Up-regulation of long non-coding RNA SNHG20 promotes ovarian cancer progression via Wnt/β-catenin signaling

Pancancer analysis of the interactions between CTNNB1 and infiltrating immune cell populations

Recently, evidence has indicated that CTNNB1 is important in a variety of malignancies. However, how CTNNB1 interacts with immune cell infiltration remains to be further investigated. In this study, we focused on the correlations between CTNNB1 and tumorigenesis, tumor progression, mutation, phosphorylation, and prognosis via gene expression profiling interaction analysis; TIMER 2.0, cBioPortal, GTEx, CPTAC, and GEPIA2 database analyses; and R software. CTNNB1 mutations are most found in uterine endometrioid carcinoma and hepatocellular carcinoma. However, no CTNNB1 mutations were found to be associated with a poor prognosis. In addition, CTNNB1 DNA methylation levels were higher in normal tissues than in tumor tissues in cancer except for breast invasive carcinoma, which had higher methylation levels in tumor tissues. The phosphorylation level of the S675 and S191 sites of CTNNB1 was greater in the primary tumor tissues in the clear cell renal cell carcinoma, liver hepatocellular carcinoma, lung adenocarcinoma, pancreatic adenocarcinoma, and breast cancer datasets but not in the glioblastoma multiform dataset. As for, with respect to immune infiltration, CD8 + T-cell infiltration was negatively correlated with the expression of CTNNB1 in thymoma and uterine corpus endometrial carcinoma. The CTNNB1 level was found to be positively associated with the infiltration index of the corresponding fibroblasts in the TCGA tumors of colon adenocarcinoma, human papillomavirus-negative head and neck squamous cell carcinoma, mesothelioma, testicular germ cell tumor, and thymoma. We also identified the top CTNNB1-correlated genes in the TCGA projects and analyzed the expression correlation between CTNNB1 and selected target genes, including PPP4R2, RHOA, and SPRED1. Additionally, pathway enrichment suggested that NUMB is involved in the Wnt pathway. This study highlights the predictive role of CTNNB1 across cancers, suggesting that CTNNB1 might serve as a potential biomarker for the diagnosis and prognosis evaluation of various malignant tumors.

C-MYC-activated lncRNA SNHG20 accelerates the proliferation of diffuse large B cell lymphoma via USP14-mediated deubiquitination of β-catenin

BACKGROUND

Long noncoding RNAs (lncRNAs) are implicated in the initiation and progression of diffuse large B-cell lymphoma (DLBCL). Small nucleolar RNA host gene 20 (SNHG20) has been recognized as a critical lncRNA in multiple human cancers. However, the role of SNHG20 and its underlying mechanism in DLBCL are still unclear.

METHODS

The expression levels of SNHG20, c-MYC, β-catenin, and ubiquitin-specific peptidase 14 (USP14) were measured by reverse transcription-quantitative polymerase chain reaction (RT‒qPCR) and immunoblotting. Cell Counting Kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EdU) incorporation, and flow cytometry assays were used to assess the proliferation and apoptosis of DLBCL cells. The transcriptional regulation of SNHG20 by c-MYC was confirmed by a luciferase reporter assay and RNA immunoprecipitation. The interaction between USP14 and β-catenin was demonstrated using coimmunoprecipitation. A subcutaneous xenograft model was constructed to determine the role of SNHG20 in vivo.

RESULTS

In the present study, we found that SNHG20 expression was upregulated in DLBCL cell lines and tissues compared to their normal counterparts. SNHG20 knockdown prominently reduced the proliferation and induced the apoptosis of U2932 and OCI-LY3 cells. However, SNHG20 overexpression increased the proliferation and apoptosis resistance of DLBCL cells. Mechanistically, the expression of SNHG20 was positively regulated by c-MYC in DLBCL cells. C-MYC directly bound to the promoter of SNHG20 to activate its transcription. SNHG20 was expressed mainly in the cytosol in DLBCL cells. SNHG20 silencing did not impact USP14 expression but markedly decreased the level of β-catenin, the substrate of USP14, in DLBCL cells. USP14 overexpression increased the β-catenin level, and this increase was attenuated by SNHG20 knockdown. Treatment with the proteasome inhibitor MG132 abolished SNHG20 knockdown-induced β-catenin downregulation. Moreover, SNHG20 silencing reduced the half-life but increased the ubiquitination of β-catenin in DLBCL cells. SNHG20 knockdown weakened the interaction between both endogenous and exogenous USP14 and β-catenin. In turn, SNHG20 overexpression increased the c-MYC level, and this increase was attenuated by β-catenin knockdown. Importantly, β-catenin knockdown attenuated the SNHG20-mediated increase in DLBCL cell proliferation in vitro and tumour growth in vivo.

