Temporal transcriptome and metabolite analyses provide insights into the biochemical and physiological processes underlying endodormancy release in pistachio (Pistacia vera L.) flower buds

Pistachio (Pistacia vera L.), an economically and nutritionally important tree crop, relies on winter chill for bud endodormancy break and subsequent blooming and nut production. However, insufficient winter chill poses an increasing challenge in pistachio growing regions. To gain a better understanding of the physiological and biochemical responses of endodormant pistachio buds to chilling accumulation, we investigated the global gene expression changes in flower buds of pistachio cv. Kerman that were cultivated at three different orchard locations and exposed to increasing durations of winter chill. The expression of genes encoding β-1,3-glucanase and β-amylase, enzymes responsible for breaking down callose (β-1,3-glucan) and starch (α-1,4-glucan), respectively, increased during the endodormancy break of pistachio buds. This result suggested that the breakdown of callose obstructing stomata as well as the release of glucose from starch enables symplasmic trafficking and provides energy for bud endodormancy break and growth. Interestingly, as chilling accumulation increased, there was a decrease in the expression of nine-cis-epoxycarotenoid dioxygenase (NCED), encoding an enzyme that uses carotenoids as substrates and catalyzes the rate-limiting step in abscisic acid (ABA) biosynthesis. The decrease in NCED expression suggests ABA biosynthesis is suppressed, thus reducing inhibition of endodormancy break. The higher levels of carotenoid precursors and a decrease in ABA content in buds undergoing endodormancy break supports this suggestion. Collectively, the temporal transcriptome and biochemical analyses revealed that the degradation of structural (callose) and non-structural (starch) carbohydrates, along with the attenuation of ABA biosynthesis, are critical processes driving endodormancy break in pistachio buds.

Neutral-to-positive cadmium effects on germination and seedling vigor, with and without seed priming

This review gathered and analyzed data about (i) the Cd-induced impacts on seed germination and seedling vigor, and (ii) the use of different priming agents to mitigate Cd-induced impacts on the early plant development. Critical evaluation of the obtained data revealed intriguing results. First, seeds of diverse species can endure exposures to Cd. Such endurance is exhibited as maintenance of or even improvement in the seed germination and vigor (up to 15% and 70%, respectively). Second, the main factors influencing seed tolerance to Cd toxicity are related to temporal variations in anatomical, physiological, and/or biochemical features. Third, Cd can trigger diverse transgenerational effects on plants by shaping seed endophytes, by modulating seed provisioning with resources and regulatory elements, and/or by altering seed (epi)genomics. Fourth, different chemical, biological and physical priming agents can mitigate Cd-induced impacts on seeds, sometimes enhancing their performance over the control (reference) values. Overall, this review shows that the impacts of Cd on seed germination and vigor encompass not only negative outcomes but also neutral and positive ones, depending upon the Cd dose, media properties, plant species and genotypes, plant developmental stage and organ, and management approaches. Increasing our understanding of plant tolerance mechanisms against the growing background Cd pollution is relevant to support breeding programs, agricultural practices, and health-environmental policies.

Tree-level almond yield estimation from high resolution aerial imagery with convolutional neural network

Introduction

Estimating and understanding the yield variability within an individual field is critical for precision agriculture resource management of high value tree crops. Recent advancements in sensor technologies and machine learning make it possible to monitor orchards at very high spatial resolution and estimate yield at individual tree level.

Methods

This study evaluates the potential of utilizing deep learning methods to predict tree-level almond yield with multi-spectral imagery. We focused on an almond orchard with the 'Independence' cultivar in California, where individual tree harvesting and yield monitoring was conducted for ~2,000 trees and summer aerial imagery at 30cm was acquired for four spectral bands in 2021. We developed a Convolutional Neural Network (CNN) model with a spatial attention module to take the multi-spectral reflectance imagery directly for almond fresh weight estimation at the tree level.

Results

The deep learning model was shown to predict the tree level yield very well, with a R2 of 0.96 (±0.002) and Normalized Root Mean Square Error (NRMSE) of 6.6% (±0.2%), based on 5-fold cross validation. The CNN estimation captured well the patterns of yield variation between orchard rows, along the transects, and from tree to tree, when compared to the harvest data. The reflectance at the red edge band was found to play the most important role in the CNN yield estimation.

Discussion

This study demonstrates the significant improvement of deep learning over traditional linear regression and machine learning methods for accurate and robust tree level yield estimation, highlighting the potential for data-driven site-specific resource management to ensure agriculture sustainability.

Estimation of tomato water status with photochemical reflectance index and machine learning: Assessment from proximal sensors and UAV imagery

Tracking plant water status is a critical step towards the adaptive precision irrigation management of processing tomatoes, one of the most important specialty crops in California. The photochemical reflectance index (PRI) from proximal sensors and the high-resolution unmanned aerial vehicle (UAV) imagery provide an opportunity to monitor the crop water status efficiently. Based on data from an experimental tomato field with intensive aerial and plant-based measurements, we developed random forest machine learning regression models to estimate tomato stem water potential (ψ _stem), (using observations from proximal sensors and 12-band UAV imagery, respectively, along with weather data. The proximal sensor-based model estimation agreed well with the plant ψ _stem with R ² of 0.74 and mean absolute error (MAE) of 0.63 bars. The model included PRI, normalized difference vegetation index, vapor pressure deficit, and air temperature and tracked well with the seasonal dynamics of ψ _stem across different plots. A separate model, built with multiple vegetation indices (VIs) from UAV imagery and weather variables, had an R ² of 0.81 and MAE of 0.67 bars. The plant-level ψ _stem maps generated from UAV imagery closely represented the water status differences of plots under different irrigation treatments and also tracked well the temporal change among flights. PRI was found to be the most important VI in both the proximal sensor- and the UAV-based models, providing critical information on tomato plant water status. This study demonstrated that machine learning models can accurately estimate the water status by integrating PRI, other VIs, and weather data, and thus facilitate data-driven irrigation management for processing tomatoes.

Foliar Application of an Inositol-Based Plant Biostimulant Boosts Zinc Accumulation in Wheat Grains: A μ-X-Ray Fluorescence Case Study

There has been much interest in the incorporation of organic molecules or biostimulants into foliar fertilizers with the rationalization that these compounds will enhance the uptake, or subsequent mobility of the applied nutrient. The objective of this research was to investigate the effects of an inositol-based plant stimulant on the mobility and accumulation of foliar-applied zinc (Zn) in wheat plants (Triticum aestivum L.). High-resolution elemental imaging with micro-X-ray fluorescence (μ-XRF) was utilized to examine Zn distribution within the vascular bundle of the leaf and whole grains. The inclusion of myo-inositol with Zinc sulfate, significantly increased Zn concentration in shoots in contrast to untreated controls and Zn sulfate applied alone. Foliar Zn treated plants increased Zn in grains by 5-25% with myo-inositol plus Zn treated plants significantly increasing grain Zn concentration compared to both Zn treated and non-treated controls. XRF imaging revealed Zn enrichment in the bran layer and germ, with a very low Zn concentration present in the endosperm. Plants treated with Zn plus myo-inositol showed an enhanced and uniform distribution of Zn throughout the bran layer and germ with an increased concentration in the endosperm. While our data suggest that foliar application of myo-inositol in combination with Zn may be a promising strategy to increase the absorption and mobility of Zn in the plant tissue and subsequently to enhance Zn accumulation in grains, further research is needed to clarify the mechanisms by which myo-inositol affects plant metabolism and nutrient mobility.

A gift from parent to offspring: transgenerational hormesis

Hormesis is a biological phenomenon characterized by opposite effects between low and high doses of stresses that can result in stimulatory and adaptive benefits to individuals within a population. While evidence of hormesis is well established, two recent studies (Nogueira et al., Belz and Sinkkonen) suggest that hormesis can also offer transgenerational benefit.

Spatial imaging reveals the pathways of Zn transport and accumulation during reproductive growth stage in almond plants

The reproductive processes of several deciduous trees are highly sensitive to Zn deficiency. An understanding of the patterns of Zn storage and remobilization during bud development and bud break is critical for the development of fertilization strategies to prevent deficiencies and may be valuable in selection and breeding programs to develop more Zn-resilient cultivars. In this study, we provide insights into the in situ distribution of Zn in almond reproductive organs at tissue, cellular, and subcellular scales using synchrotron-based X-ray fluorescence. The concentrations of Zn in different parts of the vegetative and reproductive tissues were also analysed. Our results show that the small branches subtending the flower and fruit, pollen grain, transmitting tissues of styles, and seed embryo are all important storage sites for Zn. An increase in Zn concentrations in almond reproductive organs mostly occur during the expanding growth phase, such as bud-flush and the mid-fruit enlargement stage; however, Zn transport to floral parts and fruit tissues was restricted at the pedicel and seed coat, suggesting a bottleneck in the export of Zn from the mother plant to filial tissues. Our results provide direct visual evidence for in-situ Zn distribution within the reproductive tissues of a deciduous tree species.

Nutrient Storage in the Perennial Organs of Deciduous Trees and Remobilization in Spring - A Study in Almond (Prunus dulcis) (Mill.) D. A. Webb

The annual dynamics of whole mature almond tree nutrient remobilization in spring and the accumulation of nutrients in perennial tissues during the year were determined by sequential coring, tissue sampling, nutrient analysis, whole tree excavation and biomass estimation for trees grown under four nitrogen rate treatments 140 kg ha-1 N (N140), 224 kg ha-1 N (N224), 309 kg ha-1 N (N309), and 392 kg ha-1 N (N392) over 2 years. Whole tree perennial organ N content was greatest in dormancy then declined through bud swell, flowering and fruit set, achieving the lowest total whole tree nutrient content of perennial organs by March 12 [12-14 days after full bloom (DAFB)] coincident with 60-70% leaf expansion. During this period no net increment in whole tree N content (annual plus perennial N) was observed indicating that tree demand for N for bud break, flowering, fruit set and leaf out was met by remobilized stored N and that there was no net N uptake from soil. Remobilizable N increased with increasing N application up to N309 and was maximal at 44.4 ± 4 kg ha-1 and 37.5 ± 5.7 kg ha-1 for the optimally fertilized N309 in 2012 and 2013 respectively. Net increases in perennial organ N (stored N) commenced 41 DAFB and continued through full leaf abscission at 249 DAFB. Total annual N increment in perennial organs varied from 25 to 60 kg ha-1 and was strongly influenced by N rate and tree yield. N remobilized from senescing leaves contributed from 11 to 15.5 ± 0.6 kg ha-1 to perennial stored N. Similar patterns of nutrient remobilization and storage were observed for P, K, and S with maximal whole tree perennial storage occurring during dormancy and remobilization of that stored P, K, S to support annual tree demands through to fruit set and 70-100% leaf development. Net annual increment in perennial organ P, K, S commenced 98 DAFB and continued through full leaf abscission at 249 DAFB. Organ specific contribution to remobilizable and stored nutrients changes over the growing season are presented. Details of the pattern of perennial organ nutrient allocation, storage, and remobilization provides a framework for the optimal management of nutrients in almond with relevance for other deciduous tree species.

