Clinical characterization of the mutational landscape of 24,639 real-world samples from patients with myeloid malignancies

Myeloid neoplasms represent a broad spectrum of hematological disorders for which somatic mutation status in key driver genes is important for diagnosis, prognosis and treatment. Here we summarize the findings of a targeted, next generation sequencing laboratory developed test in 24,639 clinical myeloid samples. Data were analyzed comprehensively and as part of individual cohorts specific to acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and myeloproliferative neoplasms (MPN). Overall, 48,015 variants were detected, and variants were found in all 50 genes in the panel. The mean number of mutations per patient was 1.95. Mutation number increased with age (Spearman's rank correlation coefficient, ρ = 0.29, P < 0.0001) and was higher in patients with AML than MDS or MPN (Student's t-test, P < 0.0001). TET2 was the most common mutation detected (19.1% of samples; 4,695/24,639) including 7.7% (1,908/24,639) with multi-hit TET2 mutations. Mutation frequency was correlated between patients with cytopenias and MDS (Spearman's, ρ = 0.97, P < 2.2×10-16) with the MDS diagnostic gene SF3B1 being the only notable outlier. This large retrospective study shows the utility of NGS testing to inform clinical decisions during routine clinical care and highlights the mutational landscape of a broad population of myeloid patients.

Pubertal exposure to dietary advanced glycation end products disrupts ductal morphogenesis and induces atypical hyperplasia in the mammary gland

BACKGROUND

Advanced glycation end products (AGEs) are reactive metabolites intrinsically linked with modern dietary patterns. Processed foods, and those high in sugar, protein and fat, often contain high levels of AGEs. Increased AGE levels are associated with increased breast cancer risk, however their significance has been largely overlooked due to a lack of direct cause-and-effect relationship.

METHODS

To address this knowledge gap, FVB/n mice were fed regular, low AGE, and high AGE diets from 3 weeks of age and mammary glands harvested during puberty (7 weeks) or adulthood (12 weeks and 7 months) to determine the effects upon mammary gland development. At endpoint mammary glands were harvested and assessed histologically (n ≥ 4). Immunohistochemistry and immunofluorescence were used to assess cellular proliferation and stromal fibroblast and macrophage recruitment. The Kruskal-Wallis test were used to compare continuous outcomes among groups. Mammary epithelial cell migration and invasion in response to AGE-mediated fibroblast activation was determined in two-compartment co-culture models. In vitro experiments were performed in triplicate. The nonparametric Wilcoxon rank sum test was used to compare differences between groups.

RESULTS

Histological analysis revealed the high AGE diet delayed ductal elongation, increased primary branching, as well as increased terminal end bud number and size. The high AGE diet also led to increased recruitment and proliferation of stromal cells to abnormal structures that persisted into adulthood. Atypical hyperplasia was observed in the high AGE fed mice. Ex vivo fibroblasts from mice fed dietary-AGEs retain an activated phenotype and promoted epithelial migration and invasion of non-transformed immortalized and tumor-derived mammary epithelial cells. Mechanistically, we found that the receptor for AGE (RAGE) is required for AGE-mediated increases in epithelial cell migration and invasion.

CONCLUSIONS

We observed a disruption in mammary gland development when mice were fed a diet high in AGEs. Further, both epithelial and stromal cell populations were impacted by the high AGE diet in the mammary gland. Educational, interventional, and pharmacological strategies to reduce AGEs associated with diet may be viewed as novel disease preventive and/or therapeutic initiatives during puberty.

Chronic Engineered Nanoparticle Additions Alter Insect Emergence and Result in Metal Flux from Aquatic Ecosystems into Riparian Food Webs

Freshwater ecosystems are exposed to engineered nanoparticles (NPs) through discharge from wastewater and agricultural runoff. We conducted a 9-month mesocosm experiment to examine the combined effects of chronic NP additions on insect emergence and insect-mediated contaminant flux to riparian spiders. Two NPs (copper, gold, plus controls) were crossed by two levels of nutrients in 18 outdoor mesocosms open to natural insect and spider colonization. We collected adult insects and two riparian spider genera, Tetragnatha and Dolomedes, for 1 week on a monthly basis. We estimated a significant decrease in cumulative insect emergence of 19% and 24% after exposure to copper and gold NPs, irrespective of nutrient level. NP treatments led to elevated copper and gold tissue concentrations in adult insects, which resulted in terrestrial fluxes of metals. These metal fluxes were associated with increased gold and copper tissue concentrations for both spider genera. We also observed about 25% fewer spiders in the NP mesocosms, likely due to reduced insect emergence and/or NP toxicity. These results demonstrate the transfer of NPs from aquatic to terrestrial ecosystems via emergence of aquatic insects and predation by riparian spiders, as well as significant reductions in insect and spider abundance in response to NP additions.

Impaired glucose metabolism underlies articular cartilage degeneration in osteoarthritis

Osteoarthritis (OA) is the leading joint disease characterized by cartilage destruction and loss of mobility. Accumulating evidence indicates that the incidence and severity of OA increases with diabetes, implicating systemic glucose metabolism in joint health. However, a definitive link between cellular metabolism in articular cartilage and OA pathogenesis is not yet established. Here, we report that in mice surgically induced to develop knee OA through destabilization of medial meniscus (DMM), expression of the main glucose transporter Glut1 is notably reduced in joint cartilage. Inducible deletion of Glut1 specifically in the Prg4-expressing articular cartilage accelerates cartilage loss in DMM-induced OA. Conversely, forced expression of Glut1 protects against cartilage destruction following DMM. Moreover, in mice with type I diabetes, both Glut1 expression and the rate of glycolysis are diminished in the articular cartilage, and the diabetic mice exhibit more severe cartilage destruction than their nondiabetic counterparts following DMM. The results provide proof of concept that boosting glucose metabolism in articular chondrocytes may ameliorate cartilage degeneration in OA.

Mutational landscape and clinical characterization of over 17,000 patients with myeloid malignancies using real-world data

7022

Background: Myeloid neoplasms represent a broad spectrum of hematological disorders for which somatic mutation status in key driver genes is important for diagnosis, prognosis and treatment. Here we summarize the findings from 17,181 clinical samples analyzed by a targeted next generation sequencing (NGS) laboratory developed test. Samples were analyzed comprehensively and as part of individual cohorts specific to acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and myeloproliferative neoplasms (MPN). Methods: Whole blood or bone marrow samples from patients with cause-for-testing for hematological symptoms were submitted for analysis by a referring clinician. DNA was extracted and assayed by a targeted, NGS panel to detect and report single nucleotide variants and small indels within 50 genes associated with myeloid malignancies and sequenced on Illumina DNA sequencers (Illumina, San Diego, CA). Results were reviewed, orthogonally confirmed unless previously validated, and reported by clinical laboratory directors. Disease status or symptoms were taken from test requisitions for each patient. Results: Overall, 34,581 Tier I, II, or III somatic variants were detected. The mean number of variants reported per patient was 1.98. This number increased with age (p < 0.001) and was highest in patients with AML. Mutations in genes associated with FDA-approved therapies ( FLT3, IDH1, IDH2, KIT, and JAK2) were observed in 22.3% (3836) patients while 28.0% of samples had mutations considered diagnostically relevant by the WHO. Clinical trials are in progress for therapies targeting TP53, NPM1, and CEBPA mutations and were observed in 12.5% (2144) of samples. FLT3, NPM1 and RUNX1 mutation which are diagnostic for AML were found in 29.0% (646 of 2225) of AML samples. Pair-wise mutation analyses found 21 mutually exclusive pairs including between genes associated with RNA splicing ( SF3B1, SRSF2 and U2AF1; OR < 0.29, p < 0.001) suggesting possible candidates for targeted therapy. The clinically favorable co-mutation of NPM1 with FLT3 internal tandem duplicate was significantly enriched (OR = 7.4, p < 0.001) in the AML population. Co-occurrence of ASXL1 with RUNX1 mutations which independently confer adverse risk was also enriched in AML (OR = 3.9, p < 0.001). Some patients (1021; 6.3%) were tested at multiple time-points with 48.8% showing loss or gain of a mutation between sample dates, potentially the result of tumor evolution and/or therapeutic intervention. Conclusions: This study shows that parallel testing of multiple genes in addition to the canonical driver mutations encompasses the mutations contributing to the etiology of these diseases. Despite the breadth of different mutations observed for myeloid neoplasms, consistent patterns are routinely observed that can help the clinician tailor the treatment and chart the progression of these diseases for each patient.

Preventing ovariectomy-induced weight gain decreases tumor burden in rodent models of obesity and postmenopausal breast cancer

BACKGROUND

Obesity and adult weight gain are linked to increased breast cancer risk and poorer clinical outcomes in postmenopausal women, particularly for hormone-dependent tumors. Menopause is a time when significant weight gain occurs in many women, and clinical and preclinical studies have identified menopause (or ovariectomy) as a period of vulnerability for breast cancer development and promotion.

METHODS

We hypothesized that preventing weight gain after ovariectomy (OVX) may be sufficient to prevent the formation of new tumors and decrease growth of existing mammary tumors. We tested this hypothesis in a rat model of obesity and carcinogen-induced postmenopausal mammary cancer and validated our findings in a murine xenograft model with implanted human tumors.

RESULTS

In both models, preventing weight gain after OVX significantly decreased obesity-associated tumor development and growth. Importantly, we did not induce weight loss in these animals, but simply prevented weight gain. In both lean and obese rats, preventing weight gain reduced visceral fat accumulation and associated insulin resistance. Similarly, the intervention decreased circulating tumor-promoting growth factors and inflammatory cytokines (i.e., BDNF, TNFα, FGF-2), with greater effects in obese compared to lean rats. In obese rats, preventing weight gain decreased adipocyte size, adipose tissue macrophage infiltration, reduced expression of the tumor-promoting growth factor FGF-1 in mammary adipose, and reduced phosphorylated FGFR indicating reduced FGF signaling in tumors.