CONCLUSIONS

Taken together, our results suggested that c-MYC-activated SNHG20 accelerated the proliferation and increased the apoptosis resistance of DLBCL cells via USP14-mediated deubiquitination of β-catenin. The c-MYC/SNHG20 positive feedback loop may be a new target for anti-DLBCL treatment.

Long Non-Coding RNAs as Novel Targets for Phytochemicals to Cease Cancer Metastasis

Metastasis is a multi-step phenomenon during cancer development leading to the propagation of cancer cells to distant organ(s). According to estimations, metastasis results in over 90% of cancer-associated death around the globe. Long non-coding RNAs (LncRNAs) are a group of regulatory RNA molecules more than 200 base pairs in length. The main regulatory activity of these molecules is the modulation of gene expression. They have been reported to affect different stages of cancer development including proliferation, apoptosis, migration, invasion, and metastasis. An increasing number of medical data reports indicate the probable function of LncRNAs in the metastatic spread of different cancers. Phytochemical compounds, as the bioactive agents of plants, show several health benefits with a variety of biological activities. Several phytochemicals have been demonstrated to target LncRNAs to defeat cancer. This review article briefly describes the metastasis steps, summarizes data on some well-established LncRNAs with a role in metastasis, and identifies the phytochemicals with an ability to suppress cancer metastasis by targeting LncRNAs.

Cancer Stem Cells in Ovarian Cancer-A Source of Tumor Success and a Challenging Target for Novel Therapies

Ovarian cancer is the most lethal neoplasm of the female genital organs. Despite indisputable progress in the treatment of ovarian cancer, the problems of chemo-resistance and recurrent disease are the main obstacles for successful therapy. One of the main reasons for this is the presence of a specific cell population of cancer stem cells. The aim of this review is to show the most contemporary knowledge concerning the biology of ovarian cancer stem cells (OCSCs) and their impact on chemo-resistance and prognosis in ovarian cancer patients, as well as to present the treatment options targeted exclusively on the OCSCs. The review presents data concerning the role of cancer stem cells in general and then concentrates on OCSCs. The surface and intracellular OCSCs markers and their meaning both for cancer biology and clinical prognosis, signaling pathways specifically activated in OCSCs, the genetic and epigenetic regulation of OCSCs function including the recent studies on the non-coding RNA regulation, cooperation between OCSCs and the tumor microenvironment (ovarian cancer niche) including very specific environment such as ascites fluid, the role of shear stress, autophagy and metabolic changes for the function of OCSCs, and finally mechanisms of OCSCs escape from immune surveillance, are described and discussed extensively. The possibilities of anti-OCSCs therapy both in experimental settings and in clinical trials are presented, including the recent II phase clinical trials and immunotherapy. OCSCs are a unique population of cancer cells showing a great plasticity, self-renewal potential and resistance against anti-cancer treatment. They are responsible for the progression and recurrence of the tumor. Several completed and ongoing clinical trials have tested different anti-OCSCs drugs which, however, have shown unsatisfactory efficacy in most cases. We propose a novel approach to ovarian cancer diagnosis and therapy.

LncRNA SNHG20 promotes migration and invasion of ovarian cancer via modulating the microRNA-148a/ROCK1 axis

BACKGROUND

Ovarian cancer (OC) is characterized by early metastasis and poor prognosis, which threatens the health of women worldwide. Small nucleolar RNA host gene 20 (SNHG20), a long noncoding RNA (lncRNA), has been verified to be significantly up-regulated in several tumors, including OC. MicroRNA-148a (miR-148a)/rho-kinase1 (ROCK1) axis plays an important role in the modulation of tumor development. However, whether SNHG20 can regulate OC progression through miR-148a/ROCK1 axis remains unclear. Normal human ovarian epithelial cell line and four OC cell lines were adopted for in vitro experiments. Real-time PCR was performed to assess the levels of SNHG20 and miR-148a. OC cell proliferation, apoptosis, invasion and migration were detected using clone formation, flow cytometry, transwell, and wound healing assays, respectively. Tumor xenograft assay was applied to evaluate the effect of SNHG20 on tumor growth in vivo.

RESULTS

Significant higher expression of SNHG20 was observed in OC cell lines. SNHG20 markedly promoted the invasion, migration, proliferation and inhibited the apoptosis of OC cells. SNHG20 enhanced ROCK1 expression by sponging miR-148a, and the direct binding between SNHG20/ROCK1 and miR-148a was identified.

