Synthesis and evaluation of 2,5-substituted pyrimidines as small-molecule gankyrin binders

Background: Gankyrin is an ankyrin-repeat protein that promotes cell proliferation, tumor development and cancer progression when overexpressed. Aim: To design and synthesize a novel series of gankyrin-binding small molecules predicated on a 2,5-pyrimidine scaffold. Materials & methods: The synthesized compounds were evaluated for their antiproliferative activity, ability to bind gankyrin and effects on cell cycle progression and the proteasomal degradation pathway. Results: Compounds 188 and 193 demonstrated the most potent antiproliferative activity against MCF7 and A549 cells, respectively. Both compounds also demonstrated the ability to effectively bind gankyrin, disrupt proteasomal degradation and inhibit cell cycle progression. Conclusion: The 2,5-pyrimidine scaffold exhibits a novel and promising strategy for binding gankyrin and inhibiting cancer cell proliferation.

Surface-Modified Inhaled Microparticle-Encapsulated Celastrol for Enhanced Efficacy in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer affecting the pleural lining of the lungs. Celastrol (Cela), a pentacyclic triterpenoid, has demonstrated promising therapeutic potential as an antioxidant, anti-inflammatory, neuroprotective agent, and anti-cancer agent. In this study, we developed inhaled surface-modified Cela-loaded poly(lactic-co-glycolic) acid (PLGA) microparticles (Cela MPs) for the treatment of MPM using a double emulsion solvent evaporation method. The optimized Cela MPs exhibited high entrapment efficiency (72.8 ± 6.1%) and possessed a wrinkled surface with a mean geometric diameter of ~2 µm and an aerodynamic diameter of 4.5 ± 0.1 µm, suggesting them to be suitable for pulmonary delivery. A subsequent release study showed an initial burst release up to 59.9 ± 2.9%, followed by sustained release. The therapeutic efficacy of Cela MPs was evaluated against four mesothelioma cell lines, where Cela MP exhibited significant reduction in IC50 values, and blank MPs produced no toxicity to normal cells. Additionally, a 3D-spheroid study was performed where a single dose of Cela MP at 1.0 µM significantly inhibited spheroid growth. Cela MP was also able to retain the antioxidant activity of Cela only while mechanistic studies revealed triggered autophagy and an induction of apoptosis. Therefore, these studies highlight the anti-mesothelioma activity of Cela and demonstrate that Cela MPs are a promising inhalable medicine for MPM treatment.

Solubility Enhancement and Inhalation Delivery of Cyclodextrin-Based Inclusion Complex of Delamanid for Pulmonary Tuberculosis Treatment

Tuberculosis (TB) is a contiguous airborne disease caused by Mycobacterium tuberculosis (M.tb), primarily affecting the human lungs. The progression of drug-susceptible TB to drug-resistant strains, MDR-TB and XDR-TB, has become a global challenge toward eradicating TB. Conventional TB treatment involves frequent dosing and prolonged treatment regimens predominantly by an oral or invasive route, leading to treatment-related systemic adverse effects and patient's noncompliance. Pulmonary delivery is an attractive option as we could reduce dose, limit systemic side-effects, and achieve rapid onset of action. Delamanid (DLD), an antituberculosis drug, has poor aqueous solubility, and in this study, we aim to improve its solubility using cyclodextrin complexation. We screened different cyclodextrins and found that HP-β-CD resulted in a 54-fold increase in solubility compared to a 27-fold and 13-fold increase by SBE-β-CD and HP-ɣ-CD, respectively. The stability constant (265 ± 15 M^-1) and complexation efficiency (8.5 × 10^-4) suggest the formation of a stable inclusion complex of DLD and HP-β-CD in a 2:1 ratio. Solid-state characterization studies (DSC, PXRD, and NMR) further confirmed successful complexation of DLD in HP-β-CD. The nebulized DLD-CD complex solution showed a mass median aerodynamic diameter of 4.42 ± 0.62 μm and fine particle fraction of 82.28 ± 2.79%, suggesting deposition in the respiratory airways. In bacterial studies, minimum inhibitory concentration of DLD-CD complex was significantly reduced (four-fold) compared to free DLD in M.tb (H37Ra strain). Furthermore, accelerated stability studies confirmed that the inclusion complex was stable for 4 weeks with 90%w/w drug content. In conclusion, we increased the aqueous solubility of DLD through cyclodextrin complexation and improved its efficacy in vitro.

Repurposing an Antiepileptic Drug for the Treatment of Glioblastoma

PURPOSE

Glioblastoma multiforme (GBM) is a grade IV, highly proliferative, and malignant form of brain tumor with a 5-year survival rate at ~ 5%. Current treatment strategies for GBM include surgery, radiation, and chemotherapy. Major challenges in GBM management include difficulties in surgical resection due to brain's vital functions and GBM metastasis, development of resistance to temozolomide (TMZ), and protection of tumor by blood brain barrier (BBB). Therefore, we aimed to discover a novel therapeutic for GBM by targeting its metabolic reprogramming.

METHOD

We screened metabolic inhibitors by their effects on GBM cell viability by MTT assay. We discovered an FDA-approved drug stiripentol (STP) in our screening of metabolic inhibitors in GBM cells. STP is used for Dravet syndrome (a rare epilepsy). We further tested efficacy of STP using proliferation assay, clonogenic assay, in vitro migration assay, cell cycle assay, apoptosis assay, and in U87 3D spheroids. We also tested the toxicity of STP, and combinations used in the study on normal human dermal fibroblasts.

RESULTS

STP was effective in decreasing GBM cell viability, proliferation, clonogenic ability, and migration. Moreover, cell cycle changes were involved but robust apoptosis was absent in STP's anticancer effects. STP was effective in 3D spheroid models, and in TMZ-resistant cells. STP showed additive or synergistic effect with TMZ in different anticancer assays on GBM cells and was considerably less toxic in normal cells.

CONCLUSION

Our results indicate that STP can be an effective GBM therapeutic that enhances the effects of TMZ on GBM cells. Importantly, STP reduced viability of TMZ-resistant cells. Our results warrant further studies in the mechanistic basis of STP's effects on GBM cells and the preclinical potential of STP in animal models.

