bims-scepro 2024-09-01 papers

bims-scepro

Biomed News

on Stem cell proteostasis

Issue of 2024–09–01
fourteen papers selected by
William Grey, University of York

Systemic and local regulation of hematopoietic homeostasis in health and disease.
PIWI pathway: bridging acute myeloid leukemia stemness and cellular differentiation.
Targeted, safe, and efficient gene delivery to human hematopoietic stem and progenitor cells in vivo using the engineered AVID adenovirus vector platform.
SKF-96365 Expels Tyrosine Kinase Inhibitor-Treated CML Stem and Progenitor Cells from the HS27A Stromal Cell Niche in a RhoA-Dependent Mechanism.
Mitochondrial serine catabolism safeguards maintenance of the hematopoietic stem cell pool in homeostasis and injury.
OMIP-106: A 30-color panel for analysis of check-point inhibitory networks in the bone marrow of acute myeloid leukemia patients.
Reprogramming hematopoietic stem cell metabolism in lung cancer: glycolysis, oxidative phosphorylation, and the role of 2-DG.
PURE-seq identifies Egr1 as a Potential Master Regulator in Murine Aging by Sequencing Long-Term Hematopoietic Stem Cells.
The Lactate Receptor GPR81 is a Mechanism of Leukemia-Associated Macrophage Polarization in the Bone Marrow Microenvironment.
TOPORS E3 ligase mediates resistance to hypomethylating agent cytotoxicity in acute myeloid leukemia cells.
A multidimensional analysis reveals distinct immune phenotypes and the composition of immune aggregates in pediatric acute myeloid leukemia.
CRISPR screen of venetoclax response-associated genes identifies transcription factor ZNF740 as a key functional regulator.
Common Driver Mutations in AML: Biological Impact, Clinical Considerations, and Treatment Strategies.
Inhibition of TOPORS ubiquitin ligase augments the efficacy of DNA hypomethylating agents through DNMT1 stabilization.

Nat Cardiovasc Res. 2024 Jun;3(6): 651-665

Systemic and local regulation of hematopoietic homeostasis in health and disease.

Randall S Carpenter, Maria Maryanovich.

Hematopoietic stem cells (HSCs) generate all blood cell lineages responsible for tissue oxygenation, life-long hematopoietic homeostasis and immune protection. In adulthood, HSCs primarily reside in the bone marrow (BM) microenvironment, consisting of diverse cell types that constitute the stem cell 'niche'. The adaptability of the hematopoietic system is required to respond to the needs of the host, whether to maintain normal physiology or during periods of physical, psychosocial or environmental stress. Hematopoietic homeostasis is achieved by intricate coordination of systemic and local factors that orchestrate the function of HSCs throughout life. However, homeostasis is not a static process; it modulates HSC and progenitor activity in response to circadian rhythms coordinated by the central and peripheral nervous systems, inflammatory cues, metabolites and pathologic conditions. Here, we review local and systemic factors that impact hematopoiesis, focusing on the implications of aging, stress and cardiovascular disease.

DOI: https://doi.org/10.1038/s44161-024-00482-4
Front Cell Dev Biol. 2024 ;12 1449353

PIWI pathway: bridging acute myeloid leukemia stemness and cellular differentiation.

M R Garcia-Silva, M E Márquez, N Pinello.

  PIWI proteins are stem cell-associated RNA-binding proteins crucial for survival of germ stem cells. In cancer, PIWI proteins are overexpressed. Specifically, PIWIL4 is highly expressed in multiple cancers with the highest levels found in acute myeloid leukemia (AML), an aggressive malignancy propagated by a population of leukemia stem cells (LSCs). Bamezai et al. (Blood Journal, blood, 2023, 142, 90-105) demonstrated that PIWIL4 supports AML blasts and LSCs but is not necessary for healthy human hematopoietic progenitor stem cells (HSPCs) function in vivo. PIWIL4 in AML acts by preventing the accumulation of R-loops in key genes for LSCs persistence implicated in: DNA damage, replicative stress, and transcription arrest. We report that PIWIL4 expression significantly decreases in THP-1 monocytes exposed to a differentiating agent, suggesting a potential role for PIWIL4 in maintaining the undifferentiated state of myeloid cells. PIWIL4 overexpression could lead to the emergence of LSCs, driving leukemia propagation and maintenance. Our findings correlate with the persistent overexpression of PIWIL4 in myeloid cancers as reported by Bamezai et al., and suggest that PIWIL4 may be involved in myeloid cell differentiation. In this perspective, we highlight recent findings on the implication of PIWI pathway in maintaining AML stemness. Additionally, we propose further investigation on the role of PIWI pathway in oncogenesis and cellular differentiation as a strategy to identify biomarkers and therapeutic targets for AML.