CONCLUSIONS

Together, these findings suggest that the underlying mechanisms associated with the anti-tumor effects of weight maintenance are multi-factorial, and that weight maintenance during the peri-/postmenopausal period may be a viable strategy for reducing obesity-associated breast cancer risk and progression in women.

Generation and diversification of recombinant monoclonal antibodies

Antibodies are indispensable tools used for a large number of applications in both foundational and translational bioscience research; however, there are drawbacks to using traditional antibodies generated in animals. These include a lack of standardization leading to problems with reproducibility, high costs of antibodies purchased from commercial sources, and ethical concerns regarding the large number of animals used to generate antibodies. To address these issues, we have developed practical methodologies and tools for generating low-cost, high-yield preparations of recombinant monoclonal antibodies and antibody fragments directed to protein epitopes from primary sequences. We describe these methods here, as well as approaches to diversify monoclonal antibodies, including customization of antibody species specificity, generation of genetically encoded small antibody fragments, and conversion of single chain antibody fragments (e.g. scFv) into full-length, bivalent antibodies. This study focuses on antibodies directed to epitopes important for mitosis and kinetochore function; however, the methods and reagents described here are applicable to antibodies and antibody fragments for use in any field.

Advances in Analyzing the Breast Cancer Lipidome and Its Relevance to Disease Progression and Treatment

Abnormal lipid metabolism is common in breast cancer with the three main subtypes, hormone receptor (HR) positive, human epidermal growth factor 2 (HER2) positive, and triple negative, showing common and distinct lipid dependencies. A growing body of studies identify altered lipid metabolism as impacting breast cancer cell growth and survival, plasticity, drug resistance, and metastasis. Lipids are a class of nonpolar or polar (amphipathic) biomolecules that can be produced in cells via de novo synthesis or acquired from the microenvironment. The three main functions of cellular lipids are as essential components of membranes, signaling molecules, and nutrient storage. The use of mass spectrometry-based lipidomics to analyze the global cellular lipidome has become more prevalent in breast cancer research. In this review, we discuss current lipidomic methodologies, highlight recent breast cancer lipidomic studies and how these findings connect to disease progression and therapeutic development, and the potential use of lipidomics as a diagnostic tool in breast cancer. A better understanding of the breast cancer lipidome and how it changes during drug resistance and tumor progression will allow informed development of diagnostics and novel targeted therapies.

Abstract 1625: Distribution and prevalence of LAG-3 expression in samples of melanoma and gastric/gastroesophageal junction cancer

Background: Immune checkpoint inhibitors (ICIs) have become the standard of care in a range of tumors. However, a large proportion of patients treated with ICIs have treatment-refractory/resistant tumors requiring innovative approaches. Lymphocyte-activation gene 3 (LAG-3) is an immune checkpoint receptor that inhibits effector T-cell function. Preclinical data suggest that simultaneous activation of the LAG-3 and programmed death-1 pathways results in greater T-cell exhaustion than either pathway alone, leading to impaired antitumor immune response and increased tumor growth. Therefore, LAG-3 may be a promising new target for cancer immunotherapy. The objective of this study was to assess the distribution of LAG-3 expression on lymphocytes in melanoma, gastric cancer (GC), and gastroesophageal junction cancer (GEJC) samples using an immunohistochemistry (IHC) assay.

Methods: Formalin-fixed, paraffin-embedded samples from resected melanoma, GC, or GEJC ≤ 5 years old were procured for analysis. The LAG-3 IHC assay was developed and performed by LabCorp (Research Triangle Park, NC) using the anti-LAG-3 17B4 mouse antibody clone on a Leica Bond III platform. LAG-3 expression was assessed as the percentage of positive immune cells (ICs) within the invasive margin, tumor, and stroma. Programmed death ligand 1 (PD-L1) expression on tumor cells (TCs) and ICs was evaluated on the same samples using the Dako PD-L1 IHC 28-8 pharmDx assay to determine the percentage of PD-L1-expressing TCs and the combined positive score (CPS).

Results: A total of 102 melanoma samples, 256 GC samples, and 84 GEJC samples were included in this study. LAG-3 expression was detected in the majority of samples across all tumor types, with higher expression in GEJC than in melanoma or GC. LAG-3 prevalence was similar across subgroups based on disease stage (melanoma, GC) and grade (GC). LAG-3 prevalence was also consistent across subgroups based on age, sex, and ethnicity (all tumor types), as well as alcohol consumption and smoking history (melanoma and GC). LAG-3 expression was weakly correlated with PD-L1 expression on TCs (Spearman's ρ of 0.31 for GC, 0.41 for GEJC, and 0.46 for melanoma) and moderately correlated with PD-L1 CPS (Spearman's ρ of 0.63 for GC and 0.73 for GEJC). Similar correlations were observed after binning PD-L1 TC score and CPS.

Conclusions: LAG-3-expressing lymphocytes were identified in all tumor types tested. LAG-3 expression did not differ with age, sex, ethnicity, alcohol consumption, and smoking history, and appeared to be associated, but not strongly correlated, with PD-L1 expression in all tumor types. PD-L1 and LAG-3 expression in procured samples may not be reflective of expression observed in clinical trials, and further studies are needed to characterize LAG-3 expression in a clinical setting.

Citation Format: Lloye M. Dillon, John Wojcik, Keyur Desai, Ming Lei, Lori Johnson, Bryan McCune, Krystal Johnson, Jeffrey Shuster, Steven M. Anderson, Bin Li. Distribution and prevalence of LAG-3 expression in samples of melanoma and gastric/gastroesophageal junction cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1625.

Copper and Gold Nanoparticles Increase Nutrient Excretion Rates of Primary Consumers

Freshwater ecosystems are exposed to engineered nanoparticles through municipal and industrial wastewater-effluent discharges and agricultural nonpoint source runoff. Because previous work has shown that engineered nanoparticles from these sources can accumulate in freshwater algal assemblages, we hypothesized that nanoparticles may affect the biology of primary consumers by altering the processing of two critical nutrients associated with growth and survivorship, nitrogen and phosphorus. We tested this hypothesis by measuring the excretion rates of nitrogen and phosphorus of Physella acuta, a ubiquitous pulmonate snail that grazes heavily on periphyton, exposed to either copper or gold engineered nanoparticles for 6 months in an outdoor wetland mesocosm experiment. Chronic nanoparticle exposure doubled nutrient excretion when compared to the control. Gold nanoparticles increased nitrogen and phosphorus excretion rates more than copper nanoparticles, but overall, both nanoparticles led to higher consumer excretion, despite contrasting particle stability and physiochemical properties. Snails in mesocosms enriched with nitrogen and phosphorus had overall higher excretion rates than ones in ambient (no nutrients added) mesocosms. Stimulation patterns were different between nitrogen and phosphorus excretion, which could have implications for the resulting nutrient ratio in the water column. These results suggest that low concentrations of engineered nanoparticles could alter the metabolism of consumers and increase consumer-mediated nutrient recycling rates, potentially intensifying eutrophication in aquatic systems, for example, the increased persistence of algal blooms as observed in our mesocosm experiment.

Abstract 2637: Multiplex immunohistochemistry, spatial analysis, and gene expression profiling of the tumor-immune microenvironment in HNSCC tumors

Background: The complex and dynamic nature of the tumor-immune microenvironment presents challenges for identification of robust and predictive biomarkers in immuno-oncology (IO). Multiplex immunohistochemistry (mIHC) facilitates the ability to detect, phenotype, and quantify spatial relationships of cells within the tumor microenvironment (TME). Gene expression profiling allows for sensitive and high-throughput analysis of genes and signatures associated with the tumor, the immune response, and the TME, allowing examination of tumor-immune cell interactions. We used these approaches to generate multiple data sets from a cohort of HNSCC tumors and evaluated the correlation of the various analyte detection methods. These complementary technologies provide useful tools in the IO biomarker toolkit.

Methods: Formalin-fixed paraffin-embedded (FFPE) specimens from HNSCC patients were cut into 5µm sections for all technologies. Multiplex fluorescent IHC was performed for TME markers CD3, CD8, PD-L1, PD1, CD68, Granzyme B, Ki67, and panCK/SOX10. Visualization and data analysis were performed with an Akoya Vectra Polaris and Akoya inForm and HALO software (Indica Labs). Data analysis included cell identification, phenotyping, spatial relationships, and quantitative digital pathology. Gene expression for 770 genes was performed utilizing the NanoString PanCancer IO 360 Gene Expression Panel. Transcripts were quantitated using a NanoString nCounter and target gene counts were normalized to internal housekeeping genes.

Results: Analysis of the multiplex fluorescent IHC indicated a range of expression for the assayed TME biomarkers for the different tumor samples. Quantitative analysis of mIHC phenotype counts and normalized RNA counts for the targets contained in the antibody panel revealed a significant correlation between the analytic methods. Comparison of mIHC phenotype counts with a previously validated IO gene signature containing a broader set of IO-relevant genes, the Tumor Information Signature, (Ayers, et al., J Clin Invest. 2017; 127:2930) also showed a correlation.

Conclusions: The technologies described above enable the investigation of the TME for use in biomarker discovery, drug discovery, and IO pathway interrogation. These technologies can be used in parallel to uncover roles in the biomarker discovery pathway for genes of interest. The combination of mIHC and gene expression panels can be used to screen a broad range of targets, that then can be further investigated using the spatial analysis capabilities of mIHC to gain greater insight into the immune infiltrate density at any singular area of the TME.

Citation Format: Carlee Hemphill, Timothy Maynor, John Bauman, Caitlin Schroyer, Jeffery Shuster, Thomas Turi, Steven M. Anderson. Multiplex immunohistochemistry, spatial analysis, and gene expression profiling of the tumor-immune microenvironment in HNSCC tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2637.

