Exosome circ_0044516 promotes prostate cancer cell proliferation and metastasis as a potential biomarker

Exosomes are the mediators between the tumor microenvironment and prostate cancer (Review)

Prostate cancer poses a serious threat to the well-being of men worldwide, with the leading cause of mortality being primarily through metastasis. Prostate cancer metastasis is dependent on cell communication, which is an essential component of this process; yet its exact mechanism remains obscure. Nonetheless, cell-to-cell communication plays a critical part in prostate cancer metastasis. Exosomes play an indispensable role in the development of metastatic growth by promoting intercellular communication. They are pivotal regulatory agents for both prostate cancer cells as well as their microenvironment. The present study investigated the makeup and function of exosomes in the tumor microenvironment, highlighting their significance to prostate cancer metastasis.

Current landscape of exosomal non-coding RNAs in prostate cancer: Modulators and biomarkers

Prostate cancer (PCa) has the highest frequency of diagnosis among solid tumors and ranks second as the primary cause of cancer-related deaths. Non-coding RNAs (ncRNAs), such as microRNAs, long non-coding RNAs and circular RNAs, frequently exhibit dysregulation and substantially impact the biological behavior of PCa. Compared with circulating ncRNAs, ncRNAs loaded into exosomes are more stable because of protection by the lipid bilayer. Furthermore, exosomal ncRNAs facilitate the intercellular transfer of molecules and information. Increasing evidence suggests that exosomal ncRNAs hold promising potential in the progression, diagnosis and prognosis of PCa. This review aims to discuss the functions of exosomal ncRNAs in PCa, evaluate their possible applications as clinical biomarkers and therapeutic targets, and provide a comprehensive overview of the ncRNAs regulatory network in PCa. We also identified ncRNAs that can be utilized as biomarkers for diagnosis, staging, grading and prognosis assessment in PCa. This review offers researchers a fresh perspective on the functions of exosomal ncRNAs in PCa and provides additional options for its diagnosis, progression monitoring, and prognostic prediction.

The Role of Extracellular Vesicles in the Treatment of Prostate Cancer

Prostate cancer (PCa) has become a public health concern in elderly men due to an ever-increasing number of estimated cases. Unfortunately, the available treatments are unsatisfactory because of a lack of a durable response, especially in advanced disease states. Extracellular vesicles (EVs) are lipid-bilayer encircled nanoscale vesicles that carry numerous biomolecules (e.g., nucleic acids, proteins, and lipids), mediating the transfer of information. The past decade has witnessed a wide range of EV applications in both diagnostics and therapeutics. First, EV-based non-invasive liquid biopsies provide biomarkers in various clinical scenarios to guide treatment; EVs can facilitate the grading and staging of patients for appropriate treatment selection. Second, EVs play a pivotal role in pathophysiological processes via intercellular communication. Targeting key molecules involved in EV-mediated tumor progression (e.g., proliferation, angiogenesis, metastasis, immune escape, and drug resistance) is a potential approach for curbing PCa. Third, EVs are promising drug carriers. Naïve EVs from various sources and engineered EV-based drug delivery systems have paved the way for the development of new treatment modalities. This review discusses the recent advancements in the application of EV therapies and highlights EV-based functional materials as novel interventions for PCa.

Circular RNAs in human diseases

Circular RNAs (circRNAs) are a unique class of RNA molecules formed through back-splicing rather than linear splicing. As an emerging field in molecular biology, circRNAs have garnered significant attention due to their distinct structure and potential functional implications. A comprehensive understanding of circRNAs' functions and potential clinical applications remains elusive despite accumulating evidence of their involvement in disease pathogenesis. Recent research highlights their significant roles in various human diseases, but comprehensive reviews on their functions and applications remain scarce. This review provides an in-depth examination of circRNAs, focusing first on their involvement in non-neoplastic diseases such as respiratory, endocrine, metabolic, musculoskeletal, cardiovascular, and renal disorders. We then explore their roles in tumors, with particular emphasis on exosomal circular RNAs, which are crucial for cancer initiation, progression, and resistance to treatment. By detailing their biogenesis, functions, and impact on disease mechanisms, this review underscores the potential of circRNAs as diagnostic biomarkers and therapeutic targets. The review not only enhances our understanding of circRNAs' roles in specific diseases and tumor types but also highlights their potential as novel diagnostic and therapeutic tools, thereby paving the way for future clinical investigations and potential therapeutic interventions.

Nanomedicines in diagnosis and treatment of prostate cancers: an updated review

Prostate cancer (PC) is the third most common male cancer in the world, which occurs due to various mutations leading to the loss of chromatin structure. There are multiple treatments for this type of cancer, of which chemotherapy is one of the most important. Sometimes, a combination of different treatments, such as chemotherapy, radiotherapy, and surgery, are used to prevent tumor recurrence. Among other treatments, androgen deprivation therapy (ADT) can be mentioned, which has had promising results. One of the drawbacks of chemotherapy and ADT treatments is that they are not targeted to the tumor tissue. For this reason, their use can cause extensive side effects. Treatments based on nanomaterials, known as nanomedicine, have attracted much attention today. Nanoparticles (NPs) are one of the main branches of nanomedicine, and they can be made of different materials such as polymer, metal, and carbon, each of which has distinct characteristics. In addition to NPs, nanovesicles (NVs) also have therapeutic applications in PC. In treating PC, synthetic NVs (liposomes, micelles, and nanobubbles) or produced from cells (exosomes) can be used. In addition to the role that NPs and NVs have in treating PC, due to being targeted, they can be used to diagnose PC and check the treatment process. Knowing the characteristics of nanomedicine-based treatments can help design new treatments and improve researchers' understanding of tumor biology and its rapid diagnosis. In this study, we will discuss conventional and nanomedicine-based treatments. The results of these studies show that the use of NPs and NVs in combination with conventional treatments has higher efficacy in tumor treatment than the individual use of each of them.

Emerging biomarkers for non-invasive diagnosis and treatment of cancer: a systematic review

Cancer remains a global health challenge, necessitating continuous advancements in diagnostic and treatment strategies. This review focuses on the utility of non-invasive biomarkers in cancer diagnosis and treatment, their role in early detection, disease monitoring, and personalized therapeutic interventions. Through a systematic review of the literature, we identified 45 relevant studies that highlight the potential of these biomarkers across various cancer types, such as breast, prostate, lung, and colorectal cancers. The non-invasive biomarkers discussed include liquid biopsies, epigenetic markers, non-coding RNAs, exosomal cargo, and metabolites. Notably, liquid biopsies, particularly those based on circulating tumour DNA (ctDNA), have emerged as the most promising method for early, non-invasive cancer detection due to their ability to provide comprehensive genetic and epigenetic information from easily accessible blood samples. This review demonstrates how non-invasive biomarkers can facilitate early cancer detection, accurate subtyping, and tailored treatment strategies, thereby improving patient outcomes. It underscores the transformative potential of non-invasive biomarkers in oncology, highlighting their application for enhancing early detection, survival rates, and treatment precision in cancer care.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023474749 PROSPERO, identifier CRD42023474749.

Non-coding RNAs as therapeutic targets in cancer and its clinical application

Cancer genomics has led to the discovery of numerous oncogenes and tumor suppressor genes that play critical roles in cancer development and progression. Oncogenes promote cell growth and proliferation, whereas tumor suppressor genes inhibit cell growth and division. The dysregulation of these genes can lead to the development of cancer. Recent studies have focused on non-coding RNAs (ncRNAs), including circular RNA (circRNA), long non-coding RNA (lncRNA), and microRNA (miRNA), as therapeutic targets for cancer. In this article, we discuss the oncogenes and tumor suppressor genes of ncRNAs associated with different types of cancer and their potential as therapeutic targets. Here, we highlight the mechanisms of action of these genes and their clinical applications in cancer treatment. Understanding the molecular mechanisms underlying cancer development and identifying specific therapeutic targets are essential steps towards the development of effective cancer treatments.