Keywords:  AML; PIWI; macrophage; monocytes; piwi associated RNA

DOI:  https://doi.org/10.3389/fcell.2024.1449353
Mol Ther. 2024 Aug 22. pii: S1525-0016(24)00535-5. [Epub ahead of print]

Targeted, safe, and efficient gene delivery to human hematopoietic stem and progenitor cells in vivo using the engineered AVID adenovirus vector platform.

Jia Yao, Svetlana Atasheva, Nicole Wagner, Nelson C Di Paolo, Phoebe L Stewart, Dmitry M Shayakhmetov.

DOI: https://doi.org/10.1016/j.ymthe.2024.08.013
Cancers (Basel). 2024 Aug 08. pii: 2791. [Epub ahead of print]16(16):

SKF-96365 Expels Tyrosine Kinase Inhibitor-Treated CML Stem and Progenitor Cells from the HS27A Stromal Cell Niche in a RhoA-Dependent Mechanism.

Audrey Dubourg, Thomas Harnois, Laetitia Cousin, Bruno Constantin, Nicolas Bourmeyster.

   BACKGROUND: A major issue in Chronic Myeloid Leukemia (CML) is the persistence of quiescent leukemia stem cells (LSCs) in the hematopoietic niche under tyrosine kinase inhibitor (TKI) treatment.
RESULTS: Here, using CFSE sorting, we show that low-proliferating CD34+ cells from CML patients in 3D co-culture hide under HS27A stromal cells during TKI treatment-a behavior less observed in untreated cells. Under the same conditions, Ba/F3p210 cells lose their spontaneous motility. In CML CD34+ and Ba/F3p210 cells, while Rac1 is completely inhibited by TKI, RhoA remains activated but is unable to signal to ROCK. Co-incubation of Ba/F3p210 cells with TKI, SKF-96365 (a calcium channel inhibitor), and EGF restores myosin II activation and amoeboid motility to levels comparable to untreated cells, sustaining the activation of ROCK. In CFSE+ CD34+ cells containing quiescent leukemic stem cells, co-incubation of TKI with SKF-96365 induced the expulsion of these cells from the HS27A niche.
CONCLUSIONS: This study underscores the role of RhoA in LSC behavior under TKI treatment and suggests that SKF-96365 could remobilize quiescent CML LSCs through reactivation of the RhoA/ROCK pathway.

Keywords:  Chronic Myeloid Leukemia; RhoGTPases; SKF-96365; leukemia niche; leukemia stem cells; tyrosine kinase inhibitors

DOI:  https://doi.org/10.3390/cancers16162791
Cell Stem Cell. 2024 Aug 21. pii: S1934-5909(24)00285-6. [Epub ahead of print]

Mitochondrial serine catabolism safeguards maintenance of the hematopoietic stem cell pool in homeostasis and injury.

Changhong Du, Chaonan Liu, Kuan Yu, Shuzhen Zhang, Zeyu Fu, Xinliang Chen, Weinian Liao, Jun Chen, Yimin Zhang, Xinmiao Wang, Mo Chen, Fang Chen, Mingqiang Shen, Cheng Wang, Shilei Chen, Song Wang, Junping Wang.

  Hematopoietic stem cells (HSCs) employ a very unique metabolic pattern to maintain themselves, while the spectrum of their metabolic adaptations remains incompletely understood. Here, we uncover a distinct and heterogeneous serine metabolism within HSCs and identify mouse HSCs as a serine auxotroph whose maintenance relies on exogenous serine and the ensuing mitochondrial serine catabolism driven by the hydroxymethyltransferase 2 (SHMT2)-methylene-tetrahydrofolate dehydrogenase 2 (MTHFD2) axis. Mitochondrial serine catabolism primarily feeds NAD(P)H generation to maintain redox balance and thereby diminishes ferroptosis susceptibility of HSCs. Dietary serine deficiency, or genetic or pharmacological inhibition of the SHMT2-MTHFD2 axis, increases ferroptosis susceptibility of HSCs, leading to impaired maintenance of the HSC pool. Moreover, exogenous serine protects HSCs from irradiation-induced myelosuppressive injury by fueling mitochondrial serine catabolism to mitigate ferroptosis. These findings reframe the canonical view of serine from a nonessential amino acid to an essential niche metabolite for HSC pool maintenance.