CONCLUSION

SNHG20 promoted invasion and migration of OC via targeting miR-148a/ROCK1 axis. The present research may provide a novel insight for the therapeutic strategies of OC.

STAT1-Induced Upregulation lncRNA LINC00958 Accelerates the Epithelial Ovarian Cancer Tumorigenesis by Regulating Wnt/β-Catenin Signaling

Background

Growing studies have demonstrated that long noncoding RNAs (lncRNAs) play important roles in tumor progression. In this study, we aimed to explore the potential roles of lncRNA LINC00958 (LINC00958) and its biological functions in epithelial ovarian cancer (EOC).

Methods

The expression of LINC00958 in 11 cases of EOC and adjacent nontumor specimens and five cell lines was detected by qRT-PCR. CCK-8, colony formation, and flow cytometry assays were conducted to study the cell viabilities of EOC cells. Wound scratch and transwell analyses were carried out for the examination of cell invasion and migration of EOC cells. The targeting associations between LINC00958 and STAT1 were demonstrated by ChIP analyses combined with luciferase reporter assays. The related proteins of Wnt/β-catenin signaling were determined using RT-PCR.

Results

Higher levels of LINC00958 were observed in EOC tissues and cell lines. Our data also revealed that high LINC00958 expression was partly induced by STAT1. Functionally, knockdown of LINC00958 suppressed the proliferation, migration, and invasion of EOC cells. Mechanistic investigation showed that the inhibitory effect of LINC00958 knockdown on EOC cells was mediated by the Wnt/β-catenin signaling.

Conclusion

Our findings suggested that STAT1-induced overexpression of LINC00958 promoted EOC progression by modulating Wnt/β-catenin signaling.

LncRNA SNHG20 promotes cell proliferation and invasion by suppressing miR-217 in ovarian cancer

Background

Ovarian cancer is the most common female gynecological malignancy. SNHG20, as a long non-coding RNA, has been proven to be an important regulator in the occurrence and development of various tumors. However, the potential mechanism of SNHG20 in ovarian cancer is unclear.

Objective

The present study was aimed to investigate the functions and mechanisms of SNHG20 in ovarian cancer.

Methods

The expression of SNHG20 and miR-217 in ovarian cancer tissues and cell lines was detected by qRT-PCR. CCK-8 assay was used to measure cell proliferation in transfected cells. The transwell assay was used to detect the relative invasion rate of transfected cells. The putative binding sites between SNHG20 and miR-217 were predicted by software LncBase v.2, and the interaction between SNHG20 and miR-217 was confirmed by dual-luciferase reporter assays and RIP assay. The rescue experiments were used to illustrate potential mechanisms.

Results

SNHG20 was upregulated in ovarian cancer tissues and cell lines. Overexpression of SNHG20 promoted ovarian cancer cell proliferation and invasion. MiR-217 was downregulated in ovarian cancer tissues and cells, and was negatively regulated by SNHG20. Moreover, miR-217 overexpression inhibited ovarian cancer cell proliferation and invasion. Furthermore, miR-217 mimic reversed the inhibitory effect of SNHG20 overexpression on the biological behavior of ovarian cancer cells.

Conclusions

SNHG20 promoted cell proliferation and invasion by sponging miR-217 in ovarian cancer. These results suggested that SNHG20 and miR-217 might provide new targets for therapeutic application in ovarian cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13258-021-01138-4.

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.

The LINC00922 aggravates ovarian cancer progression via sponging miR-361-3p

Background

Long noncoding RNA (lncRNA) LINC00922 has been reported to promote tumorigenesis of lung and breast cancer. However, the functions and mechanisms of LINC00922 in ovarian cancer (OC) remain unclarified. The current study aims to clarify the detailed functions and underlying mechanisms of LINC00922 in the progression of OC.

Methods

LINC00922 expression in OC tissues and cells was identified by a comprehensive strategy of data miming, computational biology and quantitative real-time polymerase chain reaction (RT-qPCR) experiment. In vitro CCK-8, wound healing, transwell invasion, western blotting and in vivo tumorigenesis assays LINC00922 were conducted to evaluate the functions of LINC00992. Subsequently, bioinformatics technology and dual luciferase reporter assay were performed to confirm the between miR-361-3p and LINC00922 or CLDN1. Finally, rescue experiments were performed to confirm whether LINC00922 effect functions of OC cells through regulation of miR-361-3p.

