MIEN1 Human

MIEN1 is abundantly expressed in breast tumor tissues and is associated with poor disease-free survival in patients with Her-2 and luminal B subtypes of breast cancer . The protein is also overexpressed in other cancer types, indicating its broad role in tumor progression .

MIEN1 functions as a critical regulator of tumor cell migration and invasion, promoting systemic metastases . It increases cell migration by inducing filopodia formation at the leading edge of migrating cells . Additionally, MIEN1 is involved in the regulation of apoptosis, possibly through the control of CASP3, and may play a role in redox-related processes .

The protein undergoes post-translational modifications, such as isoprenylation at its C-terminal tail, which facilitates its translocation to the inner leaflet of the plasma membrane . This membrane association is essential for MIEN1’s function as a membrane-bound adapter molecule. MIEN1 also interacts with Annexin A2 (AnxA2), a Ca2±dependent phospholipid-binding protein, to enhance tumor cell motility .

MIEN1 contains an immunoreceptor tyrosine-based activation motif (ITAM) that undergoes phosphorylation-dependent activation . This phosphorylation is crucial for the regulation of filopodia generation, migration, and invasion. The interaction between MIEN1 and AnxA2 further accentuates tumor cell motility by stimulating cell surface translocation of AnxA2 and catalyzing its proteolytic activity .