LncRNA UCA1, Upregulated in CRC Biopsies and Downregulated in Serum Exosomes, Controls mRNA Expression by RNA-RNA Interactions

Functional roles of conserved lncRNAs and circRNAs in eukaryotes

Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) have emerged as critical regulators in essentially all biological processes across eukaryotes. They exert their functions through chromatin remodeling, transcriptional regulation, interacting with RNA-binding proteins (RBPs), serving as microRNA sponges, etc. Although non-coding RNAs are typically more species-specific than coding RNAs, a number of well-characterized lncRNA (such as XIST and NEAT1) and circRNA (such as CDR1as and ciRS-7) are evolutionarily conserved. The studies on conserved lncRNA and circRNAs across multiple species could facilitate a comprehensive understanding of their roles and mechanisms, thereby overcoming the limitations of single-species studies. In this review, we provide an overview of conserved lncRNAs and circRNAs, and summarize their conserved roles and mechanisms.

Empowering Exosomes with Aptamers for Precision Theranostics

As information messengers for cell-to-cell communication, exosomes, typically small membrane vesicles (30-150 nm), play an imperative role in the physiological and pathological processes of living systems. Accumulating studies have demonstrated that exosomes are potential biological candidates for theranostics, including liquid biopsy-based diagnosis and drug delivery. However, their clinical applications are hindered by several issues, especially their unspecific detection and insufficient targeting ability. How to upgrade the accuracy of exosome-based theranostics is being widely explored. Aptamers, benefitting from their admirable characteristics, are used as excellent molecular recognition elements to empower exosomes for precision theranostics. With high affinity against targets and easy site-specific modification, aptamers can be incorporated with platforms for the specific detection of exosomes, thus providing opportunities for advancing disease diagnostics. Furthermore, aptamers can be tailored and functionalized on exosomes to enable targeted therapeutics. Herein, this review emphasizes the empowering of exosomes by aptamers for precision theranostics. A brief introduction of exosomes and aptamers is provided, followed by a discussion of recent progress in aptamer-based exosome detection for disease diagnosis, and the emerging applications of aptamer-functionalized exosomes for targeted therapeutics. Finally, current challenges and opportunities in this research field are presented.

Panel of serum long non-coding RNAs as potential non-invasive biomarkers for gallbladder carcinoma

Gallbladder carcinoma (GBC) is a common malignancy and is usually diagnosed in the late stages of the disease. The identification of new effective early diagnostic biomarkers could represent an effective approach in reducing mortality in GBC. Altered expression of long non-coding RNAs (lncRNAs) is believed to be associated with the emergence and development of GBC. Our study aims to identify the expression of a range of circulating lncRNAs, including HOTAIR, ANRIL, H19, CCAT1 and MEG3, in matched serum and tissues of GBC for diagnosis and its association with clinicopathological features. The case and control study included matched serum and tissues from 63 GBC, 19 cholecystitis (CC), and 46 normal controls (NC). RNA extraction and cDNA synthesis from serum and fresh tissue match were performed using commercially available kits. Relative expression was assessed using SYBR Green real-time quantitative polymerase chain reaction. Circulating lncRNA levels including HOTAIR, ANRIL and H19 were upregulated in serum samples, while MEG3 and CCAT1 were downregulated in GBC compared to controls. The trend towards upregulation and downregulation was comparable in the tissue. HOTAIR and MEG3 levels were significantly different between serum CC and early-stage GBC (p = 0.0373, 0.0020), while H19 was significantly upregulated comparing early-stage GBC to advanced-stage GBC (p = 0.018). The expression of ANRIL was significant with M stage (p = 0.0488), H19 with stage (p = 0.009), M stage (p=<0.0001) & stage (0.009) and CCAT1 with M stage (0.044). When distinguishing GBC and NC, AUC for HOTAIR was 0.75, ANRIL 0.78, H19 0.74, CCAT1 0.80 and 0.96 for MEG3. The combination sensitivity for lncRNAs ranged from 84.13% (CI: 72.74-92.12%) to 100.0% (CI: 94.31-100.0%). Significant diagnostic value in discriminating pathologic stage was observed for ANRIL and MEG3 (p = 0.022, p = 0.0005). LncRNA show a significant change in expression in GBC and in discrimination of early stage from late-stage disease. The detection of 2 lncRNAs in panels, in coordination with radiology, could represent a potential serum-based biomarker for early-stage GBC diagnosis.

Extracellular vesicle biomarkers in circulation for colorectal cancer detection: a systematic review and meta-analysis

We provided an overview which evaluated the diagnostic performance of circulation EV biomarkers for CRC from PubMed, Medline, and Web of Science until 21 August 2022.Weidentified 48 studies that involved 7727 participants and evaluated 162 plasma/serum individual EV biomarkers including 117 RNAs and 45 proteins, as well as 45 EV biomarker panels for CRC detection. 12 studies evaluated the diagnostic performance of EV biomarkers for early CRC. The summarized sensitivity, specificity, and AUC value of individual EV RNAs and EV RNA panels were 76%, 75%, 0.87 and 82%, 79% and 0.90, respectively. Meanwhile, those of individual EV proteins and EV protein panels were 85%, 84%, 0.92 and 87%, 83%, 0.92, respectively. These results indicated that EV biomarker panels revealed superior diagnostic performance than the corresponding individual biomarkers. In early CRC, EV biomarkers showed available diagnostic value with the sensitivity, specificity, and AUC value of 80%, 75%, and 0.89.In subgroup analyses, EV miRNAs and LncRNAs held similar diagnostic value with the sensitivity, specificity and AUC value of 75%, 78%, 0.90 and 79%, 72%, 0.83, which was highly consistent with the whole EV RNAs. Significantly, the diagnostic values of EV miRNAs in plasma were marginally higher than those based on serum. In detail, the sensitivity, specificity, and AUC values were 79%, 81%, and 0.92 in plasma, as well as 74%, 77%, and 0.88 in serum, respectively. Therefore, circulation EV biomarkers could be considered as a promising biomarker for the early detection of CRC.

Cancer-derived exosomes as novel biomarkers in metastatic gastrointestinal cancer

Gastrointestinal cancer (GIC) is the most prevalent and highly metastatic malignant tumor and has a significant impact on mortality rates. Nevertheless, the swift advancement of contemporary technology has not seamlessly aligned with the evolution of detection methodologies, resulting in a deficit of innovative and efficient clinical assays for GIC. Given that exosomes are preferentially released by a myriad of cellular entities, predominantly originating from neoplastic cells, this confers exosomes with a composition enriched in cancer-specific constituents. Furthermore, exosomes exhibit ubiquitous presence across diverse biological fluids, endowing them with the inherent advantages of non-invasiveness, real-time monitoring, and tumor specificity. The unparalleled advantages inherent in exosomes render them as an ideal liquid biopsy biomarker for early diagnosis, prognosticating the potential development of GIC metastasis.In this review, we summarized the latest research progress and possible potential targets on cancer-derived exosomes (CDEs) in GIC with an emphasis on the mechanisms of exosome promoting cancer metastasis, highlighting the potential roles of CDEs as the biomarker and treatment in metastatic GIC.

Emerging Roles of Small Extracellular Vesicles in Gastrointestinal Cancer Research and Therapy

Discovered in the late eighties, sEVs are small extracellular nanovesicles (30-150 nm diameter) that gained increasing attention due to their profound roles in cancer, immunology, and therapeutic approaches. They were initially described as cellular waste bins; however, in recent years, sEVs have become known as important mediators of intercellular communication. They are secreted from cells in substantial amounts and exert their influence on recipient cells by signaling through cell surface receptors or transferring cargos, such as proteins, RNAs, miRNAs, or lipids. A key role of sEVs in cancer is immune modulation, as well as pro-invasive signaling and formation of pre-metastatic niches. sEVs are ideal biomarker platforms, and can be engineered as drug carriers or anti-cancer vaccines. Thus, sEVs further provide novel avenues for cancer diagnosis and treatment. This review will focus on the role of sEVs in GI-oncology and delineate their functions in cancer progression, diagnosis, and therapeutic use.

