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The copious metabolic acid production and -extrusion by cancer cells render poorly vascularized regions of solid tumors highly acidic. A growing list of proton - and bicarbonate transporters has been suggested to contribute to net acid extrusion from cancer cells, and/or been shown to be dysregulated and favor malignant development in various cancers. The great majority of these roles have been studied at the level of the cancer cells. However, recent advances in understanding of the cellular and physicochemical heterogeneity of solid tumors both enable and necessitate a reexamination of the regulation and roles of acid–base transporters in such malignancies. This review will briefly summarize the state-of-the-art, with a focus on the SLC9A and SLC4A families, for which most evidence is available. This is followed by a discussion of key concepts and open questions arising from recent insights and of the challenges that need to be tackled to address them. Finally, opportunities and challenges in therapeutic targeting of the acid–base transportome in cancers will be addressed. Show less

In this paper, three new iridium(III) complexes: [Ir(piq)₂(DFIPP)]PF₆ (piq = deprotonated 1-phenylisoquinoline, DFIPP = 3,4-difluoro-2-(1H-imidazo[4,5-f][1,10]phenenthrolin-2-yl)phenol, 3a), [Ir(bzq)₂(DFIPP)]PF₆ (bzq = deprotonated benzo[h]quinoline, 3b), and [Ir(ppy)₂(DFIPP)]PF₆ (ppy = deprotonated 1-phenylpyridine, 3c), were synthesized and characterized. The complexes were found to be nontoxic to tumor cells via 3-(4,5-dimethylthiazole-2-yl)-diphenyltetrazolium bromide (MTT) assay. Surprisingly, its liposome-entrapped complexes 3alip, 3blip, and 3clip on B16 cells showed strong cytotoxicity (IC₅₀ = 13.6 ± 2.8, 9.6 ± 1.1, and 18.9 ± 2.1 μM). Entry of 3alip, 3blip, and 3clip into B16 cells decreases mitochondrial membrane potential, regulates Bcl-2 family proteins, releases cytochrome c, triggers caspase family cascade reaction, and induces apoptosis. In addition, we also found that 3alip, 3blip, and 3clip triggered ferroptosis and autophagy. In vivo studies demonstrated that 3blip inhibited melanoma growth in C57 mice with a high inhibitory rate of 83.95%, and no organic damage was found in C57 mice. Show less

DNA structure has many potential places where endogenous compounds and xenobiotics can bind. Therefore, xenobiotics bind along the sites of the nucleic acid with the aim of changing its structure, its genetic message, and, implicitly, its functions. Currently, there are several mechanisms known to be involved in DNA binding. These mechanisms are covalent and non-covalent interactions. The covalent interaction or metal base coordination is an irreversible binding and it is represented by an intra-/interstrand cross-link. The non-covalent interaction is generally a reversible binding and it is represented by intercalation between DNA base pairs, insertion, major and/or minor groove binding, and electrostatic interactions with the sugar phosphate DNA backbone. In the present review, we focus on the types of DNA–metal complex interactions (including some representative examples) and on presenting the methods currently used to study them. Show less

Central to the quest of understanding the emergence of life is to uncover the role of metals, particularly iron, in shaping prebiotic chemistry. Iron, as the most abundant of the accessible transition metals on the prebiotic Earth, played a pivotal role in early biochemical processes and continues to be indispensable to modern biology. Here, we discuss our recent contributions to probing the plausibility of prebiotic complexes with iron, including heme and iron-sulfur clusters, in mediating chemistry beneficial to a protocell. Laboratory experiments and spectroscopic findings suggest plausible pathways, often facilitated by UV light, for the synthesis of heme and iron-sulfur clusters. Once formed, heme displays catalytic, peroxidase-like activity when complexed with amphiphiles. This activity could have been beneficial in two ways. First, heme could have catalytically removed a molecule (H₂O₂) that could have had degradative effects on a protocell. Second, heme could have helped in the synthesis of the building blocks of life by coupling the reduction of H₂O₂ with the oxidation of organic substrates. The necessity of amphiphiles to avoid the formation of inactive complexes of heme is telling, as the modern-day electron transport chain possesses heme embedded within a lipid membrane. Conversely, prebiotic iron-sulfur peptides have yet to be reported to partition into lipid membranes, nor have simple iron-sulfur peptides been found to be capable of participating in the synthesis of organic molecules. Instead, iron-sulfur peptides span a wide range of reduction potentials complementary to the reduction potentials of hemes. The reduction potential of iron-sulfur peptides can be tuned by the type of iron-sulfur cluster formed, e.g., [2Fe-2S] versus [4Fe-4S], or by the substitution of ligands to the metal center. Since iron-sulfur clusters easily form upon stochastic encounters between iron ions, hydrosulfide, and small organic molecules possessing a thiolate, including peptides, the likelihood of soluble iron-sulfur clusters seems to be high. What remains challenging to determine is if iron-sulfur peptides participated in early prebiotic chemistry or were recruited later when protocellular membranes evolved that were compatible with the exploitation of electron transfer for the storage of energy as a proton gradient. This problem mirrors in some ways the difficulty in deciphering the origins of metabolism as a whole. Chemistry that resembles some facets of extant metabolism must have transpired on the prebiotic Earth, but there are few clues as to how and when such chemistry was harnessed to support a (proto)cell. Ultimately, unraveling the roles of hemes and iron-sulfur clusters in prebiotic chemistry promises to deepen our understanding of the origins of life on Earth and aids the search for life elsewhere in the universe. Show less