Small-Molecule Gankyrin Inhibition as a Therapeutic Strategy for Breast and Lung Cancer

Gankyrin is an oncoprotein responsible for the development of numerous cancer types. It regulates the expression levels of multiple tumor suppressor proteins (TSPs) in liver cancer; however, gankyrin's regulation of these TSPs in breast and lung cancers has not been thoroughly investigated. Additionally, no small-molecule gankyrin inhibitor has been developed which demonstrates potent anti-proliferative activity against gankyrin overexpressing breast and lung cancers. Herein, we are reporting the structure-based design of gankyrin-binding small molecules which potently inhibited the proliferation of gankyrin overexpressing A549 and MDA-MB-231 cancer cells, reduced colony formation, and inhibited the growth of 3D spheroids in an in vitro tumor simulation model. Investigations demonstrated that gankyrin inhibition occurs through either stabilization or destabilization of its 3D structure. These studies shed light on the mechanism of small-molecule inhibition of gankyrin and demonstrate that gankyrin is a viable therapeutic target for the treatment of breast and lung cancer.

BX-795 inhibits neuroblastoma growth and enhances sensitivity towards chemotherapy

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AKT overexpression correlates with poor prognosis in neuroblastoma patients.

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BX-795 inhibits PDK1 and abrogates the AKT signaling pathway activation.

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BX-795 demonstrates strong efficacy in neuroblastoma spheroid tumor model.

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Combination with BX-795 synergistically enhances doxorubicin antitumor activity.

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BX-795 synergistically sensitized ALK mutated neuroblastoma cell lines to crizotinib.

High-risk neuroblastoma (NB) represents a major clinical challenge in pediatric oncology due to relapse of metastatic, drug-resistant disease, and treatment-related toxicities. An analysis of 1235 primary NB patient dataset revealed significant increase in AKT1 and AKT2 gene expression with cancer stage progression. Additionally, Both AKT1 and AKT2 expression inversely correlate with poor overall survival of NB patients. AKT1 and AKT2 genes code for AKT that drive a major oncogenic cell signaling pathway known in many cancers, including NB. To inhibit AKT pathway, we repurposed an antiviral inhibitor BX-795 that inhibits PDK1, an upstream activator of AKT. BX-795 potently inhibits NB cell proliferation and colony growth in a dose-dependent manner. BX-795 significantly enhances apoptosis and blocks cell cycle progression at mitosis phase in NB. Additionally, BX-795 potently inhibits tumor formation and growth in a NB spheroid tumor model. We further tested dual therapeutic approaches by combining BX-795 with either doxorubicin or crizotinib and found synergistic and significant inhibition of NB growth, in contrast to either drug alone. Overall, our data demonstrate that BX-795 inhibits AKT pathway to inhibit NB growth, and combining BX-795 with current therapies is an effective and clinically tractable therapeutic approach for NB.

Bioinspired particle engineering for non-invasive inhaled drug delivery to the lungs

Pulmonary drug delivery is governed by several biophysical parameters of delivery carriers, such as particle size, shape, density, charge, and surface modifications. Although much attention has been given to other parameters, particle shape effects have rarely been explored. In this work, we assess the influence of particle shape of inhaled delivery carriers on their aerodynamic properties and macrophage uptake by using polymeric microparticles of different geometries ranging in various sizes. Doxorubicin was conjugated to the polymer particles and the bioconjugates were characterized. Interestingly, the results of in-vitro lung deposition, performed using a next generation impactor, demonstrated a significant improvement in the aerodynamic properties of the rod-shaped particles with a high aspect ratio as compared to spherical particles with the same equivalent volume. The results of a macrophage uptake experiment demonstrate that the high aspect ratio particles were phagocytosed less than spherical particles. Furthermore, the cytotoxicity of these doxorubicin-conjugated particles was determined against murine macrophages, resulting in reduced toxicity when treated with high aspect ratio particles as compared to spherical particles. This project provides valuable insights into the influence of particle shape on aerodynamic properties and primary defense mechanisms in the peripheral lungs, while using polymeric microparticles of various sizes and geometries. Further systematic development can help translate these findings to preclinical and clinical studies for designing efficient inhalable delivery carriers.

Inhalable resveratrol-cyclodextrin complex loaded biodegradable nanoparticles for enhanced efficacy against non-small cell lung cancer

Resveratrol (RES), a natural polyphenol in fruits, has shown promising anti-cancer properties. Due to its relative low toxicity which limits the adverse effects observed for conventional chemotherapeutics, RES has been proposed as an alternative. However, the therapeutic applications of RES have been limited due to low water solubility, as well as chemical and physical instability. This study investigated enhancing the anti-cancer activity of RES against non-small-cell-lung-cancer (NSCLC) by complexing with sulfobutylether-β-cyclodextrin (CD-RES) and loading onto polymeric nanoparticles (NPs). The physicochemical properties of the CD-RES NPs were then characterized. The CD-RES inclusion complex increased the water solubility of RES by ~66-fold. CD-RES NPs demonstrated very good aerosolization potential with a mass median aerodynamic diameter of 2.20 μm. Cell-based studies demonstrated improved therapeutic efficacy of CD-RES NPs compared to RES. This included enhanced cellular uptake, cytotoxicity, and apoptosis, while retaining antioxidant activity. The 3D spheroid study indicated an intensified anti-cancer effect of CD-RES NPs. Altogether, these findings marked CD-RES NPs as a potential inhalable delivery system of RES for the treatment NSCLC.

Cyclodextrin Complexation for Enhanced Stability and Non-invasive Pulmonary Delivery of Resveratrol-Applications in Non-small Cell Lung Cancer Treatment

Pulmonary drug delivery is a noninvasive therapeutic approach that offers many advantages including localized drug delivery and higher patient compliance. As with all formulations, the low aqueous solubility of a drug often poses a challenge in the formulation development. Thus, strategies such as cyclodextrin (CD) complexation have been utilized to overcome this challenge. Resveratrol (RES), a natural stilbene, has shown abundant anti-cancer properties. Due to many drawbacks of conventional chemotherapeutics, RES has been proposed as an emerging alternative with promising pharmacological effects. However, RES has limited therapeutic applications due to low water solubility, chemical stability, and bioavailability. This study was aimed at developing an inhalable therapy that would increase the aqueous solubility and stability of RES by complexation with sulfobutylether-β-cyclodextrin (SBECD). Phase solubility profiles indicated an optimal stoichiometric inclusion complex at 1:1 (SBECD:RES) ratio for formulation considerations. Physiochemical characterizations were performed to analyze CD-RES. Stability studies at pH 7.4 and in plasma indicated significant improvement in RES stability after complexation, with a much longer half-life. The mass median aerodynamic diameter (MMAD) of CD-RES was 2.6 ± 0.7 μm and fine particle fraction (FPF) of 83.4 ± 3.0% are suitable for pulmonary delivery and efficient deposition. Lung cancer was selected as the respiratory model disease, owing to its high relevance as the major cause of cancer deaths worldwide. Cell viability studies in 5 non-small-cell-lung-cancer (NSCLC) cell lines suggest CD-RES retained significant cytotoxic potential of RES. Taken together, CD-RES proves to be a promising inhalation treatment for NSCLC.

