Androgen receptor antagonism drives cytochrome P450 17A1 inhibitor efficacy in prostate cancer

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Abstract

The clinical utility of inhibiting cytochrome P450 17A1 (CYP17), a cytochrome p450 enzyme that is required for the production of androgens, has been exemplified by the approval of abiraterone for the treatment of castration-resistant prostate cancer (CRPC). Recently, however, it has been reported that CYP17 inhibitors can interact directly with the androgen receptor (AR). A phase I study recently reported that seviteronel, a CYP17 lyase–selective inhibitor, demonstrated a sustained reduction in prostate-specific antigen in a patient with CRPC, and another study showed seviteronel’s direct effects on AR function. This suggested that seviteronel may have therapeutically relevant activities in addition to its ability to inhibit androgen production. Here, we have demonstrated that CYP17 inhibitors, with the exception of orteronel, can function as competitive AR antagonists. Conformational profiling revealed that the CYP17 inhibitor–bound AR adopted a conformation that resembled the unliganded AR (apo-AR), precluding nuclear localization and DNA binding. Further, we observed that seviteronel and abiraterone inhibited the growth of tumor xenografts expressing the clinically relevant mutation AR-F876L and that this activity could be attributed entirely to competitive AR antagonism. The results of this study suggest that the ability of CYP17 inhibitors to directly antagonize the AR may contribute to their clinical efficacy in CRPC.

Authors

John D. Norris, Stephanie J. Ellison, Jennifer G. Baker, David B. Stagg, Suzanne E. Wardell, Sunghee Park, Holly M. Alley, Robert M. Baldi, Alexander Yllanes, Kaitlyn J. Andreano, James P. Stice, Scott A. Lawrence, Joel R. Eisner, Douglas K. Price, William R. Moore, William D. Figg, Donald P. McDonnell

ω-3 polyunsaturated fatty acids ameliorate type 1 diabetes and autoimmunity

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Abstract

Despite the benefit of insulin, blockade of autoimmune attack and regeneration of pancreatic islets are ultimate goals for the complete cure of type 1 diabetes (T1D). Long-term consumption of ω-3 polyunsaturated fatty acids (PUFAs) is known to suppress inflammatory processes, making these fatty acids candidates for the prevention and amelioration of autoimmune diseases. Here, we explored the preventative and therapeutic effects of ω-3 PUFAs on T1D. In NOD mice, dietary intervention with ω-3 PUFAs sharply reduced the incidence of T1D, modulated the differentiation of Th cells and Tregs, and decreased the levels of IFN-γ, IL-17, IL-6, and TNF-α. ω-3 PUFAs exerted similar effects on the differentiation of CD4⁺ T cells isolated from human peripheral blood mononuclear cells. The regulation of CD4⁺ T cell differentiation was mediated at least in part through ω-3 PUFA eicosanoid derivatives and by mTOR complex 1 (mTORC1) inhibition. Importantly, therapeutic intervention in NOD mice through nutritional supplementation or lentivirus-mediated expression of an ω-3 fatty acid desaturase, mfat-1, normalized blood glucose and insulin levels for at least 182 days, blocked the development of autoimmunity, prevented lymphocyte infiltration into regenerated islets, and sharply elevated the expression of the β cell markers pancreatic and duodenal homeobox 1 (Pdx1) and paired box 4 (Pax4). The findings suggest that ω-3 PUFAs could potentially serve as a therapeutic modality for T1D.

Authors

Xinyun Bi, Fanghong Li, Shanshan Liu, Yan Jin, Xin Zhang, Tao Yang, Yifan Dai, Xiaoxi Li, Allan Zijian Zhao

Somatic mutations and progressive monosomy modify SAMD9-related phenotypes in humans

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Abstract

It is well established that somatic genomic changes can influence phenotypes in cancer, but the role of adaptive changes in developmental disorders is less well understood. Here we have used next-generation sequencing approaches to identify de novo heterozygous mutations in sterile α motif domain–containing protein 9 (SAMD9, located on chromosome 7q21.2) in 8 children with a multisystem disorder termed MIRAGE syndrome that is characterized by intrauterine growth restriction (IUGR) with gonadal, adrenal, and bone marrow failure, predisposition to infections, and high mortality. These mutations result in gain of function of the growth repressor product SAMD9. Progressive loss of mutated SAMD9 through the development of monosomy 7 (–7), deletions of 7q (7q–), and secondary somatic loss-of-function (nonsense and frameshift) mutations in SAMD9 rescued the growth-restricting effects of mutant SAMD9 proteins in bone marrow and was associated with increased length of survival. However, 2 patients with –7 and 7q– developed myelodysplastic syndrome, most likely due to haploinsufficiency of related 7q21.2 genes. Taken together, these findings provide strong evidence that progressive somatic changes can occur in specific tissues and can subsequently modify disease phenotype and influence survival. Such tissue-specific adaptability may be a more common mechanism modifying the expression of human genetic conditions than is currently recognized.