Dihydroorotate dehydrogenase (DHODH)-mediated ferroptosis defense is a targetable vulnerability in cancer. Currently, only a few DHODH inhibitors have been utilized in clinical practice. To further enhance DHODH targeting, we introduced the mitochondrial targeting group triphenylphosphine (TPP) to brequinar (BRQ), a robust DHODH inhibitor, resulting in the creation of active molecule B2. This compound exhibits heightened anticancer activity, effectively inhibiting proliferation in various cancer cells, and restraining tumor growth in melanoma xenografts in mice. B2 achieves these effects by targeting DHODH, triggering the formation of reactive oxygen species (ROS), promoting mitochondrial lipid peroxidation, and inducing ferroptosis in B16F10 and A375 cells. Surprisingly, B2 significantly downregulates PD-L1 and alleviates immune suppression. Importantly, B2 exhibits no apparent adverse effects in mice. Collectively, these findings highlight that enhancing the mitochondrial targeting capability of the DHODH inhibitor is a promising therapeutic approach for melanoma treatment. Show less

Efforts to identify anti-cancer therapeutics and understand tumor-immune interactions are built with in vitro models that do not match the microenvironmental characteristics of human tissues. Using in vitro models which mimic the physical properties of healthy or cancerous tissues and a physiologically relevant culture medium, we demonstrate that the chemical and physical properties of the microenvironment regulate the composition and topology of the glycocalyx. Remarkably, we find that cancer and age-related changes in the physical properties of the microenvironment are sufficient to adjust immune surveillance via the topology of the glycocalyx, a previously unknown phenomenon observable only with a physiologically relevant culture medium. Show less

Dysregulation of Fibroblast Growth Factor Receptors (FGFRs) signaling has been associated with breast cancer, yet employing FGFR-targeted delivery systems to improve the efficacy of cytotoxic agents is still sparsely exploited. Herein, we report four new bi-functional ruthenium-peptide conjugates (RuPCs) with FGFR-targeting and pH-dependent releasing abilities, envisioning the selective delivery of cytotoxic Ru complexes to FGFR(+)-breast cancer cells, and controlled activation at the acidic tumoral microenvironment. The antiproliferative potential of the RuPCs and free Ru complexes was evaluated in four breast cancer cell lines with different FGFR expression levels (SKBR-3, MDA-MB-134-VI, MCF-7, and MDA-MB-231) and in human dermal fibroblasts (HDF), at pH 6.8 and pH 7.4 aimed at mimicking the tumor microenvironment and normal tissues/bloodstream pHs, respectively. The RuPCs showed higher cytotoxicity in cells with higher level of FGFR expression at acidic pH. Additionally, RuPCs showed up to 6-fold higher activity in the FGFR(+) breast cancer lines compared to the normal cell line. The release profile of Ru complexes from RuPCs corroborates the antiproliferative effects observed. Remarkably, the cytotoxicity and releasing ability of RuPCs were shown to be strongly dependent on the conjugation of the peptide position in the Ru complex. Complementary molecular dynamic simulations and computational calculations were performed to help interpret these findings at the molecular level. In summary, we identified a lead bi-functional RuPC that holds strong potential as a FGFR-targeted chemotherapeutic agent. Show less

Neurobiological research relies heavily on imaging techniques, such as fluorescence microscopy, to understand neurological function and disease processes. However, the number and variety of fluorescent probes available for ex vivo tissue section imaging limits the advance of research in the field. In this review, we outline the current range of fluorescent probes that are available to researchers for ex vivo brain section imaging, including their physical and chemical characteristics, staining targets, and examples of discoveries for which they have been used. This review is organised into sections based on the biological target of the probe, including subcellular organelles, chemical species (e.g., labile metal ions), and pathological phenomenon (e.g., degenerating cells, aggregated proteins). We hope to inspire further development in this field, given the considerable benefits to be gained by the greater availability of suitably sensitive probes that have specificity for important brain tissue targets. Show less