Keywords:  NADPH; SHMT2; ferroptosis; hematopoietic stem cell; heterogeneity; ionizing radiation; mitochondrial serine catabolism; myelosuppressive injury

DOI:  https://doi.org/10.1016/j.stem.2024.07.009
Cytometry A. 2024 Aug 27.

OMIP-106: A 30-color panel for analysis of check-point inhibitory networks in the bone marrow of acute myeloid leukemia patients.

Jan Musil, Antonin Ptacek, Sarka Vanikova.

  Acute myeloid leukemia (AML) is the most common form of acute leukemia diagnosed in adults. Despite advances in medical care, the treatment of AML still faces many challenges, such as treatment-related toxicities, that limit the use of high-intensity chemotherapy, especially in elderly patients. Currently, various immunotherapeutic approaches, that is, CAR-T cells, BiTEs, and immune checkpoint inhibitors, are being tested in clinical trials to prolong remission and improve the overall survival of AML patients. However, early reports show only limited benefits of these interventions and only in a subset of patients, showing the need for better patient stratification based on immunological markers. We have therefore developed and optimized a 30-color panel for evaluation of effector immune cell (NK cells, γδ T cells, NKT-like T cells, and classical T cells) infiltration into the bone marrow and analysis of their phenotype with regard to their differentiation, expression of inhibitory (PD-1, TIGIT, Tim3, NKG2A) and activating receptors (DNAM-1, NKG2D). We also evaluate the immune evasive phenotype of CD33+ myeloid cells, CD34+CD38-, and CD34+CD38+ hematopoietic stem and progenitor cells by analyzing the expression of inhibitory ligands such as PD-L1, CD112, CD155, and CD200. Our panel can be a valuable tool for patient stratification in clinical trials and can also be used to broaden our understanding of check-point inhibitory networks in AML.

Keywords:  AML; NK cells; T cells; bone marrow; checkpoint inhibitors; high‐dimensional flow cytometry; immune checkpoint; immunotherapy; inhibitory ligands; leukemic stem cells

DOI:  https://doi.org/10.1002/cyto.a.24892
Biol Direct. 2024 Aug 24. 19(1): 73

Reprogramming hematopoietic stem cell metabolism in lung cancer: glycolysis, oxidative phosphorylation, and the role of 2-DG.

Ziqi Guo, Yaping Liu, Xin Li, Yuying Huang, Zuping Zhou, Cheng Yang.

  Hematopoietic stem cells (HSCs) exhibit significant functional and metabolic alterations within the lung cancer microenvironment, contributing to tumor progression and immune evasion by increasing differentiation into myeloid-derived suppressor cells (MDSCs). Our aim is to analyze the metabolic transition of HSCs from glycolysis to oxidative phosphorylation (OXPHOS) in lung cancer and determine its effects on HSC functionality. Using a murine Lewis Lung Carcinoma lung cancer model, we conducted metabolic profiling of long-term and short-term HSCs, as well as multipotent progenitors, comparing their metabolic states in normal and cancer conditions. We measured glucose uptake using 2-[N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino]-2-Deoxyglucose (2-NBDG) and assessed levels of lactate, acetyl-coenzyme A, and ATP. Mitochondrial functionality was evaluated through flow cytometry, alongside the impact of the glucose metabolism inhibitor 2-DG on HSC differentiation and mitochondrial activity. HSCs under lung cancer conditions showed increased glucose uptake and lactate production, with an associated rise in OXPHOS activity, marking a metabolic shift. Treatment with 2-DG led to decreased T-HSCs and MDSCs and an increased red blood cell count, highlighting its potential to influence metabolic and differentiation pathways in HSCs. This study provides novel insights into the metabolic reprogramming of HSCs in lung cancer, emphasizing the critical shift from glycolysis to OXPHOS and its implications for the therapeutic targeting of cancer-related metabolic pathways.

Keywords:  2-DG; Glycolysis; Hematopoietic stem cells; Lung cancer; Metabolic reprogramming; Oxidative phosphorylation; Tumor microenvironment

DOI:  https://doi.org/10.1186/s13062-024-00514-w
Res Sq. 2024 Aug 13. pii: rs.3.rs-4863813. [Epub ahead of print]

PURE-seq identifies Egr1 as a Potential Master Regulator in Murine Aging by Sequencing Long-Term Hematopoietic Stem Cells.

