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Abstract

BACKGROUND Proteinuria is considered an unfavorable clinical condition that accelerates renal and cardiovascular disease. However, it is not clear whether all forms of proteinuria are damaging. Mutations in CUBN cause Imerslund-Gräsbeck syndrome (IGS), which is characterized by intestinal malabsorption of vitamin B12 and in some cases proteinuria. CUBN encodes for cubilin, an intestinal and proximal tubular uptake receptor containing 27 CUB domains for ligand binding.METHODS We used next-generation sequencing for renal disease genes to genotype cohorts of patients with suspected hereditary renal disease and chronic proteinuria. CUBN variants were analyzed using bioinformatics, structural modeling, and epidemiological methods.RESULTS We identified 39 patients, in whom biallelic pathogenic variants in the CUBN gene were associated with chronic isolated proteinuria and early childhood onset. Since the proteinuria in these patients had a high proportion of albuminuria, glomerular diseases such as steroid-resistant nephrotic syndrome or Alport syndrome were often the primary clinical diagnosis, motivating renal biopsies and the use of proteinuria-lowering treatments. However, renal function was normal in all cases. By contrast, we did not found any biallelic CUBN variants in proteinuric patients with reduced renal function or focal segmental glomerulosclerosis. Unlike the more N-terminal IGS mutations, 37 of the 41 proteinuria-associated CUBN variants led to modifications or truncations after the vitamin B12–binding domain. Finally, we show that 4 C-terminal CUBN variants are associated with albuminuria and slightly increased GFR in meta-analyses of large population-based cohorts.CONCLUSIONS Collectively, our data suggest an important role for the C-terminal half of cubilin in renal albumin reabsorption. Albuminuria due to reduced cubilin function could be an unexpectedly common benign condition in humans that may not require any proteinuria-lowering treatment or renal biopsy.FUNDING ATIP-Avenir program, Fondation Bettencourt-Schueller (Liliane Bettencourt Chair of Developmental Biology), Agence Nationale de la Recherche (ANR) Investissements d’avenir program (ANR-10-IAHU-01) and NEPHROFLY (ANR-14-ACHN-0013, to MS), Steno Collaborative Grant 2018 (NNF18OC0052457, to TSA and MS), Heisenberg Professorship of the German Research Foundation (KO 3598/5-1, to AK), Deutsche Forschungsgemeinschaft (DFG) Collaborative Research Centre (SFB) KIDGEM 1140 (project 246781735, to CB), and Federal Ministry of Education and Research (BMB) (01GM1515C, to CB).

Authors

Mathilda Bedin, Olivia Boyer, Aude Servais, Yong Li, Laure Villoing-Gaudé, Marie-Josephe Tête, Alexandra Cambier, Julien Hogan, Veronique Baudouin, Saoussen Krid, Albert Bensman, Florie Lammens, Ferielle Louillet, Bruno Ranchin, Cecile Vigneau, Iseline Bouteau, Corinne Isnard-Bagnis, Christoph J. Mache, Tobias Schäfer, Lars Pape, Markus Gödel, Tobias B. Huber, Marcus Benz, Günter Klaus, Matthias Hansen, Kay Latta, Olivier Gribouval, Vincent Morinière, Carole Tournant, Maik Grohmann, Elisa Kuhn, Timo Wagner, Christine Bole-Feysot, Fabienne Jabot-Hanin, Patrick Nitschké, Tarunveer S. Ahluwalia, Anna Köttgen, Christian Brix Folsted Andersen, Carsten Bergmann, Corinne Antignac, Matias Simons

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Abstract

Patients with bladder cancer (BCa) with clinical lymph node (LN) metastasis have an extremely poor prognosis. VEGF-C has been demonstrated to play vital roles in LN metastasis in BCa. However, approximately 20% of BCa with LN metastasis exhibits low VEGF-C expression, suggesting a VEGF-C–independent mechanism for LN metastasis of BCa. Herein, we demonstrate that BCa cell–secreted exosome-mediated lymphangiogenesis promoted LN metastasis in BCa in a VEGF-C–independent manner. We identified an exosomal long noncoding RNA (lncRNA), termed lymph node metastasis-associated transcript 2 (LNMAT2), that stimulated human lymphatic endothelial cell (HLEC) tube formation and migration in vitro and enhanced tumor lymphangiogenesis and LN metastasis in vivo. Mechanistically, LNMAT2 was loaded to BCa cell–secreted exosomes by directly interacting with heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1). Subsequently, exosomal LNMAT2 was internalized by HLECs and epigenetically upregulated prospero homeobox 1 (PROX1) expression by recruitment of hnRNPA2B1 and increasing the H3K4 trimethylation level in the PROX1 promoter, ultimately resulting in lymphangiogenesis and lymphatic metastasis. Therefore, our findings highlight a VEGF-C–independent mechanism of exosomal lncRNA-mediated LN metastasis and identify LNMAT2 as a therapeutic target for LN metastasis in BCa.

