Tumors dependent on the Hippo/YAP signaling pathway often show increased resistance to therapy and an aggressive course. Neighboring studies in the archive focus on medical imaging, image segmentation, and weak supervision of learning, which highlights the uniqueness of this work: it shifts the focus from diagnosis to functional testing of a drug's action in a living genetic model. It was previously known that MitoC inhibits TrxR and kills cancer cells in culture, but its effect in the context of a whole organism and a specific oncogenic driver remained untested.
The authors used an intestinal tumor model in adult Drosophila melanogaster flies: a constitutively active form of Yorkie (the YAP homolog) was induced in intestinal stem cells (ISCs) using the GAL4/GAL80ts system. Flies were treated with MitoC at concentrations of 10-40 µM for 48 hours. Tumor burden was assessed by the volume of GFP-positive cells, proliferation by phospho-histone H3, and apoptosis by cleaved caspase Dcp1. ROS levels were measured with the fluorescent probe CellROX, mitochondrial membrane potential with TMRE, and mitochondrial morphology with MitoView plus 3D reconstruction. In addition, the authors performed molecular docking and 500-ns molecular dynamics of the MitoC complex with Drosophila and mammalian TrxR, as well as untargeted metabolomic analysis.
MitoC reduced tumor burden in a dose-dependent manner: 30 µM shrank the volume of GFP+ cells to a level comparable to 24-hour induction, that is, roughly by half compared with the 48-hour control. Tumor cell proliferation fell (the number of pH3+ cells decreased), while apoptosis rose (the number of cDcp1+ puncta increased). ROS levels in tumor cells rose sharply, comparable to the effect of paraquat, and the antioxidant response was activated: expression of the cnc gene (the Nrf2 homolog) increased, while keap1 decreased. Mitochondrial membrane potential dropped, and expression of electron transport chain genes was suppressed, yet mitochondrial morphology did not change. Metabolomic analysis revealed 51 altered metabolites: acylcarnitines, succinate, malate, methionine sulfoxide, and purine metabolites accumulated, while glycerophosphocholine decreased. At the organism level, MitoC reduced abdominal bloating and extended median survival from 28 to 36 days.
This work differs from neighboring studies in that it does not stop at observation or diagnosis but provides a direct functional test of a therapeutic hypothesis in a living model with a clear genetic driver. It shows that TrxR inhibition can be an effective strategy against tumors with hyperactivation of the Hippo pathway, and that Drosophila is suitable for screening redox-modulating drugs. Importantly, the effect of MitoC does not depend on selenocysteine, which is characteristic of mammalian TrxR, and this broadens the range of potential targets.
The topic could develop toward studying the systemic effects of redox therapy: how changes in tumor cell metabolism affect other organs and cachexia. It would be interesting to investigate in detail the mechanism of compensatory activation of antioxidant pathways and the possibility of combining MitoC with inhibitors of these pathways to enhance the effect. It would also be promising to test MitoC in models with other oncogenic drivers and in mouse models of intestinal cancer.
The results could influence the development of anticancer drugs targeting mitochondrial redox balance, and the use of Drosophila as a platform for preclinical screening.
Conduct enzymatic studies of Drosophila TrxR to confirm direct inhibition, examine the activity of antioxidant enzymes (not just their transcripts) after MitoC treatment, and investigate the inter-organ signals responsible for the improvement of systemic symptoms.
The work addresses a key problem in oncology: how to use oxidative stress to selectively destroy tumor cells without damaging normal tissues. It also links metabolic reprogramming to redox homeostasis in the context of Hippo-dependent tumors, which remains a poorly studied area.
Drosophila thioredoxin reductase uses cysteine instead of selenocysteine, as in mammals, but retains high catalytic activity. This makes the fly enzyme a convenient model for testing inhibitors that do not depend on selenium.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.