[Recombinant methioninase regulates PI3K/Akt/Glut-1 pathway and inhibits aerobic glycolysis to promote apoptosis of gastric cancer cells].

OBJECTIVE: To investigate the molecular mechanism of recombinant methioninase (rMETase) in promoting apoptosis of gastric cancer cells.
METHODS: Gastric cancer SGC-7901 cells were treated with rMETase (final concentration of 1.25 and 2.50 mmmol/L) for 72 h, and the changes in the cell viability were detected using CCK-8 method and the cell morphology changes were observed under an inverted microscope. Plate colony formation assay was used to evaluate colony formation ability of the cells, and flow cytometry was performed to analyze the changes in cell apoptosis and cell cycles. Glucose and lactate levels in the culture medium were determined using a colorimetric method and ATP concentration was detected using a fluorescence microplate reader; Western blotting was used to assess the effect of rMETase on PI3K/Akt pathway, glucose transporter-1 (GLUT-1), glycolysis- related proteins and apoptotic proteins in SGC-7901 cells.
RESULTS: rMETase significantly inhibited the proliferation and clonal formation, promoted cell apoptosis, and induced cell cycle arrest in S phase in SGC-7901 cells (P < 0.05). With the increase of rMETase concentration, the cells showed obviously decreased glucose intake accompanied by decreased glycolysis and ATP concentration (P < 0.001). The results of Western blotting showed that the expressions of PI3K, p-Akt/t-Akt, GLUT-1, and the key glycolytic enzymes HK2, PFKM, LDHA, antiapoptosis protein Bcl-2 were all downregulated and the pro-apoptotic proteins Bax and caspase-3 were up-regulated in response to rMETase treatment in SGC-7901 cells (P < 0.01).
CONCLUSIONS: rMETase can inhibit aerobic glycolysis, induce apoptosis and inhibit the proliferation of SGC-7901 cells by inhibiting the activity of PI3K/Akt/GLUT-1 pathway, suggesting its potential as a therapeutic agent for gastric cancer.