Intensive fertilizer use increases orchard N cycling and lowers net global warming potential

Nitrogen (N) fertilizer use has simultaneously increased global food production and N losses, resulting in degradation of water quality and climate pollution. A better understanding of N application rates and crop and environmental response is needed to optimize management of agroecosystems. Here we show an orchard agroecosystem with high N use efficiency promoted substantial gains in carbon (C) storage, thereby lowering net global warming potential (GWP). We conducted a 5-year whole-system analysis comparing reduced (224 kg N ha^-1 yr^-1) and intensive (309 kg N ha^-1 yr^-1) fertilizer N rates in a California almond orchard. The intensive rate increased net primary productivity (Mg C ha^-1) and significantly increased N productivity (kg N ha^-1) and net N mineralization (mg N kg^-1 soil d^-1). Use of ¹⁵N tracers demonstrated short and long-term mechanisms of soil N retention. These low organic matter soils (0.3-0.5%) rapidly immobilized fertilizer nitrate within 36 h of N application and ¹⁵N in tree biomass recycled back into soil organic matter over five years. Both fertilizer rates resulted in high crop and total N recovery efficiencies of 90% and 98% for the reduced rate, and 72% and 80% for the intensive rate. However, there was no difference in the proportion of N losses to N inputs due to a significant gain in soil total N (TN) in the intensive rate. Higher soil TN significantly increased net N mineralization and a larger gain in soil organic carbon (SOC) from the intensive rate offset nitrous oxide (N₂O) emissions, leading to significantly lower net GWP of -1.64 Mg CO₂-eq ha^-1 yr^-1 compared to -1.22 Mg CO₂-eq ha^-1 yr^-1 for the reduced rate. Our study demonstrates increased N cycling and climate mitigation from intensive fertilizer N use in this orchard agroecosystem, implying a fundamentally different result than seen in conventional annual cropping systems.

Advancing Agricultural Production With Machine Learning Analytics: Yield Determinants for California's Almond Orchards

Agricultural productivity is subject to various stressors, including abiotic and biotic threats, many of which are exacerbated by a changing climate, thereby affecting long-term sustainability. The productivity of tree crops such as almond orchards, is particularly complex. To understand and mitigate these threats requires a collection of multi-layer large data sets, and advanced analytics is also critical to integrate these highly heterogeneous datasets to generate insights about the key constraints on the yields at tree and field scales. Here we used a machine learning approach to investigate the determinants of almond yield variation in California's almond orchards, based on a unique 10-year dataset of field measurements of light interception and almond yield along with meteorological data. We found that overall the maximum almond yield was highly dependent on light interception, e.g., with each one percent increase in light interception resulting in an increase of 57.9 lbs/acre in the potential yield. Light interception was highest for mature sites with higher long term mean spring incoming solar radiation (SRAD), and lowest for younger orchards when March maximum temperature was lower than 19°C. However, at any given level of light interception, actual yield often falls significantly below full yield potential, driven mostly by tree age, temperature profiles in June and winter, summer mean daily maximum vapor pressure deficit (VPD_max), and SRAD. Utilizing a full random forest model, 82% (±1%) of yield variation could be explained when using a sixfold cross validation, with a RMSE of 480 ± 9 lbs/acre. When excluding light interception from the predictors, overall orchard characteristics (such as age, location, and tree density) and inclusive meteorological variables could still explain 78% of yield variation. The model analysis also showed that warmer winter conditions often limited mature orchards from reaching maximum yield potential and summer VPD_max beyond 40 hPa significantly limited the yield. Our findings through the machine learning approach improved our understanding of the complex interaction between climate, canopy light interception, and almond nut production, and demonstrated a relatively robust predictability of almond yield. This will ultimately benefit data-driven climate adaptation and orchard nutrient management approaches.

Efficient phloem remobilization of Zn protects apple trees during the early stages of Zn deficiency

Apple trees are extensively cultivated worldwide but are often affected by zinc (Zn) deficiency. Limited knowledge regarding Zn remobilization within fruit crops has hampered the development of efficient strategies for providing adequate amounts of Zn. In the present study, Zn distribution and remobilization were compared among apple trees cultivated under different Zn conditions. Without Zn application, plants showed visible symptoms of Zn deficiency at the shoot tips after 1 year but appeared to grow normally during the first 6 months (early stage of Zn deficiency). Compared with apple plants under sufficient Zn treatment, plants suffering from early-stage Zn deficiency showed preferential Zn distribution to young leaves and higher Zn levels in phloem, demonstrating that hidden Zn deficiency triggers a highly efficient remobilization of Zn in this species. The in vivo Zn-nicotianamine complex in phloem tissues, combined with the significant enhanced expression of MdNAS3 and MdYSL6, suggested a positive role for nicotianamine in the phloem remobilization of Zn. These results strongly suggest that a proportion of Zn in the old leaves of apple trees can be efficiently remobilized by phloem transport to the shoot tips, partially in the form of Zn-nicotianamine, thus protecting apple trees against the early stages of Zn deficiency.

Abstract OT2-09-01: Pilot study of denosumab in BRCA1/2 mutation carriers scheduling for risk-reducing salpingo-oophorectomy

Background: Denosumab is a monoclonal antibody that inhibits RANKL and is approved for the prevention of fractures in patients with osteoporosis or bone metastases. The RANKL signaling pathway is also involved in BRCA1-associated mammary tumorigenesis via a progesterone-induced paracrine effect of RANKL on luminal progenitor cells. Pre-clinical studies have demonstrated that RANKL inhibition resulted in reduced proliferation of mammary tumors. Early findings from an ongoing pre-surgical study demonstrated that denosumab treatment resulted in decreased Ki67 proliferation index in benign breast tissue. Based on these data, denosumab is being pursued as a potential preventive agent for breast cancer in BRCA1 mutation carriers. While promising, the effect of RANKL inhibition on gynecologic tissues such as the ovaries and fallopian tubes, in which progesterone has a protective effect, is unknown.

Trial design: We will conduct a multicenter, open-label randomized pilot study of presurgical administration of denosumab versus no treatment in premenopausal women with BRCA1/2 mutations undergoing risk-reducing salpingo-oophorectomy (RRSO). A total of 60 women will be randomized 1:1 to Arm 1) 3-4 doses of 120 mg denosumab subcutaneously every 4 weeks or Arm 2) No treatment. Participants will be stratified by 1) BRCA1 versus BRCA2 mutation status and 2) Use of hormonal contraceptives within the past 3 months (yes/no). Assuming a 10% unevaluable rate, we expect to have 54 evaluable participants (27 per arm).

Eligibility criteria: 1) Premenopausal women (defined as < 3 months since last menstrual period OR serum follicle-stimulating hormone (FSH) < 20 mIU/mL), age > 18 years; 2) Documented germline pathogenic mutation or likely pathogenic variant in the BRCA1 or BRCA2 gene; 3) Plan for RRSO with or without hysterectomy; 4) ECOG performance status ≤ 1 (Karnofsky ≥ 70%); 5) Normal organ and marrow function; 6) Negative pregnancy test and use of adequate contraception; 7) Willingness to take supplemental oral calcium and vitamin D3; 8) Dental examination within 6 months of enrollment and no evidence of active dental issues; 9) Ability to understand and willingness to provide informed consent.

Specific aims: Our primary objective is to compare the effect of denosumab to no treatment on Ki67 expression in the fimbrial end of the fallopian tube. Secondary objectives are to assess Ki67 in ovary and endometrium; cleaved caspase-3, RANK/RANKL, ER/PR, CD44, and STAT3/pSTAT3 expression in fallopian tube, ovary, and endometrium; gene expression profiling in the fallopian tube and ovary; serum markers (progesterone, estradiol, C-terminal telopeptide) and denosumab levels; and toxicity.

Statistical methods: The primary endpoint is post-treatment Ki67 expression in the fimbrial end of the fallopian tube in the denosumab arm compared to the no treatment arm. Assuming a standard deviation of 5.0%, we will have 82% power to detect a 4.0% absolute difference (or effect size of 0.8) in Ki67 proliferation index between the denosumab and no treatment groups by applying a 2-sample t-test at a 0.05 significance level.

Target accrual: 60 participants, to be activated in Summer 2018.

Citation Format: Trivedi MS, Samimi G, Wright JD, Holcomb K, Garber JE, Horowitz NS, Arber N, Friedman E, Wenham RM, House M, Parnes H, Lee JJ, Abutaseh S, Vornik LA, Heckman-Stoddard BM, Brown PH, Crew KD. Pilot study of denosumab in BRCA1/2 mutation carriers scheduling for risk-reducing salpingo-oophorectomy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-09-01.

Abstract OT2-09-02: A phase I dose escalation study of topical bexarotene in women at high risk for breast cancer

Background: Breast cancer prevention with anti-estrogens, including tamoxifen, raloxifene, and exemestane, has been shown to reduce the incidence of hormone receptor-positive breast cancer. However, agents that can reduce the incidence of hormone receptor negative breast cancer are currently lacking. Rexinoids such as bexarotene are vitamin A analogues that have been shown to be involved in cell differentiation, growth, and apoptosis. In preclinical mouse models that develop ER-negative breast cancers, bexarotene showed a significant reduction in mammary tumor development. Oral bexarotene has been evaluated in BRCA mutation carriers and significant decreases in cyclin D1 were noted in breast cells suggesting biological activity of bexarotene on breast tissue. Systemic side effects of hyperlipidemia and hypothyroidism were also found. Data from chemoprevention studies with topical 4-hydroxytamoxifen support the concept of topical agents penetrating into the breast tissue and exhibiting biological activity in the tissue. We hypothesize that topical bexarotene can be applied to the breast as a chemoprevention agent with penetration to the breast tissue without subsequent systemic side effects and toxicity as seen with oral bexarotene.

