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Pharmacological targeting of the IL17/neutrophil axis attenuates calcific deposits in rat models of calciphylaxis

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Abstract

Calciphylaxis is a rare but life-threatening disorder characterized by ectopic calcification affecting the subcutaneous tissues and blood vessels of the skin. Once diagnosed, survival rates are less than a year and yet despite the severity of the condition, the pathobiology of calciphylaxis is ill understood. Here, we create animal models of calciphylaxis that recapitulate many characteristics of the human phenotype. We demonstrate that cutaneous calcification is preceded by inflammatory cell infiltration. We show that increased local skin inflammation, regardless of the inciting cause, in the presence of hypercalcemia and hyperphosphatemia contributes to cutaneous ectopic calcification. Genetically modified rodents lacking immune activation of T and B cells or NK cells are resistant to developing cutaneous calcification. Consistent with this, administration of the immunosuppressive cyclophosphamide rescued calcific deposits as did T cell suppression with cyclosporine. We demonstrate IL17 is upregulated in calcific skin and neutrophils are the predominant cell types expressing IL 17 and tissue alkaline phosphatase that is necessary for ectopic calcification. Targeting IL17 with a monoclonal antibody or using a myeloperoxidase inhibitor to blunt neutrophil activation notably attenuated calcific deposits in vivo. Taken together, these observations provide fresh insight into the role of the immune system and the IL17/neutrophil axis in mediating ectopic calcification in rodent models of calciphylaxis.

Authors

Bo Tao, Edward Z. Cao, James Hyun, Sivakumar Ramadoss, Juan F. Alvarez, Lianjiu Su, Qihao Sun, Zhihao Liu, Linlin Zhang, Alejandro Espinoza, Yiqian Gu, Feiyang Ma, Shen Li, Matteo Pellegrini, Arjun Deb

Single-Dose Genome Editing Therapy Rescues Auditory and Vestibular Functions in Adult Mice with DFNA41 Deafness

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Abstract

Genome editing has shown the potential to treat genetic hearing loss. However, current editing therapies for genetic hearing loss have shown efficacy only in hearing rescue. In this study, we evaluated a rescue strategy using AAV2-mediated delivery of SaCas9/sgRNA in the mature inner ear of the P2rx2V61L/+ mouse model of DFNA41, a dominant, delayed-onset, and progressive hearing loss in humans. We demonstrate that local injection in adult mice results in efficient and specific editing that abolishes the mutation without notable off-target effects or AAV genome integration. Editing effectively restores long-term auditory and vestibular function. Editing further protects P2rx2V61L/+ mice from hypersensitivity to noise-induced hearing loss (NIHL), a phenotype also observed in DFNA41 patients. Intervention at a juvenile stage broadens the frequency range rescued, highlighting the importance of early intervention. An effective and specific gRNA for the human P2RX2 V60L mutation has been identified. Our study establishes the feasibility of editing to treat DFNA41 caused by P2RX2 V60L mutation in humans and opens an avenue for using editing to rescue hearing and vestibular function while mitigating noise-induced hearing loss.

Authors

Wei Wei, Wenliang Zhu, Stewart Silver, Ariel M. Armstrong, Fletcher S. Robbins, Arun Prabhu Rameshbabu, Katherina Walz, Yizhou Quan, Wan Du, Yehree Kim, Artur A. Indzhykulian, Yilai Shu, Xue-Zhong Liu, Zheng-Yi Chen

Dual targeting CDK4/6 and CDK7 augments tumor response and anti-tumor immunity in breast cancer models