Results

LINC00922 was significantly upregulated in OC tissues and cell lines, which is significantly positively corelated with the poor prognosis of patients with OC. LINC00922 knockdown inhibited proliferation and tumorigenesis of OC cells in vitro and vivo. In addition, LINC00922 knockdown suppressed migration, invasion, and EMT of OC cells in vitro. Mechanically, LINC00922 could competitively bind with miR-361-3p to relieve the repressive effect of miR-361-3p on its target gene CLDN1 in OC cells. In addition, silencing miR-361-3p promoted OC cell proliferation, migration, invasion, EMT and Wnt/β-catenin signaling, while LINC00922 knockdown inhibited Wnt/β-catenin signaling by upregulating miR-361-3p. Rescue experiments revealed that LINC00922 knockdown inhibited OC cell proliferation, migration, invasion and EMT by regulating miR-361-3p.

Conclusion

This study suggested that LINC00922 could competitively bind with miR-361-3p to promote the CLDN1 expression and activate Wnt/β-catenin signaling in OC progression, which providing a promising therapeutically target for OC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00828-7.

Tumor Inhibitory Effect of Long Non-coding RNA LOC100505817 on Gastric Cancer

Gastric cancer (GC) is one of the major malignancies worldwide. Emerging evidence has revealed the potential involvement of long noncoding RNA (lncRNA) in human genetic disorders and cancer, but the role of LOC100505817 remains unknown. Thus, in this study, we isolated tissues from GC patients to characterize the functional importance of LOC100505817 in GC tumorigenesis. We also proposed a hypothesis that the regulation of Wnt/β-catenin pathway by LOC100505817 was regulated by miR-20a-mediated WT1. After the collection of cancer tissues and adjacent tissues were obtained from GC patients, expression of LOC100505817, Wnt/β-catenin pathway- and EMT-related genes was quantified. Ectopic expression and knockdown experiments were applied in order to investigate the protective role of LOC100505817 in the progression of GC. Subsequently, cell viability, flow cytometry for apoptosis and cell cycle were detected via CCK-8, while migration and invasion were determined using scratch test and Transwell assay respectively. Then interactions among LOC100505817, miR-20a and WT1 were explored by dual luciferase reporter gene assay, RNA pull down assay and RNA binding protein immunoprecipitation (RIP) assay. The results found poor expression LOC100505817 was poorly expressed in GC cells and tissues. Overexpressed LOC100505817 resulted in the significant reduction of cell proliferation, migration and invasion as well as the expression of Wnt2b, β-catenin, CyclinD1, N-cadherin, Vimentin and snail, while increased cell apoptosis along with the expression of E-cadherin. Wnt/β-catenin pathway and EMT in GC cells were suppressed by LOC100505817 through miR-20a-inhibted WT1. In summary, our results provided evidence suggesting that LOC100505817 inhibits GC through LOC100505817-mediated inhibition of Wnt/β-catenin pathway, that leads to the overall restraining of GC cell proliferation, migration and invasion through miR-20a-reduced WT1.

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.

Long non-coding RNA SNHG1 stimulates ovarian cancer progression by modulating expression of miR-454 and ZEB1

Ovarian cancer (OC) is highly prevalent and is associated with high mortality rates due to metastasis and relapse. In this study, we assessed the role of long non‐coding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) in OC to gain further insight into mechanisms that contribute to its aggressiveness. We analyzed the correlation between SNHG1, miR‐454 and zinc finger E‐box‐binding homeobox 1 (ZEB1) using a dual‐luciferase reporter assay. Alterations in cell metastasis and invasiveness were observed using wound‐healing and Transwell invasion assays, respectively. Tumor xenografts allowed us to monitor liver metastasis of mice injected with A2780 cells. We found that SNHG1 is overexpressed in OC. Downregulation of SNHG1 promoted miR‐454 expression and reduced ZEB1 levels. In addition, knockdown of SNHG1, also reduced the aggressiveness of A2780 and SK‐OV3 cells. Furthermore, SNHG1 downregulation by siRNA hindered cell migration and invasion; however, this effect was reversed by co‐transfection of miR‐454 into A2780 and SK‐OV3 cells. Moreover, SNHG1 increased ZEB1 expression by downregulating miR‐454 and activated Akt signaling, thereby promoting epithelial‐mesenchymal transition and enhancing the invasiveness of OC cells. Tumor xenograft analyses confirmed that SNHG1 affects OC proliferation and metastasis in vivo. In summary, our data demonstrate that SNHG1 plays crucial roles in tumor progression and may be a useful maker for OC prognosis.

