A Novel LncRNA, AC091729.7 Promotes Sinonasal Squamous Cell Carcinomas Proliferation and Invasion Through Binding SRSF2

The nexus of long noncoding RNAs, splicing factors, alternative splicing and their modulations

The process of alternative splicing (AS) is widely deregulated in a variety of cancers. Splicing is dependent upon splicing factors. Recently, several long noncoding RNAs (lncRNAs) have been shown to regulate AS by directly/indirectly interacting with splicing factors. This review focuses on the regulation of AS by lncRNAs through their interaction with splicing factors. AS mis-regulation caused by either mutation in splicing factors or deregulated expression of splicing factors and lncRNAs has been shown to be involved in cancer development and progression, making aberrant splicing, splicing factors and lncRNA suitable targets for cancer therapy. This review also addresses some of the current approaches used to target AS, splicing factors and lncRNAs. Finally, we discuss research challenges, some of the unanswered questions in the field and provide recommendations to advance understanding of the nexus of lncRNAs, AS and splicing factors in cancer.

Towards understandings of serine/arginine-rich splicing factors

Serine/arginine-rich splicing factors (SRSFs) refer to twelve RNA-binding proteins which regulate splice site recognition and spliceosome assembly during precursor messenger RNA splicing. SRSFs also participate in other RNA metabolic events, such as transcription, translation and nonsense-mediated decay, during their shuttling between nucleus and cytoplasm, making them indispensable for genome diversity and cellular activity. Of note, aberrant SRSF expression and/or mutations elicit fallacies in gene splicing, leading to the generation of pathogenic gene and protein isoforms, which highlights the therapeutic potential of targeting SRSF to treat diseases. In this review, we updated current understanding of SRSF structures and functions in RNA metabolism. Next, we analyzed SRSF-induced aberrant gene expression and their pathogenic outcomes in cancers and non-tumor diseases. The development of some well-characterized SRSF inhibitors was discussed in detail. We hope this review will contribute to future studies of SRSF functions and drug development targeting SRSFs.

Insights into established and emerging roles of SR protein family in plants and animals

Splicing of pre-mRNA is an essential part of eukaryotic gene expression. Serine-/arginine-rich (SR) proteins are highly conserved RNA-binding proteins present in all metazoans and plants. SR proteins are involved in constitutive and alternative splicing, thereby regulating the transcriptome and proteome diversity in the organism. In addition to their role in splicing, SR proteins are also involved in mRNA export, nonsense-mediated mRNA decay, mRNA stability, and translation. Due to their pivotal roles in mRNA metabolism, SR proteins play essential roles in normal growth and development. Hence, any misregulation of this set of proteins causes developmental defects in both plants and animals. SR proteins from the animal kingdom are extensively studied for their canonical and noncanonical functions. Compared with the animal kingdom, plant genomes harbor more SR protein-encoding genes and greater diversity of SR proteins, which are probably evolved for plant-specific functions. Evidence from both plants and animals confirms the essential role of SR proteins as regulators of gene expression influencing cellular processes, developmental stages, and disease conditions. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.

Long Non-Coding RNA DUXAP8 Acts as an Oncogene in Sinonasal Squamous Cell Carcinoma Through miR-584-5p/FNDC3B Pathway

Sinonasal squamous cell carcinoma (SNSCC) is one of the least frequent carcinomas in the head and neck and accounts for 60% to 75% of sinonasal malignancies. The role of long non-coding RNAs (lncRNAs) in cancer development has drawn great attention over the years. The current study intended to assess the role and specific mechanism of lncRNA double homeobox A pseudogene 8 (DUXAP8) in SNSCC. Quantitative real-time PCR (qRT-PCR) analysis was implemented to assess the expression level of DUXAP8, microRNA-584-5p (miR-584-5p), and fibronectin type III domain containing 3B (FNDC3B). Proliferation assays included colony formation assay, Cell Counting Kit-8 (CCK-8) assay, and 5-ethynyl-2′-deoxyuridine (EdU) assay. Transwell assays were implemented to monitor cell migration and invasion. Cell apoptosis was evaluated via terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) and JC-1 experiments. Mechanism experiments included RNA pull-down assay, RNA binding protein immunoprecipitation (RIP) assay, and luciferase reporter assay. DUXAP8 is overexpressed in SNSCC cells. Functionally, DUXAP8 silencing suppresses the malignant progression of SNSCC. Furthermore, DUXAP8 up-regulates the expression of FNDC3B via sponging miR-584-5p. Rescue experiments demonstrated that DUXAP8 mediates the progression of SNSCC via up-regulating FNDC3B expression. In conclusion, DUXAP8 acts as an oncogene in SNSCC, which may be a new molecular marker for SNSCC.

