Despite substantial progress in the field of bladder cancer management, the disease continues to represent an important health issue characterized by increased recurrence and progression rates. This is largely attributed to cancer stem cells (CSCs), a unique cell subpopulation capable of self-renewal, differentiation and resistance to conventional anti-cancer therapies. At the same time, our understanding of cancer biology has been revolutionized by the identification of non-coding RNAs (ncRNAs), a heterogeneous group of RNA molecules that do not translate into proteins yet function as pivotal regulators of gene expression. Emerging evidence demonstrates that ncRNAs modulate key hallmarks of CSCs, including self-renewal, epithelial–mesenchymal transition and drug resistance. This review investigates the intricate interplay between ncRNAs and the core signaling pathways that underlie bladder CSC biology. Unravelling the nexus between CSCs and ncRNAs is crucial for developing novel diagnostic biomarkers, better prognostic tools and innovative therapeutic strategies for patients with bladder cancer.

Erectile dysfunction (ED) is a prevalent condition involving multiple molecular mechanisms. Although non-coding RNAs have emerged as important regulators of gene expression, the role of circular RNAs (circRNAs) in ED remains poorly defined. CircRNAs are characterised by a covalently closed loop structure that confers enhanced stability and enables diverse regulatory functions. This review aims to investigate the potential interactions between circRNAs and the signalling pathways linked to ED. Only two primary studies directly investigating circRNA dysregulation in ED were identified, highlighting the early stage of this field. This hybrid systematic narrative review combines a PRISMA-guided systematic search with a pre-specified, hypothesis-generating narrative synthesis of the broader circRNA literature across key signalling pathways implicated in ED, including the NO/cGMP/PKG, RhoA/ROCK, JNK/c-Jun/Bak, and TNF-α/NF-κB axes. We identify several circRNAs as potential regulators of endothelial dysfunction, inflammation, and smooth muscle contractility. CircRNAs therefore emerge as candidate biomarkers and potential therapeutic targets. Given that direct evidence is currently limited to two animal studies, with no circRNA validated in human tissue or as a biomarker, these molecules should be regarded only as candidates for future biomarker and therapeutic target validation.