Energy metabolism,
insulin resistance and adiposity have been implicated in
breast cancer, but dietary interventions to reduce
breast cancer morbidity and mortality have had limited success.
MicroRNA (
miRNA) are short,
non-coding RNA that participate in the control of metabolic processes through the post-transcriptional modification of
RNA. We investigated the effect of a low-glycaemic load dietary intervention on
miRNA expression, with subsequent bioinformatics pathway analyses to explore metabolic pathways potentially affected by the diet. Total
RNA, including
miRNA, was isolated from the serum of fourteen otherwise healthy pre-menopausal women with a high
breast cancer risk participating in a 12-month dietary intervention designed to lower glycaemic load by at least 15% from baseline. Genome-wide
miRNA expression was conducted using Illumina BeadChips. In the intervention subjects, three differentially expressed
miRNA were validated by real-time (RT)-PCR, and in the twenty control participants, four top differentially expressed
miRNA were evaluated to confirm a diet effect. In post-intervention v. baseline serum, twenty
miRNA were found to be differentially expressed, with twelve up-regulated and eight down-regulated. These differentially expressed
miRNA were predicted to be potentially associated with energy balance and
cancer pathways based on exploratory enrichment analysis. Quantitative RT-PCR validations in the controls confirmed that the observed
miRNA differential expression was dietary intervention induced. Manipulation of dietary glycaemic load has the potential to modify the expression of multiple
miRNA predicted to be involved in energy balance and
cancer pathways. Further research is necessary to confirm the role of these
miRNA in the control of energy metabolism and relationships with
cancer-related processes.