Differential Reactivity of Copper- and Gold-Based Nanomaterials Controls Their Seasonal Biogeochemical Cycling and Fate in a Freshwater Wetland Mesocosm

Reliable predictions of the environmental fate and risk of engineered nanomaterials (ENMs) require a better understanding of ENM reactivity in complex, biologically active systems for chronic low-concentration exposure scenarios. Here, simulated freshwater wetland mesocosms were dosed with ENMs to assess how their reactivity and seasonal changes in environmental parameters influence ENM fate in aquatic systems. Copper-based ENMs (Kocide), known to dissolve in water, and gold nanoparticles (AuNPs), stable against dissolution in the absence of specific ligands, were added weekly to mesocosm waters for 9 months. Metal accumulation and speciation changes in the different environmental compartments were assessed over time. Copper from Kocide rapidly dissolved likely associating with organic matter in the water column, transported to terrestrial soils and deeper sediment where it became associated with organic or sulfide phases. In contrast, Au accumulated on/in the macrophytes where it oxidized and transferred over time to surficial sediment. A dynamic seasonal accumulation and metal redox cycling were found between the macrophyte and the surficial sediment for AuNPs. These results demonstrate the need for experimental quantification of how the biological and chemical complexity of the environment, combined with their seasonal variations, drive the fate of metastable ENMs.

Succession, regression and loss: does evidence of saltwater exposure explain recent changes in the tree communities of North Carolina's Coastal Plain?

BACKGROUND AND AIMS

Coastal plant communities globally are highly vulnerable to future sea-level rise and storm damage, but the extent to which these habitats are affected by the various environmental perturbations associated with chronic salinization remains unclear. In this study, we examine the relationship between North Carolina wetland tree community composition and basal area change and indicators of salinization such as soil salt ion content and elevation.

METHODS

We surveyed 34 forest plots in forested, freshwater wetlands across the Albemarle-Pamlico Peninsula. A subset of our study sites had been sampled during the previous decade as part of the Carolina Vegetation Survey, enabling us to investigate the environmental effects on current community structure, and community change over time.

KEY RESULTS

Multi-variate (ordination) analysis and linear regression models of tree community composition revealed that elevation and soil salt content were correlated with changes in total site tree basal area. Shifts in tree community composition were, however, only weakly correlated with indicators of salinization, specifically elevation, soil sulphate and sodium, but not chloride. While the majority of plots experienced gains in basal area over the past decade, consistent with secondary succession, sites with high soil salt content or low elevation experienced basal area (biomass) loss during the same period.

CONCLUSIONS

The key factors associated with chronic saltwater intrusion (soil ion content) likely explain recent changes in tree biomass, and potential shifts in community composition in low-elevation sites along the North Carolina coast. Not only is it probable that other coastal forest ecosystems worldwide will experience similar stressors and shifts in community biomass and structure as sea levels rise, but the ability of these habitats to deliver key ecosystem services like carbon sequestration and flood defence will be compromised as a result.

Liver X receptor-α activation enhances cholesterol secretion in lactating mammary epithelium

Liver X receptors (LXRs) are ligand-dependent transcription factors activated by cholesterol metabolites. These receptors induce a suite of target genes required for de novo synthesis of triglycerides and cholesterol transport in many tissues. Two different isoforms, LXRα and LXRβ, have been well characterized in liver, adipocytes, macrophages, and intestinal epithelium among others, but their contribution to cholesterol and fatty acid efflux in the lactating mammary epithelium is poorly understood. We hypothesize that LXR regulates lipogenesis during milk fat production in lactation. Global mRNA analysis of mouse mammary epithelial cells (MECs) revealed multiple LXR/RXR targets upregulated sharply early in lactation compared with midpregnancy. LXRα is the primary isoform, and its protein levels increase throughout lactation in MECs. The LXR agonist GW3965 markedly induced several genes involved in cholesterol transport and lipogenesis and enhanced cytoplasmic lipid droplet accumulation in the HC11 MEC cell line. Importantly, in vivo pharmacological activation of LXR increased the milk cholesterol percentage and induced sterol regulatory element-binding protein 1c (Srebp1c) and ATP-binding cassette transporter a7 (Abca7) expression in MECs. Cumulatively, our findings identify LXRα as an important regulator of cholesterol incorporation into the milk through key nodes of de novo lipogenesis, suggesting a potential therapeutic target in women with difficulty initiating lactation.

Size-Based Differential Transport, Uptake, and Mass Distribution of Ceria (CeO2) Nanoparticles in Wetland Mesocosms

Trace metals associated with nanoparticles are known to possess reactivities that are different from their larger-size counterparts. However, the relative importance of small relative to large particles for the overall distribution and biouptake of these metals is not as well studied in complex environmental systems. Here, we have examined differences in the long term fate and transport of ceria (CeO₂) nanoparticles of two different sizes (3.8 vs 185 nm), dosed weekly to freshwater wetland mesocosms over 9 months. While the majority of CeO₂ particles were detected in soils and sediments at the end of nine months, there were significant differences observed in fate, distribution, and transport mechanisms between the two materials. Small nanoparticles were removed from the water column primarily through heteroaggregation with suspended solids and plants, while large nanoparticles were removed primarily by sedimentation. A greater fraction of small particles remained in the upper floc layers of sediment relative to the large particles (31% vs 7%). Cerium from the small particles were also significantly more bioavailable to aquatic plants (2% vs 0.5%), snails (44 vs 2.6 ng), and insects (8 vs 0.07 μg). Small CeO₂ particles were also significantly reduced from Ce(IV) to Ce(III), while aquatic sediments were a sink for untransformed large nanoparticles. These results demonstrate that trace metals originating from nanoscale materials have much greater potential than their larger counterparts to distribute throughout multiple compartments of a complex aquatic ecosystem and contribute to the overall bioavailable pool of the metal for biouptake and trophic transfer.

Engineered nanoparticles interact with nutrients to intensify eutrophication in a wetland ecosystem experiment

Despite the rapid rise in diversity and quantities of engineered nanomaterials produced, the impacts of these emerging contaminants on the structure and function of ecosystems have received little attention from ecologists. Moreover, little is known about how manufactured nanomaterials may interact with nutrient pollution in altering ecosystem productivity, despite the recognition that eutrophication is the primary water quality issue in freshwater ecosystems worldwide. In this study, we asked two main questions: (1) To what extent do manufactured nanoparticles affect the biomass and productivity of primary producers in wetland ecosystems? (2) How are these impacts mediated by nutrient pollution? To address these questions, we examined the impacts of a citrate-coated gold nanoparticle (AuNPs) and of a commercial pesticide containing Cu(OH)₂ nanoparticles (CuNPs) on aquatic primary producers under both ambient and enriched nutrient conditions. Wetland mesocosms were exposed repeatedly with low concentrations of nanoparticles and nutrients over the course of a 9-month experiment in an effort to replicate realistic field exposure scenarios. In the absence of nutrient enrichment, there were no persistent effects of AuNPs or CuNPs on primary producers or ecosystem productivity. However, when combined with nutrient enrichment, both NPs intensified eutrophication. When either of these NPs were added in combination with nutrients, algal blooms persisted for >50 d longer than in the nutrient-only treatment. In the AuNP treatment, this shift from clear waters to turbid waters led to large declines in both macrophyte growth and rates of ecosystem gross primary productivity (average reduction of 52% ± 6% and 92% ± 5%, respectively) during the summer. Our results suggest that nutrient status greatly influences the ecosystem-scale impact of two emerging contaminants and that synthetic chemicals may be playing an under-appreciated role in the global trends of increasing eutrophication. We provide evidence here that chronic exposure to Au and Cu(OH)₂ nanoparticles at low concentrations can intensify eutrophication of wetlands and promote the occurrence of algal blooms.

Plant and Microbial Responses to Repeated Cu(OH)2 Nanopesticide Exposures Under Different Fertilization Levels in an Agro-Ecosystem

The environmental fate and potential impacts of nanopesticides on agroecosystems under realistic agricultural conditions are poorly understood. As a result, the benefits and risks of these novel formulations compared to the conventional products are currently unclear. Here, we examined the effects of repeated realistic exposures of the Cu(OH)2 nanopesticide, Kocide 3000, on simulated agricultural pastureland in an outdoor mesocosm experiment over 1 year. The Kocide applications were performed alongside three different mineral fertilization levels (Ambient, Low, and High) to assess the environmental impacts of this nanopesticide under low-input or conventional farming scenarios. The effects of Kocide over time were monitored on forage biomass, plant mineral nutrient content, plant-associated non-target microorganisms (i.e., N-fixing bacteria or mycorrhizal fungi) and six soil microbial enzyme activities. We observed that three sequential Kocide applications had no negative effects on forage biomass, root mycorrhizal colonization or soil nitrogen fixation rates. In the Low and High fertilization treatments, we observed a significant increase in aboveground plant biomass after the second Kocide exposure (+14% and +27%, respectively). Soil microbial enzyme activities were significantly reduced in the short-term after the first exposure (day 15) in the Ambient (-28% to -82%) and Low fertilization (-25% to -47%) but not in the High fertilization treatment. However, 2 months later, enzyme activities were similar across treatments and were either unresponsive or responded positively to subsequent Kocide additions. There appeared to be some long-term effects of Kocide exposure, as 6 months after the last Kocide exposure (day 365), both beta-glucosidase (-57% in Ambient and -40% in High fertilization) and phosphatase activities (-47% in Ambient fertilization) were significantly reduced in the mesocosms exposed to the nanopesticide. These results suggest that when used in conventional farming with high fertilization rates, Kocide applications did not lead to marked adverse effects on forage biomass production and key plant-microorganism interactions over a growing season. However, in the context of low-input organic farming for which this nanopesticide is approved, Kocide applications may have some unintended detrimental effects on microbially mediated soil processes involved in carbon and phosphorus cycling.

