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Traditional antibody-drug conjugate (ADC) technology has employed tumor-targeting antibodies to selectively deliver ultrapotent cytotoxins to tumor tissue. While this technology has been highly successful, resulting in the FDA approval of over 10 ADCs, the field continues to struggle with modest efficacy and significant off-target toxicity. Concurrent with the struggles of the ADC field, a new generation of immune-activating therapeutics has arisen, most clearly exemplified by the PD-1/PD-L1 inhibitors that are now part of standard-of-care treatment regimens for a variety of cancers. The success of these immuno-oncology therapeutic agents has prompted the investigation of a variety of new immuno-stimulant approaches, including toll-like receptor (TLR) activators. Herein, we describe the optimization of ADC technology for the selective delivery of a potent series of TLR7 agonists. A series of imidazole[4,5-c]quinoline agonists (as exemplified by compound

KRAS is a well-validated anti-cancer therapeutic target, whose transcriptional downregulation has been demonstrated to be lethal to tumor cells with aberrant KRAS signaling. G-quadruplexes (G4s) are non-canonical nucleic acid structures that mediate central dogmatic events, such as DNA repair, telomere elongation, transcription and splicing events. G4s are attractive drug targets, as they are more globular than B-DNA, enabling more selective gene interactions. Moreover, their genomic prevalence is increased in oncogenic promoters, their formation is increased in human cancers, and they can be modulated with small molecules or targeted nucleic acids. The putative formation of multiple G4s has been described in the literature, but compounds with selectivity among these structures have not yet been able to distinguish between the biological contribution of the predominant structures. Using cell free screening techniques, synthesis of novel indoloquinoline compounds and cellular models of KRAS-dependent cancer cells, we describe compounds that choose between KRAS promoter G4near and G4mid, correlate compound cytotoxic activity with KRAS regulation, and highlight G4mid as the lead molecular non-canonical structure for further targeting efforts.

Lipid nanoparticles (LNPs) can be used as delivery vehicles for nucleic acid biotherapeutics. In fact, LNPs are currently being used in the Pfizer/BioNTech and Moderna COVID-19 vaccines. Cationic LNPs composed of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/cholesterol (chol) LNPs have been classified as one of the most efficient gene delivery systems and are being tested in numerous clinical trials. The objective of this study was to examine the effect of the molar ratio of DOTAP/chol, PEGylation, and lipid to mRNA ratio on mRNA transfection, and explore the applications of DOTAP/chol LNPs in pDNA and oligonucleotide transfection. Here we showed that PEGylation significantly decreased mRNA transfection efficiency of DOTAP/chol LNPs. Among non-PEGylated LNP formulations, 1:3 molar ratio of DOTAP/chol in DOTAP/chol LNPs showed the highest mRNA transfection efficiency. Furthermore, the optimal ratio of DOTAP/chol LNPs to mRNA was tested to be 62.5 µM lipid to 1 μg mRNA. More importantly, these mRNA-loaded nanoparticles were stable for 60 days at 4 °C storage without showing reduction in transfection efficacy. We further found that DOTAP/chol LNPs were able to transfect pDNA and oligonucleotides, demonstrating the ability of these LNPs to transport the cargo into the cell nucleus. The influence of various factors in the formulation of DOTAP/chol cationic LNPs is thus described and will help improve drug delivery of nucleic acid-based vaccines and therapies.

To review the pharmacology, efficacy, and safety of lofexidine for the treatment of opioid withdrawal secondary to the recent Food and Drug Administration (FDA) approval.A literature search using PubMed was conducted (inception to December 2018) using the terms lofexidine, opioid, opiate, and withdrawal. References from retrieved articles and the prescribing information were reviewed for any additional material.The literature search was limited to human studies published in English that pertained to human pharmacology, pharmacokinetics, pharmacodynamics, dosing, efficacy, and safety regarding opioid withdrawal. Phase I, II, and III studies of lofexidine for opioid withdrawal were reviewed for inclusion.Lofexidine is newly FDA approved in the United States for the treatment of opioid withdrawal symptoms in adults. Several randomized controlled trials and a Cochrane review noted the effectiveness of lofexidine versus placebo for this indication. The efficacy of lofexidine has also been shown to be comparable to that of other indicated first- and second-line pharmacological agents. Relevance to Patient Care and Clinical Practice: This article examines the trials that led to lofexidine's new FDA-approved indication as well as other recent literature published since its last major review, seeking to guide providers in the appropriate use of lofexidine for its new indication.Lofexidine is an effective and safe agent in treating symptoms related to opioid withdrawal in adults when compared with placebo; although it is more widely accessible than other first-line therapies, its use in practice may be limited by cost.

KRAS is a GTPase involved in the proliferation signaling of a number of growth factors, such as epidermal growth factor. The protein is mutated or upregulated in an array of cancers, including pancreatic and ovarian cancers, where it correlates with more aggressive and chemoresistant disease. Within the promoter of KRAS lies a G-rich region capable of forming the higher order non-canonical DNA structure, the G-quadruplex (G4). Stabilization of G4 formation in the mid-region of the KRAS promoter downregulates transcription and facilitates decreased growth and chemo-sensitization of pancreatic and ovarian cancer cells with aberrant KRAS signaling. Our collaborative team designed Polypurine Reverse Hoogsteen (PPRH) hairpin oligonucleotides that establish Watson Crick bonds with the pyrimidine strand within the KRAS-mid-G4-forming region to enhance G4 formation, downregulate KRAS transcription and mediate an anti-proliferative effect. In particular, two PPRHs were designed to interact with the 3’ and 5’ ends of the G4-forming region, along with two correlating W:C, and one scramble, controls. The binding of these oligonucleotides to the G4-forming region was verified by gel electrophoresis, and the cell activity was examined in vitro both by luciferase and in pancreatic and ovarian cancer cells. Using a luciferase construct driven by the KRAS promoter, only the PPRHs, and none of the control oligonucleotides, significantly decreased activity. Cytotoxicity experiments in KRAS dependent and independent cell lines demonstrated that PPRHs, but not control oligonucleotides, selectively suppressed proliferation only in the dependent pancreatic and ovarian cancer cell lines. Correlation of the cytotoxic effects of these potential therapeutic PPRHs with transcriptional downregulation is under investigation. PPRH also demonstrated synergistic activity with a KRAS promoter selective G4-stabilizing compound in KRAS-dependent pancreatic cells, and sensitization to standard chemotherapeutic regimens is also being studied. These designed PPRH oligonucleotides selectively stabilize G4 formation within the KRAS mid promoter region, and represent an innovative approach both for G4-stabilization and KRAS modulation with potential for development into novel therapeutics. Citation Format: Alexandra Maria Psaras, Simonas Valiuska, Veronique Noe, Carlos J. Ciudad, Tracy A. Brooks. Facilitating G-quadruplex formation in the KRAS promoter with polypurine reverse Hoogsteen oligonucleotides [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 675.