Optimizing the aryl-triazole of cjoc42 for enhanced gankyrin binding and anti-cancer activity

Gankyrin is an oncoprotein overexpressed in numerous cancer types and appears to play a key role in regulating cell proliferation, cell growth, and cell migration. These roles are largely due to gankyrin's protein-protein interaction with the 26S proteasome. We previously published a study exploring the aryl sulfonate ester of cjoc42 in an effort to enhance gankyrin binding and inhibit cancer cell proliferation. In order to further improve the gankyrin binding ability of the cjoc42 scaffold, an extensive SAR for the aryl-triazole moiety of cjoc42 was developed. Our cjoc42 derivatives exhibited enhanced gankyrin binding, as well as enhanced antiproliferative activity against Hep3B, HepG2, A549, and MDA-MB-231 cancer cell lines.

Development of pharmaceutically scalable inhaled anti-cancer nanotherapy - Repurposing amodiaquine for non-small cell lung cancer (NSCLC)

New drug and dosage form development faces significant challenges, especially in oncology, due to longer development cycle and associated scale-up complexities. Repurposing of existing drugs with potential anti-cancer activity into new therapeutic regimens provides a feasible alternative. In this project, amodiaquine (AQ), an anti-malarial drug, has been explored for its anti-cancer efficacy through formulating inhalable nanoparticulate systems using high-pressure homogenization (HPH) with scale-up feasibility and high reproducibility. A 3² multifactorial design was employed to better understand critical processes (probe homogenization speed while formulating coarse emulsion) and formulation parameters (concentration of cationic polymer in external aqueous phase) so as to ensure product quality with improved anticancer efficacy in non-small cell lung cancer (NSCLC). Optimized AQ loaded nanoparticles (AQ NP) were evaluated for physicochemical properties, stability profile, in-vitro aerosol deposition behavior, cytotoxic potential against NSCLC cells in-vitro and in 3D simulated tumor spheroid model. The highest probe homogenization speed (25,000 rpm) resulted in lower particle size. Incorporation of cationic polymer, polyethylenimine (0.5% w/v) resulted in high drug loading efficiencies at optimal drug quantity of 5 mg. Formulated nanoparticles (liquid state) exhibited an aerodynamic diameter of 4.7 ± 0.1 μm and fine particle fraction of 81.0 ± 9.1%, indicating drug deposition in the respirable airways. Cytotoxicity studies in different NSCLC cell lines revealed significant reduction in IC₅₀ values with AQ-loaded nanoparticles compared to plain drug, along with significant cell migration inhibition (scratch assay) and reduced % colony growth (clonogenic assay) in A549 cells with AQ NP. Moreover, 3D simulated spheroid studies revealed efficacy of nanoparticles in penetration to tumor core, and growth inhibition. AQ's autophagy inhibition ability significantly increased (increased LC3B-II levels) with nanoparticle encapsulation, along with moderate improvement in apoptosis induction (Caspase-3 levels). No impact was observed on HUVEC angiogenesis suggesting alternative anticancer mechanisms. To conclude, amodiaquine can be a promising candidate for repurposing to treat NSCLC while delivering inhalable nanoparticles developed using a scalable HPH process. Despite the involvement of complex parameters, application of DoE has simplified the process of product and process optimization.

Sorafenib Loaded Inhalable Polymeric Nanocarriers against Non-Small Cell Lung Cancer

PURPOSE

This exploration is aimed at developing sorafenib (SF)-loaded cationically-modified polymeric nanoparticles (NPs) as inhalable carriers for improving the therapeutic efficacy of SF against non-small cell lung cancer (NSCLC).

METHODS

The NPs were prepared using a solvent evaporation technique while incorporating cationic agents. The optimized NPs were characterized by various physicochemical parameters and evaluated for their aerosolization properties. Several in-vitro evaluation studies were performed to determine the efficacy of our delivery carriers against NSCLC cells.

RESULTS

Optimized nanoparticles exhibited an entrapment efficiency of ~40%, <200 nm particle size and a narrow poly-dispersity index. Cationically-modified nanoparticles exhibited enhanced cellular internalization and cytotoxicity (~5-fold IC₅₀ reduction vs SF) in various lung cancer cell types. The inhalable nanoparticles displayed efficient aerodynamic properties (MMAD ~ 4 μM and FPF >80%). In-vitro evaluation also resulted in a superior ability to inhibit cancer metastasis. 3D-tumor simulation studies further established the anti-cancer efficacy of NPs as compared to just SF.

CONCLUSION

The localized delivery of SF-loaded nanoparticles resulted in improved anti-tumor activity as compared to SF alone. Therefore, this strategy displays great potential as a novel treatment approach against certain lung cancers.

Metformin-Encapsulated Liposome Delivery System: An Effective Treatment Approach against Breast Cancer

This study aimed at developing metformin hydrochloride (Met) encapsulated liposomal vesicles for enhanced therapeutic outcomes at reduced doses against breast cancer. Liposomal Met was prepared using thin-film hydration through various loading methods; passive loading, active loading, and drug-loaded lipid film. The drug-loaded film method exhibited maximum entrapment efficiency (~65%) as compared to active loading (~25%) and passive loading (~5%) prepared Met-loaded liposomes. The therapeutic efficacy of these optimized liposomes was evaluated for cellular uptake, cytotoxicity, inhibition of metastatic activity, and apoptosis-inducing activity. Results demonstrated significantly superior activity of positively charged liposomes resulting in reduced IC₅₀ values, minimal cell migration activity, reduced colony formation, and profound apoptosis-induced activity in breast cancer cells as compared to Met. The anti-tumor activity was investigated using a clinically relevant in vitro tumor simulation model, which confirmed enhanced anti-tumorigenic property of liposomal Met over Met itself. To the authors’ knowledge, this is the first report of Met-loaded liposomes for improving the efficacy and therapeutic effect of Met against breast cancer. With the results obtained, it can be speculated that liposomal encapsulation of metformin offers a potentially promising and convenient approach for enhanced efficacy and bioavailability in breast cancer treatment.

Abstract 23: Small molecule targeting of gankyrin reduces cell migration and proliferation in certain cancers

Introduction: Gankyrin is an oncoprotein involved in regulating numerous pathways important to cell growth, signaling, proliferation and death. The overexpression of gankyrin and subsequent increased protein-protein interactions have been identified as key to increased proliferation in a variety of cancers. Consequently, small molecules that bind to and disrupt these protein-protein interactions are promising therapeutic strategies for the treatment of certain cancers. The first small molecule binder of gankyrin, cjoc42, was recently developed and exhibited efficacy in inhibiting the gankyrin-26S proteasome interaction. The aim of this work is to determine the effects of cjoc42 and its derivatives on cell migration and proliferation in gankyrin-overexpressing cancers.