CircUGGT2 facilitates progression and cisplatin resistance of bladder cancer through nonhomologous end-joining pathway

The development of resistance to cisplatin (CDDP) in bladder cancer presents a notable obstacle, with indications pointing to the substantial role of circular RNAs (circRNAs) in this resistance. Nevertheless, the precise mechanisms through which circRNAs govern resistance are not yet fully understood. Our findings demonstrate that circUGGT2 is significantly upregulated in bladder cancer, facilitating cancer cell migration and invasion. Additionally, our analysis of eighty patient outcomes revealed a negative correlation between circUGGT2 expression levels and prognosis. Using circRNA pull-down assays, mass spectrometry analyses, and RNA Immunoprecipitation (RIP), it was shown that circUGGT2 interacts with the KU heterodimer, consisting of KU70 and KU80. Both KU70 and KU80 are critical components of the non-homologous end joining (NHEJ) pathway, which plays a role in CDDP resistance. Flow cytometry was utilized in this study to illustrate the impact of circUGGT2 on the sensitivity of bladder cancer cell lines to CDDP through its interaction with KU70 and KU80. Additionally, a reduction in the levels of DNA repair factors associated with the NHEJ pathway, such as KU70, KU80, DNA-PKcs, and XRCC4, was observed in chromatin of bladder cancer cells following circUGGT2 knockdown post-CDDP treatment, while the levels of DNA repair factors in total cellular proteins remained constant. Thus, the promotion of CDDP resistance by circUGGT2 is attributed to its facilitation of repair factor recruitment to DNA breaks via interaction with the KU heterodimer. Furthermore, our study demonstrated that knockdown of circUGGT2 resulted in reduced levels of γH2AX, a marker of DNA damage response, in CDDP-treated bladder cancer cells, implicating circUGGT2 in the NHEJ pathway for DNA repair.

Computational approaches and challenges in the analysis of circRNA data

Circular RNAs (circRNA) are a class of non-coding RNA, forming a single-stranded covalently closed loop structure generated via back-splicing. Advancements in sequencing methods and technologies in conjunction with algorithmic developments of bioinformatics tools have enabled researchers to characterise the origin and function of circRNAs, with practical applications as a biomarker of diseases becoming increasingly relevant. Computational methods developed for circRNA analysis are predicated on detecting the chimeric back-splice junction of circRNAs whilst mitigating false-positive sequencing artefacts. In this review, we discuss in detail the computational strategies developed for circRNA identification, highlighting a selection of tool strengths, weaknesses and assumptions. In addition to circRNA identification tools, we describe methods for characterising the role of circRNAs within the competing endogenous RNA (ceRNA) network, their interactions with RNA-binding proteins, and publicly available databases for rich circRNA annotation.

Exosomal circRNAs: Novel biomarkers and therapeutic targets for urinary tumors

Exosomal circRNAs have emerged as promising biomarkers and therapeutic targets for urinary tumors. In this review, we explored the intricate role of exosomal circRNAs in urological cancers, focusing on their biological functions, dysregulation in tumors, and potential clinical applications. The review delves into the mechanisms by which exosomal circRNAs contribute to tumor progression and highlights their diagnostic and therapeutic implications. By synthesizing current research findings, we present a compelling case for the significance of exosomal circRNAs in the context of urinary tumors. Furthermore, the review discusses the challenges and opportunities associated with utilizing exosomal circRNAs as diagnostic tools and targeted therapeutic agents. There is a need for further research to elucidate the specific mechanisms of exosomal circRNA secretion and delivery, as well as to enhance the detection methods for clinical translational applications. Overall, this comprehensive review underscores the pivotal role of exosomal circRNAs in urinary tumors and underscores their potential as valuable biomarkers and therapeutic tools in the management of urological cancers.

Engineered exosomes with enhanced stability and delivery efficiency for glioblastoma therapy

Due to the blood-brain barrier (BBB), the application of chemical drugs for glioblastoma treatment is severely limited. Recently, exosomes have been widely applied for drug delivery to the brain. However, the differences in brain targeting efficiency among exosomes derived from different cell sources, as well as the premature drug leakage during circulation, still limit the therapeutic efficacy. Here, we designed a functional oligopeptide-modified exosome loaded with doxorubicin (Pep2-Exos-DOX) for glioblastoma treatment. BV2 mouse microglial cell line was selected as the exosome source due to the favorable BBB penetration. To avoid drug release in the circulation, a redox-response oligopeptide was designed for incorporation into the membranes of exosomes to lock the drug during circulation. The enrichment of the drug in glioblastoma was confirmed. Pharmacodynamic evaluation showed Pep2-Exos-DOX possessed significant anti-cancer activity against glioblastoma as well as relative biosafety. This exosome-based drug delivery system modified with redox-response oligopeptides provides us a novel strategy for brain diseases treatment.

Circ_0082878 contributes to prostate cancer progression via the miR-455-3p/WTAP axis

Circ_0082878 has been found to be strongly expressed in prostate cancer (PCa). However, its roles and potential mechanism in PCa have not been investigated. This study aims to clarify it. RNase R digestion method was adopted for verifying the circular structure of circ_0082878. RT-qPCR assay is aimed to detect the expressions of circ_0082878, miR-455-3p and WTAP in PCa tissues and cells. For identifying cell proliferation, migration and invasion abilities, CCK-8 and transwell assay were used. To show the correlation between miR-455-3p and WTAP or circ_0082878, the luciferase reporter gene, RNA RIP and RNA pull-down experiments were employed. We employed western blot to detect protein level of WTAP. In addition, the impact of circ_0082878 on PCa cells in vivo was also studied. It was found that circ_0082878 and WTAP were highly expressed in PCa tissues and cells, whereas miR-455-3p was lowly expressed. Inhibition of circ_0082878 restrained the growth of PCa in vitro and in vivo. Regarding mechanism, miR-455-3p was the target of circ_0082878, and WTAP was the target of miR-455-3p. Circ_0082878 could downregulate the level of miR-455-3p, and inhibiting of miR-455-3p expression could partially eliminate the inhibitory impact of low expression of circ_0082878 on the proliferation and migration of PCa cells. Additionally, over-expression of miR-455-3p resulted in the reduced level of WTAP, and WTAP over-expression counteracted the tumor suppressive impact of miR-455-3p in PCa cells. Moreover, the obtained findings indicated that circ_0082878 may exert tumor-promoting activity in PCa via sponging miR-455-3p and then upregulating WTAP. This indicates that the circ_0082878/miR-455-3p/WTAP axis can probably become the possible therapeutic target for PCa.

Roles of exosome-derived non-coding RNA in tumor micro-environment and its clinical application

Tumor-derived exosomes play an important role in the tumor micro-environment. The exosome-derived non-coding RNAs are transmitted in the tumor microenvironment in three ways, communication between tumor cells, normal cells affecting tumor cells, and tumor cells affecting normal cells. Through these three ways, exosomal non-coding RNAs are involved in the regulation of tumor progression, affecting tumor angiogenesis, tumor invasiveness, drug resistance, stemness, tumor metabolic repro-gramming and immune escape, resulting in dual roles in promoting or inhibiting tumor development. Exosomes have a membranous structure and their contents are resistant to degradation by extracellular proteases and remain highly stable in body fluids, thus exosome-derived non-coding RNAs are expected to serve as diagnostic and prognostic indicators for a variety of cancers. In addition, exosomes can be used to deliver non-coding RNAs for targeted therapy, or to knock down or modify tumor-promoting non-coding RNAs for tumor therapy. This article reviews the function and communication mechanism of exosomal non-coding RNAs in the tumor microenvironment, including their pathways of action, effects, potential values for tumor biomarkers and treatment targets. This article also points out the issues that need to be further studied in order to promote the progress of extracellular non-coding RNAs in cancer research and their application in tumor diagnosis and treatment.