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Abstract

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) have transformed the treatment landscape for hormone receptor-positive (HR+) breast cancer. However, their long-term efficacy is limited by acquired resistance, and CDK4/6i monotherapy remains ineffective in triple-negative breast cancer (TNBC). Here, we demonstrate that dual inhibition of CDK4/6 and CDK7 is a promising strategy to overcome therapeutic resistance in both HR+ and TNBC models. Kinetic analyses reveal that CDK7 inhibitors (CDK7i) primarily impair RNA polymerase II-mediated transcription rather than directly targeting cell-cycle CDKs. This transcriptional suppression attenuates E2F-driven transcriptional amplification, a key mechanism for developing CDK4/6i resistance following the degradation of the retinoblastoma protein. Consequently, combining CDK7i at minimal effective concentrations with CDK4/6i potently inhibits the growth of drug-resistant tumors. Furthermore, dual CDK4/6 and CDK7 inhibition stimulates immune-related signaling and cytokine production in cancer cells, promoting anti-tumor immune responses within the tumor microenvironment. These findings provide mechanistic insights into CDK inhibition and support the therapeutic potential of combining CDK7i with CDK4/6i for breast cancer treatment.

Authors

Sungsoo Kim, Eugene Son, Ha-Ram Park, Minah Kim, Hee Won Yang

Divergent TIR signaling domains in TLR7 and TLR9 control opposing effects on systemic autoimmunity

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Abstract

Toll like receptor (TLR) 7 and 9, endosomal sensors for RNA and DNA, are key mediators of autoreactivity. Although generally considered homologous, they paradoxically have opposing effects on lupus: TLR7 exacerbates disease while TLR9 protects from disease. How they mediate opposing effects in autoimmunity remains undetermined. We hypothesized that differences in signaling qualities of the Toll-Interleukin 1 Receptor (TIR) domains of TLR7 and TLR9 could be responsible for their opposing effects. To test this, we introduced the TIR domain of TLR9 into the endogenous TLR7 locus and the TLR7 TIR domain into the endogenous TLR9 locus of mice, creating chimeric molecules termed TLR779 and TLR997. Lupus-prone MRL/lpr mice carrying Tlr779 had greatly ameliorated disease while MRL/lpr mice carrying Tlr997 had markedly exacerbated disease compared to respective TlrWT mice. These experiments establish that TLR7 and TLR9 TIR domains have divergent properties and control disease quality, thus explaining the longstanding “TLR paradox.”

Authors

Claire Leibler, Kayla B. Thomas, Coralie Josensi, Russell C. Levack, Shuchi Smita, Shinu John, Daniel J. Wikenheiser, Sheldon Bastacky, Sebastien Gingras, Kevin M. Nickerson, Mark J. Shlomchik

Epigenetic targeting of PGBD5-dependent DNA damage in SMARCB1-deficient sarcomas

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Abstract

Despite the potential of targeted epigenetic therapies, most cancers do not respond to current epigenetic drugs. The Polycomb repressive complex EZH2 inhibitor tazemetostat was recently approved for the treatment of SMARCB1-deficient epithelioid sarcomas, based on the functional antagonism between PRC2 and SMARCB1. Through the analysis of tazemetostat-treated patient tumors, we recently defined key principles of their response and resistance to EZH2 epigenetic therapy. Here, using transcriptomic inference from SMARCB1-deficient tumor cells, we nominated the DNA damage repair kinase ATR as a target for rational EZH2 combination epigenetic therapy. We showed that EZH2 inhibition promotes DNA damage in epithelioid and rhabdoid tumor cells, at least in part via its induction of piggyBac transposable element derived 5 (PGBD5). We leveraged this collateral synthetic lethal dependency to target PGBD5-dependent DNA damage by inhibition of ATR, but not CHK1, using the ATR inhibitor elimusertib. Consequently, combined EZH2 and ATR inhibition improved therapeutic responses in diverse patient-derived epithelioid and rhabdoid tumors in vivo. This advances a combination epigenetic therapy based on EZH2-PGBD5 synthetic lethal dependency suitable for immediate translation to clinical trials for patients.

