Cancer stem cells synthesize proline to attenuate oxidative stress
Weichi Wu, Po Zhang, Donghai Wang, Xujia Wu, Qiulian Wu, Daqi Li, Tengfei Huang, Rui Wang, Huan Li, Hailong Mi, Suchet Taori, Fanen Yuan, Tingting Duan, Zhiye Chen, Huairui Yuan, Jeremy N. Rich
Weichi Wu, Po Zhang, Donghai Wang, Xujia Wu, Qiulian Wu, Daqi Li, Tengfei Huang, Rui Wang, Huan Li, Hailong Mi, Suchet Taori, Fanen Yuan, Tingting Duan, Zhiye Chen, Huairui Yuan, Jeremy N. Rich
View: Text | PDF
Research Article Cell biology Metabolism Oncology

Cancer stem cells synthesize proline to attenuate oxidative stress

Abstract

Cancers reprogram their metabolism to provide anabolic needs without driving excessive oxidative stress. Attention has focused on glucose metabolism, yet amino acid synthesis and degradation also promote tumor cell states and growth. Here, we assessed amino acids that maintain cancer stem cells in glioblastoma and found increased proline levels relative to differentiated tumor progeny through increased proline synthesis. Cancer stem cells preferentially expressed the signaling molecule FAM3C induced by the stem cell transcription factor SOX2 to drive expression of proline synthesis enzymes. FAM3C classically mediated cellular responses as a secreted protein but gained intracellular functions in cancer stem cells through binding the histone reader spindlin 1 (SPIN1), thereby preventing its lysosomal degradation, assisting its nuclear localization, and promoting epigenetic regulation of proline synthesis. Proline synthesis depleted ROS, and genetic targeting of FAM3C attenuated ROS scavenging, whereas SPIN1 OE restored ROS levels. Molecular docking identified tucatinib as a brain-penetrant pharmacologic disruptor of FAM3C-SPIN1 interactions, promoting SPIN1 degradation and reducing intracellular proline levels. Thus, cancer stem cells induced a favorable metabolic state through proline synthesis and ROS depletion, revealing potential therapeutic dependencies.

Authors

Weichi Wu, Po Zhang, Donghai Wang, Xujia Wu, Qiulian Wu, Daqi Li, Tengfei Huang, Rui Wang, Huan Li, Hailong Mi, Suchet Taori, Fanen Yuan, Tingting Duan, Zhiye Chen, Huairui Yuan, Jeremy N. Rich

×

Figure 8

Tucatinib disrupts the interaction between FAM3C and SPIN1.

Options: View larger image (or click on image) Download as PowerPoint
Tucatinib disrupts the interaction between FAM3C and SPIN1. (A) Drug scr...
(A) Drug screening strategy based on the binding interface between FAM3C and SPIN1. (B) The 10 compounds with the highest docking scores identified on the basis of the drug screening strategy in A. Docking scores below –6 were considered indicative of effective binding. (C) Therapeutic efficacy prediction of drugs for FAM3C (Methods). The blue dot shows the top resistance drug, and red dots show the top sensitive drugs for high FAM3C expression. Two-tailed Pearson correlation was used for statistical analysis. (D and E) Immunoblot analysis of FAM3C IP was performed on GSC23 (D) and GSC387 (E) cells overexpressing Flag-FAM3C after treatment with gradually increasing concentrations of tucatinib (0 μM, 2–5 μM, 2–4 μM) for 6 hours. (F and G) Immunoblot analysis (F) and thermal shift curves (G) of FAM3C from a cellular thermal shift assay (CETSA) in HEK293T cells pretreated with 2–5 μM tucatinib (n = 3 independent experiments). Data are presented as the mean ± SD. CETSA, cellular thermal shift assay. (H) SPR was used to analyze binding affinities and kinetic parameters between FAM3C and tucatinib.