Adam Abate, Sixuan Pan, Kai-Chun Chang, Inés Fernández-Maestre, Stéphane Haver, Matthew Wereski, Robert Bowman, Ross Levine.

Single-cell transcriptomics is valuable for uncovering individual cell properties, particularly in highly heterogeneous systems. However, this technique often results in the analysis of many well-characterized cells, increasing costs and diluting rare cell populations. To address this, we developed PURE-seq (PIP-seq for Rare-cell Enrichment and Sequencing) for scalable sequencing of rare cells. PURE-seq allows direct cell loading from FACS into PIP-seq reactions, minimizing handling and reducing cell loss. PURE-seq reliably captures rare cells, with 60 minutes of sorting capturing tens of cells at a rarity of 1 in 1,000,000. Using PURE-seq, we investigated murine long-term hematopoietic stem cells and their transcriptomes in the context of hematopoietic aging, identifying Egr1 as a potential master regulator of hematopoiesis in the aging context. PURE-seq offers an accessible and reliable method for isolating and sequencing cells that are currently too rare to capture successfully with existing methods.

DOI: https://doi.org/10.21203/rs.3.rs-4863813/v1
bioRxiv. 2024 Aug 16. pii: 2023.11.13.566874. [Epub ahead of print]

The Lactate Receptor GPR81 is a Mechanism of Leukemia-Associated Macrophage Polarization in the Bone Marrow Microenvironment.

Celia A Soto, Maggie L Lesch, Jennifer L Becker, Azmeer Sharipol, Amal Khan, Xenia L Schafer, Michael W Becker, Joshua C Munger, Benjamin J Frisch.

  Interactions between acute myeloid leukemia (AML) and the bone marrow microenvironment (BMME) are critical to leukemia progression and chemoresistance. Altered metabolite levels in the tumor microenvironment contribute to immunosuppression in solid tumors, while this has not been studied yet in the leukemic BMME. Metabolomics of AML patient bone marrow serum detected elevated metabolites, including lactate, compared to age- and sex-matched controls. Excess lactate has been implicated in solid tumors for inducing suppressive tumor-associated macrophages (TAMs) and correlates with poor prognosis. We describe the role of lactate in the polarization of leukemia-associated macrophages (LAMs) using a murine model of blast crisis chronic myelogenous leukemia (bcCML) and mice genetically lacking the lactate receptor GPR81. LAMs were CD206hi and suppressive in transcriptomics and cytokine profiling. Yet, LAMs had a largely unique expression profile from other types of TAMs. We demonstrate GPR81 signaling as a mechanism of both LAM polarization and the direct support of leukemia cell growth and self-repopulation. Furthermore, LAMs and elevated lactate diminished the function of hematopoietic progenitors and stromal support, while knockout of GPR81 had modest protective effects on the hematopoietic system. We report microenvironmental lactate as a critical driver of AML-induced immunosuppression and leukemic progression, thus identifying GPR81 signaling as an exciting and novel therapeutic target for treating this devastating disease.

Keywords:  Acute myeloid leukemia (AML); GPR81; bone marrow microenvironment; lactate; macrophages

DOI:  https://doi.org/10.1101/2023.11.13.566874
Nat Commun. 2024 Aug 28. 15(1): 7360

TOPORS E3 ligase mediates resistance to hypomethylating agent cytotoxicity in acute myeloid leukemia cells.

Peter Truong, Sylvie Shen, Swapna Joshi, Md Imtiazul Islam, Ling Zhong, Mark J Raftery, Ali Afrasiabi, Hamid Alinejad-Rokny, Mary Nguyen, Xiaoheng Zou, Golam Sarower Bhuyan, Chowdhury H Sarowar, Elaheh S Ghodousi, Olivia Stonehouse, Sara Mohamed, Cara E Toscan, Patrick Connerty, Purvi M Kakadia, Stefan K Bohlander, Katharine A Michie, Jonas Larsson, Richard B Lock, Carl R Walkley, Julie A I Thoms, Christopher J Jolly, John E Pimanda.