Authors

Yaniv Kazansky, Helen S. Mueller, Daniel Cameron, Phillip Demarest, Nadia Zaffaroni, Noemi Arrighetti, Valentina Zuco, Prabhjot S. Mundi, Yasumichi Kuwahara, Romel Somwar, Rui Qu, Andrea Califano, Elisa de Stanchina, Filemon S. Dela Cruz, Andrew L. Kung, Mrinal M. Gounder, Alex Kentsis

The Na_V1.5 auxiliary subunit FGF13 modulates channels by regulating membrane cholesterol independent of channel binding

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Abstract

Fibroblast growth factor homologous factors (FHFs) bind to the cytoplasmic carboxy terminus of voltage-gated sodium channels (VGSCs) and modulate channel function. Variants in FHFs or VGSCs perturbing that bimolecular interaction are associated with arrhythmias. Like some channel auxiliary subunits, FHFs exert additional cellular regulatory roles, but whether these alternative roles affect VGSC regulation is unknown. Using a separation-of-function strategy, we show that a structurally guided, binding incompetent mutant FGF13 (the major FHF in mouse heart) confers complete regulation of VGSC steady-state inactivation (SSI), the canonical effect of FHFs. In cardiomyocytes isolated from Fgf13 knockout mice, expression of the mutant FGF13 completely restores wild-type regulation of SSI. FGF13 regulation of SSI derives from effects on local accessible membrane cholesterol, which is unexpectedly polarized and concentrated in cardiomyocytes at the intercalated disc (ID) where most VGSCs localize. Fgf13 knockout eliminates the polarized cholesterol distribution and causes loss of VGSCs from the ID. Moreover, we show that the previously described FGF13-dependent stabilization of VGSC currents at elevated temperatures depends on the cholesterol mechanism. These results provide new insights into how FHFs affect VGSCs and alter the canonical model by which channel auxiliary subunits exert influence.

Authors

Aravind R. Gade, Mattia Malvezzi, Lala Tanmoy Das, Maiko Matsui, Cheng-I J. Ma, Keon Mazdisnian, Steven O. Marx, Frederick R. Maxfield, Geoffrey S. Pitt

Platelet-specific SLFN14 deletion causes macrothrombocytopenia and platelet dysfunction through dysregulated megakaryocyte and platelet gene expression

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Abstract

SLFN14-related thrombocytopenia is a rare bleeding disorder caused by SLFN14 mutations altering hemostasis in patients with platelet dysfunction. Schlafen (SLFN) proteins are highly conserved in mammals where SLFN14 is specifically expressed in megakaryocyte (MK) and erythroblast lineages. The role of SLFN14 in megakaryopoiesis and platelet function has not been elucidated. We generated a new murine model with a platelet- and MK-specific SLFN14 deletion using platelet factor-4 (PF4) cre-mediated deletion of exons 2 and 3 in Slfn14 (Slfn14;PF4-Cre) to decipher the molecular mechanisms driving the bleeding phenotype. SLFN14;PF4-Cre+ platelets displayed reduced platelet signaling to thrombin, reduced thrombin formation, increased bleeding tendency, and delayed thrombus formation as assessed by intravital imaging. Moreover, fewer in situ bone marrow MKs compared to controls. RNA sequencing and gene ontology analysis of MKs and platelets from Slfn14;PF4-Cre homozygous mice revealed altered pathways of ubiquitination, ATP activity, cytoskeleton and molecular function. In summary, we investigated how SLFN14 deletion in MKs and platelets leads to platelet dysfunction and alters their transcriptome, explaining the platelet dysfunction and bleeding in humans and mice with SLFN14 mutations.

Authors

Rachel J. Stapley, Xenia Sawkulycz, Gabriel H.M. Da Mota Araujo, Maximilian Englert, Lourdes Garcia-Quintanilla, Sophie R.M. Smith, Amna Ahmed, Elizabeth J. Haining, Nayandeep Kaur, Andrea Bacon, Andrey V. Pisarev, Natalie S. Poulter, Dean P.J. Kavanagh, Steven G. Thomas, Samantha J. Montague, Julie Rayes, Zoltan Nagy, Neil V. Morgan

