Estrogen regulates divergent transcriptional and epigenetic cell states in breast cancer.

Breast cancers are known to be driven by the transcription factor estrogen receptor and its ligand estrogen. While the receptor's cis-binding elements are known to vary between tumors, heterogeneity of hormone signaling at a single-cell level is unknown. In this study, we systematically tracked estrogen response across time at a single-cell level in multiple cell line and organoid models. To accurately model these changes, we developed a computational tool (TITAN) that quantifies signaling gradients in single-cell datasets. Using this approach, we found that gene expression response to estrogen is non-uniform, with distinct cell groups expressing divergent transcriptional networks. Pathway analysis suggested the two most distinct signatures are driven separately by ER and FOXM1. We observed that FOXM1 was indeed activated by phosphorylation upon estrogen stimulation and silencing of FOXM1 attenuated the relevant gene signature. Analysis of scRNA-seq data from patient samples confirmed the existence of these divergent cell groups, with the FOXM1 signature predominantly found in ER negative cells. Further, multi-omic single-cell experiments indicated that the different cell groups have distinct chromatin accessibility states. Our results provide a comprehensive insight into ER biology at the single-cell level and potential therapeutic strategies to mitigate resistance to therapy.

Concise Review: Adaptation of the Bone Marrow Stroma in Hematopoietic Malignancies: Current Concepts and Models.

The bone marrow stroma maintains hematopoiesis and coordinately regulates regenerative responses through dynamic interactions with hematopoietic stem and progenitor cells. Recent studies indicate that stromal components in the bone marrow of leukemia patients undergo a process of successive adaptation that in turn exerts dramatic effects on the hematopoietic stem cell compartment and promotes leukemic drug resistance. Therefore, functional changes in discrete marrow stromal populations can be considered an aspect of leukemia biogenesis in that they create an aberrant, self-reinforcing microenvironment. In this review, we will describe the current understanding of the remodeling of the hematopoietic stem cell niche following invasion by leukemia cells. We place emphasis on existing evidence of how mesenchymal stem cells and their progeny facilitate neoplastic growth and describe available models and analytical techniques to understand the conversion of the niche toward disease persistence. Stem Cells 2018;36:304-312.

Long-lasting effect of obesity on skeletal muscle transcriptome.

BACKGROUND: Reduced physical activity and increased intake of calorically-dense diets are the main risk factors for obesity, glucose intolerance, and type 2 diabetes. Chronic overnutrition and hyperglycemia can alter gene expression, contributing to long-term obesity complications. While caloric restriction can reduce obesity and glucose intolerance, it is currently unknown whether it can effectively reprogram transcriptome to a pre-obesity level. The present study addressed this question by the preliminary examination of the transcriptional dynamics in skeletal muscle after exposure to overnutrition and following caloric restriction. RESULTS: Six male rhesus macaques of 12-13 years of age consumed a high-fat western-style diet for 6 months and then were calorically restricted for 4 months without exercise. Skeletal muscle biopsies were subjected to longitudinal gene expression analysis using next-generation whole-genome RNA sequencing. In spite of significant weight loss and normalized insulin sensitivity, the majority of WSD-induced (n = 457) and WSD-suppressed (n = 47) genes remained significantly dysregulated after caloric restriction (FDR ≤0.05). The MetacoreTM pathway analysis reveals that western-style diet induced the sustained activation of the transforming growth factor-ß gene network, associated with extracellular matrix remodeling, and the downregulation of genes involved in muscle structure development and nutritional processes. CONCLUSIONS: Western-style diet, in the absence of exercise, induced skeletal muscle transcriptional programing, which persisted even after insulin resistance and glucose intolerance were completely reversed with caloric restriction.

Combined androgen excess and Western-style diet accelerates adipose tissue dysfunction in young adult, female nonhuman primates.