Methods: Wound healing and CyQuant proliferation assays were used to determine the ability of cjoc42 to inhibit migration and proliferation in the gankyrin-overexpressing cell lines A549, MDA-MB231 and Huh6 cells. A protein thermal shift assay was used to screen new cjoc42 derivatives for their ability to bind gankyrin. Western blot experiments will determine if binding of cjoc42 and its derivatives to gankyrin is the mechanism of action in cells.

Results: Cjoc42 demonstrated an ability to inhibit the migratory and proliferative activity of A549 and MDA-MB231 cells. While only a modest inhibition of migration was observed, cjoc42 exhibited a significant antiproliferative effect against these cell lines. Utilization of a protein thermal shift assay yielded cjoc42 derivatives with more potent gankyrin-binding ability. These compounds will be evaluated in-cellulo for their ability to inhibit cell migration and proliferation. Western blot experiments will confirm that gankyrin-binding of cjoc42 attributes to the anti-migration and anti-proliferative effects observed.

Conclusions: These studies show that cjoc42 directly inhibits cell migration and proliferation by inhibiting the interaction between gankyrin and the 26S proteasome. Consequently, this work provides background for the development of small molecule inhibitors as a gankyrin-mediated therapy for the treatment of lung, breast and liver cancers.

Citation Format: Pamela Farrales, Aaron Muth. Small molecule targeting of gankyrin reduces cell migration and proliferation in certain cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 23.

Abstract 1311: Inhibition of gankyrin-tumor suppressor protein interactions due to small molecule induced conformational change

Introduction: Gankyrin is a highly conserved, 25 kDa protein containing 7 ankyrin repeats that binds to the S6 ATPase subunit of the 26S proteasome. It plays a crucial role in cellular growth, proliferation and metastasis. It is found to be largely overexpressed in a variety of malignancies and its abnormal overexpression makes it a biomarker in certain cancers. Gankyrin promotes cellular growth and proliferation through a variety of protein-protein interactions. Specifically, it binds to and promotes degradation of numerous tumor suppressor proteins (TSPs) such as p53 and retinoblastoma protein by promoting their proteasomal degradation. In 2016, a small molecule binder of gankyrin (cjoc42), demonstrated an ability to inhibit gankyrin activity in a dose dependent manner by inhibiting gankyrin’s interaction with certain TSPs as well as the proteasome.

Methods: In this research, we hypothesize that small molecule binding of gankyrin brings about a conformational change that inhibits its interaction with certain TSPs as well as the proteasome. In order to test this hypothesis, we have performed a series of fluorescence based experiments. We investigated the effect cjoc42 binding to gankyrin has on its intrinsic tryptophan fluorescence as well as its effect on fluorescently conjugated gankyrin. Follow up experiments consisted of both simple western blotting and co-immunoprecipitation assays to further investigate the ability of cjoc42 to induce a conformational change in gankyrin.

Discussion: We observed a diminished fluorescence intensity for both the intrinsic and labeled gankyrin experiments when in the presence of cjoc42. Western blot and Co-IP experiments are currently underway to further support our findings.

Conclusion: Cjoc42, a small molecule binder of gankyrin, appears to induce a conformational change. This conformational change appears to play a prominent role in regulating certain protein-protein interactions. Furthermore, this suggests that gankyrin's binding to specific TSPs and the proteasome are modulated by this mechanism.

Citation Format: Abbas Kabir, Aaron Muth. Inhibition of gankyrin-tumor suppressor protein interactions due to small molecule induced conformational change [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1311.

Drug repurposing: a promising tool to accelerate the drug discovery process

Traditional drug discovery and development involves several stages for the discovery of a new drug and to obtain marketing approval. It is necessary to discover new strategies for reducing the drug discovery time frame. Today, drug repurposing has gained importance in identifying new therapeutic uses for already-available drugs. Typically, repurposing can be achieved serendipitously (unintentional fortunate observations) or through systematic approaches. Numerous strategies to discover new indications for FDA-approved drugs are discussed in this article. Drug repurposing has therefore become a productive approach for drug discovery because it provides a novel way to explore old drugs for new use but encounters several challenges. Some examples of different approaches are reviewed here.

Genetic testing and surveillance guidelines in hereditary pheochromocytoma and paraganglioma

Pheochromocytoma and paraganglioma (PPGL) are rare tumours and at least 30% are part of hereditary syndromes. Approximately 20% of hereditary PPGL are caused by pathogenic germ line variants in genes of the succinate dehydrogenase complex (SDHx), TMEM127 or MAX. Herein we present guidelines regarding genetic testing of family members and their surveillance based on a thorough literature review. All cases of PPGL are recommended genetic testing for germ line variants regardless of patient and family characteristics. At minimum, FH, NF1, RET, SDHB, SDHD and VHL should be tested. In addition, testing of MEN1, SDHA, SDHAF2, SDHC, TMEM127 and MAX is recommended. Healthy first-degree relatives (and second-degree relatives in the case of SDHD and SDHAF2 which are maternally imprinted) should be offered carrier testing. Carriers of pathogenic variants should be offered surveillance with annual biochemical measurements of methoxy-catecholamines and bi-annual rapid whole-body magnetic resonance imaging and clinical examination. Surveillance should start 5 years before the earliest age of onset in the family and thus only children eligible for surveillance should be offered pre-symptomatic genetic testing. The surveillance of children younger than 15 years needs to be individually designed. Our guidelines will provide a framework for patient management with the possibility to follow outcome via national registries and/or follow-up studies. Together with improved insights into the disease, this may enable optimisation of the surveillance scheme in order to minimise both anxiety and medical complications while ensuring early disease detection.

Colorectal cancer liver metastatic growth depends on PAD4-driven citrullination of the extracellular matrix

Citrullination of proteins, a post-translational conversion of arginine residues to citrulline, is recognized in rheumatoid arthritis, but largely undocumented in cancer. Here we show that citrullination of the extracellular matrix by cancer cell derived peptidylarginine deiminase 4 (PAD4) is essential for the growth of liver metastases from colorectal cancer (CRC). Using proteomics, we demonstrate that liver metastases exhibit higher levels of citrullination and PAD4 than unaffected liver, primary CRC or adjacent colonic mucosa. Functional significance for citrullination in metastatic growth is evident in murine models where inhibition of citrullination substantially reduces liver metastatic burden. Additionally, citrullination of a key matrix component collagen type I promotes greater adhesion and decreased migration of CRC cells along with increased expression of characteristic epithelial markers, suggesting a role for citrullination in promoting mesenchymal-to-epithelial transition and liver metastasis. Overall, our study reveals the potential for PAD4-dependant citrullination to drive the progression of CRC liver metastasis.

