Upregulated expression of long noncoding RNA SNHG15 promotes cell proliferation and invasion through regulates MMP2/MMP9 in patients with GC. Tumour Biol. 2016;37:6801-6812. [PMID: 26662309 DOI: 10.1007/s13277-015-4404-0]

Diagnostic Accuracy of Exosomal Long Noncoding RNAs in Diagnosis of NSCLC: A Meta-Analysis

PURPOSE

Globally, non-small cell lung cancer (NSCLC) is the primary cause of cancer-related mortality, both early and accurate diagnosis are essential for effective treatment and improved patient outcomes. Exosomal noncoding RNAs (ncRNAs) have emerged as promising biomarkers for NSCLC diagnosis. This meta-analysis aims to assess the diagnostic accuracy of exosomal long noncoding RNAs (lncRNAs) for diagnosing NSCLC.

METHODS

A comprehensive literature search was conducted to identify relevant studies that assessed the diagnostic performance of exosomal lncRNAs in NSCLC. Quality assessment and data extraction were performed independently by two reviewers. Pooled sensitivity, specificity, and other relevant diagnostic parameters were calculated using a bivariate random-effects model. Subgroup analyses and meta-regression were conducted to explore potential sources of heterogeneity.

RESULTS

Sixteen studies, comprising 1843 NSCLC cases and 1298 controls, were included in this meta-analysis. The pooled sensitivity and specificity of nine exosomal lncRNAs for diagnosing NSCLC were 0.74 [95% confidence interval (CI) 0.69-0.79] and 0.78 (95% CI 0.68-0.85). The pooled area under the receiver operating characteristic curve (AUC) for fifteen lncRNAs was 0.80 (95% CI 0.768-0.831). Meta-regression could not find any source for interstudy heterogeneity.

CONCLUSION

Exosomal lncRNAs, particularly AL139294.1, GAS5, LUCAT1, and SOX2-OT, have excellent diagnostic accuracy and promising diagnostic potential in NSCLC. Therefore, they can be used as diagnostic tools for early detection of NSCLC.

Non-Coding RNA as Biomarkers and Their Role in the Pathogenesis of Gastric Cancer-A Narrative Review

Non-coding RNAs (ncRNAs) represent a broad family of molecules that regulate gene expression, including microRNAs, long non-coding RNAs and circular RNAs, amongst others. Dysregulated expression of ncRNAs alters gene expression, which is implicated in the pathogenesis of several malignancies and inflammatory diseases. Gastric cancer is the fifth most frequently diagnosed cancer and the fourth most common cause of cancer-related death. Studies have found that altered expression of ncRNAs may contribute to tumourigenesis through regulating proliferation, apoptosis, drug resistance and metastasis. This review describes the potential use of ncRNAs as diagnostic and prognostic biomarkers. Moreover, we discuss the involvement of ncRNAs in the pathogenesis of gastric cancer, including their interactions with the members of major signalling pathways.

Functional role of lncRNAs in gastrointestinal malignancies: the peculiar case of small nucleolar RNA host gene family

Long noncoding RNAs (lncRNAs) play crucial roles in normal physiology and are often de-regulated in disease states such as cancer. Recently, a class of lncRNAs referred to as the small nucleolar RNA host gene (SNHG) family have emerged as important players in tumourigenesis. Here, we discuss new findings describing the role of SNHGs in gastrointestinal tumours and summarize the three main functions by which these lncRNAs promote carcinogenesis, namely: competing with endogenous RNAs, modulating protein function, and regulating epigenetic marking. Furthermore, we discuss how SNHGs participate in different hallmarks of cancer, and how this class of lncRNAs may serve as potential biomarkers in cancer diagnosis and therapy.

Nephroblastoma-specific dysregulated gene SNHG15 with prognostic significance: scRNA-Seq with bulk RNA-Seq data and experimental validation

Wilms tumor (WT) is the most common malignancy of the genitourinary system in children. Currently, the Integration of single-cell RNA sequencing (scRNA-Seq) and Bulk RNA sequencing (RNA-Seq) analysis of heterogeneity between different cell types in pediatric WT tissues could more accurately find prognostic markers, but this is lacking. RNA-Seq and clinical data related to WT were downloaded from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database. Small nucleolar RNA host gene 15 (SNHG15) was identified as a risk signature from the TARGET dataset by using weighted gene co-expression network analysis, differentially expressed analysis and univariate Cox analysis. After that, the functional mechanisms, immunological and molecular characterization of SNHG15 were investigated at the scRNA-seq, pan-cancer, and RNA-seq levels using Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), ESTIMATE, and CIBERSORT. Based on scRNA-seq data, we identified 20 clusters in WT and annotated 10 cell types. Integration of single-cell and spatial data mapped ligand-receptor networks to specific cell types, revealing M2 macrophages as hubs for intercellular communication. In addition, in vitro cellular experiments showed that siRNAs interfering with SNHG15 significantly inhibited the proliferation and migration of G401 cells and promoted the apoptosis of G401 cells compared with the control group. The effect of siRNAs interfering with SNHG15 on EMT-related protein expression was verified by Western blotting assay. Thus, our findings will improve our current understanding of the pathogenesis of WT, and they are potentially valuable in providing novel prognosis markers for the treatment of WT.

Diagnostic value of long noncoding RNA SNHG15 in gastric cancer: in vitro and in silico studies

LncRNA SNHG15 has been recognized as the main factor in the progression of various cancer types. However, the underlying mechanisms are not well clarified. This research aimed to explore the diagnostic potential of SNHG15 in gastric cancer (GC) patients and also the effects of SNHG15-miRNA-mRNA network in GC pathobiology. The expression level of SNHG15 in GC tissues and adjacent normal tissues (ANTs) was evaluated by qRT-PCR and also considered in relation to clinicopathologic factors. The ROC curve was explored to consider the specificity and sensitivity of SNHG15. Gene ontology functional annotation and KEGG pathway analysis were performed in order to predict the effects of SNHG15-miRNA-mRNA network in GC pathobiology. SNHG15 was overexpressed in GC tissues compared to ANTs (fold change= 3.87 and P-value = 0.0022). The SNHG15 expression level was not significantly associated with clinicopathologic factors. ROC curve indicated the specificity of 63.51 and sensitivity of 79.73 and the AUC of 0.744 (P-value < 0.0001). Further gene network analysis revealed that SNHG15 interacts with has-miR-613, has-miR-542-3p, and has-miR-1236-3p, and may be involved in the GC pathobiology by affecting the EGFR tyrosine kinase inhibitor resistance, HIF-1 signaling pathway, and VEGF signaling pathway. It can be concluded that SNHG15 may be a diagnostic factor in GC and may contribute in a variety of cancer-related signaling pathways.

Tumor-targeted delivery of SNHG15 siRNA using a ZIF-8 nanoplatform: Towards a more effective prostate cancer therapy

Small interfering RNAs (siRNAs) can be used as a powerful tool in gene therapy to downregulate the expression of specific disease related genes. Some properties however, such as instability, and low penetration into cells can limit their efficacy, and thus reduce their therapeutic potential. Metal-organic frameworks (MOFs) such as zeolitic imidazolate framework-8 (ZIF-8), which consist of organic bridging ligands and metal cations (Zn), have a very high binding affinity with nucleic acids including siRNAs. In this study, we designed a PEGylated ZIF-8 platform that was equipped with epithelial cell adhesion molecule (EpCAM) aptamer for the targeted delivery of siRNA molecules, in order to knockdown SNHG15 in both a prostate cancer (PC) cell line, and a human PC xenograft mouse model. SNHG15 is a long noncoding RNA, with oncogenic roles in different cancers including PC. The results indicated that the depletion of SNHG15 by Apt-PEG-siRNA@ZIF-8 nanoplatfrom inhibited cell proliferation and colony formation, and increased apoptosis in PC cells. This nanoparticle facilitated the release of siRNAs into the tumor environment in vivo, and subsequently reduced the tumor growth, with no side effects observed in vital organs. We have therefore developed a novel siRNA nano-delivery system for targeted prostate cancer treatment; however further studies are required before it can be tested in clinical trials.

A comprehensive insight into the role of small nucleolar RNAs (snoRNAs) and SNHGs in human cancers

Long non-coding RNAs (lncRNAs), which comprise most non-coding RNAs (ncRNAs), have recently become a focus of cancer research. How many functional ncRNAs exist is still a matter of debate. Although insufficient evidence supports that most lncRNAs function as transcriptional by-products, it is widely known that an increasing number of lncRNAs play essential roles in cells. Small nucleolar RNAs (snoRNAs), 60-300 nucleotides in length, have been better studied than long non-coding RNAs (lncRNAs) and are predominantly present in the nucleolus. Most snoRNAs are encoded in introns of protein- and non-protein-coding genes called small nucleolar RNA host genes (SNHGs). In this article, we explore the biology and characteristics of SNHGs and their role in developing human malignancies. In addition, we provide an update on the ability of these snoRNAs to serve as prognostic and diagnostic variables in various forms of cancer.

