Long non-coding RNA SNHG12promotes the proliferation and migration of glioma cells by binding to HuR

Molecular mechanism of lncRNA SNHG12 in immune escape of non-small cell lung cancer through the HuR/PD-L1/USP8 axis

Background

The pivotal role of long noncoding RNAs (lncRNAs) in cancer immune responses has been well established. This study was conducted with the aim of exploring the molecular mechanism of lncRNA small nucleolar RNA host gene 12 (SNHG12) in immune escape of non-small cell lung cancer (NSCLC).

Methods

Expression of lncRNA SNHG12, programmed cell death receptor ligand 1 (PD-L1), ubiquitin-specific protease 8 (USP8), and human antigen R (HuR) in NSCLC tissues and cells was measured, and their binding relationship was determined. NSCLC cell proliferation and apoptosis were assessed. Peripheral blood mononuclear cells (PBMCs) were co-cultured with NSCLC cells. The ratio of CD8⁺ T cells, PBMC proliferation, and inflammatory factors were determined. lncRNA SNHG12 localization was assessed via subcellular fractionation assay. The half-life period of mRNA was determined using actinomycin D. Xenograft tumor models were established to confirm the role of lncRNA SNHG12 in vivo.

Results

LncRNA SNHG12 was found to be prominently expressed in NSCLC tissues and cells, which was associated with a poor prognosis. Silencing lncRNA SNHG12 resulted in the reduction in proliferation and the promotion of apoptosis of NSCLC cells, while simultaneously increasing PBMC proliferation and the ratio of CD8⁺ T cells. Mechanically, the binding of lncRNA SNHG12 to HuR improved mRNA stability and expression of PD-L1 and USP8, and USP8-mediated deubiquitination stabilized the protein level of PD-L1. Overexpression of USP8 or PD-L1 weakened the inhibition of silencing lncRNA SNHG12 on the immune escape of NSCLC. Silencing lncRNA SNHG12 restricted tumor growth and upregulated the ratio of CD8⁺ T cells by decreasing USP8 and PD-L1.

Conclusion

LncRNA SNHG12 facilitated the immune escape of NSCLC by binding to HuR and increasing PD-L1 and USP8 levels.

LncRNA NEAT1 ameliorate ischemic stroke via promoting Mfn2 expression through binding to Nova and activates Sirt3

BACKGROUND

Recent studies revealed that long non-coding RNAs (lncRNAs) have significant roles in regulating the pathogenesis of ischemia stroke, and oxygen-glucose deprivation/reoxygenation (OGD/R)-induced cell apoptosis. Aberrant expression of NEAT1 was found after the injury of ischemia-reperfusion, but the mechanism was not fully understood.

METHODS

The expression of NEAT1 and Mfn2 were detected in BV-2 and N2a cell with or without OGD/R-induced by qRT-PCR. Inflammatory cytokines secretion was detected by enzyme-linked immunosorbent assay (ELISA). The oxidative stress was evaluated by the examination of ROS, MDA and SOD levels. Flow cytometry and apoptosis marker detection by western blot were performed to examined apoptosis.

RESULTS

The expression of NEAT1 and Mfn2 were decreased in OGD/R-induced cell model. Overexpression of NEAT1 or Mfn2 reduced oxidative stress and apoptosis by OGD/R-induced in neuronal cells, while knockdown of Sirt3 reversed the protective effect of NEAT1 and Mfn2. NEAT1 stabilized Mfn2 mRNA via recruiting Nova. NEAT1 alleviates the oxidative stress and apoptosis by OGD/R-induced via activating Sirt3.

CONCLUSION

LncRNA NEAT1 stabilizes Mfn2 mRNA via recruiting Nova, therefore increase the expression of Mfn2 and alleviates ischemia-reperfusion induced oxidative stress and apoptosis via Mfn2/Sirt3 pathway.

Molecular Subtypes and Prognostic Signature of Pyroptosis-Related lncRNAs in Glioma Patients

