bims-stacyt 2025-09-21 papers

bioRxiv. 2025 Sep 08. pii: 2025.09.03.674106. [Epub ahead of print]

MondoA mediates transcriptional coordination between the MYC network and the integrated stress response in pancreatic ductal adenocarcinoma.

Erin L Ramsey, Stephanie Dobersch, Brian Freie, Nan Hyung Hong, Xiaoying Wu, Sita Kugel, Robert N Eisenman, Patrick A Carroll.

MYC amplification contributes to poor survival and outcome in pancreatic ductal adenocarcinoma (PDAC). Here we show that in PDAC cell lines with amplified MYC, MondoA is required for viability, facilitating proliferation while suppressing apoptosis in vitro and in vivo . Transcriptional and genomic profiling demonstrates that loss of MondoA leads to altered expression of direct MondoA targets as well as MYC target genes and is accompanied by shifts in genomic occupancy of MYC, MNT, and the MondoA paralog ChREBP. This altered genomic binding by MYC network members is associated with transcriptional perturbation of multiple metabolic and stress pathways, as well as global changes in N6-methyladenosine modification (m 6 A) of mRNA. MondoA inhibition disrupts coordination between MYC network members and the Integrated Stress Response (ISR), resulting in decreased translation of ATF4 mRNA, discordant gene regulation of shared targets of MYC and ATF4 and, ultimately, apoptosis. Re-establishing ATF4 protein expression rescues the diminished viability due to loss of MondoA expression or activity, providing direct evidence of a link between deregulated MYC and the transcriptional machinery of the ISR. Lastly, we find that small-molecule inhibition of MondoA is lethal in a subset of PDAC cell lines, including patient-derived organoids, suggesting that the ability to target MYC via chemical inhibition of MondoA transcriptional activity may have broad efficacy.
Significance Statement: This report investigates mechanisms underlying the dependence of MYC-amplified pancreatic cancer cells on the MYC network member MondoA which, as a heterodimer with MLX, is a nutrient-sensing transcription factor. We show this dependency is linked to genomic crosstalk between MYC, components of the proximal MYC network, and the master regulator of the integrated stress response, ATF4. Moreover, we find that small molecule inhibitors of MondoA-MLX transcriptional activity abrogate survival of MYC-amplified PDAC lines and patient derived organoids. The significance of this work relates to its focus on a unique vulnerability intrinsic to MYC, an oncogenic driver associated with a wide range of cancers, which is considered to be "undruggable".

DOI: https://doi.org/10.1101/2025.09.03.674106

Cancer Lett. 2025 Sep 11. pii: S0304-3835(25)00608-1. [Epub ahead of print]633 218038

Lactate metabolic checkpoint in immuno-oncology: mechanisms and therapeutic implications.

Zhe Wang, Ziyan Gu, Wendi Mo, Haijun Zhang.

Immuno-Oncology has transformed cancer therapeutics, yet its clinical efficacy remains limited by the immunosuppressive tumor microenvironment (TME). Once considered merely a metabolic byproduct of glycolysis, lactate is now recognized as a critical regulator of immune TME through both direct metabolic effects and its derivative modification, histone lysine lactylation (Kla). Within the TME, lactate and Kla reprogram signaling pathways that impair immune function, thereby facilitating tumor immune escape. This review synthesizes emerging evidence positioning lactate metabolism and histone Kla as pivotal immunosuppressive modulators within the TME. Tumor-derived lactate, produced through the Warburg effect, acidifies the TME and disrupts immune cell function via two interconnected mechanisms: direct metabolic interference and epigenetic reprogramming via Kla. Histone Kla represents a novel post-translational modification that drives immunosuppressive signaling in immune cells, serving as a prognostic biomarker across multiple cancers. Moreover, we highlight therapeutic strategies targeting lactate metabolism, which show considerable promise in overcoming the current limitations of immunotherapy and enhancing its clinical efficacy.