Biomarkers in Otorhinolaryngology

Biomarkers of otorhinolaryngologic diseases with higher insult over a person’s him/herself and overall health services are summarized in brief. In order to define, diagnose, treat and monitor any disease markers are needed. Otorhinolaryngology (ORL) is interested in special disease entities of the region besides otorhinolaryngologic involvements of the systemic diseases and unique forms of pathologies such as cholesteatoma, Meniere’s disease and otosclerosis. Neoplasia is another heading to deal with. In the following chapter, one will find an overview of molecules that have been used as a biomarker as well as the end points of the present research on the issue relevant with ORL. Day by day, new molecules are being named however, the pathways of action are rather the same. Readers will find the headings related to the most common diseases of the field, informing them about where to look for defining new strategies of understanding of each disease.

Long Non-Coding RNA DUXAP8 Acts as an Oncogene in Sinonasal Squamous Cell Carcinoma Through miR-584-5p/FNDC3B Pathway

Sinonasal squamous cell carcinoma (SNSCC) is one of the least frequent carcinomas in the head and neck and accounts for 60% to 75% of sinonasal malignancies. The role of long non-coding RNAs (lncRNAs) in cancer development has drawn great attention over the years. The current study intended to assess the role and specific mechanism of lncRNA double homeobox A pseudogene 8 (DUXAP8) in SNSCC. Quantitative real-time PCR (qRT-PCR) analysis was implemented to assess the expression level of DUXAP8, microRNA-584-5p (miR-584-5p), and fibronectin type III domain containing 3B (FNDC3B). Proliferation assays included colony formation assay, Cell Counting Kit-8 (CCK-8) assay, and 5-ethynyl-2'-deoxyuridine (EdU) assay. Transwell assays were implemented to monitor cell migration and invasion. Cell apoptosis was evaluated via terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) and JC-1 experiments. Mechanism experiments included RNA pull-down assay, RNA binding protein immunoprecipitation (RIP) assay, and luciferase reporter assay. DUXAP8 is overexpressed in SNSCC cells. Functionally, DUXAP8 silencing suppresses the malignant progression of SNSCC. Furthermore, DUXAP8 up-regulates the expression of FNDC3B via sponging miR-584-5p. Rescue experiments demonstrated that DUXAP8 mediates the progression of SNSCC via up-regulating FNDC3B expression. In conclusion, DUXAP8 acts as an oncogene in SNSCC, which may be a new molecular marker for SNSCC.

LncRNA MIAT Promotes Spinal Cord Injury Recovery in Rats by Regulating RBFOX2-Mediated Alternative Splicing of MCL-1

LncRNA myocardial infarction-associated transcript (MIAT) alleviates acute spinal cord injury (ASCI)-induced neuronal cell apoptosis, but the specific mechanism of it involved in regulating SCI progression needs further exploration. Here, a SCI rat model was established, followed by administration with adenovirus-mediated MIAT overexpression vector (Ad-MIAT) alone or together with Ad-RBFOX2 (RNA binding fox-1 homolog 2). The data indicated that MIAT overexpression promoted motor function recovery, improved morphology of injured tissues, and restrained neuron loss and cell apoptosis in SCI rats. Then, PC-12 cells were treated with H₂O₂ to induce cell injury. And highly expressed MIAT suppressed H₂O₂-caused decrease in cell viability and increase in cell apoptosis. MIAT stabilized RBFOX2 protein expression by binding to RBFOX2, thereby promoting RBFOX2-induced upregulation of anti-apoptotic MCL-1L (myeloid cell leukemia sequence 1) and reduction of pro-apoptotic MCL-1S. And silencing RBFOX2 in vitro blocked the inhibitory effect of MIAT on cell apoptosis. Moreover, MCL-1-specific steric-blocking oligonucleotides (SBOs) were used to transfer the MCL-1 pre-mRNA splicing pattern from MCL-1L to MCL-1S. SBOs reversed the protection effect of RBFOX2 overexpression on H₂O₂-induced cell injury. Furthermore, overexpression of MCL-1L instead of MCL-1S facilitated autophagy activation in H₂O₂-stimulated cells. Interestingly, co-overexpression of MIAT and RBFOX2 had a better promoting effect on SCI recovery. In conclusion, MIAT mitigated SCI by promoting RBFOX2-mediated alternative splicing of MCL-1. Our findings might provide a promising therapeutic target for SCI.

