Biology subjects

Hofmann, I.

Publications and source records attributed to Hofmann, I..

5 recordsLinked to original sources

bioRxiv2025

GLYATL1 is associated with metabolic and epigenetic changes and with endocrine resistance in luminal breast cancer

Estrogen receptor alpha (ER)-positive luminal breast cancer is commonly treated with aromatase inhibitors (AI) to block estrogen signaling; however, resistance frequently develops, limiting therapy success. We observed that GLYATL1 (Glycine-N-Acyltransferase Like 1) expression is upregulated in AI-resistant breast cancer cell models and in patients undergoing AI therapy, correlating with poorer survival. Here we demonstrate that GLYATL1 promotes resistance to estrogen deprivation by elevating succinate levels and altering epigenetic histone marks associated with active transcription. Knockdown or knockout of GLYATL1 reverses these effects and reduces proliferation under estrogen-deprived conditions. Notably, GLYATL1 expression is positively regulated by estrogen receptor alpha signaling independently of estrogen. These findings reveal GLYATL1 as a metabolic and epigenetic mediator of endocrine therapy resistance, suggesting it as a potential target to overcome AI resistance in luminal breast cancer.

cancer biology↗

bioRxiv2025

P2RY2 is a purinergic immune checkpoint linking extracellular ATP to immune evasion and adaptive resistance to immunotherapy

Extracellular ATP (eATP) accumulates substantially in the tumor microenvironment (TME) and rises further during immunotherapy. While canonically an immune-activating "danger" signal, eATP also promotes immunosuppression in tumors, thus far largely attributed to its metabolite, adenosine. Here, we identify direct eATP signaling through P2RY2 as a dominant, adenosine-independent mechanism of immune resistance. Specifically, eATP-P2RY2 signaling serves as the primary upstream driver of COX-1/2 upregulation and consequent accumulation of immunosuppressive PGE2 in the TME, uncovering the long-sought TME-specific trigger of pathological COX-PGE2 hyperactivation in solid tumors. Genetic deletion or pharmacologic inhibition of P2RY2 eliminates both baseline and therapy-induced intratumoral PGE2, restores antitumor T cell responses, and reverses resistance to CAR-T, TCR-T, checkpoint blockade, and TIL therapies. Given that persistently elevated eATP is a hallmark of solid tumors, our work reveals a fundamental mechanism by which tumors hijack innate "danger" signaling to establish immune suppression and develop adaptive resistance to immunotherapy. These findings establish P2RY2 as a purinergic immune checkpoint with translational potential for combinatorial cancer immunotherapies. HIGHLIGHTSO_LIeATP in the TME drives baseline and therapy-induced immune evasion via P2RY2 C_LIO_LIeATP-P2RY2 signaling is the primary cause of PGE2 accumulation in the TME C_LIO_LIP2RY2 propels a feedback loop that enforces adaptive resistance to immunotherapies C_LIO_LIP2RY2 blockade reprograms the TME and restores immunotherapy responsiveness C_LI

immunology↗

bioRxiv2025

Repurposing passenger amplifications as Trojan horses identifies MPZL1 as a potent target for solid cancers

Personalized cancer therapies focus mostly on targeting driver alterations, such as oncogenic point mutations or oncogenic driver events within large somatic copy number alterations. However, these alterations are often not actionable or only present in a small subset of patients. We hypothesized that passenger events, specifically in amplified regions, could be therapeutically exploited by providing actionable molecules on the cell surface, serving as Trojan horses for specific therapy delivery. Applying a multiomics in silico approach, we identified MPZL1 (Myelin protein zero-like 1), a glycosylated cell surface receptor located on chromosome 1q, as a promising candidate, which is amplified in up to 75% of cases in several solid cancers. Notably, immunohistochemistry of a wide range of human cancer tissues (n=2244 samples) as well as normal tissues revealed strong membranous MPZL1 expression in a majority of solid tumors (e.g. 48% of hepatocellular carcinomas or 89% of triple-negative breast cancers), whereas healthy tissues were mostly negative or just faintly positive for MPZL1. Next, we generated a highly specific monoclonal antibody directed to the extracellular domain of human MPZL1 protein and utilized this antibody to produce MPZL1 CAR-T cells. MPZL1 CAR-T cells showed high specificity as well as high sensitivity in targeting a multitude of human cancer cell lines (e.g. liver, breast, and lung cancer) with high MPZL1 expression in vitro. Finally, we demonstrate strong therapeutic efficiency of MPZL1 CAR-T cells not only in different human xenograft tumors in vivo but also in a unique autochthonous liver cancer mouse model. Our work provides a framework to target passenger events within large chromosomal amplifications, reveals MPZL1 as a new trojan horse entry point for therapies of 1q-amplified cancers, and as such opens a new avenue for innovative approaches in anti-cancer drug development.

cancer biology↗

bioRxiv2023

Diurnal control of iron responsive element (IRE)-containing mRNAs through iron regular proteins IRP1 and IRP2 is mediated by feeding rhythms

BackgroundCellular iron homeostasis is regulated by iron regulatory proteins (IRP1 and IRP2) that sense iron levels (and other metabolic cues) and modulate mRNA translation or stability via interaction with iron regulatory elements (IREs). IRP2 is viewed as the primary regulator in liver, yet our previous datasets showing diurnal rhythms for certain IRE-containing mRNAs suggest a nuanced temporal control mechanism. The purpose of this study is to gain insights into the daily regulatory dynamics across IRE-bearing mRNAs, specific IRP involvement, and underlying systemic and cellular rhythmicity cues in mouse liver. ResultsWe uncover high-amplitude diurnal oscillations in the regulation of key IRE containing transcripts in liver, compatible with maximal IRP activity at the onset of the dark phase. Although IRP2 protein levels also exhibit some diurnal variations and peak at the light-dark transition, ribosome profiling in IRP2-deficient mice reveals that maximal repression of target mRNAs at this time-point still occurs. We further find that diurnal regulation of IRE-containing mRNAs can continue in the absence of a functional circadian clock as long as feeding is rhythmic. ConclusionsOur findings suggest temporally controlled redundancy in IRP activities, with IRP2 mediating regulation of IRE-containing transcripts in the light phase and redundancy, conceivably with IRP1, at dark onset. Moreover, we highlight the significance of feeding-associated signals in driving rhythmicity. Our work highlights the dynamic nature and regulatory complexity in a metabolic pathway that had previously been considered well-understood.

molecular biology↗

bioRxiv2020

Distinct genetic pathways define pre-leukemic and compensatory clonal hematopoiesis in Shwachman-Diamond syndrome

Shwachman-Diamond syndrome (SDS) is an inherited bone marrow failure syndrome with predisposition to developing leukemia. We found that multiple independent somatic hematopoietic clones arise early in life, most commonly harboring heterozygous mutations in EIF6 or TP53. EIF6 mutations cause functional compensation for the germline deficiency by alleviating the SDS ribosome joining defect, improving translation, and reducing p53 activation. TP53 mutations decrease checkpoint activation without affecting ribosome assembly. We link development of leukemia with acquisition of biallelic TP53 alterations. Our results define distinct pathways of clonal selection driven by germline fitness constraint and provide a mechanistic framework for clinical surveillance.

cancer biology↗