Expanding the horizon of EV-RNAs: LncRNAs in EVs as biomarkers for disease pathways

Extracellular vesicles (EVs) are membrane-bound nanoparticles with different types of cargo released by cells and postulated to mediate functions such as intercellular communications. Recent studies have shown that long non-coding RNAs (lncRNAs) or their fragments are present as cargo within EVs. LncRNAs are a heterogeneous group of RNA species with a length exceeding 200 nucleotides with diverse functions in cells based on their localization. While lncRNAs are known for their important functions in cellular regulation, their presence and role in EVs have only recently been explored. While certain studies have observed EV-lncRNAs to be tissue-and disease-specific, it remains to be determined whether or not this is a global observation. Nonetheless, these molecules have demonstrated promising potential to serve as new diagnostic and prognostic biomarkers. In this review, we critically evaluate the role of EV-derived lncRNAs in several prevalent diseases, including cancer, cardiovascular diseases, and neurodegenerative diseases, with a specific focus on their role as biomarkers.

The role of CDR1as/ciRS-7 in cardio-cerebrovascular diseases

Cerebellar degeneration-related protein 1 antisense RNA (CDR1as), also known as ciRS-7, is a circular natural antisense transcript of CDR1. It is a widely studied and powerful representative of circular RNAs. Based on its widely reported role in cancer, CDR1as is considered one of the most promising biomarkers for diagnosing and treating tumours. However, some recent studies have extensively focused on its regulatory role in cardio-cerebrovascular diseases instead of in tumours. Studies have shown that CDR1as plays a unique role in the occurrence of cardio-cerebrovascular diseases; thus, it may be a potential target for preventing and treating cardio-cerebrovascular diseases. Furthermore, CDR1as has also been found to be related to signal transduction pathways related to inflammatory response, oxidative stress, etc., which may reveal its potential mechanism in cardio-cerebrovascular diseases. However, there is no literature to summarize the role and possible mechanism of CDR1as in cardio-cerebrovascular diseases. Therefore, in the present review, we have comprehensively summarised the latest progress in the biological characteristics, development processes, regulatory mechanisms, and roles of CDR1as in cardio-cerebrovascular diseases, aiming to provide a reference and guidance for future studies.

Current advances in detecting genetic and epigenetic biomarkers of colorectal cancer

Colorectal carcinoma (CRC) is the third most common cancer in terms of diagnosis and the second in terms of mortality. Recent studies have shown that various proteins, extracellular vesicles (i.e., exosomes), specific genetic variants, gene transcripts, cell-free DNA (cfDNA), circulating tumor DNA (ctDNA), microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and altered epigenetic patterns, can be used to detect, and assess the prognosis of CRC. Over the last decade, a plethora of conventional methodologies (e.g., polymerase chain reaction [PCR], direct sequencing, enzyme-linked immunosorbent assay [ELISA], microarray, in situ hybridization) as well as advanced analytical methodologies (e.g., microfluidics, electrochemical biosensors, surface-enhanced Raman spectroscopy [SERS]) have been developed for analyzing genetic and epigenetic biomarkers using both optical and non-optical tools. Despite these methodologies, no gold standard detection method has yet been implemented that can analyze CRC with high specificity and sensitivity in an inexpensive, simple, and time-efficient manner. Moreover, until now, no study has critically reviewed the advantages and limitations of these methodologies. Here, an overview of the most used genetic and epigenetic biomarkers for CRC and their detection methods are discussed. Furthermore, a summary of the major biological, technical, and clinical challenges and advantages/limitations of existing techniques is also presented.

PHLPP2: A Prognostic Biomarker in Adenocarcinoma of the Rectum

BACKGROUND/AIMS

Adenocarcinoma of the rectum (READ) is typically diagnosed at advanced stages due to a lack of early-onset spe- cific features.

MATERIALS AND METHODS

The study used bioinformatics analysis of READ ribonucleic acid sequencing data from The Cancer Genome Atlas database to identify differentially expressed genes (DEGs). Overlapping genes between DEGs and autophagy-associated genes were screened for prognosis-associated DEGs, which were then validated in the OncoLnc database.

RESULTS

A total of 129 autophagy-associated DEGs were identified, with 17 genes found to be associated with READ prognosis. Multivariate Cox regression analysis revealed that only the PHLPP2 gene was significantly associated with READ prognosis (hazard ratio = 0.442, P = .026), and its low expression correlated with low survival in patients with brain lower-grade glioma (P = .00623) and pancreatic adenocarcinoma (P = .00109).

CONCLUSIONS

PHLPP2 expression may serve as a READ-specific prognostic biomarker and is involved in the PI3K-Akt signaling pathway.

Noncoding RNA as an influential epigenetic modulator with promising roles in cancer therapeutics

The epigenetic landscape has an important role in cellular homeostasis and its deregulation leads to cancer. Noncoding (nc)RNA networks function as major regulators of cellular epigenetic hallmarks via regulation of vital processes, such as histone modification and DNA methylation. They are integral intracellular components affecting multiple oncogenic pathways. Thus, it is important to elucidate the effects of ncRNA networks on epigenetic programming that lead to the initiation and progression of cancer. In this review, we summarize the effects of epigenetic modification influenced by ncRNA networks and crosstalk between diverse classes of ncRNA, which could aid the development of patient-specific cancer therapeutics targeting ncRNAs, thereby altering cellular epigenetics.

RNA-RNA competitive interactions: a molecular civil war ruling cell physiology and diseases

The idea that proteins are the main determining factors in the functioning of cells and organisms, and their dysfunctions are the first cause of pathologies, has been predominant in biology and biomedicine until recently. This protein-centered view was too simplistic and failed to explain the physiological and pathological complexity of the cell. About 80% of the human genome is dynamically and pervasively transcribed, mostly as non-protein-coding RNAs (ncRNAs), which competitively interact with each other and with coding RNAs generating a complex RNA network regulating RNA processing, stability, and translation and, accordingly, fine-tuning the gene expression of the cells. Qualitative and quantitative dysregulations of RNA-RNA interaction networks are strongly involved in the onset and progression of many pathologies, including cancers and degenerative diseases. This review will summarize the RNA species involved in the competitive endogenous RNA network, their mechanisms of action, and involvement in pathological phenotypes. Moreover, it will give an overview of the most advanced experimental and computational methods to dissect and rebuild RNA networks.

Genomic and Transcriptomic Research in the Discovery and Application of Colorectal Cancer Circulating Markers

Colorectal cancer (CRC) is the most frequently occurring malignancy in the world. However, the mortality from CRC can be reduced through early diagnostics, selection of the most effective treatment, observation of the therapy success, and the earliest possible diagnosis of recurrences. A comprehensive analysis of genetic and epigenetic factors contributing to the CRC development is needed to refine diagnostic, therapeutic, and preventive strategies and to ensure appropriate decision making in managing specific CRC cases. The liquid biopsy approach utilizing circulating markers has demonstrated its good performance as a tool to detect the changes in the molecular pathways associated with various cancers. In this review, we attempted to brief the main tendencies in the development of circulating DNA and RNA-based markers in CRC such as cancer-associated DNA mutations, DNA methylation changes, and non-coding RNA expression shifts. Attention is devoted to the existing circulating nucleic acid-based CRC markers, the possibility of their application in clinical practice today, and their future improvement. Approaches to the discovery and verification of new markers are described, and the existing problems and potential solutions for them are highlighted.