Introduction: As the role of the pharmacist on the transdisciplinary palliative care team grows, the need for adequate instruction on palliative care and clinical reasoning skills in schools of pharmacy grows accordingly. Methods: This study evaluates second- and third-year pharmacy students from 6 accredited schools of pharmacy that participated in surveys before and after the delivery of a didactic palliative care elective. The survey collected student demographics, perceptions of the importance of and student skill level in palliative care topics. The script concordance test (SCT) was used to assess clinical decision-making skills on patient cases. Student scores on the SCT were compared to those of a reference panel of experts. Results: A total of 89 students completed the pre-/postsurveys and were included in data analysis. There was no statistically significant difference in student perceived importance of palliative care skills before and after the elective. Students from all 6 institutions showed significant increase in confidence in their palliative care skills at the end of the course. There was also a significant improvement across all institutions in clinical reasoning skills in most of the SCT questions used to assess these skills. Conclusions: Students choosing an elective in palliative care likely do so because they already have an understanding of the importance of these topics in their future practice settings. Delivery of a palliative care elective in the pharmacy curriculum significantly increases both student confidence in their palliative care skills and their clinical reasoning skills in these areas.

KRAS is a well validated anti-cancer therapeutic target; many active drug discovery programs are ongoing with foci on individual mutant isoforms, necessitating a wide array of drugs to be developed and missing cancers with dysregulation of non-mutant KRAS. Transcriptional down-regulation has been demonstrated to be lethal to tumor cells with aberrant KRAS signaling, irrespective of mutational status, and to potentially have a wide therapeutic window. G-quadruplex (G4) formation within KRAS's core promoter offers a molecular target to decrease the gene expression. Targeted G4-stabilization within the KRAS promoter targets cancer cells' acquired addiction to the transforming event of aberrant KRAS signaling through an activating mutation or protein overexpression, and thus is applicable to both of these deviant states. Small molecules that specifically inhibit transcriptional expression of KRAS genes have great potential for patients whose tumors have disregulated KRAS function. In the current works, compounds clarify the physiologically relevant G4 within the KRAS promoter (G4mid) through a combination of ex vivo screening, luciferase, cytotoxicity, and transcriptional regulation assays. A small set of novel indolo[2,3-c]quinoline compounds were synthesized and a newly optimized FRET Melt2 assay with a Z' score of >0.5 was used to determine KRAS G4mid stabilization efficacy and selectivity. Compounds were then examined for KRAS promoter stabilization using a luciferase assay, pancreatic and ovarian cancer cytotoxicity by an MTS assay, and correlative changes in KRAS transcription as measured by multiplexed qPCR. JM-222 is the lead indolo[2,3-c]quinoline compound that demonstrates KRAS G4mid selective stabilization and promoter regulation, cancer cell cytotoxicity and altered KRAS transcription. These works highlight the function of G4mid in regulating KRAS transcription, novel synthetic methods for indolo[2,3-c]quinoline synthesis, the improved utility of the FRET Melt2 assay, and the overall potential for small compound-mediated KRAS promoter G4 stabilization for patients harboring tumors with aberrant KRAS signaling. Citation Format: Alexandra Maria Psaras, Jared Miller, L. Nathan Tumey, Tracy A. Brooks. Anticancer activitiy of indolo[2,3-c]quinoline stabilization of the KRAS promoter G4mid structure [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1246.

A new iridoid glycoside; 6-O-β-D-xylopyranoside-shanzhiside methyl ester (1) along with six known compounds; shanzhiside methyl ester (2), lamalbid (3), geniposidic acid (4), theveside (5), verbascoside (6) and arenarioside (7) were isolated from the roots of Lantana montevidensis. The structures of the compounds were determined through 1D and 2D NMR spectroscopic data analysis, HRESIMS, electronic circular dichorism and UPLC-UV/MS method. The total extract, chloroformic (F1) and aqueous (F2) fractions together with the isolated compounds were tested for their antimicrobial, antiprotozoal, antiplasmodial, anti-inflammatory, monoamine oxidase inhibition and cell viability activities in addition to free radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The phenylpropanoid compounds (6 and 7) resulted in a potent antioxidant activity. Total methanolic extract together with the aqueous fraction (F2) showed decrease in reactive oxidative stress with 57 and 66%, respectively, while the chloroformic fraction (F1), together with the total methanolic extract, showed a decrease in iNOS with IC50 values 5 and 30 μg/mL, respectively. Compounds 1, 2, 3, 6, and 7 showed inhibition in the reactive oxidative stress with values 50, 60, 57, 63, and 52%, respectively. Both F1 and F2 fractions demonstrated measurable inhibition of MCF-7 breast cancer cell growth, with IC50 value 0.3 mg/mL. Compounds 2 and 7 showed mild monoamine oxidase inhibition. None of the tested compounds showed antimicrobial, antiplasmodial or antiprotozoal activity.

The MYC proto-oncogene is upregulated, often at the transcriptional level, in ∼80% of all cancers. MYC's promoter is governed by a higher order G-quadruplex (G4) structure in the NHE III1 region. Under a variety of conditions, multiple isoforms have been described to form from the first four continuous guanine runs (G41-4) predominating under the physiologically relevant supercoiled conditions. In the current study, short oligonucleotides complementing the 5'- and 3'-regions flanking the G4 have been connected by an abasic linker to form G4 clamps, varying both linker length and G4 isoform being targeted. Clamp A with an 18 A linker was found to have marked affinity for its target isomer (G41-4) over the other major structures (G42-5 and G41-5, recognized by clamps B and C, respectively), and to be able to shift equilibrating DNA to foster greater G4 formation. In addition, clamp A, but not B or C, is able to modulate MYC promoter activity with a significant and dose-dependent effect on transcription driven by the Del4 plasmid. This linked clamp-mediated approach to G4 recognition represents a novel therapeutic mechanism with specificity for an individual promoter structure, amenable to a large array of promoters.

Background: Non-Hodgkin's Lymphoma (NHL) is the fifth most common cancer in the United States. Up to 40% of NHL is diffuse large B-cell lymphoma (DLBCL); while only 3% of NHL is classified as mantle cell lymphoma, it is a particularly lethal disease. DLBCL and MCL patients that aberrantly express MYC, which occurs up to 20 and 50% of the time, respectively, have worse survival rates and a lack of sustained clinical response to the standard R-CHOP therapy. We sought to examine both the effect of MYC downregulation on the efficacy of standard of care drugs and enhanced anti-cancer activity with a novel NF-kB targeting steroid, in place of prednisone/prednisolone, and also under conditions of MYC modulation, in NHL cells. Methods and Summary of Findings: The downregulation of MYC was achieved in two distinct manners: with siRNA and with our pioneered MYC G-quadruplex (G4)-stabilizing DNA interference (DNAi) oligonucleotide. This DNAi was optimized for stability, specificity, and in cell activity, from our previously work developing this approach (Hao, et al, NAR 2016). The optimization was done using EMSA, chemical (DMS) footprinting, cell viability assays, qPCR, and microscopy. The lead steroid compound, which is selective for NF-κB signaling inhibition over DNA binding and transcription effects, was more cytotoxic than prednisolone, as determined by cell viability assays in NHL cells. Moreover, its effects on cell growth were additive with doxorubicin, and the overall effect of both drugs on cytotoxicity were enhanced by MYC downregulation. The combination studies were also performed with prednisolone; effects on decreased cell viability were more notable with the novel steroid, as compared to prednisolone. Conclusion: MYC-overexpressing NHL, particularly DLBCL and MCL, respond poorly to the standard R-CHOP therapy. The addition of a MYC-downregulating DNAi, a novel NF-kB targeting steroid, or both, have been noted to enhance the cytotoxic effects of standard drugs. Work is expanding to evaluate the utility of an updated R-CHOP regimen in order to enhance survival for patients with MYC-overexpressing NHL. Citation Format: Alexandra Maria Psaras, Tracy Ann Brooks. Enhancing therapies for MYC-overexpressing Non-Hodgkin's lymphoma: A role for MYC downregulation and new combination therapies [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 653.