The multifaceted role of extracellular vesicles in prostate cancer-a review

Prostate cancer is the second most prominent form of cancer in men and confers the highest mortality after lung cancer. The term "extracellular vesicles" refers to minute endosomal-derived membrane microvesicles and it was demonstrated that extracellular vesicles affect the environment in which tumors originate. Extracellular vesicles' involvement is also established in the development of drug resistance, angiogenesis, stemness, and radioresistance in various cancers including prostate cancer. Extracellular vesicles influence the general environment, processes, and growth of prostate cancer and can be a potential area that offers a significant lead in prostate cancer therapy. In this review, we have elaborated on the multifaceted role of extracellular vesicles in various processes involved in the development of prostate cancer, and their multitude of applications in the diagnosis and treatment of prostate cancer through the encapsulation of various bioactives.

Exosomal circKDM4A Induces CUL4B to Promote Prostate Cancer Cell Malignancy in a miR-338-3p-Dependent Manner

Circular RNA lysine demethylase 4A (circKDM4A) is also named circ_0012098 and its abnormal expression has been confirmed in serum exosomes of prostate cancer (PC) patients. However, whether PC progression involves the exosomal circ_0012098 remains unknown. RNA expression of circKDM4A, microRNA-338-3p (miR-338-3p) and cullin 4B (CUL4B) was detected by quantitative real-time polymerase chain reaction. Protein expression was checked by Western blot. The positive expression rate of nuclear proliferation marker (ki-67) was analyzed by immunohistochemistry assay. Dual-luciferase reporter assay and RNA immunoprecipitation assay were used to identify the interaction between miR-338-3p and circKDM4A or CUL4B. Mouse model assay was performed to determine the effect of exosomal circKDM4A on tumorigenesis in vivo. CircKDM4A expression was significantly upregulated in the serum exosomes from PC patients compared with the exosomes from healthy volunteers. Exosomes treatment promoted the proliferation, migration and invasion of PC cells but inhibited apoptosis; however, these effects were attenuated after circKDM4A knockdown. Meanwhile, circKDM4A depletion restored exosome-increased circKDM4A expression. Additionally, circKDM4A acted as a miR-338-3p sponge, and miR-338-3p bound to CUL4B in PC cells. CircKDM4A regulated the effect of exosome-induced PC cell malignancy by interacting with miR-338-3p and CUL4B. Moreover, circKDM4A silencing relieved exosome-induced tumor growth in vivo. Exosomal circKDM4A promoted PC malignant progression by the miR-338-3p/CUL4B axis, providing a therapeutic target for PC.

Circular RNAs in extracellular vesicles: Promising candidate biomarkers for schizophrenia

As one of common and severe mental illnesses, schizophrenia is difficult to be diagnosed exactly. Both its pathogenesis and the causes of its development are still uncertain because of its etiology complexity. At present, the diagnosis of schizophrenia is mainly based on the patient's symptoms and signs, lacking reliable biomarkers that can be used for diagnosis. Circular RNAs in extracellular vesicles (EV circRNAs) can be used as promising candidate biomarkers for schizophrenia and other diseases, for they are not only high stability and disease specificity, but also are rich in contents and easy to be detected. The review is to focus on the research progress of the correlation between circRNAs and schizophrenia, and then to explores the possibility of EV circRNAs as new biomarkers for the schizophrenia diagnosis.

MiR-29a-3p: a potential biomarker and therapeutic target in colorectal cancer

Cancer is frequently caused by microRNAs, which control post-transcriptional levels of gene expression by binding to target mRNAs. MiR-29a-3p has recently been shown to play a twofold function in the majority of malignancies, including colorectal cancer (CRC), according to mounting evidence. Here, we not only briefly summarize such connection between miR-29a-3p and cancers, but aslo primarily evaluate the miR-29a-3p expression pattern, clinical applicability, and molecular mechanisms in CRC to provide a guide for future studies. This review established the diagnostic and prognostic value of miR-29a-3p abnormalty in a variety of clinical samples for CRC. Furthermore, current molecular mechanisms of miR-29a-3p for regulating cancerous biological processes such growth, invasion, metastasis, the epithelial-mesenchymal transformation process, and immunomodulation through its upstream regulatory factors and downstream targeted genes were briefly explored. More specifically, miR-29a-3p has been linked to a few medications that have been shown to have anticancer benefits. To sum up, miR-29a-3p is a promising biomarker and prospective therapeutic target for the diagnosis and prognosis of CRC, but further research is still needed to establish a theoretical basis for more practical applications.

Role of Exosomal Non-Coding RNA in the Tumour Microenvironment of Genitourinary System Tumours

In recent years, genitourinary system tumors are common in people of all ages, seriously affecting the quality of life of patients, the pathogenesis and treatment of these diseases are constantly being updated and improved. Exosomes, with a lipid bilayer that enable delivery of their contents into body fluids or other cells. Exosomes can regulate the tumor microenvironment, and play an important role in tumor development. In turn, cellular and non-cellular components of tumor microenvironment also affect the occurrence, progression, invasion and metastasis of tumor. Non-coding RNAs have been shown to be able to be ingested and released by exosomes, and are seen as a potential tool in cancer diagnosis and treatment. Here, we summarize the effect of non-coding RNAs of exosome contents on the tumor microenvironment of genitourinary system tumor, expound the significance of non-coding RNAs of exosome in the occurrence, development, diagnosis and treatment of cancers.

Current Status of Research on Small Extracellular Vesicles for the Diagnosis and Treatment of Urological Tumors

Extracellular vesicles (EVs) are important mediators of communication between tumor cells and normal cells. These vesicles are rich in a variety of contents such as RNA, DNA, and proteins, and can be involved in angiogenesis, epithelial-mesenchymal transition, the formation of pre-metastatic ecological niches, and the regulation of the tumor microenvironment. Small extracellular vesicles (sEVs) are a type of EVs. Currently, the main treatments for urological tumors are surgery, radiotherapy, and targeted therapy. However, urological tumors are difficult to diagnose and treat due to their high metastatic rate, tendency to develop drug resistance, and the low sensitivity of liquid biopsies. Numerous studies have shown that sEVs offer novel therapeutic options for tumor treatment, such as tumor vaccines and tumor drug carriers. sEVs have attracted a great deal of attention owing to their contribution to in intercellular communication, and as novel biomarkers, and role in the treatment of urological tumors. This article reviews the research and applications of sEVs in the diagnosis and treatment of urological tumors.

The Role and Application of Exosomes and Their Cargos in Reproductive Diseases: A Systematic Review

In recent years, the incidence of the reproductive diseases is increasing year-by-year, leading to abortion or fetal arrest, which seriously affects the reproductive health of human beings and the reproductive efficiency of animals. Exosomes are phospholipid bilayer vesicles that are widely distributed in living organisms and released by the cells of various organs and tissues. Exosomes contain proteins, RNA, lipids, and other components and are important carriers of information transfer between cells, which play a variety of physiological and pathological regulatory functions. More and more studies have found that exosomes and their connotations play an important role in the diagnosis, prognosis and treatment of diseases. A systematic review was conducted in this manuscript and then highlights our knowledge about the diagnostic and therapeutic applications of exosomes to reproductive diseases, such as polycystic ovary syndrome (PCOS), endometriosis, premature ovarian failure (POF), preeclampsia, polycystic, endometrial cancer, cervical cancer, ovarian cancer, and prostate gland cancer.