The relationship between pyroptosis-related long non-coding RNAs (pyroptosis-related lncRNAs) and glioma prognosis have not been studied clearly. Basing on The Cancer Genome Atlas and The Chinese Glioma Genome Atlas datasets, we firstly identified 23 pyroptosis-related lncRNAs with Pearson coefficient |r| > 0.5 and p < 0.001. The survival probability was lower in cluster 1. 13 lncRNAs was included into signature and divided all the glioma patients into two groups, among which survival probability of the high-risk group was lower than that in low-risk group (P<0.001). The risk score was higher in the age>60, dead grade 3, cluster 1 and immune score high groups. Furthermore, subgroup analysis showed patients with different grades, IDH and 1p19ql state distinguished by the median of risk score had different survival probability. Risk score was one of independent factors for glioma prognosis, and 1-, 3-, 5-years survival were calculated in nomogram. Meanwhile, the same as the median risk score in TCGA cohort, the glioma patients from CGGA were categorized into two groups and validated the outcome mentioned above(P<0.01). GO and KEGG analysis revealed the immunity process of the targeted genes. Thus, the immune filtration we compared showed naive B cell, resting dendritic cells, activated NK cells, activated Mast cells, monocytes are higher in low-risk group. Moreover, level of the activated NK cells, M0-and M1 Macrophages was in positive relationship with the risk score. Besides, competing endogenous RNA (ceRNA) network display interaction among microRNA, lncRNAs and their targeted genes. Pyroptosis-related lncRNAs could be a dependent prognosis factor and maybe linked to the immune response in glioma. This prognosis signature had potential value in estimate the survival of the patients with glioma.

Non-Coding RNAs and Brain Tumors: Insights Into Their Roles in Apoptosis

A major terrifying ailment afflicting the humans throughout the world is brain tumor, which causes a lot of mortality among pediatric and adult solid tumors. Several major barriers to the treatment and diagnosis of the brain tumors are the specific micro-environmental and cell-intrinsic features of neural tissues. Absence of the nutrients and hypoxia trigger the cells' mortality in the core of the tumors of humans' brains: however, type of the cells' mortality, including apoptosis or necrosis, has been not found obviously. Current studies have emphasized the non-coding RNAs (ncRNAs) since their crucial impacts on carcinogenesis have been discovered. Several investigations suggest the essential contribution of such molecules in the development of brain tumors and the respective roles in apoptosis. Herein, we summarize the apoptosis-related non-coding RNAs in brain tumors.

LncRNA SNHG12 in extracellular vesicles derived from carcinoma-associated fibroblasts promotes cisplatin resistance in non-small cell lung cancer cells

Non-small-cell lung cancer (NSCLC) is defined as the most universally diagnosed class of lung cancer. Cisplatin (DDP) is an effective drug for NSCLC, but tumors are prone to drug resistance. The current study set out to evaluate the regulatory effect of long non-coding RNA (lncRNA) small nucleolar RNA host gene 12 (SNHG12) in extracellular vesicles (EVs) derived from carcinoma-associated fibroblasts (CAFs) on DDP resistance in NSCLC cells. Firstly, NSCLC cells were treated with EVs, followed by detection of cell activity, IC50 values, cell proliferation and apoptosis, and Cy3-SNHG12. We observed that CAFs-EVs promoted IC50 values and cell proliferation and inhibited apoptosis. In addition, we learned that lncRNA SNHG12 carried by CAFs-EVs into NSCLC facilitated DDP resistance of NSCLC cells. Furthermore, ELAV like RNA binding protein 1 (HuR/ELAVL1) binding to lncRNA SNHG12 and X-linked inhibitor of apoptosis (XIAP) was verified and RNA stability of XIAP was also verified CAFs-EVs promoted RNA stability and transcription of XIAP, while silencing HuR could partially-reverse this promoting effect. Further joint experimentation showed that silencing XIAP partially inhibited DDP resistance in NSCLC cells. Additionally, the tumor growth and the positive rate of Ki67 and HuR were detected, which showed that CAFs-oe-EVs promoted the tumor and the positive rate of Ki67, as well as the levels of lncRNA SNHG12, HuR, and XIAP in vivo. Collectively, our findings indicated that lncRNA SNHG12 carried by CAFs-EVs into NSCLC cells promoted RNA stability and XIAP transcription by binding to HuR, thus augmenting DDP resistance in NSCLC cells.

miR-140-3p is involved in the occurrence and metastasis of gastric cancer by regulating the stability of FAM83B

Background

Gastric cancer (GC) is a malignant tumor and microRNAs (miRNAs) are closely connected to GC development. The purpose of this study is to investigate the effect of miR-140-3p on the occurrence and metastasis of GC.

Methods

We detected miR-140-3p expression in GC cells and tissues. The correlation between miR-140-3p and prognosis and clinicopathological features in GC was analyzed. The role of miR-140-3p in GC cell migration, invasion, and proliferation was analyzed. The model of tumor transplantation and metastasis in nude mice was established, and the effect of miR-140-3p on the development and metastasis of GC was assessed. The relation between miR-140-3p and SNHG12 and the relations among HuR, SNHG12, and FAM83B were analyzed.

