Targeting the radiation-induced TR4 nuclear receptor-mediated QKI/circZEB1/miR-141-3p/ZEB1 signaling increases prostate cancer radiosensitivity

A RBM47 and IGF2BP1 mediated circular FNDC3B-FNDC3B mRNA imbalance is involved in the malignant processes of osteosarcoma

BACKGROUND

Circular RNAs (circRNAs) are a class of noncoding RNAs that are involved in the progression of many human cancers. The precise gene locus and the roles of circular RNA from Fibronectin type III domain containing 3B (FNDC3B) in OS and its mechanisms of action have not been fully explored.

MATERIALS AND METHODS

qRT-qPCR assay was used to determine gene expressions. CCK8 Assay, EdU assay, wound-healing assay, transwell invasion assay and in vivo xenograft assay were used to perform functional investigations. RNA-FISH, immunofluorescence, RIP assay, RNA stability analysis were applied in mechanistic studies.

RESULTS

We found that circFNDC3B downregulated and FNDC3B mRNA upregulated in OS, and might be potential biomarkers for indicating disease progression and prognosis of OS patients. CircFNDC3B acted as a tumor suppressor gene to restrain OS progression and FNDC3B functioned as an oncogene to promote OS progression in vitro and in vivo. RNA binding protein RNA binding motif protein 47 (RBM47) could bind to the flanking introns of circFNDC3B to facilitate the generation of circFNDC3B, resulting in the reduction of FNDC3B mRNA and the circFNDC3B-FNDC3B mRNA imbalance. CircFNDC3B also inhibited FNDC3B mRNA expression by reducing its stability via competitively binding to Insulin-like growth-factor-2 mRNA binding protein (IGF2BP1).

CONCLUSION

This study demonstrated that RBM47 and IGF2BP1 mediated circular FNDC3B/FNDC3B mRNA imbalance was involved in the malignant processes of OS.

Interactions between circRNAs and miR-141 in Cancer: From Pathogenesis to Diagnosis and Therapy

The function of non-coding RNAs (ncRNAs) in the pathogenesis and development of cancer is indisputable. Molecular mechanisms underlying carcinogenesis involve the aberrant expression of ncRNAs, including circular RNAs (circRNAs), and microRNAs (miRNAs). CircRNAs are a class of single-stranded, covalently closed RNAs responsible for maintaining cellular homeostasis through their diverse functions. As a part of the competing endogenous RNA (ceRNAs) network, they play a central role in the regulation of accessibility of miRNAs to their mRNA targets. The interplay between these molecular players is based on the primary role of circRNAs that act as miRNAs sponges, and the circRNA/miRNA imbalance plays a central role in different pathologies including cancer. Herein, we present the latest state of knowledge about interactions between circRNAs and miR-141, a well-known member of the miR-200 family, in malignant transformation, with emphasis on the biological role of circRNA/miR-141/mRNA networks as a future target for novel anti-cancer therapies.

Circular RNA EPHA3 suppresses progression and metastasis in prostate cancer through the miR-513a-3p/BMP2 axis

BACKGROUND

Circular RNAs (circRNAs) may regulate the onset and progression of human malignancies by competitively binding to microRNA (miRNA) sponges, thus regulating the downstream genes. However, aberrant circRNA expression patterns and their biological functions in prostate cancer (PCa) warrant further studies. Our research sought to shed further light on the possible role and molecular mechanism of circEPHA3 action in controlling the growth and metastasis of PCa cells.

MATERIALS AND METHODS

circEPHA3 (has_circ_0066596) was initially screened from a previous circRNA microarray and identified following Actinomycin D and RNase R assays. Fluorescence in situ hybridization, biotin-coupled probe RNA pulldown, and dual-luciferase reporter gene assays were performed to examine the relationship between circEPHA3 and miR-513a-3p. The biological role of circEPHA3 in PCa was assessed by CCK8, wound healing, Transwell assays, and animal experiments.

RESULTS

We identified a novel circular RNA, circEPHA3 (has_circ_0066596), which was down-regulated in high-grade PCa tissues and cell lines. The outcomes of CCK8, wound healing, Transwell assays, and animal experiments revealed that circEPHA3 prohibited the progression and metastasis of PCa in vivo and in vitro. Mechanistically, circEPHA3 was directly bound to miR-513a-3p and regulated the downstream gene, BMP2, thereby serving as a tumor suppressor in PCa.

CONCLUSIONS

As a tumor suppressor, circEPHA3 inhibited the proliferation and metastasis of PCa cells through the miR-513a-3p/BMP2 axis, suggesting that circEPHA3 might be a potential therapeutic target for PCa.