Cyclodextrin modified erlotinib loaded PLGA nanoparticles for improved therapeutic efficacy against non-small cell lung cancer

This study was aimed at developing a nanoparticle strategy to overcome acquired resistance against erlotinib in non-small cell lung cancer (NSCLC). To load erlotinib on biodegradable PLGA nanoparticles, erlotinib-cyclodextrin (Erlo-CD) complex was prepared using β-cyclodextrin sulfobutyl ether, which was in turn loaded in the core of PLGA nanoparticles using multiple emulsion solvent evaporation. Nanoparticles were characterized for size distribution, entrapment and loading efficiency, in-vitro release, and therapeutic efficacy against different lung cancer cells. Effect of formulation on cell cycle, apoptosis, and other markers was evaluated using flow cytometry and western blotting studies. The efficacy of optimized nanoformulation was evaluated using a clinically relevant in-vitro 3D-spheroid model. Results showed that Erlo-CD loaded nanoparticles (210 ± 8 nm in size) demonstrated 3-fold higher entrapment (61.5 ± 3.2% vs 21.9 ± 3.7% of plain erlotinib loaded nanoparticles) with ~5% loading efficiency and sustained release characteristics. Developed nanoparticles demonstrated significantly improved therapeutic efficacy against NSCLC cells in terms of low IC50 values and suppressed colony forming ability of cancer cells, increased apoptosis, and autophagy inhibition. Interestingly, 3D spheroid study demonstrated better anticancer activity of Erlo-CD nanoparticles compared to plain erlotinib. Present study has shown a premise to improve therapeutic efficacy against erlotinib-resistant lung cancer using modified nanoErlo formulations.

Nintedanib-cyclodextrin complex to improve bio-activity and intestinal permeability

Cyclodextrin complex of nintedanib was prepared aiming for increased bio-activity and improved transport across intestinal membrane with reduced p-glycoprotein (p-gp) efflux. Based on preliminary phase solubility studies and molecular modeling, sulfobutyl ether derivative of β-cyclodextrin (SBE-β-CD, Captisol^®) was selected to prepare inclusion complex. Complexation was confirmed using FTIR, 1H NMR, DSC, and XRD. Bioactivity of the formed complex was tested using lung fibroblast cells, WI-38 for anti-proliferative activity and effect on collagen deposition and cells migration. In-vitro permeability studies were performed using epiIntestinal tissue model to assess the effect of complexation on transport and p-gp efflux. Results of the study demonstrated that cyclodextrin complexation increased stability of nintedanib in PBS (pH 7.4) and simulated intestinal fluid (SIF). Further, bioactivity of nintedanib also improved. Interestingly, complexation has increased transport of nintedanib across intestinal membrane and reduced efflux ratio, suggesting the role of cyclodextrin complexation in modulating p-gp efflux.

BB-Cl-Amidine as a novel therapeutic for canine and feline mammary cancer via activation of the endoplasmic reticulum stress pathway

Background

Mammary cancer is highly prevalent in dogs and cats and results in a poor prognosis due to critically lacking viable treatment options. Recent human and mouse studies have suggested that inhibiting peptidyl arginine deiminase enzymes (PAD) may be a novel breast cancer therapy. Based on the similarities between human breast cancer and mammary cancer in dogs and cats, we hypothesized that PAD inhibitors would also be an effective treatment for mammary cancer in these animals.

Methods

Canine and feline mammary cancer cell lines were treated with BB-Cl-Amidine (BB-CLA) and evaluated for viability and tumorigenicity. Endoplasmic reticulum stress was tested by western blot, immunofluorescence, and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Canine and feline mammary cancer xenograft models were created using NOD scid gamma (NSG) mice, and were treated with BB-CLA for two weeks.

Results

We found that BB-CLA reduced viability and tumorigenicity of canine and feline mammary cancer cell lines in vitro. Additionally, we demonstrated that BB-CLA activates the endoplasmic reticulum stress pathway in these cells by downregulating 78 kDa Glucose-regulated Protein (GRP78), a potential target in breast cancer for molecular therapy, and upregulating the downstream target gene DNA Damage Inducible Transcript 3 (DDIT3). Finally, we established a mouse xenograft model of both canine and feline mammary cancer in which we preliminarily tested the effects of BB-CLA in vivo.

Conclusion

We propose that our established mouse xenograft models will be useful for the study of mammary cancer in dogs and cats, and furthermore, that BB-CLA has potential as a novel therapeutic for mammary cancer in these species.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4323-8) contains supplementary material, which is available to authorized users.

The Development of Benzimidazole-Based Clickable Probes for the Efficient Labeling of Cellular Protein Arginine Deiminases (PADs)

Citrullination is the post-translational hydrolysis of peptidyl-arginines to form peptidyl-citrulline, a reaction that is catalyzed by the protein arginine deiminases (PADs), a family of calcium-regulated enzymes. Aberrantly increased protein citrullination is associated with a slew of autoimmune diseases (e.g., rheumatoid arthritis (RA), multiple sclerosis, lupus, and ulcerative colitis) and certain cancers. Given the clear link between increased PAD activity and human disease, the PADs are therapeutically relevant targets. Herein, we report the development of next generation cell permeable and "clickable" probes (BB-Cl-Yne and BB-F-Yne) for covalent labeling of the PADs both in vitro and in cell-based systems. Using advanced chemoproteomic technologies, we also report the off targets of both BB-Cl-Yne and BB-F-Yne. The probes are highly specific for the PADs, with relatively few off targets, especially BB-F-Yne, suggesting the preferential use of the fluoroacetamidine warhead in next generation irreversible PAD inhibitors. Notably, these compounds can be used in a variety of modalities, including the identification of off targets of the parent compounds and as activity-based protein profiling probes in target engagement assays to demonstrate the efficacy of PAD inhibitors.

