Abstract:
The capability of cancer cells to resist to anoikis, migrate and invade surrounding tissues is associated with high metastatic potential and advanced stage of cancers. Recently, caveolin-1 (Cav-1) protein has garnered increased attention in implicating the aggressive behavior of cancer cells. We demonstrate herein that nitric oxide and hydrogen peroxide play a role in inhibiting anoikis process of lung cancer cells via caveolin-1 dependent mechanism. The Cav-1 function in inhibition of anoikis was demonstrated to be cause through Mcl-1 dependent mechanism. The present study demonstrated that Cav-1 regulates Mcl-1 through protein-protein interaction and inhibits its down-regulation during cell anoikis. Immunoprecipitation and immunocytochemistry studies showed that Cav-1 interacted with Mcl-1 and prevented it from degradation via the ubiquitin-proteasome pathway. Mcl-1 and Mcl-1-Cav-1 complex were highly elevated in Cav-1-overexpressing cells but were greatly reduced in Cav-1 knockdown cells. Consistent with this finding, we found that Mcl-1 ubiquitination was significantly attenuated by Cav-1 overexpression but increased by Cav-1 knockdown. Furthermore, we revealed herein that Cav-1 plays an important role in the migration and invasion of human lung carcinoma H460 cells and that these effects are differentially regulated by cellular ROS. Superoxide anion and hydrogen peroxide down-regulated Cav-1 expression and inhibited cell migration and invasion, whereas hydroxyl radical up-regulated the Cav-1 expression and promoted cell migration and invasion. The down-regulating effect of superoxide anion and hydrogen peroxide on Cav-1 is mediated through a transcription-independent mechanism that involves protein degradation via the ubiquitin-proteasome pathway.