The LINC00852/miR-29a-3p/JARID2 axis regulates the proliferation and invasion of prostate cancer cell

Long intergenic non-coding RNA 00852 (LINC00852) has been shown to promote the progression of many different cancers including prostate cancer. However, the involved mechanism in promoting the proliferation, migration and invasion of prostate cancer cells has not been reported. In this study, we found that LINC00852 was highly expressed in the tissue of prostate cancer using quantitative reverse transcription PCR (qRT-PCR). CCK-8 assay, colony formation experiment, Transwell migration and invasion experiments were performed to prove that the up-regulation of LINC00852 could promote the proliferation, migration and invasion of prostate cancer cells in vitro. Xenograft tumors experiments in nude mice confirmed that up-regulation of LINC00852 promoted the proliferation of prostate cancer cells in vivo. Bioinformatics predictions and dual-luciferase reporter gene assay showed that miR-29a-3p binds to the 3'-untranslated region of JARID2, and the enhancement of miR-29a-3p could reverse the effect of LINC00852 overexpression in vitro. Moreover, the results of qRT-PCR and western blot showed that LINC00852 could regulate the expression of JARID2 through miR-29a-3p induction. In summary, we demonstrated that LINC00852 played a key role in promoting the prostate cancer, and LINC00852/miR-29a-3p/JARID2 axis could be used as a target for prostate cancer treatment.

Exosome-delivered circSATB2 targets the miR-330-5p/PEAK1 axis to regulate proliferation, migration and invasion of lung cancer cells

Exosomes can carry various kinds of RNAs to mediate intercellular communication. Circular RNA (circRNA) special AT-rich sequence-binding protein 2 (circSATB2) was identified as an oncogene in lung cancer. This study was performed to explore the association of circSATB2 with exosomes and the regulatory mechanism of circSATB2. Exosomes could transmit circSATB2 into lung cancer cells. Exosomes enhanced cell proliferation, invasion, and migration by carrying circSATB2. Exosomal circSATB2 abrogated the inhibitory effect of short hairpin (sh)-circSATB2 on lung cancer progression. Moreover, circSATB2 promoted tumor growth in vivo via exosomes. CircSATB2 interacted with microRNA-330-5p (miR-330-5p) and miR-330-5p targeted pseudopodium enriched atypical kinase 1 (PEAK1). In addition, circSATB2 affected the PEAK1 level via sponging miR-330-5p in lung cancer cells. All results suggested that exosomal transfer of circSATB2 contributed to the malignant development of lung cancer by acting as a sponge of miR-330-5p to upregulate PEAK1.

The regulatory roles of circular RNAs via autophagy in ischemic stroke

Ischemic stroke (IS) is a severe disease with a high disability, recurrence, and mortality rates. Autophagy, a highly conserved process that degrades damaged or aging organelles and excess cellular components to maintain homeostasis, is activated during IS. It influences the blood–brain barrier integrity and regulates apoptosis. Circular RNAs (circRNAs) are novel non-coding RNAs involved in IS-induced autophagy and participate in various pathological processes following IS. In addition, they play a role in autophagy regulation. This review summarizes current evidence on the roles of autophagy and circRNA in IS and the potential mechanisms by which circRNAs regulate autophagy to influence IS injury. This review serves as a basis for the clinical application of circRNAs as novel biomarkers and therapeutic targets in the future.

Exosomes in the tumor microenvironment: Promoting cancer progression

Exosomes, which are extracellular vesicles produced by endosomes, are important performers of intercellular communication functions. For more than three decades, there has been a growing awareness of exosomes as the contents of the tumor microenvironment and their intimate connection to the development of cancer. The composition, generation, and uptake of exosomes as well as their roles in tumor metastasis, angiogenesis, and immunosuppression are discussed in this paper. In order to stop the progression of cancer, it is crucial to find new diagnostic biomarkers and therapeutic targets for the disease. Knowing the biological characteristics of exosomes and their functions in tumor development helps in this endeavor.

Exosomal circRNA Scm-like with four malignant brain tumor domains 2 (circ-SFMBT2) enhances the docetaxel resistance of prostate cancer via the microRNA-136-5p/tribbles homolog 1 pathway

Exosomal circular RNA was found to mediate cancer chemoresistance. However, whether exosomal circRNA Scm-like with four malignant brain tumor domains 2 (circ-SFMBT2) was involved in the chemoresistance of prostate cancer (PCa) remains unclear. The docetaxel (DTX) resistance of PCa cells was analyzed by Cell Counting Kit 8 assay. Quantitative real-time PCR was used to measure circSFMBT2, microRNA (miR)-136-5p and tribbles homolog 1 (TRIB1) expression. Cell proliferation, apoptosis, migration and invasion were analyzed by 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, wound-healing assay and transwell assay. RNA interaction was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Protein expression was measured by western blot analysis. Exosomes-extracted from cells were identified by transmission electron microscope, nanoparticles tracking analysis and western blot. Xenograft mice models were constructed to analyze the effect of exosomal circSFMBT2 on the DTX sensitivity of PCa tumors in vivo. CircSFMBT2 was upregulated in DTX-resistant PCa cells, and its knockdown enhanced the DTX sensitivity of DTX-resistant PCa cells by suppressing cell proliferation, migration, invasion and enhancing apoptosis. CircSFMBT2 severed as miR-136-5p sponge to positively regulate TRIB1. The regulation of circSFMBT2 knockdown on the DTX sensitivity of DTX-resistant PCa cells could be reversed by miR-136-5p inhibitor or TRIB1 overexpression. Exosomal circSFMBT2 from DTX-resistant PCa could increase the DTX resistance of normal PCa cells. In addition, exosomal circSFMBT2 also enhanced the DTX resistance of PCa tumors in vivo, and it was highly expressed in the serum of DTX-resistance PCa patients. Exosomal circSFMBT2 enhanced the DTX resistance of PCa by miR-136-5p/TRIB1 axis, indicating that circSFMBT2 might be a potential target for the treatment of PCa chemoresistance.

Small extracellular vesicles as a multicomponent biomarker platform in urinary tract carcinomas

Extracellular vesicles are a large group of nano-sized vesicles released by all cells. The variety of possible cargo (mRNAs, miRNAs, lncRNAs, proteins, and lipids) and the presence of surface proteins, signaling molecules, and receptor ligands make them a rich source of biomarkers for malignancy diagnosis. One of the groups gathering the most interest in cancer diagnostic applications is small extracellular vesicles (sEVs), with ≤200 nm diameter, mainly composed of exosomes. Many studies were conducted recently, evaluating the diagnostic potential of sEVs in urinary tract carcinomas (UTCs), discovering and clinically evaluating various classes of biomarkers. The amount of research concerning different types of UTCs understandably reflects their incidence. sEV cargos getting the most interest are non-coding RNAs (miRNA and lncRNA). However, implementation of other approaches such as metabolomic and proteomic analysis is also evaluated. The results of many studies indicate that sEVs have an essential role in the cancer process and possess many possible diagnostic and prognostic applications for UTC. The relative ease of obtaining biofluids rich in sEVs (urine and blood) confirms that sEVs are essential for UTC detection in the liquid biopsy approach. A noticeable rise in research quality is observed as more researchers are aware of the research standardization necessity, which is essential for considering the clinical application of their findings.

Circ_0000291 contributes to hepatocellular carcinoma tumorigenesis by binding to miR-1322 to up-regulate UBE2T

INTRODUCTION AND OBJECTIVES

Circular RNAs (circRNAs) are identified to show important regulatory functions in cancer biology. We attempted to analyze the role of circ_0000291 in hepatocellular carcinoma (HCC) progression and its related mechanism.

METHODS

The circular characteristic of circ_0000291 was tested using exonuclease RNase R. Cell proliferation was analyzed by 5-Ethynyl-2'-deoxyuridine (EdU) incorporation and colony formation assays. Cell apoptosis was measured by flow cytometry and a caspase 3 activity assay kit. Transwell assays were performed to analyze cell migration and invasion abilities. Sphere formation assay was conducted to analyze cell stemness. Dual-luciferase reporter and RNA-pull down assays were conducted to verify the interaction between microRNA-1322 (miR-1322) and circ_0000291 or ubiquitin conjugating enzyme E2 T (UBE2T).