Long non-coding RNA SNHG25 promotes epithelial ovarian cancer progression by up-regulating COMP

Long non-coding RNAs (lncRNAs) play a pivotal role in the genesis and development of cancer. The role and molecular mechanisms of SNHG25 in epithelial ovarian cancer (EOC) have not been investigated. In the present study, we showed that SNHG25 expression was up-regulated in EOC tissues relative to normal ovarian tissues. In vitro, functional experiments demonstrated that high expression of SNHG25 promoted proliferation, migration and invasion, and decreased apoptosis, in ovarian cancer cell lines. In vivo, downregulation of SNHG25 inhibited the growth (tumor volume) of subcutaneous xenografts in nude mice. High-throughput sequencing and western blot analysis showed a significant decrease in the expression of COMP mRNA and protein in SNHG25 knockdown compared to control ovarian cancer cells. These data suggest that SNHG25 promotes EOC progression by regulating COMP, serving as a potential biomarker for EOC.

Long non-coding RNA SNHG20 promotes ovarian cancer development by targeting microRNA-338-3p to regulate MCL1 expression

Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs/miRs) were reported to be associated with the development of ovarian cancer (OC). Increasing evidence demonstrated that lncRNA SNHG20 and miR-338-3p were involved in OC. However, the functional mechanism of lncRNA SNHG20 and miR-338-3p in OC development remains unknown. The expression of SNHG20, miR-338-3p and myeloid cell leukemia 1 (MCL1) was detected by reverse transcription-quantitative PCR. MTT assay, flow cytometry and transwell migration and invasion assays were used to assess cell proliferation, apoptosis, migration and invasion, respectively. The relative protein expression was detected by western blot analysis. The interaction between miR-338-3p and SNHG20 or MCL1 was predicted by starBase v3.0, and subsequently confirmed by dual-luciferase reporter assay. Besides, mouse xenograft assay was carried out to explore the effect of SNHG20 on tumor growth in vivo. The levels of SNHG20 and MCL1 were upregulated, while miR-338-3p level was downregulated in OC tissues and cells. SNHG20 knockdown repressed OC cell proliferation, migration, invasion and epithelial-mesenchymal transition, and induced apoptosis. Interestingly, SNHG20 targeted miR-338-3p to regulate MCL1 expression. miR-338-3p depletion or MCL1 overexpression could reverse the effects of SNHG20 knockdown on OC cells. Besides, SNHG20 knockdown impeded tumor growth in vivo. In conclusion, the present study demonstrated that SNHG20 regulates OC development via modulation of the miR-338-3p/MCL1 axis, providing the theoretical basis for the treatment of OC.

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 RNAs As Epigenetic Regulators in Cancer

Long noncoding RNAs (lncRNAs) constitute large portions of the mammalian transcriptome which appeared as a fundamental player, regulating various cellular mechanisms. LncRNAs do not encode proteins, have mRNA-like transcripts and frequently processed similar to the mRNAs. Many investigations have determined that lncRNAs interact with DNA, RNA molecules or proteins and play a significant regulatory function in several biological processes, such as genomic imprinting, epigenetic regulation, cell cycle regulation, apoptosis, and differentiation. LncRNAs can modulate gene expression on three levels: chromatin remodeling, transcription, and post-transcriptional processing. The majority of the identified lncRNAs seem to be transcribed by the RNA polymerase II. Recent evidence has illustrated that dysregulation of lncRNAs can lead to many human diseases, in particular, cancer. The aberrant expression of lncRNAs in malignancies contributes to the dysregulation of proliferation and differentiation process. Consequently, lncRNAs can be useful to the diagnosis, treatment, and prognosis, and have been characterized as potential cancer markers as well. In this review, we highlighted the role and molecular mechanisms of lncRNAs and their correlation with some of the cancers.

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.

An Emerging Class of Long Non-coding RNA With Oncogenic Role Arises From the snoRNA Host Genes

The small nucleolar RNA host genes (SNHGs) are a group of long non-coding RNAs, which are reported in many studies as being overexpressed in various cancers. With very few exceptions, the SNHGs (SNHG1, SNHG3, SNHG5, SNHG6, SNHG7, SNHG12, SNHG15, SNHG16, SNHG20) are recognized as inducing increased proliferation, cell cycle progression, invasion, and metastasis of cancer cells, which makes this class of transcripts a viable biomarker for cancer development and aggressiveness. Through our literature research, we also found that silencing of SNHGs through small interfering RNAs or short hairpin RNAs is very effective in both in vitro and in vivo experiments by lowering the aggressiveness of solid cancers. The knockdown of SNHG as a new cancer therapeutic option should be investigated more in the future.

