Small nucleolar RNAs in cancer

SUMOylation regulation of ribosome biogenesis: Emerging roles for USP36

Ribosome biogenesis is essential for cell growth, proliferation, and animal development. Its deregulation leads to various human disorders such as ribosomopathies and cancer. Thus, tight regulation of ribosome biogenesis is crucial for normal cell homeostasis. Emerging evidence suggests that posttranslational modifications such as ubiquitination and SUMOylation play a crucial role in regulating ribosome biogenesis. Our recent studies reveal that USP36, a nucleolar deubiquitinating enzyme (DUB), acts also as a SUMO ligase to regulate nucleolar protein group SUMOylation, thereby being essential for ribosome biogenesis. Here, we provide an overview of the current understanding of the SUMOylation regulation of ribosome biogenesis and discuss the role of USP36 in nucleolar SUMOylation.

Biomarker discovery and validation for gastrointestinal tumors: A comprehensive review of colorectal, gastric, and liver cancers

Gastrointestinal (GI) malignancies, encompassing gastric, hepatic, colonic, and rectal cancers, are prevalent forms of cancer globally and contribute substantially to cancer-related mortality. Although there have been improvements in methods for diagnosing and treating GI cancers, the chances of survival for these types of cancers are still extremely low. According to the World Cancer Research International Fund's most recent figures, stomach cancer was responsible for roughly one million deaths worldwide in 2020. This emphasizes the importance of developing more effective tools for detecting, diagnosing, and predicting the outcome of these cancers at an early stage. Biomarkers, quantitative indications of biological processes or disease states, have emerged as promising techniques for enhancing the diagnosis and prognosis of GI malignancies. Recently, there has been a considerable endeavor to discover and authenticate biomarkers for various GI cancers by the utilization of diverse methodologies, including genomics, proteomics, and metabolomics. This review provides a thorough examination of the current state of biomarker research in the field of gastrointestinal malignancies, with a specific emphasis on colorectal, stomach, and liver cancers. A thorough literature search was performed on prominent databases such as PubMed, Scopus, and Web of Science to find pertinent papers published until November, 2023 for the purpose of compiling this review. The diverse categories of biomarkers, encompassing genetic, epigenetic, and protein-based biomarkers, and their potential utility in the fields of diagnosis, prognosis, and treatment selection, are explored. Recent progress in identifying and confirming biomarkers, as well as the obstacles that persist in employing biomarkers in clinical settings are emphasized. The utilization of biomarkers in GI cancers has significant potential in enhancing patient outcomes. Ongoing research is expected to uncover more efficient biomarkers for the diagnosis and prognosis of these cancers.

Identification of four snoRNAs (SNORD16, SNORA73B, SCARNA4, and SNORD49B) as novel non-invasive biomarkers for diagnosis of breast cancer

BACKGROUND

Emerging data point to the critical role of snoRNA in the emergence of different types of cancer, but scarcely in breast cancer (BC). This study aimed to clarify the differential expressions and potential diagnostic value of SNORD16, SNORA73B, SCARNA4, and SNORD49B in BC.

METHODS

We screened differential snoRNAs in BC tissues and adjacent tissues through SNORic datasets, and then we further verified them in the plasma of BC patients and healthy volunteers by quantitative polymerase chain reaction (qPCR).

RESULTS

These four snoRNAs: SNORD16, SNORA73B, SCARNA4, and SNORD49B were considerably more abundant in cancerous tissues than in neighboring tissues in the TCGA database. Their plasma levels were also higher in BC and early-stage BC patients when compared to healthy controls. Furthermore, the ROC curve demonstrated that BC (AUC = 0.7521) and early-stage BC (AUC = 0.7305) might be successfully distinguished from healthy people by SNORD16, SNORA73B, SCARNA4, and SNORD49B.

CONCLUSION

Plasma snoRNAs: SNORD16, SNORA73B, SCARNA4, and SNORD49B were upregulated in BC and early-stage BC and can be used as potential diagnostic markers for BC and early-stage BC.

Small nucleolar RNA Snora73 promotes psoriasis progression by sponging miR-3074-5p and regulating PBX1 expression

Chronic psoriasis is a kind of immune-mediated skin illness and the underlying molecular mechanisms of pathogenesis remain incompletely understood. Here, we used small RNA microarray assays to scan the differential expressed RNAs in psoriasis patient samples. The downstream miRNAs and its targets were predicted using bioinformatics analysis from online bases and confirmed using fluorescence in situ hybridization and dual‑luciferase report gene assay. Cell ability of proliferation and migration were detected using CCK-8 and transwell assays. The results showed that a new snoRNA Snora73 was upregulated in psoriasis patient samples. Overexpression of Snora73 significantly increased psoriasis cells viability and migration, while knockdown of Snora73 got the opposite results. Mechanistically, our results showed that Snora73 acted as a sponge for miR-3074-5p and PBX1 is a direct target of miR-3074-5p in psoriasis cells. Furthermore, miR-3074-5p suppressed psoriasis cell proliferation and migration, while PBX1 promoted cell proliferation and migration in psoriasis. Collectively, these findings reveal a crucial role of Snora73 in progression of psoriasis through miR-3074-5p/PBX1 signaling pathway and suggest a potential therapeutic strategy.

Small nucleolar RNA and its potential role in the oncogenesis and development of colorectal cancer

Small nucleolar RNAs (snoRNAs) represent a class of non-coding RNAs that play pivotal roles in post-transcriptional RNA processing and modification, thereby contributing significantly to the maintenance of cellular functions related to protein synthesis. SnoRNAs have been discovered to possess the ability to influence cell fate and alter disease progression, holding immense potential in controlling human diseases. It is suggested that the dysregulation of snoRNAs in cancer exhibits differential expression across various cancer types, stages, metastasis, treatment response and/or prognosis in patients. On the other hand, colorectal cancer (CRC), a prevalent malignancy of the digestive system, is characterized by high incidence and mortality rates, ranking as the third most common cancer type. Recent research indicates that snoRNA dysregulation is associated with CRC, as snoRNA expression significantly differs between normal and cancerous conditions. Consequently, assessing snoRNA expression level and function holds promise for the prognosis and diagnosis of CRC. Nevertheless, current comprehension of the potential roles of snoRNAs in CRC remains limited. This review offers a comprehensive survey of the aberrant regulation of snoRNAs in CRC, providing valuable insights into the discovery of novel biomarkers, therapeutic targets, and potential tools for the diagnosis and treatment of CRC and furnishing critical cues for advancing research into CRC and the judicious selection of therapeutic targets.

Non-coding RNAs as Biomarkers for Survival in Colorectal Cancer Patients

Colorectal cancer (CRC) has a high incidence and fatality rate worldwide. It ranks second concerning death worldwide. Cancer patients are diagnosed with the disease at a later stage due to the absence of early diagnostic methods, which leads to increased death. With the help of recent advancements in the fields of diagnosis and therapy, the development of novel methods using new targets could be helpful for the long-term survival of CRC patients when CRC is detected early. However, the prognosis for the advanced stage of CRC is abysmal. New biomarkers are emerging as promising alternatives since they can be utilized for early detection of CRC, are simple to use, and non-invasive. Non-coding RNAs (ncRNAs) have been seen to have an aberrant expression in the development of many malignancies, including CRC. In the past two decades, much research has been done on non-coding RNAs, which may be valuable as biomarkers and targets for antitumor therapy. Non-coding RNAs can be employed in detecting and treating CRC. Non-coding RNAs play an essential role in regulating gene expression. This article reviews ncRNAs and their expression levels in CRC patients that could be used as potential biomarkers. Various ncRNAs have been associated with CRC, such as microRNAs, long non-coding RNAs, circular RNAs, etc. The expression of these non-coding RNAs may provide insights into the stages of cancer and the prognosis of cancer patients and therefore proper precautionary measures can be taken to decrease cancer-related deaths.