Authors

Federica Buonocore, Peter Kühnen, Jenifer P. Suntharalingham, Ignacio Del Valle, Martin Digweed, Harald Stachelscheid, Noushafarin Khajavi, Mohammed Didi, Angela F. Brady, Oliver Blankenstein, Annie M. Procter, Paul Dimitri, Jerry K.H. Wales, Paolo Ghirri, Dieter Knöbl, Brigitte Strahm, Miriam Erlacher, Marcin W. Wlodarski, Wei Chen, George K. Kokai, Glenn Anderson, Deborah Morrogh, Dale A. Moulding, Shane A. McKee, Charlotte M. Niemeyer, Annette Grüters, John C. Achermann

Estrogens enhance myoblast differentiation in facioscapulohumeral muscular dystrophy by antagonizing DUX4 activity

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Abstract

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant neuromuscular disorder that is characterized by extreme variability in symptoms, with females being less severely affected than males and presenting a higher proportion of asymptomatic carriers. The sex-related factors involved in the disease are not known. Here, we have utilized myoblasts isolated from FSHD patients (FSHD myoblasts) to investigate the effect of estrogens on muscle properties. Our results demonstrated that estrogens counteract the differentiation impairment of FSHD myoblasts without affecting cell proliferation or survival. Estrogen effects are mediated by estrogen receptor β (ERβ), which reduces chromatin occupancy and transcriptional activity of double homeobox 4 (DUX4), a protein whose aberrant expression has been implicated in FSHD pathogenesis. During myoblast differentiation, we observed that the levels and activity of DUX4 increased progressively and were associated with its enhanced recruitment in the nucleus. ERβ interfered with this recruitment by relocalizing DUX4 in the cytoplasm. This work identifies estrogens as a potential disease modifier that underlie sex-related differences in FSHD by protecting against myoblast differentiation impairments in this disease.

Authors

Emanuela Teveroni, Marsha Pellegrino, Sabrina Sacconi, Patrizia Calandra, Isabella Cascino, Stefano Farioli-Vecchioli, Angela Puma, Matteo Garibaldi, Roberta Morosetti, Giorgio Tasca, Enzo Ricci, Carlo Pietro Trevisan, Giuliana Galluzzi, Alfredo Pontecorvi, Marco Crescenzi, Giancarlo Deidda, Fabiola Moretti

Targeting PPARγ in the epigenome rescues genetic metabolic defects in mice

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Abstract

Obesity causes insulin resistance, and PPARγ ligands such as rosiglitazone are insulin sensitizing, yet the mechanisms remain unclear. In C57BL/6 (B6) mice, obesity induced by a high-fat diet (HFD) has major effects on visceral epididymal adipose tissue (eWAT). Here, we report that HFD-induced obesity in B6 mice also altered the activity of gene regulatory elements and genome-wide occupancy of PPARγ. Rosiglitazone treatment restored insulin sensitivity in obese B6 mice, yet, surprisingly, had little effect on gene expression in eWAT. However, in subcutaneous inguinal fat (iWAT), rosiglitazone markedly induced molecular signatures of brown fat, including the key thermogenic gene Ucp1. Obesity-resistant 129S1/SvImJ mice (129 mice) displayed iWAT browning, even in the absence of rosiglitazone. The 129 Ucp1 locus had increased PPARγ binding and gene expression that were preserved in the iWAT of B6x129 F1–intercrossed mice, with an imbalance favoring the 129-derived alleles, demonstrating a cis-acting genetic difference. Thus, B6 mice have genetically defective Ucp1 expression in iWAT. However, when Ucp1 was activated by rosiglitazone, or by iWAT browning in cold-exposed or young mice, expression of the B6 version of Ucp1 was no longer defective relative to the 129 version, indicating epigenomic rescue. These results provide a framework for understanding how environmental influences like drugs can affect the epigenome and potentially rescue genetically determined disease phenotypes.

