Exosomes from CD133+ cells carrying circ-ABCC1 mediate cell stemness and metastasis in colorectal cancer

Extracellular vesicles and cancer stem cells: a deadly duo in tumor progression

The global incidence of cancer is increasing, with estimates suggesting that there will be 26 million new cases and 17 million deaths per year by 2030. Cancer stem cells (CSCs) and extracellular vesicles (EVs) are key to the resistance and advancement of cancer. They play a crucial role in tumor dynamics and resistance to therapy. CSCs, initially discovered in acute myeloid leukemia, are well-known for their involvement in tumor initiation, progression, and relapse, mostly because of their distinct characteristics, such as resistance to drugs and the ability to self-renew. EVs, which include exosomes, microvesicles, and apoptotic bodies, play a vital role in facilitating communication between cells within the tumor microenvironment (TME). They have a significant impact on cellular behaviors and contribute to genetic and epigenetic changes. This paper analyzes the mutually beneficial association between CSCs and EVs, emphasizing their role in promoting tumor spread and developing resistance mechanisms. This review aims to investigate the interaction between these entities in order to discover new approaches for attacking the complex machinery of cancer cells. It highlights the significance of CSCs and EVs as crucial targets in the advancement of novel cancer treatments, which helps stimulate additional research, promote progress in ideas for cancer treatment, and provide renewed optimism in the effort to reduce the burden of cancer.

Challenges and opportunities for cancer stem cell-targeted immunotherapies include immune checkpoint inhibitor, cancer stem cell-dendritic cell vaccine, chimeric antigen receptor immune cells, and modified exosomes

Cancer stem cells (CSCs) are associated with the tumor microenvironment (TME). CSCs induce tumorigenesis, tumor recurrence and progression, and resistance to standard therapies. Indeed, CSCs pose an increasing challenge to current cancer therapy due to their stemness or self-renewal properties. The molecular and cellular interactions between heterogeneous CSCs and surrounding TME components and tumor-supporting immune cells show synergistic effects toward treatment failure. In the immunosuppressive TME, CSCs express various immunoregulatory proteins, growth factors, metabolites and cytokines, and also produce exosomes, a type of extracellular vesicles, to protect themselves from host immune surveillance. Among these, the identification and application of CSC-derived exosomes could be considered for the development of therapeutic approaches to eliminate CSCs or cancer, in addition to targeting the modulators that remodel the composition of the TME, as reviewed in this study. Here, we introduce the role of CSCs and how their interaction with TME complicates immunotherapies, and then present the CSC-based immunotherapy and the limitation of these therapies. We describe the biology and role of tumor/CSC-derived exosomes that induce immune suppression in the TME, and finally, introduce their potentials for the development of CSC-based targeted immunotherapy in the future.

CircUBE3A(2,3,4,5) promotes adenylate-uridylate-rich binding factor 1 nuclear translocation to suppress prostate cancer metastasis

Metastatic progression is the primary cause of mortality in prostate cancer (PCa) patients. Although circular RNAs (circRNAs) have been implicated in cancer progression and metastasis, our current understanding of their role in PCa metastasis remains limited. In this study, we identified that circUBE3A(2,3,4,5), which originated from exons 2, 3, 4 and 5 of the human ubiquitin-protein ligase E3A (UBE3A) gene, was specifically downregulated in PCa tissues and correlated with the Gleason score, bone metastasis, and D'Amico risk classification. Through the in vitro and in vivo experiments, we demonstrated that overexpression of circUBE3A(2,3,4,5) inhibited PCa cell migration, invasion, metastasis, and proliferation. Mechanistically, circUBE3A(2,3,4,5) was found to bind to adenylate-uridylate-rich binding factor 1 (AUF1), promoting the translocation of AUF1 into the nucleus. This led to decreased AUF1 in the cytoplasm, resulting in methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) mRNA instability and a subsequent reduction at the protein level. The downregulation of MTHFD2 further inhibited vimentin expression, thereby suppressing PCa cell epithelial-mesenchymal transition. Additionally, two pairs of the short-inverted repeats (TSIRs) in flanking introns were identified to synergistically facilitate the generation of circUBE3A(2,3,4,5) and other circRNAs. In summary, TSIRs-induced circUBE3A(2,3,4,5) acts as a suppressor of PCa metastasis by enhancing AUF1 nuclear translocation, reducing MTHFD2, and subsequently inhibiting vimentin expression. This study characterizes circUBE3A(2,3,4,5) as a functional circRNA and proposes it as a highly promising target for preventing PCa metastasis.

Function and mechanism of exosomes derived from different cells as communication mediators in colorectal cancer metastasis

Colorectal cancer (CRC) ranks as the second leading cause of cancer-related mortality, with metastasis being the primary determinant of poor prognosis in patients. Investigating the molecular mechanisms underlying CRC metastasis is currently a prominent and challenging area of research. Exosomes, as crucial intercellular communication mediators, facilitate the transfer of metabolic and genetic information from cells of origin to recipient cells. Their roles in mediating information exchange between CRC cells and immune cells, fibroblasts, and other cell types are pivotal in reshaping the tumor microenvironment, regulating key biological processes such as invasion, migration, and formation of pre-metastatic niche. This article comprehensively examines the communication function and mechanism of exosomes derived from different cells in cancer metastasis, while also presenting an outlook on current research advancements and future application prospects. The aim is to offer a distinctive perspective that contributes to accurate diagnosis and rational treatment strategies for 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.

Aberrant stem cell and developmental programs in pediatric leukemia

Hematopoiesis is a finely orchestrated process, whereby hematopoietic stem cells give rise to all mature blood cells. Crucially, they maintain the ability to self-renew and/or differentiate to replenish downstream progeny. This process starts at an embryonic stage and continues throughout the human lifespan. Blood cancers such as leukemia occur when normal hematopoiesis is disrupted, leading to uncontrolled proliferation and a block in differentiation of progenitors of a particular lineage (myeloid or lymphoid). Although normal stem cell programs are crucial for tissue homeostasis, these can be co-opted in many cancers, including leukemia. Myeloid or lymphoid leukemias often display stem cell-like properties that not only allow proliferation and survival of leukemic blasts but also enable them to escape treatments currently employed to treat patients. In addition, some leukemias, especially in children, have a fetal stem cell profile, which may reflect the developmental origins of the disease. Aberrant fetal stem cell programs necessary for leukemia maintenance are particularly attractive therapeutic targets. Understanding how hijacked stem cell programs lead to aberrant gene expression in place and time, and drive the biology of leukemia, will help us develop the best treatment strategies for patients.

