A common approach for understanding how drugs induce their therapeutic effects is to identify the genetic determinants of drug sensitivity. Because 'chemo-genetic profiles' are performed in a pooled format, inference of gene function is subject to several confounding influences related to variation in growth rates between clones. In this study, we developed Method for Evaluating Death Using a Simulation-assisted Approach (MEDUSA), which uses time-resolved measurements, along with model-driven constraints, to reveal the combination of growth and death rates that generated the observed drug response. MEDUSA is uniquely effective at identifying death regulatory genes. We apply MEDUSA to characterize DNA damage-induced lethality in the presence and absence of p53. Loss of p53 switches the mechanism of DNA damage-induced death from apoptosis to a non-apoptotic death that requires high respiration. These findings demonstrate the utility of MEDUSA both for determining the genetic dependencies of lethality and for revealing opportunities to potentiate chemo-efficacy in a cancer-specific manner.
© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.

5-fluorouracil (5-FU), a major anti-cancer therapeutic, is believed to function primarily by inhibiting thymidylate synthase, depleting deoxythymidine triphosphate (dTTP), and causing DNA damage. Here, we show that clinical combinations of 5-FU with oxaliplatin or irinotecan show no synergy in human colorectal cancer (CRC) trials and sub-additive killing in CRC cell lines. Using selective 5-FU metabolites, phospho- and ubiquitin proteomics, and primary human CRC organoids, we demonstrate that 5-FU-mediated CRC cell killing primarily involves an RNA damage response during ribosome biogenesis, causing lysosomal degradation of damaged rRNAs and proteasomal degradation of ubiquitinated ribosomal proteins. Tumor types clinically responsive to 5-FU treatment show upregulated rRNA biogenesis while 5-FU clinically non-responsive tumor types do not, instead showing greater sensitivity to 5-FU's DNA damage effects. Finally, we show that treatments upregulating ribosome biogenesis, including KDM2A inhibition, promote RNA-dependent cell killing by 5-FU, demonstrating the potential for combinatorial targeting of this ribosomal RNA damage response for improved cancer therapy.
Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.

To investigate the effect of the kinase inhibitor AT9283 on Burkitt lymphoma (BL) cells and elucidate the underlying mechanisms.
The effect of AT9283 on the proliferation of BL cell lines was tested using the MTT assay. Apoptosis and cell cycle were measured by flow cytometry. The proteins associated with the cell cycle, apoptosis, and the Warburg effect were detected using Western blotting. Alterations in glycolytic metabolism in terms of glucose intake and lactate concentrations were determined by glucose and lactate assays.
The current study utilized the GEPIA, the Human Protein Atlas (HAP) database and immunohistochemistry to conduct analyses, which revealed a high expression of Aurora kinases and Warburg effect-related proteins in malignant B-cell lymphoma tissues. AT9283 significantly inhibited the cell proliferation of BL cells and induced G2/M arrest. Additionally, AT9283 induced apoptosis in BL cells and reversed the Warburg effect by increasing glucose uptake and reducing lactate production. Moreover, the protein expression of hexokinase 2, pyruvate kinase M2, and lactate dehydrogenase A was significantly suppressed by AT9283, possibly through the inhibition of c-Myc and HIF-1α protein expression.
The reversal of the Warburg effect in BL cells and the subsequent inhibition of cell proliferation and induction of apoptosis were observed by targeting Aurora A and Aurora B with AT9283. This finding may present new therapeutic options and targets for BL.
©2023 Jiang et al.

Meiosis is a specialized type of cell division that occurs only in germ cells physiologically. We have previously demonstrated that MYC-associated factor X (MAX) is involved in blocking ectopic and precocious meiotic onsets in embryonic and germline stem cells, respectively, as a central component of the PRC1 subtype PRC1.6. In this study, we investigated the role of the Max gene in germ cells in vivo . Our data revealed that mitotically active germ cell-specific disruption of Max was coupled to meiotic onset in male and female germ cells. However, such Max -null germ cells did not undergo meiotic processes progressively, but were stalled at its relatively early stages and eventually eliminated by apoptosis. Our data also revealed that Max , which is generally known as an obligate heterodimerization partner for MYC and MXD transcription factors, showed high expression in sexually undifferentiated male and female germ cells, but female germ cells exhibited an abrupt decline in its expression at the timing of or immediately prior to physiological meiotic onset. Moreover, computational analyses identified the regulatory region that supported high levels of Max expression in sexually undifferentiated germ cells.

SUMMARY DNA damage can activate apoptotic and non-apoptotic forms of cell death; however, it remains unclear what features dictate which type of cell death is activated. We report that p53 controls the choice between apoptotic and non-apoptotic death following exposure to lethal levels of DNA damage. The canonical response to DNA damage involves p53-dependent activation of cell intrinsic apoptosis, downstream of DNA damage response (DDR) activation. Decades of research suggest that DNA damage does not robustly activate cell death in the absence of p53. In contrast, we find that p53-deficient cells die at high rates following exposure to DNA damage, but exclusively using non-apoptotic types of cell death. Our experimental and computational analyses demonstrate that non-apoptotic death in p53-deficient cells has generally been missed due to use of assays that are either insensitive to cell death, or that specifically measure apoptotic cells. To characterize which subtype of non-apoptotic death is activated by DNA damage in p53-deficient cells, we used functional genetic screening, with an analysis method that enables computational inference of the drug-induced death rate, rather than the relative population size. We find in p53-deficient cells that DNA damage activates a mitochondrial respiration-dependent form of cell death called MPT-driven necrosis. This study reveals how the dual functions of p53 in regulating mitochondrial activity and the DDR combine to facilitate choice between apoptotic and non-apoptotic death following DNA damage.