Background Hypoxia is a common feature of many solid tumors and causes radiotherapy and immunotherapy resistance. Pharmacological inhibition of oxidative phosphorylation (OXPHOS) has emerged as a therapeutic strategy to reduce hypoxia. However, the OXPHOS inhibitors tested in clinical trials caused only moderate responses in hypoxia alleviation or trials were terminated due to dose-limiting toxicities. To improve the therapeutic benefit, FDA approved OXPHOS inhibitors (e.g. atovaquone) were conjugated to triphenylphosphonium ­( TPP+) to preferentially target Show less

The NCI60 human tumor cell line screen has been in operation as a service to the cancer research community for more than 30 years. The screen operated with 96-well plates, a 2-day exposure period to test agents, and following cell fixation, a visible absorbance endpoint by the protein-staining dye sulforhodamine B. In this study, we describe the next phase of this important cancer research tool, the HTS384 NCI60 screen. Although the cell lines remain the same, the updated screen is performed with 384-well plates, a 3-day exposure period to test agents, and a luminescent endpoint to measure cell viability based upon cellular ATP content. In this study, a library of 1,003 FDA-approved and investigational small-molecule anticancer agents was screened by the two NCI60 assays. The datasets were compared with a focus on targeted agents with at least six representatives in the library. For many agents, including inhibitors of EGFR, BRAF, MEK, ERK, and PI3K, the patterns of GI50 values were very similar between the screens with strong correlations between those patterns within the dataset from each screen. However, for some groups of targeted agents, including mTOR, BET bromodomain, and NAMPRTase inhibitors, there were limited or no correlations between the two datasets, although the patterns of GI50 values and correlations between those patterns within each dataset were apparent. Beginning in January 2024, the HTS384 NCI60 screen became the free screening service of the NCI to facilitate drug discovery by the cancer research community. Significance: The new NCI60 cell line screen HTS384 shows robust patterns of response to oncology agents and substantial overlap with the classic screen, providing an updated tool for studying therapeutic agents. See related commentary by Colombo and Corsello, p. 2397. Show less

Glioblastoma multiforme (GBM) is the most common highly aggressive malignant brain tumor, with a very limited chance for survival post-diagnosis and post-treatment. Despite significant advancement in GBM genomics implicated in molecularly targeted chemotherapies, the prognosis remains poor and requires new drug discovery approaches. We used fluoropyrimidine 5-fluorouracil (5-FU), an antimetabolite anticancer drug conjugated or 'caged' within a lipophilic Ru(II)-diphosphine (dppe) core formulated as [Ru^II(dppe)₂(5-FU)]PF₆ (Ru-DPPE-5FU), where dppe = 1,2-bis(diphenylphosphino)ethane, and evaluated its in vitro cytotoxicity in depth with aggressive GBM cells (LN229). The hydrophilic nature of 5-FU limits its passage through the blood-brain barrier (BBB), which prevents its effective accumulation and efficacy for GBM tumors. Herein, we attempted to modulate the lipophilicity of 5-FU by inserting it within a well-designed lipophilic {Ru(dppe)₂}-core with anticipated higher efficiency towards GBM. The physicochemical properties of [Ru^II(dppe)₂(5-FU)]PF₆ (Ru-DPPE-5FU) were studied using various spectroscopic and analytical techniques. The molecular structure was determined using X-ray crystallography, showing a distorted {RuP₄NO} octahedral geometry with bidentate (N, O) binding of 5-FU and its aromatization in the Ru(II)-bound form. The ³¹P-NMR spectra of Ru-DPPE-5FU showed four closely spaced distinct ³¹P-signals, indicating four unique chemical environments around P, and the strong coupling constants between them make it a second-order spectrum. The Ru^II/Ru^III redox potential in Ru-DPPE-5FU shifted by ∼0.91 V towards the anodic region as compared to its precursor complex cis-[Ru(dppe)₂Cl₂] (Ru-DPPE-Cl). DFT-based theoretical calculations have been performed to correlate the experimental electronic absorption spectra and redox behaviours of the complexes. The electrostatic potential (ESP) plots indicate the delocalization of the charge density on the O-/F-atom from the 5-FU ligand towards Ru(II) upon its complexation. The antioxidant properties of all the compounds were quantified by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The hyphenation of the 5-fluorouracil (5-FU) ligand to the lipophilic {Ru(dppe)₂}-core endowed lipophilicity to Ru-DPPE-5FU with higher in vitro cytotoxicity (IC₅₀ = 2.37 μM) against the LN229 GBM cells as compared to the hydrophilic 5-FU, suggesting efficient cellular uptake. Further biological assays indicated that the complex is highly potent in inhibiting significant proliferation and spheroid formation and restricting the migratory potentials of the GBM cells. Increased caspase 3/7 activity and the presence of apoptotic bodies at the center of 3-D GBM spheroids as revealed by AO/EB dual staining indicated a deeper penetration of the lipophilic complex. The Ru-DPPE-5FU complex displayed lower cytotoxicity in HaCaT normal cells (IC₅₀ = 7.27 μM) in comparison to LN229 cancer cells with a selectivity index (S.I.) of ≥3. Overall, the synergism and caging of 5-FU within the hydrophobic {Ru(dppe)₂}-core improves the pharmacokinetic profile of Ru-DPPE-5FU as a potent anticancer agent for glioblastoma. Show less

