Investigating Differential Expression of MicroRNAs Related to Recurrence in the Luminal Breast Cancer Subtype

Breast cancer is a heterogeneous disease, and patients with the luminal subtype have a range of outcomes unable to be predicted by current clinical methods. My hypothesis was that microRNA (miRNA) expression profiling might provide a method of discriminating tumours of this subtype into good and poor prognosis groups, and reveal miRNAs involved in recurrence.Expression profiling revealed nine miRNAs significantly differentially expressed in luminal tumours from patients with recurrence compared to patients without recurrence. Four, miR-135a-5p, miR-140-5p, miR-218-5p, and miR-200a-3p, selected for technical validation were confirmed as differentially expressed. Functional analysis in an in vitro breast cancer model revealed a reduction in cellular migration when miR-218-5p was ectopically overexpressed in two different assays, suggesting a possible association of miR-218-5p with metastasis, an important factor in recurrence. The expression of these miRNAs may allow improved prognostication in luminal tumours, and provide avenues of further research in breast cancer pathology.M.Sc