G-4 inhibits triple negative breast cancer by inducing cell apoptosis and promoting LCN2-dependent ferroptosis.

Compound G-4 is a derivate of cyclin-dependent kinase inhibitor Rocovitine and showed strong sensitivity to triple negative breast cancer (TNBC) cells. In this study, the antitumor activity, mechanism and possible targets of G-4 in TNBC were investigated. Flow cytometry and immunoblotting showed that G-4 not only arrested the S phase of the cell cycle, but also induced apoptosis in TNBC cells via the mitochondrial pathway through inhibiting epidermal growth factor receptor (EGFR), AKT and MAPK pathways. In addition, G-4 induced the iron-mutagenesis process in TNBC cells and down-regulated differentially expressed gene lipid carrier protein 2 (LCN2) by RNA-seq. Moreover, G-4 elevated levels of cytosolic reactive oxygen species (ROS), lipid ROS, Fe and malondialdehyde (MDA), but decreased levels of superoxide dismutase (SOD) and glutathione (GSH), consistent with the effects of iron-mutagenic agonists Erastin and RSL3, which were inhibited by the iron inhibitor ferrostatin-1 (Fer-1). Furthermore, a LCN2 knockdown cell model was established by siRNA transfection, the IC50 of G-4 was increased nearly 100-fold, accompanied by a trend of no ferroptosis characteristic index. The results indicated that G-4 suppressed the malignant phenotype of TNBC, induced apoptosis by inhibiting EGFR pathway and promoted LCN2-dependent ferroptosis.

Synthesis and mechanism of action of new purine derivatives against triple negative breast cancer.

Triple negative breast cancer (TNBC) is considered to be the most difficult subtype of breast cancer to treat because of its extremely prone to metastasis and the lack of targeted therapy drugs. New purine derivatives were synthesized and evaluated in a series of kinases and cell lines. The most active compounds 3g and 3j were selected based on their antiproliferative activities, then their pharmaceutical activity and mechanism in MDA-MB-231 cells were analyzed. The results in vitro indicated that compounds 3g and 3j can induce MDA-MB-231 cells apoptosis, and inhibit its migration and angiogenesis through influencing protein expression such as Bcl-2, Bax, Bcl-xl, P38, MMP2, MMP9, AKT and EGFR. In vivo results indicate that compounds 3g and 3j can inhibit tumor growth and metastasis and reduce the expression of Ki67 and CD31 protein in TNBC xenograft models. These findings not only broaden our understanding of the anti-TNBC effects and mechanisms of compounds 3g and 3j, but also provide new ideas and reference directions for the treatment of TNBC.

Molecular mechanisms in Alzheimer's disease and related potential treatments such as structural target convergence of antibodies and simple organic molecules.

The amyloid cascade is the most frequently accepted hypothesis of Alzheimer's Disease (AD). According to this hypothesis, the formation of plaques precedes the appearance of fibrillary tangles. Therapeutic agents able to inhibit the formation of plaques are therefore considered as potential disease-modifying treatments (DMT) that could prevent or limit the progression of AD. Plaques are deposits formed by aggregates of amyloid-ß (Aß)-peptides. These peptides are metabolites of amyloid precursor protein (APP) first mediated by two enzymes: ß-secretase 1 (BACE1) and γ-secretase. Molecular identification of these two enzymes has stimulated the development of their inhibitors. The clinical testing of these two classes of molecules has not been successful to date. The oligomerization of Aß-peptides into plaques is now targeted by immunological approaches such as antibodies and vaccines. Structural consideration of the Aß-peptide sequence led to the launch of the antibody Aducanumab. Several other antibodies are in late clinical phases. Progress in the understanding of the effects of N-truncated Aß-peptides such as pE3-42, formed by the action of recently well characterized enzymes (aminopeptidase A, dipeptidylpeptidase-4 and glutaminyl cyclase) suggests that oligomerization can be limited either by enzyme inhibitors or antibody approaches. This strategy associating two structurally interconnected mechanisms is focused in this review.

Co-delivery of F7 and crizotinib by thermosensitive liposome for breast cancer treatment.

