PTEN deficiency exposes a requirement for an ARF GTPase module in integrin-dependent invasion in ovarian cancer

Dysregulation of the PI3K/AKT pathway is a common occurrence in ovarian carcinomas. Loss of the tumour suppressorPTENin high-grade serous ovarian carcinoma (HGSOC) is associated with a patient subgroup with poor prognosis. The cellular mechanisms of howPTENloss contributes to HGSOC are largely unknown. We utilise long-term time-lapse imaging of HGSOC spheroids coupled to a machine learning approach to classify the phenotype ofPTENloss.PTENdeficiency does not affect proliferation but rather induces PI(3,4,5)P₃-rich and -dependent membrane protrusions into the extracellular matrix (ECM), resulting in a collective invasion phenotype. We identify the small GTPase ARF6 as a crucial vulnerability uponPTENloss. Through a functional proteomic CRISPR screen of ARF6 interactors, we identify the ARF GTPase-activating protein (GAP) AGAP1 and the ECM receptor β1-integrin (ITGB1) as key ARF6 interactors regulating thePTENloss-associated invasion phenotype. ARF6 functions to promote invasion by controlling the recycling of internalised, active β1-integrin complexes to maintain invasive activity into the ECM. The expression of the ARF6-centred complex in HGSOC patients is inversely associated with outcome, allowing identification of patient groups with improved versus poor outcome. ARF6 may represent a new therapeutic vulnerability inPTEN- depleted HGSOC tumours.