Hypomethylating agents (HMAs) are frontline therapies for Myelodysplastic Neoplasms (MDS) and Acute Myeloid Leukemia (AML). However, acquired resistance and treatment failure are commonplace. To address this, we perform a genome-wide CRISPR-Cas9 screen in a human MDS-derived cell line, MDS-L, and identify TOPORS as a loss-of-function target that synergizes with HMAs, reducing leukemic burden and improving survival in xenograft models. We demonstrate that depletion of TOPORS mediates sensitivity to HMAs by predisposing leukemic blasts to an impaired DNA damage response (DDR) accompanied by an accumulation of SUMOylated DNMT1 in HMA-treated TOPORS-depleted cells. The combination of HMAs with targeting of TOPORS does not impair healthy hematopoiesis. While inhibitors of TOPORS are unavailable, we show that inhibition of protein SUMOylation with TAK-981 partially phenocopies HMA-sensitivity and DDR impairment. Overall, our data suggest that the combination of HMAs with inhibition of SUMOylation or TOPORS is a rational treatment option for High-Risk MDS (HR-MDS) or AML.

DOI: https://doi.org/10.1038/s41467-024-51646-6
Leukemia. 2024 Aug 26.

A multidimensional analysis reveals distinct immune phenotypes and the composition of immune aggregates in pediatric acute myeloid leukemia.

Joost B Koedijk, Inge van der Werf, Livius Penter, Marijn A Vermeulen, Farnaz Barneh, Alicia Perzolli, Joyce I Meesters-Ensing, Dennis S Metselaar, Thanasis Margaritis, Marta Fiocco, Hester A de Groot-Kruseman, Rubina Moeniralam, Kristina Bang Christensen, Billie Porter, Kathleen Pfaff, Jacqueline S Garcia, Scott J Rodig, Catherine J Wu, Henrik Hasle, Stefan Nierkens, Mirjam E Belderbos, C Michel Zwaan, Olaf Heidenreich.

Because of the low mutational burden and consequently, fewer potential neoantigens, children with acute myeloid leukemia (AML) are thought to have a T cell-depleted or 'cold' tumor microenvironment and may have a low likelihood of response to T cell-directed immunotherapies. Understanding the composition, phenotype, and spatial organization of T cells and other microenvironmental populations in the pediatric AML bone marrow (BM) is essential for informing future immunotherapeutic trials about targetable immune-evasion mechanisms specific to pediatric AML. Here, we conducted a multidimensional analysis of the tumor immune microenvironment in pediatric AML and non-leukemic controls. We demonstrated that nearly one-third of pediatric AML cases has an immune-infiltrated BM, which is characterized by a decreased ratio of M2- to M1-like macrophages. Furthermore, we detected the presence of large T cell networks, both with and without colocalizing B cells, in the BM and dissected the cellular composition of T- and B cell-rich aggregates using spatial transcriptomics. These analyses revealed that these aggregates are hotspots of CD8+ T cells, memory B cells, plasma cells and/or plasmablasts, and M1-like macrophages. Collectively, our study provides a multidimensional characterization of the BM immune microenvironment in pediatric AML and indicates starting points for further investigations into immunomodulatory mechanisms in this devastating disease.

DOI: https://doi.org/10.1038/s41375-024-02381-w
Cell Death Dis. 2024 Aug 27. 15(8): 627

CRISPR screen of venetoclax response-associated genes identifies transcription factor ZNF740 as a key functional regulator.

Lixia Zhang, Xinyue Zhou, Sajesan Aryal, Virginia Veasey, Pengcheng Zhang, Fu Jun Li, Yu Luan, Ravi Bhatia, Yang Zhou, Rui Lu.

BCL-2 inhibitors such as venetoclax offer therapeutic promise in acute myeloid leukemia (AML) and other cancers, but drug resistance poses a significant challenge. It is crucial to understand the mechanisms that regulate venetoclax response. While correlative studies have identified numerous genes linked to venetoclax sensitivity, their direct impact on the drug response remains unclear. In this study, we targeted around 1400 genes upregulated in venetoclax-sensitive primary AML samples and carried out a CRISPR knockout screen to evaluate their direct effects on venetoclax response. Our screen identified the transcription factor ZNF740 as a critical regulator, with its expression consistently predicting venetoclax sensitivity across subtypes of the FAB classification. ZNF740 depletion leads to increased resistance to ventoclax, while its overexpression enhances sensitivity to the drug. Mechanistically, our integrative transcriptomic and genomic analysis identifies NOXA as a direct target of ZNF740, which negatively regulates MCL-1 protein stability. Loss of ZNF740 downregulates NOXA and increases the steady state protein levels of MCL-1 in AML cells. Restoring NOXA expression in ZNF740-depleted cells re-sensitizes AML cells to venetoclax treatment. Furthermore, we demonstrated that dual targeting of MCL-1 and BCL-2 effectively treats ZNF740-deficient AML in vivo. Together, our work systematically elucidates the causal relationship between venetoclax response signature genes and establishes ZNF740 as a novel transcription factor regulating venetoclax sensitivity.