Authors

Changhao Chen, Yuming Luo, Wang He, Yue Zhao, Yao Kong, Hongwei Liu, Guangzheng Zhong, Yuting Li, Jun Li, Jian Huang, Rufu Chen, Tianxin Lin

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Abstract

Immunotherapy targeting programmed cell death-1 (PD-1) induces durable antitumor efficacy in many types of cancer. However, such clinical benefit is limited because of the insufficient reinvigoration of antitumor immunity with the drug alone; therefore, rational therapeutic combinations are required to improve its efficacy. In our preclinical study, we evaluated the antitumor effect of U3-1402, a human epidermal growth factor receptor 3–targeting (HER3–targeting) antibody-drug conjugate, and its potential synergism with PD-1 inhibition. Using a syngeneic mouse tumor model that is refractory to anti–PD-1 therapy, we found that treatment with U3-1402 exhibited an obvious antitumor effect via direct lysis of tumor cells. Disruption of tumor cells by U3-1402 enhanced the infiltration of innate and adaptive immune cells. Chemotherapy with exatecan derivative (Dxd, the drug payload of U3-1402) revealed that the enhanced antitumor immunity produced by U3-1402 was associated with the induction of alarmins, including high-mobility group box-1 (HMGB-1), via tumor-specific cytotoxicity. Notably, U3-1402 significantly sensitized the tumor to PD-1 blockade, as a combination of U3-1402 and the PD-1 inhibitor significantly enhanced antitumor immunity. Further, clinical analyses indicated that tumor-specific HER3 expression was frequently observed in patients with PD-1 inhibitor–resistant solid tumors. Overall, U3-1402 is a promising candidate as a partner of immunotherapy for such patients.

Authors

Koji Haratani, Kimio Yonesaka, Shiki Takamura, Osamu Maenishi, Ryoji Kato, Naoki Takegawa, Hisato Kawakami, Kaoru Tanaka, Hidetoshi Hayashi, Masayuki Takeda, Naoyuki Maeda, Takashi Kagari, Kenji Hirotani, Junji Tsurutani, Kazuto Nishio, Katsumi Doi, Masaaki Miyazawa, Kazuhiko Nakagawa

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Abstract

Novel approaches for adjunctive therapy are urgently needed for complicated infections and patients with compromised immunity. Necrotizing fasciitis (NF) is a destructive skin and soft tissue infection. Despite treatment with systemic antibiotics and radical debridement of necrotic tissue, lethality remains high. The key iron regulatory hormone hepcidin was originally identified as a cationic antimicrobial peptide (AMP), but its putative expression and role in the skin, a major site of AMP production, have never been investigated. We report here that hepcidin production is induced in the skin of patients with group A Streptococcus (GAS) NF. In a GAS-induced NF model, mice lacking hepcidin in keratinocytes failed to restrict systemic spread of infection from an initial tissue focus. Unexpectedly, this effect was due to its ability to promote production of the CXCL1 chemokine by keratinocytes, resulting in neutrophil recruitment. Unlike CXCL1, hepcidin is resistant to degradation by major GAS proteases and could therefore serve as a reservoir to maintain steady-state levels of CXCL1 in infected tissue. Finally, injection of synthetic hepcidin at the site of infection can limit or completely prevent systemic spread of GAS infection, suggesting that hepcidin agonists could have a therapeutic role in NF.

Authors

Mariangela Malerba, Sabine Louis, Sylvain Cuvellier, Srikanth Mairpady Shambat, Camille Hua, Camille Gomart, Agnès Fouet, Nicolas Ortonne, Jean-Winoc Decousser, Annelies S. Zinkernagel, Jacques R.R. Mathieu, Carole Peyssonnaux

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Abstract

Tyrosine kinase inhibitors (TKIs) induce molecular remission in the majority of patients with chronic myelogenous leukemia (CML), but the persistence of CML stem cells hinders cure and necessitates indefinite TKI therapy. We report that CML stem cells upregulate the expression of pleiotrophin (PTN) and require cell-autonomous PTN signaling for CML pathogenesis in BCR/ABL+ mice. Constitutive PTN deletion substantially reduced the numbers of CML stem cells capable of initiating CML in vivo. Hematopoietic cell–specific deletion of PTN suppressed CML development in BCR/ABL+ mice, suggesting that cell-autonomous PTN signaling was necessary for CML disease evolution. Mechanistically, PTN promoted CML stem cell survival and TKI resistance via induction of Jun and the unfolded protein response. Human CML cells were also dependent on cell-autonomous PTN signaling, and anti-PTN antibody suppressed human CML colony formation and CML repopulation in vivo. Our results suggest that targeted inhibition of PTN has therapeutic potential to eradicate CML stem cells.