PAD1 promotes epithelial-mesenchymal transition and metastasis in triple-negative breast cancer cells by regulating MEK1-ERK1/2-MMP2 signaling

Peptidylargininedeiminase 1 (PAD1) catalyzes protein for citrullination, and this activity has been linked to the epidermal cornification. However, a role for PAD1 in tumorigenesis, including breast cancers has not been previously explored. Here we first showed that PAD1 is overexpressed in human triple negative breast cancer (TNBC). In cultured cells and xenograft mouse models, PAD1 depletion or inhibition reduced cell proliferation, suppressed epithelial-mesenchymal transition, and prevented metastasis of MDA-MB-231 cells. These changes were correlated with a dramatic decrease in MMP2/9 expression. Furthermore, ERK1/2 and P38 MAPK signaling pathways are activated upon PAD1 silencing. Treatment with MEK1/2 inhibitor in PAD1 knockdown cells significantly recovered MMP2 expression, while inhibiting P38 activation only slightly elevated MMP9 levels. We then showed that PAD1 interacts with and citrullinates MEK1 thereby disrupting MEK1-catalyzed ERK1/2 phosphorylation, thus leading to the MMP2 overexpression. Collectively, our data indicate that PAD1 appears to promote tumorigenesis by regulating MEK1-ERK1/2-MMP2 signaling in TNBC. These results also raise the possibility that PAD1 may function as an important new biomarker for TNBC tumors and suggest that PAD1-specific inhibitors could potentially be utilized to treat metastatic breast cancer.

Citrullination of NF-κB p65 promotes its nuclear localization and TLR-induced expression of IL-1β and TNFα

Many citrullinated proteins are known autoantigens in rheumatoid arthritis, a disease mediated by inflammatory cytokines, such as tumor necrosis factor-α (TNFα). Citrullinated proteins are generated by converting peptidylarginine to peptidylcitrulline, a process catalyzed by the peptidylarginine deiminases (PADs), including PAD1 to PAD4 and PAD6. Several major risk factors for rheumatoid arthritis are associated with heightened citrullination. However, the physiological role of citrullination in immune cells is poorly understood. We report that suppression of PAD activity attenuates Toll-like receptor-induced expression of interleukin-1β (IL-1β) and TNFα by neutrophils in vivo and in vitro but not their global transcription activity. Mechanistically, PAD4 directly citrullinates nuclear factor κB (NF-κB) p65 and enhances the interaction of p65 with importin α3, which brings p65 into the nucleus. The citrullination-enhanced interaction of p65 with importin α3 and its nuclear translocation and transcriptional activity can be attributed to citrullination of four arginine residues located in the Rel homology domain of p65. Furthermore, a rheumatoid arthritis-prone variant of PAD4, carrying three missense mutations, is more efficient in interacting with p65 and enhancing NF-κB activity. Together, these data not only demonstrate a critical role of citrullination in an NF-κB-dependent expression of IL-1β and TNFα but also provide a molecular mechanism by which heightened citrullination propagates inflammation in rheumatoid arthritis. Accordingly, attenuating p65-mediated production of IL-1β and TNFα by blocking the citrullination of p65 has great therapeutic potential in rheumatoid arthritis.

Diverse stimuli engage different neutrophil extracellular trap pathways

Neutrophils release neutrophil extracellular traps (NETs) which ensnare pathogens and have pathogenic functions in diverse diseases. We examined the NETosis pathways induced by five stimuli; PMA, the calcium ionophore A23187, nigericin, Candida albicans and Group B Streptococcus. We studied NET production in neutrophils from healthy donors with inhibitors of molecules crucial to PMA-induced NETs including protein kinase C, calcium, reactive oxygen species, the enzymes myeloperoxidase (MPO) and neutrophil elastase. Additionally, neutrophils from chronic granulomatous disease patients, carrying mutations in the NADPH oxidase complex or a MPO-deficient patient were examined. We show that PMA, C. albicans and GBS use a related pathway for NET induction, whereas ionophores require an alternative pathway but that NETs produced by all stimuli are proteolytically active, kill bacteria and composed mainly of chromosomal DNA. Thus, we demonstrate that NETosis occurs through several signalling mechanisms, suggesting that extrusion of NETs is important in host defence.

DOI:http://dx.doi.org/10.7554/eLife.24437.001

The immune system protects the body against microorganisms that can cause infections and diseases. Neutrophils are a type of immune cell that patrol the blood in search of germs. Once they encounter potentially harmful microbes, neutrophils eradicate them in different ways. One way to catch the germs is by using ‘neutrophil extracellular traps’, or NETs for short, to confine and kill the invaders.

NETs are web-like structures made up of anti-microbial proteins and the neutrophil’s own DNA. The process of making NETs kills the neutrophil, as it eventually explodes to release the NETs. NETs play a key role in disease prevention, but producing too many NETs or producing them at the wrong time or in the wrong place can actually make certain diseases worse. Therefore, it is important to fully understand the signaling pathways and molecules the neutrophils use to make NETs.

Kenny et al. exposed neutrophils from healthy people to five different compounds known to cause the cells to make NETs, including some harmful molecules, a fungus and a bacterium. Microscopy was then used to count how many neutrophils made NETs in response to each of the five stimuli. Further experiments showed that neutrophils from patients with an immune system disorder produced fewer NETs when stimulated with some of the compounds, while the other stimuli caused neutrophils to produce the same levels of NETs as healthy individuals.

Kenny et al. also revealed that neutrophils use several different ways to produce and release NETs, depending on the stimulus used. Some of the ways required reactive oxygen species, such as hydrogen peroxide and enzymes, while others produced NETs without the need for these molecules. Lastly, Kenny et al. showed that the way the cells die after the NET is released is unique from other pathways that are known to kill cells.

Future work will aim to identify a single molecule that can block neutrophils from releasing NETs at the wrong time and place, without affecting the important role NETs play in fighting germs. Such a molecule could be developed into a drug for people with diseases like lupus or rheumatoid arthritis, where the release of NETs makes the disease worse not better.

DOI:http://dx.doi.org/10.7554/eLife.24437.002

Development of a Selective Inhibitor of Protein Arginine Deiminase 2

Protein arginine deiminase 2 (PAD2) plays a key role in the onset and progression of multiple sclerosis, rheumatoid arthritis, and breast cancer. To date, no PAD2-selective inhibitor has been developed. Such a compound will be critical for elucidating the biological roles of this isozyme and may ultimately be useful for treating specific diseases in which PAD2 activity is dysregulated. To achieve this goal, we synthesized a series of benzimidazole-based derivatives of Cl-amidine, hypothesizing that this scaffold would allow access to a series of PAD2-selective inhibitors with enhanced cellular efficacy. Herein, we demonstrate that substitutions at both the N-terminus and C-terminus of Cl-amidine result in >100-fold increases in PAD2 potency and selectivity (30a, 41a, and 49a) as well as cellular efficacy (30a). Notably, these compounds use the far less reactive fluoroacetamidine warhead. In total, we predict that 30a will be a critical tool for understanding cellular PAD2 function and sets the stage for treating diseases in which PAD2 activity is dysregulated.