TET3 is a common epigenetic immunomodulator of pathogenic macrophages

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Abstract

Through a combination of single-cell/single-nucleus RNA-sequencing (sc/snRNA-seq) data analysis, immunohistochemistry, and primary macrophage studies, we have identified pathogenic macrophages characterized by TET3 overexpression (Toe-Macs) in three major human diseases associated with chronic inflammation: metabolic dysfunction-associated steatohepatitis (MASH), non-small cell lung cancer (NSCLC), and endometriosis. These macrophages are induced by common factors present in the disease microenvironment (DME). Crucially, the universal reliance on TET3 overexpression among these macrophages enables their selective elimination as a single population, irrespective of heterogeneity in other molecular markers. In mice, depleting these macrophages via myeloid-specific Tet3 knockout markedly mitigates disease progression and the therapeutic effects are recapitulated pharmacologically using a TET3-specific small molecule degrader. Through an unexpected mode of action, TET3 epigenetically regulates expression of multiple genes key to the generation and maintenance of an inflammatory/immunosuppressive DME. We propose that Toe-Macs are a unifying feature of pathogenic macrophages that could be therapeutically targeted to treat MASH, NSCLC, endometriosis, and potentially other chronic inflammatory diseases.

Authors

Beibei Liu, Yangyang Dai, Zixin Wang, Jiahui Song, Yushu Du, Haining Lv, Stefania Bellone, Yang-Hartwich Yang, Andrew Kennedy, Songying Zhang, Muthukumaran Venkatachalapathy, Yulia V. Surovtseva, Penghua Wang, Gordon G. Carmichael, Hugh S. Taylor, Xuchen Zhang, Da Li, Yingqun Huang

Overexpression of the signaling-coordinator GAB2 can play an important role in Acute Myeloid Leukemia progression

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Abstract

Mutations that initiate AML can cause clonal expansion without transformation (“clonal hematopoiesis”). Cooperating mutations, usually in signaling genes, are needed to cause overt disease, but these may require a specific “fitness state” to be tolerated. Here, we show that nearly all AMLs arising in a mouse model expressing two common AML initiating mutations (Dnmt3aR878H and Npm1cA) acquire a single copy amplification of chromosome 7, followed by activating mutations in signaling genes. We show that overexpression of a single gene on chromosome 7 (Gab2, which coordinates signaling pathways) is tolerated in the presence of the Npm1cA mutation, can accelerate the development of AML, and is important for survival of fully transformed AML cells. GAB2 is likewise overexpressed in many human AMLs with mutations in NPM1 and/or signaling genes, and also in Acute Promyelocytic Leukemia initiated by PML::RARA; the PML::RARA fusion protein may activate GAB2 by directly binding to its 5′ flanking region. A similar pattern of GAB2 overexpression preceding mutations in signaling genes has been described in other human malignancies. GAB2 overexpression may represent an oncogene-driven adaptation that facilitates the action of signaling mutations, suggesting an important (and potentially targetable) “missing link” between the initiating and progression mutations associated with AML.

Authors

Michael H. Kramer, Stephanie N. Richardson, Yang Li, Tiankai Yin, Nichole M. Helton, Daniel R. George, Michelle Cai, Sai Mukund Ramakrishnan, Casey D.S. Katerndahl, Christopher A. Miller, Timothy J. Ley

Differential BK channel potentiation by vanzacaftor enantiomers enables therapy for modulator-ineligible people with cystic fibrosis

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Abstract

Authors

Nathalie Baumlin, Sumedha Gunewardena, Scott H. Randell, Frank Horrigan, Matthias Salathe

Serum- and glucocorticoid-induced kinase 3 orchestrates glucocorticoid signaling to facilitate chromatin remodeling during murine adipogenesis

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Abstract

Elevated glucocorticoid (GC) levels are common in conditions such as aging, chronic stress, Cushing syndrome, and GC therapy. While GCs suppress inflammation through the glucocorticoid receptor (GR), they also cause metabolic side effects. Investigating alternative pathways beyond GR activation is crucial for reducing these side effects. Our phosphoproteomics analysis revealed that glucocorticoid exposure promotes phosphorylation at the RxxS motifs of multiple proteins in preadipocytes, including those mediated by Serum- and glucocorticoid-induced kinase 3 (SGK3). SGK3 is a key mediator of glucocorticoid-induced adipogenesis, as shown by impaired adipogenesis following SGK3 inhibition or genetic ablation. Sgk3 knockout mice were resistant to glucocorticoid- or high-fat diet-induced obesity, and PROTAC targeting SGK3 reduced adipogenesis in both obese mice and a thyroid eye disease cell line. Mechanistically, SGK3 translocated to the nucleus upon glucocorticoid stimulation, interacted with and phosphorylated the BRG1 subunit of the BAF complex, and prevented BRG1 degradation, promoting chromatin remodeling necessary for adipogenesis. These findings highlight SGK3 as a potential therapeutic target to mitigate metabolic side effects of elevated glucocorticoid levels.

