Figure 4.

Metformin blocks MYC protein synthesis in glucose‐free media. (A,B) Metformin‐induced MYC reduction is neither rescued by the proteasome inhibitor MG132, nor accelerated by the protein synthesis inhibitor CHX in HCT116 cells (A) and in HT29 cells (B). In A and B, cells were treated with metformin for 24 h (2 mm), in the presence or absence of MG132 (10 μM). (C) Metformin does not enhance the MYC phosphorylation at threonine 58. (D) Metformin reduces the overexpressed MYC protein in HT29 cells established with lentiviral MYC plasmid lacking 5′UTR and 3′UTR. (E) Metformin reduces MYC protein in COLO320 cells that express high level of endogenous MYC due to genomic amplification.