Non-coding RNAs regulation in breast cancer pathogenesis.

Breast cancer represents a molecularly heterogeneous disease shaped by complex genetic, epigenetic, and transcriptional dysregulation. Non-coding RNAs (ncRNAs) including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) as well as small nucleolar RNAs (snoRNAs), piwi-interacting RNAs (piRNAs), and small nuclear RNAs (snRNAs), have emerged as key epigenetic regulators that integrate multiple layers of gene control. Through interactions with chromatin-modifying enzymes, RNA-binding proteins, and signaling effectors, ncRNAs modulate transcriptional activity, chromatin accessibility, and post-transcriptional stability of target genes. miRNAs predominantly act as post-transcriptional repressors, whereas lncRNAs and circRNAs exert transcriptional and epigenetic control via scaffolding, miRNA sponging, and chromatin remodeling; some circRNAs even encode functional peptides. Aberrant ncRNA expression contributes to proliferation, metastasis, metabolic reprogramming, immune evasion, and therapeutic resistance, with distinct expression signatures associated with triple-negative, HER2-positive, and hormone receptor - positive breast cancers. Owing to their stability and detectability in plasma and exosomes, ncRNAs hold promise as minimally invasive biomarkers for early detection and disease monitoring. Moreover, therapeutic strategies targeting ncRNAs, such as antisense oligonucleotides, RNA interference, CRISPR/Cas-based editing, and ncRNA-derived vaccines, are advancing toward clinical translation. Collectively, ncRNAs redefine the epigenetic landscape of breast cancer, offering a framework for integrated diagnostic and therapeutic approaches in precision oncology.