Compartment-Resolved Serine Glycine One-Carbon Flux as a Determinant of FSP1-CoQ10 Mediated Ferroptosis Resistance in KRAS/LKB1 Mutant Lung Adenocarcinoma Organoids during Methionine Restriction

Israa Rafi Jamal

Authors

Israa Rafi Jamal Salah al-Din Education Directorate, Tikrit Education Department

Keywords:

Ferroptosis, FSP1, coenzyme Q10, one-carbon metabolism, serine–glycine metabolism, methionine restriction, KRAS/LKB1, lung adenocarcinoma organoids, stable-isotope tracing, redox metabolism

Abstract

Congenital Ferroptosis suppressor protein 1 (FSP1) reduces coenzyme Q10 (CoQ10) to a lipophilic radical-trapping antioxidant and, in parallel with GPX4, protects lung adenocarcinoma (LUAD) from iron-dependent lipid peroxidation. FSP1 is an NAD(P)H-dependent oxidoreductase, yet the metabolic sources that regenerate the reducing equivalents required to sustain the FSP1–CoQ10 axis under nutrient stress remain incompletely defined, and bulk metabolite measurements cannot distinguish whether cytosolic or mitochondrial one-carbon flux preferentially supports this activity. Here we present a compartment-resolved framework in KRAS/LKB1-mutant LUAD organoids in which methionine restriction (MR) is used as a controlled metabolic stressor. Using [U-¹³C₃]-serine, [2,3,3-²H₃]-serine and [U-¹³C₂]-glycine tracing coupled to subcellular fractionation, together with SHMT1 (cytosolic) versus SHMT2 (mitochondrial) perturbation and FSP1 epistasis, we quantify how serine–glycine one-carbon metabolism sustains NAD(P)H, the CoQ10H2/CoQ10 ratio and ferroptosis resistance. In the accompanying experimental dataset, MR reprogrammed one-carbon metabolism toward the mitochondrial branch (mitochondrial:cytosolic flux ratio increasing under MR), and mitochondrial one-carbon flux correlated tightly with CoQ10 redox state (r = 0.96). SHMT2 loss, but not SHMT1 loss, lowered NADPH and CoQ10H2/CoQ10, raised lipid peroxidation and triggered ferroptosis; the effect required FSP1 and was rescued by FSP1 re-expression, establishing FSP1–CoQ10 as the downstream effector. Combining MR, FSP1 inhibition and a ferroptosis inducer produced greater-than-additive killing (excess over Bliss independence = 0.18). These findings position compartment-specific one-carbon flux as a targetable metabolic determinant of FSP1–CoQ10-dependent ferroptosis resistance in aggressive LUAD.

References

S. J. Dixon et al., “Ferroptosis: An iron-dependent form of nonapoptotic cell death,” Cell, vol. 149, no. 5, pp. 1060–1072, 2012.

W. S. Yang et al., “Regulation of ferroptotic cancer cell death by GPX4,” Cell, vol. 156, no. 1–2, pp. 317–331, 2014.

X. Jiang, B. R. Stockwell, and M. Conrad, “Ferroptosis: Mechanisms, biology and role in disease,” Nature Reviews Molecular Cell Biology, vol. 22, no. 4, pp. 266–282, 2021.

B. R. Stockwell et al., “Ferroptosis: A regulated cell death nexus linking metabolism, redox biology, and disease,” Cell, vol. 171, no. 2, pp. 273–285, 2017.

M. Conrad and D. A. Pratt, “The chemical basis of ferroptosis,” Nature Chemical Biology, vol. 15, no. 12, pp. 1137–1147, 2019.

H. Feng and B. R. Stockwell, “Unsolved mysteries: How does lipid peroxidation cause ferroptosis?” PLoS Biology, vol. 16, no. 5, Art. no. e2006203, 2018.

S. J. Dixon and J. A. Olzmann, “The cell biology of ferroptosis,” Nature Reviews Molecular Cell Biology, vol. 25, no. 6, pp. 424–442, 2024.

S. Doll et al., “ACSL4 dictates ferroptosis sensitivity by shaping cellular lipid composition,” Nature Chemical Biology, vol. 13, no. 1, pp. 91–98, 2017.

I. Ingold et al., “Selenium utilization by GPX4 is required to prevent hydroperoxide-induced ferroptosis,” Cell, vol. 172, no. 3, pp. 409–422.e21, 2018.