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.

Wnt Signaling in Ovarian Cancer Stemness, EMT, and Therapy Resistance

Ovarian cancers represent the deadliest among gynecologic malignancies and are characterized by a hierarchical structure with cancer stem cells (CSCs) endowed with self-renewal and the capacity to differentiate. The Wnt/β-catenin signaling pathway, known to regulate stemness in a broad spectrum of stem cell niches including the ovary, is thought to play an important role in ovarian cancer. Importantly, Wnt activity was shown to correlate with grade, epithelial to mesenchymal transition, chemotherapy resistance, and poor prognosis in ovarian cancer. This review will discuss the current knowledge of the role of Wnt signaling in ovarian cancer stemness, epithelial to mesenchymal transition (EMT), and therapy resistance. In addition, the alleged role of exosomes in the paracrine activation of Wnt signaling and pre-metastatic niche formation will be reviewed. Finally, novel potential treatment options based on Wnt inhibition will be highlighted.

SNHG20: A vital lncRNA in multiple human cancers

Long noncoding RNAs (lncRNAs) act as an initial factor and promoter in different tumors as a kind of ncRNAs. The length of them is >200 nucleotides opposite small ncRNAs. Increasing researches have proved that dysregulation lncRNA has been implicated in tumorigenesis. Small nucleolar RNA host gene 20 (SNHG20), a member of lncRNAs, expresses frequently in cancer types, such as hepatocellular carcinoma, ovarian cancer, colorectal cancer, and bladder cancer, contributing to cancer development and progression by transcriptional or posttranscriptional modifications. Not only does this review show the recent published literature concerning the biological functions but also demonstrates molecular mechanisms of SNHG20 among above multiple malignancies and others.

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.

LncRNA SNHG20 predicts a poor prognosis and promotes cell progression in epithelial ovarian cancer

The long noncoding RNA small nucleolar RNA host gene 20 (SNHG20) has been demonstrated to play a crucial role in cancer progression. However, the functions of SNHG20 in epithelial ovarian cancer (EOC) are not well established. The aim of the present study was to investigate SNHG20 clinical significance and its underlying mechanism in proliferation and metastasis in EOC. The expression level of SNHG20 was identified via in situ hybridization (ISH) and quantitative RT-PCR (qRT-PCR). The proliferative and metastatic capacities by silencing SNHG20 expression in A2780 and CAOV-3 cells were measured by cell counting kit-8 (CCK-8) and transwell assays. The molecular mRNA and protein expressions were examined using qRT-PCR, Western blot, and double immunofluorescent staining. SNHG20 expression was markedly higher in serous EOC tissues than that in adjacent tissues and closely correlated with histological grade and lymph node (LN) status. Patients with high SNHG20 showed a shorter overall survival (OS) and SNHG20 was an independent risk factor for the prognosis of serous EOC. Knockdown of SNHG20 remarkably inhibited EOC cell proliferation, migration, and invasion, which was associated with dysregulation of P21, Cyclin D1, E-cadherin, and Vimentin. These results suggest that SNHG20 may serve as an independent prognostic predictor and function as a noncoding oncogene in EOC progression, which might be a possible novel diagnostic marker and treatment target.

SNHG20 knockdown suppresses proliferation, migration and invasion, and promotes apoptosis in non-small cell lung cancer through acting as a miR-154 sponge

Long noncoding RNAs (LncRNAs) play critical roles in the development and progression of cancers. However, little is known about the function and mechanism of lncRNAs in non-small cell lung cancer (NSCLC). In this study, we investigated the expression and functional role of lncRNA small nucleolar RNA host gene 20 (SNHG20) as well as its underlying mechanism in NSCLC. Our results showed that SNHG20 was significantly up-regulated in NSCLC tissues and cells. High SNHG20 expression was implicated with poor prognosis in NSCLC patients. Moreover, SNHG20 knockdown suppressed proliferation, migration and invasion, and induced apoptosis in NSCLC cells. Furthermore, SNHG20 could function as a competing endogenous RNA (ceRNA) to elevate ZEB2 and RUNX2 expression by sponging miR-154. Rescue assays revealed that miR-154 inhibition could reverse the inhibitory effect of SNHG20 silence on proliferation, migration and invasion in NSCLC cells. More importantly, SNHG20 knockdown suppressed tumor growth in NSCLC in vivo through suppressing miR-154 and elevating ZEB2 and RUNX2 expression. In summary, knockdown of lncRNA SNHG20 suppressed proliferation, migration and invasion, and promotes apoptosis through up-regulating ZEB2 and RUNX2 expression by sponging miR-154 in NSCLC, providing a promising therapeutic target for NSCLC patients.