FGFR1 underlies obesity-associated progression of estrogen receptor-positive breast cancer after estrogen deprivation

Obesity increases breast cancer mortality by promoting resistance to therapy. Here, we identified regulatory pathways in estrogen receptor-positive (ER-positive) tumors that were shared between patients with obesity and those with resistance to neoadjuvant aromatase inhibition. Among these was fibroblast growth factor receptor 1 (FGFR1), a known mediator of endocrine therapy resistance. In a preclinical model with patient-derived ER-positive tumors, diet-induced obesity promoted a similar gene expression signature and sustained the growth of FGFR1-overexpressing tumors after estrogen deprivation. Tumor FGFR1 phosphorylation was elevated with obesity and predicted a shorter disease-free and disease-specific survival for patients treated with tamoxifen. In both human and mouse mammary adipose tissue, FGF1 ligand expression was associated with metabolic dysfunction, weight gain, and adipocyte hypertrophy, implicating the impaired response to a positive energy balance in growth factor production within the tumor niche. In conjunction with these studies, we describe a potentially novel graft-competent model that can be used with patient-derived tissue to elucidate factors specific to extrinsic (host) and intrinsic (tumor) tissue that are critical for obesity-associated tumor promotion. Taken together, we demonstrate that obesity and excess energy establish a tumor environment with features of endocrine therapy resistance and identify a role for ligand-dependent FGFR1 signaling in obesity-associated breast cancer progression.

Metformin inhibits stromal aromatase expression and tumor progression in a rodent model of postmenopausal breast cancer

BACKGROUND

Obesity and type II diabetes are linked to increased breast cancer risk in postmenopausal women. Patients treated with the antidiabetic drug metformin for diabetes or metabolic syndrome have reduced breast cancer risk, a greater pathologic complete response to neoadjuvant therapy, and improved breast cancer survival. We hypothesized that metformin may be especially effective when targeted to the menopausal transition, as this is a lifecycle window when weight gain and metabolic syndrome increase, and is also when the risk for obesity-related breast cancer increases.

METHODS

Here, we used an 1-methyl-1-nitrosourea (MNU)-induced mammary tumor rat model of estrogen receptor (ER)-positive postmenopausal breast cancer to evaluate the long-term effects of metformin administration on metabolic and tumor endpoints. In this model, ovariectomy (OVX) induces rapid weight gain, and an impaired whole-body response to excess calories contributes to increased tumor glucose uptake and increased tumor proliferation. Metformin treatment was initiated in tumor-bearing animals immediately prior to OVX and maintained for the duration of the study.

RESULTS

Metformin decreased the size of existing mammary tumors and inhibited new tumor formation without changing body weight or adiposity. Decreased lipid accumulation in the livers of metformin-treated animals supports the ability of metformin to improve overall metabolic health. We also found a decrease in the number of aromatase-positive, CD68-positive macrophages within the tumor microenvironment, suggesting that metformin targets the immune microenvironment in addition to improving whole-body metabolism.

CONCLUSIONS

These findings suggest that peri-menopause/menopause represents a unique window of time during which metformin may be highly effective in women with established, or at high risk for developing, breast cancer.

Predicting response to checkpoint inhibitors in melanoma beyond PD-L1 and mutational burden

BACKGROUND

Immune checkpoint inhibitors (ICIs) have changed the clinical management of melanoma. However, not all patients respond, and current biomarkers including PD-L1 and mutational burden show incomplete predictive performance. The clinical validity and utility of complex biomarkers have not been studied in melanoma.

METHODS

Cutaneous metastatic melanoma patients at eight institutions were evaluated for PD-L1 expression, CD8+ T-cell infiltration pattern, mutational burden, and 394 immune transcript expression. PD-L1 IHC and mutational burden were assessed for association with overall survival (OS) in 94 patients treated prior to ICI approval by the FDA (historical-controls), and in 137 patients treated with ICIs. Unsupervised analysis revealed distinct immune-clusters with separate response rates. This comprehensive immune profiling data were then integrated to generate a continuous Response Score (RS) based upon response criteria (RECIST v.1.1). RS was developed using a single institution training cohort (n = 48) and subsequently tested in a separate eight institution validation cohort (n = 29) to mimic a real-world clinical scenario.

RESULTS

PD-L1 positivity ≥1% correlated with response and OS in ICI-treated patients, but demonstrated limited predictive performance. High mutational burden was associated with response in ICI-treated patients, but not with OS. Comprehensive immune profiling using RS demonstrated higher sensitivity (72.2%) compared to PD-L1 IHC (34.25%) and tumor mutational burden (32.5%), but with similar specificity.

CONCLUSIONS

In this study, the response score derived from comprehensive immune profiling in a limited melanoma cohort showed improved predictive performance as compared to PD-L1 IHC and tumor mutational burden.

Abstract P5-05-03: Obesity drives breast cancer progression through estrogen dependent and independent mechanisms

Background: More than 200,000 women are diagnosed with breast cancer each year and 75% develop estrogen receptor positive (ER+) tumors. Obesity is an independent risk factor for the development of ER+ breast cancer, particularly after menopause, and affects 40% of US women. Obese women are more likely to be diagnosed with advanced tumors, lymph node involvement, and less likely to respond to endocrine therapy versus lean women. Mechanisms underlying the increased risk and worse prognosis of obese women are poorly understood. The dogma in the field states that estrogen production is the main contributor to obesity-associated ER+ breast cancer. We show that this is not always the case. Given the epidemic proportions of obesity in the US, we need better pre-clinical models that will inform focused clinical trials and interventions for patients. In this study, we describe a novel mouse model of obesity and ER+ breast cancer patient-derived xenografts (PDX). Our studies highlight the heterogeneity of responses within the ER+ breast cancer subtype to the obese environment and implicate both estrogen-dependent and independent mechanisms of obesity-associated tumor progression.

Methods: ER+, FGFR1-amplified or non-amplified human tumors were established in ovariectomized lean and obese mice in the presence of high or low estradiol (E2). To simulate the hormonal environment of women on aromatase inhibitors, E2 was removed from half of the mice in each adiposity group and the study was terminated 3 weeks later. Weight gain, body fat percentage, and adipose tissue as well as tumor characteristics were analyzed.

Results: Prior to EWD, obese mice were heavier and had higher body fat percentage than lean mice and also displayed a phenotype of metabolic dysfunction. This trend was accelerated after EWD, with obese mice gaining more weight due to body fat accumulation. Tumors responded in one of two ways: Regardless of FGFR1 amplification, obesity promoted ER+ tumor growth in the presence of low (postmenopausal), but not high (premenopausal) E2. In the presence of low E2, tumor PR levels were higher in obese compared to lean mice, suggesting hyperactive ER signaling. In FGFR1-amplified tumors, obesity promoted tumor growth after EWD. In addition, EWD induced excess fat deposition in visceral depots in both lean and obese mice; however, obese mice also gained fat in mammary adipose depots. Mammary fat pad mass and rate of post-EWD weight gain directly correlated with adipose FGF1 levels. Tumors from obese mice had higher levels of phosphorylated FGFR1, without changes in total FGFR1, compared to lean mice.

Conclusions: Utilizing a unique PDX model system, we show that obesity promotes tumor progression in the presence of low E2, and also after EWD, and identify growth factor receptor signaling as a mediator of these phenotypes. The activation of FGFR1 may underlie increased breast cancer risk and recurrence observed in obese, postmenopausal women.

Citation Format: Wellberg EA, Johnson SJ, Jacobsen BM, Anderson SM, Sartorius CA, MacLean PS, Kabos P. Obesity drives breast cancer progression through estrogen dependent and independent mechanisms [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-05-03.

Functional traits of the understory plant community of a pyrogenic longleaf pine forest across environmental gradients

Understanding and predicting the response of plant communities to environmental changes and disturbances such as fire requires an understanding of the functional traits present in the system, including within and across species variability, and their dynamics over time. These data are difficult to obtain as few studies provide comprehensive information for more than a few traits or species, rarely cover more than a single growing season, and usually present only summary statistics of trait values. As part of a larger study seeking to understand the dynamics of plant communities in response to different prescribed fire regimes, we measured the functional traits of the understory plant communities located in over 140 permanent plots spanning strong gradients in soil moisture in a pyrogenic longleaf pine forest in North Carolina, USA, over a four-year period from 2011 and 2014. We present over 120,000 individual trait measurements from over 130 plant species representing 91 genera from 47 families. We include data on the following 18 traits: specific leaf area, leaf dry matter content, leaf area, leaf length, leaf width, leaf perimeter, plant height, leaf nitrogen, leaf carbon, leaf carbon to nitrogen ratio, water use efficiency, time to ignition, maximum flame height, maximum burn temperature, mass-specific burn time, mass-specific smolder time, branching architecture, and the ratio of leaf matter consumed by fire. We also include information on locations, soil moisture, relative elevation, soil bulk density, and fire histories for each site.

Experiences of adolescent lung transplant recipients: A qualitative study

Many young transplant recipients experience psychological distress and adjustment difficulties, yet there is little research investigating lung transplantation from the recipients' perspective. This qualitative study aimed to explore experiences of young people who underwent lung transplantation. Semi-structured interviews were conducted with six lung transplant recipients (aged 15-18). Interviews were analysed using IPA, a qualitative research approach examining how people make sense of their major life experiences. The analysis revealed three master themes: "Living with Dodgy Lungs" outlined how participants dealt with their experiences, managing through accepting or discussing their feelings with others, although talking was often difficult. "The Big Deal" reflected participants' experiences of the process, their expectations, and the contrast of their lives pre- and post-transplant. Inherent in their accounts was the profound meaning ascribed to transplantation, the emotional turmoil, and impact on their lives. "A Sense of Self" illustrated participants' developing identities within their social contexts and at times isolating experiences. The results highlight key areas where adolescent lung transplant recipients could be supported by clinicians, enabling the promotion of psychological well-being. Examples include supporting identity integration post-transplant, facilitating social inclusion, considering alternative means of support, and involving adolescents in healthcare decisions.

Abstract P4-06-07: Fibroblast growth factor receptor activation and breast tumor progression in a mouse xenograft model of obesity

This abstract was withdrawn by the authors.

