Development of Hsp90 inhibitor to regulate cytokine storms in excessive delayed- and acute inflammation.

BACKGROUND: The surplus cytokines remaining after use in the early stages of the inflammatory response stimulate immune cells even after the response is over, causing a secondary inflammatory response and ultimately damaging the host, which is called a cytokine storm. Inhibiting heat shock protein 90 (Hsp90), which has recently been shown to play an important role in regulating inflammation in various cell types, may help control excessive inflammatory responses and cytokine storms. METHODS: We discovered an anti-inflammatory compound by measuring the inhibitory effect of CD86 expression on spleen DCs (sDCs) using the chemical compounds library of Hsp90 inhibitors. Subsequently, to select the hit compound, the production of cytokines and expression of surface molecules were measured on the bone marrow-derived DCs (BMDCs) and peritoneal macrophages. Then, we analyzed the response of antigen-specific Th1 cells. Finally, we confirmed the effect of the compound using acute lung injury (ALI) and delayed-type hypersensitivity (DTH) models. RESULTS: We identified Be01 as the hit compound, which reduced CD86 expression the most in sDCs. Treatment with Be01 decreased the production of pro-inflammatory cytokines (IL-6, TNF-α, and IL-1ß) in BMDC and peritoneal macrophages stimulated by LPS. Under the DTH model, Be01 treatment reduced ear swelling and pro-inflammatory cytokines in the spleen. Similarly, Be01 treatment in the ALI model decreased neutrophil infiltration and lower levels of secreted cytokines (IL-6, TNF-α). CONCLUSIONS: Reduction of CD80 and CD86 expression on DCs by Be01 indicates reduced secondary inflammatory response by Th1 cells, and reduced release of pro-inflammatory cytokines by peritoneal macrophages may initially control the cytokine storm.

Targeting Heme Oxygenase 2 (HO2) with TiNIR, a Theragnostic Approach for Managing Metastatic Non-Small Cell Lung Cancer.

Despite notable advancements in cancer therapeutics, metastasis remains a primary obstacle impeding a successful prognosis. Our prior study has identified heme oxygenase 2 (HO2) as a promising therapeutic biomarker for the aggressive subsets within tumor. This study aims to systematically evaluate HO2 as a therapeutic target of cancer, with a specific emphasis on its efficacy in addressing cancer metastasis. Through targeted inhibition of HO2 by TiNIR (tumor-initiating cell probe with near infrared), we observed a marked increase in reactive oxygen species. This, in turn, orchestrated the modulation of AKT and cJUN activation, culminating in a substantial attenuation of both proliferation and migration within a metastatic cancer cell model. Furthermore, in a mouse model, clear inhibition of cancer metastasis was unequivocally demonstrated with an HO2 inhibitor administration. These findings underscore the therapeutic promise of targeting HO2 as a strategic intervention to impede cancer metastasis, enhancing the effectiveness of cancer treatments.

Visualization of Metastatic Lung Cancer with TiNIR.

The development of efficient biomarkers and probes for monitoring and treating cancer, specifically metastatic cancer, is a critical research area that can have a significant impact on both patient outcomes and drug discovery. In this context, TiNIR has been developed to detect tumor-initiating cells (TICs), with heme oxygenase 2 (HO2) as a promising therapeutic biomarker for tumor-initiating cells. In this study, TiNIR has demonstrated its effectiveness as an in vivo metastatic lung cancer tracker, highlighting its potential as a valuable tool in cancer research and therapy. The development of innovative approaches that selectively target metastatic cancers represents a promising avenue for improving survival rates and enhancing the quality of life of cancer patients.

Correction: A preliminary study for the development of cleavable linkers using activatable fluorescent probes targeting leucine aminopeptidase.

Correction for 'A preliminary study for the development of cleavable linkers using activatable fluorescent probes targeting leucine aminopeptidase' by Julie Kang et al., Analyst, 2022, https://doi.org/10.1039/d2an01145j.

A preliminary study for the development of cleavable linkers using activatable fluorescent probes targeting leucine aminopeptidase.

