Lifelong dietary interventions selectively reverse age-associated circulating microRNA upregulation in a time-dependent manner in female MMTV-TGF-α mice

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, female breast cancer-prone transgenic mouse model. Blood samples were collected and circulating miRNA expression levels were determined at weeks 10 (young), 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 significantly altered the global circulating miRNA profile and validated targets were enriched in the IL-7 signaling, GPCR signaling, and TCA cycle. Both chronic and intermittent CR reshaped these age-associated alterations, with the consistent target pathways. The effects were most pronounced at adult age rather than old age, while the refeeding phase of the intermittent CR partially preserved the CR-induced miRNA patterns. Integrative analyses identified three key miRNAs (mmu-miR-142-5p, mmu-miR-30e-5p, mmu-miR-494-3p), where CR reversed the expression patterns induced by aging, suggesting a shared molecular mechanism. Our findings demonstrate that chronic and intermittent CR modulate circulating miRNAs in an age-dependent manner in female transgenic breast cancer-prone mice.