PITPNC1 Recruits RAB1B to the Golgi Network to Drive Malignant Secretion

Enhanced secretion of tumorigenic effector proteins is a feature of malignant cells. The molecular mechanisms underlying this feature are poorly defined. We identify PITPNC1 as a gene amplified in a large fraction of human breast cancer and overexpressed in metastatic breast, melanoma, and colon cancers. Biochemical, molecular, and cell-biological studies reveal that PITPNC1 promotes malignant secretion by binding Golgi-resident PI4P and localizing RAB1B to the Golgi. RAB1B localization to the Golgi allows for the recruitment of GOLPH3, which facilitates Golgi extension and enhanced vesicular release. PITPNC1-mediated vesicular release drives metastasis by increasing the secretion of pro-invasive and pro-angiogenic mediators HTRA1, MMP1, FAM3C, PDGFA, and ADAM10. We establish PITPNC1 as a PI4P-binding protein that enhances vesicular secretion capacity in malignancy. •PITPNC1 promotes metastasis by melanoma, breast cancer, and colon cancer cells•PITPNC1 recruits RAB1B to the Golgi compartment of the cell•Golgi localization of RAB1B enhances vesicular secretion via GOLPH3 recruitment Halberg et al. identify PITPNC1 as a gene amplified in a large fraction of human breast cancer and overexpressed in multiple cancer types. PITPNC1 drives malignancy and metastasis by binding Golgi-resident PI4P and localizing RAB1B to the Golgi, facilitating GOLPH3 recruitment and secretion of pro-tumor factors.