Ageing is a well-accepted risk factor for developing cancer, however, the mechanisms that facilitate the age-associated increase in breast tumorigenesis have remained largely unknown. Now in Cancer Cell, Yan et al. use a preclinical rat model to study this.

Using an interactome analysis to study ligand and receptor interactions between the epithelial clusters, midkine, a growth factor that is involved in development and overexpressed in various tumours, had the most notable age-related increase in expression and activity. Through a series of analyses of various datasets, the authors confirmed that MDK (encoding midkine) is elevated in human breast cancer versus normal breast tissue, and that its expression correlates with clinical outcome in patients with breast cancer.