Involvement of Iysosomal proteolysis in hepatocyte cytotoxicity induced by Cu (II) or Cr (VI)

J. Pourahmad; P.J. O'Brien

doi:doi:10.1051/jp4:20030489

Issue		J. Phys. IV France Volume 107, May 2003


Page(s)		1087 - 1090
DOI		https://doi.org/10.1051/jp4:20030489

J. Phys. IV France 107 (2003) 1087
DOI: 10.1051/jp4:20030489

Involvement of Iysosomal proteolysis in hepatocyte cytotoxicity induced by Cu (II) or Cr (VI)

J. Pourahmad¹ and P.J. O'Brien²

¹ Faculty of Pharmacy, Shaheed Beheshti University of Medical Sciences, Tehran, P.O. Box 14155-6153, Iran
² Faculty of Pharmacy, University of Toronto, 19 Russell St., Toronto, Ontario M5S 2S2,Canada

Abstract
Previously we showed that the redox active Cu (II) and Cr (VI) were very powerful at inducing reactive oxygen species ("ROS") formation in hepatocytes and furthermore "ROS" scavengers prevented Cu (II) and Cr (VI) induced hepatocyte cytotoxicity [1, 2]. In the following it is shown that hepatocyte cytotoxicity induced by Cu (II) and Cr (VI) were preceded by lysosomal proteolysis as demonstrated by tyrosine release. Hepatocyte lysosomal proteolysis was also prevented by leupeptin and pepstatin (lysosomal protease inhibitors). Cu (II) and Cr (VI) induced cytotoxicity was also prevented by leupeptin and pepstatin. A marked increase in Cu (II) and Cr (VI) induced hepatocyte toxicity also occurred if the lysosomal toxins gentamicin or aurothioglucose were added at the same time as the Cu (II) and Cr (VI). Furthermore destabilizing lysosomal membranes beforehand by preincubating the hepatocytes with gentamicin or aurothioglucose prevented Cu (II) and Cr (VI) induced hepatocyte cytotoxicity. It is proposed that Cu (II) and Cr (VI) induced cytotoxicity involves lysosomal damage that causes the release of cytotoxic digestive enzymes as a result of lysosomal membrane damage by "ROS".