Recent advances of exosomal circRNAs in cancer and their potential clinical applications

Circular RNA (circRNA) is a type of non-coding RNA that forms a covalently closed, uninterrupted loop. The expression of circRNA differs among cell types and tissues, and various circRNAs are aberrantly expressed in a variety of diseases, including cancer. Aberrantly expressed circRNAs contribute to disease progression by acting as microRNA sponges, functional protein sponges, or novel templates for protein translation. Recent studies have shown that circRNAs are enriched in exosomes. Exosomes are spherical bilayer vesicles released by cells into extracellular spaces that mediate intercellular communication by delivering cargoes. These cargoes include metabolites, proteins, lipids, and RNA molecules. Exosome-mediated cell-cell or cell-microenvironment communications influence the progression of carcinogenesis by regulating cell proliferation, angiogenesis, metastasis as well as immune escape. In this review, we summarize the current knowledge about exosomal circRNAs in cancers and discuss their specific functions in tumorigenesis. Additionally, we discuss the potential value of exosomal circRNAs as diagnostic biomarkers and the potential applications of exosomal circRNA-based cancer therapy.

Progress of regulatory RNA in small extracellular vesicles in colorectal cancer

Colorectal cancer (CRC) is the second most common malignant tumor of the gastrointestinal tract with the second highest mortality rate and the third highest incidence rate. Early diagnosis and treatment are important measures to reduce CRC mortality. Small extracellular vesicles (sEVs) have emerged as key mediators that facilitate communication between tumor cells and various other cells, playing a significant role in the growth, invasion, and metastasis of cancer cells. Regulatory RNAs have been identified as potential biomarkers for early diagnosis and prognosis of CRC, serving as crucial factors in promoting CRC cell proliferation, invasion and metastasis, angiogenesis, drug resistance, and immune cell differentiation. This review provides a comprehensive summary of the vital role of sEVs as biomarkers in CRC diagnosis and their potential application in CRC treatment, highlighting their importance as a promising avenue for further research and clinical translation.

A tale of exosomes and their implication in cancer

Cancer is a cause of high deaths worldwide and also a huge burden for the health system. Cancer cells have unique properties such as a high rate of proliferation, self-renewal, metastasis, and treatment resistance, therefore, the development of novel diagnoses of cancers is a tedious task. Exosomes are secreted by virtually all cell types and have the ability to carry a multitude of biomolecules crucial for intercellular communication, hence, contributing a crucial part in the onset and spread of cancer. These exosomal components can be utilized in the development of markers for diagnostic and prognostic purposes for various cancers. This review emphasized primarily the following topics: exosomes structure and functions, isolation and characterization strategies of exosomes, the role of exosomal contents in cancer with a focus in particular on noncoding RNA and protein, exosomes, and the cancer microenvironment interactions, cancer stem cells, and tumor diagnosis and prognosis based on exosomes.

Non-coding RNAs are correlated to TGF-β receptor type 2 in patients with colorectal cancer

BACKGROUND

Multiple molecular expression alterations, particularly in non-coding RNAs, play fundamental roles in the regulations of cellular processes and may relate to the occurrence and progression of colorectal cancer (CRC). In the present study, we investigated the associations between TGFBR2, miR20a-5p and long non-coding RNA (lncRNA) LAMTOR5-AS1 in CRC patients.

METHODS

Colorectal cancer and adjacent normal tissue samples (n = 34) were prepared from CRC patients. The associations between TGFBR2, miR20a-5p and lncRNA LAMTOR5-AS1 were predicted using bioinformatics tools. The expression levels of TGFBR2, miR20a-5p and lncRNA LAMTOR5-AS1 were measured using a quantitative real-time polymerase chain reaction technique. The TGFBR2 protein values were measured by western blotting. The clinical importance of lncRNA LAMTOR5-AS1 was assessed using receiver operating characteristic curve.

RESULTS

The up-regulated levels of TGFBR2 (p = 0.02), TGFBR2 protein (p = 0.008) and lncRNA LAMTOR5-AS1 (p = 0.02) were significantly observed in CRC tissues compared to the adjacent normal tissues. The miR20a-5p expression level (p = 0.009) was downregulated in CRC tissues. In addition, the miR20a-5p expression level was inversely correlated to the TGFBR2 gene (r²  = 0.88, p < 0.0001), protein (r²  = 0.95, p < 0.0001) and lncRNA LAMTOR5-AS1 gene (r²  = 0.93, p < 0.0001) expression levels. Based on the area under curve, the increase of lncRNA LAMTOR5-AS1 expression level with a sensitivity of 64.52% and specificity of 65.52% was considered in CRC patients.

CONCLUSIONS

We propose that miR20a-5p is inversely related to long non-coding RNA (lncRNA) LAMTOR5-AS, such that it may be involved in the regulation of TGFBR2 expression level in CRC patients.

Exosomes in Colorectal Cancer: From Physiology to Clinical Applications

Exosomes are nanosized vesicles that have been found to be involved in many diseases. Exosomes can mediate communication between cells in a variety of ways. Certain types of mediators derived from cancer cells can play a crucial role in the development of this pathology, promoting tumor growth, invasion, metastasis, angiogenesis, and immunomodulation. Exosomes in the bloodstream show promise as a future tool for detecting cancer at an early stage. The sensitivity and specificity of clinical exosome biomarkers need to be enhanced. Knowledge of exosomes is not only important for understanding the significance of cancer progression but also for providing clinicians with useful information for the diagnosis, treatment, and discovery of methods to prevent cancer from recurring. The widespread adoption of diagnostic tools based on exosomes may revolutionize cancer diagnosis and treatment. Tumor metastasis, chemoresistance, and immunity are all aided by exosomes. A potential new approach to cancer therapy involves preventing metastasis by inhibiting miRNA intracellular signaling and blocking the formation of pre-metastatic niches. For colorectal patients, exosomes represent a promising area of investigation for improving the diagnosis, treatment, and management. Reported data demonstrate that the serum expression level of certain exosomal miRNA is significantly higher in primary colorectal cancer patients. The present review discusses mechanisms and clinical implications of exosomes in colorectal cancer.

Exosomes as a Source of Biomarkers for Gastrointestinal Cancers

Exosomes are small, lipid-bilayer bound extracellular vesicles of 40-160 nanometers in size that carry important information for intercellular communication. Exosomes are produced more by tumor cells than normal cells and carry tumor-specific content, such as DNA, RNA, and proteins, which have been implicated in tumorigenesis, tumor progression, and treatment response. Due to the critical role of exosomes in cancer development and progression, they can be exploited to develop specific biomarkers and therapeutic targets. Since exosomes are present in various biofluids, such as blood, saliva, urine, and peritoneal fluid, they are ideally suited to be developed as liquid biopsy tools for early diagnosis, molecular profiling, disease surveillance, and treatment response monitoring. In the past decade, numerous studies have been published about the functional significance of exosomes in a wide variety of cancers, with a particular focus on exosome-derived RNAs and proteins as biomarkers. In this review, utilizing human studies on exosomes, we highlight their potential as diagnostic, prognostic, and predictive biomarkers in gastrointestinal cancers.

Exosomal lncRNAs in gastrointestinal cancer

Gastrointestinal cancer (GIC) remains a leading cause of morbidity and mortality worldwide. Unfortunately, these cancers are diagnosed in advanced metastatic stages due to lack of reliable biomarkers that are sufficiently specific and sensitive in early disease. There has been growing evidence that circulating exosomes can be used to diagnose cancer non-invasively with limited risks and side effects. Furthermore, exosomal long non-coding RNAs (lncRNAs) are emerging as a new class of promising biomarkers in cancer. This review provides an overview of the extraction and detection of exosomal lncRNAs with a focus on their potential role in GIC.

