma cells increased following overexpression of lncRNA PCAT6. MDM2 expression was upregulated while the levels of P53 and P21 decreased following overexpression of lncRNA PCAT6. However, the proliferation, migration and invasion of osteosarcoma cells were inhibited following MDM2 knockdown. Additionally, P53 and P21 was rescued following MDM2 knockdown. To conclude, lncRNA PCAT6 promoted the proliferation, migration and invasion of osteosarcoma cells by promoting the expression of MDM2 and suppressing the expression of P53 and P21.

The Non-Coding RNA GAS5 and Its Role in Tumor Therapy-Induced Resistance

The growth arrest-specific transcript 5 (GAS5) is a >200-nt lncRNA molecule that regulates several cellular functions, including proliferation, apoptosis, invasion and metastasis, across different types of human cancers. Here, we reviewed the current literature on the expression of GAS5 in leukemia, cervical, breast, ovarian, prostate, urinary bladder, lung, gastric, colorectal, liver, osteosarcoma and brain cancers, as well as its interaction with various miRNAs and its effect on therapy-related resistance in these malignancies. The general consensus is that GAS5 acts as a tumor suppressor across different tumor types and that its up-regulation results in tumor sensitization to chemotherapy or radiotherapy. GAS5 seems to play a previously unappreciated, but significant role in tumor therapy-induced resistance.

Long Non-Coding Small Nucleolar RNA Host Genes (SNHGs) in Endocrine-Related Cancers

Long non-coding RNAs (lncRNAs) are emerging regulators of a diverse range of biological processes through various mechanisms. Genome-wide association studies of tumor samples have identified several lncRNAs, which act as either oncogenes or tumor suppressors in various types of cancers. Small nucleolar RNAs (snoRNAs) are predominantly found in the nucleolus and function as guide RNAs for the processing of transcription. As the host genes of snoRNAs, lncRNA small nucleolar RNA host genes (SNHGs) have been shown to be abnormally expressed in multiple cancers and can participate in cell proliferation, tumor progression, metastasis, and chemoresistance. Here, we review the biological functions and emerging mechanisms of SNHGs involved in the development and progression of endocrine-related cancers including thyroid cancer, breast cancer, pancreatic cancer, ovarian cancer and prostate cancer.

Long non-coding RNA GAS5 in human cancer

Long non-coding RNAs (lncRNAs) constitute a group of >200-nucleotide ncRNA molecules. lncRNAs regulate several cell functions, such as proliferation, apoptosis, invasion and metastasis. Meanwhile, lncRNAs are abnormally expressed in human malignancies, where they suppress or promote tumor growth. The present study focused on growth arrest-specific transcript 5 (GAS5), a well-known lncRNA that acts as a tumor suppressor but is suppressed in multiple types of cancer, including mammary carcinoma, prostate cancer, colorectal cancer, gastric cancer, melanoma, esophageal squamous cell carcinoma, lung cancer, ovarian cancer, cervical cancer, gliomas, osteosarcoma, pancreatic cancer, bladder cancer, kidney cancer, papillary thyroid carcinoma, neuroblastoma, endometrial cancer and liver cancer. Notably, GAS5 is overexpressed in liver cancer, potentially functioning as an oncogene. In the present study, the diagnostic and therapeutic roles of GAS5 in different tumors were reviewed, with a summary of the potential clinical application of the lncRNA, which may help identify novel study directions for GAS5.

Long non-coding RNA GAS5, by up-regulating PRC2 and targeting the promoter methylation of miR-424, suppresses multiple malignant phenotypes of glioma

PURPOSE

Malignant gliomas remain significant challenges in clinic and pose dismal prognosis on patients. In this study, we focused on growth arrest-specific 5 (GAS5), a tumor suppressive long non-coding RNA in glioma, explored its crosstalk with miR-424, and examined their biological functions in glioma.