The role of long non-coding RNAs in the pathogenesis of head and neck squamous cell carcinoma

Head and neck cancers are a heterogeneous collection of malignancies of the upper aerodigestive tract, salivary glands, and thyroid. However, the molecular mechanisms underlying the carcinogenesis of head and neck squamous cell carcinomas (HNSCCs) remain poorly understood. Over the past decades, overwhelming evidence has demonstrated the regulatory roles of long non-coding RNAs (lncRNAs) in tumorigenesis, including HNSCC. Notably, these lncRNAs have vital roles in gene regulation and affect various aspects of cellular homeostasis, including proliferation, survival, and metastasis. They exert regulating functions by interacting with nucleic acids or proteins and affecting cancer cell signaling. LncRNAs represent a burgeoning field of cancer research, and we are only beginning to understand the importance and complicity of lncRNAs in HNSCC. In this review, we summarize the deregulation and function of lncRNAs in human HNSCC. We also review the working mechanism of lncRNAs in HNSCC pathogenesis and discuss the potential application of lncRNAs as diagnostic/prognostic tools and therapeutic targets in human HNSCC.

Downregulation of LNMAS orchestrates partial EMT and immune escape from macrophage phagocytosis to promote lymph node metastasis of cervical cancer

Epithelial-mesenchymal transition (EMT) is an essential step to drive the metastatic cascade to lymph nodes (LNs) in cervical cancer cells. However, few of them metastasize successfully partially due to increased susceptibility to immunosurveillance conferred by EMT. The precise mechanisms of cancer cells orchestrate EMT and immune evasion remain largely unexplored. In this study, we identified a lncRNA termed lymph node metastasis associated suppressor (LNMAS), which was downregulated in LN-positive cervical cancer patients and correlated with LN metastasis and prognosis. Functionally, LNMAS suppressed cervical cancer cells metastasis in vitro and in vivo. Mechanistically, LNMAS exerts its metastasis suppressive activity by competitively interacting with HMGB1 and abrogating the chromatin accessibility of TWIST1 and STC1, inhibiting TWIST1-mediated partial EMT and STC1-dependent immune escape from macrophage phagocytosis. We further demonstrated that the CpG sites in the promoter region of LNMAS was hypermethylated and contributed to the downregulation of LNMAS. Taken together, our results reveal the essential role of LNMAS in the LN metastasis of cervical cancer and provide mechanistic insights into the regulation of LNMAS in EMT and immune evasion.

Identification and Validation of a Novel Genomic Instability-Associated Long Non-Coding RNA Prognostic Signature in Head and Neck Squamous Cell Carcinoma

Background: Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive malignant cancers worldwide, and accurate prognostic models are urgently needed. Emerging evidence revealed that long non-coding RNAs (lncRNAs) are related to genomic instability. We sought to identify and validate a genomic instability-associated lncRNA prognostic signature to assess HNSCC patient survival outcomes.

Methods: RNA-sequencing data, somatic mutation files, and patient clinical data were downloaded from The Cancer Genome Atlas database. A total of 491 patients with completely clinical files were randomly divided into training and testing sets. In the training set, genomic instability-associated lncRNAs were screened through univariate Cox regression analyses and least absolute shrinkage and selection operator regression analyses to build a genomic instability-associated lncRNA signature (GILncSig). In addition, time-dependent receiver operating characteristic (ROC) curve, Kaplan-Meier survival curve, and clinical stratification analyses were used to evaluate the signature’s reliability. Finally, in situ hybridization experiments were performed to validate GILncSig expression levels between adjacent non-tumor tissues and tumor tissues from HNSCC patients.