SAGESDA: Multi-GraphSAGE networks for predicting SnoRNA-disease associations

Over the years, extensive research has highlighted the functional roles of small nucleolar RNAs in various biological processes associated with the development of complex human diseases. Therefore, understanding the existing relationships between different snoRNAs and diseases is crucial for advancing disease diagnosis and treatment. However, classical biological experiments for identifying snoRNA-disease associations are expensive and time-consuming. Therefore, there is an urgent need for cost-effective computational techniques that can enhance the efficiency and accuracy of prediction. While several computational models have already been proposed, many suffer from limitations and suboptimal performance. In this study, we introduced a novel Graph Neural Network-based (GNN) classification model, called SAGESDA, which is implemented through the GraphSAGE architecture with attention for the prediction of snoRNA-disease associations. The classifier leverages local neighbouring nodes in a heterogeneous network to generate new node embeddings through message passing. The mini-batch gradient descent technique was applied to divide the graph into smaller sub-graphs, which enhances the model's accuracy, speed and scalability. With these advancements, SAGESDA attained an area under the receiver operating characteristic (ROC) curve (AUC) of 0.92 using the standard dot product classifier, surpassing previous related studies. This notable performance demonstrates that SAGESDA is a promising model for predicting unknown snoRNA-disease associations with high accuracy. The SAGESDA implementation details can be obtained from https://github.com/momanyibiffon/SAGESDA.git.

Regulation of the epigenome through RNA modifications

Chemical modifications of nucleotides expand the complexity and functional properties of genomes and transcriptomes. A handful of modifications in DNA bases are part of the epigenome, wherein DNA methylation regulates chromatin structure, transcription, and co-transcriptional RNA processing. In contrast, more than 150 chemical modifications of RNA constitute the epitranscriptome. Ribonucleoside modifications comprise a diverse repertoire of chemical groups, including methylation, acetylation, deamination, isomerization, and oxidation. Such RNA modifications regulate all steps of RNA metabolism, including folding, processing, stability, transport, translation, and RNA's intermolecular interactions. Initially thought to influence all aspects of the post-transcriptional regulation of gene expression exclusively, recent findings uncovered a crosstalk between the epitranscriptome and the epigenome. In other words, RNA modifications feedback to the epigenome to transcriptionally regulate gene expression. The epitranscriptome achieves this feat by directly or indirectly affecting chromatin structure and nuclear organization. This review highlights how chemical modifications in chromatin-associated RNAs (caRNAs) and messenger RNAs (mRNAs) encoding factors involved in transcription, chromatin structure, histone modifications, and nuclear organization affect gene expression transcriptionally.

Knowledge mapping and current trends of global research on snoRNA in the field of cancer

Cancer is a major health hazard for humans. Recent studies have indicated the involvement of small nucleolar RNAs (snoRNAs) in the occurrence and development of cancer and indicated its potential role as a diagnostic/prognostic marker and therapeutic target. The purpose of this study was to use the bibliometrics method to analyze the published literature on this subject. We collected articles pertaining to the field of snoRNA and cancer from the Web of Science Core Collection database. The data were analyzed to identify the research hotspots and frontiers. The number of articles in this field was low in the early period. Chu Liang and Montanaro Lorenzo were the most prolific authors on this subject, while Jiang and Feng were the most frequently cited authors. In China, three institutions published the most articles, namely Wuhan Univ, China Med Univ, and Guangxi Med Univ. The journal with the highest number of articles on this subject was Oncotarget. The country with the most published articles was China. Analysis of keywords and burst words indicated that early studies mainly focused on molecular mechanisms. Available evidence suggests the involvement of snoRNAs in the molecular mechanism of cancer development and their potential role as a diagnostic and prognostic biomarker.

Uterine leiomyoma with RAD51B::NUDT3 fusion: a report of 2 cases

Three main uterine leiomyoma molecular subtypes include tumors with MED12 mutation, molecular aberrations leading to HMGA2 overexpression, and biallelic loss of FH. These aberrations are mutually exclusive and can be found in approximately 80-90% of uterine leiomyoma, in which they seem to be a driver event. Approximately 10% of uterine leiomyoma, however, does not belong to any of these categories. Uterine leiomyoma with HMGA2 overexpression is the most common subtype in cellular and second most common category of usual leiomyoma. In some of these tumors, rearrangement of HMGA2 gene is present. The most common fusion partner of HMGA2 gene is RAD51B. Limited data suggests that RAD51B fusions with other genes may be present in uterine leiomyoma. In our study, we described two cases of uterine leiomyoma with RAD51B::NUDT3 fusion, which occur in one case of usual and one case of highly cellular leiomyoma. In both cases, no other driver molecular aberrations were found. The results of our study showed that RAD51::NUDT3 fusion can occur in both usual and cellular leiomyoma. RAD51B may be a fusion partner of multiple genes other than HMGA2 and HMGA1. In these cases, RAD51B fusion seems to be mutually exclusive with other driver aberrations defining molecular leiomyoma subtypes. RAD51B::NUDT3 fusion should be added to the spectrum of fusions which may occur in uterine leiomyoma, which can be of value especially in cellular leiomyoma in the context of differential diagnosis against endometrial stromal tumors.

snoRNAs in hematopoiesis and blood malignancies: A comprehensive review

Small nucleolar RNAs (snoRNAs) are noncoding RNA molecules of highly variable size, usually ranging from 60 to 150 nucleotides. They are classified into H/ACA box snoRNAs, C/D box snoRNAs, and scaRNAs. Their functional profile includes biogenesis of ribosomes, processing of rRNAs, 2'-O-methylation and pseudouridylation of RNAs, alternative splicing and processing of mRNAs and the generation of small RNA molecules like miRNA. The snoRNAs have been observed to have an important role in hematopoiesis and malignant hematopoietic conditions including leukemia, lymphoma, and multiple myeloma. Blood malignancies arise in immune system cells or the bone marrow due to chromosome abnormalities. It has been estimated that annually over 1.25 million cases of blood cancer occur worldwide. The snoRNAs often show a differential expression profile in blood malignancies. Recent reports associate the abnormal expression of snoRNAs with the inhibition of apoptosis, uncontrolled cell proliferation, angiogenesis, and metastasis. This implies that targeting snoRNAs could be a potential way to treat hematologic malignancies. In this review, we describe the various functions of snoRNAs, their role in hematopoiesis, and the consequences of their dysregulation in blood malignancies. We also evaluate the potential of the dysregulated snoRNAs as biomarkers and therapeutic targets for blood malignancies.

Plasma SNORD42B and SNORD111 as potential biomarkers for early diagnosis of non‐small cell lung cancer

Background

Non‐small‐cell lung cancer (NSCLC) still occupied the leading reason of cancer death due to lack of availability of early detection. This study aimed to identify the effective biomarkers for the early‐stage NSCLC diagnostics based on plasma snoRNAs.

Materials and Methods

The differential snoRNAs between lung cancer patients and healthy donors were analyzed using the SNORic and TCGA databases. SNORD42B and SNORD111 were screened out and further verified in 48 FFPE NSCLC and adjacent normal tissues, as well as in plasma from 165 NSCLC patients and 118 health donors using qRT‐PCR. Next, their diagnostic efficiency, as well as combined with carcinoembryonic antigen (CEA), was obtained by the analysis of receiver operating characteristic (ROC).

Results

We first screened out 47 top differential snoRNAs, among which the top 10 upregulated snoRNAs in LUAD were U44, U75, U78, U77, SNORD72, SNORD13, SNORD12B, SCARNA5, U80, SNORD41, and in LUSC were U44, U75, U78, SNORD41, SNORD111, SNORA56, U17a, SNORD35A, SNORD32A, SNORA71D. SNORD42B and SNORD111 was significantly increased not only in tumor tissues but also in plasma from NSCLC and early‐stage NSCLC patients. They were capable to act as promising biomarkers for NSCLC and early‐stage NSCLC diagnosis. Moreover, CEA diagnostic efficiency for early‐stage NSCLC was significantly improved when combined with these two plasma snoRNAs.

Conclusion

SNORD42B and SNORD111 could act as the potential and non‐invasive diagnostic biomarkers for NSCLC and early‐stage NSCLC.

Small Nucleolar RNA and C/D Box 15B Regulate the TRIM25/P53 Complex to Promote the Development of Endometrial Cancer

Background

Endometrial cancer is associated with a high mortality rate, which warrants the identification of novel diagnostic markers and therapeutic targets. The aim of this study is to evaluate the role of SNORD15B in the development of endometrial cancer and explore the potential underlying mechanisms.