Exosomal non-coding RNAs in colorectal cancer metastasis

Colorectal cancer (CRC) is a type of gastrointestinal cancer with high morbidity and mortality rates, and is often accompanied by distant metastases. Metastasis is a major cause of shortened survival time and poor treatment outcomes for patients with CRC. However, the molecular mechanisms underlying the metastasis of CRC remain unclear. Exosomes are a class of small extracellular vesicles that originate from almost all human cells and can transmit biological information (e.g., nucleic acids, lipids, proteins, and metabolites) from secretory cells to target recipient cells. Recent studies have revealed that non-coding RNAs (ncRNAs) can be released by exosomes into the tumour microenvironment or specific tissues, and play a pivotal role in tumorigenesis by regulating a series of key molecules or signalling pathways, particularly those involved in tumour metastasis. Exosomal ncRNAs have potential as novel therapeutic targets for CRC metastasis, and can also be used as liquid biopsy biomarkers because of their specificity and sensitivity. Therefore, further investigations into the biological function and clinical value of exosomal ncRNAs will be of great value for the prevention, early diagnosis, and treatment of CRC metastasis.

Tumor cell stemness in gastrointestinal cancer: regulation and targeted therapy

The cancer stem cells are a rare group of self-renewable cancer cells capable of the initiation, progression, metastasis and recurrence of tumors, and also a key contributor to the therapeutic resistance. Thus, understanding the molecular mechanism of tumor stemness regulation, especially in the gastrointestinal (GI) cancers, is of great importance for targeting CSC and designing novel therapeutic strategies. This review aims to elucidate current advancements in the understanding of CSC regulation, including CSC biomarkers, signaling pathways, and non-coding RNAs. We will also provide a comprehensive view on how the tumor microenvironment (TME) display an overall tumor-promoting effect, including the recruitment and impact of cancer-associated fibroblasts (CAFs), the establishment of an immunosuppressive milieu, and the induction of angiogenesis and hypoxia. Lastly, this review consolidates mainstream novel therapeutic interventions targeting CSC stemness regulation.

circEPB41L2 blocks the progression and metastasis in non-small cell lung cancer by promoting TRIP12-triggered PTBP1 ubiquitylation

The metastasis of non-small cell lung cancer (NSCLC) is the leading death cause of NSCLC patients, which requires new biomarkers for precise diagnosis and treatment. Circular RNAs (circRNAs), the novel noncoding RNA, participate in the progression of various cancers as microRNA or protein sponges. We revealed the mechanism by which circEPB41L2 (hsa_circ_0077837) blocks the aerobic glycolysis, progression and metastasis of NSCLC through modulating protein metabolism of PTBP1 by the E3 ubiquitin ligase TRIP12. With ribosomal RNA-depleted RNA seq, 57 upregulated and 327 downregulated circRNAs were identified in LUAD tissues. circEPB41L2 was selected due to its dramatically reduced levels in NSCLC tissues and NSCLC cells. Interestingly, circEPB41L2 blocked glucose uptake, lactate production, NSCLC cell proliferation, migration and invasion in vitro and in vivo. Mechanistically, acting as a scaffold, circEPB41L2 bound to the RRM1 domain of the PTBP1 and the E3 ubiquitin ligase TRIP12 to promote TRIP12-mediated PTBP1 polyubiquitylation and degradation, which could be reversed by the HECT domain mutation of TRIP12 and circEPB41L2 depletion. As a result, circEPB41L2-induced PTBP1 inhibition led to PTBP1-induced PKM2 and Vimentin activation but PKM1 and E-cadherin inactivation. These findings highlight the circEPB41L2-dependent mechanism that modulates the "Warburg Effect" and EMT to inhibit NSCLC development and metastasis, offering an inhibitory target for NSCLC treatment.

Tumor-derived small extracellular vesicles in cancer invasion and metastasis: molecular mechanisms, and clinical significance

The production and release of tumor-derived small extracellular vesicles (TDSEVs) from cancerous cells play a pivotal role in the propagation of cancer, through genetic and biological communication with healthy cells. TDSEVs are known to orchestrate the invasion-metastasis cascade via diverse pathways. Regulation of early metastasis processes, pre-metastatic niche formation, immune system regulation, angiogenesis initiation, extracellular matrix (ECM) remodeling, immune modulation, and epithelial-mesenchymal transition (EMT) are among the pathways regulated by TDSEVs. MicroRNAs (miRs) carried within TDSEVs play a pivotal role as a double-edged sword and can either promote metastasis or inhibit cancer progression. TDSEVs can serve as excellent markers for early detection of tumors, and tumor metastases. From a therapeutic point of view, the risk of cancer metastasis may be reduced by limiting the production of TDSEVs from tumor cells. On the other hand, TDSEVs represent a promising approach for in vivo delivery of therapeutic cargo to tumor cells. The present review article discusses the recent developments and the current views of TDSEVs in the field of cancer research and clinical applications.

Exosomal non-coding RNAs: Blueprint in colorectal cancer metastasis and therapeutic targets

Colorectal cancer (CRC) is ranked as the world's third-most prevalent cancer, and metastatic CRC considerably increases cancer-related fatalities globally. A number of complex mechanisms that are strictly controlled at the molecular level are involved in metastasis, which is the primary reason for death in people with CRC. Recently, it has become clear that exosomes, which are small extracellular vesicles released by non-tumorous and tumorigenic cells, play a critical role as communication mediators among tumor microenvironment (TME). To facilitate communication between the TME and cancer cells, non-coding RNAs (ncRNAs) play a crucial role and are recognized as potent regulators of gene expression and cellular processes, such as metastasis and drug resistance. NcRNAs are now recognized as potent regulators of gene expression and many hallmarks of cancer, including metastasis. Exosomal ncRNAs, like miRNAs, circRNAs, and lncRNAs, have been demonstrated to influence a number of cellular mechanisms that contribute to CRC metastasis. However, the molecular mechanisms that link exosomal ncRNAs with CRC metastasis are not well understood. This review highlights the essential roles that exosomal ncRNAs play in the progression of CRC metastatic disease and explores the therapeutic choices that are open to patients who have CRC metastases. However, exosomal ncRNA treatment strategy development is still in its early phases; consequently, additional investigation is required to improve delivery methods and find novel therapeutic targets as well as confirm the effectiveness and safety of these therapies in preclinical and clinical contexts.

