Analysis of a mechanism of Girdin-mediated regulation of cancer cell metabolism

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The previous work from our laboratory characterized the actin-binding protein Girdin as a critical regulator of migration of endothelial cells, cancer cells, and neuroblasts, which depends on extracellular cues including growth factor stimulation. We also previously found that Girdin also interacts with amino acids transporters to regulate amino acids-induced mTORC1 activation. To further investigate the role of Girdin in cancer metabolism, we employed affinity column chromatography to isolate Girdin-interacting proteins, and identified Pyruvate Kinase M2 (PKM2), a key enzyme that regulates the Warburg effect that is necessary for tumor growth, as a candidate. The interaction of PKM2 with Girdin was confirmed by co-immunoprecipitation (co-IP), western blot analysis and immunofluorescence. Next, to check on the role of Girdin in cancer metabolism, we evaluated the effect of Girdin depletion on ATP and lactate production, and glucose consumption by commercially available biochemical kits. We also investigated the role of Girdin in PKM2 Y105 phosphorylation, which is highly related to PKM2 enzyme activity. We also analyzed the role of Girdin in lung cancer progression through IHC, where we found that the expression of Girdin is correlated with the expression of PKM2 in lung cancer tissue. In summary, the data we got from the study revealed the role of Girdin in cancer metabolism and cancer progression, and showed the possibility that Girdin is involved in the modulation of chemotherapy effect through affecting aerobic glycolysis.