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Cytotoxicity of glucose analogues in V79 multicell spheroids
Abstract:
2-Deoxy-D-glucose (2DG) and 5-thio-D-glucose (5TG) are glucose antimetabolites that are known to be selectively toxic to hypoxic cells grown as single cells or as monolayer cultures. These analogues were toxic to Chinese hamster V79 cells grown as multicell spheroids even under aerobic conditions. When spheroids, 500- to 600-microns diameter, were exposed to 7.5 mM of these chemicals for 3 days, the number of clonogenic cells per spheroid dropped to 50% for 5-thio-D-glucose and 20% for 2-deoxy-D-glucose, relative to control values. Survivals were reduced to less than 1% when the experiment was repeated in glucose-free medium. Scanning electron photomicrographs of spheroids treated with 7.5 mM of either analogue showed extensive damage to the outer cells. The cell killing observed was much more than could be predicted on the basis of the hypoxic fraction known to be present in these spheroids. The crowded tumor-like environment may make the cells vulnerable to the cytotoxic action of glucose analogues and other glycolytic inhibitors.
Insights
Glucose analogues 2-deoxy-D-glucose (2DG) and 5-thio-D-glucose (5TG) show significant toxicity to Chinese hamster V79 cells in spheroids, even under aerobic conditions. This suggests tumor microenvironments enhance sensitivity to glycolytic inhibitors.
Area of Science:
- Biochemistry
- Cell Biology
- Cancer Research
Background:
- Glucose antimetabolites 2-deoxy-D-glucose (2DG) and 5-thio-D-glucose (5TG) exhibit selective toxicity towards hypoxic cells in vitro.
- Previous studies indicate their efficacy in single-cell or monolayer cultures.
Purpose of the Study:
- To investigate the toxicity of 2DG and 5TG on Chinese hamster V79 cells grown as multicellular spheroids.
- To assess the impact of the tumor-like microenvironment on the efficacy of these glucose analogues.
Main Methods:
- Exposure of V79 multicellular spheroids (500-600 microns) to 7.5 mM of 2DG or 5TG for 3 days.
- Assessment of clonogenic cell survival and comparison with control groups.
- Repetition of experiments in glucose-free medium.
- Analysis of spheroid morphology using scanning electron microscopy.
Main Results:
- Significant reduction in clonogenic cell survival: 50% for 5TG and 20% for 2DG compared to controls.
- Survival reduced to less than 1% in glucose-free medium.
- Scanning electron microscopy revealed extensive damage to outer spheroid cells.
- Observed cell killing exceeded predictions based on known hypoxic fractions.
Conclusions:
- 2DG and 5TG demonstrate potent cytotoxicity against V79 spheroids, irrespective of oxygen levels.
- The crowded, tumor-like environment of spheroids enhances cellular vulnerability to glucose analogues.
- These findings highlight the potential of glycolytic inhibitors in targeting tumor cells within dense microenvironments.