Exosomes in Cancer Progression and Therapy Resistance: Molecular Insights and Therapeutic Opportunities

The development of therapy resistance still represents a major hurdle in treating cancers, leading to impaired treatment success and increased patient morbidity. The establishment of minimally invasive liquid biopsies is a promising approach to improving the early diagnosis, as well as therapy monitoring, of solid tumors. Because of their manifold functions in the tumor microenvironment, tumor-associated small extracellular vesicles, referred to as exosomes, have become a subject of intense research. Besides their important roles in cancer progression, metastasis, and the immune response, it has been proposed that exosomes also contribute to the acquisition and transfer of therapy resistance, mainly by delivering functional proteins and RNAs, as well as facilitating the export of active drugs or functioning as extracellular decoys. Extensive research has focused on understanding the molecular mechanisms underlying the occurrence of resistance and translating these into strategies for early detection. With this review, we want to provide an overview of the current knowledge about the (patho-)biology of exosomes, as well as state-of-the-art methods of isolation and analysis. Furthermore, we highlight the role of exosomes in tumorigenesis and cancer treatment, where they can function as therapeutic agents, biomarkers, and/or targets. By focusing on their roles in therapy resistance, we will reveal new paths of exploiting exosomes for cancer diagnosis and treatment.

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.

The application of extracellular vesicles in colorectal cancer metastasis and drug resistance: recent advances and trends

Colorectal cancer (CRC) has high incidence and mortality rates and is one of the most common cancers of the digestive tract worldwide. Metastasis and drug resistance are the main causes of cancer treatment failure. Studies have recently suggested extracellular vesicles (EVs) as a novel mechanism for intercellular communication. They are vesicular particles, which are secreted and released into biological fluids, such as blood, urine, milk, etc., by a variety of cells and carry numerous biologically active molecules, including proteins, nucleic acids, lipids, metabolites, etc. EVs play a crucial part in the metastasis and drug resistance of CRC by delivering cargo to recipient cells and modulating their behavior. An in-depth exploration of EVs might facilitate a comprehensive understanding of the biological behavior of CRC metastasis and drug resistance, which might provide a basis for developing therapeutic strategies. Therefore, considering the specific biological properties of EVs, researchers have attempted to explore their potential as next-generation delivery systems. On the other hand, EVs have also been demonstrated as biomarkers for the prediction, diagnosis, and presumed prognosis of CRC. This review focuses on the role of EVs in regulating the metastasis and chemoresistance of CRC. Moreover, the clinical applications of EVs are also discussed.

Silencing circular RNA hsa_circABCC1 inhibits osteosarcoma progression through down-regulating HDAC4 via sponging miR-591

BACKGROUND

Circular RNA (circRNA) has been shown to play an important regulatory role in the development of various cancers, including osteosarcoma (OS). However, the role of circRNA ABCC1 (circABCC1) in OS was still poorly understood. The aim of our study was to investigate the role of circABCC1 in OS progression and its potential molecular mechanisms.

METHODS

The expression of circABCC1, microRNA-591 (miR-591) and histone deacetylase 4 (HDAC4) in OS tissues or cells was detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot (WB) analyses. In vitro experiments, the viability, proliferation, apoptosis, migration, invasion and autophagy of U2OS and HOS cells were assessed in vitro using cell counting kit-8 (CCK-8) assay, 5-ethynyl-29-deoxyuridine (EdU) assay, flow cytometry (FCM) assay, transwell migration and invasion assays (transwell) and WB assay, respectively. Interactions between circABCC1 and miR-591, miR-591 and HDAC4 were confirmed using a dual luciferase reporter gene assay system. The oncogenic role of circABCC1 in OS in vivo was examined by establishing a tumor xenograft model.

RESULTS

CircABCC1 was significantly elevated in OS tissues (about 3.1-folds) and cells (U2OS (about 2.1-folds) and HOS (about 2.8-folds)) compared with the control (p < .05). Silencing of circABCC1 significantly reduced the viability and proliferation, promoted apoptosis, impaired migration and invasion, and increased autophagy of U2OS and HOS cells (p < .05). In addition, miR-591 was confirmed to be a target of circABCC1, exerting an opposite effect to circABCC1 (p < .05). MiR-591 attenuation in U2OS and HOS cells was able to reply to the inhibition of cell proliferation, migration and invasion as well as promotion of cell apoptosis and autophagy mediated by silencing circABCC1 (p < .05). HDAC4 was verified to be the target gene of miR-591 in U2OS and HOS cells and was regulated by the circABCC1/miR-591 axis (p < .05), and restoration of HDAC4 levels in U2OS and HOS cells was able to restore the altered cellular function caused by silencing circABCC1 (p < .05). In addition, knockdown of circABCC1 attenuated tumor growth in vivo (p < .05).

CONCLUSION

Silencing of circABCC1 inhibits osteosarcoma progression by attenuating HDAC4 expression through sponging miR-591.

Research progress of circular RNA molecules in aging and age-related diseases

Circular RNAs (circRNAs) are a class of single-chain endogenous closed circular RNAs that do not have a poly(A) tail at the 3' end and a cap structure at the 5' end and are connected end-to-end by covalent bonds. CircRNAs, which are pervasive, diverse, stable, and conversed, have functions in transcriptional control and protein translation and play vital roles in modulating cell senescence, individual aging, as well as the occurrence and development of age-related diseases. Studies in recent years were reviewed from aspects including the biosynthesis mechanisms, classification, expression, biomedical functions, associations with aging and age-related diseases, and potential clinical applications of circRNAs. It will provide the theoretic basis for exploring the molecular biological mechanisms of aging, using circRNA as the therapeutic target to delay aging, and finding therapeutic strategies to prevent and treat age-related diseases.