Results

miR-140-3p was poorly expressed in GC. GC patients with low miR-140-3p expression had a poor prognosis and unfavorable clinicopathologic features. Overexpression of miR-140-3p inhibited GC cell migration, invasion, and proliferation, and inhibited the development and metastasis of GC. miR-140-3p directly bound to SNHG12 in GC tissues and downregulated SNHG12 expression. SNHG12 overexpression induced HuR nuclear transportation. HuR can bind to FAM83B and up-regulate the mRNA level of FAM83B. Overexpression of SNHG12 or FAM83B reduced the inhibition of overexpression of miR-140-3p on GC.

Conclusion

miR-140-3p directly bound to SNHG12 in GC and down-regulated the expression of SNHG12, reduced the binding of SNHG12 and HuR, thus inhibiting the nuclear transportation of HuR and the binding of HuR and FAM83B, and reducing the transcription of FAM83B, and finally inhibiting the growth and metastasis of GC.

Apatinib inhibits cell proliferation and migration of osteosarcoma via activating LINC00261/miR-620/PTEN axis

Apatinib has been recently identified as a potential treatment option for osteosarcoma (OS). Nonetheless, the molecular mechanism of Apatinib in regulating OS progression remains unclear. To explore the downstream molecules that mediated the tumor-suppressive effect of Apatinib on OS. Expression levels of genes were detected by RT-qPCR and western blot assays. Functional assays including Transwell assay were applied to detect the proliferation, apoptosis and migration of OS cells. Molecular interactions were detected by luciferase reporter assay and RIP assay. Apatinib inhibited the proliferation and migration of OS cells. LINC00261 was down-regulated in OS cells but then up-regulated after the treatment by Apatinib. Silencing LINC00261 abrogated the suppressive effect of Apatinib on OS cell proliferation and migration. MicroRNA-620 (miR-620) could be sponged by LINC00261. Besides, miR-620 was up-regulated in OS cells and Apatinib treatment reduced miR-620 expression. Furthermore, LINC00261 acted as a competitive endogenous RNA (ceRNA) by sequestering miR-620 to up-regulate the expression of phosphatase and tensin homolog (PTEN). Moreover, Apatinib hindered in vitro cell proliferation and migration as well as the in vivo tumorigenesis of OS through LINC00261/miR-620/PTEN axis. Apatinib-enhanced LINC00261 restrained OS via miR-620/PTEN axis, indicating LINC00261 might promote the efficacy of Apatinib on OS.

Long noncoding RNA SNHG12 is a potential diagnostic and prognostic biomarker in various tumors

BACKGROUND

Tumors are the second most common cause of death in humans worldwide, second only to cardiovascular and cerebrovascular diseases. Although methods and techniques for the treatment of tumors continue to improve, the effect is not satisfactory. These may lack effective therapeutic targets. This study aimed to evaluate the value of SNHG12 as a biomarker in the prognosis and clinical characteristics of various cancer patients.

METHODS

We analyzed SNHG12 expression and plotted the survival curves of all cancer samples in the TCGA database using the GEPIA tool. Then, we searched for eligible papers up to April 1, 2019, in databases. Next, the data were extracted from studies examining SNHG12 expression, overall survival and clinicopathological features in patients with malignant tumors. We used Review Manager 5.3 and Stata 15 software to analyze the statistical data.

RESULTS

In the TCGA database, abnormally high expression of SNHG12 in tumor samples indicates that the patient has a poor prognosis. Results of meta-analysis is that SNHG12 high expression is related to low overall survival (HR = 2.72, 95% CI = 1.95-3.8, P < 0.00001), high tumor stage (OR = 3.94, 95% CI = 2.80-5.53, P < 0.00001), high grade (OR = 2.04, 95% CI = 1.18-3.51, P = 0.01), distant metastasis (OR = 2.20, 95% CI = 1.40-3.46, P = 0.0006), tumor size (OR = 2.79, 95% CI = 1.89-4.14, P < 0.00001), and lymph node metastasis (OR = 2.66, 95% CI = 1.65-4.29, P < 0.0001).

CONCLUSIONS

Our study confirmed that the high expression level of SNHG12 is closely related to the clinicopathological characteristics and prognosis of patients and is a new predictive biomarker for various cancer patients.

Long noncoding RNA SNHG12 promotes the proliferation, migration, and invasion of trophoblast cells by regulating the epithelial-mesenchymal transition and cell cycle

Objective

The deficient placental blood perfusion caused by the attenuated infiltration of trophoblast cells is a key factor in the occurrence of preeclampsia (PE). Furthermore, the long noncoding (lnc)RNA SNHG12 (small nucleolar RNA host gene 12) can promote the proliferation and metastasis of multiple tumor cells. However, whether lncRNA SNHG12 affects proliferation and metastasis of trophoblast cells is unclear.

