To identify genetic dependencies and hence uncover treatment targets for diffuse intrinsic pontine glioma (DIPG), Duchatel et al. employed a multiomic analysis pipeline that uncovered PIK3CA as targetable molecular dependency across DIPG patient models, highlighting the therapeutic potential of the blood-brain barrier penetrant PI3K inhibitor paxalisib. The cover art presents a model whereby the connectivity of these cancers can be harnessed using integrated technologies to identify potential therapeutic strategies. Image credit: somersault18:24.
Mediator kinases CDK19 and CDK8, pleiotropic regulators of transcriptional reprogramming, are differentially regulated by androgen signaling but both kinases are upregulated in castration-resistant prostate cancer (CRPC). Genetic or pharmacological inhibition of CDK8 and CDK19 reverses the castration-resistant phenotype and restores the sensitivity of CRPC xenografts to androgen deprivation in vivo. Prolonged CDK8/19 inhibitor treatment combined with castration not only suppresses the growth of CRPC xenografts but also induces tumor regression and cures. Transcriptomic analysis revealed that Mediator kinase inhibition amplifies and modulates the effects of castration on gene expression, disrupting CRPC adaptation to androgen deprivation. Mediator kinase inactivation in tumor cells also affects stromal gene expression, indicating that Mediator kinase activity in CRPC molds the tumor microenvironment. The combination of castration and Mediator kinase inhibition downregulates the MYC pathway, and Mediator kinase inhibition suppresses a MYC-driven CRPC tumor model even without castration. CDK8/19 inhibitors show efficacy in patient-derived xenograft models of CRPC, and a gene signature of Mediator kinase activity correlates with tumor progression and overall survival in clinical samples of metastatic CRPC. These results indicate that Mediator kinases mediate androgen-independent in vivo growth of CRPC, supporting the development of CDK8/19 inhibitors for the treatment of this presently incurable disease.
Jing Li, Thomas A. Hilimire, Liu Yueying, Lili Wang, Jiaxin Liang, Balázs Győrffy, Vitali Sikirzhytski, Hao Ji, Li Zhang, Chen Cheng, Xiaokai Ding, Kendall R. Kerr, Charles E. Dowling, Alexander A. Chumanevich, Zachary T. Mack, Gary P. Schools, Chang-uk Lim, Leigh Ellis, Xiaolin Zi, Donald C. Porter, Eugenia V. Broude, Campbell McInnes, George Wilding, Michael B. Lilly, Igor B. Roninson, Mengqian Chen
Aberrant expression of ETS transcription factors characterizes numerous human malignancies. Many of these proteins, including EWS::FLI1 and EWS::ERG fusions in Ewing sarcoma (EwS) and TMPRSS2::ERG in prostate cancer (PCa), drive oncogenic programs via binding to GGAA repeats. We report here that both EWS::FLI1 and ERG bind and transcriptionally activate GGAA-rich pericentromeric heterochromatin. The respective pathogen-like HSAT2 and HSAT3 RNAs, together with LINE, SINE, ERV and other repeat transcripts, are expressed in EwS and PCa tumors, secreted in extracellular vesicles (EVs) and are highly elevated in plasma of EwS patients with metastatic disease. High HSAT2,3 levels in EWS::FLI1 or ERG expressing cells and tumors were associated with induction of G2/M checkpoint, mitotic spindle and DNA damage programs. These programs were also activated in EwS EV-treated fibroblasts, coincident with accumulation of HSAT2,3 RNAs, proinflammatory responses, mitotic defects, and senescence. Mechanistically, HSAT2,3-enriched cancer EVs induced cGAS-TBK1 innate immune signaling and formation of cytosolic granules positive for double-strand RNAs, RNA-DNA and cGAS. Hence, aberrantly expressed ETS proteins derepress pericentromeric heterochromatin, yielding pathogenic RNAs which transmit genotoxic stress and inflammation to local and distant sites. Monitoring HSAT2,3 plasma levels and preventing their dissemination may thus improve therapeutic strategies and blood-based diagnostics.
Peter Ruzanov, Valentina Evdokimova, Manideep C. Pachva, Alon Minkovich, Zhenbo Zhang, Sofya Langman, Hendrik Gassmann, Uwe Thiel, Marija Orlic-Milacic, Syed H. Zaidi, Vanya Peltekova, Lawrence E. Heisler, Manju Sharma, Michael E. Cox, Trevor D. McKee, Mark Zaidi, Eve Lapouble, John D. McPherson, Olivier Delattre, Laszlo Radvanyi, Stefan E.G. Burdach, Lincoln D. Stein, Poul H. Sorensen
G protein-coupled receptor 37-like 1 (GPR37L1) is an orphan GPCR with largely unknown functions. Here we report that Gpr37l1/GRP37L1 ranks among the most highly expressed GPCR transcripts in mouse and human dorsal root ganglia (DRGs), selectively expressed in satellite glial cells (SGCs). Peripheral neuropathy induced by streptozotoxin (STZ) and paclitaxel (PTX) led to reduced GPR37L1 expression on the plasma membrane expression in mouse and human DRGs. Transgenic mice with Gpr37l1 deficiency exhibited impaired resolution of neuropathic pain symptoms following PTX and STZ-induced pain, whereas overexpression of Gpr37l1 in mouse DRGs reversed pain. GPR37L1 is co-expressed with potassium channels, including KCNJ10 (Kir4.1) in mouse SGCs and both KCNJ3 (Kir3.1) and KCNJ10 in human SGCs. GPR37L1 regulates the surface expression and function of the potassium channels. Notably, the pro-resolving lipid mediator maresin 1 (MaR1) serves as a ligand of GPR37L1 and enhances KCNJ10 or KCNJ3-mediated potassium influx in SGCs through GPR37L1. Chemotherapy suppressed KCNJ10 expression and function in SGCs, which MaR1 rescued through GPR37L1. Finally, genetic analysis revealed that the GPR37L1-E296K variant increased chronic pain risk by destabilizing the protein and impairing the protein’s function. Thus, GPR37L1 in SGCs offers a new therapeutic target for the protection of neuropathy and chronic pain.