Extracellular Vesicles in Colorectal Cancer: From Tumor Growth and Metastasis to Biomarkers and Nanomedications

Colorectal cancer (CRC) is a leading public health concern due to its incidence and high mortality rates, highlighting the requirement of an early diagnosis. Evaluation of circulating extracellular vesicles (EVs) might constitute a noninvasive and reliable approach for CRC detection and for patient follow-up because EVs display the molecular features of the cells they originate. EVs are released by almost all cell types and are mainly categorized as exosomes originating from exocytosis of intraluminal vesicles from multivesicular bodies, ectosomes resulting from outward budding of the plasma membrane and apoptotic bodies' ensuing cell shrinkage. These vesicles play a critical role in intercellular communications during physiological and pathological processes. They facilitate CRC progression and premetastatic niche formation, and they enable transfer of chemotherapy resistance to sensitive cells through the local or remote delivery of their lipid, nucleic acid and protein content. On another note, their stability in the bloodstream, their permeation in tissues and their sheltering of packaged material make engineered EVs suitable vectors for efficient delivery of tracers and therapeutic agents for tumor imaging or treatment. Here, we focus on the physiopathological role of EVs in CRCs, their value in the diagnosis and prognosis and ongoing investigations into therapeutic approaches.

The Role of Tumor Microenvironment in Regulating the Plasticity of Osteosarcoma Cells

Osteosarcoma (OS) is a malignancy that is becoming increasingly common in adolescents. OS stem cells (OSCs) form a dynamic subset of OS cells that are responsible for malignant progression and chemoradiotherapy resistance. The unique properties of OSCs, including self-renewal, multilineage differentiation and metastatic potential, 149 depend closely on their tumor microenvironment. In recent years, the likelihood of its dynamic plasticity has been extensively studied. Importantly, the tumor microenvironment appears to act as the main regulatory component of OS cell plasticity. For these reasons aforementioned, novel strategies for OS treatment focusing on modulating OS cell plasticity and the possibility of modulating the composition of the tumor microenvironment are currently being explored. In this paper, we review recent studies describing the phenomenon of OSCs and factors known to influence phenotypic plasticity. The microenvironment, which can regulate OSC plasticity, has great potential for clinical exploitation and provides different perspectives for drug and treatment design for OS.

Molecular actions of exosomes and their theragnostics in colorectal cancer: current findings and limitations

Extracellular vesicles (EVs) are cell-released, membranous structures essential for intercellular communication. The biochemical compositions and physiological impacts of exosomes, lipid-bound, endosomal origin EVs, have been focused on, especially on the tumor-host interactions in a defined tumor microenvironment (TME). Despite recent progress in targeted therapy and cancer immunotherapy in colorectal cancer (CRC), cancer patients still suffer from distal metastasis and tumor relapse, suggesting unmet needs for biomarkers directing therapeutic interventions and predicting treatment responsiveness. As exosomes are indispensable for intercellular communication and high exosome abundance makes them feasible biomarker molecules, this review discusses exosome heterogeneity and how exosomes orchestrate the interplay among tumor cells, cancer stem cells (CSCs) and host cells, including stromal cells, endothelial cells and immunocytes, in the CRC TME. This review also discusses mechanisms for loading exosomal contents and potential exosomal DNA, RNA and protein biomarkers for early CRC detection. Finally, we summarize the diagnostic and therapeutic exosomes in clinical trials. We envision that detecting and targeting cancer-specific exosomes could provide therapeutic advances in developing personalized cancer medicine.

Bench to Bedside: New Therapeutic Approaches with Extracellular Vesicles and Engineered Biomaterials for Targeting Therapeutic Resistance of Cancer Stem Cells

Cancer has recently been the second leading cause of death worldwide, trailing only cardiovascular disease. Cancer stem cells (CSCs), represented as tumor-initiating cells (TICs), are mainly liable for chemoresistance and disease relapse due to their self-renewal capability and differentiating capacity into different types of tumor cells. The intricate molecular mechanism is necessary to elucidate CSC's chemoresistance properties and cancer recurrence. Establishing efficient strategies for CSC maintenance and enrichment is essential to elucidate the mechanisms and properties of CSCs and CSC-related therapeutic measures. Current approaches are insufficient to mimic the in vivo chemical and physical conditions for the maintenance and growth of CSC and yield unreliable research results. Biomaterials are now widely used for simulating the bone marrow microenvironment. Biomaterial-based three-dimensional (3D) approaches for the enrichment of CSC provide an excellent promise for future drug discovery and elucidation of molecular mechanisms. In the future, the biomaterial-based model will contribute to a more operative and predictive CSC model for cancer therapy. Design strategies for materials, physicochemical cues, and morphology will offer a new direction for future modification and new methods for studying the CSC microenvironment and its chemoresistance property. This review highlights the critical roles of the microenvironmental cues that regulate CSC function and endow them with drug resistance properties. This review also explores the latest advancement and challenges in biomaterial-based scaffold structure for therapeutic approaches against CSC chemoresistance. Since the recent entry of extracellular vesicles (EVs), cell-derived nanostructures, have opened new avenues of investigation into this field, which, together with other more conventionally studied signaling pathways, play an important role in cell-to-cell communication. Thus, this review further explores the subject of EVs in-depth. This review also discusses possible future biomaterial and biomaterial-EV-based models that could be used to study the tumor microenvironment (TME) and will provide possible therapeutic approaches. Finally, this review concludes with potential perspectives and conclusions in this area.

Use of Personalized Biomarkers in Metastatic Colorectal Cancer and the Impact of AI

Colorectal cancer is a major cause of cancer-related death worldwide and is correlated with genetic and epigenetic alterations in the colonic epithelium. Genetic changes play a major role in the pathophysiology of colorectal cancer through the development of gene mutations, but recent research has shown an important role for epigenetic alterations. In this review, we try to describe the current knowledge about epigenetic alterations, including DNA methylation and histone modifications, as well as the role of non-coding RNAs as epigenetic regulators and the prognostic and predictive biomarkers in metastatic colorectal disease that can allow increases in the effectiveness of treatments. Additionally, the intestinal microbiota’s composition can be an important biomarker for the response to strategies based on the immunotherapy of CRC. The identification of biomarkers in mCRC can be enhanced by developing artificial intelligence programs. We present the actual models that implement AI technology as a bridge connecting ncRNAs with tumors and conducted some experiments to improve the quality of the model used as well as the speed of the model that provides answers to users. In order to carry out this task, we implemented six algorithms: the naive Bayes classifier, the random forest classifier, the decision tree classifier, gradient boosted trees, logistic regression and SVM.

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.