In order to enhance the targeting efficiency and reduce the side effects and drug resistance, crizotinib (Cri) and F7 were co-loaded in a thermosensitive liposome (TSL) (F7-Cri-TSL), which showed enhanced permeability and retention in breast cancer model, as well as local controlled release by external hyperthermia. Cri is an inhibitor for cell proliferation and a promoter of apoptosis, by inhibiting the phosphorylation of intracellular ALK and c-Met, but its drug resistance limits its application. F7 is a novel drug candidate with significant resistance to cyclin-dependent kinase, but its use was restricted by its high toxicity. The F7-Cri-TSL was found with excellent particle size (about 108 nm), high entrapment efficiency (>95%), significant thermosensitive property, and good stability. Furthermore, F7-Cri-TSL/H had strongest cell lethality compared with other formulations. On the MCF-7 xenograft mice model, the F7-Cri-TSL also exhibited therapeutic synergism of Cri, F7 and hyperthermia. Meanwhile, it was shown that the TSL reduced the systemic toxicity of the chemotherapy drug. Therefore, the F7-Cri-TSL may serve as a promising system for temperature triggered breast cancer treatment.

Exosomes from different cells: Characteristics, modifications, and therapeutic applications.

Exosomes are cystic vesicles secreted by living cells with a phospholipid bilayer membrane. Importantly, these vesicles could serve to carry lipids, proteins, genetic materials, and transmit biological information in vivo. The cell-specific proteins and genetic materials in exosomes are capable of reflecting their cell origin and physiological status. Based on the different tissues and cells (macrophage, dendritic cells, tumor cells, mesenchymal stem cells, various body fluids, and so on), exosomes exhibit different characteristics and functions. Furthermore, owing to their high delivery efficiency, biocompatibility, and multifunctional properties, exosomes are expected to become a new means of drug delivery, disease diagnosis, immunotherapy, and precise treatment. At the same time, in order to supplement or enhance the therapeutic applicability of exosomes, chemical or biological modifications can be used to broaden, change or improve their therapeutic capabilities. This review focuses on three aspects: the characteristics and original functions of exosomes secreted by different cells, the modification and transformation of exosomes, and the application of exosomes in different diseases.

Author Correction: A Small Compound Targeting Prohibitin with Potential Interest for Cognitive Deficit Rescue in Aging mice and Tau Pathology Treatment.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

F7 and topotecan co-loaded thermosensitive liposome as a nano-drug delivery system for tumor hyperthermia.

In order to enhance the targeting efficiency and reduce anti-tumor drug's side effects, topotecan (TPT) and F7 were co-loaded in thermosensitive liposomes (F7-TPT-TSL), which show enhanced permeability and retention in tumors, as well as local controlled release by heating in vitro. TPT is a water-soluble inhibitor of topoisomerase I that is converted to an inactive carboxylate structure under physiological conditions (pH 7.4). F7 is a novel drug significantly resistant to cyclin-dependent kinase but its use was restricted by its high toxicity. F7-TPT-TSL had excellent particle distribution (about 103 nm), high entrapment efficiency (>95%), obvious thermosensitive property, and good stability. Confocal microscopy demonstrated specific higher accumulation of TSL in tumor cells. MTT proved F7-TPT-TSL/H had strongest cell lethality compared with other formulations. Then therapeutic efficacy revealed synergism of TPT and F7 co-loaded in TSL, together with hyperthermia. Therefore, the F7-TPT-TSL may serve as a promising system for temperature triggered cancer treatment.

A Small Compound Targeting Prohibitin with Potential Interest for Cognitive Deficit Rescue in Aging mice and Tau Pathology Treatment.

Neurodegenerative diseases, including Alzheimer's and Parkinson's disease, are characterized by increased protein aggregation in the brain, progressive neuronal loss, increased inflammation, and neurogenesis impairment. We analyzed the effects of a new purine derivative drug, PDD005, in attenuating mechanisms involved in the pathogenesis of neurodegenerative diseases, using both in vivo and in vitro models. We show that PDD005 is distributed to the brain and can rescue cognitive deficits associated with aging in mice. Treatment with PDD005 prevents impairment of neurogenesis by increasing sex-determining region Y-box 2, nestin, and also enhances synaptic function through upregulation of synaptophysin and postsynaptic density protein 95. PDD005 treatment also reduced neuro-inflammation by decreasing interleukin-1ß expression, activation of astrocytes, and microglia. We identified prohibitin as a potential target in mediating the therapeutic effects of PDD005 for the treatment of cognitive deficit in aging mice. Additionally, in the current study, glycogen synthase kinase appears to attenuate tau pathology.