Methods

Bioinformatics was used to analyze the expression level and prognostic relevance of SNORD15B in endometrial cancer. The Ishikawa and HEC-1B cells were respectively transfected with SNORD15B expression plasmid and an antisense oligonucleotide, or the corresponding empty vector and a nonspecific sequence. The malignant phenotype of the suitably transfected cells was assessed by standard in vitro functional assays and the establishment of in vivo xenografts. The expression levels of the specific markers were analyzed with RT-qPCR and western blotting. The subcellular localization of P53 was determined by analyzing the nuclear and cytoplasmic fractions. RIP, Co-IP, and immunohistochemistry were performed as per standard protocols.

Results

SNORD15B was overexpressed in the endometrial cancer tissues and correlated to a poor prognosis. Ectopic expression of SNORD15B in Ishikawa cells inhibited apoptosis, increased the proliferation, invasion, and migration in vitro, and enhanced their tumorigenicity in vivo. SNORD15B overexpression also upregulated TRIM25 and accelerated P53 accumulation in the cytoplasm of the endometrial cancer cells.

Conclusion

SNORD15B functions as an oncogene in endometrial cancer by targeting the TRIM25/P53 complex and blocking the nuclear translocation of P53.

Non-Coding RNAs in Hepatocellular Carcinoma

Liver cancer ranks as the fourth leading cause of cancer-related deaths. Despite extensive research efforts aiming to evaluate the biological mechanisms underlying hepatocellular carcinoma (HCC) development, little has been translated towards new diagnostic and treatment options for HCC patients. Historically, the focus has been centered on coding RNAs and their respective proteins. However, significant advances in sequencing and RNA detection technologies have shifted the research focus towards non-coding RNAs (ncRNA), as well as their impact on HCC development and progression. A number of studies reported complex post-transcriptional interactions between various ncRNA and coding RNA molecules. These interactions offer insights into the role of ncRNAs in both the known pathways leading to oncogenesis, such as dysregulation of p53, and lesser-known mechanisms, such as small nucleolar RNA methylation. Studies investigating these mechanisms have identified prevalent ncRNA changes in microRNAs, snoRNAs, and long non-coding RNAs that can both pre- and post-translationally regulate key factors in HCC progression. In this review, we present relevant publications describing ncRNAs to summarize the impact of different ncRNA species on liver cancer development and progression and to evaluate recent attempts at clinical translation.

A nop56 Zebrafish Loss-of-Function Model Exhibits a Severe Neurodegenerative Phenotype

NOP56 belongs to a C/D box small nucleolar ribonucleoprotein complex that is in charge of cleavage and modification of precursor ribosomal RNAs and assembly of the 60S ribosomal subunit. An intronic expansion in NOP56 gene causes Spinocerebellar Ataxia type 36, a typical late-onset autosomal dominant ataxia. Although vertebrate animal models were created for the intronic expansion, none was studied for the loss of function of NOP56. We studied a zebrafish loss-of-function model of the nop56 gene which shows 70% homology with the human gene. We observed a severe neurodegenerative phenotype in nop56 mutants, characterized mainly by absence of cerebellum, reduced numbers of spinal cord neurons, high levels of apoptosis in the central nervous system (CNS) and impaired movement, resulting in death before 7 days post-fertilization. Gene expression of genes related to C/D box complex, balance and CNS development was impaired in nop56 mutants. In our study, we characterized the first NOP56 loss-of-function vertebrate model, which is important to further understand the role of NOP56 in CNS function and development.

The role and mechanism of noncoding RNAs in regulation of metabolic reprogramming in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Metabolic reprogramming is considered to be an important hallmark of cancer. Emerging studies have demonstrated that noncoding RNAs (ncRNAs) are closely associated with metabolic reprogramming of HCC. NcRNAs can directly regulate the expressions or functions of metabolic enzymes or indirectly regulate the metabolism of HCC cells through some vital signaling pathways. Until now, the mechanisms of HCC development and progression remain largely unclear, and understanding the regulatory mechanism of ncRNAs on metabolic reprogramming of HCC may provide an important basis for breakthrough progress in the treatment of HCC. In this review, we summarize the ncRNAs involved in regulating metabolic reprogramming of HCC. Specifically, the regulatory roles of ncRNAs in glucose, lipid and amino acid metabolism are elaborated. In addition, we discuss the molecular mechanism of ncRNAs in regulation of metabolic reprogramming and possible therapeutic strategies that target the metabolism of cancer cells by modulating the expressions of specific ncRNAs.

Per- and polyfluoroalkyl substances, epigenetic age and DNA methylation: a cross-sectional study of firefighters

Background: Per- and polyfluoroalkyl substances (PFASs) are persistent chemicals that firefighters encounter. Epigenetic modifications, including DNA methylation, could serve as PFASs toxicity biomarkers. Methods: With a sample size of 197 firefighters, we quantified the serum concentrations of nine PFASs, blood leukocyte DNA methylation and epigenetic age indicators via the EPIC array. We examined the associations between PFASs with epigenetic age, site- and region-specific DNA methylation, adjusting for confounders. Results: Perfluorohexane sulfonate, perfluorooctanoate (PFOA) and the sum of branched isomers of perfluorooctane sulfonate (Sm-PFOS) were associated with accelerated epigenetic age. Branched PFOA, linear PFOS, perfluorononanoate, perfluorodecanoate and perfluoroundecanoate were associated with differentially methylated loci and regions. Conclusion: PFASs concentrations are associated with accelerated epigenetic age and locus-specific DNA methylation. The implications for PFASs toxicity merit further investigation.

Endogenous microRNA triggered enzyme-free DNA logic self-assembly for amplified bioimaging and enhanced gene therapy via in situ generation of siRNAs

BACKGROUND

Small interfering RNA (siRNA) has emerged as a kind of promising therapeutic agents for cancer therapy. However, the off-target effect and degradation are the main challenges for siRNAs delivery. Herein, an enzyme-free DNA amplification strategy initiated by a specific endogenous microRNA has been developed for in situ generation of siRNAs with enhanced gene therapy effect on cervical carcinoma.

METHODS

This strategy contains three DNA hairpins (H1, H2/PS and H3) which can be triggered by microRNA-21 (miR-21) for self-assembly of DNA nanowheels (DNWs). Notably, this system is consistent with the operation of a DNA logic circuitry containing cascaded "AND" gates with feedback mechanism. Accordingly, a versatile biosensing and bioimaging platform is fabricated for sensitive and specific analysis of miR-21 in HeLa cells via fluorescence resonance energy transfer (FRET). Meanwhile, since the vascular endothelial growth factor (VEGF) antisense and sense sequences are encoded in hairpin reactants, the performance of this DNA circuit leads to in situ assembly of VEGF siRNAs in DNWs, which can be specifically recognized and cleaved by Dicer for gene therapy of cervical carcinoma.

RESULTS

The proposed isothermal amplification approach exhibits high sensitivity for miR-21 with a detection limit of 0.25 pM and indicates excellent specificity to discriminate target miR-21 from the single-base mismatched sequence. Furthermore, this strategy achieves accurate and sensitive imaging analysis of the expression and distribution of miR-21 in different living cells. To note, compared to naked siRNAs alone, in situ siRNA generation shows a significantly enhanced gene silencing and anti-tumor effect due to the high reaction efficiency of DNA circuit and improved delivery stability of siRNAs.

CONCLUSIONS

The endogenous miRNA-activated DNA circuit provides an exciting opportunity to construct a general nanoplatform for precise cancer diagnosis and efficient gene therapy, which has an important significance in clinical translation.