Metformin Accumulation Correlates with Organic Cation Transporter 2 Protein Expression and Predicts Mammary Tumor Regression In Vivo

Several epidemiologic studies have associated metformin treatment with a reduction in breast cancer incidence in prediabetic and type II diabetic populations. Uncertainty exists regarding which patient populations and/or tumor subtypes will benefit from metformin treatment, and most preclinical in vivo studies have given little attention to the cellular pharmacology of intratumoral metformin uptake. Epidemiologic reports consistently link western-style high fat diets (HFD), which drive overweight and obesity, with increased risk of breast cancer. We used a rat model of HFD-induced overweight and mammary carcinogenesis to define intratumoral factors that confer metformin sensitivity. Mammary tumors were initiated with 1-methyl-1-nitrosourea, and rats were randomized into metformin-treated (2 mg/mL drinking water) or control groups (water only) for 8 weeks. Two-thirds of existing mammary tumors responded to metformin treatment with decreased tumor volumes (P < 0.05), reduced proliferative index (P < 0.01), and activated AMPK (P < 0.05). Highly responsive tumors accumulated 3-fold greater metformin amounts (P < 0.05) that were positively correlated with organic cation transporter-2 (OCT2) protein expression (r = 0.57; P = 0.038). Importantly, intratumoral metformin concentration negatively associated with tumor volume (P = 0.03), and each 10 pmol increase in intratumoral metformin predicted >0.11 cm³ reduction in tumor volume. Metformin treatment also decreased proinflammatory arachidonic acid >1.5-fold in responsive tumors (P = 0.023). Collectively, these preclinical data provide evidence for a direct effect of metformin in vivo and suggest that OCT2 expression may predict metformin uptake and tumor response. Cancer Prev Res; 10(3); 198-207. ©2017 AACR.

The glucose transporter GLUT1 is required for ErbB2-induced mammary tumorigenesis

BACKGROUND

Altered tumor cell metabolism is an emerging hallmark of cancer; however, the precise role for glucose in tumor initiation is not known. GLUT1 (SLC2A1) is expressed in breast cancer cells and is likely responsible for avid glucose uptake observed in established tumors. We have shown that GLUT1 was necessary for xenograft tumor formation from primary mammary cells transformed with the polyomavirus middle-T antigen but that it was not necessary for growth after tumors had formed in vivo, suggesting a differential requirement for glucose depending on the stage of tumorigenesis.

METHODS

To determine whether GLUT1 is required early during mammary tumorigenesis, we crossed MMTV-NIC mice, which express activated HER2/NEU/ERBB2 and Cre recombinase, to Slc2a1 ^Flox/Flox (GLUT1^Flox/Flox) mice to generate NIC-GLUT1^+/+, NIC-GLUT1^Flox/+, and NIC-GLUT1^Flox/Flox mice. In addition, we evaluated effects of glucose restriction or GLUT1 inhibition on transformation in MCF10A-ERBB2 breast epithelial cells in three-dimensional culture. Finally, we utilized global gene expression profiling data of primary human breast tumors to determine the relationship between SLC2A1 and stage of tumorigenesis.

RESULTS

All of the NIC-GLUT1^+/+ mice developed tumors in less than 200 days. In contrast, only 1 NIC-GLUT1^Flox/Flox mouse and 1 NIC-GLUT1^Flox/+ mouse developed mammary tumors, even after 18 months. Mammary gland development was not disrupted in NIC mice lacking GLUT1; however, epithelial content of mature glands was reduced compared to NIC-GLUT1^Flox/+ mice. In MCF10A-ERBB2 cells, glucose restriction or GLUT1 inhibition blocked transformation induced by activated ERBB2 through reduced cell proliferation. In human breast cancers, SLC2A1 was higher in ductal carcinoma in situ compared to the normal breast, but lower in invasive versus in situ lesions, suggesting the requirement for GLUT1 decreases as tumors progress.

CONCLUSIONS

This study demonstrates a strict requirement for GLUT1 in the early stages of mammary tumorigenesis in vitro and in vivo. While metabolic adaptation has emerged as a hallmark of cancer, our data indicate that early tumor cells rely heavily on glucose and highlight the potential for glucose restriction as a breast cancer preventive strategy.

A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase

BACKGROUND

Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle.

METHODS

Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change.

RESULTS

PSSM1-affected horse muscle had significantly higher glycogen content than control horse muscle despite no difference in GS expression. GS activity was significantly higher in muscle from homozygous mutants than from heterozygote and control horses, in the absence and presence of the allosteric regulator, glucose 6 phosphate (G6P). Muscle from homozygous mutant horses also had significantly increased GS phosphorylation at sites 2+2a and significantly higher AMPKα1 (an upstream kinase) expression than controls, likely reflecting a physiological attempt to reduce GS enzyme activity. Recombinant mutant GS was highly active with a considerably lower K_m for UDP-glucose, in the presence and absence of G6P, when compared to wild type GS, and despite its phosphorylation.

CONCLUSIONS

Elevated activity of the mutant enzyme is associated with ineffective regulation via phosphorylation rendering it constitutively active. Modelling suggested that the mutation disrupts a salt bridge that normally stabilises the basal state, shifting the equilibrium to the enzyme's active state.

GENERAL SIGNIFICANCE

This study explains the gain of function pathogenesis in this highly prevalent polyglucosan myopathy.

Abstract PR03: GLUT1 is required for induction of mammary tumorigenesis by activated ErbB2/HER2/Neu

Alterations in tumor cell metabolism have been investigated for decades, and include changes in glucose utilization, as well as changes in mitochondrial and fatty acid metabolism; however, it is unclear at what point during the process of tumorigenesis these metabolic changes occur. We hypothesized that elevated glucose uptake represents the first metabolic adaptation to transformation, and thus may be a target for the prevention of breast cancer. The GLUT1 transporter is expressed in breast cancer cells and is responsible for the majority of their glucose uptake. Not surprisingly, breast cancer patients with high levels of GLUT1 have a poorer clinical outcome than those with lower levels, likely due to the association between glucose uptake and high tumor grade. We previously showed that the reduction of GLUT1 in established tumor cells resulted in a 50% decrease in glucose consumption and lactate generation. There was a corresponding decrease in proliferation in both two and three-dimensional culture, and in tumor growth in immunodeficient mice. Mammary epithelial cells from GLUT1fl/fl mice were transformed using polyoma middle tumor antigen (PyMT), and GLUT1 excised using Cre recombinase. Cells expressing GLUT1 were tumorigenic in immunodeficient mice, while cells lacking GLUT1 were not tumorigenic. This suggests that in mammary epithelial cells transformed in vitro, loss of GLUT1 was sufficient to prevent tumor outgrowths when injected into the mammary fat pad of nude mice. This indicates that GLUT1 and by extension glucose, are critical at an early stage of mammary tumorigenesis.

To test the hypothesis that elevated glucose uptake is required very early in the process of tumor formation, we crossed the MMTV-NIC (NIC) mice, which contain activated NeuNT, an internal ribosome entry site (IRES), and Cre recombinase, to mice bearing floxed alleles of GLUT1, and monitored tumor development. All of the control MMTV-NIC mice developed tumors in less than 200 days. In contrast, none of the NIC-GLUT1fl/fl mice developed mammary tumors even after eighteen months. We anticipated that loss of one allele of GLUT1 would significantly delay mammary tumorigenesis; however, we did not observe any tumors in these mice, even at eighteen months of age. Tumors that formed in the NIC mice were typical Neu-dependent tumors observed in similar transgenic mice with a high proliferative index (38% by Ki67 staining), and there was evidence of preneoplastic lesions in the non tumor-bearing mammary glands. Small Cre-positive lesions were also positive for GLUT1 indicating GLUT1 expression increases very early in Neu-mediated tumorigenesis. The mammary ductal tree developed normally in NIC-Glut1fl/fl and NIC-Glut1fl/+ mice. Mammary glands from mice lacking one allele of GLUT1 had increased epithelial content and higher proliferative index, compared to mice lacking both Glut1 alleles; however, no palpable tumors ever formed in either group. These results suggest that loss of a single allele of GLUT1 is sufficient to suppress Neu-induced mammary tumorigenesis and that there is an absolute requirement for GLUT1 at the earliest stages of tumorigenesis.

Citation Format: Elizabeth A. Wellberg, Angelo D'Allessandro, Andrew S. Lewis, Kristina Terrell, E. Dale Abel, William A. Muller, Kirk A. Hansen, Steven M. Anderson. GLUT1 is required for induction of mammary tumorigenesis by activated ErbB2/HER2/Neu. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr PR03.

Anxiolytic-like and anxiogenic-like effects of nicotine are regulated via diverse action at β2*nicotinic acetylcholine receptors

BACKGROUND AND PURPOSE

Nicotine dose-dependently activates or preferentially desensitizes β2 subunit containing nicotinic ACh receptors (β2*nAChRs). Genetic and pharmacological manipulations assessed effects of stimulation versus inhibition of β2*nAChRs on nicotine-associated anxiety-like phenotype.

EXPERIMENTAL APPROACH

Using a range of doses of nicotine in β2*nAChR subunit null mutant mice (β2KO; backcrossed to C57BL/6J) and their wild-type (WT) littermates, administration of the selective β2*nAChR agonist, 5I-A85380, and the selective β2*nAChR antagonist dihydro-β-erythroidine (DHβE), we determined the behavioural effects of stimulation and inhibition of β2*nAChRs in the light-dark and elevated plus maze (EPM) assays.

KEY RESULTS

Low-dose i.p. nicotine (0.05 mg·kg(-) 1) supported anxiolysis-like behaviour independent of genotype whereas the highest dose (0.5 mg·kg(-1) ) promoted anxiogenic-like phenotype in WT mice, but was blunted in β2KO mice for the measure of latency. Administration of 5I-A85380 had similar dose-dependent effects in C57BL/6J WT mice; 0.001 mg·kg(-1) 5I-A85380 reduced anxiety on an EPM, whereas 0.032 mg·kg(-1) 5I-A85380 promoted anxiogenic-like behaviour in both the light-dark and EPM assays. DHβE pretreatment blocked anxiogenic-like effects of 0.5 mg·kg(-1) nicotine. Similarly to DHβE, pretreatment with low-dose 0.05 mg·kg(-1) nicotine did not accumulate with 0.5 mg·kg(-1) nicotine, but rather blocked anxiogenic-like effects of high-dose nicotine in the light-dark and EPM assays.