Authors

Heather A. Himburg, Martina Roos, Tiancheng Fang, Yurun Zhang, Christina M. Termini, Lauren Schlussel, Mindy Kim, Amara Pang, Jenny Kan, Liman Zhao, Hyung Suh, Joshua P. Sasine, Gopal Sapparapu, Peter M. Bowers, Gary Schiller, John P. Chute

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Abstract

Polymorphonuclear neutrophils (PMNs) are increasingly recognized to influence solid tumor development, but why their effects are so context dependent and even frequently divergent remains poorly understood. Using an autochthonous mouse model of uterine cancer and the administration of respiratory hyperoxia as a means to improve tumor oxygenation, we provide in vivo evidence that hypoxia is a potent determinant of tumor-associated PMN phenotypes and direct PMN–tumor cell interactions. Upon relief of tumor hypoxia, PMNs were recruited less intensely to the tumor-bearing uterus, but the recruited cells much more effectively killed tumor cells, an activity our data moreover suggested was mediated via their production of NADPH oxidase–derived reactive oxygen species and MMP-9. Simultaneously, their ability to promote tumor cell proliferation, which appeared to be mediated via their production of neutrophil elastase, was rendered less effective. Relieving tumor hypoxia thus greatly improved net PMN-dependent tumor control, leading to a massive reduction in tumor burden. Remarkably, this outcome was T cell independent. Together, these findings identify key hypoxia-regulated molecular mechanisms through which PMNs directly induce tumor cell death and proliferation in vivo and suggest that the contrasting properties of PMNs in different tumor settings may in part reflect the effects of hypoxia on direct PMN–tumor cell interactions.

Authors

Karim Mahiddine, Adam Blaisdell, Stephany Ma, Amandine Créquer-Grandhomme, Clifford A. Lowell, Adrian Erlebacher

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Abstract

Pancreatic ductal adenocarcinoma (PDAC) is considered to be a highly immunosuppressive and heterogenous neoplasm. Despite improved knowledge regarding the genetic background of the tumor and better understanding of the tumor microenvironment, immune checkpoint inhibitor therapy (targeting CTLA4, PD1, PDL1) has not been very successful against PDAC. The robust desmoplastic stroma, along with an extensive extracellular matrix (ECM) that is rich in hyaluronan, plays an integral role in this immune evasion. Hexosamine biosynthesis pathway (HBP), a shunt pathway of glycolysis, is a metabolic node in cancer cells that can promote survival pathways on the one hand and influence the hyaluronan synthesis in the ECM on the other. The rate-limiting enzyme of the pathway, glutamine-fructose amidotransferase 1 (GFAT1), uses glutamine and fructose 6-phosphate to eventually synthesize uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). In the current manuscript, we targeted this glutamine-utilizing enzyme by a small molecule glutamine analog (6-diazo-5-oxo-l-norleucine [DON]). Our results showed that DON decreased the self-renewal potential and metastatic ability of tumor cells. Further, treatment with DON decreased hyaluronan and collagen in the tumor microenvironment, leading to an extensive remodeling of the ECM and an increased infiltration of CD8+ T cells. Additionally, treatment with DON sensitized pancreatic tumors to anti-PD1 therapy, resulting in tumor regression and prolonged survival.

Authors

Nikita S. Sharma, Vineet K. Gupta, Vanessa T. Garrido, Roey Hadad, Brittany C. Durden, Kousik Kesh, Bhuwan Giri, Anthony Ferrantella, Vikas Dudeja, Ashok Saluja, Sulagna Banerjee

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Abstract

Albuminuria acts as a marker of progressive chronic kidney disease and as an indicator for initiation of hypertension treatment via modulation of the renin-angiotensin-aldosterone system with angiotensin receptor blockers or angiotensin-converting enzyme inhibitors. However, the true significance of albuminuria has yet to be fully defined. Is it merely a marker of underlying pathophysiology, or does it play a causal role in the progression of kidney disease? The answer remains under debate. In this issue of the JCI, Bedin et al. used next-generation sequencing data to identify patients with chronic proteinuria who had biallelic variants in the cubilin gene (CUBN). Through investigation of these pathogenic mutations in CUBN, the authors have further illuminated the clinical implications of albuminuria.

Authors

Andrew Beenken, Jonathan M. Barasch, Ali G. Gharavi

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Abstract

Axon regeneration failure causes neurological deficits and long-term disability after spinal cord injury (SCI). Here, we found that the α2δ2 subunit of voltage-gated calcium channels negatively regulates axon growth and regeneration of corticospinal neurons, the cells that originate the corticospinal tract. Increased α2δ2 expression in corticospinal neurons contributed to loss of corticospinal regrowth ability during postnatal development and after SCI. In contrast, α2δ2 pharmacological blockade through gabapentin administration promoted corticospinal structural plasticity and regeneration in adulthood. Using an optogenetic strategy combined with in vivo electrophysiological recording, we demonstrated that regenerating corticospinal axons functionally integrate into spinal circuits. Mice administered gabapentin recovered upper extremity function after cervical SCI. Importantly, such recovery relies on reorganization of the corticospinal pathway, as chemogenetic silencing of injured corticospinal neurons transiently abrogated recovery. Thus, targeting α2δ2 with a clinically relevant treatment strategy aids repair of motor circuits after SCI.