Authors

Qilong Chen, Jialu Guo, Yuyi Liu, Tai Du, Jiapei Liu, Yuyao Zhang, Yuming Dai, Mengdi Zhang, Ziqian Zhou, Qiyang Zhang, Caixia Wei, Qiurong Ding, Jun Qin, Qiwei Zhai, Ju Qiu, Mengle Shao, Fang Zhang, Alexander A. Soukas, Ben Zhou

Jab1 promotes immune evasion and progression in acute myeloid leukemia models under oxidative stress

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Abstract

Acute myeloid leukemia (AML) is the most common hematological malignancy. Leukemia stem cells exhibit high levels of oxidative stress, with reactive oxygen species (ROS) being the primary products of this stress, inducing the expression of Jab1. Previous studies have demonstrated that Jab1, as a transcriptional coactivator of c-JUN, promotes the malignant progression of AML under oxidative stress. However, its role in immune evasion is still under investigation. Here, we observed that knocking out Jab1 reduced the expression of immune checkpoints in vivo, effectively overcame the immune evasion of AML. Interestingly, the deletion of Jab1 had no impact on the maturation of normal hematopoietic cells in mice. Mechanistically, Jab1 directly activated IGF2BP3 by driving the transcription factor c-JUN, consequently modulated the m6A modification of LILRB4 mRNA and promoted immune evasion in AML. Finally, CSN5i-3 effectively disrupted the signaling pathway mediated by Jab1, thereby restoring cellular immune surveillance and halting the progression of AML. Thus, our results highlight the functional role of Jab1 in supporting AML survival and support the development of targeted therapeutic strategies.

Authors

Nan Zhang, Qian Wang, Guopeng Chen, Li Liu, Zhiying Wang, Linlu Ma, Yuxing Liang, Jinxian Wu, Xinqi Li, Xiaoyan Liu, Fuling Zhou

An IFN/STAT1/CYBB Axis Defines Protective Plasmacytoid DC to Neutrophil Crosstalk in Aspergillus fumigatus - Infected mice

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Abstract

Aspergillus fumigatus is the most common cause of invasive aspergillosis (IA), a devastating infection in immunocompromised patients. Plasmacytoid dendritic cells (pDCs) regulate host defense against IA by enhancing neutrophil antifungal properties in the lung. Here, we define the pDC activation trajectory during A. fumigatus infection and the molecular events that underlie the protective pDC - neutrophil crosstalk. Fungus-induced pDC activation begins after bone marrow egress and results in pDC-dependent regulation of lung type I and type III IFN levels. These pDC-derived products act on type I and type III IFN receptor-expressing neutrophils and control neutrophil fungicidal activity and reactive oxygen species production via STAT1 signaling in a cell-intrinsic manner. Mechanistically, neutrophil STAT1 signaling regulates the transcription and expression of Cybb, which encodes one of five NADPH oxidase subunits. Thus, pDCs regulate neutrophil-dependent immunity against inhaled molds by controlling the local expression of a subunit required for NADPH oxidase assembly and activity in the lung.