Exosomal non-coding RNAs have a significant effect on tumor metastasis

Exosomes are produced by the majority of eukaryotic cells and are capable of transporting a variety of substances, including non-coding RNAs, between cells. Metastasis is a significant cause of death from cancer. Numerous studies have established an important role for exosomal non-coding RNAs in tumor metastasis. Exosomal non-coding RNAs from a variety of cells have been shown to affect tumor metastasis via several mechanisms. Exosomes transmit non-coding RNAs between tumor cells, fibroblasts, endothelial cells, and immune cells within the tumor microenvironment. Exosomal non-coding RNAs also have an effect on epithelial-mesenchymal transition, angiogenesis, and lymphangiogenesis. Exosomes derived from tumor cells have the ability to transport non-coding RNAs to distant organs, thereby facilitating the formation of the metastatic niche. Due to their role in tumor metastasis, exosomal non-coding RNAs have the potential to serve as diagnostic or prognostic markers as well as therapeutic targets for tumors. The purpose of this paper is to review and discuss the mechanisms of exosomal non-coding RNAs, their role in tumor metastasis, and their clinical utility, aiming to establish new directions for tumor metastasis, diagnosis, and treatment research.

The Exosome Journey: From Biogenesis to Regulation and Function in Cancers

Exosomes are a type of small endosomal-derived vesicles ranging from 30 to 150 nm, which can serve as functional mediators in cell-to-cell communication and various physiological and pathological processes. In recent years, exosomes have emerged as crucial mediators of intracellular communication among tumor cells, immune cells, and stromal cells, which can shuttle bioactive molecules, such as proteins, lipids, RNA, and DNA. Exosomes exhibit the high bioavailability, biological stability, targeting specificity, low toxicity, and immune characteristics, suggesting their potentials in the diagnosis and treatment of cancers. They can be applied as an effective tool in the diagnostics, therapeutics, and drug delivery in cancers. This review summarizes the regulation and functions of exosomes in various cancers to augment our understanding of exosomes, which paves the way for parallel advancements in the therapeutic approach of cancers. In this review, we also discuss the challenges and prospects for clinical application of exosome-based diagnostics and therapeutics for cancers.

Exosome-Derived Circ_0094343 Promotes Chemosensitivity of Colorectal Cancer Cells by Regulating Glycolysis via the miR-766-5p/TRIM67 Axis

Objective

Currently, the role of circ_0094343 (circPTEN) on the chemosensitivity of CRC remains to be clarified. This study aimed to investigate the role and mechanism of exosome-delivered circ_0094343 in the proliferation, glycolysis, and chemosensitivity of colorectal cancer (CRC) cells.

Methods

Real-time quantitative polymerase chain reaction (qRT-PCR) was utilized to detect the expression level of circ_0094343, miR-766-5p, and TRIM67 (Tripartite motif-containing 67) in CRC clinical tissue samples and cells, transmission electron microscopy (TEM) to observe the morphology of exosomes, and nanoparticle tracking analysis (NTA) system to measure the diameter of exosomes. Besides, PKH67 fluorescent labeling was applied for assessing the level of exosome uptake by cells, MTT and cell clone formation assays for detecting cell proliferation and clone formation, respectively, and related kits for checking the glucose consumption, lactate production, and extracellular acidification rate (ECAR) in cells. Dual-luciferase reporter (DLR) gene assay was used for verifying the targeting relationship between circ_0094343 and miR-766-5p, miR-766-5p and TRIM67, RNA immunoprecipitation (RIP) experiment for the interaction between circ_0094343 and miR-766-5p, and Western blot for the protein level of exosome surface antigens (HSP70, CD63) and TRIM67 in cells in exosomes and cell lysates.

Results

circ_0094343 was significantly downregulated in CRC tissues, chemotherapy-resistant CRC tissues, and metastatic CRC tissues. Moreover, exosomes-carried circ_0094343 played an inhibitory role in the proliferation, clone formation and glycolysis of HCT116 cells. Meanwhile, it could also improve the chemosensitivity of HCT116 cells to 5-fluorouracil (5-FU), oxaliplatin (L-OHP), and doxorubicin (Dox). Additionally, circ_0094343 acted as a sponge for miR-766-5p, and miR-766-5p targeted and regulated TRIM67. In CRC tissues, miR-766-5p expression was negatively correlated with TRIM67 expression, while circ_0094343 was positively associated with TRIM67. Further, mechanistic validation also demonstrated that circ_0094343 could inhibit HCT116 cell proliferation, clone formation, glycolysis, and chemotherapy resistance via the miR-766-5p/TRIM67 axis.

Conclusion

circ_0094343 inhibited the proliferation, clone formation and glycolysis of CRC cells and improved their chemosensitivity to various chemotherapeutic drugs via the miR-766-5p/TRIM67 axis. This finding may provide new insights into the treatment of CRC.

Analysis of Exosomal Cargo Provides Accurate Clinical, Histologic and Mutational Information in Non-Small Cell Lung Cancer

Simple Summary

Non-small cell lung cancer (NSCLC) is the second most commonly diagnosed cancer and the leading cause of cancer-related death worldwide. Clinical decision-making depends on the histological classification; however, tissue biopsy is frequently not technically feasible due to tumor location or limited tissue samples. Therefore, we propose to find clinical, molecular and histological biomarkers using a minimally invasive approach based on the analysis of the cargo of the blood extracellular vesicles. Exosomes are membranous vesicles present in several biological fluids, which carry biological information to distant tissues, regulating several tumor processes. This study aims to analyze NSCLC exosome cargo for search biomarkers that could improve clinical management. This report demonstrates the possibility of implementing exosomes to detect molecular alterations and as a source of biomarkers to differentiate NSCLC histology, allowing for a new approach in precision oncology.

Abstract

Lung cancer is a malignant disease with high mortality and poor prognosis, frequently diagnosed at advanced stages. Nowadays, immense progress in treatment has been achieved. However, the present scenario continues to be critical, and a full comprehension of tumor progression mechanisms is required, with exosomes being potentially relevant players. Exosomes are membranous vesicles that contain biological information, which can be transported cell-to-cell and modulate relevant processes in the hallmarks of cancer. The present research aims to characterize the exosomes’ cargo and study their role in NSCLC to identify biomarkers. We analyzed exosomes secreted by primary cultures and cell lines, grown in monolayer and tumorsphere formations. Exosomal DNA content showed molecular alterations, whereas RNA high-throughput analysis resulted in a pattern of differentially expressed genes depending on histology. The most significant differences were found in XAGE1B, CABYR, NKX2-1, SEPP1, CAPRIN1, and RIOK3 genes when samples from two independent cohorts of resected NSCLC patients were analyzed. We identified and validated biomarkers for adenocarcinoma and squamous cell carcinoma. Our results could represent a relevant contribution concerning exosomes in clinical practice, allowing for the identification of biomarkers that provide information regarding tumor features, prognosis and clinical behavior of the disease.

