Cell biology
Abstract
Our research uncovers a new role for ATR in responding to extracellular matrix (ECM) stiffness and promoting epithelial-to-mesenchymal transition (EMT) and metastasis. ATR, when deubiquitinated and upregulated by USP21 under enhanced ECM stiffness conditions, phosphorylates the nuclear protein SUN2 which promotes β-catenin nuclear translocation and EMT. ATM mediated EMT promotes polymorphonuclear myeloid-derived suppressor cell recruitment and inhibits CD103+ dendritic cells, fostering an immunosuppressive tumor milieu. ATR inhibition disrupts this malignant cascade by promoting mesenchymal to epithelial transition to enhance anti-tumor immunity and mitigate metastases. Consistently, circulating HLA-DR+ dendritic cells were also enhanced following treatment with the ATR inhibitor, Berzosertib, in patients with therapeutically resistant early-stage breast cancer. Our data suggest that ATR targeted therapy may be optimized by considering both DNA damage dependent and EMT inducing effects of ATR.
Authors
Xinyi Tu, Xiangyu Zeng, Yaoliang Sun, Yaobin Ouyang, Lingling Zhu, Ping Yin, Kevin D. Pavelko, Roberto A. Leon-Ferre, Yanxia Jiang, Haidong Dong, Jodi M. Carter, Shouhai Zhu, Jann N. Sarkaria, Liewei Wang, Jinzhou Huang, Kuntian Luo, Yiqun Han, Zheming Wu, Zhenkun Lou, Robert W. Mutter
Abstract
ATR inhibition is under evaluation for treatment of high-grade serous ovarian cancer (HGSOC) to reverse acquired resistance to poly (ADP-ribose) polymerase (PARP) inhibition and to exacerbate chemotherapy-induced replicative stress. Here, we define PTEN deficiency as a predictive biomarker for response to ATR inhibition, as monotherapy and in combination with PARP inhibition or gemcitabine. In response to ATR inhibition and compared to PTEN-proficient cells, PTEN-deficient cells are prone to (1) uncoupling of DNA polymerase and helicase activities, leading to excessive single-stranded DNA and replication stress; (2) cytoplasmic sequestration of CHK1, compromising cell cycle checkpoint control with reduced compensatory effects by ATM and DNA-PK, leading to mitotic catastrophe; and (3) reduced RAD51 recruitment, exacerbating replication fork instability, also leading to lethality. Retrospective analyses demonstrate that patients with HGSOC expressing low PTEN levels experience greater clinical benefit on ATR inhibitor-based trials than those with high levels. These results justify prospective trials evaluating ATR inhibition as a therapeutic strategy for PTEN-deficient tumors.
Authors
Jie Hao, Bose Kochupurakkal, Timothy B. Branigan, Ozge Sezin Somuncu, Renyan Liu, Heta Jadhav, Alexandre Andre B.A. da Costa, Yuqing Jiao, Jenny Z. Yu, David B. Martignetti, Golbahar Sadatrezaei, Sirisha Mukkavalli, Prafulla C. Gokhale, Su-Chun Cheng, Steven J. Skates, Dimitrios Nasioudis, Panagiotis A. Konstantinopoulos, Joyce F. Liu, Stephanie L. Gaillard, Robert L. Giuntoli II, Lainie P. Martin, Janos L. Tanyi, Nawar Latif, Ian S. Heller, Fiona Simpkins, Kalindi Parmar, Alan D. D'Andrea, Geoffrey I. Shapiro
Abstract
Heterogeneous degeneration of the retinal pigment epithelium (RPE) leads to irreversible blindness in diseases associated with macular atrophy. However, the underlying mechanisms of regional RPE degeneration remain poorly understood. To address this gap, this study identifies a peripheral RPE subpopulation through spatial, transcriptomic, and functional analyses, thereby contributing to the understanding of the heterogeneity of degenerative RPE cells. Specifically, omics analyses in human and macaque RPE reveal a peripheral RPE cell population with high SERPINE3 expression, while SERPINE3-GFP knock-in mice show comparable expression patterns. In addition, SMART-seq2 analysis further distinguishes transcriptomic profiles between GFP-positive and GFP-negative RPE cells. Under oxidative stress, SERPINE3 expression increases, and GFP-positive cells exhibit improved survival and reentry into the cell cycle. Notably, genetic studies indicate that SERPINE3 is essential for the oxidative stress resistance of GFP-positive cells. Moreover, loss of SERPINE3 results in regional RPE degeneration and increased microglial accumulation in aged mice. Mechanistically, proteinase screening and co-immunoprecipitation indicate that SERPINE3 targets Caspase-1. Importantly, delivery of SERPINE3 via AAV-Serpine3 partially reduces RPE degeneration in an oxidative damage model. These findings advance the understanding of RPE heterogeneous degeneration and highlight SERPINE3 as a protective factor with therapeutic potential for macular atrophy.
