Biological role and regulation of circular RNA as an emerging biomarker and potential therapeutic target for cancer

Circular RNAs in gynecological cancer: From molecular mechanisms to clinical applications (Review)

Circular RNAs (circRNAs) have emerged as promising biomarkers and therapeutic targets in gynecological cancer. The present review explored developments in circRNA research in ovarian, endometrial and cervical cancer. circRNA biogenesis, functions and roles in cancer pathogenesis have been discussed, focusing on their potential as diagnostic and prognostic markers. Furthermore, circRNAs mechanisms of action, including miRNA sponging, protein scaffolding and peptide encoding were examined, highlighting specific circRNAs implicated in each cancer type and their clinical significance. The unique properties of circRNAs, such as stability and tissue-specific expression, make them ideal candidates for biomarker development. By synthesizing the currently available literature and identifying future research directions, the present review underscored circRNAs potential to improve gynecological cancer management through novel diagnostic tools, prognostic markers and targeted therapies.

CircSLC22A3 inhibits the invasion and metastasis of ESCC via the miR-19b-3p/TRAK2 axis and by reducing the stability of m6A-modified ACSBG1 mRNA

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a major contributor to cancer-related deaths, driven by its invasive and metastatic nature. Circular RNAs (circRNAs) are increasingly recognized as regulators of cancer progression, primarily through miRNA sponging and interactions with RNA-binding proteins. Their dysregulation has been linked to the development of in various cancers. The present study aimed to investigate the potential involvement of circSLC22A3 in the pathogenesis of ESCC.

METHODS

CircSLC22A3 expression in ESCC tissues and cells was analyzed using transcriptome sequencing and RT-qPCR. Its circular structure was validated through Sanger sequencing, agarose gel electrophoresis, RNase R digestion, and random priming assays. Subcellular localization was determined by nucleoplasmic separation and fluorescence in situ hybridization (FISH). Clinical correlations were assessed via tissue microarrays. Functional roles of circSLC22A3 in ESCC progression were investigated through in vitro and in vivo assays. Downstream miR-19b-3p and target gene TRAK2 were screened by bioinformatics analysis and RT-qPCR, with binding confirmed via luciferase reporter assays. RNA pulldown combined with RNA immunoprecipitation (RIP) identified IGF2BP1 as a circSLC22A3-interacting protein. RNA-seq and RT-qPCR revealed ACSBG1 as a key downstream effector. IGF2BP1-mediated m6A modification of ACSBG1 was mapped by MeRIP-seq and RIP, with mRNA stability assessed via Actinomycin D assay. ACSBG1 expression and biological function in ESCC were confirmed by immunohistochemistry, RT-qPCR, and functional assays.

RESULTS

Significant downregulation of circSLC22A3 was observed in both ESCC tissues and cell lines. Overexpression of circSLC22A3 significantly reduced ESCC cells' migration and invasion capabilities. Mechanistic investigation revealed that circSLC22A3 played a pivotal role in the invasion and metastasis of esophageal cancer through distinct pathways. On one hand, circSLC22A3 functioned as a miR-19b-3p sponge to augment trafficking kinesin protein 2 (TRAK2) expression, while, on the other hand, circSLC22A3 formed a protein-RNA complex with IGF2BP1, resulting in the degradation of acyl-CoA synthetase bubblegum family member 1 (ACSBG1) mRNA through the recognition of m6A modification, thereby suppressing invasion and metastasis of ESCC.

CONCLUSIONS

The present study identified circSLC22A3 as a new tumor suppressor that inhibited ESCC progression through both the circSLC22A3/ miR-19b-3p/ TRAK2 and circSLC22A3/ IGF2BP1/ ACSBG1 axes.

Preliminary Evaluation of Plasma circ_0009910, circ_0027478, and miR-1236-3p as Diagnostic and Prognostic Biomarkers in Hepatocellular Carcinoma