Ligand-targeted drugs (LTDs) such as antibody-drug conjugates (ADCs) are currently attracting great attention as an alternative class of therapeutics to conventional chemotherapy for the clinical treatment of cancer. The linker is one of important factors determining the efficacy and toxicity of LTDs. The linker for LTDs should have enough stability during blood circulation, effectively release the payload, and leave no polar moieties in the released payload. However, the drug release activity and plasma stability of cleavable linkers are generally evaluated by complex and sophisticated in vivo techniques containing LC-MS, and the designing of new clinically applicable linkers remains a challenge. In this work, leucine aminopeptidase (LAP)-responsive fluorescent probes were designed as a simple preliminary model to verify whether a peptidase-responsive fluorescent probe can be used as a facile tool for the development of cleavable linkers although LAP is an exopeptidase and can't be a real target for cleavable linkers. LAP-responsive fluorescent probes were prepared by conjugation of a leucine to several xanthene fluorophores through a few linkages with a p-aminobenzyl spacer. The stability tests, kinetic study and live cell imaging of LAP-responsive activatable fluorescent probes demonstrated that the chemical stability and intrinsic activity of the linker for the release of drug can be easily evaluated by a fluorogenic assay. The ex vivo plasma stability test using mice suggested that an enzyme-responsive activatable fluorescent probe can be used as a feasible platform to evaluate the plasma stability of cleavable linkers during blood circulation.

Anti-Inflammatory Effects of Phlebia sp. Extract in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages.

Lichens are a life form in which algae and fungi have a symbiotic relationship and have various biological activities, including anti-inflammatory and antiproliferative activities. This is the first study to investigate the anti-inflammatory activity of a Phlebia sp. fungal extract (PSE) isolated from Peltigera neopolydactyla in lipopolysaccharide- (LPS-) stimulated RAW 264.7 macrophage. PSE reduced the production of the proinflammatory cytokine (tumor necrosis factor-α, interleukin-6, and interleukin-1ß), chemokine (granulocyte-macrophage colony-stimulating factor), nitric oxide, and prostaglandin E2 in the LPS-stimulated RAW264.7 macrophages. Especially, PSE inhibits the phosphorylation of activator protein-1 (AP-1) signaling (c-Fos and c-Jun) and their upstream mitogen-activated protein kinase kinases/mitogen-activated protein kinases (MKK/MAPKs: MKK4, MKK7, and JNK) and finally reduced the production of the inflammatory cytokines. The inhibitory effects mainly act via suppressing JNK-mediated AP-1 rather than the NF-κB pathway. Furthermore, PSE inhibited the production of final inflammatory effector molecules involved in AP-1 signaling, including nitric oxide (NO) and prostaglandin E2 (PGE2). Here, we report that PSE has the potential to be developed as an anti-inflammatory agent.

Induction of Apoptosis in MDA-MB-231 Cells Treated with the Methanol Extract of Lichen Physconia hokkaidensis.

Physconia hokkaidensis methanol extract (PHE) was studied to identify anticancer effects and reveal its mechanism of action by an analysis of cytotoxicity, cell cycles, and apoptosis biomarkers. PHE showed strong cytotoxicity in various cancer cells, including HL-60, HeLa, A549, Hep G2, AGS, MDA-MB-231, and MCF-7. Of these cell lines, the growth of MDA-MB-231 was concentration-dependently suppressed by PHE, but MCF-7 was not affected. MDA-MB-231 cells, triple-negative breast cancer (TNBC) cells, do not express estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2), whereas MCF-7 cells are ER-positive, PR-positive, and HER-2-negative breast cancer cells. The number of cells in sub-G1 phase was increased after 24 h of treatment, and annexin V/PI staining showed that the population size of apoptotic cells was increased by prolonged exposure to PHE. Moreover, PHE treatment downregulated the transcriptional levels of Bcl-2, AMPK, and p-Akt, whereas it significantly upregulated the levels of cleaved caspase-3, cleaved caspase-9, and cleaved-PARP. In conclusion, it was confirmed that the PHE exhibited selective cytotoxicity toward MDA-MB-231, not toward MCF-7, and its cytotoxic activity is based on induction of apoptosis.

