Effect of substituents on the ability of nickel Schiff base complexes with four pendant groups to bind to G-quadruplexes.

The synthesis of eleven new nickel Schiff base complexes each bearing four pendant groups is reported. The structures of the complexes differ in the identity of the pendant groups and/or diamine moiety. All complexes were characterised by microanalysis, Nuclear Magnetic Resonance (NMR) spectroscopy and Electrospray Ionisation Mass Spectrometry (ESI-MS), while the solid-state structures of two of the molecules were also determined using X-ray crystallographic methods. The DNA binding properties of the nickel complexes with double stranded DNA and a range of G-quadruplex DNA structures was explored using different spectroscopic methods as well as computational techniques. Results from ESI-MS experiments and Fluorescent Indicator Displacement (FID) assays were consistent with each other and indicated that varying the diamine moiety had less influence on DNA affinity than changing the pendant groups. These conclusions were also generally supported by results obtained from UV melting experiments and Fluorescence Resonance Energy Transfer (FRET) assays. The cytotoxicity of selected examples of the new complexes, and close analogues reported recently, towards V79 Chinese hamster lung cancer cells and THP-1 human leukemia cells was measured. All were found to display modest cytotoxicity, with flow cytometry experiments suggesting an apoptotic pathway was the most likely mechanism of cell death.

G-quadruplex DNA binding properties of novel nickel Schiff base complexes with four pendant groups.

Three new nickel Schiff base complexes were prepared using a two-step procedure that involves initial selective dialkylation of 2,4,6-trihydroxybenzaldehyde, followed by reaction with 1,2-phenylenediamine and nickel(II) acetate. Each of the complexes possessed the same Schiff base core but differed in the identity of the four pendant groups. All complexes were characterised by microanalysis, NMR spectroscopy and ESI mass spectrometry. In addition, two of the complexes were also characterised in the solid state using X-ray crystallography, which confirmed the presence of a square planar geometry around the metal ion. The DNA binding properties of the three nickel complexes with double stranded DNA and a range of G-quadruplex DNA structures were explored using ESI mass spectrometry, CD spectroscopy, UV melting curves, Fluorescence Resonance Energy Transfer (FRET) assays, Fluorescent Indicator Displacement (FID) assays and molecular docking studies. These techniques confirmed the ability of the three nickel complexes to bind to most of the DNA molecules examined, as well as stabilise the latter in several instances. In addition, the results of these investigations provided evidence that pendant groups with morpholine rings generally reduced DNA binding behaviour, whilst pendants featuring piperidine ring systems attached to the Schiff base core by three and not two methylene linkers often showed the greatest extent of binding or DNA stabilisation.

Therapeutic Targeting of Mitochondrial Plasticity and Redox Control to Overcome Cancer Chemoresistance.

Significance: Mitochondria are subcellular organelles performing essential metabolic functions contributing to cellular bioenergetics and regulation of cell growth or death. The basic mitochondrial function in fulfilling the need for cell growth and vitality is evidenced whereby cancer cells with depleted mitochondrial DNA (rho zero, p0 cells) no longer form tumors until newly recruited mitochondria are internalized into the rho zero cells. Herein lies the absolute dependency on mitochondria for tumor growth. Hence, mitochondria are key regulators of cell death (by apoptosis, necroptosis, or other forms of cell death) and are, therefore, important targets for anticancer therapy. Recent Advances: Mitochondrial plasticity regulating their state of fusion or fission is key to the chemoresistance properties of cancer cells by promoting pro-survival pathways, enabling the mitochondria to mitigate against the cellular stresses and extreme conditions within the tumor microenvironment caused by chemotherapy, hypoxia, or oxidative stress. Critical Issues: This review discusses many characteristics of mitochondria, the processes and pathways controlling the dynamic changes occurring in the morphology of mitochondria, the roles of reactive oxygen species, and their relationship with mitochondrial fission or fusion. It also examines the relationship of redox to mitophagy when mitochondria become compromised and its effect on cancer cell survival, stemness, and the changes accompanying malignant progression from primary tumors to metastatic disease. Future Directions: A challenging question that arises is whether the changes in mitochondrial dynamics and their regulation can provide opportunities for improving drug targeting during cancer treatment and enhancing survival outcomes. Antioxid. Redox Signal. 39, 591-619.