Circular RNAs (circRNAs) are increasingly recognized as significant regulators in multiple cancers, such as hepatocellular carcinoma (HCC), frequently affecting microRNA (miRNA) expression. The diagnostic and prognostic roles of circRNAs, specifically circ_0009910 and circ_0027478, in conjunction with miR-1236-3p, in HCC, have not yet been fully investigated. In this pilot study, we assessed the expression levels of circ_0009910, circ_0027478, and miR-1236-3p in plasma samples from 100 patients diagnosed with HCC and 50 healthy controls through reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). The diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis, and correlations with clinicopathological features were examined. Circ_0009910 and circ_0027478 exhibited significant upregulation in patients with HCC (p < 0.05), whereas miR-1236-3p demonstrated downregulation (p < 0.05). Circ_0009910 demonstrated significant diagnostic accuracy (area under the curve [AUC] = 0.90), effectively differentiating HCC from controls and showing a correlation with tumor size, metastasis, and alpha-fetoprotein (AFP) levels (p < 0.05). Both circ_0009910 and circ_0027478 exhibited a positive correlation with clinicopathological features, whereas miR-1236-3p demonstrated an inverse correlation. Logistic regression validated the diagnostic and prognostic capabilities of these biomarkers. The results indicate that circ_0009910, circ_0027478, and miR-1236-3p, in conjunction with AFP three, present a promising diagnostic and prognostic profile for HCC. Additional validation in larger cohorts is required to establish their clinical utility.

Role of MicroRNAs in Acute Myeloid Leukemia

MicroRNA (miRNA), a significant class of regulatory non-coding RNA (ncRNA), can regulate the expression of numerous protein-coding messenger RNAs (mRNAs). miRNA plays an important part in shaping the human transcriptome. So far, in the human genome, about 2500 miRNAs have been found. Acute myeloid leukemia (AML) belongs to a malignant clonal disorder of hematopoietic stem cells and is characterized by the uncontrolled clonal proliferation of abnormal progenitor cells in the bone marrow and blood. For the past several years, significant scientific attention has been attracted to the role of miRNAs in AML, since alterations in the expression levels of miRNAs may contribute to AML development. This review describes the main functions of non-coding RNA classes and presents miRNA biogenesis. This study aims to review recent reports about altered microRNA expression and their influence on AML cell survival, cell cycle, and apoptotic potential. Additionally, it summarizes the correlations between miRNAs and their target mRNAs in AML and outlines the role of particular miRNAs in AML subtypes according to ELN recommendations.

Advancing brain tumor therapy: unveiling the potential of PROTACs for targeted protein degradation

The long-term treatment of malignancies, particularly brain tumors, is challenged by abnormal protein expression and drug resistance. In terms of potency, selectivity, and overcoming drug resistance, Proteolysis Targeting Chimeras (PROTACs), a cutting-edge method used to selectively degrade target proteins, beats traditional inhibitors. This review summarizes recent research on using PROTACs as a therapeutic strategy for brain tumors, focusing on their mechanism, benefits, limitations, and the need for optimization. The review draws from a comprehensive search of peer-reviewed literature, scientific databases, and clinical trial databases. Articles published up to the knowledge cutoff date up to 14 April 2023 were included. Inclusion criteria covered PROTAC-based brain tumor therapies, including preclinical and early clinical studies, with no restrictions on design or publication type. We included studies using in vitro, in vivo brain tumor models, and human subjects. Eligible treatments involved PROTACs targeting proteins linked to brain tumor progression. We evaluated the selected studies for methodology, including design, sample size, and data analysis techniques. A narrative synthesis summarized key outcomes and trends in PROTAC-based brain tumor therapy. Recent research shows PROTACs selectively degrade brain tumor-related proteins with minimal off-target effects. They offer enhanced potency, selectivity, and the ability to combat resistance compared to traditional inhibitors. PROTACs hold promise for brain tumor treatment offering advantages over traditional inhibitors, but more research is needed to refine their mechanisms, efficacy, and safety. Larger-scale trials and translational studies are essential for assessing their clinical utility.

Unraveling the genetic connections for mitochondrial DNA control region and breast cancer susceptibility

Breast cancer, a complex global health concern, has predominantly been studied for nuclear DNA variations. However, the role of mitochondrial DNA (mtDNA) haplogroups in breast cancer susceptibility, especially in Pakistan, remains underexplored. This case-control study investigates the association between mtDNA haplogroups and breast cancer in Pakistan. The study reveals a significant abundance of haplogroup M in breast cancer cases by analyzing breast cancer patients and healthy controls through mitochondrial control region genome sequencing (p < 0.001). Increased frequencies of haplogroups M, H, and R in patients compared to controls suggest their potential role in breast cancer susceptibility. Triple-Negative Breast Cancer (TNBC) cases are also linked to haplogroup M, showing a statistically significant association with a p-value of 0.002. This suggests a potential meaningful association between haplogroup M and the occurrence of TNBC in the studied population. These findings emphasize the importance of mitochondrial genetics in breast cancer risk among the Pakistani population, offering insights for biomarker discovery and targeted interventions. Recognizing mitochondrial genetics in breast cancer risk assessment holds promise for tailored medicine strategies and may impact global breast cancer research and prevention efforts.