The noncoding RNAs SNORD50A and SNORD50B-mediated TRIM21-GMPS interaction promotes the growth of p53 wild-type breast cancers by degrading p53

Small nucleolar RNA SNORD50A and SNORD50B (SNORD50A/B) has been reported to be recurrently deleted and function as a putative tumor suppressor in different types of cancer by binding to and suppressing the activity of the KRAS oncoproteins. Its deletion correlates with poorer patient survival. However, in this study, we surprisingly found that SNORD50A/B loss predicted a better survival in breast cancer patients carrying wild-type p53. Functional studies showed that SNORD50A/B deletion strongly inhibited the proliferation, migration, invasion and tumorigenic potential, and induced cell cycle arrest and apoptosis in p53 wild-type breast cancer cells, while exerted the opposite effects in p53 mutated breast cancer cells. This was also supported by ectopically expressing SNORD50A/B in both p53 wild-type and mutated breast cancer cells. Mechanistically, SNORD50A/B clearly enhances the interaction between E3 ubiquitin ligase TRIM21 and its substrate GMPS by forming a complex among them, thereby promoting GMPS ubiquitination and its subsequent cytoplasmic sequestration. SNORD50A/B deletion in p53 wild-type breast cancer cells will release GMPS and induce the translocation of GMPS into the nucleus, where GMPS can recruit USP7 and form a complex with p53, thereby decreasing p53 ubiquitination, stabilizing p53 proteins, and inhibiting malignant phenotypes of cancer cells. Altogether, the present study first reports that SNORD50A/B plays an oncogenic role in p53 wild-type breast cancers by mediating TRIM21-GMPS interaction.

The small Cajal body-specific RNA 15 (SCARNA15) directs p53 and redox homeostasis via selective splicing in cancer cells

Small Cajal body-specific RNAs (scaRNAs) guide post-transcriptional modification of spliceosomal RNA and, while commonly altered in cancer, have poorly defined roles in tumorigenesis. Here, we uncover that SCARNA15 directs alternative splicing (AS) and stress adaptation in cancer cells. Specifically, we find that SCARNA15 guides critical pseudouridylation (Ψ) of U2 spliceosomal RNA to fine-tune AS of distinct transcripts enriched for chromatin and transcriptional regulators in malignant cells. This critically impacts the expression and function of the key tumor suppressors ATRX and p53. Significantly, SCARNA15 loss impairs p53-mediated redox homeostasis and hampers cancer cell survival, motility and anchorage-independent growth. In sum, these findings highlight an unanticipated role for SCARNA15 and Ψ in directing cancer-associated splicing programs.

Targeting Epigenetics in Lung Cancer

The epigenetic landscape, which in part includes DNA methylation, chromatin organization, histone modifications, and noncoding RNA regulation, greatly contributes to the heterogeneity that makes developing effective therapies for lung cancer challenging. This review will provide an overview of the epigenetic alterations that have been implicated in all aspects of cancer pathogenesis and progression as well as summarize clinical applications for targeting epigenetics in the treatment of lung cancer.

Biomarkers (mRNAs and Non-Coding RNAs) for the Diagnosis and Prognosis of Colorectal Cancer - From the Body Fluid to Tissue Level

In recent years, the diagnosis and treatment of colorectal cancer (CRC) have been continuously improved, but the mortality rate continues to be high, especially in advanced patients. CRC patients usually have no obvious symptoms in the early stage and are already in the advanced stage when they are diagnosed. The 5-year survival rate is only 10%. The blood markers currently used to screen for CRC, such as carcinoembryonic antigen and carbohydrate antigen 19-9, have low sensitivity and specificity, whereas other methods are invasive or too expensive. As a result, recent research has shifted to the development of minimally invasive or noninvasive biomarkers in the form of body fluid biopsies. Non-coding RNA molecules are composed of microRNAs, long non-coding RNAs, small nucleolar RNAs, and circular RNAs, which have important roles in the occurrence and development of diseases and can be utilized for the early diagnosis and prognosis of tumors. In this review, we focus on the latest findings of mRNA-ncRNA as biomarkers for the diagnosis and prognosis of CRC, from fluid to tissue level.

High-Throughput Detection of Multiple miRNAs and Methylated DNA by Droplet Digital PCR

Altered miRNA expression and DNA methylation have highly active and diverse roles in carcinogenesis. Simultaneous detection of the molecular aberrations may have a synergistic effect on the diagnosis of malignancies. Herein, we develop a high-throughput assay for detecting multiple miRNAs and DNA methylation using droplet digital PCR (ddPCR) coupled with a 96-microwell plate. The microplate-based ddPCR could absolutely and reproducibly quantify 15 miRNAs and 14 DNA methylation sites with a high sensitivity (one copy/µL and 0.1%, respectively). Analyzing sputum and plasma of 40 lung cancer patients and 36 cancer-free smokers by this approach identified an integrated biomarker panel consisting of two sputum miRNAs (miRs-31-5p and 210-3p), one sputum DNA methylation (RASSF1A), and two plasma miRNAs (miR-21-5p and 126) for the diagnosis of lung cancer with higher sensitivity and specificity compared with a single type of biomarker. The diagnostic value of the integrated biomarker panel for the early detection of lung cancer was confirmed in a different cohort of 36 lung cancer patients and 39 cancer-free smokers. The high-throughput assay for quantification of multiple molecular aberrations across sputum and plasma could improve the early detection of lung cancer.

The deubiquitinase USP36 promotes snoRNP group SUMOylation and is essential for ribosome biogenesis

SUMOylation plays a crucial role in regulating diverse cellular processes including ribosome biogenesis. Proteomic analyses and experimental evidence showed that a number of nucleolar proteins involved in ribosome biogenesis are modified by SUMO. However, how these proteins are SUMOylated in cells is less understood. Here, we report that USP36, a nucleolar deubiquitinating enzyme (DUB), promotes nucleolar SUMOylation. Overexpression of USP36 enhances nucleolar SUMOylation, whereas its knockdown or genetic deletion reduces the levels of SUMOylation. USP36 interacts with SUMO2 and Ubc9 and directly mediates SUMOylation in cells and in vitro. We show that USP36 promotes the SUMOylation of the small nucleolar ribonucleoprotein (snoRNP) components Nop58 and Nhp2 in cells and in vitro and their binding to snoRNAs. It also promotes the SUMOylation of snoRNP components Nop56 and DKC1. Functionally, we show that knockdown of USP36 markedly impairs rRNA processing and translation. Thus, USP36 promotes snoRNP group SUMOylation and is critical for ribosome biogenesis and protein translation.

A small nucleolar RNA, SNORD126, promotes adipogenesis in cells and rats by activating the PI3K-AKT pathway

Small nucleolar RNA (snoRNA) plays important role in various histogenesis. Whether snoRNA plays a role in adipogenesis is unknown. SNORD126 is a C/D box snoRNA. We previously demonstrated that SNORD126 promoted hepatocellular carcinoma cell growth by activating the phosphoinositide 3-kinase-protein kinase B (Akt) pathway through upregulating fibroblast growth factor receptor 2 expression. In the present study, we found that the expression of SNORD126 was downregulated in the obesity-related tissues in high-fat diet-fed rats. Overexpression of SNORD126 in 3T3-L1 cells promoted adipocytes differentiation. SNORD126 significantly increased the expression of CCAAT/enhancer-binding protein α, fatty acid-binding protein 4, peroxisome proliferative-activated receptor-γ, and the phosphorylation of Akt and p70S6K. Overexpression of SNORD126 in human adipose-derived stem cells stimulated adipogenesis and increased phosphorylation of Akt. Meanwhile, SNORD126 increased the messenger RNA and protein levels of cyclin D1 and cyclin-dependent kinase 2, which promoted mitotic clonal expansion progression during the early stage of 3T3-L1 cell differentiation. We further found that SNORD126 accelerated the growth of the groin fat pad and increased phosphorylation of Akt and p70S6K in rats. Overall, our results suggested that SNORD126 promoted adipocyte differentiation through increasing phosphorylation of Akt and p70S6K both in vitro and in vivo.

TERRA Gene Expression in Gastric Cancer: Role of hTERT

PURPOSE

One of the most important serious malignancies is gastric cancer (GC) with a high mortality globally. In this way, beside the environmental factors, genetic parameter has a remarkable effective fluctuation in GC. Correspondingly, telomeres are nucleoprotein structures measuring the length of telomeres and they have special potential in diagnosis of various types of cancers. Defect protection of the telomeric length initiates the instability of the genome during cancer, including gastric cancer. The most common way of maintaining telomere length is the function of the telomerase enzyme that replicates the TTAGGG to the end of the 3' chromosome.