METHODS

Expressions of GAS5 and miR-424 were measured using qRT-PCR. The regulation of GAS5 on miR-424 expression was examined in GAS5-overexpressing glioma cells by combining methylation-specific PCR, western blotting, and RNA immunoprecipitation. Functional significance of GAS5 and miR-424 on in vitro cell proliferation, apoptosis, migration, invasion, and in vivo tumor growth was examined using colony formation, flow cytometry, wound healing, transwell assay, and the xenograft model, respectively. The potential targeting of AKT3 by miR-424 was investigated using luciferase reporter assay.

RESULTS

GAS5 and miR-424 were significantly down-regulated in glioma cells. GAS5 directly interacted with enhancer of zeste homolog 2 (EZH2), stimulated the formation of polycomb repressive complex 2 (PRC2), reduced the levels of DNA methyltransferases (Dnmts), alleviated promoter methylation of miR-424, and promoted miR-424 expression. Functionally, GAS5, by up-regulating miR-424, inhibited cell proliferation, migration, and invasion, while increased apoptosis of glioma cells in vitro, and suppressed xenograft growth in vivo. miR-424 directly inhibited AKT3 and altered the expressions of AKT3 targets, cyclinD1, c-Myc, Bax, and Bcl-2, which might contribute to its tumor suppressive activities.

CONCLUSIONS

GAS5, by inhibiting methylation and boosting expression of miR-424, inhibits AKT3 signaling and suppresses multiple malignant phenotypes. Therefore, stimulating GAS5/miR-424 signaling may benefit the treatment of glioma.

Downregulated Long Noncoding RNA DGCR5 Acts as a New Promising Biomarker for the Diagnosis and Prognosis of Ovarian Cancer

Emerging evidence have indicated that dysregulated long noncoding ribonucleic acids act as a novel diagnostic and therapeutic target in the progression of ovarian cancer. Long noncoding RNA DiGeorge syndrome critical region gene 5 has been reported to participate in some types of human cancer progresses, but its clinical roles in ovarian cancer had been rarely reported. This study aimed to explore the expression, clinicopathological features, diagnostic, and prognostic values of DiGeorge syndrome critical region gene 5 in ovarian cancer. The total levels of DiGeorge syndrome critical region gene 5 transcript variant 1 (NR_002733.2) and 2 (NR_045121.1) in patients with ovarian cancer were determined by quantitative reverse transcription polymerase chain reaction. The correlation of DiGeorge syndrome critical region gene 5 expression with clinicopathological factors was statistically analyzed by χ² test. Overall survival analysis was carried out with the Kaplan–Meier curves with the log-rank test. Univariate and multivariate Cox regression analyses were performed to identify the prognostic significance of DiGeorge syndrome critical region gene 5 expression. Receiver operating characteristic curves were constructed to estimate the diagnostic and prognostic usefulness of DiGeorge syndrome critical region gene 5 in ovarian cancer. Results showed that relative DiGeorge syndrome critical region gene 5 expression was reduced by 36.81% and 65.79% in ovarian cancer tissues of patients and Gene Expression Omnibus DataSets (GSE119056) in contrast to normal tissues, respectively. Patients with lymph node metastasis and distant metastasis exhibited lower levels of DiGeorge syndrome critical region gene 5 in contrast to those patients with non-lymph node metastasis and non-distant metastasis, respectively. Low expression of DiGeorge syndrome critical region gene 5 was significantly associated with large tumor size, more lymph node metastasis, present distant metastasis, advanced clinical stage, and short overall survival in patients with ovarian cancer. Low expression of DiGeorge syndrome critical region gene 5 was an independent unfavorable prognostic factor for overall survival in patients with ovarian cancer. Receiver operating characteristics curves for prognosis yielded significant area under curves for lymph node metastasis, clinical stage, and overall survival. In conclusion, our study demonstrated that downregulated DiGeorge syndrome critical region gene 5 may be a new promising biomarker for predicting clinical progression and prognosis in patients with ovarian cancer.