Trial Design: Women at high risk for breast cancer will be recruited and assigned to one of three different dose levels: 10mg (1ml) every other day, 10mg (1ml) daily, 20mg (2ml) daily to one unaffected breast for 4 weeks. The primary endpoint of the study is to determine the recommended phase II dose of topical bexarotene 1% gel for evaluation in healthy at-risk women. Dose Limiting Toxicity (DLT) is defined as a grade 2 skin adverse event that persists for at least 6 days or any grade 3 or greater adverse event related to the study drug. A grade 2 skin adverse event that recurs and persists for at least 3 days is also a DLT. The Maximum Tolerated Dose (MTD) will be defined as the highest dose level at which no more than 2 participants experience a DLT among 10 participants treated. A conservative modification of the standard “3+3” design will be applied. The first three participants will be assigned to the lowest dose level. New cohorts of 3-4 participants will not be treated until toxicity has been fully evaluated for all current participants through 4 weeks. Once the MTD has been determined, an expansion cohort of an additional 10 patients will be recruited at the MTD to further evaluate safety and toxicity at this dose level as well bexarotene concentration in the breast tissue. Secondary endpoints include serum bexarotene level, tissue bexarotene levels, and changes in thyroid function tests, lipid profile, and calcium. The planned accrual for this study if maximally accrued to all dose levels and the dose expansion cohort will be 40 participants.

Citation Format: Thomas PS, Patel AB, Contreras A, Liu DD, Lee JJ, Khan S, Vornik LA, Dimond EP, Perloff M, Heckman-Stoddard BM, Brown PH. A phase I dose escalation study of topical bexarotene in women at high risk for breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-09-02.

Abstract PD3-07: A phase II pre-surgical trial of lapatinib for the treatment of women with HER2 positive or EGFR positive ductal carcinoma in situ

Background: Estrogen receptor (ER)-negative tumors and human epidermal growth factor 2-Neu (HER2) positive breast cancers are known to be more clinically aggressive subtypes of breast cancer and account for 30% of all breast cancers. Women with HER2 + breast cancers, whether ER+ or ER -, require cytotoxic chemotherapy with a HER2-targeting agent, and often have adverse outcomes. Thus, preventive agents are needed to reduce the incidence of these subtypes of aggressive breast cancer. Lapatinib, a dual tyrosine kinase inhibitor, inhibits epidermal growth factor receptors (EGFR) and HER2 kinases and has shown to decrease breast cell proliferation in invasive breast cancer and adjacent premalignant lesions. Therefore, we conducted a multi-institutional randomized Phase II clinical trial to study the effects of the signal transduction inhibitor lapatinib in women with HER2-positive or EGFR-positive ductal carcinoma in situ (DCIS).

Methods: Randomized participants received either lapatinib (750mg, 1000mg, or 1500mg) or placebo daily for 2-6 weeks prior to their surgery. After minimal accrual, the trial was later amended to lapatinib 1000mg or placebo. Pre-treatment breast tissue was obtained from initial diagnostic core biopsy and post-treatment breast tissue was obtained from surgical excision specimen. Blood was obtained prior to surgery to assess serum lapatinib level. Participants kept a daily symptom assessment log and had a cardiac assessment at baseline and prior to surgery. Patients were instructed to take drug up to and including the day before surgery. The dual primary endpoint for this study was change in proliferation in pre- versus post-treatment biopsies between the two treatment arms, as measured by Ki67 as well as toxicity assessment. Secondary endpoints included incidence of DCIS at surgery and modulation of tissue biomarker expression in growth factor receptors (EGFR, ErbB2); phosphorylated growth factor receptor (phospho-ErbB2); signal transduction markers (MAPK, phospho-MAPK); hormone receptors (ER, PR); and p27.

Results:Twenty-two women (mean age: 51; range: 32-66) with HER2+ or EGFR+ DCIS were treated with lapatinib (1,000 or 1,500 mg) or placebo for 2–6 weeks prior to surgical excision. Ki67 expression was significantly decreased in the lapatinib treatment arms compared to placebo (p=0.0122). Diarrhea, fatigue, and skin reactions were notable adverse events that occurred predominately in the lapatinib arm compared to placebo. No grade 3 or 4 events related to the study drug were noted during the study. No changes were noted in cardiac function. DCIS was present in all surgical specimens in both arms. Invasive breast cancer was noted in 1 patient on lapatinib 1000mg and 3 patients on placebo. No statistically significant changes were noted in signal transduction biomarkers

Conclusion:These results demonstrate the effectiveness of lapatinib in reducing proliferation in women with EGFR+ or HER2+ DCIS. Even low-grade toxicities can deter use of an agent in the prevention setting. This and the lack of a risk model for HER2+ and triple negative breast cancer make the development of larger scale clinical prevention trials of lapatinib for the prevention a challenge.

Citation Format: Thomas PS, Contreras A, Pruthi S, Krontiras H, Rimawi M, Garber J, Wang T, Hilsenbeck SG, Vornik LA, Gilmer T, Friedman R, Heckman-Stoddard BM, Dunn B, Kuerer H, Brown PH. A phase II pre-surgical trial of lapatinib for the treatment of women with HER2 positive or EGFR positive ductal carcinoma in situ [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD3-07.

Abstract P5-15-02: Withdrawn

This abstract was withdrawn by the authors.

Grower Analysis of Organic Matter Amendments in California Orchards

Organic matter amendments supply crop nutrients and enhance soil health, yet information specific to orchards is lacking. A survey was conducted to analyze use of these materials by California almond [ (Mill.) D.A. Webb] growers. Significant differences were observed for benefits, concerns, and accessibility to manure and green waste sources and between users and nonusers. Use patterns were significantly influenced by heavy and light users, farm size, and geographic region. Enhanced soil biology was the main benefit attributed to organic matter amendments by both users and nonusers. Nonusers showed greater concern for food safety compared to users, and all growers reported greater concern for food safety from manure. The greatest adoption of organic matter amendments occurred on small farms (≤170 ha) located in the north San Joaquin Valley in California. Greater accessibility to manure correlated with presence of dairy farms. Poorer accessibility ratings by nonusers suggest access is a barrier to adoption, as opposed to nonusers having an undesirable view of the practice. Common management included applying organic matter amendments during tree dormancy from manure sources in composted forms with no-till. Heavy users on small farms exhibited the greatest year-to-year consistency and were more flexible with selection of sources and diverse in application methods. Large farms (>170 ha) were less likely to use organic matter amendments every year and less likely to apply them on all their farm area. This study identifies a number of strategies to fill knowledge gaps, increase practice awareness, and overcome barriers to adoption.

Uptake, sequestration and tolerance of cadmium at cellular levels in the hyperaccumulator plant species Sedum alfredii

Sedum alfredii is one of a few plant species known to hyperaccumulate cadmium (Cd). Uptake, localization, and tolerance of Cd at cellular levels in shoots were compared in hyperaccumulating (HE) and non-hyperaccumulating (NHE) ecotypes of Sedum alfredii. X-ray fluorescence images of Cd in stems and leaves showed only a slight Cd signal restricted within vascular bundles in the NHEs, while enhanced localization of Cd, with significant tissue- and age-dependent variations, was detected in HEs. In contrast to the vascular-enriched Cd in young stems, parenchyma cells in leaf mesophyll, stem pith and cortex tissues served as terminal storage sites for Cd sequestration in HEs. Kinetics of Cd transport into individual leaf protoplasts of the two ecotypes showed little difference in Cd accumulation. However, far more efficient storage of Cd in vacuoles was apparent in HEs. Subsequent analysis of cell viability and hydrogen peroxide levels suggested that HE protoplasts exhibited higher resistance to Cd than those of NHE protoplasts. These results suggest that efficient sequestration into vacuoles, as opposed to rapid transport into parenchyma cells, is a pivotal process in Cd accumulation and homeostasis in shoots of HE S. alfredii. This is in addition to its efficient root-to-shoot translocation of Cd.

Abstract OT3-01-04: VADIS trial: Phase II trial of the nelipepimut-S peptide v accine in women with DCIS of the breast

Background: Our group has been investigating vaccination strategies in breast cancer. Specifically, we have been evaluating HER2-derived peptide vaccines including nelipepimut-S+GM-CSF administered adjuvantly to breast cancer patients who have been rendered disease-free with standard of care therapy but are at high risk for recurrence. Early phase clinical trials showed an approximately 50% reduction in relative recurrence risk in vaccinated patients. Based on these data, nelipepimut-S+GM-CSF is being evaluated in a phase III registration trial. Having shown the vaccine to be safe, effective in stimulating an antigen-specific immune response and potentially having clinical efficacy in the setting of secondary prevention, the current study was initiated to evaluate vaccination in DCIS patients. This trial represents an initial step to move the vaccine into the primary prevention setting.

Trial Design: Phase II, randomized, single-blind study. Patients will be randomized 2:1 to receive vaccine or GM-CSF alone. After enrollment, patients will receive 3 inoculations administered every other week preoperatively followed by surgery then completion of the vaccination series (3 additional inoculations) in the adjuvant setting.

Eligibility: The trial will enroll pre- or post-menopausal women with a diagnosis of DCIS made by core biopsy. The area of radiographic abnormality must measure at least 1 cm. Because the vaccine is a MHC class I, CD8+ T cell-eliciting vaccine, it is HLA restricted, and patients must be HLA-A2+ to enroll. Participants must also have an ECOG performance status <2, adequate cardiac, kidney and liver function and be willing to comply with all study interventions and follow-up procedures.

Specific Aims: The trial's primary endpoint is to evaluate for nelipepimut-specific CD8+ T cells in the peripheral blood of vaccinated patients compared to patients receiving GM-CSF alone. Secondary endpoints include evaluating toxicity; determining the immune response in vivo by DTH, in vitro by evaluating for epitope spreading to other tumor antigens, and importantly in the tumor by assessing the degree of lymphocytic infiltration in surgically resected specimens. The extent of HER2 expression, Ki67 and cleaved caspase 3 in the resected specimen will also be assessed.

Statistical Methods: A total of 108 DCIS patients will be consented and screened for eligibility. 48 (45%) are expected to be HLA-A2 positive. These 48 patienst will be randomized 2:1 to vaccine or GM-CSF alone groups. Accounting for 10% attrition rate and for an approximately 5% non-evaluable sample rate, we expect to have 40 evaluable patients, 27 in the vaccine group and 13 in the GM-CSF alone group, that have baseline, pre-surgery, and post-surgery measures of nelipepimut-S-specific CD8+ T cells. We will have 82% power to detect a significant increase in nelipepimut-S-specific CD8+ T cells in the vaccine group versus the GM-CSF alone group.