Non-B-DNA G-quadruplex (G4) structures have shown promise as molecular targets. Modulating G4 stability for oncogenic transcriptional control is a promising avenue for the development of novel therapeutics. Extracellularly, G4 stabilization can be mediated by alkali cations, modifying water content, or with molecular crowding. Intracellularly, G4 formation is mediated by negative superhelicity and transcriptional activity, and can be stabilized with small molecules or oligonucleotides. Numerous G4-stabilizing compounds have been identified that impact promoter activity in plasmids. These compounds, however, infrequently show activity in cells, are found to have non-G4-mediated mechanisms of action, or do not demonstrate activity in vivo. The G4 field requires enhanced predictive screening methods to identify compounds with G4-mediated in vitro activity and in vivo efficacy. Using the best characterized promoter G4 to date, MYC, we examined the effects of varying annealing conditions (rate of cool down and number of heat/cool cycles), co-solvents (glucose, acetonitrile, polyethylene glycol, dextran sulfate, sucrose, ficoll-70, glycerol) and nucleoplasm on G4 formation and compound screening. We observed a marked decrease in hit rates when shifting from simple buffer conditions to include potassium and glycerol, and utilizing two or more rapid annealing cycles; the difference in hit compounds coincides with previous findings of active, inactive, and non-G4-mediated activity, including NSC338258, Quindoline i, and TMPyP4; with these changes, we describe a modification of the primary FRET Melt screening assay – the FRET Melt(2). This understanding of physiological principles governing the above G4 formation will better inform future drug discovery efforts for this and other oncogenic promoters.

Non-canonical DNA structures are found throughout the genome, transiently interspersed with B-DNA, in regions that are important for the regulation of various cellular processes. G–C-rich tracts, in particular, can form unique higher order G-quadruplex structures, which have been shown to exist in regions of DNA repair, telomeric regulation, centromeres and, most notably, transcriptional control. These structures have been identified in the promoters of an array of proto-oncogenes and represent attractive targets for small molecule development. This chapter focuses on the identification and targeting of G-quadruplex structures found in telomeres and oncogenes, discusses the findings related to the transcriptional regulation of MYC, kRAS, and Bcl-2, and concludes with a discussion on the future of targeting unique G-quadruplexes throughout the genome.

The four-stranded i-motif (iM) conformation of cytosine-rich DNA is important in a wide variety of biochemical systems ranging from its use in nanomaterials to a potential role in oncogene regulation. An iM is stabilized by acidic pH that allows hemiprotonated cytidines to form a C·C(+) base pair. Fundamental studies that aim to understand how the lengths of loops connecting the protonated C·C(+) pairs affect intramolecular iM physical properties are described here. We characterized both the thermal stability and the pK(a) of intramolecular iMs with differing loop lengths, in both dilute solutions and solutions containing molecular crowding agents. Our results showed that intramolecular iMs with longer central loops form at pHs and temperatures higher than those of iMs with longer outer loops. Our studies also showed that increases in thermal stability of iMs when molecular crowding agents are present are dependent on the loop that is lengthened. However, the increase in pK(a) for iMs when molecular crowding agents are present is insensitive to loop length. Importantly, we also determined the proton activity of solutions containing high concentrations of molecular crowding agents to ascertain whether the increase in pK(a) of an iM is caused by alteration of this activity in buffered solutions. We determined that crowding agents alone increase the apparent pK(a) of a number of small molecules as well as iMs but that increases to iM pK(a) were greater than that expected from a shift in proton activity.

DNA sequences with the potential to form secondary structures such as i-motifs (iMs) and G-quadruplexes (G4s) are abundant in the promoters of several oncogenes and, in some instances, are known to regulate gene expression. Recently, iM-forming DNA strands have also been employed as functional units in nanodevices, ranging from drug delivery systems to nanocircuitry. To understand both the mechanism of gene regulation by iMs and how to use them more efficiently in nanotechnological applications, it is essential to have a thorough knowledge of factors that govern their conformational states and stabilities. Most of the prior work to characterize the conformational dynamics of iMs have been done with iM-forming synthetic constructs like tandem (CCT)n repeats and in standard dilute buffer systems. Here, we present a systematic study on the consequences of epigenetic modifications, molecular crowding, and degree of hydration on the stabilities of an iM-forming sequence from the promoter of the c-myc gene. Our results indicate that 5-hydroxymethylation of cytosines destabilized the iMs against thermal and pH-dependent melting; contrarily, 5-methylcytosine modification stabilized the iMs. Under molecular crowding conditions (PEG-300, 40% w/v), the thermal stability of iMs increased by ∼10 °C, and the pKa was raised from 6.1 ± 0.1 to 7.0 ± 0.1. Lastly, the iM's stability at varying degrees of hydration in 1,2-dimethoxyethane, 2-methoxyethanol, ethylene glycol, 1,3-propanediol, and glycerol cosolvents indicated that the iMs are stabilized by dehydration because of the release of water molecules when folded. Our results highlight the importance of considering the effects of epigenetic modifications, molecular crowding, and the degree of hydration on iM structural dynamics. For example, the incorporation of 5-methylycytosines and 5-hydroxymethlycytosines in iMs could be useful for fine-tuning the pH- or temperature-dependent folding/unfolding of an iM. Variations in the degree of hydration of iMs may also provide an additional control of the folded/unfolded state of iMs without having to change the pH of the surrounding matrix.

Curcumin (CUR; diferuloylmethane), a rhizome extract of Curcuma Longa L. is commonly used as a food coloring and flavoring agent. Although oriental and Ayurvedic medicines have traditionally used CUR in the treatment of diseases, conventional medicine has just begun to recognize its potential therapeutic value. Numerous recent studies have demonstrated the ability of CUR to halt or prevent certain types of cancer, decrease inflammation, and improve cardiovascular health. However, very few studies have examined its ability to protect against drug-induced organ injury. This study explored whether CUR pre-exposure has the potential to prevent acetaminophen (APAP)-induced: (i) hepatotoxicity, (ii) genomic injury, (iii) oxidative stress in the liver, and (iv) apoptotic and necrotic cell deaths in the liver in vivo. Additional goals were to investigate the interplay of pro- and anti-apoptotic genes and their ultimate impact on various forms of cell death. In order to study the CUR-APAP interaction, male B6C3F1 mice were gavaged with CUR (17 mg/kg/day, p.o.) for 12 days followed by a single APAP exposure (400 mg/kg, ip). Four groups of animals (control, CUR, APAP, CUR+APAP) were sacrificed 24 h after APAP exposure. The results indicated that APAP-induced liver injury associated events as serum ALT (80-fold), lipid peroxidation (357%) and DNA fragmentation (469%) were markedly reduced to 3-fold, 134% and 162%, respectively, in the CUR+APAP group. The APAP-induced increase in expression of pro-apoptotic genes (Bax, caspase-3) decreased while expression of anti-apoptotic genes (Bcl-XL) increased in CUR preexposed mouse livers, and these changes were mirrored in the pattern of apoptotic and necrotic cell deaths. Levels of DNA damage sensor P⁵³ and its counterpart Mdm2 were also analyzed during this interaction. Based on the available literature, and these results, it seems likely that CUR may impart global protection in vivo against drug-induced liver injury by opposing several crucial events instrumental to both apoptosis and necrosis.

