Mechanisms and therapeutic implications of gene expression regulation by circRNA-protein interactions in cancer

Non-coding RNA biomarkers in Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent cause of dementia among elderly individuals and is characterized by progressive cognitive decline, memory impairment, and the accumulation of amyloid-beta (Aβ) plaques and neurofibrillary tangles in the brain. Despite extensive research, current therapeutic approaches remain limited to symptomatic relief and are unable to halt disease progression. This challenge highlights the urgent need for reliable biomarkers that enable early diagnosis and facilitate the development of targeted interventions. Noncoding RNAs (ncRNAs) have recently emerged as promising biomarkers because of their regulatory roles in gene expression and cellular function. Among them, microRNAs (miRNAs) have revolutionized our understanding of neurodegenerative processes, with evidence linking their dysregulation to AD pathology. Additionally, circular RNAs (circRNAs), long noncoding RNAs (lncRNAs), and PIWI-interacting RNAs (piRNAs) have been implicated in neuronal survival, synaptic maintenance, and amyloid precursor protein processing, further expanding the biomarker landscape. This review examines the expression patterns, functional significance, and diagnostic potential of ncRNAs in AD, alongside methodological approaches for their detection. By bridging molecular insights with translational applications, we explore how ncRNAs may redefine AD diagnostics and therapeutic strategies in the future.

DDX27: An RNA helicase regulating cancer progression and therapeutic prospects

DDX27, a member of the DEAD-box RNA helicase family, plays a crucial role in RNA metabolism, inflammation, and cancer progression. Elevated expression of DDX27 has been observed in multiple cancers, including oral squamous cell carcinoma (OSCC), breast cancer (BC), colorectal cancer (CRC), gastric cancer (GC), and hepatocellular carcinoma (HCC), where it is associated with poor prognosis, tumor growth, metastasis, and chemoresistance. DDX27 regulates the NF-κB signaling pathway, which is central to inflammation and tumor progression, and influences key cellular processes such as cell cycle regulation, apoptosis, migration, and stemness. Additionally, DDX27 promotes epithelial-mesenchymal transition (EMT), further contributing to metastasis. Its interactions with non-coding RNAs and various signaling pathways complicate treatment responses, making DDX27 a promising therapeutic target. This review explores the role of DDX27 as both a biomarker and therapeutic target, with potential strategies including small molecule inhibitors, RNA interference, and combination therapies with existing treatments such as NF-κB inhibitors or chemotherapy. Targeting DDX27 may help overcome resistance, reduce metastasis, and improve cancer treatment outcomes. Further research into its molecular mechanisms and interactions will be crucial for developing effective therapies, particularly for cancers with high metastatic potential.

Extrachromosomal circular DNA drives dynamic genome plasticity: emerging roles in disease progression and clinical potential

Extrachromosomal circular DNA (eccDNA) has emerged as a dynamic and versatile genomic element with key roles in physiological regulation and disease pathology. This review synthesizes current knowledge on eccDNA, covering its classification, biogenesis, detection methods, biological functions, and clinical implications. Once considered rare anomalies, eccDNAs are now recognized as major drivers of oncogene amplification, genomic plasticity, and therapeutic resistance, particularly in cancer. EccDNA subtypes such as microDNA, double minutes, and ecDNA are defined by their structural, genomic, and pathological features. EccDNAs originate through diverse mechanisms including DNA repair, chromothripsis, breakage fusion bridge cycles, and apoptosis, occurring in both normal and stressed cells. Advances in long-read and single-cell sequencing, CRISPR-based synthesis, and computational tools have improved detection and functional analysis. Functionally, eccDNAs contribute to transcriptional amplification, activate immune responses through cGAS-STING signaling, and facilitate intercellular communication. They are found across a range of tissues and disease states-including cancer, cardiovascular, neurological, autoimmune, and metabolic disorders-and serve as both biomarkers and regulatory elements. We introduce the concept of the stress selection theory, which proposes eccDNA as an adaptive reservoir that enhances cellular fitness in response to environmental and therapeutic pressures. Despite growing insights, challenges remain in understanding tissue-specific roles, achieving clinical translation, and standardizing methodologies. Emerging tools in multi-omics, spatial biology, and artificial intelligence are expected to drive future breakthroughs in precision medicine.

