PINCH-1 interacts with myoferlin to promote breast cancer progression and metastasis.

PINCH-1 is a cytoplasmic component of the cell-extracellular matrix (ECM) adhesion machine that is frequently overexpressed in cancer. The functions and mechanism of PINCH-1 in cancer, however, remain to be determined. Here, we show that PINCH-1 interacts with myoferlin, a transmembrane protein that is critical for cancer progression. High expression of both PINCH-1 and myoferlin correlates with poor clinical outcome in human breast cancer patients. Ablation of PINCH-1 from breast cancer cells diminished myoferlin level and suppressed breast cancer cell proliferation, migration, and endothelial cell tube formation in vitro and breast tumor growth, angiogenesis and metastasis in vivo. Mechanistically, PINCH-1 controls myoferlin level through its interaction with myoferlin and regulation of its ubiquitination and proteasome-dependent degradation. Functionally, re-expression of PINCH-1, but not that of a myoferlin-binding defectiveΔLIM2 mutant, effectively reversed the inhibition of myoferlin expression and breast cancer progression induced by loss of PINCH-1. Finally, restoration of myoferlin expression was sufficient to reverse PINCH-1-deficiency induced inhibition on breast cancer progression. These results reveal a PINCH-1-myoferlin signaling axis that is critical for breast cancer progression and suggest a new strategy for therapeutic control of breast cancer.