Figure 3.

Autophagy regulates multiple metastasis-related signaling pathways. (A) Autophagy mediates the degradation of focal adhesion proteins to promote focal adhesion disassembly and migration. The autophagy protein LC3-II mediates the targeted degradation of several focal adhesion proteins, including ubiquitinated (UBB) focal adhesion (FA) proteins through NBR1, phosphorylated SRC (SRC p-Y416) through CBLC, and SRC-mediated phosphorylated PXN. (B) Autophagy negatively regulates Rho GTPases. Autophagy is activated by RHOA-ROCK signaling activity to target ARHGEF2 and RHOA for SQSTM1-dependent degradation through a negative feedback mechanism. Loss of autophagy can promote metastasis through increased RHOA activity. Autophagy and RAC negatively regulate one another, whereas CDC42 promotes autophagy. (C) Autophagy promotes anoikis-resistance. In detached cells and CTCs, autophagy is stimulated to suppress anoikis through several mechanisms, including EIF2AK3-ATF4-mediated increases in ATG gene expression, EIF2AK3-mediated suppression of MTORC1, and ROS-CCAR2-mediated IKK activation. (D) Autophagy suppresses EMT and fibrosis. EMT and fibrosis promote metastasis and exhibit mechanistic overlap. TGFB1 signals through SMAD, which promotes SNAIL- and TWIST-induced EMT and fibrosis. Autophagy negatively regulates EMT through SQSTM1-mediated degradation of SNAIL and by reducing SQSTM1-mediated stabilization of TWIST. Autophagy reduces FN1 and fibrosis by suppressing ROS to inhibit IL1B- and NFKB-induced fibrosis, and through MAP1S-dependent autophagic degradation of FN1.