DOI: https://doi.org/10.1038/s41419-024-06995-x
Cells. 2024 Aug 21. pii: 1392. [Epub ahead of print]13(16):

Common Driver Mutations in AML: Biological Impact, Clinical Considerations, and Treatment Strategies.

Tiffany Nong, Shefali Mehra, Justin Taylor.

  Next-generation sequencing of samples from patients with acute myeloid leukemia (AML) has revealed several driver gene mutations in adult AML. However, unlike other cancers, AML is defined by relatively few mutations per patient, with a median of 4-5 depending on subtype. In this review, we will discuss the most common driver genes found in patients with AML and focus on the most clinically relevant ones that impact treatment strategies. The most common driver gene mutations in AML occur in NPM1 and FLT3, accounting for ~30% each. There are now targeted therapies being tested or already approved for these driver genes. Menin inhibitors, a novel targeted therapy that blocks the function of the menin protein, are in clinical trials for NPM1 driver gene mutant AML after relapse. A number of FLT3 inhibitors are now approved for FLT3 driver gene mutant AML in combination with chemotherapy in the frontline and also as single agent in relapse. Although mutations in IDH1/2 and TP53 only occur in around 10-20% of patients with AML each, they can affect the treatment strategy due to their association with prognosis and availability of targeted agents. While the impact of other driver gene mutations in AML is recognized, there is a lack of data on the actionable impact of those mutations.

Keywords:  AML; FLT3; IDH; NPM1; TP53; driver mutations

DOI:  https://doi.org/10.3390/cells13161392
Nat Commun. 2024 Aug 28. 15(1): 7359

Inhibition of TOPORS ubiquitin ligase augments the efficacy of DNA hypomethylating agents through DNMT1 stabilization.

Satoshi Kaito, Kazumasa Aoyama, Motohiko Oshima, Akiho Tsuchiya, Makiko Miyota, Masayuki Yamashita, Shuhei Koide, Yaeko Nakajima-Takagi, Hiroko Kozuka-Hata, Masaaki Oyama, Takao Yogo, Tomohiro Yabushita, Ryoji Ito, Masaya Ueno, Atsushi Hirao, Kaoru Tohyama, Chao Li, Kimihito Cojin Kawabata, Kiyoshi Yamaguchi, Yoichi Furukawa, Hidetaka Kosako, Akihide Yoshimi, Susumu Goyama, Yasuhito Nannya, Seishi Ogawa, Karl Agger, Kristian Helin, Satoshi Yamazaki, Haruhiko Koseki, Noriko Doki, Yuka Harada, Hironori Harada, Atsuya Nishiyama, Makoto Nakanishi, Atsushi Iwama.

DNA hypomethylating agents (HMAs) are used for the treatment of myeloid malignancies, although their therapeutic effects have been unsatisfactory. Here we show that CRISPR-Cas9 screening reveals that knockout of topoisomerase 1-binding arginine/serine-rich protein (TOPORS), which encodes a ubiquitin/SUMO E3 ligase, augments the efficacy of HMAs on myeloid leukemic cells with little effect on normal hematopoiesis, suggesting that TOPORS is involved in resistance to HMAs. HMAs are incorporated into the DNA and trap DNA methyltransferase-1 (DNMT1) to form DNA-DNMT1 crosslinks, which undergo SUMOylation, followed by proteasomal degradation. Persistent crosslinking is cytotoxic. The TOPORS RING finger domain, which mediates ubiquitination, is responsible for HMA resistance. In TOPORS knockout cells, DNMT1 is stabilized by HMA treatment due to inefficient ubiquitination, resulting in the accumulation of unresolved SUMOylated DNMT1. This indicates that TOPORS ubiquitinates SUMOylated DNMT1, thereby promoting the resolution of DNA-DNMT1 crosslinks. Consistently, the ubiquitination inhibitor, TAK-243, and the SUMOylation inhibitor, TAK-981, show synergistic effects with HMAs through DNMT1 stabilization. Our study provides a novel HMA-based therapeutic strategy that interferes with the resolution of DNA-DNMT1 crosslinks.

DOI: https://doi.org/10.1038/s41467-024-50498-4