Authors
Huirong Li, Takerra Johnson-Stephenson, Vincent P. Kunze, Wei Yan, David M. McGaughey, Temesgen D. Fufa, Koray Dogan Kaya, Ashley M. Rasys, Davide Ortolan, Dominik Reichert, Congxiao Zhang, Ruchi Sharma, Lijin Dong, Bin Guan, Brian P. Brooks, Tiansen Li, Wei Li, Wencan Wu, Kapil Bharti, Robert B. Hufnagel
Abstract
Pancreatic cancer remains a devastating disease with limited therapeutic options. Accumulating evidence has shown that cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs), the predominant cells in the pancreatic cancer (PDAC) tumor microenvironment (TME), hinder anti-tumor immunity. However, the role of extracellular vesicles (EVs) in such process is poorly understood. In this study, using human bone-marrow-derived monocytes and PDAC tumor cells, we show that tumor cell-derived EVs (TC-EVs) induced monocyte differentiation towards M2-like immunosuppressive CD200R+/PD-L1+/HLA-DR- macrophages that express ALOX15b, that we identify as an independent PDAC poor-prognosis biomarker using a human pancreatic cancer metacohort. We also demonstrate that TC-EVs reprogram human primary PDAC CAFs, causing a fibronectin network reorganization associated with changes in extracellular matrix (ECM) composition, including alterations of the Wnt pathway elements such as SFRP1 enrichment. We further reveal that monocytes cultured on rSFRP1-enriched ECM differentiate also into M2-like immunosuppressive macrophages. Lastly, we demonstrate that both directly and indirectly TC-EVs, or rSFRP1-enriched ECM, driven differentiated macrophages hindered T-cell activation and subsequent anti-tumor activity. Our findings highlight novel, dual mechanisms of TC-EVs-mediated crosstalk, involving Alox15b+-Macrophages and SFRP1+-CAFs, that simultaneously contribute to foster the immunosuppressive ecosystem of pancreatic cancer.
Authors
Zainab Hussain, Claudio Montenegro, Christopher Rovera, Djamila Belghoula, Sarah simha Tubiana, Pascal Finetti, Eugenie Lohmann, Magda Rodrigues, Thomas Bertran, Ghislain Bidaut, Daniel Isnardon, Sophie Vasseur, Francois Bertucci, Stephane Audebert, Luc Camoin, Moacyr Rego, Richard Tomasini
Abstract
Lymphatic valves are essential for maintaining tissue fluid homeostasis, and their dysfunction leads to lymphedema, a morbid and disfiguring disease without a cure. Mechanical forces due to lymph flow are required for proper lymphatic valve development, yet it remains unclear how lymphatic endothelial cells (LECs) sense and decode mechanical signals. In this study, we identify the cell guidance semaphorin receptor plexin D1 (PLXND1) as a lymphatic mechanosensor required for lymphatic valve morphogenesis. Conditional genetic ablation of Plxnd1 in LECs caused major defects in lymphatic valve development in 2 different lymphatic vascular beds. Mechanistically, PLXND1 acted as a mechanosensor within a lymphatic mechanocomplex, initiating distinct mechanical signals and activating the lymphatic valve transcriptional program through an unconventional pathway. Screening of patients with primary lymphedema identified PLXND1 missense variants, and functional analysis established 2 pathogenic variants that selectively disrupt the ligand versus mechanosensing functions of this receptor. Variants associated with lymphedema in members of the mechanocomplex disrupted its formation, underscoring the central role of this complex in lymphatic valve biology. Our work uncovers a mechanosensing mechanism guiding lymphatic valve development, and has profound implications for the understanding and treatment of primary lymphedema in humans.
