Background: Cancer is the disease that causes the most death after cardiovascular diseases
all over the world these days. Breast cancer is the most common type of cancer among women
and ranks the second among cancer-related deaths after lung cancer. Chemotherapeutics act by
killing cancer cells, preventing their spread and slowing their growth. Recent studies focus on the
effects of chemotherapeutics on cancer cells and new chemotherapy approaches that targeting enzymes
that catalyze important metabolic reactions in the cell.
Objective: The aim of this study was to investigate the effects of chemotherapeutic agents, Tamoxifen
and 5-FU, on MCF-7 cell line and human erythrocyte GST, an important enzyme of intracellular
Methods: In this study, it was investigated that the effect of chemotherapeutic agents, Tamoxifen
and 5-FU, on MCF-7 breast cancer cell line and performed ROS analyzes. In addition, it was purified
glutathione S-transferase (GST), one of the important enzymes of intracellular antioxidant
mechanism, from human erythrocytes by using ammonium sulfate precipitation and glutathione
agarose affinity chromatography, and investigated in vitro effects of chemotherapeutic agents, 5 -
FU and Tamoxifen, on the activity of this enzyme for the first time.
Results: it was determined that Tamoxifen and 5-FU inhibited cellular viability and 5-FU increased
intracellular levels of ROS, whereas Tamoxifen reduced intracellular levels of ROS. In addition,
human erythrocyte GST enzyme with 16.2 EU/mg specific activity was purified 265.97-fold
with a yield of 35% using ammonium sulfate precipitation and glutathione agarose affinity chromatography.
The purity of the enzyme was checked by the SDS-PAGE method. In vitro effects of chemotherapeutics,
5-FU and Tamoxifen, on GST activity purified from human erythrocytes were investigated.
The results showed that 5-FU increased the activity of GST in the concentration range
of 77 to 1155 μM and that Tamoxifen increased the activity of GST in the concentration range of
0.54 to 2.70 μM.
Conclusion: In this study, the effects of tamoxifen and 5-FU chemotherapeutic agents on both
MCF-7 cell line and human GST enzyme were examined together for the first time. Our study
showed that chemotherapeutic agents (5-FU and Tamoxifen) inhibited cellular viability and Tamoxifen
reduced intracellular levels of ROS whereas 5-FU increased intracellular levels of ROS. In addition,
5-FU and Tamoxifen were found to increase the activity of GST enzyme purified from the