CONCLUSIONS AND IMPLICATIONS

These studies provide direct evidence that low-dose nicotine inhibits nAChRs and demonstrate that inhibition or stimulation of β2*nAChRs supports the corresponding anxiolytic-like or anxiogenic-like effects of nicotine. Inhibition of β2*nAChRs may relieve anxiety in smokers and non-smokers alike.

Modulation of tumor fatty acids, through overexpression or loss of thyroid hormone responsive protein spot 14 is associated with altered growth and metastasis

Introduction

Spot14 (S14), encoded by the THRSP gene, regulates de novo fatty acid synthesis in the liver, adipose, and lactating mammary gland. We recently showed that S14 stimulated fatty acid synthase (FASN) activity in vitro, and increased the synthesis of fatty acids in mammary epithelial cells in vivo. Elevated de novo fatty acid synthesis is a distinguishing feature of many solid tumors compared with adjacent normal tissue. This characteristic is thought to be acquired during tumor progression, as rapidly proliferating cells have a heightened requirement for membrane phospholipids. Further, overexpression of FASN is sufficient to stimulate cell proliferation. While many studies have focused on the FASN enzyme in cancer biology, few studies have addressed the roles of proteins that modify FASN activity, such as S14.

Methods

Tumor fatty acids were modulated using two mouse models, mouse mammary tumor virus (MMTV)-neu mice overexpressing S14 and MMTV-polyomavirus middle T antigen (PyMT) mice lacking S14, and associations between elevated or impaired fatty acid synthesis on tumor latency, growth, metastasis, and signaling pathways were investigated. We evaluated S14-dependent gene expression profiles in mouse tumors by microarray and used publicly available microarray datasets of human breast tumors.

Results

S14 overexpression in the MMTV-Neu transgenic model is associated with elevated medium-chain fatty acids, increased proliferation and a shorter tumor latency, but reduced tumor metastasis compared to controls. Loss of S14 in the MMTV-PyMT model decreased FASN activity and the synthesis of medium-chain fatty acids but did not alter tumor latency. Impaired fatty acid synthesis was associated with reduced solid tumor cell proliferation, the formation of cystic lesions in some animals, and decreased phosphorylation of Src and protein kinase B (Akt). Analysis of gene expression in these mouse and human tumors revealed a relationship between S14 status and the expression of genes associated with luminal epithelial differentiation.

Conclusions

This study demonstrates a potential role for S14 in regulating mammary tumor growth and fatty acid synthesis in vivo. Furthermore, these results suggest that modulating the amount of medium chain fatty acids, by changing the levels of S14, has the potential to impact malignant mammary tumor phenotypes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0481-z) contains supplementary material, which is available to authorized users.

Abstract 1417: Stimulation of fatty acid synthesis by Spot14 enhances tumor cell proliferation but decreases metastasis in vivo

We have recently observed that Spot14 (S14), also known as Thyroid Hormone Responsive Protein, stimulates de novo fatty acid biosynthesis in mammary epithelial cells by increasing Fatty Acid Synthase (FASN) activity. In the presence of S14, FASN had increased Vmax, decreased Km, and shifted product formation toward medium chain fatty acids. Numerous studies have suggested that high expression of FASN is associated with higher tumor grade and poor clinical outcome, and likewise elevated expression of S14 has been linked to a poor clinical outcome for patients with invasive disease. In contrast, our analysis of S14 expression in databases of human breast tumors representing a variety of stages, grades, and subtypes suggests that high S14 is associated with ER-positive status, the luminal intrinsic subtype, and consequently, a favorable patient outcome. To determine the effect of S14 on mammary tumorigenesis in vivo, we crossed S14 null mice to MMTV-PyMT mice. Tumor latency was not altered in mice lacking S14; however, tumor cell proliferation was significantly decreased. Tumors arising in MMTV-PyMT mice lacking S14 were less dense and had a cystic morphology. There was a decrease in the phosphorylation of Src at Y416 and Akt at S473, indicating that activation of both signaling molecules was decreased in tumors lacking S14. Furthermore, tumors lacking S14 had reduced levels of de novo synthesized fatty acids. We also crossed MMTV-S14 transgenic mice expressing S14 in the mammary epithelium, to MMTV-Neu line 202 mice and observed that S14 overexpression significantly shortened tumor latency, increased tumor cell proliferation and increased concentration of fatty acids in tumor cells. Despite the increased proliferative index observed in the MMTV-Neu tumors expressing S14, there was a decrease in metastatic lesions detected in the lungs compared to MMTV-Neu mice. Gene expression profiling of mouse tumors revealed that tumors overexpressing S14 displayed features of lobular differentiation including increased expression of Elf5, a proposed master regulator of mammary differentiation, and expression of milk protein genes. Elevated fatty acid synthesis is a distinguishing feature of many solid tumors compared to adjacent normal tissue and this activity is thought to be acquired during tumor progression, as rapidly proliferating cancer cells have a heightened requirement for membrane phospholipid precursors. Our studies suggest that increased de novo fatty acid biosynthesis is sufficient to stimulate tumor cell proliferation; however, this is not correlated with increased metastasis, and in fact, tumors that expressed high levels of S14 appeared to have a more differentiated phenotype that may correlate with improved clinical outcome.

Citation Format: Elizabeth A. Wellberg, Michael C. Rudolph, Andrew Lewis, Steven M. Anderson. Stimulation of fatty acid synthesis by Spot14 enhances tumor cell proliferation but decreases metastasis in vivo. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1417. doi:10.1158/1538-7445.AM2014-1417

The glucose transporter Glut1 is selectively essential for CD4 T cell activation and effector function

CD4 T cell activation leads to proliferation and differentiation into effector (Teff) or regulatory (Treg) cells that mediate or control immunity. While each subset prefers distinct glycolytic or oxidative metabolic programs in vitro, requirements and mechanisms that control T cell glucose uptake and metabolism in vivo are uncertain. Despite expression of multiple glucose transporters, Glut1 deficiency selectively impaired metabolism and function of thymocytes and Teff. Resting T cells were normal until activated, when Glut1 deficiency prevented increased glucose uptake and glycolysis, growth, proliferation, and decreased Teff survival and differentiation. Importantly, Glut1 deficiency decreased Teff expansion and the ability to induce inflammatory disease in vivo. Treg cells, in contrast, were enriched in vivo and appeared functionally unaffected and able to suppress Teff, irrespective of Glut1 expression. These data show a selective in vivo requirement for Glut1 in metabolic reprogramming of CD4 T cell activation and Teff expansion and survival.

Thyroid hormone responsive protein Spot14 enhances catalysis of fatty acid synthase in lactating mammary epithelium

Thyroid hormone responsive protein Spot 14 has been consistently associated with de novo fatty acid synthesis activity in multiple tissues, including the lactating mammary gland, which synthesizes large quantities of medium chain fatty acids (MCFAs) exclusively via FASN. However, the molecular function of Spot14 remains undefined during lactation. Spot14-null mice produce milk deficient in total triglyceride and de novo MCFA that does not sustain optimal neonatal growth. The lactation defect was rescued by provision of a high fat diet to the lactating dam. Transgenic mice overexpressing Spot14 in mammary epithelium produced total milk fat equivalent to controls, but with significantly greater MCFA. Spot14-null dams have no diminution of metabolic gene expression, enzyme protein levels, or intermediate metabolites that accounts for impaired de novo MCFA. When [(13)C] fatty acid products were quantified in vitro using crude cytosolic lysates, native FASN activity was 1.6-fold greater in control relative to Spot14-null lysates, and add back of Spot14 partially restored activity. Recombinant FASN catalysis increased 1.4-fold and C = 14:0 yield was enhanced 4-fold in vitro following addition of Spot14. These findings implicate Spot14 as a direct protein enhancer of FASN catalysis in the mammary gland during lactation when maximal MCFA production is needed.

Inhibiting tyrosine phosphorylation of protein kinase Cδ (PKCδ) protects the salivary gland from radiation damage

Radiation therapy for head and neck cancer can result in extensive damage to normal adjacent tissues such as the salivary gland and oral mucosa. We have shown previously that tyrosine phosphorylation at Tyr-64 and Tyr-155 activates PKCδ in response to apoptotic stimuli by facilitating its nuclear import. Here we have identified the tyrosine kinases that mediate activation of PKCδ in apoptotic cells and have explored the use of tyrosine kinase inhibitors for suppression of irradiation-induced apoptosis. We identify the damage-inducible kinase, c-Abl, as the PKCδ Tyr-155 kinase and c-Src as the Tyr-64 kinase. Depletion of c-Abl or c-Src with shRNA decreased irradiation- and etoposide-induced apoptosis, suggesting that inhibitors of these kinases may be useful therapeutically. Pretreatment with dasatinib, a broad spectrum tyrosine kinase inhibitor, blocked phosphorylation of PKCδ at both Tyr-64 and Tyr-155. Expression of "gate-keeper" mutants of c-Abl or c-Src that are active in the presence of dasatinib restored phosphorylation of PKCδ at Tyr-155 and Tyr-64, respectively. Imatinib, a c-Abl-selective inhibitor, also specifically blocked PKCδ Tyr-155 phosphorylation. Dasatinib and imatinib both blocked binding of PKCδ to importin-α and nuclear import, demonstrating that tyrosine kinase inhibitors can inhibit nuclear accumulation of PKCδ. Likewise, pretreatment with dasatinib also suppressed etoposide and radiation induced apoptosis in vitro. In vivo, pre-treatment of mice with dasatinib blocked radiation-induced apoptosis in the salivary gland by >60%. These data suggest that tyrosine kinase inhibitors may be useful prophylactically for protection of nontumor tissues in patients undergoing radiotherapy of the head and neck.