Methods

We examined the level of lncRNA SNHG12 in plasma and placenta of patients with PE and constructed trophoblast cells with overexpressed or knocked down SNHG12. CCK-8, wound healing, and Transwell assays were used to detect alterations in proliferation, migration, and invasion of trophoblast cells. Western blotting was used to detect proteins related to the epithelial–mesenchymal transition (EMT), and cell cycle assays clarified cell cycle distribution.

Results

LncRNA SNHG12 promoted the proliferation, migration, and invasion of trophoblast cells. The expression of matrix metalloproteinase-2 (MMP-2) and MMP-9, β-catenin, and vimentin were positively correlated with SNHG12, and expression of E-cadherin was negatively correlated with SNHG12. SNHG12 also promoted the transition of trophoblast cells from G₀/G₁ to S phase.

Conclusion

Overall, lncRNA SNHG12 promoted the migration and invasion of trophoblast cells by inducing the progression of EMT.

Long Noncoding RNA SNHG12 Promotes Prostate Tumor Occurrence and Progression via AKT Regulation

The small nucleolar RNA host gene 12 (SNHG12) has been reported to play an important role in the tumorigenesis and progression of PCa, but the functional underlying mechanism has not been studied clearly. We detected the expression level of SNHG12 in PCa tissues and matched adjacent normal tissues that were collected from 85 patients. Then, colony formation assays, MTT experiments, and flow cytometry were used to examine the effect of SNHG12 on proliferation, cell cycle distribution, and apoptosis of DU145 cells. Further, Transwell invasion assay was utilized to assess whether SNHG12 participates in PCa cell invasion and affects the secretion of VEGF secretion in DU145 cells. Finally, we investigated the effect of SNHG12 on tumor growth in vivo. We found that SNHG12 promoted cell proliferation and suppressed apoptosis in PCa cells, which suggests that SNHG12 is probably a novel PCa biomarker and therapy target of PCa.

Prognostic Value of Long Noncoding RNA SNHG12 in Various Carcinomas: A Meta-Analysis

Background

Numerous recent studies suggested that overexpression of the long noncoding RNA small nucleolar RNA host gene 12 (SNHG12) exhibited prooncogenic activity in multiple cancers. However, results regarding the prognostic value of SNHG12 in cancers still remained controversial. Therefore, we conducted a meta-analysis complemented with bioinformatics analysis to elucidate the clinical significance of SNHG12 in cancer patients.

Methods

PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang, and Weipu databases were searched for eligible studies until July 2020. Additionally, bioinformatics analysis was applied to verify the results of meta-analysis.

Results

Twenty-three related studies consisting of 1389 cancer patients were enrolled in the current meta-analysis. Elevated SNHG12 expression was found to be significantly associated with poor overall survival (OS) (HR = 1.81; 95% CI: 1.53-2.13; P < 0.001) and disease-free survival (DFS) (HR = 1.40; 95% CI: 1.12-1.76; P = 0.004) in multiple cancers, which were also verified by the results of bioinformatics analysis. Moreover, overexpression of SNHG12 was also related to clinicopathological characteristics including LNM, distant metastasis, high clinical stage, large tumor size, and poor tumor differentiation in diverse types of cancers.

Conclusion

The present findings indicated that SNHG12 might act as a novel biomarker for diagnosis or prognosis in human cancers.

Prognostic and clinical significance of long non-coding RNA SNHG12 expression in various cancers

Recently, increasing studies suggested that lncRNA SNHG12 was aberrantly expressed in kinds of cancers. However, definite prognostic value of SNHG12 remains unclear. We conducted this meta-analysis to evaluate the association between SNHG12 expression level and cancer prognosis. A literature retrieval was conducted by searching kinds of databases. The meta-analysis was performed by using Revman 5.2 and Stata 12.0 software. Besides, The Cancer Genome Atlas dataset was analyzed to validate the results in our meta-analysis via using Gene Expression Profiling Interactive Analysis. The pooled results showed that high SNHG12 expression significantly indicated worse overall survival and recurrence-free survival. Tumor type, sample size, survival analysis method, and cutoff value did not alter SNHG12 prognosis value according to stratified analysis results. Additionally, higher expression of SNHG12 suggested unfavorable clinicopathological outcomes including larger tumor size, lymph node metastasis, distant metastasis, and advanced clinical stage. Online cross-validation in TCGA dataset further indicated that cancer patients with upregulated SNHG12 expression had worse overall survival and disease-free survival. Therefore, elevated SNHG12 expression was associated with poor survival and unfavorable clinical outcomes in various cancers, and therefore might be a potential prognostic biomarker in human cancers.