The presence and biological importance of DNA secondary structures in eukaryotic promoters are becoming increasingly recognized among chemists and biologists as bioinformatics in vitro and in vivo evidence for these structures in the c-Myc, c-Kit, KRAS, PDGF-A, hTERT, Rb, RET and Hif-1α promoters accumulates. Nevertheless, the evidence remains largely circumstantial. This minireview differs from previous ones in that here we examine the diversity of G-quadruplex and i-motif structures in promoter elements and attempt to categorize the different types of arrangements in which they are found. For the c-Myc G-quadruplex and Bcl-2 i-motif, we summarize recent biological and structural studies.

MYC is deregulated in most tumour types, but an effective means to selectively target its aberrant expression is not yet available. Supercoiling that is induced by transcription has been demonstrated to have dynamic effects on DNA in the MYC promoter element: it converts duplex DNA to non-duplex DNA structures, even at considerable distances from the transcriptional start site. These non-duplex DNA structures, which control both turning on and off of transcription and the rate of transcription firing, are amenable to small-molecule targeting. This dynamic system provides a unique opportunity for the treatment of tumours in which MYC is an important oncogene.

P-glycoprotein (Pgp, ABCB1) is a critical efflux transporter at the blood-brain barrier (BBB) where its luminal location and substrate promiscuity limit the brain distribution of numerous therapeutics. Moreover, Pgp is known to confer multi-drug resistance in cancer chemotherapy and brain diseases, such as epilepsy, and is highly regulated by inflammatory mediators. The involvement of inflammatory processes in neuropathological states has led us to investigate the effects of peripheral inflammatory hyperalgesia on transport properties at the BBB. In the present study, we examined the effects of lambda-carrageenan-induced inflammatory pain (CIP) on brain endothelium regulation of Pgp. Western blot analysis of enriched brain microvessel fractions showed increased Pgp expression 3 h post-CIP. In situ brain perfusion studies paralleled these findings with decreased brain uptake of the Pgp substrate and opiate analgesic, [(3)H] morphine. Cyclosporin A-mediated inhibition of Pgp enhanced the uptake of morphine in lambda-carrageenan and control animals. This indicates that the CIP induced decrease in morphine transport was the result of an increase in Pgp activity at the BBB. Furthermore, antinociception studies showed decreased morphine analgesia following CIP. The observation that CIP modulates Pgp at the BBB in vivo is critical to understanding BBB regulation during inflammatory disease states.

The blood–brain barrier (BBB) is a dynamic system which maintains brain homeostasis and limits CNS penetration via interactions of transmembrane and intracellular proteins. Inflammatory pain (IP) is a condition underlying several diseases with known BBB perturbations, including stroke, Parkinson's, multiple sclerosis and Alzheimer's. Exploring the underlying pathology of chronic IP, we demonstrated alterations in BBB paracellular permeability with correlating changes in tight junction (TJ) proteins: occludin and claudin-5. The present study examines the IP-induced molecular changes leading to a loss in functional BBB integrity. IP was induced by injection of Complete Freund's Adjuvant (CFA) into the plantar surface of the right hindpaw of female Sprague–Dawley rats. Inflammation and hyperalgesia were confirmed, and BBB paracellular permeability was assessed by in situ brain perfusion of [14C]sucrose (paracellular diffusion marker). The permeability of the BBB was significantly increased at 24 and 72 h post-CFA. Analysis of the TJ proteins, which control the paracellular pathway, demonstrated decreased claudin-5 expression at 24 h, and an increase at 48 and 72 h post-injection. Occludin expression was significantly decreased 72 h post-CFA. Expression of junction adhesion molecule-1 (JAM-1) increased 48 h and decreased by 72 h post-CFA. Confocal microscopy demonstrated continuous expression of both occludin and JAM-1, each co-localizing with ZO-1. The increased claudin-5 expression was not limited to the junction. These results provide evidence that chronic IP causes dramatic alterations in specific cytoarchitectural proteins and demonstrate alterations in molecular properties during CFA, resulting in significant changes in BBB paracellular permeability.

Background: The synthetic 4’-O-benzylated doxorubicin analog WP744 was designed to abrogate transport by the multidrug resistance (MDR)-associated ATP-binding cassette (ABC) proteins P-glycoprotein (Pgp) and multidrug resistance protein (MRP-1). We compared its uptake and cytotoxicity with those of doxorubicin and daunorubicin in cell lines overexpressing Pgp, MRP-1 or breast cancer resistance protein (BCRP) and in acute myeloid leukemia (AML) cells. Methods: Cellular uptake was studied by flow cytometry and cytotoxicity in 96-h 96-well cultures in cell lines overexpressing Pgp, MRP-1 or wild type (BCRPR482) or mutant (BCRPR482T, BCRPR482G) BCRP and in pre-treatment AML marrow cells. Results: Uptake and cytotoxicity of WP744 were consistently greater than those of doxorubicin and daunorubicin at equimolar concentrations in all cell lines studied and in AML cells. Conclusion: WP744 overcomes transport by Pgp, MRP-1 and BCRP in cell lines and AML cells and is a promising agent for clinical development in AML and other malignancies with broad-spectrum multidrug resistance.

kRAS is one of the most prevalent oncogenic aberrations. It is either upregulated or mutationally activated in a multitude of cancers, including pancreatic, lung, and colon cancers. While a significant effort has been made to develop drugs that target kRAS, their clinical activity has been disappointing due to a variety of mechanistic hurdles. The presented works describe a novel mechanism and molecular target to downregulate kRAS expression--a previously undescribed G-quadruplex (G4) secondary structure within the proximal promoter acting as a transcriptional silencer. There are three distinct guanine-rich regions within the core kRAS promoter, including a previously examined region (G4near). Of these regions, the most distal region does not form an inducible and stable structure, whereas the two more proximal regions (termed near and mid) do form strong G4s. G4near is predominantly a tri-stacked structure with a discontinuous guanine run incorporated; G4mid consists of seven distinct runs of continuous guanines and forms numerous competing isoforms, including a stable three-tetrad stacked mixed parallel and antiparallel loop structures with longer loops of up to 10 nucleotides. Comprehensive analysis of the regulation of transcription by higher order structures has revealed that the guanine-rich region in the middle of the core promoter, termed G4mid, is a stronger repressor of promoter activity than G4near. Using the extensive guanine-rich region of the kRAS core promoter, and particularly the G4mid structure, as the primary target, future drug discovery programs will have potential to develop a potent, specifically targeted small molecule to be used in the treatment of pancreatic, ovarian, lung, and colon cancers.

