Shear stress enhances anoikis resistance of cancer cells through ROS and NO suppressed degeneration of Caveolin-1.

Circulating tumor cells (CTCs) acquire enhanced anti-anoikis abilities after experiencing flow shear stress in the circulatory system. Our previous study demonstrated that low shear stress (LSS) promotes anoikis resistance of human breast carcinoma cells via caveolin-1 (Cav-1)-dependent extrinsic and intrinsic apoptotic pathways. However, the underlying mechanism how LSS enhanced Cav-1 expression in suspended cancer cells remains unclear. Herein, we found that LSS induced redox signaling was involved in the regulation of Cav-1 level and anoikis resistance in suspension cultured cancer cells. Exposure of human breast carcinoma MDA-MB-231 cells to LSS (2 dyn/cm2) markedly induced ROS and •NO generation, which promoted the cell viability and reduced the cancer cell apoptosis. Furthermore, ROS and •NO scavenging inhibited the upregulation of Cav-1 by interfering ubiquitination, and suppressed the anoikis resistance of suspended tumor cells. These findings provide new insight into the mechanism by which LSS-stimulated ROS and •NO generation increases Cav-1 stabilization in suspended cancer cells through inhibition of ubiquitination and proteasomal degradation, which could be a potential target for therapy of metastatic tumors.