Abbreviations Akt: protein kinase B; CESC: cervical squamous cell carcinoma and endocervical adenocarcinoma; ceRNA: competitive endogenous RNA; CNKI: China National Knowledge Infrastructure; CI: confidence interval; CCNE1: cyclin E1; COAD: colon adenocarcinoma; DM: distant metastasis; DFS: disease-free survival; EMT: epithelial–mesenchymal transition; FISH: fluorescence in situ hybridization; FIGO: the International Federation of Gynecology and Obstetrics; GEPIA: Gene Expression Profiling Interactive Analysis; HR: hazard ratio; HIFα: hypoxia-inducible factor 1 α; KIRC: kidney renal clear cell carcinoma; KIRP: kidney renal papillary cell carcinoma; LIHC: hepatocellular carcinoma; LNM: lymph node metastasis; mTOR: mechanistic target of rapamycin kinase; MMP-9: matrix metalloproteinase 9; MCL1: myeloid cell leukemia 1; MLK3: mixed-lineage protein kinase 3; N/A: not available; NOS: Newcastle-Ottawa Scale; OR: odd ratio; OS: overall survival; PSA: prostate-specific antigen; PI3K: phosphoinositide 3-kinase; qRT-PCR: quantitative real-time polymerase chain reaction; READ: rectum adenocarcinoma; RFS: recurrence-free survival; SARC: sarcoma; SNHG12: small nucleolar RNA host gene 12; STAT3: signal transducer and activator of transcription 3; SOX4: SRY-box transcription factor 4; SOX5: SRY-box transcription factor 5; STAD: stomach adenocarcinoma; TCGA: The Cancer Genome Atlas; TNM: tumor node metastasis; WWP1: WW domain-containing E3 ubiquitin protein ligase 1; WHO grade: World Health Organization grade; ZEB2: zinc finger E-box-binding homeobox 2

Long non-coding RNA SNHG12 promotes immune escape of ovarian cancer cells through their crosstalk with M2 macrophages

Accumulating evidence shows that the tumor microenvironment contributes to this phenomenon and that long non-coding RNAs (lncRNAs) are also involved in this process. In this study, we identified a new lncRNA small nucleolar RNA host gene 12 (SNHG12) and investigated its role in tumor immune escape. We analyzed the expression levels of interlukin (IL)-6R and programmed death-ligand 1 (PD-L1) in 51 ovarian cancer and 20 normal specimens by immunohistochemistry. The correlation between SNHG12 and IL-6R in clinical ovarian cancer samples was identified by RT-qPCR. We then performed SNHG12 gain- and loss-function experiments in order to investigate its role in the regulation of immune escape and the crosstalk between miR-21 and IL-6. T cell proliferation was assessed by flow cytometry. In vivo pro-immune escape activity of SNHG12 was assessed by tumor-xenograft mouse model. IL-6R and PD-L1 were found to be overexpressed in clinical ovarian cancer specimens. Meanwhile, SNHG12 and IL-6R expressions were positively correlated in clinical ovarian cancer samples. SNHG12 facilitated ovarian immune escape by promoting IL-6/miR-21 crosstalk between ovarian cancer cells and M2 macrophages. Notably, SNHG12 promoted IL-6R transcription by recruiting NF-κB1 to the IL-6R promoter. Our study reveals that SNHG12 facilitates ovarian cancer immune escape by upregulating IL-6R.

Long Noncoding RNA FGD5-AS1 Promotes Glioma Cell Proliferation, Migration and Invasion by Regulating wnt/β-Catenin Pathway

Purpose

To investigate the specific function of long noncoding RNA FGD5 antisense RNA 1 (lncRNA FGD5-AS1) in glioma.

Materials and Methods

The level of FGD5-AS1 was detected in clinical samples and cell lines by qRT-PCR. Small interfering RNA (siRNA) of FGD5-AS1 or scramble siRNA was transfected into U87 cell lines to examine the role of FGD5-AS1 on glioma development. The proliferation of glioma cells was tested by Cell Counting Kit-8 (CCK-8), the migration and invasion of glioma cells were tested by transwell assay without matrigel or with matrigel. Western blot was used to detect the protein expression, and XAV-939 was used to inhibit wnt/β-catenin pathway. The effect of FGD5-AS1 on tumorigenesis of glioma was confirmed by xenograft nude mice model.

Results

FGD5-AS1 was significantly increased in glioma tissues and cells. Loss of FGD5-AS1 inhibited the proliferation, migration and invasion of U87 cells. Furthermore, overexpression of FGD5-AS1 increased the mRNA and protein levels of β-catenin and cyclin D1. Blocking of wnt/β-catenin using XAV-939 reversed the promotion role of FGD3-AS1 on glioma cells’ migration and invasion. The in vivo tumor growth assay showed that FGD3-AS1 accelerated glioma tumorigenesis with activating wnt/β-catenin pathway.