The Challenges and Opportunities of LncRNAs in Ovarian Cancer Research and Clinical Use

Ovarian cancer is one of the most lethal gynecological malignancies worldwide because it tends to be detected late, when the disease has already spread, and prognosis is poor. In this review we aim to highlight the importance of long non-coding RNAs (lncRNAs) in diagnosis, prognosis and treatment choice, to make progress towards increasingly personalized medicine in this malignancy. We review the effects of lncRNAs associated with ovarian cancer in the context of cancer hallmarks. We also discuss the molecular mechanisms by which lncRNAs become involved in cellular physiology; the onset, development and progression of ovarian cancer; and lncRNAs' regulatory mechanisms at the transcriptional, post-transcriptional and post-translational stages of gene expression. Finally, we compile a series of online resources useful for the study of lncRNAs, especially in the context of ovarian cancer. Future work required in the field is also discussed along with some concluding remarks.

Overexpression of Growth-Arrest-Specific Transcript 5 Improved Cisplatin Sensitivity in Hepatocellular Carcinoma Through Sponging miR-222

Long noncoding RNA growth-arrest-specific transcript 5 (GAS5) has been proved to play a crucial role in cancer chemoresistance. However, the function of GAS5 and its underlying molecular mechanism in hepatocellular carcinoma (HCC) chemoresistance remain unknown. In this study, we aimed to investigate its function and underlying molecular mechanism in HCC cisplatin (CDDP) resistance. The results demonstrated that GAS5 was significantly downregulated in HCC tissues and cells, especially in CDDP-resistant HCC tissues and cells. Low GAS5 expression was tightly correlated with shorter survival in patients with HCC. Functionally, GAS5 overexpression sensitized CDDP-resistant HepG2/CDDP and Huh7/CDDP cells to CDDP. Mechanically, GAS5 improved the sensitivity of HCC cells to CDDP through sponging miR-222. Taken together, these observations suggested that overexpression of GAS5 overcame CDDP resistance of HCC cells by regulating miR-222, providing a potential therapeutic target for overcoming the chemoresistance of HCC cells.

GAS5 knockdown ameliorates apoptosis and inflammatory response by modulating miR-26b-5p/Smad1 axis in cerebral ischaemia/reperfusion injury

Ischemic stroke (IS) caused by cerebral arterial embolism remains the leading cause of disability and death worldwide. Cerebral ischemia / reperfusion (CI / R) injury is one of the common complications of ischemic stroke. Growth arrest specific transcript 5 (GAS5) has been found to be abnormally expressed in various tumors. However, the role and potential molecular mechanisms of GAS5 in CI / R-induced injury remain unknown. This study established a CI / R injury model in vivo and in vitro. The results showed that the expression of GAS5 was increased in CI / R rats, while miR-26b-5p expression was decreased. Besides, knockdown of GAS5 by siRNA (si-GAS5) reversed CI / R-induced apoptosis and inflammatory responses. Notably, bioinformatics analysis indicated that GAS5 competitively adsorbed miR-26b-5p, and the relationship was further confirmed by pull-down assay. In addition, miR-26b-5p overexpression reversed CI / R-induced apoptosis and inflammatory responses, whereas low expression of miR-26b-5p had the opposite effect. Moreover, TargetScan assay predicted that drosophila mothers against decapentaplegic protein 1 (Smad1) was a target of miR-26b-5p, and miR-26b-5p overexpression inhibited Smad1 expression. Conversely, Smad1 overexpression reversed the inhibitory effect of miR-26b-5p on CI / R-induced apoptosis and inflammatory responses in rats. Collectively, these results indicate that GAS5 knockdown can improve apoptosis and inflammatory responses by modulating the miR-26b-5p / Smad1 axis in CI / R rats.