Authors

Wenjing Sun, Molly J.E. Larson, Conrad M. Kiyoshi, Alexander J. Annett, William A. Stalker, Juan Peng, Andrea Tedeschi

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Abstract

Pancreatic ductal adenocarcinomas (PDACs) are classically immunologically cold tumors that have failed to demonstrate a significant response to immunotherapeutic strategies. This feature is attributed to both the immunosuppressive tumor microenvironment (TME) and limited immune cell access due to the surrounding stromal barrier, a histological hallmark of PDACs. In this issue of the JCI, Sharma et al. employ a broad glutamine antagonist, 6-diazo-5-oxo-l-norleucine (DON), to target a metabolic program that underlies both PDAC growth and hyaluronan production. Their findings describe an approach to converting the PDAC TME into a hot TME, thereby empowering immunotherapeutic strategies such as anti-PD1 therapy.

Authors

Won Jin Ho, Elizabeth M. Jaffee

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Abstract

Aberrant Tau inclusions in the locus coeruleus (LC) are the earliest detectable Alzheimer’s disease–like (AD-like) neuropathology in the human brain. However, why LC neurons are selectively vulnerable to developing early Tau pathology and degenerating later in disease and whether the LC might seed the stereotypical spread of Tau pathology to the rest of the brain remain unclear. Here, we show that 3,4-dihydroxyphenylglycolaldehyde, which is produced exclusively in noradrenergic neurons by monoamine oxidase A metabolism of norepinephrine, activated asparagine endopeptidase that cleaved Tau at residue N368 into aggregation- and propagation-prone forms, thus leading to LC degeneration and the spread of Tau pathology. Activation of asparagine endopeptidase–cleaved Tau aggregation in vitro and in intact cells was triggered by 3,4-dihydroxyphenylglycolaldehyde, resulting in LC neurotoxicity and propagation of pathology to the forebrain. Thus, our findings reveal that norepinephrine metabolism and Tau cleavage represent the specific molecular mechanism underlying the selective vulnerability of LC neurons in AD.

Authors

Seong Su Kang, Xia Liu, Eun Hee Ahn, Jie Xiang, Fredric P. Manfredsson, Xifei Yang, Hongbo R. Luo, L. Cameron Liles, David Weinshenker, Keqiang Ye

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Abstract

N-3 docosapentaenoic acid–derived resolvin D5 (RvD5n-3 DPA) is diurnally regulated in peripheral blood and exerts tissue-protective actions during inflammatory arthritis. Here, using an orphan GPCR screening approach coupled with functional readouts, we investigated the receptor(s) involved in mediating the leukocyte-directed actions of RvD5n-3 DPA and identified GPR101 as the top candidate. RvD5n-3 DPA bound to GPR101 with high selectivity and stereospecificity, as demonstrated by a calculated KD of approximately 6.9 nM. In macrophages, GPR101 knockdown limited the ability of RvD5n-3 DPA to upregulate cyclic adenosine monophosphate, phagocytosis of bacteria, and efferocytosis. Inhibition of this receptor in mouse and human leukocytes abrogated the pro-resolving actions of RvD5n-3 DPA, including the regulation of bacterial phagocytosis in neutrophils. Knockdown of the receptor in vivo reversed the protective actions of RvD5n-3 DPA in limiting joint and gut inflammation during inflammatory arthritis. Administration of RvD5n-3 DPA during E. coli–initiated inflammation regulated neutrophil trafficking to the site of inflammation, increased bacterial phagocytosis by neutrophils and macrophages, and accelerated the resolution of infectious inflammation. These in vivo protective actions of RvD5n-3 DPA were limited when Gpr101 was knocked down. Together, our findings demonstrate a fundamental role for GPR101 in mediating the leukocyte-directed actions of RvD5n-3 DPA.

Authors

Magdalena B. Flak, Duco S. Koenis, Agua Sobrino, James Smith, Kimberly Pistorius, Francesco Palmas, Jesmond Dalli

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Abstract

Potentiating radiotherapy and chemotherapy by inhibiting DNA damage repair is proposed as a therapeutic strategy to improve outcomes for patients with solid tumors. However, this approach risks enhancing normal tissue toxicity as much as tumor toxicity, thereby limiting its translational impact. Using NU5455, a newly identified highly selective oral inhibitor of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) activity, we found that it was indeed possible to preferentially augment the effect of targeted radiotherapy on human orthotopic lung tumors without influencing acute DNA damage or a late radiation-induced toxicity (fibrosis) to normal mouse lung. Furthermore, while NU5455 administration increased both the efficacy and the toxicity of a parenterally administered topoisomerase inhibitor, it enhanced the activity of doxorubicin released locally in liver tumor xenografts without inducing any adverse effect. This strategy is particularly relevant to hepatocellular cancer, which is treated clinically with localized drug-eluting beads and for which DNA-PKcs activity is reported to confer resistance to treatment. We conclude that transient pharmacological inhibition of DNA-PKcs activity is effective and tolerable when combined with localized DNA-damaging therapies and thus has promising clinical potential.