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.

Biological functions, mechanisms, and clinical significance of circular RNA in pancreatic cancer: a promising rising star

Pancreatic cancer (PC) is a highly malignant solid tumor with insidious onset and easy early metastasis. Despite tremendous efforts devoted to research in this field, the mechanisms underlying PC tumorigenesis and progression remain unclear. Additionally, robust biomarkers and satisfactory therapeutic strategies for clinical use in PC patients are still lacking. Circular RNAs (circRNAs) are a new type of non-coding RNA originating from precursor messenger RNAs, with a covalent continuous closed-loop structure, strong stability and high specificity. Accumulating evidence suggests that circRNAs may participate in PC development and progression. Abnormal expression of circRNAs in PC is considered a vital factor that affects tumor cell proliferation, migration, invasion, apoptosis, angiogenesis and drug resistance. In this review of relevant articles published in recent years, we describe the basic knowledge concerning circRNAs, including their classification, biogenesis, functions and research approaches. Moreover, the biological roles and clinical significance of circRNAs related to PC are discussed. Finally, we note the questions remaining from recent studies and anticipate that further investigations will address these gaps in knowledge in this field. In conclusion, we expect to provide insights into circRNAs as potential targets for specific PC diagnosis and treatment in the future.

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.

Immune cell responses in pancreatic cancer and their clinical application

Pancreatic cancer is one of the most lethal diseases around the world, for hardly detection and poor prognosis. Recent years, functions of the tumor microenvironment and immune cells attract people’s view and there is emerging evidence implicating some immune cells hold the key points in the metabolism, invasion, and metastasis in pancreatic cancer. In this review, we highlight some main immune cells, such as Tumor-associated neutrophils (TANs) and macrophages (TAMs), Pancreatic stellate cells (PSCs), Myeloid-derived suppressor cells (MDSCs), and Regulatory T cells (Tregs). Furthermore, we review current clinical applications and discuss potential values in future.

Exosomes Derived from SW480-Resistant Colon Cancer Cells Are Promote Angiogenesis via BMP-2/Smad5 Signaling Pathway

Background

Multidrug resistance is the main cause of tumor recurrence and metastasis. Therefore, it is urgent to explore the mechanism and treatment of drug resistance of tumor cells. We aim to investigate the relationship between drug resistance and angiogenesis in SW480 colon cancer cells and the possible underlying mechanism.

Methods

Exosomes were extracted from SW480-sensitive or SW480-resistant colon cancer cells (SW480/oxaliplatin). The CCK-8 assay, migration assay, tube formation assay, qPCR, and Western blotting were performed in human umbilical vein endothelial cells (HUVECs). The underlying mechanisms were detected by Western blotting assays and BMP-2 si-RNA silencing assay in vitro and in vivo.

Results

The conditioned medium and exosomes of SW480/oxaliplatin cells promoted proliferation, migration, and tube formation of HUVECs. The expression of BMP-2 released by SW480/oxaliplatin exosomes was 2.3-folds higher than that by SW480 exosomes. Additionally, exosomal BMP-2 inhibiting the Smad signaling pathway induced the expression of vascular endothelial growth factor and CD31. Silencing of BMP-2 partly blocks the promoting effect of SW480/oxaliplatin exosomes on angiogenesis. Moreover, SW480/oxaliplatin cells increased the BMP-2 expression, consequently promoting angiogenesis in vivo.

Conclusions

SW480-resistant colon cancer exosomes promoted angiogenesis via the BMP-2/Smad signaling pathway, which is potential for the novel treatment for antiangiogenic therapies in colon cancer.

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.

The functional roles of the circRNA/Wnt axis in cancer

CircRNAs, covalently closed noncoding RNAs, are widely expressed in a wide range of species ranging from viruses to plants to mammals. CircRNAs were enriched in the Wnt pathway. Aberrant Wnt pathway activation is involved in the development of various types of cancers. Accumulating evidence indicates that the circRNA/Wnt axis modulates the expression of cancer-associated genes and then regulates cancer progression. Wnt pathway-related circRNA expression is obviously associated with many clinical characteristics. CircRNAs could regulate cell biological functions by interacting with the Wnt pathway. Moreover, Wnt pathway-related circRNAs are promising potential biomarkers for cancer diagnosis, prognosis evaluation, and treatment. In our review, we summarized the recent research progress on the role and clinical application of Wnt pathway-related circRNAs in tumorigenesis and progression.

The emerging landscape of exosomal CircRNAs in solid cancers and hematological malignancies

Circular RNAs (circRNAs) are a type of recently discovered noncoding RNA. They exert their biological functions by competitively binding to microRNAs (miRNAs) as miRNA sponges, promoting gene transcription and participating in the regulation of selective splicing, interacting with proteins and being translated into proteins. Exosomes are derived from intracavitary vesicles (ILVs), which are formed by the inward budding of multivesicular bodies (MVBs), and exosome release plays a pivotal role in intercellular communication. Accumulating evidence indicates that circRNAs in exosomes are associated with solid tumor invasion and metastasis. Additionally, emerging studies in the last 1 ~ 2 years have revealed that exosomal circRNA also have effect on hematological malignancies. In this review, we outline the properties and biological functions of circRNAs and exosomes. In particular, we summarize in detail the mechanism and roles of exosomal circRNAs and highlight their application as novel biomarkers in malignant tumors.

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.

Liquid biopsy at the frontier of detection, prognosis and progression monitoring in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide and a leading cause of carcinogenic death. To date, surgical resection is regarded as the gold standard by the operator for clinical decisions. Because conventional tissue biopsy is invasive and only a small sample can sometimes be obtained, it is unable to represent the heterogeneity of tumor or dynamically monitor tumor progression. Therefore, there is an urgent need to find a new minimally invasive or noninvasive diagnostic strategy to detect CRC at an early stage and monitor CRC recurrence. Over the past years, a new diagnostic concept called “liquid biopsy” has gained much attention. Liquid biopsy is noninvasive, allowing repeated analysis and real-time monitoring of tumor recurrence, metastasis or therapeutic responses. With the advanced development of new molecular techniques in CRC, circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), exosomes, and tumor-educated platelet (TEP) detection have achieved interesting and inspiring results as the most prominent liquid biopsy markers. In this review, we focused on some clinical applications of CTCs, ctDNA, exosomes and TEPs and discuss promising future applications to solve unmet clinical needs in CRC patients.