Authors

Raymond E. Soccio, Zhenghui Li, Eric R. Chen, Yee Hoon Foong, Kiara K. Benson, Joanna R. Dispirito, Shannon E. Mullican, Matthew J. Emmett, Erika R. Briggs, Lindsey C. Peed, Richard K. Dzeng, Carlos J. Medina, Jennifer F. Jolivert, Megan Kissig, Satyajit R. Rajapurkar, Manashree Damle, Hee-Woong Lim, Kyoung-Jae Won, Patrick Seale, David J. Steger, Mitchell A. Lazar

Loss of microRNA-7a2 induces hypogonadotropic hypogonadism and infertility

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Abstract

MicroRNAs (miRNAs) are negative modulators of gene expression that fine-tune numerous biological processes. miRNA loss-of-function rarely results in highly penetrant phenotypes, but rather, influences cellular responses to physiologic and pathophysiologic stresses. Here, we have reported that a single member of the evolutionarily conserved miR-7 family, miR-7a2, is essential for normal pituitary development and hypothalamic-pituitary-gonadal (HPG) function in adulthood. Genetic deletion of mir-7a2 causes infertility, with low levels of gonadotropic and sex steroid hormones, small testes or ovaries, impaired spermatogenesis, and lack of ovulation in male and female mice, respectively. We found that miR-7a2 is highly expressed in the pituitary, where it suppresses golgi glycoprotein 1 (GLG1) expression and downstream bone morphogenetic protein 4 (BMP4) signaling and also reduces expression of the prostaglandin F2a receptor negative regulator (PTGFRN), an inhibitor of prostaglandin signaling and follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion. Our results reveal that miR-7a2 critically regulates sexual maturation and reproductive function by interconnecting miR-7 genomic circuits that regulate FSH and LH synthesis and secretion through their effects on pituitary prostaglandin and BMP4 signaling.

Authors

Kashan Ahmed, Mary P. LaPierre, Emanuel Gasser, Rémy Denzler, Yinjie Yang, Thomas Rülicke, Jukka Kero, Mathieu Latreille, Markus Stoffel

Sphingosine-1-phosphate lyase mutations cause primary adrenal insufficiency and steroid-resistant nephrotic syndrome

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Abstract

Primary adrenal insufficiency is life threatening and can present alone or in combination with other comorbidities. Here, we have described a primary adrenal insufficiency syndrome and steroid-resistant nephrotic syndrome caused by loss-of-function mutations in sphingosine-1-phosphate lyase (SGPL1). SGPL1 executes the final decisive step of the sphingolipid breakdown pathway, mediating the irreversible cleavage of the lipid-signaling molecule sphingosine-1-phosphate (S1P). Mutations in other upstream components of the pathway lead to harmful accumulation of lysosomal sphingolipid species, which are associated with a series of conditions known as the sphingolipidoses. In this work, we have identified 4 different homozygous mutations, c.665G>A (p.R222Q), c.1633_1635delTTC (p.F545del), c.261+1G>A (p.S65Rfs*6), and c.7dupA (p.S3Kfs*11), in 5 families with the condition. In total, 8 patients were investigated, some of whom also manifested other features, including ichthyosis, primary hypothyroidism, neurological symptoms, and cryptorchidism. Sgpl1^–/– mice recapitulated the main characteristics of the human disease with abnormal adrenal and renal morphology. Sgpl1^–/– mice displayed disrupted adrenocortical zonation and defective expression of steroidogenic enzymes as well as renal histology in keeping with a glomerular phenotype. In summary, we have identified SGPL1 mutations in humans that perhaps represent a distinct multisystemic disorder of sphingolipid metabolism.

Authors

Rathi Prasad, Irene Hadjidemetriou, Avinaash Maharaj, Eirini Meimaridou, Federica Buonocore, Moin Saleem, Jenny Hurcombe, Agnieszka Bierzynska, Eliana Barbagelata, Ignacio Bergadá, Hamilton Cassinelli, Urmi Das, GOSgene, Ruth Krone, Bulent Hacihamdioglu, Erkan Sari, Ediz Yesilkaya, Helen L. Storr, Maria Clemente, Monica Fernandez-Cancio, Nuria Camats, Nanik Ram, John C. Achermann, Paul P. Van Veldhoven, Leonardo Guasti, Debora Braslavsky, Tulay Guran, Louise A. Metherell

Mechanism for leptin’s acute insulin-independent effect to reverse diabetic ketoacidosis

