Impact of dual mTORC1/2 mTOR kinase inhibitor AZD8055 on acquired endocrine resistance in breast cancer in vitro

Introduction: Upregulation of PI3K/Akt/mTOR signalling in endocrine-resistant breast cancer (BC) has identified mTOR as an attractive target alongside anti-hormones to control resistance. RAD001 (everolimus/Afinitor®), an allosteric mTOR inhibitor, is proving valuable in this setting; however, some patients are inherently refractory or relapse during treatment requiring alternative strategies. Here we evaluate the potential for novel dual mTORC1/2 mTOR kinase inhibitors, exemplified by AZD8055, by comparison with RAD001 in ER + endocrine resistant BC cells. Methods: In vitro models of tamoxifen (TamR) or oestrogen deprivation resistance (MCF7-X) were treated with RAD001 or AZD8055 alone or combined with anti-hormone fulvestrant. Endpoints included growth, cell proliferation (Ki67), viability and migration, with PI3K/AKT/mTOR signalling impact monitored by Western blotting. Potential ER cross-talk was investigated by immunocytochemistry and RT-PCR. Results: RAD001 was a poor growth inhibitor of MCF7-derived TamR and MCF7-X cells (IC50 ≥1 μM), rapidly inhibiting mTORC1 but not mTORC2/AKT signalling. In contrast AZD8055, which rapidly inhibited both mTORC1 and mTORC2/AKT activity, was a highly effective (P <0.001) growth inhibitor of TamR (IC50 18 nM) and MCF7-X (IC50 24 nM), and of a further T47D-derived tamoxifen resistant model T47D-tamR (IC50 19 nM). AZD8055 significantly (P <0.05) inhibited resistant cell proliferation, increased cell death and reduced migration. Furthermore, dual treatment of TamR or MCF7-X cells with AZD8055 plus fulvestrant provided superior control of resistant growth versus either agent alone (P <0.05). Co-treating with AZD8055 alongside tamoxifen (P <0.01) or oestrogen deprivation (P <0.05) also effectively inhibited endocrine responsive MCF-7 cells. Although AZD8055 inhibited oestrogen receptor (ER) ser167 phosphorylation in TamR and MCF7-X, it had no effect on ER ser118 activity or expression of several ER-regulated genes, suggesting the mTOR kinase inhibitor impact was largely ER-independent. The capacity of AZD8055 for ER-independent activity was further evidenced by growth inhibition (IC5018 and 20 nM) of two acquired fulvestrant resistant models lacking ER. Conclusions: This is the first report demonstrating dual mTORC1/2 mTOR kinase inhibitors have potential to control acquired endocrine resistant BC, even under conditions where everolimus fails. Such inhibitors may prove of particular benefit when used alongside anti-hormonal treatment as second-line therapy in endocrine resistant disease, and also potentially alongside anti-hormones during the earlier endocrine responsive phase to hinder development of resistance

Gold(I) complexes incorporating emissive mercapto-pteridine ligands: Syntheses, X-ray structure, luminescence and preliminary cytotoxic evaluation

The syntheses of six new mixed P/S-donor two-coordinate AuI complexes are described. The complexes incorporate a pteridinyl ligand coordinated through a thiolate donor, and an ancillary tertiary phosphane (PPh3 or PCy3). The mercapto-pteridine ligands (L1–L3) differ in the nature of the substituents on the pteridine core. An X-ray crystal structure was obtained for one of the examples, [(L1)Au(PPh3)], revealing weak intermolecular interactions between two molecules of the complex: π–π contacts between aromatic rings appear to support an intermolecular Au–Au contact of approximately 3.05 Å. All of the complexes are luminescent in solution, with emission arising from tuneable ligand-based excited states, and characterised as a perturbed fluorescence in nature. In this context, complexes of L3 displayed useful visible absorption and emission. Preliminary cytotoxicity assessments were conducted using the MTT assay, and the complexes each displayed impressive anti-proliferative activities (IC50 < 5 μm) with respect to four different adenocarcinoma cell lines (MCF7, A549, PC3 and LOVO). For a given pteridine moiety, triphenylphosphane appeared to be the co-ligand of choice for enhancing biological activity

Gold (I) Complexes Derived From Alkynoxy-substituted Anthraquinones: Syntheses, Luminescence, Cytotoxicity and Cell Imaging Studies,

A series of mono- and dimetallic Au(I) triphenylphosphine complexes derived from 1,2-, 1,4-, and 1,8-dialkynyloxyanthraquinone have been prepared. The photophysical and cytotoxic behavior of the ligands and complexes have been explored, with all of the complexes showing both appreciable cytotoxicity against the MCF-7 carcinoma cell line and useful room-temperature anthraquinone-based visible luminescence, which allowed their successful application as fluorophores in cell imaging microscopy. The implications of the photophysical and toxicological properties for the design and investigation of gold-based anticancer agents are discussed

