POTEE promotes breast cancer cell malignancy by inducing invadopodia formation through the activation of SUMOylated Rac1.

The small GTPase Rac1 (Ras-related C3 botulinum toxin substrate 1) has been implicated in cancer progression and in the poor prognosis of various types of tumors. Rac1 SUMOylation occurs during epithelial-mesenchymal transition (EMT), and it is required for tumor cell migration and invasion. Here we identify POTEE (POTE Ankyrin domain family member E) as a novel Rac1-SUMO1 effector involved in breast cancer malignancy that controls invadopodium formation through the activation of Rac1-SUMO1. POTEE activates Rac1 in the invadopodium by recruiting TRIO-GEF (Triple functional domain protein), and it induces tumour cell proliferation and metastasis in vitro and in vivo. We found that the co-localization of POTEE with Rac1 is correlated with more aggressive breast cancer subtypes. Given its role in tumour dissemination, the leading cause of cancer-related deaths, POTEE could represent a potential therapeutic target for these types of cancer.