Navigating PROTACs in Cancer Therapy: Advancements, Challenges, and Future Horizons

Proteolysis Targeting Chimeras (PROTACs) have revolutionized cancer therapy by offering a selective and innovative approach to degrade key oncogenic proteins associated with various malignancies. These hybrid molecules exploit the ubiquitin-proteasome system, facilitating the degradation of target proteins through an event-driven mechanism, thereby overcoming drug resistance and enhancing selectivity. With diverse targets including androgen receptors, BTK, estrogen receptors, BET proteins, and BRAF, PROTACs offer a versatile strategy for personalized cancer treatment. Advantages of PROTACs over traditional small molecule inhibitors include their ability to operate at lower concentrations, catalyzing the degradation of multiple proteins of interest with reduced cytotoxicity. Notably, PROTACs address challenges associated with traditionally "undruggable" targets, expanding the therapeutic landscape of cancer therapy. Ongoing preclinical and clinical studies highlight the transformative potential of PROTACs, with promising results in prostate, breast, lung, melanoma, and colorectal cancers. Despite their potential, challenges persist in optimizing physicochemical properties and enhancing bioavailability. Further research is needed to refine PROTAC design and address complexities in molecule development. Nevertheless, the development of oral androgen receptor PROTACs represents a significant milestone, demonstrating the feasibility and efficacy of this innovative therapeutic approach. This review provides a comprehensive overview of PROTACs in cancer therapy, emphasizing their mechanism of action, advantages, and challenges. As PROTAC research progresses, continued exploration in both preclinical and clinical settings will be crucial to unlocking their full therapeutic potential and shaping the future of personalized cancer treatment.

Circular RNAs in cancer: roles, mechanisms, and therapeutic potential across colorectal, gastric, liver, and lung carcinomas

The prominence of circular RNAs (circRNAs) has surged in cancer research due to their distinctive properties and impact on cancer development. This review delves into the role of circRNAs in four key cancer types: colorectal cancer (CRC), gastric cancer (GC), liver cancer (HCC), and lung cancer (LUAD). The focus lies on their potential as cancer biomarkers and drug targets. Our study analyses the reported circRNAs in the mentioned malignancies, examining their nature, functions, targets, origins, and contributions as tumor enhancers or suppressors. The approach involved assessing full-text reports on PMC, utilizing keywords such as "CircRNA" and "Cancer types," coupled with bioinformatics, experimental assays, or clinical investigations. Exclusions encompassed non-English publications, conference abstracts, letters, and expert opinions. The findings unveil 577 identified circRNAs across these cancer types: 124 in CRC, 177 in GC, 93 in HCC, and 183 in LUAD. Mechanistic insights into how circRNAs modulate gene expression in cancer are explored, particularly their interactions with microRNAs and RNA-binding proteins. Dysregulation of circRNAs across various cancers and their potential as diagnostic and prognostic indicators are synthesized. The exploration extends to the potential of targeting circRNAs as a novel cancer therapy strategy, either through inhibiting oncogenic circRNAs or reinstating tumor-suppressive ones. This article discusses the challenges and prospects in harnessing circRNAs for cancer diagnostics and therapies. These comprehensive analyses hold promise for advancing cancer research and fostering the development of innovative therapies and diagnostics.

Anticancer potential of hydroxycinnamic acids: mechanisms, bioavailability, and therapeutic applications

Hydroxycinnamic acids (HCAs) are plant compounds with anticancer potential due to their antioxidant, anti-inflammatory, apoptosis-inducing, and proliferation-inhibiting effects. This review aims to consolidate and analyze current knowledge on the anticancer effects of HCAs, exploring their mechanisms of action, bioavailability challenges, and potential therapeutic applications. A comprehensive literature search on PubMed/MedLine, Scopus, Web of Science, and Google Scholar focused on the anticancer properties, mechanisms, bioavailability, and safety profiles of HCAs. Studies have shown that HCAs, such as caffeic acid, ferulic acid, and sinapic acid, inhibit the growth of cancer cells in vitro and in vivo and sensitize cancer cells to chemotherapy and radiation therapy. These effects are mediated by mechanisms including the inhibition of cell survival pathways, modulation of gene expression, and induction of oxidative stress and DNA damage. Additionally, several studies have demonstrated that HCAs exhibit selective toxicity, with a higher propensity to induce cell death in cancerous cells compared to normal cells. However, the toxicity profile of HCAs can vary depending on the specific compound, dosage, and experimental conditions. The anticancer properties of HCAs suggest potential applications in cancer prevention and treatment. However, it is essential to distinguish between their use as dietary supplements and therapeutic agents, as the dosage and formulation suitable for dietary supplements may be insufficient for therapeutic purposes. The regulatory and practical implications of using HCAs in these different contexts require careful consideration. Further research is needed to determine appropriate dosages, formulations, long-term effects, and regulatory frameworks for HCAs as both dietary supplements and therapeutic agents.

