The response of muscle and inflammation-related miRNAs to breast cancer and its treatment

Abstract Aim this study aims to evaluate the response of muscle-specific (miR-1, miR-133, miR-208, miR-486, miR-499) and inflammation-related (miR-21, miR-146, and miR-155) miRNAs, well documented in side effects caused by cancer treatment and exercise physiology, to cancer and cancer treatment in breast cancer, in hope to looking for promising biomarkers to be investigated in prospective exercise program for monitoring physiologic response to exercise. Methods a total of 77 plasma was obtained from either Discipline of Surgery, University Hospital of Galway or Amsbio company. A panel of miRNAs, well documented in cancer- and cancer treatment-induced complications and exercise physiology, were detected in these 77 plasma samples by qRT-PCR. Results cancer subtypes and treatment approaches strongly impacted the expression of selected miRNAs: Luminal A had more impact on muscle-specific miRNAs while Luminal B had more impact on inflammation-related miRNAs; surgery, chemotherapy combined therapy (4 out of 5 cases had both surgery and chemotherapy) had a prominent effect on miRNA change (miR-21 and miR-486) compared to endocrine therapy. Treatment duration and age hugely impacted the expression of selected miRNAs: Muscle-specific miR-133 and miR-486 significantly respond to cancer treatment in the first 91 days, and also have different responses to cancer treatment between younger and older breast cancer patients. Conclusion muscle-specific and inflammation-related miRNAs respond differently regardless of cancer subtypes, treatment regimens and duration, and age. miR-21, miR-133, and miR-486 may be promising biomarkers to be investigated in prospective patient cohort studies in exercise-based cancer rehabilitation for monitoring physiologic response to exercise.