Thesis (Ph.D.)--Chulalongkorn University, 2011

Both Caveolin-1 (Cav-1) and Mcl-1 have been implicated in the regulation of cancer cell anoikis but their relationship and underlying mechanisms of regulation are not known. By using the kinetics, the present study demonstrated that Cav-1 and Mcl-1 both regulate anoikis in non small cell lung cancer cells (NSCLCs). Modulation of Cav-1 and Mcl-1 levels by overexpressing or short hairpin containing plasmids was shown to influence the cell viability and apoptosis after detachment in H460 cells which indicates the pivotal role of Cav-1 and Mcl-1 in regulating anoikis in this cancer cell model. The western blot results have been shown that the levels of Cav-1 and Mcl-1 were gradually reduced over time of detachment. Correlation analysis shows that the reduction of these two proteins has closely correlated with Pearson correlation (r) = 0.986 (p-value< 0.0001) leading to the hypothesis of the interaction between Cav-1 and Mcl-1 proteins. Immunoprecipitation and immunofluorescence studies suggested that Cav-1 interacted with Mcl-1 and prevented it from degradation via the ubiquitin-proteasome pathway during cell anoikis. 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, it was found that Mcl-1 ubiquitination was significantly attenuated by Cav-1 overexpression but increased by Cav-1 knockdown. Together, our results indicate a novel role of Cav-1 in anoikis regulation through Mcl-1 interaction and stabilization, which provides a new insight to the pathogenesis of metastatic lung cancer and its potential treatment.