Transcription factor AP-2α activates RNA polymerase III-directed transcription and tumor cell proliferation by controlling expression of c-MYC and p53

Deregulation of transcription factor AP2 alpha (TFAP2A) and RNA polymerase III (Pol III) products is associated with tumorigenesis. However, the mechanism underlying this event is not fully understood and the connection between TFAP2A and Pol III-directed transcription has not been investigated. Here, we report that TFAP2A functions as a positive factor in the regulation of Pol III-directed transcription and cell proliferation. We found TFAP2A is also required for the activation of Pol III transcription induced by the silencing of filamin A, a well-known cytoskeletal protein and an inhibitor in Pol III-dependent transcription identified previously. Using a chromatin immunoprecipitation technique, we showed TFAP2A positively modulates the assembly of Pol III transcription machinery factors at Pol III-transcribed gene loci. We found TFAP2A can activate the expression of Pol III transcription-related factors, including BRF1, GTF3C2, and c-MYC. Furthermore, we demonstrate TFAP2A enhances expression of MDM2, a negative regulator of tumor suppressor p53, and also inhibits p53 expression. Finally, we found MDM2 overexpression can rescue the inhibition of Pol III-directed transcription and cell proliferation caused by TFAP2A silencing. In summary, we identified that TFAP2A can activate Pol III-directed transcription by controlling multiple pathways, including general transcription factors, c-MYC and MDM2/p53. The findings from this study provide novel insights into the regulatory mechanisms of Pol III-dependent transcription and cancer cell proliferation.

Liquid biopsy approaches and immunotherapy in colorectal cancer for precision medicine: Are we there yet?

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths globally, with nearly half of patients detected in the advanced stages. This is due to the fact that symptoms associated with CRC often do not appear until the cancer has reached an advanced stage. This suggests that CRC is a cancer with a slow progression, making it curable and preventive if detected in its early stage. Therefore, there is an urgent clinical need to improve CRC early detection and personalize therapy for patients with this cancer. Recently, liquid biopsy as a non-invasive or nominally invasive approach has attracted considerable interest for its real-time disease monitoring capability through repeated sample analysis. Several studies in CRC have revealed the potential for liquid biopsy application in a real clinical setting using circulating RNA/miRNA, circulating tumor cells (CTCs), exosomes, etc. However, Liquid biopsy still remains a challenge since there are currently no promising results with high specificity and specificity that might be employed as optimal circulatory biomarkers. Therefore, in this review, we conferred the plausible role of less explored liquid biopsy components like mitochondrial DNA (mtDNA), organoid model of CTCs, and circulating cancer-associated fibroblasts (cCAFs); which may allow researchers to develop improved strategies to unravel unfulfilled clinical requirements in CRC patients. Moreover, we have also discussed immunotherapy approaches to improve the prognosis of MSI (Microsatellite Instability) CRC patients using neoantigens and immune cells in the tumor microenvironment (TME) as a liquid biopsy approach in detail.

LncRNA-UCA1 regulates lung adenocarcinoma progression through competitive binding to miR-383

The present study aimed to assess the role of the long non-coding RNA-urothelial cancer associated 1 (lncRNA-UCA1)/microRNA (miR)-383/vascular endothelial growth factor A (VEGFA) axis in regulating lung adenocarcinoma physiology through in vivo and in vitro experiments. The expression profile of lncRNA-UCA1 was analyzed by genome-wide analysis from GSE146459. The cell counting Kit-8, colony formation, wound healing and transwell assays were performed to evaluate the effects of lncRNA-UCA1 in vitro. In addition, luciferase reporter assays were performed to confirm the binding site. The expression levels of miR-383 and VEGFA in tumor cells were measured using reverse transcription-quantitative PCR. HCC-78 was also transfected with miR-383 mimics, inhibitors and siRNA-VEGFA before their viability was also assessed. Xenograft models were established in nude mice to investigate the tumor characteristics in vivo. The expression of lncRNA-UCA1 was significantly increased in tumor tissues and cells compared with adjacent tissues or HBE cells. Silencing lncRNA-UCA1 expression in cells resulted in a reduction in lung cancer cell viability. In addition, lncRNA-UCA1 silencing increased the expression of miR-383. Inhibiting miR-383 expression increased HCC-78 proliferation, migration and invasion, whilst reducing their apoptosis. miR-383 was shown to specifically target VEGFA to inhibit its expression at both the protein and mRNA levels. VEGFA knockdown resulted in a reduction in all aforementioned aspects of HCC-78 cell activity. In addition, inhibiting miR-383 expression led to larger tumor sizes in vivo. To conclude, the results of the study suggest that lncRNA-UCA1 can regulate the expression of miR-383 and, in turn, VEGFA.

CCAT 1- A Pivotal Oncogenic Long Non-Coding RNA in Colorectal Cancer

Colorectal cancer (CRC) is ranked as the third most common cancer and second deadliest cancer in both men and women in the world. Currently, the cure rate and 5-year survival rate of CRC patients remain relatively low. Therefore, discovering a novel molecular biomarker that can be used to improve CRC screening, diagnosis, prognosis, and treatment would be beneficial. Long non-coding RNA colon cancer-associated transcript 1 (CCAT 1) has been found overexpressed in CRC and is associated with CRC tumorigenesis and treatment outcome. CCAT 1 has a high degree of specificity and sensitivity, it is readily detected in CRC tissues and is significantly overexpressed in both premalignant and malignant CRC tissues. Besides, CCAT 1 is associated with clinical manifestation and advanced features of CRC, such as lymph node metastasis, high tumor node metastasis stage, differentiation, invasion, and distant metastasis. In addition, they can upregulate oncogenic c-MYC and negatively modulate microRNAs via different mechanisms of action. Furthermore, dysregulated CCAT 1 also enhances the chemoresistance in CRC cells while downregulation of them reverses the malignant phenotypes of cancer cells. In brief, CCAT 1 serves as a potential screening, diagnostic and prognostic biomarker in CRC, it also serves as a potential therapeutic marker to treat CRC patients.

Exosomal circRNAs: Novel biomarkers and therapeutic targets for gastrointestinal tumors

Despite the high prevalence of gastrointestinal tumors, early diagnosis and treatment of these tumors is limited by the lack of effective and specific biomarkers and therapeutic targets. Exosomes carry active molecules to mediate cell-to-cell communication, especially in the tumor microenvironment, and are promising biomarkers and therapeutic targets for cancer. Circular RNAs (circRNAs) are stably enriched in exosomes and show a unique circular structure, high stability, conservation, and tissue specificity. Exosomal circRNAs play important roles in regulating cell proliferation, metastasis, angiogenesis, metabolism, and the immune microenvironment of gastrointestinal tumors and exhibit great potential as tumor biomarkers and anti-tumor targets or tools. This review briefly introduces the characteristics and functions of circRNAs and exosomes, and systematically describes the biological roles and mechanisms of exosomal circRNAs in gastrointestinal tumors. This article also summarizes the detection methodology of exosomal circRNAs and discusses their clinical significance as biomarkers and targets for gastrointestinal tumors.

Construction of an lncRNA model for prognostic prediction of bladder cancer

OBJECTIVE

We aimed to investigate the role and potential mechanisms of long non-coding RNAs (lncRNAs) in bladder cancer (BC), as well as determine their prognostic value.

