Resveratrol Analogs: Potential Chemopreventive Agents in Breast Cancer

Title from PDF of title page, viewed on June 3, 2015Dissertation advisor: Hari K. BhatVitaIncludes bibliographic references (pages 157-187)Thesis (Ph.D.)--School of Pharmacy and School of Biological Sciences. University of Missouri--Kansas City, 2014Epidemiological data and studies in rodent models strongly support the role of estrogens in the development of breast cancers. Estrogens have been added to the list of known human carcinogens. Exact mechanisms underlying the initiation and progression of estrogen-related cancers are not clear. Literature evidence and our studies strongly support the role of estrogen metabolism mediated oxidative stress in estrogen-induced breast carcinogenesis. It was recently demonstrated from our laboratory that antioxidants vitamin C or butylated hydroxyanisole (BHA) strongly inhibit 17β-estradiol (E2)-induced breast tumor development in female ACI rats. The objective of present study was to characterize the role of CNC b-zip transcription factors in antioxidant-mediated prevention of breast cancer. The present study was based on the central hypothesis that 17β-estradiol mediates carcinogenic insult in the cellular environment by producing reactive oxygen species (ROS) / oxidative stress during its metabolism to quinones. This oxidative stress can be controlled by production of phase-II detoxifying antioxidant enzymes. In order to test this hypothesis we examined the cellular levels of different antioxidant enzymes after treatment with E2. We then investigated the molecular mechanism(s) and pathways iv involved in E2-induced breast carcinogenesis. To address the question if antioxidant agents can reverse E2-induced oxidative stress and ultimately mediate chemoprevention of breast cancer, we checked several different cellular antioxidant enzymes’ levels and dissected out possible molecular pathways involved after treatment with naturally occurring well studied antioxidants like resveratrol (Res), resveratrol analogs (TIMBD and HPIMBD) and Vitamin C. Resveratrol has been shown to reduce primary tumor growth of xenografts in a nude mouse model. But its clinical applications in prevention of breast cancer are limited because of its lower efficacy in in vivo systems. Thus, to improve the anticancer and antioxidant efficacy of Res and to use it as a successful agent targeting breast cancer, pharmacologically active resveratrol analogs have been synthesized. Our newly synthesized Res-analog compounds: 4-(E)-{(p-tolylimino)-methylbenzene-1,2-diol} (TIMBD) and 4-(E)-{(4-hydroxyphenylimino)-methylbenzene, 1, 2-diol} (HPIMBD), have effectively inhibited the growth of breast cancer cells and have no/minimal cytotoxicity towards normal cells. To further delineate the mechanisms responsible for higher growth inhibitory potency of TIMBD and HPIMBD, we have aimed at finding out its antioxidant potentials. In this current work we have shown the contribution of TIMBD and HPIMBD in providing antioxidant defense in human breast epithelial cells. In our previous studies we have shown that estrogen-induced breast carcinogenesis is initiated by down-regulation of expression of the antioxidant enzymes, superoxide dismutase 3 (SOD3, also known as extracellular superoxide dismutase) and NAD(P)H:Quinone Oxidoreductase 1 (NQO1), via a nuclear factor erythroid 2-related factor 2 (Nrf2)- dependent signaling pathway. In this present study, we have shown that a new and potent resveratrol analogs TIMBD and HPIMBD, synthesized by our collaborating team functions to inhibit E2-dependent breast cancer development by up-regulation of the expression of SOD3 and NQO1 via this same Nrf2-dependent pathway. We have also provided evidence how TIMBD and HPIMBD mediate antioxidant defense through regulation of CNC-bzip transcription factors other than Nrf2; nuclear factor erythroid 2- related factor 1 (Nrf1) and nuclear factor erythroid 2-related factor 3 (Nrf3). We also investigated the potential roles of Res-analogs in prevention of epithelialmesenchymal transition (EMT). An epithelial-mesenchymal transition can be defined as a biological process which mediates a phenotypical change in the polarized epithelial cells to mesenchymal cells. Epithelial cells, which interact with basement membrane, undergo different complex biochemical and molecular changes to become mesenchymal cells. The process of EMT increases a cell’s migratory and invasive properties. It is well documented that the process of EMT plays a very critical role in cancer metastasis. The effects of Res-analogs on EMT and the migration of human breast cancer cell lines were studied. We found that Res-analogs significantly increased epithelial marker E-cadherin expression and down-regulated matrix metalloproteases (MMPs) and expression of mesenchymal markers, such as snail, slug, zeb1/2. In present studies, we have demonstrated the potential of Res-analogs in prevention of EMT these studies suggest that our novel Res-analogs may have the potential to be therapeutic agents for breast cancer chemoprevention. In order to dissect out the possible molecular mechanism of Res-analogs on the suppression of EMT and breast cancer cell metastasis, we found a critical involvement of β-catenin. The expression and nuclear translocation of β-catenin was significantly down-regulated with Res-analogs implicating that these analogs may prevent breast cancer cell metastasis involving β-catenin pathway. We have also tested the ability of these Res-analogs to inhibit the proliferation of 5 breast cancer cell lines and 3 non-neoplastic breast epithelial cell lines and compared their inhibition potential with Res. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cell proliferation was carried out in human breast cancer and non-neoplastic breast epithelial cell lines. The breast cancer cell lines tested were MCF-7, T47D, MDA-MB-231, MDA-MB-468 and BT-20. The non-neoplastic breast cell lines tested were MCF-10A, MCF-10F and HMEC. Of all the analogs tested, two analogs, 4- hydroxyphenyl-immino-methylbenzene-1,2-diol (HPIMBD) and TIMBD showed higher potency for inhibiting the proliferation of breast cancer cells compared to Res. Furthermore, TIMBD or HPIMBD showed higher potency for inhibiting the growth of triple negative breast cancer cells (MDA-MB-231, MDA-MB-468 and BT-20) compared to estrogen receptor positive breast cancer cells MCF-7 and T47D. There was neither inhibition nor proliferation by TIMBD or HPIMBD of non-neoplastic breast epithelial celllines. TIMBD and HPIMBD induced Beclin-1 and LC3-II which suggest autophagy mediated inhibition of cell growth. Beclin-1 is known to be suppressed in breast cancers and it’s over expression is reported to inhibit breast cancer. Results from our studies demonstrate that Res-analogs TIMBD and HPIMBD are better than Res in inhibiting specifically breast cancer cell growth and shows higher potency for inhibiting the growth of triple negative breast cancer cells by inducing autophagy with an earlier onset for triple negative breast cancer cells. Therefore, TIMBD and HPIMBD may be better chemotherapeutic agents than Res against breast cancer and more specifically against triple negative breast cancer cell growth, a cancer type prevalent in minority African American population with poor prognosis.General introduction -- General materials and methods -- Identification and characterization of resveratrol analogs in inhibiting breast cancer cell growth and possible mechanism of action of chemoprevention -- Determination of the mechanism of inhibition of E2-induced breast cancer by res-analogs through regulation of cnc-b zip transcription factors (NRFS) -- Determination of the role of res-analogs in epithelial mesenchymal transition (EMT) -- Novel res-analogs: TIMBD and HPIMBD demonstrate cytotoxicity towards breast cancer cells by a mechanism involving an early onset autophagy -- Appendi