Authors

Catherine E. Willoughby, Yanyan Jiang, Huw D. Thomas, Elaine Willmore, Suzanne Kyle, Anita Wittner, Nicole Phillips, Yan Zhao, Susan J. Tudhope, Lisa Prendergast, Gesa Junge, Luiza Madia Lourenco, M. Raymond V. Finlay, Paul Turner, Joanne M. Munck, Roger J. Griffin, Tommy Rennison, James Pickles, Celine Cano, David R. Newell, Helen L. Reeves, Anderson J. Ryan, Stephen R. Wedge

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Abstract

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the CNS. Although CD4+ T cells are implicated in MS pathogenesis and have been the main focus of MS research using the animal model experimental autoimmune encephalomyelitis (EAE), substantial evidence from patients with MS points to a role for CD8+ T cells in disease pathogenesis. We previously showed that an MHC class I–restricted epitope of myelin basic protein (MBP) is presented in the CNS during CD4+ T cell–initiated EAE. Here, we investigated whether naive MBP-specific CD8+ T cells recruited to the CNS during CD4+ T cell–initiated EAE engaged in determinant spreading and influenced disease. We found that the MBP-specific CD8+ T cells exacerbated brain but not spinal cord inflammation. We show that a higher frequency of monocytes and monocyte-derived cells presented the MHC class I–restricted MBP ligand in the brain compared with the spinal cord. Infiltration of MBP-specific CD8+ T cells enhanced ROS production in the brain only in these cell types and only when the MBP-specific CD8+ T cells expressed Fas ligand (FasL). These results suggest that myelin-specific CD8+ T cells may contribute to disease pathogenesis via a FasL-dependent mechanism that preferentially promotes lesion formation in the brain.

Authors

Catriona A. Wagner, Pamela J. Roqué, Trevor R. Mileur, Denny Liggitt, Joan M. Goverman

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Abstract

Brown adipose tissue (BAT), as the main site of adaptive thermogenesis, exerts beneficial metabolic effects on obesity and insulin resistance. BAT has been previously assumed to contain a homogeneous population of brown adipocytes. Utilizing multiple mouse models capable of genetically labeling different cellular populations, as well as single-cell RNA sequencing and 3D tissue profiling, we discovered a new brown adipocyte subpopulation with low thermogenic activity coexisting with the classical high-thermogenic brown adipocytes within the BAT. Compared with the high-thermogenic brown adipocytes, these low-thermogenic brown adipocytes had substantially lower Ucp1 and Adipoq expression, larger lipid droplets, and lower mitochondrial content. Functional analyses showed that, unlike the high-thermogenic brown adipocytes, the low-thermogenic brown adipocytes have markedly lower basal mitochondrial respiration, and they are specialized in fatty acid uptake. Upon changes in environmental temperature, the 2 brown adipocyte subpopulations underwent dynamic interconversions. Cold exposure converted low-thermogenic brown adipocytes into high-thermogenic cells. A thermoneutral environment had the opposite effect. The recruitment of high-thermogenic brown adipocytes by cold stimulation is not affected by high fat diet feeding, but it does substantially decline with age. Our results revealed a high degree of functional heterogeneity of brown adipocytes.

Authors

Anying Song, Wenting Dai, Min Jee Jang, Leonard Medrano, Zhuo Li, Hu Zhao, Mengle Shao, Jiayi Tan, Aimin Li, Tinglu Ning, Marcia M. Miller, Brian Armstrong, Janice M. Huss, Yi Zhu, Yong Liu, Viviana Gradinaru, Xiwei Wu, Lei Jiang, Philipp E. Scherer, Qiong A. Wang

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Abstract

Diabetes is a common complication of cystic fibrosis (CF) that affects approximately 20% of adolescents and 40%–50% of adults with CF. The age at onset of CF-related diabetes (CFRD) (marked by clinical diagnosis and treatment initiation) is an important measure of the disease process. DNA variants associated with age at onset of CFRD reside in and near SLC26A9. Deep sequencing of the SLC26A9 gene in 762 individuals with CF revealed that 2 common DNA haplotypes formed by the risk variants account for the association with diabetes. Single-cell RNA sequencing (scRNA-Seq) indicated that SLC26A9 is predominantly expressed in pancreatic ductal cells and frequently coexpressed with CF transmembrane conductance regulator (CFTR) along with transcription factors that have binding sites 5′ of SLC26A9. These findings were replicated upon reanalysis of scRNA-Seq data from 4 independent studies. DNA fragments derived from the 5′ region of SLC26A9-bearing variants from the low-risk haplotype generated 12%–20% higher levels of expression in PANC-1 and CFPAC-1 cells compared with the high risk haplotype. Taken together, our findings indicate that an increase in SLC26A9 expression in ductal cells of the pancreas delays the age at onset of diabetes, suggesting a CFTR-agnostic treatment for a major complication of CF.