Reactive oxygen species are essential molecules that are generated and eliminated through complex balanced mechanisms. Increased reactive oxygen species levels have a role in tumour development, and targeting reactive oxygen species and their regulatory machineries is a promising therapeutic strategy. This Review discusses recent research developments in the field, their implications for cancer drug discovery, as well as emerging concepts and future perspectives. Show less

The endoplasmic reticulum plays an important role in maintaining the protein homeostasis of cells as well as regulating Ca2+ storage. An increased load of unfolded proteins in the endoplasmic reticulum due to alterations in the cell's metabolic pathway leads to the activation of the unfolded protein response, also known as ER stress. ER stress plays a major role in maintaining the growth and survival of various cancer cells, but persistent ER stress can also lead to cell death and hence can be a therapeutic pathway in the treatment of cancer. In this review, we focus on different types of small molecules that impair different ER stress sensors, the protein degradation machinery, and chaperone proteins. We also review the metal complexes and other miscellaneous compounds inducing ER stress through multiple mechanisms. Finally, we discuss the challenges in this emerging area of research and the potential direction of research to overcome them towards next-generation ER-targeted cancer therapy. Show less

Title: Exploring the phototoxicity of GSH-resistant 2-(5,6-dichloro-1 Abstract: Metal complexes play a crucial role in photo-activated chemotherapy (PACT), which has recently been used to treat specific disorders. Triple-negative breast cancer has an enormously high rate of relapse due to the existence and survival of cancer stem cells (CSCs) characterized by increased amounts of glutathione (GSH). Hence, designing a phototoxic molecule is an enticing area of research to combat triple-negative breast cancer (TNBC) via GSH depletion and DNA photocleavage. Herein, we focus on the application of PTA and non-PTA Ir(III) complexes for phototoxicity in the absence and presence of GSH against MDA-MB-231 TNBC cells. Between these two complexes, [Cp*IrIII(DD)PTA]·2Cl (DDIRP) exhibited better phototoxicity (IC50 ∼ 2.80 ± 0.52 μM) compared to the non-PTA complex [Cp*IrIII(DD)Cl]·Cl (DDIR) against TNBC cells because of the high GSH resistance power of the complex DDIRP. The significant potency of the complex DDIRP under photo irradiation in both normoxia and hypoxia conditions can be attributed to selective transportation, high cellular permeability and uptake towards the nucleus, GSH depletion by GSH-GSSG conversion, the ability of strong DNA binding including intercalation, and oxidative stress. The strong affinity to serum albumin, which serves as a carrier protein, aids in the transport of the complex to its target site while preventing glutathione (GSH) deactivation. Consequently, the complex DDIRP was developed as a suitable phototoxic complex in selective cancer therapy, ruling over the usual chemotherapeutic drug cisplatin and the PDT drug Photofrin. The ability of ROS generation under hypoxic conditions delivers this complex as a hypoxia-efficient selective metallodrug for the treatment of TNBC. Show less