METHODS

LncRNA expression data and clinical data from BC patients were downloaded from The Cancer Genome Atlas (TCGA) database. R software was used to carry out principal component analysis (PCA), differential analysis, and prognostic analysis. Lasso regression and multivariate Cox regression analyses were performed to identify potential prognostic genes. The expression of five identified genes and their correlation with prognosis were verified using TCGA and GSE13507 datasets. In addition, quantitative real-time polymerase chain reaction (qRT-PCR) was used to confirm the expression of these five genes in cell lines (two human BC cell lines and one human bladder epithelial cell line) and tissues (84 pairs of BC tissues and the corresponding paracancerous tissues). Risk scores that had been generated from the five genes and their prognostic ability were assessed by receiver operating characteristic (ROC) and Kaplan-Meier (KM) curves. Co-expressed genes were screened by WGCNA and analyzed by GO and KEGG, while functional enrichment and immune infiltration analyses were performed using STRING ( https://cn.string-db.org/ ) and TIMER2.0 ( http://timer.cistrome.org/ ) online tools, respectively.

RESULTS

CYP4F8, FAR2P1, LINC01518, LINC01764, and DTNA were identified as potential prognostic genes. We found that these five genes were differentially expressed in BC tissue, as well as in BC cell lines, and were significantly correlated with the prognosis of BC patients. KM analysis considering risk scores as independent parameters revealed differences in overall survival (OS) by subgroups. The ROC curve revealed that a combined model consisting of all five genes had good predictive ability at 1, 3, and 5 years. GO and KEGG analyses of 567 co-expressed genes revealed that these genes were significantly associated with muscle function.

CONCLUSION

LncRNAs can be good predictors of BC development and prognosis, and may act as potential tumor markers and therapeutic targets that may be beneficial in helping clinicians decide the most effective treatment strategies.

Long non-coding RNA colon cancer-associated transcript 2: role and function in human cancers

ABSTRACT

Long non-coding RNAs (lncRNAs) are a family of non-protein-coding RNAs that span a length of over 200 nucleotides. Research reports have illustrated that lncRNAs are involved in various cellular processes and that their abnormal expression leads to the occurrence and development of various tumors. Colon cancer-associated transcript 2 (CCAT2) was first reported as an oncogene in colon cancer. LncRNA CCAT2 is abnormally expressed in hepatocellular carcinoma, cholangiocarcinoma, lung cancer, breast cancer, ovarian cancer, glioma, and other tumors. In tumor tissues, abnormally overexpressed CCAT2 can affect cell proliferation, migration, epithelial-mesenchymal transition, apoptosis, and other biological behaviors through endogenous RNAs mechanisms, various signaling pathways, transcriptional regulation, and other complex mechanisms. Additionally, the overexpression of CCAT2 is also closely related to the tumor size, tumor node metastasis (TNM) stage, survival time, and other prognostic factors, suggesting that it is a potential prognostic indicator. This article reviews the biological functions of CCAT2 and its mechanisms of action in tumors from previous studies. In this review, we attempt to provide a molecular basis for future clinical applications of lncRNA CCAT2.

circSMARCA5 Is an Upstream Regulator of the Expression of miR-126-3p, miR-515-5p, and Their mRNA Targets, Insulin-like Growth Factor Binding Protein 2 (IGFBP2) and NRAS Proto-Oncogene, GTPase (NRAS) in Glioblastoma

The involvement of non-coding RNAs (ncRNAs) in glioblastoma multiforme (GBM) pathogenesis and progression has been ascertained but their cross-talk within GBM cells remains elusive. We previously demonstrated the role of circSMARCA5 as a tumor suppressor (TS) in GBM. In this paper, we explore the involvement of circSMARCA5 in the control of microRNA (miRNA) expression in GBM. By using TaqMan^® low-density arrays, the expression of 748 miRNAs was assayed in U87MG overexpressing circSMARCA5. Differentially expressed (DE) miRNAs were validated through single TaqMan^® assays in: (i) U87MG overexpressing circSMARCA5; (ii) four additional GBM cell lines (A172; CAS-1; SNB-19; U251MG); (iii) thirty-eight GBM biopsies; (iv) twenty biopsies of unaffected brain parenchyma (UC). Validated targets of DE miRNAs were selected from the databases TarBase and miRTarbase, and the literature; their expression was inferred from the GBM TCGA dataset. Expression was assayed in U87MG overexpressing circSMARCA5, GBM cell lines, and biopsies through real-time PCR. TS miRNAs 126-3p and 515-5p were upregulated following circSMARCA5 overexpression in U87MG and their expression was positively correlated with that of circSMARCA5 (r-values = 0.49 and 0.50, p-values = 9 × 10^-5 and 7 × 10^-5, respectively) in GBM biopsies. Among targets, IGFBP2 (target of miR-126-3p) and NRAS (target of miR-515-5p) mRNAs were positively correlated (r-value = 0.46, p-value = 0.00027), while their expression was negatively correlated with that of circSMARCA5 (r-values = -0.58 and -0.30, p-values = 0 and 0.019, respectively), miR-126-3p (r-value = -0.36, p-value = 0.0066), and miR-515-5p (r-value = -0.34, p-value = 0.010), respectively. Our data identified a new GBM subnetwork controlled by circSMARCA5, which regulates downstream miRNAs 126-3p and 515-5p, and their mRNA targets IGFBP2 and NRAS.

Endoplasmic reticulum-resident protein Sec62 drives colorectal cancer metastasis via MAPK/ATF2/UCA1 axis

OBJECTIVE

Metastasis is responsible for the poor prognosis of patients with colorectal cancer (CRC), and the role of aberrant expression of endoplasmic reticulum (ER) receptors in tumour metastasis has not been fully elucidated. The aim of the study is to ensure the role of ER-resident protein Sec62 in CRC metastasis and illuminate associated molecular mechanisms.

MATERIALS AND METHODS

Bioinformatics analysis, qRT-PCR, western blot and immunohistochemistry assays were performed to evaluate the expression level and clinical significance of Sec62 in CRC. The specific role of Sec62 in CRC was identified by a series of functional experiments. We conducted RNA sequencing and rescue experiments to analyse the differentially expressed genes and identified UCA1 as a novel pro-metastasis target of Sec62 in CRC. Besides, the efficacy of MAPK/JNK inhibitor or agonist on Sec62-mediated CRC metastasis was evaluated by trans-well and wound healing assays. Finally, luciferase reporter and ChIP assay were employed to further explore the potential mechanisms.

RESULTS

The abnormally elevated expression of Sec62 predicted poor prognosis of CRC patients and facilitated malignant metastasis of CRC cells. Mechanistically, Sec62 enhanced UCA1 expression through activating MAPK/JNK signalling pathway. And the p-JNK activating ATF2 could transcriptionally regulate UCA1 expression. Furthermore, blocking or activating MAPK/JNK signalling with JNK inhibitor or agonist potently suppressed or enhanced Sec62 mediated CRC metastatic process.

CONCLUSIONS

Our study reports for the first time that the Sec62/MAPK/ATF2 /UCA1 axis exists in CRC metastatic process, which could be a potential treatment target of metastatic CRC.

Exosomal noncoding RNAs in colorectal cancer: An overview of functions, challenges, opportunities, and clinical applications

Colorectal cancer (CRC) is the third most threatening malignancy worldwide. Colorectal tumors transfer information with their tumor microenvironment (TME) and communicate together which can be detected through exosome transmission. Exosomes are important regulators made by different types of cells in all body fluids containing RNA, DNA, metabolites, and proteins. Recently, Exosome-derived noncoding RNAs (ncRNAs) applications have gained great consideration based on their potential role in the different pathological processes. Therefore, in this review, we summarized the recent discoveries on exosomal ncRNAs function in CRC initiation and development, and drug resistance to provide a novel insight into exosomal ncRNAs' clinical application and their potential to be biomarkers for CRC patients.