Therapeutic targeting of circTNK2 with nanoparticles restores tamoxifen sensitivity and enhances NK cell-mediated immunity in ER-positive breast cancer

Endocrine resistance is a leading cause of relapse in patients with estrogen receptor (ER)-positive breast cancer (ER+ BC), with tamoxifen resistance being the most prevalent form. circTNK2, a circular RNA, is overexpressed in tamoxifen-resistant BC tissues and is correlated with poor prognosis. circTNK2 encodes a novel 487-amino acid protein, termed C-TNK2-487aa, which inhibits the recruitment of natural killer (NK) cells into BC tumors. Mechanistically, C-TNK2-487aa interacts with STAT3 and promotes STAT3 phosphorylation (p-STAT3) in ER+ BC cells. The increased p-STAT3 competes with STAT1 binding, inhibiting the formation of STAT1 homodimers that induces CXCL10 expression, ultimately leading to immune evasion. Additionally, circTNK2 RNA binds to SRSF1 and promotes tamoxifen resistance and BC tumorigenicity by activating AKT-mTOR signaling. Delivery of BC-targeting ZIF-8 nanoparticles loaded with circTNK2 antisense oligonucleotides (ASOs) and a CXCL10-encoding plasmid DNA markedly suppresses the growth of BC tumor xenografts, restores tamoxifen sensitivity, and increases CD56+ NK cell infiltration into BC tumors. Our data describe a critical role of the circTNK2-encoded peptide and its RNA in ER+ BC resistance to tamoxifen and immune evasion, providing a therapeutic vulnerability in treating tamoxifen-resistant breast cancer.

Mechanism of circRNA_4083 Circularization and Its Role in Regulating Cell Viability

Circular RNAs (circRNAs), a class of covalently closed non-coding RNAs, are pivotal regulators of gene expression and contributors to disease pathogenesis. This study elucidated the biogenesis, functional significance, and regulatory network of circRNA_4083, a novel exon-derived circRNA originating from exons 22 and 23 of the MSH3 gene in chicken. Through comprehensive molecular characterization-including Sanger sequencing, RNase R digestion assays, and subcellular localization-we confirmed the robust stability and predominant cytoplasmic localization of circRNA_4083 across diverse chicken tissues. Mechanistic investigations revealed that reverse complementary sequences within flanking intronic regions are indispensable for its circularization, as demonstrated by overexpression plasmids (#1-#4) in DF-1 cells. Functional analyses demonstrated that circRNA_4083 significantly inhibited cell apoptosis and increased cellular viability. Integrative bioinformatics approaches predicted a competing endogenous RNA (ceRNA) network comprising 12 miRNAs and 2132 target genes (FDR < 0.05), with significant enrichment in pathways critical to genomic stability, including non-homologous end joining (NHEJ) and ubiquitin-mediated proteolysis. These findings position circRNA_4083 as a key modulator of cellular viability and genomic integrity, with potential implications for avian leukosis virus-J (ALV-J) pathogenesis and resistance breeding strategies. This work advances our understanding of circRNA-driven regulatory mechanisms in avian species and underscores their relevance in poultry health.

Emerging role and clinical applications of circular RNAs in human diseases

Circular RNAs (circRNAs) are a large family of non-coding RNAs characterized by a single-stranded, covalently closed structure, predominantly synthesized through a back-splicing mechanism. While thousands of circRNAs have been identified, only a few have been functionally characterized. Although circRNAs are less abundant than other RNA types, they exhibit exceptional stability due to their covalently closed structure and demonstrate high cell and tissue specificity. CircRNAs play a critical role in maintaining cellular homeostasis by influencing gene transcription, translation, and post-translation processes, modulating the immune system, and interacting with mRNA, miRNA, and proteins. Abnormal circRNA expression has been associated with a wide range of human diseases and various infections. Due to their remarkable stability in body fluids and tissues, emerging research suggests that circRNAs could serve as diagnostic and therapeutic biomarkers for these diseases. This review focuses on the emerging role of circRNAs in various human diseases, exploring their biogenesis, molecular functions, and potential clinical applications as diagnostic and therapeutic biomarkers with current evidence, challenges, and future perspectives. The key theme highlights the significance of circRNAs in regulating gene expression, their involvement in diseases like cancer, neurodegenerative disorders, cardiovascular diseases, and diabetes, and their potential use in translational medicine for developing novel therapeutic strategies. We also discuss recent clinical trials involving circRNAs. Thus, this review is important for both basic researchers and clinical scientists, as it provides updated insights into the role of circRNAs in human diseases, aiding further exploration and advancements in the field.