Reactive Oxidative Species Sensitivity in Cancer

By Daniel Walocha ‘19

Hydrogen_Peroxide.png

Figure 1. Hydrogen peroxide is a reactive oxygen species byproduct of cellular metabolism used to induce cell death in Dr. Yilmazer’s experiments.

Cancer cells primarily use glycolysis to gain ATP and important intermediates for amino acid biosynthesis via the Warburg effect, even in the presence of readily available oxygen. This highlights a key distinction between cancer and normal cells: normal cells mainly utilize the electron transport chain for their ATP needs, while cancer cells do not. As a result, cancer cells build up a higher concentration of reactive oxidative species (ROS) than normal cells. Dr. Acelya Yilmazer from Ankara University in Turkey exploited this difference in testing the sensitivities of cancer cells to ROS—specifically, the pronounced difference in cancer stem cells (CSCs).

Dr. Yilmazer used A549, G361, and MCF-7 cancer cell lines to represent human lung carcinoma, human melanoma, and human breast cancer, respectively, as models for cancer ROS sensitivity. Human primary melanocytes were used as a control, and all four cell types were incubated with hydrogen peroxide concentrations of increasing degree (0.1, 0.5, and 1 mM) for 25 hours. The cell death was measured with an initial MTT assay and AnnexinV-FITC/PI incubation. CSC death was then tested using flow cytometry analysis using CSC markers. The experiments were conducted in triplicates and statistical analysis of variance was performed for significance.

The MTT assay showed a stepwise decrease in cell viability from 0.1 to 1 mM of hydrogen peroxide. A549 and G361 cells exhibited a decreased viability of 50% in the 1 mM concentration while MCF-7 cells exhibited a 40% viability at all concentrations. Cancer cells were seen to exhibit higher apoptotic activity in response to hydrogen peroxide treatment than the human primary melanocytes. The CSC flow cytometry analysis showed a diverse response to ROS.

The experiments confirm a possible therapeutic target for cancer treatment, capitalizing on ROS sensitivities. Further experimentation would be needed to further illuminate the CSC response and distinguish important markers in the cell.

References:

  1. A. Yilmazer, Cancer cell lines involving cancer stem cell populations respond to oxidative stress. Biotechnology Reports 17, 24-30 (2018). doi: 10.1016/j.btre.2017.11.004.
  2. Image retrieved from: https://commons.wikimedia.org/wiki/File:Hydrogen-peroxide-3D-balls.png
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