Figure 1.

Oncogenic IDH1 Arg-132 mutant down-regulates p53. A, genotyping PCR of genomic DNA from IDH1^WT/WT, IDH1^WT/LSL, and IDH1^LSL/LSL MEFs treated with or without Cre recombinase. After administration of Cre five different genotypes, IDH1^WT/WT, IDH1^WT/LSL, IDH1^WT/Mut, IDH1^LSL/LSL, and IDH1^Mut/Mut were obtained. Bands associated with IDH1 R132Q mutant (Mut), wildtype (WT), and LSL alleles are indicated. B, p53 protein levels were dramatically decreased in IDH1^WT/Mut and IDH1^Mut/Mut MEFs. The same cell lines as displayed in A were detected for p53 and IDH1 expression with Western blotting (WB). C, the same cell lines as displayed in B were treated with or without 2.5 μm DOX for 4 h, followed by Western blotting with the antibodies indicated. D and E, IDH1 R132H mutant also inhibits p53 expression in cancerous cell lines U2OS and HCT116. U2OS cells (D) and HCT116 cells (E) were transfected with FLAG-tagged WT IDH1 or its R132H mutant. At 24 h post-transfection cells were treated with or without 2.5 μm DOX for 4 h, followed by detection of the indicated proteins.