The insulin receptor plays an important role in secretory differentiation in the mammary gland

Insulin is known to be an important regulator of milk secretion in the lactating mammary gland. Here we examine the role of insulin signaling in mammary development in pregnancy using a mouse with a floxed insulin receptor (IR) crossed with a mouse expressing Cre specifically in the mammary gland. In the mammary glands of these IR(fl/fl) Cre(+) mice, expression of IR is significantly diminished throughout development. Glands from these mice had 50% fewer alveoli at midpregnancy; casein and lipid droplets were diminished by 60 and 75%, respectively, indicating a role for IR both in alveolar development and differentiation. In an acinar preparation from mammary epithelial cells (MEC) isolated from pregnant mice, insulin stimulated lumen formation, mammary cell size, acinar size, acinar casein content, and the formation of lipid droplets with a Km of ∼1.7 nM. IGF-I and IGF-II had no effect at concentrations below 50 nM, and a function blocking antibody to the IGF type 1 receptor did not alter the response to insulin. We conclude that insulin interacting with IR is essential for mammary differentiation during murine pregnancy. Using array analysis, we then examined the expression of genes up- or downregulated >1.5-fold in the IR(fl/fl) Cre(+) MECs, finding significant downregulation of differentiation specific genes and upregulation of cell cycle and extracellular matrix genes. We conclude that insulin fosters differentiation and may inhibit cell proliferation in the mammary gland of the midpregnant mouse.

Glucose promotes breast cancer aggression and reduces metformin efficacy

Metformin treatment has been associated with a decrease in breast cancer risk and improved survival. Metformin induces complex cellular changes, resulting in decreased tumor cell proliferation, reduction of stem cells, and apoptosis. Using a carcinogen-induced rodent model of mammary tumorigenesis, we recently demonstrated that overfeeding in obese animals is associated with a 50% increase in tumor glucose uptake, increased proliferation, and tumor cell reprogramming to an "aggressive" metabolic state. Metformin significantly inhibited these pro-tumorigenic effects. We hypothesized that a dynamic relationship exists between chronic energy excess (glucose by dose) and metformin efficacy/action. Media glucose concentrations above 5 mmol/L was associated with significant increase in breast cancer cell proliferation, clonogenicity, motility, upregulation/activation of pro-oncogenic signaling, and reduction in apoptosis. These effects were most significant in triple-negative breast cancer (TNBC) cell lines. High-glucose conditions (10 mmol/L or above) significantly abrogated the effects of metformin. Mechanisms of metformin action at normal vs. high glucose overlapped but were not identical; for example, metformin reduced IGF-1R expression in both the HER2+ SK-BR-3 and TNBC MDA-MB-468 cell lines more significantly at 5, as compared with 10 mmol/L glucose. Significant changes in gene profiles related to apoptosis, cellular processes, metabolic processes, and cell proliferation occurred with metformin treatment in cells grown at 5 mmol/L glucose, whereas under high-glucose conditions, metformin did not significantly increase apoptotic/cellular death genes. These data indicate that failure to maintain glucose homeostasis may promote a more aggressive breast cancer phenotype and alter metformin efficacy and mechanisms of action.

Inducible overexpression of GLUT1 prevents mitochondrial dysfunction and attenuates structural remodeling in pressure overload but does not prevent left ventricular dysfunction

BACKGROUND

Increased glucose transporter 1 (GLUT1) expression and glucose utilization that accompany pressure overload-induced hypertrophy (POH) are believed to be cardioprotective. Moreover, it has been shown that lifelong transgenic overexpression of GLUT1 in the heart prevents cardiac dysfunction after aortic constriction. The relevance of this model to clinical practice is unclear because of the life-long duration of increased glucose metabolism. Therefore, we sought to determine if a short-term increase in GLUT1-mediated myocardial glucose uptake would still confer cardioprotection if overexpression occurred at the onset of POH.

METHODS AND RESULTS

Mice with cardiomyocyte-specific inducible overexpression of a hemagglutinin (HA)-tagged GLUT1 transgene (G1HA) and their controls (Cont) were subjected to transverse aortic constriction (TAC) 2 days after transgene induction with doxycycline (DOX). Analysis was performed 4 weeks after TAC. Mitochondrial function, adenosine triphosphate (ATP) synthesis, and mRNA expression of oxidative phosphorylation (OXPHOS) genes were reduced in Cont mice, but were maintained in concert with increased glucose utilization in G1HA following TAC. Despite attenuated adverse remodeling in G1HA relative to control TAC mice, cardiac hypertrophy was exacerbated in these mice, and positive dP/dt (in vivo) and cardiac power (ex vivo) were equivalently decreased in Cont and G1HA TAC mice compared to shams, consistent with left ventricular dysfunction. O-GlcNAcylation of Ca2+ cycling proteins was increased in G1HA TAC hearts.

CONCLUSIONS

Short-term cardiac specific induction of GLUT1 at the onset of POH preserves mitochondrial function and attenuates pathological remodeling, but exacerbates the hypertrophic phenotype and is insufficient to prevent POH-induced cardiac contractile dysfunction, possibly due to impaired calcium cycling.

Coat color genotypes and risk and severity of melanoma in gray quarter horses

BACKGROUND

Both graying and melanoma formation in horses have recently been linked to a duplication in the STX17 gene. This duplication, as well as a mutation in the ASIP gene that increases MC1R pathway signaling, affects melanoma risk and severity in gray horses.

OBJECTIVE

To determine if melanoma susceptibility in gray Quarter Horses (QH) is lower than gray horses from other breeds because of decreased MC1R signaling resulting from a high incidence of the MC1R chestnut coat color allele in the QH population.

ANIMALS

A total of 335 gray QH with and without dermal melanomas.

METHODS

Blood or hair root samples were collected from all horses for DNA extraction and genotyping for STX17, ASIP, and MC1R genotypes. Age, sex, and external melanoma presence and grade were recorded. The effect of age and genotype on melanoma presence and severity was evaluated by candidate gene association.

RESULTS

Melanoma prevalence (16%) and grade (0.35) in this QH cohort was lower than that reported in other breeds. Age was significantly associated with melanoma prevalence (P = 5.28 × 10(-11)) and severity (P = 2.2 × 10(-13)). No significant effect of MC1R genotype on melanoma prevalence or severity was identified. An effect of ASIP genotype on melanoma risk was not detected. Low STX17 homozygosity precluded evaluation of the gray allele effect.

CONCLUSION AND CLINICAL IMPORTANCE

Melanoma prevalence and severity is lower in this population of gray QH than what is reported in other breeds. This could be because of the infrequent STX17 homozygosity, a mitigating effect of the MC1R mutation on ASIP potentiation of melanoma, other genes in the MC1R signaling pathway, or differences in breed genetic background.

Long-term stability of RNA from FFPE brian tissue post-sectioning on slides

e22142

Background: Analysis of nucleic acids (NA) from formalin fixed paraffin embedded (FFPE) tissue can provide detailed information about gene sequence mutational status, which may be important for oncology treatment decisions. FFPE specimens also have utility for retrospective analyses. Potential degradation of NA during formalin fixation, paraffin embedding processes and possible continued deterioration during subsequent storage may diminish utility of FFPE tissue for these purposes. Using real-time PCR, this study investigated the functional stability of RNA from brain FFPE tissue sections on slides over an extended time period after sectioning. Methods: Brain biopsy specimens obtained from glioblastoma patients with informed consent were used to prepare blocks with standard formalin fixation and paraffin embedding techniques. Slides were made from the FFPE blocks and stored at room temperature until testing. RNA was extracted from sequential slides within one week of sectioning for a zero time and then at 4, 8 and 12 months. Reverse transcription PCR was performed, and real-time PCR was analyzed on the ABI7900 to detect EGFRvIII mutation and cABL gene. RNA Integrity Analysis was performed with an Agilent Bioanalyzer. Results: Consistent qualitative results were obtained with EGFRvIII mutant positive specimens (n =10) and wild type (wt) specimens (n =10) from slides stored up to twelve months at room temperature compared to the initial testing (95% agreement). One wt specimen showed negative results for the first three time points but a low positive result at 12 months, possibly due to tumor content change in the different sections of the FFPE block. Ct values for EGFR (wt and mutant) and cABL genes did not increase during the storage period. RNA integrity number (RIN) indicated the degradation of RNA during FFPE processing, although no further significant degradation occurred during the course of the experiment. Conclusions: The results of this study indicated that although the RNA was impacted by the tissue preparation, fixation, and processing steps, for the brain FFPE slide specimens, target genes with amplicon size up to 124bp could be detected with minimum degradation for up to 12 months when slides were stored at room temperature.

Clinical and analytical performance of non-small cell lung cancer biomarkers

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Background: A variety of biomarkers are currently used to help guide treatment decisions for patients with non-small cell lung cancer (NSCLC). These include mutation analysis for the EGFR and KRAS genes, along with gene rearrangement analysis for the ALK and ROS1 loci. In this study we have evaluated the clinical and analytical performance features of these assays in a series of formalin-fixed paraffin-embedded (FFPE) tissue samples. Methods: FFPE samples submitted for analysis of the EGFR, KRAS, ALK and ROS1 genes were evaluated using molecular and FISH assays. EGFR mutation analysis was performed using Sanger nucleic acid sequencing methods for exons 18-21. KRAS mutations were detected using allele specific PCR or pyrosequencing methods. Rearrangements involving the ALK gene were detected using break-apart FISH probes (Abbott Molecular). Genetic alterations involving the ROS1 gene were determined using FISH probes (Kreatech Diagnostics). Over 6,200 test results for these 4 markers are included in this analysis. Results: Mutations in the EGFR gene were detected in 10.1% of samples evaluated (n=3,872). A slightly higher percentage of samples from female patients (13%) had a detectable mutation compared to samples from males (7%) (chi-square p<0.0001). Deletions in exon 19 (51%) were the most common alterations detected, followed by point mutations in exon 21 (35%). KRAS mutations were detected in approximately 22% of specimens. ALK gene rearrangements were observed in 3.1% of samples (n=1,524). Specimens from individuals <50y of age were more likely to provide a positive result (11%) compared to samples from individuals >50y of age (2.5%) (chi-square p<0.0001). Gene amplification for the ALK gene was a common finding in the NSCLC samples evaluated. ROS1 alterations were detected in 2.8% of the specimens. In this cohort, no specimens were positive for both an EGFR mutation and an ALK gene rearrangement. Conclusions: Biomarker testing is well established in clinical practice for NSCLC, with results from the tests used to guide important therapy decisions. Assays for biomarkers such as EGFR, KRAS, ALK and ROS1 are robust, allowing for the analysis of multiple analytes in FFPE samples, even when the amount of tissue may be limiting.

