Cell biology
Abstract
Direct interaction of RAS with the PI3K p110α subunit mediates RAS-driven tumor development: however, it is not clear how p110α/RAS-dependant signaling mediates interactions between tumors and host tissues. Here, using a murine tumor cell transfer model, we demonstrated that disruption of the interaction between RAS and p110α within host tissue reduced tumor growth and tumor-induced angiogenesis, leading to improved survival of tumor-bearing mice, even when this interaction was intact in the transferred tumor. Furthermore, functional interaction of RAS with p110α in host tissue was required for efficient establishment and growth of metastatic tumors. Inhibition of RAS and p110α interaction prevented proper VEGF-A and FGF-2 signaling, which are required for efficient angiogenesis. Additionally, disruption of the RAS and p110α interaction altered the nature of tumor-associated macrophages, inducing expression of markers typical for macrophage populations with reduced tumor-promoting capacity. Together, these results indicate that a functional RAS interaction with PI3K p110α in host tissue is required for the establishment of a growth-permissive environment for the tumor, particularly for tumor-induced angiogenesis. Targeting the interaction of RAS with PI3K has the potential to impair tumor formation by altering the tumor-host relationship, in addition to previously described tumor cell–autonomous effects.
Authors
Miguel Manuel Murillo, Santiago Zelenay, Emma Nye, Esther Castellano, Francois Lassailly, Gordon Stamp, Julian Downward
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
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
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
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
Abstract
Inactivation of cyclin-dependent kinase 12 (CDK12) defines an immunogenic molecular subtype of prostate cancer characterized by genomic instability and increased intratumoral T cell infiltration. This study reveals that genetic or pharmacologic inactivation of CDK12 and its paralog CDK13 robustly activates stimulator of interferon genes (STING) signaling across multiple cancer types. Clinical cohort analysis shows that reduced CDK12/13 expression correlates with improved survival and response to immune checkpoint blockade (ICB). Mechanistically, CDK12/13 depletion or targeted degradation induces cytosolic nucleic acid release, triggering STING pathway activation. CDK12/13 degradation delays tumor growth and synergizes with anti-PD1 therapy in syngeneic tumor models, enhancing STING activity and promoting CD8+ T cell infiltration and activation within tumors. Notably, the anti-tumor effects of this combination require STING signaling and functional CD8+ T cells. These findings establish STING activation as the key driver of T cell infiltration and the immune-hot tumor microenvironment in CDK12 mutant cancers, suggesting that dual CDK12/13 inhibitors and degraders activate anti-tumor immunity and potentiate responses to immunotherapies.
Authors
Yi Bao, Yu Chang, Jean Tien, Gabriel Cruz, Fan Yang, Rahul Mannan, Somnath Mahapatra, Radha Paturu, Xuhong Cao, Fengyun Su, Rui Wang, Yuping Zhang, Mahnoor Gondal, Jae Eun Choi, Jonathan K. Gurkan, Stephanie J. Miner, Dan R. Robinson, Yi-Mi Wu, Licheng Zhou, Zhen Wang, Ilona Kryczek, Xiaoju Wang, Marcin Cieslik, Yuanyuan Qiao, Alexander Tsodikov, Weiping Zou, Ke Ding, Arul M. Chinnaiyan
Abstract
The cystine-xCT transporter–glutathione (GSH)–GPX4 axis is the canonical pathway protecting cells from ferroptosis. While GPX4-targeting ferroptosis-inducing compounds (FINs) act independently of mitochondria, xCT-targeting FINs require mitochondrial lipid peroxidation, though the mechanism remains unclear. Since cysteine is also a precursor for coenzyme A (CoA) biosynthesis, here, we demonstrated that CoA supplementation selectively prevented ferroptosis triggered by xCT inhibition by regulating the mitochondrial thioredoxin system. Our data showed that CoA regulated the in vitro enzymatic activity of mitochondrial thioredoxin reductase (TXNRD2) by covalently modifying the thiol group of cysteine (CoAlation) on Cys-483. Replacing Cys-483 with alanine on TXNRD2 abolished its enzymatic activity and ability to protect cells against ferroptosis. Targeting xCT to limit cysteine import and, therefore, CoA biosynthesis reduced CoAlation on TXNRD2. Furthermore, the fibroblasts from patients with disrupted CoA metabolism demonstrated increased mitochondrial lipid peroxidation. In organotypic brain slice cultures, inhibition of CoA biosynthesis led to an oxidized thioredoxin system, increased mitochondrial lipid peroxidation, and loss of cell viability, which were all rescued by ferrostatin-1. These findings identified CoA-mediated post-translational modification to regulate the thioredoxin system as an alternative ferroptosis protection pathway with potential clinical relevance for patients with disrupted CoA metabolism.