Implication of Urban Agriculture and Vertical Farming for Future Sustainability

Urban agriculture (UA) is defined as the production of agricultural goods (crop) and livestock goods within urban areas like cities and towns. In the modern days, the urbanization process has raised a question on the sustainable development and growing of urban population. UA has been claimed to contribute to urban waste recycling, efficient water use and energy conservation, reduction in air pollution and soil erosion, urban beautification, climate change adaptation and resilience, disaster prevention, and ecological and social urban sustainability. Therefore, UA contributes to the sustainability of cities in various ways—socially, economically, and environmentally. An urban farming technology that involves the large-scale agricultural production in the urban surroundings is the vertical farming (VF) or high-rise farming technology. It enables fast growth and production of the crops by maintaining the environmental conditions and nutrient solutions to crop based on hydroponics technology. Vertical farms are able to grow food year-round because they maintain consistent growing conditions regardless of the weather outside and are much less vulnerable to climate changes. This promises a steady flow of products for the consumers and a consistent income for growers. Various advantages of VF over traditional farming, such as reduced farm inputs and crop failures and restored farmland, have enabled scientists to implement VF on a large scale

Nature-inspired Enzyme engineering and sustainable catalysis: biochemical clues from the world of plants and extremophiles

The use of enzymes to accelerate chemical reactions for the synthesis of industrially important products is rapidly gaining popularity. Biocatalysis is an environment-friendly approach as it not only uses non-toxic, biodegradable, and renewable raw materials but also helps to reduce waste generation. In this context, enzymes from organisms living in extreme conditions (extremozymes) have been studied extensively and used in industries (food and pharmaceutical), agriculture, and molecular biology, as they are adapted to catalyze reactions withstanding harsh environmental conditions. Enzyme engineering plays a key role in integrating the structure-function insights from reference enzymes and their utilization for developing improvised catalysts. It helps to transform the enzymes to enhance their activity, stability, substrates-specificity, and substrate-versatility by suitably modifying enzyme structure, thereby creating new variants of the enzyme with improved physical and chemical properties. Here, we have illustrated the relatively less-tapped potentials of plant enzymes in general and their sub-class of extremozymes for industrial applications. Plants are exposed to a wide range of abiotic and biotic stresses due to their sessile nature, for which they have developed various mechanisms, including the production of stress-response enzymes. While extremozymes from microorganisms have been extensively studied, there are clear indications that plants and algae also produce extremophilic enzymes as their survival strategy, which may find industrial applications. Typical plant enzymes, such as ascorbate peroxidase, papain, carbonic anhydrase, glycoside hydrolases and others have been examined in this review with respect to their stress-tolerant features and further improvement via enzyme engineering. Some rare instances of plant-derived enzymes that point to greater exploration for industrial use have also been presented here. The overall implication is to utilize biochemical clues from the plant-based enzymes for robust, efficient, and substrate/reaction conditions-versatile scaffolds or reference leads for enzyme engineering

Antioxidant-mediated up-regulation of OGG1 via NRF2 induction is associated with inhibition of oxidative DNA damage in estrogen-induced breast cancer

Abstract Background Estrogen metabolism-mediated oxidative stress is suggested to play an important role in estrogen-induced breast carcinogenesis. We have earlier demonstrated that antioxidants, vitamin C (Vit C) and butylated hydroxyanisole (BHA) inhibit 17β-estradiol (E2)-mediated oxidative stress and oxidative DNA damage, and breast carcinogenesis in female August Copenhagen Irish (ACI) rats. The objective of the present study was to characterize the mechanism by which above antioxidants prevent DNA damage during breast carcinogenesis. Methods Female ACI rats were treated with E2; Vit C; Vit C + E2; BHA; and BHA + E2 for up to 240 days. mRNA and protein levels of a DNA repair enzyme 8-Oxoguanine DNA glycosylase (OGG1) and a transcription factor NRF2 were quantified in the mammary and mammary tumor tissues of rats after treatment with E2 and compared with that of rats treated with antioxidants either alone or in combination with E2. Results The expression of OGG1 was suppressed in mammary tissues and in mammary tumors of rats treated with E2. Expression of NRF2 was also significantly suppressed in E2-treated mammary tissues and in mammary tumors. Vitamin C or BHA treatment prevented E2-mediated decrease in OGG1 and NRF2 levels in the mammary tissues. Chromatin immunoprecipitation analysis confirmed that antioxidant-mediated induction of OGG1 was through increased direct binding of NRF2 to the promoter region of OGG1. Studies using silencer RNA confirmed the role of OGG1 in inhibition of oxidative DNA damage. Conclusions Our studies suggest that antioxidants Vit C and BHA provide protection against oxidative DNA damage and E2-induced mammary carcinogenesis, at least in part, through NRF2-mediated induction of OGG1.Peer Reviewe