The blood-brain barrier (BBB) maintains brain homeostasis by limiting entry of substances to the central nervous system through interaction of transmembrane and intracellular proteins that make up endothelial cell tight junctions (TJs). Recently it was shown that the BBB can be modulated by disease pathologies including inflammatory pain. This study examined the effects of chronic inflammatory pain on the functional and molecular integrity of the BBB. Inflammatory pain was induced by injection of complete Freund's adjuvant (CFA) into the right plantar hindpaw in female Sprague-Dawley rats under halothane anesthesia; control animals were injected with saline. Edema and hyperalgesia were assessed by plethysmography and infrared paw-withdrawal latency. At 72 h postinjection, significant edema formation and hyperalgesia were noted in the CFA-treated rats. Examination of permeability of the BBB by in situ perfusion of [14C]sucrose while rats were under pentobarbital anesthesia demonstrated that CFA treatment significantly increased brain sucrose uptake. Western blot analysis of BBB TJ proteins showed no change in expression of zonula occludens-1 (an accessory protein) or actin (a cytoskeletal protein) with CFA treatment. Expression of the transmembrane TJ proteins occludin and claudin-3 and -5 significantly changed with CFA treatment with a 60% decrease in occludin, a 450% increase in claudin-3, and a 615% increase in claudin-5 expression. This study demonstrates that during chronic inflammatory pain, alterations in BBB function are associated with changes in specific transmembrane TJ proteins.

A series of novel taxane-based multidrug resistance (MDR) reversal agents (TRAs) has been designed and synthesized. Structure-activity relationship (SAR) study clearly indicates that modification of the C-7 position with hydrophobic arenecarbonylcinnamoyl groups brings about high potency against drug efflux mediated by P-glycoprotein (P-gp). Six TRAs exhibit ability to modulate a wide range of ATP-binding cassette (ABC) transporters, such as P-gp, multidrug resistance-associated protein 1 (MRP1), and breast cancer resistance protein (BCRP), which may serve as novel broad-spectrum modulators of ABC transporters.

The synthesis and characterization of a family of nine pH-responsive, diblock copolymers designed to effectively deliver nucleic acids are reported. The stabilizing A block is comprised of an oligo(ethylene glycol) methyl ether methacrylate to impart water solubility. The cationic blocks of varying degrees of polymerization (DPs) are derived from three pH responsive, tertiary amine-containing methacrylates capable of complexing negatively charged nucleic acids. The cytotoxicity studies utilizing human embryonic kidney cells (HEK-293) and Michigan Cancer Foundation-7 (MCF-7) breast cancer cells indicate no decrease of cell viability with the diblock copolymers, with the exception of the two highest DPs of the cationic blocks with ethyl-substitutes tertiary amine. Gene knockdown experiments indicate high siRNA delivery and MYC gene knockdown in MCF-7 breast cancer cells for eight of the nine studied block copolymers. The results of the current study enable further development of the pH-responsive copolymer family for promising nucleic acid delivery vehicles applicable for clinical use.

G-quadruplexes (G4s) tend to cluster around biologically important regions such as promoters of DNA, 5’-UTR of mRNA and telomeres. Modulating the stability of G4 as in these regulatory sequences is an emerging approach for cancer treatment. MYC proto-oncogene is overexpressed in over 80% of tumor types, contributing to deregulated cancer cell proliferation. Silencing MYC expression has been demonstrated to be an effective approach to inhibit tumor growth. Among all the silencing strategies, stabilizing MYC promoter G4 that serves as an on-off switch for the transcription of MYC has been explored by the targeting of small molecules. However, the binding specificity of small molecule retarded the drug development process. Exploring novel MYC G4-targeting strategies is necessary to potentiate the pharmacological specificity of MYC G4 modulation. Here, we adopted a nucleic acid clamp based approach to recognize and stabilize the physiologically predominant MYC G4. Previously, a clamp (clamp A) was been demonstrated to recognize the physiologically relevant MYC G4 with high specificity and to downregulate MYC promoter activity. In the current research, we modified and optimized this clamp to allow for flexibility with labeling and monitoring techniques. The original 18 Å polyethylene glycol phosphate linker connecting the 5’ and 3’ regions of clamp A were substituted with thymine bases of varying lengths; 5 thymines were found to be optimal. The binding specificity and MYC G4 recognizing ability of this optimized clamp A T5 were confirmed by EMSA and ECD; the G4 stabilizing ability of clamp A T5 was demonstrated by DMS footprinting. The cytotoxicity of clamp A T5 was examined by MTS assay on HEK-293 and MCF-7 cells. The intracellular localization of clamp A T5 is being determined microscopically with a 6-FAM-labeled clamp A T5 after being transfected into and incubated with HEK-293 and MCF-7 cells for 48 hr. Nuclear localization is being examined by co-staining with DAPI, and MYC promoter localization is being determined by clustering with a MYC FISH probe. The modification of the clamp is both cost-effective, and enables the detailed study of intracellular functions. This clamp has potential as both a diagnostic tool to inform the use of MYC G4-targeted small molecules, and as a nanotherapeutic. Citation Format: Taisen Hao, Tracy A. Brooks. Nucleic acid clamp-mediated recognition and transcriptional modulation of MYC oncogenes through the stabilization of G-quadruplexes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2168. doi:10.1158/1538-7445.AM2017-2168

Epigenetic modifications to DNA base sequences may regulate gene expression. CpG islands can contain methylated (5mC) or hydroxymethylated (5hmC) cytosine. Most CpG islands are found primarily in promoter regions that may also contain a high number of repeated cytosines and/or guanines. G-quadraplexes (G4) and i-motifs (iM) are two unique DNA secondary structures that can form in repeating sequences of either guanine or cytosine, respectively. Both G4 and iM sequences may contain CpG sequences that can be methylated or hydroxymethylated. The effects of CpG islands on DNA secondary structures were determined by incorporating a single 5hmC at varying positions in the Vascular Endothelial Growth Factor (VEGF) G4 and iM sequences. An Olis DSM-20 spectropolarimeter and a Cary 100 UV-visible spectrometer were used to monitor the effect of 5hmC on G4 and iM thermal stability. Two of the three 5hmC-containing loops showed a notable decrease in stability for G4's and increased intermolecular structure formation. Contrastingly, the iM stability increased when 5hmC was incorporated into its sequence. Additionally, there was little change in the iM pka. In summary, our results suggest the 5hmC has little effect on iM structures, but can destabilize the G4's.