Authors

Anh-Thu N. Lam, Melis A. Aksit, Briana Vecchio-Pagan, Celeste A. Shelton, Derek L. Osorio, Arianna F. Anzmann, Loyal A. Goff, David C. Whitcomb, Scott M. Blackman, Garry R. Cutting

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Abstract

The c-MYC (MYC) oncoprotein is often overexpressed in human breast cancer; however, its role in driving disease phenotypes is poorly understood. Here, we investigate the role of MYC in HER2+ disease, examining the relationship between HER2 expression and MYC phosphorylation in HER2+ patient tumors and characterizing the functional effects of deregulating MYC expression in the murine NeuNT model of amplified-HER2 breast cancer. Deregulated MYC alone was not tumorigenic, but coexpression with NeuNT resulted in increased MYC Ser62 phosphorylation and accelerated tumorigenesis. The resulting tumors were metastatic and associated with decreased survival compared with NeuNT alone. MYC;NeuNT tumors had increased intertumoral heterogeneity including a subtype of tumors not observed in NeuNT tumors, which showed distinct metaplastic histology and worse survival. The distinct subtypes of MYC;NeuNT tumors match existing subtypes of amplified-HER2, estrogen receptor–negative human tumors by molecular expression, identifying the preclinical utility of this murine model to interrogate subtype-specific differences in amplified-HER2 breast cancer. We show that these subtypes have differential sensitivity to clinical HER2/EGFR–targeted therapeutics, but small-molecule activators of PP2A, the phosphatase that regulates MYC Ser62 phosphorylation, circumvents these subtype-specific differences and ubiquitously suppresses tumor growth, demonstrating the therapeutic utility of this approach in targeting deregulated MYC breast cancers.

Authors

Tyler Risom, Xiaoyan Wang, Juan Liang, Xiaoli Zhang, Carl Pelz, Lydia G. Campbell, Jenny Eng, Koei Chin, Caroline Farrington, Goutham Narla, Ellen M. Langer, Xiao-Xin Sun, Yulong Su, Colin J. Daniel, Mu-Shui Dai, Christiane V. Löhr, Rosalie C. Sears

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Abstract

Authors

Javid Moslehi, W. Kimryn Rathmell

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Abstract

Brown adipose tissue (BAT) contains mitochondria-enriched thermogenic fat cells (brown adipocytes) that play a crucial role in the regulation of energy metabolism and systemic glucose homeostasis. It was presumed that brown adipocytes are composed of a homogeneous cell population. In this issue of the JCI, however, Song and colleagues report a previously uncharacterized subpopulation of brown adipocytes that display distinct characteristics from the conventional brown adipocytes in their molecular signature, regulation, and fuel utilization. The present study provides novel insight into our understanding of cellular heterogeneity in adipose tissues.

Authors

Yasuo Oguri, Shingo Kajimura

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Abstract

Background: DICER1 is the only miRNA biogenesis component associated with an inherited tumor syndrome, featuring multinodular goiter (MNG) and rare pediatric-onset lesions. Other susceptibility genes for familial forms of MNG likely exist. Methods: Whole exome sequencing of a kindred with early-onset MNG and schwannomatosis was followed by investigation of germline pathogenic variants that fully segregated with the disease. Genome wide analyses were performed on 13 tissue samples from familial and non-familial DGCR8-E518K positive tumors, including MNG, schwannomas, papillary thyroid cancers (PTC) and Wilms Tumors. MiRNA profiles of four tissue types were compared, and sequencing of miRNA, pre-miRNA and mRNA was performed in a subset of 9 schwannomas, four of which harbor DGCR8-E518K. Results: We identified c.1552G>A;p.E518K in DGCR8, a microprocessor located in 22q, in the kindred. The variant identified is a somatic hotspot in Wilms Tumors and has been identified in two PTCs. Copy number loss of chromosome 22q, leading to loss of heterozygosity at the DGCR8 locus, was found in all 13 samples harboring c.1552G>A;p.E518K. miRNA profiling of PTC, MNG, schwannomas and Wilms Tumors revealed a common profile among E518K hemizygous tumors. In vitro cleavage demonstrated improper processing of pre-miRNA by DGCR8-E518K. MicroRNA and RNA profiling show that this variant disrupts precursor microRNA production, impacting populations of canonical microRNAs and mirtrons. Conclusions: We identified DGCR8 as the cause of an unreported autosomal dominant mendelian tumor susceptibility syndrome: familial multinodular goiter with schwannomatosis. Funded by CIHR, Compute Canada, Alex’s Lemonade Stand Foundation, and the Mia Neri Foundation for Childhood Cancer.

