NDR2 regulates non-small cell lung cancer cell migration under starvation by supporting autophagosome biogenesis through LC3 and ATG9A regulation

Non-small cell lung cancer (NSCLC) is characterized by the deregulation of the Hippo kinase NDR2 and high basal autophagic activity. NDR2 promotes autophagy-driven tumor growth in some cancers, but evidence in lung cancer is lacking. Human bronchial epithelial tumor cell (HBEC) lines H2030, H2030-BrM3, and H1299, with or without NDR2 depletion via siRNA or shRNA, were cultured for up to 24 h in the presence or absence of serum, and with or without the autophagosome-lysosome fusion inhibitor chloroquine (CQ). Autophagosome biogenesis, migration and Golgi apparatus functionality were analyzed. Serum deprivation of HBECs silences the expression of NDR1 but not NDR2. As shown by the increased expression of the autophagosome marker LC3-II, NDR2 participates to the formation and distribution of phagophores/autophagosomes in HBECs in an ATG9A-dependent manner. NDR2 is required for cargos degradation since its depletion disrupts lysosomal trafficking and/or fusion with autophagosomes. Finally, NDR2 silencing inhibits filopodia formation and cell polarization during HBEC migration under serum deprivation by disrupting Golgi repositioning to the leading edge, a process essential for cell migration. These data highlight NDR2's role in Golgi- and autophagy-regulated migration during starvation. Unlike NDR1, NDR2 is stabilized under starvation and promotes autophagy by regulating LC3 and ATG9A, thereby supporting NSCLC cell proliferation and migration. Routine staining for NDR2 and/or ATG9 could aid in diagnosing NSCLC with high migratory potential.