Long non-coding RNA SNHG15 regulates cardiomyocyte apoptosis after hypoxia/reperfusion injury via modulating miR-188-5p/PTEN axis

Nowadays the most effective way to cure myocardial infarction (MI) is reperfusion, which inevitably leads to cardiomyocyte apoptosis. In this study, we discussed the functions of SNHG15 in regulating cardiomyocyte apoptosis through the modulation of miR-188-5p/PTEN axis. We examined the links between SNHG15 and miR-188-5p/PTEN in mice with MI. Extensive experiments, measurements and comparisons were performed, including RT-PCR, western blotting, luciferase reporter assay, flow cytometry analysis etc. Through a series of comparisons and analysis, we discovered that SNHG15 could interact with the miR-188-5p/PTEN axis and impact the cellular physiology of cardiomyocyte apoptosis. PTEN was upregulated in hypoxia cells, but this effect was attenuated by miR-188-5p. MiR-188-5p could combine with SNHG15 and PTEN, and form a SNHG15-miR-188-5p-PTEN axis, which regulated the apoptosis of MCs. These results suggest that LncRNA SNHG15 regulates cardiomyocyte apoptosis induced by hypoxia or reperfusion injury through modulating of miR-188-5p/PTEN axis.

Long noncoding RNA SNHG15: A promising target in human cancers

As oncogenes or tumor suppressor genes, lncRNAs played an important role in tumorigenesis and the progression of human cancers. The lncRNA SNHG15 has recently been revealed to be dysregulated in malignant tumors, suggesting the aberrant expression of which contributes to clinical features and regulates various oncogenic processes. We have selected extensive literature focused on SNHG15 from electronic databases, including studies relevant to its clinical significance and the critical events in cancer-related processes such as cell proliferation, apoptosis, autophagy, metastasis, and drug resistance. This review summarized the current understanding of SNHG15 in cancer, mainly focusing on the pathological features, known biological functions, and underlying molecular mechanisms. Furthermore, SNHG15 has been well-documented to be an effective diagnostic and prognostic marker for tumors, offering novel therapeutic interventions in specific subsets of cancer cells.

Silencing the expression of lncRNA SNHG15 may be a novel therapeutic approach in human breast cancer through regulating miR-345-5p

BACKGROUND

Long noncoding RNA (lncRNA) short nucleolar RNA host gene 15 (SNHG15) has been found to have an oncogenic function in numerous malignancies. Nevertheless, the biological function and regulatory mechanisms of SNHG15 in breast cancer have not been fully elucidated.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of SNHG15 and in MDA-MB-231 breast cancer cells. The expression of SNHG15 was silenced using small interfering RNA (siRNA) technology. The proliferation and migration of the cells were examined by colony formation assays, cell counting kit 8 (CCK-8) assays, and transwell assays. For the zebrafish xenograft injection experiments, cultured cells labelled with the fluorescent dye CM-DiI were injected into the perivitelline space of the larvae.

RESULTS

This present study revealed that the expression of lncRNA SNHG15 (lnc-SNHG15) was significantly upregulated in breast cancer cells, and its overexpression was associated with the tumor. The relative expression of lnc-SNHG15 could be downregulated using siRNAs, and silencing lnc-SNHG15 inhibited the proliferation and the migration of MDA-MB-231 cells. In vivo experiments using the zebrafish xenograft model showed similar results. Mechanistically, the knockdown effect of lnc-SNHG15 could be restored by inhibiting the expression of the miR-345-5p, confirming the negative regulation between lnc-SNHG15 and miR-345-5p. Interestingly, cisplatin treatment combined with SNHG15 knockdown effectively inhibited MDA-MB-231 cell proliferation and migration in the zebrafish xenograft compared to negative controls.

CONCLUSIONS

In conclusion, lnc-SNHG15 knockdown increased miR-345-5p expression and negated cisplatin resistance in breast cancer cells, and thus, lnc-SNHG15 may be a potential novel target for breast cancer therapy.

The Role of SNHG15 in the Pathogenesis of Hepatocellular Carcinoma

Long non-coding RNAs (lncRNAs) are transcripts of more than 200 nucleotides which cannot be translated into proteins. Small nucleolar RNA host gene 15 (SNHG15) is a lncRNA whose dysregulation has been found to have an important impact on carcinogenesis and affect the prognosis of cancer patients in various cancer types. Hepatocellular carcinoma (HCC) is one of the most common cancers with a poor long-term prognosis, while the best prognostic factor of the disease is its early diagnosis and surgery. Consequently, the investigation of the mechanisms of hepatocarcinogenesis, as well as the discovery of efficient molecular markers and therapeutic targets are of great significance. An extensive literature search was performed in MEDLINE in order to identify clinical studies that tried to reveal the role of SNHG15 in HCC. We used keywords such as ‘HCC’, ‘hepatocellular carcinoma’, ‘SNHG15’ and ‘clinical study’. Finally, we included four studies written in English, published during the period 2016–2021. It was revealed that SNHG15 is related to the appearance of HCC via different routes and its over-expression affects the overall survival of the patients. More assays are required in order to clarify the potential role of SNHG15 as a prognostic tool and therapeutic target in HCC.

LncRNA SNHG15: A potential therapeutic target in the treatment of colorectal cancer

The global burden of colorectal cancer (CRC) is increasing annually. CRC could develop from genetic and phenotypic factors involving changes in gene expression. Incredibly, the human genome transcribes into non-coding RNAs, among which long non-coding RNAs (lncRNAs) signify the most crucial part of the transcriptome in multicellular organisms. lncRNAs affect gene expression at multiple levels, from transcription to protein localization and stability. Recent studies have implicated lncRNA small nucleolar RNA host gene 15 (SNHG15) in cancers occurrence and progression. Previously, an indication suggests SNHG15 overexpression triggers proliferation, metastasis, and impedes apoptosis in CRC. Further, through its activity of binding micro-RNAs, lncRNA SNHG15 modulates genes associated with CRC progression and promotes CRC resistance to chemotherapeutic drugs. Here we reviewed recent findings on the various mechanisms and roles of lncRNA SNHG15 implicated in CRC tumorigenesis. We further highlight how SNHG15 plays a vital role in regulating critical pathways linked to the development and progression of CRC. Finally, we highlight how SNHG15 can be modulated for CRC treatments and the various therapeutic strategies to be implored when targeting SNHG15 in the context of CRC treatments. Findings from these studies present SNHG15 as a potential therapeutic target for preventing and treating CRC.

lncRNA SNHG15 Induced by SOX12 Promotes the Tumorigenic Properties and Chemoresistance in Cervical Cancer via the miR-4735-3p/HIF1a Pathway

Cervical cancer (CC) is one of the most common malignancies in females, with high prevalence and mortality globally. Despite advances in diagnosis and therapeutic strategies developed in recent years, CC is still a major health burden worldwide. The molecular mechanisms underlying the development of CC need to be understood. In this study, we aimed to demonstrate the role of lncRNA SNHG15 in CC progression. Using qRT-PCR, we determined that lncRNA SNHG15 is highly expressed in CC tumor tissues and cells. lncRNA SNHG15 knockdown also reduces the tumorigenic properties of CC in vitro, as determined using the MTT, EdU, flow cytometry, and transwell assays. Using bioinformatics analysis, RNA pull-down, ChIP, and luciferase reporter assays, we verified the molecular mechanisms of lncRNA SNHG15 in CC progression and found that lncRNA SNHG15 expression in CC cells is transcriptionally regulated by SOX12; moreover, lncRNA SNHG15 promotes CC progression via the miR-4735-3p/HIF1a axis. This study can provide a potential target for CC diagnosis or therapeutic strategies in the future.