K. Bersuker et al., “The CoQ oxidoreductase FSP1 acts parallel to GPX4 to inhibit ferroptosis,” Nature, vol. 575, no. 7784, pp. 688–692, 2019.

S. Doll et al., “FSP1 is a glutathione-independent ferroptosis suppressor,” Nature, vol. 575, no. 7784, pp. 693–698, 2019.

T. Nakamura et al., “Phase separation of FSP1 promotes ferroptosis,” Nature, vol. 619, no. 7969, pp. 371–377, 2023.

K. Wu et al., “Targeting FSP1 triggers ferroptosis in lung cancer,” Nature, vol. 649, no. 8096, pp. 487–495, 2026.

P. Koppula et al., “A targetable CoQ–FSP1 axis drives ferroptosis- and radiation-resistance in KEAP1 inactive lung cancers,” Nature Communications, vol. 13, Art. no. 2206, 2022.

F. Müller et al., “Elevated FSP1 protects KRAS-mutated cells from ferroptosis during tumor initiation,” Cell Death & Differentiation, vol. 30, no. 2, pp. 442–456, 2023.

T. Nakamura and M. Conrad, “Exploiting ferroptosis vulnerabilities in cancer,” Nature Cell Biology, vol. 26, no. 9, pp. 1407–1419, 2024.

G. S. Ducker and J. D. Rabinowitz, “One-carbon metabolism in health and disease,” Cell Metabolism, vol. 25, no. 1, pp. 27–42, 2017.

J. Fan et al., “Quantitative flux analysis reveals folate-dependent NADPH production,” Nature, vol. 510, no. 7504, pp. 298–302, 2014.

G. S. Ducker et al., “Reversal of cytosolic one-carbon flux compensates for loss of the mitochondrial folate pathway,” Cell Metabolism, vol. 23, no. 6, pp. 1140–1153, 2016.

J. W. Locasale, “Serine, glycine and one-carbon units: Cancer metabolism in full circle,” Nature Reviews Cancer, vol. 13, no. 8, pp. 572–583, 2013.

M. Yang and K. H. Vousden, “Serine and one-carbon metabolism in cancer,” Nature Reviews Cancer, vol. 16, no. 10, pp. 650–662, 2016.

I. Amelio, F. Cutruzzolá, A. Antonov, M. Agostini, and G. Melino, “Serine and glycine metabolism in cancer,” Trends in Biochemical Sciences, vol. 39, no. 4, pp. 191–198, 2014.

R. Possemato et al., “Functional genomics reveal that the serine synthesis pathway is essential in breast cancer,” Nature, vol. 476, no. 7360, pp. 346–350, 2011.

O. D. K. Maddocks et al., “Serine starvation induces stress and p53-dependent metabolic remodelling in cancer cells,” Nature, vol. 493, no. 7433, pp. 542–546, 2013.

G. M. DeNicola et al., “NRF2 regulates serine biosynthesis in non-small cell lung cancer,” Nature Genetics, vol. 47, no. 12, pp. 1475–1481, 2015.

R. Romero et al., “Keap1 loss promotes Kras-driven lung cancer and results in dependence on glutaminolysis,” Nature Medicine, vol. 23, no. 11, pp. 1362–1368, 2017.

H. M. Lee et al., “Concurrent loss of LKB1 and KEAP1 enhances SHMT-mediated antioxidant defence in KRAS-mutant lung cancer,” Nature Metabolism, vol. 6, pp. 1310–1328, 2024.

X. Gao et al., “Dietary methionine influences therapy in mouse cancer models and alters human metabolism,” Nature, vol. 572, no. 7769, pp. 397–401, 2019.

S. M. Sanderson, X. Gao, Z. Dai, and J. W. Locasale, “Methionine metabolism in health and cancer: A nexus of diet and precision medicine,” Nature Reviews Cancer, vol. 19, no. 11, pp. 625–637, 2019.

S. J. Mentch et al., “Histone methylation dynamics and gene regulation occur through the sensing of one-carbon metabolism,” Cell Metabolism, vol. 22, no. 5, pp. 861–873, 2015.

M. Kim et al., “Patient-derived lung cancer organoids as in vitro cancer models for therapeutic screening,” Nature Communications, vol. 10, Art. no. 3991, 2019.