Understanding G-Quadruplex Biology and Stability Using Single-Molecule Techniques.

The link between the chemical stability of G-quadruplex (qDNA) structures and their roles in eukaryotic genomic maintenance processes has been an area of interest now for several decades. This Review seeks to demonstrate how single-molecule force-based techniques can provide insight into the mechanical stabilities of a variety of qDNA structures as well as their ability to interconvert between different conformations under conditions of stress. Atomic force microscopy (AFM) and magnetic and optical tweezers have been the primary tools used in these investigations and have been used to examine both free and ligand-stabilized G-quadruplex structures. These studies have shown that the degree of stabilization of G-quadruplex structures has a significant effect on the ability of nuclear machinery to bypass these roadblocks on DNA strands. This Review will illustrate how various cellular components including replication protein A (RPA), Bloom syndrome protein (BLM), and Pif1 helicases are capable of unfolding qDNA. Techniques such as single-molecule fluorescence resonance energy transfer (smFRET), often in conjunction with the aforementioned force-based techniques, have proven extremely effective at elucidating the factors underpinning the mechanisms by which these proteins unwind qDNA structures. We will provide insight into how single-molecule tools have facilitated the direct visualization of qDNA roadblocks and also showcase results obtained from experiments designed to examine the ability of G-quadruplexes to limit the access of specific cellular proteins normally associated with telomeres.

Mitoribosome sensitivity to HSP70 inhibition uncovers metabolic liabilities of castration-resistant prostate cancer.

The androgen receptor is a key regulator of prostate cancer and the principal target of current prostate cancer therapies collectively termed androgen deprivation therapies. Insensitivity to these drugs is a hallmark of progression to a terminal disease state termed castration-resistant prostate cancer. Therefore, novel therapeutic options that slow progression of castration-resistant prostate cancer and combine effectively with existing agents are in urgent need. We show that JG-98, an allosteric inhibitor of HSP70, re-sensitizes castration-resistant prostate cancer to androgen deprivation drugs by targeting mitochondrial HSP70 (HSPA9) to suppress aerobic respiration. Rather than impacting androgen receptor stability as previously described, JG-98's primary effect is inhibition of mitochondrial translation, leading to disruption of electron transport chain activity. Although functionally distinct from HSPA9 inhibition, direct inhibition of the electron transport chain with a complex I or II inhibitor creates a similar physiological state capable of re-sensitizing castration-resistant prostate cancer to androgen deprivation therapies. These data identify a significant role for HspA9 in mitochondrial ribosome function and highlight an actionable metabolic vulnerability of castration-resistant prostate cancer.

Intratumoral pro-oxidants promote cancer immunotherapy by recruiting and reprogramming neutrophils to eliminate tumors.

Neutrophils have recently gained recognition for their potential in the fight against cancer. Neutrophil plasticity between the N1 anti-tumor and N2 pro-tumor subtypes is now apparent, as is the ability to polarize these individual subtypes by interventions such as intratumoral injection of various agents including bacterial products or pro-oxidants. Metabolic responses and the production of reactive oxygen species (ROS) such as hydrogen peroxide act as potent chemoattractants and activators of N1 neutrophils that facilitates their recruitment and ensuing activation of a toxic respiratory burst in tumors. Greater understanding of the precise mechanism of N1 neutrophil activation, recruitment and regulation is now needed to fully exploit their anti-tumor potential against cancers both locally and at distant sites. This systematic review critically analyzes these new developments in cancer immunotherapy.

Multi-layer inverse design of vertical grating couplers for high-density, commercial foundry interconnects.