Conclusion

Our research emphasized FGD5-AS1 acting as an oncogene by regulating wnt/β-catenin signaling pathway, thus providing some novel experimental basis for clinical treatment of glioma.

RNA-Binding Proteins as Important Regulators of Long Non-Coding RNAs in Cancer

The majority of the genome is transcribed into pieces of non-(protein) coding RNA, among which long non-coding RNAs (lncRNAs) constitute a large group of particularly versatile molecules that govern basic cellular processes including transcription, splicing, RNA stability, and translation. The frequent deregulation of numerous lncRNAs in cancer is known to contribute to virtually all hallmarks of cancer. An important regulatory mechanism of lncRNAs is the post-transcriptional regulation mediated by RNA-binding proteins (RBPs). So far, however, only a small number of known cancer-associated lncRNAs have been found to be regulated by the interaction with RBPs like human antigen R (HuR), ARE/poly(U)-binding/degradation factor 1 (AUF1), insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), and tristetraprolin (TTP). These RBPs regulate, by various means, two aspects in particular, namely the stability and the localization of lncRNAs. Importantly, these RBPs themselves are commonly deregulated in cancer and might thus play a major role in the deregulation of cancer-related lncRNAs. There are, however, still many open questions, for example regarding the context specificity of these regulatory mechanisms that, in part, is based on the synergistic or competitive interaction between different RBPs. There is also a lack of knowledge on how RBPs facilitate the transport of lncRNAs between different cellular compartments.

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.

Noninvasive quantification of SIRT1 expression-activity and pharmacologic inhibition in a rat model of intracerebral glioma using 2-[18F]BzAHA PET/CT/MRI

Background

Several studies demonstrated that glioblastoma multiforme progression and recurrence is linked to epigenetic regulatory mechanisms. Sirtuin 1 (SIRT1) plays an important role in glioma progression, invasion, and treatment response and is a potential therapeutic target. The aim of this study is to test the feasibility of 2-[¹⁸F]BzAHA for quantitative imaging of SIRT1 expression–activity and monitoring pharmacologic inhibition in a rat model of intracerebral glioma.

Methods

Sprague Dawley rats bearing 9L (N = 12) intracerebral gliomas were injected with 2-[¹⁸F]BzAHA (300–500 µCi/animal i.v.) and dynamic positron-emission tomography (PET) imaging was performed for 60 min. Then, SIRT1 expression in 9L tumors (N = 6) was studied by immunofluorescence microscopy (IF). Two days later, rats with 9L gliomas were treated either with SIRT1 specific inhibitor EX-527 (5 mg/kg, i.p.; N = 3) or with histone deacetylases class IIa specific inhibitor MC1568 (30 mg/kg, i.p.; N = 3) and 30 min later were injected i.v. with 2-[¹⁸F]BzAHA. PET-computerized tomography-magnetic resonance (PET/CT/MR) images acquired after EX-527 and MC1568 treatments were co-registered with baseline images.

Results

Standard uptake values (SUVs) of 2-[¹⁸F]BzAHA in 9L tumors measured at 20 min post-radiotracer administration were 1.11 ± 0.058 and had a tumor-to-brainstem SUV ratio of 2.73 ± 0.141. IF of 9L gliomas revealed heterogeneous upregulation of SIRT1, especially in hypoxic and peri-necrotic regions. Significant reduction in 2-[¹⁸F]BzAHA SUV and distribution volume in 9L tumors was observed after administration of EX-527, but not MC1568.

Conclusions

PET/CT/MRI with 2-[¹⁸F]BzAHA can facilitate studies to elucidate the roles of SIRT1 in gliomagenesis and progression, as well as to optimize therapeutic doses of novel SIRT1 inhibitors.

Role of linc00174/miR-138-5p (miR-150-5p)/FOSL2 Feedback Loop on Regulating the Blood-Tumor Barrier Permeability

The blood-tumor barrier (BTB) limits the transport of chemotherapeutic drugs to brain tumor tissues and impacts the treatment of glioma. Long non-coding RNAs play critical roles in various biological processes of tumors; however, the function of these in BTB permeability is still unclear. In this study, we have identified that long intergenic non-protein coding RNA 174 (linc00174) was upregulated in glioma endothelial cells (GECs) from glioma tissues. Additionally, linc00174 was also upregulated in GECs from the BTB model in vitro. Knock down of linc00174 increased BTB permeability and reduced the expression of the tight junction-related proteins ZO-1, occludin, and claudin-5. Both bioinformatics data and results of luciferase reporter assays demonstrated that linc00174 regulated BTB permeability by binding to miR-138-5p and miR-150-5p. Furthermore, knock down of linc00174 inhibited FOSL2 expression via upregulating miR-138-5p and miR-150-5p. FOSL2 interacted with the promoter regions and upregulated the promoter activity of ZO-1, occludin, claudin-5, and linc00174 in GECs. In conclusion, the present study demonstrated that the linc00174/miR-138-5p (miR-150-5p)/FOSL2 feedback loop played an essential role in regulating BTB permeability.

