Student Projects - Biology

Project Name

The Role of Peroxiredoxin 6 in Cancer Cell Resistance to Peroxide-Induced Cell Death

Project Description

Reactive oxygen species (ROS) such as hydrogen peroxide are generated in cells by normal metabolism and in response to various agents and conditions. The accumulation of ROS to high levels can lead to the inactivation of macromolecules, and sometimes cell death. Peroxiredoxin 6 is a member of a protein family that detoxifies reactive oxygen species like hydrogen peroxide. Unpublished results from our lab have demonstrated that that the cancerous Hepa1-6 hepatocyte cell line expresses higher levels of Prdx6 and lower peroxide-induced toxicity as compared to the non-cancerous H2.35 hepatocyte line. We hypothesize that the elevation of Peroxiredoxin 6 in Hepa1-6 cells protects them from peroxide-induced cell death.

Using western blotting, we found that H2.35 cells normally express p53, and the level is not induced by hydrogen peroxide. In contrast, Hepa1-6 cells express no p53 before or after treatment. Based on a colorimetric caspase-3 assay for apoptosis, we showed that peroxide-induced cell death in H2.35 cells does not occur by apoptosis. Further analysis of cell morphology and ethidium bromide nuclear staining suggests that this peroxide-induced cell death occurs by necrosis. We next investigated whether suppression of Prdx6 expression in Hepa1-6 by siRNA would increase susceptibility to peroxide-induced toxicity. Our results show that Pdrx6 is down-regulated in siRNA-transfected cells.

We currently are examining whether this suppression of Prdx6 increases cell death in response to hydrogen peroxide. This work may provide new insight into the molecular changes associated with carcinogenesis.

Project Outcomes

See abstract above. Further research is being conducted to determine if the cancer cells are dying by apoptosis or through necrosis, using a Caspase-3 assay.