Fundamentally, i examined the power of PHGDH inhibitors with the 4T1 tumors which have IDH2-higher profile
Because of one’s part away from PHGDH and PSAT1 for the mediating IDH2-built metabolic remodeling, i examined the fresh new proteomic negative effects of this type of connections. Proteins in kcalorie burning, translation machinery, ribosome biogenesis, splicing, and you will mobile migration was in fact upregulated because of the IDH2 and you may downregulated that have PHGDH and you will PSAT1 knockouts (Second Fig. S8A and you may S8B; Additional Desk Ssix). Significant metabolic necessary protein included this new cytochrome members of the family (CYCS, CYC1, CYB5R1), glutamine use and you can glutamate metabolic rate (SLC1A5 and GLUD1), solute provider transporters (SLC25A1 – CIC, citrate/malate transporter, SLC25A11 – OGC, alpha-ketoglutarate/malate transporter and you may SLC25A5 – ATP/ADP transporter), lipid metabolic rate (SOAT1, TSPO, ACAD9), and you can glycolytic protein (HK1 and you may PKM). We speculated one to a decrease in the newest metabolic interest up on PHGDH and you may PSAT1 knockout you’ll contribute to the brand new redox instability and you can sensitize the fresh muscle so you’re able to oxidative destroy. S8C). For this reason, PHGDH and you may PSAT1 play an essential part from inside the bringing anabolic provide out-of nucleotides, lipids, and amino acids from inside the cells with high IDH2, and you will support cellular fret opposition (Secondary Fig. S8D).
Indeed, the increased loss of PHGDH and PSAT1 created vulnerability to help you oxidative ruin and telephone emergency was lower than the manage tissue (Additional 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-fifty2) 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.