Microproteins as a Hidden Player in Breast Cancer: From Molecular Insights to Therapeutic Potential

Breast cancer continues to pose a public health problem and is the second leading cause of cancer-related mortality among women globally. Despite advances in our understanding of cancer biology and the development of treatment strategies, the therapeutic response is not often satisfactory as treatment efficacy is limited by severe side effects and drug resistance. Therefore, there is an urgent need for innovative approaches to improve diagnosis, prognosis, and treatment of breast cancer. Recent advances in bioinformatics and proteomics have enabled the discovery of a novel class of small proteins encoded from the small open reading frames, which were previously thought to be non-coding. Emerging evidence has indicated that these microproteins play a pivotal role in modulating breast cancer progression. This article reviews the current understanding of microproteins, highlights the microproteins identified to date as key regulators in breast cancer, and explores their potential clinical applications in improving breast cancer management.