Phosphoinositide Conversion Inactivates R‐RAS and Drives Metastases in Breast Cancer

• Published in: Advanced science 2022-03, Vol.9 (9), p.e2103249-n/a
• Main Authors: Li, Huayi, Prever, Lorenzo, Hsu, Myriam Y., Lo, Wen‐Ting, Margaria, Jean Piero, De Santis, Maria Chiara, Zanini, Cristina, Forni, Marco, Novelli, Francesco, Pece, Salvatore, Di Fiore, Pier Paolo, Porporato, Paolo Ettore, Martini, Miriam, Belabed, Hassane, Nazare, Marc, Haucke, Volker, Gulluni, Federico, Hirsch, Emilio
• Format: Article
• Language: English
• Subjects: Binding sites; Breast cancer; Breast Neoplasms; Cell adhesion & migration; Cell Adhesion - physiology; Cytoskeleton; Experiments; Extracellular matrix; Female; focal adhesions; Focal Adhesions - metabolism; Focal Adhesions - pathology; Gene expression; GTPase-Activating Proteins - metabolism; Humans; Kinases; Localization; metastases; Metastasis; migration; Phosphatidylinositols - metabolism; PI3KC2α; Protein expression; Proteins; RASA3; R‐RAS; Tumors
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202103249

Breast cancer is the most prevalent cancer and a major cause of death in women worldwide. Although early diagnosis and therapeutic intervention significantly improve patient survival rate, metastasis still accounts for most deaths. Here it is reported that, in a cohort of more than 2000 patients with breast cancer, overexpression of PI3KC2α occurs in 52% of cases and correlates with high tumor grade as well as increased probability of distant metastatic events, irrespective of the subtype. Mechanistically, it is demonstrated that PI3KC2α synthetizes a pool of PI(3,4)P2 at focal adhesions that lowers their stability and directs breast cancer cell migration, invasion, and metastasis. PI(3,4)P2 locally produced by PI3KC2α at focal adhesions recruits the Ras GTPase activating protein 3 (RASA3), which inactivates R‐RAS, leading to increased focal adhesion turnover, migration, and invasion both in vitro and in vivo. Proof‐of‐concept is eventually provided that inhibiting PI3KC2α or lowering RASA3 activity at focal adhesions significantly reduces the metastatic burden in PI3KC2α‐overexpressing breast cancer, thereby suggesting a novel strategy for anti‐breast cancer therapy. The authors report that overexpression of PI3KC2α in breast cancer correlates with high tumor grade and increased probability of distant metastatic events. Mechanistically, PI3KC2α produces PI(3,4)P2 at focal adhesion which inactivates R‐RAS by recruiting RASA3. This leads to increased focal adhesion disassembly and cell migration. Proof‐of‐concept is provided that inhibiting PI3KC2α or lowering RASA3 significantly reduces the metastatic burden.