ZRANB2/SNHG20/FOXK1 Axis regulates Vasculogenic mimicry formation in glioma

Background

Glioma is the most common intracranial neoplasm with vasculogenic mimicry formation as one form of blood supply. Many RNA-binding proteins and long non-coding RNAs are involved in tumorigenesis of glioma.

Methods

The expression of ZRANB2, SNHG20 and FOXK1 in glioma were detected by real-time PCR or western blot. The function of ZRANB2/SNHG20/FOXK1 axis in glioma associated with vasculogenic mimicry formation was analyzed.

Results

ZRANB2 is up-regulated in glioma tissues and glioma cells. ZRANB2 knockdown inhibits the proliferation, migration, invasion and vasculogenic mimicry formation of glioma cells. ZRANB2 binds to SNHG20 and increases its stability. Knockdown of SNHG20 reduces the degradation of FOXK1 mRNA by SMD pathway. FOXK1 inhibits transcription by binding to the promoters of MMP1, MMP9 and VE-Cadherin and inhibits vasculogenic mimicry formation of glioma cells.

Conclusions

ZRANB2/SNHG20/FOXK1 axis plays an important role in regulating vasculogenic mimicry formation of glioma, which might provide new targets of glioma therapy.

Electronic supplementary material

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lncRNA small nucleolar RNA host gene 20 predicts poor prognosis in glioma and promotes cell proliferation by silencing P21

Background

In multiple cancers, long non-coding RNA small nucleolar RNA host gene 20 (lncRNA SNHG20) is generally dysregulated. In the present study, both the biological role and clinicopathological value of lncRNA SNHG20 in glioma are explored.

Methods

Real-time PCR was employed to determine lncRNA SNHG20 expression in glioma patients. The prognostic role of expression of lncRNA SNHG20 was evaluated in a retrospective cohort study. In addition, the association between lncRNA SNHG20 expression and the clinicopathological features of glioma patients, such as tumor recurrence, survival status, follow-up time, WHO grade, resection extent, tumor location, Karnofsky performance scale score, cystic change, tumor size, gender and age, was discussed. By constructing and transfecting siRNAs that targeted lncRNA SNHG20 into the glioma U87 cells, the effects of lncRNA SNHG20 on the proliferation and cell cycle of U87 cells were assessed through cell counting kit-8, colony formation and cell cycle assays, respectively. In addition, Western blot and real-time PCR measured the expression levels of P21 and CCNA1 in U87 cells after being transfected with SNHG20 siRNA.

Results

Our results suggested the high expression of lncRNA SNHG20 in human glioma tissues compared with normal brain tissues, which was related to recurrence-free survival and poor overall survival in glioma patients. According to the existing retrospective cohort study, high lncRNA SNHG20 expression was associated with tumor size, extent of resection, WHO grade, follow-up time, survival status and recurrence. Besides, knocking down the expression of lncRNA SNHG20 could inhibit the proliferation and colony formation abilities of glioma U87 cells through cell cycle arrest. Consequently, the expression of CCNA1 was inhibited, and the expression of P21 was up-regulated in U87 cells.

Conclusion

A high lncRNA SNHG20 expression level predicts the poor prognosis for glioma patients. Moreover, lncRNA SNHG20 can promote glioma proliferation through silencing P21 and thus lncRNA SNHG20 is an independent potential prognostic biomarker for glioma patients.

The roles of Wnt/β-catenin signaling pathway related lncRNAs in cancer

Long noncoding RNAs (lncRNAs), with length of more than 200 nucleotides, are not translated into proteins but involved in multiple diverse diseases, especially tumorigenesis. The dysregulation of lncRNAs greatly contributes to the progression of various tumors through specific signaling pathways, including Wnt/β-catenin signaling pathway, which is associated with malignant features of tumors. The interactions between lncRNAs, which have specific expression characteristics in diverse cancer tissues, and Wnt/β-catenin signaling pathway, exhibit potential as novel biomarkers and therapeutic targets. In this review, we aim to present research findings on the roles of Wnt pathway-related lncRNAs and their effects on Wnt/β-catenin signaling to regulate tumorigenesis in different cancer types. Results may be used as basis to develop or improve strategies for treatment of different carcinomas.