Sangsu Bang, Changyu Jiang, Jing Xu, Sharat Chandra, Aidan McGinnis, Xin Luo, Qianru He, Yize Li, Zilong Wang, Xiang Ao, Marc Parisien, Lorenna Oliveira Fernandes de Araujo, Sahel Jahangiri Esfahani, Qin Zhang, Raquel Tonello, Temugin Berta, Luda Diatchenko, Ru-Rong Ji
Gender affirming hormone therapy (GAHT) is often prescribed to transgender (TG) adolescents to alleviate gender dysphoria, but the impact of GAHT on the growing skeleton is unclear. We found GAHT to improve trabecular bone structure via increased bone formation in young male mice and not to affect trabecular structure in female mice. GAHT modified gut microbiome composition in both male and female mice. However, fecal microbiota transfers (FMT) revealed that GAHT-shaped gut microbiome was a communicable regulator of bone structure and turnover in male, but not in female mice. Mediation analysis identified two species of Bacteroides as significant contributors to the skeletal effects of GAHT in male mice, with Bacteroides supplementation phenocopying the effects of GAHT on bone. Bacteroides have the capacity to expand Treg populations in the gut. Accordingly, GAHT expanded intestinal regulatory T cells (Tregs) and stimulated their homing to the bone marrow (BM) in male but not in female mice. Attesting to the functional relevance of Tregs, pharmacological blockade of Treg expansion prevented GAHT-induced bone anabolism. In summary, in male mice GAHT stimulated bone formation and improved trabecular structure by promoting Treg expansion via a microbiome-mediated effect. In female mice GAHT neither improved nor impaired trabecular structure.
Subhashis Pal, Xochitl Morgan, Hamid Y. Dar, Camilo Anthony Gacasan, Sanchiti Patil, Andreea Stoica, Yi-Juan Hu, M. Neale Weitzmann, Rheinallt M. Jones, Roberto Pacifici
The mammalian SUMO-targeted E3 Ubiquitin Ligase, Rnf4, has been reported to act as a regulator of DNA repair, but the importance of RNF4 as a tumor suppressor has not been tested. Using a conditional-knockout mouse model, we deleted Rnf4 in the B cell lineage to test the importance of RNF4 for growth of somatic cells. Although Rnf4 conditional-knockout B cells exhibited substantial genomic instability, Rnf4 deletion caused no increase in tumor susceptibility. In contrast, Rnf4 deletion extended the healthy lifespan of mice expressing an oncogenic c-myc transgene. Rnf4 activity is essential for normal DNA replication, and in its absence, there was a failure in ATR-CHK1 signaling of replication stress. Factors that normally mediate replication fork stability, including members of the Fanconi Anemia gene family and the helicases, PIF1 and RECQL5, showed reduced accumulation at replication forks in the absence of RNF4. RNF4 deficiency also resulted in an accumulation of hyper-SUMOylated proteins in chromatin, including members of the SMC5/6 complex, which contributes to replication failure by a mechanism dependent on RAD51. These findings indicate that RNF4, which shows increased expression in multiple human tumor types, is a potential target for anti-cancer therapy, especially in tumors expressing c-myc.
Joonyoung Her, Haiyan Zheng, Samuel F. Bunting
JCI celebrates a century of publishing scientific discoveries with a special collection highlighting major innovations in medicine and key contributing mechanistic studies.
The lungs are regularly exposed to airborne irritants, pathogens, and other sources of inflammation that cause injury to the lung epithelium and its underlying structure. Repair and regeneration are essential for healthy lung function throughout life, yet these processes can also influence development and progression of acute and chronic conditions. Series editor Suzanne Herold developed this review series on lung inflammatory injury and tissue repair to reveal the many cell populations involved in normal and aberrant reparative responses. Ranging from discussion of lung stroma and vasculature to adaptive and innate immune systems, the reviews in this series describe the many complex mechanisms that influence pathogen-, inflammation-, and aging-driven injury to the lung and can contribute to aberrant healing, resolution of inflammation, and fibrosis. Reviews also discuss a wide range of potential therapies targeting injury and repair processes that represent promising progress toward better clinical options for patients with acute and chronic lung conditions.
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