A Fluorogenic Assay: Analysis of Chemical Modification of Lysine and Arginine to Control Proteolytic Activity of Trypsin.

The chemical modification of amino acids plays an important role in the modulation of proteins or peptides and has useful applications in the activation and stabilization of enzymes, chemical biology, shotgun proteomics, and the production of peptide-based drugs. Although chemoselective modification of amino acids such as lysine and arginine via the insertion of respective chemical moieties as citraconic anhydride and phenyl glyoxal is important for achieving desired application objectives and has been extensively reported, the extent and chemoselectivity of the chemical modification of specific amino acids using specific chemical agents (blocking or modifying agents) has yet to be sufficiently clarified owing to a lack of suitable assay methodologies. In this study, we examined the utility of a fluorogenic assay method, based on a fluorogenic tripeptide substrate (FP-AA1-AA2-AA3) and the proteolytic enzyme trypsin, in determinations of the extent and chemoselectivity of the chemical modification of lysine or arginine. As substrates, we used two fluorogenic tripeptide probes, MeRho-Lys-Gly-Leu(Ac) (lysine-specific substrate) and MeRho-Arg-Gly-Leu(Ac) (arginine-specific substrate), which were designed, synthesized, and evaluated for chemoselective modification of specific amino acids (lysine and arginine) using the fluorogenic assay. The results are summarized in terms of half-maximal inhibitory concentrations (IC50) for the extent of modification and ratios of IC50 values (IC50arginine/IC50lysine and IC50lysine/IC50arginine) as a measure of the chemoselectivity of chemical modification for amino acids lysine and arginine. This novel fluorogenic assay was found to be rapid, precise, and reproducible for determinations of the extent and chemoselectivity of chemical modification.

Bisoprolol-based 18F-PET tracer: Synthesis and preliminary in vivo validation of ß1-blocker selectivity for ß1-adrenergic receptors in the heart.

The selectivity of a drug toward various isoforms of the target protein family is important in terms of toxicology. Typically, drug or candidate selectivity is assessed by in vitro assays, but in vivo investigations are currently lacking. Positron emission tomography (PET) allows the non-invasive determination of the in vivo distribution of a radiolabeled drug, which can provide in vivo data regarding drug selectivity. Since the discovery of propranolol, a non-selective ß-blocker inhibiting both ß1- and ß2-adrenoreceptors (ß-ARs), various selective ß1-blockers, including bisoprolol, have been developed to overcome disadvantages associated with ß2-AR inhibition. As a proof of concept, we performed an in vivo PET study to understand the selectivity and efficacy of bisoprolol as a selective ß-blocker toward ß1-AR, as the heart and peripheral smooth muscles demonstrate distinct populations of ß1- and ß2-ARs. Biodistribution of 18F-labeled bisoprolol (1, [18F]bisoprolol) showed the retention of its uptake in the heart compared with other ß-AR-rich organs at late time points post-injection. The competitive blocking assay using unlabeled bisoprolol exhibited no inhibition of [18F]bisoprolol uptake in any organ but exhibited significantly rapid loss of radioactivity between two different time points in ß1-AR-rich organs such as the heart and brain. Furthermore, the organ-to-blood ratio revealed the slow excretion and better accumulation of [18F]bisoprolol inside the heart. Collectively, the ex vivo biodistribution and blocking study presented insightful evidence to better comprehend the in vivo distribution pattern of bisoprolol as a selective inhibitor targeting ß1-ARs in the heart and provided the possibility of PET as an in vivo technique for evaluating drug selectivity.

Atraric Acid Exhibits Anti-Inflammatory Effect in Lipopolysaccharide-Stimulated RAW264.7 Cells and Mouse Models.