Authors

Barbara Rivera, Javad Nadaf, Somayyeh Fahiminiya, Maria Apellaniz-Ruiz, Avi Saskin, Anne-Sophie Chong, Sahil Sharma, Rabea Wagener, Timothée Revil, Vincenzo Condello, Zineb Harra, Nancy Hamel, Nelly Sabbaghian, Karl Muchantef, Christian Thomas, Leanne de Kock, Marie-Noëlle Hébert-Blouin, Angelia V. Bassenden, Hannah Rabenstein, Ozgur Mete, Ralf Paschke, Marc P. Pusztaszeri, Werner Paulus, Albert Berghuis, Jiannis Ragoussis, Yuri E. Nikiforov, Reiner Siebert, Steffen Albrecht, Robert Turcotte, Martin Hasselblatt, Marc R. Fabian, William D. Foulkes

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Abstract

Background. An increase in intrahepatic triglyceride (IHTG) is the hallmark feature of nonalcoholic fatty liver disease (NAFLD) and is decreased by weight loss. Hepatic de novo lipogenesis (DNL) contributes to steatosis in people with NAFLD. The physiological factors that stimulate hepatic DNL and the effect of weight loss on hepatic DNL are not clear.Methods. Hepatic DNL, 24-h integrated plasma insulin and glucose concentrations, and both liver and whole-body insulin sensitivity were determined in people who were lean (n = 14), obese with normal IHTG content (Obese, n = 26) and obese with NAFLD (Obese-NAFLD, n = 27). Hepatic DNL was assessed by using the deuterated water method corrected for the potential confounding contribution of adipose tissue DNL. Liver and whole-body insulin sensitivity were assessed by using the hyperinsulinemic-euglycemic clamp procedure in conjunction with glucose tracer infusion. Six subjects in the Obese-NAFLD group were also evaluated before and after 10% diet-induced weight loss.Results. The contribution of hepatic DNL to IHTG-palmitate was 11%, 19% and 38% in the Lean, Obese and Obese-NAFLD groups, respectively. Hepatic DNL was inversely correlated with hepatic and whole-body insulin sensitivity, but directly correlated with 24-h plasma glucose and insulin concentrations. Weight loss decreased IHTG content, in conjunction with a decrease in hepatic DNL and 24-h plasma glucose and insulin concentrations. Conclusions. These data suggest hepatic DNL is an important regulator of IHTG content, and that increases in circulating glucose and insulin stimulate hepatic DNL in people with NAFLD. Weight loss decreases IHTG content, at least in part, by decreasing hepatic DNL.

Authors

Gordon I. Smith, Mahalakshmi Shankaran, Mihoko Yoshino, George G. Schweitzer, Maria Chondronikola, Joseph W. Beals, Adewole L. Okunade, Bruce W. Patterson, Edna Nyangau, Tyler Field, Claude B. Sirlin, Saswata Talukdar, Marc K. Hellerstein, Samuel Klein

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Abstract

Epidermal growth factor receptor (EGFR) and MEK inhibitors (EGFR/MEKi) are beneficial for the treatment of solid cancers but are frequently associated with severe therapy-limiting acneiform skin toxicities. The underlying molecular mechanisms are poorly understood. Using gene expression profiling we identified IL-36γ and IL-8 as candidate drivers of EGFR/MEKi skin toxicity. We provide molecular and translational evidence that EGFR/MEKi in concert with the skin commensal bacterium Cutibacterium acnes act synergistically to induce IL-36γ in keratinocytes and subsequently IL-8, leading to cutaneous neutrophilia. IL-36γ expression was the combined result of C. acnes-induced NF-κB activation and EGFR/MEKi-mediated expression of the transcription factor Krüppel-like factor 4 (KLF4), due to the presence of both NF-κB- and KLF4-binding sites in the human IL-36γ gene promoter. EGFR/MEKi increased KLF4 expression by blockade of the EGFR-MEK-ERK pathway. These results provide an insight into understanding the pathological mechanism of the acneiform skin toxicities induced by EGFR/MEKi and identify IL-36γ and the transcription factor KLF4 as potential therapeutic targets.

Authors

Takashi K. Satoh, Mark Mellett, Barbara Meier-Schiesser, Gabriele Fenini, Atsushi Otsuka, Hans-Dietmar Beer, Tamara Rordorf, Julia-Tatjana Maul, Jürg Hafner, Alexander A. Navarini, Emmanuel Contassot, Lars E. French

