MAM domain containing 2 is a potential breast cancer biomarker that exhibits tumour-suppressive activity.

OBJECTIVES The aim of this study was to discover new potential biomarkers of breast cancer and investigate their cellular functions. MATERIALS AND METHODS We analysed the gene expression profiles of matched pairs of breast tumour and normal tissues from 24 breast cancer patients. Tetracycline-inducible MAMDC2 expression system was established and used to evaluate cell proliferation in vitro and in vivo. MAMDC2-mediated signalling was determined using immunoblot analysis. RESULTS We identified MAMDC2 as a down-regulated gene showing significant prognostic capability. Overexpression of MAMDC2 or treatment with MAMDC2-containing culture medium significantly inhibited the cell proliferation of T-47D cells. Furthermore, MAMDC2 expression reduced in vivo growth of T-47D xenograft tumours. MAMDC2 may exert its growth-inhibitory functions by attenuating the MAPK signalling pathway. CONCLUSION We report that MAMDC2 has a tumour-suppressive role and, as a secretory protein, it might be useful as a biomarker for breast cancer treatment.