Lichens, composite organisms resulting from the symbiotic association between the fungi and algae, produce a variety of secondary metabolites that exhibit pharmacological activities. This study aimed to investigate the anti-inflammatory activities of the secondary metabolite atraric acid produced by Heterodermia hypoleuca. The results confirmed that atraric acid could regulate induced pro-inflammatory cytokine, nitric oxide, prostaglandin E2, induced nitric oxide synthase and cyclooxygenase-2 enzyme expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Meanwhile, atraric acid downregulated the expression of phosphorylated IκB, extracellular signal-regulated kinases (ERK) and nuclear factor kappa B (NFκB) signaling pathway to exhibit anti-inflammatory effects in LPS-stimulated RAW264.7 cells. Based on these results, the anti-inflammatory effect of atraric acid during LPS-induced endotoxin shock in a mouse model was confirmed. In the atraric acid treated-group, cytokine production was decreased in the peritoneum and serum, and each organ damaged by LPS-stimulation was recovered. These results indicate that atraric acid has an anti-inflammatory effect, which may be the underlying molecular mechanism involved in the inactivation of the ERK/NFκB signaling pathway, demonstrating its potential therapeutic value for treating inflammatory diseases.

Synthesis of imatinib, a tyrosine kinase inhibitor, labeled with carbon-14.

Imatinib (Gleevec) is a multiple tyrosine kinase inhibitor that decreases the activity of the fusion oncogene called BCR-ABL (breakpoint cluster region protein-Abelson murine leukemia viral oncogene homolog) and is clinically used for the treatment of chronic myelogenous leukemia and acute lymphocytic leukemia. Small molecule drugs, such as imatinib, can bind to several cellular proteins including the target proteins in the cells, inducing undesirable effects along with the effects against the disease. In this study, we report the synthetic optimization for 14 C-labeling and radiosynthesis of [14 C]imatinib to analyze binding with cellular proteins using accelerator mass spectroscopy. 14 C-labeling of imatinib was performed by the synthesis of 14 C-labeld 2-aminopyrimidine intermediate using [14 C]guanidine·HCl, which includes an in situ reduction of an inseparable byproduct for easy purification by HPLC, followed by a cross-coupling reaction with aryl bromide precursor. The radiosynthesis of [14 C]imatinib (specific activity, 631 MBq/mmol; radiochemical purity, 99.6%) was achieved in six steps with a total chemical yield of 29.2%.

Asymmetric and Reduced Xanthene Fluorophores: Synthesis, Photochemical Properties, and Application to Activatable Fluorescent Probes for Detection of Nitroreductase.

Xanthene fluorophores, including fluorescein, rhodol, and rhodamines, are representative classes of fluorescent probes that have been applied in the detection and visualization of biomolecules. "Turn on" activatable fluorescent probes, that can be turned on in response to enzymatic reactions, have been developed and prepared to reduce the high background signal of "always-on" fluorescent probes. However, the development of activity-based fluorescent probes for biological applications, using simple xanthene dyes, is hampered by their inefficient synthetic methods and the difficulty of chemical modifications. We have, thus, developed a highly efficient, versatile synthetic route to developing chemically more stable reduced xanthene fluorophores, based on fluorescein, rhodol, and rhodamine via continuous Pd-catalyzed cross-coupling. Their fluorescent nature was evaluated by monitoring fluorescence with variation in the concentration, pH, and solvent. As an application to activatable fluorescent probe, nitroreductase (NTR)-responsive fluorescent probes were also developed using the reduced xanthene fluorophores, and their fluorogenic properties were evaluated.

Radiosynthesis, biological evaluation and preliminary microPET study of 18F-labeled 5-resorcinolic triazolone derivative based on ganetespib targeting HSP90.

