Lifelong dietary interventions remodel age-associated circulating microRNA landscape linking metabolism, neurogenesis, and breast cancer susceptibility

Breast cancer is among the leading causes of cancer mortality worldwide, with aging as a major risk factor. Caloric restriction (CR) is a well-established non-pharmaceutical intervention that extends healthspan and delays tumorigenesis, yet the systemic molecular mechanisms remain elusive. Both chronic and intermittent CR influence metabolic homeostasis, but their long-term effects on circulating miRNAs in breast cancer predisposition are unclear. Here, we examined how chronic and intermittent CR and subsequent refeeding remodel circulating miRNA networks in a tumor-free, breast cancer-prone transgenic mouse model. Blood samples were collected and circulating miRNA expression levels were determined at weeks 10 (baseline), 49 (adult), and 81 (old) using GeneChip miRNA 4.1 Array. Differential expression and target enrichment analysis were performed to identify age- and diet-associated modulatory patterns. Aging was associated with notable alterations in circulating miRNAs, and validated targets were enriched in the regulation of neurogenesis, MAPK, and FoxO signaling. Both chronic and intermittent CR reshaped these age-associated alterations, with the regulation of neurogenesis emerging as a key regulatory pathway. The effects were most pronounced at adult age rather than old age, while refeeding phase of the intermittent CR partially preserved the CR-induced miRNA patterns. Integrative analyses identified ten core miRNAs, where CR counteracted the expression patterns induced by aging, suggesting shared molecular mechanisms connecting aging, diet, and breast cancer risk. Our findings demonstrate that chronic and intermittent CR modulate circulating miRNAs in an age-dependent manner. These circulating miRNAs may act as systemic mediators linking to CR to neuroendocrine homeostasis and reduced breast cancer susceptibility.