Motuporamine Derivatives as Antimicrobial Agents and Antibiotic Enhancers against Resistant Gram-Negative Bacteria

Dihydromotuporamine C and its derivatives were evaluated for their in vitro antimicrobial activities and antibiotic enhancement properties against Gram‐negative bacteria and clinical isolates. The mechanism of action of one of these derivatives, MOTU‐N44, was investigated against Enterobacter aerogenes by using fluorescent dyes to evaluate outer‐membrane depolarization and permeabilization. Its efficiency correlated with inhibition of dye transport, thus suggesting that these molecules inhibit drug transporters by de‐energization of the efflux pump rather than by direct interaction of the molecule with the pump. This suggests that depowering the efflux pump provides another strategy to address antibiotic resistance.

Citrullination regulates the expression of insulin-like growth factor-binding protein 1 (IGFBP1) in ovine uterine luminal epithelial cells

There are five peptidylarginine deiminase (PAD) isozymes designated as PADs 1, 2, 3, 4 and 6, and many are expressed in female reproductive tissues. These enzymes post-translationally convert positively charged arginine amino acids into neutral citrulline residues. Targets for PAD-catalyzed citrullination include arginine residues on histone tails, which results in chromatin decondensation and changes in gene expression. Some of the first studies examining PADs found that they are localized to rodent uterine epithelial cells. Despite these findings, the function of PAD-catalyzed citrullination in uterine epithelial cells is still unknown. To address this, we first examined PAD expression in uterine cross-sections from pregnant ewes on gestation day 25 (d25). Immunohistochemistry revealed that the levels of PADs 2 and 4 are robust in luminal and glandular epithelia compared with those of PADs 1 and 3. As PADs 2 and 4 have well-characterized roles in histone citrullination, we next hypothesized that PADs citrullinate histones in these uterine cells. Examination of caruncle lysates from pregnant ewes on gestation d25 and an ovine luminal epithelial (OLE) cell line shows that histone H3 arginine residues 2, 8, 17 and 26 are citrullinated, but histone H4 arginine 3 is not. Using a pan-PAD inhibitor, we next attenuated histone citrullination in OLE cells, which resulted in a significant decrease in the expression of insulin-like growth factor-binding protein 1 (IGFBP1) mRNA. As IGFBP1 is important for the migration and attachment of the trophectoderm to uterine endometrium, our results suggest that PAD-catalyzed citrullination may be an important post-translational mechanism for the establishment of pregnancy in ewes.

GnRH Stimulates Peptidylarginine Deiminase Catalyzed Histone Citrullination in Gonadotrope Cells

Peptidylarginine deiminase (PAD) enzymes convert histone tail arginine residues to citrulline resulting in chromatin decondensation. Our previous work found that PAD isoforms are expressed in female reproductive tissues in an estrous cycle-dependent fashion, but their role in the anterior pituitary gland is unknown. Thus, we investigated PAD expression and function in gonadotrope cells. The gonadotrope-derived LβT2 cell line strongly expresses PAD2 at the protein level compared with other PAD isoforms. Consistent with this, PAD2 protein expression is highest during the estrous phase of the estrous cycle and colocalizes with the LH β-subunit in the mouse pituitary. Using the GnRH agonist buserelin (GnRHa), studies in LβT2 and mouse primary gonadotrope cells revealed that 30 minutes of stimulation caused distinct puncta of PAD2 to localize in the nucleus. Once in the nucleus, GnRHa stimulated PAD2 citrullinates histone H3 tail arginine residues at sites 2, 8, and 17 within 30 minutes; however, this effect and PAD2 nuclear localization was blunted by incubation of the cells with the pan-PAD inhibitor, biphenyl-benzimidazole-Cl-amidine. Given that PAD2 citrullinates histones in gonadotropes, we next analyzed the functional consequence of PAD2 inhibition on gene expression. Our results show that GnRHa stimulates an increase in LHβ and FSHβ mRNA and that this response is significantly reduced in the presence of the PAD inhibitor biphenyl-benzimidazole-Cl-amidine. Overall, our data suggest that GnRHa stimulates PAD2-catalyzed histone citrullination in gonadotropes to epigenetically regulate gonadotropin gene expression.

Development of Glucose Regulated Protein 94-Selective Inhibitors Based on the BnIm and Radamide Scaffold

Glucose regulated protein 94 (Grp94) is the endoplasmic reticulum resident of the heat shock protein 90 kDa (Hsp90) family of molecular chaperones. Grp94 associates with many proteins involved in cell adhesion and signaling, including integrins, Toll-like receptors, immunoglobulins, and mutant myocilin. Grp94 has been implicated as a target for several therapeutic areas including glaucoma, cancer metastasis, and multiple myeloma. While 85% identical to other Hsp90 isoforms, the N-terminal ATP-binding site of Grp94 possesses a unique hydrophobic pocket that was used to design isoform-selective inhibitors. Incorporation of a cis-amide bioisostere into the radamide scaffold led to development of the original Grp94-selective inhibitor, BnIm. Structure-activity relationship studies have now been performed on the aryl side chain of BnIm, which resulted in improved analogues that exhibit better potency and selectivity for Grp94. These analogues also manifest superior antimigratory activity in a metastasis model as well as enhanced mutant myocilin degradation in a glaucoma model compared to BnIm.

Citrullination-acetylation interplay guides E2F-1 activity during the inflammatory response

Peptidyl arginine deiminase 4 (PAD4) is a nuclear enzyme that converts arginine residues to citrulline. Although increasingly implicated in inflammatory disease and cancer, the mechanism of action of PAD4 and its functionally relevant pathways remains unclear. E2F transcription factors are a family of master regulators that coordinate gene expression during cellular proliferation and diverse cell fates. We show that E2F-1 is citrullinated by PAD4 in inflammatory cells. Citrullination of E2F-1 assists its chromatin association, specifically to cytokine genes in granulocyte cells. Mechanistically, citrullination augments binding of the BET (bromodomain and extra-terminal domain) family bromodomain reader BRD4 (bromodomain-containing protein 4) to an acetylated domain in E2F-1, and PAD4 and BRD4 coexist with E2F-1 on cytokine gene promoters. Accordingly, the combined inhibition of PAD4 and BRD4 disrupts the chromatin-bound complex and suppresses cytokine gene expression. In the murine collagen-induced arthritis model, chromatin-bound E2F-1 in inflammatory cells and consequent cytokine expression are diminished upon small-molecule inhibition of PAD4 and BRD4, and the combined treatment is clinically efficacious in preventing disease progression. Our results shed light on a new transcription-based mechanism that mediates the inflammatory effect of PAD4 and establish the interplay between citrullination and acetylation in the control of E2F-1 as a regulatory interface for driving inflammatory gene expression.