METHODS

In this review, we want to discuss the alterations of hTERT repression on the modification of TERRA gene expression in conjunction with the importance of telomere and telomerase in GC.

RESULTS

The telomerase enzyme contains two essential components called telomerase reverse transcriptase (hTERT) and RNA telomerase (hTR, hTERC). Deregulation of hTERT plays a key role in the multistage process of tumorigenicity and anticancer drug resistance. The direct relationship between telomerase activity and hTERT has led to hTERT to be considered a key target for cancer treatment. Recent results show that telomeres are transcribed into telomeric repeat-containing RNA (TERRA) in mammalian cells and are long noncoding RNAs (lncRNAs) identified in different tissues. In addition, most chemotherapy methods have a lot of side effects on normal cells.

CONCLUSION

Telomere and telomerase are useful therapeutic goal. According to the main roles of hTERT in tumorigenesis, growth, migration, and cancer invasion, hTERT and regulatory mechanisms that control the expression of hTERT are attractive therapeutic targets for cancer treatment.

jouvence, a new human snoRNA involved in the control of cell proliferation

Background

Small nucleolar RNAs (snoRNAs) are non-coding RNAs that are conserved from archaebacteria to mammals. They are associated in the nucleolus, with proteins to form small nucleolar ribonucleoprotein (snoRNPs). They modify ribosomal RNAs, for example, the H/ACA box that converts uridine to pseudouridine. In humans, various pathologies have been associated with snoRNAs, and several snoRNAs have been reported to participate in many cancer processes. Recently, a new H/ACA box snoRNA named jouvence has been identified in Drosophila and has been shown to be involved in lifespan determination in relation to gut homeostasis. Because snoRNAs are conserved through evolution, both structurally and functionally, a jouvence orthologue has been identified in humans. RT-PCR has revealed that jouvence is expressed, suggesting that it might be functional. These results suggest the hypothesis that jouvence may display similar functions, including increasing the healthy lifespan in humans.

Results

Here, we report the characterization of the human snoRNA jouvence, which has not yet been annotated in the genome. We show that its overexpression significantly stimulates cell proliferation, both in various stable cancerous cell lines as well as in primary cells. By contrast, its knockdown by siRNA leads to the opposite phenotype, a rapid decrease in cell proliferation. Transcriptomic analysis (RNA-Seq) revealed that the overexpression of jouvence leads to a dedifferentiation signature of the cells. Conversely, the knockdown of jouvence led to a striking decrease in the expression levels of genes involved in ribosome biogenesis and the spliceosome.

Conclusion

The overexpression of a single and short non-coding RNA of 159 nucleotides, the snoRNA-jouvence, seems to be sufficient to reorient cells toward stemness, while its depletion blocks cell proliferation. In this context, we speculate that the overexpression of jouvence, which appears to be a non-canonical H/ACA snoRNA, could represent a new tool to fight against the deleterious effects of aging, while inversely, its knockdown by siRNA could represent a new approach in cancer therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07197-3.

Nucleolar protein 10 (NOP10) predicts poor prognosis in invasive breast cancer

Purpose

Nucleolar protein 10 (NOP10) is required for ribosome biogenesis and telomere maintenance and plays a key role in carcinogenesis. This study aims to evaluate the clinical and prognostic significance of NOP10 in breast cancer (BC).

Methods

NOP10 expression was assessed at mRNA level employing the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) (n = 1980) and Cancer Genome Atlas (TCGA) BC cohorts (n = 854). Protein expression was evaluated on tissue microarray of a large BC cohort (n = 1081) using immunohistochemistry. The correlation between NOP10 expression, clinicopathological parameters and patient outcome was assessed.

Results

NOP10 expression was detected in the nucleus and nucleolus of the tumour cells. At the transcriptomic and proteomic levels, NOP10 was significantly associated with aggressive BC features including high tumour grade, high nucleolar score and poor Nottingham Prognostic Index. High NOP10 protein expression was an independent predictor of poor outcome in the whole cohort and in triple-negative BC (TNBC) class (p = 0.002 & p = 0.014, respectively). In chemotherapy- treated patients, high NOP10 protein expression was significantly associated with shorter survival (p = 0.03) and was predictive of higher risk of death (p = 0.028) and development of distant metastasis (p = 0.02) independent of tumour size, nodal stage and tumour grade.

Conclusion

High NOP10 expression is a poor prognostic biomarker in BC and its expression can help in predicting chemotherapy resistance. Functional assessments are necessary to decipher the underlying mechanisms and to reveal its potential therapeutic values in various BC subtypes especially in the aggressive TNBC class.

Electronic supplementary material

The online version of this article (doi:10.1007/s10549-020-05999-3) contains supplementary material, which is available to authorized users.

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.

snoRNAs Offer Novel Insight and Promising Perspectives for Lung Cancer Understanding and Management

Small nucleolar RNAs (snoRNAs) are non-coding RNAs localized in the nucleolus, where they participate in the cleavage and chemical modification of ribosomal RNAs. Their biogenesis and molecular functions have been extensively studied since their identification in the 1960s. However, their role in cancer has only recently started to emerge. In lung cancer, efforts to profile snoRNA expression have enabled the definition of snoRNA-related signatures, not only in tissues but also in biological fluids, exposing these small RNAs as potential non-invasive biomarkers. Moreover, snoRNAs appear to be essential actors of lung cancer onset and dissemination. They affect diverse cellular functions, from regulation of the cell proliferation/death balance to promotion of cancer cell plasticity. snoRNAs display both oncogenic and tumor suppressive activities that are pivotal in lung cancer tumorigenesis and progression. Altogether, we review how further insight into snoRNAs may improve our understanding of basic lung cancer biology and the development of innovative diagnostic tools and therapies.

Separated Siamese Twins: Intronic Small Nucleolar RNAs and Matched Host Genes May be Altered in Conjunction or Separately in Multiple Cancer Types

Small nucleolar RNAs (snoRNAs) are non-coding RNAs involved in RNA modification and processing. Approximately half of the so far identified snoRNA genes map within the intronic regions of host genes, and their expression, as well as the expression of their host genes, is dependent on transcript splicing and maturation. Growing evidence indicates that mutations and/or deregulations that affect snoRNAs, as well as host genes, play a significant role in oncogenesis. Among the possible factors underlying snoRNA/host gene expression deregulation is copy number alteration (CNA). We analyzed the data available in The Cancer Genome Atlas database, relative to CNA and expression of 295 snoRNA/host gene couples in 10 cancer types, to understand whether the genetic or expression alteration of snoRNAs and their matched host genes would have overlapping trends. Our results show that, counterintuitively, copy number and expression alterations of snoRNAs and matched host genes are not necessarily coupled. In addition, some snoRNA/host genes are mutated and overexpressed recurrently in multiple cancer types. Our findings suggest that the differential contribution to cancer development of both snoRNAs and host genes should always be considered, and that snoRNAs and their host genes may contribute to cancer development in conjunction or independently.

The nucleolus: a central response hub for the stressors that drive cancer progression

The nucleolus is a sub-nuclear body known primarily for its role in ribosome biogenesis. Increased number and/or size of nucleoli have historically been used by pathologists as a prognostic indicator of cancerous lesions. This increase in nucleolar number and/or size is classically attributed to the increased need for protein synthesis in cancer cells. However, evidences suggest that the nucleolus plays critical roles in many cellular functions in both normal cell biology and disease pathologies, including cancer. As new functions of the nucleolus are elucidated, there is mounting evidence to support the role of the nucleolus in regulating additional cellular functions, particularly response to cellular stressors, maintenance of genome stability, and DNA damage repair, as well as the regulation of gene expression and biogenesis of several ribonucleoproteins. This review highlights the central role of the nucleolus in carcinogenesis and cancer progression and discusses how cancer cells may become "addicted" to nucleolar functions.

Comprehensive transcriptomic analyses of tissue, serum, and serum exosomes from hepatocellular carcinoma patients

BACKGROUND

The expression of microRNAs (miRNAs) is a promising prognostic and diagnostic tool in hepatocellular carcinoma (HCC). Here we performed small RNA sequencing (sRNA-seq) of tissue, serum and serum exosomes to investigate changes in miRNA expression between the different sample types and correlated the expression with clinical parameters. We also performed gene expression arrays on tumor and normal tissue.