Over the past three decades, high-throughput phenotypic cancer cell line screens have revealed unanticipated small-molecule activities and illuminated connections between tumor genotypes and anticancer efficacy. Founded in 1984, the National Cancer Institute's "NCI60" screen laid the conceptual groundwork for the contemporary landscape of phenotypic drug discovery. NCI60 first operated as a primary bioactivity screen, but molecular characterization of the NCI60 cell line panel and development of a small-molecule sensitivity pattern recognition algorithm (called "COMPARE") have enabled subsequent studies into drug mechanisms of action and biomarker identification. In this issue of Cancer Research, Kunkel and colleagues report an updated version of the NCI60 screen, dubbed "HTS384" NCI60, that better aligns with current cell proliferation assay standards and has higher throughput. Changes include the use of a 384-well plate format, automated laboratory equipment, 3 days of compound exposure, and a CellTiter-Glo luminescent endpoint. To confirm that data from the HTS384 and classic NCI60 screen are comparable, the authors tested a library of 1,003 anticancer agents using both protocols and applied COMPARE to analyze patterns of cell line sensitivities. More than three dozen groups of targeted therapies showed high comparability between screens. Modernization of NCI60, and closer integration with other large-scale pharmacogenomic screens and molecular feature sets, will help this public screening service remain pertinent for cancer drug discovery efforts for years to come. See related article by Kunkel et al., p. 2403. Show less

Title: Induction of ferroptosis of iridium(III) complexes localizing at the mitochondria and lysosome by photodynamic therapy. Abstract: In this study, [Ir(ppy)2(DMHBT)](PF6) (ppy = deprotonated 1-phenylpyridine, DMHBT = 10,12-dimethylpteridino[6,7-f][1,10]phenanthroline-11,13-(10,12H)-dione, 8a), [Ir(bzq)2(DMHBT)](PF6) (bzq = deprotonated benzo[h]quinoline, 8b) and [Ir(piq)2(DMHBT)](PF6) (piq = deprotonated 1-phenylisoquinoline, 8c) were synthesized and characterized by HRMS, 13C NMR and 1H NMR. In vitro cytotoxicity experiments showed that 8a, 8b, 8c show moderate cytotoxicity against B16 cells, while the cytotoxicity of the complexes 8a, 8b and 8c toward B16 cells was greatly improved upon light irradiation, which can be used as photosensitizers to exert anticancer efficacy in photodynamic therapy (PDT). After being taken up by cells, 8a, 8b, 8c were localized in the mitochondria, resulting in a large amount of Ca2+ in-flux, a burst release of ROS, a sustained opening of mitochondrial permeability transition pore, and a decrease of the mitochondrial membrane potential, which led to mitochondrial dysfunction and further activation of caspase 3 and Bcl-2 family proteins to induce apoptosis. Overloaded ROS reacted with polyunsaturated fatty acids on the cell membrane, and initiated lipid peroxidation, inhibited the xc--system-glutathione (GSH)-glutathione peroxidase 4 (GPX4) antioxidant defense system, and upregulated the expression of the damage-associated molecules, HMGB1, CRT, and HSP70. The presence of Fer-1 was effective on increasing the cell survival, which demonstrates that the complexes possess the potential to induce ferroptosis and immunogenic cell death. In addition, 8a, 8b and 8c induced autophagy by inhibiting the AKT/PI3K/mTOR signaling pathway, downregulating p62 and promoting Beclin-1 expression upon light irradiation. Show less

Autophagy is a crucial quality control mechanism that degrades damaged cellular components through lysosomal fusion with autophagosomes. However, elevated autophagy levels can promote drug resistance in cancer cells, enhancing their survival. Downregulation of autophagy through oxidative stress is a clinically promising strategy to counteract drug resistance, yet precise control of oxidative stress in autophagic proteins remains challenging. Here, a molecular design strategy of biocompatible neutral Ir(III) photosensitizers is demonstrated, B2 and B4, for precise reactive oxygen species (ROS) control at lysosomes to inhibit autophagy. The underlying molecular mechanisms for the biocompatibility and lysosome selectivity of Ir(III) complexes are explored by comparing B2 with the cationic or the non-lysosome-targeting analogs. Also, the biological mechanisms for autophagy inhibition via lysosomal oxidation are explored. Proteome analyses reveal significant oxidation of proteins essential for autophagy, including lysosomal and fusion-mediator proteins. These findings are verified in vitro, using mass spectrometry, live cell imaging, and a model SNARE complex. The anti-tumor efficacy of the precise lysosomal oxidation strategy is further validated in vivo with B4, engineered for red light absorbance. This study is expected to inspire the therapeutic use of spatiotemporal ROS control for sophisticated modulation of autophagy. Show less