Abstract A108: Targeting sphingolipid metabolism and metastasis with motuporamine derivatives

The purpose of this research is to develop non-toxic antimetastatic agents for use in the treatment of metastatic pancreatic cancers. Dihydromotuporamine C (1) and related motuporamines were previously isolated from the sea sponge Xestospongia exigua found off the coast of Motupore island, New Guinea. The motuporamine structure contains a large heterocycle with an appended polyamine chain. These are of biological interest due to their potent anti-migration and anti-angiogenic properties. Previous work demonstrated key structural features (i.e., saturated 15-membered heterocycle and norspermidine) necessary for their antimetastatic activity. Genetic studies in yeast suggested that these compounds target sphingolipid metabolism. In this report, a series of carbocycle-polyamine conjugates were explored to find compounds with improved properties. Of this panel, (N1-(3-aminopropyl)-N3-(cyclopentadecylmethyl)propane-1,3-diamine 2) was discovered which had a two-fold increase in anti-migration potency and was 133-fold less toxic than 1.

Several experimental procedures were used to investigate perturbations in sphingolipid metabolism. Significant changes in specific ceramide populations (N16:0 and N22:1) were noted in human L3.6pl metastatic pancreatic cancer cells treated with 1, but not with derivative 2 (which was similar to the untreated control). Both 1 and 2 gave increased levels of low molecular weight sphingomyelins and inhibited cell migration in vitro. A mouse model using metastatic human L3.6pl pancreatic cancer cells demonstrated significant reduction in L3.6pl liver metastases for mice treated with the new derivative 2 compared with the parent compound 1.

In summary, alterations in the N16:0/N22:1 ceramide ratio provided a potential explanation for the toxicity of 1. Significantly increased levels of low molecular weight sphingomyelins in cells treated with either 1 or 2 suggested that they potentially target sphingomyelin synthase (as agonists) or sphingomyelinase enzymes (as inhibitors). We speculate that these increased levels of sphingomyelin may inhibit metastatic pathways associated with CXCR4 signaling; a pathway with known sensitivity to sphingomyelin.

In conclusion, this report describes for the first time how compounds of this type alter chain-length specific ceramide and sphingomyelin populations in metastatic pancreatic cancer cells and suggests a novel mechanism for how they inhibit pancreatic cell metastasis.

References:

1. Synthesis and Biological Evaluation of Dihydromotuporamine Derivatives in Cells Containing Active Polyamine Transporters. Kaur, N,; Delcros, J-G.; Martin, B.; Phanstiel, IV, O. J. Med. Chem. 2005, 48, 3832-3839.

2. Modeling the Preferred Shapes of Polyamine Transporter Ligands and Dihydromotuporamine-C Mimics: Shovel versus Hoe. Breitbeil III, F. Kaur, N.; Delcros, J-G.; Martin,B.; Abboud, K.A.; Phanstiel, IV, O. J. Med. Chem. 2006, 49, 2407-2416.

3. Motuporamine Mimic Agents. Otto Phanstiel IV, U.S. Patent: 7,728,041, June 1, 2010.

4. Antimetastatic Agents Predicated upon Polyamine-macrocyclic conjugates. Otto Phanstiel IV and Aaron Muth. World Patent A1, WO 2013148219, October 3, 2013.

Citation Format: Aaron Muth, Veethika Pandey, Xianlin Han, Deborah Altomare, Otto Phanstiel, IV. Targeting sphingolipid metabolism and metastasis with motuporamine derivatives. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A108.

Systematic review of surgery and outcomes in patients with primary aldosteronism

BACKGROUND

Primary aldosteronism (PA) is the most common cause of secondary hypertension. The main aims of this paper were to review outcome after surgical versus medical treatment of PA and partial versus total adrenalectomy in patients with PA.

METHODS

Relevant medical literature from PubMed, the Cochrane Library and Embase OvidSP from 1985 to June 2014 was reviewed.

RESULTS

Of 2036 records, 43 articles were included in the final analysis. Twenty-one addressed surgical versus medical treatment of PA, four considered partial versus total adrenalectomy for unilateral PA, and 18 series reported on surgical outcomes. Owing to the heterogeneity of protocols and reported outcomes, only a qualitative analysis was performed. In six studies, surgical and medical treatment had comparable outcomes concerning blood pressure, whereas six showed better outcome after surgery. No differences were seen in cardiovascular complications, but surgery was associated with the use of fewer antihypertensive medications after surgery, improved quality of life, and (possibly) lower all-cause mortality compared with medical treatment. Randomized studies indicate a role for partial adrenalectomy in PA, but the high rate of multiple adenomas or adenoma combined with hyperplasia in localized disease is disconcerting. Surgery for unilateral dominant PA normalized BP in a mean of 42 (range 20-72) per cent and the biochemical profile in 96-100 per cent of patients. The mean complication rate in 1056 patients was 4·7 per cent.

CONCLUSION

Recommendations for treatment of PA are hampered by the lack of randomized trials, but support surgical resection of unilateral disease. Partial adrenalectomy may be an option in selected patients.

Polyamine transport inhibitors: design, synthesis, and combination therapies with difluoromethylornithine

The development of polyamine transport inhibitors (PTIs), in combination with the polyamine biosynthesis inhibitor difluoromethylornithine (DFMO), provides a method to target cancers with high polyamine requirements. The DFMO+PTI combination therapy results in sustained intracellular polyamine depletion and cell death. A series of substituted benzene derivatives were evaluated for their ability to inhibit the import of spermidine in DFMO-treated Chinese hamster ovary (CHO) and L3.6pl human pancreatic cancer cells. Several design features were discovered which strongly influenced PTI potency, sensitivity to amine oxidases, and cytotoxicity. These included changes in (a) the number of polyamine chains appended to the ring system, (b) the polyamine sequence, (c) the attachment linkage of the polyamine to the aryl core, and (d) the presence of a terminal N-methyl group. Of the series tested, the optimal design was N(1),N(1'),N(1″)-(benzene-1,3,5-triyltris(methylene))tris(N(4)-(4-(methylamino)butyl)butane-1,4-diamine, 6b, which contained three N-methylhomospermidine motifs. This PTI exhibited decreased sensitivity to amine oxidases and low toxicity as well as high potency (EC50 = 1.4 μM) in inhibiting the uptake of spermidine (1 μM) in DFMO-treated L3.6pl human pancreatic cancer cells.