PFOI stimulates the motility of T24 bladder cancer cells: Possible involvement and activation of lncRNA malat1

Perfluorinated iodine alkanes (PFIs) can serve as an important raw materials for the synthesis of various perfluorinated chemical products through telomerization reaction. The estrogenic effects of PFIs have been reported previously by some in vitro and in vivo screening assays. To explore the potential epigenetic toxicity of PFIs, activation of lncRNAs was screened, and the cell motility changes induced by perfluorooctyl iodide (PFOI) were analyzed in this study. High metastatic bladder cell line (T24) was used to investigate the cellular migration function affected by PFOI. PFOI exposure significantly induced the upregulation of lncRNA anril, thorlnc, hotairm1, meg3, and malat1. The migration and invasion of T24 cells were also enhanced upon PFOI exposure. The transcription level of matrix metalloenzyme genes, epidermal growth factors, cytoskeleton genes, and the upstream factors involved in cell motility pathways were examined to illustrate possible mechanisms. Additionally, the basic role of malat1 in cellular motility was investigated by lncRNA knockdown and migration assays. The knockdown of malat1 inhibited the cellular motility induced by PFOI. The levels of MMP-2/-9 genes were also down-regulated by the treatment of si-malat1. Overall, the perturbation of cytoskeleton genes (E-cadherin/N-cadherin) may account for the impact on the motility of T24 cells. Our studies indicate that perfluorinated chemicals might regulate the lncRNAs, thus promoting the metastasis of the tumor cells.

RHO GTPase-Related Long Noncoding RNAs in Human Cancers

RHO GTPases are critical signal transducers that regulate cell adhesion, polarity, and migration through multiple signaling pathways. While all these cellular processes are crucial for the maintenance of normal cell homeostasis, disturbances in RHO GTPase-associated signaling pathways contribute to different human diseases, including many malignancies. Several members of the RHO GTPase family are frequently upregulated in human tumors. Abnormal gene regulation confirms the pivotal role of lncRNAs as critical gene regulators, and thus, they could potentially act as oncogenes or tumor suppressors. lncRNAs most likely act as sponges for miRNAs, which are known to be dysregulated in various cancers. In this regard, the significant role of miRNAs targeting RHO GTPases supports the view that the aberrant expression of lncRNAs may reciprocally change the intensity of RHO GTPase-associated signaling pathways. In this review article, we summarize recent advances in lncRNA research, with a specific focus on their sponge effects on RHO GTPase-targeting miRNAs to crucially mediate gene expression in different cancer cell types and tissues. We will focus in particular on five members of the RHO GTPase family, including RHOA, RHOB, RHOC, RAC1, and CDC42, to illustrate the role of lncRNAs in cancer progression. A deeper understanding of the widespread dysregulation of lncRNAs is of fundamental importance for confirmation of their contribution to RHO GTPase-dependent carcinogenesis.

Smoking is Associated with Lung Adenocarcinoma and Lung Squamous Cell Carcinoma Progression through Inducing Distinguishing lncRNA Alterations in Different Genders

BACKGROUND

Smoking participates in pathogenesis of lung cancer. Long non-coding RNAs (lncRNAs) play some specific roles during development of lung cancers.

OBJECTIVE

To investigate effects of smoking on lncRNA alterations in lung cancer.

METHODS

There are 522 lung adenocarcinoma (LUAD) and 504 lung squamous cell carcinoma (LUSC) participants. Clinical and lncRNA genetic data were downloaded from The Cancer Genome Atlas (TCGA) database. LncRNA alterations were analyzed in lung cancer patients. Smoking category and packs were evaluated. Correlations between smoking and LncRNA alterations were analyzed. Kaplan-Meier analysis was performed to determine overall survival and disease free survival.

RESULTS

There are more non-smokers in LUSC than in LUAD. In both LUAD and LUSC, smoking could increase total mutation counts and fraction of copy number alterations. Smoking index positively correlated with total mutations in LUAD, but not in LUSC. Smoking could trigger lncRNA alterations both in LUAD and LUSC. Smoking regulated different lncRNA between male and female. EXOC3-AS1 and LINC00603 alterations were positively correlated with smoking index in male LUAD smokers. In female LUAD smokers, smoking index was positively correlated with SNHG15, TP53TG1 and LINC01600 and negatively with LINC00609 and PTCSC3. In both male and female LUSC patients, smoking increased or decreased several lncRNA alterations. DGCR5 alteration increased in male LUSC than in female LUSC patients. In female LUSC patients, LOH12CR2 alteration was positively correlated with smoking index.

CONCLUSIONS

Smoking promoted LUAD and LUSC development by affecting different lncRNA alterations in different genders.

Long noncoding RNAs as diagnostic biomarkers for the early detection of digestive tract cancers: a systematic review and meta-analysis

BACKGROUND

long noncoding RNAs (lncRNAs) have attracted attention recently. However, many inconsistencies frequently appeared for the early diagnosis of digestive tract cancers (DTCs). We performed this meta-analysis to describe the diagnostic performance of lncRNAs in the discrimination of DTCs.

METHODS

data were extracted from PubMed, Web of Science, Embase, and Cochrane Library. Their quality was evaluated using the revised Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). Such parameters as sensitivity and specificity were included for pooled analyses. The STATA 12.0 and Meta-Disc 1.4 software packages were used to perform the statistical analysis.

RESULTS

sixty-nine papers were included in this meta-analysis. The pooled analysis of DTCs showed that lncRNAs had a sensitivity of 0.78 and a specificity of 0.80. The area under the summary ROC curve (AUC) was 0.86. For gastric cancer (GC), the pooled sensitivity and specificity were 0.77 (95 % CI: 0.72-0.81) and 0.75 (95 % CI: 0.71-0.79), respectively, and the AUC was 0.83. For colorectal cancer (CRC), these three parameters were 0.82 (95 % CI: 0.76-0.86), 0.84 (95 % CI: 0.79-0.88), and 0.90, respectively. For esophageal cancer (EC) sensitivity was 0.74 (95 % CI: 0.67-0.80) and specificity reached 0.86 (95 % CI: 0.72-0.93), with an AUC of 0.82.

CONCLUSIONS

LncRNAs show potential diagnostic value for discrimination between DTCs.

RNA Interference and Nanotechnology: A Promising Alliance for Next Generation Cancer Therapeutics

Cancer is a significant health hazard of the 21st century, and GLOBOCAN predicts increasing cancer incidence in the coming decades. Though several conventional treatment modalities exist, most of them end up causing off-target and debilitating effects, and drug resistance acquisition. Advances in our understanding of tumor molecular biology offer alternative strategies for precise, robust, and potentially less toxic treatment paradigms for circumventing the disease at the cellular and molecular level. Several deregulated molecules associated with tumorigenesis have been developed as targets in RNA interference (RNAi) based cancer therapeutics. RNAi, a post-transcriptional gene regulation mechanism, has significantly gained attention because of its precise multi-targeted gene silencing. Although the RNAi approach is favorable, the direct administration of small oligonucleotides has not been fruitful because of their inherent lower half-lives and instability in the biological systems. Moreover, the lack of an appropriate delivery system to the primary site of the tumor that helps determine the potency of the drug and its reach, has limited the effective medical utilization of these bio-drugs. Nanotechnology, with its unique characteristics of enhanced permeation and better tumor-targeting efficiency, offers promising solutions owing to the various possibilities and amenability for modifications of the nanoparticles to augment cancer therapeutics. Nanoparticles could be made multimodal, by designing and synthesizing multiple desired functionalities, often resulting in unique and potentially applicable biological structures. A small number of Phase I clinical trials with systemically administered siRNA molecules conjugated with nanoparticles have been completed and the results are promising, indicating that, these new combinatorial therapies can successfully and safely be used to inhibit target genes in cancer patients to alleviate some of the disease burden. In this review, we highlight different types of nano-based delivery strategies for engineering Nano-RNAi-based bio drugs. Furthermore, we have highlighted the insights gained from current research that are entering the preclinical evaluation and information about initial clinical developments, shaping the future for next generation cancer therapeutics.

High lncSNHG15 expression may predict poor cancer prognosis: a meta-analysis based on the PRISMA and the bio-informatics analysis

Background: SNHG15 has been reported to be aberrantly expressed in various tumor tissues and could serve as a promising prognostic cancer biomarker. Previous studies on SNHG15 yielded inconsistent results with insufficient sampling. Here, a meta-analysis was conducted to investigate the prognostic value of SNHG15 in multiple cancers. Methods: Relevant studies were retrieved from six electronic databases including PubMed, Cochrane Library, Google Scholar, Embase, Web of Science and China National Knowledge Infrastructure (CNKI). Fifteen publications comprising 1318 patients were included. The publication bias was identified by the Begg’s Test, and the sensitivity analysis was also performed. Results: The results demonstrated a positive correlation between high expression level of lncSNHG15 and short overall survival (hazard ratio (HR) = 2.07, 95% confidence interval (CI), 1.48–2.88; P<0.0001) and disease-free survival (DFS) (HR = 2.32, 95% CI, 1.53–3.53; P<0.0001). The analysis based on different cancer types showed that SNHG15 had the most prominent prognostic potential in Glioma (HR = 3.81; 95% CI, 0.84–42.69; P=0.28). Moreover, the high expression level of lncSNHG15 indicated advanced TNM stage (OR = 2.52; 95% CI, 1.33–4.76; P=0.00001), lymph node metastasis (OR = 2.41, 95% CI, 0.99–4.81; P=0.05), bigger tumor size (OR = 2.06; 95% CI, 1.03–4.13; P=0.04) and poor histological grade (OR = 2.62, 95% CI, 1.90–3.59; P<0.00001), yet no association with distant metastasis (OR = 1.64, 95% CI, 0.40–6.74; P=0.49), age (OR = 0.98, 95% CI, 0.78–1.22; P=0.84) and gender (OR = 0.9, 95% CI, 0.71–1.14; P=0.3838) was found. Its conclusions further confirmed by exploring TCGA databases. Conclusion: It revealed that lncSNHG15 might be a promising prognostic biomarker of multiple cancer types, especially in Glioma.