Density-based topology optimization is used to design large-scale, multi-layer grating couplers that comply with commercial foundry fabrication constraints while simultaneously providing beam profiles that efficiently couple to a single-mode optical fiber without additional optics. Specifically, we describe the design process and experimentally demonstrate both single- and dual-polarization grating couplers that couple at normal incidence (0° from the normal) with low backreflections (-13.7 dB and -15.4 dB at the center wavelength), broad 3 dB bandwidths (75 nm and 89 nm), and standard coupling efficiencies (-4.7 dB and -7.0 dB). The dual-polarization grating couplers exhibit over 30 dB of polarization extinction across the entire band. The devices were fabricated on the GlobalFoundries 45CLO CMOS platform and characterized across three separate wafers. This new design approach produces distinct features for multiple foundry layers and yields emitters with arbitrary, user-specified far-field profiles.

Constellation-based identification of linear and nonlinear OSNR using machine learning: a study of link-agnostic performance.

We demonstrate accurate estimation of generalized optical signal to noise ratio (GOSNR) for wavelength division multiplexed fiber communication systems using an experimentally trained multi-tasking convolutional neural network while simultaneously estimating linear and nonlinear noise contributions. Using dual-polarized 32-GBaud 16QAM DWDM links we extract learnable features from constellation density matrices and accurately estimate GOSNR while simultaneously estimating linear and nonlinear contributions. Estimation of the OSNRASE, OSNRNL and GOSNR are demonstrated with < 0.5 dB mean absolute error. We also assess the universality of our model within the regime of metro networks by cross-training with data from such links comprised of different fiber types. We demonstrate a path to a practical universal training method that includes additional link parameters. The methods do not require contiguous high-speed sampling, additional hardware nor transmission of special symbols or patterns and are readily implemented in deployed systems.

High-performance hybrid time/frequency-domain topology optimization for large-scale photonics inverse design.

We present a photonics topology optimization (TO) package capable of addressing a wide range of practical photonics design problems, incorporating robustness and manufacturing constraints, which can scale to large devices and massive parallelism. We employ a hybrid algorithm that builds on a mature time-domain (FDTD) package Meep to simultaneously solve multiple frequency-domain TO problems over a broad bandwidth. This time/frequency-domain approach is enhanced by new filter-design sources for the gradient calculation and new material-interpolation methods for optimizing dispersive media, as well as by multiple forms of computational parallelism. The package is available as free/open-source software with extensive tutorials and multi-platform support.

Targeting the redox imbalance in mitochondria: A novel mode for cancer therapy.

Changes in reactive oxygen species (ROS) levels affect many aspects of cell behavior. During carcinogenesis, moderate ROS production modifies gene expression to alter cell function, elevating metabolic activity and ROS. To avoid extreme ROS-activated death, cancer cells increase antioxidative capacity, regulating sustained ROS levels that promote growth. Anticancer therapies are exploring inducing supranormal, cytotoxic oxidative stress levels either inhibiting antioxidative capacity or promoting excess ROS to selectively destroy cancer cells, triggering mechanisms such as apoptosis, autophagy, necrosis, or ferroptosis. This review exemplifies pro-oxidants (natural/synthetic/repurposed drugs) and their clinical significance as cancer therapies providing revolutionary approaches.

Photonic topology optimization with semiconductor-foundry design-rule constraints.

We present a unified density-based topology-optimization framework that yields integrated photonic designs optimized for manufacturing constraints including all those of commercial semiconductor foundries. We introduce a new method to impose minimum-area and minimum-enclosed-area constraints, and simultaneously adapt previous techniques for minimum linewidth, linespacing, and curvature, all of which are implemented without any additional re-parameterizations. Furthermore, we show how differentiable morphological transforms can be used to produce devices that are robust to over/under-etching while also satisfying manufacturing constraints. We demonstrate our methodology by designing three broadband silicon-photonics devices for nine different foundry-constraint combinations.

Tea tree oil extract causes mitochondrial superoxide production and apoptosis as an anticancer agent, promoting tumor infiltrating neutrophils cytotoxic for breast cancer to induce tumor regression.