Authors
Chao-Chieh Lin, Yi-Tzu Lin, Ssu-Yu Chen, Yasaman Setayeshpour, Yubin Chen, Denise E. Dunn, Taylor Nguyen, Alexander A. Mestre, Adrija Banerjee, Lalitha Guruprasad, Erik J. Soderblom, Guo-Fang Zhang, Chen-Yong Lin, Valeriy Filonenko, Suh Young Jeong, Scott R. Floyd, Susan J. Hayflick, Ivan Gout, Jen-Tsan Chi
Abstract
Pathogenic variants in the gene TMPRSS3 are a common cause of hearing loss in humans, although the causal mechanisms remain unknown. Previous work has shown that Tmprss3Y260X/Y260X mice exhibit normal hair cell development, mechanosensory transduction, and spiral ganglion patterning, but experience rapid hair cell death from P12 to P14 at the onset of hearing. Here, we demonstrate that Tmprss3Y260X/Y260X mice display an early and temporary spike in endocochlear potential (EP) prior to the onset of hair cell death. In vitro experiments with cochlear explants from Tmprss3Y260X/Y260X mice and in vivo studies with Tmprss3Y260X/Y260X mice crossed with two different mutant models that lacked EP generation promoted hair cell survival. Furthermore, systemic administration of furosemide, a drug that reduces EP in vivo, reduced hair cell death in Tmprss3Y260X/Y260X mice. These findings suggest that extracellular factors, including EP, play a role in TMPRSS3-related hair cell survival and hearing loss, and suggest that modulating EP could be a therapeutic strategy.
Authors
A. Eliot Shearer, Yuan-Siao Chen, Stephanie L. Rouse, Xiaohan Wang, Janmaris Marin Fermin, Kevin T.A. Booth, Jasmine Moawad, Nicole Bianca Libiran, Jinan Li, Hae-Young Kim, Michael Hoa, Rafal Olszewski, Jing-Yu Lei, Ernesto Cabrera, Douglas J. Totten, Bo Zhao, Jeffrey R. Holt, Rick F. Nelson
Abstract
The germinal center (GC) dark zone (DZ) and light zone (LZ) represent distinct anatomical regions in lymphoid tissue where B-cell proliferation, immunoglobulin diversification, and selection are coordinated. Diffuse Large B-cell Lymphomas (DLBCL) with DZ-like gene expression profiles exhibit poor outcomes, though reasons are unclear and are not directly related to proliferation. Physiological DZs exhibit an exclusion of T-cells, prompting exploration for whether T-cell paucity contributes to DZ-like DLBCL. We used spatial transcriptomic approaches to achieve higher resolution of T-cell spatial heterogeneity in the GC and to derive potential pathways that underlie T-cell exclusion. We showed that T-cell exclusion from the DZ was linked to DNA damage response (DDR) and chromatin compaction molecular features characterizing the spatial DZ signature, and that these programs were independent of AID deaminase activity. As ATR is a key regulator of DDR, we tested its role in the T-cell inhibitory DZ transcriptional imprint. ATR inhibition reversed not only the DZ transcriptional signature but also DZ T-cell exclusion in DZ-like DLBCL in vitro microfluidic models and in in vivo samples of murine lymphoid tissue. These findings highlight that ATR activity underpins a physiological scenario of immune silencing. ATR inhibition may reverse the immune silent state and enhance T-cell based immunotherapy in aggressive lymphomas with GC DZ-like characteristics.
Authors
Valeria Cancila, Giorgio Bertolazzi, Allison S.Y. Chan, Giovanni Medico, Giulia Bastianello, Gaia Morello, Daniel Paysan, Clemence Lai, Liang Hong, Girija Shenoy, Patrick W. Jaynes, Giovanna Schiavoni, Fabrizio Mattei, Silvia Piconese, Maria V. Revuelta, Francesco Noto, Luca Businaro, Adele De Ninno, Ilenia Cammarata, Fabio Pagni, Saradha Venkatachalapathy, Sabina Sangaletti, Arianna Di Napoli, Giada Cicio, Davide Vacca, Silvia Lonardi, Luisa Lorenzi, Andrés J.M. Ferreri, Beatrice Belmonte, Min Liu, Manikandan Lakshmanan, Michelle S.N. Ong, Biyan Zhang, Tingyi See, Kong-Peng Lam, Gabriele Varano, Mario P. Colombo, Silvio Bicciato, Giorgio Inghirami, Leandro Cerchietti, Maurilio Ponzoni, Roberta Zappasodi, Evelyn Metzger, Joseph Beechem, Fabio Facchetti, Marco Foiani, Stefano Casola, Anand D. Jeyasekharan, Claudio Tripodo
Abstract
Nuclear size is crucial for cellular functions and often increases with malignancy. Irregular nuclei are linked to aggressive tumors, driven by genetic and epigenetic changes. However, the precise mechanisms controlling nuclear size are still not fully understood. In this study, we demonstrated that cancer-associated speckle-type POZ protein (SPOP) mutations enlarged nuclear size by reducing the protein level of lamin B2 (LMNB2), a key nuclear integrity protein. Mechanistically, SPOP bound to LMNB2 and promoted its mono-ubiquitination at lysine-484, which protected it from degradation by the E3 ubiquitin ligase WD repeat domain 26. SPOP mutations disrupted this process, leading to reduced LMNB2 levels and impaired nuclear envelope (NE) integrity. This compromised NE was more vulnerable to damage from farnesyltransferase inhibitors (FTIs), causing nuclear rupture in SPOP-mutant tumor cells. This study identified SPOP as a positive regulator of nuclear size; the findings suggest tumors with SPOP mutations may be vulnerable to FTI-based therapies.
Authors
Zixi Wang, Lei Li, Qi Ye, Yuzeshi Lei, Mingming Lu, Leihong Ye, Jialu Kang, Wenyue Huang, Shan Xu, Ke Wang, Jing Liu, Yang Gao, Chenji Wang, Jian Ma, Lei Li
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ISSN: 0021-9738 (print), 1558-8238 (online)