ROS-mediated induction of apoptosis by benzoquinone embelin in human colon adenocarcinoma cells HT-29.

Background Embelin is a benzoquinone reported to possess anticancer activity in several in vivo and in vitro models of carcinogenesis, especially hematopoietic and prostate malignancy. A detailed investigation on the influence of embelin on epithelial malignancy model system, especially colon adenocarcinoma, is lacking. The objective of the current study is to investigate the antiproliferative, antiinvasive and proapoptotic potential of embelin on colon adenocarcinoma cell line HT-29. Methods The effect of embelin (35 µg/mL for 24 h) on cell proliferation was assessed by Sulforhodamine B assay and bromodeoxyuridine incorporation test, antiinvasive effect by Boyden chamber assay and scratch assay. Proapoptotic effects of embelin were determined by studies on DNA fragmentation, annexin V-FITC labeling, TUNEL assay, COMET assay and assay of caspase-3 activity. Influence of embelin on the expression of genes regulating apoptosis (caspase 3 and 9, Bcl-2, Bax, cytochrome C and X-linked inhibitor of apoptosis protein) and migration/invasion (matrix metalloproteinase [MMP]-2 and MMP-9) was investigated by reverse transcription polymerase chain reaction (PCR). Further, the effect of embelin on the levels of reactive oxygen species (ROS), lipid peroxides, nitric oxide, mitochondrial membrane potential and antioxidant status (total reduced glutathione [GSH] and GSH-S-transferase) was evaluated. Results Results implicated that embelin treatment inhibited proliferation (IC50 35 µg/mL), induced DNA fragmentation, phosphatidyl serine externalization, increased caspase expression, decreased cell migration and expression of MMPs in HT-29 cells. Interestingly, embelin exhibited prooxidant effect on HT-29 cells and induced excessive ROS generation resulting in apoptotic cell death. Conclusions To conclude, embelin treatment could be a promising strategy for the chemotherapy of colon cancer.