RESULTS

Paired tissue, serum and serum exosomes sequencing revealed consistent positive correlation of miR-21 between serum exosomes and tumor tissue, indicating that miR-21 could be exported from tissue to circulation via exosomes. We found that let-7 miRNAs are generally upregulated in serum exosomes compared to whole serum, indicating that these miRNAs could be preferentially loaded into exosomes. Comparing serum from HCC patients with serum from healthy individuals revealed a global increase of miRNAs in serum from HCC patients, including an almost 4-fold increase of several miRNAs, including the liver-specific miR-122. When correlating miRNA expression with clinical parameters we detected significant association between hepatitis B virus (HBV) infection and miR-122 in serum as well as several serum and tissue-miRNAs that correlated with surgery type. We found that miR-141 and miR-146 correlated with cirrhosis in tumor tissue and normal tissue, respectively. Finally, high expression of miR-21 in tumors were associated with poor survival. Focusing on gene expression we found several significant messenger RNAs (mRNAs) between tumor and normal tissue and a Gene Ontology (GO) analysis revealed that these changes were mainly related to cell cycle and metabolism. Further, we detected mRNAs that correlated with cirrhosis and HBV infection in tissue. Finally, GO analysis of predicted targets for miRNAs down-regulated in tumor found that these were enriched for functions related to collagen synthesis.

CONCLUSIONS

Our combined data point to altered miRNA and mRNA expression contributing to both generally impaired lipid metabolism and increased cell proliferation and a miRNA-driven increase in collagen synthesis in HCC. Our results further indicate a correlation in miRNA expression between exosomes, serum, and tissue samples suggesting export from tumors via exosomes. This correlation could provide a basis for a more tumor-specific miRNA profile in serum.

Integrated bioinformatics analysis reveals role of the LINC01093/miR-96-5p/ZFAND5/NF-κB signaling axis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a significant health burden worldwide and its pathogenesis remains to be fully elucidated. One of the means by which long non-coding (lnc)RNAs regulate gene expression is by interacting with micro (mi)RNAs and acting as competing endogenous (ce)RNAs. lncRNAs have important roles in various diseases. The aim of the present study was to examine the potential roles of lncRNAs in HCC. The RNA expression profiles of 21 paired tissues of HCC and adjacent non-tumor tissues were obtained from the Gene Expression Omnibus database. The differentially expressed RNAs were analyzed using the DESeq package in R. Expression validation and survival analysis of selected RNAs were performed using Gene Expression Profile Interactive Analysis and/or Kaplan-Meier Plotter. The target genes of the miRNAs were predicted using lncBase or TargetScan. Functional analyses were performed using the Database for Annotation, Visualization and Integrated Discovery, and regulatory networks were determined using Cytoscape. Long intergenic non-protein coding RNA 1093 (LINC01093) was identified as one of the most significantly downregulated lncRNAs in HCC tissues. Downregulated expression of LINC01093 was associated with poor prognosis. A ceRNA network involving LINC01093, miR-96-5p and zinc finger AN1-type containing 5 (ZFAND5) was established. According to functional analyses, NF-κB signaling was implicated in the regulatory network for HCC. The present study revealed that a LINC01093/miR-96-5p/ZFAND5/NF-κB signaling axis may have an important role in the pathogenesis of HCC, and further investigation of this axis may provide novel insight into the development and progression of HCC.

How Cancer Exploits Ribosomal RNA Biogenesis: A Journey beyond the Boundaries of rRNA Transcription

The generation of new ribosomes is a coordinated process essential to sustain cell growth. As such, it is tightly regulated according to cell needs. As cancer cells require intense protein translation to ensure their enhanced growth rate, they exploit various mechanisms to boost ribosome biogenesis. In this review, we will summarize how oncogenes and tumor suppressors modulate the biosynthesis of the RNA component of ribosomes, starting from the description of well-characterized pathways that converge on ribosomal RNA transcription while including novel insights that reveal unexpected regulatory networks hacked by cancer cells to unleash ribosome production.

Small Nucleolar RNAs: Insight Into Their Function in Cancer

Small nucleolar RNAs (SnoRNAs) are a class of non-coding RNAs divided into two classes: C/D box snoRNAs and H/ACA box snoRNAs. The canonical function of C/D box and H/ACA box snoRNAs are 2'-O-ribose methylation and pseudouridylation of ribosomal RNAs (rRNAs), respectively. Emerging evidence has demonstrated that snoRNAs are involved in various physiological and pathological cellular processes. Mutations and aberrant expression of snoRNAs have been reported in cell transformation, tumorigenesis, and metastasis, indicating that snoRNAs may serve as biomarkers and/or therapeutic targets of cancer. Hence, further study of the functions and underlying mechanism of snoRNAs is valuable. In this review, we summarize the biogenesis and functions of snoRNAs, as well as the association of snoRNAs in different types of cancers and their potential roles in cancer diagnosis and therapy.

Ets2 anchors the prometastatic function of mutant p53 in osteosarcoma

This Outlook by Liu and Kang discusses a study in this issue by Pourebrahim et al., which describes how the role of gain-of-function mutant p53 in promoting lung metastasis is shown to be critically dependent on the transcription factor Ets2 and is accompanied by the elevated expression of a cluster of small nucleolar RNAs (snoRNAs).

Mutations in the tumor suppressor p53 occur in a majority of human cancers. Some gain-of-function (GOF) p53 mutations endow tumor cells with increased metastatic ability, although our understanding of the underlying mechanism remains incomplete. In this issue of Genes & Development, Pourebrahim and colleagues (pp. 1847–1857) develop a new mouse model of osteosarcoma in which a GOF mutant p53 allele is expressed specifically in osteoblasts, while the tumor microenvironment remains wild type for p53, allowing for the study of cell-autonomous functions. In this model, the role of GOF mutant p53 in promoting lung metastasis is shown to be critically dependent on the transcription factor Ets2 and is accompanied by the elevated expression of a cluster of small nucleolar RNAs (snoRNAs).

Does functional specialization of ribosomes really exist?

It has recently become clear that ribosomes are much more heterogeneous than previously thought, with diversity arising from rRNA sequence and modifications, ribosomal protein (RP) content and posttranslational modifications (PTMs), as well as bound nonribosomal proteins. In some cases, the existence of these diverse ribosome populations has been verified by biochemical or structural methods. Furthermore, knockout or knockdown of RPs can diversify ribosome populations, while also affecting the translation of some mRNAs (but not others) with biological consequences. However, the effects on translation arising from depletion of diverse proteins can be highly similar, suggesting that there may be a more general defect in ribosome function or stability, perhaps arising from reduced ribosome numbers. Consistently, overall reduced ribosome numbers can differentially affect subclasses of mRNAs, necessitating controls for specificity. Moreover, in order to study the functional consequences of ribosome diversity, perturbations including affinity tags and knockouts are introduced, which can also affect the outcome of the experiment. Here we review the available literature to carefully evaluate whether the published data support functional diversification, defined as diverse ribosome populations differentially affecting translation of distinct mRNA (classes). Based on these observations and the commonly observed cellular responses to perturbations in the system, we suggest a set of important controls to validate functional diversity, which should include gain-of-function assays and the demonstration of inducibility under physiological conditions.

A panel of noncoding RNAs in non-small-cell lung cancer

Non-small-lung cancer (NSCLC) is the leading cause of cancer death. Early detection of NSCLC could pave the way for effective therapies. Analysis of molecular genetic biomarkers in biological fluids has been proposed as a useful tool for cancer diagnosis. Here, we aimed to develop a panel of noncoding RNAs (ncRNAs) in sputum for NSCLC early detection. Expression of 11 ncRNAs were analyzed by real-time polymerase chain reaction in sputum samples of 30 NSCLC patients and 30 sex- and age-matched cancer-free controls. Stability of endogenous microRNAs (miRNAs) in sputum was evaluated after 3 and 6 days at 4°C, 6 months, and 1 year at -80°C. Nine ncRNAs showed significant differences of their expression in sputum between NSCLC patients and controls. A logistic regression model with the best prediction was built based on miR-145, miR-126, and miR-7. The composite of the three miRNAs produced 90% sensitivity and specificity in distinguishing NSCLC patients from the controls. Results indicate that miRNAs could be useful biomarkers based on their stability under various storage conditions and maintain differential changes between cancer and control groups. Moreover, measurement of miRNAs in sputum could be a noninvasive approach for detection of lung cancer.