RESULTS

Circ_0000291 was markedly up-regulated in HCC tissues and cell lines. HCC patients with high expression of circ_0000291 displayed a low survival rate. Circ_0000291 knockdown restrained the proliferation, migration, invasion, and stemness and induced the apoptosis of HCC cells. Circ_0000291 directly interacted with miR-1322 and negatively regulated miR-1322 expression. Circ_0000291 knockdown-mediated anti-tumor impacts in HCC cells were largely overturned by the interference of miR-1322. miR-1322 directly paired with the 3' untranslated region (3'UTR) of UBE2T, and UBE2T was negatively regulated by miR-1322. UBE2T overexpression largely reversed circ_0000291 silencing-induced effects in HCC cells. Circ_0000291 positively regulated UBE2T expression by absorbing miR-1322 in HCC cells. Circ_0000291 silencing notably reduced the tumorigenic potential in vivo.

CONCLUSION

Circ_0000291 facilitated HCC progression by targeting miR-1322/UBE2T axis, which provided novel potential biomarkers and targets for HCC patients.

Small Extracellular Vesicles of M1-BV2 Microglia Induce Neuronal PC12 Cells Apoptosis via the Competing Endogenous Mechanism of CircRNAs

Polarized microglia play a vital role in neurodegenerative diseases. However, the effects of polarized microglia-derived small extracellular vesicles (SEVs) on neuronal cells and the regulatory mechanisms of circular RNAs (circRNAs) in SEVs remain incompletely defined. In the present study, we carried out high-throughput sequencing and differential expression analysis of circRNAs in the SEVs of M0-phenotype BV2 microglia (M0-BV2) and polarized M1-phenotype BV2 microglia (M1-BV2). Hub circRNAs in the SEVs and their functions were screened using multiple bioinformatics methods. We further validated the effects of SEVs on neuronal PC12 cells by co-culturing M0-BV2 SEVs and M1-BV2 SEVs with neuronal PC12 cells. Among the differentially expressed circRNAs, the target mRNAs of six hub circRNAs (circ_0000705, circ_0001313, circ_0000229, circ_0001123, circ_0000621, and circ_0000735) were enriched in apoptosis-related biological processes. Furthermore, western blot and flow cytometry analysis demonstrated that M0-BV2 SEVs had no distinct effect on apoptosis of neuronal PC12 cells, while M1-BV2 SEVs remarkably increased the apoptosis of neuronal PC12 cells. We then constructed the competing endogenous RNA (ceRNA) networks of the six hub circRNAs. Taken together, the results suggest that polarized M1-BV2 microglia can induce apoptosis of neuronal PC12 cells through secreted SEVs, and this regulatory effect may be achieved by the circRNAs circ_0000705, circ_0001313, circ_0000229, circ_0001123, circ_0000621, and circ_0000735 through ceRNAs regulatory networks. These findings provide new potential targets for the treatment of neurodegenerative diseases.

Exosomes: Small Vesicles with Important Roles in the Development, Metastasis and Treatment of Breast Cancer

Breast cancer (BC) has now overtaken lung cancer as the most common cancer, while no biopredictive marker isolated from biological fluids has yet emerged clinically. After traditional chemotherapy, with the huge side effects brought by drugs, patients also suffer from the double affliction of drugs to the body while fighting cancer, and they often quickly develop drug resistance after the drug, leading to a poor prognosis. And the treatment of some breast cancer subtypes, such as triple negative breast cancer (TNBC), is even more difficult. Exosomes (Exos), which are naturally occurring extracellular vesicles (EVs) with nanoscale acellular structures ranging in diameter from 40 to 160 nm, can be isolated from various biological fluids and have been widely studied because they are derived from the cell membrane, have extremely small diameter, and are widely involved in various biological activities of the body. It can be used directly or modified to make derivatives or to make some analogs for the treatment of breast cancer. This review will focus on the involvement of exosomes in breast cancer initiation, progression, invasion as well as metastasis and the therapeutic role of exosomes in breast cancer.

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.

Integrated analysis of the functions and clinical implications of exosome circRNAs in colorectal cancer

Background

Exosome circRNAs (Exo-circRNAs) regulate cancer progression and intercellular crosstalk in the tumor microenvironment. However, their biological functions and potential clinical importance in colorectal cancer (CRC) remain unknown.

Methods

We used exoRBase 2.0 data to identify significant differentially expressed Exo-circRNAs (Exo-DEcircRNAs) in CRC patients and healthy individuals. The least absolute shrinkage and selector operation algorithm, support vector machine-recursive feature elimination, and multivariate Cox regression analyses were used to select candidate Exo-circRNAs and constructed a diagnostic model. Quantitative reverse transcription-polymerase chain reaction analysis was performed to confirm the expression of Exo-circRNAs in the serum samples of patients. Furthermore, we constructed an exosome circRNA-miRNA-mRNA network for CRC. Upregulated target mRNAs in the exosome competing endogenous RNA (Exo-ceRNA) network were used for functional and pathway enrichment analyses. We identified 22 immune cell types in CRC patients using CIBERSORT. Correlation analysis revealed the relationship between Exo-ceRNA networks and immune-infiltrating cells. The relationship between target mRNAs and immunotherapeutic response was also explored. Finally, using the Kaplan–Meier survival curve, a prognostic upregulated target mRNA was screened. We constructed a survival-related Exo-ceRNA subnetwork and explored the correlation between the Exo-ceRNA subnetwork and immune-infiltrating cells.

Results

The constructed diagnostic model had a high area under the curve (AUC) value in both the training and validation sets (AUC = 0.744 and AUC = 0.741, respectively). qRT-PCR confirmed that the Exo-circRNAs were differentially expressed in CRC serum samples. We constructed Exo-ceRNA networks based on the interactions among seven upregulated Exo-DEcircRNAs, eight differentially expressed miRNAs, and twenty-two differentially expressed mRNAs in CRC. Functional enrichment analysis revealed that the upregulated target mRNAs were significantly enriched in cytoskeletal motor activity and the PI3K-Akt signaling pathway. Co-expression analysis showed a significant correlation between the Exo-ceRNA networks and immune cells. The significant correlation was observed between target mRNAs and the immunotherapeutic response. Additionally, based on the prognostic upregulated target gene (RGS2), we constructed a survival-related Exo-ceRNA subnetwork (Exosome hsa_circ_0050334-hsa_miR_182_5p-RGS2). CIBERSORT results revealed that the Exo-ceRNA subnetwork correlated with M2 macrophages (P = 4.6e-07, R = 0.31).

Conclusions

Our study identified an Exo-diagnostic model, established Exo-ceRNA networks, and explored the correlation between Exo-ceRNA networks and immune cell infiltration in CRC. These findings elucidated the biological functions of Exo-circRNAs and their potential clinical implications.

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.

Plasma Exosomal hsa_circ_0015286 as a Potential Diagnostic and Prognostic Biomarker for Gastric Cancer

Circular RNA (circRNA) is stable and abundant in exosomes as a potential biomarker for the diagnosis and prognosis of tumor. In this study, cancer specific exosomal circRNAs were identified through circRNA microarray, and 58 circRNAs were significantly upregulated in cancer cells derived exosomes. Then 60 patients with newly diagnosed gastric cancer (GC), 30 chronic gastritis patients and 30 healthy subjects were enrolled for further clinical validation. We detected that hsa_circ_0015286 was remarkably highly expressed in GC tissue, plasma and cancer cells compared with normal controls. Results of ROC curve analysis showed that the area under curve (AUC) of hsa_circ_0015286, CEA and CA 19-9 was 0.778, 0.673, and 0.665, respectively. The combined detection of three indicators had the highest AUC (0.843). Exosomal hsa_circ_0015286 expression was closely associated with tumor size, TNM stage and lymph node metastasis. The expression level of exosomal hsa_circ_0015286 in GC patients decreased significantly after surgery. Overall survival of patients with low hsa_circ_0015286 expression was longer than those with high expression. Our data demonstrated that exosomal hsa_circ_0015286 might be a promising noninvasive biomarker for the diagnosis and prognosis evaluation of GC.