Understanding the roles and regulation patterns of circRNA on its host gene in tumorigenesis and tumor progression

Circular RNAs (circRNAs) are a novel type of endogenous non-coding RNAs, which are covalently closed loop structures formed by precursor mRNAs (pre-mRNAs) through back-splicing. CircRNAs are abnormally expressed in many tumors, and play critical roles in a variety of tumors as oncogenes or tumor suppressor genes by sponging miRNAs, regulating alternative splicing and transcription, cis-regulating host genes, interacting with RNA binding proteins (RBPs) or encoding polypeptides. Among them, the regulation of circRNAs on their corresponding host genes is a critical way for circRNAs to exit their functions. Accumulating evidence suggests that circRNAs are able to regulate the expression of host genes at the transcriptional level, post-transcriptional level, translational level, post-translational level, or by encoding polypeptides. Therefore, this paper mainly summarized the roles and association of circRNAs and their corresponding host genes in tumorigenesis and tumor progression, generalized the circRNAs that function synergistically or antagonistically with their host genes, and elaborated the mechanisms of mutual regulation between circRNAs and their host genes. More importantly, this review provides specific references for revealing the potential application of circRNAs combined with their host genes in tumor diagnosis, treatment and prognosis.

Circular RNA circGlis3 protects against islet β-cell dysfunction and apoptosis in obesity

Pancreatic β-cell compensation is a major mechanism in delaying T2DM progression. Here we report the abnormal high expression of circGlis3 in islets of male mice with obesity and serum of people with obesity. Increasing circGlis3 is regulated by Quaking (QKI)-mediated splicing circularization. circGlis3 overexpression enhances insulin secretion and inhibits obesity-induced apoptosis in vitro and in vivo. Mechanistically, circGlis3 promotes insulin secretion by up-regulating NeuroD1 and Creb1 via sponging miR-124-3p and decreases apoptosis via interacting with the pro-apoptotic factor SCOTIN. The RNA binding protein FUS recruits circGlis3 and collectively assemble abnormal stable cytoplasmic stress granules (SG) in response to cellular stress. These findings highlight a physiological role for circRNAs in β-cell compensation and indicate that modulation of circGlis3 expression may represent a potential strategy to prevent β-cell dysfunction and apoptosis after obesity.

Hypoxia-induced circADAMTS6 in a TDP43-dependent manner accelerates glioblastoma progression via ANXA2/ NF-κB pathway

Circular RNAs (circRNAs) play important roles in the malignant progression of tumours. Herein, we identified an unreported circRNA (hsa-circ-0072688, also named circADAMTS6) that is specifically upregulated in the hypoxic microenvironment of glioblastoma and closely correlated with poor prognosis of gliblastoma patients. We found that circADAMTS6 promotes the malignant progression of glioblastoma by promoting cell proliferation and inhibiting apoptosis. Mechanistically, the hypoxic tumour microenvironment upregulates circADAMTS6 expression through transcription factor activator protein 1 (AP-1) and RNA-binding protein TAR DNA-binding protein 43 (TDP43). Moreover, circADAMTS6 accelerates glioblastoma progression by recruiting and stabilising annexin A2 (ANXA2) in a proteasomes-dependent manner. Furthermore, we found T-5224 (AP-1 inhibitor) treatment induces downregulation of circADAMTS6 and then inhibits tumour growth. In conclusion, our findings highlight the important role of the circADAMTS6/ANXA2 axis based on hypoxic microenvironment in glioblastoma progression, as well as its regulation in NF-κB pathway. Targeting circADAMTS6 is thus expected to become a novel therapeutic strategy for glioblastoma.

Targeting the radiation-induced ARv7-mediated circNHS/miR-512-5p/XRCC5 signaling with Quercetin increases prostate cancer radiosensitivity

Background

Radiation therapy (RT) with androgen deprivation therapy (ADT) is an effective therapy to suppress the locally advanced prostate cancer (PCa). However, we unexpectedly found that RT could also induce the androgen receptor splice variant 7 (ARv7) expression to decrease the radiosensitivity.

Methods

The study was designed to target ARv7 expression with Quercetin or ARv7-shRNA that leads to enhancing and increasing the radiation sensitivity to better suppress the PCa that involved the modulation of the circNHS/miR-512-5p/XRCC5 signaling.

Results

Mechanism studies revealed that RT-induced ARv7 may function via altering the circNHS/miR-512-5p/XRCC5 signaling to decrease the radiosensitivity. Results from preclinical studies using multiple in vitro cell lines and in vivo mouse models concluded that combining RT with the small molecule of Quercetin to target full-length AR and ARv7 could lead to better efficacy to suppress PCa progression.

Conclusion

Together, these results suggest that ARv7 may play key roles to alter the PCa radiosensitivity, and targeting this newly identified ARv7 mediated circNHS/miR-512-5p/XRCC5 signaling with Quercetin may help physicians to develop a novel RT to better suppress the progression of PCa.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02287-4.

