Post-translation modification of the 6-pfosphofructo-1-kinase (PFK1) enzyme is supposedly responsible for deregulated glycolysis in cancer cells. We tested the effect of two inhibitors in different concentrations on PFK-P and on the production of lactate in the tumorigenic cell lines Caco-2, MDA-MB-231, MCF-7, Colo829 and in the non-tumorigenic cell line MCF-10A. We also used non-tumorigenic HEK293-T-Rex cells transfected with the native human gene for the muscular type of PFK-M, cells transfected with a short fragment of PFK1 enzyme and cells without additional genes. The inhibitors did not have any effect on the production of lactate in the MCF-10A cells, but a dependency between the concentration of inhibitors and the production of lactate was observed in the MCF-7 cells. The two inhibitors were selected to inhibit primarly PFK-M and PFK-P. We determined the concentration of certain glycolysis metabolites using mass spectrometry. In the cells treated with inhibitor 3 a higher concentration of metabolites before the PFK1 level was observed and a lower concentration of metabolites after that level in respect to the un-treated cells. These results suggest PFK1 enzymes must be the target for inhibitors. The inhibitors were not citotoxic for any of the used cell lines. After the experiment, we discovered that some of the used media were not suitable for our experiment because their composition was not similar to human serum and they did not promote deregulated glycolysis.
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