Identification of Diagnostic Exosomal LncRNA-miRNA-mRNA Biomarkers in Colorectal Cancer Based on the ceRNA Network

Background: Colorectal cancer (CRC) is currently the fourth most common cancer worldwide. The roles of exosomal competing endogenous RNAs (ceRNAs) in CRC remain unclear. In this study, we constructed an exosomal ceRNA network to identify the core ceRNAs and investigate the diagnostic biomarkers in CRC.

Methods and Patients: Serum exosomes were isolated from four CRC patients and two healthy donors by ultracentrifugation, and then subjected to RNA isolation, sequencing and microarray. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) analyses were performed to identify functional enrichment implications of differentially expressed exosomal mRNAs. TargetScan and miRanda were used for identifying the miRNA-mRNA and miRNA-LncRNA interactions. The predicted lncRNAs and mRNAs were intersected with the differentially expressed genes, for which the screening criterion was fold change &gt;1.5 in the microarray. Differentially expressed exosomal miRNAs were identified in the GSE71008 dataset, and differentially expressed mRNAs (DEmRNAs) were further summarized from The Cancer Genome Atlas (TCGA) database.

Results: A total of 1186 exosomal DEmRNAs, 2088 exosomal DElncRNAs and 29 exosomal miRNAs were detected in CRC patients compared to the healthy donors. Functional enrichment analysis suggested that exosomal DEmRNAs might participate in pathways related to carcinogenesis and development of cancer. An exosomal ceRNA regulatory network of CRC was constructed based on 40 lncRNAs, two miRNAs, and five mRNAs. Exosomal miR-150-5p and miR-10b-5p expression levels were increased in healthy donors compared with CRC patients in the GSE71008 dataset, and five DEmRNAs (TOMM70A, RBM48, BEND3, RHOBTB1, and ADAMTS2) were significantly upregulated in TCGA database. Two potential exosomal regulatory axes of lncRNA G016261-miR-150-5p-RBM48 and lncRNA XLOC_011677-miR-10b-5p-BEND3 were identified from the network.

Conclusion: The current study revealed potential molecular biological regulation pathways and diagnostic biomarkers through the exosomal ceRNA regulatory network.

LncRNA UCA1 accelerates osteosarcoma progression via miR-145 and Wnt/β-catenin pathway

Long non-coding (lnc) urothelial cancer associated 1 (UCA1) has been confirmed to participate in osteosarcoma (OS), but its specific mechanism is still under investigation. The study was designed to reveal the interaction between UCA1 and its downstream effector molecules, so as to determine whether there is any interaction of regulating physiological processes in tumor cells. Here, we studied the signaling cascade involving UCA1, miR-145, and HMGA1. The expression of UCA1 and miR-145 levels was interfered to assess their effects on physiological processes of tumor cells. The relationship between UCA1 and miR-145 as well as between HMGA1 and miR-145 was identified by the dual-luciferase reporter (DLR) assay, and the in vivo effect of UCA1 was estimated in nude mouse xenografts. As a result, a negative association was found between UCA1 and miR-145 in OS cells. Both UCA1 knockout and miR-145 over-expression inhibited malignant progression and induced apoptosis in MG-63 and U2OS cells. UCA1 knockout led to an increase in miR-145 and decreases in HMGA1, p-β-catenin and cyclin D1. In addition, UCA1 upregulation promoted tumor growth in vitro and changed miR-145 and HMGA1 levels in vivo. Moreover, the DLR assay and RNA immunoprecipitation (RIP) showed that UCA1 was likely to regulate HMGA1 levels by sponging miR-145. Overall, the inhibition of UCA1 increases miR-145 levels and decreases HMGA1 levels, thereby exerting an anti-tumor role in OS.

Noncoding RNome as Enabling Biomarkers for Precision Health

Noncoding RNAs (ncRNAs), in the form of structural, catalytic or regulatory RNAs, have emerged to be critical effectors of many biological processes. With the advent of new technologies, we have begun to appreciate how intracellular and circulatory ncRNAs elegantly choreograph the regulation of gene expression and protein function(s) in the cell. Armed with this knowledge, the clinical utility of ncRNAs as biomarkers has been recently tested in a wide range of human diseases. In this review, we examine how critical factors govern the success of interrogating ncRNA biomarker expression in liquid biopsies and tissues to enhance our current clinical management of human diseases, particularly in the context of cancer. We also discuss strategies to overcome key challenges that preclude ncRNAs from becoming standard-of-care clinical biomarkers, including sample pre-analytics standardization, data cross-validation with closer attention to discordant findings, as well as correlation with clinical outcomes. Although harnessing multi-modal information from disease-associated noncoding RNome (ncRNome) in biofluids or in tissues using artificial intelligence or machine learning is at the nascent stage, it will undoubtedly fuel the community adoption of precision population health.

MALAT1 in colorectal cancer: Its implication as a diagnostic, prognostic, and predictive biomarker

Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT1), originally described as a prognostic biomarker remarkably linked with metastasis potential in lung cancer, has been identified as contributing to many diseases, including colorectal cancer (CRC). This long non-coding RNA (lncRNA) has come to the forefront of lncRNA research for its implications in cancer-related processes, such as cell proliferation and migration. In general, lncRNAs are recognized as enhancers, scaffolds, or decoys for a variety of oncogenes and tumor suppressors, although our understanding of lncRNA functions and mechanisms of action is still limited. Nowadays, cancer research is attracted to lncRNAs' ability to improve the early diagnosis of cancer, determine patients' prognosis, or predict therapy outcomes. In this review, we aimed to evaluate recent publications trying to uncover the cellular mechanisms of MALAT1-mediated regulation, and its potential exploitation in the management of CRC. The conclusions of this review provide robust support for the essential role of MALAT1 in CRC development and future personalized therapy.

Diagnostic and prognostic biomarkers in colorectal cancer and the potential role of exosomes in drug delivery

Colorectal cancer (CRC) is third most common cancer with second most common cause of death worldwide. One fourth to one fifth of the CRC cases are detected at advance stage. Early detection of colorectal cancer might help in decreasing mortality and morbidity worldwide. CRC being a heterogeneous disease, new non-invasive approaches are needed to complement and improve the screening and management of CRC. Reliable and early detectable biomarkers would improve diagnosis, prognosis, therapeutic responses, and will enable the prediction of drug response and recurrence risk. Over the past decades molecular research has demonstrated the potentials of CTCs, ctDNAs, circulating mRNA, ncRNAs, and exosomes as tumor biomarkers. Non-invasive screening approaches using fecal samples for identification of altered gut microbes in CRC is also gaining attention. Exosomes can be potential candidates that can be employed in the drug delivery system. Further, the integration of in vitro, in vivo and in silico models that involve CRC biomarkers will help to understand the interactions occurring at the cellular level. This review summarizes recent update on CRC biomarkers and their application along with the nanoparticles followed by the application of organoid culture in CRC.

The diagnostic value of exosomal circular RNAs in cancer patients: A systematic review and meta-analysis

BACKGROUND

Recently, serum exosomal circular RNAs (circRNAs) were applied to discriminate cancer patients from healthy individuals, indicating that exosomal circRNAs have the potential to be novel biomarkers for cancer diagnosis. This study aims to summarize the role of exosomal circRNAs in cancer diagnosis by a meta-analysis.

METHODS

A comprehensive literature search was conducted up to July 2021 in PubMed, Web of Science, EMBASE, and Cochrane Database. To evaluate the diagnostic value, the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) were pooled. Threshold effect followed by subgroup analysis and meta-regression were performed to explore the source of heterogeneity. Sensitivity analysis was performed to assess the stability of this meta-analysis model. Fagan plots and likelihood ratio scattergrams were used to explore the potential clinical significance.