The antitumor activity of the tea tree oil (TTO) derived product, Melaleuca Alternifolia Concentrate (MAC) was characterized mechanistically at the molecular and cellular level. MAC was analyzed for its anticancer activity against human prostate (LNCaP) and breast (MCF-7) cancer cell lines growing in vitro. MAC (0.02-0.06% v/v) dose-dependently induced the intrinsic (mitochondrial) apoptotic pathway in both the LNCaP and MCF-7 cell lines, involving increased mitochondrial superoxide production, loss of mitochondrial membrane potential (MMP), caspase 3/7 activation, as well as the presence of TUNEL+ and cleaved-PARP+ cell populations. At concentrations of 0.01-0.04% v/v, MAC caused cell cycle arrest in the G0/1-phase, as well as autophagy. The in vivo anticancer actions of MAC were examined as a treatment in the FVB/N c-Neu murine model for spontaneously arising breast cancers. Intratumoral MAC injections (1-4% v/v) significantly suppressed tumor progression in a dose-dependent manner and was associated with greater levels of tumor infiltrating neutrophils exhibiting anticancer cytotoxic activity. Induction of breast cancer cell death by MAC via the mitochondrial apoptotic pathway was also replicated occurring in tumors treated in vivo. In conclusion, our data highlights the potential for the Melaleuca-derived MAC product inducing anticancer neutrophil influx, supporting its application as a novel therapeutic agent.

Non-Steroidal Anti-Inflammatory Drugs Increase Cisplatin, Paclitaxel, and Doxorubicin Efficacy against Human Cervix Cancer Cells.

This study shows that the non-steroidal anti-inflammatory drug (NSAID) celecoxib and its non-cyclooxygenase-2 (COX2) analogue dimethylcelecoxib (DMC) exert a potent inhibitory effect on the growth of human cervix HeLa multi-cellular tumor spheroids (MCTS) when added either at the beginning ("preventive protocol"; IC50 = 1 ± 0.3 nM for celecoxib and 10 ± 2 nM for DMC) or after spheroid formation ("curative protocol"; IC50 = 7.5 ± 2 µM for celecoxib and 32 ± 10 µM for DMC). These NSAID IC50 values were significantly lower than those attained in bidimensional HeLa cells (IC50 = 55 ± 9 µM celecoxib and 48 ± 2 µM DMC) and bidimensional non-cancer cell cultures (3T3 fibroblasts and MCF-10A mammary gland cells with IC50 from 69 to >100 µM, after 24 h). The copper-based drug casiopeina II-gly showed similar potency against HeLa MCTS. Synergism analysis showed that celecoxib, DMC, and casiopeinaII-gly at sub-IC50 doses increased the potency of cisplatin, paclitaxel, and doxorubicin to hinder HeLa cell proliferation through a significant abolishment of oxidative phosphorylation in bidimensional cultures, with no apparent effect on non-cancer cells (therapeutic index >3.6). Similar results were attained with bidimensional human cervix cancer SiHa and human glioblastoma U373 cell cultures. In HeLa MCTS, celecoxib, DMC and casiopeina II-gly increased cisplatin toxicity by 41-85%. These observations indicated that celecoxib and DMC used as adjuvant therapy in combination with canonical anti-cancer drugs may provide more effective alternatives for cancer treatment.

Optical performance monitoring using digital coherent receivers and convolutional neural networks.

We experimentally demonstrate accurate modulation format identification, optical signal to noise ratio (OSNR) estimation, and bit error ratio (BER) estimation of optical signals for wavelength division multiplexed optical communication systems using convolutional neural networks (CNN). We assess the benefits and challenges of extracting information at two distinct points within the demodulation process: immediately after timing recovery and immediately prior to symbol unmapping. For the former, we use 3D Stokes-space based signal representations. For the latter, we use conventional I-Q constellation images created using demodulated symbols. We demonstrate these methods on simulated and experimental dual-polarized waveforms for 32-GBaud QPSK, 8QAM, 16QAM, and 32QAM. Our results show that CNN extracts distinct and learnable features at both the early stage of demodulation where the information can be used to optimize subsequent stages and near the end of demodulation where the constellation images are readily available. Modulation format identification is demonstrated with >99.8% accuracy, OSNR estimation with <0.5 dB average discrepancy and BER estimation with percentage error of <25%.