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Abstract

The mechanism by which leptin reverses diabetic ketoacidosis (DKA) is unknown. We examined the acute insulin-independent effects of leptin replacement therapy in a streptozotocin-induced rat model of DKA. Leptin infusion reduced rates of lipolysis, hepatic glucose production (HGP), and hepatic ketogenesis by 50% within 6 hours and were independent of any changes in plasma glucagon concentrations; these effects were abrogated by coinfusion of corticosterone. Treating leptin- and corticosterone-infused rats with an adipose triglyceride lipase inhibitor blocked corticosterone-induced increases in plasma glucose concentrations and rates of HGP and ketogenesis. Similarly, adrenalectomized type 1 diabetic (T1D) rats exhibited decreased rates of lipolysis, HGP, and ketogenesis; these effects were reversed by corticosterone infusion. Leptin-induced decreases in lipolysis, HGP, and ketogenesis in DKA were also nullified by relatively small increases (15 to 70 pM) in plasma insulin concentrations. In contrast, the chronic glucose-lowering effect of leptin in a STZ-induced mouse model of poorly controlled T1D was associated with decreased food intake, reduced plasma glucagon and corticosterone concentrations, and decreased ectopic lipid (triacylglycerol/diacylglycerol) content in liver and muscle. Collectively, these studies demonstrate marked differences in the acute insulin-independent effects by which leptin reverses fasting hyperglycemia and ketoacidosis in a rodent model of DKA versus the chronic pleotropic effects by which leptin reverses hyperglycemia in a non-DKA rodent model of T1D.

Authors

Rachel J. Perry, Liang Peng, Abudukadier Abulizi, Lynn Kennedy, Gary W. Cline, Gerald I. Shulman

PAX6 maintains β cell identity by repressing genes of alternative islet cell types

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Abstract

Type 2 diabetes is thought to involve a compromised β cell differentiation state, but the mechanisms underlying this dysfunction remain unclear. Here, we report a key role for the TF PAX6 in the maintenance of adult β cell identity and function. PAX6 was downregulated in β cells of diabetic db/db mice and in WT mice treated with an insulin receptor antagonist, revealing metabolic control of expression. Deletion of Pax6 in β cells of adult mice led to lethal hyperglycemia and ketosis that were attributed to loss of β cell function and expansion of α cells. Lineage-tracing, transcriptome, and chromatin analyses showed that PAX6 is a direct activator of β cell genes, thus maintaining mature β cell function and identity. In parallel, we found that PAX6 binds promoters and enhancers to repress alternative islet cell genes including ghrelin, glucagon, and somatostatin. Chromatin analysis and shRNA-mediated gene suppression experiments indicated a similar function of PAX6 in human β cells. We conclude that reduced expression of PAX6 in metabolically stressed β cells may contribute to β cell failure and α cell dysfunction in diabetes.

Authors

Avital Swisa, Dana Avrahami, Noa Eden, Jia Zhang, Eseye Feleke, Tehila Dahan, Yamit Cohen-Tayar, Miri Stolovich-Rain, Klaus H. Kaestner, Benjamin Glaser, Ruth Ashery-Padan, Yuval Dor

Deficiency in prohormone convertase PC1 impairs prohormone processing in Prader-Willi syndrome

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Abstract

Prader-Willi syndrome (PWS) is caused by a loss of paternally expressed genes in an imprinted region of chromosome 15q. Among the canonical PWS phenotypes are hyperphagic obesity, central hypogonadism, and low growth hormone (GH). Rare microdeletions in PWS patients define a 91-kb minimum critical deletion region encompassing 3 genes, including the noncoding RNA gene SNORD116. Here, we found that protein and transcript levels of nescient helix loop helix 2 (NHLH2) and the prohormone convertase PC1 (encoded by PCSK1) were reduced in PWS patient induced pluripotent stem cell–derived (iPSC-derived) neurons. Moreover, Nhlh2 and Pcsk1 expression were reduced in hypothalami of fasted Snord116 paternal knockout (Snord116^p–/m+) mice. Hypothalamic Agrp and Npy remained elevated following refeeding in association with relative hyperphagia in Snord116^p–/m+ mice. Nhlh2-deficient mice display growth deficiencies as adolescents and hypogonadism, hyperphagia, and obesity as adults. Nhlh2 has also been shown to promote Pcsk1 expression. Humans and mice deficient in PC1 display hyperphagic obesity, hypogonadism, decreased GH, and hypoinsulinemic diabetes due to impaired prohormone processing. Here, we found that Snord116^p–/m+ mice displayed in vivo functional defects in prohormone processing of proinsulin, pro-GH–releasing hormone, and proghrelin in association with reductions in islet, hypothalamic, and stomach PC1 content. Our findings suggest that the major neuroendocrine features of PWS are due to PC1 deficiency.

Authors

Lisa C. Burnett, Charles A. LeDuc, Carlos R. Sulsona, Daniel Paull, Richard Rausch, Sanaa Eddiry, Jayne F. Martin Carli, Michael V. Morabito, Alicja A. Skowronski, Gabriela Hubner, Matthew Zimmer, Liheng Wang, Robert Day, Brynn Levy, Ilene Fennoy, Beatrice Dubern, Christine Poitou, Karine Clement, Merlin G. Butler, Michael Rosenbaum, Jean Pierre Salles, Maithe Tauber, Daniel J. Driscoll, Dieter Egli, Rudolph L. Leibel