Small nucleolar RNA Sf-15 regulates proliferation and apoptosis of Spodoptera frugiperda Sf9 cells

BACKGROUND

Small nucleolar RNAs (snoRNAs) function in guiding 2'-O-methylation and pseudouridylation of ribosomal RNAs (rRNAs) and small nuclear RNAs (snRNAs). In recent years, more and more snoRNAs have been found to play novel roles in mRNA regulation, such as pre-mRNA splicing or RNA editing. In our previous study, we found a silkworm C/D box snoRNA Bm-15 can interact with Notch receptor gene in vitro. To further study the function of Bm-15, we cloned its homolog Sf-15 from Spodoptera frugiperda and investigate the function of Sf-15 in Sf9 cells.

RESULTS

We showed that knocking down of Sf-15 can inhibit the proliferation, then induce apoptosis of insect S. frugiperda Sf9 cells, but the results were reversed when Sf-15 was overexpressed. De novo sequencing of transcriptome of Sf9 cells showed that the expression of 21 apoptosis-related genes were increased upon Sf-15 repression. Further analysis showed that a Ca²⁺-induced cell death pathway gene Cn (PPP3C, the serine/threonine-protein phosphatase 2B catalytic subunit), was significantly increased upon Sf-15 depression but decreased when Sf-15 was overexpressed, which indicated that Cn might be a potential target of Sf-15.

CONCLUSIONS

We conclude that C/D box snoRNA Sf-15 can participate in apoptosis through regulating the expression of Ca²⁺-induced cell death pathway gene Cn in Sf9 cells. This is the first time that we found snoRNAs exhibiting dual functions in insect, which reveals a novel layer of ncRNA modulation in cell growth and death.

DNA methylation signature of smoking in lung cancer is enriched for exposure signatures in newborn and adult blood

Smoking impacts DNA methylation genome-wide in blood of newborns from maternal smoking during pregnancy and adults from personal smoking. We compared smoking-related DNA methylation in lung adenocarcinoma (61 never smokers, 91 current smokers, and 238 former smokers) quantified with the Illumina450k BeadArray in The Cancer Genome Atlas with published large consortium meta-analyses of newborn and adult blood. We assessed whether CpG sites related to smoking in blood from newborns and adults were enriched in the lung adenocarcinoma methylation signal. Testing CpGs differentially methylated by smoke exposure, we identified 296 in lung adenocarcinoma meeting a P < 10-4 cutoff, while previous meta-analyses identified 3,042 in newborn blood, and 8,898 in adult blood meeting the same P < 10-4 cutoff. Lung signals were highly enriched for those seen in newborn (24 overlapping CpGs, Penrichment = 1.2 × 10-18) and adult blood (66 overlapping CpGs, Penrichment = 1.2 × 10-48). The 105 genes annotated to CpGs differentially methylated in lung tumors, but not blood, were enriched for RNA processing ontologies. Some epigenetic alterations associated with cigarette smoke exposure are tissue specific, but others are common across tissues. These findings support the value of blood-based methylation biomarkers for assessing exposure effects in target tissues.

C/D box snoRNAs in viral infections: RNA viruses use old dogs for new tricks

C/D box snoRNAs (SNORDs) are a highly expressed class of non-coding RNAs. Besides their well-established role in rRNA modification, C/D box snoRNAs form protein complexes devoid of fibrillarin and regulate pre-mRNA splicing and polyadenylation of numerous genes. There is an emerging body of evidence for functional interactions between RNA viruses and C/D box snoRNAs. The infectivity of some RNA viruses depends on enzymatically active fibrillarin, and many RNA viral proteins associate with nucleolin or nucleophosmin, suggesting that viruses benefit from their cytosolic accumulation. These interactions are likely reflected by morphological changes in the nucleolus, often leading to relocalization of nucleolar proteins and ncRNAs to the cytosol that are a characteristic feature of viral infections. Knock-down studies have also shown that RNA viruses need specific C/D box snoRNAs for optimal replication, suggesting that RNA viruses benefit from gene expression programs regulated by SNORDs, or that viruses have evolved “new” uses for these humble ncRNAs to advance their prospects during infection.

Noncoding RNAs regulating cardiac muscle mass

Noncoding RNAs, including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs) play roles in the development and homeostasis of nearly every tissue of the body, including the regulation of processes underlying heart growth. Cardiac hypertrophy can be classified as either physiological (beneficial heart growth) or pathological (detrimental heart growth), the latter of which results in impaired cardiac function and heart failure and is predictive of a higher incidence of death due to cardiovascular disease. Several miRNAs have a functional role in exercise-induced cardiac hypertrophy, while both miRNAs and lncRNAs are heavily involved in pathological heart growth and heart failure. The latter have the potential to act as an endogenous sponge RNA and interact with specific miRNAs to control cardiac hypertrophy, adding another level of complexity to our understanding of the regulation of cardiac muscle mass. In addition to tissue-specific effects, ncRNA-mediated tissue cross talk occurs via exosomes. In particular, miRNAs can be internalized in exosomes and secreted from various cardiac and vascular cell types to promote angiogenesis, as well as protection and repair of ischemic tissues. ncRNAs hold promising therapeutic potential to protect the heart against ischemic injury and aid in regeneration. Numerous preclinical studies have demonstrated the therapeutic potential of ncRNAs, specifically miRNAs, for the treatment of cardiovascular disease. Most of these studies employ antisense oligonucleotides to inhibit miRNAs of interest; however, off-target effects often limit their potential to be translated to the clinic. In this context, approaches using viral and nonviral delivery tools are promising means to provide targeted delivery in vivo.

Deciphering the Role of the Non-Coding Genome in Regulating Gene-Diet Interactions

Protein encoding genes constitute a small fraction of mammalian genomes. In addition to the protein coding genes, there are other functional units within the genome that are transcribed, but not translated into protein, the so called non-coding RNAs. There are many types of non-coding RNAs that have been identified and shown to have important roles in regulating gene expression either at the transcriptional or post-transcriptional level. A number of recent studies have highlighted that dietary manipulation in mammals can influence the expression or function of a number of classes of non-coding RNAs that contribute to the protein translation machinery. The identification of protein translation as a common target for nutritional regulation underscores the need to investigate how this may mechanistically contribute to phenotypes and diseases that are modified by nutritional intervention. Finally, we describe the state of the art and the application of emerging ‘-omics’ technologies to address the regulation of protein translation in response to diet.

Dual biomarkers long non-coding RNA GAS5 and microRNA-34a co-expression signature in common solid tumors

Accumulating evidence indicates that non-coding RNAs including microRNAs (miRs) and long non-coding RNAs (lncRNAs) are aberrantly expressed in cancer, providing promising biomarkers for diagnosis, prognosis and/or therapeutic targets. We aimed in the current work to quantify the expression profile of miR-34a and one of its bioinformatically selected partner lncRNA growth arrest-specific 5 (GAS5) in a sample of Egyptian cancer patients, including three prevalent types of cancer in our region; renal cell carcinoma (RCC), glioblastoma (GB), and hepatocellular carcinoma (HCC) as well as to correlate these expression profiles with the available clinicopathological data in an attempt to clarify their roles in cancer. Quantitative real-time polymerase chain reaction analysis was applied. Different bioinformatics databases were searched to confirm the potential miRNAs-lncRNA interactions of the selected ncRNAs in cancer pathogenesis. The tumor suppressor lncRNA GAS5 was significantly under-expressed in the three types of cancer [0.08 (0.006-0.38) in RCC, p <0.001; 0.10 (0.003-0.89) in GB, p < 0.001; and 0.12 (0.015-0.74) in HCC, p < 0.001]. However, levels of miR-34a greatly varied according to the tumor type; it displayed an increased expression in RCC [4.05 (1.003-22.69), p <0.001] and a decreased expression in GB [0.35 (0.04-0.95), p <0.001]. Consistent to the computationally predicted miRNA-lncRNA interaction, negative correlations were observed between levels of GAS5 and miR-34a in RCC samples (r = -0.949, p < 0.001), GB (r = -0.518, p < 0.001) and HCC (r = -0.455, p = 0.013). Kaplan-Meier curve analysis revealed that RCC patients with down-regulated miR-34a levels had significantly poor overall survival than their corresponding (p < 0.05). Hierarchical clustering analysis showed RCC patients could be clustered by GAS5 and miR-34a co-expression profile. Our results suggest potential applicability of GAS5 and miR-34a with other conventional markers for various types of cancer. Further functional validation studies are warranted to confirm miR-34a/GAS5 interplay in cancer.