Authors

Yahui Guo, Mariano A. Aufiero, Kathleen A.M. Mills, Simon A. Grassmann, Hyunu Kim, Mergim Gjonbalaj, Paul Zumbo, Audrey Billips, Katrina B. Mar, Yao Yu, Laura Echeverri Tirado, Lena Heung, Amariliz Rivera, Doron Betel, Joseph C. Sun, Tobias M. Hohl

CBFβ-SMMHC–driven leukemogenesis requires enhanced RUNX1-DNA binding affinity in mice

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Abstract

The leukemia fusion gene CBFB-MYH11 requires RUNX1 for leukemogenesis, but the underlying mechanism is unclear. By in vitro studies, we found that CBFβ-SMMHC, the chimeric protein encoded by CBFB-MYH11, could enhance the binding affinity between RUNX1 and its target DNA. Increased RUNX1-DNA binding was also observed in myeloid progenitor cells from mice expressing CBFβ-SMMHC. Moreover, only CBFβ-SMMHC variants able to enhance the DNA binding affinity by RUNX1 could induce leukemia in mouse models. Marked transcriptomic changes, affecting genes associated with inflammatory response and target genes of CBFA2T3, were observed in mice expressing leukemogenic CBFβ-SMMHC variants. Finally, we show that CBFβ-SMMHC could not induce leukemia in mice with a Runx1-R188Q mutation, which reduces RUNX1 DNA binding but not affecting its interaction with CBFβ-SMMHC or its sequestration to cytoplasm by CBFβ-SMMHC. Our data suggest that, in addition to binding RUNX1 to regulate gene expression, enhancing RUNX1 binding affinity to its target DNA is an important mechanism by which CBFβ-SMMHC contributes to leukemogenesis, highlighting RUNX1–DNA interaction as a potential therapeutic target in inv(16) AML.

Authors

Tao Zhen, Yaqiang Cao, Tongyi Dou, Yun Chen, Guadalupe Lopez, Ana Catarina Menezes, Xufeng Wu, John Hammer, Jun Cheng, Lisa Garrett, Stacie Anderson, Martha Kirby, Stephen Wincovitch, Bayu Sisay, Abdel G. Elkahloun, Di Wu, Lucio H. Castilla, Wei Yang, Jiansen Jiang, Keji Zhao, Paul P. Liu

BRD4 inhibition leads to MDSC apoptosis and enhances checkpoint blockade therapy

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BRD4 is an epigenetic reader protein that regulates oncogenes such as myc in cancer. However, its additional role in shaping immune responses via regulation of inflammatory and myeloid cell responses is not yet fully understood. This work further characterized the multifaceted role of BRD4 in anti-tumor immunity. NanoString gene expression analysis of EMT6 tumors treated with a BRD4 inhibitor identified a reduction in myeloid gene expression signatures. Additionally, BRD4 inhibition significantly reduced myeloid derived suppressor cells (MDSC) in the spleens and tumors of mice in multiple tumor models and also decreased the release of tumor-derived MDSC growth and chemotactic factors. Pharmacologic inhibition of BRD4 in MDSC induced apoptosis and modulated expression of apoptosis regulatory proteins. A BRD4-myeloid specific knockout model suggested that the dominant mechanism of MDSC reduction after BRD4 inhibition was primarily through a direct effect on MDSC. BRD4 inhibition enhanced anti-PD-L1 therapy in the EMT6, 4T1, and LLC tumor models, and the efficacy of the combination treatment was dependent on CD8+ T cells and on BRD4 expression in the myeloid compartment. These results identify BRD4 as a regulator of MDSC survival and provide evidence to further investigate BRD4 inhibitors in combination with immune based therapies.

Authors

Himanshu Savardekar, Andrew Stiff, Alvin Liu, Robert Wesolowski, Emily Schwarz, Ian C. Garbarine, Megan C. Duggan, Sara Zelinskas, Jianying Li, Gabriella Lapurga, Alexander Abreo, Lohith Savardekar, Ryan Parker, Julia Sabella, Mallory J. DiVincenzo, Brooke Benner, Steven H. Sun, Dionisia Quiroga, Luke Scarberry, Gang Xin, Anup Dey, Keiko Ozato, Lianbo Yu, Merve Hasanov, Debasish Sundi, Richard C. Wu, Kari L. Kendra, William E. Carson III

Inverted chimeric RNAi molecules synergistically co-target MYC and KRAS in KRAS-driven cancers