Recent advances in the development of cyclin-dependent kinase 7 inhibitors.

Cyclin dependent kinase 7 (CDK7) plays a double role as it activates several other cyclin dependent kinases and participates to the initiation of transcription. This kinase is overexpressed in various types of tumors. Relatively few selective CDK7 inhibitors have been up to now disclosed. Most of these inhibitors belong to two chemical families: pyrazolopyrimidines and pyrazolotriazines on one side and pyrimidines on another side. They also differ by their molecular mechanism of action. Some are acting as competitive inhibitors and some others are covalent inhibitors. With these tools, the understanding of the potential therapeutic interest of CDK7 inhibitors in cancer is rapidly growing. They display antiproliferative activity against various types of tumors and leukemia and synergies have been identified. Two inhibitors are undergoing clinical testing. The most potent compounds inhibit a large number of cell-lines with IC50 < 200 nM.

Composition design and medical application of liposomes.

Liposomes, which possess the properties of nano-scale, biofilm similar structure, excellent biocompatibility, become more and more useful in the drug development as the delivery system. Liposomes are relatively stable, their aqueous phase could contain the hydrophilic drugs and their phospholipid bilayer should localize the lipophilic drugs. Moreover, their surface-modifiable characteristics have really extended the liposomes' application to targeting and environmental sensitive delivery system. In order to make the common liposome more fit the human and animal body's complex environment, the structural variation strategy in the head, tail and bond of lipid molecules have been employed to develop the different functionalized liposomes-based drug delivery system for the localizable relieve and organ/tissue targeting relieve. In this paper, we would like to summarize the recent development on the design and optimization of liposomes, including Long-circulation liposomes, Specific active targeting liposomes, Environmental sensitive liposomes, Multifunctional liposomes, and so on. And the liposome content selection and current status of clinical application are systematically discussed.

5-Acetamido-1-(methoxybenzyl) isatin inhibits tumor cell proliferation, migration, and angiogenesis.

Indole and its derivatives are widely distributed in both animals and plants. Among its array of biological activities, the anti-tumor activity of indole has garnered much attention. Furthermore, the synthesis and activity of indole derivatives, including isatin, constitute a flourishing research topic. Previously, many isatin derivatives were synthesized by our group, and 5-acetamido-1-(methoxybenzyl) isatin was screened as a candidate anti-tumor agent. In this study, we found that 5-acetamido-1-(methoxybenzyl) isatin inhibited the proliferation of several tumor cell lines, especially the human leukemia cell line K562. Morphological observation suggested that 5-acetamido-1-(methoxybenzyl) isatin induced apoptosis and caused cell cycle arrest in K562 cells. Flow cytometry revealed that 5-acetamido-1-(methoxybenzyl) isatin induced mitochondrial pathway-mediated apoptosis in K562 cells. Moreover, it downregulated Cyclin B and CDC25C and upregulated p-CDC25C and p-CDK1 (Thr14), and induced K562 cell cycle arrest in the G2/M phase. Findings from wound healing as well as transwell assay determined that 5-acetamido-1-(methoxybenzyl) isatin could suppress migration and chemotaxis in HepG2 liver cancer cells. 5-Acetamido-1-(methoxybenzyl) isatin also inhibited angiogenesis of the human umbilical vein endothelial cell line HUVEC, determined via a cell tube formation study. A clone formation study indicated that 5-acetamido-1-(methoxybenzyl) isatin can inhibit tumor cell proliferation and population dependence in a concentration-dependent manner. Thus, our findings support that 5-acetamido-1-(methoxybenzyl) isatin could be used as a potential antitumor candidate in future investigations.

A ß-glucuronidase-responsive albumin-binding prodrug for potential selective kinase inhibitor-based cancer chemotherapy.