Heat-shock protein 90 (HSP90) is a molecular chaperone that activates oncogenic transformation in several solid tumors, including lung and breast cancers. Ganetespib, a most promising candidate among several HSP90 inhibitors under clinical trials, has entered Phase III clinical trials for cancer therapy. Despite numerous evidences validating HSP90 as a target of anticancer, there are few studies on PET agents targeting oncogenic HSP90. In this study, we synthesized and biologically evaluated a novel 18F-labeled 5-resorcinolic triazolone derivative (1, [18F]PTP-Ganetespib) based on ganetespib. [18F]PTP-Ganetespib was labeled by click chemistry of Ganetespib-PEG-Alkyne (10) and [18F]PEG-N3 (11) with 37.3 ±â€¯5.11% of radiochemical yield and 99.7 ±â€¯0.09% of radiochemical purity. [18F]PTP-Ganetespib showed proper LogP (0.96 ±â€¯0.06) and good stability in human serum over 97% for 2 h. [18F]PTP-Ganetespib showed high uptakes in breast cancer cells containing triple negative breast cancer (TNBC) MDA-MB-231 and Her2-negative MCF-7 cells, which are target breast cancer cell lines of HSP90 inhibitor, ganetespib, as an anticancer. Blocking of HSP90 by the pretreatment of ganetespib exhibited significantly decreased accumulation of [18F]PTP-Ganetespib in MDA-MB-231 and MCF-7 cells, indicating the specific binding of [18F]PTP-Ganetespib to MDA-MB-231 and MCF-7 cells with high HSP90 expression. In the biodistribution and microPET imaging studies, the initial uptake into tumor was weaker than in other thoracic and abdominal organs, but [18F]PTP-Ganetespib was retained relatively longer in the tumor than other organs. The uptake of [18F]PTP-Ganetespib in tumors was not sufficient for further development as a tumor-specific PET imaging agent by itself, but this preliminary PET imaging study of [18F]PTP-Ganetespib can be basis for developing new PET imaging agents based on HSP90 inhibitor, ganetespib.

Acetazolamide-based [18F]-PET tracer: In vivo validation of carbonic anhydrase IX as a sole target for imaging of CA-IX expressing hypoxic solid tumors.

Carbonic anhydrase IX is overexpressed in many solid tumors including hypoxic tumors and is a potential target for cancer therapy and diagnosis. Reported imaging agents targeting CA-IX are successful mostly in clear cell renal carcinoma as SKRC-52 and no candidate was approved yet in clinical trials for imaging of CA-IX. To validate CA-IX as a valid target for imaging of hypoxic tumor, we designed and synthesized novel [18F]-PET tracer (1) based on acetazolamide which is one of the well-known CA-IX inhibitors and performed imaging study in CA-IX expressing hypoxic tumor model as 4T1 and HT-29 in vivo models other than SKRC-52. [18F]-acetazolamide (1) was found to be insufficient for the specific accumulation in CA-IX expressing tumor. This study might be useful to understand in vivo behavior of acetazolamide PET tracer and can contribute to the development of successful PET imaging agents targeting CA-IX in future. Additional study is needed to understand the mechanism of poor targeting of CA-IX, as if CA-IX is not reliable as a sole target for imaging of CA-IX expressing hypoxic solid tumors.

Identification of a novel circadian clock modulator controlling BMAL1 expression through a ROR/REV-ERB-response element-dependent mechanism.

Circadian rhythms, biological oscillations with a period of about 24 h, are maintained by an innate genetically determined time-keeping system called the molecular circadian clockwork. Despite the physiological and clinical importance of the circadian clock, development of small molecule modulators targeting the core clock machinery has only recently been initiated. BMAL1, a core clock gene, is controlled by a ROR/REV-ERB-response element (RORE)-dependent mechanism, which plays an important role in stabilizing the period of the molecular circadian clock. Therefore, we aimed to identify a novel small molecule modulator that regulates Bmal1 gene expression in RORE-dependency, thereby influencing the molecular feedback loop of the circadian clock. For this purpose, we carried out a cell-based screen of more than 1000 drug-like compounds, using a luciferase reporter driven by the proximal region of the mouse Bmal1 promoter. One compound, designated KK-S6, repressed the RORE-dependent transcriptional activity of the mBmal1 promoter and reduced endogenous BMAL1 protein expression. More importantly, KK-S6 significantly altered the amplitude of circadian oscillations of Bmal1 and Per2 promoter activities in a dose-dependent manner, but barely affected the period length. KK-S6 effectively decreased mRNA expression of metabolic genes acting downstream of REV-ERBα, Pai-1 and Citrate synthase, that contain RORE cis-element in their promoter. KK-S6 likely acts in a RORE-dependent manner by reinforcing the REV-ERBα activity, though not by the same mechanism as known REV-ERB agonists. In conclusion, the present study demonstrates that KK-S6 functions as a novel modulator of the amplitude of molecular circadian rhythms by influencing RORE-mediated BMAL1 expression.