ADAM-15, with known zymogen, secretase, and disintegrin activities, is a catalytically active member of the ADAM family normally expressed in early embryonic development and aberrantly expressed in various cancers, including breast, prostate and lung. ADAM-15 promotes extracellular shedding of E-cadherin, a soluble ligand for the HER2/neu receptor, leading to activation, increased motility, and proliferation. Targeted downregulation of both ADAM-15 and HER2/neu function synergistically kills breast cancer cells, but to date there are no therapeutic options for decreasing ADAM-15 function or expression. In this vein, we have examined a unique string of guanine-rich DNA within the critical core promoter of ADAM-15. This region of DNA consists of seven contiguous runs of three or more consecutive guanines, which, under superhelical stress, can relax from duplex DNA to form an intrastrand secondary G-quadruplex (G4) structure. Using biophysical and biological techniques, we have examined the G4 formation within the entire and various truncated regions of the ADAM-15 promoter, and demonstrate strong intrastrand G4 formation serving to function as a biological silencer element. Characterization of the predominant G4 species formed within the ADAM-15 promoter will allow for specific drug targeting and stabilization, and the further development of novel, targeted therapeutics.

The effect of storage length and temperature on the shelf life of three ground beef formulations (lean:fat: 73:27, 81:19 and 91:9) was investigated. Coarsely ground beef was stored at − 1.7 or 2.3 °C for up to 28 d. Traditional overwrap packages were produced every 7 d prior to retail display for 24 h. Lipid oxidation (TBARS), subjective color, instrumental color, and aerobic bacteria were evaluated after 0 and 24 h of display. Formulation influenced initial L* and subjective color values (P < 0.05). Storage temperature did not affect initial color, but product stored at 2.3 °C was more discolored after 24 h (P < 0.05). Aerobic bacteria increased as storage d and temperature increased (P < 0.05). Initial TBARS increased through d 21, but were lower after 28 d. Overall, initial characteristics depended on formulation; however, ground beef shelf-life and stability were largely influenced by storage length and storage temperature.

Pancreatic cancer is the fourth most deadly cancer with 5 year survival rate of ∼6%. One of the major attributes of pancreatic cancer is kRAS mutations. kRAS is a proto-oncogene with intrinsic GTPase activity, and is responsible for cell proliferation, division, and apoptosis. kRAS mutations are observed in >95% of pancreatic adenocarcinoma and in 30% all human tumors. When mutated it leads to continuous activity and uncontrolled proliferation which results in increased tumorigenicity and poor prognosis. Downregulating kRAS expression has shown to halt proliferation and leads to cellular death in pancreatic cancer models, but to date no small molecule capable of such transcriptional silencing has been described. A novel series of molecules with either biphenylene or bipyridine spacer connecting the terminal benzofuran ring was synthesized using solution phase chemistry. Tertiary amine side chains were incorporated to the C2-position of the benzofuran ring to improve the DNA binding affinity of these compounds. The synthesized compounds were purified using a “catch and release” method employing the sulfonic acid based resins. The eleven novel compounds were screened in parallel for their ability to stabilize G-quadruplex structures in the kRAS promoter, and to downregulate kRAS promoter activity. Two of the compounds increased the thermal profile of non-canonical DNA formations in the promoter region by >5 °C; however, on the whole these compounds did not seem to function as G-quadruplex-stabilizing agents. Eight compounds significantly decreased luciferase expression under the explicit control of the kRAS promoter by up to 75%, by compound BF 4.3, through an as-yet unknown mechanism of action. The compound series was examined for the inhibition of cellular viability in two mutant kRAS pancreatic cancer cell lines - Panc-1 and MIA PaCa-2; in both cell lines the compounds containing the bipyridine spacer had greater cytotoxic effects with IC50's of ∼30 μM, consistently. qPCR is being used to confirm the decrease in promoter activity in native cellular conditions. These agents are intriguing in both their novel scaffold and their unexpected activity decreasing kRAS expression in a mechanism unrelated to higher order DNA structures. Ultimately, down regulation of kRAS transcription will provide a novel therapeutic approach for pancreatic cancer and improve the prognosis of this highly lethal disease. Citation Format: Harshul Batra, Mohammad K. Islam, David E. Thurston, Khondaker M. Rahman, Tracy A. Brooks. Biphenylene and bipyridine connected benzofuran compounds as novel regulators of kRAS transcription. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2914.

Pancreatic cancer is disproportionally lethal (7% of all cancer deaths), as compared to its incidence (3% of cancer incidences) within the United States. One of the most important genetic alterations in pancreatic cancer is within the kRAS oncogene. Over 60% of all pancreatic cancers, and up to 95% of pancreatic ductal adenocarcinomas, harbor mutations in this oncogene. While approaches to therapeutically modulate kRAS activity have not yielded clinical agents, downregulation of expression shows promise in preclinical models. To date, no molecular target has allowed for small molecule mediated downregulation of kRAS expression; however, the promoter region holds promise for a new approach. The kRAS promoter has three distinct guanine-rich regions capable of forming higher order non-B-DNA structures, G-quadruplexes (G4s). In particular the middle (mid) of these three regions forms a stable, inducible, and transcriptionally silencing G4 structures, whereas the more distal (far) region forms no such structure, and the more proximal (near) region has little to no biological function. The structure of this mid-region G4 has been elucidated by electromobility shift assay, DMS footprinting, and circular dichroism (CD). Small molecules capable of stabilizing this structure have been screened from the NCI Diversity Set III by the FRET melt assay, confirmed by CD, and examined for their downregulation of kRAS promoter activity. From the 1600 compounds, the indoloquinolone NSC 317605 is the lead molecule identified. It is particularly interesting as it prefers the mid-, as opposed to the near-, G4 and significantly reduces kRAS promoter activity. This is in contrast to the ellipticine NSC 176327, which favors the near-, over the mid-, G4 and does not decrease kRAS promoter activity. The effect of each compound on cell viability on kRAS transcription is under examination in a panel of pancreatic cancer cells. These works support previous findings that the mid-, and not the near-G4, harbors the potential to transcriptionally downregulate kRAS, and identify a new scaffold for future development. Brooks Lab startup funds, DoD, Rhianna Morgan GSC Grant, University of Mississippi School of Pharmacy Citation Format: Rhianna K. Morgan, Tracy A. Brooks. Small molecule targeting of the kRAS mid-G-quadruplex for potential pancreatic cancer therapeutics. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1254.

DNA G-quadruplexes (G4s) have become increasingly present in modern drug discovery efforts. The main focus centers on cancer therapeutic development, as G4s are more concentrated in oncogenic promoters than the rest of the genome. Two of the most well described G4s to date are within the MYC and the VEGF promoters; stabilization of either structure fosters transcriptional silencing. Downregulation of MYC decreases cell proliferation and alters metabolism; it is promising for a number of cancers, such lymphomas, leukemia, colorectal cancer and more. VEGF downregulation would modulate angiogenesis, which is of therapeutic benefit for almost all solid tumors. The physiological structure of both of these promoter G4s has been elucidated using plasmid DMS footprinting, which incorporates DNA supercoiling in addition to stabilizing cations or molecules. The current study examines a variety of anhydrous or crowding co-solvents for their ability to recapitulate the physiological structure in single-stranded ex vivo conditions. The co-solvents tested included glucose, acetonitrile, polyethylene glycol, dextran sulfate, sucrose, ficoll, and extracted nucleoplasm, ranging from 0-40%. Significant changes in structure, including loop directionality and number of competing isoforms, were examined by electronic circular dichroism. Electromobility shift assays differentiated inter- and intra-molecular structures, further distinguishing the distribution of isoforms. DMS footprinting with select molecular crowding and dehydrating agents was performed and compared to plasmid footprints, to validate physiological mimicry ex vivo. Ongoing studies examining the physiological conditions regulating G4 stability and function include moving from plasmid to in cell DMS footprinting in order to most completely identify the physiologic isoform, and to using optimized co-solvents to examine the effects of small molecules ex vivo and better predict active hits for in vitro evaluation. Overall the VEGF and MYC promoter G4 structures are promising therapeutic targets for anti-angiogenic and anti-proliferative therapy, respectively. This comprehensive understanding of physiological principles governing the above G4 formation will best inform future drug discovery efforts for these and other oncogenic promoters. Citation Format: Rhianna K. Morgan, Tracy A. Brooks. Physiological mimicry to characterize the average topology of the MYC and VEGF promoter G-quadruplexes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3092.