Contact Info: The study is accruing at four sites to include Columbia University, Dana Farber Cancer Institute, MD Anderson Cancer Center and Memorial Sloan Kettering Cancer Center. Additional information can be obtained from the overall study PI, Dr. Elizabeth Mittendorf (eamitten@mdanderson.org). NCT0236582.

Citation Format: Mittendorf EA, Plitas G, Garber J, Crew K, Heckman-Stoddard B, Wojtowicz M, Vornik L, Peoples GE, Brown PH. VADIS trial: Phase II trial of the nelipepimut-S peptide vaccine in women with DCIS of the breast [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-01-04.

Abstract P3-07-07: Inhibition of death-associated protein kinase 1 enhances chemotherapy action against triple-negative breast cancer

Background: Triple negative breast cancers (TNBCs) are the most aggressive ER negative breast cancers with limited therapy strategies and poor prognosis. P53 gene is frequently mutated in approximately 80% of TNBCs. To identify novel molecular targets for ER negative breast cancer, particularly the more aggressive TNBC, we conducted a human kinome screen and identified death-associated protein kinase 1 (DAPK1) as one of the kinases that are highly expressed in ER negative breast cancer. Deletion or inhibition of DAPK1 suppresses growth of p53-mutant but not p53-wildtype breast cancer cells. Here we investigate whether DAPK1 inhibition will enhance chemotherapy action against p53-mutant TNBCs.

Experimental design and methods: We performed experiments to test cell growth of p53-mutant TNBCs that were treated with DAPK1 siRNA or DAPK1 inhibitors in combination with different doses of chemotherapy drugs including 5-FU (5-Fluorouracil), doxorubicin, cisplatin, PARP inhibitor (BMN673), paclitaxel, gemcitabine and vinorelbine.

Results: Our results show that DAPK1 inhibitors enhance the growth inhibitory effects of cisplatin and PARP inhibitor in p53-mutant TNBCs. Furthermore, combined DAPK1 inhibition (via siRNA knockdown) with cisplatin synergistically inhibits cell growth of p53-mutant TNBCs.

Conclusion: DAPK1 is a novel, promising target for the treatment of triple-negative p53-mutant breast cancer. Our studies demonstrate that DAPK1 inhibition sensitizes TNBCs to the cytotoxic effects of cisplatin or the PARP inhibitor. We are now conducting studies to determine whether DAPK1 inhibition will sensitize TNBC tumors and patient-derived TNBC xenografts to the effects of cisplatin and PARP inhibition. These studies suggest that the combination of DAPK1 inhibition with drugs that interfere with DNA repair will be useful for the treatment of the most aggressive form of breast cancer, triple-negative breast cancer.

Funding: This study was funded by a Susan G. Komen Promise grant (SAB12-00006 to P.H. Brown), a MD Anderson Knowledge Gap Moonshot grant (to P.H. Brown) and a Breast Cancer Research Foundation grant (BCRF 15101807, 2015–2016 to P.H. Brown).

Citation Format: Zhao D, Zhao J, Mazumadar A, Bollu L, Shepherd J, Ma Y, Zhang Y, Hill JL, Savage MI, Brown PH. Inhibition of death-associated protein kinase 1 enhances chemotherapy action against triple-negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-07-07.

Biostimulants in Plant Science: A Global Perspective

This review presents a comprehensive and systematic study of the field of plant biostimulants and considers the fundamental and innovative principles underlying this technology. The elucidation of the biological basis of biostimulant function is a prerequisite for the development of science-based biostimulant industry and sound regulations governing these compounds. The task of defining the biological basis of biostimulants as a class of compounds, however, is made more complex by the diverse sources of biostimulants present in the market, which include bacteria, fungi, seaweeds, higher plants, animals and humate-containing raw materials, and the wide diversity of industrial processes utilized in their preparation. To distinguish biostimulants from the existing legislative product categories we propose the following definition of a biostimulant as "a formulated product of biological origin that improves plant productivity as a consequence of the novel or emergent properties of the complex of constituents, and not as a sole consequence of the presence of known essential plant nutrients, plant growth regulators, or plant protective compounds." The definition provided here is important as it emphasizes the principle that biological function can be positively modulated through application of molecules, or mixtures of molecules, for which an explicit mode of action has not been defined. Given the difficulty in determining a "mode of action" for a biostimulant, and recognizing the need for the market in biostimulants to attain legitimacy, we suggest that the focus of biostimulant research and validation should be upon proof of efficacy and safety and the determination of a broad mechanism of action, without a requirement for the determination of a specific mode of action. While there is a clear commercial imperative to rationalize biostimulants as a discrete class of products, there is also a compelling biological case for the science-based development of, and experimentation with biostimulants in the expectation that this may lead to the identification of novel biological molecules and phenomenon, pathways and processes, that would not have been discovered if the category of biostimulants did not exist, or was not considered legitimate.

Biostimulants in Plant Science: A Global Perspective

This review presents a comprehensive and systematic study of the field of plant biostimulants and considers the fundamental and innovative principles underlying this technology. The elucidation of the biological basis of biostimulant function is a prerequisite for the development of science-based biostimulant industry and sound regulations governing these compounds. The task of defining the biological basis of biostimulants as a class of compounds, however, is made more complex by the diverse sources of biostimulants present in the market, which include bacteria, fungi, seaweeds, higher plants, animals and humate-containing raw materials, and the wide diversity of industrial processes utilized in their preparation. To distinguish biostimulants from the existing legislative product categories we propose the following definition of a biostimulant as "a formulated product of biological origin that improves plant productivity as a consequence of the novel or emergent properties of the complex of constituents, and not as a sole consequence of the presence of known essential plant nutrients, plant growth regulators, or plant protective compounds." The definition provided here is important as it emphasizes the principle that biological function can be positively modulated through application of molecules, or mixtures of molecules, for which an explicit mode of action has not been defined. Given the difficulty in determining a "mode of action" for a biostimulant, and recognizing the need for the market in biostimulants to attain legitimacy, we suggest that the focus of biostimulant research and validation should be upon proof of efficacy and safety and the determination of a broad mechanism of action, without a requirement for the determination of a specific mode of action. While there is a clear commercial imperative to rationalize biostimulants as a discrete class of products, there is also a compelling biological case for the science-based development of, and experimentation with biostimulants in the expectation that this may lead to the identification of novel biological molecules and phenomenon, pathways and processes, that would not have been discovered if the category of biostimulants did not exist, or was not considered legitimate.

Biointeractions of ultrasmall glutathione-coated gold nanoparticles: effect of small size variations

Recent in vivo studies have established ultrasmall (<3 nm) gold nanoparticles coated with glutathione (AuGSH) as a promising platform for applications in nanomedicine. However, systematic in vitro investigations to gain a more fundamental understanding of the particles' biointeractions are still lacking. Herein we examined the behavior of ultrasmall AuGSH in vitro, focusing on their ability to resist aggregation and adsorption from serum proteins. Despite having net negative charge, AuGSH particles were colloidally stable in biological media and able to resist binding from serum proteins, in agreement with the favorable bioresponses reported for AuGSH in vivo. However, our results revealed disparate behaviors depending on nanoparticle size: particles between 2 and 3 nm in core diameter were found to readily aggregate in biological media, whereas those strictly under 2 nm were exceptionally stable. Molecular dynamics simulations provided microscopic insight into interparticle interactions leading to aggregation and their sensitivity to the solution composition and particle size. These results have important implications, in that seemingly small variations in size can impact the biointeractions of ultrasmall AuGSH, and potentially of other ultrasmall nanoparticles as well.

Abstract P4-14-22: A single-center, open-label phase 1b study of entinostat, and lapatinib alone, and in combination with and trastuzumab in patients with HER2+ metastatic breast cancer after progression on trastuzumab

Background: Our in vitro and in vivo preclinical data showed that entinostat enhances the efficacy of lapatinib in HER2 positive (HER2+) breast cancer cells via FOXO3-mediated Bim1 expression, which resulted in enhanced apoptosis in HER2 targeted therapy (lapatinib and trastuzumab)-resistant breast cancer (IBC and non-IBC) cells [Lee et al.]. Based on these findings, we conducted a phase 1b trial of entinostat to determine the maximal tolerated dose (MTD) in combination with lapatinib alone and in combination with lapatinib and trastuzumab for metastatic HER2+ breast cancer patients (pts), who progressed on trastuzumab.

Method: This was a single-center, open-label phase 1b study to evaluate the dose limiting toxicity (DLT) and determine MTD. 3+3 dose escalation schedule was used for Cohorts 1 and 2. Pts received lapatinib and entinostat (Cohort 1) or entinostat, lapatinib, and trastuzumab (Cohort 2). Initial dose of lapatinib 1250mg in Cohort 1 and 1000mg for Cohort 2 to match standard dose in combination with trastuzumab dose. In Cohort 1, entinostat was given PO on day 1 and 15 every 28 days cycle at dose levels 10 mg (level 0), 12 mg (level 1), or 15 mg (level 2). The dose levels for Cohort 2 were 12 mg (co-level 0) or 15 mg (co-level 1) on day 1 and 15 every 28 days cycle. While lapatinib and entinostat were given 28 days cycle due to entinostat dosing, the dosing of trastuzumab followed approved schedule every 21 days starting at 8mg/kg loading followed by 6mg/kg q 3 wks in Cohort 2 and 3. After the MTD of entinostat in cohort 2 was determined at 12mg, an expansion cohort of 10 pts (cohort 3) was conducted.

Results: Median age was 52 (26-69 yrs). Median number of prior trastuzumab-based regimens was 2 (1-6), 8 pts had lapatinib containing treatment prior to the trial, including 5 pts who had clinical benefit. 16 had ER+ and 13 ER negative, and 9 had IBC. Clinical efficacy and toxicity of treatment is summarized in table 1. Out of 14 pts who had clinical benefit (CR, PR, SD), 6 had IBC. Three pts are still on therapy (1CR, 1PR, 1SD).