Identification of small molecule inhibitors of the STAT3 signaling pathway: Insights into their structural features and mode of action.

A series of novel STAT3 inhibitors consisting of Michael acceptor has been identified through assays of the focused in-house library. In addition, their mode of action and structural feature responsible for the STAT3 inhibition were investigated. In particular, analog 6 revealed promising STAT3 inhibitory activity in HeLa cell lines. The analog also exhibited selective inhibition of STAT3 phosphorylation without affecting STAT1 phosphorylation and cytostatic effect in human breast epithelial cells (MCF10A-ras), which supports cancer cell-specific inhibitory properties.

Total synthesis of (-)-deguelin via an iterative pyran-ring formation strategy.

Enantioselective synthesis of (-)-deguelin was accomplished via an iterative pyran-ring formation approach. The key features involve the anionic addition of a chromene unit to aryloxy alkyl aldehyde for the double cyclization precursor and iterative pyran ring formation by Pd-catalyzed O-arylation and C-arylation, respectively.

Discovery of structurally simplified analogs of colchicine as an immunosuppressant.

We have discovered a new class of colchicine-derived therapeutic agents for immune diseases including rejection of organ-transplantation and autoimmune disease. Compound 2, which had been developed to overcome poor pharmacokinetic properties of compound 1, a first-generation colchicine analog, turned out to show toxicity such as intestinal toxicity and loss of weight during in vivo tests. The deletion of 7-carboxamide group and middle ring-truncation in colchicine allowed us to have structurally simplified analogs with strong immunosuppressive activity. Herein, we report non-alkaloid tricyclic compound 7 and 12 as immunosuppressants which exhibited a strong immunosuppressive in vivo efficacy on the T-dependent antibody response, the Zymosan A-induced arthritis model and the Carrageenan-induced edema model. Compound 7 and 12 revealed less toxicity than the previous lead compound 2, and their minimum lethal doses (MLD) were proved to exceed 100 mg/kg.

Hypoxia-mediated retinal neovascularization and vascular leakage in diabetic retina is suppressed by HIF-1α destabilization by SH-1242 and SH-1280, novel hsp90 inhibitors.

In diabetic retinopathy (DR), visual deterioration is related with retinal neovascularization and vascular hyperpermeability. Anti-vascular endothelial growth factor (VEGF) agents are currently utilized to suppress retinal neovascularization and macular edema (ME); however, there are still concerns on the widespread use of them because VEGF is a trophic factor for neuronal and endothelial cells in the retina. As an alternative treatment strategy for DR, it is logical to address hypoxia-related molecules to treat DR because the retina is in relative hypoxia as DR progresses. In this study, we demonstrate that destabilization of hypoxia-inducible factor-1α (HIF-1α) by SH-1242 and SH-1280, novel heat shock protein 90 (hsp90) inhibitors, leads to suppression of hypoxia-mediated retinal neovascularization and vascular leakage in diabetic retina. In vitro experiments showed that these inhibitors inhibited hypoxia-induced upregulation of target genes of HIF-1α and further secretion of VEGF. Furthermore, these inhibitors effectively suppressed expression of target genes of HIF-1α including vegfa in the retina of oxygen-induced retinopathy (OIR) mice. Interestingly, despite hsp90 inhibition, these inhibitors do not induce definite toxicity at the level of gene expression, cellular viability, and histologic integrity. We suggest that SH-1242 and SH-1280 can be utilized in the treatment of DR, as an alternative treatment of direct VEGF inhibition. Key message: SH-1242 and SH-1280 are novel hsp90 inhibitors similar to deguelin. HIF-1α destabilization by hsp90 inhibition leads to anti-angiogenic effects. Despite hsp90 inhibition, both inhibitors do not induce definite toxicity. HIF-1α modulation can be a safer therapeutic option than direct VEGF inhibition.