Circulating MicroRNAs Reflect Body Composition Features in Newly Diagnosed Breast Cancer.

Alterations in body composition are clinically relevant features occurring in patients with breast cancer (BC), but the mechanism remains poorly defined. We investigated whether circulating microRNAs (miRNAs) involved in skeletal muscle (SM) and adipose tissue (AT) metabolism are associated with body composition alterations in BC. We analyzed by RT-qPCR circulating levels of SM- and AT-related miRNAs in a cohort of breast cancer patients (BCPs) (n = 46) and controls (n = 16). Associations between miRNA profiles and body composition parameters were evaluated. miR-21, miR-29a, and miR-29b were upregulated in BCPs compared with controls (all p < 0.05). miR-133a was downregulated in patients with low muscle mass (p = 0.040), independently of adiposity. miR-133a was found to be lower in BCP subgroups with LUM-B and low levels of muscularity compared to those with LUM-A or LUM-B with high muscularity levels (all p < 0.05). Correlation analyses supported a closer association of miR-133a with SM-related parameters than with fat mass. miR-21, miR-29a and miR-29b appeared to reflect tumor-related systemic signaling. miR-133a was associated with reduced SM mass and influenced by tumor molecular subtype. These results suggest that miR-133a might represent a potential mediator of cancer-associated SM alterations and warrant validation in larger longitudinal studies.