MACHINE LEARNING-INSPIRED RESOURCE MANAGEMENT IN M3D-ENABLED MANYCORE ARCHITECTURES

Monolithic 3D (M3D) integration has emerged as an enabling technology to design high performance and energy-efficient circuits and systems. The smaller dimension of vertical monolithic inter-tier vias (MIVs) lowers effective wirelength and allows high integration density. To design an energy-efficient many-core architecture, necessitates efficient resource management of the full SOC system, in terms of power and performance of the system. Voltage/frequency island (VFI)-based power management is a popular methodology for designing energy-efficient manycore architectures without incurring significant performance overhead. In an M3D chip, the vertical layers introduce inter-tier process variations that affect the performance of transistors and interconnects in different layers. Therefore, VFI-based power management in M3D manycore systems requires the consideration of inter-tier process variation effects. In this dissertation, we undertake the problem of resource management in M3D many-core architectures degraded due to inter-tier process variation effects inherent in M3D chips. Firstly, we present the design of an imitation learning (IL)-enabled VFI-based power management strategy that considers the inter-tier process-variation effects in M3D manycore chips. We demonstrate that the IL-based power management strategy can be fine-tuned based on the M3D characteristics. Our policy generates suitable V/F levels based on the computation and communication characteristics of the system for both process-oblivious and process-aware configurations. Subsequently, we propose a machine learning-based online update strategy of IL-based DVFI policies for process degraded M3D architectures. We demonstrate that with no prior knowledge of process-variation parameters, our online strategy captures the inter-tier process variations in the M3D system improving the power-performance trade-off than a process-oblivious offline DVFI policy for the degraded M3D many-core architecture. Furthermore, we show that online update strategy improves the overall energy-efficiency for unseen workloads that are not considered during offline DVFI policy creation

Modified fermi level in strontium nanoparticles decorated reduced graphene oxide for wide concentration detection of nitrogen dioxide at room temperature

We demonstrate room temperature nitrogen dioxide (NO2) sensing at parts per billion level (ppb) using a chemiresistive sensor based on strontium nanoparticles decorated reduced graphene oxide. Among the various functional materials used for NO2 sensing, it is a unique study reported for the first time using hybrid of reduced graphene oxide with a low work function alkaline earth metal. An increase of nearly 222% in sensing response is observed in the hybrid device over reduced graphene oxide alone at a concentration of 1 ppm. Moreover, the hybrid device exhibits a good sensitivity to NO2 over a wide concentration range from 500 ppb to 104 ppm. Additionally, the hybrid device is highly selective to NO2 amongst other pollutants. The integration of strontium nanoparticles onto reduced graphene oxide imparts excellent performance to the hybrid sensor due to their high adsorption energy for NO2. Further, strontium nanoparticle, being a low work function material, raises the fermi level of reduced graphene oxide and populate it with more electrons thus facilitating rapid charge transfer to electrophilic nitrogen dioxide. Hence, strontium nanoparticles attribute to an important role in fast and selective adsorption of nitrogen dioxide at room temperature with underlying graphene helping in rapid charge transfer

Tailored nitrogen dioxide sensing response of three-dimensional graphene foam

Ultralight and macroporous three-dimensional reduced graphene oxide (rGO) foams are prepared by lyophilization (freeze-drying) technique to avoid a conventional template method. This method allows tailoring the porosity of the foams by varying the weight percentages of graphene oxide dispersions in water. Three different rGO foams of 0.2, 0.5 and 1.0 wt% are used for NO2 sensing. Sensing response from the tailored structure of rGO is found to be directly related to the density. A maximum of 20% sensing response is observed for a higher porosity of the structure, better than the known results so far on graphene foams in the literature. (C) 2015 Elsevier B.V. All rights reserved