SNHG12: An LncRNA as a Potential Therapeutic Target and Biomarker for Human Cancer

Limitations in current diagnostic procedures warrant identification of new methodologies to improve diagnoses of cancer patients. In this context, long non-coding RNAs (lncRNAs) have emerged as stable biomarkers which are expressed abundantly in tumors. Importantly, these can be detected at all stages of tumor development, and thus may provide potential biomarkers and/or therapeutic targets. Recently, we suggested that aberrant levels of lncRNAs can be used to determine the invasive and metastatic potential of tumor cells. Further, direct correlations of lncRNAs with cancer-derived inflammation, metastasis, epithelial-to-mesenchymal transition, and other hallmarks of cancer indicate their potential as biomarkers and targets for cancer. Thus, in this review we have discussed the importance of small nucleolar RNA host gene 12 (SNHG12), a lncRNA, as a potential biomarker for a variety of cancers. A meta-analysis of a large cohort of cancer patients revealed that SNHG12 may also serve as a potential target for cancer-directed interventions due to its involvement in unfolded protein responses, which many tumor cells exploit to both evade immune-mediated attack and enhance the polarization of effector immune cells (e.g., macrophages and T cells). Thus, we propose that SNHG12 may serve as both a biomarker and a druggable therapeutic target with promising clinical potential.

RNA processing genes characterize RNA splicing and further stratify lower-grade glioma

BACKGROUND

Aberrant expression of RNA processing genes may drive the alterative RNA profile in lower-grade gliomas (LGGs). Thus, we aimed to further stratify LGGs based on the expression of RNA processing genes.

METHODS

This study included 446 LGGs from The Cancer Genome Atlas (TCGA, training set) and 171 LGGs from the Chinese Glioma Genome Atlas (CGGA, validation set). The least absolute shrinkage and selection operator (LASSO) Cox regression algorithm was conducted to develop a risk-signature. The receiver operating characteristic (ROC) curves and Kaplan-Meier curves were used to study the prognosis value of the risk-signature.

RESULTS

Among the tested 784 RNA processing genes, 276 were significantly correlated with the OS of LGGs. Further LASSO Cox regression identified a 19-gene risk-signature, whose risk score was also an independently prognosis factor (P<0.0001, multiplex Cox regression) in the validation dataset. The signature had better prognostic value than the traditional factors "age", "grade" and "WHO 2016 classification" for 3- and 5-year survival both two datasets (AUCs > 85%). Importantly, the risk-signature could further stratify the survival of LGGs in specific subgroups of WHO 2016 classification. Furthermore, alternative splicing events for genes such as EGFR and FGFR were found to be associated with the risk score. mRNA expression levels for genes, which participated in cell proliferation and other processes, were significantly correlated to the risk score.

CONCLUSIONS

Our results highlight the role of RNA processing genes for further stratifying the survival of patients with LGGs and provide insight into the alternative splicing events underlying this role.

Small Nucleolar RNA Host Gene 12 (SNHG12) Promotes Proliferation and Invasion of Laryngeal Cancer Cells via Sponging miR-129-5p and Potentiating WW Domain-Containing E3 Ubiquitin Protein Ligase 1 (WWP1) Expression

Background

The clinical significance and biological function of long noncoding RNA SNHG12 have not been identified in laryngeal squamous cell carcinoma (LSCC).

Material/Methods

Expression levels of SNHG12, miR-129-5p, and WWP1 in LSCC tissues or cells were tested by RT-qPCR. MTT assay, flow cytometry, and Transwell assay were used to identify the progression of LSCC cells in vitro. Luciferase reporter assay was used to assess the associations among SNHG12, WWP1, and miR-129-5p.

