Boeravinone B a natural rotenoid exerts anticancer activity via inducing internalization and degradation of inactivated EGFR and ErbB2 in human colon cancer cells.

backgroundEpidermal growth factor receptors (EGFR) are identified to be favorable targets for cancer treatment. In present work, we showed that Boeravinone B, a Rotenoid from natural origin has significant anticancer activity via internalization of ErbB2 and EGFR, and thereby resulting in destruction of the receptors.

methodsFor cell viability and apoptosis were done by MTT assay. Annexin V-FITC staining was done for determining the extent of apoptosis. Immunoblotting for expression of proteins in HT-29 cell lysates after exposing them to Boeravinone G. Immunofluorescence and Confocal microscopic analysis was done for HT-29 cells incubated with anti-EGFR or anti-ErbB2 antibodies. Surface biotinylation assay was done followed by western blot analysis for expression of proteins using antibodies against transferrin receptor, ErbB2 and EGFR.

resultsExposure of HT-29 cells with Boeravinone B suppressed constitutive as well as ligand mediated phosphorylation of ErbB2, ErbB3 and EGFR. The treatment also inhibited the activation of mitogen-activated protein kinase (MAPK), Akt and Erk1/2 which are downstream signaling molecules. The treatment also bought about internalization of ErbB2 and EGFR causing destruction of receptors, Boeravinone B also caused apoptosis in HT-29 cells. Boeravinone B mediated degradation was halted by Chloroquine (lysosomal inhibitor). Boeravinone B caused nuclear translocation of apoptosis-inducing factor (AIF) and caused proteolytic processing of PARP along with caspase-3, confirming Boeravinone B may induce caspase-independent apoptosis in HT-29 cells.

conclusionThe findings of present study provide first ever evidences for Boeravinone B suggesting anticancer activity via internalization and destruction of EGFR family receptors i.e. ErbB2 and EGFR in HT-29 cell lines.