STUDY QUESTION: What are the separate and combined effects of mild hyperandrogenemia and consumption of a high-fat Western-style diet (WSD) on white adipose tissue (WAT) morphology and function in young adult female nonhuman primates? SUMMARY ANSWER: Combined exposure to mild hyperandrogenemia and WSD induces visceral omental (OM-WAT) but not subcutaneous (SC-WAT) adipocyte hypertrophy that is associated with increased uptake and reduced mobilization of free fatty acids. WHAT IS KNOWN ALREADY: Mild hyperandrogenemia in females, principally in the context of polycystic ovary syndrome, is often associated with adipocyte hypertrophy, but the mechanisms of associated WAT dysfunction and depot specificity remain poorly understood. STUDY DESIGN, SIZE AND DURATION: Female rhesus macaques were randomly assigned at 2.5 years of age (near menarche) to receive either cholesterol (C; n = 20) or testosterone (T; n = 20)-containing silastic implants to elevate T levels 5-fold above baseline. Half of each of these groups was then fed either a low-fat monkey chow diet or WSD, resulting in four treatment groups (C, control diet; T alone; WSD alone; T + WSD; n = 10/group) that were maintained until the current analyses were performed at 5.5 years of age (3 years of treatment, young adults). PARTICIPANTS/MATERIALS, SETTING AND METHODS: OM and SC-WAT biopsies were collected and analyzed longitudinally for in vivo changes in adipocyte area and blood vessel density, and ex vivo basal and insulin-stimulated fatty acid uptake and basal and isoproterenol-stimulated lipolysis. MAIN RESULTS AND THE ROLE OF CHANCE: In years 2 and 3 of treatment, the T + WSD group exhibited a significantly greater increase in OM adipocyte size compared to all other groups (P < 0.05), while the size of SC adipocytes measured at the end of the study was not significantly different between groups. In year 3, both WAT depots from the WSD and T + WSD groups displayed a significant reduction in local capillary length and vessel junction density (P < 0.05). In year 3, insulin-stimulated fatty acid uptake in OM-WAT was increased in the T + WSD group compared to year 2 (P < 0.05). In year 3, basal lipolysis was blunted in the T and T + WSD groups in both WAT depots (P < 0.01), while isoproterenol-stimulated lipolysis was significantly blunted in the T and T + WSD groups only in SC-WAT (P < 0.01). LIMITATIONS, REASONS FOR CAUTION: At this stage of the study, subjects were still relatively young adults, so that the effects of mild hyperandrogenemia and WSD may become more apparent with increasing age. WIDER IMPLICATIONS OF THE FINDINGS: The combination of mild hyperandrogenemia and WSD accelerates the development of WAT dysfunction through T-specific (suppression of lipolytic response by T), WSD-dependent (reduced capillary density) and combined T + WSD (increased fatty acid uptake) mechanisms. These data support the idea that combined hyperandrogenemia and WSD increases the risk of developing obesity in females. STUDY FUNDING/COMPETING INTEREST(S): Research reported in this publication was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health under award number P50 HD071836 to C.T.R. and award number OD 011092 from the Office of the Director, National Institutes of Health, for operation of the Oregon National Primate Research Center. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Short-Term Caloric Restriction Attenuates Obesity-Induced Pro-Inflammatory Response in Male Rhesus Macaques.

White adipose tissue (WAT) hypertrophy is an essential hallmark of obesity and is associated with the activation of resident immune cells. While the benefits of caloric restriction (CR) on health span are generally accepted, its effects on WAT physiology are not well understood. We previously demonstrated that short-term CR reverses obesity in male rhesus macaques exposed to a high-fat Western-style diet (WSD). Here, we analyzed subcutaneous WAT biopsies collected from this cohort of animals before and after WSD and following CR. This analysis showed that WSD induced adipocyte hypertrophy and inhibited ß-adrenergic-simulated lipolysis. CR reversed adipocyte hypertrophy, but WAT remained insensitive to ß-adrenergic agonist stimulation. Whole-genome transcriptional analysis revealed that ß3-adrenergic receptor and de novo lipogenesis genes were downregulated by WSD and remained downregulated after CR. In contrast, WSD-induced pro-inflammatory gene expression was effectively reversed by CR. Furthermore, peripheral blood monocytes isolated during the CR period exhibited a significant reduction in the production of pro-inflammatory cytokines compared to those obtained after WSD. Collectively, this study demonstrates that short-term CR eliminates an obesity-induced pro-inflammatory response in WAT and peripheral monocytes.

SUMO-Enriched Proteome for Drosophila Innate Immune Response.

Small ubiquitin-like modifier (SUMO) modification modulates the expression of defense genes in Drosophila, activated by the Toll/nuclear factor-κB and immune-deficient/nuclear factor-κB signaling networks. We have, however, limited understanding of the SUMO-modulated regulation of the immune response and lack information on SUMO targets in the immune system. In this study, we measured the changes to the SUMO proteome in S2 cells in response to a lipopolysaccharide challenge and identified 1619 unique proteins in SUMO-enriched lysates. A confident set of 710 proteins represents the immune-induced SUMO proteome and analysis suggests that specific protein domains, cellular pathways, and protein complexes respond to immune stress. A small subset of the confident set was validated by in-bacto SUMOylation and shown to be bona-fide SUMO targets. These include components of immune signaling pathways such as Caspar, Jra, Kay, cdc42, p38b, 14-3-3ε, as well as cellular proteins with diverse functions, many being components of protein complexes, such as prosß4, Rps10b, SmD3, Tango7, and Aats-arg. Caspar, a human FAF1 ortholog that negatively regulates immune-deficient signaling, is SUMOylated at K551 and responds to treatment with lipopolysaccharide in cultured cells. Our study is one of the first to describe SUMO proteome for the Drosophila immune response. Our data and analysis provide a global framework for the understanding of SUMO modification in the host response to pathogens.