Role of lncRNA and EZH2 Interaction/Regulatory Network in Lung Cancer

Lung cancer is the leading cause of cancer-related deaths worldwide. Long non-coding RNAs (lncRNAs) are non-protein-coding transcripts and longer than 200 nucleotides. LncRNAs have been demonstrated to modulate gene expression at transcriptional, post-transcriptional, as well as epigenetic levels in lung cancer. Interestingly, compelling studies have revealed that lncRNAs participated in the EZH2 oncogenic regulatory network. EZH2 plays an important role in the initiation, progression and metastasis of cancer. On one hand, lncRNAs can directly bind to EZH2, recruit EZH2 to the promoter region of genes and repress their expression. On the other hand, lncRNAs can also serve as EZH2 effectors or regulators. In this review, we summarized the types of lncRNA-EZH2 interaction and regulatory network identified till date and discussed their influence on lung cancer. Better understanding regarding the interaction and regulatory network will provide new insights on lncRNA- or EZH2-based therapeutic development in lung cancer.

LncRNA CRNDE promotes hepatocellular carcinoma cell proliferation, invasion, and migration through regulating miR-203/ BCAT1 axis

OBJECTIVE

To investigate the impact of long noncodingRNA (lncRNA) colorectal neoplasia differentially expressed (CRNDE) on hepatocellular cancer (HCC) cell propagation, invasion, and migration by mediating miR-203/ BCAT1 axis.

METHODS

Microarray analysis was based on 25 pairs of HCC cancerous tissues and adjacent tissues. The expression levels of CRNDE, miR-203, and BCAT1 in HCC tissues were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The liver cell line L-02 and HCC cell lines HepG2 and Huh-7 were utilized to assess the regulatory effects of CRNDE and miR-203 on HCC progression in vitro. Western blot was used to qualify BCAT1 protein expression level. Cell proliferation and apoptosis were evaluated using CCK-8 and flow cytometry analysis, whereas cell invasion and migration assay were performed by the Transwell assay. The relationship among CRNDE, miR-203, and BCAT1 was validated by dual luciferase assay. Tumor Xenograft study was established to verify the pathological effect of CRNDE on HCC development in vivo.

RESULTS

The expression levels of the CRNDE and BCAT1 were upregulated in HCC tissues and cells, whereas miR-203 was downregulated in HCC. Knockdown of CRNDE or miR-203 overexpression would inhibit HCC cell propagation and metastasis, and induced cell apoptosis. Moreover, miR-203 was negatively correlated with CRNDE, the same as miR-203 with BCAT1. Dual luciferase assay showed that miR-203 was an inhibitory target of CRNDE, and BCAT1 was directly targeted by miR-203 as well.

CONCLUSION

LncRNA CRNDE could enhance HCC tumorgenesis by sponging miR-203 and mediating BCAT1. LncRNA CRNDE might facilitate HCC cell propagation, invasiveness, and migration through regulating miR-203/ BCAT1 axis.

Long non-coding RNA SNHG20 promotes bladder cancer via activating the Wnt/β-catenin signalling pathway

The long non‑coding RNA, small nucleolar RNA host gene 20 (SNHG20), is involved in promoting several common types of human cancer, however, the exact function of SNHG20 in the pathogenesis of bladder cancer remains to be elucidated. The present study aimed to examine the regulatory mechanism of SNHG20 underlying the malignant progression of bladder cancer. Reverse transcription‑quantitative polymerase chain reaction and western blotting were used to examine mRNA and protein expression. Cell survival, proliferation, apoptosis, colony formation, migration and invasion were also studied. The resulting data indicated that SNHG20 was significantly upregulated in bladder cancer tissues and cell lines, compared with its expression in adjacent non‑tumour tissues and the SV‑HUC‑1 normal urinary tract epithelial cell line, respectively. In addition, the high expression of SNHG20 was associated with advanced clinical stage, lymph node metastasis, and reduced patient survival rate. The knockdown of SNHG20 caused a significant reduction in cancer cell survival, proliferation, colony formation, migration and invasion, and induced cell apoptosis. Additionally, the inhibition of SNHG20 reduced tumour growth in vivo. Investigations into the mechanism revealed that the inhibition of SNHG20 suppressed the activation of Wnt/β‑catenin signalling and the expression of certain key genes in bladder cancer cells. Taken together, these results indicated that SNHG20 is involved in promoting bladder cancer and may be used as a potential therapeutic target for the treatment of this disease.