Table 1. Clinical Efficacy, Toxicity of combination Receptor StatusResponseGrade 3 toxicityGrade 4 toxicityCohort 1HER2+/ER- (N=8) HER2+/ER+ (N=7)CR (N=1; 8M), SD (N=4;1,2,4M)Lapatinib dose reduction: 3 pts Rash (2) Abdominal pain + dyspnea (1)Entinostat dose reduction: 2pts Neutropenia (1 at 12mg, 1 at 15mg)Cohort 2/3HER2+/ER- (N=8) HER2+/ER+ (N=6)CR (N=2; 3,6M), PR (N=2;4,5M) SD (N=5;1,2,4,6M)Lapatinib dose reduction: 2 pts Diarrhea (N=1 at 12mg N=1 at 10mg) Entinostat dose reduction: 5 pts Neutropenia (N=2 at 12 mg) Leukopenia (N=1 at 12mg) Anemia (N=1 at 12mg)Entinostat dose reduction: 2pts Hypokalemia (N=1 at 12mg) Thrombocytopenia (N=1 at 15mg)CR: complete response, PR: partial response, SD: stable disease, N=number of pts, M=months

Conclusion: MTD was reached at 12mg q 2wkly entinostat, lapatinib 1000 mg daily and trastuzumab 8 mg/kg followed by 6mg/kg q 3 wks. This combination was safe and had promising clinical efficacy in patients with trastuzumab-resistant metastatic HER2+ breast cancer including IBC, warranting further study.

Citation Format: Lim B, Jackson S, Alvarez RH, Ibrahim NK, Willey JS, Murthy RK, Booser DJ, Giordano SH, Barcenas CH, Brewster A, Walters RS, Brown PH, Tripathy D, Valero V, Ueno NT. A single-center, open-label phase 1b study of entinostat, and lapatinib alone, and in combination with and trastuzumab in patients with HER2+ metastatic breast cancer after progression on trastuzumab. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-14-22.

Nut crop yield records show that budbreak-based chilling requirements may not reflect yield decline chill thresholds

Warming winters due to climate change may critically affect temperate tree species. Insufficiently cold winters are thought to result in fewer viable flower buds and the subsequent development of fewer fruits or nuts, decreasing the yield of an orchard or fecundity of a species. The best existing approximation for a threshold of sufficient cold accumulation, the "chilling requirement" of a species or variety, has been quantified by manipulating or modeling the conditions that result in dormant bud breaking. However, the physiological processes that affect budbreak are not the same as those that determine yield. This study sought to test whether budbreak-based chilling thresholds can reasonably approximate the thresholds that affect yield, particularly regarding the potential impacts of climate change on temperate tree crop yields. County-wide yield records for almond (Prunus dulcis), pistachio (Pistacia vera), and walnut (Juglans regia) in the Central Valley of California were compared with 50 years of weather records. Bayesian nonparametric function estimation was used to model yield potentials at varying amounts of chill accumulation. In almonds, average yields occurred when chill accumulation was close to the budbreak-based chilling requirement. However, in the other two crops, pistachios and walnuts, the best previous estimate of the budbreak-based chilling requirements was 19-32 % higher than the chilling accumulations associated with average or above average yields. This research indicates that physiological processes beyond requirements for budbreak should be considered when estimating chill accumulation thresholds of yield decline and potential impacts of climate change.

Foliar application of microbial and plant based biostimulants increases growth and potassium uptake in almond (Prunus dulcis [Mill.] D. A. Webb)

The use of biostimulants has become a common practice in agriculture. However, there is little peer-reviewed research on this topic. In this study we tested, under controlled and replicated conditions, the effect of one biostimulant derived from seaweed extraction (Bio-1) and another biostimulant derived from microbial fermentation (Bio-2). This experiment utilized 2-years-old almond plants over two growing seasons in a randomized complete design with a full 2 × 4 factorial structure with two soil potassium treatments (125 μg g(-1) of K vs. 5 μg g(-1)) and four foliar treatments (No spray, Foliar-K, Bio-1, Bio-2). Rubidium was utilized as a surrogate for short-term potassium uptake and plant growth, nutrient concentration, and final plant biomass were evaluated. There was a substantial positive effect of both biostimulant treatments on total shoot leaf area, and significant increases in shoot length and biomass under adequate soil potassium supply with a positive effect of Bio-1 only under low K supply. Rubidium uptake was increased by Bio-1 application an effect that was greater under the low soil K treatment. Though significant beneficial effects of the biostimulants used on plant growth were observed, it is not possible to determine the mode of action of these materials. The results presented here illustrate the promise and complexity of research involving biostimulants.

Long-term effects of inhaled budesonide on screening-detected lung nodules

BACKGROUND

A previously carried out randomized phase IIb, placebo-controlled trial of 1 year of inhaled budesonide, which was nested in a lung cancer screening study, showed that non-solid and partially solid lung nodules detected by low-dose computed tomography (LDCT), and not immediately suspicious for lung cancer, tended to regress. Because some of these nodules may be slow-growing adenocarcinoma precursors, we evaluated long-term outcomes (after stopping the 1-year intervention) by annual LDCT.

PATIENTS AND METHODS

We analyzed the evolution of target and non-target trial nodules detected by LDCT in the budesonide and placebo arms up to 5 years after randomization. The numbers and characteristics of lung cancers diagnosed during follow-up were also analyzed.

RESULTS

The mean maximum diameter of non-solid nodules reduced significantly (from 5.03 mm at baseline to 2.61 mm after 5 years) in the budesonide arm; there was no significant size change in the placebo arm. The mean diameter of partially solid lesions also decreased significantly, but only by 0.69 mm. The size of solid nodules did not change. Neither the number of new lesions nor the number of lung cancers differed in the two arms.

CONCLUSIONS

Inhaled budesonide given for 1 year significantly decreased the size of non-solid nodules detected by screening LDCT after 5 years. This is of potential importance since some of these nodules may progress slowly to adenocarcinoma. However, further studies are required to assess clinical implications.

CLINICAL TRIAL NUMBER

NCT01540552.

Estimates of benefits and harms of prophylactic use of aspirin in the general population

BACKGROUND

Accumulating evidence supports an effect of aspirin in reducing overall cancer incidence and mortality in the general population. We reviewed current data and assessed the benefits and harms of prophylactic use of aspirin in the general population.

METHODS

The effect of aspirin for site-specific cancer incidence and mortality, cardiovascular events was collated from the most recent systematic reviews. Studies identified through systematic Medline search provided data regarding harmful effects of aspirin and baseline rates of harms like gastrointestinal bleeding and peptic ulcer.

RESULTS

The effects of aspirin on cancer are not apparent until at least 3 years after the start of use, and some benefits are sustained for several years after cessation in long-term users. No differences between low and standard doses of aspirin are observed, but there were no direct comparisons. Higher doses do not appear to confer additional benefit but increase toxicities. Excess bleeding is the most important harm associated with aspirin use, and its risk and fatality rate increases with age. For average-risk individuals aged 50-65 years taking aspirin for 10 years, there would be a relative reduction of between 7% (women) and 9% (men) in the number of cancer, myocardial infarction or stroke events over a 15-year period and an overall 4% relative reduction in all deaths over a 20-year period.

CONCLUSIONS

Prophylactic aspirin use for a minimum of 5 years at doses between 75 and 325 mg/day appears to have favourable benefit-harm profile; longer use is likely to have greater benefits. Further research is needed to determine the optimum dose and duration of use, to identify individuals at increased risk of bleeding, and to test effectiveness of Helicobacter pylori screening-eradication before starting aspirin prophylaxis.

Speciation and localization of Zn in the hyperaccumulator Sedum alfredii by extended X-ray absorption fine structure and micro-X-ray fluorescence

Differences in metal homeostasis among related plant species can give important information of metal hyperaccumulation mechanisms. Speciation and distribution of Zn were investigated in a hyperaccumulating population of Sedum alfredii by using extended X-ray absorption fine structure and micro-synchrotron X-ray fluorescence (μ-XRF), respectively. The hyperaccumulator uses complexation with oxygen donor ligands for Zn storage in leaves and stems, and variations in the Zn speciation was noted in different tissues. The dominant chemical form of Zn in leaves was most probably a complex with malate, the most prevalent organic acid in S. alfredii leaves. In stems, Zn was mainly associated with malate and cell walls, while Zn-citrate and Zn-cell wall complexes dominated in the roots. Two-dimensional μ-XRF images revealed age-dependent differences in Zn localization in S. alfredii stems and leaves. In old leaves of S. alfredii, Zn was high in the midrib, margin regions and the petiole, whereas distribution of Zn was essentially uniform in young leaves. Zinc was preferentially sequestered by cells near vascular bundles in young stems, but was highly localized to vascular bundles and the outer cortex layer of old stems. The results suggest that tissue- and age-dependent variations of Zn speciation and distribution occurred in the hyperaccumulator S. alfredii, with most of the Zn complexed with malate in the leaves, but a shift to cell wall- and citric acid-Zn complexes during transportation and storage in stems and roots. This implies that biotransformation in Zn complexation occurred during transportation and storage processes in the plants of S. alfredii.

Fruit presence negatively affects photosynthesis by reducing leaf nitrogen in almond

Fruit presence often positively and seldom negatively affects leaf carbon assimilation rate in fruit-trees. In almond (Prunus dulcis (Mill.) DA Webb) the presence of fruit often results in the death of the fruit bearing spurs. The mechanism of this effect is unclear, but may be a consequence of diminished carbon assimilation rate in leaves adjacent to fruit and the subsequent depletion of nutrient and carbohydrates reserves. This study evaluated the influence of fruit on leaf carbon assimilation rate and leaf nitrogen throughout the season. Carbon assimilation rate (Aa), rubisco carboxylation capacity at leaf temperature (Vcmax@Tleaf), maximum rate of RubP regeneration at leaf temperature (Jmax@Tleaf), leaf nitrogen on a mass basis (N%) and area basis (Na), and specific leaf weight data were recorded. Fruit presence negatively affected leaf nitrogen concentration by a reduction in specific leaf weight and leaf nitrogen content. The impact of fruit presence on carbon assimilation rate was predominantly associated with the negative effect of fruit on Na and resulted in a significant reduction in Jmax@Tleaf and therefore in Aa, especially after full leaf and fruit expansion. The reduction in leaf area, leaf nitrogen, reduced Jmax@Tleaf and decreased carbon assimilation rate in the presence of fruit explains the negative effects of fruit presence on spur vitality.