We report on the synthesis and in vitro biological evaluations of a nanomolar protein kinase inhibitor (PKI) and its ß-glucuronidase-responsive albumin-binding prodrug. The highly potent PKI is 400-3400 times more cytotoxic than the well-known PKI Roscovitine. The prodrug is able to bind covalently to human serum albumin through Michael addition and release the cytotoxic PKI in the presence of ß-glucuronidase, an enzyme over-expressed in the microenvironment of solid tumours.

One-pot synthesis of ß-lactams by the Ugi and Michael addition cascade reaction.

Diversity-oriented synthesis of ß-lactams was achieved via Ugi/Michael reaction cascades under mild conditions. The intramolecular hydrogen bonding between the heteroatom from an aldehyde component and the amide NH group controls the chemoselectivity of the Michael reaction versus the aza-Michael reaction. DFT calculation was performed to clarify the mechanism, chemo-selectivity and diastereoselectivity of this work. This one-pot protocol offers a straightforward method to build a diversified ß-lactam library for drug discovery.

Antioxidant properties of flavonoid derivatives and their hepatoprotective effects on CCl4 induced acute liver injury in mice.

Excessive accumulation of free radicals in the body can cause liver damage, aging, cancer, stroke, and myocardial infarction. Anastatin B, a skeletal flavonoid, was reported to have antioxidant and hepatoprotective effects. Anastatin B derivatives, compound 1 and 2, were synthesized by our group previously. In this study, their antioxidant activity and hepatoprotective mechanism were studied using chemical evaluation methods, a cellular model of hydrogen peroxide (H2O2)-induced oxidative damage, and a mouse model of carbon tetrachloride (CCl4)-induced liver injury. Results from the chemical evaluation suggested that both compounds had good antioxidant power and radical scavenging ability in vitro. MTT assay showed that both compounds had cytoprotective activity in H2O2-treated PC12 cells. Moreover, their hepatoprotective activities evaluated using a mouse model of CCl4-induced liver injury that compared with the model group, pretreatment with compound 1 and 2 significantly decreased alanine transaminase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH), and malondialdehyde (MDA) levels; reduced the liver tissue damage; and increased glutathione content. However, compound 2 was a more effective hepatoprotectant than compound 1 was. Finally, the amount of TNF-α and cytochrome P450 2E1 (CYP2E1) were significantly downregulated in compound 1 and 2 pretreatment groups. Collectively, our findings demonstrate that both compounds have potential antioxidant activity and hepatoprotective effect in vitro and in vivo. Further chemo-biological study and investigation of the compounds' enzymatic targets are ongoing.

A Simple Isomerization of the Purine Scaffold of a Kinase Inhibitor, Roscovitine, Affords a Four- to Seven-Fold Enhancement of Its Affinity for Four CDKs. Could This Be Traced Back to Conjugation-Induced Stiffenings/Loosenings of Rotational Barriers?

Roscovitine is an antitumor purine inhibitor of cyclin-dependent kinase CDK5, for which it displays submicromolar affinity. It reached phase IIb clinical trials in 2007. The search for analogues with improved kinase affinities led recently to an isomer, finisterine, having a nearly 10-fold greater affinity for both CDK5 and CDK9. It solely differs by the displacement of one nitrogen atom in the purine ring, from position 6 to position 9. This has no incidence on the intermolecular interaction of either drug with the neighboring sites that anchor the ring in the recognition site. Quantum chemistry calculations combined with conformational and topological analyses of the impact of the purine ring isomerization of roscovitine and finisterine on its conformational stability show that the modified electronic conjugation, on the other hand, results in a stiffening of the rotational barrier around the extracyclic C-NH bond of finisterine, vicinal to N9, and to which an aryl ring is connected, along with a loosening of the barrier around an extracyclic C6-C bond connecting to a shorter, hydrophobic arm. The first effect is proposed to lead to a lesser hydration entropy of solvation in the case of finisterine, thus to a facilitated desolvation term in the overall energy balances.

Exploration of the imidazo[1,2-b]pyridazine scaffold as a protein kinase inhibitor.