Long noncoding RNA GAS5 inhibits cell proliferation and fibrosis in diabetic nephropathy by sponging miR-221 and modulating SIRT1 expression

Diabetic nephropathy (DN) is one of the leading causes of end-stage renal diseases worldwide. This study is designed to investigate the underlying function and mechanism of a novel lncRNA GAS5 in the progression of DN. We found that lncRNA GAS5 expression level was decreased in type 2 diabetes (T2D) with DN compared with that in patients without DN. Moreover, lncRNA GAS5 expression level was negatively associated with the severity of DN-related complications. lncRNA GAS5 inhibited MCs proliferation and caused G0/1 phase arrest. lncRNA GAS5 overexpression alleviated the expression of fibrosis-related protein in mesangial cells (MCs). The dual-luciferase reporter assay and RNA binding protein immunoprecipitation (RIP) assay results revealed that lncRNA GAS5 functions as an endogenous sponge for miR-221 via both the directly targeting way and Ago2-dependent manner. Furthermore, SIRT1 was confirmed as a target gene of miR-221. lncRNA GAS5 upregulated SIRT1 expression and inhibited MCs proliferation and fibrosis by acting as an miR-221 sponge. Finally, we found that lncRNA GSA5 suppressed the development of DN in vivo. Thus, lncRNA GAS5 was involved in the progression of DN by sponging miR-221 and contributed to lncRNA-directed diagnostics and therapeutics in DN.

Novel Tumor Suppressor lncRNA Growth Arrest-Specific 5 (GAS5) In Human Cancer

Long noncoding RNAs (lncRNAs) play crucial regulatory roles in fundamental biological processes, and deregulations of lncRNAs have been linked to numerous human diseases, especially cancers. Of particular interest in this regard is lncRNA GAS5, which is mainly identified as a tumor suppressor in several cancers. GAS5 was significantly low expressed in multiple cancers and was associated with clinic-pathological characteristics and patient survival, indicating a novel potential diagnostic and prognostic biomarker, and a therapeutic target for cancer. Functionally, GAS5 is involved in cell proliferation, metastasis, invasion, apoptosis, epithelial-mesenchymal transition (EMT), and drug resistance, among others, via multiple molecular mechanisms, such as binding to DNA sequences, forming RNA-DNA triplex complex, triggering or suppressing the expression of genes, binding proteins to form chromatin-modifying complex, which activates or represses gene expression, and acting as miRNA sponge to suppress miRNA expression, leading to regulation of miRNA target genes. This review provides an overview of the current state of knowledge and role of GAS5 in clinical relevance, biological functions and molecular mechanisms underlying the dysregulation of expression and function of GAS5 in cancer. Finally, the potential prospective role as diagnostic and prognostic biomarker and therapeutic target in cancer is discussed.

LncRNA GAS5 facilitates nasopharyngeal carcinoma progression through epigenetically silencing PTEN via EZH2

Increasing evidence demonstrated that long non-coding RNA growth-arrest-specific transcript 5 (GAS5) serves as a critical regulator in cancer development and progression. However, its function and mechanism in nasopharyngeal carcinoma (NPC) is still not well elucidated. In this study, we investigate the functional role as well as the molecular mechanism of GAS5 in NPC progression. Our results indicated that GAS5 expression was elevated in NPC tissues and cells. High GAS5 expression was correlated with poor prognosis of NPC patients. GAS5 knockdown suppressed proliferation, migration and invasion, and induced apoptosis in NPC cells. Moreover, GAS5 could epigenetically suppress PTEN expression via recruiting enhancer of zeste homolog 2 (EZH2). PTEN knockdown could reverse the inhibitory effect of GAS5 inhibition on NPC progression. Furthermore, GAS5 knockdown suppressed the tumor growth in vivo. In summary, knockdown of GAS5 repressed proliferation, migration and invasion, and promoted apoptosis in NPC through epigenetically silencing PTEN via recruiting EZH2.

HOX Genes in High Grade Ovarian Cancer

HOX genes are highly conserved members of the homeobox superfamily that have a crucial role in determining cellular identity. High grade ovarian cancer is the most lethal gynaecological malignancy. Our understanding of the role of HOX genes in the oncogenesis of ovarian cancer is evolving, and here we review their dysregulated expression patterns, their function in cell survival and invasion, their potential uses as biomarkers, and ways in which HOX genes are being targeted with new and existing drugs.