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Abstract

Background: In retinitis pigmentosa (RP) rod photoreceptors degenerate from one of many mutations after which cones are compromised by oxidative stress. N-acetylcysteine (NAC) reduces oxidative damage and increases cone function/survival in RP models. We tested the safety, tolerability, and visual function effects of oral NAC in RP patients. Methods: Subjects (n = 10 per cohort) received 600 mg (cohort 1), 1200 mg (cohort 2), or 1800 mg (cohort 3) NAC BID for 12 weeks and then TID for 12 weeks. Best-corrected visual acuity (BCVA), macular sensitivity, ellipsoid zone (EZ) width, and aqueous NAC were measured. Linear mixed effects models were used to estimate the rates of changes during the treatment period. Results: There were 9 drug-related gastrointestinal adverse events which resolved spontaneously or with dose reduction (MTD 1800 mg bid). During the 24 week treatment period, mean BCVA significantly improved at 0.4 (95% CI 0.2–0.6, P < 0.001), 0.5 (95% CI 0.3–0.7, P < 0.001) and 0.2 (95% CI 0.02–0.4, P = 0.03) letters/month in cohorts 1, 2 and 3, respectively. There was no significant improvement in mean sensitivity (MS) over time in cohorts 1 and 2, but there was in cohort 3 (0.15 dB/month, 95%CI 0.04–0.26). There was no significant change in mean EZ width in any cohort. Conclusion: Oral NAC is safe and well-tolerated in patients with moderately advanced RP and may improve suboptimally functioning macular cones. A randomized, placebo-controlled trial is needed to determine if oral NAC can provide long term stabilization and/or improvement in visual function in patients with RP.

Authors

Peter A. Campochiaro, Mustafa Iftikhar, Gulnar Hafiz, Anam Akhlaq, Grace Tsai, Dagmar Wehling, Lili Lu, G. Michael Wall, Mandeep S. Singh, Xiangrong Kong

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Abstract

Cancer cachexia is a major cause of patient morbidity and mortality, with no efficacious treatment or management strategy. Despite sharing pathophysiological features with a number of neuromuscular wasting conditions, including age-related sarcopenia, the mechanisms underlying cachexia remain poorly understood. Studies of related conditions suggest that pathological targeting of the neuromuscular junction (NMJ) may play a key role in cachexia, but this has yet to be investigated in human patients. Here, high-resolution morphological analyses were undertaken on NMJs of rectus abdominis obtained from patients undergoing upper GI cancer surgery compared with controls (N=30; n=1,165 NMJs). Cancer patients included those with cachexia and weight-stable disease. Despite the low skeletal muscle index and significant muscle fibre atrophy in patients with cachexia, NMJ morphology was fully conserved. No significant differences were observed in any of the pre- and post-synaptic variables measured. We conclude that NMJs remain structurally intact in rectus abdominis in both cancer and cachexia, suggesting that denervation of skeletal muscle is not a major driver of pathogenesis. The absence of NMJ pathology is in stark contrast to related conditions, such as age-related sarcopenia, and supports the hypothesis that intrinsic changes within skeletal muscle, independent of any changes in motor neurons, represent the primary locus of neuromuscular pathology in cancer cachexia.

Authors

Ines Boehm, Janice Miller, Thomas M. Wishart, Stephen J. Wigmore, Richard J.E. Skipworth, Ross A. Jones, Thomas H. Gillingwater

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December 2019

December 2019 Issue

On the cover:
Preventing hemoglobin-induced damage in cerebral arteries

In this issue of the JCI, Hugelshofer, Buzzi, et al. show that cell-free hemoglobin present in the cerebrospinal fluid (CSF) of patients with subarachnoid hemorrhage disrupts nitric oxide signaling, driving pathological vasoconstriction. Sequestering hemoglobin by adding haptoglobin to CSF restored nitric oxide–mediated vasodilation and reduced vasospasm in an in vivo model. The findings support further research into haptoglobin-based interventions to mitigate neurological damage associated with subarachnoid bleeding. The cover image is a drawing depicting hemoglobin (red) in the tiny CSF-space alongside small penetrating cerebral arteries (green) of the sheep brain. Whereas free hemoglobin penetrates from CSF into the vascular smooth muscle layer (lower artery) and into the brain tissue, haptoglobin blocks hemoglobin translocation and its vasoconstrictive effects (upper artery). Image credit: Rok Humar.

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December 2019 JCI This Month

JCI This Month is a digest of the research, reviews, and other features published each month.

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Review Series - More

Mechanisms Underlying the Metabolic Syndrome

Series edited by Philipp E. Scherer

Obesity often occurs with a quintessential array of metabolic abnormalities: elevations in blood pressure, visceral fat, and circulating blood lipids, and, importantly, insulin resistance. Together, this constellation of conditions constitutes the metabolic syndrome and forecasts an individual’s increased risk of developing cardiovascular diseases and type 2 diabetes. Although metabolic syndrome presents as dysfunction across multiple tissues, its onset stems from pathological increases in adipose tissue. The 9 review in this series, conceptualized by series editor Philipp Scherer, delve into the complex biology underlying the metabolic syndrome. These reviews address adipocyte and beta cell dysfunction in the metabolic syndrome; the functions of adipose tissue fibrosis, the microbiome, and exosomal communication in obesity; and the concepts we use to define metabolic health.

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