AbstractA series of gold (I) phoshpine complexes with diverse alkynyl ligands [Au(C≡CR)(PTA)] (R=C6H11OH, 1; C5H9OH, 2; C15H11OH, 3; C19H27O2, 4; C18H23O2, 5; C9H12N, 6; CH2OCH2C6H5, 7; C6H4OCH3, 8; PTA=1,3,5‐Triaza‐7‐phosphaadamantane) have been synthesized and characterized using a range of spectroscopic techniques. Complex 1 and 3 show an infinite one–dimensional S–type and zigzag aurophilic chain, respectively, whereas complex 2 containing 1‐ethynyl‐1‐cyclohexanol gives an approximate linear two–dimensional aurophilic chain, through intra/intermolecular Au(I)⋯Au(I) interactions as well as hydrogen bonding interactions between hydroxy groups of alkynyl ligands and PTA. Solid complexes 1–8 display strongly room/low–temperature emissive of 477–613 nm with the emission lifetime of 0.40–14.0 μs. All the complexes display higher cytotoxicities against MCF‐7, with the cytotoxicity decreasing in the following order 4>8>5>3>7>6>2>1. Complex 4 and 5 stand out for the highest selectivity towards MCF–7 (IC50=0.63–0.78 μM) compared with normal human embryonic lung fibroblasts (helf) (IC50=14.85–18.13 μM), which makes those complexes attractive for breast cancer therapy. Show less

Nitrogen-rich energetic materials are of interest due to their potential use as high-energy-density materials in various applications. However, most compounds with a high nitrogen content show poor thermal stabilities, which may limit their use in certain applications. In pursuit of nitrogen-rich energetic materials, this study presents the synthesis and characterization of two nitrogen rich energetic compounds, namely 3-azido-1-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (3, C₃H₃N₁₁, N%: 79.78) and (E)-1,2-bis(3-azido-1-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-yl) diazene (7, C₆H₂N₂₂, N%: 80.62). Compounds 3 and 7 have high thermal stabilities of 216 and 221 °C, respectively, making them the most thermally stable among metal-free primary explosives. Additionally, they show good energetic performance (v_D: 8345 m s^-1; P: 25.17 GPa; v_D: 8275 m s^-1; P: 25.57 GPa), making them potential candidates for metal-free high energy primary explosive. The energetic salts of 3 and 7 were also investigated. Among them, hydrazinium salt 11 displays better energetic performance (v_D: 9089 m s^-1; P: 30.55 GPa), which was on par with those of cyclotetramethylene tetranitramine (HMX). This research contributes to the exploration of nitrogen-rich energetic materials with potential applications in various fields. Show less

Nucleotide excision repair (NER) is vital for genome integrity. Yet, our understanding of the complex NER protein machinery remains incomplete. Combining cryo-EM and XL-MS data with AlphaFold2 predictions, we build an integrative model of the NER pre-incision complex(PInC). Here TFIIH serves as a molecular ruler, defining the DNA bubble size and precisely positioning the XPG and XPF nucleases for incision. Using simulations and graph theoretical analyses, we unveil PInC's assembly, global motions, and partitioning into dynamic communities. Remarkably, XPG caps XPD's DNA-binding groove and bridges both junctions of the DNA bubble, suggesting a novel coordination mechanism of PInC's dual incision. XPA rigging interlaces XPF/ERCC1 with RPA, XPD, XPB, and 5' ssDNA, exposing XPA's crucial role in licensing the XPF/ERCC1 incision. Mapping disease mutations onto our models reveals clustering into distinct mechanistic classes, elucidating xeroderma pigmentosum and Cockayne syndrome disease etiology. Show less

Morpholine motifs have been used extensively as targeting moieties for lysosomes, primarily in fluorescence imaging agents. Traditionally these imaging agents are based on organic molecules which have several shortcomings including small Stokes shifts, short emission lifetimes, and susceptibility to photobleaching. To explore alternative lysosome targeting imaging agents we have used a rhenium based phosphorescent platform which has been previously demonstrated to have an improved Stokes shift, a long lifetime emission, and is highly photostable. Rhenium complexes containing morpholine substituted ligands were designed to accumulate in acidic compartments. Two of the three complexes prepared exhibited bright emission in cells, when incubated at low concentrations (20 μM) and were non-toxic at concentrations as high as 100 μM, making them suitable for live cell imaging. We show that the rhenium complexes are amenable to chemical modification and that the morpholine targeted derivatives can be used for live cell confocal fluorescence imaging of endosomes–lysosomes. Show less