Long non-coding RNAs and cancer metastasis: Molecular basis and therapeutic implications

Cancer metastasis, defined by the epithelial to mesenchymal transition (EMT) of tumor cells, disseminates from the primary site to progressively colonize in distant tissues, and accounts for most cancer-associated deaths. However, studies on the molecular basis of cancer metastasis are still in their infancy. Besides genetic mutations, accumulating evidence indicates that epigenetic alterations also contribute in a major way to the refractory nature of cancer metastasis. Considered as one of the essential epigenetic regulators, long non-coding RNAs (lncRNAs) can act as signaling regulators, decoys, guides and scaffolds, modulating key molecules in every step of cancer metastasis including dissemination of carcinoma cells, intravascular transit, and metastatic colonization. Although still having limited clinical application, it is encouraging to witness that several lncRNAs, including CCAT1 and HOTAIR, are under clinical evaluation as potential biomarkers for cancer staging and assessment of metastatic potential. In this review, we focus on the molecular mechanisms underlying lncRNAs in the regulation of cancer metastasis and discuss their clinical potential as novel therapeutic targets as well as their diagnostic and prognostic significance for cancer treatment. Gaining clear insights into the detailed molecular basis underlying lncRNA-modulated cancer metastasis may provide previously unrecognized diagnostic and therapeutic strategies for metastatic patients.

The PARP Inhibitor Olaparib Modulates the Transcriptional Regulatory Networks of Long Non-Coding RNAs during Vasculogenic Mimicry

In highly metastatic tumors, vasculogenic mimicry (VM) involves the acquisition by tumor cells of endothelial-like traits. Poly-(ADP-ribose) polymerase (PARP) inhibitors are currently used against tumors displaying BRCA1/2-dependent deficient homologous recombination, and they may have antimetastatic activity. Long non-coding RNAs (lncRNAs) are emerging as key species-specific regulators of cellular and disease processes. To evaluate the impact of olaparib treatment in the context of non-coding RNA, we have analyzed the expression of lncRNA after performing unbiased whole-transcriptome profiling of human uveal melanoma cells cultured to form VM. RNAseq revealed that the non-coding transcriptomic landscape differed between olaparib-treated and non-treated cells: olaparib significantly modulated the expression of 20 lncRNAs, 11 lncRNAs being upregulated, and 9 downregulated. We subjected the data to different bioinformatics tools and analysis in public databases. We found that copy-number variation alterations in some olaparib-modulated lncRNAs had a statistically significant correlation with alterations in some key tumor suppressor genes. Furthermore, the lncRNAs that were modulated by olaparib appeared to be regulated by common transcription factors: ETS1 had high-score binding sites in the promoters of all olaparib upregulated lncRNAs, while MZF1, RHOXF1 and NR2C2 had high-score binding sites in the promoters of all olaparib downregulated lncRNAs. Finally, we predicted that olaparib-modulated lncRNAs could further regulate several transcription factors and their subsequent target genes in melanoma, suggesting that olaparib may trigger a major shift in gene expression mediated by the regulation lncRNA. Globally, olaparib changed the lncRNA expression landscape during VM affecting angiogenesis-related genes.

LncRNA SNHG15 contributes to doxorubicin resistance of osteosarcoma cells through targeting the miR-381-3p/GFRA1 axis

Background

Osteosarcoma is a common primary malignant bone cancer. Long noncoding RNA small nucleolar RNA host gene 15 (SNHG15) has been reported to play an oncogenic role in many cancers. Nevertheless, the role of SNHG15 in the doxorubicin (DXR) resistance of osteosarcoma cells has not been fully addressed.

Methods

Cell Counting Kit-8 assay was conducted to measure the half-maximal inhibitory concentration value of DXR in osteosarcoma cells. Western blotting was carried out to examine the levels of autophagy-related proteins and GDNF family receptor alpha-1 (GFRA1). Quantitative reverse transcription-polymerase chain reaction was performed to determine the levels of SNHG15, miR-381-3p, and GFRA1. The proliferation of osteosarcoma cells was measured by MTT assay. The binding sites between miR-381-3p and SNHG15 or GFRA1 were predicted by Starbase bioinformatics software, and the interaction was confirmed by dual-luciferase reporter assay. Murine xenograft model was established to validate the function of SNHG15 in vivo.

Results

Autophagy inhibitor 3-methyladenine sensitized DXR-resistant osteosarcoma cell lines to DXR. SNHG15 was upregulated in DXR-resistant osteosarcoma tissues and cell lines. SNHG15 knockdown inhibited the proliferation, DXR resistance, and autophagy of osteosarcoma cells. MiR-381-3p was a direct target of SNHG15, and GFRA1 bound to miR-381-3p in osteosarcoma cells. SNHG15 contributed to DXR resistance through the miR-381-3p/GFRA1 axis in vitro. SNHG15 depletion contributed to the inhibitory effect of DXR on osteosarcoma tumor growth through the miR-381-3p/GFRA1 axis in vivo.

Conclusions

SNHG15 enhanced the DXR resistance of osteosarcoma cells through elevating the autophagy via targeting the miR-381-3p/GFRA1 axis. Restoration of miR-381-3p expression might be an underlying therapeutic strategy to overcome the DXR resistance of osteosarcoma.

The lncRNA SNHG15/miR-18a-5p axis promotes cell proliferation in ovarian cancer through activating Akt/mTOR signaling pathway

Here, we report the expression pattern, function and regulatory mechanism of SNHG15 together with miR-18a-5p micro RNA in ovarian cancer (OC) for the first time. We recruited 20 patients and took normal ovarian tissues and ovarian tumor tissues from them. We used cell culture, transfection, in vivo tumor xenograft assay, and multiple types of detection assays to investigate the expression and regulation of long noncoding RNA (lncRNA) SNHG15/miR-18a-5p in ovarian tissues and cells. Results: We found that the messenger RNA expression level of SNHG15 was significantly higher and miR-18 was decreased in ovarian cancer tissues and in OC cells. Functional experiments showed that SNHG15 overexpression potentiated the migration and invasion of OC cells, while SNHG15 inhibition reduced the tumor proliferation, which was restored via overexpression of miR-18a. SNHG15 was found to directly target and suppress the expression of miR-18a. Our results illustrate the possible molecular mechanism of lncRNA SNHG15/miR-18a-5p functions in cell proliferation in OC. SNHG15/miR-18a promoted the progression of OC cells via the protein kinase B/mammalian target of rapamycin signaling pathway.

Long non-coding RNA SNHG15 in various cancers: a meta and bioinformatic analysis

Background

The snoRNA host gene SNHG15 produces a long non-coding RNA (lncRNA) with a short half-life and has been reported to be dysregulated in multiple cancers and has recently been found to be correlated with tumour progression. Therefore, this meta-analysis was performed to evaluate the generalised prognostic role of small nucleolar RNA host gene 15 (SNHG15) in malignancies, based on variable data from different studies.

Methods

Four public databases were used to identify eligible studies. The association between prognostic indicators and clinical features was extracted and pooled to estimate the hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs). Publication bias was measured using Begg’s test and Egger’s test, and the stability of pooled results were measured using sensitivity analysis. Additionally, an online database based on The Cancer Genome Atlas (TCGA) was screened to further validate our results. Ultimately, we predicted the molecular regulation of SNHG15 based on the public databases.

Results

In total, 11 studies including 1087 patients were ultimately enrolled in our meta-analysis. We found that SNHG15 overexpression was associated with worse overall survival (OS) and disease-free survival (DFS), and this was validated in the Gene Expression Profiling Interactive Analysis (GEPIA) cohort. Moreover, increased SNHG15 expression suggested advanced TNM stage and LNM, but was not associated with age, gender, or tumour size. No publication bias or instability of the results was observed. SNHG15 was significantly upregulated in seven cancers and elevated expression of SNHG15 indicated shorter OS and DFS in five malignancies based on the validation using the GEPIA cohort. Further functional prediction indicated that SNHG15 may participate in some cancer-related pathways.