Exosomes in urological diseases - Biological functions and clinical applications

Exosomes are extracellular vesicles with a variety of biological functions that exist in various biological body fluids and exert their functions through proteins, nucleic acids, lipids, and metabolites. Recent discoveries have revealed the functional and biomarker roles of miRNAs in urological diseases, including benign diseases and malignancies. Exosomes have several uses in the diagnosis, treatment, and monitoring of urological diseases, especially cancer. Proteins and nucleic acids can be used as alternative biomarkers for detecting urological diseases. Additionally, exosomes can be detected in most body fluids, thereby avoiding pathogenesis. More importantly, for urological tumors, exosomes display a higher sensitivity than circulating tumor cells and tumor-derived DNA in body fluid biopsies because of their low immunogenicity and high stability. These advantages have made it a research hotspot in recent years. In this review, we focus on the biological characteristics and functions of exosomes and summarize their advantages and the latest progress in the diagnosis and treatment of urological diseases.

Circ_0044516 inhibits cell proliferation and migration and induces apoptosis in gastric cancer cells by targeting miR-516a-5p

BACKGROUND

Circ_0044516 is highly expressed in gastric cancer, and inhibition of circ_0044516 can promote gastric cancer cell proliferation and induce apoptosis. Bioinformatics analysis predicts that miR-516a-5p binds to circ_0044516. The expression of miR-516a-5p is low in non-small cell lung cancer, but its role is unclear in gastric cancer cells. This study mainly explored the effect of circ_0044516 targeting miR-516a-5p on the proliferation, migration, and apoptosis of gastric cancer cells.

AIM

To explore whether circ_0044516 targets and regulates miR-516a-5p and its effects on the proliferation, migration, and apoptosis of gastric cancer cells.

METHODS

Quantitative real time polymerase chain reaction (qRT-PCR) was first used to detect the expression levels of circ_0044516 and miR-516a-5p in gastric epithelial cells GES-1 and gastric cancer cells (SNU-16 and HGC-27). HGC-27 cells were then divided into si-NC group (transfected with si-NC), si-circ_0044516 group (transfected with si-circ_0044516), miR-NC group (transfected with miR-NC), miR-516a-5p group (transfected with miR-516a-5p), si-circ_0044516 + anti-miR-NC group (co-transfected with si-circ_0044516 and anti-miR-NC), and si-circ_0044516 + anti-miR-516a-5p group (co-transfected with si-circ_0044516 and anti-miR-516a-5p). qRT-PCR was used to detect the expression levels of circ_0044516 and miR-516a-5p, MTT assay was used to detect cell proliferation, flow cytometry was performed to detect cell apoptosis, Transwell assay was used to detect cell migration, Western blot analysis was performed to detect the protein expression of p21, Bcl-2 associated X protein (Bax), B cell lymphoma/lewkmia-2 (Bcl-2), and matrix metalloproteinase 2 (MMP2), and dual luciferase reporter assay was ued to detect the targeting relationship between circ_0044516 and miR-516a-5p.

RESULTS

Compared with gastric epithelial cells GES-1, the expression level of circ_0044516 was increased in gastric cancer cells SNU-16 and HGC-27, and the expression level of miR-516a-5p was decreased. Silencing circ_0044516 or overexpression of miR-516a-5p decreased the survival rate of gastric cancer cells and the number of migrating cells, increased the rate of cell apoptosis and the expression of p21 and Bax proteins, and reduced the expression of Bcl-2 and MMP2 proteins. Circ_0044516 targets and negatively regulates the expression of miR-516a-5p, and inhibition of miR-516a-5p partially restored the effect of silencing circ_0044516 on the proliferation, migration, and apoptosis of gastric cancer cells.

CONCLUSION

Circ_0044516 inhibits cell proliferation and migration and induces apoptosis in gastric cancer cells through targeted negative regulation of miR-516a-5p.

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.

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.

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.

Circ_0058063 contributes to cisplatin-resistance of bladder cancer cells by upregulating B2M through acting as RNA sponges for miR-335-5p

Bladder cancer (BC) is one of the most common malignant tumors of the urinary system, and cisplatin (CDDP) is a critical chemical drug for the treatment of BC. However, CDDP-resistance seriously limits the therapeutic efficacy of this drug for clinical utilization. Thus, identification of pivotal molecule targets that regulate CDDP-resistance in BC become urgent and necessary. In this study, we firstly identified a novel BC-associated circular RNA circ_0058063 that participates in the regulation of CDDP-resistance in BC. Specifically, circ_0058063 was significantly overexpressed in CDDP-resistant tissue and cells, in contrast with the corresponding CDDP-sensitive counterparts. Further loss-of-function experiments validated that downregulation of circ_0058063 suppressed cell proliferation and tumor growth, whereas induced cell apoptosis in the CDDP-resistant BC cells in vitro and in vivo. In addition, we disclosed that circ_0058063 acts as a sponge for miR-335-5p to positively regulate B2M expression, and further rescuing experiments verified that the enhancing effects of sh-circ_0058063 on CDDP-sensitivity in the CDDP-resistant BC cells were abrogated by silencing miR-335-5p. Taken together, our results demonstrated that circ_0058063 contributed to CDDP resistance of bladder cancer cells via sponging miR-335-5p, and B2M might be the downstream effector gene. This study firstly evidenced that targeting circ_0058063 might be an effective strategy to improve CDDP-sensitivity in BC.

Liquid biopsy: a step closer to transform diagnosis, prognosis and future of cancer treatments

Over the past decade, invasive techniques for diagnosing and monitoring cancers are slowly being replaced by non-invasive methods such as liquid biopsy. Liquid biopsies have drastically revolutionized the field of clinical oncology, offering ease in tumor sampling, continuous monitoring by repeated sampling, devising personalized therapeutic regimens, and screening for therapeutic resistance. Liquid biopsies consist of isolating tumor-derived entities like circulating tumor cells, circulating tumor DNA, tumor extracellular vesicles, etc., present in the body fluids of patients with cancer, followed by an analysis of genomic and proteomic data contained within them. Methods for isolation and analysis of liquid biopsies have rapidly evolved over the past few years as described in the review, thus providing greater details about tumor characteristics such as tumor progression, tumor staging, heterogeneity, gene mutations, and clonal evolution, etc. Liquid biopsies from cancer patients have opened up newer avenues in detection and continuous monitoring, treatment based on precision medicine, and screening of markers for therapeutic resistance. Though the technology of liquid biopsies is still evolving, its non-invasive nature promises to open new eras in clinical oncology. The purpose of this review is to provide an overview of the current methodologies involved in liquid biopsies and their application in isolating tumor markers for detection, prognosis, and monitoring cancer treatment outcomes.

Circ_0003340 downregulation mitigates esophageal squamous cell carcinoma progression by targeting miR-940/PRKAA1 axis

Background

Esophageal squamous cell carcinoma (ESCC) is a highly prevalent type of esophageal cancer (EC), usually found at an advanced stage with a high mortality rate, and it is now crucial to find new ways to diagnose and treat ESCC. This study analyzed the function of circular RNA_0003340 (circ_0003340)/microRNA‐940 (miR‐940)/protein kinase AMP‐activated alpha 1 catalytic subunit (PRKAA1) axis in ESCC.

Methods

Circ_0003340, miR‐940 and PRKAA1 contents were measured with the application of real‐time quantitative polymerase chain reaction (RT‐qPCR) and western blot. Cell proliferation, cell cycle, apoptosis, migration, invasion and angiogenesis were assessed with a cell counting kit‐8 (CCK8), 5‐ethynyl‐2′‐deoxyuridine (EdU), flow cytometry, wound healing, transwell and tube formation assays. We used both the luciferase reporter system and RNA immunoprecipitation (RIP) to analyze the relationship between miR‐940 and circ_0003340 or PRKAA1. Finally, xenograft models were applied to analyze the effect of circ_0003340 on tumor growth in vivo.