Results: Four genomic instability-associated lncRNAs (AC023310.4, AC091729.1, LINC01564, and MIR3142HG) were selected for the prognostic signature. The model was successfully validated using the testing cohort. ROC analysis demonstrated its strong predictive ability for HNSCC prognosis. Univariate and multivariate Cox analyses revealed that the GILncSig was an independent predictor of prognosis. HNSCC patients with a low-risk score showed a substantially better prognosis than the high-risk groups. The in situ hybridization experiments using human HNSCC tissue revealed high GILncSig expression in HNSCC tissues compared with adjacent non-tumor tissues.

Conclusion: We developed a novel GILncSig for prognosis prediction in HNSCC patients, and the components of that signature might be therapeutic targets for HNSCC.

Splicing factor SRSF2-centric gene regulation

Serine/arginine-rich splicing factor 2 (SRSF2) is a splicing factor that is widely expressed in a variety of mammalian cell types. Increasing evidence has confirmed that SRSF2 plays vital roles in a number of biological and pathological processes. Therefore, it is important to understand how its expression is regulated, and how it regulates the expression of its target genes. Recently, we found that SRSF2 expression could be upregulated by herpes simplex virus-1 (HSV-1) infection, and that altered SRSF2 expression, in turn, epigenetically regulates the transcription of HSV-1 genes. Further studies on T cell exhaustion demonstrated that upregulated SRSF2 in exhausted T cells elevated the levels of multiple immune checkpoint molecules by associating with the acyl-transferases, P300 and CBP, and by altering histone modification near the transcription start sites of these genes, thereby influencing signal transducer and activator of transcription 3 binding to these gene promoters. These findings suggest that SRSF2 acts as an important sensor and effector during disease progression. Here, we discuss the molecules that regulate SRSF2 gene expression and their associated mechanisms, and the mechanisms via which SRSF2 regulates the expression of target genes, thus providing novel insights into the central role of SRSF2 in gene regulation.

Down-regulating NEAT1 inhibited the viability and vasculogenic mimicry formation of sinonasal squamous cell carcinoma cells via miR-195-5p/VEGFA axis

The role of long non-coding RNA nuclear-enriched abundant transcript 1 (lncRNA NEAT1) in sinonasal squamous cell carcinoma (SNSCC) remained obscure. Target genes and potential binding sites of NEAT1, microRNA (miR)-195-5p and VEGFA were predicted using StarBase and TargetScan, and confirmed by dual-luciferase reporter assay. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the expressions of NEAT1, vascular endothelial growth factor A (VEGFA) and miR-195-5p. Pearson's correlation analysis of NEAT1, miR-195-5p and VEGFA was conducted. Cell viability, apoptosis and tube formation capability were assessed by MTT assay, flow cytometry and capillary-like tube formation assay, respectively. Expressions of VEGFA and proteins related to the phosphatidylinositide 3-kinase/Protein Kinase B (PI3K/AKT) pathway were measured by Western blot. In SNSCC tissues and cells, the expressions of NEAT1 and VEGFA were up-regulated while the expression of miR-195-5p was down-regulated, and NEAT1 was negatively correlated with miR-195-5p yet positively correlated with VEGFA. Overexpressed VEGFA promoted the viability and capillary-like tube formation of SNSCC cells yet suppressed their apoptosis, while silencing VEGFA led to the opposite results. MiR-195-5p could bind to NEAT1, and down-regulating miR-195-5p reversed the effects of silencing NEAT1 on the expressions of NEAT1 and miR-195-5p, cell viability, apoptosis and capillary-like tube formation as well as PI3K/AKT pathway activation. VEGFA was the target of miR-195-5p, and overexpressed VEGFA reversed the effects of miR-195-5p. Down-regulating NEAT1 inhibited the viability and vasculogenic mimicry formation of SNSCC cells yet promoted their apoptosis via the miR-195-5p/VEGFA axis, providing a possible therapeutic target for SNSCC treatment.