Conclusions

Upregulation of lncRNA SNHG15 was notably associated with worse prognosis and clinical features, suggesting that SNHG15 might serve as a novel prognostic factor in various cancers.

LncRNA SNHG15 Contributes to Immuno-Escape of Gastric Cancer Through Targeting miR141/PD-L1

Introduction

Long non-coding RNAs (lncRNAs) have been demonstrated to participate in many biological processes and severs as important regulators during the progression of gastric cancer.

Methods

Here, we introduced human lncRNA SNHG15 which was highly expressed in gastric cancer and cells. Interestingly, the expression of SNHG15 was correlated with programmed cell death ligand 1 (PD-L1), which promotes the resistance of gastric cancer cells to immune responses. Meanwhile, SNHG15 downregulation suppressed the expression of PD-L1 and resistance of immune responses.

Results

Further, our results suggested that SNHG15 acted as a competing endogenous RNA (CeRNA) to sponge miR-141, which was downregulated in gastric cancers and negatively correlated to PD-L1.

Conclusion

Our results suggested that SNHG15 improved the expression of PD-L1 by inhibiting miR-141, which in turn promoted the resistance of stomach cancer cells to the immune responses.

High Expression of the Long Noncoding RNA SNHG15 in Cancer Tissue Samples Predicts an Unfavorable Prognosis of Cancer Patients: A Meta-Analysis

Background

Although the prognostic value of lncRNA small nucleolar RNA host gene 15 (SNHG15) expression in cancers has been evaluated in many studies, the results remain controversial. This meta-analysis aimed to clarify the role of SNHG15 in the prognosis of different cancer patients.

Materials and Methods

Eligible studies were selected from PubMed, PMC, EMBASE, Web of Science, and Cochrane Library according to the inclusion and exclusion criteria (up to December 20, 2019). The primary outcome was overall survival (OS) and recurrence-free survival (RFS). The secondary outcome was other clinicopathological parameters (including advanced TNM stage, lymph node metastasis, distant metastases, and gender). The Cancer Genome Atlas (TCGA) dataset was used to verify the analysis results.

Results

Eleven eligible studies were eventually included, involving 9 different types of cancer and 1,079 patients. The high expression of SNHG15 was indicative of a significantly poor OS of cancer patients (HR = 1.96, 95% CI = 1.55–2.47, P < 0.00001). Subgroup analysis showed that the high expression of SNHG15 was associated with a significantly poor OS of patients with digestive cancer (HR = 1.91, 95% CI = 1.38–2.66, P=0.0001), but not lung cancer (HR = 1.83, 95% CI = 0.89–3.76, P=0.010). The RFS of patients with high expression of SNHG15 was shorter than that of patients with low expression of SNHG15 (HR = 2.03, 95% CI = 1.46–2.83, P < 0.00001). In addition, high SNHG15 expression level was significantly correlated with later TNM stage (OR = 3.05, 95% CI = 2.31–4.02, P < 0.00001), lymphatic metastasis (OR = 3.20, 95% CI = 2.30–4.45, P < 0.00001), and distant metastasis (OR = 5.05, 95% CI = 2.15–11.85, P=0.0002). The TCGA verification results were consistent with those observed in our meta-analysis.

Conclusion

High expression of the long noncoding RNA SNHG15 in cancer tissue samples predicts an unfavorable prognosis for cancer patients. LncRNA SNHG15 can be used as an adverse prognostic biomarker for cancer patients.

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.

Long non-coding RNA signature in gastric cancer

Gastric cancer as a common human malignancy has been associated with aberrant expressions of several coding and non-coding genes. Long non-coding RNAs (lncRNAs) as regulators of gene expressions at different genomic, transcriptomic and post-transcriptomic levels are among putative biomarkers and therapeutic targets in gastric cancer. In the present study, we have searched available literature and listed lncRNAs that are involved in the pathogenesis of gastric cancer. In addition, we discuss associations between expressions of these lncRNAs and tumoral features or risk factors for gastric cancer. Based on the established role of lncRNAs in regulation of genomic stability, cell cycle, apoptosis, angiogenesis and other aspects of cell physiology, the potential of these transcripts as therapeutic targets in gastric cancer should be evaluated in future studies.

Long non-coding small nucleolar RNA host genes in digestive cancers

Although long noncoding RNAs (lncRNAs) do not have protein coding capacities, they are involved in the pathogenesis of many types of cancers, including hepatocellular carcinoma, cervical cancer, and gastric cancer. Notably, the roles of lncRNAs are vital in nearly every aspect of tumor biology. Long non-coding small nucleolar RNA host genes (lnc-SNHGs) are abnormally expressed in multiple cancers, including urologic neoplasms, respiratory tumors, and digestive cancers, and play vital roles in these cancers. These host genes could participate in tumorigenesis by regulating proliferation, migration, invasion and apoptosis of tumor cells. This review focuses on the overview of the roles that lnc-SNHGs play in the formation and progression of digestive cancers.

Long Non-Coding RNA HOTAIR Modulates KLF12 to Regulate Gastric Cancer Progression via PI3K/ATK Signaling Pathway by Sponging miR-618

Purpose

Long non-coding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) has been reported to dysregulate in many tumors. However, the mechanism of HOTAIR was rarely reported in GC.

Methods

The levels of HOTAIR, microRNA-618 (miR-618) and Krueppel-like factor 12 (KLF12) in GC tissues and cells were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The cell viability and apoptotic rate were assessed via cell counting kit-8 (CCK-8) assay and flow cytometry, respectively. The migrating and invading abilities were tested by Transwell assay. The protein levels of KLF12, p-PI3K, PI3K, p-ATK and ATK were measured by Western blot assay. These interactions between miR-618 and HOTAIR or KLF12 were predicted by DIANA tools, and then, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were conducted to validate these interactions. Besides, the xenograft tumor experiment was performed to further verify the roles of HOTAIR in GC.

Results

The levels of HOTAIR and KLF12 were significantly upregulated and the level of miR-618 was strikingly downregulated in GC tissues and cells. miR-618 was verified as a direct target of HOTAIR or KLF12. HOTAIR silencing blocked GC progression and PI3K/ATK signaling pathway by sponging miR-618 and also restrained xenograft tumor growth in vivo. miR-618 inhibited GC progression and PI3K/ATK signaling pathway by targeting KLF12. Mechanistically, HOTAIR modulated KLF12 expression by sponging miR-618 in GC cells.

Conclusion

These data unraveled that HOTAIR promoted GC progression through PI3K/ATK signaling pathway via miR-618/KLF12 axis.

LncRNA SNHG15: A new budding star in human cancers

OBJECTIVES

Long non-coding RNAs (lncRNAs) represent an important group of non-coding RNAs (ncRNAs) with more than 200 nucleotides in length that are transcribed from the so-called genomic "dark matter." Mounting evidence has shown that lncRNAs have manifested a paramount function in the pathophysiology of human diseases, especially in the pathogenesis and progression of cancers. Despite the exponential growth in lncRNA publications, our understanding of regulatory mechanism of lncRNAs is still limited, and a lot of controversies remain in the current lncRNA knowledge.The purpose of this article is to explore the clinical significance and molecular mechanism of SNHG15 in tumors.

MATERIALS & METHODS

We have systematically searched the Pubmed, Web of Science, Embase and Cochrane databases. We provide an overview of current evidence concerning the functional role, mechanistic models and clinical utilities of SNHG15 in human cancers in this review.

RESULTS

Small nucleolar RNA host gene 15 (SNHG15), a novel lncRNA, is identified as a key regulator in tumorigenesis and progression of various human cancers, including colorectal cancer (CRC), gastric cancer (GC), pancreatic cancer (PC) and hepatocellular carcinoma (HCC). Dysregulation of SNHG15 has been revealed to be dramatically correlated with advanced clinicopathological factors and predicts poor prognosis, suggesting its potential clinical value as a promising biomarker and therapeutic target for cancer patients.

CONCLUSIONS

LncRNA SNHG15 may serve as a prospective and novel biomarker for molecular diagnosis and therapeutics in patients with cancer.

lncRNA-SNHG15 accelerates the development of hepatocellular carcinoma by targeting miR-490-3p/ histone deacetylase 2 axis

BACKGROUND

Hepatocellular carcinoma (HCC) has become a great threat for people’s health. Many long noncoding RNAs are involved in the pathogenesis of HCC. SNHG15, as a tissue specific long noncoding RNAs, has been studied in many human cancers, except HCC.

AIM

To explore the regulatory mechanism of SNHG15 in HCC.