Circular RNAs in stem cells: from basic research to clinical implications

Circular RNAs (circRNAs) are a special class of endogenous RNAs with a wide variety of pathophysiological functions via diverse mechanisms, including transcription, microRNA (miRNA) sponge, protein sponge/decoy, and translation. Stem cells are pluripotent cells with unique properties of self-renewal and differentiation. Dysregulated circRNAs identified in various stem cell types can affect stem cell self-renewal and differentiation potential by manipulating stemness. However, the emerging roles of circRNAs in stem cells remain largely unknown. This review summarizes the major functions and mechanisms of action of circRNAs in stem cell biology and disease progression. We also highlight circRNA-mediated common pathways in diverse stem cell types and discuss their diagnostic significance with respect to stem cell-based therapy.

Exosomal circular RNAs: A new frontier in the metastasis of digestive system tumors

Exosomes are membrane vesicles with a diameter of 30–150 nm. Exosomes are secreted by various types of tumor cell and contain a variety of proteins, circular RNAs (circRNAs), microRNAs and DNA, depending on the host cells. Among them, circRNAs, which are long non-coding endogenous RNAs, form covalently closed and continuous loops that link the 3′ and 5′ terminals generated by back-splicing. circRNAs have become a hotspot of research. Exosomal circRNAs are in volved in the pathogenesis of cancer, especially metastasis, which is mainly ascribed to the frequently abnormal expression levels within neoplasms. Nonetheless, the functions and regulatory mechanisms of exosomal circRNAs in the progression of digestive system tumors (DSTs) remain unclear. More knowledge on the regulation and network interactions of exosomal circRNAs will help identify superior treatment strategies for the metastasis of DSTs. The present review aims to summarize the existing studies on the functions and mechanisms of exosomal circRNAs in tumorigenesis, and evaluate the associations between the dysregulation of exosomal circRNAs and tumor metastasis.

The emerging roles of circular RNAs in vessel co-option and vasculogenic mimicry: clinical insights for anti-angiogenic therapy in cancers

Unexpected resistance to anti-angiogenic treatment prompted the investigation of non-angiogenic tumor processes. Vessel co-option (VC) and vasculogenic mimicry (VM) are recognized as primary non-angiogenic mechanisms. In VC, cancer cells utilize pre-existing blood vessels for support, whereas in VM, cancer cells channel and provide blood flow to rapidly growing tumors. Both processes have been implicated in the development of tumor and resistance to anti-angiogenic drugs in many tumor types. The morphology, but rare molecular alterations have been investigated in VC and VM. There is a pressing need to better understand the underlying cellular and molecular mechanisms. Here, we review the emerging circular RNA (circRNA)-mediated regulation of non-angiogenic processes, VC and VM.

Extracellular Vesicles and Cancer Stem Cells in Tumor Progression: New Therapeutic Perspectives

Tumor burden is a complex microenvironment where different cell populations coexist and have intense cross-talk. Among them, a heterogeneous population of tumor cells with staminal features are grouped under the definition of cancer stem cells (CSCs). CSCs are also considered responsible for tumor progression, drug resistance, and disease relapse. Furthermore, CSCs secrete a wide variety of extracellular vesicles (EVs) with different cargos, including proteins, lipids, ssDNA, dsDNA, mRNA, siRNA, or miRNA. EVs are internalized by other cells, orienting the microenvironment toward a protumorigenic and prometastatic one. Given their importance in tumor growth and metastasis, EVs could be exploited as a new therapeutic target. The inhibition of biogenesis, release, or uptake of EVs could represent an efficacious strategy to impair the cross-talk between CSCs and other cells present in the tumor microenvironment. Moreover, natural or synthetic EVs could represent suitable carriers for drugs or bioactive molecules to target specific cell populations, including CSCs. This review will discuss the role of CSCs and EVs in tumor growth, progression, and metastasis and how they affect drug resistance and disease relapse. Furthermore, we will analyze the potential role of EVs as a target or vehicle of new therapies.

The effective function of circular RNA in colorectal cancer

Colorectal cancer (CRC) is the 3rd most common type of cancer worldwide. Late detection plays role in one-third of annual mortality due to CRC. Therefore, it is essential to find a precise and optimal diagnostic and prognostic biomarker for the identification and treatment of colorectal tumorigenesis. Covalently closed, circular RNAs (circRNAs) are a class of non-coding RNAs, which can have the same function as microRNA (miRNA) sponges, as regulators of splicing and transcription, and as interactors with RNA-binding proteins (RBPs). Therefore, circRNAs have been investigated as specific targets for diagnostic and prognostic detection of CRC. These non-coding RNAs are also linked to metastasis, proliferation, differentiation, migration, angiogenesis, apoptosis, and drug resistance, illustrating the importance of understanding their involvement in the molecular mechanisms of development and progression of CRC. In this review, we present a detailed summary of recent findings relating to the dysregulation of circRNAs and their potential role in CRC.

Circular RNA Circ_0000677 promotes cell proliferation by regulating microRNA-106b-5p/CCND1 in non-small cell lung cancer

Recently, circular RNAs (circRNAs) have become an intense focus of research and large numbers of circRNAs have been identified, awaiting functional elucidation. Thus, the present study aims to examine the regulation of circRNAs and its molecular mechanism in lung cancer growth. Here, we show that circular RNA circ_0000677 was overexpressed and correlated with poor prognosis in non‐small cell lung cancer (NSCLC) patients. Functionally, circ_0000677 knockdown markedly inhibited proliferation of NSCLC cells by observing of immunofluorescence staining of Ki67, clone formation assay, and xenograft experiments. In mechanism, circ_0000677 acted as a sponge of microRNA-106b and further regulated CCDND1 gene expression in NSCLC cells by dual luciferase activity assay and their expression examination. Taken together, these findings suggest a role for circ_0000677/miR-106b/CCND1 regulation axis in promoting NSCLC growth and progression.

