Circular RNAs (circRNAs) are non‑coding single‑stranded covalently closed RNA molecules that are considered important as regulators of gene expression at the transcriptional and post‑transcriptional levels. These molecules have been implicated in the initiation and progression of multiple human diseases, ranging from cancer to inflammatory and metabolic diseases, including diabetes mellitus and its vascular complications. The present article aimed to review the current knowledge on the biogenesis and functions of circRNAs, as well as their role in cell processes associated with diabetic nephropathy. In addition, novel potential interactions between circRNAs expressed in renal cells exposed to high‑glucose concentrations and the transcription factors c‑Jun and c‑Fos are reported.

In recent years, it has been discovered that the expression of long non-coding RNAs is highly deregulated in several types of cancer and contributes to its progression and development. Recently, it has been described that in tumors of the digestive system, such as colorectal cancer, pancreatic cancer, and gastric cancer, DNA damage-activated lncRNA (NORAD) was frequently up-regulated. The purpose of this review is to elucidate the functions of NORAD in tumors of the digestive system, emphasizing its involvement in important cellular processes such as invasion, metastasis, proliferation, and apoptosis. NORAD acts as a ceRNA (competitive endogenous RNA) that sponges microRNAs and regulates the expression of target genes involved in tumorigenesis. Thus, the mechanisms underlying the effects of NORAD are complex and involve multiple signaling pathways. This review consolidates current knowledge on the role of NORAD in digestive cancers and highlights the need for further research to explore its potential as a therapeutic target. Understanding the intricate functions of NORAD could elucidate the way for innovative approaches to cancer treatment.

Trichomonas vaginalis, the protozoan responsible for trichomoniasis, encounters fluctuating levels of metal cations in the male urogenital tract, notably zinc (Zn²⁺) and cadmium (Cd²⁺), which may induce genotoxic stress. While zinc is a key physiological component of the male reproductive tract, both Zn²⁺ and Cd²⁺ can become genotoxic at elevated concentrations. However, their effect on DNA repair mechanisms in T. vaginalis remains poorly understood. This study characterizes, for the first time, the expression and modulation of the recombinase TvRAD51, a homologous recombination (HR) key enzyme, in response to UV irradiation and sublethal concentrations of Zn²⁺ (1.6 mM) and Cd²⁺ (0.1 mM). In silico analyses confirmed the presence and conserved structure of the tvrad51 gene and its interaction with HR-related proteins, such as TvBLM and TvBRCA2. Quantitative RT-PCR, Western blot, and immunofluorescence assays revealed that TvRAD51 is upregulated at both transcript and protein levels following UV- and cation-induced DNA damage, with distinct temporal expression patterns for Zn²⁺ and Cd²⁺ exposure. Notably, TvRAD51 showed nuclear localization at early time points post-exposure, suggesting active participation in DNA repair processes. These findings demonstrate that TvRAD51 is a central component of the genotoxic stress response in T. vaginalis, potentially contributing to parasite survival and adaptation in hostile environments through homologous recombination repair pathways.

Nuclear receptors (NRs) are ligand-activated transcription factors that regulate gene expression and are involved in diverse physiological and pathological processes, including carcinogenesis. In bladder cancer (BCa), dysregulation of NR signaling pathways has been linked to tumor initiation, progression, therapy resistance, and immune evasion. Recent evidence highlights the intricate crosstalk between NRs and microRNAs (miRNAs), which are small non-coding RNAs that posttranscriptionally modulate gene expression. This review provides an integrated overview of the molecular interactions between key NRs and miRNAs in BCa. We investigated how miRNAs regulate NR expression and function and, conversely, how NRs influence miRNA biogenesis, thereby forming regulatory feedback loops that shape tumor behavior. Specific miRNA–NR interactions affecting epithelial-to-mesenchymal transition, metabolic reprogramming, angiogenesis, and chemoresistance are discussed in detail. Additionally, we highlight therapeutic strategies targeting NR–miRNA networks, including selective NR modulators, miRNA mimics and inhibitors, as well as RNA-based combinatorial approaches focusing on their utility as diagnostic biomarkers and personalized treatment targets. Understanding the molecular complexity of NR–miRNA regulation in BCa may open new avenues for improving therapeutic outcomes and advancing precision oncology in urological cancers.

MicroRNAs (miRNAs) are key regulators of gene expression that act primarily by binding to target messenger RNAs (mRNAs). However, the biology of miRNAs is more complex than initially thought, with functional complexity extending beyond canonical sequences. A multilayered miRNA regulatory landscape involving isomiR generation, altered 5p/3p strand usage, arm switching, A-to-I RNA editing, and epitranscriptomic RNA modifications operates in eukaryotic cells to regulate miRNA function. Collectively, these mechanisms expand the functional diversity of miRNAs by regulating their biogenesis, stability, strand selection, and target specificity, increasing their functional plasticity and contributing to regulatory heterogeneity found in cells. IsomiRs arise from alternative Drosha/Dicer processing, terminal nucleotide additions, RNA editing, and genetic variation, producing functionally distinct isoforms. Arm switching alters gene regulatory outputs through context-dependent changes in predominant 5p/3p strand usage. In addition, epitranscriptomic RNA modifications, such as m6A and m5C, together with A-to-I RNA editing, represent an additional layer of miRNA regulation. These mechanisms can act directly on miRNAs or their precursors, or indirectly by modifying circRNAs and lncRNAs, thereby altering miRNA availability and function. Together, these processes form a dynamic regulatory network that influences key cancer hallmarks, including cell proliferation, apoptosis, epithelial–mesenchymal transition, metastasis, immune evasion, and therapy resistance. However, the contribution of these non-canonical regulatory layers to tumor-specific miRNA function remains poorly understood. In this review, we explore how isomiR generation, miRNA strand selection, arm switching, and epitranscriptomic regulation expand the functional diversity of miRNAs in gynecologic cancers.