The effect of isomerism and other structural variations on the G-quadruplex DNA-binding properties of some nickel Schiff base complexes.

A series of novel isomeric nickel Schiff base complexes, as well as nickel complexes of related ligands having asymmetric structures have been prepared and characterised using microanalysis, 1H and 13C NMR spectroscopy and ESI-MS. The Schiff base ligands were prepared by condensation reactions involving ethylenediamine and different derivatives of benzophenone. The solid-state structures of eight of the complexes were also determined and revealed that each possessed a regular square planar coordination geometry around the metal ion. Many of the new complexes featured at least one, and in many instances two, protonatable pendant groups that enhance aqueous solubility. This enabled the DNA binding properties of the latter complexes to be explored using a variety of instrumental approaches, including ESI-MS, circular dichroism (CD) spectroscopy, FRET melting assays and FID assays, as well as molecular docking studies. The results of experiments performed using ESI-MS suggested that none of the nickel complexes exhibit a high affinity towards either a double stranded DNA (dsDNA) molecule D2, or the parallel unimolecular quadruplex DNA (qDNA) molecule Q1. In contrast, complexes (8) and (12) both gave spectra which reflected a significant level of binding to the parallel tetramolecular qDNA Q4. The results of binding experiments performed using CD spectroscopy suggested that (12) exhibits a significant level of affinity towards most types of DNA, while (4) shows a preference for interacting with parallel, unimolecular qDNA molecules. Complex (4) produced the lowest values of DC50 in FID assays performed using parallel Q1 or Q4, confirming its affinity for these qDNA molecules. The results of FRET melting experiments provided further evidence that (12), along with (8), can interact extensively with anti-parallel unimolecular qDNA. Experiments which monitored the effect of the nickel complexes on the melting temperature of D2 showed that none had a stabilising effect on this dsDNA molecule.

A new class of quadruplex DNA-binding nickel Schiff base complexes.

We have prepared six new nickel Schiff base complexes via reactions of substituted benzophenones with different diamines in the presence of nickel(ii). These new complexes were then reacted with 1-(2-choroethyl)piperidine to afford a further six novel nickel(ii) Schiff base complexes bearing pendant ethylpiperidine groups. The complexes bearing the ethylpiperidine moieties had greater solubility in water, and were therefore suitable for use in DNA binding experiments. ESI mass spectra of solutions containing 4 and the parallel, tetramolecular quadruplex Q4, contained ions attributable to formation of non-covalent complexes. In contrast, no ions from non-covalent complexes were observed when the experiments were repeated using 4 and either a double stranded DNA (dsDNA) molecule (D2), or parallel Q1, a unimolecular quadruplex DNA (qDNA). The ESI-MS binding study also revealed that 14 has a significant ability to form non-covalent complexes with qDNA, but does not interact to the same extent with D2. This is supported by the large changes to the ellipticity of bands observed in the circular dichroism spectra of two different unimolecular qDNA molecules (c-kit1 and Q1), including the latter annealed under conditions designed to induce formation of alternative topologies (antiparallel and hybrid). In Fluorescent Indicator Displacement (FID) assays conducted using the new nickel complexes, 14 gave the lowest values of DC50 for experiments conducted with Q1 and Q4. Furthermore, 14 showed greater stabilisation of an antiparallel qDNA molecule in FRET assays than when the other new complexes were examined. These results highlight the potential of 14 as a lead complex for future structure/DNA binding investigations. This is reinforced by the results obtained from cytotoxicity studies performed using four of the nickel complexes, including 14, and Chinese hamster lung cancer (V79) cells, which gave IC50 values between 4 and 12 µM. These complexes were also shown to have the ability to induce apoptosis in the same cancer cell line.

