As with other non-coding RNAs (ncRNAs), the aberrant expression of long non-coding RNAs (lncRNAs) can be associated with different forms of cancers, including breast cancer (BC). Various lncRNAs may either promote or suppress cell proliferation, metastasis, and other related cancer signaling pathways by interacting with other cellular machinery, thus affecting the expression of BC-related genes. However, lncRNAs are characterized by features that are unlike protein-coding genes, which pose unique challenges when it comes to their study and utility. They are highly diverse and may display contradictory functions depending on factors like the BC subtype, isoform diversity, epigenetic regulation, subcellular localization, interactions with various molecular partners, and the tumor microenvironment (TME), which contributes to the intratumoral heterogeneity and phenotypic plasticity. While lncRNAs have potential clinical utility, their functional heterogeneity coupled with a current paucity of knowledge of their functions present challenges for clinical translation. Strategies to address this heterogeneity include improving classification systems, employing CRISPR/Cas tools for functional studies, utilizing single-cell and spatial sequencing technologies, and prioritizing robust targets for therapeutic development. A comprehensive understanding of the lncRNA functional heterogeneity and context-dependent behavior is crucial for advancing BC research and precision medicine. This review discusses the sources of lncRNA heterogeneity, their implications in BC biology, and approaches to resolve knowledge gaps in order to harness lncRNAs for clinical applications.

Age-related changes in neurotransmitter systems contribute to declines in cognitive, emotional, and motor function, yet the biological mechanisms linking these changes to aging are not completely understood. Epigenetic regulation offers a promising framework to bridge this gap. DNA methylation-based biomarkers of biological aging (i.e., epigenetic clocks) capture cumulative and dynamic aspects of biological aging that may reflect vulnerability in neural systems beyond chronological age. However, whether these indices track with the integrity of neurotransmitter systems has not been systematically examined. This scoping review synthesizes evidence across human studies to evaluate how epigenetic aging processes influence neurotransmitter gene regulation and system function across the lifespan. We included 109 studies spanning 2005–2026. GABAergic genes (GAD1, GABRA2) showed the most consistent and reproducible age-related promoter hypermethylation across the cortex, inversely correlated with mRNA expression and corroborated by MRS evidence of cortical GABA decline. Dopaminergic and serotonergic evidence during normative aging was sparse; most epigenetic data in these systems came from disease cohorts. Histone modifications converged on neurotransmission and synaptic-plasticity loci, predominantly in Alzheimer’s disease tissue. Subcortical and brainstem nuclei central to monoaminergic and cholinergic systems remain under-investigated for normative aging epigenetic processes. Environmental and social determinants, socioeconomic status, childhood adversity, and chronic stress, were consistently associated with accelerated peripheral epigenetic aging, but brain-specific data are scarce.