RESULTS

Ten eligible studies with 514 controls and 557 patients were included in this diagnostic meta-analysis. The pooled sensitivity, specificity, PLR, NLR, and DOR were 0.75 (95% CI: 0.65-0.83), 0.84 (95% CI, 0.78-0.89), 5.87 (95% CI, 3.67-9.38), 0.28 (95% CI, 0.19-0.40), and 21.15 (95% CI, 10.25-43.68), respectively. The AUC was 0.89 (95% CI, 0.86-0.91). Sensitivity analysis showed that four studies had an impact on the pooled results and mainly contributed to the heterogeneity. Fagan's nomogram revealed that the prior probability of 20%, the post probability positive, the post probability negative were 59% and 6%, respectively.

CONCLUSION

Our results suggested that exosomal circRNAs might serve as powerful biomarkers in detecting cancers with high sensitivity and specificity. However, more well-designed and multicenter diagnostic tests are needed to validate our results.

Prospect of exosomal circular RNAs in breast Cancer: presents and future

Implementing precision oncology for breast cancer (BC) is a critical method for improving patient outcomes, which relies on the use of reliable biomarkers to be effective and safe. exosomes represent a potential alternative for the diagnosis and therapy of BC, As a "liquid biopsy" and a novel source for biomarkers. Exosomes are nanoscale phospholipid bilayer vesicles released by most cells that contain a large payload of various RNA species that can alter recipient cell activity. Circular RNAs (circRNAs) were recently revealed as a looping subclass of competing endogenous noncoding RNAs (ceRNAs) capable of microRNA sponging to regulate gene expression. They provide critical regulatory functions in carcinogenesis, proliferation, invasion, metastasis, and treatment resistance, as well as cancer prognostic. However, there is still a major gap in our understanding of the role of circRNA in the advancement of BC. CircRNAs are abundant in exosomes, according to various studies, and exosomal circRNAs (exo-circRNAs) play a significant role in cancer biology. Exo-circRNAs can be picked up by nearby or distant cells, affecting many features of the target cells' pathophysiological states, thus boosting cell communication and tumor spread. In this review, we have briefly summarized the major properties and functions of exosomes. Then, we have focused on exo-circRNAs, discussing their potential roles in both driving and inhibiting BC, as well as for cancer diagnosis, prognosis, and monitoring.

Emerging role of exosomes in cancer progression and tumor microenvironment remodeling

Cancer is one of the leading causes of death worldwide, and the factors responsible for its progression need to be elucidated. Exosomes are structures with an average size of 100 nm that can transport proteins, lipids, and nucleic acids. This review focuses on the role of exosomes in cancer progression and therapy. We discuss how exosomes are able to modulate components of the tumor microenvironment and influence proliferation and migration rates of cancer cells. We also highlight that, depending on their cargo, exosomes can suppress or promote tumor cell progression and can enhance or reduce cancer cell response to radio- and chemo-therapies. In addition, we describe how exosomes can trigger chronic inflammation and lead to immune evasion and tumor progression by focusing on their ability to transfer non-coding RNAs between cells and modulate other molecular signaling pathways such as PTEN and PI3K/Akt in cancer. Subsequently, we discuss the use of exosomes as carriers of anti-tumor agents and genetic tools to control cancer progression. We then discuss the role of tumor-derived exosomes in carcinogenesis. Finally, we devote a section to the study of exosomes as diagnostic and prognostic tools in clinical courses that is important for the treatment of cancer patients. This review provides a comprehensive understanding of the role of exosomes in cancer therapy, focusing on their therapeutic value in cancer progression and remodeling of the tumor microenvironment.

Crosstalk of Exosomal Non-Coding RNAs in The Tumor Microenvironment: Novel Frontiers

The tumor microenvironment (TME) is defined as a complex and dynamic tissue entity composed of endothelial, stromal, immune cells, and the blood system. The homeostasis and evolution of the TME are governed by intimate interactions among cellular compartments. The malignant behavior of cancer cells, such as infiltrating growth, proliferation, invasion, and metastasis, is predominantly dependent on the bidirectional communication between tumor cells and the TME. And such dialogue mainly involves the transfer of multifunctional regulatory molecules from tumor cells and/or stromal cells within the TME. Interestingly, increasing evidence has confirmed that exosomes carrying regulatory molecules, proteins, and nucleic acids act as an active link in cellular crosstalk in the TME. Notably, extensive studies have identified non-coding RNAs (ncRNAs), including long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), that could be encapsulated by exosomes, which regulate the coordinated function within the TME and thus participate in cancer development and progression. In this review, we summarize recent literature around the topic of the functions and mechanisms of exosomal ncRNAs in the TME and highlight their clinical significance.

Exosome-Derived Non-Coding RNAs in the Tumor Microenvironment of Colorectal Cancer: Possible Functions, Mechanisms and Clinical Applications

Colorectal cancer (CRC) is the second leading cause of cancer death and the third most prevalent malignancy. Colorectal tumors exchange information with the surrounding environment and influence each other, which collectively constitutes the tumor microenvironment (TME) of CRC. Many studies have shown that exosome-derived non-coding RNAs (ncRNAs) play important roles in various pathophysiological processes by regulating the TME of CRC. This review summarizes recent findings on the fundamental roles of exosomal ncRNAs in angiogenesis, vascular permeability, tumor immunity, tumor metabolism and drug resistance. Certainly, the in-depth understanding of exosomal ncRNAs will provide comprehensive insights into the clinical application of these molecules against CRC.

Role of exosomal competitive endogenous RNA (ceRNA) in diagnosis and treatment of malignant tumors

Malignant tumors are a threat to human health, thus it is critical to better understand the mechanism of tumor occurrence and development and to find key therapeutic targets. Competitive endogenous RNA (ceRNA) is a type of RNA molecule that includes mRNA of coding-protein, pseudogenes, long non-coding RNA (lncRNA), and circular RNA (circRNA) etc. It is created through a competitive combination of common small RNA (miRNA) and has an inhibitory effect on mRNA translation. ceRNA regulate the post transcriptional expression of genes by competitively binding to common microRNAs (miRNAs).Studies have shown that cernas are involved in tumor cell proliferation, invasion and migration, drug resistance, angiogenesis, as well as tumor immunity, and so on, affecting the progression of tumor development. This article reviews the reported roles of exosomal ceRNA in the diagnosis and treatment of malignant tumors and the mechanisms underlying these.

Circular RNAs and Their Role in Exosomes

As a novel class of endogenous non-coding RNAs discovered in recent years, circular RNAs (circRNAs) are highly conserved and stable covalently closed ring structures with no 5'-end cap or 3'-end poly(A) tail. CircRNAs are formed by reverse splicing, mainly by means of a noose structure or intron complementary pairing. Exosomes are tiny discoid vesicles with a diameter of 40-100 nm that are secreted by cells under physiological and pathological conditions. Exosomes play an important role in cell-cell communication by carrying DNA, microRNAs, mRNAs, proteins and circRNAs. In this review, we summarize the biological functions of circRNAs and exosomes, and further reveal the potential roles of exosomal circRNAs in different diseases, providing a scientific basis for the diagnosis, treatment, and prognosis of a wide variety of diseases.