A study of Pt(II)-phenanthroline complex interactions with double-stranded and G-quadruplex DNA by ESI-MS, circular dichroism, and computational docking.

The binding interactions of a series of square-planar platinum(II)-phenanthroline complexes of the type [Pt(PL)(AL)]2+ [where PL = variously methyl-substituted 1,10-phenanthroline (phen) and AL = ethane-1,2-diamine (en)] were assessed with a G-quadruplex DNA (5'-TTG GGG GT-3', G4DNA) and a double-stranded DNA (5'-CGC GAA TTC GCG-3', dsDNA) sequence by ESI-MS. The results indicate a strong correlation between G4DNA affinity and increasing phenanthroline methyl substitution. Circular dichroism (CD) spectroscopy and molecular docking studies also support the finding that increased substitution of the phenanthroline ligand increased selectivity for G4DNA. ESI-MS was used to probe the interaction of a range of square-planar Pt(II)-phenanthroline complexes with double-stranded and G-quadruplex DNA.

Phase I/II parallel double-blind randomized controlled clinical trial of perispinal etanercept for chronic stroke: improved mobility and pain alleviation.

Background: Previous open-label studies showed that chronic post-stroke pain could be abated by treatment with perispinal etanercept, although these benefits were questioned. A randomized double-blind placebo controlled clinical trial was conducted to test perispinal etanercept for chronic post-stroke pain.Research design and methods: Participants received two treatments, either perispinal etanercept (active) or saline (control). Primary outcomes were the differences in daily pain levels between groups analyzed by SPSS.Results: On the 0-100 points visual analog scale, perispinal etanercept reduced mean levels for worst and average daily pain from baseline after two treatments by 19.5 - 24 points (p < 0.05), and pain alleviation was maintained in the etanercept group, with no significant change in the control group. Thirty percent of etanercept participants had near complete pain abatement after first treatment. Goniometry of the paretic arm showed improved mean shoulder rotation by 55 degrees in active forward flexion for the etanercept group (p = 0.003) only.Conclusions: Perispinal etanercept can provide significant and ongoing benefits for the chronic post-stroke management of pain and greater shoulder flexion by the paretic arm. Effects are rapid and highly significant, supporting direct action on brain function.Trial registration: ACTRN12615001377527 and Universal Trial Number U1111-1174-3242.

Repurposing drugs as pro-oxidant redox modifiers to eliminate cancer stem cells and improve the treatment of advanced stage cancers.

Over the last decade, three major advances have contributed in improving the response rates against cancer including, immunotherapy; greater understanding of the molecular, biochemical, and cellular mechanisms in carcinogenesis thereby providing drug targets; and identification of reliable biomarkers for early detection to facilitate the earlier stage treatment of disease. However, no single universal cancer cure has yet been found, although combinations from the above areas have steadily improved survival outcomes. Hence, chemotherapy remains a key component in the oncologist's arsenal for cancer therapy, despite frequent development of drug resistance and more aggressive cancers with onset of advanced stage metastases. The focus here is to explore the repurposing of old drugs that cause pro-oxidative overload to overcome onset of resistance to chemotherapy and enhance chemotherapeutic responses, particularly against metastatic cancer. Excellent examples of US Food and Drug Administration approved drugs suitable for repurposing are the potent and specific thioreductase inhibitor auranofin and the nonsteroidal anti-inflammatory drug, celecoxib. Recently, both drugs were shown to selectively target and kill metastatic cancer cells and cancer stem cells (CSCs), predominantly by promoting excessive mitochondrial reactive oxygen species. Thus, targeting intracellular redox systems of advanced stage metastatic cancer cells and CSCs can promote an overload of pro-oxidative stress to activate the intrinsic pathway for programmed cell death. It is envisaged that more clinical studies will incorporate longer term use of repurposed drugs, such as auranofin or celecoxib, to target redox systems in cancer cells as part of common practice postcancer diagnosis, providing enhanced chemotherapeutic responses and increased cancer survival.