METHODS

In the present research, 101 HCC patient samples, two HCC cell lines and one normal liver cell line were used. RT-qPCR and Western blot analysis were applied to detect SNHG15, miR-490-3p and histone deacetylase 2 (HDAC2) expression. The regulatory mechanism of SNHG15 was investigated using CCK-8, Transwell and luciferase reporter assays.

RESULTS

Our research showed that up-regulation of SNHG15 was found in HCC and was related to aggressive behaviors in HCC patients. Moreover, knockdown of SNHG15 restrained HCC cell proliferation, migration and invasion. In addition, SNHG15 served as a molecular sponge for miR-490-3p. Further, miR-490-3p directly targets HDAC2. HDAC2 was involved in HCC progression by interacting with the SNHG15/miR-490-3p axis.

CONCLUSION

In conclusion, long noncoding RNA SNHG15 promotes HCC progression by mediating the miR-490-3p/HDAC2 axis in HCC.

Mechanisms Underlying Therapeutic Effects Of Traditional Chinese Medicine On Gastric Cancer

Gastric cancer (GC) is one of the most common malignant tumors in the world. It is the fourth most common cancer and has the second highest mortality rate globally. Metastasis is an important feature of gastric cancer and is the most common cause of death. Exploring the mechanism underlying the metastasis of gastric cancer and searching for new drug targets has become the focus of several studies. Traditional Chinese medicine may show promise for treatment of gastric cancer. In this review, we report the recent progress in research on the anti-metastasis activity of Chinese medicine, to facilitate clinical development of treatments for gastric cancer.

Modulating lncRNA SNHG15/CDK6/miR-627 circuit by palbociclib, overcomes temozolomide resistance and reduces M2-polarization of glioma associated microglia in glioblastoma multiforme

Background

Accumulating evidence demonstrates the oncogenic roles of lncRNA (long non-coding RNA) molecules in a wide variety of cancer types including glioma. Equally important, However, tumorigenic functions of lncRNA in glioma remain largely unclear. A recent study suggested lncRNA SNHG15 played a role for regulating angiogenesis in glioma but its role in the tumor microenvironment (TME) was not investigated.

Methods

First, we showed that SNHG15 was upregulated in GBM cells and associated with a poor prognosis for the patients of GBM using public databases. Next, we collected temozolomide sensitive (TMZ-S) and resistant (TMZ-R) clinical samples and demonstrated that co-culturing TMZ-R cells with HMC3 (microglial) cells promoted M2-polarization of HMC3 and the secretion of pro-GBM cytokines TGF-β and IL-6.

Results

Comparative qPCR analysis of TMZ-S and TMZ-R cells showed that a significantly higher level of SNHG15, coincidental with a higher level of Sox2, β-catenin, EGFR, and CDK6 in TMZ-R cells. Subsequently, using bioinformatics tool, a potential mechanistic route for SNHG15 to promote GBM tumorigenesis was by inhibiting tumor suppressor, miR-627-5p which leads to activation of CDK6. Gene-silencing technique was employed to demonstrate that suppression of SNHG15 indeed led to the suppression of GBM tumorigenesis, accompanied by an increase miR-627-5p and decreased its two oncogenic targets, CDK6 and SOX-2. In addition, SNHG15-silenced TMZ-R cells became significantly sensitive towards TMZ treatment and less capable of promoting M2-phenotype in the HMC3 microglial cells. We then evaluated the potential anti-GBM activity of CDK6 inhibitor, palbociclib, using TMZ-R PDX mouse models. Palbociclib treatment significantly reduced tumorigenesis in TMZ-R/HMC3 bearing mice and SNHG15 and CDK6 expression was significantly reduced while miR-627-5p level was increased. Additionally, palbociclib treatment appeared to overcome TMZ resistance as well as reduced M2 markers in HMC3 cells.

Conclusion

Together, we provided evidence supporting the usage of CDK6 inhibitor for TMZ-resistant GBM cases. Further investigation is warranted for the consideration of clinical trials.

Graphical abstract

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1371-0) contains supplementary material, which is available to authorized users.

CXCL1 stimulates migration and invasion in ER‑negative breast cancer cells via activation of the ERK/MMP2/9 signaling axis

Chemokine (C‑X‑C motif) ligand 1 (CXCL1), a member of the CXC chemokine family, has been reported to be a critical factor in inflammatory diseases and tumor progression; however, its functions and molecular mechanisms in estrogen receptor α (ER)‑negative breast cancer (BC) remain largely unknown. The present study demonstrated that CXCL1 was upregulated in ER‑negative BC tissues and cell lines compared with ER‑positive tissues and cell lines. Treatment with recombinant human CXCL1 protein promoted ER‑negative BC cell migration and invasion in a dose‑dependent manner, and stimulated the activation of phosphorylated (p)‑ extracellular signal‑regulated kinase (ERK)1/2, but not p‑STAT3 or p‑AKT. Conversely, knockdown of CXCL1 in BC cells attenuated these effects. Additionally, CXCL1 increased the expression of matrix metalloproteinase (MMP)2/9 via the ERK1/2 pathway. Inhibition of MEK1/2 by its antagonist U0126 reversed the effects of CXCL1 on MMP2/9 expression. Furthermore, immunohistochemical analysis revealed a strong positive association between CXCL1 and p‑ERK1/2 expression levels in BC tissues. In conclusion, the present study demonstrated that CXCL1 is highly expressed in ER‑negative BC, and stimulates BC cell migration and invasion via the ERK/MMP2/9 pathway. Therefore, CXCL1 may serve as a potential therapeutic target in ER‑negative BC.

SNHG15: a promising cancer-related long noncoding RNA

Cancer is expected to rank as the leading cause of death worldwide due to increasing morbidity and mortality. Long noncoding RNAs (lncRNAs) have been found to play pivotal roles in multiple biological processes, such as transcriptional interference, posttranscriptional regulation and epigenetic modification. Small nucleolar RNA host gene 15 (SNHG15), a snoRNA host gene which produces a short half-lived lncRNA, was reported to be upregulated in tumor cells and participate in the occurrence and development of multiple cancers. And more than half of the SNHG15 research in cancers has been published within the last 2 years. In this review, we summarized the current evidence concerning the biological functions and molecular mechanisms of SNHG15 in various cancers, including gastric, hepatocellular, pancreatic, colorectal, breast, and thyroid cancer, osteosarcoma, glioma, lung cancer, renal cell carcinoma, and epithelial ovarian cancer. SNHG15 plays critical roles in regulation of cell proliferation, migration and invasion of tumors via different potential mechanisms. Moreover, the abnormal expression of SNHG15 was associated with clinical features of patients with cancers. Consequently, SNHG15 could be considered as a promising biomarker for cancer diagnosis, prognosis or treatment.

In silico identification of novel lncRNAs with a potential role in diagnosis of gastric cancer

Gastric cancer (GC) is the second leading cause of cancer-related deaths in the world. Due to the shortage of adequate symptoms in the early stages, it is diagnosed when the tumor has spread to distant organs. Early recognition of GC enhances the chance of successful treatment. Molecular mechanisms of GC are still poorly understood. LncRNAs are emerging as new players in cancer in both oncogene and tumor suppressor roles. High-throughput technologies such as RNA-Seq, have revealed thousands of lncRNAs which are dysregulated in GC. In this study, we retrieved lncRNAs obtained by High-throughput technologies from OncoLnc database. Consequently, retrieved lncRNAs were compared in literature-based databases including PubMed. As a result, two lists, including experimentally validated lncRNAs and predicted lncRNAs were provided. We found 43 predicted lncRNAs that had not been experimentally validated in GC, so far. Further Bioinformatics analyses were performed to obtain the expression profile of predicted lncRNAs in tumor and normal tissues. Also, the roles and targets of predicted lncRNAs in GC were identified by related databases. Finally, using the GEPIA database was reviewed the significant relationship of predicted lncRNAs with the survival of GC patients. By recognizing the lncRNAs involved in initiation and progression of GC, they may be considered as potential biomarkers in the GC early diagnosis or targeted treatment and lead to novel therapeutic strategies. Communicated by Ramaswamy H. Sarma.