Exosomal circRNAs: new players in colorectal cancer

Colorectal cancer (CRC) is one of the most malignant cancer types, characterized by elevated mortality rate and treatment resistance. Despite the progress achieved in the explanation of the molecular basis of the disease as well as introducing potential biomarkers in the clinical practice, further investigation is essential to identify innovative molecules that contribute to colorectal carcinogenesis. Circular RNAs (circRNAs) are a novel and unexplored RNA type, associated with various human pathological conditions. Recently, circRNAs have been identified to be enriched and stable in exosomes and can exert their functions when exosomes reach neighboring or distant cells. Increasing evidence indicates that these so called exosomal circRNAs (exo-circRNAs) act as signaling molecules to regulate cancer proliferation, metastasis, and sensitivity to radio- and chemotherapy. This review aims to discuss the latest progress in exo-circRNAs studies in CRC with an emphasis on their potential as promising diagnostic molecular markers and therapeutic targets.

ATP-binding cassette (ABC) transporters in cancer: A review of recent updates

The ATP-binding cassette (ABC) transporter superfamily is one of the largest membrane protein families existing in wide spectrum of organisms from prokaryotes to human. ABC transporters are also known as efflux pumps because they mediate the cross-membrane transportation of various endo- and xenobiotic molecules energized by ATP hydrolysis. Therefore, ABC transporters have been considered closely to multidrug resistance (MDR) in cancer, where the efflux of structurally distinct chemotherapeutic drugs causes reduced itherapeutic efficacy. Besides, ABC transporters also play other critical biological roles in cancer such as signal transduction. During the past decades, extensive efforts have been made in understanding the structure-function relationship, transportation profile of ABC transporters, as well as the possibility to overcome MDR via targeting these transporters. In this review, we discuss the most recent knowledge regarding ABC transporters and cancer drug resistance in order to provide insights for the development of more effective therapies.

Expression of the circular RNAs in astaxanthin promotes cholesterol efflux from THP-1 cells based on RNA-seq

BACKGROUND

It is reported that circular RNAs (circRNAs) play a key role in atherosclerosis (AS). Foam cell formation, which is the main feature of AS, can be significantly inhibited by cholesterol efflux.

METHODS

We established a model of astaxanthin (AST) promoting cholesterol efflux from macrophages through oil red O staining, real-time quantitative PCR (qRT-PCR), and western blot and used RNA sequencing to detect the expression of circRNAs in AST-treated and untreated THP-1 cells. Finally, siRNA transfection screened out circRNAs that were significantly differentially expressed. The data analysis was performed by Student's t test and P < 0.05 was considered statistically significant.

RESULTS

In the model of AST promoting cholesterol efflux from THP-1 cells, there were a total of 7276 circRNAs differentially expressed, among which the top 25 upregulated and the top 25 downregulated circRNAs were selected based on the log2 (fold change). GO analysis showed that differential expression of circRNAs in biological process (2066/3098; 66.69%), molecular function (543/3098; 17.53%), and cellular component (489/3098; 15.78%). Based on KEGG analysis, RNA transport was the most enriched pathway. Finally, we obtained 3 significantly upregulated circRNAs by siRNA transfection and qRT-PCR.

CONCLUSIONS

The 3 differentially expressed circRNAs may play an important role in the process of AST promoting cholesterol efflux and may be used as biomarkers to prevent AS.

Circ-GALNT16 restrains colorectal cancer progression by enhancing the SUMOylation of hnRNPK

BACKGROUND

Recent studies have investigated the role of circular RNAs (circRNAs) as significant regulatory factors in multiple cancer progression. Nevertheless, the biological functions of circRNAs and the underlying mechanisms by which they regulate colorectal cancer (CRC) progression remain unclear.

METHODS

A novel circRNA (circ-GALNT16) was identified by microarray and qRT-PCR. A series of in vitro and in vivo phenotype experiments were performed to investigate the role of circ-GALNT16 in CRC. The FISH, RNA pulldown assay, RIP assay, RNA sequencing, coimmunoprecipitation, and ChIP were performed to investigate the molecular mechanisms of circ-GALNT16 in CRC progression.

RESULTS

Circ-GALNT16 was downregulated in CRC and was negatively correlated with poor prognosis. Circ-GALNT16 suppressed the proliferation and metastatic ability of CRC cells in vitro and in vivo. Mechanistically, circ-GALNT16 could bind to the KH3 domain of heterogeneous nuclear ribonucleoprotein K (hnRNPK), which promoted the SUMOylation of hnRNPK. Additionally, circ-GALNT16 could enhance the formation of the hnRNPK-p53 complex by facilitating the SUMOylation of hnRNPK. RNA sequencing assay identified serpin family E member 1 as the target gene of circ-GALNT16 at the transcriptional level. Rescue assays revealed that circ-GALNT16 regulated the expression of Serpine1 by inhibiting the deSUMOylation of hnRNPK mediated by SUMO-specific peptidase 2 and then regulating the sequence-specific DNA binding ability of the hnRNPK-p53 transcriptional complex.

CONCLUSIONS

Circ-GALNT16 suppressed CRC progression by inhibiting Serpine1 expression through regulating the sequence-specific DNA binding ability of the SENP2-mediated hnRNPK-p53 transcriptional complex and might function as a biomarker and therapeutic target for CRC.

Roles of circular RNAs in colorectal cancer

Colorectal cancer (CRC) is one of the most common types of malignant cancer worldwide and poses a significant burden on both the individual and healthcare systems. Despite advances in treatment options, advanced-stage CRC has a high mortality rate due to its heterogeneity, metastatic potential and/or delay in diagnosis. In recent years, an increasing number of studies have indicated that circular RNAs (circRNAs) serve important roles in several types of cancer, including CRC. Recent studies have revealed that circRNAs are aberrantly expressed in CRC tissues and function as oncogenic or tumor suppressive regulators of CRC carcinogenesis and development. Numerous circRNAs have been associated with the clinicopathological features of patients with CRC and have been considered as potential biomarkers for the diagnosis and prognosis of CRC, as well as targets for treatment. However, a deeper understanding of their potential function is required. In the present review, the current body of knowledge on the biogenesis and functions of CRC-associated circRNAs, and their potential value in clinical applications, such as in CRC diagnosis, prognosis and treatment, is discussed and summarized.