In the end, we looked at the effectiveness of PHGDH inhibitors towards the 4T1 cancers which have IDH2-large levels
In view of your own part from PHGDH and PSAT1 for the airg apk mediating IDH2-established metabolic remodeling, we examined the fresh new proteomic outcomes of such relationships. Healthy protein working in metabolic process, interpretation machines, ribosome biogenesis, splicing, and you can telephone migration had been upregulated because of the IDH2 and you may downregulated which have PHGDH and you will PSAT1 knockouts (Second Fig. S8A and you will S8B; Additional Table Ssix). Biggest metabolic necessary protein provided brand new cytochrome members of the family (CYCS, CYC1, CYB5R1), glutamine uptake and you will glutamate kcalorie burning (SLC1A5 and you will GLUD1), solute supplier transporters (SLC25A1 – CIC, citrate/malate transporter, SLC25A11 – OGC, alpha-ketoglutarate/malate transporter and you will SLC25A5 – ATP/ADP transporter), lipid kcalorie burning (SOAT1, TSPO, ACAD9), and you will glycolytic necessary protein (HK1 and you may PKM). I speculated one to a decrease in the latest metabolic interest abreast of PHGDH and you can PSAT1 knockout you will sign up to the fresh new redox imbalance and you can sensitize brand new muscle so you’re able to oxidative destroy. S8C). For this reason, PHGDH and you may PSAT1 enjoy a significant part in getting anabolic present out-of nucleotides, lipids, and proteins into the structure with a high IDH2, and you can service mobile be concerned resistance (Supplementary Fig. S8D).
Actually, the loss of PHGDH and you will PSAT1 induced susceptability to oxidative destroy while the mobile emergency try less than the latest manage tissues (Supplementary Fig
Aiming to translate the SDL interaction to cancer therapy, we examined the sensitivity of IDH2-high cells to PHGDH inhibitors, in vitro and in vivo. Cells with stable IDH2 overexpression and IDH2 knockout were treated with PHGDH inhibitor (NCT-502) for 48 hours in RPMI medium without serine and glycine. Initial metabolic analysis showed that PHGDH inhibition reduced serine (m3) and glycine (m2) labeling from 13 C6-glucose (Supplementary Fig. S8E-S8H). The dose range of NCT-502 was calibrated for each cell line (HCC38 and HCC1143), due to basal differences in cell line sensitivities. In agreement with the SDL prediction, HCC38 cells with IDH2 overexpression were more sensitive to NCT-502 treatment (IC50: 0.05 ?mol/L) compared with the control cells with low IDH2 expression (IC50: 0.18 ?mol/L; Fig. 7A). Control knockout HCC1143 cells with high basal IDH2 were more sensitive to NCT-502 (IC50: 0.5 ?mol/L) compared with the cells with IDH2 knockout (IC50: 2.2 ?mol/L; Fig. 7B). Next, we examined the efficacy of the PHGDH inhibitor in an in vivo murine model, 4T1 TN breast cancer cells, with high basal IDH2 and PHGDH expression. We knocked down IDH2 using stable shRNA constructs and the knockdown was confirmed by Western blotting (Supplementary Fig. S8I). 4T1 cells exhibited reduced cell proliferation and colony formation upon IDH2 knockdown (Fig. 7C and D). In addition, DMKG supplement to the murine 4T1 cells with IDH2 knockdown rescued the reduced cell proliferation and colony formation (Fig. 7C and D). 4T1 cells with high and low IDH2 expression were injected orthotopically to mammary glands of female mice and treated with the PHGDH inhibitor NCT-503 (Supplementary Fig. S8J), which is reported to have increased solubility in vivo (42). Analysis of tumor growth revealed that 4T1 tumors with high IDH2 showed enhanced tumor growth with larger tumor size and weight compared with the tumors with low IDH2 (Fig. 7E–G; Supplementary Fig. S8K). In addition, only the IDH2-high tumors treated with NCT-503 showed reduced tumor size and weight compared with the IDH2-high tumors treated with vehicle (Fig. 7E–G). IDH2-low tumors treated with either NCT-503 or vehicle were not affected by the treatment. Altogether, pharmacologic inhibition of serine biosynthesis using PHGDH inhibitor affects only the growth of IDH2-high cells. This in vivo validation demonstrated the SDL interaction between PHGDH and IDH2 and strengthened the metabolic alterations and the in vitro protumorigenic phenotypes. Our study emphasizes PHGDH inhibition as a promising therapeutic approach for TN breast tumors with high IDH2.