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Mutant KRAS has been implicated in driving a quarter of all cancer types. Although inhibition of the KRASG12C mutant protein has shown clinical promise, there is still a need for therapies that overcome resistance and target non-KRASG12C mutations. KRAS activates downstream MYC, which is also a challenging-to-drug oncoprotein. We have developed an “inverted” RNAi molecule with the passenger strand of a MYC-targeting siRNA fused to the guide strand of a KRAS-targeting siRNA. The chimeric molecule simultaneously inhibits KRAS and MYC, showing marked improvements in efficacy beyond the individual siRNA components. This effect is mediated by 5’-dT overhangs following endosomal metabolism. The synergistic RNAi activity led to a >10-40-fold improvement in inhibiting cancer viability in vitro. When conjugated to an epidermal growth factor receptor (EGFR)-targeting ligand, the chimeric siRNA was delivered to and internalized by tumor cells. As compared with individual targeting siRNAs, the chimeric design resulted in considerably improved metabolic stability in tumors, enhanced silencing of both oncogenes, and reduced tumor progression in multiple cancer models. This inverted chimeric design establishes proof-of-concept for ligand-directed, dual-silencing of KRAS and MYC in cancer and constitutes an innovative molecular strategy for co-targeting any two genes of interest, which has broad implications.

Authors

Yogitha S Chareddy, Hayden P. Huggins, Snehasudha S Sahoo, Lyla Stanland, Christina Gutierrez-Ford, Kristina M. Whately, Lincy Edatt, Salma H Azam, Matthew C. Fleming, Jonah Im, Alessandro Porrello, Imani Simmons, Jillian L. Perry, Albert A. Bowers, Martin Egli, Chad V. Pecot

The protein deacetylase SIRT2 exerts metabolic control over adaptive β cell proliferation

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Abstract

Selective and controlled expansion of endogenous β-cells has been pursued as a potential therapy for diabetes. Ideally, such therapies would preserve feedback control of β-cell proliferation to avoid excessive β-cell expansion. Here, we identified a regulator of β-cell proliferation whose inactivation results in controlled β-cell expansion: the protein deacetylase Sirtuin 2 (SIRT2). Sirt2 deletion in β-cells of mice increased β-cell proliferation during hyperglycemia with little effect in homeostatic conditions, indicating preservation of feedback control of β-cell mass. SIRT2 restrains proliferation of human islet β-cells, demonstrating conserved SIRT2 function. Analysis of acetylated proteins in islets treated with a SIRT2 inhibitor revealed that SIRT2 deacetylates enzymes involved in oxidative phosphorylation, dampening the adaptive increase in oxygen consumption during hyperglycemia. At the transcriptomic level, Sirt2 inactivation has context-dependent effects on β-cells, with Sirt2 controlling how β-cells interpret hyperglycemia as a stress. Finally, we provide proof-of-principle that systemic administration of a GLP1-coupled Sirt2-targeting antisense oligonucleotide achieves β-cell Sirt2 inactivation and stimulates β-cell proliferation during hyperglycemia. Overall, these studies identify a therapeutic strategy for increasing β-cell mass in diabetes without circumventing feedback control of β-cell proliferation. Future work should test the extent that these findings translate to human β-cells from individuals with and without diabetes.

Authors

Matthew Wortham, Bastian Ramms, Chun Zeng, Jacqueline R. Benthuysen, Somesh Sai, Dennis P. Pollow, Fenfen Liu, Michael Schlichting, Austin R. Harrington, Bradley Liu, Thazha P. Prakash, Elaine C. Pirie, Han Zhu, Siyouneh Baghdasarian, Sean T. Lee, Victor A. Ruthig, Kristen L. Wells, Johan Auwerx, Orian S. Shirihai, Maike Sander

Early CD4⁺ T-cell proliferative burst and chronic T-cell engagement impact myeloma outcomes following T-cell engager therapy

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Abstract

Authors

Alyssa M. Duffy, Anshika Goenka, Maryam I. Azeem, Azmain Taz, Sayalee V. Potdar, Sara A. Scott, Ellen Marin, Jonathan L. Kaufman, Craig C. Hofmeister, Nisha S. Joseph, Vikas A. Gupta, Sagar Lonial, Ajay K. Nooka, Madhav V. Dhodapkar, Kavita M. Dhodapkar