Authors
Kar-Lai Pang, Vedanta Mehta, Claire Aitken, Sara E. Dobbins, Jing Yu, Gabriele Bonetti, Adam N. Keen, Feiran Zhang, Amélie Sabine, Tatiana V. Petrova, Paul R. Riley, E. Yvonne Jones, Sandro Michelini, Matteo Bertelli, John S. Reader, Pia Ostergaard, Ellie Tzima
Abstract
MDM2 is transcriptionally activated by the ST-MYCL-Tip60 complex in virus-positive Merkel cell carcinoma (MCC). MDM2 suppresses p53 and is a rational therapeutic target. MDM2 inhibitors face an intrinsic limitation: p53 activation induces MDM2 transcription, creating a feedback loop that blunts inhibitor efficacy. We demonstrate that MDM2 degraders KTX-049 and KT-253 overcome this limitation by collapsing the p53/MDM2 negative feedback loop. KTX-049 was >100-fold more potent than the MDM2 inhibitor DS-3032 across WT p53 MCC cell lines, and this superior potency was quantitatively supported by mechanistic mathematical modeling. In vivo, KT-253 produced deep and durable tumor regressions, including complete responses in patient-derived xenograft models. Acquired resistance was strongly associated with acquisition of TP53 mutations, confirming on-target pathway pressure. These findings establish feedback architecture as a critical determinant of therapeutic response and position MDM2 degradation as a qualitatively distinct strategy that produces more durable pathway engagement than MDM2 inhibition, providing a preclinical rationale for prioritizing MDM2 degraders in WT TP53 MCC.
Authors
Varsha Ananthapadmanabhan, Simone Bruno, Leonard Vonk, Yu-Chen Cheng, Abeba Teshager, Benjamin K. Eschle, Charles L. Howarth, Joana S. Rodrigues, Julia Schnabel, Ananya Kodali, Prafulla C. Gokhale, Rujuta Kshirsagar, Susanne B. Breitkopf, Kirti Sharma, Joao A. Paulo, Yvonne Li, Andrew D. Cherniack, Franziska Michor, Yogesh Chutake, Joyoti Dey, James A. DeCaprio
Abstract
Glioblastoma is a fatal primary malignant brain tumor, with an average survival of 15 months despite surgical resection, chemotherapy, and radiation therapy. Due to the concurrent deregulation of numerous genes in glioblastoma, molecular monotherapies have not improved clinical outcomes. Evidence suggests that targeting multiple deregulated molecules is essential for better therapies; however, this is limited by the lack of suitable drugs and increased toxicity of combination therapies. To address this, we hypothesized that miRNAs, small gene-regulatory RNAs that suppress mRNA, could simultaneously inhibit multiple deregulated genes in glioblastoma, and be used for more effective therapies. We identified regulatory miRNAs — those that target several deregulated genes in glioblastoma — using a combination of PAR-CLIP screening, TCGA data analyses and an algorithm to rank target importance and miRNA therapeutic potential. We selected two tumor suppressor miRNAs, miR-340 and miR-382, and one oncogenic miRNA, miR-17 and showed that they target critical glioblastoma pathways and alter cell growth, survival, invasion, and in vivo tumor growth. We developed and successfully applied a miRNA therapeutic delivery approach using Brain Penetrating Nanoparticles combined with MRI-guided focused ultrasound and microbubbles, to inhibit established tumor growth and to extend animal survival. This strategy offers a promising approach for translating miRNA-based therapies into clinical trials for glioblastoma and other cancers.
Authors
Shekhar Saha, Ying Zhang, Myron K. Gibert Jr., Collin Dube, Farina Hanif, Elizabeth Qian Xu Mulcahy, Sylwia Bednarek, Yunan Sun, Pawel Marcinkiewicz, Xiantao Wang, Gijung Kwak, Ahsan H. Polash, Haolin Li, Kadie Hudson, Manikarna Dinda, Tapas Saha, Matthew McCord, Fadila Guessous, Nichola Cruickshanks, Rossymar Rivera Colon, Lily Dell'Olio, Rajitha Anbu, Wenjie Liu, Songy Choi, Benjamin Kefas, Pankaj Kumar, Alexander L. Klibanov, David Schiff, Jung Soo Suk, Justin Hanes, Jamie Mata, Markus Hafner, Roger Abounader
Abstract
CIC::DUX4 sarcoma (CDS) is a lethal cancer driven by a fusion between tumor suppressor Capicua (CIC) and pioneer transcription factor double homeobox 4 (DUX4). We previously generated three genetically engineered mouse models (GEMMs) of CDS with CIC::DUX4 regulated by loxP-STOP-loxP cassettes, however, all three models developed spontaneous tumors without Cre recombinase. Here, we established a next-generation GEMM of CDS (dFLEx CDS) that employs a dual recombinase (Cre + FLPE) FLEx-switch design to activate CIC::DUX4 expression and initiate sarcomagenesis in a spatially and temporally-controlled manner. Because CIC::DUX4 drives sarcoma development by activating a oncogenic transcriptional program, we performed a drug screen on human-derived CDS cell lines using a library of compounds that modulate transcription. This screen identified Minnelide, an inhibitor of RNA polymerase II-mediated transcription, as a selective inhibitor of CDS. Mechanistically, Minnelide acted through xeroderma pigmentosum type B to alter phosphorylation of RPB1, the largest subunit of RNA polymerase II. Subsequently, RPB1 underwent degradation leading to apoptosis of CDS cells. Minnelide demonstrated in vivo efficacy in dFLEx CDS GEMMs and in human CDS xenografts. As Minnelide has already been demonstrated to be safe in clinical trials, these findings nominate Minnelide as a potential therapeutic option to test in CDS patients.