Spatial imaging of Zn and other elements in Huanglongbing-affected grapefruit by synchrotron-based micro X-ray fluorescence investigation

Huanglongbing (HLB) is a highly destructive, fast-spreading disease of citrus, causing substantial economic losses to the citrus industry worldwide. Nutrient levels and their cellular distribution patterns in stems and leaves of grapefruit were analysed after graft-inoculation with lemon scions containing 'Candidatus Liberibacter asiaticus' (Las), the heat-tolerant Asian type of the HLB bacterium. After 12 months, affected plants showed typical HLB symptoms and significantly reduced Zn concentrations in leaves. Micro-XRF imaging of Zn and other nutrients showed that preferential localization of Zn to phloem tissues was observed in the stems and leaves collected from healthy grapefruit plants, but was absent from HLB-affected samples. Quantitative analysis by using standard references revealed that Zn concentration in the phloem of veins in healthy leaves was more than 10 times higher than that in HLB-affected leaves. No significant variation was observed in the distribution patterns of other elements such as Ca in stems and leaves of grapefruit plants with or without graft-inoculation of infected lemon scions. These results suggest that reduced phloem transport of Zn is an important factor contributing to HLB-induced Zn deficiency in grapefruit. Our report provides the first in situ, cellular level visualization of elemental variations within the tissues of HLB-affected citrus.

Supplemental macronutrients and microbial fermentation products improve the uptake and transport of foliar applied zinc in sunflower (Helianthus annuus L.) plants. Studies utilizing micro X-ray florescence

Enhancing nutrient uptake and the subsequent elemental transport from the sites of application to sites of utilization is of great importance to the science and practical field application of foliar fertilizers. The aim of this study was to investigate the mobility of various foliar applied zinc (Zn) formulations in sunflower (Helianthus annuus L.) and to evaluate the effects of the addition of an organic biostimulant on phloem loading and elemental mobility. This was achieved by application of foliar formulations to the blade of sunflower (H. annuus L.) and high-resolution elemental imaging with micro X-ray fluorescence (μ-XRF) to visualize Zn within the vascular system of the leaf petiole. Although no significant increase of total Zn in petioles was determined by inductively-coupled plasma mass-spectrometer, μ-XRF elemental imaging showed a clear enrichment of Zn in the vascular tissues within the sunflower petioles treated with foliar fertilizers containing Zn. The concentration of Zn in the vascular of sunflower petioles was increased when Zn was applied with other microelements with EDTA (commercial product Kick-Off) as compared with an equimolar concentration of ZnSO4 alone. The addition of macronutrients N, P, K (commercial product CleanStart) to the Kick-Off Zn fertilizer, further increased vascular system Zn concentrations while the addition of the microbially derived organic biostimulant "GroZyme" resulted in a remarkable enhancement of Zn concentrations in the petiole vascular system. The study provides direct visualized evidence for phloem transport of foliar applied Zn out of sites of application in plants by using μ-XRF technique, and suggests that the formulation of the foliar applied Zn and the addition of the organic biostimulant GroZyme increases the mobility of Zn following its absorption by the leaf of sunflower.

Abstract OT3-3-01: A multicenter phase II study of docosahexaenoic acid (DHA) in triple negative breast cancer (TNBC) survivors

Background: The development of effective chemopreventive strategies to reduce the risk of TNBC, is a critical unmet need. Obesity is associated with a chronic inflammatory condition in the white adipose tissue of the breast, characterized microscopically by crown-like structures of the breast (CLS-B). The presence and extent of these lesions is associated with a series of proinflammatory mediators, including tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β) and aromatase. Importantly these proinflammatory mediators are known to be involved in breast carcinogenesis. In translational studies to date, the strongest correlations have been seen between CLS-B and TNF-α. Therefore, we aim to evaluate whether treatment with a dietary supplement, DHA, an omega-3 fatty acid, with potent effects on TNF-α, can decrease obesity-related breast inflammation in women.

Trial design: This is a randomized phase II placebo-controlled, double-blinded study of DHA in overweight/obese patients (pts), defined as body mass index (BMI) ≥25 with a history of TNBC. Pts will receive DHA or placebo twice daily for 24 weeks and will undergo core biopsies from normal (non-irradiated contralateral) breast tissue before and after the treatment to determine whether DHA can decrease obesity-related breast inflammation.

Eligibility: Inclusion criteria: 1) Age ≥ 18. 2) BMI ≥ 25. 3) Completed treatment for stage I-III TNBC ≥ 6 months prior. 4) No clinical evidence of disease. 5) Adequate accessible breast tissue for pre- and post- treatment biopsy, consisting of one breast unaffected by invasive cancer, which has not been radiated or surgically augmented. 6) Adequate organ and bone marrow function. 7) ECOG status ≤2. Exclusion criteria: 1) DHA supplementation. 2) Aspirin/NSAID use in the month preceding and during the trial. 3) Therapeutic anticoagulation. 4) Regular use of statins, steroids, or immunomodulators.

Specific aims: The primary objective is to determine whether treatment with DHA for 24 weeks at 1,000 mg twice daily as compared to placebo reduces normal breast tissue levels of TNF-α in overweight/obese pts with a history of TNBC. The secondary objective is to evaluate the effect of DHA on the change from baseline in levels of the following tissue biomarkers: COX-2, IL-1β, aromatase, and CLS-B. Exploratory endpoints include assessment of age as a predictor of CLS-B and inflammatory biomarkers and the evaluation of red blood cell fatty acid levels as a surrogate of DHA compliance.

Statistical methods: Percent change in TNF-α mRNA levels in normal breast tissue between DHA and placebo arm will be compared using two-sample t-test. If normality assumptions are violated, a two-sample Wilcoxon rank-sum test will be used. With 30 subjects in each arm, we will have 80% power to detect effect size as small as 0.74 at 0.05 significance level using a two-sided, two-sample, Student t-test.

Accrual: A total of 60 evaluable pts will be enrolled. Assuming a 10% dropout rate and 10% non-evaluable rate, up to 76 participants will be randomized in this study. This trial is currently enrolling pts.

Contact information: For more information on this trial, please visit clinicaltrials.gov (NCT01849250) or contact Ayca Gucalp MD (gucalpa@mskcc.org).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT3-3-01.

Abstract P4-06-01: Expression and DNA copy number profiling suggest novel therapeutic approaches for triple negative breast cancer subtypes

The aggressive triple negative breast cancers (TNBCs), which lack ER, PR and HER2, comprise a high-risk subset of human breast cancers which remain poorly characterized and lack effective treatments. While recent meta-analyses indicate the complexity of these tumors, no robust independently validated phenotypes have been defined. We have identified four distinct molecular subtypes through independent non-negative matrix factorization of expression data from 84 Discovery and 114 Validation Set TNBCs profiled at a single institution, with matching CNV data (SNP array). We then classified 485 publically available TNBCs via a centroid signature of only 80 genes. All three sets supported stratification of tumors by cell cycle, DNA repair, and immunological signaling pathways that have significantly different clinical outcomes. The first subtype, composed of intermediate grade tumors, resembles the “Molecular Apocrine” or “Luminal AR” subtype described previously and was defined by enrichment of prolactin, aryl hydrocarbon receptor, and ERBB4 signaling with activated downstream expression patterns of ESR1 signaling. Large deletions of chromosome 6 were specific to this subtype. While focal deletions at 14q21.2 and 12q13.13 were present in &gt;60% of tumors of the other subtypes, the genes at these loci (FOXA1 and ERBB3) were overexpressed in the first subtype. Inhibitors of AR and MUC1, both overexpressed, may prove effective for these tumors. A second subtype defined as “Claudin-Low” or “Mesenchymal Stem-Like” showed overexpression of markers of mesenchymal lineage (ADIPOQ and OGN). Targets responsive to beta-blockers (ADRB2), and targetable molecules associated with platelet and endothelial function (EDNRB, PLA2G2A, PTGER3/4, PTGFR, PTGFRA) were also upregulated. Two basal-like subtypes were found with significant differences in DFS and OS, even after correction for available clinical covariates. The high-risk (31% 5-year DFS), low immune function subtype was regulated by SOX 10, 8, and 6 and had unique copy-number driven expression of FGFR2. The second, low-risk (78% 5-year DFS) basal-like subtype was enriched for overexpression of many immune pathways, regulated by increased STAT1 and activated STAT downstream signaling, as well as exclusive upregulation of CTLA4. This subtype also had the lowest tumor cell fraction as calculated by allele specific copy number analysis of tumors (ASCAT). Both basal-like subtypes expressed TTK, CHEK1, TOP2A, and AURKA. CDK1 was correlated with copy number variation at 10q21.1. We proposed and validated four molecular subtypes of TNBC before applying the resulting gene signature to 7 external expression sets. The described subtypes vary by clinical behavior and inferred biology. Each subtype appears to have specific gene expression regulated by copy number variation and a set of genes targetable by currently available agents. These findings further define the heterogeneity of TNBCs and suggest potential therapeutic targets for each subtype.

This work was supported by a Promise grant from the Susan G. Komen for the Cure Foundation (KG081694).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-06-01.

Abstract OT3-3-02: Phase IIB randomized double-blind placebo-controlled biomarker modulation study of high dose vitamin D in premenopausal women at high-risk for breast cancer: SWOG S0812

Background: Priorities in breast cancer chemoprevention include developing agents effective against estrogen receptor (ER)-negative breast cancer and validating intermediate biomarkers which correlate with breast cancer risk. Vitamin D is a fat-soluble vitamin which regulates calcium and bone homeostasis, but also has diverse biological effects relevant to breast carcinogenesis. The biologically active form of vitamin D [1,25(OH)D] interacts with the vitamin D receptor (VDR) to modulate cell proliferation, differentiation, apoptosis, and angiogenesis. Epidemiologic data suggests that serum 25(OH)D levels &gt;40-50 ng/ml are associated with a 40-50% reduction in breast cancer risk compared to women with vitamin D deficiency (&lt;20 ng/ml). Given the high prevalence of vitamin D deficiency in the general population, vitamin D3 3000-4000 IU daily would be required to raise 25(OH)D to this putative target level. The central hypothesis of this proposal is that high-dose vitamin D will modulate biomarkers of breast cancer risk.

Trial Design: This trial is a phase IIB, randomized, double-blind, placebo-controlled study of oral vitamin D3 (cholecalciferol) 20,000 IU (2 capsules) weekly for one year in 200 premenopausal women at high-risk for breast cancer. Both groups will be supplemented with a standard dose of vitamin D3 600 IU daily. Participants will undergo a mammogram and optional random core breast biopsy timed within 10 days after the start of their menstrual cycle at baseline and 1 year and blood collections at baseline, 6, and 12 months. Participants will be monitored for toxicity, particularly hypercalcemia and hypercalciuria, every 3 months during the 1-year intervention.