SP1-mediated up-regulation of lncRNA TUG1 underlines an oncogenic property in colorectal cancer

The long non-coding RNA (lncRNA) taurine up-regulated gene 1 (TUG1) acts as tumor-promoting factor in colorectal cancer (CRC). We aimed to elucidate the mechanism by which the transcription factor specificity protein 1 (SP1) regulates TUG1 and microRNAs (miRs)/mRNAs in the context of CRC, which has not been fully studied before. Expression patterns of TUG1 and SP1 were determined in clinical CRC samples and cells, followed by identification of their interaction. Next, the functional significance of TUG1 in CRC was investigated. An in vivo CRC model was established to validate the effect of TUG1. The results demonstrated that TUG1 and SP1 were highly-expressed in CRC, wherein SP1 bound to the TUG1 promoter and consequently, positively regulated its expression. Silencing of TUG1 caused suppression of CRC cell growth and promotion of cell apoptosis. TUG1 could bind to miR-421 to increase KDM2A expression, a target gene of miR-421. TUG1 could activate the ERK pathway by impairing miR-421-targeted inhibition of KDM2A. Additionally, SP1 could facilitate the tumorigenesis of CRC cells in vivo by regulating the TUG1/miR-421/KDM2A/ERK axis. Altogether, the current study emphasizes the oncogenic role of TUG1 in CRC, and illustrates its interactions with the upstream transcription factor SP1 and the downstream modulatory axis miR-421/KDM2A/ERK, thus offering novel insights into the cancerogenic mechanism in CRC.

Liquid Biopsy as a Source of Nucleic Acid Biomarkers in the Diagnosis and Management of Lynch Syndrome

Lynch syndrome (LS) is an autosomal dominant inherited cancer predisposition disorder, which may manifest as colorectal cancer (CRC), endometrial cancer (EC) or other malignancies of the gastrointestinal and genitourinary tract as well as the skin and brain. Its genetic cause is a defect in one of the four key DNA mismatch repair (MMR) loci. Testing of patients at risk is currently based on the absence of MMR protein staining and detection of mutations in cancer tissue and the germline, microsatellite instability (MSI) and the hypermethylated state of the MLH1 promoter. If LS is shown to have caused CRC, lifetime follow-up with regular screening (most importantly, colonoscopy) is required. In recent years, DNA and RNA markers extracted from liquid biopsies have found some use in the clinical diagnosis of LS. They have the potential to greatly enhance the efficiency of the follow-up process by making it minimally invasive, reproducible, and time effective. Here, we review markers reported in the literature and their current clinical applications, and we comment on possible future directions.

Roles and clinical application of exosomal circRNAs in the diagnosis and treatment of malignant tumors

Exosomes are microvesicles secreted by cells. They contain a variety of bioactive substances with important roles in intercellular communication. Circular RNA (circRNA), a type of nucleic acid molecule found in exosomes, forms a covalently bonded closed loop without 5′ caps or 3′ poly(A) tails. It is structurally stable, widely distributed, and tissue specific. CircRNAs mainly act as microRNA sponges and have important regulatory roles in gene expression; they are superior to other non-coding RNAs as molecular diagnostic markers and drug treatment targets. Exosomal-derived circRNAs in the body fluids of tumor patients can modulate tumor proliferation, invasion, metastasis, and drug resistance. They can be used as effective biomarkers for early non-invasive diagnosis and prognostic evaluation of tumors, and also represent ideal targets for early precision therapeutic intervention. This review provides a theoretical basis for exploring the applications of exosomal circRNAs in malignant tumor diagnosis and treatment. We describe the biological functions of exosomal circRNAs in the occurrence and development of malignant tumors, their potential utility in diagnosis and treatment, and possible mechanisms.

Dynamic liquid biopsy components as predictive and prognostic biomarkers in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. The diagnosis, prognosis and therapeutic monitoring of CRC depends largely on tissue biopsy. However, due to tumor heterogeneity and limitations such as invasiveness, high cost and limited applicability in longitudinal monitoring, liquid biopsy has gathered immense attention in CRC. Liquid biopsy has several advantages over tissue biopsy including ease of sampling, effective monitoring, and longitudinal assessment of treatment dynamics. Furthermore, the importance of liquid biopsy is signified by approval of several liquid biopsy assays by regulatory bodies indicating the powerful approach of liquid biopsy for comprehensive CRC screening, diagnostic and prognostics. Several liquid biopsy biomarkers such as novel components of the microbiome, non-coding RNAs, extracellular vesicles and circulating tumor DNA are extensively being researched for their role in CRC management. Majority of these components have shown promising results on their clinical application in CRC including early detection, observe tumor heterogeneity for treatment and response, prediction of metastases and relapse and detection of minimal residual disease. Therefore, in this review, we aim to provide updated information on various novel liquid biopsy markers such as a) oral microbiota related bacterial network b) gut microbiome-associated serum metabolites c) PIWI-interacting RNAs (piRNAs), microRNA(miRNAs), Long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and d) circulating tumor DNAs (ctDNA) and circulating tumor cells (CTC) for their role in disease diagnosis, prognosis, treatment monitoring and their applicability for personalized management of CRC.

The Role of LncRNA TUG1 in Obesity-Related Diseases

With the continuous improvement of living standards, obesity has become an inevitable hotspot in our daily life. It remains a chronic and recurrent disease with serious adverse consequences. Over the past few years, several articles suggested that long non-coding RNA taurine increased gene 1（lncRNA TUG1）, a useful RNA, was suggested to show a relationship to obesity-related disease occurrence and development. Exosome is an emerging research field, which contains substances that are actively involved in regulating the molecular mechanisms of disease. This review summarizes the current relevant TUG1 in different molecular pathways of diseases related to obesity, relationship between exosomes and TUG1 or diseases related to obesity. The aim is to explore TUG1 as a novel target for obesity, which can deepen the knowledge regarding epigenetic regulation pathway. Besides, it is likely to be a potential future targeting diseases related to obesity site treatment and diagnosis.

Competing endogenous RNA network mediated by circ_3205 in SARS-CoV-2 infected cells

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a new member of the Betacoronaviridae family, responsible for the recent pandemic outbreak of COVID-19. To start exploring the molecular events that follow host cell infection, we queried VirusCircBase and identified a circular RNA (circRNA) predicted to be synthesized by SARS-CoV-2, circ_3205, which we used to probe: (i) a training cohort comprised of two pools of cells from three nasopharyngeal swabs of SARS-CoV-2 infected (positive) or uninfected (negative, UCs) individuals; (ii) a validation cohort made up of 12 positive and 3 negative samples. The expression of circRNAs, miRNAs and miRNA targets was assayed through real-time PCR. CircRNA-miRNA interactions were predicted by TarpMiR, Analysis of Common Targets for circular RNAs (ACT), and STarMir tools. Enrichment of the biological processes and the list of predicted miRNA targets were retrieved from DIANA miRPath v3.0. Our results showed that the predicted SARS-CoV-2 circ_3205 was expressed only in positive samples and its amount positively correlated with that of SARS-CoV-2 Spike (S) mRNA and the viral load (r values = 0.80952 and 0.84867, Spearman's correlation test, respectively). Human (hsa) miR-298 was predicted to interact with circ_3205 by all three predictive tools. KCNMB4 and PRKCE were predicted as hsa-miR-298 targets. Interestingly, the function of both is correlated with blood coagulation and immune response. KCNMB4 and PRKCE mRNAs were upregulated in positive samples as compared to UCs (6 and 8.1-fold, p values = 0.049 and 0.02, Student's t test, respectively) and their expression positively correlated with that of circ_3205 (r values = 0.6 and 0.25, Spearman's correlation test, respectively). We propose that our results convincingly suggest that circ_3205 is a circRNA synthesized by SARS-CoV-2 upon host cell infection and that it may behave as a competitive endogenous RNA (ceRNA), sponging hsa-miR-298 and contributing to the upregulation of KCNMB4 and PRKCE mRNAs.