Ethnogenetic analysis reveals the Bronze Age genetic affiliation of Yashkuns with West Eurasians

Focusing on the Yashkun population of Gilgit-Baltistan, an administrative territory in northern Pakistan, our study investigated mtDNA haplotypes as indicators of ancient gene flow and genetic diversity. Genomic DNA was extracted and evaluated for quality using agarose gel electrophoresis. The complete control region of mtDNA (nt 16024-576) was amplified via PCR, and sequencing was performed using the Big Dye Terminator Kit on an Applied Biosystems Genetic Analyzer. Sequence alignment and analysis were conducted using Geneious software and the Cambridge Reference Sequence (CRS). Haplotypes were classified into phylogenetic haplogroups with HaploGrep 2 and the Mito Tool platform, referencing PhyloTree version 17. The study identified considerable genetic diversity within the Yashkun population, with major macro-haplogroups H (29.47%), T (13.68%), and M (13.68%) representing West Eurasian, South Asian, and East & Southeast Asian lineages. The highest genetic affiliation was with West Eurasian haplogroups (73.68%), indicating significant gene flow from the West. The population's genetic distinctiveness was highlighted by the calculation of forensic genetic characteristics, such as power of discrimination (PD = 0.9975), genetic diversity (GD = 0.9865), and random match probability (RMP = 0.01349). The knowledge of the genetic makeup of the Yashkun population was further improved by the inference of phylogenetic links made possible by comparisons with other indigenous groups in Pakistan. These results attest to the reliability of mtDNA data for forensic applications such as ancestry tracking, individual identification, and additions to national forensic databases. The inclusion of mtDNA analysis in forensic science is strongly supported by this groundbreaking study on the Yashkun community, especially in areas like Pakistan with diverse genetic histories.

Exploring the therapeutic potential of cannabinoids in cancer by modulating signaling pathways and addressing clinical challenges

For centuries, cannabinoids have been utilized for their medicinal properties, particularly in Asian and South-Asian countries. Cannabis plants, known for their psychoactive and non-psychoactive potential, were historically used for spiritual and remedial healing. However, as cannabis became predominantly a recreational drug, it faced prohibition. Recently, the therapeutic potential of cannabinoids has sparked renewed research interest, extending their use to various medical conditions, including cancer. This review aims to highlight current data on the involvement of cannabinoids in cancer signaling pathways, emphasizing their potential in cancer therapy and the need for further investigation into the underlying mechanisms. A comprehensive literature review was conducted using databases such as PubMed/MedLine, Google Scholar, Web of Science, Scopus, and Embase. The search focused on peer-reviewed articles, review articles, and clinical trials discussing the anticancer properties of cannabinoids. Inclusion criteria included studies in English on the mechanisms of action and clinical efficacy of cannabinoids in cancer. Cannabinoids, including Δ9-THC, CBD, and CBG, exhibit significant anticancer activities such as apoptosis induction, autophagy stimulation, cell cycle arrest, anti-proliferation, anti-angiogenesis, and metastasis inhibition. Clinical trials have demonstrated cannabinoids' efficacy in tumor regression and health improvement in palliative care. However, challenges such as variability in cannabinoid composition, psychoactive effects, regulatory barriers, and lack of standardized dosing remain. Cannabinoids show promising potential as anticancer agents through various mechanisms. Further large-scale, randomized controlled trials are essential to validate these findings and establish standardized therapeutic protocols. Future research should focus on elucidating detailed mechanisms, optimizing dosing, and exploring cannabinoids as primary chemotherapeutic agents.

circ_SMA4 promotes gastrointestinal stromal tumors malignant progression by sponging miR-494-3p/KIT axis and activating JAK/STAT pathway