Anticancer, azonafide-inspired fluorescent ligands and their rhenium(I) complexes for cellular imaging

Two dipicolyamino-conjugated anthracene-1,9-dicarboximide fluorophores and their corresponding ReI complexes have been synthesised and photophysically examined. All species were fluorescent in the visible region at about 490 nm with lifetimes up to 16 ns. The anticancer potency of the ligands and complexes was demonstrated across a range of cancer cell lines (LOVO, PC3, A549, MCF-7). Cell imaging studies with MCF7 cells and Schizosaccharomyces pombe show that these fluorophores exhibit variable intracellular localisation patterns that are structure-dependent

Gold(I) Complexes Derived from Alkynyloxy-Substituted Anthraquinones: Syntheses, Luminescence, Preliminary Cytotoxicity, and Cell Imaging Studies

A series of mono- and dimetallic Au­(I) triphenylphosphine complexes derived from 1,2-, 1,4-, and 1,8-dialkynyloxyanthraquinone have been prepared. The photophysical and cytotoxic behavior of the ligands and complexes have been explored, with all of the complexes showing both appreciable cytotoxicity against the MCF-7 carcinoma cell line and useful room-temperature anthraquinone-based visible luminescence, which allowed their successful application as fluorophores in cell imaging microscopy. The implications of the photophysical and toxicological properties for the design and investigation of gold-based anticancer agents are discussed

Gold(I) Complexes Derived from Alkynyloxy-Substituted Anthraquinones: Syntheses, Luminescence, Preliminary Cytotoxicity, and Cell Imaging Studies

A series of mono- and dimetallic Au­(I) triphenylphosphine complexes derived from 1,2-, 1,4-, and 1,8-dialkynyloxyanthraquinone have been prepared. The photophysical and cytotoxic behavior of the ligands and complexes have been explored, with all of the complexes showing both appreciable cytotoxicity against the MCF-7 carcinoma cell line and useful room-temperature anthraquinone-based visible luminescence, which allowed their successful application as fluorophores in cell imaging microscopy. The implications of the photophysical and toxicological properties for the design and investigation of gold-based anticancer agents are discussed

Alkynyl-naphthalimide Fluorophores: Gold Coordination Chemistry and Cellular Imaging Applications

A range of fluorescent alkynyl-naphthalimide fluorophores has been synthesized and their photophysical properties examined. The fluorescent ligands are based upon a 4-substituted 1,8-naphthalimide core and incorporate structural variations (at the 4-position) to tune the amphiphilic character: chloro (<b>L1</b>), 4-[2-(2-aminoethoxy)­ethanol] (<b>L2</b>), 4-[2-(2-methoxyethoxy)­ethylamino] (<b>L3</b>), piperidine (<b>L4</b>), morpholine (<b>L5</b>), 4-methylpiperidine (<b>L6</b>), and 4-piperidone ethylene ketal (<b>L7</b>) variants. The amino-substituted species (<b>L2</b>–<b>L7</b>) are fluorescent in the visible region at around 517–535 nm through a naphthalimide-localized intramolecular charge transfer (ICT), with appreciable Stokes’ shifts of ca. 6500 cm^–1 and lifetimes up to 10.4 ns. Corresponding two-coordinate Au­(I) complexes [Au­(L)­(PPh₃)] were isolated, with X-ray structural studies revealing the expected coordination mode via the alkyne donor. The Au­(I) complexes retain the visible fluorescence associated with the coordinated alkynyl-naphthalimide ligand. The ligands and complexes were investigated for their cytotoxicity across a range of cell lines (LOVO, MCF-7, A549, PC3, HEK) and their potential as cell imaging agents for HEK (human embryonic kidney) cells and Spironucleus vortens using confocal fluorescence microscopy. The images reveal that these fluorophores are highly compatible with fluorescence microscopy and show some clear intracellular localization patterns that are dependent upon the specific nature of the naphthalimide substituent

Integration and early testing of WEAVE: the next-generation spectroscopy facility for the William Herschel Telescope

We present an update on the overall integration progress of the WEAVE next-generation spectroscopy facility for the William Herschel Telescope (WHT), now scheduled for first light in early-2021, with almost all components now arrived at the observatory. We also present a summary of the current planning behind the 5-year initial phase of survey operations, and some detailed end-to-end science simulations that have been implemented to evaluate the final on-sky performance after data processing. WEAVE will provide optical ground-based follow up of ground-based (LOFAR) and space-based (Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2-degree prime focus field of view at the WHT, with a buffered pick-and-place positioner system hosting 1000 multi-object (MOS) fibres, 20 mini integral field units, or a single large IFU for each observation. The fibres are fed to a single (dual-beam) spectrograph, with total of 16k spectral pixels, located within the WHT GHRIL enclosure on the telescope Nasmyth platform, supporting observations at R~5000 over the full 370-1000nm wavelength range in a single exposure, or a high resolution mode with limited coverage in each arm at R~20000