LncRNA SNHG17 promotes gastric cancer progression by epigenetically silencing of p15 and p57

Long noncoding RNAs (lncRNA) are attractive biomarkers and therapeutic targets because of their disease- and stage-restricted expression. Small nucleolar RNA host gene 17 (SNHG17) belongs to a large family of noncoding genes hosting small RNAs, with its expression pattern and biological function not clarified in gastric cancer (GC). Thus, we conducted this study to investigate the functional significance and the underlying mechanisms of SNHG17 in GC progression. Our results showed that SNHG17 expression was upregulated in GC tissues and cells, and its high expression was significantly correlated with increased invasion depth, lymphatic metastasis, and advanced TNM stage. The expression of plasma SNHG17 was also found upregulated in patients with GC compared with healthy controls, with a moderate accuracy for diagnosis of GC (area under the receiver operating characteristic curve = 0.748; 95% CI, 0.666-0.830). Gain- and loss-of-function of SNHG17 revealed that SNHG17 promoted GC cell proliferation, cell cycle progression, invasion, and migration and inhibited apoptosis. Mechanistic investigations showed that SNHG17 was associated with polycomb repressive complex 2 and that this association was required for epigenetic repression of cyclin-dependent protein kinase inhibitors, including p15 and p57, thus contributing to the regulation of GC cell cycle and proliferation. Furthermore, rescue experiments indicated that SNHG17 functioned as an oncogene via activating enhancer of zeste homolog 2 in GC cells. Our study provides a new perspective for SNHG17 acting as a noncoding oncogene in GC tumorigenesis, and it may serve as a novel early diagnostic marker and potential target for the treatment of GC.

Sno-derived RNAs are prevalent molecular markers of cancer immunity

Small nucleolar RNAs (snoRNAs) constitute a family of non-coding RNAs that are classically known as guide RNAs for processing and modification of ribosomal RNAs. Recently, it was discovered that snoRNAs can be further processed into sno-derived RNAs (sdRNAs), some of which are known to exhibit microRNA-like properties. SdRNAs have been implicated in human cancer; however, a systems-level sdRNA landscape in human cancers is lacking. Through integrative analysis of ~22 nt size-selected smRNA-seq datasets from 10,262 patient samples across 32 cancer types, we mapped a pan-cancer sdRNAome and interrogated its signatures in multiple clinically relevant features, particularly cancer immunity and clinical outcome. Aggregating sdRNA abundances by parental snoRNAs, these expression signatures alone are sufficient to distinguish patients with distinct cancer types. Interestingly, a large panel of sdRNAs are significantly correlated with features of the tumor-immune microenvironment, such as immunosuppressive markers, CD8+ T cell infiltration, cytolytic T cell activity, and tumor vasculature. A set of individual sdRNAs with tumor-immune signatures can also stratify patient survival. These findings implicate snoRNAs and their derivative sdRNAs as a class of prevalent non-coding molecular markers of human cancer immunity.

Targeting RNA in mammalian systems with small molecules

The recognition of RNA functions beyond canonical protein synthesis has challenged the central dogma of molecular biology. Indeed, RNA is now known to directly regulate many important cellular processes, including transcription, splicing, translation, and epigenetic modifications. The misregulation of these processes in disease has led to an appreciation of RNA as a therapeutic target. This potential was first recognized in bacteria and viruses, but discoveries of new RNA classes following the sequencing of the human genome have invigorated exploration of its disease-related functions in mammals. As stable structure formation is evolving as a hallmark of mammalian RNAs, the prospect of utilizing small molecules to specifically probe the function of RNA structural domains and their interactions is gaining increased recognition. To date, researchers have discovered bioactive small molecules that modulate phenotypes by binding to expanded repeats, microRNAs, G-quadruplex structures, and RNA splice sites in neurological disorders, cancers, and other diseases. The lessons learned from achieving these successes both call for additional studies and encourage exploration of the plethora of mammalian RNAs whose precise mechanisms of action remain to be elucidated. Efforts toward understanding fundamental principles of small molecule-RNA recognition combined with advances in methodology development should pave the way toward targeting emerging RNA classes such as long noncoding RNAs. Together, these endeavors can unlock the full potential of small molecule-based probing of RNA-regulated processes and enable us to discover new biology and underexplored avenues for therapeutic intervention in human disease. This article is categorized under: RNA Methods > RNA Analyses In Vitro and In Silico RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions RNA in Disease and Development > RNA in Disease.

Stromal fibroblasts from perimenopausal endometrium exhibit a different transcriptome than those from the premenopausal endometrium

Human endometrium undergoes extensive regeneration on a cyclic basis in premenopausal women and likely occurs through the contribution of stem/progenitor cells. Menopause results in the permanent cessation of menstrual cycles and is preceded by perimenopause, a period of several years in which endocrine and biological changes occur and is a period of risk for endometrial proliferative disorders. The objectives of this study were to identify endometrial mesenchymal stem cells (eMSC) and endometrial stromal fibroblasts (eSF) in endometrium of perimenopausal women and perform expression profile analysis of perimenopausal eMSC and eSF to gain insight into the biology of stem/progenitor and lineage cell populations during the transition to menopause. Endometrial tissue was collected from perimenopausal and premenopausal women (n = 9 each). Microarray analysis was performed on fluorescence-activated cell sorting-isolated eSF and eMSC, and data were validated by quantitative real-time PCR. Principal component analysis showed that cells clustered into three distinct groups in 3-dimensional space: perimenopausal eMSC and premenopausal eMSC clustered together, while perimenopausal eSF and premenopausal eSF formed two discrete clusters separate from eMSC. Hierarchical clustering revealed a branching pattern consistent with principle clustering analysis results, indicating that eMSC from premenopausal and perimenopausal women exhibit similar transcriptomic signatures. Pathway analysis revealed dysregulation of cytoskeleton, proliferation, and survival pathways in perimenopausal vs. premenopausal eSF. These data demonstrate that cell populations have altered gene expression in perimenopausal vs. premenopausal endometrium, and that perimenopausal eSF had altered pathway activation when compared to premenopausal eSF. This study provides insight into aging endometrium with relevance to function in reproductively older women.

The Role of scaRNAs in Adjusting Alternative mRNA Splicing in Heart Development

Congenital heart disease (CHD) is a leading cause of death in children <1 year of age. Despite intense effort in the last 10 years, most CHDs (~70%) still have an unknown etiology. Conotruncal based defects, such as Tetralogy of Fallot (TOF), a common complex of devastating heart defects, typically requires surgical intervention in the first year of life. We reported that the noncoding transcriptome in myocardial tissue from children with TOF is characterized by significant variation in levels of expression of noncoding RNAs, and more specifically, a significant reduction in 12 small cajal body-associated RNAs (scaRNAs) in the right ventricle. scaRNAs are essential for the biochemical modification and maturation of small nuclear RNAs (spliceosomal RNAs), which in turn are critical components of the spliceosome. This is particularly important because we also documented that splicing of mRNAs that are critical for heart development was dysregulated in the heart tissue of infants with TOF. Furthermore, we went on to show, using the zebrafish model, that altering the expression of these same scaRNAs led to faulty mRNA processing and heart defects in the developing embryo. This review will examine how scaRNAs may influence spliceosome fidelity in exon retention during heart development and thus contribute to regulation of heart development.