Long non-coding RNA AFAP1-AS1 promotes cell growth and inhibits apoptosis by binding to specific proteins in germinal center B-cell-like diffuse large B-cell lymphoma

Germinal center B-cell-like diffuse large B-cell lymphoma (GCB-DLBCL) is a common subtype of lymphoma in adults. Previously, we found that actin filament-associated protein 1-antisense RNA 1 (AFAP1-AS1) is among the most overexpressed lncRNAs in GCB-DLBCL. In this study, we explored its biological functions and molecular mechanisms in the progression of GCB-DLBCL. We discovered, via bioinformatics, that patients with a high expression of AFAP1-AS1 had significantly poor disease-free survival (DFS) and overall survival (OS). Subsequent assays demonstrated that AFAP1-AS1 knockdown inhibited cell proliferation and prompted arrest of the G0/G1 cell cycle and apoptosis in GCB-DLBCL cell lines. Proteomics analysis indicated that hundreds of proteins were deregulated after AFAP1-AS1 knockdown and KEGG pathway analysis revealed that the deregulated proteins belonged to multiple signaling pathways, such as "B-cell receptor signaling pathway". Moreover, in the comprehensive identification of proteins that bind to RNA (by ChIRP-MS), several proteins associated with RNA splicing were identified (e.g., SFPQ, NONO, SRSF2, SRSF6, and KHSRP) that could specifically bind to AFAP1-AS1, which was confirmed by parallel reaction monitoring assay (PRM). Conclusively, we demonstrated that AFAP1-AS1 is a possible prognostic marker of poor outcomes in GCB-DLBCL patients and could modulate gene expression through connecting to specific proteins to practice its oncogenic role in GCB-DLBCL.

miR-362-3p suppresses sinonasal squamous cell carcinoma progression via directly targeting pituitary tumor-transforming gene 1

BACKGROUND

Sinonasal squamous cell carcinoma (SNSCC) is a main subtype of sinonasal malignancy with unclear pathogenesis. microRNAs (miRNAs) are involved in SNSCC progression. Nevertheless, the role and mechanism of miR-362-3p in SNSCC development are unclear.

METHODS

The SNSCC tissues (n = 23) and normal sinonasal samples (n = 13) were harvested. SNSCC cell line RPMI-2650 cells were transfected using Lipofectamine 3000. miR-362-3p and pituitary tumor-transforming gene 1 (PTTG1) were determined by quantitative reverse transcription polymerase chain reaction and western blot. Cell proliferation was analyzed via Cell Counting Kit-8 and 5-ethynyl-2'-deoxyuridine assays. Cell migration and invasion was assessed using wound healing assay and transwell assay. Epithelial-mesenchymal transition (EMT)-associated protein (E-cadherin, N-cadherin and Vimentin) levels were measured via western blot. The binding relationship was analyzed via bioinformatic analysis and dual-luciferase reporter assay.

RESULTS

miR-362-3p abundance was decreased in SNSCC samples. miR-362-3p addition constrained cell proliferation, migration, invasion and EMT, but miR-362-3p knockdown played an opposite effect. PTTG1 was targeted and negatively modulated by miR-362-3p. PTTG1 abundance was elevated in SNSCC samples. PTTG1 overexpression mitigated miR-362-3p-modulated suppression of cell proliferation, migration, invasion and EMT in SNSCC cells.

CONCLUSION

miR-362-3p repressed cell proliferation, migration, invasion and EMT in SNSCC via targeting PTTG1.

The Role of lncRNA Crosstalk in Leading Cancer Metastasis of Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common type of human malignancy. For decades, research into HNSCC invasion and metastasis has been dedicated to the study of protein-coding genes. Along with whole-genome and transcriptome sequencing development, long non-coding RNA (lncRNA) has attracted greater attention. Compelling evidence has proven the critical role of lncRNAs in the occurrence and development of HNSCC by means of epigenetic modifications, regulation of gene transcription, and post-transcription level. More importantly, crosstalk between lncRNAs and microRNAs was recently proven to regulate HNSCC metastasis through EMT modification. Based on these, this review summarizes the critical roles of lncRNAs in HNSCC metastasis and the crosstalk between lncRNAs and microRNAs as well as the detailed regulatory mechanism of the interaction. Thus, a deeper understanding of the lncRNA network in cancer metastasis is finally uncovered in order to provide a rationale and innovative concepts toward new therapeutic strategies for the highly metastatic HNSCC.

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.