3,6-Disubstituted imidazo[1,2-b]pyridazine derivatives were synthesized to identify new inhibitors of various eukaryotic kinases, including mammalian and protozoan kinases. Among the imidazo[1,2-b]pyridazines tested as kinase inhibitors, several derivatives were selective for DYRKs and CLKs, with IC50 < 100 nM. The characterization of the kinome of several parasites, such as Plasmodium and Leishmania, has pointed out profound divergences between protein kinases of the parasites and those of the host. This led us to investigate the activities of the prepared compounds against 11 parasitic kinases. 3,6-Disubstituted imidazo[1,2-b]pyridazines showed potent inhibition of Plasmodium falciparum CLK1 (PfCLK1). Compound 20a was found to be the most selective product against CLK1 (IC50 = 82 nM), CLK4 (IC50 = 44 nM), DYRK1A (IC50 = 50 nM), and PfCLK1 (IC50 = 32 nM). The compounds were also tested against Leishmania amazonensis. Several compounds showed anti-leishmanial activity at rather high (10 µM) concentration, but were not toxic at 1 µM or 10 µM, as judged by viability assays carried out using a neuroblastoma cell line.

Specific Triazine Herbicides Induce Amyloid-ß42 Production.

Proteolytic cleavage of the amyloid-ß protein precursor (AßPP) by secretases leads to extracellular release of amyloid-ß (Aß) peptides. Increased production of Aß42 over Aß40 and aggregation into oligomers and plaques constitute an Alzheimer's disease (AD) hallmark. Identifying products of the 'human chemical exposome' (HCE) able to induce Aß42 production may be a key to understanding some of the initiating causes of AD and to generate non-genetic, chemically-induced AD animal models. A cell model was used to screen HCE libraries for Aß42 inducers. Out of 3500+ compounds, six triazine herbicides were found that induced a ß- and γ-secretases-dependent, 2-10 fold increase in the production of extracellular Aß42 in various cell lines, primary neuronal cells, and neurons differentiated from human-induced pluripotent stem cells (iPSCs). Immunoprecipitation/mass spectrometry analyses show enhanced production of Aß peptides cleaved at positions 42/43, and reduced production of peptides cleaved at positions 38 and lower, a characteristic of AD. Neurons derived from iPSCs obtained from a familial AD (FAD) patient (AßPP K724N) produced more Aß42 versus Aß40 than neurons derived from healthy controls iPSCs (AßPP WT). Triazines enhanced Aß42 production in both control and AD iPSCs-derived neurons. Triazines also shifted the cleavage pattern of alcadeinα, another γ-secretase substrate, suggesting a direct effect of triazines on γ-secretase activity. In conclusion, several widely used triazines enhance the production of toxic, aggregation prone Aß42/Aß43 amyloids, suggesting the possible existence of environmental "Alzheimerogens" which may contribute to the initiation and propagation of the amyloidogenic process in late-onset AD.

Modulating Innate and Adaptive Immunity by (R)-Roscovitine: Potential Therapeutic Opportunity in Cystic Fibrosis.

(R)-Roscovitine, a pharmacological inhibitor of kinases, is currently in phase II clinical trial as a drug candidate for the treatment of cancers, Cushing's disease and rheumatoid arthritis. We here review the data that support the investigation of (R)-roscovitine as a potential therapeutic agent for the treatment of cystic fibrosis (CF). (R)-Roscovitine displays four independent properties that may favorably combine against CF: (1) it partially protects F508del-CFTR from proteolytic degradation and favors its trafficking to the plasma membrane; (2) by increasing membrane targeting of the TRPC6 ion channel, it rescues acidification in phagolysosomes of CF alveolar macrophages (which show abnormally high pH) and consequently restores their bactericidal activity; (3) its effects on neutrophils (induction of apoptosis), eosinophils (inhibition of degranulation/induction of apoptosis) and lymphocytes (modification of the Th17/Treg balance in favor of the differentiation of anti-inflammatory lymphocytes and reduced production of various interleukins, notably IL-17A) contribute to the resolution of inflammation and restoration of innate immunity, and (4) roscovitine displays analgesic properties in animal pain models. The fact that (R)-roscovitine has undergone extensive preclinical safety/pharmacology studies, and phase I and II clinical trials in cancer patients, encourages its repurposing as a CF drug candidate.