Participation of cathepsin B in emodin-induced apoptosis in HK-2 cells

Objective To Investigated cytotoxic effects of emodin on HK-2 cell (a human proximal tubular epithelial cell line)and relative mechanism in vitro.Methods Cells treated with a series of concentration of emodin were detected their viabilities by MTT assay.Morphological changes of nuclear were observed under a transmission electron microscope.The ratio of hypodiploid cells was analyzed by flow cytometry.The activities of caspase 3 and cathepsin B were detected by incubation with specific substrates respectively.Results Emodin induceed the death of HK-2 cell death,accompanied by the increase in the ratio of hypodiploid cells,and nuclear condensation and chromatin margination.Emodin at apoptosis-inducing concentrations caused an increase of caspase 3 activity.The caspase 3 inhibitor,Ac-DEVD-CHO,recovered HK-2 cell viability,inhibited the ratio of hypodiploid cells.Emodin increased the expression of cathepsin B protein and the activity of cathepsin B also.CA-074 [N-(1-3-trans-propyl-carbam oyloxirane-2-carbonyl)-1-isoleucyl-1-proline],a cathepsin B inhibitor,inhibited the increase of caspase 3 activity induced by emodin,and recovered HK-2 cell viability.Conclusion Emodin impairs HK-2 cell by inducting apoptosis in a caspase 3-dependent manner,and cathepsin B may be involved in this process.