Response of colon cancer cells to selenium and cis‐platinum exposure

Abstract

Colon cancer is normally refractive to the chemotherapy drug cis‐platinum, (Cis‐Pt). Selenium (Se) containing glutathione peroxidase has been studied because of its role in reduction of reactive oxygen species which would improve the efficacy of Cis‐pt. The influence of Se on the effect of Cis‐PT on the HT‐29 colon cancer cell line was tested using a three dimensional agarose culture model. This method allowed independent analysis of mitosis and cell viability. Single cells were suspended in low temperature agarose and grown for 1 week. Se at low doses did not affect cell viability or mitosis when compared to vehicle controls. To simulate the in vivo scenario, colonies were allowed to form prior to Cis‐Pt exposure. Experiments were conducted to determine the time course of exposure to Se and Cis‐Pt. Some cultures were untreated or pretreated with Se (0.33 μg/ml) at day 0 followed by or in conjunction with Cis‐Pt (3 and 6 μg/ml) on day 4. On day 7 cultures were evaluated for cell viability, using trypan blue exclusion, and mitotic activity by counting single cells and colonies alive and dead. Differences between treatment groups were analyzed using ANOVA at 95% confidence level. Cell growth conditions allowed evaluation of glutathione peroxidase acitivity under each treatment condition following analysis of mitotic and cell viability. Glutathione peroxidase activity was compared to total protein in each cell culture. Initial results indicate that cultures treated with Se in conjunction with Cis‐Pt exhibited higher glutathione peroxidase activity coinciding with increased Cis‐Pt efficacy. These data suggest that supplementation with Se will increase efficacy of Cis‐Pt in colon cancer, specifically in the HT‐29 cell line, thus providing a more effective use of existing treatments. Support for this project was provided by The Raabe College of Pharmacy and the Department of Biological and Allied Health Sciences, Ohio Northern University.