Main Eligibility Criteria: High-risk is defined as a 5-year Gail risk score ≥1.67% or lifetime risk ≥20%, history of atypical hyperplasia, lobular or ductal carcinoma in situ, germline mutations in BRCA1, BRCA2, p53, or PTEN, history of stage I-II breast cancer in remission for &gt;5 years, or baseline mammographic density &gt;50%. Other eligibility criteria include baseline serum 25(OH)D ≤32 ng/ml, normal serum calcium and urine calcium/creatinine ratio, and no history of kidney stones.

Specific Aims: The primary endpoint is change in mammographic density at 12 months compared to baseline between the vitamin D and placebo groups. Secondary exploratory endpoints include breast tissue-based biomarkers (Ki-67, cleaved caspase-3, ER, VDR, and 1α-hydroxylase) and blood-based biomarkers (25(OH)D, 1,25(OH)D, PTH, IGF-1, IGFBP-3, VDR polymorphisms).

Statistical Methods: Power calculations are based on a two-sample comparison of normal deviates, using a 2-sided, 0.05-level test. To be conservative, we assume that 15% will have missing breast density data at 12 months and a 2% difference in mammographic density between intervention and control at 12 months with a the standard deviation for each arm of 4%. With 200 women randomized, the study will have 90% power to detect this difference.

Target Accrual: 200. Sixty-seven patients accrued as of June 2013. Accrual completion expected December 2014.

Contact: Katherine Crew, Columbia University Medical Center, kd59@columbia.edu.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT3-3-02.

From plant surface to plant metabolism: the uncertain fate of foliar-applied nutrients

The application of agrochemical sprays to the aerial parts of crop plants is an important agricultural practice world-wide. While variable effectiveness is often seen in response to foliar treatments, there is abundant evidence showing the beneficial effect of foliar fertilizers in terms of improving the metabolism, quality, and yields of crops. This mini-review is focused on the major bottlenecks associated with the uptake and translocation of foliar-applied nutrient solutions. A better understanding of the complex scenario surrounding the ultimate delivery of foliar-applied nutrients to sink cells and organs is essential for improving the effectiveness and performance of foliar fertilizers.

Efficient xylem transport and phloem remobilization of Zn in the hyperaccumulator plant species Sedum alfredii

Sedum alfredii is one of a few species known to hyperaccumulate zinc (Zn) and cadmium (Cd). Xylem transport and phloem remobilization of Zn in hyperaccumulating (HP) and nonhyperaccumulating (NHP) populations of S. alfredii were compared. Micro-X-ray fluorescence (μ-XRF) images of Zn in the roots of the two S. alfredii populations suggested an efficient xylem loading of Zn in HP S. alfredii, confirmed by the seven-fold higher Zn concentrations detected in the xylem sap collected from HP, when compared with NHP, populations. Zn was predominantly transported as aqueous Zn (> 55.9%), with the remaining proportion (36.7-42.3%) associated with the predominant organic acid, citric acid, in the xylem sap of HP S. alfredii. The stable isotope (68)Zn was used to trace Zn remobilization from mature leaves to new growing leaves for both populations. Remobilization of (68)Zn was seven-fold higher in HP than in NHP S. alfredii. Subsequent analysis by μ-XRF, combined with LA-ICPMS (laser ablation-inductively coupled plasma mass spectrometry), confirmed the enhanced ability of HP S. alfredii to remobilize Zn and to preferentially distribute the metal to mesophyll cells surrounding phloem in the new leaves. The results suggest that Zn hyperaccumulation by HP S. alfredii is largely associated with enhanced xylem transport and phloem remobilization of the metal. To our knowledge, this report is the first to reveal enhanced remobilization of metal by phloem transport in hyperaccumulators.

Detecting nonlinear response of spring phenology to climate change by Bayesian analysis

The impact of climate change on the advancement of plant phenological events has been heavily studied in the last decade. Although the majority of spring plant phenological events have been trending earlier, this is not universally true. Recent work has suggested that species that are not advancing in their spring phenological behavior are responding more to lack of winter chill than increased spring heat. One way to test this hypothesis is by evaluating the behavior of a species known to have a moderate to high chilling requirement and examining how it is responding to increased warming. This study used a 60-year data set for timing of leaf-out and male flowering of walnut (Juglans regia) cultivar 'Payne' to examine this issue. The spring phenological behavior of 'Payne' walnut differed depending on bud type. The vegetative buds, which have a higher chilling requirement, trended toward earlier leaf-out until about 1994, when they shifted to later leaf-out. The date of male bud pollen shedding advanced over the course of the whole record. Our findings suggest that many species which have exhibited earlier bud break are responding to warmer spring temperatures, but may shift into responding more to winter temperatures (lack of adequate chilling) as warming continues.

Synthesis, characterization, and direct intracellular imaging of ultrasmall and uniform glutathione-coated gold nanoparticles

Gold nanoparticles (AuNPs) with core sizes below 2 nm and compact ligand shells constitute versatile platforms for the development of novel reagents in nanomedicine. Due to their ultrasmall size, these AuNPs are especially attractive in applications requiring delivery to crowded intracellular spaces in the cytosol and nucleus. For eventual use in vivo, ultrasmall AuNPs should ideally be monodisperse, since small variations in size may affect how they interact with cells and how they behave in the body. Here we report the synthesis of ultrasmall, uniform 144-atom AuNPs protected by p-mercaptobenzoic acid followed by ligand exchange with glutathione (GSH). Quantitative scanning transmission electron microscopy (STEM) reveals that the resulting GSH-coated nanoparticles (Au(GSH)) have a uniform mass distribution with cores that contain 134 gold atoms on average. Particle size dispersity is analyzed by analytical ultracentrifugation, giving a narrow distribution of apparent hydrodynamic diameter of 4.0 ± 0.6 nm. To evaluate the nanoparticles' intracellular fate, the cell-penetrating peptide TAT is attached noncovalently to Au(GSH), which is confirmed by fluorescence quenching and isothermal titration calorimetry. HeLa cells are then incubated with both Au(GSH) and the Au(GSH)-TAT complex, and imaged without silver enhancement of the AuNPs in unstained thin sections by STEM. This imaging approach enables unbiased detection and quantification of individual ultrasmall nanoparticles and aggregates in the cytoplasm and nucleus of the cells.

Analysis of high-affinity assembly for AMPA receptor amino-terminal domains

Analytical ultracentrifugation (AUC) and steady-state fluorescence anisotropy were used to measure the equilibrium dissociation constant (Kd) for formation of dimers by the amino-terminal domains (ATDs) of the GluA2 and GluA3 subtypes of AMPA receptor. Previous reports on GluA2 dimerization differed in their estimate of the monomer-dimer Kd by a 2,400-fold range, with no consensus on whether the ATD forms tetramers in solution. We find by sedimentation velocity (SV) analysis performed using absorbance detection a narrow range of monomer-dimer Kd values for GluA2, from 5 to 11 nM for six independent experiments, with no detectable formation of tetramers and no effect of glycosylation or the polypeptide linker connecting the ATD and ligand-binding domains; for GluA3, the monomer-dimer Kd was 5.6 µM, again with no detectable tetramer formation. For sedimentation equilibrium (SE) experiments, a wide range of Kd values was obtained for GluA2, from 13 to 284 nM, whereas for GluA3, the Kd of 3.1 µM was less than twofold different from the SV value. Analysis of cell contents after the ∼1-week centrifuge run by silver-stained gels revealed low molecular weight GluA2 breakdown products. Simulated data for SE runs demonstrate that the apparent Kd for GluA2 varies with the extent of proteolysis, leading to artificially high Kd values. SV experiments with fluorescence detection for GluA2 labeled with 5,6-carboxyfluorescein, and fluorescence anisotropy measurements for GluA2 labeled with DyLight405, yielded Kd values of 5 and 11 nM, consistent with those from SV with absorbance detection. However, the sedimentation coefficients measured by AUC using absorbance and fluorescence systems were strikingly different, and for the latter are not consistent with hydrodynamic protein models. Thus, for unknown reasons, the concentration dependence of sedimentation coefficients obtained with fluorescence detection SV may be unreliable, limiting the usefulness of this technique for quantitative analysis.

A SNP in steroid receptor coactivator-1 disrupts a GSK3β phosphorylation site and is associated with altered tamoxifen response in bone

The coregulator steroid receptor coactivator (SRC)-1 increases transcriptional activity of the estrogen receptor (ER) in a number of tissues including bone. Mice deficient in SRC-1 are osteopenic and display skeletal resistance to estrogen treatment. SRC-1 is also known to modulate effects of selective ER modulators like tamoxifen. We hypothesized that single nucleotide polymorphisms (SNP) in SRC-1 may impact estrogen and/or tamoxifen action. Because the only nonsynonymous SNP in SRC-1 (rs1804645; P1272S) is located in an activation domain, it was examined for effects on estrogen and tamoxifen action. SRC-1 P1272S showed a decreased ability to coactivate ER compared with wild-type SRC-1 in multiple cell lines. Paradoxically, SRC-1 P1272S had an increased protein half-life. The Pro to Ser change disrupts a putative glycogen synthase 3 (GSK3)β phosphorylation site that was confirmed by in vitro kinase assays. Finally, knockdown of GSK3β increased SRC-1 protein levels, mimicking the loss of phosphorylation at P1272S. These findings are similar to the GSK3β-mediated phospho-ubiquitin clock previously described for the related coregulator SRC-3. To assess the potential clinical significance of this SNP, we examined whether there was an association between SRC-1 P1272S and selective ER modulators response in bone. SRC-1 P1272S was associated with a decrease in hip and lumbar bone mineral density in women receiving tamoxifen treatment, supporting our in vitro findings for decreased ER coactivation. In summary, we have identified a functional genetic variant of SRC-1 with decreased activity, resulting, at least in part, from the loss of a GSK3β phosphorylation site, which was also associated with decreased bone mineral density in tamoxifen-treated women.

P3-14-09: A Phase II Preoperative Study of Dasatinib, a Multi-Targeted Tyrosine Kinase Inhibitor, in Locally Advanced “Triple-Negative” Breast Cancer Patients

Background: We previously reported that kinases (Src, Yes-1, cKIT, Abl, and EPH4) were druggable in triple negative breast cancer (TNBC). In this clinical trial, we sought to translate these findings by treating TNBC patients with dasatinib, a multi-targeted kinase inhibitor against these targets.