Downregulated Long Noncoding RNA GAS5 Fails to Function as Decoy of CEBPB, Resulting in Increased GDF15 Expression and Rapid Ovarian Cancer Cell Proliferation

Introduction: Growth differentiation factor 15 (GDF15), a newly identified member of transforming growth factor (GDF) superfamily, is upregulated in ovarian (OV) cancer. Upregulated GDF15 positively correlates with poor prognosis of OV cancer. Thus, elucidation of the mechanism underlying GDF15 overexpression is important. Method and Results: PROMO and JASPAR prediction software were used to find transcription factors for GDF15 expression. Data from TCGA database were analyzed to find long noncoding RNAs (lncRNAs) that were also abnormally expressed in OV cancer and had associations with GDF15 expression. Transcription factor CEBPB was predicted as an important regulator of GDF15, confirmed by luciferase reporter assay. However, CEBPB expression was not significantly changed in OV cancer. Data from TCGA database showed that lncRNA GAS5 is downregulated in OV cancer and its expression is negatively correlated with GDF15 expression. RPISeq showed high affinity of GAS5 to CEBPB and this was confirmed by RNA-binding protein immunoprecipitation assay. GAS5 overexpression increased its binding to CEBPB and consequently downregulated GDF15. GAS5 overexpression and GDF15 knockdown decreased viability and increased apoptosis of OV cancer cells, but CEBPB overexpression had opposite effects. However, simultaneous GAS5 and CEBPB overexpression or CEBPB overexpression together with GDF15 knockdown had no effect on cell viability and apoptosis. Conclusion: GAS5 functions as decoy of CEBPB, blocking transcription-promoting effect of CEBPB on GDF15.

LncRNA GAS5-mediated miR-1323 promotes tumor progression by targeting TP53INP1 in hepatocellular carcinoma

Background: MiR-1323 was identified in 2006. Until now, the roles and mechanisms of miR-1323 in the progression of cancers including hepatocellular carcinoma (HCC) remain unknown. The aim of this study was to investigate the expressions, roles and mechanisms of miR-1323 in HCC development.

Methods: QRT-PCR was used to evaluate the expressions of miR-1323, GAS5 and TP53INP1 in HCC tissues and cell lines. CCK-8 assay, transwell invasion assay and flow cytometry assay were conducted to evaluate the proliferation, invasion and apoptosis of HCC cells. Luciferase assay was used to identify microRNA-target interaction.

Results: Firstly, our results showed that miR-1323 promoted proliferation and invasion, and inhibited apoptosis of HCC cells. Secondly, we found that TP53INP1 was a direct target of miR-1323 and could reverse the effects of miR-1323 on proliferation, invasion and apoptosis of HCC cells. Thirdly, our results showed that long non-coding RNA (lncRNA) GAS5 and miR-1323 could interact with each other and affect biological processes of HCC cells. Furthermore, we identified the negative correlations between miR-1323 and TP53INP1, and between miR-1323 and GAS5 in tumor tissues of patients with HCC.

Conclusion: Taken together, our study revealed the important roles of GAS5/miR-1323/TP53INP1 axis in HCC progression. This study also provided promising strategies for targeted therapy of patients with HCC.

Growth arrest specific transcript 5 in tumorigenesis process: An update on the expression pattern and genomic variants

Growth arrest-specific 5 (GAS5) is a long non-coding RNA (lncRNA) with diverse functions in regulation of gene expression. Most studies have reported a role for this lncRNA in induction of cell apoptosis and suppression of tumorigenesis process. Although few studies demonstrated up-regulation of this lncRNA in tumor tissues compared to non-tumor tissues of the same origin, the results of in vitro functional studies mostly support the tumor suppressor role for GAS5. A number of recent studies have also shown associations between genomic variants of this gene and risk of cancer in some populations. The role of this lncRNA in modulation of response to anti-cancer regimens has been verified through both in vitro and clinical studies. Taken together, this lncRNA is a putative biomarker and therapeutic target in human malignancies.