Authors
MaKenna R. Browne, Axel V. Silver, Risha Banerjee, Brendan C. Dickson, Benigno Aquino, Kristianne M. Oristian, Jonathon E. Himes, Peter G. Hendrickson, David G. Kirsch
Abstract
Most mitochondrial proteins are nuclear encoded, translated in the cytosol, and imported into the mitochondria. Through gene expression analysis and functional assays, we demonstrated that mitochondrial protein import is increased in acute myeloid leukemia (AML) cells compared to normal hematopoietic cells. Increased mitochondrial protein import was positively correlated with increased mitochondrial unfolded protein response (UPRmt), a stress activated pathway of mitochondrial proteases and chaperones that maintains protein solubility and prevents the formation of toxic aggregates. The UPRmt protease LONP1 (Lon Peptidase 1) was upregulated in AML and positively correlated with increased mitochondrial protein import and UPRmt. Genetically or chemically inhibiting the LONP1 ATPase domain induced mitochondrial protein aggregation and selectively killed AML cells with high LONP1 expression while sparing AML cells with low LONP1 expression and normal hematopoietic cells in vitro and in vivo. Thus, we uncovered a critical role of the UPRmt protease LONP1 in buffering stress from mitochondrial protein import in AML.
Authors
Matthew Tcheng, Veronique Voisin, Geethu Emily Thomas, Anastasija A. Piric, Marcela Gronda, Rose Hurren, Dakai Ling, Yongran Yan, Lan Xin Zhang, Yue Feng, Ali Chegini, Nathan Duong, Ross S. Mancini, Stefan Quinn W. Currie, Zaynab Mamai, Brady Stock, Shahbaz Khan, Yulia Jitkova, Chaitra Sarathy, Edward Ayoub, Po Yee Mak, Andrea Arruda, Thomas Kislinger, Mark Reed, Bing Z. Carter, Michael Andreeff, Steven M. Kornblau, Mark D. Minden, Siavash Vahidi, Aaron D. Schimmer
Abstract
Renal water reabsorption is classically regulated by vasopressin V2 receptor (V2R) signaling through cyclic AMP and protein kinase A, driving apical accumulation of aquaporin-2 (AQP2). However, collecting duct water handling is also modulated by vasopressin-independent mechanisms. Here, we examined intracellular soluble urate as a vasopressin-independent regulator of AQP2 trafficking. Intracellular urate accumulation in collecting duct cells was mediated by enhanced apical urate uptake via GLUT9b and reduced apical urate efflux through ABCG2, triggering phosphodiesterase-4 activation, reduced cAMP, and downstream AMP-activated protein kinase (AMPK) activation. The resulting AQP2 accumulation at the apical membrane was independent of V2R signaling, required ongoing endocytosis and was associated with features of post-endocytic apical trafficking of internalized AQP2. In vivo ABCG2 inhibition with probenecid increased apical AQP2 abundance and markedly attenuated tolvaptan-induced polyuria in both wild-type and Pkd1RC/RC autosomal dominant polycystic kidney disease (ADPKD) mice in a uricase-independent manner, while preserving tolvaptan’s ADPKD-modifying efficacy. In a Phase 2 trial with tolvaptan-treated ADPKD patients, probenecid reduced urine volume and nocturia frequency. Together, these findings support a vasopressin-independent urate–AMPK–AQP2 pathway that regulates renal water handling and, in a preclinical ADPKD model, can uncouple cyst growth attenuation from the dose-limiting aquaretic effects of V2R antagonism.
Authors
Mohamad Hadla, Jean Marc Mardirossian, Daniel G. Bichet, Abdul Hamid Borghol, Georges Abboud, Ahmad Ghanem, Eduardo N. Chini, Peter C. Harris, Vicente E. Torres, Seth L. Alper, Volker Vallon, Fouad T. Chebib
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ISSN: 0021-9738 (print), 1558-8238 (online)