LncRNAs with miRNAs in regulation of gastric, liver, and colorectal cancers: updates in recent years

Long noncoding RNA (lncRNA) is a kind of RNAi molecule composed of hundreds to thousands of nucleotides. There are several major types of functional lncRNAs which participate in some important cellular pathways. LncRNA-RNA interaction controls mRNA translation and degradation or serves as a microRNA (miRNA) sponge for silencing. LncRNA-protein interaction regulates protein activity in transcriptional activation and silencing. LncRNA guide, decoy, and scaffold regulate transcription regulators of enhancer or repressor region of the coding genes for alteration of expression. LncRNA plays a role in cellular responses including the following activities: regulation of chromatin structural modification and gene expression for epigenetic and cell function control, promotion of hematopoiesis and maturation of immunity, cell programming in stem cell and somatic cell development, modulation of pathogen infection, switching glycolysis and lipid metabolism, and initiation of autoimmune diseases. LncRNA, together with miRNA, are considered the critical elements in cancer development. It has been demonstrated that tumorigenesis could be driven by homeostatic imbalance of lncRNA/miRNA/cancer regulatory factors resulting in biochemical and physiological alterations inside the cells. Cancer-driven lncRNAs with other cellular RNAs, epigenetic modulators, or protein effectors may change gene expression level and affect the viability, immortality, and motility of the cells that facilitate cancer cell cycle rearrangement, angiogenesis, proliferation, and metastasis. Molecular medicine will be the future trend for development. LncRNA/miRNA could be one of the potential candidates in this category. Continuous studies in lncRNA functional discrepancy between cancer cells and normal cells and regional and rational genetic differences of lncRNA profiles are critical for clinical research which is beneficial for clinical practice.

SNHG15 is a bifunctional MYC-regulated noncoding locus encoding a lncRNA that promotes cell proliferation, invasion and drug resistance in colorectal cancer by interacting with AIF

Background

Thousands of long noncoding RNAs (lncRNAs) are aberrantly expressed in various types of cancers, however our understanding of their role in the disease is still very limited.

Methods

We applied RNAseq analysis from patient-derived data with validation in independent cohort of patients. We followed these studies with gene regulation analysis as well as experimental dissection of the role of the identified lncRNA by multiple in vitro and in vivo methods.

Results

We analyzed RNA-seq data from tumors of 456 CRC patients compared to normal samples, and identified SNHG15 as a potentially oncogenic lncRNA that encodes a snoRNA in one of its introns. The processed SNHG15 is overexpressed in CRC tumors and its expression is highly correlated with poor survival of patients. Interestingly, SNHG15 is more highly expressed in tumors with high levels of MYC expression, while MYC protein binds to two E-box motifs on SNHG15 sequence, indicating that SNHG15 transcription is directly regulated by the oncogene MYC.

The depletion of SNHG15 by siRNA or CRISPR-Cas9 inhibits cell proliferation and invasion, decreases colony formation as well as the tumorigenic capacity of CRC cells, whereas its overexpression leads to opposite effects. Gene expression analysis performed upon SNHG15 inhibition showed changes in multiple relevant genes implicated in cancer progression, including MYC, NRAS, BAG3 or ERBB3. Several of these genes are functionally related to AIF, a protein that we found to specifically interact with SNHG15, suggesting that the SNHG15 acts, at least in part, by regulating the activity of AIF. Interestingly, ROS levels, which are directly regulated by AIF, show a significant reduction in SNHG15-depleted cells. Moreover, knockdown of SNHG15 increases the sensitiveness of the cells to 5-FU, while its overexpression renders them more resistant to the chemotherapeutic drug.

Conclusion

Altogether, these results describe an important role of SNHG15 in promoting colon cancer and mediating drug resistance, suggesting its potential as prognostic marker and target for RNA-based therapies.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1169-0) contains supplementary material, which is available to authorized users.

LncRNA SNHG15 acts as an oncogene in prostate cancer by regulating miR-338-3p/FKBP1A axis

Long non-coding RNAs (lncRNAs) are crucial regulators in the progression of various diseases. Although the role of lncRNAs in prostate cancer (PCa) has been studied in recent years, there are still numerous lncRNAs need to be elucidated. This study aims to detect the role of lncRNA small nucleolar RNA host gene 15 (SNHG15) in human prostate cancer. Using qRT-PCR analysis, we identified the upregulation of SNHG15 in PCa cell lines. Loss-of function assays were conducted to determine the regulatory effect of SNHG15 on PCa cell proliferation, migration and epithelial-mesenchymal transition (EMT). According to the results of functional assays, we found that knockdown of SNHG15 impaired cell viability, suppressed cell proliferation, inhibited cell migration and invasion, reversed EMT progress. All these findings revealed the oncogenic function of SNHG15 in PCa. Mechanism investigation revealed that SNHG15 was located in the cytoplasm of PCa cells and acted as a molecular sponge of microRNA-338-3p (miR-338-3p). Moreover, FKBP prolyl isomerase 1A (FKBP1A) was a target of miR-338-3p. This investigation demonstrated that SNHG15 may serve as a competing endogenous RNA (ceRNA) to regulate miR-338-3p and FKBP1A. Finally, the involvement of miR-338-3p and FKBP1A in SNHG15-mediated biological function was demonstrated by performing rescue assays. In summary, our study revealed the function of a novel pathway in PCa.

LncRNA-SNHG15 enhances cell proliferation in colorectal cancer by inhibiting miR-338-3p

The incidence and death rate of colorectal cancer (CRC) is very high, which brings great need to understand the early molecular events of CRC. These studies demonstrate that long noncoding RNA (lncRNA) plays an important role in the occurrence and development of human cancer. Small nucleolar RNA host gene 15 (SNHG15) was recently identified as a cancer‐related lncRNA. In this study, we aimed to evaluate the function and mechanism of SNHG15 in CRC. The expression of SNHG15 was detected by quantitative RT‐PCR (qRT‐PCR) in CRC tissues and matched noncancerous tissues (NCTs). CCK‐8 assay, colony formation assay, flow cytometric analysis, and nude mouse xenograft mode were used to examine the tumor‐promoting function of SNHG15 in vitro and in vivo. The binding relationship between SNHG15, miR‐338‐3p and the target genes of miR‐338‐3p were screened and identified by databases, qRT‐PCR, dual luciferase reporter assay and western blot. Our results showed that SNHG15 was up‐regulated in CRC tissues compared with paired NCTs (P < 0.0001). High level of SNHG15 expression predicted poor prognosis of CRC (P = 0.0051). SNHG15 overexpression could promote cell proliferation and inhibit cell apoptosis. Animal experiments showed that up‐regulation of SNHG15 promoted tumor growth in vivo. The results of mechanism experiments showed that SNHG15 could bind to miR‐338‐3p and block its inhibition on the expression and activity of FOS or RAB14. In conclusion SNHG15 promotes cell proliferation through SNHG15/miR‐338‐3p/FOS‐RAB14 axis in CRC.

SNHG15 functions as a tumor suppressor in thyroid cancer

Small nucleolar RNA host gene 15 (SNHG15) has been suggested to be overexpressed, and function as an oncogenic long noncoding RNA (lncRNA) in various types of human malignancies. However, the expression status and function of SNHG15 were still unknown in thyroid cancer. In our study, we assessed the expression status and clinical value in thyroid cancer samples, and explored the effect of SNHG15 on thyroid cancer cell proliferation, migration, and invasion. In results, SNHG15 expression was downregulated in thyroid cancer tissues and cells, and correlated with age, pathology classification, clinical stage, tumor size, distant metastasis, and disease-free survival. The in vitro studies suggested SNHG15 overexpression suppressed cell proliferation, migration, and invasion in thyroid cancer. In summary, SNHG15 serves as tumor suppressive role in thyroid cancer.

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

Objective

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

Materials and methods

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

Results

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

Conclusion

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

Competing endogenous RNA (ceRNA) cross talk and language in ceRNA regulatory networks: A new look at hallmarks of breast cancer

Breast cancer (BC) is the most frequently occurring malignancy in women worldwide. Despite the substantial advancement in understanding the molecular mechanisms and management of BC, it remains the leading cause of cancer death in women. One of the main reasons for this obstacle is that we have not been able to find the Achilles heel for the BC as a highly heterogeneous disease. Accumulating evidence has revealed that noncoding RNAs (ncRNAs), play key roles in the development of BC; however, the involving of complex regulatory interactions between the different varieties of ncRNAs in the development of this cancer has been poorly understood. In the recent years, the newly discovered mechanism in the RNA world is "competing endogenous RNA (ceRNA)" which proposes regulatory dialogues between different RNAs, including long ncRNAs (lncRNAs), microRNAs (miRNAs), transcribed pseudogenes, and circular RNAs (circRNAs). In the latest BC research, various studies have revealed that dysregulation of several ceRNA networks (ceRNETs) between these ncRNAs has fundamental roles in establishing the hallmarks of BC development. And it is thought that such a discovery could open a new window for a better understanding of the hidden aspects of breast tumors. Besides, it probably can provide new biomarkers and potential efficient therapeutic targets for BC. This review will discuss the existing body of knowledge regarding the key functions of ceRNETs and then highlights the emerging roles of some recently discovered ceRNETs in several hallmarks of BC. Moreover, we propose for the first time the "ceRnome" as a new term in the present article for RNA research.