Results

SNHG12 was significantly overexpressed in LSCC tissues compared with adjacent normal tissues. The expression level of SNHG12 was significantly associated with T classification, lymph node metastasis, and cancer stage of LSCC. High expression of SNHG12 predicted shorter disease-free survival. Suppressing SNHG12 using siRNA inhibited proliferation and invasion and promoted apoptosis in the AMC-HN-8 LSCC cell line. SNHG12, mainly located in cytoplasm of AMC-HN-8 cells, was validated by dual luciferase reporter test and RT-qPCR to directly interact with miR-129-5p. Inhibition of miR-129-5p significantly increased proliferation and invasion of AMC-HN-8 cells and ameliorated the suppressive effects of si-SNHG12. Luciferase assay showed that miR-129-5p was able to combine with the 3′UTR region of WWP1, which is generally regarded as an E3 ubiquitin protein ligase. RT-qPCR and Western blot showed that WWP1 was positively regulated by SNHG12 and negatively regulated by miR-129-5p at the mRNA level and protein level. Overexpression of WWP1 significantly increased proliferation and invasion of laryngeal cancer cells. Moreover, when SNHG12 was suppressed, rescue of WWP1 restored the proliferation and invasion abilities of AMC-HN-8 cells.

Conclusions

Our study demonstrated that SNHG12 promoted LSCC cells progression via sponging miR-129-5p and potentiating WWP1 expression.

Long non-coding RNA SNHG12 promotes proliferation and invasion of colorectal cancer cells by acting as a molecular sponge of microRNA-16

Long non-coding (lnc)RNA small nucleolar RNA host gene 12 (SNHG12) has an oncogenic role in various common human cancer types, including colorectal cancer (CRC). However, the detailed regulatory mechanisms of SNHG12 in CRC cells have remained largely elusive, and the investigation thereof was the purpose of the present study. Polymerase chain reaction analysis was performed to examine the expression of lncRNA and microRNA (miR). Cell Counting Kit-8 and Transwell assays were used to assess cell proliferation and invasion. A luciferase reporter assay was performed to confirm a predicted targeting association between lncRNA and miR. It was observed that SNHG12 was markedly upregulated in CRC tissues when compared with that in adjacent non-tumour tissues, and its high expression was associated with CRC progression, as well as poor prognosis of patients. In addition, the expression of SNHG12 was higher in CRC cell lines when compared with that in a normal intestinal epithelial cell line. Knockdown of SNHG12 significantly inhibited CRC cell proliferation and invasion, while ectopic overexpression of SNHG12 had the opposite effect. A Bioinformatics analysis predicted that SNHG12 and miR-16 have complementary binding sites, which was confirmed by a luciferase reporter gene assay. The expression levels of miR-16 were markedly decreased in CRC tissues and cell lines compared with those in normal tissues or cells, and were inversely correlated with the expression levels of SNHG12 in CRC tissues. Furthermore, silencing of miR-16 eliminated the suppressive effects of SNHG12 knockdown on CRC cell proliferation and invasion. In conclusion, the present study demonstrated that SNHG12 promotes CRC cell proliferation and invasion, at least in part, by acting as a molecular sponge of miR-16, suggesting that SNHG12 may be a promising therapeutic target for CRC.

Current approaches for RNA-labelling to identify RNA-binding proteins

RNA is involved in all domains of life, playing critical roles in a host of gene expression processes, host-defense mechanisms, cell proliferation, and diseases. A critical component in many of these events is the ability for RNA to interact with proteins. Over the past few decades, our understanding of such RNA-protein interactions and their importance has driven the search and development of new techniques for the identification of RNA-binding proteins. In determining which proteins bind to the RNA of interest, it is often useful to use the approach where the RNA molecule is the "bait" and allow it to capture proteins from a lysate or other relevant solution. Here, we review a collection of methods for modifying RNA to capture RNA-binding proteins. These include small-molecule modification, the addition of aptamers, DNA-anchoring, and nucleotide substitution. With each, we provide examples of their application, as well as highlight their advantages and potential challenges.

CDK5 suppresses the metastasis of gastric cancer cells by interacting with and regulating PP2A

Several previous studies have demonstrated that cyclin‑dependent kinase (CDK)‑5 expression serves an important role in promoting the development of malignant tumours. We have previously reported that CDK5 suppresses gastric tumourigenesis. The aim of the present study was to investigate the mechanistic basis of CDK5. The results of immunoprecipitation and western blot analysis demonstrated that CDK5 could interact with serine/threonine‑protein phosphatase 2A (PP2A). The use of an inhibitor of PP2A in CDK5‑overexpressing gastric cancer (GC) cell lines antagonized CDK5‑mediated suppression in GC cells. Further analysis revealed that PP2A expression was downregulated in GC and patients with low levels of PP2A had worse survival outcomes than those with high levels of PP2A (P=0.035). Therefore, the present study provided a novel mechanism for CDK5‑mediated tumour suppression, suggesting that CDK5 may be an attractive target for future therapeutic strategies for treating GC. In addition, low levels of PP2A may indicate a tendency for poor prognosis in patients with GC.