Abstract P5-10-04: Metformin mediated upregulation of microRNA-193 triggers apoptosis by decreasing fatty acid synthase

Background: We have previously shown that the anti-diabetic drug metformin kills triple negative (TN) breast cancer cells lines via apoptosis, at lower IC50 than luminal and HER2 subtypes (presented at ENDO, manuscript in preparation). Metformin reportedly shows greater efficacy against stem cells than differentiated cells, reducing mammosphere formation in in non-adherent culture. Fatty acid synthase (FASN) is an enzyme critical for de novo fatty acid synthesis that is overexpressed in breast cancer.

Hypothesis: We hypothesized that miRNAs might be involved in the ability of metformin to preferentially kill TN cell lines at a lower IC50 than luminal A lines.

Methods: TN and luminal A (LA) breast cancer cell lines (MDA-468, HCC70 and MCF7, T47D, respectively) were used to study the effects of 10mM metformin action in vitro, at physiological and hyperglycemic culture conditions. Affymetrix chips Human Gene 1.1 and the miRNA 2.0 were utilized to profile gene and miRNA expression at 6 and 24 hrs. Mimics and lentiviral expression vectors were utilized to manipulate miRNA expression and a luciferase reporter was used to confirm miR-193 direct targeting of the FASN 3′ UTR.

Results: miR-193 is significantly higher in untreated LA as compared to TN cells. MiR-193 increases 2–4 fold within 6 hrs of metformin treatment in both TN, but not LA cell lines. A predicted target of miR-193, fatty acid synthase (FASN), is decreased by 8 fold following 24 hrs 10mM metformin treatment of the TN breast cancer cells. miR-193 directly targets FASN via a binding site in the 3′ UTR, downregulating gene expression. Restoration of miR-193 to TN lines, causes a dramatic decrease in FASN protein in a dose dependent fashion.

Conclusions and future directions: Metformin stimulates an increase in mature miR-193, which mediates the dramatic downregulation of FASN. This occurs coincident with apoptotic cell death. It remains to be determined if FASN is the only relevant direct target of miR-193 in TN cell lines. The addition of exogenous non-targetable FASN, lacking its 3′ UTR, will demonstrate whether this pathway is a primary mechanism of metformin action in TN cells. Future studies will investigate the ability of metformin to inhibit FASN in non-adherent mammosphere (stem cell-like) subpopulations, the role of fatty acid metabolism in mammosphere maintenance and anoikis resistance.

Supported by Komen Breast Cancer Foundation Grants KG100575 (ADT, JKR, SME, NSS) and KG090415 (JKR, DRC)

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-10-04.

Obesity and overfeeding affecting both tumor and systemic metabolism activates the progesterone receptor to contribute to postmenopausal breast cancer

Obese postmenopausal women have increased risk of breast cancers with poorer clinical outcomes than their lean counterparts. However, the mechanisms underlying these associations are poorly understood. Rodent model studies have recently identified a period of vulnerability for mammary cancer promotion, which emerges during weight gain after the loss of ovarian function (surgical ovariectomy; OVX). Thus, a period of transient weight gain may provide a life cycle-specific opportunity to prevent or treat postmenopausal breast cancer. We hypothesized that a combination of impaired metabolic regulation in obese animals prior to OVX plus an OVX-induced positive energy imbalance might cooperate to drive tumor growth and progression. To determine if lean and obese rodents differ in their metabolic response to OVX-induced weight gain, and whether this difference affects later mammary tumor metabolism, we performed a nutrient tracer study during the menopausal window of vulnerability. Lean animals preferentially deposited excess nutrients to mammary and peripheral tissues rather than to the adjacent tumors. Conversely, obese animals deposited excess nutrients into the tumors themselves. Notably, tumors from obese animals also displayed increased expression of the progesterone receptor (PR). Elevated PR expression positively correlated with tumor expression of glycolytic and lipogenic enzymes, glucose uptake, and proliferation markers. Treatment with the antidiabetic drug metformin during ovariectomy-induced weight gain caused tumor regression and downregulation of PR expression in tumors. Clinically, expression array analysis of breast tumors from postmenopausal women revealed that PR expression correlated with a similar pattern of metabolic upregulation, supporting the notion that PR+ tumors have enhanced metabolic capacity after menopause. Our findings have potential explanative power in understanding why obese, postmenopausal women display an increased risk of breast cancer.

Comparison of immunohistochemistry (IHC) and quantitative RT-PCR: ER, PR, and HER2 receptor status

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Background: IHC is the present standard for measuring estrogen (ER) and progesterone receptor (PR) expression for breast cancer. However, the lack of concordance between testing laboratories and the critical patient treatment decisions made with results prompted ASCO/CAP to recommend guidelines and proficiency testing requirements to ensure accuracy. Quantitative RT-PCR (qRT-PCR) is an alternative method for ER and PR testing and while concordance with IHC has been reported, additional testing is merited. This study compares ER, PR and HER2 status determined by IHC and qRT-PCR. Methods: FFPE tissues of ER(+) tumors collected and tested at the Blumenthal Cancer Center were studied. Expression levels of ESR1, PGR, and ERBB2 were determined by a multiplex qRT-PCR TaqMan assay and by the Oncotype Dx assay. Pre-established cutpoints were used to determine positivity. Only samples with qRT-PCR and corresponding IHC data were used, resulting in 144 ER, 128 PR, and 107 HER2 comparisons. ESR1 and PGR expression levels determined by the two qRT-PCR assays were also compared. Results: Of the144 IHC ER(+) samples, 142 were positive and 2 were negative by both qRT-PCR assays. All 120 IHC PR(+) samples were positive by both qRT-PCR assays. Of the 8 IHC PR(-) samples, 5 were negative and 3 were positive by both qRT-PCR assays. Of the 107 IHC HER2(-) samples, all but 2 were negative by qRT-PCR. One sample was positive by both qRT-PCR assays; one was positive by Oncotype Dx only. The expression levels determined by the qRT-PCR assays showed good correlation for ESR1 (r=0.85) and PGR (r=0.9). Conclusions: Concordance between qRT-PCR and IHC was 98.6% for ER and 97.7% for PR. Except for a single HER2 determination, there was 100% concordance between the two qRT-PCR assays. The discordant sample was HER2 (+) by multiplex qRT-PCR and “equivocal” by Oncotype Dx. Excellent correlation was also observed in the mRNA expression levels. The absence of HER2(+) and ER(-) samples are limitations of this study. These results suggest that qRT-PCR is a promising alternative method to IHC for determining hormone receptor status. Additional testing of samples with endocrine therapy outcomes including ER(-) samples would be beneficial.

Lactation and neonatal nutrition: defining and refining the critical questions

This paper resulted from a conference entitled "Lactation and Milk: Defining and refining the critical questions" held at the University of Colorado School of Medicine from January 18-20, 2012. The mission of the conference was to identify unresolved questions and set future goals for research into human milk composition, mammary development and lactation. We first outline the unanswered questions regarding the composition of human milk (Section I) and the mechanisms by which milk components affect neonatal development, growth and health and recommend models for future research. Emerging questions about how milk components affect cognitive development and behavioral phenotype of the offspring are presented in Section II. In Section III we outline the important unanswered questions about regulation of mammary gland development, the heritability of defects, the effects of maternal nutrition, disease, metabolic status, and therapeutic drugs upon the subsequent lactation. Questions surrounding breastfeeding practice are also highlighted. In Section IV we describe the specific nutritional challenges faced by three different populations, namely preterm infants, infants born to obese mothers who may or may not have gestational diabetes, and infants born to undernourished mothers. The recognition that multidisciplinary training is critical to advancing the field led us to formulate specific training recommendations in Section V. Our recommendations for research emphasis are summarized in Section VI. In sum, we present a roadmap for multidisciplinary research into all aspects of human lactation, milk and its role in infant nutrition for the next decade and beyond.

Muscle microvascular recruitment predicts insulin sensitivity in middle-aged patients with type 1 diabetes mellitus

AIMS/HYPOTHESIS

Insulin delivery to muscle is rate-limiting for insulin's metabolic action and is regulated by insulin's own action to increase skeletal muscle blood flow and to recruit microvasculature. Microvascular dysfunction has been observed in insulin resistant states. We investigated the relation between insulin's action to recruit microvasculature and its metabolic action in type 1 diabetes.

METHODS

Near euglycaemia was obtained by an overnight insulin infusion during 17 inpatient admissions of participants with type 1 diabetes. This was followed by a 2 h 1 mU kg⁻¹ min⁻¹ euglycaemic-hyperinsulinaemic clamp. Microvascular blood volume (MBV) was assessed using contrast-enhanced ultrasound 10 min before and 30 min after starting the clamp.

RESULTS

We observed that, after overnight modest hyperinsulinaemia (average ≈ 286 pmol/l), MBV was positively related to the steady-state insulin sensitivity measured during the subsequent clamp (r = 0.62, p = 0.008). The more marked hyperinsulinaemia during the clamp (average steady-state insulin ≈ 900 pmol/l) increased MBV in the more insulin resistant participants within 30 min but not in the insulin sensitive participants. The change in MBV during the clamp was negatively correlated to the insulin sensitivity (r = -0.55, p = 0.022). As a result, MBV after 30 min of marked hyperinsulinaemia was comparable between the insulin sensitive and resistant participants.

CONCLUSIONS/INTERPRETATION

We conclude that moderate overnight hyperinsulinaemia recruited microvasculature in the more sensitive participants, while higher levels of plasma insulin were needed for more insulin resistant participants. This suggests that microvascular responsiveness to insulin is one determinant of metabolic insulin sensitivity in type 1 diabetes.