Elevated NR2F1 underlies the persistence of invasive disease after treatment of BRAF-mutant melanoma

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Despite the clinical success of targeted inhibitors in cutaneous melanoma, therapeutic responses are transient and influenced by the aged tumor microenvironment, and drug-tolerant residual cells seed resistance. Given the similarities between drug tolerance and cellular dormancy, we studied the dormancy marker, nuclear receptor subfamily 2 group F member 1 (NR2F1), in response to targeted therapy. We utilized BRAF-V600E inhibitors (BRAFi) plus MEK inhibitors (MEKi) in BRAF-mutant melanoma models since melanoma patients treated with this combination display minimal residual disease, but ultimately tumors relapse. Transcriptomic analysis of melanoma samples from patients treated up to 20 days with BRAFi + MEKi showed increased expression of NR2F1. Similarly, NR2F1 was highly expressed in the drug-tolerant invasive cell state of minimal residual disease in patient-derived and mouse-derived xenograft tumors on BRAFi + MEKi treatment. Overexpression of NR2F1 alone was sufficient to reduce BRAFi + MEKi effects on tumor growth in vivo as well as on cell proliferation, death, and invasion in vitro. NR2F1-overexpressing cells were enriched for hallmarks gene sets for mTORC1 signaling, and NR2F1 bound to the promoter regions of genes involved in mTORC1 signaling. These cells were sensitive to the combination of BRAFi, MEKi plus rapamycin in vitro and in vivo. Melanomas from aged mice, which are known to exhibit a decreased response to BRAFi + MEKi, displayed higher levels of NR2F1 compared to tumors from young mice. Depleting NR2F1 levels in an aged mouse melanoma model improved the response to targeted therapy. These findings show high NR2F1 expression in ‘invasive-state’ residual cells and that targeting NR2F1-high cells with mTORC1 inhibitors could improve outcomes in melanoma patients.

Authors

Manoela Tiago, Timothy J. Purwin, Casey D. Stefanski, Renaira Silva, Mitchell E. Fane, Yash Chhabra, Jelan I. Haj, Jessica L.F. Teh, Rama Kadamb, Weijia Cai, Sheera R. Rosenbaum, Vivian Chua, Nir Hacohen, Michael A. Davies, Jessie Villanueva, Inna Chervoneva, Ashani T. Weeraratna, Dan A. Erkes, Claudia Capparelli, Julio A. Aguirre-Ghiso, Andrew E. Aplin

Chromatin factor YY1 controls fetal hematopoietic stem cell migration and engraftment in mice

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The fetal liver is the primary site of hematopoietic stem cell (HSC) generation during embryonic development. However, the molecular mechanisms governing the transition of hematopoiesis from the fetal liver to the bone marrow (BM) remain incompletely understood. Here, we identify the mammalian Polycomb group (PcG) protein Yin Yang 1 (YY1) as a key regulator of this developmental transition. Conditional deletion of Yy1 in the hematopoietic system during fetal development results in neonatal lethality and depletion of the fetal HSC pool. YY1-deficient fetal HSCs exhibit impaired migration and fail to engraft in the adult BM, thereby losing their ability to reconstitute hematopoiesis. Transcriptomic analysis reveals that Yy1 knockout disrupts genetic networks controlling cell motility and adhesion in fetal hematopoietic stem and progenitor cells (HSPCs). Notably, YY1 does not directly bind the promoters of most dysregulated genes. Instead, it modulates chromatin accessibility at regulatory loci, orchestrating broader epigenetic programs essential for HSPC migration and adhesion. Together, these findings establish YY1 as a critical epigenetic regulator of fetal HSC function and provide a mechanistic framework to further decipher how temporal epigenomic configurations determine HSC fetal-to-adult transition during development.

Authors

Sahitya Saka, Zhanping Lu, Yinghua Wang, Peng Liu, Deependra K. Singh, Junki P. Lee, Carmen G. Palii, Tyler R. Alvarez, Anna L. F. V. Assumpção, Xiaona You, Jing Zhang, Marjorie Brand, Michael L. Atchison, Xuan Pan