Results

Upregulated circ_0003340 and PRKAA1, and downregulated miR‐940 levels were detected in ESCC. Meanwhile, ESCC progression was apparently restrained by circ_0003340 knockdown in vitro. Circ_0003340 acted as a ceRNA for miR‐940 in regulating ESCC progression and miR‐940 was proved to target PRKAA1 to arrest ESCC progression in vitro. Finally, in vivo experiments established that silencing of circ_0003340 slowed tumor growth in vivo.

Conclusion

Circ_0003340 downregulation mitigated esophageal squamous cell carcinoma progression by targeting miR‐940/PRKAA1 axis.

Circular RNA midline-1 (circMID1) promotes proliferation, migration, invasion and glycolysis in prostate cancer

The key role of circular RNA (circRNA) in the malignant progression of cancers has been demonstrated. However, the role of circRNA midline-1 (circMID1) in prostate cancer (PCa) progression has not been clarified. Quantitative real-time PCR was used to measure relative expression. Function analysis was performed using EdU staining, colony formation assay, flow cytometry, wound healing assay, transwell assay and cell glycolysis detection. The protein levels were detected by Western blot analysis. RNA pull-down assay, dual-luciferase reporter assay and RIP assay were performed to verify RNA interaction. Animal experiments were utilized to explore the effects of circMID1 knockdown on PCa tumorigenesis in vivo. Our results showed that circMID1 was upregulated in PCa tissues and cells and its knockdown inhibited PCa cell proliferation, migration, invasion and glycolysis in vitro, as well as PCa tumorigenesis in vivo. IGF1R and YTHDC2 were highly expressed in PCa tissues and cells, and their expression was positively regulated by circMID1. IGF1R and YTHDC2 overexpression reversed the inhibitory effect of circMID1 silencing on PCa cell progression. In terms of mechanism, circMID1 could sponge miR-330-3p and miR-330-3p could target IGF1R and YTHDC2. Functional experiments showed that circMID1 sponged miR-330-3p to regulate PCa progression via the YTHDC2/IGF1R/AKT axis. In conclusion, our data confirmed that circMID1 might play a pro-cancer role in PCa, which promoted PCa progression through regulating the miR-330-3p/YTHDC2/IGF1R/AKT axis.

Hsa_circ_0041268 promotes NSCLC progress by sponging miR-214-5p/ROCK1

Circular RNAs hold significant regulatory functions during various tumors. However, the exact hsa_circ_0041268 roles in non-small cell lung cancer (NSCLC) along with regulatory mechanism are unknown. In this study, RT-qPCR was used to perceive hsa_circ_0041268 expressions in NSCLC cell lines. Our team constructed small interfering RNA for hsa_circ_0041268. NSCLC cell proliferation, migration, and tumorigenesis in nude mice were assayed to confirm hsa_circ_0041268 activities in NSCLC cells. We then used bioinformatics and luciferase reporter analyses to characterize the hsa_circ_0041268 downstream targets. The result shows that the expressions of hsa_circ_0041268 incremented in NSCLC cell lines and hsa_circ_0041268 downregulation decreased cell proliferation and migration. ROCK1 and miR-214-5p were hsa_circ_0041268 downstream targets. miR-214-5p downregulation or ROCK1 overexpression restored migration and proliferation abilities after hsa_circ_0041268 silencing. ROCK1 overexpression renovated migration and proliferation abilities after miR-214-5p overexpression. In vivo investigations confirmed that hsa_circ_0041268 downregulation inhibited tumor formation and metastasis in nude mice xenografts. Together, results demonstrated that hsa_circ_0041268 acted as tumor promoter through novel hsa_circ_0041268/miR-214-5p/ROCK1 axis, which highlighted its potential as NSCLC therapeutic agent.

Hsa_circ_0005230 is up-regulated and promotes gastric cancer cell invasion and migration via regulating the miR-1299/RHOT1 axis

Gastric cancer (GC) is one of the most common cancers in the world. Circular RNAs (circRNAs) are a class of non-coding RNAs that are widely expressed in eukaryotic cells. However, their role has been poorly understood in GC. This report aimed to explore the biological functions of hsa_circ_0005230 and its action mechanism in GC. This study validated that hsa_circ_0005230 was significantly up-regulated in 130 cases of GC tissues using qRT-PCR, and clinicopathological feature analysis revealed that its high expression was positively associated with histological grade, lymph node metastasis, TNM stages, and poor prognosis. In vitro, functional experiments showed that silencing hsa_circ_0005230 significantly decreased GC cell proliferation, invasion and migration capabilities. In addition, the major proteins of EMT (epithelial-mesenchymal transition) relevance have changed. In mechanism studies, bioinformatics analyses were used to predict the hsa_circ_0005230/miR-1299/RHOT1 axis and hsa_circ_0005230 may serve as a sponge for miR-1299 and indirectly regulate the expression of RHOT1. The regulated relationships between the molecules on the axis were verified using qRT-PCR and correlation analysis. Dual-luciferase reporter gene assay has been used to verify the binding site between miR-1299 and RHOT1. WB (Western blotting) and IHC (Immunohistochemical) were used to verify that RHOT1 may play the role of oncoprotein and affect the biological behavior of GC. Overall, hsa_circ_0005230 could enhance the EMT phenotype by promoting RHOT1 expression through sponging miR-1299, thus affecting the biological behavior of GC. Hsa_circ_0005230 can be easily identified as a potential diagnostic biomarker and assessment prognosis target for GC.

Using Graph Attention Network and Graph Convolutional Network to Explore Human CircRNA-Disease Associations Based on Multi-Source Data

Cumulative research studies have verified that multiple circRNAs are closely associated with the pathogenic mechanism and cellular level. Exploring human circRNA-disease relationships is significant to decipher pathogenic mechanisms and provide treatment plans. At present, several computational models are designed to infer potential relationships between diseases and circRNAs. However, the majority of existing approaches could not effectively utilize the multisource data and achieve poor performance in sparse networks. In this study, we develop an advanced method, GATGCN, using graph attention network (GAT) and graph convolutional network (GCN) to detect potential circRNA-disease relationships. First, several sources of biomedical information are fused via the centered kernel alignment model (CKA), which calculates the corresponding weight of different kernels. Second, we adopt the graph attention network to learn latent representation of diseases and circRNAs. Third, the graph convolutional network is deployed to effectively extract features of associations by aggregating feature vectors of neighbors. Meanwhile, GATGCN achieves the prominent AUC of 0.951 under leave-one-out cross-validation and AUC of 0.932 under 5-fold cross-validation. Furthermore, case studies on lung cancer, diabetes retinopathy, and prostate cancer verify the reliability of GATGCN for detecting latent circRNA-disease pairs.

Circular RNA 0000654 facilitates the growth of gastric cancer cells through absorbing microRNA-149-5p to up-regulate inhibin-beta A

Circular (circ) RNAs are differentially expressed in gastric cancer (GC) and participate in the biological growth of tumor cells. Given that, investigations were performed to unravel the function of circ_0000654 in GC. GC tissue and normal tissue specimens were obtained, in which circ_0000654, microRNA (miR)-149-5p, and inhibin-beta A (INHBA) levels were examined. GC cell line (BGC-823) was transfected to alter circ_0000654 and miR-149-5p expression, thereby observing cell malignancy. Stably-transfected BGC-823 cells were injected into nude mice to observe tumor growth in vivo. The interaction circ_0000654, miR-149-5p, and INHBA was validated. circ_0000654 and INHBA were up-regulated but miR-149-5p was down-regulated in GC. circ_0000654 absorbed miR-149-5p to target INHBA. Silencing circ_0000654inhibited the progress of GC cell biology. Oppositely, restoring circ_0000654 enhanced the growth of GC cells. Inhibiting miR-149-5p rescued down-regulated circ_0000654-induced anti-tumor effect on GC. circ_0000654 silence or miR-149-5p overexpression limited the growth of GC tumors in vivo. Obviously, circ_0000654 facilitates the growth of GC cells through absorbing miR-149-5p to up-regulate INHBA.