Mechanism and Function of Circular RNA in Regulating Solid Tumor Radiosensitivity

Radiotherapy is an important tool in the treatment of malignant tumors, and exploring how to make radiotherapy more effective is a new way to break through the current bottleneck in the development of radiation oncology. Circular RNAs (circRNAs) are a special class of endogenous non-coding RNAs. Numerous studies have shown that circRNAs have shown great potential in regulating the biological functions of tumors, including proliferation, migration, invasion, and treatment resistance, and that differences in their expression levels are closely related to the clinical prognosis of tumor patients. This review systematically compares the mechanisms of circRNAs in the process of tumor development and radiosensitivity and provides insight into the clinical translation of circRNAs in radiotherapy.

The role of MicroRNA networks in tissue-specific direct and indirect effects of metformin and its application

Metformin is a first-line oral antidiabetic agent that results in clear benefits in relation to glucose metabolism and diabetes-related complications. The specific regulatory details and mechanisms underlying these benefits are still unclear and require further investigation. There is recent mounting evidence that metformin has pleiotropic effects on the target tissue development in metabolic organs, including adipose tissue, the gastrointestinal tract and the liver. The mechanism of actions of metformin are divided into direct effects on target tissues and indirect effects via non-targeted tissues. MicroRNAs (miRNAs) are a class of endogenous, noncoding, negative gene regulators that have emerged as important regulators of a number of diseases, including type 2 diabetes mellitus (T2DM). Metformin is involved in many aspects of miRNA regulation, and metformin treatment in T2DM should be associated with other miRNA targets. A large number of miRNAs regulation by metformin in target tissues with either direct or indirect effects has gradually been revealed in the context of numerous diseases and has gradually received increasing attention. This paper thoroughly reviews the current knowledge about the role of miRNA networks in the tissue-specific direct and indirect effects of metformin. Furthermore, this knowledge provides a novel theoretical basis and suggests therapeutic targets for the clinical treatment of metformin and miRNA regulators in the prevention and treatment of cancer, cardiovascular disorders, diabetes and its complications.

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.

Functional mechanism and clinical implications of miR-141 in human cancers

Cancer is caused by the abnormal proliferation of local tissue cells under the control of many oncogenic factors. MicroRNAs (miRNAs) are a class of evolutionarily conserved, approximately 22-nucleotide noncoding small RNAs that influence transcriptional regulationby binding to the 3'-untranslated region of target messenger RNA. As a member of the miRNA family, miR-141 acts as a suppressor or an oncomiR in various cancers and regulates cancer cell proliferation, apoptosis, invasion, and metastasis through a variety of signaling pathways, such as phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) and constitutive activation of nuclear factor-κB (NF-κB). Target gene validation and pathway analysis have provided mechanistic insight into the role of this miRNA in different tissues. This review also outlines novel findings that suggest miR-141 may be useful as a noninvasive biomarker and as a therapeutic target in several cancers.

CircRNAs in Malignant Tumor Radiation: The New Frontier as Radiotherapy Biomarkers

World Health Organization (WHO) data show that of the top 20 factors that threaten human life and health, cancer is at the forefront, and the therapeutic approaches for cancer consist of surgery, radiotherapy, chemotherapy and immunotherapy. For most highly metastatic and recurrent cancer, radiation therapy is an essential modality to mitigate tumor burden and improve patient survival. Despite the great accomplishments that have been made in clinical therapy, an inevitable challenge in effective treatment is radioresistance, the mechanisms of which have not yet been completely elucidated. In addition, radiosensitization methods based on molecular mechanisms and targets, and clinical applications are still inadequate. Evidence indicates that circular RNAs (circRNAs) are important components in altering tumor progression, and in influencing resistance and susceptibility to radiotherapy. This review summarizes the reasons for tumor radiotherapy resistance induced by circRNAs, and clarifies the molecular mechanisms and targets of action. Moreover, we determine the potential value of circRNAs as clinical indicators in radiotherapy, providing a theoretical basis for circRNAs-based strategies for cancer radiotherapy.

RNA-binding proteins and cancer metastasis

RNA-binding proteins (RBPs) can regulate gene expression through post-transcriptionally influencing all manner of RNA biology, including alternative splicing (AS), polyadenylation, stability, and translation of mRNAs, as well as microRNAs (miRNAs) and circular RNAs (circRNAs) processing. There is accumulating evidence reinforcing the perception that dysregulation or dysfunction of RBPs can lead to various human diseases, including cancers. RBPs influence diverse cancer-associated cellular phenotypes, such as proliferation, apoptosis, senescence, migration, invasion, and angiogenesis, contributing to the initiation and development of tumors, as well as clinical prognosis. Metastasis is the leading cause of cancer-related recurrence and death. Therefore, it is necessary to elucidate the molecular mechanisms behind tumor metastasis. In fact, a growing body of published research has proved that RBPs play pivotal roles in cancer metastasis. In this review, we will summarize the recent advances for helping us understand the role of RBPs in tumor metastasis, and discuss dysfunctions and dysregulations of RBPs affecting metastasis-associated processes including epithelial-mesenchymal transition (EMT), migration, and invasion of cancer cells. Furthermore, we will discuss emerging RBP-based strategy for the treatment of cancer metastasis.

