Autophagy inhibition specifically promotes epithelial-mesenchymal transition and invasion in RAS-mutated cancer cells

Macroautophagy/autophagy inhibition is a novel anticancer therapeutic strategy, especially for tumors driven by mutant <i>RAS</i>. Here, we demonstrate that autophagy inhibition in <i>RAS</i>-mutated cells induces epithelial-mesenchymal transition (EMT), which is associated with enhanced tumor invasion. This is at least partially achieved by triggering the NFKB/NF-κB pathway via SQSTM1/p62. Knockdown of <i>ATG3</i> or <i>ATG5</i> increases oncogenic <i>RAS</i>-induced expression of ZEB1 and SNAI2/Snail2, and activates NFKB activity. Depletion of <i>SQSTM1</i> abolishes the activation of the NFKB pathway induced by autophagy inhibition in <i>RAS</i>-mutated cells. NFKB pathway inhibition by depletion of <i>RELA</i>/p65 blocks this EMT induction. Finally, accumulation of SQSTM1 protein correlates with loss of CDH1/E-cadherin expression in pancreatic adenocarcinoma. Together, we suggest that combining autophagy inhibition with NFKB inhibitors may therefore be necessary to treat <i>RAS</i>-mutated cancer. <b>Abbreviations:</b> 4-OHT: 4-hydroxytamoxifen; DIC: differential interference contrast; EMT: epithelial-mesenchymal transition; ESR: estrogen receptor; MAPK/ERK: mitogen-activated protein kinase; iBMK: immortalized baby mouse kidney epithelial cells; MET: mesenchymal-epithelial transition; PI3K: phosphoinositide 3-kinase; RNAi: RNA interference; TGFB/TGF-β: transforming growth factor beta; TNF: tumor necrosis factor; TRAF6: TNF receptor associated factor 6.