Colorectal cancer (CRC) exhibits significant diversity and heterogeneity, posing a requirement for novel therapeutic targets. Polysulfides are associated with CRC progression and immune evasion, but t Show more
Colorectal cancer (CRC) exhibits significant diversity and heterogeneity, posing a requirement for novel therapeutic targets. Polysulfides are associated with CRC progression and immune evasion, but the underlying mechanisms are not fully understood. Sulfide: quinone oxidoreductase (SQR), a mitochondrial flavoprotein, catalyzes hydrogen sulfide (H2S) oxidation and polysulfides production. Herein, we explored its role in CRC pathogenesis and its potential as a therapeutic target. Our findings revealed that SQR knockout disrupted polysulfides homeostasis, diminished mitochondrial function, impaired cell proliferation, and triggered early apoptosis in HCT116 CRC cells. Moreover, the SQR knockout led to markedly reduced tumor sizes in mice models of colon xenografts. Although the transcription of glycolytic genes remained largely unchanged, metabolomic analysis demonstrated a reprogramming of glycolysis at the fructose-1,6-bisphosphate degradation step, catalyzed by aldolase A (ALDOA). Both Western blot analysis and enzymatic assays confirmed the decrease in ALDOA levels and activity. In conclusion, the study establishes the critical role of SQR in mitochondrial function and metabolic regulation in CRC, with its knockout leading to metabolic reprogramming and diminished tumor growth in HCT116 tumor xenografts. These insights lay a foundation for the development of SQR-targeted therapies for CRC. Show less
Academic Editor: Dooil Jeoung Received: 5 November 2025 Revised: 24 November 2025 Accepted: 26 November 2025 Published: 28 November 2025 Citation: Lee, J.; Roh, J.-L. Dihydroorotate Dehydrogenase in M Show more
Academic Editor: Dooil Jeoung Received: 5 November 2025 Revised: 24 November 2025 Accepted: 26 November 2025 Published: 28 November 2025 Citation: Lee, J.; Roh, J.-L. Dihydroorotate Dehydrogenase in Mitochondrial Ferroptosis and Cancer Therapy. Cells 2025, 14, 1889. https://doi.org/10.3390/ cells14231889 Show less
Cytochrome c binds to cardiolipin (CL) on the inner mitochondrial membrane during the initial stages of apoptosis where it oxidizes CL, promoting its release into the cytoplasm where it initiates apop Show more
Cytochrome c binds to cardiolipin (CL) on the inner mitochondrial membrane during the initial stages of apoptosis where it oxidizes CL, promoting its release into the cytoplasm where it initiates apoptosis. Previous work has identified interaction sites on cytochrome c involved in the cytochrome c-CL interaction. The contributions of the lysines attributed to site A, the anionic site, are studied here to elucidate the relative importance of each for electrostatic interaction of cytochrome c with CL at pH 8, conditions where site A is dominant. A set of single, double, and quadruple lysine to alanine variants of yeast iso-1-cytochrome c, at sequence positions 72, 73, 86, and 87, show that all contribute to the site A-mediated interaction with CL. All variants experience two sequential structural rearrangements as the lipid to protein ratio (LPR) increases. At a low LPR near 10, all variants undergo a small heme-centered structural change detected by Soret circular dichroism. At higher LPRs ranging from 22 to 34, all variants partially unfold as detected by Trp59 emission. The robustness of the mechanism of interaction to sequential neutralization of the four lysines assigned to site A demonstrates that site A is more extensive than previously supposed. The nature of both structural rearrangements also depends on which lysines constitute site A. The peroxidase activity of cytochrome c in the early stages of apoptosis depends on the nature of structural rearrangement near the heme. Thus, the lysines that comprise site A may have evolved to optimize the peroxidase signaling switch. Show less
Significance: Oxidative stress is thought to account for aberrant redox homeostasis and contribute to aging and disease. However, more often than not, administration of antioxidants is ineffective, su Show more
Significance: Oxidative stress is thought to account for aberrant redox homeostasis and contribute to aging and disease. However, more often than not, administration of antioxidants is ineffective, suggesting that our current understanding of the underlying regulatory processes is incomplete. Recent Advances: Similar to reactive oxygen species and reactive nitrogen species, reactive sulfur species are now emerging as important signaling molecules, targeting regulatory cysteine redox switches in proteins, affecting gene regulation, ion transport, intermediary metabolism, and mitochondrial function. To rationalize the Show less
The effect of aging and treatment with acetyl-L-carnitine on the activity of cytochrome oxidase and adenine nucleotide translocase in rat heart mitochondria was studied. It was found that the activity Show more
The effect of aging and treatment with acetyl-L-carnitine on the activity of cytochrome oxidase and adenine nucleotide translocase in rat heart mitochondria was studied. It was found that the activity of both these mitochondrial protein systems was reduced (by around 30%) in aged animals. Treatment of aged rats with acetyl-L-carnitine almost completely reversed this effect. Changes in the mitochondrial cardiolipin content appear to be responsible for these effects of acetyl-L-carnitine. Show less