Recent evidence has demonstrated that abnormal expression and regulation of circular RNA (circRNAs) are implicated in the development and progression of various tumors. The aim of this study was to investigate the effects of circ_SMA4 in Gastrointestinal Stromal Tumors (GISTs) malignant progression. Human circRNAs microarray analysis was conducted to identify differentially expressed (DE) circRNAs in GISTs. The effect of circ_SMA4 on cell proliferation, invasion, migration, and apoptosis was assessed in both in vitro and in vivo settings. Dual-luciferase reporter assay, RT-qPCR, Western-blot, and rescue assay were employed to confirm the interaction between circ_SMA4/miR-494-3p/ KIT axis. The results revealed that circ_SMA4 was significantly upregulated in GISTs, and exhibited high diagnostic efficiency with an AUC of 0.9824 (P < 0.01). circ_SMA4 promoted cell proliferation, invasion, migration, while inhibiting apoptosis in GISTs cells, both in vitro and in vivo. Silencing circ_SMA4 partially inhibited GISTs malignant progression. Additionally, circ_SMA4 acted as a competing endogenous RNA (ceRNA) by targeting miR-494-3p, and KIT was identified as a functional gene for miR-494-3p in GISTs. Furthermore, the results confirmed that circ_SMA4/miR-494-3p/ KIT axis plays a role in activating the JAK/STAT signaling pathway in GISTs. Therefore, for the first time, we have identified and emphasized that circ_SMA4 is significantly upregulated and plays an oncogenic role in GISTs by sponging miR-494-3p to activate the KIT/JAK/STAT pathway. These findings underscore circ_SMA4 may serve as a novel diagnostic biomarker and therapeutic target for GISTs.

The role of circular RNAs (circRNAs) as a prognostic factor in lung cancer: a meta-analysis

BACKGROUND

Lung cancer is a leading cause of cancer-related death worldwide. Among various histological types of lung cancer, majority are non-small cell lung cancer (NSCLC) which account for > 80%. Circular RNAs (circRNAs) are widely expressed in various cancers including lung cancer and implicated in tumourigenesis and cancer progression. This study aimed to systematically evaluate the prognostic values of circRNAs in lung cancer.

METHODS

A systematic literature search was done in PubMed, Embase, and MEDLINE databases to select the eligible studies which reported the association between the expression of circRNAs and overall survival (OS) or disease-free survival (DFS) in histopathologically diagnosed lung cancer patients. The pooled hazard ratio (HR) and 95% confidence interval (CI) were assessed to determine the prognostic significance of circRNAs.

RESULTS

A total of 43 studies were eligible for this meta-analysis (MA). 39 different types of circRNAs were reported: 28 showing upregulating and 11 showing downregulating action in lung cancer. High expression of circRNAs with upregulating action in lung cancer was associated with worse prognosis and poor OS (HR 1.93, 95% CI [1.61-2.33], p < 0.00001). High expression of circRNAs with downregulating action in lung cancer was associated with favorable OS and prognosis (HR 0.73, 95% CI [0.58-0.94], p = 0.01). However, there was no statistically significant association between high and low expression of both upregulating and downregulating circRNAs and DFS (HR 1.44, 95% CI [0.92-2.24], p = 0.11).

CONCLUSIONS

This MA confirmed the pivotal role of circRNAs as important prognostic biomarkers for lung cancer, especially NSCLC. High expression of upregulating circRNAs is associated with poor prognosis; however, high expression of downregulating circRNAs is associated with favorable prognosis. Therefore, downregulatory action of circRNAs should be considered a promising treatment in the management of lung cancer, especially NSCLC.

Roles and mechanisms of circular RNA in respiratory system cancers

Circular RNAs (circRNAs) constitute a class of endogenous non-coding RNAs (ncRNAs) that lack a 5'-ended cap and 3'-ended poly (A) tail and form a closed ring structure with covalent bonds. Due to its special structure, circRNA is resistant to Exonuclease R (RNaseR), making its distribution in the cytoplasm quite rich. Advanced high-throughput sequencing and bioinformatics methods have revealed that circRNA is highly conserved, stable, and disease- and tissue-specific. Furthermore, increasing research has confirmed that circRNA, as a driver or suppressor, regulates cancer onset and progression by modulating a series of pathophysiological mechanisms. As a result, circRNA has emerged as a clinical biomarker and therapeutic intervention target. This article reviews the biological functions and regulatory mechanisms of circRNA in the context of respiratory cancer onset and progression.