Title: New cyclometalated iridium(III) complexes bearing substituted 2-(1H-benzimidazol-2-yl)quinoline: Synthesis, characterization, electrochemical and anticancer studies. Abstract: New iridium(III) compounds (C1-C3) bearing 2-(1H-benzimidazol-2-yl)quinoline ligands with different side groups (benzyl, 2,3,4,5,6-pentamethylbenzyl and 2,3,4,5,6-pentafluorobenzyl) were synthesized and characterized by using spectroscopic analyses. The effects of different side groups of iridium compounds on the photophysical and electrochemical properties have been investigated. The cytotoxicity and apoptosis of the compounds have been evaluated on breast cancer cell lines using various methods including MTT assay, flow cytometry, qRT-PCR, and colony formation. The cytotoxicity of C1, expressed as IC50 values, was found to be 11.76 μM for MDA-MB-231 and 5.35 μM for MCF-7 cells. For C3, the IC50 value was 16.22 μM for MDA-MB-231 and 8.85 μM for MCF-7 cells. In both cell lines, increased levels of Bax and caspase 3, along with downregulation of BCL-2 and positive annexin V staining, were observed, confirming apoptosis. Moreover, the colony-forming abilities in both cell lines decreased after C1 and C3 complex treatment. All these results suggest that the compounds C1 and C3 may have potential in the treatment of breast cancer, though further research is needed to confirm their efficacy. Show less

“Reprogramming of energy metabolism” was first considered an emerging hallmark of cancer in 2011 by Hanahan & Weinberg and is now considered a core hallmark of cancer. Mitochondria are the hubs of metabolism, crucial for energetic functions and cellular homeostasis. The mitochondrion’s bacterial origin and preservation of their own genome, which encodes proteins and RNAs essential to their function, make them unique organelles. Successful generation of mitochondrial gene products requires coordinated functioning of the mitochondrial ‘central dogma,’ encompassing all steps necessary for mtDNA to yield mitochondrial proteins. Each of these processes has several levels of regulation, including mtDNA accessibility and protection through mtDNA packaging and epigenetic modifications, mtDNA copy number through mitochondrial replication, mitochondrial transcription through mitochondrial transcription factors, and mitochondrial translation through mitoribosome formation. Deregulation of these mitochondrial processes in the context of cancers has only recently been appreciated, with most studies being correlative in nature. Nonetheless, numerous significant associations of the mitochondrial central dogma with pro-tumor phenotypes have been documented. Several studies have even provided mechanistic insights and further demonstrated successful pharmacologic targeting strategies. Based on the emergent importance of mitochondria for cancer biology and therapeutics, it is becoming increasingly important that we gain an understanding of the underpinning mechanisms so they can be successfully therapeutically targeted. It is expected that this mechanistic understanding will result in mitochondria-targeting approaches that balance anticancer potency with normal cell toxicity. This review will focus on current evidence for the dysregulation of mitochondrial gene expression in cancers, as well as therapeutic opportunities on the horizon. Show less

Advances in high-throughput high-resolution mass spectrometry and the development of thermal proteome profiling approach (TPP) have made it possible to accelerate a drug target search. Since its introduction in 2014, TPP quickly became a method of choice in chemical proteomics for identifying drug-to-protein interactions on a proteome-wide scale and mapping the pathways of these interactions, thus further elucidating the unknown mechanisms of action of a drug under study. However, the current TPP implementations based on tandem mass spectrometry (MS/MS), associated with employing lengthy peptide separation protocols and expensive labeling techniques for sample multiplexing, limit the scaling of this approach for the ever growing variety of drug-to-proteomes. A variety of ultrafast proteomics methods have been developed in the last couple of years. Among them, DirectMS1 provides MS/MS-free quantitative proteome-wide analysis in 5-min time scale, thus opening the way for sample-hungry applications, such as TPP. In this work, we demonstrate the first implementation of the TPP approach using the ultrafast proteome-wide analysis based on DirectMS1. Using a drug topotecan, which is a known topoisomerase I (TOP1) inhibitor, the feasibility of the method for identifying drug targets at the whole proteome level was demonstrated for an ovarian cancer cell line. Graphical Abstract Show less