The transcriptional landscape and biomarker potential of circular RNAs in prostate cancer

Background

Circular RNAs (circRNAs) constitute a largely unexplored source for biomarker discovery in prostate cancer (PC). Here, we characterize the biomarker potential of circRNAs in PC, where the need for novel diagnostic and prognostic tools to facilitate more personalized management is pressing.

Methods

We profiled the transcriptomic landscape of circRNAs in PC by total RNA sequencing of 31 adjacent-normal and 143 tumor samples from localized (radical prostatectomy (RP)) and metastatic PC patients (cohort 1, training). Diagnostic and prognostic potential was evaluated in cohort 1, and 39 top circRNA candidates were selected for validation in two additional PC cohorts (cohort 2, n = 111; RP cohort 3, n = 191) by NanoString-based expression analysis. Biochemical recurrence (BCR)-free survival was assessed using Kaplan-Meier, univariate, and multivariate Cox regression analyses. The circRNA candidates were further detected in extracellular vesicle (EV)-enriched plasma samples from PC patients and controls (cohort 4, n = 54).

Results

Expression of circABCC4, circFAT3, circATRNL1, and circITGA7 was highly cancer-specific (area under the curve 0.71–0.86), while low circITGA7 expression was significantly (P < 0.05) associated with BCR in univariate analysis in two RP cohorts. Moreover, we successfully trained and validated a novel 5-circRNA prognostic signature (circKMD1A/circTULP4/circZNF532/circSUMF1/circMKLN1) significantly associated with BCR beyond routine clinicopathological variables (RP cohort 1: P = 0.02, hazard ratio = 2.1; RP cohort 3: P < 0.001, hazard ratio = 2.1). Lastly, we provide proof-of-principle for detection of candidate circRNAs in EV-enriched plasma samples from PC patients.

Conclusions

circRNAs hold great biomarker potential in PC and display both high cancer specificity and association to disease progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-021-01009-3.

Circular RNA hsa_circ_0006091 as a novel biomarker for hepatocellular carcinoma

Circular RNAs (circRNAs) are stable and extensively distributed non-coding RNA molecules that are differentially expressed in liver cancer tissues in the human body. In this study, we aimed to investigate circRNA as a novel candidate biomarker for hepatocellular carcinoma (HCC). For three groups of HCC and neighboring healthy tissues, the differentially expressed circRNAs were identified through high-throughput sequencing analysis. Reverse transcription PCR (RT-PCR) and quantitative polymerase chain reaction (qPCR) were employed for the evaluation of circRNAs that show an elevated expression level in HCC. The obtained results revealed the significantly differential expression of hsa_circ_0006091 in HCC. Then we obtained their target genes through biological analysis, followed by verifying the underlined target genes, and the regulator of G-protein signaling 12 (RGS12) showed an elevated expression level in HCC tissues. Finally, receiver operating characteristic (ROC) curve analysis was conducted on AFP, RGS12, and hsa_circ_0006091, and combined analysis was performed. Furthermore, hsa_circ_0006091 is a novel candidate biomarker for HCC and could improve the diagnostic strategies, prediction, and follow-up of HCC patients. The joint diagnosis of the hsa_circ_0006091&AFP and hsa_circ_0006091&RGS12 has diagnostic significance and can be used as a molecular marker for HCC diagnosis.

Abbreviations: AUC:area under the ROC curve; ROC:Receptor Operating Characteristics; bp:base pair;mRNA:Messenger Ribonucleic acid;ceRNA:Competing endogenous RNA; RT-qPCR: Real time-quantitativen PCR technology; circRNA: circular RNA; HCC:Hepatocellular carcinoma;miRNA:microRNA;KEGG:Kyoto Encyclopedia of Genes and Genomes; RGS12:regulator of G-protein signaling 12; AFP:alpha fetoprotein; ncRNAs:non-coding RNAs; GEO:Gene Expression Omnibus; FDR:false discovery rate

Circ_0044516 Enriches the Level of SARM1 as a miR-330-5p Sponge to Regulate Cell Malignant Behaviors and Tumorigenesis of Prostate Cancer

Prostate cancer (PCa) is one of the most common and deadly cancers in men. The dysregulated circular RNAs (circRNAs) are involved in the development of various cancers, including PCa. The purpose of this study was to construct a circRNA-microRNA (miRNA)-mRNA network to explain the function of circ_0044516 in PCa. The expression analysis of circ_0044516, miR-330-5p, and sterile alpha and TIR motif-containing 1 (SARM1) was performed using real-time quantitative polymerase chain reaction, and the protein level of SARM1 was detected by western blot. The interaction between miR-330-5p and circ_0044516 or SARM1 obtained by bioinformatics prediction was verified by dual-luciferase reporter assay or RNA immunoprecipitation assay. For functional studies, cell proliferation was assessed by cell viability and colony formation ability using cell counting kit-8 assay and colony formation assay. Cell migration and invasion were studied using transwell assay. Cell apoptosis and cell cycle were investigated using flow cytometry assay. The tumorigenicity of circ_0044516 was tested by animal study. Circ_0044516 and SARM1 were highly expressed, while miR-330-5p was rarely expressed in PCa tissues and cells. Circ_0044516 acted as a miR-330-5p sponge to block miR-330-5p expression, and circ_0044516 knockdown suppressed PCa cell proliferation, migration, invasion, and cycle progression by enriching miR-330-5p. SARM1 was a target of miR-330-5p, and miR-330-5p restoration also inhibited PCa cell proliferation, migration, invasion, and cycle progression by degrading SARM1. Moreover, circ_0044516 deficiency blocked tumor growth in vivo by regulating the miR-330-5p/SARM1 axis. Circ_0044516 as a miR-330-5p sponge increases SARM1 expression, thus promoting the malignant development of PCa.

CircFBXW8 Acts an Oncogenic Role in the Malignant Progression of Non-small Cell Lung Carcinoma by miR-370-3p-Dependent Regulation of TRIM44

Non-small cell lung carcinoma (NSCLC) is an aggressive malignant tumor. Growing evidences have revealed that circular RNA (circRNA) is involved in NSCLC progression. This study aims to investigate the role of circular RNA F-box and WD repeat domain containing 8 (circFBXW8) in NSCLC progression and the underlying mechanism. The expression of circFBXW8, microRNA-370-3p (miR-370-3p) and tripartite motif containing 44 (TRIM44) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression was detected by western blot analysis or immunohistochemistry assay. Additionally, cell viability, colony-forming ability, proliferation and apoptosis were investigated by 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide, cell colony formation, 5-Ethynyl-29-deoxyuridine and flow cytometry analysis assays, respectively. Cell migratory and invasive abilities were examined by wound-healing and transwell assays. The regulatory relationship between miR-370-3p and circFBXW8 or TRIM44 was identified by dual-luciferase reporter and RNA pull-down assays. Furthermore, xenograft experiment was employed to explain the effect of circFBXW8 silencing on tumor formation. CircFBXW8 and TRIM44 expression were upregulated, while miR-370-3p was downregulated in NSCLC tissues, cells and the exosomes from NSCLC cells compared with respective controls. CircFBXW8 depletion repressed NSCLC cell proliferation, migration and invasion, but promoted cell apoptosis. CircFBXW8 acted as a sponge of miR-370-3p and regulated NSCLC cell malignancy by binding to miR-370-3p. Additionally, miR-370-3p repressed NSCLC cell processes by regulating TRIM44. CircFBXW8 knockdown inhibited tumor formation in vivo. Further, circFBXW8 secretion was mediated by exosomes. CircFBXW8 modulated NSCLC progression by increasing TRIM44 expression through sponging miR-370-3p, which provided a new direction for studying the therapy of NSCLC.