MYC overexpression occurs in up to 80% of all cancers. Down-regulating MYC's expression is an effective therapeutic strategy for the treatment of many of these cancers, and particularly for non-Hodgkin's lymphoma (NHL). NHL is the fifth most common cancer type, accounting for 5% of all cancers and 4% of all cancer deaths. Developing MYC-targeting therapeutics will be very impactful to NHL patients. In the current study, we have developed a nucleic acid clamp to transcriptionally down-regulate MYC expression by stabilizing the G-quadruplex (G4) formed in the nuclease hypersensitivity element III1 promoter region. The clamps complement nucleotides on the 5’- and 3’- regions flanking the G4-forming sequence, linked together with an 18 angstrom abasic moiety. To date, the binding affinity and specificity, G4 structure stabilizing ability, MYC down-regulation capability, and the selective cytotoxicity on cancerous vs non-cancerous cell lines of these clamps have been confirmed by EMSA and electronic circular dichroism, DMS footprinting, luciferase reporter assay, and MTS viability assay respectively. Recently, various replacements have been explored to replace the abasic moiety with non-complementary nucleic acids and to optimize the phosphate backbone with peptide nucleic acids. In addition, complexation with block co-polymers is under investigation to develop a functionalizable nanotherapeutic for NHL. The highly selective G4 stabilizing ability of the clamps used in the current approach offers an advantage over traditional G4 stabilizing small molecules. This novel approach is a promising therapeutic for the treatment of MYC related malignancies, and provides a framework for future G4-therapeutic development for other high-value genes, such as kRAS, VEGF, c-KIT and many more. Citation Format: Taisen Hao, Tracy Brooks. Transcription down-regulation of c-Myc through nucleic acid clamp-mediated stabilization of the promoter G-quadruplex. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4514.

This G-rich region of the c-MYC promoter has been shown to form a G-quadruplex structure that acts as a silencer element for c-MYC transcriptional control. In the present work, we have synthesized a series of 11-substituted quindoline analogues as c-MYC G-quadruplex-stabilizing compounds, and the cell-free and in vitro activity of these compounds were evaluated. Two lead compounds (4 and 12) demonstrated good cell-free profiles, and compound 4 (2-(4-(10H-indolo[3,2-b]quinolin-11-yl)piperazin-1-yl)-N,N-dimethylethanamine) significantly down-regulated c-MYC expression. However, despite the good cell-free activity and the effect of these compounds on c-MYC gene expression, we have demonstrated, using a cellular assay in a Burkitt's lymphoma cell line (CA46-specific), that these effects were not mediated through targeting of the c-MYC G-quadruplex. Thus, caution should be used in assigning the effects of G-quadruplex-interactive compounds that lower c-MYC to direct targeting of these promoter elements unless this assay, or similar ones, demonstrates direct targeting of the G-quadruplex in cells.

Most transcription of the MYC proto-oncogene initiates in the near upstream promoter, within which lies the nuclease hypersensitive element (NHE) III(1) region containing the CT-element. This dynamic stretch of DNA can form at least three different topologies: single-stranded DNA, double-stranded DNA, or higher order secondary structures that silence transcription. In the current report, we identify the ellipticine analog GQC-05 (NSC338258) as a high affinity, potent, and selective stabilizer of the MYC G-quadruplex (G4). In cells, GQC-05 induced cytotoxicity with corresponding decreased MYC mRNA and altered protein binding to the NHE III(1) region, in agreement with a G4 stabilizing compound. We further describe a unique feature of the Burkitt's lymphoma cell line CA46 that allowed us to clearly demonstrate the mechanism and location of action of GQC-05 within this region of DNA and through the G4. Most importantly, these data present, as far as we are aware, the most direct evidence of intracellular G4-mediated control of a particular promoter.

The presence and biological importance of DNA secondary structures in eukaryotic promoters are becoming increasingly recognized among chemists and biologists as bioinformatics in vitro and in vivo evidence for these structures in the c-Myc, c-Kit, KRAS, PDGF-A, hTERT, Rb, RET and Hif-1alpha promoters accumulates. Nevertheless, the evidence remains largely circumstantial. This minireview differs from previous ones in that here we examine the diversity of G-quadruplex and i-motif structures in promoter elements and attempt to categorize the different types of arrangements in which they are found. For the c-Myc G-quadruplex and Bcl-2 i-motif, we summarize recent biological and structural studies.

To understand the mechanisms controlling platelet-derived growth factor receptor beta (PDGFR-beta) expression in malignancies, we have cloned and characterized the first functional promoter of the human PDGFR-beta gene, which has been confirmed by luciferase reporter gene assays. The transcription initiation sites were mapped by primer extension. Promoter deletion experiments demonstrate that the proximal, highly GC-rich region (positions -165 to -139) of the human PDGFR-beta promoter is crucial for basal promoter activity. This region is sensitive to S1 nuclease and likely to assume a non-B-form DNA secondary structure within the supercoiled plasmid. The G-rich strand in this region contains a series of runs of three or more guanines that can form multiple different G-quadruplex structures, which have been subsequently assessed by circular dichroism. A Taq polymerase stop assay has shown that three different G-quadruplex-interactive drugs can each selectively stabilize different G-quadruplex structures of the human PDGFR-beta promoter. However, in transfection experiments, only telomestatin significantly reduced the human PDGFR-beta basal promoter activity relative to the control. Furthermore, the PDGFR-beta mRNA level in Daoy cells was significantly decreased after treatment with 1 muM telomestatin for 24 h. Therefore, we propose that ligand-mediated stabilization of specific G-quadruplex structures in the human PDGFR-beta promoter can modulate its transcription.