Metastatic EMT Phenotype Is Governed by MicroRNA-200-Mediated Competing Endogenous RNA Networks

Epithelial–mesenchymal transition (EMT) is a fundamental physiologically relevant process that occurs during morphogenesis and organ development. In a pathological setting, the transition from epithelial toward mesenchymal cell phenotype is hijacked by cancer cells, allowing uncontrolled metastatic dissemination. The competing endogenous RNA (ceRNA) hypothesis proposes a competitive environment resembling a large-scale regulatory network of gene expression circuits where alterations in the expression of both protein-coding and non-coding genes can make relevant contributions to EMT progression in cancer. The complex regulatory diversity is exerted through an array of diverse epigenetic factors, reaching beyond the transcriptional control that was previously thought to single-handedly govern metastatic dissemination. The present review aims to unravel the competitive relationships between naturally occurring ceRNA transcripts for the shared pool of the miRNA-200 family, which play a pivotal role in EMT related to cancer dissemination. Upon acquiring more knowledge and clinical evidence on non-genetic factors affecting neoplasia, modulation of the expression levels of diverse ceRNAs may allow for the development of novel prognostic/diagnostic markers and reveal potential targets for the disruption of cancer-related EMT.

miR-616-5p Promotes Invasion and Migration of Bladder Cancer via Downregulating NR2C2 Expression

Background

MicroRNAs, small non-coding RNA molecules with about 22 nucleotides in length, play a significant role in the development of bladder cancer. Previous studies found that miR-616-5p could promote the progress of cancers. However, its role in bladder cancer remains unclear. In the study, we aimed to demonstrate how miR-616-5p impacts the invasion and migration of bladder cancer and its potential downstream targets.

Methods

Firstly, qRT-PCR was used to detect the expression of miR-616-5p in normal bladder uroepithelial cell lines and bladder cancer cell lines. Then, chamber–transwell invasion and wound healing migration assays were used to detect the roles of miR-616-5p and NR2C2 in invasion and migration. Subsequently, Western blot was used to evaluate the regulation effects of miR-616-5p and NR2C2. Finally, luciferase assays were performed to manifest the mechanism of miR-616-5p and NR2C2 regulation.

Results

We found that miR-616-5p was upregulated in bladder cancer, and it could promote the invasion and migration of bladder cancer in vitro. Moreover, we demonstrated that NR2C2 was a downstream target of miR-616-5p. miR-616-5p could inhibit the expression of NR2C2 by binding to the 3′UTR of NR2C2 mRNA. Importantly, patients with a high expression of NR2C2 showed better prognoses in bladder cancer.

Conclusions

This study identifies that miR-616-5p can promote bladder cancer progression via altering the expression of NR2C2. Therefore, identifying miR-616-5p expression levels might be a useful strategy for developing potential therapeutic targets in bladder cancer.

Role of ZEB family members in proliferation, metastasis and chemoresistance of prostate cancer cells: Revealing signaling networks

Prostate cancer (PCa) is one of the leading causes of death worldwide. A variety of strategies including surgery, chemotherapy, radiotherapy and immunotherapy are applied for PCa treatment. PCa cells are responsive towards therapy at early stages, but they can obtain resistance in the advanced stage. Furthermore, their migratory ability is high in advanced stages. It seems that genetic and epigenetic factors play an important in this case. Zinc finger E-box-binding homeobox (ZEB) is a family of transcription with two key members including ZEB1 and ZEB2. ZEB family members are known due to their involvement in promoting cancer metastasis via EMT induction. Recent studies have shown their role in cancer proliferation and inducing therapy resistance. In the current review, we focus on revealing role of ZEB1 and ZEB2 in PCa. ZEB family members that are able to significantly promote proliferation and viability of cancer cells. ZEB1 and ZEB2 enhance migration and invasion of PCa cells via EMT induction. Overexpression of ZEB1 and ZEB2 is associated with poor prognosis of PCa. ZEB1 and ZEB2 upregulation occurs during PCa progression and can provide therapy resistance to cancer cells. PRMT1, Smad2, and non-coding RNAs can function as upstream mediators of the ZEB family. Besides, Bax, Bcl-2, MRP1, N-cadherin and E-cadherin can be considered as downstream targets of ZEB family in PCa.