Title: Polydiacetylene/lipid-coated red-emissive silica nanorods for the sustained release and ameliorated anticancer efficacy of a Ru(arene) complex bearing piperlongumine natural product. Abstract: A suitable drug delivery strategy for metallodrugs is as significant as the strategies adopted for an efficient metallodrug design. In this study, piperlongumine, which is isolated from long pepper, is coordinated with a Ru(II)-p-cymene moiety to obtain an organoruthenated complex containing the natural product (Ru(pip)). The isolated complex shows higher cytotoxicity in MCF-7 breast cancer cells than in THP-1 leukemia and HepG2 liver cancer cells. The IC50 value of the complex in non-cancerous HEK-239 cells is also almost equal to that in MCF-7 cells. Next, with an aim to modulate the antiproliferative activity of Ru(pip) using a drug delivery strategy, the complex is loaded into mesoporous silica nanorods (MSNRs), which have a higher surface area than spherical silica nanoparticles. Furthermore, the outer surface of the loaded nanorods is covered with a polydiacetylene-lipid (PL) hybrid bilayer. Given the unique optical properties of polydiacetylene, the PL coating modifies non-fluorescent MSNRs into red-emissive particles (PL-Ru(pip)@MSNRs), which can be useful for diagnostic applications. The release profile studies reveal that the ene-yne conjugation in the PL coating ensures the sustained release of the complex from nanoparticles in both physiological and simulated cancer cell media. While Ru(pip) exhibits both necrotic and apoptotic modes of cell death, PL-Ru(pip)@MSNRs preferably induce the apoptotic mode of cell death in MCF-7 and THP-1 cells. Also, the nanoformulation exhibits a higher percentage of cell cycle arrest in the G0/G1 phase than Ru(pip), as measured by flow cytometry analysis. In contrast, the in vitro antioxidant potency of the complex is decreased after being loaded into PL-coated silica nanoparticles. Show less

Title: Microtubule-Targeting NAP Peptide-Ru(II)-polypyridyl Conjugate As a Bimodal Therapeutic Agent for Triple Negative Breast Carcinoma. Abstract: Triple-negative breast cancer (TNBC) poses significant treatment challenges due to its high metastasis, heterogeneity, and poor biomarker expression. The N-terminus of an octapeptide NAPVSIPQ (NAP) was covalently coupled to a carboxylic acid derivative of Ru(2,2'-bipy)32+ (Rubpy) to synthesize an N-stapled short peptide-Rubpy conjugate (Ru-NAP). This photosensitizer (PS) was utilized to treat TNBC through microtubule (MT) targeted chemotherapy and photodynamic therapy (PDT). Ru-NAP formed more elaborate molecular aggregates with fibrillar morphology as compared to NAP. A much higher binding affinity of Ru-NAP over NAP toward β-tubulin (KRu-NAP: (6.8 ± 0.55) × 106 M-1; KNAP: (8.2 ± 1.1) × 104 M-1) was observed due to stronger electrostatic interactions between the MT with an average linear charge density of ∼85 e/nm and the cationic Rubpy part of Ru-NAP. This was also supported by docking, simulation, and appropriate imaging studies. Ru-NAP promoted serum stability, specific binding of NAP to the E-site of the βIII-tubulin followed by the disruption of the MT network, and effective singlet oxygen generation in TNBC cells (MDA-MB-231), causing cell cycle arrest in the G2/M phase and triggering apoptosis. Remarkably, MDA-MB-231 cells were more sensitive to Ru-NAP compared to noncancerous human embryonic kidney (HEK293 cells) when exposed to light (LightIC50Ru-NAP[HEK293]: 17.2 ± 2.5 μM, compared to LightIC50Ru-NAP[MDA-MB-231]: 32.5 ± 7.8 nM, DarkIC50Ru-NAP[HEK293]: > 80 μM, compared to DarkIC50Ru-NAP[MDA-MB-231]: 2.9 ± 0.5 μM). Ru-NAP also effectively inhibited tumor growth in MDA-MB-231 xenograft models in nude mice. Our findings provide strong evidence that Ru-NAP has a potential therapeutic role in TNBC treatment. Show less

DNA damage occurs throughout life from a variety of sources, and it is imperative to repair damage in a timely manner to maintain genome stability. Thus, DNA repair mechanisms are a fundamental part of life. Nucleotide excision repair (NER) plays an important role in the removal of bulky DNA adducts, such as cyclobutane pyrimidine dimers from ultraviolet light or DNA crosslinking damage from platinum-based chemotherapeutics, such as cisplatin. A main component for the NER pathway is transcription factor IIH (TFIIH), a multifunctional, 10-subunit protein complex with crucial roles in both transcription and NER. In transcription, TFIIH is a component of the pre-initiation complex and is important for promoter opening and the phosphorylation of RNA Polymerase II (RNA Pol II). During repair, TFIIH is important for DNA unwinding, recruitment of downstream repair factors, and verification of the bulky lesion. Several different disease states can arise from mutations within subunits of the TFIIH complex. Most strikingly are xeroderma pigmentosum (XP), XP combined with Cockayne syndrome (CS), and trichothiodystrophy (TTD). Here, we summarize the recruitment and functions of TFIIH in the two NER subpathways, global genomic (GG-NER) and transcription-coupled NER (TC-NER). We will also discuss how TFIIH's roles in the two subpathways lead to different genetic disorders. Show less