The microenvironment of the brain requires tight regulation for proper neuronal function. Protecting the central nervous system (CNS) from the varying concentrations of ions, proteins, and toxins in the periphery is the dynamically regulated blood-brain barrier (BBB). Recent studies have demonstrated significant modulation of the BBB in a number of diseases and physiological states, including pain. This study expands on previous explorations of acute and chronic pain-induced effects on the function and molecular cytoarchitecture of the barrier. It describes the role of cyclooxygenase (COX) up-regulation by blocking with diclofenac (30 mg/kg, i.p.), and it examines the variation in BBB regulation through various brain regions. Edema and hyperalgesia were induced by lambda-carrageenan and attenuated by the additional administration of diclofenac. Examination of unidirectional [14C]sucrose permeability with multitime in situ perfusion studies demonstrated that lambda-carrageenan significantly increased cerebral permeability and decreased brainstem permeability. There were no significant changes in any of the other brain regions examined. These permeability changes correlated with up- and down-regulation of the tight junction (TJ) protein claudin-5 in the cerebrum and brainstem, respectively. Diclofenac administration attenuated the cerebral permeability uptake as well as the claudin-5 up-regulation. In addition, diclofenac reversed the lowered permeability in the brainstem, but it did not attenuate TJ protein expression. These studies demonstrate the complex regulation of the BBB occurring during inflammatory pain and the role of COX in this process. An understanding of BBB regulation during pain states is critically important for pharmacotherapy, and it holds great promise for new therapies to treat central nervous system pathologies.

kRAS is a GTPase protein affecting normal cell proliferation, division, and apoptosis. It is mutated in >30% of all cancers, particularly in 60-90% of pancreatic cancers. Mutated kRAS leads to continuous activity and uncontrolled proliferation. To date there have been no successful clinical agents targeting mutant kRAS activity. Modulating kRAS expression has shown anti-proliferative promise as an approach in pancreatic cancer models, but is not a main avenue of pursuit for clinical development due to lack of a molecular target. Our lab is focused on the regulation of kRAS transcription through a variety of G-rich regions of DNA in the promoter capable of forming non-B-DNA structures termed G-quadruplexes (G4s). In the current study, we sought to determine the effect of the transcription factor MAZ on the regulation of kRAS, with a particular focus on the three putative G4-forming regions (herein termed near, mid, and far in reference to their relative proximity to the transcriptional start site). In a study of the kRAS promoter using a series of luciferase plasmids, MAZ expression led to a concentration-dependent decrease in promoter activity. This action was localized to interactions with the mid-G4-forming region. In the context of a more multifaceted intracellular mileu as found in the pancreatic cancer cell lines MiaPaCa-2, Panc-1, and BxPc3, the effects of MAZ were much more complex. In particular, 48 hr post-transfection with MAZ expression plasmids, monitoring of kRAS transcription revealed a cell line-specific modulation with an increase in kRAS expression in Panc-1 cells only, confirming a previous study, and no changes noted in either the MiaPaCa-2 or the Bx-Pc3 cells. Further studies are ongoing evaluating the direct binding of MAZ to the various G-rich regions in those cell lines, as well as determining the DNA structure (single-stranded, double-stranded, or G4-DNA) to which the MAZ protein is binding. Ultimately, an understanding of the regulation of this G-rich region of DNA, by MAZ or any other transcription factors such as Sp1 or p53, is an important part of the larger puzzle leading to a targeted drug discovery program focused on G4-regulation. Ultimately, G4-stabilization-mediated down regulation of kRAS has high potential for anti-cancer efficacy in pancreatic cancers, where there is a dire need for novel therapeutic development. Citation Format: Harshul Batra, Tracy A. Brooks. The effect of the transcription factor MAZ on kRAS transcription: a role for the G-quadruplex. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2137. doi:10.1158/1538-7445.AM2015-2137

CpG islands are prone to epigenetic cytosine modification via methylation (5mC) or 5-hydroxymethylation (5hmC). Although their potential sequences and regions for occurrence in G/C-rich DNA overlap, throughout the genome 5mC and 5hmC, and 5mC and G-quadruplex (G4) and i-motif (iM) structures, are found to not be co-existent. Moreover, in some regions of DNA, 5hmCs and G4/iM forming regions have high potential to form in concurrence. However, minimal research has been done examining the effect of 5hmC incorporation into G4 and iMs in order to determine the effect of cytosine modification on non-B-DNA structures. These higher order secondary DNA formations have been described within the VEGF promoter and have great potential to silence its transcription and prevent subsequent angiogenesis. In addition, there are three cytosines in the promoter on both the guanine- and the cytosine-rich strands found in CpG sequences that have the potential for 5mhC modification. Therefore, the current study was undertaken to examine the whether there is an effect of 5hmC incorporation into G4 loops and iM stems on structure formation and stabilization. Significant changes in structure or stability in buffers with varying pH’s, cationic strength, and molecular crowding conditions were examined by circular dichroism and confirmed by UV-monitored melting. Electromobility shift assays differentiated inter- and intra-molecular structures, further identifying the number of isoforms. Notable changes in G4 dynamics were seen with two of the three loop modifications, which decreased overall stability and increased intermolecular structures. Much less marked effects were discovered for the iM structures. Ongoing studies examining the role of G4 and iM 5hmC incorporation in regulation by endogenous proteins are part of a global effort to best understand the physiological conditions regulating G4 and iM stability and function. These VEGF promoter higher order structures are promising therapeutic targets for anti-angiogenic therapy, and a comprehensive understanding of the physiological principles governing their formation will best inform future drug discovery efforts. Brooks Lab startup funds, R15, University of Mississippi School of Pharmacy Citation Format: Rhianna Morgan, Randy Wadkins, Tracy Brooks. Effects of 5-hydroxymethylcytosine epigenetic modification on G-quadruplex and i-motif structure and stability within the VEGF promoter. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1050. doi:10.1158/1538-7445.AM2015-1050

Over 60% of pancreatic cancers harbor mutations in the kRAS oncogene, whose promoter has three distinct guanine-rich regions (near, mid, and far) capable of forming higher order G-quadruplexes (G4s). These important structures have transcriptional silencing potential and stabilizing compounds cause selective apoptosis in kRAS-addicted cells. Previous works in our laboratory have identified the mid-G4 region as having the highest silencing capacity, with little apparent roles for the near- or far-G4 regions. The structure of this mid-region G4 is being elucidated by electromobility shift assay, DNA polymerase stop assay, DMS footprinting, and circular dichroism (CD). In addition, small molecules are being screened by the Förster Resonance Energy Transfer (FRET) melt assay and confirmed by CD for their stabilization potential. We have identified multiple, equilibrating, intramolecular G4s forming within the mid-region of the kRAS promoter. Varying buffer conditions (cations, dehydration, and molecular crowding) affect these formations; the predominating isoform is a tetra-stacked mixed parallel and antiparallel structure with an 8:15:7 loop configuration. Over 1,600 compounds have been screened and several are being pursued as leads. Several compounds selectively stabilized the mid-G4 and suppress kRAS transcription. Our work highlights the mid-G4-forming region of the kRAS promoter a therapeutic target with the utmost promise for pancreatic cancer, and further features the stabilizing potential of targeted compounds. Studies are ongoing to vet the potential of other “hit” compounds from the FRET screen, as well as to elucidate the structure of the kRAS mid-G4 in chromosomal DNA. Brooks Lab startup funds, DoD, Rhianna Morgan GSC Grant, University of Mississippi School of Pharmacy Citation Format: Rhianna K. Morgan, Tracy A. Brooks, Khondaker M. Rahman. Structure elucidation of G-quadruplex within the mid-region of the kRAS promoter and identification of stabilizing small molecules as promising transcriptional silencers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5419. doi:10.1158/1538-7445.AM2015-5419