Methods: Women with stage II-III TNBC were eligible. Patients received dasatinib at 100 mg daily for 3 to 4 weeks before standard-of-care definitive surgery and chemotherapy. Biopsies were performed at baseline, week 1, and at the time of surgery. A cohort of patients had positron emission mammography (PEM; baseline and at 2–3 weeks of dasatinib therapy). This study was designed to detect an increase in clinical response rate from 10% to 25%, using a Simon optimal two stage design, with one-sided alpha=5% and power=80%. At least 3 responses out of 22 patients were needed to proceed to the second stage.

Results: 22 patients were enrolled (Table 1). Median tumor size was 7.0 cm (range 2.4-25 cm). Adverse events were modest, mainly grade 1–2 (headache: 45%, abnormal LFTs: 55%, GI: 23%, fatigue: 18%). One patient had a myocardial infarction 24 hours after starting dasatinib. Out of 22 patients, 2 (9%) had a clinical partial response after 3–4 weeks of therapy, 15 had stable disease (68%), while 5 had progressive disease (23%). Of the 8 patients who received paired PEM imaging, metabolic responses were observed in 2 patients (25%). Conclusion: A short course of dasatinib led to clinical responses in 2 out of 22 patients with TNBC, and the study did not proceed to second stage. Since TNBC is a heterogeneous disease, biomarker studies including sequencing of candidate genes like B-RAF for inactivating mutations might enable selection of those TNBC patients who could benefit from dasatinib.

PD03-03: Identification of Transcription Factors Critical for the Growth of Basal Breast Cancer

Background: Basal breast cancers are aggressive, poor prognosis tumors that occur commonly in young women and in African American women. Profiling of breast tumor mRNA has demonstrated that there are differences in gene expression between the basal and luminal subtypes of breast cancer. In this study, we identified response elements in the genes that define basal breast cancers, and identified transcription factors that are critical for the growth of basal breast cancer cells.

Materials and Methods: We performed promoter analysis using 4 published microarray studies (PMID: 12829800; PMID: 19435916; PMID: 17157792; PMID: 11562467) to select genes that are highly expressed in basal tumors compared to luminal tumors. For this analysis we selected 61 genes highly expressed in a set of basal tumors in any of the 4 microarray studies. We next used the online tool, CORE_TF, along with the MATCH algorithm minimizing for the sum of false positives and false negatives to identify binding motifs within the promoter (defined from −1 kb to the first exon) of each gene. The frequency of binding motif occurrence for these 61 basal genes was compared to the frequency within the promoters of 3000 randomly selected genes. Significance was tested using an exact binomial test with a cutoff of p&lt;0.05. RNA expression of motif-identified transcription factors was then analyzed in-silico using all 10 datasets in Oncomine™ that contained annotation for triple-negative status. Expression in triple negative samples was compared to expression in non-triple-negative samples with a cutoff of p &lt;0.05. We next performed siRNA knockdown studies to determine whether the identified TFs regulate basal breast cancer growth. Basal and luminal cells transfected with control and specific siRNAs were grown in triplicate and mean cell counts at day 6 were compared.

Results: Promoter analysis identified 24 binding motifs that were over-represented in basal breast tumor genes compared to a random set of 3000 genes. TransFac analysis indicated that 47 transcription factors bind the 24 identified motifs. Oncomine analysis showed that 8 of the 47 transcription factors were significantly more highly expressed in basal as compared to non-basal tumors. Identified transcription factors include FOXC1, FOXM1, CDC5L, E2F3, CEBP and NF-Y. siRNA to FOXM1 in 2 basal breast cell lines reduced growth by &gt;70% after 6 days, whereas, in the luminal cell line MCF7, growth was reduced by 15%.

Discussion: This study identified transcription factors that are highly expressed in basal breast tumors (as compared to non-basal breast tumors). siRNA knockdown studies showed that FOXM1 is critical for basal breast cancer cell growth. These results suggest that transcription factors highly expressed in basal breast cancers may be novel targets for the treatment of this disease.

These studies were supported by a Promise grant from the Susan G. Komen for the Cure (PB, SGH), and by the Norman E. Brinker Award for Research Excellence (PB).

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD03-03.

P4-01-18: AP-1 Blockade Potentiates the Anti-Tumor Effect of Endocrine Treatment and Reverts the Resistant Phenotype in Hormone Receptor-Positive Breast Cancer

Background: Resistance to endocrine therapy is a major clinical issue. The transcription factor AP-1 is a key regulator of cell growth and survival as well as a downstream signaling component of several pathways deregulated in endocrine-resistant breast cancer. We have previously shown that acquired endocrine resistance is associated with increased AP-1 activity. AP-1 has also been shown to interact with and modulate the ER network and transcriptional program, especially under hyperactive growth factor signaling, which is commonly associated with endocrine resistance. We hypothesized that interfering with AP-1 function would circumvent endocrine resistance possibly due to its role in modulating ER transcriptional activity.

Methods and results: We inhibited AP-1 function by a genetic approach. We used two different MCF7 clones stably transfected with a Doxycycline (Dox)-inducible dominant-negative (DN) c-Jun (MCF7/Tet-Off Tam67 clones 62 and 67) and two vector-alone control MCF7 clones. Xenografts of these clones were established in ovariectomized nude mice supplemented with estrogen (E2). Mice were then randomized to continued E2 supplementation (control) or to endocrine therapy with either estrogen deprivation (ED) or tamoxifen (Tam), all in the presence or absence of Dox to induce the DN c-Jun expression. AP-1 blockade in both MCF7/Tet-Off Tam67 clones significantly enhanced sensitivity to Tam by reducing time to tumor size halving (p=.014 and p=.006 for clone 62 and 67, respectively) and time to complete tumor disappearance (p=.001 and p=.0034 for clone 62 and 67, respectively). Similar results were obtained with ED treatment. In addition, AP-1 blockade significantly delayed the onset of Tam resistance by increasing time to tumor size doubling (p=.0028). Furthermore, induction of DN c-Jun resulted in a dramatic shrinkage of growing tumors after long-term Tam treatment, suggesting reversal of endocrine resistance with AP-1 blockade. None of the above effects was observed in control clones upon Dox removal. Interestingly, no significant effect of AP-1 blockade was observed on E2-stimulated tumor growth. IHC analysis showed that AP-1 blockade induced tumor response by reducing proliferation (i.e., decreased % of Ki67- and phospho-Histone 3-positive cells) and by inducing apoptosis (i.e., increased % of cleaved caspase 3/7-positive cells). Bioinformatic analyses were conducted to intersect our MCF7 xenograft/Tam-resistant gene signature and the datasets of genes associated with ER DNA-binding sites obtained by whole-genome ER cistromic analysis under estrogen or epidermal growth factor (EGF) stimulation of MCF7 cells. A significant enrichment of the genes associated with the EGF-unique ER DNA-binding sites was observed within our Tam-resistant signature (p&lt;2E-16). Remarkably, 90% of these DNA binding sites harbored an AP-1 motif.

Conclusions: We show that AP-1 blockade increases tumor sensitivity and circumvents resistance to endocrine therapy, thus warranting the development of AP-1-targeted therapy to improve endocrine treatment outcomes. Overall, we suggest that AP-1 is critical in induction of a switch in the ER transcriptional program and may be a new hallmark of endocrine resistance.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-01-18.

Density contrast sedimentation velocity for the determination of protein partial-specific volumes

The partial-specific volume of proteins is an important thermodynamic parameter required for the interpretation of data in several biophysical disciplines. Building on recent advances in the use of density variation sedimentation velocity analytical ultracentrifugation for the determination of macromolecular partial-specific volumes, we have explored a direct global modeling approach describing the sedimentation boundaries in different solvents with a joint differential sedimentation coefficient distribution. This takes full advantage of the influence of different macromolecular buoyancy on both the spread and the velocity of the sedimentation boundary. It should lend itself well to the study of interacting macromolecules and/or heterogeneous samples in microgram quantities. Model applications to three protein samples studied in either H(2)O, or isotopically enriched H(2) (18)O mixtures, indicate that partial-specific volumes can be determined with a statistical precision of better than 0.5%, provided signal/noise ratios of 50-100 can be achieved in the measurement of the macromolecular sedimentation velocity profiles. The approach is implemented in the global modeling software SEDPHAT.

The molecular refractive function of lens γ-Crystallins

γ-Crystallins constitute the major protein component in the nucleus of the vertebrate eye lens. Present at very high concentrations, they exhibit extreme solubility and thermodynamic stability to prevent scattering of light and formation of cataracts. However, functions beyond this structural role have remained mostly unclear. Here, we calculate molecular refractive index increments of crystallins. We show that all lens γ-crystallins have evolved a significantly elevated molecular refractive index increment, which is far above those of most proteins, including nonlens members of the βγ-crystallin family from different species. The same trait has evolved in parallel in crystallins of different phyla, including S-crystallins of cephalopods. A high refractive index increment can lower the crystallin concentration required to achieve a suitable refractive power of the lens and thereby reduce their propensity to aggregate and form cataracts. To produce a significant increase in the refractive index increment, a substantial global shift in amino acid composition is required, which can naturally explain the highly unusual amino acid composition of γ-crystallins and their functional homologues. This function provides a new perspective for interpreting their molecular structure.

On the distribution of protein refractive index increments

The protein refractive index increment, dn/dc, is an important parameter underlying the concentration determination and the biophysical characterization of proteins and protein complexes in many techniques. In this study, we examine the widely used assumption that most proteins have dn/dc values in a very narrow range, and reappraise the prediction of dn/dc of unmodified proteins based on their amino acid composition. Applying this approach in large scale to the entire set of known and predicted human proteins, we obtain, for the first time, to our knowledge, an estimate of the full distribution of protein dn/dc values. The distribution is close to Gaussian with a mean of 0.190 ml/g (for unmodified proteins at 589 nm) and a standard deviation of 0.003 ml/g. However, small proteins <10 kDa exhibit a larger spread, and almost 3000 proteins have values deviating by more than two standard deviations from the mean. Due to the widespread availability of protein sequences and the potential for outliers, the compositional prediction should be convenient and provide greater accuracy than an average consensus value for all proteins. We discuss how this approach should be particularly valuable for certain protein classes where a high dn/dc is coincidental to structural features, or may be functionally relevant such as in proteins of the eye.