Prognostic Value of Long Noncoding RNAs in Patients with Gastrointestinal Cancer: A Systematic Review and Meta-Analysis

Gastrointestinal cancers (GICs) are a huge threat to human health, which mainly include esophageal, gastric, and colorectal cancers. The purpose of this study was to clarify the prognostic value of long noncoding RNAs (lncRNAs) in GICs. A total of 111 articles were included, and 13103 patients (3123 with esophageal cancer, 4972 with gastric cancer, and 5008 with colorectal cancer) were enrolled in this study. The pooled hazard ratio (HR) values and corresponding 95% confidence interval (95% CI) of overall survival (OS) related to different lncRNA expressions in esophageal, gastric, colorectal, and gastrointestinal cancer patients were 1.92 (1.70–2.16), 1.96 (1.77–2.16), 2.10 (1.87–2.36), and 2.00 (1.87–2.13), respectively. We have identified 74 lncRNAs which were associated closely with poor prognosis of GIC patients, including 58 significantly upregulated lncRNA expression and 16 significantly downregulated lncRNA expression. In addition, 47 of the included studies revealed relative mechanisms and 12 of them investigated the correlation between lncRNAs and microRNAs. Taken together, this meta-analysis supports that specific lncRNAs are significantly related to the prognosis of GIC patients and may serve as novel markers for predicting the prognosis of GIC patients. Furthermore, lncRNAs may have a promising contribution to lncRNA-based targeted therapy and clinical decision-making in the future.

Cancer Stem Cells: Emergent Nature of Tumor Emergency

A functional analysis of 167 genes overexpressed in Krebs-2 tumor initiating cells was performed. In the first part of the study, the genes were analyzed for their belonging to one or more of the three groups, which represent the three major phenotypic manifestation of malignancy of cancer cells, namely (1) proliferative self-sufficiency, (2) invasive growth and metastasis, and (3) multiple drug resistance. 96 genes out of 167 were identified as possible contributors to at least one of these fundamental properties. It was also found that substantial part of these genes are also known as genes responsible for formation and/or maintenance of the stemness of normal pluri-/multipotent stem cells. These results suggest that the malignancy is simply the ability to maintain the stem cell specific genes expression profile, and, as a consequence, the stemness itself regardless of the controlling effect of stem niches. In the second part of the study, three stress factors combined into the single concept of "generalized cellular stress," which are assumed to activate the expression of these genes, were defined. In addition, possible mechanisms for such activation were identified. The data obtained suggest the existence of a mechanism for the de novo formation of a pluripotent/stem phenotype in the subpopulation of "committed" tumor cells.

Aberrant expression of long noncoding RNA SNHG15 correlates with liver metastasis and poor survival in colorectal cancer

Long noncoding RNAs (lncRNAs) play a critical role in the initiation and progression of colorectal cancer (CRC), but little is known about the function of lncRNAs in the colorectal liver metastasis (CLM). This study was designed to identify specific lncRNAs correlating to liver metastasis of CRC, and to further assess their clinical value. Seventeen patients with primary CRC lesions, adjacent normal mucosa, and synchronous liver metastases lesions were divided into discovery set (six patients) and test set (11 patients). Transcriptome sequencing (RNAseq) was used to screen differential expression of lncRNAs in the discovery set. Based on bioinformatics data, quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was used to verify the target lncRNA in test set. The relationships between target lncRNA and clinical values were analysed in an expanded validation set of additional 91 patients. 23 upregulated and 14 downregulated lncRNAs were detected for distinguishing synchronous liver metastases, primary CRC lesions from adjacent normal mucosa in the RNAseq set. The expression levels of four lncRNAs in the 37 lncRNA signature were verified by qRT-PCR in the test set. Compared with the paired normal mucosa, high expression levels of lnc-small-nucleolar RNA host gene 15 (SNHG15) were detected not only in primary CRC lesions but also in liver metastases lesions in the test set. Furthermore, in the expanded validation set, high expression of lnc-SNHG15 was significantly associated with lymph-node metastasis and liver metastasis (p < 0.05), and patients displaying high lncRNA-SNHG15 expression exhibited a shorter median overall survival duration than those displaying low expression (30.7 vs. 35.2 months; p = 0.003). Multivariate analyses demonstrated that lncRNA-SNHG15 overexpression may serve as a poor prognostic biomarker for CRC patients (p = 0.049; Cox's regression: 2.731). Lnc-SNHG15 overexpression was significantly associated with CLM and high-expression of lnc-SNHG15 in CRC was an independent predictor of poor survival.

LncRNA SNHG15 acts as a ceRNA to regulate YAP1-Hippo signaling pathway by sponging miR-200a-3p in papillary thyroid carcinoma

Over the past decade, lncRNAs have been widely reported in human malignant tumors, including papillary thyroid carcinoma. LncRNA SNHG15 has been validated to be a tumor facilitator in several types of malignancies. The present study focused on the biological role of SNHG15 in papillary thyroid carcinoma. Based on the result of qPCR analysis, we identified the strong expression of SNHG15 in human papillary thyroid carcinoma tissues and cell lines. Moreover, Kaplan–Meier method was utilized to analyze the internal relevance between SNHG15 expression and overall survival rate of patients with papillary thyroid carcinoma. Loss-of-function assays were designed and conducted to determine the inhibitory effects of silenced SNHG15 on the cell growth and migration in papillary thyroid carcinoma. The mechanical investigation indicated that SNHG15 upregulated YAP1 by sponging miR-200a-3p. Moreover, results of gain-of-function assays validated the anti-oncogenic function of miR-200a-3p in papillary thyroid carcinoma. Finally, results of rescue assays validated the function of SNHG15-miR-200a-3p-YAP1 axis in papillary thyroid carcinoma. YAP1 is known as an oncogene and a core factor of Hippo pathway. Here, we demonstrated that SNHG15 inactivated Hippo signaling pathway in papillary thyroid carcinoma. In summary, our findings demonstrated that SNHG15 serves as a competitively endogenous RNA (ceRNA) to regulate YAP1-Hippo signaling pathway by sponging miR-200a-3p in papillary thyroid carcinoma.

Long non-coding RNAs involved in metastasis of gastric cancer

Gastric cancer (GC) is one of the most frequently diagnosed malignant diseases. The molecular mechanisms of metastasis remain unclear. Recently, studies have shown that long non-coding RNAs (lncRNAs) play critical roles in metastasis. Therefore, deeper understanding of this mechanism could provide potential diagnostic tools and therapeutic targets for metastatic GC. This review focuses on dysregulated lncRNAs in GC metastases. Due to the identification of multiple diverse mechanisms involved in GC metastasis, we classified them into seven categories, including lncRNAs related to epithelial-mesenchymal transition, regulation of degradation of extracellular matrix, angiopoiesis, vasculogenic mimicry, and immunologic escape. As the TNM stage is pivotal for evaluating the severity and prognosis of GC patients, we summarize the lncRNAs relevant to lymphatic metastasis, distant metastasis and TNM classification. This review summarizes the lncRNAs related to metastasis, which may provide insight into the mechanisms, and provide potential markers for prognostic prediction and monitoring the relapse of GC.

Long non-coding RNAs in the gastric juice of gastric cancer patients

Differently from other digestive malignancies, gastric cancer (GC) carcinogenesis seems more heterogeneous and unclear. This entails failing in identification of reliable serum tumor markers for screening early GC (EGC) as well as persisting ominous prognosis of this disease. Recently, investigation of human noncoding genome, especially long noncoding molecules (lncRNAs), has provided promising data. As for GC, however, since the current information on GC-specific lncRNAs is still scarce and comes largely from analyses performed on tissue or serum of affected patients, we decided to review the current literature dealing with expression of such molecules in the gastric juice (GJ) of GC patients. In the case of GC, in fact, several cytological and molecular works have already demonstrated GJ to be an interesting biological material for improving clinicopathologic and prognostic knowledge of this cancer. For this review, we burrowed into the literature on lncRNAs expressed in GJ of GC patients. PubMed, Science Direct, Scopus, Web of Science, Google Scholar and ResearchGate were the search engines entertained. As of 2018, only seven studies have been reported. LINC00152, AA174084, UCA1, RMRP, ABHD11-AS1, LINC00982 and H19 were the GJ lncRNAs examined. Following our review, we can conclude that, due to their high specificity and reliability, GJ lncRNAs should deserve a prominent role in the field of GC research: importantly, they could be used for screening EGC, ameliorating the existing methods of staging (which are still far from being completely accurate), improving the prognostic capacity of the current diagnostic armamentarium and, finally, providing new and valuable therapeutic targets.