Keywords: Immunotherapy; Lactate; Lactylation; Tumor microenvironment

DOI: https://doi.org/10.1016/j.canlet.2025.218038

PLoS Biol. 2025 Sep 16. 23(9): e3003364

Hexokinase 2 is an RNA-binding protein that regulates mRNA translation independently of glycolysis and induces melanoma cell proliferation.

Ana Luisa Dian, Lucilla Fabbri, Antoine Moya-Plana, Giuseppina Claps, Juliana C Ferreira, Céline M Labbé, Virginie Quidville, Sylvain Martineau, Dorothée Baille, Laetitia Besse, Cédric Messaoudi, Séverine Roy, Virginie Raynal, Sylvain Baulande, Wael M Rabeh, Caroline Robert, Stéphan Vagner.

Although metabolic benefits of glycolysis have been extensively described in tumor cells, the extra-metabolic functions linked to this energetic pathway in tumor growth and cell proliferation have not been clearly established yet. Recently, some key glycolytic enzymes, such as glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase 2, were reported to regulate mRNA translation. Translational control of gene expression is considered as a critical effector in cancer biology, representing a highly promising area of research. Here, we report that Hexokinase 2 (HK2), a glucose kinase that catalyzes the first step of glycolysis at the outer mitochondrial membrane (OMM), is an RNA-binding protein (RBP) that regulates mRNA translation in melanoma cell lines. Polysome profiling experiments followed by RNA sequencing indicate that the translational regulation exerted by HK2 is partly independent of the metabolic status or the glycolytic pathway. We found that HK2 specifically regulates translation of the mRNA encoding SOX10, a transcription factor implicated in the regulation of tumor initiation, maintenance, and progression in melanoma. RNA-protein interaction assays, including CrossLinking ImmunoPrecipitation (CLIP), indicate that HK2 is an RBP whose interaction with RNA is independent of its enzymatic activity, its ability to bind glucose or its association with the OMM. HK2 directly interacts with the 5' untranslated region (5'UTR) of the SOX10 mRNA through a stem-loop RNA secondary structure. Using RNA-protein proximity ligation assays and a fluorescence-based ribosome-bound mRNA mapping method, we found that high glucose conditions, which promote the release of HK2 from the OMM, induce an increase in HK2-SOX10 mRNA interaction and SOX10 mRNA translation in the cytoplasm. We further showed that HK2-dependent SOX10 mRNA translation is involved in melanoma cell proliferation and colony formation. Collectively, our data highlight a nonmetabolic function of HK2 acting as an RBP and translation regulator.

DOI: https://doi.org/10.1371/journal.pbio.3003364

Cancer Discov. 2025 Sep 19.

Activation of T cell-intrinsic p53 by acetylation elicits antitumor immunity to boost cancer immunotherapy.

Xiaojun Yan, Wenbin Xu, Han Yao, Zhen Wu, Jingyuan Ning, Shidong Zhao, Yajing Liu, Meng Zhang, Dongkui Xu, Zhanlong Shen, Wei Gu, Donglai Wang.

Although p53 plays a central role in tumor suppression, how it is regulated in T cells to exert antitumor effects remains unclear. Here, we show that activation of T cell-intrinsic p53 via carboxyl-terminal domain (CTD) acetylation during immunotherapy activates the IFN-γ pathway, promotes CD8+ T cell infiltration, and elicits CD8+ T cell-dependent antitumor immunity. Using T cell-specific knockin mouse models, we demonstrate that loss of CTD acetylation in T cells abrogates CD8+ T cell-dependent antitumor immunity whereas expression of CTD acetylation-mimicking p53 in T cells enhances this immune response. Moreover, we identify IFNG as a direct target of T cell-intrinsic p53 and uncover a positive feedback loop between p53 and the IFN-γ pathway for enhancing T cell-dependent antitumor immunity. Our study reveals that CTD acetylation-mediated activation of T cell-intrinsic p53 promotes antitumor immunity in response to immunotherapy, highlighting a non-tumor cell-autonomous mechanism of p53 action by regulating adoptive immune responses.

DOI: https://doi.org/10.1158/2159-8290.CD-25-0649